Lateral unicompartmental knee replacement: Survivorship and clinical experience over 21 years

Abstract

We describe 88 knees (79 patients) with lateral unicompartmental osteoarthritis which had been treated by the St Georg Sled prosthesis. At a mean follow-up of nine years (2 to 21) 15 knees had revision surgery, nine for progression of arthritis, six for loosening, four for breakage of a component and four for more than one reason. Six patients complained of moderate or severe pain at the final follow-up. Only five knees were lost to follow-up in the 21-year period. We performed survivorship analysis on the group using revision for any cause as the endpoint. At ten years the cumulative survival rate was 83%, and at 15 years, when ten knees were still at risk, it was 74%. Based on our clinical results and survival rate the St Georg Sled may be considered to be a suitable unicompartmental replacement for isolated lateral compartment osteoarthritis.

Long-term Results With a Lateral Unicondylar Replacement

“…Besides osteotomy for correction of a valgus deformity [17], surgical treatment of lateral femorotibial OA includes either total or unicompartmental arthroplasty [5,11,13,17,21]. When there is full loss of cartilage in the affected compartment, UKA may offer an alternative to TKA when the other compartments are preserved with the potential advantage of reduced morbidity and preservation of bone stock [2,12].…”

“…Furthermore, the mean followup (12.6 ± 4.2 years) is one of the longest reported in the literature with patients followed over 23 years (Fig. 4A-B) [5,13,17,22,27,30,32,33]. Finally, to consider the changes concerning the implants and the indications over time, we performed a direct comparison of the survivorship between the group of patients operated on before 1989 and the group of patients operated on after 1989.…”

“…UKA has several potential advantages compared with TKA such as reduced morbidity, quicker recovery, the preservation of bone stock, and a more physiological knee function [2][3][4]32]. Midterm and long-term studies suggest reasonable outcome at 10 years with survivorship greater than 95% of UKA performed for medial osteoarthritis or osteonecrosis [2,29], but limited long-term followup data are available for lateral UKA in the literature [5,14,17,30,32]. The authors of one small series of UKA in the lateral compartment reported only one failure out of 19 patients at 89 months of followup [22].…”

“…Each author certifies that his or her institution has approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research. Both the anatomic and biomechanical characteristics are different in each of the knee femorotibial compartments [5,32], and similar surgical treatment may not provide reproducible results when applied to a different compartment [5,32]. Furthermore, UKA in the lateral compartment has been described as technically more challenging and 10 times less performed than medial UKA, thus representing less than 1% of all knee arthroplasty procedures [33].…”

Better Quality of Life After Medial Versus Lateral Unicondylar Knee Arthroplasty

“…A lateral UKA reportedly is performed approximately 10 times less frequently than a medial UKA [35] and therefore there is limited literature regarding the outcome of lateral UKAs. In a recent review [18] of lateral UKAs, nine retrospective studies were identified, of which four involved fewer than 20 patients; 83 patients were analyzed in the largest study [6]. In that study, the cumulative survival rates for a lateral UKA were 83% at 10 years and 74% at 15 years.…”