Enhancement of bone growth into porous intramedullary implants using non-invasive low intensity ultrasound.

An in vivo study was designed to determine if non-invasive low intensity ultrasound could enhance bone growth into porous intramedullary implants. Fully porous intramedullary rods were implanted bilaterally into the ulnae of six dogs. In each dog, one ulna served as a control and the other was treated with 20 min of daily ultrasound stimulation for 6 consecutive weeks. Analysis of serial transverse sections indicated an average of 119% more bone growth into the ultrasound-treated implants compared with the contralateral controls (P < 0.001). In each of the 6 dogs, there was a significantly greater amount of bone ingrowth on the ultrasound-stimulated side. These data indicate a clear potential for externally applied ultrasound therapy to augment biological fixation.