Abstract

Abstract

Total knee arthroplasty (TKA) aims to alleviate pain and restore joint biomechanics to an equivalent degree to age-matched peers.

Zimmer Biomet's Nexgen TKA was the most common implant in the UK between 2003 and 2016. This study compared the biomechanical outcomes of the Nexgen implant against a cohort of healthy older adults to determine whether knee biomechanics is restored post-TKA.

Patients with a primary Nexgen TKA and healthy adults >55 years old with no musculoskeletal deficits or diagnosis of arthritis were recruited locally.

Eligible participants attended one research appointment. Bilateral knee range of motion (RoM) was assessed with a goniometer. A motorised arthrometer (GENOUROB) was then used to quantify the anterior-posterior laxity of each knee. Finally, gait patterns were analysed on a treadmill. An 8-camera Vicon motion capture system generated the biomechanical model.

Preliminary statistical analyses were performed in SPSS (α = 0.05; required sample size for ongoing study: n=21 per group).

The patient cohort (n=21) was older and had a greater BMI than the comparative group (n=13). Patients also had significantly poorer RoM than healthy older adults. However, there were no inter-group differences in knee laxity, walking speed or cadence. Gait kinematics were comparable in the sagittal plane during stance phase. Peak knee flexion during swing phase was lower in the patient group, however (49.0° vs 41.1°).

Preliminary results suggest that knee laxity and some spatiotemporal and kinematic parameters of gait are restored in Nexgen TKA patients.

While knee RoM remains significantly poorer in the patient cohort, an average RoM of >110° was achieved. This suggests the implant provides sufficient RoM for most activities of daily living. Further improvements to knee kinematics may necessitate additional rehabilitation.

Future recruitment drives will concentrate on adults over the age of 70 for improved inter-group comparability.

Abstract

Our unpublished data has indicated that the perivascular stem cells (PSCs) have increased chondrogenic potential compared to mesenchymal stem cells (MSCs) derived in culture. There has been a recent change in the theory that stem cells work by a paracrine effect rather than differentiation. There are minimal data demonstrating the persistence of implanted stem cells when used for engraftment. This study aimed to develop an autologous large animal model for perivascular stem cells as well as to determine if cells were retained in the articular cartilage defects.

The reactivity of anti-human and anti-ovine antibodies was ascertained using immunohistochemistry and fluorescence-activated cell sorting (FACS). A panel of antibodies were combined and used to identify and purify pericytes (CD34-CD45-CD146+) and adventitial cells (CD34+CD45-CD146-) using FACS. The purified cells were cultured and their identity checked using FACS. These cultured cells demonstrated osteogenic, adipogenic and chondrogenic potential.

Autologous ovine PSCs (oPSCs) were isolated, cultured and transfected using a GFP virus. The transfection rate was 88%. The cells were implanted into an articular cartilage defect on the medial femoral condyle using a hydrogel, four weeks following implantation the condyle was explanted and confocal laser scanning microscopy demonstrated the presence of oPSCs in the defect. Histology did not demonstrate any repair tissue at this early time point.

These data have confirmed the viability our large animal model and that the implanted stem cells were retained in the defect four weeks following implantation.

Opening-wedge High Tibial Osteotomy (HTO) has been shown to be an effective procedure to treat mild to moderate osteoarthritis of the medial compartment of the knee in active individuals. It has also become a mandatory surgical adjunct to articular cartilage restoration when there is preoperative mal-alignment. However, its efficacy is directly correlated with the accuracy of the correction, which must be within 3° of the preoperative target. Achieving this goal is a significant challenge with conventional techniques. Therefore, computer-assisted navigation protocols have been developed; however, they do not adequately address the technical difficulties associated with this procedure. We present an integrated solution dedicated to the opening-wedge HTO. Advantages to the technique we propose include: 1) a minimum number of implanted bone trackers, 2) depth control of the saw, 3) improved 3-D accuracy in the location of the lateral tibial hinge, and 4) micrometric adjustment of the degree of correction. The proof of concept has been completed on all six specimens. The following key points have been validated: a) Compatibility with a minimally-invasive (5–6 cm) surgical incision b) The compact navigation station can be placed close to the operative field and manipulated through a sterile draping device c) Only two trackers are necessary to acquire the required landmarks and to provide 3-D control of the correction. These can be inserted within the surgical wound without any secondary incisions d) The optimised guide accurately controlled the external tibial hinge in all six cases e) The implant cavity could be milled effectively f) The distractor used to complete the desired realignment maintained stability of the distraction until final fixation with the PEEK implant g) The PEEK implant could be fixed to the tibia with excellent stability in a low-profile fashion. The solution presented here has the potential to help surgeons perform a medial opening-wedge HTO more safely and accurately. This will likely result in an increase in the number of HTOs performed for both isolated medial compartment osteoarthritis as well as for lower extremity realignment in association with cartilage restorative procedures.

