Disclosures: Amelia Y. Ni, BA, DO: No financial relationships or conflicts of interest

Case Diagnosis: Femoral head avascular necrosis with atypical pain referral pattern to the ipsilateral shin

Case Description or Program Description: The patient presented as a referral from Orthopedic Surgery for evaluation of shin pain. She had a known history of avascular necrosis (AVN) with severe collapse of the femoral head secondary to severe osteoarthritis. The pain on presentation was severe, sharp, and aching in quality, exacerbated by activity, and without alleviating factors. Previous treatments, including anti-inflammatories and narcotics, provided slight benefit. On physical exam the patient had 3/5 strength with hip flexion. She had severe pain with palpation diffusely over the distal femur, knee, and tibial plateau without nidus or radiation. Testing with logroll, FADIR, hip scour, and Patrick’s all reproduced the pain with limited motion. Hip distraction improved the pain. Range of motion and all knee special tests did not replicate the pain. X-rays demonstrated hip osteoarthritis with femoral head subluxation and flattening, with only minimal knee arthritis. A diagnostic and possibly therapeutic intra-articular hip injection was planned to evaluate for an atypical pain pattern referring from femoral head AVN.

Setting: Top 20 US academic hospital, Level 1 Trauma center

Assessment/Results: The patient underwent a fluoroscopically guided, intra-articular hip joint injection with Lidocaine, Ropivacaine, and Triamcinolone. At follow-up, the patient reported that during the immediate and sub-acute anesthetic phase she experienced essentially complete pain resolution. Unfortunately, the pain returned within the next week. Plans for hip replacement to address the referred pain are underway.

Discussion (relevance): This is a case of atypical pain referral from the femoral head distal to the knee and tibial plateau, where an intra-articular hip injection was both diagnostic and therapeutic, providing guidance for future surgical plans.

Conclusions: Atypical pain referral patterns must be on the differential for patients who present with AVN of the femoral head, with low risk, cost-effective intra-articular injections available to guide pain management.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/avascular-necrosis-of-the-femoral-head-referring-pain-to-the-anterior-tibia-a-case-report/