Figure 2.

Chronic implantation of a balloon catheter in the femur. A skin incision was made on the medial side of the right knee, and the proximal patellar ligament of the femur was severed, revealing the synovial space of the knee joint. A 22-gauge needle was used to core between the femoral condyles and into the medullary cavity of the right femur. A diamond drill burr, 1 mm in diameter, was used to prime the opening of the hole made by the 22-gauge needle. A balloon catheter used for coronary angioplasty in patients with coronary artery disease (PTCA catheter, RX-2, 2 × 15 mm, TERUMO Co., Tokyo, Japan) was implanted in the medullary cavity of the femur for increasing intraosseous pressure of the femur. The balloon catheter was then tunneled subcutaneously to emerge at the neck. To stimulate intraosseous receptors, the balloon was inflated with saline using an inflation device (Encore™ 26, Boston Scientific Japan, Tokyo, Japan).