Perivascular stem cells (PSCs) from lipoaspirate demonstrate increased purity and immaturity with greater engraftment potential than standard mesenchymal stem cells (MSCs). MSCs from the infra-patellar fat pad (IFP) have previously demonstrated increased chondrogenic potential. This study investigated the availability and potential of PSCs harvested from the infra-patellar fat pad of the human knee for musculoskeletal regeneration.

Tissue sections of IFP were stained with markers for PSCs, MSCs and endothelial cells to confirm their presence and location. Samples were obtained from patients undergoing TKR (n=13) or ACL reconstructions (n=10). Pericytes and adventitial cells made up 3.8% and 21.2% respectively of the stromal vascular fraction. The total number of pericytes and adventitial cells were 4.6±2.2×104 and 16.2±3.2×104 respectively. Cells were cultured both separately and combined. Cell identity was ascertained using fluorescence-activated cell sorting, immunocytochemistry and PCR. Cultured PSCs were differentiated using chondrogneic, osteogenic, adipogenic and myogenic medias. Differentiation was determined using Alcian Blue, Alizarin red, Oil Red O and myosin staining.

This study demonstrates that the IPFP is a viable source of PSCs that can be harvested either arthroscopically or through an arthrotomy by orthopaedic surgeons for cell-based musculoskeletal regeneration. Their potential now needs to be compared to conventional MSCs.

Perivascular stem cells (PSCs) from lipoaspirate demonstrate increased purity and immaturity with greater engraftment potential than standard mesenchymal stem cells (MSCs). MSCs from the infra-patellar fat pad (IFP) have previously demonstrated increased chondrogenic potential. This study investigated the availability and potential of PSCs harvested from the infra-patellar fat pad of the human knee for musculoskeletal regeneration.

Sections of IFP were stained with markers for PSCs, MSCs and endothelial cells to confirm their presence and location. Samples were obtained from patients undergoing TKR (n=13) or ACL reconstructions (n=10). Pericytes and adventitial cells made up 3.8% and 21.2% respectively of the stromal vascular fraction. The total number of pericytes and adventitial cells were 4.6±2.2×10⁴ and 16.2±3.2×10⁴ respectively. Cells were cultured both separately and combined. Cell identity was ascertained using fluorescence-activated cell sorting and immunocytochemistry. Cultured PSCs were differentiated using chondrogneic, osteogenic, adipogenic and myogenic medias. Differentiation was determined using Alcian Blue, Alizarin red, Oil Red O and mysosin staining.

This study demonstrates that the IFP is a viable source of PSCs that can be harvested either arthroscopically or through an arthrotomy by orthopaedic surgeons for cell-based musculoskeletal regeneration. Their potential now needs to be compared to conventional MSCs.

This study investigated confocal laser scanning microscopy (CLSM) as a novel method of imaging of chondrocytes on a collagen membrane used for articular cartilage repair. Cell viability and the effects of surgery on the cells were assessed.

Cell images were acquired under four conditions: 1, Pre-operative 2, After handling 3, Heavily grasped with forceps 4, Cut around the edge. Live and dead cell stains were used. Images were obtained for cell counting and morphology. Mean cell density was 1.12–1.68 ± 0.22 × 10⁶ cells/cm² in specimens without significant trauma (n=25 images), this decreased to 0.253 × 10⁶ cells/cm² in the specimens that had been grasped with forceps (p <0.001) (5 images). Cell viability on delivery grade membrane was 86.8±2.1%. The viability dropped to 76.3 ± 1.6% after handling and 35.1 ± 1.7% after crushing with forceps. Where the membrane was cut with scissors, there was a band of cell death where the viability dropped to 17.3 ± 2.0% compared to 73.4 ± 1.9% in the adjacent area (p <0.001). Higher magnification revealed cells did not have the rounded appearance of chondrocytes.

CLSM can quantify and image the fine morphology of cells on a MACI membrane. Careful handling of the membrane is essential to minimise chondrocyte death during surgery.

Proximal femoral fractures remain the most common reason for admission to hospital following orthopaedic injury, with an annual cost of £1.7 billion to the National Health Service and social care services. Fragility fractures of the hip in the elderly are a substantial cause of mortality and morbidity. Revision surgery for any cause carries a higher morbidity, mortality, healthcare- and social economic burden. Which patients suffer failed surgery and the reasons for failure have not been established. The aim of this study was to determine which patients are at risk of failed proximal femoral fracture surgery, the mechanism and cause fo failed surgery and modifiable patient factors associated with failure of hip fracture surgery.

