The Secret to a "Normal" Knee: How Joint Forces Dictate Movement

New data shows intraoperative contact forces predict how a knee will pivot and feel.

Despite excellent long-term survivorship and outcomes after total knee arthroplasty (TKA) , patient satisfaction stubbornly lags behind that of total hip arthroplasty, with approximately 20% of unsatisfied patients. Unsatisfied patients experience pain, functional limitations, and describe an unnatural feel to the knee. To help close the gap on the subset of unsatisfied patients, there is increased interest in knee kinematics before and after TKA related to kinematic pivot patterns, which may help optimize patient-reported outcomes.

Traditionally, it was hypothesized that the optimal kinematic pivot pattern was predominantly medial through the range of motion. However, a modern understanding of kinematic pivot patterns in healthy knees and post-TKA knees may be nuanced with a more accurate description of a dual-pivot kinematic pivot pattern characterized by a lateral pivot in early flexion, which transitions to a medial pivot in mid to late flexion. Recently, this dual-pivot kinematic pivot pattern has shown superior patient-reported outcomes related to satisfaction and patients reporting their knee to always feel normal at 1-year after TKA compared with various other patterns.