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Volume 105-B, Issue SUPP_2 February 2023 The New Zealand Orthopaedic Association and the Australian Orthopaedic Association (NZOA AOA) Combined Annual Scientific Meeting, Christchurch, New Zealand, 31 October – 3 November 2022. Part 1 of 2.

A. Sundaram G. Perianayagam A. Hong J. Mar H. Lo A. Lawless R.L. Carey Smith

The Australia and New Zealand Sarcoma Association established the Sarcoma Guidelines Working Party to develop national guidelines for the management of Sarcoma. We asked whether surgery at a specialised centre improves outcomes. A systematic review was performed of all available evidence pertaining to paediatric or adult patients treated for bone or soft tissue sarcoma at a specialised centre compared with non-specialised centres. Outcomes assessed included local control, limb salvage rate, 30-day and 90-day surgical mortality, and overall survival.

Definitive surgical management at a specialised sarcoma centre improves local control as defined by margin negative surgery, local or locoregional recurrence, and local recurrence free survival. Limb conservation rates are higher at specialised centres, due in part to the depth of surgical experience and immediate availability of multidisciplinary and multimodal therapy. A statistically significant correlation did not exist for 30-day and 90-day mortality between specialised centres and non-specialised centres. The literature is consistent with improved survival when definitive surgical treatment is performed at a specialised sarcoma centre.

Evidence-based recommendation: Patients with suspected sarcoma to be referred to a specialised sarcoma centre for surgical management to reduce the risk of local recurrence, surgical complication, and to improve limb conservation and survival.

Practice point: Patients with suspected sarcoma should be referred to a specialised sarcoma centre early for management including planned biopsy.

A. Sundaram R.L. Carey Smith

Proximal femoral focal deficiency is a congenital disorder of malformation of the proximal femur and/or the acetabulum. Patients present with limb length discrepancy and clinical features along a spectrum of severity. As these patients progress through to skeletal maturity and on to adulthood, altered biomechanical demands lead to progression of arthropathy in any joint within the lower limb. Abnormal anatomy presents a challenge to surgeons and conventional approaches and implants may not necessarily be applicable.

We present a case of a 62-year-old lady with unilateral proximal femoral focal deficiency (suspected Aitken Class A) who ambulated with an equinus prosthesis for her entire life. She presented with ipsilateral knee pain and instability due to knee arthritis but could not tolerate a total knee arthroplasty due to poor quadriceps control.

A custom osteointegration prosthesis was inserted with a view to converting to the proximal segment to a total hip replacement if required. The patient went on to develop ipsilateral symptomatic hip arthritis but altered acetabular anatomy required a custom tri-flange component (Ossis, Christchurch, New Zealand) and a custom proximal femoral component to link with the existing osseointegration component (Osseointegration Group of Australia, Sydney, Australia) were designed and implanted.

The 18 month follow up of the custom hip components showed that the patient had Oxford hip scores that were markedly improved from pre-operatively. Knee joint heights were successfully restored to equal when the patient's prosthesis was attached. The patient describes feeling like “a normal person”, walks unaided for short distances and can ambulate longer distances with crutches.

Advances in design and manufacture of implants have empowered surgeons to offer life improving treatments to patients with challenging anatomy. Using a custom acetabular tri-flange and osseointegration components is one possible solution to address symptomatic ipsilateral hip and knee arthropathy in the context of PFFD in adulthood.

A. Sundaram J. Woods L. Clifton V. Alt R.H. Clark R.L. Carey Smith

Complex acetabular reconstruction for oncology and bone loss are challenging for surgeons due to their often hostile biological and mechanical environments. Titrating concentrations of silver ions on implants and alternative modes of delivery allow surgeons to exploit anti-infective properties without compromising bone on growth and thus providing a long-term stable fixation. We present a case series of 12 custom acetabular tri-flange and custom hemipelvis reconstructions (Ossis, Christchurch, New Zealand), with an ultrathin plasma coating of silver particles embedded between layers of siloxane (BioGate HyProtect™, Nuremberg, Germany).

At the time of reporting no implant has been revised and no patient has required a hospital admission or debridement for a deep surgical site infection. Routine follow up x-rays were reviewed and found 2 cases with loosening, both at their respective anterior fixation. Radiographs of both cases show remodelling at the ilium indicative of stable fixation posteriorly. Both patients remain asymptomatic. 3 patients were readmitted for dislocations, 1 of whom had 5 dislocations within 3 weeks post-operatively and was immobilised in an abduction brace to address a lack of muscle tone and has not had a revision of their components.

Utilising navigation with meticulous implant design and construction; augmented with an ultrathin plasma coating of silver particles embedded between layers of siloxane with controlled and long-term generation of silver ion diffusion has led to outstanding outcomes in this series of 12 custom acetabular and hemipelvis reconstructions. No patients were revised for infection and no patients show signs of failure of bone on growth and incorporation. Hip instability remains a problem in these challenging mechanical environments and we continue to reassess our approach to this multifaceted problem.

A. Sundaram E. Hockley T. Hardy R.L. Carey Smith

Rates of prosthetic joint infection in megaprostheses are high. The application of silver ion coating to implants serves as a deterrent to infection and biofilm formation.

A retrospective review was performed of all silver-coated MUTARS endoprosthetic reconstructions (SC-EPR) by a single Orthopaedic Oncology Surgeon. We examined the rate of component revision due to infection and the rate of infection successfully treated with antibiotic therapy. We reviewed overall revision rates, sub-categorised into the Henderson groupings for endoprosthesis modes of failure (Type 1 soft tissue failure, Type 2 aseptic loosening, Type 3 Structural failure, Type 4 Infection, Type 5 tumour progression).

283 silver-coated MUTARS endoprosthetic reconstructions were performed for 229 patients from October 2012 to July 2022. The average age at time of surgery was 58.9 years and 53% of our cohort were males. 154 (71.3%) patients underwent SC-EPR for oncological reconstruction and 32 (14.8%) for reconstruction for bone loss following prosthetic joint infection(s). Proximal femur SC-EPR (82) and distal femur (90) were the most common procedures. This cohort had an overall revision rate of 21.2% (60/283 cases). Component revisions were most commonly due to Type 4 infection (19 cases), Type 2 aseptic loosening/culture negative disease (15 cases), and Type 1 dislocation/soft tissue (12 cases).

Component revision rate for infection was 6.7% (19 cases). 15 underwent exchange of implants and 4 underwent transfemoral amputation due to recalcitrant infection and failure of soft tissue coverage. This equates to a limb salvage rate of 98.3%. The most common causative organisms remain staphylococcus species (47%) and polymicrobial infections (40%).

We expand on the existing literature advocating for the use of silver-coated endoprosthetic reconstructions. We provide insights from the vast experience of a single surgeon when addressing patients with oncological and bone loss-related complex reconstruction problems.

A.A. Badurudeen N. Mathai D. Altaf W. Mohamed M. Deglurkar

The aim of this study is to analyse the radiological outcomes and predictors of avascular necrosis following 2-hole DHS in Garden I and II neck of femur fractures in patients more than 60 years with a minimum follow up of one year.

We retrospectively reviewed 51 consecutive patients aged more than 60 years who underwent DHS fixation for Garden I and II fractures. Demographics, fracture classification, time to surgery, pre-operative AMTS, preoperative posterior tilt angle, quality of reduction, pre and post-operative haemoglobin(hb), creatinine and comorbidities were analysed for correlation with AVN using Chi-Square test, Independent Sample and paired t test.

There were 40 (78.4%) females and the mean age of the cohort was 77 years. 28 and 23 were Garden I and II NOF fractures respectively. Union was observed in all our patients except one(kappa =1). 12/51(23.5%) developed AVN of the femoral head. Statistically significant higher incidence of AVN was noted in patients with a pre-op tilt angle > 200 (p = 0.006). The mean drop in Hb was higher in patients who developed AVN (21.5 g/L) versus the non-AVN group (15.9 g/L) (p = 0.001). There was no difference in AVN rates with respect to laterality, mean time to surgery, pre-op AMTS and Charlson comorbidity index. 4/52 (7.6%) had re-operations (one hardware prominence, two conversions to arthroplasty, one fixation failure during the immediate post-op period). The 30-day and one year mortality rates were 1.9 % and 11.7 % respectively.

2-hole DHS fixation in undisplaced NOF fractures has excellent union rates. A pre-operative posterior tilt angle of >200 and a greater difference in pre and post operative haemoglobin were found to correlate positively with the progression to AVN . No correlation was observed between AVN and time to surgery, laterality, quality of reduction and comorbidities.

A.M. Lawless J. Ebert P. Edwards R. Aujla M. Finsterwald S. Dalgleish S. Malik R. Raymond U. Giwnewer A. Simpson M. Grant T. Leys P.A. D'Alessandro

Hamstring grafts have been associated with reduced strength, donor site pain and muscle strains following Anterior Cruciate Ligament Reconstruction (ACLR). Traditional graft fixation methods required both semitendinosus and gracilis tendons to achieve a graft of sufficient length and diameter, but newer techniques allow for shorter, broad single tendon grafts.

This study seeks to compare the outcomes between Single Tendon (ST) and Dual Tendon (DT) ACLR, given there is no prospective randomised controlled trial (RCT) in the literature comparing outcomes between these options.

In this ongoing RCT: (ANZ Clinical Trials Registry ACTRN126200000927921) patients were recruited and randomised into either ST or DT groups. All anaesthetic and surgical techniques were uniform aside from graft technique and tibial fixation. 13 patients were excluded at surgery as their ST graft did not achieve a minimum 8mm diameter. 70 patients (34 ST, 36DT) have been assessed at 6 months, using PROMS including IKDC2000, Lysholm and Modified Cincinnati Knee, visual analog scale for pain frequency (VAS-F) and severity (VAS-S), dedicated donor site morbidity score, KT-1000 assessment, and isokinetic strength.

Graft diameters were significantly lesser in the ST group compared to the DT group (8.44mm/9.11mm mean difference [MD],-0.67mm; P<0.001). There was a significant and moderate effect in lower donor site morbidity in the ST group compared to the DT group (effect size [ES], 0.649; P = .01). No differences between groups were observed for knee laxity in the ACLR limb (P=0.362) or any of the patient-reported outcome measures (P>0.05). Between-group differences were observed for hamstrings strength LSI favouring the ST group, though these were small-to-moderate and non-significant (ES, 0.351; P = .147).

ST (versus DT) harvest results in significantly less donor site morbidity and this is the first prospective RCT to determine this. There were no differences between ST and DT hamstring ACLR were observed in PROMs, knee laxity and hamstring strength. Younger female patients tend to have inadequate single tendon size to produce a graft of sufficient diameter, and alternative techniques should be considered. Further endpoints include radiological analysis, longer term donor site morbidity, revision rates and return to sport and will continue to be presented in the future.

A. Brennan C. Doran J. Cashman

As Total Hip Replacement (THR) rates increase healthcare providers have sought to reduce costs, while at the same time improving patient safety and satisfaction. Up to 50% of patients may be appropriate for Day Case THR, and in appropriately selected patients’ studies show no increase in complication rate while affording a significant cost saving and maintaining a high rate of patient satisfaction.

Despite the potential benefits, levels of adoption of Day Case THR vary. A common cause for this is the perception that doing so would require the adoption of new surgical techniques, implants, or theatre equipment. We report on a Day-Case THR pathway in centres with an established and well-functioning Enhanced Recovery pathway, utilising the posterior approach and standard implants and positioning.

We prospectively collected the data on consecutive THRs performed by a single surgeon between June 2018 and July 2021. A standardised anaesthetic regimen using short acting spinal was used. Surgical data included approach, implants, operative time, and estimated blood loss. Outcome data included time of discharge from hospital, post operative complications, readmissions, and unscheduled health service attendance.

Data was gathered on 120 consecutive DCTHRs in 114 patients. 93% of patients were successfully discharged on the day of surgery. Four patients required re-admission: one infection treated with DAIR, one dislocation, one wound ooze admitted for a day of monitoring, one gastric ulcer. One patient had a short ED attendance for hypertension.

Our incidence of infection, dislocation and wound problems were similar to those seen in inpatient THR. Out data show that the widely used posterior approach using standard positioning and implants can be used effectively in a Day Case THR pathway, with no increase in failure of same-day discharge or re-admission to hospital.

A. Brennan J. Blackburn J. Thompson J. Field

Thumb carpometacarpal joint (CMCJ) arthritis is a common and debilitating condition. The mainstay of surgical management is Trapeziectomy. Concerns about possible functional implications of collapse of the metacarpal into the arthroplasty space as well as the potential for scaphometacarpal led to the development of techniques to try and prevent this. The purpose of this study was to investigate if there were any significant differences in the long-term outcomes of patients who participated in a randomized trial of trapeziectomy alone compared with trapeziectomy with ligament reconstruction and tendon interposition (LRTI).

Sixty-five patients participated in our original trial, the 1 year findings of which were published in 2007. These patients were invited for a follow-up visit at a mean of 17 years (range 15–20) postoperatively. Twenty-eight patients attended, who had 34 operations, 14 trapeziectomy alone and 20 with LRTI. Patients were asked to complete a visual analogue scale (VAS) for satisfaction with the outcome of their procedure, rated on a scale from 0 (most dissatisfied) to 100 (most satisfied). They also completed the short version of the Disabilities of the Arm, Shoulder and Hand Score (QuickDASH) at their appointment. They underwent a functional assessment with a hand therapist and had a radiograph of the thumb.

There were no statistically significant differences between the two groups in terms of satisfaction with surgery or functional outcomes, with most measurements showing minimal or no differences in means between the two groups. There was no difference in the space between the metacarpal and scaphoid on radiograph. Radial abduction was the only parameter that was significantly greater in the patients with simple trapeziectomy (median 79°) compared with trapeziectomy with LRTI (median 71°) (p = 0.04). Even at 17 years there is no significant benefit of LRTI over trapeziectomy alone for thumb carpometacarpal joint osteoarthritis.

A.J. Talia N. Furness S.M. Liew

Complications are an inevitable part of orthopaedic surgery, how one defines complications can have an impact on the ability to learn from them. A group of general surgeons headed by Clavien and Dindo et al.1 have previously published their classification system for surgical complications based on the type of therapy required to correct the complication.

Our aim was to evaluate a modification of this classification system and its use over a 12-month period at our institution via our departmental audits, our hypothesis being that this would direct appropriate discussion around our complications and hence learning and institutional change.

A modified Clavien-Dindo Classification was prospectively applied to all complications recorded in the Orthopaedic departmental quarterly audits at our institution for a 12-month period (4 audits). The audit discussion was recorded and analysed and compared with the quarterly complication audits for the preceding 12-month period.

The modified Clavien-Dindo classification for surgical complications was applicable and reproducible to Orthopaedic complications in our level 1 trauma centre. It is a transparent system, objective in its interpretation and avoids the tendency to down-grade serious complications. It was easy to apply and directed discussion appropriately at our quarterly audit meetings on complications where there was a preventable outcome or important learning point. In particular modifications to VTE and Death classes allowed the unit to focus discussion on cases where complication was preventable or unexpected.

The modified Clavien-Dindo classification system is an easy to use and reproducible classification system for Orthopaedic complications in our unit it directed audit discussion towards cases where complications were preventable or had a learning point.

A.J. Talia S. Clare S.M. Liew E.R. Edwards

The Victorian state government introduced a trial electronic scooter sharing scheme on 1st February 2022 in inner city Melbourne. Despite epidemiological data from other jurisdictions that show these devices are associated with significant trauma. This is a descriptive study from the largest trauma centre in Victoria demonstrating the “scope of the problem” after introduction of this government-approved, ride sharing scheme.

Retrospective case series. Our hospital orthopaedic department database was searched from 1/1/2021 to 30/6/22 to identify all presentations associated with electronic scooter trauma, the mechanism of injury and admission information was confirmed via chart review. Data collected included: mode of arrival, alcohol/drug involvement, hospital LOS, injury severity score, ICU admission, list of injuries, operations undertaken, surgical procedures, discharge destination, death.

In the 12 months prior to and 5 months since introduction of the ride share scheme, 43 patients were identified. 18 patients (42% of our cohort) presented in the 5 months since ride sharing was introduced, and 25 patients in the preceding 12 months.

58% were found to be alcohol or drug affected. All patients were admitted to hospital, 14% of which included ICU admission. 44% were polytrauma admissions. Median hospital length of stay was 2 days. The longest individual hospital stay was 69 days. No patients in this series died. There were 49 surgical procedures in 35 patients including neurosurgical, plastics and maxillofacial operations. Mean Injury Severity Score was 10.

Despite data demonstrating their danger in other jurisdictions, the Victorian state government approved a trial of an electronic scooter ride share scheme in inner Melbourne in February 2022. These devices are associated with a significant trauma burden and the rate has increased since the introduction of the ride-sharing scheme. This data may be combined with other hospital data and could be used to inform policy makers.

A.B. Boyle C.M. George S.B.M. MacLean

A larger radial tuberosity, and therefore a smaller radioulnar space, may cause mechanical impingement of the DBT predisposing to tear. We sought to investigate anatomic factors associated with partial DBT tears by retrospectively reviewing 3-T MRI scans of elbows with partial DBT tears and a normal elbow comparison group

3-T MRI scans of elbows with partial DBT tears and elbows with no known pathology were reviewed retrospectively by two independent observers. Basic demographic data were collected and measurements of radial tuberosity length, radial tuberosity thickness, radio-ulnar space, and radial tuberosity-ulnar space were made using simultaneous tracker lines and a standardised technique. The presence or absence of enthesophytes and the presence of a single or double DBT were noted.

26 3-T MRI scans of 26 elbows with partial DBT tears and 30 3-T MRI scans of 30 elbows without pathology were included. Basic demographic data was comparable between the two groups. The tear group showed statistically significant larger mean measurements for radial tuberosity length (24.3mm vs 21.3mm, p=0.002), and radial tuberosity thickness (5.5mm vs 3.7mm, p=<0.0001. The tear group also showed statistically significant smaller measurements for radio-ulnar space (8.2mm vs 10.0mm, p=0.010), and radial tuberosity-ulnar space (7.2mm vs 9.1mm, p=0.013). There was a statistically significant positive correlation between partial DBT tears and presence of enthesophytes (p=0.007) as well as between partial DBT tears and having two discrete DBTs rather than a single or interdigitating tendon (p=<0.0001).

Larger radial tuberosities, and smaller radio-ulnar and radial tuberosity-ulnar spaces are associated with partial DBT tears. This may be due to chronic impingement, tendon delamination and consequent weakness which ultimately leads to tears. Enthesophytes may be associated with tears for the same reason. Having two discrete DBTs that do not interdigitate prior to insertion is also associated with partial tears.

A.B. Boyle M. Zhu C. Frampton V. Poutawera A. Vane

Multiple joint registries have reported better implant survival for patients aged >75 years undergoing total hip arthroplasty (THA) with cemented implant combinations when compared to hybrid or uncemented implant combinations. However, there is considerable variation within these broad implant categories, and it has therefore been suggested that specific implant combinations should be compared. We analysed the most common contemporary uncemented (Corail/Pinnacle), hybrid (Exeter V40/Trident) and cemented (Exeter V40/Exeter X3) implant combinations in the New Zealand Joint Registry (NZJR) for patients aged >75 years.

All THAs performed using the selected implants in the NZJR for patients aged >75 years between 1999 and 2018 were included. Demographic data, implant type, and outcome data including implant survival, reason for revision, and post-operative Oxford Hip Scores were obtained from the NZJR, and detailed survival analyses were performed. Primary outcome was revision for any reason. Reason for revision, including femoral or acetabular failure, and time to revision were recorded.

5427 THAs were included. There were 1105 implantations in the uncemented implant combination group, 3040 in the hybrid implant combination group and 1282 in the cemented implant combination group. Patient reported outcomes were comparable across all groups. Revision rates were comparable between the cemented implant combination (0.31 revisions/100 component years) and the hybrid implant combination (0.40 revisions/100 component years) but were statistically significantly higher in the uncemented implant combination (0.80/100 component years). Femoral-sided revisions were significantly greater in the uncemented implant combination group.

The cemented implant and hybrid implant combinations provide equivalent survival and functional outcomes in patients aged over 75 years. Caution is advised if considering use of the uncemented implant combination in this age group, predominantly due to a higher risk of femoral sided revisions. The authors recommend comparison of individual implants rather than broad categories of implants.

A. Giurea G. Fraberger P. Kolbitsch R. Lass B. Kubista R. Windhager

Ten to twenty percent of patients are dissatisfied with the clinical result after total knee arthroplasty (TKA). Aim of this study was to investigate the impact of personality traits on patient satisfaction and subjective outcome of TKA.

We investigated 80 patients with 86 computer navigated TKAs (Emotion®, B Braun Aesculap) and asked for patient satisfaction. We divided patients into two groups (satisfied or dissatisfied). 12 personality traits were tested by an independent psychologist, using the Freiburg Personality Inventory (FPI-R). Postoperative examination included Knee Society Score (KSS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the Visual Analogue Scale (VAS). Radiologic investigation was done in all patients.

84% of our patients were satisfied, while 16% were not satisfied with clinical outcome. The FPI-R showed statistically significant influence of four personality traits on patient satisfaction: life satisfaction (ρ = 0.006), performance orientation (ρ =0.015), somatic distress (ρ = 0.001), and emotional stability (ρ = 0.002). All clinical scores (VAS, WOMAC, and KSS) showed significant better results in the satisfied patient group. Radiological examination showed optimal alignment of all TKAs. There were no complications requiring revision surgery in both groups.

The results of our study show that personality traits may influence patient satisfaction and clinical outcome after TKA. Thus, patients personality traits may be a useful predictive factor for postoperative satisfaction after TKA.

K. Vertesich K. Staats Ch. Böhler R. Koza R. Lass A. Giurea

The use of rotating hinge (RH) prostheses for severe primary as well as revision arthroplasty is widely established. Aim of this study was to investigate long term results of a new RH prosthesis (EnduRo®, B Braun, Germany), which uses carbon-fiber reinforced poly-ether-ether-ketone (CFR PEEK) as a new bearing material, first time used in knee arthroplasty.

Fifty-six consecutive patients, who received the EnduRo® RH prosthesis were included in this prospective study: 21 patients (37.5%) received the prosthesis as a primary total knee arthroplasty (TKA) and 35 patients (62.5%) underwent revision total knee arthroplasties (rTKA). Clinical and radiographic examinations were performed preoperatively as well as postoperatively after 3 and 12 months and annually thereafter. Min. Follow up was 7 and mean follow up 9,3 years. Clinical examination included Knee Society Score (KSS), Western Ontario and McMaster Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), and range of motion (ROM). Competing risk analysis was assessed for survival with respect to indication and failure mode.

KSS, WOMAC, OKS, and ROM significantly improved from the preoperative to the follow up investigations (p < 0.0001). There was no difference in clinical outcome between the primary and the revision group. The overall cumulative incidence for revision for any reason was 23.6% and the cumulative incidence for complications associated with failure of the prothesis was 5.6% at 7 years, respectively. Complications occurred more frequently in the revision group (p = 0.002).

The evaluated RH prosthesis provided reliable and durable results with a minimum follow-up of 7 years. Prosthesis survival was successful considering the complexity of cases. The use of this RH system in primary patients showed high survival rates. Long-term functional and clinical results proved to be satisfying in both revision and primary cases. No adverse events were associated with the new bearing material CFR-PEEK.

A. Manobianco O. Enketan R. Grass

Tibiotalocalcaneal arthrodesis (TTCA) is a salvage procedure to functionally block the ankle and subtalar joints to treat severe ankle and hindfoot disease. Complication rates range between 20-40%, with below-knee amputation rate 1.5-19%. The heterogeneous patient cohort and indication(s) for surgery make post-operative outcomes difficult to predict. Consulting patients about potential pain and functional outcomes is difficult. When researching this area commonly, PROM data is used, less frequently functional objective measures like the 2-minute-walk-test (2MWT) are used. The aim was to compare the PROMs and objective outcomes between patients who underwent TTCA and BKA.

Fifty-two patients underwent a TTCA using an intramedullary hindfoot nail. Indications for TTCA, post-traumatic OA, failed arthrodesis and malalignment. These patients were compared to 11 patients who underwent unilateral below knee amputation (BKA) due to trauma. Outcomes measures PROMs AOFAS ankle hindfoot scale and Shor-Form 36 (SF-36). Objective measures; 2MWT, Timed-up-and-go (TUG).

Mean age TTCA 55.9, BKA 46.4. Average follow-up time 53 months. TTCA group had average 6.3 operations prior to arthrodesis (range 1-23). Of the TTCA group two ankles did not unite (7%), all complication rate 35%, 18% reported no pain. A significant negative correlation was demonstrated between the clinical outcome and the number of surgeries prior to the TTCA. TUG and 2MWT had significantly (p<0.05) better outcomes for the BKA group compared to TTCA. SF-36 BKA patients scored higher than the TTCA patients on physical functioning (p<0.01) and mental health (p<0.05) subscales as well as the mental component score (p<0.05).

This study gives clinicians evidence about the natural history of hindfoot arthrodesis and functional outcomes from BKA. Hopefully this study will improve evidence to help patients and surgeons make decisions about expected surgical outcomes from TTCA and BKA procedures.