From prospectively collected data of 795 consecutive proximal femoral fractures admitted between July 2007 and July 2008, all peri-operative and post-operative complications were identified.

55 (6.9%) patients were found to have developed a surgical complication requiring further intervention. Risk factors included younger age (p=0.01), smoking (p=0.01) and cannulated screw fixation (p<0.01). Cannulated screw fixation was associated with a 30.9% complication rate. Mechanical cause was the most common reason for cannulated screw failure. Hip hemiarthroplasty most commonly failed by infective causes. Inter-trochanteric and subtrochanteric fracture fixation had very low failure rates. Surgical complication was not found to be associated with an increased mortality but a post-operative medical complication (21.8%) was associated with higher rate of mortality at 4-years (78.5%) and shorter time to mortality. (Median time 0.16 years (95% CI 0.00–0.33).

Open or closed fracture of the tibial shaft is a common injury. There is no long-term outcome data of patients after tibial shaft fracture utilising modern treatment methods. This study assessed pain and function of 1509 consecutive patients with a tibial shaft fracture at 12–22 years following injury. Secondary outcomes included: effect on employment, effect of social deprivation, necessity for hardware removal and comparative morbidity following fasciotomy.

Prospective study of 1509 consecutive adult patients with a tibial shaft fracture (1990–1999) at a high-volume trauma unit. 1034 were male, and the mean age at injury was 40 years. Fractures were classified according to AO, and open fractures graded after Gustillo and Anderson. Time to fracture union, complication rate, hardware removal and incidence of anterior knee pain were recorded. Employment and assessment of social deprivation were detailed. Function was assessed at 12 to 22 years post injury using the Short Musculoskeletal Functional Assessment and Short Form 12 questionnaires.

87% of fractures united without further intervention. Social deprivation was associated with higher incidence of fracture and poorer functional and economic outcomes. 11.5% patients underwent fasciotomy which correlated with poorer long-term outcome. Tibial shaft fracture had high mortality in the elderly. At long-term follow-up 25% of patients have anterior knee pain and 20% ankle discomfort after IM nailing.

This is the largest and longest study assessing functional and economic outcomes of tibial shaft fracture. This is the first paper to describe ankle pain following tibial IM nailing at long-term follow-up.

It is widely accepted by orthopaedic surgeons that antibiotics should be withheld until aspiration has been performed to increase the odds of identifying an organism in septic arthritis. Patients often present to other specialties that may not be as familiar with these principles.

Twenty-five of forty-nine patients with septic arthritis of the native or prosthetic knee had received antibiotics prior to review by the orthopaedic service. Patients were significantly less likely to demonstrate an organism on initial microscopy (entire cohort p=0.001, native knees p=0.006, prosthetic knees p=0.033) or on subsequent culture (entire cohort p=0.001, native knees p=0.017, prosthetic knees p=0.012) of their aspirate if they had received antibiotics. The sensitivity of microscopy dropped from 0.58 to 0.12 when patients had received antibiotics (native knees 0.46 to 0, prosthetic knees 0.72 to 0.27). The sensitivity of the culture dropped from 0.79 to 0.28 when the patient had received antibiotics (native knees 0.69 to 0.21, prosthetic knees 0.91 to 0.36).

Patients treated with empirical antibiotics are less likely to demonstrate an organism on microscopy and culture of their initial aspirate. There is a significantly high false negative rate associated with knee aspiration, particularly with prior administration of antibiotics.

Patient expectations and their fulfilment are an important factor in determining patient-reported outcome and satisfaction of hip (THR) and knee replacement (TKR). The aim of this prospective cohort study was to examine the expectations of patients undergoing THR and TKR, and to identify differences in expectations, predictors of high expectations and the relationship between the fulfilment of expectations and patient-reported outcome measures. During the study period, patients who underwent 346 THRs and 323 TKRs completed an expectation questionnaire, Oxford score and Short-Form 12 (SF-12) score pre-operatively. At one year post-operatively, the Oxford score, SF-12, patient satisfaction and expectation fulfilment were assessed. Univariable and multivariable analysis were performed. Improvements in mobility and daytime pain were the most important expectations in both groups. Expectation level did not differ between THR and TKR. Poor Oxford score, younger age and male gender significantly predicted high pre-operative expectations (p < 0.001). The level of pre-operative expectation was not significantly associated with the fulfilment of expectations or outcome. THR better met the expectations identified as important by patients. TKR failed to meet expectations of kneeling, squatting and stair climbing. High fulfilment of expectation in both THR and TKR was significantly predicted by young age, greater improvements in Oxford score and high pre-operative mental health scores. The fulfilment of expectations was highly correlated with satisfaction.

