Closed reduction of constrained total hip arthroplasty.

Many surgeons use acetabular components with constrained polyethylene liners to improve stability in patients with a history of hip dislocation. Considering that the reported incidence of hip dislocation in patients with constrained components is 4% to 29%, it generally is recognized that open reduction would likely be necessary in cases of redislocation. Recent reports have indicated that closed reduction of constrained total hip arthroplasty is possible in some cases. However, it is unknown whether closed reduction damages the constrained polyethylene liner and predisposes patients to additional dislocations. The current study evaluated the integrity of the polyethylene constraint mechanism after in vitro simulation of hip dislocation and closed reduction. After lever-out dislocation and reduction, 76% of the capture mechanism strength was maintained without additionally damaging the polyethylene liner. Also reported is the technique for closed reduction in patients with constrained components and a clinical series of six patients who had successful closed reduction. These patients remain stable without any additional dislocations 7 to 72 months after reduction. These data suggest that closed reduction of Poly-Dial constrained polyethylene liners can be successful without predisposing patients to additional dislocations.