A. Gibson M. Guest T. Taylor D. Gwynne Jones

The purpose of this study was to determine whether there have been changes in the complexity of femoral fragility fractures presenting to our Dunedin Orthopaedic Department, New Zealand, over a period of ten years.

Patients over the age of 60 presenting with femoral fragility fractures to Dunedin Hospital in 2009 −10 (335 fractures) were compared with respect to demographic data, incidence rates, fracture classification and treatment details to the period 2018-19 (311 fractures). Pathological and high velocity fractures were excluded.

The gender proportion and average age (83.1 vs 83.0 years) was unchanged. The overall incidence of femoral fractures in people over 60 years in our region fell by 27% (p<0.001). Intracapsular fractures (31 B1 and B2) fell by 29% (p=0.03) and stable trochanteric fractures by 56% (p<0.001). The incidence of unstable trochanteric fractures (31A2 and 31A3) increased by 84.5% from 3.5 to 6.4/10,000 over 60 years (p = 0.04). The proportion of trochanteric fractures treated with an intramedullary (IM) nail increased from 8% to 37% (p <0.001). Fewer intracapsular fractures were treated by internal fixation (p<0.001) and the rate of acute total hip joint replacements increased from 13 to 21% (p=0.07). The incidence of femoral shaft fractures did not change significantly with periprosthetic fractures comprising 70% in both cohorts.

While there has been little difference in the numbers there has been a decrease in the incidence of femoral fragility fractures likely due to the increasing use of bisphosphonates. However, the incidence of unstable trochanteric fractures is increasing. This has led to the increased use of IM nails which are increasingly used for stable fractures as well.

The increasing complexity of femoral fragility fractures is likely to have an impact on implant use, theatre time and cost.

A. Weber M. Dares

Percutaneous flexor tenotomy involves cutting the flexor digitorum tendons to correct claw toe deformity to treat apical pressure areas and prevent subsequent infection in patients with peripheral neuropathy. Performing this under ultrasound guidance provides reassurance of complete release of the tendon and increases procedural safety.

This study is a retrospective case series evaluating the effectiveness, safety, and patient satisfaction of performing percutaneous ultrasound-guided flexor tenotomy in an outpatient setting. People with loss of protective sensation, a digital flexion deformity, and an apical toe ulcer or pre-ulcerative lesion who presented to our institution between December 2019 and June 2022 were included in this study. Participants were followed-up at a minimum of 3 months. Time to ulcer healing, re-ulceration rate, patient satisfaction, and complications were recorded. An Australian cost analysis was performed comparing this procedure performed in rooms versus theatres.

There were 28 ulcers and 41 pre-ulcerative lesions. A total of 69 tenotomy procedures were performed on 38 patients across 52 episodes of care. The mean time to ulcer healing was 22.5 +/- 6.4 days. There were 2 cases of re-ulceration. 1 patient sustained a transfer lesion. There were four toes that went onto require amputation, all in the setting of pre-existing osteomyelitis. 94% of patients strongly agreed that they were satisfied with the outcome of the procedure. Costs saved were estimated to be $1426.

Flexor tenotomy is a minimally invasive procedure that can be performed in the outpatient setting, and therefore without delay to treatment, reducing risk of ulcer progression and need for subsequent amputation. This is the first study to report on flexor tenotomy under ultrasound-guidance.

Ultrasound-guided percutaneous flexor tenotomy is safe and effective, with high patient satisfaction and low recurrence rates. This performance in the outpatient setting ensures significant time and cost savings for both the practitioner and patient.

A.L. Foster W. Boot V. Stenger M. D'Este A. Jaiprakash R. Crawford M.A. Schuetz D. Eglin S. Zeiter R.G. Richards T.F. Moriarty

Local antimicrobial therapy is an integral aspect of treating orthopaedic device related infection (ODRI), which is conventionally administered via polymethylmethacrylate (PMMA) bone cement. PMMA, however, is limited by a suboptimal antibiotic release profile and a lack of biodegradability.

In this study, we compare the efficacy of PMMA versus an antibioticloaded hydrogel in a single- stage revision for chronic methicillin-resistant Staphylococcus aureus (MRSA) ODRI in

sheep. Antibiofilm activity of the antibiotic combination (gentamicin and vancomycin) was determined in vitro. Swiss alpine sheep underwent a single-stage revision of a tibial intramedullary nail with MRSA infection. Local gentamicin and vancomycin therapy was delivered via hydrogel or PMMA (n = 5 per group), in conjunction with systemic antibiotic therapy. In vivo observations included: local antibiotic tissue concentration, renal and liver function tests, and quantitative microbiology on tissues and hardware post-mortem.

There was a nonsignificant reduction in biofilm with an increasing antibiotic concentration in vitro (p = 0.12), confirming the antibiotic tolerance of the MRSA biofilm. In the in vivo study, four out of five sheep from each treatment group were culture negative. Antibiotic delivery via hydrogel resulted in 10–100 times greater local concentrations for the first 2–3 days compared with PMMA and were comparable thereafter. Systemic concentrations of gentamicin were minimal or undetectable in both groups, while renal and liver function tests were within normal limits.

This study shows that a single-stage revision with hydrogel or PMMA is equally effective, although the hydrogel offers certain practical benefits over PMMA, which make it an attractive proposition for clinical use.

A. Crombie J. Boyd R. Pozzi

Multiple studies have established an inverse relationship between ambient theatre temperatures and polymethyl methacrylate (PMMA) cement setting times. It is also known that allowing cement to equilibrate to ambient theatre temperatures restores expected setting characteristics. One overlooked entity is the transport and storage conditions of cement. This is important in tropical regions, where extreme temperature and humidity may cause rapid cement setting times, resulting in potentially significant intra-operative complications.

This study investigated the relationship between extreme transport and storage conditions of Antibiotic Simplex cement (Stryker), and the effect on setting times at Cairns Hospital, Far North Queensland, Australia.

Fifty units of cement were divided evenly into a control arm and four experimental arms. The experimental arms were designed to mimic potential transport and storage conditions. They included seven days of storage in a medication fridge, on the hospital loading dock, in a cane shed, and in a Toyota Landcruiser parked outdoors during January 2022. Humidity and temperature readings were recorded.

The samples in each group were evenly distributed to equilibrate to theatre conditions for 1 hour and 24 hours. Setting time was recorded when a no. 15 scalpel blade was unable to mark the surface.

All three ‘hot’ exposures setting times were significantly faster for both 1 hour (ρ=0.001) and 24 hours (ρ=0.024) equilibration times. The difference in setting times for the ‘cold’ exposure was not significant for either equilibration times (ρ=1).

To our knowledge, this is the first study investigating cement setting times in tropical climates. Further studies are required to address the effect of these conditions on biomechanical strength of PMMA cement. We conclude that extreme heat and humidity during transport and storage have a statistically significant effect on cement setting times.

A. McDonald C. Byrnes M. Boyle H. Crawford

Survival of sepsis has been documented worldwide, but little is documented about the long-term health outcomes of multifocal sepsis from acute musculoskeletal infection - the first study of its kind in New Zealand.

Children admitted to the Paediatric Intensive Care Unit (PICU) from 1st January 2002 to 31st December 2017 with a musculoskeletal focus of infection were identified from hospital coding data. Notes review from discharge to present day determined survival and morbidity. Present-day clinical assessment of the musculoskeletal and respiratory systems along with questionnaires on health-related quality of life, mental health and sleep were performed.

Seventy patients were studied. Seven children died acutely (five Pasifika and two Māori children) indicating 10% mortality. Long-term survival was favourable with no recorded deaths after discharge. Recurrence/chronic infection occurred in 23%, a mean of 1.1 year after discharge. Growth disturbance occurred in 18%, a mean of 3 years after discharge. The hip joint and proximal femur have the worst complications. Children under 2 years are most at risk of long-term disability. No patients had chronic respiratory illness beyond 90 days. Fifteen children had symptoms of acute neurological impairment, three of whom had permanent brain injury. Twenty-six survivors (41%) were assessed a mean of 8.2 years after discharge. Health-related quality of life scores were on par with normative data. Six patients and eight parents screened positive for moderate to severe post-traumatic stress disorder.

Paediatric multifocal musculoskeletal sepsis can result in complex illness with long hospital stay and multi-organ complications. Māori and Pasifika children, those under two and those involving the proximal femur/or hip are most at risk. Other outcomes are favourable with no evidence of chronic lung disease or poor quality of life. A period of rehabilitation for children with identified acquired brain injury should be part of discharge planning.

A. McDonald A. Maling M. Puttick

Instant messaging via WhatsApp is used within hospital teams. Group messaging can lead to efficient and non-hierarchical communication. Despite being end-to-end encrypted, WhatsApp is owned by Facebook, raising concerns regarding data security. The aims of this study were: 1) to record the prevalence of WhatsApp group instant messaging amongst clinical teams; 2) to ascertain clinician attitudes towards use of instant messaging, 3) to gauge clinicians’ awareness of best practice regarding mobile data protection and 4) to create a practical guideline based off available literature that can be used to by clinicians to improve data security practice.

Over a two-week period, clinical nurse specialists in the Auckland District Health Board Department of Orthopaedics retrospectively completed a blind audit of all messaging activity across the five teams WhatsApp group message threads, recording quantity of messages sent and the nature of the messages. Concurrently individuals in these WhatsApp groups completed an anonymous survey of their use of WhatsApp and their awareness of local data security policies and practice. A guideline adapted from available literature was created to compare current practice to recommended standards and subsequently adopted into local policy.

1360 messages were sent via WhatsApp in a two-week period. 384 (28%) of the messages contained patient identifiable data. Thirty-six photos were shared. Participants rated use of WhatsApp at 9.1/10 – extremely beneficial. Sixty-five per cent of clinicians reported they had not read or were unaware of the ADHB policies regarding mobile devices and information privacy and security.

WhatsApp use is widespread within the Orthopaedic department and is the preferred platform of communication with many perceived benefits. Data security is a risk and implementation of an appropriate guideline to assist clinicians in achieving best practice is crucial to ensure patient data remains protected.

A. Horn C. Cetner M. Laubscher H. Tootlah

Osteoarticular infections (OAI) are a common cause of morbidity in children, and as opposed to adults is usually caused by haematogenous spread. The bacteriology of OAI in children is not well described in the South African context, therefore this study was designed to determine the bacteriology of OAI in our population.

All patients that underwent surgery for the treatment of OAI over a 3-year period were identified and those with positive cultures where organisms were identified from tissue, pus, fluid or blood were included. Duplicate cultures from the same patient were excluded if the organism and antibiotic susceptibility profile was the same. Patients were categorised according to age and class of infection (Septic arthritis, acute osteomyelitis, fracture related infection, post-operative sepsis and chronic osteomyelitis) and organisms were stratified according to these categories.

We identified 132 organisms from 123 samples collected from 86 patients. Most cultured organisms were from children older than 3-years with acute haematogenous septic arthritis, osteomyelitis, or both. Methicillin sensitive Staphylococcus aureus accounted for 56% (74/132) of organisms cultured. There were no cases of MRSA. The Enterobacterales accounted for 17% (22/132) of organisms cultured, mostly in the fracture related and post-operative infection groups. Of these, 6 each were extended spectrum B-lactamase producers and AmpC producers. There were no carbapenemase producing Enterobacterales. Kingella kingae was not isolated in any patient.

Methicillin sensitive S. aureus is the most common infecting organism in paediatric OAI and an anti-staphylococcal penicillin such as cloxacillin or flucloxacillin is the most appropriate empiric treatment for haematogenous OAI in our environment. In fracture related or post-operative infections, Enterobacterales were more frequently cultured, and treatment should be guided by culture and susceptibility results.

A. Silva T. Walsh J. Gray S. Platt

Swelling following an ankle fracture is commonly believed to preclude surgical fixation, delaying operative treatment to allow the swelling to subside. This is in an attempt to achieve better soft tissue outcomes. We aim to identify whether pre-operative ankle swelling influences postoperative wound complications following ankle fracture surgery.

This is a prospective cohort study of 80 patients presenting to a tertiary referral centre with operatively managed malleolar ankle fractures.

Ankle swelling was measured visually and then quantitatively using the validated ‘Figure-of-eight’ technique. Follow-up was standardised at 2, 6, and 12 weeks post-operatively. Wound complications, patient co-morbidities, operative time, surgeon experience, and hospital stay duration were recorded.

The complication rate was 8.75% (n=7), with 1 deep infection requiring operative intervention and all others resolving with oral antibiotics and wound cares. There was no significant difference in wound complication rates associated with quantitative ankle swelling (p=0.755), visual assessment of ankle swelling (p=0.647), or time to operative intervention (p=0.270).

Increasing age (p=0.006) and female gender (p=0.049) had a significantly greater probability of wound complications. However, BMI, smoking status, level of the operating surgeon, and tourniquet time were not significantly different.

Visual assessment of ankle swelling had a poor to moderate correlation to ‘Figure-of-eight’ ankle swelling measurements ICC=0.507 (0.325- 0.653).

Neither ankle swelling nor time to surgery correlates with an increased risk of postoperative wound complication in surgically treated malleolar ankle fractures. Increasing patient age and female gender had a significantly greater probability of wound infection, irrespective of swelling. Visual assessment of ankle swelling is unreliable for quantifying true ankle swelling.

Operative intervention at any time after an ankle fracture, irrespective of swelling, is safe and showed no better or worse soft tissue outcomes than those delayed for swelling.

A.P. Truong C.J. Wall J. Stoney S.E. Graves M.F. Lorimer R.N. de Steiger

Obesity is a known risk factor for hip osteoarthritis. The aim of this study was to compare the incidence of obesity in Australians undergoing hip replacements (HR) for osteoarthritis to the general population.

A cohort study was conducted comparing data from the Australian Bureau of Statistics and the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from 2017-18. Body mass index (BMI) data for patients undergoing primary total hip replacement and resurfacing for osteoarthritis were obtained from the AOANJRR. The distribution of HR patients by BMI category was compared to the general population, in age and sex sub-groups.

During the study period, 32,495 primary HR were performed for osteoarthritis in Australia. Compared to the general population, there was a higher incidence of Class I, II, and III obesity in patients undergoing HR in both sexes aged 35 to 74 years old. Class III obese females and males undergoing HR were on average 6 to 7 years younger than their normal weight counterparts. Class III obese females and males aged 55-64 years old were 2.9 and 1.7 times more likely to undergo HR, respectively (p<0.001).

There is a strong association between increased BMI and relative risk of undergoing HR. Similar findings have been noted in the United States of America, Canada, United Kingdom, Sweden and Spain. A New Zealand Registry study and recent meta-analysis have also found a concerning trend of Class III obese patients undergoing HR at a younger age.

Obese Australians are at increased risk of undergoing HR at a younger age. A national approach to address the prevalence of obesity is needed.

A.P. Truong D. Perez-Prieto J. Byrnes J.C. Monllau C.J. Vertullo

While pre-soaking grafts in vancomycin has demonstrated to be effective in observational studies for anterior cruciate ligament reconstruction (ACLR) infection prevention, the economic benefit of the technique is uncertain. The primary aim of this study was to determine the cost-effectiveness of vancomycin pre-soaking during primary ACLR to prevent post-operative joint infections. The secondary aims of the study were to establish the breakeven cost-effectiveness threshold of the technique.

A Markov model was used to determine cost effectiveness and the incremental cost effectiveness ratio of additional vancomycin pre-soaking compared to intravenous antibiotic prophylaxis alone. A repeated meta-analysis of nine cohort studies (Level III evidence) was completed to determine the odds ratio of infection with vancomycin pre-soaking compared to intravenous antibiotics alone. Estimated costs and transitional probabilities for further surgery were obtained from the literature. Breakeven threshold analysis was performed.

The vancomycin soaking technique provides an expected cost saving of $600AUD per patient. There was an improvement in the quality-adjusted life years of 0.007 compared to intravenous antibiotic prophylaxis alone (4.297 versus 4.290). If the infection rate is below 0.023% with intravenous antibiotics alone or the additional intervention cost more than $1000AUD, the vancomycin wrap would no longer be cost-effective.

For $30AUD, the vancomycin soaking technique provides a $600AUD cost saving by both reducing the risk of ACLR related infection and economic burden of infection. Treating septic arthritis represents a mean cost per patient of 6 times compared to that of the primary surgery. There has been no previous cost-effectiveness study of the vancomycin wrap technique.

The vancomycin pre-soaking technique is a highly cost-effective method to prevent post-operative septic arthritis following primary ACLR.

A. Chavan J. Hoellwarth K. Tetsworth W. Lu A. Oomatia S. Alam E. Vrazas M. Al Muderis

Traditional socket prosthesis (TSP) rehabilitation for amputees is associated with substantial dissatisfaction due to poor mobility and pain from soft tissue squeezing. Osseointegration (OI), eliminates skin compression and prosthesis fit issues, providing superior mobility and quality of life (QOL) for most amputees. The potential for OI to benefit patients with exceptionally poor mobility is understudied. To address this knowledge gap, this project investigated the mobility and QOL changes.

A retrospective review was performed to identify transfemoral amputees who presented with wheelchair-bound mobility (K0) and had at least five years of post-osseointegration follow-up. Outcome measures included changes in mobility (K-level, daily prosthesis wear hours, Timed Up and Go (TUG), 6 minute walk test (6MWT)) and QOL (Questionnaire for persons with a Transfemoral Amputation (QTFA); Short Form Health Survey 36 (SF36). Adverse events recorded included debridement for infection, implant revision surgery, fractures, and implant failures.

9 patients with mean age 48.2±7.7 (range 34-59) years were included. The proportion of patients achieving K-level >2 improved from 0/9=0% to [9/9=100%], p<0.001. The 6MWT improved from 0±0 to 320.65±57 meters (p<0.001). The TUG improved from incapable to 10.68±2.7 seconds (p<0.001). Statistically significant QOL metrics included QTFA global score (33.33±31 vs 68.52±21, p=0.039), SF36 physical component score (30.03±6.3 vs 42.34±12, p=0.023) and the SF36 mental component score (47.89±8.8 vs 51.95±10.4, p=0.332). Six patients required operative intervention to address complications. Five developed infections: three had debridement, and 2 required implant removal and reimplantation.

Osseointegration does confer significant sustained mobility and quality of life improvement for wheelchair bound transfemoral amputees. All 9 K0 patients had statistically improved mobility and QOL after osseointegrated reconstruction. This supports osseointegration as an effective rapid and long-term rehabilitation alternative for patients who have the neurologic and muscular capacity to walk but are unable due to issues related to their TSP.

A. Matt J.L. Kemp A.B. Mosler A.L. Semciw B.R. Gooden M.D. O'Sullivan M.C. Lyons L. Salmon

Total hip arthroplasty (THA) has high rates of patient satisfaction; however patient expectations for recreational and sporting activities are not always met. Our study aimed to identify preoperative factors that predict whether patient expectations for sporting or recreational activity are met 12 months following THA.

Patient reported outcome measures (PROMs) were collected prospectively from 2015-2018 at one private hospital in Sydney. Age, gender, postcode, weight, and height were recorded preoperatively. Included participants underwent primary THA by one of the investigating surgeons. Univariable and multivariable analyses were performed with an expectation fulfilment score used as the primary outcome variable. Preoperative predictor variables included: age, gender, BMI, Socio-economic Indexes for Areas (SEIFA), Oxford Hip Score, Hip Osteoarthritis Outcome Score, EQ-5D-5L and EQ Visual Analogue Scale (EQ VAS).

1019 participants were eligible and included. 13% reported that preoperative expectations of sport or recreation were not met at 12 months. Younger age, lower preoperative EQ VAS, and higher BMI were associated with failed expectations on multivariable analysis. Odds of failed expectations increased by 2% for every one year younger in age (OR= 0.98, 95% CI = 0.96 to 1.00, p=.048), by 2% for every one point lower on EQ VAS (OR=0.98, 95% CI = 0.98 to 0.99, p=.002), and by 4% for every one-point increase in BMI (OR = 1.04, 95% CI = 1.00 to 1.09, p=.042).

Failure to have expectations met for sporting or recreational activity was associated with younger age, poorer general health, and high BMI. With a rise in younger patients who likely have higher physical demands, a tailored preoperative education is preferable to generic models to better manage patient expectations.

Younger age, higher BMI, and poorer health may predict unmet expectations for sport and recreation after THA. Tailored education in these groups should be considered.

A. Faveere L. Milne C. Holder S.E. Graves

Increasing femoral offset in total hip replacement (THR) has several benefits including improved hip abductor strength and enhanced range of motion. Biomechanical studies have suggested that this may negatively impact on stem stability. However, it is unclear whether this has a clinical impact. Using data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), the aim of this study was to determine the impact of stem offset and stem size for the three most common cementless THR prostheses revised for aseptic loosening.

The study period was September 1999 to December 2020. The study population included all primary procedures for osteoarthritis with a cementless THR using the Corail, Quadra-H and Polarstem. Procedures were divided into small and large stem sizes and by standard and high stem offset for each stem system. Hazard ratios (HR) from Cox proportional hazards models, adjusting for age and gender, were performed to compare revision for aseptic loosening for offset and stem size for each of the three femoral stems.

There were 55,194 Corail stems, 13,642 Quadra-H stem, and 13,736 Polarstem prostheses included in this study. For the Corail stem, offset had an impact only when small stems were used (sizes 8-11). Revision for aseptic loosening was increased for the high offset stem (HR=1.90;95% CI 1.53–2.37;p<0.001).

There was also a higher revision risk for aseptic loosening for high offset small size Quadra-H stems (sizes 0-3). Similar to the Corail stem, offset did not impact on the revision risk for larger stems (Corail sizes 12-20, Quadra-H sizes 4-7). The Polarstem did not show any difference in aseptic loosening revision risk when high and standard offset stems were compared, and this was irrespective of stem size.

High offset may be associated with increased revision for aseptic loosening, but this is both stem size and prosthesis specific.

A. Gupta M. Jomaa A. Ker F. Hollman N. Singh J. Maharaj K. Cutbush

Massive posterosuperior cuff tears (mRCT) retracted to the glenoid are surgically challenging and often associated with high retear rates. Primary repair is a less-favourable option and other salvage procedures such as SCR and tendon transfers are used. This study presents clinical and radiological outcomes of muscle advancement technique for repair of mRCT.

Sixty-one patients (mean age 57±6, 77% males and 23% females) (66 shoulders) underwent all-arthroscopic rotator cuff repair that included supraspinatus and infraspinatus subperiosteal dissection off scapular bony fossae, lateral advancement of tendon laminae, and tension-free double-layer Lasso Loop repair to footprint.

Pre-and post-operative range of motion (ROM), cuff strength, VAS, Constant, ASES, and UCLA scores were assessed. Radiologic assessment included modified Patte and Goutallier classifications. All patients had MRI at 6 months to evaluate healing and integrity of repair was assessed using Sugaya classification with Sugaya 4 and 5 considered retears.

Advanced fatty degeneration (Goutallier 3-4) was present in 44% and 20% of supraspinatus and infraspinatus. Tendon retraction was to the level of or medial to glenoid in 22%, and just lateral in 66%. 50.8% mRCT extended to teres minor. Subscapularis was partially torn (Lafosse 1-3) in 46% and completely torn (Lafosse 4-5) in 20%.

At mean follow-up (52.4 weeks), a significant increase in ROM, Relative Cuff Strength (from 57% to 90% compared to contralateral side), VAS (from 4 ±2.5 to 1±1.7), Constant (50±17.8 to 74 ±13.0), ASES (52 ±17.5 to 87 ±14.9), and UCLA (16± 4.9 to 30 ±4.9) scores were noted. There were six retears (10%), one failure due to P. acnes infection. 93% returned to pre-injury work and 89% of cases returned to pre-injury sport. Satisfaction rate was 96%.

Muscle advancement technique for mRCT is a viable option with low retear rates, restoration of ROM, strength, and excellent functional outcomes.

A. Gupta M. Launay J. Maharaj A. Salhi F. Hollman A. Tok L. Gilliland S. Pather K. Cutbush

Complications such as implant loosening, infection, periprosthetic fracture or instability may lead to revision arthroplasty procedures. There is limited literature comparing single-stage and two-stage revision shoulder arthroplasty. This study aims to compare clinical outcomes and cost benefit between single-stage and two-stage revision procedures.

Thirty-one revision procedures (mean age 72+/-7, 15 males and 16 females) performed between 2016 and 2021 were included (27 revision RSA, 2 revision TSA, 2 failed ORIFs). Two-stage procedures were carried out 4-6 weeks apart. Single-stage procedures included debridement, implant removal and washout, followed by re-prep, re-drape and reconstruction with new instrumentations. Clinical parameters including length of stay, VAS, patient satisfaction was recorded preoperatively and at mean 12-months follow up. Cost benefit analysis were performed.

Seven revisions were two-stage procedures and 24 were single-stage procedures. There were 5 infections in the two-stage group vs 14 in the single-stage group. We noted two cases of unstable RSA and 8 other causes for single-stage revision. Majority of the revisions were complex procedures requiring significant glenoid and/or humeral allografts and tendon transfers to compensate for soft tissue loss. No custom implants were used in our series.

