ISAKOS: 2019 Congress in Cancun, Mexico
ISAKOS

2019 ISAKOS Biennial Congress ePoster #1012

 

Age-Related Differences of Neuronal Structures within the Posterior Horn of the Medial and Lateral Meniscus

Theresa Diermeier, MD, Munich, Bavaria GERMANY
Stefan Milz, MD, Prof., Munich, Bavaria GERMANY
Elmar Herbst, MD, PhD, M√ľnster GERMANY
Andreas B. Imhoff, MD, Prof., Munich, Bavaria GERMANY
Andrea E. Achtnich, MD, Munich GERMANY

Department of Sportorthopedic, Klinikum rechts der Isar, Technical University Munich, Munich, Bavaria, GERMANY

FDA Status Not Applicable

Summary

Neurons and mechanoreceptors are found more often in the upper part of the parameniscal synovia and red-red zone of the posterior horn of the lateral meniscus compared to the medial. No age-related differences were found.

Abstract

In recent years special interest in posterior horns of medial (PMM) and lateral meniscus (PLM) raised, due to their influence on knee stability. The meniscofemoral ligaments and the attachment of the meniscus border to the knee joint capsule (ramp-lesion) contribute to knee stability in cases of anterior cruciate ligament deficiency. Yet, in clinical practice, meniscus injuries exist which leave patients with horizontal tears without signs of mechanical deficits, but increased pain levels. Although nociceptive and proprioceptive neuronal structures within the meniscus are described, a topographic, age-related description of neuronal structures within the PLM and PMM is lacking. Therefore, the purpose of the present study was to investigate specific age-related innervation patterns at the level of the posterior horns of the medial and lateral human meniscus samples as correlate of influence of knee stability.

Material And Methods

The study was carried out on 18 PLM and 11 PMM with a mean donor age of 50,4 (Range 24,2 - 78,0). Cryosections of the posterior horns and the neighboring capsular tissue of the medial and lateral meniscus, near to the anchorage of the posterior root were labelled with a panel of antibodies directed against various neuronal structures. Antibodies S100 and GFAP were used as markers for Schwan cells while antibodies against RT97 and SMI 32 were used to detect the presence of neurofilaments. Labelling with an antibody against acid sensing channel 2 (ASIC 2) was conducted due to its association with mechanosensory neurons and mechanoreceptors.

Results

Neuronal structures were identified through the characteristic histological morphology and with the aid of S100 and RT 97 labelling. Most positive results are situated in the PML and PMM at the upper part of the synovial fold and in the outer (red-red) zone of the meniscus. During dissection of the fresh tissue a tiny blood vessel can be frequently detected in this region of the joint capsule.
GFAP and ASIC positive neuronal structure were detected in nearly every PLM in the perimeniscal synovia and the red-red zone. In contrast ASIC 2 was only evident in the parameniscal synovia of the PMM, whereas GFAP was visible in both. SMI 32 was only evident in the red-red Zone of the PLM and PMM near to the accompanying blood vessels. Mechanoreceptors of different types were more apparent in the PLM compared to PMM, but only in the synovial fold and infrequent in the red-red zone. ASIC 2 was slightly more often positive in samples from elderly donors.

Conclusion

In contrast to recent literature neurons and mechanoreceptors were found predominantly within the upper part of the parameniscal synovia and red-red zone of the PLM. In contrast in PMM less often mechanoreceptors were detected. The other neuronal structures (RT97, GFAP, S100) were only evident in this area and most likely are sensory neuronal structures involved in pain reception and transmission. No signs of neuronal structures were found within the dense, fibrous inner parts of the meniscus body. No age related differences between neuronal structures in the PLM or PMM were determined.