Increased bone mineral density adjacent to hydroxy-apatite-coated ankle arthroplasty

We measured bone mineral density (BMD) in patients treated with a unilateral hydroxy-apatite-coated ankle arthroplasty. The study comprised 11 consecutive patients measured preoperatively and postoperatively after 3, 6, and 12 months (group I) and 17 patients measured once at 12 to 82 months follow-up (group II). BMD was measured in the distal tibia adjacent to the prosthesis and in the calcaneus. BMD of the calcaneus was measured bilaterally as an indicator of changes in foot load. In group I BMD was significantly increased in the distal tibia after 6 and 12 months compared to preoperative values. In group II BMD of the distal tibia was significantly higher compared to the non-operated side. No radiolucencies were detected during follow-up in any case. The increase in BMD and the radiographic findings after uncemented ankle arthroplasty indicates that it is being loaded by the prosthesis. This may indicate a well fixed prosthesis.