Objective. To investigate the effectiveness of applying fast track surgery concept in primary total hip arthroplasty. Methods. The data of patients with primary total hip arthroplasty in our department from January 1, 2013 to October 1, 2015 were retrospectively analyzed. The patients were divided into traditional recovery group, enhanced recoverygroup and update enhanced recovery group according to different interventions. The blood loss, transfusion rate, complications rate, postoperative function, length of stay, hospitalization expense and readmission rate were compared between three groups. Results. A total of 435 cases were included. Compared with traditional recovery group, the average blood loss, length of stay and total cases of complication in update enhanced recovery group were reduced 91.44 ml, 1.34 days and 14.05%, respectively, and the differences showed statistical significance. From 2013 to 2015 the hip flexion and abduction degree increased annually, the differences also showed statistical significance. The blood transfusion rate, other complications and hospitalization expense were all reduced, but there were no statistical significance. Conclusions. The emphasis of fast track surgery concept in primary total hip arthroplasty was the management in perioperative period. Through continuous optimization of intervention measures under the guidance of evidence based medicine, it can effectively accelerate recovery, diminish complications and reduce the length of hospital stay

The Fixion expandable nailing system provides an intramedullary fracture fixation solution without the need for locking screws. Proponents of this system have demonstrated shorter surgery times with rapid fracture healing, but several centres have reported suboptimal results with loss of fixation. This is the largest comparative series to be reported to date. We compared outcomes between 50 consecutive diaphyseal tibial fractures treated with a Fixion device at our institution to an age, sex and fracture configuration matched series of 57 fractures at a neighbouring hospital treated with a conventional interlocked intramedullary nail. Minimum follow up time was 2 years. Operating time was significantly reduced in the Fixion group (mean 61 minutes, range 20–99) compared to the interlocked group (88 minutes, 52–93), p< 0.00001. The union rate was no different between the Fixion group (93.9%) and the interlocked group (96.5%), p=0.527. Time to clinical and radiological union was significantly faster in the Fixion group (median 85 days, range 42–243) compared to the interlocked group (119, 70–362), p< 0.0001. The overall reoperation rate was lower in the Fixion series (24.5% vs 38.6%, p=0.121), although the majority of reoperations in the interlocked group were more minor, for screw removal. 3 Fixion nails were revised for fixation failure and 2 manipulations were required for rotational deformities after falls; all of these patients were non-compliant with post-operative instructions. There were no fixation failures in the interlocked group. 3 fractures were noted to propagate during inflation of Fixion nails. The Fixion nail is faster to implant and allows more physiological loading of the fracture, with a faster union time. However, these advantages are offset by a reduction in construct stability. Our results have demonstrated a learning curve with a reduction in complications as our indications were narrowed, avoiding osteoporotic, multifragmentary, unstable fractures and non-compliant patients

Anterior Cruciate Ligament injuries are a common cause of downgrade in Service personnel. The Multidisciplinary Injury Assessment Clinic (MIAC) is a service which patients can be referred to for expert musculoskeletal injury management. MIAC has a Fast Track (FT) referral system in place for imaging, and can subsequently refer isolated ACL injuries to a private provider for reconstruction. We examined this pathway in the South West region which has an overall population at risk of 19775. Over 4 years 173 knee injuries were referred to MIAC, of which 32 were ACL injuries. Of the 29 patients referred for MRI, the median time to imaging was 8 days with FT (n=13, range 2–14) and. 15 days via the NHS (n=16, range 5–64). The majority of injuries were found to involve multiple pathologies (n=19), excluding them from FT surgery. Time to NHS clinic from point of referral took a median time of 54 days, and onward delay to surgery was 47 days. None of the referrals to the private provider for reconstruction were accepted (n=3). We have identified aspects of current referral and treatment pathways that are inefficient and discuss a current solution utilising Military surgeons

Introduction

To reduce several disadvantages many surgeons are not using tourniquet in TKA. Here we compared functional outcome along with pain and blood loss in sixty patients.

