Bone mineral content (BMC) of the lumbar spine, femoral neck and shaft, and proximal tibia was measured by dual photon absorptiometry in six men and two women after traumatic spinal cord injuries. In six of these patients, BMC of the distal forearm was measured as well. The patients were 18-49 years old at injury and had complete motor lesions from C7 to L1. All but one had some spasticity, and they all used a wheelchair. The initial BMC measurements were carried out from 9-167 days (median 43) post-injury and followed up by 5-13 (median 8) measurements up to 31-53 months (median 41) after the injury. BMC of the lumbar spine and distal forearm remained nearly unchanged in the whole period, and the measurements were within the normal range, except for the lumbar spine when Harrington rods in the scanned area induced high BMC values. In the lower extremities the BMC decreased after injury. New steady-state levels for BMC were reached at 2 years post-injury for the proximal tibia and the femoral neck at 40-50% and 60-70% respectively of normal values. For the femoral shaft the decrease in BMC was more slow and it seems that a steady-state was not reached within our observation period for several of the patients. This longitudinal study indicates, in agreement with a previous cross-sectional study, that normal muscle function and load bearing is necessary to prevent bone loss.

SummaryBone mineral content (BMC) was measured by dual photon absorptiometry in the lumbar spine, femoral neck and shaft, and proximal tibia in 26 individuals with

At inclusion the BMC of the spine and femoral neck was low in patients with Crohn's disease. During the study significant bone loss was only demonstrated in the femoral neck. BMC or rate of change in BMC was not related to treatment with steroids or length of the resected small intestine.

Regional bone mineral density (BMD, g/cm2) of the proximal tibia including the subchondral plate was measured in vivo by dual photon absorptiometry (DPA). Twenty-one women and six men with gonarthrosis (GA) were examined. Twenty-four healthy women served as controls for the women. The precision error of the BMD measurements ranged from 1.4-3.7% depending on the region measured. Subchondral BMD correlated significantly to the radiologic stage (P < 0.05). Compared to the controls, BMD of the subchondral plate, BMD of the medial condyle, the medial to lateral distribution ratio of subchondral BMD and the ratio between BMD of the subchondral plate and of the immediately underlying region were significantly increased in patients with predominantly medial GA (P < 0.05-0.0001). The BMD of the lateral condyle was lower in GA patients than in controls (P < 0.05). In patients with unilateral GA, the above-mentioned changes were found in the affected tibia compared to the normal knee in the same individual (P < 0.05). In contrast to any of the patients with varus deformity, the two patients with valgus deformity had higher BMD of the lateral condyle than of the medial. No differences in BMD of the distal forearm or the ultradistal region of the proximal tibia were found between the GA patients and the controls. The study shows that regional bone changes of the proximal tibia in GA can be measured precisely and noninvasively in vivo by DPA.