BACKGROUND: Hemiplegia caused by stroke or brain injury may lead to secondary osteoporosis. Under the circumstance, bone mineral density (BMD) and Bone Mineral Content (BMC) are two effective factors for predicting the risk of osteoporosis-related fracture OBJECTIVE: To investigate the characteristics of secondary osteoporosis in stroke patients with hemiplegia by measuring and analyzing BMD and BMC.DESIGN: A case study.PARTICIPANTS: From March 1999 to May 2002, 156 hemiplegia patients at the Neurorehabilitation Department of Peking Boai Hospital were selected, 87 males and 69 females, with an age ranging from 17 to 65 years old, in average of (47.0±5.3) years old and having a course of diseases ranging (5.0±3.5) months. The types of their illness: 89 had cerebral infarction, 67 had cerebral hemorrhage. Hemiplegia sides: 79 patients had hemiplegia in the left and 77 in the right.METHODS: Using LUNAR Dual Energy X-Ray densitometers, all the patients underwent a fro-top-to-toe scan to assess the BMD and BMC status.MAIN OUTCOME MEASURES: ① The occurrence rate of osteoporosis in patients with various course of hemiplegia. ② The BMC in patients with hemiplegia in various part.RESULTS: All the 156 patients entered the statistical analysis procedure.① The occurrence rate of osteoporosis was highest in patients with 3 to 6 months of hemiplegia (44%, 16/36) and was lowest in those with 9 to 12 months of disease (21%,7/33). The total occurrence rate of osteoporosis was 31% (48/156). ② For those with a less-than-3-month course of hemiplegia: Of all the 47 patients, 9 had dystonic hemiplegia, all suffering from osteoporosis and 2 of whom having fracture. For those with a 3-to-6-month course of hemiplegia: Of all the 36 patients, 3 had dystonic hemiplegia and osteporosis as well. ③ BMC in the affect side of upper limb was signifi cantly lower than that in healthy side [(154.76±43.91) g, (172.59±43.78) g,t=3.591, P＜ 0.001]. BMC in the affect side of lower extremity was close to that in healthy side [(463.41±30928) g, (464.11±86.45) g, t=0.027, P＞ 0.05].CONCLUSION: In patients with hemiplegia, changes in bone mass fluctuate with the length of hemiplegia. BMC in the affect side of upper limb is low while that in the healthy side is nearly normal. It may be explained that upper extremities start the functional exercises at an early time. This indicated that bone mass has a close relationship with excercises.