ABSTRACT
Single-bundle posterior cruciate ligament (PCL) reconstruction can restore normal
posterior laxity; double-bundle reconstruction is needed to more closely mimic normal
knee kinematics. Drilling two tunnels removes additional bone from the medial femoral
condyle and may interfere with its vascular supply, increasing the risk of fracture
or subchondral collapse. Three groups of seven synthetic femurs were tested: no tunnels,
single anterolateral 10-mm tunnel, and double tunnel (anterolateral 10-mm tunnel and
posteromedial 8-mm tunnel). The distal femur was potted to rigidly hold each specimen
during testing. Compressive loading was performed at 2 mm/minute using an Instron
(Instron Corp, Canton, Mass). Load and displacement at failure were recorded; stiffness
was calculated from those measurements. Mean failure load of the double-tunnel group
(7705 N) was significantly lower than the intact group (10962 N, P < .008). No other significant differences were detected.
In this model, the double-bundle technique significantly reduced failure force, increasing
the potential risk of medial femoral condyle fracture compared to the intact femur.
The double-bundle technique also trended toward reduced stiffness. Therefore, a period
of postoperative protected weight bearing is recommended.