Hospital stay was reduced from 41+/-29 days for 2-stage procedures to 16+/-13 days for single-stage (p<0.05). VAS improved from 9+/-1 to 2+/-4 for two-stage procedures and from 5+/-3 to 1+/-2 for single-stages. The average total cost of hospital and patient was reduced by two-thirds. Patient satisfaction in the single-stage group was 43% which was comparable to the two-stage group.

All infections were successfully treated with no recurrence of infection in our cohort of 31 patients. There was no instability postoperatively. 3 patients had postoperative neural symptoms which resolved within 6 months.

Single-stage procedures for revision shoulder arthroplasty significantly decrease hospital stay, improve patients’ satisfaction, and reduced surgical costs.

B. Minasian N. Hope

Surfing has rapidly grown in popularity as the sport made its debut at the Tokyo 2020 Olympic Games. Surfing injuries are becoming more relevant with the globalisation and increasing risks of the sport, but despite this, little is known about surfing injuries or prevention strategies in either the competitive or recreational surfer.

We reviewed the literature for the incidence, anatomical distribution, type and underlying mechanism of acute and overuse injuries, and discuss current preventative measures. Four online databases, including MEDLINE, PubMed, EMBASE and Cochrane Library were searched from inception to March 2020.

This review finds that skin injuries represent the highest proportion of total injuries. Acute injuries most frequently affect the head, neck and face, followed by the lower limbs. Being struck by one's own board is the most common mechanism of injury. Surfers are injured at a frequency of 0.30–6.60 injuries per 1000 hours of surfing.

Most prior studies are limited by small sample sizes, poor data collection methodology and geographical constraints. The scientific literature on surfing injuries under-represents overuse musculoskeletal injuries and the efficacy of prevention strategies for surfing-related overuse musculoskeletal injuries has not been studied. Injuries to the head and neck pose greater risks to a surfer's morbidity and mortality, yet there is no consensus on the management protocol of spinal injuries that occur in open water. Non-contact acute ligament injuries have increased as surfing manoeuvres have become more acrobatic, and overuse musculoskeletal injuries are highly correlated with paddling.

Further research is needed to establish preventative measures for both acute and overuse surfing injuries and to ensure the increasing popularity of surfing is met with an improved understanding of sport risks and safety. Specifically, we recommend research be prioritised regarding the efficacy of training programmes to prevent surfing-related overuse musculoskeletal injuries.

B. Jadav

3D printing techniques have attracted a lot of curiosity in various surgical specialties and the applications of the 3D technology have been explored in many ways including fracture models for education, customized jigs, custom implants, prosthetics etc. Often the 3D printing technology remains underutilized in potential areas due to costs and technological expertise being the perceived barriers.

We have applied 3D printing technology for acetabular fracture surgeries with in-house, surgeon made models of mirrored contralateral unaffected acetabulum based on the patients’ trauma CT Scans in 9 patients. The CT Scans are processed to the print with all free-ware modeling software and relatively inexpensive printer by the surgeon and the resulting model is used as a ‘reduced fracture template’ for pre-contouring the standard pelvic reconstruction plates. This allows use of the standard surgical implants, saves time on intra-operative plate contouring, and also aids in reduction to an extent.

We share through this presentation the workflow of the freeware softwares to use in order to use this surgical planning and implant preparation that may remove the perceived barriers of cost and technology from surgeons that wish to explore using 3D printing technology for acetabular fracture management and may extend applications to other regions.

B. Jadav

Sternoclavicular joint infections are uncommon but severe and complex condition usually in medically complex and compromised hosts. These infections are challenging to treat with risks of infection extending into the mediastinal structures and surgical drainage is often faced with problems of multiple unplanned returns to theatre, chronic non-healing wounds that turn into sinus and the risk of significant clinical escalation and death. Percutaneous aspirations or small incision drainage often provide inadequate drainage and failed control of infection, while open drainage and washout require multidisciplinary support, due to the close proximity of the mediastinal structures and the great vessels as well as failure to heal the wounds and creation of chronic wound or sinus.

We present our series of 8 cases over 6 years where we used the plan of open debridement of the Sternoclavicular joint with medial end of clavicle excision to allow adequate drainage. The surgical incision was not closed primarily, and a suction vacuum dressing was applied until the infection was contained on clinical and laboratory parameters. After the infection was deemed contained, the surgical incision was closed by local muscle flap by transferring the medial upper sternal head of the Pectoralis Major muscle to fill in the sternoclavicular joint defect. This technique provided a consistent and reliable way to overcome the infection and have the wound definitively closed that required no secondary procedures after the flap surgery and no recurrence of infections so far.

We suggest that open and adequate drainage of Sternoclavicular joint staged with vacuum dressing followed by pectoralis major local flap is a reliable technique for achieving control of infection and wound closure for these challenging infections.

J.E. Farey Y. Chai J. Xu A. Sadeghpour D. Marsden-Jones N. Baker J. Vigdorchik W.L. Walter

Imageless computer navigation systems have the potential to improve acetabular cup position in total hip arthroplasty (THA), thereby reducing the risk of revision surgery. This study aimed to evaluate the accuracy of three alternate registration planes in the supine surgical position generated using imageless navigation for patients undergoing THA via the direct anterior approach (DAA).

Fifty-one participants who underwent a primary THA for osteoarthritis were assessed in the supine position using both optical and inertial sensor imageless navigation systems. Three registration planes were recorded: the anterior pelvic plane (APP) method, the anterior superior iliac spines (ASIS) functional method, and the Table Tilt (TT) functional method. Post-operative acetabular cup position was assessed using CT scans and converted to radiographic inclination and anteversion. Two repeated measures analysis of variance (ANOVA) and Bland-Altman plots were used to assess errors and agreement of the final cup position.

For inclination, the mean absolute error was lower using the TT functional method (2.4°±1.7°) than the ASIS functional method (2.8°±1.7°, ρ = .17), and the ASIS anatomic method (3.7°±2.1, ρ < .001). For anteversion, the mean absolute error was significantly lower for the TT functional method (2.4°±1.8°) than the ASIS functional method (3.9°±3.2°, ρ = .005), and the ASIS anatomic method (9.1°±6.2°, ρ < .001). All measurements were within ± 10° for the TT method, but not the ASIS functional or APP methods.

A functional registration plane is preferable to an anatomic reference plane to measure intra-operative acetabular cup inclination and anteversion accurately. Accuracy may be further improved by registering patient location using their position on the operating table rather than anatomic landmarks, particularly if a tighter target window of ± 5° is desired.

B. Lee B. Gilpin R. Bindra

Chauffeur fractures or isolated radial styloid fractures (IRSF) are known to be associated with scapholunate ligament (SL) injuries. Diagnosis without arthroscopic confirmation is difficult in acute fractures. Acute management of this injury with early repair may prevent the need for more complex reconstructive procedures for chronic injuries. We investigated if all IRSF should be assessed arthroscopically for concomitant SL injuries.

We performed a prospective cohort study on patients above the age of 16, presenting to the Gold Coast University Hospital with an IRSF, over 2 years. Plain radiographs and computerized tomography (CT) scans were performed. All patients had a diagnostic wrist arthroscopy performed in addition to an internal fixation of the IRSF. Patients were followed up for at least 3 months post operatively. SL repair was performed for all Geissler Grade 3/4 injuries.

10 consecutive patients were included in the study. There was no radiographic evidence of SL injuries in all patients. SL injuries were identified arthroscopically in 60% of patients and one third of these required surgical stabilisation. There were no post operative complications associated with wrist arthroscopy.

We found that SL injuries occurred in 60% of IRSF and 20% of patients require surgical stabilisation. This finding is in line with the literature where SL injuries are reported in up to 40-80% of patients. Radiographic investigations were not reliable in predicting possible SL injuries in IRSF. However, no SL injuries were identified in undisplaced IRSF. In addition to identifying SL injuries, arthroscopy also aids in assisting and confirming the reduction of these intra-articular fractures.

In conclusion, we should have a high index of suspicion of SL injury in IRSF. Arthroscopic assisted fixation should be considered in all displaced IRSF. This is a safe additional procedure which may prevent missed SL injuries and their potential sequelae.

B. Driessen V. Yap D.J. Ng O. Korshid S. Wall P. Yates G. Prosser M. Wilkinson K. Hazratwala T. Tran.

Clinical success of prostheses in joint arthroplasty is ultimately determined by survivorship and patient satisfaction. The purpose of this study was to compare (non-inferiority) a new morphometric designed stem for total hip arthroplasty (THA) against an established comparator.

A prospective randomised multi-centre study of 144 primary cementless THA performed by nine experienced orthopaedic surgeons was completed (70 received a fully coated collarless tapered stem and 70 received a morphometric designed proximally coated tapered stem). PROMs and blood serum markers were assessed preoperatively and at intervals up to 2-years postoperatively. In addition, measures of femoral stem fit, fill and subsidence at 2-years post-operatively were measured from radiographs by three observers, with an intra-class correlation coefficient of 0.918. A mixed effects model was employed to compare the two prostheses over the study period. A p-value <0.05 was considered statistically significant.

Demographics and Dorr types were similar between groups. Both stems demonstrated a significant improvement in PROMs between the pre- and post-operative measurements, with no difference at any timepoint (p > 0.05). The fully coated tapered collarless femoral stem had a non-significantly higher intra-operative femoral fracture rate (5.8% vs 1.4%, p = 0.24), with all patients treated with cable fixation and partial weight bearing. The mean subsidence at 2-years was 2.5mm +/- 2.3mm for the morphometric stem and 2.4mm +/- 1.8mm for the fully coated tapered collarless femoral stem (p = 0.879). There was one outlier in each group with increased subsidence (fully coated tapered collarless femoral stem 6.9mm, morphometric wedge stem 7.4mm), with both patients reporting thigh pain at 2 years.

When compared with an established stem, the newer designed morphometric wedge stem performed well with comparable radiological and PROM outcomes at 2 year follow up. Continued follow-up is required for long term benchmarking.

I.B. McPhee

There are numerous patient satisfaction questionnaires by none specific for an Independent Medical Examination (IME). The aim of this study was to develop and evaluate a questionnaire suitable for an IME.

The questionnaire (IMESQ) consisted of five process domains (“Interpersonal manner”, “Communication”, “Technical ability”, “Information exchange”, “Time allocation”) and an outcome domain (“Satisfaction”), each with a five-scale Likert response. An 11-point numerical satisfaction scale (NSS) and a 3-point scale question on the “willing to undergo another examination with the doctor if required” were alternative measures of validation. The questionnaire was tested against numerous independent variables.

Statistical analysis included Spearman correlation ((rS) between the items in the questionnaire and the total score with the NSS, and “willing to undergo another examination with the doctor if required” with point-biserial correlation (rpb). Internal consistent reliability was tested using split-half correlation coefficient (rSB) and Cronbach's alpha coefficient (α). The construct was subjected to Factor Analysis.

The results from 53 respondents were analysed. There was moderate to strong inter-item correlation (rs range 0.57 to 0.83, median 0.67, p < 0.01) and good correlation with the NSS (rs = 0.79, p < 0.01) and dichotomous question (rpb = 0.45, p < 0.01). Five respondents were “neither satisfied or dissatisfied” (Item 6) and 12 recorded “maybe” to further examination. The split-half correlation was strong (rSB= 0.76, p < 0.01). There was good internal consistency reliability (α = 0.92). “Interpersonal manner” (ψ = 4.3) was the only item to have an eigenvalue greater than one, accounting to 72% of the variance across the scale. Eigenvector analysis confirmed the questionnaire was unidimentional.

The IMESQ is a brief questionnaire to assess satisfaction with an IME. It is validated and has good internal consistency reliability. The five process domains can identify areas of suboptimal performance: useful for a 360° audit.

B. Batinica S.M. Bolam M. Zhu M. D'Arcy R. Peterson S. Young A.P. Monk J.T. Munro

Little information exists regarding optimal tibial stem usage in revision total knee arthroplasty (rTKA) utilising a tibial trabecular metal (TM) cone. The purpose of this study was to compare 1) functional outcomes, 2) radiographic outcomes, and 3) implant survivorship in rTKA utilising TM cones combined with either short stems (SS) or long stems (LS) at minimum two-years clinical follow-up.

In this retrospective, multi-centre study, patients undergoing TM cone utilising rTKA between 2008 and 2019 were included. Patients were divided into: SS group (no diaphyseal engagement), and LS group (diaphyseal engagement). All relevant clinical charts and post-operative radiographs were examined. Oxford Knee Score (OKS) and EuroQol-5D (EQ-5D-5L) data were collected at most recent follow-up.

In total, 44 patients were included: 18 in the SS group and 26 in the LS group. The mean time of follow-up was 4.0 years. Failure free survival was 94.5% for the SS group and 92.3% for the LS group. All failures were for prosthetic joint infections managed with debridement, antibiotics, and implant retention. At most recent follow-up, 3 patients demonstrated radiographic signs of lucency (1 SS 2 LS, p = 1) and the mean OKS were 37 ± 4 and 36 ± 6 (p = 0.73) in the SS and LS groups, respectively.

Tibial SS combined with TM cones performed as well as LS in rTKA at minimum two-years follow-up. A tibial SS in combination with a TM cone is a reliable technique to achieve stable and durable fixation in rTKA.

C. Lutter T.M. Grupp W. Mittelmeier M. Selig P. Grover M. Dreischarf G. Rose T. Bien

Polyethylene wear represents a significant risk factor for the long-term success of knee arthroplasty [1]. This work aimed to develop and in vivo validate an automated algorithm for accurate and precise AI based wear measurement in knee arthroplasty using clinical AP radiographs for scientifically meaningful multi-centre studies.

Twenty postoperative radiographs (knee joint AP in standing position) after knee arthroplasty were analysed using the novel algorithm. A convolutional neural network-based segmentation is used to localize the implant components on the X-Ray, and a 2D-3D registration of the CAD implant models precisely calculates the three-dimensional position and orientation of the implants in the joint at the time of acquisition. From this, the minimal distance between the involved implant components is determined, and its postoperative change over time enables the determination of wear in the radiographs.

The measured minimum inlay height of 335 unloaded inlays excluding the weight-induced deformation, served as ground truth for validation and was compared to the algorithmically calculated component distances from 20 radiographs.

With an average weight of 94 kg in the studied TKA patient cohort, it was determined that an average inlay height of 6.160 mm is expected in the patient. Based on the radiographs, the algorithm calculated a minimum component distance of 6.158 mm (SD = 81 µm), which deviated by 2 µm in comparison to the expected inlay height.

An automated method was presented that allows accurate and precise determination of the inlay height and subsequently the wear in knee arthroplasty based on a clinical radiograph and the CAD models. Precision and accuracy are comparable to the current gold standard RSA [2], but without relying on special radiographic setups. The developed method can therefore be used to objectively investigate novel implant materials with meaningful clinical cohorts, thus improving the quality of patient care.

C.B. Tse S.I. Mandler H.A. Crawford A.J.F. Field

The purpose of this study is to evaluate risk factors for distal construct failure (DCF) in posterior spinal instrumented fusion (PSIF) in adolescent idiopathic scoliosis (AIS). We observed an increased rate of DCF when the pedicle screw in the lowest instrumented vertebra (LIV) was not parallel to the superior endplate of the LIV, however this has not been well studied in the literature. We hypothesise a more inferiorly angled LIV screw predisposes to failure and aim to find the critical angle that predisposes to failure.

A retrospective cohort study was performed on all patients who underwent PSIF for AIS at the Starship Hospital spine unit from 2010 to 2020. On a lateral radiograph, the angle between the superior endplate of the LIV was measured against its pedicle screw trajectory. Data on demographics, Cobb angle, Lenke classification, instrumentation density, rod protrusion from the most inferior screw, implants and reasons for revision were collected.

Of 256 patients, 10.9% (28) required at least one revision. The rate of DCF was 4.6% of all cases (12 of 260) and 25.7% of revisions were due to DCF. The mean trajectory angle of DCF patients compared to all others was 13.3° (95%CI 9.2° to 17.4°) vs 7.6° (7° to 8.2°), p=0.0002. The critical angle established is 11°, p=0.0076. Lenke 5 and C curves, lower preoperative Cobb angle, titanium only rod constructs and one surgeon had higher failure rates than their counterparts. 9.6% of rods protruding less than 3mm from its distal screw disengaged.

We conclude excessive inferior trajectory of the LIV screw increases the rate of DCF and a screw trajectory greater than 11° predisposes to failure. This is one factor that can be controlled by the surgeon intraoperatively and by avoiding malposition of the LIV screw, a quarter of revisions can potentially be eliminated.

C. Fryer C. Jackson K. Mckelvey H. Lin M. Xue.

Tendinopathy is a tendon pathology often resulting from a failed healing response to tendon injury. Activated protein C (APC) is a natural anti-coagulant with anti-inflammatory and wound healing promoting functions, which are mainly mediated by its receptors, endothelial protein C receptor (EPCR) and protease activated receptors (PARs). This study aimed to determine whether APC stimulates tenocyte healing and if so, to assess the involvement of the receptors.

Mouse-tail tenocytes were isolated from 3-week-old wild type (WT), PAR- 1 knockout (KO) and PAR-2 KO mice. The expression of EPCR, PAR-1 and −2 and the effect of APC on tenocytes tendon healing and the underlying mechanisms were investigated by Reverse transcription real time PCR, western blot, 3- (4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay, zymography, and scratch wound healing/ migration assay.

When compared to WT cells, PAR-1 KO tenocytes showed increased cell proliferation (3.3-fold, p<0.0001), migration (2.7-fold, p<0.0001) and wound healing (3-fold, p<0.0001), whereas PAR-2 KO cells displayed decreased cell proliferation (0.6-fold, p<0.05) and no change in cell migration or wound healing. APC at 1 μg/ml stimulated WT and PAR-1 KO tenocyte proliferation (~1.3, respectively, p<0.05) and wound healing (~1.3-fold, respectively, p<0.05), and additionally promoted PAR1-KO cell migration (1.4-fold, p<0.0001). APC only increased the migration (2-fold, p<0.05) of PAR-2 KO tenocytes. The activation of AKT, extracellular signal-regulated kinase (ERK)-2, and glycogen synthase kinase (GSK)-β3, the intracellular molecules that are associated with cell survival/growth, and matrix metalloproteinase (MMP)-2 that is related to cell migration and wound healing, were increased in all three cell lines in response to APC treatment.

These findings show that PAR-1 and PAR-2 act differentially in tenocyte proliferation/migration/wound healing. APC likely promotes tenocyte proliferation/ wound healing via PAR-2, not PAR-1.

C. Fary S. Abshagen D. Van Andel A.N. Ren M.B. Anderson B. Klar

Advances in algorithms developed with sensor data from smart phones demonstrates the capacity to passively collect qualitative gait metrics. The purpose of this feasibility study was to assess the recovery of these metrics following joint reconstruction. A secondary data analysis of an ethics approved global, multicenter, prospective longitudinal study evaluating gait quality data before and after primary total knee arthroplasty (TKA, n=476), partial knee arthroplasty (PKA, n=139), and total hip arthroplasty (THA, n=395). A minimum 24 week follow-up was required (mean 45±12, range 24 - 78). Gait bouts and gait quality metrics (walking speed, step length, timing asymmetry, and double support percentage) were collected from a standardized smartphone operating system. Pre- and post-operative values were compared using paired-samples t-tests (p<0.05).

A total of 595 females and 415 males with a mean age of 61.9±9.3 years and mean BMI of 30.2±6.1 kg/m2 were reviewed. Walking speeds were lowest at post-operative week two (all, p<.001). Speeds exceeded pre-operative means consistently by week 21 (p=0.015) for PKA, and week 13 (p=0.007) for THA. The average weekly step length was lowest in post-operative week two (all, p<0.001). PKA and THA cases achieved pre-operative step lengths by week seven (p=0.064) and week 9 (p=0.081), respectively. The average weekly gait asymmetry peaked at week two post-operatively (all, p <0.001). Return to pre-operative baseline asymmetry was achieved by week 11 (p=0.371) for TKA, week six (p=0.541) for PKA, and week eight (p=.886) for THA. Double limb support percentages peaked at week two (all, p<0.001) and returned to pre-operative levels by week 24 (p=0.089) for TKA, week 12 (p=0.156) for PKA, and week 10 (p=0.143) for THA.

Monitoring gait quality in real-world settings following joint reconstruction using smartphones is feasible, and may provide the advantage of removing the Hawthorne effect related to typical gait assessments and in-clinic observations.

C. Fary K. Tripuraneni B. Klar A.N. Ren S. Abshagen R. Verheul

We sought to evaluate the early post-operative active range-of-motion (AROM) between robotic-assisted total knee arthroplasty (raTKA) and conventional TKA (cTKA). A secondary data analysis on a global prospective cohort study was performed. A propensity score method was used to select a matched control of cTKA from the same database using 1:1 ratio, based on age, sex, BMI, and comorbidity index. This resulted in 216 raTKA and cTKA matched cases. Multivariable longitudinal regression was used to evaluate difference in ROM over time and values are reported as least squares means (95% confidence interval). The longitudinal model tested the treatment effect (raTKA vs cTKA), time effect, and their interaction with control on covariance of patients ‘s age, sex, BMI, comorbidity and pre-operative flexion. Logistic regression was used to analyze the active flexion level at one month (cut by 90°) and three months (cut by 110°).

At one-month postoperative the raTKA cases had more AROM for flexion by an average of 5.54 degrees (p<0.001). There was no difference at three months (p=0.228). The raTKA group had a greater improvement from pre-operative values at both one-month, with an average 7.07° (3.6°, 10.5°, p<0.001) more improvement, and at three-months with an average improvement of 4° more (1.61°, 7.24°, p=0.0115). AROM for extension was lower overall in the raTKA group by an average of 0.44° (p=0.029). The raTKA patients had higher odds of achieving ≥90° of flexion at one-month (OR 2.15, 95% CI 1.16, 3.99).

raTKA resulted in greater AROM flexion gains in the early postoperative period than cTKA. Additional research is needed to understand if these earlier gains in AROM are associated with improved patient satisfaction and continued improvements with time.

C. Kollias E. Neville S. Vladusic L. McLachlan

Specific brace-fitting complications in idiopathic congenital talipes equinovarus (CTEV) have been rarely described in published series, and usually focus on non-compliance. Our primary aim was to compare the rate of persistent pressure sores in patients fitted with Markell boots and Mitchell boots. Our additional aims were to describe the frequency of other brace fitting complications and identify age trends in these complications. A retrospective analysis of medical files of 247 idiopathic CTEV patients born between 01/01/2010 - 01/01/2021 was performed. Data was collected using a REDCap database.

Pressure sores of sufficient severity for clinician to recommend time out of brace occurred in 22.9% of Mitchell boot and 12.6% of Markell boot patients (X2 =6.9, p=0.009). The overall rate of bracing complications was 51.4%. 33.2% of parents admitted to bracing non-compliance and 31.2% of patients required re-casting during the bracing period for relapse. For patients with a minimum follow-up of age 6 years, 44.2% required tibialis anterior tendon transfer. Parents admitting to non-compliance were significantly more likely to have a child who required tibialis anterior tendon transfer (X2=5.71, p=0.017). Overall rate of capsular release (posteromedial release or posterior release) was 2.0%.

Neither medium nor longterm results of Ponseti treatment in the Australian and New Zealand clubfoot have been published. Globally, few publications describe specific bracing complications in clubfoot, despite this being a notable challenge for clinicians and families. Recurrent pressure sores is a persistent complication with the Mitchell boots for patients in our center. In our population of Australian clubfoot patients, tibialis anterior tendon transfer for relapse is common, consistent with the upper limit of tibialis anterior tendon transfer rates reported globally.

C. Kollias C. Conyard M. Formosa R. Page I. Incoll

Physician health is a global concern, with increasing research efforts directed towards the challenge. Australia has limited published specialty-specific well-being data for trainees and consultants in medicine and surgery. We measured distress in Australian Orthopaedic trainees using the Physician Well-Being Index (PWBI, MedEd Web Solutions) using an online anonymous survey sent by the Australian Orthopaedic Association.

The survey response rate was 38% (88/230). Forty-four percent of survey respondents met criteria for distress. Self-reported burnout in the 30 days prior was reported by 63% of respondents. Fifty-eight percent of females and 41% of males met criteria for distress. Of the 19% or respondents identifying as an ethnic minority, 53% were distressed compared to 42% of those identifying as non-ethnic minority. Trainees without a mentor had a 50% distress rate compared to those with a mentor (37% distress rate). Twenty-five percent of all trainees wished they had picked a career outside of medicine and 16% wished they had pursued a medical career other than Orthopaedic Surgery. Of those trainees who had already passed the fellowship exam, 17% wished they had pursued a career outside of medicine and 21% wished they had pursued a medical career in an area other than Orthopaedic Surgery.

These findings suggest concerning rates of career regret and gender-related trends in distress in Australian Orthopaedic trainees. Females may be over-represented in our results as 17% of the source population was female compared to 22% of respondents. Further research is required across all Australian specialties to gain further understanding of factors contributing to distress and to assist in the development of strategy to protect against physician burnout.

C.H. Tuffley J.C. Tuffley W. Donnelly I. Harris A. Cuthbert

In this study we compare survivorship and patient reported outcome measures in robotically assisted versus conventional Total Hip Arthroplasty (THA).

