Bilateral Metal-on-Metal Hybrid Hip Resurfacing in a Patient with Osteopetrosis

Abstract

Osteopetrosis, also known as marble bone disease1, is a rare inherited skeletal condition characterized by failure of osteoclast-mediated bone resorption. Orthopaedic surgeons most commonly encounter patients with the benign autosomal-dominant type of adult-onset osteopetrosis, who often first learn of their diagnosis after sustaining a fracture. The lifelong prevalence of fractures in this patient group ranges from 40% to 66.6%2-5. Other clinical manifestations include coxa vara (caused by stress-induced microfractures in the femoral neck), spine problems (scoliosis, spondylolysis, cervical spine fractures, and idiopathic low back pain), osteomyelitis, and cranial nerve compression syndromes. Degenerative osteoarthritis may occur in young adult patients with osteopetrosis. The degenerative process is believed to be caused by excessive loads on articular cartilage supported by sclerotic, unyielding subchondral bone6-8. The performance of a stem-type total hip arthroplasty in patients with this condition presents technical challenges because of the difficulty of finding and broaching the femoral canal. In addition, complications such as breakage of drill-bits, iatrogenic fractures, and an increased risk of osteomyelitis secondary to decreased bone vascularity and impaired white blood-cell function have been reported5,9,10. Despite some successful reports7,8,11-16, a stem-type total hip arthroplasty for patients with osteopetrosis remains a very difficult procedure with a long operative time of six hours or more, even for very experienced surgeons15. With the current technological advances in bearing materials and improved techniques of surgery17, resurfacing total hip arthroplasty with use of metal-on-metal bearings could offer a safer option for these patients. To our knowledge, however, there have been only two successful reports describing the use of hip resurfacing for a patient with osteopetrosis18,19. We report the use of a …