Constrained liners in revision: total hip arthroplasty an overuse syndrome: in opposition.

Use of constrained liners in revision total hip arthroplasty is frequently a necessary evil. Concomitant with the increasing complexity of the operative intervention is the deterioration of periarticular soft-tissue envelope integrity, causing increased risk of dislocation. Risk factors can be categorized as impingement independent or impingement related. Impingement-independent risk factors include those related to compromised soft-tissue tension, patient-specific issues, and surgical approach. Impingement-related risk factors include head-to-neck size and geometry, acetabular liner geometry, and surgical technique. Indications for constraint include recurrent hip instability after arthroplasty, intraoperative multidirectional hip instability, neuromuscular diseases that impair hip dynamics, neurologic diseases that impair the patient's ability to restrict activities, and proximal muscle weakness with or without deficiency of the protective muscular. Newer designs featuring large heads, improved range of motion, and reduced impingement hold the promise of improved results.