Disclosures: Kevin I. Huang, DO: Nothing to disclose

Case Description: Patient presented to clinic a week after tripping with severe left lateral buttock and hip pain. On exam left hip preferentially internally-rotated, gait antalgic, and tender at left buttock, ischial tuberosity, and greater trochanter. No pain with hip range of motion. Manual motor testing 5/5 bilateral lower extremities. In office left hip ultrasound demonstrated a large heterogeneous complex fluid collection overlying the greater trochanter extending 15cm concerning for pseudotumor.

Setting: Academic Outpatient Musculoskeletal Clinic

Patient: 85-year-old male with a history of bilateral total hip arthroplasties (right 2000, left 2005), left femur fracture status post ORIF (2012), and prior traumatic left gluteal muscle tears.

Assessment/Results: Left hip MRI confirmed hip synovitis and proximal femoral pseudotumor from a dehiscent posterior pseudocapsule extending into the greater trochanteric bursa, fascia lata, and lateral subcutaneous tissues. Left hip CT scan with small subacute non-displaced acetabular fracture. Chromium and cobalt serum levels were elevated. Patient’s presentation was consistent with pseudotumor in the setting of trunniosis/metallosis. These findings are supported by synovitis, small particle disease, osteolysis, and by elevated serum levels of chromium and cobalt. On 8-week follow-up patient reported feeling 80% improved, surgical revision was not pursued and patient cleared to pursue physical therapy.

Discussion: Lateral hip pain with extensive greater trochanteric bursa effusion after a hip arthroplasty should prompt one to consider alternative diagnoses to greater trochanteric pain syndrome. Trauma history should make one consider hematoma or Morel-Lavallee lesion. Prosthetic joint history should make one consider pseudotumor due to trunniosis/metallosis or a metallic hypersensitivity.

Conclusion: Pseudotumors form due to an inflammatory response to metallic ion shedding in the setting of metallic hypersensitivity or high wear debris. Pseudotumors are often asymptomatic but can present with groin pain, hip discomfort, antalgic gait, paresthesias, and/or palpable mass. Disruption of the pseudocapsule is common with decompression of fluid and debris into the adjacent tissue.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/pseudotumor-of-the-lateral-hip-after-hip-arthroplasty-a-case-report/