This paper investigates the hypothesis that implant survival and PROMS following THAs performed with robotic assistance were not different to outcomes following conventional THAs.

Data included all patients undergoing THA for osteoarthritis between 19 April 2016 and 31 December 2020. Analysis of PROMS outcomes was restricted to those who had completed PROMS data preoperatively and at 6 months postoperatively.

There were 157,647 procedures, including 3567 robotically assisted procedures, available for comparison of revision rates. 4557 procedures, including 130 robotically assisted procedures, had PROMS data available. The revision rate of primary THA performed with robotic assistance was not statistically different from THA performed by conventional methods (4 year cumulative percent revision 3.1% v 2.7%; HR = 1.05, p=0.67). The Oxford Hip Score, VAS for pain and the EQ-VAS score for overall health showed no statistically significant difference between the groups. The EQ-5D Utility Score showed an improved score (median score 1 v 0.88; OR = 1.58, p=0.007) for the robotically assisted group compared to the conventional group.

Robotic assisted THA was not associated with significant improvement in early revision or joint-specific PROMs. The findings may have been biased, in either direction, by unmeasured patient, surgeon, hospital and prosthesis factors. The findings (including the difference in health-related quality of life) may have also been influenced by lack of blinding. Future research should include methods to minimise these biases.

S. Reason C. Wainwright

Little guidance exists in the current literature regarding which patient recorded outcome measures (PROMs) are most clinically appropriate following anterior cruciate ligament reconstruction (ACL) surgery, and what results surgeons should expect or accept. Many PROMs have been validated, but their “ideal” results have not been published, limiting a surgeon's ability to compare their patients’ outcomes with those of their colleagues.

We undertook a systematic review of PROMs for ACL to look at common usage and outcomes. After appropriate paper selection, we then undertook a pragmatic meta-analysis (i.e., including all papers that fulfilled the selection criteria, regardless of CONSORT status) and calculated weighted mean outcome scores and standard deviations for the most commonly used PROMs.

A comprehensive literature search of all English articles of PubMed and other sources including search terms (‘Patient related outcome measure’ or ‘PROM’) AND ‘anterior cruciate ligament’ (limited to abstract/title) yielded 722 articles. Title review narrowed this to 268, and abstracts review to 151, of which 88 were included in our meta-analysis. Weighted mean and standard deviations were calculated for IKDC, KOOS, Lysholm, Teneger and “VAS Pain” PROMs as the most commonly reported. We identified significant, novel findings relating to selected PROMs and (i) demographics including age, gender and body mass index, (ii) surgical factors including bundle count, strand count, and graft type, and (iii) post operative complications.

We clarified the most commonly used PROMs for ACL, and their weighted means and standard deviations. This will allow surgeons to compare results with colleagues, ensuring they meet international levels of quality in PROMs. We have also updated which patient and operative factors have an impact on PROMs scoring to allow for population variance.

C.J. Wall R.N. de Steiger J.S. Mulford P.L. Lewis D.G. Campbell

There is growing interest in the peri-operative management of patients with indications for hip and knee arthroplasty in the setting of modifiable risk factors such as morbid obesity, type 2 diabetes mellitus, and smoking. A recent survey of the American Association of Hip and Knee Surgeons (AAHKS) found that 95% of respondents address modifiable risk factors prior to surgery. The aim of this study was to poll Australian arthroplasty surgeons regarding their approach to patients with modifiable risk factors.

The survey tool used in the AAHKS study was adapted for use in the Australian context and distributed to the membership of the Arthroplasty Society of Australia via Survey Monkey.

Seventy-seven survey responses were received, representing a response rate of 64%. The majority of respondents were experienced, high volume arthroplasty surgeons. Overall, 91% of respondents restricted access to arthroplasty for patients with modifiable risk factors. Seventy-two percent of surgeons restricted access for excessive body mass index, 85% for poor diabetic control, and 46% for smoking. Most respondents made decisions based on personal experience or literature review rather than hospital or departmental pressures.

Despite differences in healthcare systems, our findings were similar to those of the AAHKS survey, although their responses were more restrictive in all domains. Differences were noted in responses concerning financial considerations for potentially underprivileged populations. The survey is currently being administered by arthroplasty societies in six other countries, allowing comparison of orthopaedic practice across different healthcare systems around the world.

In conclusion, over 90% of Australian arthroplasty surgeons who responded to the survey address modifiable risk factors prior to surgery.

C. Erian M. Erian N. Ektas C. Scholes C. Bell

Anterior cruciate ligament (ACL) ruptures are debilitating injuries, often managed via ACL reconstruction (ACLR). Reduced range of motion (ROM), particularly loss of extension (LOE), is the most significant contributor to post-operative patient dissatisfaction. LOE may preclude return to sport, increase re-rupture rates and precipitate osteoarthritis.

Passive LOE rates following ACLR have been reported at 15%. However, LOE incidence during active tasks are poorly characterised. Our review sought to determine knee extension angles for active tasks following an ACL injury or ACLR. We hypothesised greater incidences of active LOE following ACL injury or ACLR, compared to uninjured contralateral limbs or controls.

We systematically searched MEDLINE, Embase, Cochrane Library, Scopus, SPORTDiscus, and relevant trials databases for English articles. Included were cohort, cross-sectional, case-controlled or randomised controlled trials analysing adults with ACL injury treated surgically or otherwise, with at least 12-weeks follow-up and reporting either active knee extension angle, active LOE angles or incidence of active knee LOE during functional tasks. The protocol was registered on PROSPERO (CRD42018092295). Subsequent meta-analysis was performed.

After screening, 71 eligible articles were included. Studies were heterogenous in design and quality. Included tasks were overground walking (n=44), running (n=3), hopping/jumping/cutting (n=11) single-leg landing (n=7), and stair climbing (n=6). LOE incidence varied depending on functional activities (33.95-92.74%). LOE incidence did not vary depending on ACL status (67.26% vs. 65.90% vs. 62.57% for ACL intact, ACLD and ACLR, respectively).

We observed no difference in active LOE incidence according to ACL status. Importantly, the observed incidence for active LOE was reliably higher than previously reported rates for passive measures.

Given the discrepancy between active and passive LOE incidence, clinicians may advisably prioritise active ROM during ACL rehabilitation.

A. Eagles C. Erian S. Kermeci D. Lovell P.C.L. Weinrauch

Arthroscopic hip surgery is increasingly common in Australia. Hip arthroscopy is indicated for a range of diagnostic and therapeutic purposes, including labral tears, capsular laxity and femoral-acetabular impingement (FAI). Despite this, previous cohort studies aiming to characterise hip pathology seen on arthroscopic examination are mostly limited to patients with known diagnoses of FAI. Therefore, little is known of the native articular wear patterns encountered in other disease states. Therefore, we aimed to define common osteochondral wear patterns for a cohort of patients managed via hip arthroscopy.

We retrospectively analysed intraoperative data for 1127 patients managed via hip arthroscopy between 2008 and 2013, for either therapeutic or diagnostic purposes. Intraoperative data was categorized by location (A-E as defined by Fontana et al. 2016) and chondral damage (0-4 scale as defined by Beck et al. 2005) with respect to both acetabulum and femoral head.

Data for 1127 patients were included. Location of acetabular chondral pathology was variable with locations C1 and D1 representing the most common regions of damage. Labral tears predominated in locations C and D. Femoral chondral pathology was evenly distributed. The degree of femoral chondral injury was predominantly grade 1, whilst acetabular wear was evenly distributed.

Large proportions of wear were observed at the peripheral superior and anterior regions of the lunate surface of the acetabulum in keeping with prior works. However, we observed higher rates of central wear and lower rates of grade 4 acetabular damage extending into superior/posterior zones, in our cohort.

Our work characterises common articular wear patterns encountered at the time of hip arthroscopy. Further inquiry into the natural history of osteochondral lesions is needed to better understand and manage these conditions.

Chynna Gleeson M. Zhu C. Frampton S.W. Young V. Poutawera J. Mutu-Grigg

The New Zealand Joint Registry (NZJR) was established in 1999. However, ethnicity data was not recorded by prioritisation in line with Ministry of Health (MoH) recommendations. Recently, cross-referencing with MoH updated ethnicity data for all 326,150 entries in the NZJR database. The objective of this national level, population study was to identify any ethnic disparities in access and outcome for Māori for primary total hip (THA) and knee arthroplasty (TKA) for Osteoarthritis.

The utilisation rate for THA and TKAs were calculated for the Māori and NZ European population from all data in the NZJR and Census data in 2001, 2006, 2013 and 2018. Utilisation rate was reported separately for four age groups (<55, 55-64, 65-74, >75) over four time periods (1999-2004, 2005-2009, 2010-2014, 2015-2020). Revision rate, 6 months and 5-year Oxford scores were adjusted for age, sex and BMI, then compared between groups.

In every age group and at all but one time point, significant under-utilisation of TKA was observed in Māori. For THAs, Māori had similar utilisation rates in the <55 and 55-64 age groups, but significantly lower utilisation rates in all other age groups.

When adjusted for age, sex and BMI, no significant differences in revision rates were observed between Māori and NZ Europeans for THAs (HR 0.939, P 0.417) or TKAs (HR 1.129, P 0.149). Adjusted 6 months and 5-year Oxford scores were significantly higher in NZ Europeans, however, the maximum difference was less than 3 points and is unlikely to be clinically significant.

Despite the same risk of being diagnosed with osteoarthritis, Māori are less likely to undergo THA and TKA. There are no clinically significant differences in outcomes post arthroplasty between Māori and NZ Europeans. Further research is required to investigate causes for lower utilisation in Māori.

C. Di Bella

3D printing and Bioprinting technologies are becoming increasingly popular in surgery to provide a solution for the regeneration of healthy tissues. The aim of our project is the regeneration of articular cartilage via bioprinting means, to manage isolated chondral defects.

Chrondrogenic hydrogel (chondrogel: GelMa + TGF-b3 and BMP6) was prepared and sterilised in our lab following our standard protocols. Human adipose-derived mesenchymal stem cells were harvested from the infrapatellar fat pad of patients undergoing total knee joint replacements and incorporated in the hydrogel according to our published protocols. The chondrogenic properties of the chondrogel have been tested (histology, immunohistochemistry, PCR, immunofluorescence, gene analysis and 2nd harmonic generation microscopy) in vitro and in an ex-vivo model of human articular defect and compared with standard culture systems where the growth factors are added to the media at repeated intervals.

The in-vitro analysis showed that the formation of hyaline cartilage pellet was comparable between the two strategies, with a similar metabolic activity of the cells. These results have been confirmed in the ex-vivo model: hyaline-like cartilage was observed within the chondral defect in both the chondrogel group and the control group after 28 days in culture.

The use of bioprinting techniques in vivo requires the ability of stem cells to access growth factors directly in the environment they are in, as opposed to in vitro techniques where these factors are provided externally at recurrent intervals. This study showed the successful strategy of incorporating chondrogenic growth factors for the formation of hyaline-like cartilage in vitro and in an ex-vivo model of chondral loss.

The incorporation of chondrogenic growth factors in a hydrogel is a possible strategy for articular cartilage regeneration.

C. Honeywill L. Salmon L. Pinczewski K. Sundaraj J. Roe

The aim of this study was to determine Anterior Cruciate Ligament (ACL) graft and contralateral ACL (CACL) survival in patients who have undergone ACL reconstruction (ACLR) with hamstring autograft following netball injuries, and determine factors associated with repeat ACL injury and return to netball.

From a prospectively collected database, a consecutive series of 332 female netballers who underwent primary ACLRs using hamstring autografts were identified. Subjects were surveyed at a minimum of five years following reconstruction, including details of further ACL injuries to either knee, return to netball or other sports and psychological readiness with the ACL-RSI score.

264 participants (80%) were reviewed at the mean follow up of 9 years (60-180 months). There were 12 ACL graft ruptures (5%) and 35 contralateral ACL ruptures (13%). ACL graft survival was 97% and 97%, 96% at 2, 5 and 7 years respectively. CACL survival was 99%, 94%, and 90% at 2, 5 and 7 years respectively. The 7-year ACL graft survival was 97% in those 25 or more and 93% in those under 25 years (p=0.126). The 7-year CACL survival was 93% in those 25 or more and 85% in those under 25 years (HR 2.6, 95%CI 1.3-5.0, p=0.007). A family history of ACL injury was reported by 32% of participants. A return to netball was reported by 61% of participants. The mean ACL-RSI score was 65 in those who returned to netball and 37 in those who did not (p=0.001).

ACLR with hamstring autografts is a reliable procedure for netballers with a survival rate of 96% at 7 years, allowing 63% of participants to return to netball. A successful return to sport was associated with greater psychological readiness. CACL injury occurred with more than double the frequency of ACL graft rupture and was increased by 2.6x in those <25 years.

D.P. Lewis S.M. Tarrant D. Dewar Z.J. Balogh

Prosthetic joint infections (PJI) are devastating complications. Our knowledge on hip fractureassociated hemiarthroplasty PJI (HHA-PJI) is limited compared to elective arthroplasty. The goal of this study was to describe the epidemiology, risk factors, management, and outcomes for HHA-PJI.

A population-based (465,000) multicentre retrospective analysis of HHAs between 2006-2018 was conducted. PJI was defined by international consensus and treatment success as no return to theatre and survival to 90 days after the initial surgical management of the infection. Univariate, survival and competing risk regression analyses were performed.

1852 HHAs were identified (74% female; age:84±7yrs;90-day-mortality:16.7%). Forty-three (2.3%) patients developed PJI [77±10yrs; 56% female; 90-day-mortality: 20.9%, Hazard-Ratio 1.6 95%CI 1.1-2.3,p=0.023]. The incidence of HHA-PJI was 0.77/100,000/year and 193/100,000/year for HHA. The median time to PJI was 26 (IQR 20-97) days with 53% polymicrobial growth and 41% multi-drug resistant organisms (MDRO). Competing risk regression identified younger age [Sub-Hazard-Ratio(SHR) 0.86, 95%CI 0.8-0.92,p<0.001], chronic kidney disease (SHR 3.41 95%CI 1.36-8.56, p=0.01), body mass index>35 (SHR 6.81, 95%CI 2.25-20.65, p<0.001), urinary tract infection (SHR 1.89, 95%CI 1.02-3.5, p=0.04) and dementia (SHR 9.4, 95%CI 2.89-30.58,p<0.001) as significant risk factors for developing HHA-PJI. When infection treatment was successful (n=15, 38%), median survival was 1632 days (IQR 829-2084), as opposed to 215 days (IQR 20-1245) in those who failed, with a 90-day mortality of 30%(n=12). There was no significant difference in success among debridement, excision arthroplasty or revision arthroplasty.

HHA PJI is uncommon but highly lethal. All currently identified predictors are non-modifiable. Due to the common polymicrobial and MDRO infections our standard antibiotic prophylaxis may not be adequate HHA-PJI is a different disease compared to elective PJI with distinct epidemiology, pathogens, risk factors and outcomes, which require targeted research specific to this unique population.

D. Goddard-Hodge J. Baker

Reduced cervical spine canal AP diameter is linked to the development of spinal cord injury and myelopathy. This is of particular interest to clinicians in New Zealand, given a unique socio-ethnic make-up and prevalent participation in collision sport. Our study builds upon previous unpublished evidence, by analysing normal cervical spine CT scans to explore morphological differences in the sub-axial cervical spine canal, between New Zealand European, Māori and Paciāca individuals.

670 sub-axial cervical vertebrae (C3-C7) were analysed radiographically using high resolution CT trauma scans, showing no acute pathology with respect to the cervical spine. All measurements were made uPlising mulP-planar reconstruction software to obtain slices parallel to the superior endplate at each vertebral level. Maximal canal diameter was measured in the AP and transverse planes. Statistical analysis was performed using analysis of variance (ANOVA).

We included 250 Maori, 250 NZ European and 170 Paciāca vertebrae (455 male, 215 female). Statistically and clinically signiācant differences were found in sagittal canal diameter between all ethnicities, at all spinal levels. NZ European vertebrae demonstrated the largest AP diameter and Paciāca the smallest, at all levels. Transverse canal diameter showed no signiācant difference between ethnicities, however the raatio of AP:transverse diameter was signiācantly different at all spinal levels except C3. Subjective morphological differences in the shape of the vertebral canal were noted, with Māori and Paciāca patients tending towards a flatter, curved canal shape.

A previous study of 166 patients (Coldham, G. et al. 2006) found cervical canal AP diameter to be narrower in Māori and Paciāca patients than in NZ Europeans. Our study, evaluating the normal population, conārms these differences are likely reflecPve of genuine variation between these ethniciPes. Future research is required to critically evaluate the morphologic differences noted during this study.

D. Vaotuua P. O'Connor M. Belford P. Lewis A. Hatton M. McAuliffe

Deep infection is a devastating complication of total knee arthroplasty (TKA). This study aimed to determine if there was a relationship between surgeon volume and the incidence of revision for infection after primary TKA.

Data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from 1 September 1999 to 31 December 2020 for primary TKA for osteoarthritis that were revised for infection. Surgeon volume was defined by the number of primary TKA procedures performed by the surgeon in the year the primary TKA was performed and grouped as <25, 25-49, 50-74, 75-99, >100 primary TKA procedures per year. Kaplan Meir estimates for cumulative percent revision (CPR) and Cox Proportional Hazard Ratios were performed to compare rates of revision for infection by surgeon volume, with sub-analyses for patella and polyethylene use, age <65 years and male gender.

5295 of 602,919 primary TKA for osteoarthritis were revised for infection. High volume surgeons (>100 TKA/year) had a significantly lower rate of revision for infection with a CPR at 1 and 17 years of 0.4% (95% CI 0.3, 0.4) and 1.5% (95% CI 1.2, 2.0), respectively, compared with 0.6% (95% CI 0.5, 0.7) and 2.1% (95% CI 1.8, 2.3), respectively, for low volume surgeons (<25 TKR/year). Differences between the high-volume group and the remaining groups remained when sub-analysis for age, gender, ASA, BMI, patella resurfacing and the use of cross-linked polyethylene (XLPE).

High volume surgeons have lower rates of revision for infection in primary TKA.

D.R.J. Gill S. Corfield D. Harries R.S. Page

We compared the rate of revision of two classes of primary anatomic shoulder arthroplasty, stemmed (aTSA) and stemless (sTSA) undertaken with cemented all polyethylene glenoid components.

A large national arthroplasty registry identified two cohort groups for comparison, aTSA and sTSA between 1st January 2011 and 31st December 2020. A sub-analysis from 1 January 2017 captured additional patient demographics. The cumulative percentage revision (CPR) was determined using Kaplan-Meier estimates of survivorship and hazard ratios (HR) from Cox proportional hazard models adjusted for age and gender.

Of the 7,533 aTSA procedures, the CPR at 8 years was 5.3% and for 2,567 sTSA procedures was 4.0%. There was no difference in the risk of revision between study groups (p=0.128).

There was an increased risk of revision for aTSA and sTSA undertaken with humeral head sizes <44mm (p=0.006 and p=0.002 respectively). Low mean surgeon volume (MSV) (<10 cases per annum) was a revision risk for aTSA (p=0.033) but not sTSA (p=0.926).

For primary diagnosis osteoarthritis since 2017, low MSV was associated with an increased revision risk for aTSA vs sTSA in the first year (p=0.048). Conversely, low MSV was associated with a decreased revision risk for sTSA in the first 6 months (p<0.001). Predominantly aTSA was revised for loosening (28.8%) and sTSA for instability/dislocation (40.6%).

Revision risk of aTSA and sTSA was associated with humeral head size and mean surgeon volume but not patient characteristics. Inexperienced shoulder arthroplasty surgeons experience lower early revision rates with sTSA in the setting of osteoarthritis. Revision of aTSA and sTSA occurred for differing reasons.

D. Ramage A.G. Burgess A. Powell Z.J. Tangrood

Ankle fractures represent the third most common fragility fracture seen in elderly patients following hip and distal radius fractures. Non-operative management of these see complication rates as high as 70%. Open reduction and internal fixation (ORIF) has complication rates of up to 40%. With either option, patients tend to be managed with a non-weight bearing period of six weeks or longer. An alternative is the use of a tibiotalocalcaneal (TTC) nail. This provides a percutaneous treatment that enables the patient to mobilise immediately. This case-series explores the efficacy of this device in a broad population, including the highly comorbid and cognitively impaired.

We reviewed patients treated with TTC nail for acute ankle fractures between 2019 and 2022. Baseline and surgical data were collected. Clinical records were reviewed to record any post-operative complication, and post-operative mobility status and domicile. 24 patients had their ankle fracture managed with TTC nailing. No intra-operative complications were noted. There were six (27%) post-operative complications; four patients had loosening of a distal locking screw, one significant wound infection necessitating exchange of nail, and one pressure area from an underlying displaced fracture fragment. All except three patients returned to their previous domicile. Just over two thirds of patients returned to their baseline level of mobility.

This case-series is one of the largest and is also one of the first to include cognitively impaired patients. Our results are consistent with other case-series with a favourable complication rate when compared with ORIF in similar patient groups. The use of a TTC nail in the context of acute, geriatric ankle trauma is a simple and effective treatment modality. This series shows acceptable complication rates and the majority of patients are able to return to their baseline level of mobility and domicile.

D. Hancock D. Morley M. Wyatt P. Roberts J. Zhang J. van Dalen

When removing femoral cement in revision hip surgery, creating an anterior femoral cortical window is an attractive alternative to extended trochanteric osteotomy. We describe our experience and evolution of this technique, the clinical and radiological results, and functional outcomes.

Between 2006 and 2021 we used this technique in 22 consecutive cases at Whanganui Hospital, New Zealand. The average age at surgery was 74 years (Range 44 to 89 years). 16 cases were for aseptic loosening: six cases for infection.

The technique has evolved to be more precise and since 2019 the combination of CT imaging and 3-D printing technology has allowed patient-specific (PSI) jigs to be created (6 cases). This technique now facilitates cement removal by potentiating exposure through an optimally sized anterior femoral window.

Bone incorporation of the cortical window and functional outcomes were assessed in 22 cases, using computer tomography and Oxford scores respectively at six months post revision surgery. Of the septic cases, five went onto successful stage two procedures, the other to a Girdlestone procedure.

On average, 80% bony incorporation of the cortical window occurred (range 40 −100%). The average Oxford hip score was 37 (range 22 – 48). Functional outcome (Oxford Hip) scores were available in 11 cases (9 pre-PSI jig and 2 using PSI jig). There were two cases with femoral component subsidence (1 using the PSI jig).

This case series has shown the effectiveness of removing a distal femoral cement mantle using an anterior femoral cortical window, now optimized by using a patient specific jig with subsequent reliable bony integration, and functional outcomes comparable with the mean score for revision hip procedures reported in the New Zealand Joint Registry.

D. Daly R. Maxwell

The purpose of this study is to assess the long term results of combined ACL reconstruction and unicompartmental knee replacements (UKR). These patients have been selected for this combined operation due to their combination of instability symptoms from an absent ACL and unicompartmental arthritis.

Retrospective review of 44 combined UKR and ACL reconstruction by a single surgeon. Surgeries included both medial and lateral UKR combined with either revision ACL reconstruction or primary ACL reconstruction. Patient reported outcomes were obtained preoperatively, at one year, 5 years and 10 years. Revision rate was followed up over 13 years for a mean of 7.4 years post-surgery.

The average Oxford score at one year was 43 with an average increase from pre-operation to 1 year post operation of 15. For the 7 patients with 10 year follow up average oxford score was 42 at 1 year, 43 at 5 years and 45 at 10 years.

There were 5 reoperations. 2 for revision to total knee arthroplasty and 1 for an exchange of bearing due to wear. The other 2 were the addition of another UKR. For those requiring reoperation the average time was 8 years.

Younger more active patients presenting with ACL deficiency causing instability and unicompartmental arthritis are a difficult group to manage. Combining UKR and ACL reconstruction has scant evidence in regard to long term follow up but is a viable option for this select group. This paper has one of the largest cohorts with a reasonable follow up averaging 7.4 years and a revision rate of 11 percent.

Combined unilateral knee replacements and ACL reconstruction can be a successful operation for patients with ACL rupture causing instability and unicompartmental arthritis.

E. Barrass J.L. Lin J. Lynch K. Fielding

Aboriginal and Torres Strait Islander (ATSI) people have higher elective wait times compared to non-ATSI population in Australia. The Murrumbidgee Local Health District (MLHD) in southern New South Wales services 125,242km2 and a population of 287,000 people, with 5.8% identifying as ATSI. The aim of this study is to investigate the arthroplasty waitlist time of ATSI, and the impact of rurality on joint replacement, within the MLHD and compared to the Australian national data.

1435 consecutive patients who underwent elective hip or knee arthroplasty from July 2018 to June 2021 were collated. Demographics, ATSI status, total wait time, readiness for care, and rurality were collected. Rurality was measured by distance from the arthroplasty hospital within MLHD. 1,151 patients were included after excluding patients with missing data or underwent emergent surgery.

Within this cohort, 72 of 1,151 patients (6.2%) identified as ATSI. ATSI were younger than non-ATSI population (60.7y v 66.4y). There was no difference between Aboriginal status and ready for care wait time (368.0 v 349.9 days; p=0.116). The rurality of the groups was similar and increasing rurality did not affect total wait time (ATSI 103.1km v 98.6km; p=0.309). There was no difference in total or not-ready-for-care time between the groups (p: 0.68).

