Presentation
Limitation of movement of the right hip. History of right hip hemiarthroplasty.
Patient Data
Right hip hemiathroplasty is noted, with intact prosthesis and no evidence of loosening.
Narrowed joint space with decreased cartilage thickness and acetabular bone erosions (grade I according to Baker classification).
Extensive periarticular heterotopic ossification involving surrounding muscles and around joint capsule with fragmentation and secondary extra-articular hip impingement.
Decreased bulk with partial fatty replacement of the right sided gluteal and hip muscles, suggestive of mild disuse muscle atrophy.
Osseous projections posterior to the left hip joint along the course of left gluteus minimus and medius muscles, mostly secondary to heterotopic ossification.
Case Discussion
Heterotopic ossification is the abnormal formation of mature bone within extraskeletal soft tissues. It is one of the complications after hip surgery that can cause pain and limitation of movement up to complete joint ankylosis in severe cases 1.
This is a case of right hip hemiarthroplasty complicated with acetabular cartilage erosion and extensive heterotopic ossification exerting extra-articular hip impingement associated with secondary disuse muscle atrophy.
The patient was treated with surgical excision of the bony overgrowths around right hip joint. Unfortunately, post-operative infection occurred which was managed with right hip prosthesis removal and disarticulation.