PCL Reconstruction

Figure 1

The posterior cruciate ligament PCL originates on the back of the tibia and runs to the front of the femur (Fig 1). The PCL stabilizes the knee by keeping the shin from moving backwards in relation to the thigh. When torn, the knee can become unstable. Eventually the instability can lead to pain and swelling. Like the ACL the PCL does not heal well on its own.

Figure 2

However, the PCL is larger and more complex than the ACL. One portion of the PCL provides stability when the knee is straight and another portion when it is flexed. To recreate the unique double bundled nature of the PCL an Achilles Tendon allograft used. The larger Achilles tendon is ideal for reconstructing the bulky PCL. The Achilles tendon graft is prepared as a single bone block with two.

Figure 3

We have designed a specialized drill guide which is used to position and then drill the tibial tunnel (Fig 3). The goal is to place the center of the tibial tunnel at the anatomic center of native PCL attachment. The guide protects the vessels and nerves that are located next to the PCL from the drill.

The insertion of the PCL on the femur is relatively planar and approximates a “half moon”. Its widest dimension at an average of 32 mm is in the anterior posterior direction.

Figure 4

In order to reconstruct the bulk of the femoral insertion and reproduce the double bundled biomechanics of the native PCL two femoral tunnels are created (Fig 4). An 8 mm reamer is used to drill both tunnels and slot-eyed pins are advanced into each tunnel until it exits the thigh medially. The pins are used to pull the graft into place.

Figure 5

The graft is passed through the tibial tunnel first so that the bone plug is situated in the tibial tunnel. Using a grasper, the sutures from both Achilles tendon bundles are advanced through the tibial tunnel and into the joint and then into the femoral tunnels. (Fig 5 & 6).

Figure 7

Proper tensioning and fixation of the graft is crucial to the success of the reconstruction. Because the two bands tighten separately as the knee is flexed and extended during flexion/extension some portion of the PCL remains tight at all positions. To reproduce the double bundled biomechanics one bundle is tightened and fixed in extension and the other in flexion Femoral and tibial fixation is accomplished with bioabsorbable interference screws (Fig 7).