Changes in patellar baja progress until 3 months after medial open-wedge high tibial osteotomy.

Purpose: The purpose of this study was to evaluate sequential patellar height changes as well as the factors leading to these changes after medial open-wedge high tibial osteotomy (MOWHTO).

Methods: The study cohort constituted 37 knees from 36 patients who underwent MOWHTO for varus knee. The Caton-Deschamps index (CDI) for patellar height was measured preoperatively and at 2 weeks and 3, 6, and 12 months postoperatively. The factors related to sequential changes in patellar height were evaluated.

Results: Significant differences were observed between preoperative CDI and postoperative CDI at all time points ( < .05). Two-week postoperative CDI and postoperative CDI at 3,6,12-months was also significantly different ( < .05). The only significant factor for the change in patellar height between preoperative CDI and postoperative CDI at 2-weeks and 12-months was the change in the Δ medial proximal tibial angle (ΔMPTA) (postoperative MPTA-preoperative MPTA). We could not identify the factor that affected the change in patellar height change from 2-weeks postoperatively.

Conclusion: The change in patellar height continued sequentially until at least 3 months postoperatively. ΔMPTA was associated with the change in patellar height at 2 weeks postoperatively compared with preoperatively; however, no factors associated with the change in patellar height from 2 weeks postoperatively to 3, 6, and 12-months postoperatively were identified.