Distal radius fractures are common, yet the long-term functional outcome of these patients is unknown. This study investigated the long-term functional outcomes after distal radius fracture (DRF) in adult patients 16–23 years following injury. Secondary aims were to establish morbidity, mortality and function related to pattern of injury and patient demographics.

Introduction

It is estimated 5% of patients over 65 years receive warfarin therapy. This paper aims to analyse whether a time delay to hip fracture fixation while waiting for the patients International Normalised Ratio (INR) to return to normal increases the mortality risk.

‘High flexion’ polyethylene tibial tray inserts are available from total knee replacement (TKR) manufacturers. There is currently no published data available that examines how much extra knee flexion these new implants give or if there are any wear consequences for the change in design. The high flexion inserts are narrower posteriorly than standard inserts and have chamfers anteriorly and on the post in cruciate sacrificing designs.

This prospective randomised controlled trial of 100 patients undergoing posterior stabilised TKR compared knee flexion, measured intra-operatively by a computer navigation system, of the standard and high flexion trial inserts in the same knee. Patients were then randomised to receive either a standard or ‘high flexion’ definitive component and the stability assessed. The post-operative knee flexion of all patients was measured at six months.

High flexion inserts did not give significantly more knee flexion than standard inserts either per-operatively at the trial insert stage, or at six months post-op and resulted in marginally more anterior draw. The average per-operative difference in flexion between standard and high flex inserts measured in the same knee was 3.2° (range -4-18°) The average knee flexion at 6 months post op was 106° for both groups. The average change in knee flexion comparing pre and post op was 2.3° for the high flex group and 0.6° for the standard insert group.

Laboratory Tek scan contact pressure analysis at the surface of the standard and high flexion designs was not significantly different, but the thinner polyethylene of the high flexion design raises questions about wear characteristics. High flexion polyethylene inserts are probably not justified in terms of improved knee flexion, but may be a useful option in certain technical circumstances during TKR such as patella baja or if the patella impinges on the post in deep flexion.

There is limited literature regarding the outcome of hip and knee arthroplasty (THR and TKR) in the Super-Elderly (≥80yrs). The aim is to compare the outcome of THR and TKR in the Super-Elderly with a standard-age cohort of patients. From January 2006 to August 2008; 1290 TKR and 1344 THR were performed at the study institute. Comorbidity, length of stay, patient satisfaction, Oxford knee or hip scores, and SF12 scores were recorded prospectively. The Oxford Score and SF12 were recorded at one year. The mode age range was 65-74yrs for TKR (n=492) and THR (n=495), deemed the standard cohort. 185 TKR and 171 THR were performed in the Super-Elderly. Outcome in this cohort was compared to the standard.

The standard cohort had a greater absolute improvement in Oxford knee scores (15.8 and 14.7.p=0.2). Improvement of absolute Oxford hip scores revealed no difference (20.0 and 20.2.p=0.8), but the Super-Elderly had a greater improvement in pain components (11.0 vs.12.0.p=0.05) with a lesser improvement of the functional components (9.0.vs.8.2.p=0.05). There was a greater improvement in the physical component of the SF-12 score in the standard cohort for both TKR and THR (10.6.vs.7.9.p=0.05 and 14.4.vs.10.4.p=<0.01, respectively).

No significant difference was seen in comorbidities, but the Super-Elderly patients had a longer hospital stay for TKR (6.2.vs.8.3.p=0.01) and THR (5.9.vs.9.0.p=0.01).

The Super-Elderly were more satisfied with their surgery (p=0.05).

Super-Elderly patients have comparable outcomes to their younger counterparts and are more satisfied with their surgery, but they may require a longer length of stay.

Background: Tranexamic acid has been shown to be effective in reducing blood loss and transfusion requirement in cardiac surgery and total knee replacement surgery. The most effective dose of tranexamic acid in hip arthroplasty surgery is not yet known. We investigated the effect of a pre-operative bolus 1g intravenous tranexamic acid on intra- and post-operative blood loss, transfusion requirement, and risk of venous thromboembolism following total hip arthroplasty.

Results: We report a cohort comparison study of 73 patients who underwent primary hip arthroplasty. Thirty-six patients received tranexamic acid (TA group), and thirty-seven received no tranexamic acid (control group). Blood loss was measured directly intra-operatively, and indirectly post-operatively by haemoglobin and haematocrit measurement. Deep vein thrombosis (DVT) was investigated by venography.