Outcome measures are an essential element of our industry: comparing a novel procedure against an established one requires a reliable set of metrics that are comprehensible to both the technologist and the layman.

We surmised that a detailed assessment of function before and after knee arthroplasty, combined with a detailed set of personal goals would enable us to test the hypothesis that less invasive joint and ligament preserving operations could be demonstrated to be more successful, and cost effective. We asked the simple question: how well can people walk following arthroplasty, and can we measure this?

Introduction. A 6cm femoral gain requires 5-Y during normal growth, but only 6–8-W surgically (x30–40 faster). In lengthening surgery, losses of muscle force (MF) and circumferences (MC) are major. Recovery is long, preventing sports till bone fusion. Can we maintain MC and strength throughout the entire lengthening and how?. We monitored for over 30 years patients for muscle force (isokinetic), circumferences, activities (including sports) and food intake, and acted on the 5 principles of the Osteostasis. Materials & Methods. Over 750 femoral lengthening with Full WB Nails (FWBN) got Isokinetic testing (≧1991), circumferences measurements (≧2012; 20-15-10-5-0cm above patella, max-calf, mini/max-ankle), food intake (≧2012), using MyFitnessPal App (≧2016), gradually enforced. Preoperative training along with a daily post-operative training are supervised by our trainers. Recommendations for food intake and activities were provided. Patients noted on a specific App all parameters. Compliance was noted. Results. Instead of a traditional 7–9cm circumference loss for 8–10cm gains using Ex-fix or nails, with FWBN and our protocols, no MC loss could be noted in compliant pre-trained patients, intensive early post-op resistance training, high calory intake (M:>4200, F:>3000; 20–25% Proteins) and supplements (no fat pad increase). Bone fusion could be obtained at the end of lengthening or within short weeks (Healing Index down to 8D/cm). Non-compliant patients (or using morphine), lost weight and MC. Conclusions. Increasing by 8–10cm muscle length, even bilaterally, and maintaining MC during lengthening, is possible, with very fast bone fusion. It requires building up several hundred of grams of muscles. The ‘building up equation’ associating resistance bike from the early post-operative phase with sports, strong food intake with increased protein intake, and added supplements with no morphine medication, proved to boost circumferences and bone fusion. It induced fast recovery, walking and sports capacities

