The evaluation of two methods for the placement of the tibial component of total knee arthroplasties in obese patients

Between December 2004 and October 2008 we studied 38 obese patients who underwent cemented total knee arthroplasty (using the rotating platform tibial tray) due to medial compartment osteoarthritis and consequent varus deformity. All patients had a body mass index (BMI)> 40. Functional outcome was assessed using the Knee Society Score (KSS). The study was based on the comparison between extramedullary (group A) and intramedullary (group B) instrumentation systems for the placement of the tibial prosthesis. The main endpoint was the immediate post-operative knee joint alignment.

There were 10 male and 28 female patients. The average follow-up period was 13.8 months (minimum follow-up of 6 months). There were 22 patients in group A whereas 16 patients comprised group B. In 5 of the 22 patients in group A there was an average varus malalignment of 40 and a mean KSS of 71.5 at the time of the latest follow-up visit. In the rest of patients of both groups there was a valgus alignment between 0 and 70 and a mean KSS of 86.4 respectively

Our experience suggests that the intramedullary instrumentation technique for the placement of the tibial component offers a more favourable post-operative alignment as well as better functional outcome in obese patients.