Patient demographics were similar between both groups. There was no significant difference in intra-operative blood loss between both groups. The early post-operative blood loss and total blood loss were significantly less in the tranexamic acid group. This effect of tranexamic acid was more significant in females who showed a dose-related relationship between tranexamic acid dose and blood loss. Fewer patients in the tranexamic acid group required blood transfusion. There was no increased incidence of DVT in the tranexamic acid group.

The use of a single pre-operative 1g bolus of tranexamic acid administered before surgery is a safe, cost-effective method of reducing post-operative blood loss following total hip arthroplasty. The effect is more significant in females at this dose.

Aim: To assess the functional outcome and longevity of patients who are mentally competent when they sustain an intra-capsular fracture of the femoral neck.

Methods: Prospective cohort study of fifty female patients over the age of seventy years of age with a displaced intra-capsular fracture of the femoral neck. Patients with known, cognitive impairment terminal illness or active infection were excluded from the study. Patients were treated with a large head total hip replacement. Functional outcome was assessed using the the Barthel index score and the Charnley-modified Merle d’Aubigne score yearly for five years. The Oxford hip score was also recorded annually from three to ten years post op. The date and cause of death were recorded from hospital notes and death certificates.

Results: The mean age at time of femoral neck fracture was 81 years. Three patients died before discharge from hospital. The mortality rates were 18% at twelve months, 28% at two years, 44% at five years and 92% at ten years. Those patients surviving had mean Oxford scores of 24 at 3 years, 26 at 5 years, 23 at 7 years and 25 at ten years. The cause of death was ischaemic heart disease in 22%, cancer in 10%, bronchopneumonia in 12% and simply ‘old age’ in 14%.

Conclusion: Elderly female patients who are not cognitively impaired at the time of displaced intra-capsular fracture of the femoral neck have a 56% chance of living five years. Function scores in the survivors are maintained, and are better than would be expected if the patients had undergone hip hemiarthroplasty. Total hip replacement in this population may be justified.

Aims: Minimum ten year clinical, radiological and postmortem results of the flexible Cambridge Cup. This acetabular prosthesis was designed to replace the horseshoe shaped articular cartilage and provide physiological loading with minimal resection of healthy bone.

Method: Fifty female patients aged over 70 years with a displaced intra-capsular fracture of the femoral neck were recruited to the ethically-approved prospective study. They underwent implantation of the Cambridge Cup, which has an outer polybutyleneterephthalate shell and an inner UHMWPE bearing, with a Thompson-type hemiarthroplasty. The cups were manufactured with a 60μm plasma-sprayed coating of hydroxyapatite. This was removed from half the cups to simulate the effects of long-term HA resorption. Implants were sterilised by gamma irradiation in air. Independent clinical and radiological assessments were undertaken before discharge, at 6 weeks, one year, 18 months, two -, five-, seven- and ten years. Patients were scored using the Barthel Index, the Charnley-modified Merle d’Aubigne scores and latterly the Oxford hip score. The date and cause of death were obtained from hospital records and death certificates. Fifteen Cambridge Cups were retrieved post-mortem for histological and wear analysis

Results: The mean functional scores recovered to levels before fracture. These scores decreased with advancing age at five years. The mortality rates were 16%, 28%, 46% and 92% at 1, 2, 5 and 10 years. The Oxford hip scores in patients surviving between five and ten years were maintained.

The HA coated implants remained asymptomatic. Three uncoated components required revision for migration. No evidence of accelerated UHMWPE wear was seen on retrievals or radiographs. Histological analysis of the retrieved HA coated specimens showed excellent bony fixation, uncoated cups showed predominantly fibrous tissue.

Conclusion: The uncemented Cambridge Cup was implanted in a challenging environment of osteoporotic bone. Clinical, radiographic and post-mortem results up to ten years are excellent.

Mountain biking is increasing in popularity worldwide. The injury patterns associated with elite level and competitive mountain biking are known. This study analysed the incidence, spectrum and risk factors for injuries sustained during recreational mountain biking.

The injury rate was 1.54 injuries per 1000 biker exposures. Males were more commonly injured than females, with those aged 30–39 years at highest risk. The commonest types of injury were wounding, skeletal fracture and musculoskeletal soft tissue injury. Joint dislocations occurred more commonly in older mountain bikers. The limbs were more commonly injured than the axial skeleton. The highest hospital admission rates were observed with head, neck and torso injuries. Protective body armour, clip-in pedals and the use of a full-suspension bicycle confer a significant protective effect.

Purpose: To investigate the mode of presentation, management and outcome of ischaemic contracture following a supracondylar fracture with a pink, pulseless hand.