Large cartilage lesions in younger patients can be treated by fresh osteochondral allograft transplantation, a surgical technique that relies on stable initial fixation and a minimum chondrocyte viability of 70% in the donor tissue to be successful. The Missouri Osteochondral Allograft Preservation System (MOPS) may extend the time when stored osteochondral tissues remain viable. This study aimed to provide an independent evaluation of MOPS storage by evaluating chondrocyte viability, chondrocyte metabolism, and the cartilage extracellular matrix using an ovine model. Femoral condyles from twelve female Arcott sheep (6 years, 70 ± 15 kg) were assigned to storage times of 0 (control), 14, 28, or 56 days. Sheep were assigned to standard of care [SOC, Lactated Ringer's solution, cefazolin (1 g/L), bacitracin (50,000 U/L), 4°C storage] or MOPS [proprietary media, 22-25°C storage]. Samples underwent weekly media changes. Chondrocyte viability was assessed using Calcein AM/Ethidium Homodimer and reported as percent live cells and viable cell density (VCD). Metabolism was evaluated with the Alamar blue assay and reported as Relative Fluorescent Units (RFU)/mg. Electromechanical properties were measured with the Arthro-BST, a device used to non-destructively compress cartilage and calculate a quantitative parameter (QP) that is inversely proportional to stiffness. Proteoglycan content was quantified using the dimethylmethylene blue assay of digested cartilage and distribution visualized by Safranin-O/Fast Green staining of histological sections. A two-way ANOVA and Tukey's post hoc were performed. Compared to controls, MOPS samples had fewer live cells (p=0.0002) and lower VCD (p=0.0004) after 56 days of storage, while SOC samples had fewer live cells (p=0.0004, 28 days; p=0.0002, 56 days) and lower VCD (p=0.0002, 28 days; p=0.0001, 56 days) after both 28 and 56 days (Table 1). At 14 days, the percentage of viable cells in SOC samples were statistically the same as controls but VCD was lower (p=0.0197). Cell metabolism in MOPS samples remained the same over the study duration but SOC had lower RFU/mg after 28 (p=0.0005) and 56 (p=0.0001) days in storage compared to controls. These data show that MOPS maintained viability up to 28 days yet metabolism was sustained for 56 days, suggesting that the conditions provided by MOPS storage allowed fewer cells to achieve the same metabolic levels as fresh cartilage. Electromechanical QP measurements revealed no differences between storage methods at any individual time point. QP data could not be used to interpret changes over time because a mix of medial and lateral condyles were used and they have intrinsically different properties. Proteoglycan content in MOPS samples remained the same over time but SOC was significantly lower after 56 days (p=0.0086) compared to controls. Safranin-O/Fast Green showed proteoglycan diminished gradually beginning at the articular surface and progressing towards bone in SOC samples, while MOPS maintained proteoglycan over the study duration (Figure 1). MOPS exhibited superior viability, metabolic activity and proteoglycan retention compared to SOC, but did not maintain viability for 56 days. Elucidating the effects of prolonged MOPS storage on cartilage properties supports efforts to increase the supply of fresh osteochondral allografts for clinical use. For any figures or tables, please contact the authors directly

Introduction. The accuracy of hexapod circular external fixator deformity correction is contingent on the precision of radiographic analysis during the planning stage. The aim of this study was to compare the SMART TSF (Smith and Nephew, Memphis, Tennessee) in-suite radiographic analysis methods with the traditional manual deformity analysis methods in terms of accuracy of correction. Materials and Methods. Sawbones models were used to simulate two commonly encountered clinical scenarios. Traditional manual radiographic analysis and digital SMART TSF analysis methods were used to correct the simulated deformities. Results. The final outcomes of all six analysis methods across both simulated scenarios were satisfactory. Any differences in residual deformity between the analysis methods are unlikely to be clinically relevant. All three SMART TSF digital analyses were faster to complete than manual radiographic analyses. Conclusions. With experience and a good understanding of the software, manual radiographic analysis can be extremely accurate and remains the gold standard for deformity analysis. In-suite SMART TSF radiographic analysis is fast and accurate to within clinically relevant parameters. Surgeons can with confidence trust the SMART TSF software to provide analysis and corrections that are clinically acceptable

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

The Femoral Neck System (FNS) was introduced as an alternative device for the fixation of neck of femur fractures (NOFFs). The purported advantages include superior angular and rotatory stability compared to multiple cancellous screws, via a minimally invasive instrumentation that is simpler than conventional fixed angle devices. There were limited clinical studies regarding the utility of this device. We aimed to study the outcomes of NOFFs fixed with the FNS. This was a single-institution, retrospective review of all undisplaced elderly (≥60 years old) undisplaced young, and displaced young NOFFs fixed with the FNS. Demographics, surgical parameters, radiographic parameters, and clinical outcomes including complications were reviewed. Thirty-six subjects with a median age of 75 [44,89] years old, had NOFF fixation using the FNS. Thirty-one (86.1%) had undisplaced fractures. There were 6 (16.7%), 26 (72.2%), and 4 (11.1%) subjects with Pauwels types 1, 2, and 3 respectively. Thirty-two (88.9%) had posterior tilt of <20º. The mean duration of surgery was 71±18 minutes. Excluding 4 patients whom required revision surgery, 2 patients whom demised, and 10 patients whom defaulted reviews, the mean follow-up duration was 55±13 weeks. Four complications were recorded, namely implant cut out at the femoral head at week 8, breaking of the locking screw at the run-off region at week 22, avascular necrosis at week 25, and a refracture following near fall, causing the fracture to fail in varus at week 7 postoperation. While reasonably fast to instrument, failures still occur and it is likely multifactorial. However, the rate of reoperation is lower than what has been reported for NOFFs fixed with the a fixed-angle device or 3 cancellous screws. In conclusion, the FNS is a reasonably safe instrument to use. Surgeons’ discretion is still needed in patient selection, keeping in mind the need for satisfactory radiological parameters

