Genu recurvatum in total knee replacement.

Genu recurvatum deformities are unusual before total knee arthroplasty (TKA), occurring in less than 1% of patients. Because of its rarity, concern may exist regarding the recurrence of the deformity and the potential for instability after TKA. Recurvatum may be associated with a severe osseous deformity, including genu valgum, capsular or ligamentous laxity, and, rarely, neuromuscular disease. In the presence of the latter, a plantarflexion contracture of the ankle also may be present. Therefore, specific attention should be given preoperatively to evaluation of the quadriceps, hamstrings, and gastrocnemius complex. Because genu recurvatum is known to recur in patients with certain neuromuscular disorders, the etiology of the hyperextension deformity must be elucidated thoroughly before surgery. In the absence of neuromuscular disease, however, hyperextension deformities tend not to recur after TKA. Care should be taken to avoid even mild degrees of residual instability in the coronal plane at surgery because this is associated with increased extension in the postoperative period.