Biological considerations in osteosynthesis

The normal process of fracture healing was described in which the dual role of external callus was stressed, firstly in providing immobilisation of the fragments and secondly in providing the first bony bridge between the fragments. The influence on this process of stable internal fixation was discussed. External callus is suppressed so that during the remodelling process the patient is dependent upon the implant for its support for up to 1 or 2 years. The clinical implications for this are considerable making it difficult to know at what point the implant should be removed so that there is a significant incidence of re-fracture. The advantages of elastic plate fixation were described. With these it is possible to produce secure fixation without sacrificing external callus avoiding the above disadvantages. Clinical experiences with a composite plate of epoxy resin reinforced with carbon fibre in fractures of the femur and forearm bones produced rapid and reliable union with external callus was achieved whilst still allowing the patient unrestricted use of the limb. This rapid union was particularly useful in osteoporotic bone. The disadvantages are that the plate is expensive and cannot be contoured to bone. The ways in which these problems might be dealt with in the future were discussed.