Abstract. Background. Extracorporeal radiation therapy (ECRT) has been reported as an oncologically safe and effective reconstruction technique for limb salvage in diaphyseal sarcomas with promising functional results. Factors affecting the ECRT graft-host bone incorporation have not been fully investigated. Methods. In our series of 51 patients of primary bone tumors treated with ECRT, we improvised this technique by using a modified V-shaped osteotomy, additional plates and intra-medullary fibula across the diaphyseal osteotomy in an attempt to increase the stability of fixation, augment graft strength and enhance union at the osteotomy sites. We analyzed our patients for various factors that affected union time and union rate at the osteotomy sites. Results. On univariate analysis, age <20 years, metaphyseal osteotomy site, V-shaped diaphyseal osteotomy, extramedullary plate fixation and use of additional plate at diaphyseal ostetomy had a significantly faster time to union while gender, tumor type, resection length, chemotherapy and use of intra-medullary fibula did not influence union time. In multivariate analysis, metaphyseal ostoeotomy, V-shaped diaphyseal osteotomy and use of additional plate at diaphyseal ostetomy were the independent factors with favourable time to union. Although the rate of union was higher with V-shaped diaphyseal osteotomy and use of additional plate and intra-medullary fibula at diaphyseal ostetomy, this difference could not be established statistically. None of the analyzed factors apparently affected the union rate in univariate analysis. Conclusion. Judicious choice of osteosynthesis and augmentation of ECRT graft can enhance incorporation with reduced complications and good functional outcome

Introduction. Distal femur fractures have traditionally been stabilized with either lateral locking plate or retrograde intramedullary nail. Dual-plates and nail-plate combination fixation have the theoretical biomechanical advantage, faster union and allows patients to weight bear immediately. The aim of this study is to compare single vs combination fixation, and evaluate outcomes and complications. Method. We retrospectively reviewed all patients over 60, admitted to Christchurch Hospital, between 1st Jan 2016 and 31st Dec 2022, with an AO 33A/33B/33C distal femur fracture. Patient demographics, fracture characteristics, operation details, and follow up data were recorded. Primary outcomes are union rate, ambulatory status at discharge, and surgical complications. Secondary outcomes include quality of reduction, operation time and rate of blood transfusions. Results. 114 patients were included. (92 single fixation, 22 combination fixation). Baseline demographic data and fracture characteristics did not differ between the cohorts. There was no difference in the rate of union or time to union between the two cohorts. Combination fixation patients were allowed to weight-bear as tolerated significantly more than single fixation patients (50% vs 18.9%, p=0.003). There was no difference in length of hospital stay, transfusion, complication and mortality rates. Medial translation of the distal articular block was significantly lower in the combination fixation cohort (1.2% vs 3.4%, p=0.021). Operation time was significantly longer in the combination fixation cohort (183mins vs 134mins, p<0.001). Discussion. The results show no difference in achieving union or time to union, despite better quality of fracture reduction with dual fixation. This differs to previously published literature. The clear benefit of combination fixation is immediate weight-bearing. As expected, operation times were longer with combination fixation, however this did not translate to more complications. Conclusion. Combination fixation allows earlier weight bearing, at the cost of longer operation times

