Extracorporeal shock wave treatment for defective nonunion of the radius: a rabbit model.

Purpose: To investigate the effect of extracorporeal shock wave treatment (ESWT) on bony union using volume analysis of the callus mass by computed tomography and histology.

Methods: Both radii of 13 rabbits were osteotomised and a defective bony nonunion created by placing a polyethylene pad between the osteotomy site for 40 days. Nonunion was confirmed by radiography using Lane-Sandhu criteria. ESWT (14 kW, 0.46 mJ/mm(2), 1000 shock waves) was applied to the right radius of the rabbits. The left radius served as a control. Five rabbits were killed 4 weeks after ESWT (group 1) and 8 after 6 weeks (group 2). Volume analysis of the callus mass was performed using computed tomography and the bone healing process was assessed by histology.

Results: In group 1, callus volume on the treated side was invariably greater than that on the control side; the difference being statistically significant (p=0.032). In group 2, the callus volume of the treated side was greater than that of the control side, except in rabbits 4 and 9. Only after excluding the findings from the latter did the difference attain statistical significance (p=0.020). Histology confirmed that the bone-healing process was faster in the treated side.

Conclusion: ESWT enhanced the bone-healing process by increasing both volume and speed of callus formation.