Findings suggest equitable access to joint arthroplasty in the MLHD between ATSI and non-ATSI populations, which differs from the national experience. There is no significant difference between rurality and accessibility in the MLHD. This may be a result of the increased focus to ATSI and rural health within the district. A state or national study would be beneficial in identifying high performing regions and reviewing processes that enable equitable and accessible care.

MLHD provides equitable access to arthroplasty surgery between ATSI and non-ATSI, as well as patients from rural areas within the LHD.

E. Jewell S. Martin C. Metusela C. Scholes

Novel oral anticoagulant (NOAC) use in Australia has increased significantly since their introduction to the Pharmaceutical Benefits Scheme (PBS). Currently, there are no specific guidelines regarding recommencement of NOAC therapy post-operatively for patients concurrently on a NOAC and undergoing arthroplasty. To address this gap in the literature, the aim of this study was to compare the clinical and patient-reported outcomes in a patient cohort recommencing a therapeutic dose of NOAC within 24 hours of total hip or knee arthroplasty.

Data was retrieved from a prospective registry (ACTRN1262000079698) containing hip and knee arthroplasties. Cases were labelled based on whether they presented on a therapeutic dose of NOAC prior to surgery or not. Descriptive statistics were used to summarise patient outcomes.

Of 291 patients undergoing 331 primary arthroplasties, 9.3% were undertaking NOAC therapy prior to their surgery. In the NOAC cohort, there was a 34.5% adverse event rate, however on closer analysis of each event, it was found that none of these events were complications in relation to NOAC use. This was compared to 15.6% of the comparison cohort who experienced a range of complications, some involving bleeding events. PROMs improved to a similar degree amongst both groups.

This study showed that recommencing therapeutic doses of NOACs in patients post hip and knee arthroplasty within 24 hours was safe. These findings will help guide larger scale analysis to better inform clinical guidelines pertaining to hip and knee arthroplasty.

E.C. Lourens A.P. Kurmis C. Holder R. N. de Steiger

Total hip arthroplasty (THA) is an effective treatment for symptomatic hip osteoarthritis (OA). Computer-navigation technologies in total knee arthroplasty show evidence-supported survivorship advantages and are used widely. The aim of this study was to determine the revision outcome of hip commercially available navigation technologies.

Data from the Australian Orthopaedic Association National Joint Replacement Registry from January 2016 to December 2020 included all primary THA procedures performed for osteoarthritis (OA). Procedures using the Intellijoint HIP® navigation were identified and compared to procedures inserted using ‘other’ computer navigation systems and to all non-navigated procedures. The cumulative percent revision (CPR) was compared between the three groups using Kaplan-Meier estimates of survivorship and hazard ratios (HR) from Cox proportional hazards models, adjusted for age and gender. A prosthesis specific analysis was also performed.

There were 1911 procedures that used the Intellijoint® system, 4081 used ‘other’ computer navigation, and 160,661 were non-navigated. The all-cause 2-year CPR rate for the Intellijoint HIP® system was 1.8% (95% CI 1.2, 2.6), compared to 2.2% (95% CI 1.8, 2.8) for other navigated and 2.2% (95% CI 2.1, 2.3) for non-navigated cases. A prosthesis specific analysis identified the Paragon/Acetabular Shell THAs combined with the Intellijoint HIP® system as having a higher (3.4%) rate of revision than non-navigated THAs (HR = 2.00 (1.01, 4.00), p=0.048).

When this outlier combination was excluded, the Intellijoint® system group demonstrated a two-year CPR of 1.3%. There was no statistical difference in the CPR between the three groups before or after excluding Paragon/Acetabular Shell system.

The preliminary data presented demonstrate no statistical difference in all cause revision rates when comparing the Intellijoint HIP® THA navigation system with ‘other’ navigation systems and ‘non-navigated’ approaches for primary THAs performed for OA. The current sample size remains too small to permit meaningful subgroup statistical comparisons.

E.C. Lourens A.P. Kurmis D. Harries R. N. de Steiger

Total hip arthroplasty (THA) is an effective treatment for symptomatic hip osteoarthritis (OA). While computer-navigation technologies in total knee arthroplasty show survivorship advantages and are widely used, comparable applications within THA show far lower utilisation. Using national registry data, this study compared patient reported outcome measures (PROMs) in patients who underwent THA with and without computer navigation.

Data from Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) PROMs program included all primary THA procedures performed for OA up to 31 December 2020. Procedures using the Intellijoint HIP® navigation system were identified and compared to procedures using other computer navigation systems or conventional instrumentation only. Changes in PROM scores between pre-operative and 6-month post-operative time points were analysed using multiple regression model, adjusting for pre-operative score, patient age, gender, ASA score, BMI, surgical approach, and hospital type.

There were 65 primary THA procedures that used the Intellijoint HIP® system, 90 procedures used other types of computer navigation, and the remaining 5,284 primary THA procedures used conventional instrumentation. The estimated mean changes in the EuroQol visual analogue scale (EQ VAS) score and Oxford Hip score did not differ significantly when Intellijoint® was compared to conventional instruments (estimated differences of 2.4, 95% CI [-1.7, 6.5], p = 0.245, and −0.5, 95% CI [-2.5, 1.4], p = 0.592, respectively). The proportion of patients who were satisfied with their procedure was also similar when Intellijoint® was compared to conventional instruments (rate ratio 1.06, 95% CI [0.97, 1.16], p = 0.227).

The preliminary data demonstrate no significant difference in PROMs when comparing the Intellijoint HIP® THA navigation system with both other navigation systems and conventional instrumentation for primary THAs performed for OA. Level of evidence: III (National registry analysis)

E.C. Lourens A.P. Kurmis D. Harries P.L. Lewis

Strategy regarding patella resurfacing in total knee replacement (TKR) remains controversial. TKR revision rates are reportedly influenced by surgeon procedure volume. The study aim was to compare revision outcomes of TKR with and without patella resurfacing in different surgeon volume groups using data from the AOANJRR.

The study population included 571,149 primary TKRs for osteoarthritis. Surgeons were classified as low, medium, or high-volume based on the quartiles of mean primary TKR volume between 2011 and 2020. Cumulative percent revision (CPR) using Kaplan-Meier estimates of survivorship were calculated for the three surgeon volume groups with and without patella resurfacing. Cox proportional hazards models, adjusted for age and sex, were used to compare revision risks.

High-volume surgeons who did not resurface the patella had the highest all-cause CPR (20-year CPR 10.9%, 95% CI [10.0%, 12.0%]). When the patella was resurfaced, high-volume surgeons had the lowest revision rate (7.3%, 95% CI [6.4%, 8.4%]). When the high-volume groups were compared there was a higher rate of revision for the non-resurfaced group after 6 months. When the medium-volume surgeon groups were compared, not resurfacing the patella also was associated with a higher rate of revision after 3 months. The low-volume comparisons showed an initial higher rate of revision with patella resurfacing, but there was no difference after 3 months. When only patella revisions were considered, there were higher rates of revision in all three volume groups where the patella was not resurfaced.

TKR performed by high and medium-volume surgeons without patella resurfacing had higher revision rates compared to when the patella was resurfaced. Resurfacing the patella in the primary procedure protected against revision for patella reasons in all surgeon volume groups.

Level of evidence: III (National registry analysis)

E. Scherf

This qualitative study aims to explore and highlight the experiences of trainees in the Orthopaedic Surgical Education Training (SET) program in New Zealand, with a focus on identifying gender-specific biases which may impact professional development.

Orthopaedic SET trainees in New Zealand were invited to complete a qualitative, semi-structured questionnaire exploring their experiences in the Orthopaedic SET program. A broad range of topics were covered, addressing culture, belonging, learning styles and role modelling. Recurrent themes were identified using inductive methods.

Analysis of questionnaire responses identified several key themes for women in the Orthopaedic SET program, compared to their male counterparts, including (1) role incredulity, (2) confidence vs. competence, (3) adaptation, (4) interdisciplinary relationships and (5) role modelling. Female participants described experiencing gender bias or discrimination by both patients and interdisciplinary colleagues at a higher rate than their male counterparts. The majority of female participants described feeling as competent as their male counterparts at the same SET level, however, identified that they do not typically exhibit the same confidence in their surgical abilities. Whilst similar numbers of female and male participants described experiencing barriers to career progression, female participants described having to adapt both physically and socially to overcome additional gender-specific barriers. Positive influences on training experience included role modelling and supportive relationships amongst trainee groups.

This study highlighted gender-specific biases experienced by trainees in the Orthopaedic SET program in New Zealand. Further investigation is warranted to determine how these experiences affect professional development, and how they may be addressed to foster increased gender equity in the surgical profession. This will likely require system-level interventions to create meaningful and sustainable culture change.

F. Zaidi

Excessive postoperative opioid prescribing is a significant contributor to the opioid crisis. Prescribing in orthopaedic surgery is often further complicated by high use of opioid-based preoperative analgesia. ‘Opioid PrEscRiptions and usage After Surgery’ (OPERAS) is an international multicentre prospective student- and trainee-led collaborative study which aims to quantify the amount of opioids prescribed at discharge after common orthopaedic surgeries against what is consumed by patients at 7-days, and assess the impact of opioids on patient-reported outcomes.

Data is being collected over 6 14-day periods on consecutive adult patients undergoing shoulder arthroplasty, rotator cuff repair, shoulder labral repair, anterior cruciate ligament repair, hip arthroplasty, and knee arthroplasty, with follow-up via telephone call at 7-days after discharge. The primary outcome is the proportion of oral morphine equivalents (OME) of prescribed opioids versus consumed opioids at 7-days post-discharge.

This ongoing study is actively recruiting in over 20 countries. Globally, 65 centres are collecting orthopaedic, including 10 New Zealand centres and 17 Australian centres. To date, 284 orthopaedic patients have been prospectively enrolled with complete data (mean age 59.6 ± 16.7 years; 51.6% female). Overall, 77% and 89% of patients were prescribed opioids on discharge in New Zealand and Australia respectively. On average, 60% of prescribed opioids were consumed at 7-days post-discharge globally (150 OME (75-500) vs. 90 OME (15-200); p<0.01). In New Zealand and Australia, 42.1% (285 OME (150-584) vs. 120 OME (6-210); p<0.01) and 63.3% (150 OME (86-503) vs. 95 OME (28-221); p<0.01) of prescribed opioids were consumed at 7-days, respectively.

OPERAS will provide the first high-quality global data on opioid prescription and consumption patterns with patient perspectives. These data can inform prescribing practice and inform guidelines. The growing interest in New Zealand and Australia in student- and trainee-led orthopaedic collaborative research, as evidenced by this study should be actively encouraged and fostered.

F. Zaidi S.M. Bolam T.C. Yeung T.F. Besier M. Hanlon J.T. Munro A.P. Monk

Patient-reported outcome measures (PROMs) have failed to highlight differences in function or outcome when comparing knee replacement designs and implantation techniques. Ankle-worn inertial measurement units (IMUs) can be used to remotely measure and monitor the bi-lateral impact load of patients, augmenting traditional PROMs with objective data. The aim of this study was to compare IMU-based impact loads with PROMs in patients who had undergone conventional total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), and robotic-assisted TKA (RA-TKA).

77 patients undergoing primary knee arthroplasty (29 RA-TKA, 37 TKA, and 11 UKA) for osteoarthritis were prospectively enrolled. Remote patient monitoring was performed pre-operatively, then weekly from post-operative weeks two to six using ankle-worn IMUs and PROMs. IMU-based outcomes included: cumulative impact load, bone stimulus, and impact load asymmetry. PROMs scores included: Oxford Knee Score (OKS), EuroQol Five-dimension with EuroQol visual analogue scale, and the Forgotten Joint Score.

On average, patients showed improved impact load asymmetry by 67% (p=0.001), bone stimulus by 41% (p<0.001), and cumulative impact load by 121% (p=0.035) between post-operative week two and six. Differences in IMU-based outcomes were observed in the initial six weeks post-operatively between surgical procedures. The mean change scores for OKS were 7.5 (RA-TKA), 11.4 (TKA), and 11.2 (UKA) over the early post-operative period (p=0.144). Improvements in OKS were consistent with IMU outcomes in the RA-TKA group, however, conventional TKA and UKA groups did not reflect the same trend in improvement as OKS, demonstrating a functional decline.

Our data illustrate that PROMs do not necessarily align with patient function, with some patients reporting good PROMs, yet show a decline in cumulative impact load or load asymmetry. These data also provide evidence for a difference in the functional outcome of TKA and UKA patients that might be overlooked by using PROMs alone.

Y.Y.F. Tong S. Holmes A. Sefton1

There is conjecture on the optimal timing to administer bisphosphonate therapy following operative fixation of low- trauma hip fractures. Factors include recommendations for early opportunistic commencement of osteoporosis treatment, and clinician concern regarding the effect of bisphosphonates on fracture healing. We performed a systematic review and meta-analysis to determine if early administration of bisphosphonate therapy within the first month post-operatively following proximal femur fracture fixation is associated with delay in fracture healing or rates of delayed or non-union.

We included randomised controlled trials examining fracture healing and union rates in adults with proximal femoral fractures undergoing osteosynthesis fixation methods and administered bisphosphonates within one month of operation with a control group. Data was pooled in meta-analyses where possible. The Cochrane Risk of Bias Tool and the GRADE approach were used to assess validity.

For the outcome of time to fracture union, meta-analysis of three studies (n= 233) found evidence for earlier average time to union for patients receiving early bisphosphonate intervention (MD = −1.06 weeks, 95% CI −2.01 – −0.12, I2= 8%). There was no evidence from two included studies comprising 718 patients of any difference in rates of delayed union (RR 0.61, 95% CI 0.25–1.46). Meta-analyses did not demonstrate a difference in outcomes of mortality, function, or pain.

We provide low-level evidence that there is no reduction in time to healing or delay in bony union for patients receiving bisphosphonates within one month of proximal femur fixation.

F Cosic N Kirzner E Edwards R Page L Kimmel B Gabbe

Proximal humerus fracture dislocations are amongst the most severe proximal humerus injuries, presenting a challenging management problem. The aim of this study was to report on the long-term outcomes of the management of proximal humerus fracture dislocations.

Patients with a proximal humerus fracture dislocation managed at a Level 1 trauma centre from January 2010 to December 2018 were included. Patients with an isolated tuberosity fracture dislocation or a pathological fracture were excluded. Outcome measures were the Oxford Shoulder Score (OSS), EQ-5D-5L, return to work, and radiological outcomes. Complications recorded included further surgery, loss of position/fixation, non-union/malunion, and avascular necrosis.

A total of 69 patients were included with a proximal humerus fracture dislocation in the study period; 48 underwent surgical management and 21 were managed with closed reduction alone. The mean (SD) age of the cohort was 59.7 (±20.4), and 54% were male. Overall patients reported a mean OSS of 39.8 (±10.3), a mean EQ-5D utility score of 0.73 (±0.20), and 78% were able to return to work at a median of 1.2 months. There was a high prevalence of complications in both patients managed operatively or with closed reduction (25% and 38% respectively). In patients undergoing surgical management, 21% required subsequent surgery.

Patient reported outcome measures post proximal humerus fracture dislocations do not return to normal population levels. These injuries are associated with a high prevalence of complications regardless of management. Appropriate patient counselling should be undertaken before embarking on definitive management.

F Cosic N Kirzner E Edwards R Page L Kimmel B Gabbe

There is very limited literature describing the outcomes of management for proximal humerus fractures with more than 100% displacement of the head and shaft fragments as a separate entity. This study aimed to compare operative and non-operative management of the translated proximal humerus fracture.

A prospective cohort study was performed including patients managed at a Level 1 trauma centre between January 2010 to December 2018. Patients with 2, 3 and 4-part fractures were included based on the degree of translation of the shaft fragment (≥100%), resulting in no cortical contact between the head and shaft fragments. Outcome measures were the Oxford Shoulder Score (OSS), EQ-5D-5L, and radiological outcomes. Complications recorded included further surgery, loss of position/fixation, and non-union/malunion. Linear and logistic regression models were used to compare management options.

There were 108 patients with a proximal humerus fracture with ≥100% translation; 76 underwent operative management and 32 were managed non-operatively with sling immobilisation. The mean (SD) age in the operative group was 54.3 (±20.2) and in the non-operative group was 73.3 (±15.3) (p<0.001). There was no association between OSS and management options (mean 38.5(±9.5) operative vs mean 41.3 (±8.5) non-operative, p=0.48). Operative management was associated with improved health status outcomes; EQ-5D utility score adjusted mean difference 0.16 (95%CI 0.04-0.27, p=0.008); EQ-5D VAS adjusted mean difference 19.2 (95%CI 5.2-33.2, p=0.008). Operative management was further associated with a lower odds of non-union (adjusted OR 0.30, 95%CI 0.09-0.97, p=0.04), malunion (adjusted OR 0.14, 95%CI 0.04-0.51, p=0.003) and complications (adjusted OR 0.07, 95%CI 0.02-0.32, p=0.001).

Translated proximal humerus fractures with ≥100% displacement demonstrate improved health status and radiological outcomes following surgical fixation. Patients with this injury should be considered for operative intervention.

F. Hollman, J. Mohammad N. Singh A. Gupta K. Cutbush

Acromioclavicular joint (ACJ) dislocations is a common disorder amongst our population for which numerous techniques have been described. It is thought that by using this novel technique combining a CC and AC repair with a reconstruction will result in high maintenance of anatomical reduction and functional results.

12 consecutive patients ACJ dislocations were included. An open superior clavicular approach is used. Firstly, the CC ligaments are repaired after which a CC reconstruction is performed using a tendon allograft. Secondly, the AC ligaments are repaired using an internal brace construct combined with a tendon allograft reconstruction (Figure 1).

The acute:chronic ratio was 6:6. Only IIIB, IV and V AC-joint dislocations were included. The Constant-Murley Score improved from 27.6 (8.0 – 56.5) up to 61.5 (42.0 – 92.0) at 12 months of follow up. Besides one frozen shoulder from which the patient recovered spontaneously no complications were observed with this technique. The CCD was reduced from 18.7 mm (13.0 – 24.0) to 10.0 mm (6.0 – 16.0) and 10.5 mm (8.0 – 14.0) respectively 12 weeks and 12 months postoperatively.

There is some evidence, suggesting to address as well as the vertical (coracoclavicular (CC) ligaments) as the horizontal (acromioclavicular (AC) ligaments) direction of instability. This study supports addressing both entities however comparative studies discriminating chronic as acute cases should be conducted to further clarify this ongoing debate on treating ACJ instability.

This study describes a novel technique to treat acute and chronic Rockwood stage IIIB – IV ACJ dislocations with promising short-term clinical and radiological results. This suggests that the combined repair and reconstruction of the AC and CC ligaments is a safe procedure with low complication risk in experienced hands. Addressing the vertical as well as horizontal stability in ACJ dislocation is considered key to accomplish optimal long-term results.

F. Genel B. Brady S. Bossina M. McMullan S. Ogul P. Ko C. Vleeskens J. Ly G. Hassett A. Huang J. Penm S. Adie J. M. Naylor

There have been no studies assessing the acceptability of opioid tapering in the pre-arthroplasty setting. This qualitative study aimed to (1) explore barriers and facilitators to opioid tapering amongst patients with chronic non-cancer pain (CNCP), and (2) explore the similarities and differences in acceptability of opioid tapering between pre-arthroplasty patients and those participating in a biopsychosocial pain management program.

From January 2021, adult participants diagnosed with CNCP and taking opioids daily (any dose at time of screening for a period of 3 months) were recruited from either Fairfield Orthopaedic Hip and Knee Service (FOHKS) or Liverpool Hospital Pain Clinic (LHPC). Semi-structured interviews underwent thematic analysis using the framework method.

17 participants were recruited (FOHKS, n=9, mean age 67, female 77%, LHPC, n=8, mean age 54, female 63%). Both groups had participants who; (i) were reluctant to use opioid medications and used them out of “necessity”, (ii) were reluctant to taper due to concerns of worsening pain, quality of life, (iii) believed opioids were “toxins” causing bodily harm. Some FOHKS participants believed tapering should be a post-operative focus, whilst others believed tapering opioids pre-operatively will assist in post-op pain management. Few LHPC participants felt dependent/addicted to opioids, thus driving their intention to taper opioids.

The belief of tapering opioids causing worse pain was based on either previous experiences or concerns alone. Some FOHKS participants were more inclined to taper opioids if they were educated on the chronic and peri-operative risks associated with using opioids at time of arthroplasty.

Opioid users recognise the harms associated with chronic opioid use and believe they are used out of desperation for adequate analgesia, function, and quality of life. Tapering opioids in the pre-arthroplasty context may need coupling with patient education highlighting the importance of opioid tapering pre-operatively.

F. Genel N. Pavlovic A. Lewin R. Mittal A. Huang J. Penm A. Patanwala B. Brady S. Adie I. Harris J.M. Naylor

In the Unites States, approximately 24% of people undergoing primary total knee or total hip arthroplasty (TKA, THA) are chronic opioid users pre-operatively. Few studies have examined the incidence of opioid use prior to TKA/THA and whether it predicts outcomes post-surgery in the Australian context. The aim was to determine: (i) the proportion of TKA and THA patients who use opioids regularly (daily) pre-surgery; (ii) if opioid use pre-surgery predicts (a) complication and readmission rates to 6-months post-surgery, (b) patient-reported outcomes to 6-months post-surgery.

A retrospective cohort study was undertaken utilising linked individual patient-level data from two independent databases comprising approximately 3500 people. Patients had surgery between January 2013 and June 2018, inclusive at Fairfield and Bowral Hospitals.

Following data linkage, analysis was completed on 1185 study participants (64% female, 69% TKA, mean age 67 (9.9)). 30% were using regular opioids pre-operatively. Unadjusted analyses resulted in the following rates in those who were vs were not using opioids pre-operatively (respectively); acute adverse events (39.1% vs 38.6%), acute significant adverse events (5.3% vs 5.7%), late adverse events: (6.9% vs 6.6%), total significant adverse events: (12.5% vs 12.4%), discharge to inpatient rehab (86.4% vs 88.6%), length of hospital stay (5.9 (3.0) vs 5.6 (3.0) days), 6-month post-op Oxford Score (38.8 (8.9) vs 39.5 (7.9)), 6 months post-op EQ-VAS (71.7 (20.2) vs 76.7 (18.2), p<0.001), success post-op described as “much better” (80.2% vs 81.3%).

Adjusted regression analyses controlling for multiple co-variates indicated no significant association between pre-op opioid use and adverse events/patient-reported outcomes.

Pre-operative opioid use was high amongst this Australian arthroplasty cohort and was not associated with increased risk of adverse events post-operatively. Further research is needed in assessing the relationship between the amount of pre-op opioid use and the risk of post-operative adverse events.

F. Genel N. Pavlovic M. Boulus D. Hackett M. Gao K. Lau S. Dennis K. Gibson N. Shackel L. Gray G. Hassett A. Lewin K. Mills S. Ogul S. Deitsch C. Vleekens B. Brady R. Boland I. Harris V. Flood M. Piya S. Adie J.M. Naylor

Obesity is associated with worse outcomes following total knee/hip arthroplasty (TKA/TKA). This study aimed to determine the feasibility of a dietitian-led low-inflammatory weight-loss program for people with obesity awaiting arthroplasty.

Quasi-experimental pilot study enrolled people with obesity waitlisted for primary TKA/THA into ‘usual care’ (UC) or weight-loss (low-inflammatory diet) program (Diet). Recruitment occurred between July 2019 and February 2020 at Fairfield and Campbelltown Hospitals. Assessments at baseline, pre-surgery, time of surgery and 90-days following surgery included anthropometric measurements, patient-reported outcomes, serum biomarkers and 90-day postoperative complication rate.

97 people consented to the study (UC, n=47, mean age 67, BMI 37, TKA 79%; Diet, n=50, mean age 66, BMI 36, TKA 72%). Baseline characteristics indicated gross joint impairments and poor compliance with a low-inflammatory diet. Study feasibility criteria included recruitment rate (52%), proportion of diet patients that improved compliance to low-inflammatory diet by ≥10% (57%) and had ≥60% attendance of dietitian consultations (72%), proportion of patients who undertook serum biomarkers (55%).

By presurgery assessments, the diet group had more patients who cancelled their surgery due to symptom improvement (4 vs 0), reduced waist-circumference measurements, increased compliance with the Low-Inflammatory diet and preservation of physical activity parameters. More usual care participants experienced at least one postoperative complication to 90-days (59% vs 47%) and were discharged to inpatient rehabilitation (21% vs 11%). There was no difference in weight change, physical function, and patient-reported outcome measures from pre-surgery to 90-days post-surgery, and length of hospital stay.

Using pre-determined feasibility criteria, conducting a definitive trial is not feasible. However, intervention audit demonstrated high intervention fidelity.

Pilot data suggest our program may promote weight loss but the clinical effects for most are modest. Further research utilising a stronger intervention may be required to assess the effectiveness of a pre-arthroplasty weight-loss intervention.