Ankle fractures in the elderly are common and have a mortality rate of 12% within the first year. Treatment is challenging due to osteoporotic bone and patient co-morbidities. Many patients struggle with non-weight-bearing (NWB) and presently there is no consensus in the literature regarding optimum management of these injuries. We hypothesised that early weight-bearing in frail patients, Clinical Frailty scale (CFS) score of 4 or more will reduce morbidity and allow patients to return to their usual place of residence faster without jeopardising clinical outcome. We conducted a retrospective analysis of 80 patients aged over 65 years managed at Fiona Stanley Hospital for ankle fractures between January 2016 and 2018. Patients were divided into two cohorts: 40 patients managed NWB and 40 who were permitted to weight-bear as tolerated (WBAT). Patients were stratified as fit (CFS 1–3) or frail (CFS 4+). Primary outcomes were one-year mortality, return to primary residence at six weeks and complications. Secondary outcomes included length of acute hospital stay and rehab stay. For frail patients, those managed NWB stayed in rehab for 19 days longer (p=0.03) and had 28% more complications (p=0.03). By 6 weeks, fewer patients returned to full weight-bearing (p=0.03) and fewer patients had returned home (p=0.01). For fit patients, there were no significant differences in primary outcomes between NWB and WBAT. Our novel study categorising patients by CSF demonstrates that early mobilisation in frail patients results in improved outcomes. Currently there is no formal treatment protocol for the management of ankle fractures in the elderly, and we hope that our proposed algorithm will assist surgeons at our institution and elsewhere. Our study suggests that WBAT may benefit frail patients. We propose a protocol to assist in the management of geriatric ankle fracture patients based on clinical frailty scores

Due to shorter hospital stays and faster patient rehabilitation Unicompartmental Knee Replacements (UKR) are now considered more cost effective than Total Knee Joint Replacements (TKJR). Obesity however, has long been thought of as a relative contraindication to UKR due to an unproven theoretical concern of early loosening. This study is a retrospective review of patient reported outcome scores and revision rates of all UKR with recorded BMI performed by the Canterbury District Health Board (CDHB) from January 2011 and September 2021. Patient reported outcome scores were taken preoperatively, at 6 months, 1 year, 5 years and 10 years post operatively. These included WOMAC, Oxford, HAAS, UCLA, WHOQOL, normality, pain and patient satisfaction. 873 patients had functional scores recorded at 5 years and 164 patients had scores recorded at 10 years. Further sub-group analysis was performed based on patient BMI of <25, 25–30, 30–35 and >35. Revision data was available for 2377 UKRs performed in Christchurch during this period. Both obese (BMI >30) and non-obese (BMI <30) patients had significantly improved post-operative scores compared to preoperative. Pre-operatively obese patients had significantly lower functional scores except for pain and UCLA. All functional scores were lower in obese patients at 5 years but this did not meet minimum clinical difference. At 10 years, there was significantly lower HAAS, satisfaction and WOMAC scores for obese patients but no difference in Oxford, normality, WHOQOL, UCLA and pain scores. There was no significant difference in the improvement from pre-operative scores between obese and non-obese patients. All cause revision rate for obese patients at 10 years was 0.69 per 100 observed component years compared to 0.76 in non-obese. This was not statistically significant. Our study proves that UKR is an excellent option in obese patients with post-operative improvement in functional scores and 10 year survivorship equivalent to non-obese patients

