The etiology and pathophysiology of posttraumatic heterotopic ossification (HO) remains unclear but represents a metaplastic osteogenic process.1 Although often asymptomatic, extensive HO can lead to limited joint range of motion (ROM), pain, and disability. The hip is the most frequently involved joint, and risk factors for HO formation include acetabular fracture fixation with posterior or extensile approaches, hip dislocation, and brain or spinal cord injury.2 The Brooker classification is used to describe the extent of HO from stage I (peritrochanteric bony islands), to stage IV (hip ankylosis). Indications for surgical excision of symptomatic HO include severe loss of ROM and resultant disability in the presence of an underlying preserved hip joint. A controversial relative contraindication is early-phase HO with high activity on bone scan. A single 700 cGy dose of radiation or indomethacin 75 mg/d is indicated to prevent recurrence. Radiation has improved compliance and can be administered either within 24 hours preoperatively or up to 72 hours postoperatively. Patients are encouraged to weight bear and begin active and passive hip ROM immediately postoperatively. Potential intraoperative complications include femoral neck fracture or neurovascular injury (sciatic, femoral, or superior gluteal). Postoperative complications include avascular necrosis of the femoral head, wound infection, HO recurrence, and venous thromboembolic disease (see Video, Supplemental Digital Content 1, http://links.lww.com/JOT/A392).
Our patient is a 53-year-old man who initially sustained multiple injuries after being struck by a semitruck while riding a moped. On the right, he had a transverse plus posterior wall acetabular fracture with hip dislocation and a femoral shaft fracture, and on the left, a subtrochanteric femur fracture with extension into the femoral neck as well as a left sacroiliac joint dislocation. The patient underwent right hip closed reduction, right acetabular open reduction and internal fixation through a Kocher-Langenbeck approach, right femur intramedullary nailing, left sacroiliac screw placement, and blade plate fixation of the left proximal femur in staged trips to the operating room. He could not receive radiation prophylaxis for HO given his clinical status and inability to be transferred off-site for the procedure, and was unable to tolerate nonsteroidal anti-inflammatory drugs. Two years later, he presented with right hip pain, stiffness and bony protrusion, and was found to have severely limited hip ROM with full extension, 30 degrees of hip flexion, 20 degrees of abduction, and no internal or external rotation with associated groin pain with attempts at hip rotation. Plain radiographs demonstrated Brooker IV HO, and a computed tomography scan with 3D reconstructions showed the extent of the bridging HO laterally and posteriorly as well as a preserved hip joint space. Because of the presence of a normal hip joint underlying the extensive HO, he was indicated for surgical excision of his HO.
A posterolateral approach to the proximal femur was undertaken using a portion of the previous Kocher-Langenbeck approach with a proximal gluteus maximus split and distal fascia incision to expose the HO. Fluoroscopy was used to differentiate between HO and normal bone. Soft tissue was dissected off the lateral HO, and a wide osteotome was used initially on the proximal lateral bridging HO. Osteotome placement was confirmed on fluoroscopy, and then used to begin the excision. Given the density of heterotopic bone, an oscillating saw was used under fluoroscopy to continue excision. After the proximal, lateral bridging HO was resected, bone anterior to the greater trochanter was coronally divided to allow for elevation off the hip capsule. After that, HO posterior to the greater trochanter was then excised with an osteotome. There was also significant soft tissue invaginated into the irregular bony surfaces that also required careful dissection to expose the HO. After excision of nearly all HO, hip ROM was 110 degrees of flexion, 40 degrees of abduction, 45 degrees of external rotation, and 15 degrees of internal rotation. Final fluoroscopic images confirmed near-complete HO excision and a preserved hip joint space. The wound was copiously irrigated, a hemostatic matrix was applied to the bleeding bony surfaces, and the wound was closed in a layered fashion. The patient had been typed and cross-matched for 4 units of blood, but despite a 1500 cc blood loss, he remained stable and did not require any blood intraoperatively.
Postoperatively, the patient did become hypotensive and required 2 units of blood but then stabilized. He received a 700 cGy dose of radiation within 72 hours, was weight bearing as tolerated, and began ROM therapy. At 2 months, he had minimal pain, was able to sit in a chair, and reach his foot for shoe wear. At 6 months, he was very satisfied with his progress, and his ROM was 90 degrees of flexion, 35 degrees of abduction, and 20 degrees of external and internal rotation. There was no radiographic evidence of HO recurrence on follow-up plain radiographs.
Patients may experience an excellent result from surgical excision, as noted by this patient's improvements in hip ROM, pain relief, and ability to perform previously challenging activities of daily living. Furthermore, he did not experience HO recurrence at final follow-up and had no surgical complications. Current literature on posttraumatic hip HO is limited to case series with varying extents of HO, surgical approaches, and techniques.3,4 On average, a 60–100-degree improvement in the arc of motion is seen, with improvements in Harris Hip Scores. HO recurrence is highly variable, from 0% to 79%, reflecting the heterogeneity of the cases summarized in the published series. Surgical excision of posttraumatic hip HO in the setting of a preserved hip joint can successfully restore hip ROM and function. Larger prospective cohort studies are needed to evaluate the efficacy and survivorship of surgical excision of hip HO, as well as the incidence of surgical complications.
1. Mavrogenis AF, Soucacos PN, Papagelopoulos PJ. Heterotopic ossification revisited. Orthopedics. 2011;34:177.
2. Vanden Bossche L, Vanderstraeten G. Heterotopic ossification: a review. J Rehabilitation Med. 2005;37:129.
3. Macheras GA, Lepetsos P, Leonidou A, et al. Results from the surgical resection of severe heterotopic ossification of the hip: a case series of 26 patients. Eur J Orthop Surg Traumatol. 2017;27:1097.
4. Wu XB, Yang MH, Zhu SW, et al. Surgical resection of severe heterotopic ossification after open reduction and internal fixation of acetabular fractures: a case series of 18 patients. Injury. 2014;45:1604.