Medial opening wedge high tibial osteotomy (HTO) for the treatment of varus gonarthrosis can be associated with inadvertent decreases in patellar height.
Decreases in patellar height observed after medial opening wedge HTO can be minimized with the addition of a tibial tubercle osteotomy (TTO).
Cohort study; Level of evidence, 3.
Twenty-nine patients undergoing medial opening wedge HTO with a concurrent TTO were matched with 29 controls who previously underwent medial opening wedge HTO without a TTO. Both groups had substantial varus malalignment (mean mechanical axis angle, -10° ± 3°) requiring large corrections. Measurements of patellar height and posterior tibial slope were calculated from standing lateral radiographs and compared preoperatively and 6 months postoperatively. Patellar height measures included the Blackburne-Peel index, Caton-Deschamps index, Miura-Kawamura index, Insall-Salvati ratio, and modified Insall-Salvati ratio.
The changes in the Blackburne-Peel, Caton-Deschamps, and Miura-Kawamura indices were significantly less in the HTO/TTO group versus the HTO group. There were 3 of 29 (10%) new cases that met the radiographic criteria for patella infera in the HTO/TTO group versus 11 of 29 (38%) new cases of patella infera found postoperatively in the HTO group, suggesting an absolute risk reduction of 28% with TTO. The changes in the Blackburne-Peel and Caton-Deschamps indices were correlated to a larger preoperative varus deformity in the coronal plane (r = 0.52 and r = 0.41, respectively).
The addition of a TTO when performing a medial opening wedge HTO minimizes the decreases in patellar height associated with the procedure.