Abstract. Background. Multiple devices can stabilise the MTP joint for arthrodesis. The ideal implant should be easy to use, provide reproducible and high quality results, and ideally enable early rehabilitation to enable faster return to function, whilst lessening soft tissue irritation. We prospectively evaluated the combination of the IO-Fix (Extremity Medical, NJ, USA) device which consists of an intra-osseous post and lag screw that offers these features with full bearing of weight after surgery. Methods. 67 feet in 65 patients were treated over 31 months. After excluding patients lost to follow-up, undergoing revision arthrodesis, or concomitant first ray procedures, there were 54 feet in 52 patients available with a minimum 12 month follow-up with clinical and radiographic outcomes. All patients were treated using a similar operative technique with immediate bearing of weight in a rigid soled shoe. Results. The mean MOXFQ score improved from 46.4 (range 18 – 64) before surgery to 30.2 (range 0 – 54) at 6 months after surgery (p=0.02), and 18.4 (range 0 – 36) (p< 0.001) at latest follow-up. Arthrodesis across the MTP joint was achieved in 52 feet (96%), at a mean of 61 days (range 39–201). Non-union was observed in two feet; superficial wound infections in two feet; and metalwork impingement in three feet. Conclusions. In the largest reported series to date, the IO-Fix device achieved a union rate of 96% across the MTP joint when coupled with immediate bearing of weight. Significant improvements were seen in patient reported outcomes with low complication rates

Aim. Antibiotic concentration at the infected site is a relevant information to gain knowledge about deep-seated infections. The combination of antibiotic therapy and debridement is often indicated to treat these infections. At University Hospital Basel the most frequently administered antibiotic before debridement is amoxicillin in combination with clavulanic acid. Amoxicillin is a fragile beta-lactam antibiotic that brings multiple challenges for its quantification. As for many sample materials only little material is available, the aim of this work was to establish a sensitive and reliable quantification method for amoxicillin that only requires a small sample mass. We did not quantify clavulanic acid as we focused on the drug with antibiotic action. Method. Usually discarded sample material during debridement was collected and directly frozen. The thawed tissues were prepared using simple protein precipitation and manual homogenization with micro pestles followed by a matrix cleanup with online solid-phase extraction. Separation was performed by HPLC followed by heated electrospray ionization and tandem mass spectrometry. Results. During method development, amoxicillin showed partial formation of a covalent methanol adduct when performing protein precipitation. Furthermore, multiple in-source products of amoxicillin during ionization could be observed. Adding an aqueous buffer to the samples before protein precipitation and summing up the signals of amoxicillin and its in-source acetonitrile-sodium-adduct led to successful method validation for a calibration range of 1–51 mg/kg using 10 mg of each tissue sample. The imprecision was < 8% over the entire concentration range and the bias was ≤ 10 %. The quantitative matrix effect was < 6 % in six different tissue samples. Until now we measured amoxicillin in samples from nine patients with prosthetic joint infection, bursitis, or an abscess who obtained amoxicillin between 5 hours and 15 minutes before sampling and found concentrations between 1.4 and 35 mg/kg. Conclusions. With this method, we developed a fast, simple, and sensitive quantification assay for amoxicillin in tissue samples with little material that can now be applied to different study samples

Introduction. Frame HI is the #Days for device removal/cm. IM Nail HI is less relevant (31–45 D/cm). Albizzia HI was 33 D/cm (1991–2003). Patients felt fine approximately 1M after end of lengthening (EoL), resuming normal life and sports. This sometimes resulted in implants fractures (e.g. skying before bone fusion). Ideally, the full fusion should occur at the EoL. We decided to shorten the HI to reach this target, optimising all parameters. Materials & Methods. The evolution of care has been monitored over a 32-year clinical experience with a fully weight-bearing nails (Albizzia then G-nail). Monitoring was with X-rays, DEXA, blood bone activity, and in London with special 5G CBCT Scans. We implemented several changes in the Care of patients and measured them according to the ‘Five Principles’ (stability, function, ‘Roads-vascular supply’, ‘Materials-calories’ and ‘Workers-BFC’, with actions on food intake, activity levels and on muscle and bone vascular growths. Results. Preop: training (vascularity, muscle force). Op & Postop: spine morphine, IM sawing preserving BFC, controlled hypo-pressure, low hydration, 50 cm leg elevation, walking, resistance bike, full motion (drainage, muscle reactivation), discharge 3–4h postop (including bilateral). Postop daily intense gym training. POD07-21: Distraction increased to fight non-linear hyper-ossification (44–50 mm gain at POD30) +/- aided by NSAIDs. HI decreased to 12–20D/cm, sometimes 8D/cm with some ‘soft fusion’ during lengthening, hardening within 1W after EoL. Conclusions. The surgeon is not a passive X-rays observer, but has an active role in changing the healing speed and decreasing HI for patient safety. Electro/Magnetic nails (torque 1 Nm) may be clocked by bone fusion, which does not occur with the G-Nail (19 Nm). An holistic vision for patients and treatments at several levels is essential to accelerate bone healing, and to return fast to full normal life, after a short ‘lengthening parenthesis’

