When performing lateral closing wedge high tibial osteotomy (LCWHTO), fibular untethering can be performed with either fibular shaft osteotomy (FSO) or proximal tibiofibular division (TFD). The aim of this study was to compare the degree of varus instability between the two methods after LCWHTO and to analyze the determinants of varus instability.
This study retrospectively analyzed 108 consecutive patients with medial compartment osteoarthritis who underwent LCWHTO and had >2 years of follow-up. Patients who underwent unilateral LCWHTO without a previous history of ligament injury were included. Forty-five patients who received LCWHTO with TFD and 51 patients who received LCWHTO with FSO were finally analyzed. The mean follow-up duration was 5.3 years in LCWHTO with TFD and 4.1 years in LCWHTO with FSO. The shortest distance between the lateral tibial plateaus and the corresponding most distal subchondral bone surface of the lateral femoral condyle was measured on varus stress radiographs and compared with that on the unaffected contralateral knee. Multivariable logistic regression analyses were conducted to identify predictors of varus instability.
Lateral joint space width showed no significant between-group difference. Multivariable logistic regression analysis revealed that the pre-operative hip-knee-ankle angle was positively correlated with the lateral joint space width. The type of fibular untethering procedure was not associated with postoperative varus instability.
Level III, Retrospective comparative study.
The degree of pre-operative varus malalignment is associated with postoperative varus instability after LCWHTO. Proximal tibiofibular division is not a variable for postoperative varus instability after LCWHTO.