Influence of Cruciate Retaining, Posterior Stabilized and Bi-Cruciate Stabilized Total Knee Replacement Designs on Gait Mechanics during Ramp and Level Walking

Twenty-five, 5 Bi-cruciate stabilized (BCS), 10 Cruciate Retaining (CR) and 10 Posterior Stabilized (PS), total knee replacement (TKR) patients and 10 healthy controls performed uphill and downhill walking on different slopes using a force platform and an instrumented ramp system. Studies one and study two examined the knee biomechanics and knee joint muscle EMG activity of TKR patients and healthy control during uphill and downhill walking at 0° (level walking), 5°, 10° and 15°, respectively. Study three compared knee biomechanics of patients with three different types of TKR implants to healthy controls during walking up and down on a 10° ramp. Study one found TKR patients had lower peak knee extension moment (KEM) than healthy controls in all uphill walking conditions. The replaced limbs showed lower peak KEM in 10° and 15° uphill walking than non-replaced limbs. The peak loading-response internal knee abduction moment (KAbM) was greater in level walking compared to 10° and 15° uphill walking. Study two showed that replaced limbs of TKR patients had lower peak loading-response and push-off KEM, and quadriceps electromyography (EMG) activity than non-replaced and matched limb of healthy controls in downhill walking. Greater peak KEM, quadriceps EMG activity were found in downhill walking compared to level walking. Study three showed peak KEM was lower in BCS patients than healthy controls and it was lower in replaced limbs than non-replaced limbs during the 10° uphill walking. Peak loading-response KAbMs were similar between the replaced limbs of three TKR groups and healthy controls in both uphill and downhill walking. Moreover, the replaced limbs had lower peak loading-response and push-off KEMs than non-replaced limbs in downhill walking. Additionally, peak loading-response KAbM was greater in non-replaced limbs of BCS and PS patients compared to that in their replaced limb. Uphill walking may have the potential to become a safe exercise for unilateral TKR patients, however, downhill walking may not be appropriate to be included in the early-stage rehabilitation exercise protocols for TKR patients. Future studies should investigate rehabilitation strategies to improve the symmetrical knee loading of BCS and PS patients, therefore postponing or avoiding another TKR surgery.