Three‐ to six‐year follow‐up results after high‐flexion total knee arthroplasty: can we allow passive deep knee bending?

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Abstract
Purpose: We evaluated 3‐ to 6‐year clinical and radiological follow‐up results after NexGen® LPS‐flex total knee arthroplasty (TKA).Methods: A retrospective evaluation was undertaken of 218 knees in 166 patients (22 males, 144 females) who were followed up for more than 3 years after TKA. Evaluations included preoperative and postoperative range of motion (ROM) measurement, Knee Society (KS) Score, tibiofemoral angle and assessment of postoperative complications.Results: TKA resulted in a significant ROM increase from a mean flexion contracture of 9° (range 0°–20°) and further flexion of 117° (range 80°–155°) to a mean flexion contracture of 2° (range 0°–10°) and a further flexion of 131° (range 95°–155°). KS knee and function scores significantly improved from 52 and 38 before surgery to 87 and 82 after surgery, respectively. The tibiofemoral angle significantly improved from varus 5.7° to valgus 5.4°. Progressive radiolucent lines around the femoral component on radiographs were observed in 30 knees (13.8%, 27 patients), and more of those knees, could squat than non‐radiolucent knees (76.7 vs. 20.2%; P < 0.05). Seven knees (3.2%, 6 patients) were revised at a mean 49 months after the index operation.Conclusions: While NexGen® LPS‐flex TKA satisfactorily improved ROM, it was associated with a relatively high incidence of early loosening of the femoral components. This might be associated with passive‐maximal flexion activity, such as squatting or kneeling. The clinical relevance of this study is that squatting or kneeling, common activity in Asian, may not be allowed after NexGen® LPS‐flex TKA.

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