G. Hooper W. Gillespie S. Maddumage D.L. Snell J. Williman

Our objective was to examine revision rates and patient reported outcome scores (PROMS) for cemented and uncemented primary total knee joint replacement (TKJR) at six months, one year and five years post-operatively. Patients and Methods: This matched cohort study involved secondary analyses of data collected as part of a large prospective observational study monitoring outcomes following knee replacement in Christchurch, New Zealand. Cemented and uncemented TKJR participants (n = 1526) were matched on age (± 5 years), sex and body mass index (BMI). From this larger sample, PROMS data, Oxford Knee Score and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), out to five years post-operatively were analysed for a matched subset of participants (n = 252).

The average age of participants was 67.9 years (SD 9.4, range 38-94). There were no differences between cemented and uncemented cohorts on the basis of age, sex, BMI or comorbidities, revision rates or PROMS outcomes. Cemented procedures had greater skin to skin times than uncemented procedures (p < 0.01). Unadjusted outcomes comparing risk for revision across the two participant cohorts did not significantly differ. Overall rates for revision were low (cemented 3.2% v uncemented 2.7%, p=0.70). Propensity adjusted associations between baseline characteristics (age, sex, BMI, comorbidity, baseline Oxford and baseline WOMAC scores) also revealed no differences in risk for revision at any post-operative timepoint.

In this large multi-surgeon matched cohort study there were no significant differences in functional outcomes or revision rates, when outcomes following modern cemented and uncemented TKJR were compared out to 5-year follow up. Based on our findings, uncemented TKJR is predictable irrespective of patient's age, BMI or gender

G Hooper D Thompson N Lash J Sharr D Faulkner C Frampton N Gilchrist

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in three morphologically different uncemented femoral stems designs to investigate whether one particular design resulted in improved preservation of BMDMethods: 119 patients were randomised to receive either a proximally coated dual taper wedge stem, a proximally coated anatomic stem or a fully coated collarless triple tapered stem. All surgeries were performed via the posterior approach with mobilization on the day of surgery. Dual energy x-ray absorptiometry scans (Lunar iDXA, GE Healthcare, Madison, WI) assessed BMD across the seven Gruen zones pre-operatively, and post-operatively at 6-weeks, 1-year, and 2-years and compared to the unoperated contralateral femur as a control. Patient reported outcome measures of pain, function and health were also included at these corresponding follow-ups.

BMD increased in zones one (2.5%), two (17.1%), three (13.0%), five (10%) and six (17.9%) for all stems. Greater preservation of BMD was measured on the lateral cortex (zone 2) for both the dual taper wedge and anatomic stems (p = 0.019). The dual taper wedge stem also demonstrated preservation of BMD in the medial calcar (zone 7) whilst the anatomic and triple taper stem declined in this region, however this was not statistically significant (p = 0.059). BMD decreased on average by 2.1% inthe mid-diaphysis region, distal to the stem tip (zone 4) for all implants. All stems performed equivalently at final follow-up in all patient reported outcome measures.

This study demonstrated maintenance of femoral BMD in three different cementless femoral stem designs, with all achieving excellent improvements in patient reported outcomes. There was no significant stress shielding observed, however longer follow-up is required to elucidate the impact of this finding on implant survivorship.

A Hannah E Henley C Frampton G Hooper

This study aimed to examine the changing trends in the reasons for total hip replacement (THR) revision surgery, in one country over a twenty-one year period, in order to assess whether changes in arthroplasty practices have impacted revision patterns and whether an awareness of these changes can be used to guide clinical practice and reduce future revision rates.

The reason for revision THR performed between January 1999 and December 2019 was extracted from the New Zealand Joint Registry (NZJR). The results were then grouped into seven 3-year periods to allow for clearer visualization of trends. The reasons were compared across the seven time periods and trends in prosthesis use, patient age, gender, BMI and ASA grade were also reviewed. We compared the reasons for early revision, within one year, with the overall revision rates.

There were 20,740 revision THR registered of which 7665 were revisions of hips with the index procedure registered during the 21 year period. There has been a statistically significant increase in both femoral fracture (4.1 – 14.9%, p<0.001) and pain (8.1 – 14.9%, p<0.001) as a reason for hip revision. While dislocation has significantly decreased from 57.6% to 17.1% (p<0.001). Deep infection decreased over the first 15 years but has subsequently seen further increases over the last 6 years. Conversely both femoral and acetabular loosening increased over the first 12 years but have subsequently decreased over the last 9 years. The rate of early revisions rose from 0.86% to 1.30% of all revision procedures, with a significant rise in revision for deep infection (13-33% of all causes, p<0.001) and femoral fracture (4-18%, p<0.001), whereas revision for dislocation decreased (59-30%, p<0.001). Adjusting for age and gender femoral fracture and deep infection rates remained significant for both (p<0.05). Adjusting for age, gender and ASA was only significant for infection.

The most troubling finding was the increased rate of deep infection in revision THR, with no obvious linked pattern, whereas, the reduction in revision for dislocation, aseptic femoral and acetabular loosening can be linked to the changing patterns of the use of larger femoral heads and improved bearing surfaces.

J.K. Ward C. Di Bella

For all the research into arthroplasty, provision of total knee arthroplasty (TKR) services based on gender in the Australian context is yet to be explored. International literature points toward a heavily gender biased provision of TKA services, skewed away from female patients. This research has aimed to assess the current experience of Australian female patients and to explore better assessment techniques that could provide more equitable services.

A retrospective cohort analysis has been conducted using pre-op PROMs data, where available, from the Australian National Joint Replacement Registry (AOANJRR), between 7 August 2018 and 31 December 2021, including: EQ VAS Health; Oxford Knee Score; joint pain; and KOOS-12. Data was adjusted for age, ASA score, BMI, primary diagnosis, public vs private hospital, surgeon gender and years of practice (as estimated from years of registry data available). Of 1,001,231 procedures performed, 27,431 were able to be analysed (12,300 male and 15,131 female).

Gender-based bias against female patients reached statistical significance across all PROM scores, according to the Kruskal-Wallis test of difference (p-value <0.0001). Males were more likely to undergo TKR than females, with odds ratios remaining statistically significant when adjusted for age, ASA score, BMI, primary diagnosis, and hospital type. Numbers were further analysed for surgeon years of recorded practice and surgeon gender with mixed results.

This study found that women were less likely to undergo TKR despite worse scores on every pre-op PROM available, thus we demonstrate a statistically significant gender-based bias against female patients. More effort needs to be made to identify the base of this bias and find new ways to assess patients that can provide more equitable provision of healthcare.

S. Bin Ghouth S. Williams S. Reid T. Besier N.S. Stott G. Handsfield

Cerebral palsy (CP) is a neural condition that impacts and impairs the musculoskeletal system. Skeletal muscles, particularly in the lower limb, have previously been shown to be significantly reduced in volume in CP compared to typical controls. Muscle volume is a gross measure, however, and does not capture shape characteristics which—if quantified—could offer a robust and novel assessment of how this condition impacts skeletal muscle form and function in CP. In this study, we used mathematical shape modelling to quantify not just size, but also the shape, of soleus muscles in CP and typically developing (TD) cohorts to explore this question.

Shape modelling is a mathematical technique used previously for bones, organs, and tumours. We obtained segmented muscle data from prior MRI studies in CP. We generated shape models of CP and TD cohorts and used our shape models to assess similarities and differences between the cohorts, and we statistically analysed shape differences.

The shape models revealed similar principal components (PCs), i.e. the defining mathematical features of each shape, yet showed greater shape variability within the CP cohort. The model revealed a distinct feature (a superior –> inferior shift of the broad central region), indicating the model could identify muscular features that were not apparent with direct observation. Two PCs dominated the differences between CP and TD cohorts: size and aspect ratio (thinness) of the muscle.

The distinct appearance characteristic in the CP model correspond to specific muscle impairments in CP to be discussed further. Overall, children with CP had smaller muscles that also tended to be long, thin, and narrow. Shape modelling captures shape features quantitatively, which indicate the ways that muscles are being impacted in CP. In the future, we hope to tailor this technique toward informing diagnosis and treatments in CP.

G. Kioa S. Hunter J. Blackett

Routine post-operative bloods following all elective arthroplasty may be unnecessary. This retrospective cohort study aims to define the proportion of post-operative tests altering clinical management.

Clinical coding identified all elective hip or knee joint replacement under Hawkes Bay District Health Board contract between September 2019-December 2020 (N=373). Uni-compartmental and bilateral replacements, procedures performed for cancer, and those with insufficient data were excluded. Demographics, perioperative technique, and medical complication data was collected. Pre- and post-operative blood tests were assessed. Outcome measures included clinical intervention for abnormal post-operative sodium (Na), creatinine (Cr), haemoglobin (Hb), or potassium (K) levels. A cost-benefit analysis assessed unnecessary testing.

350 patients were Included. Median age was 71 (range 34-92), with 46.9% male. Only 26 abnormal post-operative results required intervention (7.1%). 11 interventions were for low Na, 4 for low K, and 4 for elevated Cr. Only 7 patients were transfused blood products. Older age (p=0.009) and higher ASA (p=0.02) were associated with intervention of any kind. Abnormal preoperative results significantly predicted intervention for Na (p<0.05) and Cr (p<0.05). All patients requiring treatment for K used diuretic medication. Preoperative Hb level was not associated with need for transfusion. Overall, there were 1027 unnecessary investigations resulting in $18,307 excess expenditure.

Our study identified that the majority of elective arthroplasty patients do not require routine postoperative blood testing. We recommend investigations for patients with preoperative electrolyte abnormality, those taking diuretics, and patients with significant blood loss noted intra-operatively. In future, a larger, randomised controlled trial would be useful to confirm these factors.

K. Tetsworth N. Green G. Barlow M. Stubican F. Vindenes V. Glatt

Tibial pilon fractures are typically the result of high-energy axial loads, with complex intra- articular fractures that are often difficult to reconstruct anatomically. Only nine simultaneous pilon and talus fractures have been published previously, but we hypothesised the chondral surface of the dome is affected more frequently.

Data was acquired prospectively from 154 acute distal tibial pilon fractures (AO/OTA 43B/C) in adults. Radiographs, photographs, and intra-operative drawings of each case were utilised to document the presence of any macroscopic injuries of the talus. Detailed 1x1mm maps were created of the injuries in each case and transposed onto a statistical shape model of a talus; this enables the cumulative data to be analysed in Excel. Data was analysed using a Chi-squared test.

From 154 cases, 104 were considered at risk and their talar domes were inspected; of these, macroscopic injuries were identified in 55 (52.4%). The prevalence of talar dome injury was greater with B-type fractures (53.5%) than C-type fractures (31.5%) (ρ = .01). Injuries were more common in men than women and presented with different distribution of injuries (ρ = .032). A significant difference in the distribution of injuries was also identified when comparing falls and motor vehicle accidents (ρ = .007).

Concomitant injuries to the articular surface of the dome of the talus are relatively common, and this perhaps explains the discordance between the post-operative appearance following internal fixation and the clinical outcomes observed. These injuries were focused on the lateral third of the dome in men and MVAs, whereas women and fall mechanism were more evenly distributed.

Surgeons who operatively manage high-energy pilon fractures should consider routine inspection of the talar dome to assess the possibility of associated macroscopic osteochondral injuries.

H.S. Lee D.P. Lewis Z.J. Balogh

Distal femur fractures (DFF) are common, especially in the elderly and high energy trauma patients. Lateral locked osteosynthesis constructs have been widely used, however non-union and implant failures are not uncommon. Recent literature advocates for the liberal use of supplemental medial plating to augment lateral locked constructs. However, there is a lack of proprietary medial plate options, with some authors supporting the use of repurposing expensive anatomic pre-contoured plates. The aim of this study was to investigate the feasibility of a readily available cost-effective medial implant option.

A retrospective analysis from January 2014 to June 2022 was performed on DFF (primary or revision) managed with supplemental medial plating with a Large Fragment Locking Compression Plate (LCP) T-Plate (~$240 AUD) via a medial sub-vastus approach. The T-plate was contoured and placed superior to the medial condyle. A combination of 4.5mm cortical, 5mm locking and/or 6.5mm cancellous screws were used, with oblique screw trajectories towards the distal lateral cortex of the lateral condyle. All extra-articular fractures and revision fixation cases were allowed to weight bear immediately. The primary outcome was union rate.

This technique was utilised on sixteen patients; 3 acute, 13 revisions; mean age 52 years (range 16-85), 81% male, 5 open fractures. The union rate was 100%, with a median time to union of 29 weeks (IQR 18-46). The mean follow-up was 15 months. There were two complications: a deep infection requiring two debridements and a prominent screw requiring removal. The mean range of motion was 1–108o.

Supplemental medial plating of DFF with a Large Fragment LCP T-Plate is a feasible, safe, and economical option for both acute fixation and revisions. Further validation on a larger scale is warranted, along with considerations to developing a specific implant in line with these principles.

H. Faulkner G. Levy D. Hermans D. Duckworth

To determine whether pre-operative cessation of anticoagulant or antiplatelet medication is necessary for patients undergoing total shoulder arthroplasty (TSA) or reverse total shoulder arthroplasty (RTSA).

A prospectively maintained database was used to identify 213 consecutive patients treated with TSA or RTSA performed by a single surgeon across 3 centres. This cohort included 24 patients on an anticoagulant agent (warfarin, apixaban, rivaroxaban, dabigatran), 52 patients on an antiplatelet agent (aspirin, clopidogrel), and a control group of 137 patients not on anticoagulant or antiplatelet medication. Patients on anticoagulant or antiplatelet medications continued these agents peri-operatively. Outcomes included haemoglobin drop, intra-operative blood loss, operative time, transfusion requirements and post-operative complications.

The mean age of the cohort was 74.3 years (range 47 – 93) and 75 (35.2%) of the patients were male. TSA was performed in 63 cases and RTSA in 150 cases. The mean haemoglobin drop in the control group was 17.3 g/L, compared to 19.3 g/L in the anticoagulant group (p = 0.20) and 15.6 g/L in the anti-platelet group (p = 0.14). The mean intra-operative blood loss in the control group was 107.8 mL, compared to 143.0 mL in the anticoagulant group (p = 0.03) and 134.3 mL in the anti-platelet group (0.02). The mean operative time in the control group was 49.3 minutes, compared to 47.1 minutes in the anticoagulant group (p = 0.56) and 50.3 minutes in the anti-platelet group (p = 0.78). Post-operatively no patients developed a wound infection or haematoma requiring intervention. Three patients not on anticoagulant or antiplatelet medication developed pulmonary embolism.

Continuing anticoagulant or antiplatelet medication was associated with higher intra-operative blood loss, but produced no statistically significant differences in haemoglobin drop, operative time, transfusion requirements or post-operative complications. We now do not routinely stop any anticoagulant or antiplatelet medication for patients undergoing total shoulder arthroplasty.

Y. Fang I.N. Ackerman I. Harris R. Page K. Cashman M. Lorimer E. Heath S. Graves S-E. Soh

While clinically important improvements in Oxford Shoulder Scores have been defined for patients with general shoulder problems or those undergoing subacromial decompression, no threshold has been reported for classifying improvement after shoulder replacement surgery. This study aimed to establish the minimal clinically important change (MCIC) for the Oxford Shoulder Score in patients undergoing primary total shoulder replacement (TSR).

Patient-reported outcomes data were sourced from the Australian Orthopaedic Association National Joint Replacement Registry Patient-Reported Outcome Measures Program. These included pre- and 6-month post-operative Oxford Shoulder Scores and a rating of patient-perceived change after surgery (5-point scale ranging from ‘much worse’ to ‘much better’). Two anchor-based methods (using patient-perceived improvement as the anchor) were used to calculate the MCIC: 1) mean change method; and 2) predictive modelling, with and without adjustment for the proportion of improved patients.

The analysis included 612 patients undergoing primary TSR who provided pre- and post-operative data (58% female; mean (SD) age 70 (8) years). Most patients (93%) reported improvement after surgery. The MCIC derived from the mean change method was 6.8 points (95%CI 4.7 to 8.9). Predictive modelling produced an MCIC estimate of 11.6 points (95%CI 8.9 to 15.6), which reduced to 8.7 points (95%CI 6.0 to 12.7) after adjustment for the proportion of improved patients.

For patient-reported outcome measures to provide valuable information that can support clinical care, we need to understand the magnitude of change that matters to patients. Using contemporary psychometric methods, this analysis has generated MCIC estimates for the Oxford Shoulder Score. These estimates can be used by clinicians and researchers to interpret important changes in pain and function after TSR from the patient's perspective. We conclude that an increase in Oxford Shoulder Scores of at least 9 points can be considered a meaningful improvement in shoulder-related pain and function after TSR.

I. Nizam A. Alva D. Dabirrahmani D. Choudary

Direct anterior approach (DAA) arthroplasty has generated great interest because of its minimally invasive and muscle sparing nature. Obese patients are reported to be associated with greater incidence of complications in primary joint replacement. The purpose of this study was to compare patient outcomes and complication rates between obese and non-obese patients undergoing primary total hip arthroplasty (THA) through a Bikini direct anterior incision.

This retrospective, single surgeon study compared the outcome of 258 obese patients and 200 non-obese patients undergoing DAA THA using a Bikini incision, over a 7-year period. The average follow-up was 4.2 years (range 2.6-7.6 years).

There were no statistically significant differences in the complication rate between the two groups. The obese group recorded 2 major (venous thromboembolism and peri-prosthetic fracture) and 2 minor complications (superficial wound infection), compared with the non-obese group, which recorded 2 major (deep-wound infection and peri-prosthetic fracture) and 1 minor complication (superficial wound infection). Patient-reported outcomes (WOMAC and Harris Hip Scores) showed significant post-operative improvements (p < 0.001) and did not differ between the two groups.

Bikini DDA THA does not increase the complication rate in obese patients and offers similar clinical improvements compared to non-obese patients.

(200 words)

I. Nizam A. Alva S. Gogos

The purpose of this study was to report all complications during the first consecutive 865 cases of bikini incision direct anterior approach (DAA) total hip arthroplasty (THA) performed by a single surgeon. The secondary aims of the study are to report our clinical outcomes and implant survivorship. We discuss our surgical technique to minimize complication rates during the procedure.

We undertook a retrospective analysis of our complications, clinical outcomes and implant survivorship of 865 DAA THA's over a period of 6 years (mean = 5.1yrs from 2.9 to 9.4 years).

The complication rates identified in this study were low. Medium term survival at minimum 2-year survival and revision as the end point, was 99.53% and 99.84% for the stem and acetabular components respectively. Womac score improved from 49 (range 40-58) preoperatively to 3.5(range 0-8.8) and similarly, HHS scores improved from 53(range 40-56) to 92.5(range 63-100) at final follow-up (mean = 5.1 yrs) when compared to preoperative scores.

These results suggest that bikini incision DAA technique can be safely utilised to perform THA.

I. Seth G. Bulloch N. Seth Q. Fogg D.J. Hunter-Smith W.M. Rozen

The trapeziometacarpal joint (TMCJ) is the most common hand joint affected by osteoarthritis (OA), and trapezium implant arthroplasty is a potential treatment for recalcitrant OA. This meta-analysis aimed to investigate the efficacy and safety of various trapezium implants as an interventional option for TMCJ OA. Web of Science, PubMed, Scopus, Google Scholar, and Cochrane library databases were searched for relevant studies up to May 2022. Preferred Reported Items for Systematic Review and Meta-Analysis guidelines were adhered to and registered on PROSPERO. The methodological quality was assessed by National Heart, Lung, and Blood Institute tools for observational studies and the Cochrane risk of bias tool. Subgroup analyses were performed on different replacement implants, the analysis was done via Open Meta-Analyst software and P values < 0.05 were considered statistically significant.

A total of 123 studies comprising 5752 patients were included. Total joint replacement (TJR) implants demonstrate greater significant improvements in visual analogue scale pain scores postoperatively. Interposition with partial trapezial resection implants was associated with the highest grip strength and highest reduction in the Disabilities of the Arm, Shoulder, and Hand score. Revision rates were highest in TJR (12.3%), and lowest in interposition with partial trapezial resection (6.2%).

Total joint replacement and interposition with partial trapezial resection implants improve pain, grip strength, and DASH scores more than other implant options. Future studies should focus on high-quality randomized clinical trials comparing different implants to accumulate higher quality evidence and more reliable conclusions.

J. Parker K. Lim T. Woodfield I. Calhaem G. Hooper.

Hypochlorous acid (HOCl) is a potent anti-bacterial agent which could reduce periprosthetic joint infection. Early infection complications in joint replacements are often considered to be due to local contamination at the time of surgery and result in a significant socioeconomic cost. Current theatre cleaning procedures produce “clean” operating theatres which still contain bacteria (colony forming units, CFU). Reducing this bacterial load may reduce local contamination at the time of surgery. HOCl is produced naturally in the human neutrophil and has been implicated as the primary agent involved in bacterial killing during this process. In vitro research confirms its efficacy against essentially all clinically relevant bacteria. The recent advent of commercial production of HOCl, delivered as a fog, has resulted in extensive use in the food industry. Reported lack of corrosion and high anti-bacterial potency are seen as two key factors for the use of HOCl in the orthopaedic environment. Prior work by the authors comparing human cell toxicity of HOCl, chlorhexidine and iodine solutions shows favourable results.

This study evaluates use of neutral HOCl applied as a dry room fog to decrease bacteria in the operating theatre environment. Using an animal operating theatre as the test site, bacterial swabs were taken from ten 100cm2 sample areas before standard cleaning with detergent, after standard cleaning, and again after 60 minutes exposure to HOCl fog.

After standard cleaning, 6 of 10 sample sites recorded significant bacterial growth (>10 CFU/100cm2). After exposure to HOCl fog, growth in all 10 sites was below detection limits (<10 CFU/100cm2). This was repeated with specific exposure to Staphylococcus aureus and Escherichia coli.

We can conclude that HOCl is effective when used as a fogging agent to reduce bacterial loading within an operating theatre environment and as such has significant potential to reduce intraoperative contamination and periprosthetic infection.

P.J. Burn

Polyimide (MP-1, MMATech, Haifa, Israel), is a high performance aerospace thermoplastic used for its lubricity, stability, inertness and radiation resistance. A wear resistant thin robust bearing is needed for total hip arthroplasty (THR).

After independent laboratory testing, in 2006, the author used the material as a bearing in two Reflection (Smith and Nephew, USA) hip surgeries. The first, a revision for polyethylene wear, survives with no evidence of wear, noise, new osteolysis or complications related to the MP-1 bearing after 16 yrs. The second donated his asymptomatic MP-1 hip at 6.5yrs for post-mortem examination. There were no osteoclasts, cellular reaction bland in contrast to that of polyethylene.

In 2013 a clinical study with ethical committee approval was started using a Biolox Delta (Ceramtec, Germany) head against a polyimide liner in 97 patients. MMATech sold all liners, irradiated: steam 52:45. Sixteen were re-machined in New Zealand. Acetabular shells were Delta PF (LIMA, Italy). The liner locked by taper.

The cohort consisted of 46:51 M:F, and ages 43 to 85, mean 65. Ten received cemented stems. For contralateral surgery, a ceramic or polyethylene liner was used. Initial patients were lower demand, later, more active patients, mountain-biking and running.

All patients have on-going follow up, including MP-1 liner revision cases. There has been no measurable wear, or osteolysis around the acetabular components using weight-bearing radiographs. Squeaking within the first 6 weeks was noted in 39 number of cases and subtle increase in palpable friction, (passive rotation at 50 degrees flexion), but then disappeared. There were 6 revisions, four of which were related to cementless Stemsys implants (Evolutis, Italy) fixed distally with proximal linear lucencies in Gruen zones 1 and 7, and 2 and 6. No shells were revised and MP-1 liners were routinely changed to ceramic or polyethylene. The liners showed no head contact at the apex, with highly polished contact areas.

There were no deep or superficial infections, but one traumatic anterior dislocation at 7 years associated with 5 mm subsidence of a non-collared stem.

The initial squeaking and increased friction was due to the engineering of the liner / shell composite as implanted, not allowing adequate clearance for fluid film lubrication and contributed to by shell distortion during impaction. The revised bearings were “equatorial” rather than polar, and with lack of wear or creep this never fully resolved. Where the clearance was better, function was normal. The “slow” utilization was due to my ongoing concern with clearances not being correct. The revision of 4 Stemsys stems, tribology issues may have contributed, but non “MP-1” / Stemsys combinations outside this study have shown the same response, thought to be due to de-bonding of the hydroxyapatite coating.

With correct engineering and clearances, a 3.6 mm thick MP-1 bearing, a surface Ra<0.5, steam sterilized, shows no appreciable wear, and with confidence, can be used as a high performance THR bearing.

E. Schwer J. Grant D. Taylor J. Hewitt P. Blyth

The triangular fibrocartilage complex (TFCC) is a known stabiliser of the distal radioulnar joint (DRUJ). An injury to these structures can result in significant disability including pain, weakness and joint stiffness. The contribution each of its components makes to the stability of the TFCC is not well understood. This study was undertaken to investigate the role of the individual ligaments of the TFCC and their contribution to joint stability.

