Objectives: RSD is associated with intractable pain, hyperalgesia and decreases in bone mass. In the present study, we measured bone mass in 19 upper limb RSD patients and compared obtained values on both the affected and normal side. Left and right differences in the patients were also compared to those observed in healthy volunteers. The correlation between the time from RSD onset and decreases in bone mass was also evaluated.
Methods: Bone mass was measured in the second metacarpus by microdensitometry (MD). The following 4 parameters were used for comparison: MCI, ΣGS/D, GSmax and GSmin.
Results: Left and right differences were 3% to 9% for all parameters in the control group, while in the RSD group, decreases in bone mass of 14% (MCI) and 12% to 25% (ΣGS/D, GSmax and GSmin) were observed on the affected side. ΣGS/D and GSmin data showed significant correlation between the time from RSD onset and decreases in bone mass.
Conclusion: Findings obtained in the present study suggested that decreases in bone mass are due to decreases in bone density, rather than thinning of cortical bones, a pattern different from that observed at the degenerative stage of osteoporosis. It was also found that bone density decreases with time after onset and that decreases in bone mass occur already at an acute stage.