RADIOGRAPHIC EVALUATION OF OPEN MEDIAL TIBIAL OSTEOTOMY FIXED WITH A PUDDU PLATE

Abstract

Purpose: The purpose of this work was to evaluate radiographically architectural changes in the knee caused by open medial tibial osteotomy fixed with a Puddu plate.

Material and methods: Forty-three patients (45 knees) operated on between 1999 and 2002 were reviewed retrospectively. Osteotomy was performed for femorotibial osteoarthritis of the medial compartment in 39 knees, laxity in three and both in three. There were 16 women and 27 men, mean age 55 years (22–73). Standard x-rays of the knee (AP, lateral 30° flexion) and telemetric films obtained preoperatively and at bone healing were analysed by two independent observers (a junior and a senior). We noted: mechanical axis (HKA), presence of epiphyseal varus and its correction, patellar height (Caton-Deschamps index), and tibial slope. The alpha risk was set at 5% for statistical analysis.

Results: Complications included two cases of non-union which required revision. Measures were reproducible between the two observers (p> 0.5). Mean HKA at bone healing was 183.53±2.28° for an expected correction of 184.14±0.93 (p=0.0112). Osteotomy achieved correction of constitutional varus in 25/36 knees (p=0.014). In the nine knees without constitutional varus, an oblique tibiotalar space was observed in five. Preoperative patella was 0.86±0.13 versus 0.69±0.16 postoperatively (p=0.021). The position of the plate on the medial aspect of the metaphysic was posterior in 28 knees and middle in 17 but with no impact on tibial slope related to plate position (p=0.175).

Discussion: Open medial tibial osteotomy with Puddu plate fixation enabled us to achieve the desired correction which persisted to bone healing and to correct constitutional varus when present, an important element for ligament balance in the event a secondary total knee arthroplasty would become necessary. In our series, we did not find any changes in the posterior slope related to the position of the plate as has been reported by others. Conversely, we did observe a decrease in patellar height.