Joint Space Width Increases Medially and Decreases Laterally at Different Time points After Medial Open-Wedge High Tibial Osteotomy.

Abstract

PURPOSE\nThis study aimed to evaluate serial changes in the joint space width (JSW) of the medial and lateral compartments after medial open-wedge high tibial osteotomy (MOWHTO) and its associated factors.\n\n\nMETHODS\nMedial and lateral weight-bearing JSWs were measured on serial radiographs and analyzed preoperatively, postoperatively, and at 3 months, 6 months, 1 year, and 2 years. Associations between medial and lateral JSWs and age, body mass index, mechanical axis, correction angle, lateral distal femoral angle, medial proximal tibial angle, joint line convergence angle (JLCA), JLCA on stress radiographs and arthroscopic cartilage status were examined. Clinical outcome was measured according to the Knee Society (KS) objective and functional scores.\n\n\nRESULTS\nSeventy-one patients who underwent MOWHTO with locking plate fixation were analyzed. The respective mean medial and lateral JSWs on serial radiographs were as follows: 3.08 mm and 5.14 mm, preoperatively; 3.10 mm and 4.63 mm, postoperatively; 3.37 mm and 4.57 mm, 3 months; 3.40 mm and 4.59 mm, 6 months; 3.44 mm and 4.57 mm, 1 year; and 3.42 mm and 4.64 mm, 2 years. At 3 months, medial JSWs increased (P < .001), while lateral JSWs decreased immediately (P < .001). JSW showed no significant differences at other timepoints. Preoperative and postoperative JLCA and medial femur and tibia cartilage grades were associated with medial JSW changes (P = .021). However, no significant parameters were associated with decreases in lateral JSWs (P > 0.05). The postoperative KS objective and functional scores improved and were maintained.\n\n\nCONCLUSIONS\nAfter MOWHTO, medial JSWs increased 3 months postoperatively and lateral JSWs decreased immediately. The preoperative and postoperative JLCA and the medial femur and tibia cartilage grades were associated with changes in medial JSWs. However, no significant parameters were associated with decreases in lateral JSWs.\n\n\nLEVEL OF EVIDENCE\nIV, case series of a therapeutic study.