Aim. In trauma surgery, the development of biomaterial-associated infections (BAI) is one of the most common complications affecting trauma patients, requiring prolonged hospitalization and the intensive use of antibiotics. Following the attachment of bacteria on the surface of the biomaterial, the biofilm-forming bacteria could initiate a chronic implant-related infection. Despite the use of conventional local and systemic antibiotic therapies, persistent biofilms involve various resistance mechanisms that contribute to therapeutic failures. The development of in vivo chronic BAI models to optimize antibiofilm treatments is a major challenge. Indeed, the biofilm pathogenicity and the host response need to be finely regulated, and compatible with the animal lifestyle. Previously, a Galleria mellonella larvae model for the formation of an early-stage biofilm on the surface of a Kirschner (K)-wire was established. In the present study, two models of mature biofilm using clinical Staphylococcus aureus strains were assessed: one related to contaminated K-wires (in vitro biofilm maturation) and the second to hematogenous infections (in vivo biofilm maturation). Rifampicin was used as a standard drug for antibiofilm treatment. Method. In the first model, biofilms were formed following an incubation period (up to 7 days) in the CDC Biofilm Reactor (CBR, BioSurface Technologies). Then, after implantation of the pre-incubated K-wire in the larvae, rifampicin (80 mg/kg) was injected and the survival of the larvae was monitored. In the second model, biofilm formation was achieved after an incubation period (up to 7 days) inside the larvae and then, after removing the K-wires from the host, in vitro rifampicin susceptibility assays were performed (according to EUCAST). Results. The first model indicate that in vitro biofilm maturation affects the bacterial pathogenicity in the host, depending on the S. aureus strain used. Furthermore, the more the biofilm is matured, the more the rifampicin treatment efficiency is compromised. The second model shows that, despite the fast in vivo biofilm formation in the host, the number of bacteria, either attached to the surface of the K-wire surface or in surrounding tissue of the larvae, was not increased over time. Conclusions. Altogether, these results allow the establishment of biofilm models using G. mellonella larvae in order to understand the impact of biofilm maturation on both the bacterial pathogenicity and the efficiency of antibiofilm treatments

Most studies comparing medial pivot to the posterior stabilised (PS) systems sacrifice the PCL. It is unknown whether retaining the PCL in the Medial Congruent (MC) system may provide further benefit compared to the more commonly used PS system. A retrospective review of a single-surgeon's registry data comparing 44 PS and 25 MC with PCL retained (MC-PCLR) TKAs was performed. Both groups had similar baseline demographics in terms of age, gender, body mass index, and American Society for Anaesthesiology score. There was no significant difference in their preoperative range of motion (ROM) (104º±20º vs. 102º±20º,p=0.80), Oxford Knee Score (OKS) (27±6 vs. 26±7,p=0.72), and Knee Society Scoring System (KS) Function Score (KS-FS) (52±24 vs. 56±24,p=0.62). The preoperative KS Knee Score (KS-KS) was significantly lower in the PS group (44±14 vs. 54 ± 18,p<0.05). At 3-months postoperation, the PS group had significantly better OKS (38±6 vs. 36±6,p=0.02) but similar ROM (111º±14º vs. 108º±12º,p=0.25), KS-FS (73±20 vs. 68±23, p=0.32) and KS-KS (87±10 vs. 86±9,p=0.26). At 12-months postoperation, both groups had similar ROM (115º±13º vs. 115º±11º,p=0.99), OKS (41±5 vs. 40±5,p=0.45), KS-FS (74±22vs.78±17,p=0.80), and KS-KS (89±10vs.89±11,p=0.75). There was statistically significant improvement in all parameters at 1-year postoperation (p<0.05). The PS group had significant improvement in all parameters from preoperation to 3-month postoperation (p<0.05), but not from 3-month to 1-year postoperation (p≥0.05). The MC-PCLR group continued to have significant improvement from 3-month to 1-year postoperation (p<0.05). The MC provides stability in the medial compartment while allowing a degree of freedom in the lateral compartment. Preserving the PCL when using MC may paradoxically cause an undesired additional restrain that slows the recovery process of the patients after TKA. In conclusion, compared to MC-PCLR, a PS TKA may expect significantly faster improvement at 3 months post operation, although they will achieve similar outcomes at 1-year post operation

