Combined tibial tubercle osteotomy with medial opening wedge high tibial osteotomy minimizes changes in patellar height: a prospective cohort study with historical controls.

BACKGROUND: Medial opening wedge high tibial osteotomy (HTO) for the treatment of varus gonarthrosis can be associated with inadvertent decreases in patellar height.

HYPOTHESIS: Decreases in patellar height observed after medial opening wedge HTO can be minimized with the addition of a tibial tubercle osteotomy (TTO).

STUDY DESIGN: Cohort study; Level of evidence, 3.

METHODS: 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.

RESULTS: 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).

CONCLUSION: The addition of a TTO when performing a medial opening wedge HTO minimizes the decreases in patellar height associated with the procedure.