Ankylosing Neurogenic Myositis Ossificans of the Hip: A Case Series and Review of Literature

Abstract

Purpose: Neurogenic myositis ossificans (NMO) in patients with traumatic spinal cord or brain injuries can cause severe joint ankylosis or compromise neurovascularture. The purpose of this study was to evaluate the clinical and radiological outcomes of and review considerations relevant to surgical resection of NMO of the hip joint.

Materials and methods: Six patients (9 hips) underwent periarticular NMO resection between 2015 and 2017. The medical records of these patients were retrospectively reviewed. Preoperative computed tomography including angiography was performed to determine osteoma location and size. Improvement in hip motion allowing sitting was considered the sole indicator of a successful surgery. The anterior approach was used in all patients. The ranges of motion (ROM) before and after surgery were compared.

Results: The mean time from accident to surgery was 3.6 years. Average ROM improved from 24.3°(flexion and extension) to 98.5°(flexion and extension) after surgery, and improvement was maintained at the last follow-up. No commom complications (e.g., deep infection, severe hematoma, deep vein thrombosis) occurred in any patient. Improvement in ROM in one hip in which surgical resection was performed 10 years after the accident was not satisfactory owing to the pathologic changes in the joint.

Conclusion: Surgical excision of periarticular NMO of the hip joint can yield satisfactory results, provided that appropriate preoperative evaluation is performed. Early surgical intervention yields satisfactory results and may prevent the development of intra-articular pathology.

Keywords: Heterotopic; Hip; Margins of excision; Myositis ossification; Ossification.

Fig. 1. An 18-year-old male patient complaining of severe ankylosis in the right hip joint. (A) Intra-operative image of the right hip showing an irregularly shaped, 13 cm wide, 25 cm long osteoma. (B) The osteomas were very large and had to be split into several pieces to be removed. (C) Anteroposterior radiogram showing complete ankylosis of the hip. (D) Radiogram at 1 year after surgery showed small calcific deposit but no evidence of recurrence of severe ossification.

Fig. 2. Anteroposterior radiogram of a 31-year-old male patient reveals large bilateral osteomas of the hips in a bridge from the iliac bone to the femoral shaft (A). (B) Postoperative radiogram 6 months after surgical resection of neurogenic myositis ossificans showing joint destruction with collapsed joint space.