Modern understanding of native knee kinematics reveals more complex pattern of lateral-pivot in early flexion activities, and medial-pivot in deeper flexion (i.e. dual-pivot). The purpose of this study was to compare patient outcomes with a contemporary dual-pivot TKA, designed to replicate anterior-cruciate substitution and stability, with a traditional TKA.
One hundred and eighty-three dual-pivot TKAs were matched with 183 traditional non-conforming TKAs. All TKAs were cemented and performed with identical perioperative protocols. Patients were matched on age, sex, BMI, and ASA score. Patient-reported outcome measures were prospectively obtained and compared at minimum one-year follow-up.
Study cohorts were identical with 72% female, average age of 68 years, and BMI of 33 kg/m2. There were no differences in prevalence of fibromyalgia, depression, preoperative narcotic use, or femoral component alignment (p ≥ 0.105). Dual-pivot TKA patients had a greater prevalence of lumbar spine disease (p = 0.012) and more reported their knee never feels normal preoperatively (p = 0.012). Dual-pivot TKA patients reported less walking pain at latest follow-up (p = 0.022). Trends for greater level of participation in very active activities or impact sports (p = 0.067) and more reporting their knee feels normal (p = 0.091) were observed in dual-pivot TKAs.
Patients with dual-pivot knees reported less walking pain despite greater lumbar spine disease, supporting the potential benefit of lateral-pivot motion in early flexion activities. However, the groups were similar in overall satisfaction suggesting the nuances and potential ceiling-effect of patient satisfaction warrants further study.