Breakdown of spontaneous fused bilateral hip with heterotopic ossification to staged bilateral total hip arthroplasty through a direct lateral approach: A case report

Introduction: Heterotopic ossification (HO) is the abnormal bone formation in soft tissue where bone normally does not exist. HO can occur secondary to musculoskeletal trauma, burns, spinal cord injury, or traumatic head injury. The treatment of HO ranges from simple medical treatment to advance surgical intervention; it is largely dependent on the amount of bone formation, the location, the limitation of motion, and the severity of the joint disease. Presentation of case: We present the case of a 26-year-old man who presented to an orthopedic clinic with pain in the lower back and both knees, which was not relieved by conservative treatment. The clinical examination revealed a loss of motion in both hips. Radiography of the pelvis showed bilateral fused hips and Brooker type IV HO in both hips. The patient underwent HO resection and converted the fused hip to total hip arthroplasty (THA) through a direct lateral approach. The patient was satisfied with the outcome of over 18 months of follow-up. Discussion: A direct lateral approach, as what we performed, is a simple approach that can expose the acetabulum and proximal femur. The presence of intraoperative fluoroscopy can help identify HO's extension with less damage to the soft tissue and blood loss. Conclusion: The surgery appears to be a doable, effective, and safe procedure to treat fused bilateral hip with HO. This is the first study to report staged bilateral THA for HO through a direct lateral approach to the best of our knowledge.