Poster 234 Ultrasound Diagnosis of Quadriceps Tendon Tear and Patella Fracture in a Patient with Contraindication to MRI: A Case Report

Abstract

Listen

Translate article

Case Description: A 38-year-old woman with a history of Xlinked hypophosphatemia (XLH), stress fractures and osteomalacia presented to our clinic with a 20-year history of bilateral hip and groin pain. She underwent physical therapy when the pain initially started, and had some relief from manual therapy techniques. The pain was a 7/10 “stabbing” that was made worse with movement in the sagittal plane and external rotation of her hips. She denied numbness, tingling or weakness in her legs. Previous workup included dual-energy X-ray absorptiometry (DEXA) scan four months prior, which confirmed osteomalacia. She was started on vitamin D and phosphorus supplements at that time. Physical examination revealed pain with internal rotation, FABER’s maneuver, AP glide, log roll and a positive impingement sign. Her previous imaging was attained after our visit and an MRI of her hips revealed pseudofractures of her left femoral neck and right proximal femur, in addition to a labral tear on the left and labral degeneration on the right. Setting: Outpatient musculoskeletal clinic. Results or Clinical Course: Pseudofractures (Looser’s zones) as a result of X-Linked hypophosphatemia. Discussion: XLH is one of the most common inherited forms of rickets in North America. It results from a mutation in the PHEX gene on the X-chromosome. These patients are predisposed to bone mineralization defects and pseudofractures. The average age of diagnosis is 3.8 years old, but many cases can be missed due to normal phosphorus levels in children. Treatment involves vitamin D and phosphate supplementation, and patients must be monitored closely for nephrocalcinosis with regular laboratory studies and ultrasound examinations. Our patient was on the correct supplementation regimen, but had no regular follow up. We organized follow up with a local endocrinologist and prescribed a course of physical therapy. There is little literature on the most effective therapy course for these patients, and this represents an avenue for further research. Conclusions: Pseudofractures, or Looser’s zones, are a complication that can be seen in XLH and other vitamin-D deficit patients. It is important to recognize their distinctive appearance on Xray/ MRI imaging, as this can provide a clue to this elusive diagnosis, particularly given the non-specific clinical findings.