Innervation of nociceptors in the menisci of the knee joint: an immunohistochemical study

Abstract

Using histology, we studied the innervation of nociceptors in the medial and lateral menisci of the knee joint. Specimens examined were taken from 16 patients during arthroplasty. The patients were 6 men and 10 women, with ages ranging from 14 to 76 years (mean 56 years). Immunohistochemistry with the unlabeled antibody biotin-streptavidin method was employed to detect protein gene product 9.5 (PGP 9.5) or substance P (SP) in the specimen. The antibody for PGP 9.5 detected nerve tissues in the menisci. Most but not all of the nerve fibers were associated with blood vessels. Nerve fibers and sensory receptors were found mainly in the peripheral, vascular zone, representing the outer one-third of the meniscus, and the innervated area was wider in the anterior and posterior horns. Pacinian and Ruffini corpuscles as well as free nerve endings were identified in these areas. Larger fibers coursed circumferentially in the peripheral zone, with smaller branches of nerve fibers running radially into the meniscus. Nerve fibers positive for SP were also detected in the menisci, but were fewer in number. Their branches also were fewer, oriented radially and paralleling blood vessels. This study showed that some of the pain in cases of meniscal tear could originate in the meniscus itself, especially with peripheral tears that may be accompanied by bleeding.

Anti‐inflammatory effects of continuous passive motion on meniscal fibrocartilage

“…In fact, in humans it has been noted that CPM regimens ameliorate pain as suggested by the fact that patients on CPM therapy ask for fewer pain killers than those not being treated by CPM [16]. Since zone A of the menisci is innervated with nerve fibers and nociceptors, the perception of pain realized during inflammation of the knee joint may be in part attributed to the increased COX-2 levels in the fibrochondrocytes [15]. We have observed that CPM limits expression of COX-2 in menisci, which provides mechanistic evidence for the observed effects of CPM therapy on pain.…”

Meniscal tear—a feature of osteoarthritis

“…The nerve fi bers mostly follow the blood vessels, with the two horns of the meniscus being the richest innervated. The inner 2/3 of the meniscus have no nerves (Wilson et al 1969, Day et al 1985, Mine et al 2000.…”

Discrepancy of Magnetic Resonance Imaging Findings, Symptom Severity and Functional Status in Knee Osteoarthritis

“…Findings of Zarins et al (15) indicated that WOMAC scores were more strongly correlated with the meniscus than cartilage. These findings were explained by the fact that articular cartilage is avascular and aneural while the outer one-third of the meniscus is vascularized, contains nerves, and nociceptive fibers (16) . In a study which investigated the association of ligament injury with pain severity anterior cruciate ligament tear was found tended to have greater knee pain at baseline, over 30 months follow-up, and there was no differences in pain severity or degree of function between those who did or did not have a complete anterior cruciate ligament tear (17) .…”