Is there a difference in bony stability at three months postoperatively between opening-wedge high tibial osteotomy...

To compare the initial postoperative stability of opening-wedge high tibial osteotomy (HTO) and opening-wedge distal tuberosity osteotomy (DTO) and investigate the factors that influence initial stability.

Patients with the same operative indications who underwent HTO (n = 51) and DTO (n = 55) were included. Demographic and preoperative radiographic data (weight-bearing line percentage [%WBL], femoral-tibial angle [FTA], medial proximal tibial angle [MPTA], posterior tibial slope and correction angle), and postoperative computed tomography (CT) scan data (initial postoperative stability [12 weeks postoperative], and hinge fracture [1 and 12 weeks postoperatively], and hinge length, flange thickness, flange length, axial flange osteotomy angle, sagittal flange osteotomy angle [1 week postoperatively]) were statistically analyzed. As a subgroup analysis, HTO and DTO patients were divided into Stable and Unstable groups respectively based on postoperative CT at 12 weeks; demographic and radiological data were compared.

Patients with DTO was significantly younger (median [range]; 59 [22, 73] vs 64 [45, 75], P = 0.02) and had a smaller preoperative deformity (%WBL: median [range]; 28.9 [12.8, 46.0] vs 24.3 [4.9, 44.3], P < 0.01, FTA: median [range]; 179.0 [173.0, 183.0] vs 180.0 [172.5, 186.2], P < 0.01, MPTA: median [range]; 84.0 [79.0, 87.1] vs 83.0 [78.2, 86.5], P = 0.04) and smaller correction angles (median [range]; 9 [6, 12] vs 10 [7, 15], P < 0.01). Postoperative CT data showed that DTO was associated with significantly more unstable cases (stable/unstable: 31/24 vs. 39/12, P = 0.02) and hinge fractures (none/1/2/3: 24/25/3/3 vs. 36/12/1/2, P < 0.01) and shorter hinge (median [range]; 27.8 [14.7, 43.4] vs 32.6 [22.5, 44.0], P < 0.01) than HTO. The Unstable DTO group had significantly shorter hinges (median [range]; 23.2 [14.7, 33.9] vs 31.1 [15.2, 43.4], P < 0.01) and thicker flanges (median [range]: 15.2 [9.0, 24.8] vs. 11.0 [6.8, 13.8], P < 0.01) than the stable group. The other data were not significantly different between the two groups.

DTO resulted in less initial postoperative stability than HTO. The risk factors for initial instability in DTO were a short hinge and thick flange.