Safe Operative Planning For Extensive Neurogenic Heterotopic Ossification (NHO) at the Hip

Abstract

Objectives: Patients_with_traumatic_brain_or_spinal_cord injury are at risk of developing peri-articular NHO most frequently affecting the hip; with resulting ankyloses and functional limitations1. Surgical excision aims to improve functional ability and facilitate nursing care2. It is technically challenging as NHO development maybe multi-focal and multi-directional around the joint involving important neuro-vascular structures2. Plain_radiographs often provide sub-optimal_information_required_for_surgical planning Methods: An_18-year-old_male_presented to us with pain and immobility of his right hip 18-months following a traumatic brain injury. The joint was completely ankylosed and he was unable to walk. Plain radiograph showed extensive NHO from medial aspect of right proximal femur to ischial tuberosity (Figure_1). A CT scan with 3D reconstruction more clearly defined the NHO as extending posteriorly from the greater trochanter to ipsilateral pubic ramus and ischial tuberosity (Figures 2a & 2b). We therefore opted_for_a_Kocher-Langenback approach and performed selective excision to achieve satisfactory_range of motion. RESULTS: The_Kocher-Langenbeck_approach_enabled_us to visualise and access a major segment of the bone bridge. Excision of NHO began at the proximal end of the femur with aim to break the bone bridge between the femur and pelvis to enable hip movement (Figure 3). Limited excision was performed until satisfactory range of motion of hip is achieved as assessed intraoperatively. This is to reduce risk of iatrogenic sciatic nerve injury. 3 months following_surgery, the_patient is now weight bearing_with_80_degrees_of_hip_flexion_with good_internal_and_external_rotation. Conclusion: CT_scanning_with_3D reconstruction should be performed prior to excision of hip NHO as it aids the surgeon in planning the appropriate approach and avoid iatrogenic injury to_adjacent_structures.