Bone ingrowth into porous coated canine total hip replacements. Quantification by backscattered scanning electron microscopy and image analysis.

Bone ingrowth into titanium fiber mesh porous-surfaced canine total hip replacement prostheses was evaluated and quantified using a computer assisted image analysis system attached to a scanning electron microscope equipped with a back scattered electron detector. Excellent contrast between the bone, the porous metal and the soft tissues resulted in the backscatter mode, allowing easy differentiation of these components in real time by the image analysis based on gray scales. By three weeks the mean (+/- standard deviation) amount of bone ingrowth expressed as a percentage of porous layer measured 7.2% (+/- 1.5%) for the acetabular components, and 3.9% (+/- 1.7%) for the femoral components. At six weeks the amount of bone ingrowth increased to 10.5% (+/- 1.3%) for the acetabular components and 8.5% (+/- 1.4%) for the femoral components. Cementless prosthetic fixation using porous surfaced prostheses holds great promise in joint replacement surgery, and the ability to quantitate the amount of bone ingrowth will permit the evaluation of the efficacy of various techniques to improve bone ingrowth.