The implications of damage to the lateral femoral condyle on medial unicompartmental knee replacement

Abstract

With medial unicompartmental osteoarthritis (OA) there is occasionally a full-thickness ulcer of the cartilage on the medial side of the lateral femoral condyle. It is not clear whether this should be considered a contraindication to unicompartmental knee replacement (UKR). The aim of this study was to determine why these ulcers occur, and whether they compromise the outcome of UKR. Case studies of knees with medial OA suggest that cartilage lesions on the medial side of the lateral condyle are caused by impingement on the lateral tibial spine as a result of the varus deformity and tibial subluxation. Following UKR the varus and the subluxation are corrected, so that impingement is prevented and the damaged part of the lateral femoral condyle is not transmitting load. An illustrative case report is presented. Out of 769 knees with OA of the medial compartment treated with the Oxford UKR, 59 (7.7%) had partial-thickness cartilage loss and 20 (2.6%) had a full-thickness cartilage deficit on the medial side of the lateral condyle. The mean Oxford Knee Score (OKS) at the last follow-up at a mean of four years was 41.9 (13 to 48) in those with partial-thickness cartilage loss and 41.0 (20 to 48) in those with full-thickness loss. In those with normal or superficially damaged cartilage the mean was 39.5 (5 to 48) and 39.7 (8 to 48), respectively. There were no statistically significant differences between the pre-operative OKS, the final review OKS or of change in the score in the various groups. We conclude that in medial compartment OA, damage to the medial side of the lateral femoral condyle is caused by impingement on the tibial spine and should not be considered a contraindication to an Oxford UKR, even if there is extensive full-thickness ulceration of the cartilage.

Minimally invasive Oxford phase 3 unicompartmental knee replacement

“…The anteror cruciate ligament (ACL) should be functionally intact. The presence of a chondral ulcer on the medial side of the lateral femoral condyle can be ignored, 12 as can the patient's age, weight, level of activity and the presence of chondrocalcinosis, which are not considered to be contraindications. 1,13 Similarly, the state of the patellofemoral joint and anterior knee pain can be ignored, provided that there is not severe lateral patellofemoral OA with bone loss and subluxation.…”

Medium term results of per-operative knee arthroscopy in confirming suitability for unicompartmental arthroplasty

“…The arthroscopy and opening additional implant trays added a mean of 17 min (12)(13)(14)(15)(16)(17)(18)(19)(20) to the operative time. There was no additional tourniquet time since tourniquet was not inflated for the arthroscopy.…”

“…Weight-bearing flexion views do provide additional information over standard weight-bearing views [16]. Bone scans may not be sensitive enough in the setting of early lateral compartment changes [17]. MRI scans give information regarding meniscal pathology but less accurately ACL and chondral pathology [18].…”

Health-Related Quality of Life after Total Knee Replacement or Unicompartmental Knee Arthroplasty in an Urban Asian Population

“…The OKS is a 12-item, patient-assessed questionnaire designed specifically for use in patients undergoing knee replacement surgery [28 -30], and it has also been used in patients undergoing TKR [31][32][33][34] or UKA [35][36][37]. The OKS assessed an individual's pain (e.g., usual level of knee pain, pain in bed at night) and physical disability (e.g., trouble walking down stairs, trouble with transport).…”