Radiological analysis of closed-wedge high tibial osteotomy.

Objective: In this study, we aimed to evaluate changes in frontal plane (anatomical axis) and sagittal plane (tibial slope, patellar height) parameters following closed-wedge high tibial osteotomy (HTO) and possible correlations between them.

Methods: Between June 2003 and May 2007, 15 knees of the 13 female patients (mean age 52.6 years; range 45 to 64 years) who were followed on a regular basis in our outpatient clinic and underwent closed-wedge HTO were included. The mean follow-up was 49 months (range 29-75 months). Radiologic analysis was performed using pre- and postoperative anatomical axis, tibial slope, and patellar height measurements [Caton index (CI) and Insall-Salvati index (ISI)]. The findings were analyzed by using Wilcoxon matched pairs test and Pearson's correlation test.

Results: Preoperative varus deformity was 6.3° ± 2.7°, while it was measured as 7.2° ± 2.5° valgus in the last visit (p=0.0004). The pre- and postoperative CI were 0.97 ± 0.1 and 0.96 ± 0.1, respectively (p=0.85). The ISI decreased from 1.23 ± 0.15 to 1.14 ± 0.15 (p=0.012). Patella baja was observed in only one patient (ISI=0.77). Preoperatively tibial slope was 6.5° ± 2.4°, while it was measured as 0.06° ± 3.4° in the last visit (p=0.0001). There was no correlation between frontal plane angle change and tibial slope, also between patellar height and tibial slope.

Conclusions: Closed-wedge HTO does not result in significant changes in patellar height. The risk of patella baja can be decreased through minimal dissection around patellar tendon. However, closed-wedge HTO reduces tibial slope significantly. Optimal resection from posterior tibia is necessary to prevent this condition. A possible loss of tibial slope should be considered in the further reconstructive procedures.