Early results of fixed-bearing unicompartmental knee replacement designed for the lateral compartment

Abstract

Background Isolated lateral compartment knee arthritis is less prevalent than medial. While the reported results of medial unicompartmental knee replacement (UKR) have been good and comparable to total knee replacement, the results of lateral UKR have been mixed. We present the short-term results and survivorship of a fixed-bearing UKR designed specifically for the lateral compartment. Methods We report the result of 130 primary fixed-bearing lateral Oxford (FLO) UKRs (123 patients) performed between 2015 and 2019 with a minimum follow-up of 1 year. The indications for lateral UKR were: isolated lateral osteoarthritis (n = 122), post-trauma (n = 5) and osteonecrosis (n = 3). The mean age was 69.1 (± 11.6), mean BMI 28.4 (± 4.9), 66.9% female, 60% right-sided, and mean follow-up 3 (range 1–4.8 years, standard deviation ± 1) years. The primary outcome measure was the Oxford knee score (OKS). Survival analysis was performed with “revision for any reason”, “reoperation”, and “implant failure” as the endpoints. Results Six patients died from unrelated reasons. None of the implants failed. One required the addition of a medial UKR for medial arthritis. There were no other reoperations. At 4 years, the survival for implant failure was 100% and for both revision and all reoperations was 99.5% (95% CI 96.7–99.9%). At the last review, at a mean of 3 years, the mean Oxford knee score was 41. Conclusion The good survivorship and outcome scores suggest that UKR designed for the lateral compartment is an excellent alternative to total knee replacement in selected patients with isolated lateral tibiofemoral arthritis at short-term follow-up.

Fixed-bearing is superior to mobile-bearing in lateral unicompartmental knee replacement: a retrospective matched-pairs analysis

“…The dislocation rate of 10% is noticeable higher than in previous reports, even if all surgeries were performed by well-experienced senior surgeons who were familiar with the modified surgical technique [41,42]. In contrast, survivorship of FB-UKR for the endpoint "revision for any reason" was significantly higher with 98.3% at 2.7 years than for MB-UKR and is in line with other recent studies of lateral FB-UKR [3,35].…”

Physical Activity of Young Patients following Minimally Invasive Lateral Unicompartmental Knee Replacement

“…We demonstrate excellent clinical results with a high mean OKS of 39.9 and 81.1% of our patients having a good to excellent outcome according to the OKS criteria. Comparable results have been reported for patients following lateral FB-UKR [ 37 , 38 ] and lateral MB-UKR [ 39 , 40 ]. The mean postoperative ROM of 136° in our cohort appears to be higher than those of earlier reports of patients following lateral UKR [ 41 , 42 , 43 ].…”

Survival of lateral unicompartmental knee arthroplasty at short‐, mid‐, and long‐term follow‐up: a systematic review and meta‐analysis

“…Two thousand one hundred and sixty studies were then screened for eligibility based on their titles and abstracts. After a screening and retrieval process, 40 articles received a full‐text evaluation for eligibility and finally, 26 studies 7–9,15–37 were included in this meta‐analysis. Detailed information regarding study selection is displayed in Figure 1.…”

“…Refinements in patient selection criteria, surgical technique as well as instrumentation, and implant design aimed at better accommodating the lateral compartment, have greatly contributed to the increase in implant survivorships during this period. 8,16,19,20,22,28,32,37 It is therefore likely that the exclusion of a study 21 published in 1996 could reduce heterogeneity and improve the 10-year survival in our sensitivity analysis. Surprisingly, we further stratified studies into two subgroups according to the publication year of 2015 and found significantly lower survivorships at longer-term follow-up (15-20 years) among recently published studies.…”

“…Research into lateral UKA has flourished in the last decade as the procedure is becoming more frequent. Refinements in patient selection criteria, surgical technique as well as instrumentation, and implant design aimed at better accommodating the lateral compartment, have greatly contributed to the increase in implant survivorships during this period 8,16,19,20,22,28,32,37 . It is therefore likely that the exclusion of a study 21 published in 1996 could reduce heterogeneity and improve the 10‐year survival in our sensitivity analysis.…”