Introduction and Objective. In recent studies, robotic-assisted surgical techniques for unicompartmental knee arthroplasty (UKA) have demonstrated superior implant positioning and limb alignment compared to a conventional technique. However, the impact of the robotic-assisted technique on clinical and functional outcomes is less clear. The aim of this study was to compare the gait parameters of UKA performed with conventional and image-free robotic-assisted techniques. Materials and Methods. This prospective, single center study included 66 medial UKA, randomized to a robotic-assisted (n=33) or conventional technique (n=33). Gait analysis was performed on a treadmill at 6 months to identify changes in gait characteristics (walking speed, each degree-of-freedom: flexion–extension, abduction–adduction, internal-external rotation and anterior-posterior displacement). Clinical results were assessed at 6 months using the IKS score and the Forgotten Joint Score. Implants position was assessed on post-operative radiographs. Results. Post-operatively, the whole gait cycle was not significantly different between groups. In both groups there was a significant improvement in varus deformity between the pre- and post-operative gait cycle. There was no significant difference between the two groups in clinical scores, implant position, revision and complication rates. Conclusions. No difference of gait parameters could be identified between medial UKA performed with image-free robotic-assisted technique or with conventional technique

We report the short term follow up of nineteen consecutive PFC sigma unicompartmental knee replacements carried out in our institution with minimum one year follow up. The PFC Sigma medial unicompartmental knee replacement is a fixed bearing, cemented unicompartmenal knee replacement. There are currently no published reports of follow up for the PFC Sigma medial unicompartmental knee replacement. Nineteen patients (nineteen knees) underwent PFC sigma medial unicompartmental knee arthroplasty. The pre-operative diagnosis was osteoarthritis in eighteen patients and osteonecrosis in one patient. There were ten males and nine females with a mean age of sixty four years. All patients had clinical and radiological review at one year. All operations were carried out by the two senior authors (BPR and BL). The mean length of admission was 2.7 days (Range 2–5). There have been no infective or thromboembolic complications to date. The mean oxford scores improved from 41 (Range 26–52) pre-operatively to 18 (15–27) at one year follow-up. The mean range of motion improved from 115 degrees of flexion preoperatively to 125 degrees. All radiographs were satisfactory at one year follow up with no evidence of loosening. We report the promising early results of a new medial unicompartmental knee replacement with at least one year follow up. No early complications or infections were identified in our cohort of patients

Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty, particularly for low volume surgeons. The recent introduction of robotic-arm assisted systems has allowed for increased accuracy, however new systems typically have learning curves. The objective of this study was to determine the learning curve of a robotic-arm assisted system for UKA. Methods A total of 152 consecutive robotic-arm assisted primary medial UKA were performed by five surgeons between 2017 and 2021. Operative times, implant positioning, reoperations and patient-reported outcome measures (PROMS; Oxford Knee Score, EuroQol-5D, and Forgotten Joint Score) were recorded. There was a learning curve of 11 cases with the system that was associated with increased operative time (13 minutes, p<0.01) and improved insert sizing over time (p=0.03). There was no difference in implant survival (98.2%) between learning and proficiency phases (p = 0.15), and no difference in survivorship between ‘high’ and ‘low’ usage surgeons (p = 0.23) at 36 months. There were no differences in PROMS related to the learning curve. This suggested that the learning curve did not lead to early adverse effects in this patient cohort. The introduction of a robotic-arm assisted UKA system led to learning curves for operative time and implant sizing, but there was no effect on patient outcomes at early follow- up. The short learning curve was independent of UKA usage and indicated that robotic-arm assisted UKA may be particularly useful for low-usage surgeons