Methods: We reviewed the database at our tertiary referral unit to identify cases over a 20 year period who had been referred for complications of a supracondylar fracture and/or a Volkmann’s ischaemic contracture.

Results: We identified 20 children with Volkmann’s ischaemic contracture following a supracondylar fracture. Of these, 4 patients (mean age 5, range 2–11) were referred to us with evidence of an ischaemic contracture but they had always had a pink albeit pulseless hand. Two of these 4 had undergone vascular exploration at 48 hours and at 72 hours but despite this developed an ischaemic contracture.

The 2 patients with the most severe contractures have undergone surgical intervention for their contracture, and 2 were managed conservatively with splinting. All 4 cases have residual problems with hand function (mean follow-up 5.5 years, range 2–11).

Conclusions: Volkmann’s ischaemic contracture should be a preventable condition. The pink albeit pulseless hand is at increased risk of ischaemic muscle and nerve damage and should not be ignored as the consequences are potentially devastating.

Significance: Clinicians must consider whether they feel that their management protocols for the pink, pulseless hand are robust and defensible.

Metal-on-metal articulations are increasingly used in THR. Hypersensitivity reactions to the metal ions can occur. The symptoms and signs are similar to a patient presenting with an infected prosthesis. Correct diagnosis before revision surgery is crucial to implant selection and operation planning. We present a practical approach to this diagnostic problem.

The history, clinical findings, hip scores, radiology, serum metal ions, ESR, C-RP, hip arthroscopy and aspirate results, synovial fluid metal ion levels, labelled white cell/colloid scan, 99m-technetium scan, revision hip findings and histology of a typical patient who had an allergic response to a metal-on-metal hip articulation are presented, and how the findings differ from a patient with an infected implant. Clinical examination, hip scores and serum metal ion levels were repeated one year after revision of the metal-on-metal hip articulation to a ceramic-on-ceramic.

In hypersensitivity, the periarticular tissues undergo lymphocyte-dominated infiltration, the histology differs from that found in infection. The white cell labelled/colloid scan also uses this difference for diagnosis. Hip aspiration is the single best investigation for infection.

Conclusion: There is no single investigation available in most hospitals that will reliably differentiate infection from allergy in the painful THR. Hip aspiration, labelled white cell/colloid scan and histology obtained from hip arthroscopy biopsy are the most useful investigations.

Intro: Anatomical abnormality associated with severe developmental dysplasia of the hip presents technical difficulties at THR. Patients often present at a younger age and may have had previous surgery.

We report the difficulties encountered during surgery, and the long term results of patients who had Crowe 3 or 4 DDH and a technically difficult primary hip arthroplasty using the modular S-ROM stem.

Method: 28 patients were entered into the prospective trial. The average age of the patient at surgery was 45 (range 23–74 years). All patients underwent surgery by the senior author using the S-ROM femoral stem. They were followed up for an average of 10 years (range 5–16 years), clinical scores recorded by a clinician other than the surgeon and radiographs were examined by an independent radiologist.

Results: 21 patients required a significant autologous bone graft, one patient had a large allograft and six patients required femoral shortening at the time of their THR.

4 patients had a technical complication during surgery. The average pre-op Harris Hip Score was 37, at 5 years it was 83, and at 10 years 81. The SF12 measure of physical and mental wellbeing was 43.90 physical/54.48 mental at 5 years, and 41.64 physical/54.03 mental at 10 years. The WOMAC average score (the lower the score the better the outcome) was 27 at 5 years and 23 at 10 years.

None of the S-ROM stems had been revised, 2 hips had undergone acetabular revision and one hip had a liner exchange. None of the S-ROM stems were loose at latest follow-up. Four hips had osteolysis in Gruen zone 1, one hip had osteolysis in zone 7, and one hip had osteolysis in zone 1 and 7. There was no evidence of osteolysis around or distal to the sleeve.

Conclusion: The S-ROM stem used in primary THR shows excellent results at 10 years in patients with anatomical abnormality related to severe DDH.

S-ROM stem/sleeve modularity allows femoral component anteversion independent of the position of best fit in the proximal femur, and helps overcome the technical difficulty in these patients.

Bone allograft use in trauma and orthopaedic surgery is limited by the potential for cross infection due to inadequate acceptable decontamination methods. Current methods for allograft decontamination either put the recipient at risk of potentially pathogenic organisms or markedly reduce the mechanical strength and biological properties of bone. This study developed a technique of sterilization of donor bone which also maintains its mechanical properties.