The study was undertaken in two parts. 30 cadaveric forearms were studied in each group. The ligaments of the TFCC were progressively sectioned and the resulting effect on the stability of the DRUJ was measured. A custom jig was created to apply a 20N force through the distal radius, with the ulna fixed.

Experiment one measured the effect on DRUJ translation after TFCC sectioning. Experiment two added the measurement of rotational instability.

Part one of the study showed that complete sectioning of the TFCC caused a mean increase in translation of 6.09(±3) mm. Sectioning the palmar radioulnar ligament of the TFCC caused the most translation.

Part two demonstrated a change in rotation with a mean of 18 (± 6) degrees following sectioning of the TFCC. There was a progressive increase in rotational instability until the palmar radioulnar ligament was also sectioned.

Linear translation consistently increased after sectioning all of the TFCC ligaments, confirming its importance for DRUJ stability. Sectioning of the palmar radioulnar ligament most commonly caused the greatest degree of translation. This suggests injury to this ligament would more likely result in a greater degree of translational instability. The increase in rotation also suggests that this type of instability would be symptomatic in a TFCC injury.

J. Hoellwarth A. Chavan A. Oomatia W. Lu M. Al Muderis V. Preda

Percutaneous EndoProsthetic Osseointegration for Limbs (PEPOL) facilitates improved quality of life (QOL) and objective mobility for most amputee's discontent with their traditional socket prosthesis (TSP) experience. Some amputees desiring PEPOL have residual bone much shorter than the currently marketed press-fit implant lengths of 14-16 cm, potentially a risk for failure to integrate. We report on the techniques used, complications experienced, the management of those complications, and the overall mobility outcomes of seven patients who had femur distraction osteogenesis (DO) with a Freedom nail followed by PEPOL.

Retrospective evaluation of a prospectively maintained database identified nine patients (5 females) who had transfemoral DO in preparation for PEPOL with two years of follow-up after PEPOL. Six patients had traumatic causes of amputation, one had perinatal complications, one was performed to manage necrotizing fasciitis and one was performed as a result of osteosarcoma.

The residual femurs on average started at 102.2±39.7 mm and were lengthened 58.1±20.7 mm, 98±45% of goal (99±161% of the original bone length). Five patients (56%) had a complication requiring additional surgery. At a mean of 3.4±0.6 (2.6-4.4) years following osseointegration six patients had K-level >2. The 6 Minute Walk Test remained unchanged (267±56 vs 308 ± 117 meters). Patient self-rating of prosthesis function, problems, and amputee situation did not significantly change from before DO to after osseointegration. Six patients required additional surgery following osseointegration: six to remove fixation plates placed to maintain distraction osteogenesis length at osseointegration; two required irritation and debridement for infection.

Extremely short residual femurs which make TSP use troublesome can be lengthening with externally controlled telescoping nails, and successfully achieve osseointegration. However, it is imperative to counsel patients that additional surgery to address inadequate regenerate or to remove painful hardware used to maintain fixation may be necessary. This may improve the amputee's expectations before beginning on a potentially arduous process.

A. Wang J. Hughes J. Fitzpatrick W. Breidhahl J. Ebert M. Zheng

Interstitial supraspinatus tears can cause persistent subacromial impingement symptoms despite non operative treatment. Autologous tendon cell injection (ATI) is a non-surgical treatment for tendinopathies and tear. We report a randomised controlled study of ATI compared to corticosteroid injection (CS) as treatment for interstitial supraspinatus tears and tendinopathy.

Inclusion criteria were patients with symptom duration > 6 months, MRI confirmed intrasubstance supraspinatus tear, and prior treatment with physiotherapy and ≥ one CS or PRP injection. Participants were randomised to receive ATI to the interstitial tear or corticosteroid injection to the subacromial bursa in a 2:1 ratio, under ultrasound guidance. Assessments of pain (VAS) and function (ASES) were performed at baseline, and 1, 3, 6 and 12 months post treatment.

30 participants (19 randomised to ATI) with a mean age of 50.5 years (10 females) and a mean duration of symptoms of 23.5 months. Baseline VAS pain and ASES scores were comparable between groups. While mean VAS pain scores improved in both groups at 3 months after treatment, pain scores were superior with ATI at 6 months (p=0.01). Mean ASES scores in the ATI group were superior to the CS group at 3 months (p=0.026) and 6 months (p=0.012). Seven participants in the CS group withdrew prior to 12 months due to lack of improvement. At 12 months, mean VAS pain in the ATI group was 1.6 ± 1.3. The improvements in mean ASES scores in the ATI group at 6 and 12 months were greater than the MCID (12.0 points). At 12 months, 95% of ATI participants had an ASES score > the PASS (patient acceptable symptom state).

This is the first level one study using ATI to treat interstitial supraspinatus tear. ATI results in a significant reduction in pain and improvement in shoulder function.

J. Lynch-Larkin M. D'Arcy T. Chuang

The role of dual consultant operating (DCO) in general orthopaedics has not been researched; where it has shown benefit in other specialties, there is a lack of information on how DCO affects the surgeons themselves. We wanted to explore the potential effects of DCO on stress, as a foundation for further research to guide support for our surgeons.

We conducted a survey among orthopaedic consultants around New Zealand, containing questions pertaining to the demographics of respondents, their experience with DCO, what the expected risks and benefits of DCO would be, and provided two high-stress exemplar clinical scenarios where respondents were asked to rate their expected stress level at baseline, with a more junior consultant present, and with a more senior consultant present.

We found 99% of respondents had been involved in DCO at some point in their careers, yet only 38% were involved in DCO on at least a monthly basis. Perceived benefits greatly outweighed potential risks: 95% felt DCO would decrease their stress, 91% felt it improved intraoperative decision making, and 89% felt it provided more enjoyment at work and enhanced collegiality. A decrease in perceived stress was seen from baseline with a more junior consultant available and a greater decrease in stress seen with a more senior consultant, particularly in a complex elective setting.

All respondents felt there is benefit in DCO and the vast majority feel it has positive effects on stress levels. In a time where burnout is more prevalent, using tools such as DCO could be an effective way to decrease stress, enhance enjoyment and collegiality — challenging some key contributors to burnout — and support mentorship with further skill acquisition. This research provides a good base to pursue further qualitative and quantitative research into the area, with a view to addressing barriers to provision of regular DCO.

J. Mowbray C. Frampton R. Maxwell G. Hooper

Cementless fixation is an alternative to cemented unicompartmental knee replacement (UKR), with several advantages over cementation. This study reports on the 15-year survival and 10-year clinical outcomes of the cementless Oxford unicompartmental knee replacement (OUKR).

This prospective study describes the clinical outcomes and survival of first 693 consecutive cementless medial OUKRs implanted in New Zealand.

The sixteen-year survival was 89.2%, with forty-six knees being revised. The commonest reason for revision was progression of arthritis, which occurred in twenty-three knees, followed by primary dislocation of the bearing, which occurred in nine knees. There were two bearing dislocations secondary to trauma and a ruptured ACL, and two tibial plateau fractures. There were four revisions for polyethylene wear. There were four revisions for aseptic tibial loosening, and one revision for impingement secondary to overhang of the tibial component. There was only one revision for deep infection and one revision where the indication was not stated. The mean OKS improved from 23.3 (7.4 SD) to 40.59 (SD 6.8) at a mean follow-up of sixteen years.

In conclusion, the cementless OUKR is a safe and reproducible procedure with excellent sixteen-year survival and clinical outcomes.

J. Blundell M. Hope

Patients awaiting resolution of swelling and oedema prior to ankle surgery can represent a significant burden on hospital beds. Our study assessed whether external pneumatic intermittent compression (EPIC) can reduce delays to surgery.

Our prospective randomised controlled trial (n= 20) compared outcomes of patients treated with EPIC vs control group managed with ice and elevation. Included were patients aged <18 years with isolated closed ankle fractures admitted for management of swelling prior to surgery. Excluded were open fractures, injuries to contralateral leg, diabetes, absent pulses, peripheral vascular disease, inability to consent, no requirement for admission. Eligible patients were randomised to active or control arms. All patients were managed initially with reduction and back slab application. Patients in active arm fitted with EPIC (Hydroven 3000) device over the back slab. Assessment by treating team determined the time at which patient is assessed ready for surgery.

Patients in the treatment arm were assessed as ready for surgery sooner, (123 hrs vs 168hrs, T score = 1.925, P 0.035) and had a shorter time to surgery (167 hrs vs 216 hrs, T score = 1.748, P 0.047) Length of stay was reduced bud did not reach statistical significance. (259 hrs vs 269 hrs, T score 0.229, P 0.41)

Our results showed a statistically and clinically significant reduction in time that patients were assessed ready for surgery and time to surgery in the treatment cohort. We conclude that although further data is needed to achieve an adequately powered study and assess the safety profile of the EPIC, incorporation of EPIC into routine clinical practice has the potential for significant cost savings.

J.P. Gibbons C. Bodian A.J. Powell J.P. Sharr N.J. Lash

PFFs are an increasing burden presenting to the acute trauma services. The purpose of this study is to show that cemented revision for Vancouver B2/B3 PFFs is a safe option in the geriatric population, allows early pain-free weight bearing and comparable to a control-group of uncemented stems with regard to return to theatre and revision surgery.

A retrospective review was conducted of all PFFs treated in a Level 1 trauma centre from 2015-2020. Follow up x-rays and clinical course through electronic chart was reviewed for 78 cemented revisions and 49 uncemented revisions for PFF. Primary endpoints were all cause revision and return to theatre for any reason. Secondary endpoints recorded mobility status and all-cause mortality.

In the cemented group there were 73 Vancouver B2, 5 Vancouver B3 PFF; the mean age was 79.7 years and mean radiological follow-up of 11.9 months. In the cementless group there were 32 Vancouver B2 and 17 Vancouver B3 PFFs; with all 49 patients undergoing distally bearing uncemented revision, the mean age was 72.7 years and mean radiological follow-up of 21.3 months.

Patients treated with a cemented prosthesis had significantly higher ASA score (2.94 -v- 2.43, p<0.001). The primary endpoints showed that there was no significant difference in all cause revision 3/78 and 5/49 p=0.077, or return to theatre 13/78 -v- 12/49 p=0.142.

Secondary endpoints revealed no significant difference in in-hospital mortality. The cementless group were more likely to be mobilising without any aid at latest follow-up 35/49 -v- 24/78 p<0.001.

The use of cemented revision femoral component in the setting of PFFs is one option in the algorithm for management of unstable PFFs according to the Vancouver classification. Evidence from this case-control study, shows that the all-cause revision and return to theatre for any cause was comparable in both groups.

J. Mortimer H. Louis L. Whiteman P. Forouzandeh A. Steiner T. Gregg K. De Ridder

Idiopathic Toe-walking (ITW) is a condition where children persistently walk on their toes in the absence of neurological or orthopaedic structural abnormalities. ITW affects 2% of children at the age of 5.5yr. This may eventually result in fixed ankle equinus. There is a paucity of long-term natural history studies in untreated ITW however persisting equinus contractures are implicated in common adult foot conditions.

The Aim of this study is to show if the percentage of contact pressure through the hindfoot during standing and walking improve following surgical tendoachilles lengthening one year after surgery in children with ITW when compared to a normative cohort

23 patients (46 feet) diagnosed with ITW between 2017-2022; were treated with open zone III Achilles lengthening. We reported patient demographics, clinical resolution, or revision. Passive dorsiflexion range and hindfoot pressure percentage when standing and walking were measured on a baropodometric walkway and compared pre-operatively and at 12-18months postoperatively. We compared this to data from a previously studied normative cohort

87% of children had compete resolution of toe-walking. 3 had recurrence with 1 patient having a revision surgery. Mean pre-operative static heel pressure percentage was 15.7%, this improved to 54.7% (p<0.001). This neared normative average of 70.6%. Mean pre-operative dynamic heel pressure percentage was 5.5%, this improved to 44.6% (p<0.001). This neared the normative mean of 52.0%. Mean Passive dorsiflexion in extension and 90˚ knee flexion was −5.8˚ and 0.5˚ respectively. This improved on average by 17.4˚ and 14.5˚ to a new mean of 11.6˚ and 15.0˚ (p<0.001).

Open Zone III Achilles lengthening for ITW has high resolution rates. Hindfoot contact pressures and passive ankle dorsiflexion show improvement at 1 year post operatively.

J. Liew L. Salmon R. Mittal L. Pinczewski

Total Knee Arthroplasty (TKA) is a successful treatment for end stage osteoarthritis of the knee joint. However, post-operative pain can lead to patient dissatisfaction and poorer outcomes. Cooled radiofrequency nerve ablation (CRNA) has reportedly been effective at treating pain osteoarthritic knee pain by targeting the periarticular nerves of the knee. We undertook a prospective, controlled pilot study to determine if CRNA provides effective post-operative analgesia when utilised intra-operatively during total knee arthroplasty.

Participants were recruited from January 2019 to February 2020. Those meeting inclusion criteria underwent TKA with intraoperative CRNA to 6 target sites prior to the cementing of implants. The primary outcomes were pain scores and opiate usage in the first 4 days post-operatively, then weekly up to 6 weeks. A total of 62 patients were screened and allocated sequentially; 18 were recruited to the control group and 12 recruited to the study group. The two groups did not have any significant difference in demographics.

There were no clinically significant differences between the two groups in terms of pain scores nor opiate usage. There were complications as a result of the intervention.

This study demonstrated no benefit of using intraoperative CRNA for improving post-operative pain scores or reducing opiate use after TKA.

L.A. Mactier M. Baker J.G. Twiggs B.P. Miles J.J. Negus

A primary goal of revision Total Knee Arthroplasty (rTKA) is restoration of the Joint Line (JL) and Posterior Condylar Offsets (PCO). The presence of a native contralateral joint allows JL and PCO to be inferred in a way that could account for patient-specific anatomical variations more accurately than current techniques. This study assesses bilateral distal femoral symmetry in the context of defining targets for restoration of JL and PCO in rTKA.

566 pre-operative CTs for bilateral TKAs were segmented and landmarked by two engineers. Landmarks were taken on both femurs at the medial and lateral epicondyles, distal and posterior condyles and hip and femoral centres. These landmarks were used to calculate the distal and posterior offsets on the medial and lateral sides (MDO, MPO, LDO, LPO respectively), the lateral distal femoral angle (LDFA), TEA to PCA angle (TEAtoPCA) and anatomic to mechanical axis angle (AAtoMA). Mean bilateral differences in these measures were calculated and cases were categorised according to the amount of asymmetry.

The database analysed included 54.9% (311) females with a mean population age of 68.8 (±7.8) years. The mean bilateral difference for each measure was: LDFA 1.4° (±1.0), TEAtoPCA 1.3° (±0.9), AAtoMA 0.5° (±0.5), MDO 1.4mm (±1.1), MPO 1.0mm (±0.8). The categorisation of asymmetry for each measure was: LDFA had 39.9% of cases with <1° bilateral difference and 92.4% with <3° bilateral difference, TEAtoPCA had 45.8% <1° and 96.6% <3°, AAtoMA had 85.7% <1° and 99.8% <3°, MDO had 46.2% <1mm and 90.3% <3mm, MPO had 57.0% <1mm and 97.9% <3mm.

This study presents evidence supporting bilateral distal femoral symmetry. Using the contralateral anatomy to obtain estimates for JL and PCO in rTKA may result in improvements in intraoperative accuracy compared to current techniques and a more patient specific solution to operative planning.

W.P.J. Tan S. Yu T. Gill D. Campbell K. Umapathysivam P. Smitham

The progressive painful and disabling predicament of patients with severe osteoarthritis awaiting a total hip or knee arthroplasty (THA/TKA) results in a decline in muscle mass, strength and function also known as Sarcopenia.

We conducted a cross-sectional, prospective study of patients on the waiting-list for a THA/TKA in the South Australian public healthcare system and compared the findings to healthy participants and patients newly referred from their general practitioners. Participants with a history of joint replacements, pacemakers and cancers were excluded from this study. Outcomes of this study included (i) sarcopenia screening (SARC-F ≥4); (ii) sarcopenia, defined as low muscle strength (hand grip strength M<27kg; F<16kg), low muscle quality (skeletal muscle index M<27%, F<22.1%) and low physical performance (short physical performance battery ≤8). Additional outcomes include descriptions of the recruitment feasibility, randomisation and suitability of the assessment tools.

29 healthy controls were recruited; following screening, 83% (24/29) met the inclusion criteria and 75% (18/24) were assessed. 42 newly referred patients were recruited; following screening, 67% (30/45) met the inclusion criteria and 63% (19/30) were assessed. 68 waiting list patients were recruited; following recruitment, 24% (16/68) met the inclusion criteria and 75% (12/16) were assessed. Preliminary data shows increasing waiting time is associated with higher SARC-F scores, lower hand grip strength and lower muscle quality.

As a pilot study, preliminary data demonstrate that: (1) study subjects’ willingness to participate will enable a larger study to be conducted to establish the prevalence of sarcopenia and the diagnostic cut-off points for this patient group. (2) SARC-F is a suitable tool to screen for sarcopenia. (3) There is a positive correlation between waiting time for a THA/TKA and sarcopenia.

J. White A. Wadhawan H. Min Y. Rabi B. Schmutz J. Dowling A. Tchernegovski P. Bourgeat K. Tetsworth J. Fripp G. Mitchell C. Hacking F. Williamson M. Schuetz

Distal radius fractures (DRFs) are one of the most common types of fracture and one which is often treated surgically. Standard X-rays are obtained for DRFs, and in most cases that have an intra-articular component, a routine CT is also performed. However, it is estimated that CT is only required in 20% of cases and therefore routine CT's results in the overutilisation of resources burdening radiology and emergency departments. In this study, we explore the feasibility of using deep learning to differentiate intra- and extra-articular DRFs automatically and help streamline which fractures require a CT.

Retrospectively x-ray images were retrieved from 615 DRF patients who were treated with an ORIF at the Royal Brisbane and Women's Hospital. The images were classified into AO Type A, B or C fractures by three training registrars supervised by a consultant. Deep learning was utilised in a two-stage process: 1) localise and focus the region of interest around the wrist using the YOLOv5 object detection network and 2) classify the fracture using a EfficientNet-B3 network to differentiate intra- and extra-articular fractures.

The distal radius region of interest (ROI) detection stage using the ensemble model of YOLO networks detected all ROIs on the test set with no false positives. The average intersection over union between the YOLO detections and the ROI ground truth was Error! Digit expected.. The DRF classification stage using the EfficientNet-B3 ensemble achieved an area under the receiver operating characteristic curve of 0.82 for differentiating intra-articular fractures.

The proposed DRF classification framework using ensemble models of YOLO and EfficientNet achieved satisfactory performance in intra- and extra-articular fracture classification. This work demonstrates the potential in automatic fracture characterization using deep learning and can serve to streamline decision making for axial imaging helping to reduce unnecessary CT scans.

J. Petterwood J. Sullivan S. Coffey S. McMahon E.A. Wakelin C. Plaskos A.D. Orsi

Preoperative ligament laxity can be characterized intraoperatively using digital robotic tensioners. Understanding how preoperative knee joint laxity affects preoperative and early post-operative patient reported outcomes (PROMs) may aid surgeons in tailoring intra-operative balance and laxity to optimize outcomes for specific patients.

This study aims to determine if preoperative ligament laxity is associated with PROMs, and if laxity thresholds impact PROMs during early post-operative recovery.

106 patients were retrospectively reviewed. BMI was 31±7kg/m2. Mean age was 67±8 years. 69% were female. Medial and lateral knee joint laxity was measured intraoperatively using a digital robotic ligament tensioning device after a preliminary tibial resection.

Linear regressions between laxity and KOOS12-function were performed in extension (10°), midflexion (45°), and flexion (90°) at preoperative, 6-week, and 3-month time points. Patients were separated into two laxity groups: ≥7 mm laxity and <7 mm laxity. Student's t-tests determined significant differences between laxity groups for KOOS12-function scores at all time points.

Correlations were found between preoperative KOOS12-function and medial laxity in midflexion (p<0.001) and flexion (p<0.01). Patients with <7 mm of medial laxity had greater preoperative KOOS12-function scores compared to patients with ≥7 mm of medial laxity in extension (46.8±18.2 vs. 29.5±15.6, p<0.05), midflexion (48.4±17.8 vs. 32±16.1, p<0.001), and flexion (47.7±18.3 vs. 32.6±14.7, p<0.01). No differences in KOOS12-function scores were observed between medial laxity groups at 6-weeks or 3-months. All knees had <5 mm of medial laxity postoperatively. No correlations were found between lateral laxity and KOOS12-function.

Patients with preoperative medial laxity ≥7 mm had lower preoperative PROMs scores compared to patients with <7 mm of medial laxity. No differences in PROMs were observed between laxity groups at 6 weeks or 3 months. Patients with excessive preoperative joint laxity achieve similar PROMs scores to those without excessive laxity after undergoing gap balancing TKA.

S. McMahon S. Coffey J. Sullivan J. Petterwood C. Ponder E. Slotkin E.A. Wakelin A.D. Orsi C. Plaskos

Passive smartphone-based apps are becoming more common for measuring patient progress after total knee arthroplasty (TKA). Optimum activity levels during early TKA recovery haven't been well documented. This study investigated correlations between step-count and patient reported outcome measures (PROMs) and how demographics impact step-count preoperatively and during early post-operative recovery.

Smartphone capture step-count data from 357 TKA patients was retrospectively reviewed. Mean age was 68±8years. 61% were female. Mean BMI was 31±6kg/m2. Mean daily step count was calculated over three time-windows: 60 days prior to surgery (preop), 5-6 weeks postop (6wk), and 11-12 weeks postop (12wk).

Linear correlations between step-count and KOOS12-function and UCLA activity scores were performed. Patients were separated into three step-count levels: low (<1500steps/day), medium (1500-4000steps/day), and high (>4000steps/day). Age >65years, BMI >30kg/m2, and sex were used for demographic comparisons.

Student's t-tests determined significant differences in mean step-counts between demographic groups, and in mean PROMs between step-count groups.

UCLA correlated with step-count at all time-windows (p<0.01). KOOS12-Function correlated with step-count at 6wk and 12wk (p<0.05). High step-count individuals had improved PROMs compared to low step-count individuals preoperatively (UCLA: ∆1.4 [p<0.001], KOOS12-Function: ∆7.3 [p<0.05]), at 6wk (UCLA: ∆1 [p<0.01], KOOS12-Function: ∆7 [p<0.05]), and at 12wk (UCLA: ∆0.8 [p<0.05], KOOS12-Function: ∆6.5 [p<0.05]).

Younger patients had greater step-count preoperatively (3.8±3.0k vs. 2.5±2.3k, p<0.01), at 6wk (3.1±2.9k vs. 2.2±2.3k, p<0.05) and at 12wk (3.9±2.6k vs. 2.8±2.6k, p<0.01). Males had greater step-count preoperatively (3.7±2.6k vs. 2.5±2.6k, p<0.001), at 6wk (3.6±2.6k vs. 1.9±2.4k, p<0.001), and at 12wk (3.9±2.3 vs. 2.8±2.8k, p<0.01). No differences in step-count were observed between low and high BMI patients at any timepoint.

High step count led to improved PROMs scores compared to low step-count. Early post-operative step-count was significantly impacted by age and sex. Generic recovery profiles may not be appropriate across a diverse population.

J. Xu W. Veltman Y. Chai W. Walter

Navigation in total hip arthroplasty has been shown to improve acetabular positioning and can decrease the incidence of mal-positioned acetabular components. The aim of this study was to assess two surgical guidance systems by comparing intra-operative measurements of acetabular component inclination and anteversion with a post-operative CT scan.

We prospectively collected intra-operative navigation data from 102 hips receiving conventional THA or hip resurfacing arthroplasty through either a direct anterior or posterior approach. Two guidance systems were used simultaneously: an inertial navigation system (INS) and optical navigation system (ONS). Acetabular component anteversion and inclination was measured on a post-operative CT.

The average age of the patients was 64 years (range: 24-92) and average BMI was 27 kg/m2 (range 19-38). 52% had hip surgery through an anterior approach. 98% of the INS measurements and 88% of the ONS measurements were within 10° of the CT measurements. The mean (and standard deviation) of the absolute difference between the post-operative CT and the intra-operative measurements for inclination and anteversion were 3.0° (2.8) and 4.5° (3.2) respectively for the ONS, along with 2.1° (2.3) and 2.4° (2.1) respectively for the INS. There was significantly lower mean absolute difference to CT for the INS when compared to ONS in both anteversion (p<0.001) and inclination (p=0.02).

Both types of navigation produced reliable and reproducible acetabular cup positioning. It is important that patient-specific planning and navigation are used together to ensure that surgeons are targeting the optimal acetabular cup position. This assistance with cup positioning can provide benefits over free-hand techniques, especially in patients with an altered acetabular structure or extensive acetabular bone loss.

In conclusion, both ONS and INS allowed for adequate acetabular positioning as measured on postoperative CT, and thus provide reliable intraoperative feedback for optimal acetabular component placement.

D. Lin J. Xu P. Weinrauch P. Yates D. Young W. Walter

Hip resurfacing arthroplasty (HRA) is a bone conserving alternative to total hip arthroplasty. We present the early 1 and 2-year clinical and radiographical follow-up of a novel ceramic-on-ceramic (CoC) HRA in a multi-centric Australian cohort.

