Introduction. The alternative kinematic alignment (KA) technique for total knee arthroplasty (TKA) aims at restoring the native joint line orientation and laxity of the knee. The goal is to generate a more physiological prosthetic knee enabling higher functional performance and satisfaction for the patient. KA TKA have only been reported so far with cruciate retaining and posterior-stabilised designs. Similarly, medial pivot design for TKA has been recently developed to enable more natural knee kinematics and antero-posterior stability. The superiority of KA technique and medial pivot implant design is still controversial when compared to current practice. Our study aims to assess the value of KA TKA when performed with medial pivot implants. Methods. We conducted a retrospectively matched case-control study. Clinical data was prospectively collected on patients as part of an ongoing ODEP study. Thirty-three non-selected consecutive KA TKAs performed by the lead author were matched to a control group of 33 measured resection with mechanically aligned (MA) TKAs performed by other consultant surgeons. Patients were matched for sex, age, BMI and pre-operative Oxford Knee Score (OKS). Pre-operative median OKS was 21 points (max 48), mean age was 69, mean BMI 31, and there were 21 female patients in both arms. The medial pivot GMK Sphere implant (Medacta, Switzerland) was used in all cases. OKS and EQ-5D scores were measured pre-operatively and at 1-year post-op. Patient outcome satisfaction scores were assessed at 1-year follow-up using a visual analogic scale (VAS). Pre- and post-operative knee radiographs were analysed using TraumaCad software. Results. No reoperation or revision was recorded in either group. KA patients were found to have higher OKS (median 44 Vs 42, p=0.78), satisfaction (median 99/100 Vs 90/100, p=0.28), and EQ-5D improvement (mean 0.34 Vs 0.28, p=0.21) compared to MA patients; however, none of the differences discovered were statistically significant. In addition, KA patients had a femoral component that was on average, 3.5° more valgus orientated (aLDFA 84° Vs 80°, p<0.05) and 2.1° more flexed (4.4° Vs 2.3°, p=NS), and a tibial component with 3.6° (aMPTA 86° Vs 89.6°, p<0.05) and 3.9° (5.5° Vs 1.6°, p<0.05) increased varus orientation and posterior slope, respectively. Conclusion/Discussion. KA TKA performed with medial pivot implant design has shown good safety and efficacy at early-term. The physiological implantation provided by the KA technique seems to be clinically beneficial compared to MA implantation, although, the measured differences did not show statistical significance. Having a low study power and high ceiling effect of outcome measure tools may partly explain our results. Early results for KA TKA are encouraging and longer follow-up is warranted to assess longevity of results. For any figures or tables, please contact authors directly

INTRODUCTION. Historically, the clinical performance of novel implants was usually reported by designer surgeons who were the first to acquire clinical data. Regional and national registries now provide rapid access to survival data on new implants and drive ODEP ratings. To assess implant performance, clinical and radiological data is required in addition to implant survival. Prospective, multi-surgeon, multi-centre assessments have been advocated as the most meaningful. We report the preliminary results of such a study for the MiniHip™femoral component and Trinity™ acetabular component (Corin Ltd, UK). METHODS. As part of a non-designer, multi-surgeon, multi-centre prospective surveillance study to assess the MiniHip™stem and Trinity™ cup, 535 operations on 490 patients were undertaken. At surgery, the average age and BMI of the study group was 58.2 years (range 21 to 76 years) and 27.9 (range 16.3 to 43.4) respectively. Clinical (Harris Hip Score, HHS) and radiological review have been obtained at 6 months, 3 and 5 years. Postal Oxford Hip Score (OHS) and EuroQol- 5D (EQ5D) score have been obtained at 6 months and annually thereafter. To date, 23 study subjects have withdrawn or lost contact, 11 have died, and 9 have undergone revision surgery. By the end of March 2018, 6 month, 1, 2, 3, 4, and 5 year data had been obtained for 511, 445, 427, 376, 296 and 198 subjects respectively. RESULTS. Implant revision rate is 1.68% (9/535), with revision for any reason as an endpoint; four of the nine involved the revision of the femoral component. At the 5-year time point, mean OHS had improved from 21.3 to 42.5 (p<0.01), EQ5D from 0.42 to 0.82 (p<0.01), and HHS from 51.6 to 92.5 (p<0.01). Radiological analysis is ongoing, and thus far has revealed more variation in stem alignment than is usually observed for more conventional length femoral components. This may indicate that optimal alignment of calcar loading short stems is different to that of longer, medullary canal aligned implants, consistent with the neck-stabilised design of the MiniHip™ stem. No other significant radiological findings were noted. During surgery, 31 calcar fractures were sustained, of which 20 were treated with cerclage wiring, 1 with femoral grafting and the remainder required no treatment. None of the hips with calcar fractures have been revised to date. DISCUSSION. The clinical and radiological performance of the MiniHip™ femoral stem is consistent with established femoral implants. Longer surveillance will determine whether this performance is maintained. Patients in this study will be continued to be followed-up and reviewed at the 7 and 10-year time points. CONCLUSION. The MiniHip™ stem is safe and efficacious at mid-term follow-up

Introduction. The need for the stringent surveillance of new devices was recognised by the NICE review of hip replacement surgery in 2000 and led to the Orthopaedic Data Evaluation Panel (ODEP) developing criteria for post-marketing surveillance (PMS) studies. This requirement has been reinforced by the recent recall of ASR devices. Methods. The South West London Elective Orthopaedic Centre's (EOC's) comprehensive outcomes programme has been adapted to manage and coordinate multi-centre, multi-surgeon, PMS studies. The system allows any schedule and combination of patient-reported outcome measures (PROMS), clinical and radiological assessments, and complications to be collected. Typically, PROMS are collected pre-operatively and yearly by post. Baseline clinical assessment is undertaken pre-operatively, with baseline radiological assessments pre- and post-operatively. Subsequent clinical and radiological assessments are usually obtained at the ODEP-mandated time points of 3, 5, 7 and 10 years post-operatively. Patients are telephoned twice yearly to document complications and any impending change of address. Results. EOC co-ordinated studies extend the ODEP criteria to provide high quality evidence on implant survivorship and patient outcome. In one study, over 500 subjects are under review. The operations were undertaken by twelve surgeons, at three centres. At 3 years participant withdrawal is 4%, mortality 4%, loss to follow-up 1% and revisions 0.5%. Average annual return of PROMS is 94%, and the percentage of invited patients returning for a 3 year review is 81%. Discussion. The EOC system provides a cost-effective method for the long-term follow-up of implants through multi-site, multi-surgeon national, and international, PMS studies. Participation by high-volume centres facilitates both rapid recruitment of study participants and the infrastructure required to maintain consistent data quality. The acquired information gives timely information to surgeons, manufacturers and healthcare purchasers. We advocate adoption of the EOC PMS model for all new implants that are introduced to the UK market