Whole mature rat femurs were studied, as analogous to strut allograft. Bones were inoculated by vortexing in a solution of pathogens likely to cause cross infection in the human bone graft situation. Inoculated bones were subjected to supercritical carbon dioxide at 250 bar pressure at 35 degrees celsius for different experimental time periods until a set of conditions for sterilization was achieved. Decontamination was assessed by vortexing the treated bone in culture broth and plating this on suitable culture medium for 24 hours. The broth was also subcultured. Controls were untreated-, gamma irradiated- and dehydrated bone. Mechanical testing of the bones by precision three-point bending to failure was performed and the dimensions and cross-section digitally assessed so values could be expressed in terms of stress.

Mechanical testing revealed bone treated with supercritical carbon dioxide was consistently significantly stronger than that subjected to gamma irradiation and bones having no treatment (due to the minor dehydrating effect of the carbon dioxide). Terminal sterilization of bone is achieved using supercritical carbon dioxide and this method maintains the mechanical properties.

The new technique greatly enhances potential for bone allograft in orthopaedic surgery.

Intro: Total knee replacement (TKR) manufacturers offer the option of high flexion tibial tray inserts. The polyethylene is narrower posteriorly than the standard insert and comes with the theoretical risk of reduced longevity due to thinner implant. This trial studied both the intra-operative and post-operative difference in knee flexion.

Method: 100 consecutive patients undergoing posterior stabilized Genesis II TKR with Brainlab navigation were studied. The flexion of each knee was assessed per-operatively using the Brainlab navigation system for both the high flex and standard tibial insert trials. Patients were then randomized to receive either a high flex or standard definitive implant and the knee flexion measured clinically with a goniometer six months post op.

Results: Intra-operatively the high flexion insert trial flexed more than the standard flex option by 3.2 degrees. Clinically at six months post op there was no difference in knee flexion between the two groups.

Conclusion: There is no clinical difference in knee flex-ion at six months post-op in patients with a high flex or standard tibial insert. However, we believe that in certain technical circumstances the high flex option is a valuable option for the surgeon to have available.

Objective To survey current antithrombotic prophylaxis regimes of foot and ankle surgeons in the UK, and their self-reported rates of deep vein thrombosis (DVT) and pulmonary embolism (PE).

Method A postal questionnaire was sent to 180 members of the British Orthopaedic Foot and Ankle Society requesting regime and types of antithrombotic prophylaxis (if any) used for elective forefoot, elective midfoot, open elective ankle, elective ankle arthroscopy and ankle trauma surgery, and numbers of cases of DVT and PE.

Results Ninety surgeons responded (50%). Surgeons had been practising as consultants with a special interest in foot and ankle surgery for an average of 8.9 years, and performed an average of 24 foot and ankle cases per month. Ten per cent never used antithrombotic prophylaxis in foot and ankle surgery, 64/90 used it routinely for certain cases, and 17/90 used it routinely in all patients. The most common types of prophylaxis were low molecular weight heparin, aspirin and TED stockings. In an approximate overall total of 223,500 foot and ankle cases, the self reported DVT rate was 0.1%. There were 45 reported PEs (0.02%). There was no significant difference in the rate of DVT between those who never, sometimes or always used prophylaxis. Only 5.5% surgeons employed a specific screening protocol to identify high risk patients.

Discussion There is widely varying clinical antithrombotic practice among foot and ankle surgeons in the UK, with no significant difference in reported DVT rates. This has implications for clinical practice and medicolegal issues.

Aims: To assess the impact of ring fencing of elective orthopaedic arthroplasty patients on rates of post-operative infections including methicillin resistant staphlococ-cous aureus (MRSA). Method: For one year the rate of all postoperative infections in patients undergoing hip or knee arthroplasty were recorded (including chest, urinary, wound etc). Patients were treated using standard precautions against infection employed in most modern orthopaedic units. The elective ward was then ring fenced; admitting only elective patients who had clear swabs for infection taken in the community. Patients of other specialities and trauma were excluded. In addition barrier nursing and infection control measures were employed. The infection rate was then recorded for one year. Results: Prior to ring fencing there were 43 post-op infections in 417 patients (9 MRSA). In the ring fenced patients there were 15 infections in 488 patients (no MRSA). Conclusions: Ring fencing elective orthopaedic beds reduced overall infection rate, eradicated MRSA and allowed 17% more joint replacements to be performed. We recommend these precautions in all orthopaedic centres.

For one year (July 1999-July 2000), the rate of post-operative infection in patients undergoing joint arthroplasty was recorded (including wound, chest UTI etc). Standard precautions against infection used in most orthopaedic units in the UK were employed.

