Osteomalacia and osteoporosis in femoral neck fracture.

Iliac crest bone histomorphometry, plasma and urine biochemistry and clinical history were examined in 78 unselected patients (68 women, 10 men) at the time of femoral fracture. Histological abnormalities occurred in 56 of the 78 biopsies. The commonest of these was a low bone volume of less than 15% which, irrespective of other abnormal histological features, was present in 37 ot the biopsies. On the basis of the histomorphometry, patients could be classified into four main groups. Normal histomorphometry (bone volume > 15%, osteoid surfaces 60%) was present in 22 patients, 23 had osteoporosis as the only abnormality (bone volume 60%), nine had osteomalacia (osteoid surfaces > 24%, mineralising surface 13μm) and 13 had decreased mineralising surfaces. Of the remainder, five had increased osteoid surface and six had insufficient osteoid to assess mineralising surface. Plasma and urine biochemistry in the four groups showed that, compared to age-matched controls, all groups had reduced plasma albumin. In comparison to the group with normal histomorphometry, patients with osteoporosis had a higher plasma calcium (P < 0.01), tubular reabsorption of calcium (P < 0.05) and plasma vitamin D binding protein (P < 0.01); patients with osteomalacia had a higher plasma creatinine (P < 0.02) and parathyroid hormone (P < 0.02) and lower plasma 24,25-dihydroxyvitamin D (P < 0.02), urinary calcium/ creatinine ratio (P < 0.02) and tubular reabsorption of phosphate (P < 0.02). The biochemistry in patients with decreased mineralising surface was no different from patients with a normal biopsy. The prevalence of both osteoporosis and osteomalacia increased with age and, in subjects over the age of 90, osteoporosis occurred in 71% of patients and osteomalacia occurred in 29% of patients. The osteomalacic group were significantly older than the other three groups (P < 0.05). The histomorphometry did not relate to the site of fracture (subcapital or intertrochanteric). A history of stroke, gastrectomy, rheumatoid arthritis, steroid treatment, thyroid disease, alcohol abuse and anti-convulsant therapy was present in patients with femoral fracture but did not relate to any particular histomorphometric classification.