Attachments of separate small bundles of human posterior cruciate ligament: an anatomic study.

Purpose: To date, there is no consensus on the detailed anatomy of the posterior cruciate ligament (PCL) and the most appropriate PCL reconstruction method. The purpose of this study is the detailed observation of separate small PCL bundles for better comprehension of detailed PCL anatomy to facilitate the design of anatomic PCL reconstruction.

Methods: Twelve cadaveric knees were used in this study. PCL was divided into anterolateral and posteromedial (PM) sections and then separated into about 20 small bundles of 1 mm in diameter while maintaining preservation of their attachment sites marked with fine coloured marker pens. The positional relationship between the femoral and tibial attachments of each small bundle was investigated.

Results: The small bundles of tibial and femoral attachments showed a topographical correlation. The anterior-posterior aligned bundles in the tibia corresponded to the bundles aligned in a low-high direction in flexion in the femur. The femoral attachment pattern was relatively similar in each specimen. However, the tibial attachment showed two patterns of small bundle footprint location: a parabolic type (6 of 12) and a transverse type (6 of 12). The posterior portion of the PM bundle was separately attached to the medial and lateral portions in the tibial attachment.

Conclusion: Small bundles of PCL showed a relatively layered arrangement between tibial and femoral attachments. Therefore, anatomic PCL reconstruction cannot be completed simply performed merely with straight bundles and circular bone tunnels.