Results of prospective, randomized clinical trials comparing standard and high-flexion posterior-stabilized TKA: a focused review

High-flexion total knee arthroplasty (TKA) designs have been available for several years for patients desiring a greater postoperative flexion. We conducted a focused review on published results of prospective, randomized clinical trials that compared a standard posterior-stabilized TKA with a high-flexion posterior-stabilized TKA design. Follow-up ranged from 1 to 2.7 years. None of the articles included in the review showed a statistical difference between the standard and high-flexion designs in clinical flexion or range of motion. Mean postoperative flexion ranged from 106° to 130° for the standard design and 110° to 128° for the high-flexion design. Based on currently available literature, high-flexion cruciate-substituting TKAs do not appear to provide increased flexion in the short term. The downsides of these designs, such as increased cost, increased bone resection, and early femoral loosening, need to be weighed against the potential long-term improvement in polyethylene wear due to increased conformity in high flexion. Continued follow-up to document these findings will be important.