Men versus women: does size matter in total knee arthroplasty?

UNLABELLED: The role played by femoral component sizing in the clinical outcome of primary TKA is currently debated. Oversizing the femur in patients with smaller knees could lead to overstuffing the knee capsule with resulting pain and reduced range of motion. We asked whether the distribution of femoral component sizes differed between genders and whether the availability of additional sizes benefited genders differently and led to a measurable improvement in knee flexion and Knee Society scores or pain. We retrospectively examined two groups of consecutive knees of patients who underwent primary TKA using similar techniques and constraint: Group 1 (93 men and 90 women) who had available four original sizes and Group 2 (106 men and 106 women) after the introduction of three new smaller sizes. More than twice as many new smaller sizes were used in women (52.3%, 56 of 106) compared to men (17.9%, 19 of 106). At the scheduled 6-month followup visit (average, 6 months; range, 5-7 months), we found no differences in the knee score, pain score, and knee flexion in men and women before the additional sizes (Group 1) and after the new sizes (Group 2). Additional sizes therefore did not appear to influence short-term outcomes. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.