Introduction

The middle third of the patella tendon (bone–tendon–bone) is frequently used as a graft to replace a torn anterior cruciate ligament (ACL). A segment of bone is taken from the tibial tubercle. It is left attached to the distal end of the patella tendon. A segment of bone is taken from the inferior pole of the patella. It is left attached to the proximal end of the tendon. The graft is reversed and is pulled upward through the tibial tunnel, across the joint, and into the femoral tunnel. The leading end of the graft (the bone plug that was taken from the tibia) is fixed to the femur using an interference screw. The trailing end of the graft (the patella portion) is fixed in the tibial tunnel using an interference screw. Extra pieces of bone that were trimmed from the bone plugs are placed in the patella defect. The edges of the patella tendon are closed.

Skin Incision

A vertical skin incision is made medial to the tibial tubercle approximately 0.5 cm medial to the medial edge of the patella tendon (Fig. 14-1). The upper end of the incision begins near the level of the joint line. The incision is extended distally to the level of the lower end of the tibial tubercle, approximately 6 to 8 cm below the joint line. Do not place this vertical incision in the midline of the knee: this leaves an unsightly scar, and it is difficult to reach the tibial tunnel from this midline position. This anteromedial incision is placed distally, which is necessary to allow positioning of the tibial guide and drilling of the tibial tunnel (Fig. 14-2). It is not necessary to extend the incision very far proximally beyond the level of the joint; when the knee is extended and a single spike retractor is placed at the superior pole of the patella, the patella is pushed distally. The patella can thus be reached through this short, distally placed incision.

Fig. 14-1 The skin incision is made on the medial aspect of the right knee. The incision begins at the joint line and extends distally about 6 to 8 cm. Do not place the incision over the center of the tibial tubercle.

Fig. 14-2 The skin incision has been placed distally and medially to allow proper placement of the tibial drill guide.

Bupivacaine 0.5% with epinephrine 1:200,000 is infiltrated subcutaneously along the edges of the incision. Dissection is carried out through the superficial fascial layer to reach the deep fascial layer.

Exposure

Incise the deep fascial layer lengthwise over the center of the underlying patella tendon. This deep fascial layer is thin but becomes even thinner over the tibial tubercle. Divide the deep fascial layer proximally to the level of the upper portion of the patella (Fig. 14-3). This exposes the underlying patella, patella tendon, and tibial tuberosity. Enlarge the prepatella bursa to gain access to the patella.

Fig. 14-3 The deep fascia is incised over the center of the tibial tubercle, patella tendon, and patella.

Taking the Graft