A total of 78 patients with SCI in our hospital from April, 2018 to May, 2020 were selected and divided into groups according to the injury courses. The people receiving physical examination in the same period were selected as control. BMD of proximal femur was measured by dual energy X-ray absorptiometry. Bone metabolic markers were detected. The correlation between BMD and clinical indicators was analyzed.

There was no difference in BMD between the patients within three months and the controls (P > 0.05). BMD at trochanter major, intertrochanteric and total hip in patients three to six months post injury was lower than that in the controls (|t| > 2.242, P < 0.05). The BMD at femoral neck, trochanter major, intertrochanteric and total hip in patients during six to twelve months post injury was lower than that in the controls (|t| > 2.026, P < 0.05). BMD at proximal femur in patients with twelve to 24 months post injury was lower than that in the controls (|t| > 2.189, P < 0.05). The decrease of BMD aggravated with the course of injury. There was no difference in BMD between paraplegia and quadriplegia, complete injury and incomplete injury (P > 0.05). Collagen type I C-terminal telopeptide (CTX) and N-terminal propeptide of type l precollagen (PINP) were higher than the reference range in the course of each injury, increased within three months post injury, reached the peak at three to six months post injury, and decreased to a steady state since seven months post injury. Vitamin D deficiency occurred in 87.5% of the patients. BMD at femoral neck and total hip was negatively correlated with the course of injury (|r| > 0.250, P < 0.05), and positively correlated with body mass index (r > 0.255, P < 0.05).

The longer the duration of SCI, the more decrease of BMD. The early bone metabolism of patients with SCI is high conversion type. The rate of vitamin D deficiency in patients with SCI is quite high. It is necessary to detect and evaluate the bone metabolic markers combined with BMD at the early stage of SCI.