Relationship between range of motion and femoral rollback in total knee arthroplasty

Objective: The aim of this study was to evaluate the relation between femoral rollback and range ofmotion (ROM) in patients with cruciate retaining (CR) and posterior stabilized (PS) total knee arthroplasty (TKA). Methods: The study included 38 knees of 31 patients (26 female and 5 male) with primary knee arthrosis who underwent TKA. The posterior cruciate ligament (PCL) was sacrificed in 24 knees in the PS group and preserved in 14 in the CR group. Mean follow-up was 30.6 months. Patients were submitted to fluoroscopic lateral evaluation for ROM and femoral rollback assessment.Results: Average ROM of the CR group was 106.43±9° and 105.43±11.7° for the PS group (p=0.78).Average femoral rollback was 10.5±9.7 mm and was significantly lower in the CR group (5.8±6.5mm) than the PS group (13.2±10.5 mm) (p=0.026615). While there was no correlation between thefemoral rollback and ROM for CR prostheses (p=0.78 and r=0.8), there was a significant correlation for PR prostheses (p=0.01 and r=0.49) with regression pointing to an increase of 0.545 degrees ROM for each unit of femoral rollback. Conclusion: Despite increase in femoral rollback and its relation with ROM in PS TKA, there were no differences in ROM between CR and PS TKA.