A study of the synovial and ligamentous structure of the anterior cruciate ligament

Abstract

The synovial and ligamentous structure of 16 human anterior cruciate ligaments (ACL), removed at autopsy, were examined by light microscopy with special regard to their topographical relationships. The soft tissue support of the ACL consists of fibrous, areolar and areolo-adipose synovial tissue. The subsynovial layer comprises a tight fibrous peripheral part and an element of loose connective tissue containing some tight connective tissue strands, vessels and nerves. The collagenous ligamentous part of the ACL is the proper functional tissue and contains approximately 1500 fascicles measuring an average of 250 micron in diameter. These fascicles are composed of bundles of collagen fibres, fibrocytes and deposits of proteoglycans. The synovial and ligamentous structures are attached by the second part of the subsynovial layer, which radiates into the ligamentous tissue and envelops the fascicles like a sheath. By this means the biological connection between these two structures is guaranteed. The relevance of these findings to operative reconstruction of recent ligamentous injuries is discussed.

Innervation of the anterior cruciate ligament

“…A fibrous synovial layer on the anterior surface of the ACL, an areolar synovium on the posterior surface and an areolo-adipose synovium on the posterolateral aspect of the A C L can be distinguished [11]. We were able to establish that the largest numbers of nerves with a diameter of up to 250 ~tm, lie in the areolo-adipose synovium.…”

“…As early as 1904 Fick gave an account of the nerves in the knee and A C L [3] which others elaQffprint requests to: J. Haus borated later [5,[11][12][13]18]: The A C L is well supplied with nerves. Nerve-ending corpuscles have been described [7,17,18,21], but the structures shown needed to be interpreted with great imagination by the reader.…”

Intraarticular Ligament Degeneration Is Interrelated with Cartilage and Bone Destruction in Osteoarthritis

“…These are usually twisted in the ACL [34]. The ligament is surrounded by the epiligament, and then it is covered by the synovial layer [34,35] (Figure 1C). The synovium, especially near the attachment points of the ACL contains also many of the mechanoreceptors observed in the ACL represented by free nerve endings, Ruffini corpuscles, Pacinian corpuscles, and Golgi tendon bodies [28].…”

“…This synovitis score embraces typical features of synovitis and includes assessing the enlargement of the lining layer, cellular density of synovial stroma, and leukocyte infiltration by giving each a score of 0–3 points and sum them [83,84] (Figure 3). Due to the intimate interrelation of the ACL and the covering synovial layer [35] supplying it with blood, synovitis becomes highly relevant in ACL degeneration. Using the above mentioned score, we confirmed a significant correlation between synovitis and ACL degeneration in human samples harvested from OA and non-OA patients [13] that is in agreement with a recent study in dogs [85].…”

Biology and augmentation of tendon-bone insertion repair

“…These cells release cytokines and growth factors including TGF-beta and PDGF. There is an ingrowth of blood vessels and nerves as a result of hypoxia or growth factor stimulation[45,46]. The stem cells proliferate and differentiate.…”