Lower numbers of mechanoreceptors in the posterior cruciate ligament and anterior capsule of the osteoarthritic knees.

PURPOSE: Impaired proprioception accuracy of the knee has been proposed as a local factor in the onset and progression of knee osteoarthritis. Patients with decreased numbers of mechanoreceptors could be more likely to develop arthrosis due to a loss in proprioception of the joint. We aimed to identify and quantify the mechanoreceptors of the posterior cruciate ligament (PCL), the anterior capsule (AC) and the medial meniscocapsular junction (MCJ) in knee arthrosis.

METHODS: PCLs, ACs and MCJs were harvested from 30 patients with Kellgren and Lawrence grades 3 and 4 osteoarthritis (OA), and ten knees taken from five cadavers without OA were used as a control group. PCL degeneration was evaluated with haematoxylin & eosin, and the types and numbers of mechanoreceptors were evaluated using S100 immunostaining.

RESULTS: The patient ages in the OA and control groups (n.s.) did not differ. PCL degeneration was more severe in the gonarthrosis group than in the control group (p = 0.04). The numbers of Golgi corpuscles, Ruffini corpuscles, free nerve endings, total nerve endings and small vessels of the PCL were low in the OA group, as were the numbers of Golgi corpuscles, free nerve endings and total nerve endings of the AC. No significant correlation was found regarding the mechanoreceptors of the MCJ between the two groups.

CONCLUSION: The numbers of mechanoreceptors in patients with OA were low in the PCLs and ACs. A loss in proprioception could be a local risk factor in OA. The proprioceptive impact of preserving PCL while performing total knee arthroplasty may not be exaggerated as its thought.

LEVEL OF EVIDENCE: Prognostic study, Level I.