We tested the hypothesis that it is possible to accelerate fracture healing by changing the mechanical environment used in current methods i.e., from initial rigidity or micromovement followed by dynamisation to initial macromovement followed by rigidity (micro-movement).

It is accepted that callus formation requires movement at the fracture site and this callus response is limited to the first few weeks after fracture. Logically, early macromovement at the fracture site would be beneficial for callus formation. Additional callus is not produced by further movement. Indeed, it may be counter-productive, just as continuing movement around two ends of a wooden stick bonded with glue will retard and even prevent “union”. We postulate that continuing movement at the fracture site after the callus response has ceased will also delay union. As a result, rigidity rather than dynamisation is required in the later stage of fracture healing.

After testing an animal model, we built an external fixator which allowed 5 mm of axial movement without “self-locking” and could be compressed at a later date in order to prevent further movement.

A trial containing 15 patients with unilateral tibial shaft fractures (closed or grade 1 open) was undertaken after permission was obtained from the Helsinki Ethical Committee.

So far, 13 patients have been entered into the trial. They have completed therapy and are at least one year post-fracture (12 months to 22 months). Age range is from 20 to 49. The group is composed of nine males and one female.

Under general anaesthetic, an external fixator was applied and the fracture reduced. The patients started ankle exercises (active and passive) the following day, with as much weight-bearing on the fractured leg as possible on the day after. The patients were seen every two weeks and AP and lateral radiographs were taken. The fracture was compressed two to six weeks later. The percentage of body weight that the patient was able to tolerate through the fractured limb was measured by using the scales of Meggit’s step test. The fixators were removed when there was radiographic union and the patient could take at least 80% of body weight through the fractured limb. Mean time duration up to removal of the fixator was 10.8 weeks (range 7 to 15.4 weeks).

We conclude that it is possible to increase the speed of bone healing by changing the mechanical environment to initial macromovement followed by elimination of movement.