Total Hip Arthroplasty in Patients With Osteopetrosis.

Background: Osteopetrosis is an inherited bone disease associated with high risk of osteoarthritis and fracture non-union, which can lead to total hip arthroplasty (THA). Bone quality and morphology are altered in these patients, and there are limited data on results of THA in these patients. The goals of this study were to describe implant survivorship, clinical outcomes, radiographic results, and complications in patients with osteopetrosis undergoing primary THA.

Methods: We identified 7 patients (9 hips) with osteopetrosis who underwent primary THA between 1970 and 2017 utilizing our total joint registry. The mean age at index THA was 48 years and included two males and five females. The mean follow-up was 8 years.

Results: The 10-year survivorship free from any revision or implant removal was 89%, with 1 revision and 1 resection arthroplasty secondary to periprosthetic femoral fractures. The 10-year survivorship free from any reoperation was 42%, with 4 additional reoperations (2 ORIFs for periprosthetic femoral fractures, 1 sciatic nerve palsy lysis of adhesions, 1 hematoma evacuation). Harris hip scores significantly increased at 5 years (P = .04). Five hips had an intraoperative acetabular fracture, and 1 had an intraoperative femur fracture. All postoperative femoral fractures occurred in patients with intramedullary diameter less than 5 mm at a level 10 cm distal to the lesser trochanter.

Conclusion: Primary THA in patients with osteopetrosis is associated with good 10-year implant survivorship (89%), but a very high reoperation (58%) and periprosthetic femoral fracture rate (44%). Femoral fractures appear associated with smaller intramedullary diameters.