Patient undergoing HRA between September 2018 and April 2021 were prospectively included. Patient-reported outcome measures (PROMS) in the form of the Forgotten Joint Score (FJS), HOOS Jr, WOMAC, Oxford Hip Score (OHS) and UCLA Activity Score were collected preoperatively and at 1- and 2-years post-operation. Serial radiographs were assessed for migration, component alignment, evidence of osteolysis/loosening and heterotopic ossification formation.

209 patients were identified of which 106 reached 2-year follow-up. Of these, 187 completed PROMS at 1 year and 90 at 2 years. There was significant improvement in HOOS (p< 0.001) and OHS (p< 0.001) between the pre-operative, 1-year and 2-years outcomes. Patients also reported improved pain (p<0.001), function (p<0.001) and reduced stiffness (p<0.001) as measured by the WOMAC score. Patients had improved activity scores on the UCLA Active Score (p<0.001) with 53% reporting return to impact activity at 2 years. FJS at 1 and 2-years were not significantly different (p=0.38). There was no migration, osteolysis or loosening of any of the implants. The mean acetabular cup inclination angle was 41.3° and the femoral component shaft angle was 137°. No fractures were reported over the 2-year follow-up with only 1 patient reporting a sciatic nerve palsy.

There was early return to impact activities in more than half our patients at 2 years with no early clinical or radiological complications related to the implant. Longer term follow-up with increased patient numbers are required to restore surgeon confidence in HRA and expand the use of this novel product.

In conclusion, CoC resurfacing at 2-years post-operation demonstrate promising results with satisfactory outcomes in all recorded PROMS.

J. Xu B. Sivakumar H. Nandapalan T. Moopanar D. Harries R. Page M. Symes

Proximal humerus fractures (PHF) are common, accounting for approximately 5% of all fractures. Approximately 30% require surgical intervention which can range from open reduction with internal fixation (ORIF) to shoulder arthroplasty (including hemiarthroplasty, total shoulder arthroplasty, (TSA) or reverse total shoulder arthroplasty (RTSA)). The aim of this study was to assess trends in operative interventions for PHF in an Australian population.

Data was retrospectively collected for patients diagnosed with a PHF and requiring surgical intervention between January 2001 and December 2020. Data for patients undergoing ORIF were extracted from the Medicare database, while data for patients receiving arthroplasty for PHF were obtained from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR).

Across the study period, ORIF was the most common surgical procedure for management of PHFs. However, since 2019, RTSA has surpassed ORIF as the most common surgical procedure to treat PHFs, accounting for 51% of operations. While the number of RTSA procedures for PHF has increased, ORIF and shoulder hemiarthroplasty has significantly reduced since 2007 (p < 0.001). TSA has remained uncommon across the follow-up period, accounting for less than 1% of all operations. Patients younger than 65 years were more likely to receive ORIF, while those aged 65 years or greater were more likely to receive hemiarthroplasty or RTSA.

While the number of ORIF procedures has increased during the period of interest, it has diminished as a proportion of overall procedure volume. RTSA is becoming increasingly popular, with decreasing utilization of hemiarthroplasty, and TSA for fracture remaining uncommon. These trends provide information that can be used to guide resource allocation and health provision in the future. A comparison to similar data from other nations would be useful.

J. Guo P. Blyth K. Clifford N. Hooper H.A. Crawford

Augmented reality simulators offer opportunities for practice of orthopaedic procedures outside of theatre environments. We developed an augmented reality simulator that allows trainees to practice pinning of paediatric supracondylar humeral fractures (SCHF) in a radiation-free environment at no extra risk to patients. The simulator is composed of a tangible child's elbow model, and simulated fluoroscopy on a tablet device. The treatment of these fractures is likely one of the first procedures involving X-ray guided wire insertion that trainee orthopaedic surgeons will encounter. This study aims to examine the extent of improvement simulator training provides to real-world operating theatre performance.

This multi-centre study will involve four cohorts of New Zealand orthopaedic trainees in their SET1 year. Trainees with no simulator exposure in 2019 - 2021 will form the comparator cohort. Trainees in 2022 will receive additional, regular simulator training as the intervention cohort. The comparator cohort's performance in paediatric SCHF surgery will be retrospectively audited using routinely collected operative outcomes and parameters over a six-month period. The performance of the intervention cohorts will be collected in the same way over a comparable period. The data collected for both groups will be used to examine whether additional training with an augmented reality simulator shows improved real-world surgical outcomes compared to traditional surgical training. This protocol has been approved by the University of Otago Health Ethics committee, and the study is due for completion in 2024.

This study is the first nation-wide transfer validity study of a surgical simulator in New Zealand. As of September 2022, all trainees in the intervention cohort have been recruited along with eight retrospective trainees via email. We present this protocol to maintain transparency of the prespecified research plans and ensure robust scientific methods. This protocol may also assist other researchers conducting similar studies within small populations.

J. Sun SL E. Tan J. Sevao

Anatomically specific fixation devices have become mainstream, yet there are anatomical regions and clinical conditions where no pre-contoured plates are available, such as for glenohumeral arthrodesis. In a case series of 4 glenohumeral arthrodesis patients, a consultant orthopaedic surgeon at GCUH implemented 3D printing technology to create reconstructions of each patient's shoulder girdle to pre-contour arthrodesis plates. Our aim was to quantify the cost-benefit & intra-operative time savings of this technique in glenohumeral arthrodesis.

We hypothesized that the use of 3D printing for creating patient specific implants through pre-operative contouring of plates will lead to intra-operative time and cost savings by minimising time spent bending plates during surgery.

This study analysed 4 patients who underwent shoulder arthrodesis by a single consultant orthopaedic surgeon at GCUH between 2017-2021. A CT-based life-size model of each patient's shoulder girdle was 3D printed using freely available computer software programs: 3D Slicer, Blender, Mesh Mixer & Cura.

Once the patient's 3D model was created, plate benders were used to contour the plate pre-op, which was then sterilised prior to surgery. Arthrodesis was performed according to AO principles of fixation. The time spent pre-bending the plate using the 3D model was calculated to analyse the intra-op time and cost-saving benefits.

For the 4 cases, the plate pre-bending times were 45, 40, 45 & 20 minutes (average 38.8 mins). The intra-op correction time to make small adjustments to the plate was 2 min/ case. 3 plates needed minor (3 degree) adjustment to fine-tune scapula spine contouring. 1 plate needed a 5 degree correction to fine-tune hand position. On average, the pre-bending of the plate saved approximately 38.8 mins intra-op/ case. These shorter anaesthetic and operating times equate to approximately $2586 saving/ case, given an estimate of $4000/hour of theatre costs.

We conclude that pre-bending plates around 3D-printed life-size models of an individual's shoulder girdle prior to surgery results in approximately 38.8 mins time saving intra-op when used in shoulder arthrodesis. This is a viable and effective technique that will ultimately result in significant operative time and financial savings.

K. Kim A. Wang C. Coomarasamy M. Foster

Distal interphalangeal joint (DIPJ) fusion using a k-wire has been the gold standard treatment for DIPJ arthritis. Recent studies have shown similar patient outcomes with the headless compression screws (HCS), however there has been no cost analysis to compare the two. Therefore, this study aims to 1) review the cost of DIPJ fusion between k-wire and HCS 2) compare functional outcome and patient satisfaction between the two groups.

A retrospective review was performed over a nine-year period from 2012-2021 in Counties Manukau. Cost analysis was performed between patients who underwent DIPJ fusion with either HCS or k-wire. Costs included were surgical cost, repeat operations and follow-up clinic costs. The difference in pre-operative and post-operative functional and pain scores were also compared using the patient rate wrist/hand evaluation (PRWHE).

Of the 85 eligible patients, 49 underwent fusion with k-wires and 36 had HCS. The overall cost was significantly lower in the HCS group which was 6554 New Zealand Dollars (NZD), whereas this was 10408 NZD in the k-wire group (p<0.0001). The adjusted relative risk of 1.3 indicate that the cost of k-wires is 1.3 times more than HCS (P=0.0053). The patients’ post-operative PRWHE pain (−22 vs −18, p<0.0001) and functional scores (−38 vs −36, p<0.0001) improved significantly in HCS group compared to the k-wire group.

Literatures have shown similar DIPJ fusion outcomes between k-wire and HCS. K-wires often need to be removed post-operatively due to the metalware irritation. This leads to more surgical procedures and clinic follow-ups, which overall increases the cost of DIPJ fusion with k-wires.

DIPJ fusion with HCS is a more cost-effective with a lower surgical and follow-up costs compared to the k-wiring technique. Patients with HCS also tend to have a significant improvement in post-operative pain and functional scores.

J. Sonntag K. Landale S. Brorson I. A. Harris

The aim of this study was to investigate surgeons’ reported change of treatment preference in response to the results and conclusion from a randomized controlled trial (RCT) and to study patterns of change between subspecialties and nationalities.

Two questionnaires were developed through the Delphi process for this cross-sectional survey of surgical preference. The first questionnaire was sent out before the publication of a RCT and the second questionnaire was sent out after publication. The RCT investigated repair or non-repair of the pronator quadratus (PQ) muscle during volar locked plating of distal radial fractures (DRFs). Overall, 380 orthopaedic surgeons were invited to participate in the first questionnaire, of whom 115 replied. One hundred surgeons were invited to participate in the second questionnaire. The primary outcome was the proportion of surgeons for whom a treatment change was warranted, who then reported a change of treatment preference following the RCT. Secondary outcomes included the reasons for repair or non-repair, reasons for and against following the RCT results, and difference of preferred treatment of the PQ muscle between surgeons of different nationalities, qualifications, years of training, and number of procedures performed per year.

Of the 100 surgeons invited for the second questionnaire, 74 replied. For the primary outcome, 6 of 32 surgeons (19%), who usually repaired the PQ muscle and therefore a change of treatment preference was warranted, reported a change of treatment preference based on the RCT publication. Of the secondary outcomes, restoring anatomy was the most common response for repairing the PQ muscle.

The majority of the orthopaedic surgeons, where a change of treatment preference was warranted based on the results and conclusion of a RCT, did not report willingness to change their treatment preference.

M.C. Ross K.G. Vince W. Hoskins

Constrained implants with intra-medullary fixation are expedient for complex TKA. Constraint is associated with loosening, but can correction of deformity mitigate risk of loosening?

Primary TKA's with a non-linked constrained prosthesis from 2010-2018 were identified. Indications were ligamentous instability or intra-medullary fixation to bypass stress risers. All included fully cemented 30mm stem extensions on tibia and femur. If soft tissue stability was achieved, a posterior stabilized (PS) tibial insert was selected.

Pre and post TKA full length radiographs showed.

hip-knee-ankle angles (HKAA)

Kennedy Zone (KZ) where hip to ankle vector crosses knee joint.

77 TKA's in 68 patients, average age 69.3 years (41-89.5) with OA (65%) post-trauma (24.5%) and inflammatory arthropathy (10.5%).

Pre-op radiographs (62 knees) showed varus in 37.0% (HKAA: 4o-29o), valgus in 59.6% (HKAA range 8o-41o) and 2 knees in neutral.

13 cases deceased within 2 years were excluded. Six with 2 year follow up pending have not been revised. Mean follow-up is 6.1 yrs (2.4-11.9yrs).

Long post-op radiographs showed 34 (57.6%) in central KZ (HKKA 180o +/- 2o).

Thirteen (22.0%) were in mechanical varus (HKAA 3o-15o) and 12 (20.3%) in mechanical valgus: HKAA (171o-178o)

Three failed with infection; 2 after ORIF and one with BMI>50. The greatest post op varus suffered peri-prosthetic fracture. There was no aseptic loosening or instability.

Only full-length radiographs accurately measure alignment and very few similar studies exist. No cases failed by loosening or instability, but PPF followed persistent malalignment. Infection complicated prior ORIF and elevated BMI.

This does not endorse indiscriminate use of mechanically constrained knee prostheses. Lower demand patients with complex arthropathy, especially severe deformity, benefit from fully cemented, non-linked constrained prostheses, with intra-medullary fixation. Hinges are not necessarily indicated, and rotational constraint does not lead to loosening.

K. Burrows A. Lock Z. Smith S. McChesney

Failure of cephalomedullary fixation for proximal femur fractures is an uncommon event associated with significant morbidity to the patient and cost to the healthcare system. This institution changed nailing system from the PFNA (DePuy Synthes) to InterTan (Smith and Nephew) in February 2020. To assess for non-inferiority, a retrospective review was performed on 247 patients treated for unstable proximal femur fractures (AO 31 A2; A3).

Patients were identified through manual review of fluoroscopic images. Stable fracture patterns were excluded (AO 31 A1). Pre/post operative imaging, demographic data, operative time and ASA scores assessed. Internal/external imaging and national joint registry data were reviewed for follow up.

No significant difference was found in overall failure rate of PFNA vs InterTan (4.84% vs 3.23%; p = 0.748). Overall, short nails were more likely to fail by cut-out than long nails (7.5% vs 1.2%; p = 0.015). Nails which failed by varus cut-out had a higher tip/apex distance (TAD) (26.2mm vs 17.0mm; p < 0.001). Of concern, varus cut-out occurred in two InterTan nails with TAD of <25mm. The PFNA enjoyed a shorter operative time for both the short (59.1 vs 71.8 mins; p = 0.022) and long nails (98.8 vs 114.3 mins; p = 0.016) with no difference in 120-day survival rate.

Overall failure rates of the PFNA and InterTan nailing systems were comparable. However, the failure rate of short nails in this study is concerning. Using long nails with a lag screw design for unstable intertrochanteric femoral fractures may reduce failure rates. Cumulative frequency analysis suggests stringent tip-apex distances of less than 21mm may reduce failure rates in lag-screw design cephulomedullary nails. This dataset suggests that unstable intertrochanteric fractures may be more reliably managed with a long cephalomedullary device.

K. Rosser J. Ryu S. Deo M. Flint

The NZ Standards of Service Provision for Sarcoma patients were developed by the NZ Sarcoma working group and published by the Ministry of Health (MOH) in 2013. Although not formally enacted by the MOH we aimed to determine the impact of these published standards and referral pathways on disease-specific survival of patients with soft-tissue sarcoma in NZ.

The Middlemore Musculoskeletal Tumour Unit database was searched. Patients referred for treatment in our centre with a diagnosis of soft tissue sarcoma in the five-year period before (n=115) and after (n=155) were included. We excluded patients with bone sarcomas and retroperitoneal soft tissue sarcomas.

The rate of referral after inappropriate treatment reduced after implementation of the Standards (24% vs 12%, p=0.010). The number of patients referred with tumours larger than 50mm decreased (74.8% vs 72.3%, p=0.021) and fewer had metastases at diagnosis (11.3% vs 3.2%, p=0.017). Mortality was lower in the group after introduction of the Standards (45% vs 30%, p=0.017). The estimated disease-specific survival curve between the two groups shows a trend towards increased survival in the post-standards group, although not reaching statistical significance. Local recurrence rate and metastasis rate after definitive treatment were similar between the two groups. Patients had a shorter duration of symptoms before referral in the post-Standards group although this was not statistically significant.

Since implementation of the Standards, patients have been referred more promptly, with fewer inappropriate treatments. The time to mortality curve indicates a trend towards improved disease-specific survival. We conclude that the pathway for investigation and referral for this condition has become clearer, supporting the ongoing use of the Sarcoma Standards, and that these should be formally implemented by the MOH.

D Lin B Gooden M Lyons L Salmon K Martina K Sundaraj J Yong Yau Tai M O'Sullivan

The prevalence of gluteal tendinopathy (GT) associated with osteoarthritis of the hip is difficult to determine as it is frequently undiagnosed or misdiagnosed as trochanteric bursitis. Its relationship to total hip arthroplasty (THA) outcomes is currently unknown. The aim of this study was to determine the incidence of GT at the time of hip arthroplasty and examine the relationship between GT and patient reported outcomes (PROMS) before and after THA.

Patients undergoing THA for primary osteoarthritis between August 2017 and August 2020 were recruited. Tendinopathy was assessed and graded at time of surgery. PROMS included the Oxford Hip Score (OHS), HOOS JR, EQ-5D, and were collected preoperatively and at one year after THA. Satisfaction with surgery was also assessed at 1 year.

797 patients met eligibility criteria and were graded as Grade 1: normal tendons (n =496, 62%), Grade 2: gluteal tendinopathy but no tear (n=222, 28%), Grade 3: partial/full thickness tears or bare trochanter (n=79, 10%). Patients with abnormal gluteal tendons were older (p=0.001), had a higher mean BMI (p=0.01), and were predominately female (p=0.001). Patients with higher grade tendinopathy had statistically significant inferior PROMS at one year, OHS score (44.1 v 42.9 v 41.3, p 0.001) HOOS JR (89.3 V 86.3 V 85.6 p 0.005). Increasing gluteal tendon grade was associated with a greater incidence of problems with mobility (p=0.001), usual activities (p=0.001) and pain (p=0.021) on EQ5D. There was a 3 times relative risk of overall dissatisfaction with THA in the presence of gluteal tears.

This study demonstrated that gluteal tendinopathy was commonly observed and associated with inferior 1-year PROMS in patients undergoing THA for OA. Increasing degree of tendinopathy was a negative prognostic factor for worse functional outcomes and patient satisfaction.

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K Sundaraj V Russsell L Salmon L Pinczewski

The aim of this study was to determine the long term 20 year survival and outcomes of high tibial osteotomy (HTO).

100 consecutive subjects underwent HTO under the care of a single surgeon between 2000 and 2002, consented to participation in a prospective study and completed preoperative WOMAC scores. Subjects were reviewed at 10 years, and again at a minimum of 20 years after surgery. PROMS included further surgery, WOMAC scores, Oxford Knee Score (OHS), KOOS, and EQ-5D, and satisfaction with surgery. 20 year survival was assessed with Kaplan-Meir analysis, and failure defined as proceeding to subsequent knee arthroplasty.

The mean age at HTO was 50 years (range 26-66), and 72% were males. The 5, 10, and 20 year survival of the HTO was 88%, 76%, 43% respectively. On multiple regression analysis HTO failure was associated with poor preoperative WOMAC score of 45 or less (HR 3.2, 95% CI 1.7-6.0, p=0.001), age at surgery of 55 or more (HR 2.3, 95% CI 1.3-4.0, p=0.004), and obesity (HR 1.9, 95% CI 1.1-3.4, p=0.023). In patients who met all criteria of preoperative WOMAC score of 45 or less, age <55 years and body mass index of <30 HTO survival was 100%, 94%, and 59% at 5, 10 and 20 years respectively. Of those who had not proceeded to TKA the mean Oxford Score was 40, KOOS Pain score was 91 and KOOS function score was 97. 97% reported they were satisfied with the surgery and 88% would have the same surgery again under the same circumstances.

At 20 years after HTO 43% had not proceeded to knee arthroplasty, and were continuing to demonstrate high subjective scores and satisfaction with surgery. HTO survival was higher in those under 55 years, with BMI <30 and baseline WOMAC score of >45 at 59% HTO survival over 20 years. HTO may be considered a viable procedure to delay premature knee arthroplasty in carefully selected subjects.

K Sundaraj B Gooden M Lyons J Roe D Carmody L Pinczewski P Huang L Salmon K Martina E Smith M O'Sullivan

Obesity is a common in individuals undergoing arthroplasty, and the potential for weight loss with improved mobility may be expected by some. The aim of this study was 1. determine the proportion that achieved weight loss after hip or knee arthroplasty, and 2. examine the effect of obesity on patient reported outcomes (PROMS) and satisfaction with surgery.

Participants underwent primary TKA or THA between July 2015 and December 2020 and consented to participation in a research database with baseline PROMS, including weight, BMI, Oxford Knee, or Hip Score, and EQ5D. Participants repeated PROMS at 12 months after surgery with additional questions regarding satisfaction with surgery.

3449 patients completed PROMS 1 year after arthroplasty with weight and BMI. There were 1810 THA and 1639 TKA procedures. The mean baseline BMI was higher in TKA (29.8, SD 5.2) compared to THA (27.7, SD 5.0), p=0.001. A higher proportion of TKA were classified as obese class 1 (29% TKA, 19% THA), obese class 2 (11% TKA and 6% THA), and obese class 3 (5% TKA and 2% THA), p=0.001. The mean weight loss after 1 year was 0.4kg and 0.9kg in obese THA subjects and TKA subjects respectively. In the obese >5kg weight loss was achieved in 13% of TKA and 7% of THA (p=0.001). Obese experienced equivalent improvement in Oxford scores, compared to non-obese subjects. Satisfaction with surgery was reported by 95% of THA and 91% of TKA subjects with no significant differences between BMI group grades (p=0.491 THA and p=0.473 TKA).

Preoperative obesity was observed in 44% of TKA and 27% of THA subjects. In the obese only 1 in 10 subjects lost 5kg or more over 12 months. Obese patients experienced equivalent improvements in outcome after arthroplasty and rates of satisfaction with surgery to the non-obese.

K Sundaraj J Corbett J Yong Yau Tai L Salmon J Roe

The emergence of patient specific instrumentation has seen an expansion from simple radiographs to plan total knee arthroplasty (TKA) with modern systems using computed tomography (CT) or magnetic resonance imaging scans. Concerns have emerged regarding accuracy of these non-weight bearing modalities to assess true mechanical axis. The aim of our study was to compare coronal alignment on full length standing AP imaging generated by the EOS acquisition system with the CT coronal scout image.

Eligible patients underwent unilateral or bilateral primary TKA for osteoarthritis under the care of investigating surgeon between 2017 and 2022, with both EOS X-Ray Imaging Acquisition System and CT scans performed preoperatively. Coronal mechanical alignment was measured on the supine coronal scout CT scan and the standing HKA EOS.

Pre-operative lower limb coronal alignment was assessed on 96 knees prior to TKA on the supine coronal scout CT scan and the standing HKA EOS. There were 56 males (56%), and 44 right knees (44%). The mean age was 68 years (range 53-90). The mean coronal alignment was 4.7 degrees (SD 5.3) on CT scan and 4.6 degrees (SD 6.2) on EOS (p=0.70). There was a strong positive correlation of coronal alignment on CT scan and EOS (pearson

0.927, p=0.001). The mean difference between EOS and CT scan was 0.9 degrees (SD 2.4). Less than 3 degrees variation between measures was observed in 87% of knees. On linear regression for every 1° varus increase in CT HKA alignment, the EOS HKA alignment increased by 0.93° in varus orientation. The model explained 86% of the variability.

CT demonstrates excellent reliability for assessing coronal lower limb alignment compared to EOS in osteoarthritic knees. This supports the routine use of CT to plan TKA without further weight bearing imaging in routine cases.

S. Lai X. Zhang K. Xue P. Bubra M. Baba

The second wave of COVID-19 infections in 2021 resulting from the delta strain had a significantly larger impact on the state of New South Wales, Australia and with it the government implemented harsher restrictions.

This retrospective cohort study aims to explore how the increased restrictions affected hand trauma presentations and their treatment. Retrospective analysis was performed on patients who underwent hand surgery from the period of June 23 – August 31 in 2020 and 2021 at a level one trauma centre in Western Sydney.

During the second-wave lockdown there was an 18.9% decrease in all hand trauma presentations. Despite widespread restrictions placed on the manufacturing, wholesale, retail and construction industries, there was an insignificant difference in work injuries.

Stay-at-home orders and reduced availability of professional tradespersons likely contributed to an increase in DIY injuries. Significant reductions in metacarpal and phalangeal fractures coincided with significantly curtailed sporting seasons. The findings from this study can assist in predicting the case-mix of hand trauma presentations and resource allocation in the setting of future waves of COVID-19 and other infectious diseases.

K. Mohammed C. Oorschot M. Austen E. O'Loiughlin

We test the clinical validity and financial implications of the proposed Choosing Wisely statement: “Using ultrasound as a screening test for shoulder instability is inappropriate in people under 30 years of age, unless there is clinical suspicion of a rotator cuff tear.”

A retrospective chart review from a specialist shoulder surgeon's practice over a two-year period recorded 124 patients under the age of 30 referred with shoulder instability. Of these, forty-one had already had ultrasound scans performed prior to specialist review. The scan results and patient files were reviewed to determine the reported findings on the scans and whether these findings were clinically relevant to diagnosis and decision-making. Comparison was made with subsequent MRI scan results. The data, obtained from the Accident Compensation Corporation (ACC), recorded the number of cases and costs incurred for ultrasound scans of the shoulder in patients under 30 years old over a 10-year period.

There were no cases where the ultrasound scan was considered useful in decision-making. No patient had a full thickness rotator cuff tear. Thirty-nine of the 41 patients subsequently had MRI scans. The cost to the ACC for funding ultrasound scans in patients under 30 has increased over the last decade and exceeded one million dollars in the 2020/2021 financial year. In addition, patients pay a surcharge for this test.

The proposed Choosing Wisely statement is valid. This evidence supports that ultrasound is an unnecessary investigation for patients with shoulder instability unless there is clinical suspicion of a rotator cuff tear. Ultrasound also incurs costs to the insurer (ACC) and the patient. We recommend x-rays and, if further imaging is indicated, High Tech Imaging with MRI and sometimes CT scans in these patients