WITHDRAWN: Limited value of MRI in the preoperative assessment of lateral-compartment cartilage in potential candidates for medial unicompartmental knee arthroplasty

Abstract

Abstract Background Intact lateral-compartment cartilage is a requirement for the long-term success of medial unicompartmental knee arthroplasty (UKA). The value of MRI to rule out lateral-compartment cartilage lesions (OARSI ≥ grade 2) in potential candidates for medial UKA was prospectively evaluated. Methods One-hundred consecutive knees undergoing total knee arthroplasty for varus osteoarthritis (OA) were included. Knees with lateral-compartment OA (Kellgren-Lawrence > grade 2) were excluded, leaving 84 knees for final assessment. On MRI, lateral-compartment cartilage was assessed using a validated score. In corresponding locations, cartilage was histologically assessed using the OARSI system. Results The prevalence of histologically intact (OARSI grade 0/1) cartilage was: distal lateral femur: 71/84 (85%); lateral tibia plateau: 22/84 (26%). The sensitivity of MRI to rule out advanced cartilage lesions (OARSI ≥ grade 2) was 77% (17/22) for the lateral tibia plateau. The precision of MRI to correctly identify intact cartilage (OARSI grade 0/1) on the lateral tibia plateau was 38% (17/45). For the distal lateral femur, MRI was able to rule out OARSI ≥ grade 2 cartilage lesions in 85% (60/71) with high precision (60/62 (97%)). Conclusion MRI does not have a high accuracy of ruling out patients with more advanced (ORASI ≥ grade 2) cartilage damage on the lateral tibia plateau. MRI can reliably rule out advanced histologic cartilage lesions on the distal lateral femur, however, advanced cartilage lesions are rare in varus OA of the knee. The current study does not support the routine use of MRI to rule out lateral-compartment cartilage damage.