Histological changes and neural elements in the posterior cruciate ligament in osteoarthritic knees.

PURPOSE To evaluate histological changes and neural elements in 100 posterior cruciate ligaments (PCLs) in patients with osteoarthritis. METHODS 100 PCLs were obtained from a consecutive series of 46 women and 16 men aged 49 to 91 (mean, 67) years who underwent primary PCL-retaining total knee replacement for osteoarthritis. Histology was examined using conventional light microscopy. The PCLs were graded histologically in terms of parallel orientation of collagen fibres, mucoid degeneration, inflammation, and haemosiderin deposition. Histological changes were graded as normal, mild degeneration, moderate degeneration, and severe degeneration. The neural elements were assessed using immunohistochemical staining for S100 protein and neurofilaments. The histopathologist was blinded to the age, gender, and clinical and radiological grades of osteoarthritis. RESULTS One specimen was excluded from analysis owing to inadequate tissue. In the remaining 99 specimens, histology was normal in 72, mildly degenerative in 4, moderately degenerative in 4, and severely degenerative in 15. 76 specimens were positive for S100 protein or neurofilament or both by immunohistochemical staining, indicating the presence of neural elements. CONCLUSION Most knees with osteoarthritis present with viable PCLs. Retaining the PCL in total knee replacement is a good option for better kinematics, stability, and proprioception.