Why is the posterolateral approach in hip surgery associated with higher dislocation risk, and how can risk be mitigated?

• A. It disrupts the posterior capsule and short external rotators; mitigated by capsule repair, abductor strengthening, and consideration of alternate approaches or constrained liners in high-risk patients
• B. It preserves the posterior capsule; no mitigation needed
• C. It increases dislocation risk but cannot be mitigated
• D. It reduces bone stock; treat with bone grafting

Answer: (A)

Dislocation risk with the posterolateral hip approach is higher because this approach disrupts the posterior stabilizers of the joint—the posterior capsule and the short external rotator muscles. When these structures are released, the hip loses its primary posterior restraint, making dislocation more likely in positions common after arthroplasty, especially flexion with adduction and internal rotation.

Mitigation centers on restoring and preserving posterior stability and overall soft-tissue balance. Repairing the posterior capsule and short external rotators during closure helps re-create the posterior stabilizing sleeve. Strengthening and rehabilitating the abductor mechanism improves lateral stability and reduces edge-packing forces that can contribute to dislocation. For patients with higher instability risk, considering alternative approaches that spare the posterior structures (such as anterolateral or direct anterior) can be helpful. In some high-risk cases, using additional stability strategies—like constrained liners or dual-mobility cups—can provide extra protection against dislocation, alongside meticulous component positioning to avoid malalignment.