To determine the histological patterns of posterior cruciate ligament (PCL) degeneration during aging and in relation to changes in articular cartilage and anterior cruciate ligament (ACL) across the entire adult age spectrum.
Human knee joints (n=120 from 65 donors) were processed within 72 h of postmortem. Articular cartilage surfaces were graded macroscopically. Each PCL was histologically evaluated for inflammation, mucinous changes, chondroid metaplasia, cystic changes and orientation of collagen fibres. The severity of PCL degeneration was classified as normal, mild, moderate or severe. PCL scores were compared to ACL and cartilage scores from the same knees.
All knees had intact PCL. Histologically, 6% were normal, 76% showed mild, 12% moderate and 9% severe degeneration. Fibre disorientation was the most prevalent and severe change. Histological grades of PCL and ACL correlated, but significantly fewer PCL than ACL showed severe changes. There was a weaker correlation between aging and total histological PCL scores (R=0.26) compared to aging and ACL scores (R=0.42). ACL scores correlated with cartilage scores (R=0.54) while PCL scores increased with the severity of osteoarthritis from grades 0 to III but not between osteoarthritis grades III-IV (R=0.32). In knees with ruptured ACL, the PCL scores correlated with cartilage scores of the lateral compartment.
PCL histopathological changes were less severe than in the ACL. PCL degeneration was associated with ACL and cartilage damage. The lack of correlation with age indicates independent pathways for PCL versus ACL degeneration.