Posterior Cruciate Mechanoreceptors in Osteoarthritic and Cruciate-retaining TKA Retrievals: A Pilot Study

Background Although normal cruciate ligaments and those in patients with osteoarthritic (OA) knees contain mechanoreceptors, it is unclear whether they are present after functioning in a cruciate-retaining total knee arthroplasty (TKA).

Questions/purposes We therefore determined if the areas occupied by mechanoreceptors in the human posterior cruciate ligament (PCL) are similar in patients with osteoarthritis and in patients who have had TKA with retention of the PCL.

Methods We identified five cruciate-retaining TKA specimens from a retrieval program and obtained five PCLs during cruciate-sacrificing TKA from patients with OA; the retrieved specimens had been in place 5 to 12 years. The whole en bloc PCL specimens were harvested for the study. These specimens were then sectioned to a thickness of 8 μm and mounted on microscope slides. Two transverse cross-sections from the distal third from each specimen 100 μm apart were then subjected to immunohistochemistry with neurofilament protein (NFP) and S-100 protein.

Results All five PCL specimens in each group revealed multiple areas of positive stained elements with both S-100 protein and NFP immunohistochemical staining. Morphologically, these elements appear to correspond to Pacinilike, Golgilike, and fusiform types of mechanoreceptors. We observed no difference in positive staining mechanoreceptor elements as a percentage of area in the osteoarthritis and TKA groups.

Conclusion Mechanoreceptors appear to occupy similar areas before and after implantation of a TKA.

Clinical Relevance If mechanoreceptors continue to function after cruciate-retaining TKA, then it may continue to participate in proprioception of the knee after TKA.