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.