The effects of spinal cord injury on the bone and bone callus microarchitecture, strength and metabolism in paraplegic rats. Are drugs, mechanical loading and ultrasound therapy effective at maintaining and improving skeletal health?

Abstract

Spinal cord injury (SCI) is a condition that largely impairs bone turnover, increases fracture risk and is related to abnormal bone healing. Purpose: to assess the effects of SCI on the bone and bone callus quality in paraplegic rats, treated or not with pharmacological agents, passive standing and ultrasound therapy. Materials and methods: 96 rats will be divided into 6 groups: (1) Sham: control rats with bone fracture; (2) SCI: SCI rats with bone fracture; (3) SCI+ALE: SCI fractured rats treated with alendronate; (4) SCI+PTH: SCI fractured rats treated with PTH; (5) SCI+PS: SCI fractured rats treated with passive standing and; (6) SCI+US: SCI fractured rats treated with ultrasound. SCI rats will undergo a spinal surgery for complete spinal cord transection at the T10 level. 21 days after surgery rats will undergo a closed bone fracture at the mid-femur. Then, bone fragments will be stabilized with orthopedic implant. Bone healing will be followed by 14 days. Rats will receive subcutaneous PTH and alendronate 5d/wk. Passive standing and ultrasound will be administered 5d/wk for 20 minutes. Bones will be assessed by: optical microscopy; ¼CT; immunohistochemistry; qPCR; BMD; mechanical test and; serum bone marker and adipokines. These results will allow a better understanding of the mechanisms that lead to bone loss and changes in bone healing due to disuse. Furthermore, the effects of pharmacological agents, mechanical loading and ultrasound therapy at improving or maintaining bone quality and bone callus formation will be investigated. (AU)