In July 2000 elective orthopaedic beds were ‘ring-fenced’. Only elective orthopaedic patients who had negative swabs for MRSA in the community were admitted. Eradication therapy was commenced in the community if appropriate. Trauma and other specialties’ patients were excluded.

In addition to standard precautions, nurses wore a disposable apron and gloves for each intervention. Antibacterial hand cleanser was installed by each bed, and staff expected to use it after each consultation. Doctors left jackets at the door and donned clean white coats for ward rounds. These were left on the ward and laundered daily. New cleaning regimes were adopted.

Pre ring-fencing, 417 joint replacements were performed and 60 patients were cancelled due to no bed. There were 43 post-op infections, 9 of which were MRSA. In the year post ring-fencing, 488 joint replacements were performed; there were no cancellations due to bed shortage. There were 15 post-op infections and no MRSA.

Eight patients swabbed positive for MRSA in the community, and were admitted after eradication therapy with no infections post-op.

We concluded that ‘ring-fencing’ of elective orthopaedic beds reduced cancellations, reduced the overall infection rate and abolished MRSA.

We have continued to ring-fence elective beds following this study, and recommend these precautions be employed in all units dealing with elective orthopaedic patients.

Many methods have been described over the past 5 years for repair of articular cartilage defects. The best reported results have been from the use of autologous chondrocyte transplantation (ACT)(1) and mosaicplasty.(2) There have, however, been no prospective clinical trials of these two methods. In this trial 70 patients were prospectively randomized to receive either autologous chondrocyte transplantation (37) or mosaicplasty (33) in the knee. 37 patients were female and 33 male. The average age was 32 years (16 – 44). The indications for surgery were persistent pain and mechanical symptoms in the knee with an isolated defect of the articular cartilage. 38 (56%) were post-traumatic, 12 (16%) due to osteochondritis dissecans, 10 (14%) due to previous meniscectomy, and 10 (14%) due to chondromalacia patellae. The size of the defects ranged from 2cm2 to 12cm2 (mean 4.8cm2). There were 35 defects on the medial femoral condyle, 13 on the lateral femoral condyle, 17 on the patella and 5 on the trochlear. 31 patients were undergoing primary surgery and 39 secondary surgery. All were independently reviewed using the Visual Analogue Pain Score, the Cincinatti Pain Score and the Stanmore Score. Patients were arthroscoped at one year with MRI scan and biopsies where possible.

Results: The visual analogue pain score improved overall from a mean of 5.4 (range 3.4 – 7.4) pre-operatively to 3.9 (1.8 – 5.1) at one year review. Similarly the Cincinatti pain score improved from 6.5 pre-operatively to 10.2 post-operatively and the Cincinatti function score improved from 46 to 62 at one year before sport commenced. Overall 71% (49) patients were excellent or good on the clinical scoring scales, 15% (11) were fair, and 14% (10) were poor. The 10 poor results were no different from the main group with regard to age, sex, pain level or site or size of lesion. However, 5 were secondary procedures, 2 had multiple lesions, and 3 had had previous ruptured anterior cruciate ligaments. Arthroscopy and biopsy of 21 lesions so far after one year has shown mature articular cartilage in 2, and immature cartilage in 19. In all cases there was bonding of the repair tissue to the underlying bone. This study is already clarifying the role of ACT and mosaicplasty in the management of cartilage defects in the knee and also the necessity for the use of periosteal covering membrane.

This study examined the reliability of pre-operative templating of the femur in total hip replacement (THR), and the accuracy of the templates provided by leading arthroplasty manufacturers. Templates are provided by arthroplasty manufacturers to be used with pre-operative radiographs as an aid to selecting the appropriate size of prosthesis that will allow an optimal cement mantle in THR. These templates vary in magnification from 10-20% (Mode 15%).

A retrospective review of the pre- and post-operative AP pelvis radiographs of 50 randomly selected patients who underwent THR in 1998 was performed. The radiographs were taken using the uniform standard technique. The magnification of the post-op radiograph was calculated by measuring the femoral head size. This was compared to the magnification of the pre-op radiographs using the ratio of the inter-teardrop distance. The post-operative radiographs were templated using a 15% template and compared to the size of prosthesis inserted.

The mean radiograph magnification was 22.5% (range 10.7 to 32.6%), with the majority (74%) between 20–25%. The 15% template oversized the prosthesis in 68% of cases. A 10% template would have been inaccurate in 96% of our sample group.

In a standard AP pelvis radiograph, the only variable that affects magnification is the extent to which the patient’s soft tissues raise the bony structures away from the plate. This variation in magnification renders preoperative templating of the femur in THR unreliable. Accuracy could be improved by using templates with a magnification of 22.5%.