To compare the clinical efficacy between modified open wedge high tibial osteotomy (MOWHTO) versus traditional open wedge high tibial osteotomy (TOWHTO) for varus knee osteoarthritis (KOA).

A retrospective study was conducted to analyze the 50 patients (60 knees) with varus KOA who had received high tibial osteotomy at Department of Sports Medicine, The Affiliated Hospital of Qingdao University between September 2019 and December 2020. The patients were divided into 2 groups according to different ways of osteotomy: a traditional group and a modified group. In the traditional group subjected to TOWHTO, there were 25 cases (30 knees); in the modified group subjected to MOWHTO, there were 25 cases (30 knees). In MOWHTO, the bone block attached to the medial collateral ligament (MCL) of the knee was first chiseled at the MCL insertion before osteotomy to reduce excessive stripping of the MCL in the osteotomy area, and then the bone fragment attached to the MCL was filled into the osteotomy area to increase bone filling and bone coverage after the alignment of the lower limb was corrected. The hip-knee-ankle angle (HKAA), medioproximal tibial angle (MPTA), and joint line convergence angle (JLCA) were measured preoperatively and at 18 months postoperatively in both groups to evaluate correction of the alignment of the lower limb. Fracture healing time, bone loss in the osteotomy area, Hospital for Special Surgery (HSS) knee score and visual analogue scale (VAS) were recorded to evaluate the postoperative efficacy.

There was no statistically significant difference between the TOWHTO and MOWHTO groups in the general clinical data before operation, showing comparability (P>0.05). At 18 months after operation, HKAA was (179.1° ± 1.1°) in the TOWHTO group and (179.3° ± 0.7°) in the MOWHTO group while MPTA was (91.9° ± 0.4°) in the TOWHTO group and (91.9° ± 0.4°) in the MOWHTO group, showing no statistically significant difference between the 2 groups (P>0.05) but a significant difference between preoperation and postoperation in each group (P<0.05). At 18 months after operation, JLCA was (1.8° ± 0.4°) in the TOWHTO group, significantly larger than that in the MOWHTO group (1.5° ± 0.4°), HSS score was 81.5 (79.5, 83.0) points in the TOWHTO group, significantly lower than that in the MOWHTO group [85.0 (82.5, 87.5) points], and VAS was 1.8 (1.6, 2.0) points in the TOWHTO group, significantly higher than that in the MOWHTO group [1.5 (1.5, 2.0) points] (all P<0.05). At 18 months after operation, the preoperative JLCA was significantly improved in both groups (P<0.05). The time required for a fracture healing score higher than 4 points was (3.3 ± 0.6) months in the TOWHTO group and (4.5 ± 0.9) months in the MOWHTO group, and the rate of bone loss in the osteotomy area was 20% in the TOWHTO group (6/30) and 0 (0/30) in the MOWHTO group, both showing a significant difference between the 2 groups (P<0.05).

Both TOWHTO and MOWHTO can effectively treat varus KOA. MOWHTO is more effective in promoting bone healing in the osteotomy area, reducing bone defects in the osteotomy area and improving knee function.

Osteoarthritis, knee; Osteotomy; Medial collateral ligament, knee; Fracture healing