Abstract. Objectives. Unicompartmental (UKA) and bicompartmental (BCA) knee arthroplasty are associated with improved functional outcomes compared to Total Knee Arthroplasty (TKA) in suitable patients, although the reason is poorly understood. The aim of this study was to measure how the different arthroplasties affect knee extensor function. Methods. Extensor function was measured for sixteen cadaveric knees and then re-tested following the different arthroplasties. Eight knees underwent medial UKA then BCA, then posterior-cruciate retaining TKA, and eight underwent the lateral equivalents then TKA. Extensor efficiency was calculated for ranges of knee flexion associated with common activities of daily living. Data were analyzed with repeated measures analysis of variance (α=0.05). Results. Compared to native, no differences were detected in either extensor moment or efficiency following UKA. Conversion to BCA resulted in a small drop in extensor moment between 70-90° flexion (p<0.05), but when examined in the context of daily activity ranges of flexion, extensor efficiency was largely unaffected. Following TKA, large decreases in extensor moment were measured at low knee flexion angles (p<0.05), resulting in 8–43% reduction in extensor efficiency for daily activity ranges. Conclusion. This cadaveric study found that TKA is associated with inferior extensor function compared to UKA and BCA. This may, in part, help explain the reported differences in function and satisfaction differences between partial and total knee arthroplasty. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Summary Statement. This project proves that Patellofemoral (PF) joint degeneration is not a contraindication to medial unicompartmental knee replacement. Introduction. Unicompartmental knee arthroplasty (UKA) is a recognised procedure for treatment of medial compartment osteoarthritis. Patellofemoral (PF) joint degeneration is widely considered to be a contraindication to medial unicompartmental knee replacement. We examined the validity of this preconception using information gathered prospectively on consecutive patients who underwent UKA using the Repicci II® UKA prosthesis for medial compartment osteoarthritis. Methods. We prospectively collected data on 147 consecutive patients who underwent the Repicci II® UKA for medial compartment osteoarthritis. All operations were performed between July 1999 and September 2000 by the same surgeon. The status of the PF joint was assessed intra-operatively in all patients, and accordingly patients were divided into two groups, one group with a normal PF joint, and the second group with degenerative changes of the PF joint. Variables measured for outcome included the International Knee Society (IKS) score, limb alignment, and range of motion. Radiographs were assessed for progression of disease or failure of implant. The mean follow-up was 9.4 years (range: 5–10.7 years). Patients were reviewed initially at 2 weeks, and then at 6 months post-operatively. They were subsequently reviewed on an annual basis.. All patients completed an IKS score preoperatively and at last follow-up. Age, gender, BMI, length of hospital stay, perioperative complications, all subsequent surgery, including revision of the prosthesis, and survivorship at 10 years was recorded, and results of the 2 groups compared. Results. A total of 147 patients were included in the study. None were lost to follow-up. Sixty nine had associated PF osteoarthritis (group A) while 78 patients had a normal PF compartment when assessed intra-operatively (group B). Post-operative outcomes of the two groups were compared using the ANCOVA analysis with adjustment for pre-operation values firstly, and adjusting also for gender, age, BMI and follow-up secondly. There were no significant differences in terms of IKS, alignment, and flexion between the two groups. However, patients in group B had significantly better extension post-operatively than patients in group A (p<0.05). Conclusion. We concluded that damage to the articular cartilage of the patellofemoral joint to the extent of full-thickness cartilage loss is not a contraindication to the Repicci II® unicondylar knee arthroplasty for medial compartment osteoarthritis. However, extension is significantly improved post-operatively in those patients with minimal or no PF joint degenerative disease

Study of failed Oxford medial unicompartmental knee replacements at the Royal Cornwall Hospital. Objective. we set up a retrospective study to identify the various reasons for failure of oxford medial unicompartmental knee replacements and to assess their outcome following revision. Materials and Method. Over 5 years (2006- 2010) we identified 26 failed unicompartmental knee replacements, which were revised at the Royal Cornwall hospital. We retrospectively analysed the data to include pre-operative and post-operative Oxford score, range of movement, patient satisfaction and the type of implant used. Results. There were 9 males and 17 females in our series with an average age of 65 years (49 to 80). The average follow up was 2.6 years (1 - 4.6 years). The pre-revision Oxford score was 21.3 (12 to 35), which improved to 41.7 (18 to 47) following surgery. Almost all patients benefited with increase in the range of movement. The implants were revised at an average duration of 4 years and 8 months (1 to 17 yrs) following the index operation. The commonest cause of failure was progression of arthritis in the lateral compartment 50 % (13/26), revision for unexplained pain 23 % (6/26) and aseptic loosening 23 % (6/26). There was one case of sepsis 4 % (1/26). We did not come across dislocation of the bearing. The implants were revised using primary or complex primary knee systems. The infected knee was revised using a two-stage technique. Conclusion. Unicompartmental knee replacement is a successful procedure for treating isolated medial compartment arthritis. Commonest indication for revision in our study was progression of arthritis in the lateral compartment. Revision is relatively easy and results of revision are good with high patient satisfaction. Our results are comparable to published data from larger centres

Background. In the United Kingdom (UK), the fastest growing population demographic is the over 85 years of age, but despite this, outcomes achieved in the octogenarian population with a Unicompartmental Knee Replacement (UKR) are underrepresented in the literature. The Elective Orthopaedic Centre, Epsom, has an established patient reported outcome measures (PROMs) programme into which all patients are routinely enrolled. We aim to investigate the outcome of medial UKR using the oxford phase 3 implant in octogenarians. Methods. We retrospectively reviewed our database for patients aged 60–89 years, who underwent a medial unicompartmental Knee Replacement (UKR) using the oxford phase 3 implant, between June 2007-December 2012 (N=395). The patients were stratified into 3 groups based on age, 60–69 (N=188), 70–79(N=149), and 80–89(N=58). Oxford Knee Scores (OKS), Euro-quol (EQ-5D) scores, revision rates, and mortality were compared. Results. We found that the octogenarian group achieved considerable improvement at 1 year with a mean OKS of 39.2 (+/−7.193) and EQ-5D score of 0.791(+/−0.241). And this improvement remained significant at 2 years. There was no difference in functional outcome when the 3 groups were compared. Revision rates for the 3 groups from youngest to oldest were, 8.5%, 4.5%, and 6.9% respectively. Odds ratio and survival analysis showed no significant difference between the groups. Conclusion. In conclusion, we found that octogenarians over a 2 year period achieved similar functional outcome as their younger counterparts. Level of Evidence. IV

Objectives

Unicompartmental knee arthroplasty (UKA) is a demanding procedure, with tibial component subsidence or pain from high tibial strain being potential causes of revision. The optimal position in terms of load transfer has not been documented for lateral UKA. Our aim was to determine the effect of tibial component position on proximal tibial strain.