Abstract
Introduction and Aims: The radiographic appearance of fractures is often used as an evaluative tool when assessing the status of healing fractures. The aim of this study was in the first instance to assess the reliability of orthopaedic surgeons to measure the area of periosteal callus and secondly to compare the area with the biomechanical strength of the fractures.
Method: Thirty-seven sheep underwent a transverse osteotomy of the right radius. All sheep were managed in a plaster cast and splint to ensure non weight-bearing during rehabilitation. Nineteen of the sheep were ran-domised to receive cyclic loading by the application of a pressure cuff around the muscles of the proximal forearm deep to the cast. The other 18 sheep acted as controls. Sheep from both groups were sacrificed at either four or six weeks. Fractures were x-rayed and subjected to biomechanical testing following sacrifice. X-rays were transferred to a Labview program from which the area of callus was measured. Biomechanical testing of the fractures was a torsional test to failure. The peak torque, stiffness and energy absorbed over the first 10 degrees of torsion were measured for each fracture.
Results: The two orthopaedic surgeons who measured the area of callus showed a positive correlation (r = 0.85). When the four-week fractures that were treated with cyclic loading were compared with the four-week control fractures, the periosteal callus measurement along with the peak torque, fracture stiffness and energy absorbed over the first 10 degrees of torsion all showed a significant difference (p < 0.05). In addition, when the six-week fractures that were treated with cyclic loading were compared with the six-week control fractures, the periosteal callus measurement along with the peak torque, fracture stiffness and energy absorbed over the first 10 degrees of torsion were not significantly different (p > 0.05).
Conclusion: The results show that the area of periosteal callus on radiographs can be related to the biomechanical status of a healing fracture. Further research is required to determine if other characteristics of the periosteal callus plus quantification of the callus area is able to accurately predict fracture strength.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
One or more of the listed authors are receiving or have received benefits or support from a recognised academic body for the pursuance of the study.
