Total knee arthroplasty in severe valgus knee deformity: comparison of a standard medial parapatellar approach combined with tibial tubercle osteotomy

Abstract

Primary TKA in valgus knees with a deformity of more than ten degrees may prove challenging, since bone and soft tissue abnormalities make accurate axis restoration, component orientation and joint stability attainment a difficult task. The purpose of this study was to determine which approach is optimal in these patients, by comparing the standard medial parapatellar approach to a lateral parapatellar combined with a tibial tubercle osteotomy (TTO). Forty-four valgus knees--with an axis deviation ranging from 15 to 36 degrees (mean 24°)--were dealt with primary TKA and followed up for a minimum period of 7 years. Lateral parapatellar arthrotomy combined with TTO was performed in 22 individuals (Group A) and a standard medial parapatellar capsulotomy in the remaining patients (Group B). The International Knee Society System Score (IKSS) was used for clinical evaluation. Radiological assessment was performed yearly postoperatively using long films for assessment of the anatomical axis. The postoperative IKSS scores showed no significant statistical difference between groups A and B (P < 0.05). In the alignment parameter, however, residual valgus deviation occurred in 9% of patients from Group A and in 32% from Group B. No late-onset instability was displayed. Lateral parapatellar approach combined with TTO may prove highly beneficial in significant valgus deformities, as the anatomical axis is restored accurately and soft tissue release of the lateral contracted structures facilitated to an important extent.