MCQs – Hip Recon 5

Modern Study Review (AI-Generated)

High-Yield Summary

Hip dislocations are a staple of the Royal College exam, focusing heavily on reduction techniques, complications, and prognostic factors. The single most important clinical threshold is the time elapsed before reduction, as this strongly influences avascular necrosis (AVN) risk and long-term outcomes. The examiner often forces a choice between urgent reduction versus careful imaging when managing dislocations. While classic teaching emphasizes specific reduction maneuvers (90° flexion, adduction, internal rotation for posterior dislocations), modern practice increasingly incorporates advanced imaging and multidisciplinary care to optimize timing and minimize complications.

High-Yield Decision Matrix

Active Recall Q&A

Complications

Q: What are the likely complications after a posterior dislocation of the hip?
A: Degenerative arthritis, avascular necrosis (AVN), and sciatic nerve palsy are likely complications; redislocation is rare if there is no large posterior wall fracture.
Related Pearl: Sciatic nerve palsy occurs due to the nerve’s proximity to the posterior capsule; early recognition and monitoring are critical to prevent permanent neurological deficits.

Reduction Technique

Q: What is the optimal position to reduce a posteriorly dislocated hip?
A: The best position is 90° of hip flexion, with some adduction and internal rotation.
Related Pearl: This position relaxes the posterior capsule and surrounding muscles, facilitating a safer and more effective closed reduction.

AVN Risk

Q: How is the rate of AVN after hip dislocation related to clinical factors?
A: AVN rate correlates with the duration the hip remains dislocated and the number of unsuccessful reduction attempts, rather than the presence of acetabular fracture.
Related Pearl: Prolonged ischemia from dislocation causes femoral head necrosis; reducing the hip within 6 hours significantly lowers AVN risk.

Vascular and Neurological Compression

Q: What vascular and neurological structures can be compressed in a superior anterior hip dislocation?
A: The femoral artery and femoral nerve can be compressed.
Related Pearl: Superior anterior dislocations have a lower risk of osteoarthritis compared to posterior dislocations due to different injury mechanics and less cartilage damage.

Postoperative Management

Q: What is the recommended postoperative action for patients with internal fixation of the hip?
A: Prompt hip aspiration is recommended if there are signs of complications such as infection or hemarthrosis.
Related Pearl: Early joint aspiration aids in diagnosing infection or hematoma, enabling timely intervention and improved patient outcomes.

Prognosis

Q: What is the most significant prognostic factor in hip dislocation outcomes?
A: The length of time elapsed until reduction.
Related Pearl: Early reduction, ideally within 6 hours, is associated with significantly better functional outcomes and lower rates of AVN.

Classic Clinical Notes

• After posterior dislocation of the hip, degenerative arthritis, AVN, and sciatic nerve palsy are likely complications; redislocation is rare if there is no huge posterior wall fracture.

• The best position to reduce a posteriorly dislocated hip is in 90° of flexion, some adduction and internal rotation.

• The AVN rate post-dislocation is related to the amount of time out of joint and to repeated unsuccessful attempts at reduction. It probably does not have much to do with fracture of the acetabulum.

• A superior anterior dislocation can compress the femoral artery and nerve. It probably leads to OA less than the posterior dislocations.

• Be fast to aspirate the hips of any postop patient with internal fixation.

• The most significant factor in the prognosis of hip dislocation is the length of time elapsed until reduction.

Last Updated on January 25, 2026 by Christian Veillette