Bone histomorphometry of the iliac crest, and spinal fracture prevalence in atrophic and hypertrophic osteoarthritis of the hip.

While some authors report high bone density in osteoarthritis (OA), surgical experience with total hip arthroplasty (THA) for primary OA suggests the existence of osteoporotic subsets of patients. To identify these we analysed 107 iliac crest bone biopsies, taken at THA, by routine histomorphometry for trabecular structural and bone turnover features, and examined radiographs of the spine for vertebral fractures. Patients were grouped by hip osteophyte size (none, atrophic; small, hypotrophic; moderate, supertrophic; large, hypertrophic OA), and by major architectural disorganization of the hip (hip joint destruction, protrusio). We found hip joint destruction to be 3 times more common in atrophic than in supertrophic and hypertrophic OA (p less than 0.05). Overall, the OA patients had lower bone volume (p less than 0.05) and thinner trabeculae (p less than 0.05) than controls. Worst affected were patients with hip joint destruction and with protrusio: they also had fewer and more widely spaced trabeculae than controls (p less than 0.05). The spinal fracture prevalence was highest in patients with hip joint destruction (higher than in the general population), intermediate in those with protrusio or atrophic OA, and lowest in patients with supertrophic or hypertrophic OA. We conclude that OA hip patients with joint destruction or protrusio have a high prevalence of generalized osteoporosis, and that the larger the hip osteophytes, the lower is the prevalence of generalized osteoporosis. Our findings suggest that the generalized bone status may influence the outcome of OA of the hip.