Systemic Effects of Experimental Spinal Cord Injury on Bone Healing in Rabbit

Bone loss after spinal cord injury leads to increased fragility of bone and subsequent risk for low-trauma fractures in the sublesional parts of the body. Although in such injuries upper limbs are normally innervated, bone loss may occur in the upper extremities. The present study was designed to determine the systemic effects of spinal cord injury on the fracture healing of upper limbs in rabbits. Twenty nine skeletally mature New Zealand white rabbits received a transverse mid-humeral open osteotomy in the left upper limb with the use of a standardized technique and spinal cord injury was done using forceps model at T8 level. The animals were divided into three groups: experimental (laminectomy, spinal cord injury, and osteotomy), sham (laminectomy and osteotomy), and control (osteotomy alone). The bone healing score was calculated using modified Sandhu system by two independent pathologists. The mean (±SD) of healing scores in experimental, control, and sham groups were 7.22 (± 3.6), 8.6 (± 3.3), and 8.5 (± 4.3) respectively (P=0.68). The percentage of mesenchymal (20%) and cartilaginous tissue (35%) showed a slightly higher value in the experimental group compared with the sham group (15% and 20% respectively). A reverse pattern was seen concerning the percentage of trabecular bone, though as a whole there was no significant difference regarding the percentage of selected components of bone healing between the three trial groups. Fracture healing in innervated upper limbs is not influenced by the systemic effects of spinal cord injury.