Posterior Hip Dislocation Complication – DNB CET HYT
The inherent stability of the hip joint is provided by its ligamentous, bony, and muscular architecture, as well as the labrum. Its main blood supply is via the medial femoral circumflex artery, with other contributions from the lateral femoral circum- flex artery, artery of the ligamentum teres (obturator), and the inferior and superior gluteal arteries. The sciatic nerve lies close to the hip joint, exiting anterior to the piriformis in the greater sciatic notch.
Posterior acetabular wall fractures with >40% wall disruption lead to an unstable hip, whereas it remains stable when <20% of the wall is disrupted. An irreducible hip dislocation, which is caused by bony or soft-tissue interposition within the joint, requires emergent open surgical intervention to reduce the pressure on the hip’s artic- ular cartilage and subsequent risk for avascular necrosis. A nonconcentric reduction may also require open operative intervention or skeletal traction for the same reasons seen with irreducible hips.
A hip dislocation is an orthopaedic emergency, and closed reduction attempts must be performed as soon as possible to reduce the period of avascularity to the hip. It must be reiterated, however, that adequate imaging be obtained before any reduc- tion attempts to rule out an ipsilateral femoral neck fracture. Reduction can be per- formed in the ED if conscious sedation and muscle relaxation can be achieved. If adequate sedation and relaxation is unattainable in the ED, the hip must be reduced in the operating room under general anesthesia.
The risk of developing posttraumatic osteonecrosis of the femoral head is what makes hip dislocations an orthopaedic emergency. The critical time to reduction, which in theory will restore blood flow to the femoral head, has not been defini- tively determined. However, it is thought that a greatly increased risk of avascular necrosis occurs with a delay in reduction of greater than 6 to 12 hours. It is impor- tant to note that those who incur hip dislocations via higher energy mechanisms are more likely to develop osteonecrosis as a result of greater initial damage to the surrounding blood supply. Osteonecrosis commonly occurs within 2 years.
Other complications include development of posttraumatic arthritis, sciatic nerve palsy, and recurring dislocations. Furthermore, many patients presenting with hip disloca- tions have other significant systemic injuries as well as ipsilateral knee and bony injuries.