Combined Partial Knee Arthroplasty (CPKA) is a promising alternative to Total Knee Arthroplasty (TKA) for the treatment of multi-compartment arthrosis. Through the simultaneous or staged implantation of multiple Partial Knee Arthroplasties (PKAs), CPKA aims to restore near-normal function of the knee, through retention of the anterior cruciate ligament and native disease-free compartment. Whilst PKA is well established, CPKA is comparatively novel and associated biomechanics are less well understood. Clinically, PKA and CPKA have been shown to better restore knee function compared to TKA, particularly during fast walking. The biomechanical explanation for this superiority remains unclear but may be due to better preservation of the extensor mechanism. This study sought to assess and compare extensor function after PKA, CPKA, and TKA. An instrumented knee extension rig facilitated the measurement extension moment of twenty-four cadaveric knees, which were measured in the native state and then following a sequence of arthroplasty procedures. Eight knees underwent medial Unicompartmental Knee Arthroplasty (UKA-M), followed by patellofemoral arthroplasty (PFA) thereby converting to medial Bicompartmental Knee Arthroplasty (BCA-M). In the final round of testing the PKA implants were removed a posterior-cruciate retaining TKA was implanted. The second eight received lateral equivalents (UKA-L then BCA-L) then TKA. The final eight underwent simultaneous Bi-Unicondylar Arthroplasty (Bi-UKA) before TKA. Extensor efficiencies over extension ranges typical of daily tasks were also calculated and differences between arthroplasties were assessed using repeated measures analysis of variance. For both the medial and lateral groups, UKA demonstrated the same extensor function as the native knee. BCA resulted in a small reduction in extensor moment between 70–90° flexion but, in the context of daily activity, extensor efficiency was largely unaffected and no significant reductions were found. TKA, however, resulted in significantly reduced extensor moments, leading to efficiency deficits ranging from 8% to 43% in flexion ranges associated with downhill walking and the stance phase of gait, respectively. Comparing the arthroplasties: TKA was significantly less efficient than both UKA-M and BCA-M over ranges representing stair ascent and gait; TKA showed a significant 23% reduction compared to BCA-L in the same range. There were no differences in efficiency between the UKAs and BCAs over any flexion range and TKA efficiency was consistently lower than all other arthroplasties. Bi-UKA generated the same extensor moment as native knee at flexion angles typical of fast gait (0–30°). Again, TKA displayed significantly reduced extensor moments towards full extension but returned to the normal range in deep flexion. Overall, TKA was significantly less efficient following TKA than Bi-UKA. Recipients of PKA and CPKA have superior functional outcomes compared to TKA, particularly in relation to fast walking. This in vitro study found that both UKA and CPKA better preserve extensor function compared to TKA, especially when evaluated in the context of daily functional tasks. TKA reduced knee extensor efficiency by over 40% at flexion angles associated with gait, arguably the most important activity to maintain patient satisfaction. These findings go some way to explaining functional deficiencies of TKA compared to CPKA observed clinically