To study the complications and clinical outcomes of overcorrection of varus deformity by open wedge high tibial osteotomy (OWHTO), and to compare the compensatory changes of hip joint, patellofemoral joint and ankle joint by radiological indexes.

The data of 63 patients who underwent OWHTO in the Affiliated Hospital of Qingdao University from January 2016 to May 2020 were retrospectively analyzed. Inclusion criteria: definite diagnosis, symptomatic knee osteoarthritis with varus deformity. Exclusion criteria: patients with bilateral surgeries, knee infection, and previous history of trauma. According to the postoperative measured weight-bearing line ratio (WBLR), all the patients were divided into the normal correction group (n=52) (50%<WBLR<67%) and the overcorrection group (n=11) (WBLR≥67%). The hip knee-ankle angle (HKA), medial tibial angle (MPTA), lateral distal femoral angle (LDFA), joint line convergence angle (JLCA) and posterior tibial slope angle (PTS) were measured to evaluate the efficacy of postoperative lower limb alignment correction. The hip abduction angle (HAA), tibial slope angle (TPI), distant inclination angle (TIA), Caton-Deschamps index, lateral patellar inclination angle (LPT), patellar lateral migration distance (LPS), medial patellofemoral joint space and lateral patellar space were measured to evaluate the compensatory changes of adjacent joints after operation. The Hospital for Special Surgery (HSS) score, Western Ontario and McMaster Universities arthritis index (WOMAC) of the affected knee were followed up. The measurement data were analyzed by t test. The incidence of complications in the two groups was followed up and compared by chi square test.

The postoperative complications occurred in four cases (36.4%) in the overcorrection group; postoperative complications occurred in four cases (11.5%) in the normal correction group; the difference was statistically significant between the two groups (χ²=4.395, P=0.036). After OWHTO, the differences in HKA and MPTA between the two groups were statistically significant (t=6.586, 3.709, both P < 0.001), and the differences in HAA between the two groups had statistical significance (t=-2.309, P=0.026). There was no statistically significant difference in other imaging parameters (all P>0.05). There was no statistically significant difference in HSS score or WOMAC score between the two groups(all P>0.05).

Overcorrection of varus deformity (postoperative WBLR≥ 67%) does not affect clinical outcomes within two years after OWHTO, but may increase the incidence of postoperative complications and radiologically increase compensatory hip adductions.