Abstract
Patients with spinal cord injuries have been seen to have increased healing of attendant fractures. This for the main has been a clinical observation with laboratory work confined to rats. While the benefits in relation to quicker fracture healing are obvious, this excessive bone growth (heterotopic ossification) also causes unwanted side effects, such as decreased movement around joints, joint fusion and renal tract calculi. However, the cause for this phenomenon remains unclear.
This paper evaluates two groups with spinal column fractures – those with neurological compromise (n=10) and those without (n=11), and compares them with a control group with isolated long bone fractures (n=10). Serum was taken from these patients at five specific time intervals post injury (24hrs, 120hrs, 10 days, 6 weeks and 12 weeks). The time period most closely related to the end of the acute inflammatory reaction and the laying down of callus was the 10-day post injury time period.
Serum samples taken at this time period were analysed for IGF-1 and TGF-β levels, both known to initiate osteoblastic activity, using ELISA kits. They were also exposed to an osteoblast cell culture line and cell proliferation was measured.
Results show that the group with neurology has increased levels of IGF-1 compared to the other groups (p< 0.14, p< 0.18 respectively, Student’s t-test) but had lower TGF- (p< 0.05, p< 0.006) and osteoblast proliferation levels (p< 0.002, p< 0.001), despite having a significantly higher cell proliferation than a control group (p< 0.0001). When the neurology group is subdivided into complete (n=5) and incomplete (n=5), it was shown that the complete group had higher levels of both IGF-1 and TGF-. This trend is reversed in the osteoblast proliferation assay.
This work, for the first time in human subjects, identifies a factor which may be regulating this complication of acute spinal cord injuries, namely IGF-1. Furthermore, the observed trend in the two cytokines seen in the complete neurology group may suggest a role for TGF-β. However, the results do show that a direct mediation of this unwanted side effect of spinal cord injuries is unlikely as seen in the proliferation assay. Further work remains to be done to fully understand the complexities of the excessive bone growth recognised in this patient group.
Abstracts prepared by Mr. A. J. Stirling, FRCS, and Miss A. Weaver. Correspondence should be addressed to Miss A. Weaver at the Research and Teaching Centre, Royal Orthopaedic Hospital, Northfield, Birmingham, B31 2AP, UK
BritSpine 2002, the second combined meeting of the British Association of Spinal Surgeons, the British Cervical Spine Society, The British Scoliosis Society and the Society for Back Pain Research, took place at the International Convention Centre in Birmingham UK between 27th February and 1st March 2002. The following presentations and posters were given and displayed.
