The sensory innervation of the anterior cruciate ligament (ligamentum cruciatum anterius) of the human knee joint was studied by light- and electron microscopy. The connective tissue between the synovial membrane and the cruciate ligament contains small Ruffini corpuscles and lamellar corpuscles with several inner cores. The connective tissue septa between the individual fascicles of the cruciate ligament contain Ruffini corpuscles and free nerve endings. The free nerve endings are innervated by C-fibres and myelinated A-delta fibres. The afferent axons of Ruffini corpuscles are myelinated and measure 4-6 microns in diameter, those of the lamellar corpuscles with several inner cores measure about 6 microns in diameter. It is discussed, whether these receptors of the anterior cruciate ligament may influence the muscle tone via polysynaptic reflexes.

Tear of the anterior cruciate ligament (ACL) secondary to knee sprain injury is also quite common among children and adolescents. Whether reconstruction is indicated and which technique should be employed is still controversial. The debate focuses on the possible risk of growth plate damages due to intraarticular operative reconstruction techniques. For more details on benefit and risks of operative stabilization, our clinic's large number of surgical results was to be evaluated retrospectively. In a total of 437 knee joint arthroscopies performed between 1982 and 1992 in children and adolescents with open physes, aged 3-16 years, 63 surgical repair/reconstructions according to an algorithm were carried out. The average age at surgery was 13.8 years. Follow-up an average 6.5 years after the operation consisted of clinical and radiological examination, Lysholm, Tegner, and IKDC scores. This report focuses on intraarticular ligament reconstruction methods. Forty-four patients could be followed up, comprising of five reinsertions, ten internal fixations, 15 cases semitendinosus tendon (ST) augmentations, and 14 primary reconstructions with the middle one-third of the patellar tendon (PT). In every ST and PT case, transtibial and transfemoral tunnels were drilled. The clinical stability examination was supplemented by KT-1000 arthrometer measurements and radiography in two planes. Averaged for all surgical techniques, good and very good results were obtained in over 75% of cases. There were no major growth defects and rarely signs of osteoarthrosis. According to literature, conservative treatment of ACL tears and even primary ACL repair is not infrequently followed by re-ruptures. Therefore, reconstruction is the preferred procedure for patients aged 12 years or more. As most authors hesitate to possibly block the physes by obtaining and anchoring patellar tendon grafts, the ST should be preferred. This study demonstrates in a large number of ACL stabilizations, despite transepiphyseal drilling and grafting, very good stabilization is achieved, but no growth defects have to be expected.

The innervation of 21 human anterior cruciate ligaments (ACL) obtained at autopsy or during operation was studied by light microscopy. Nerves and nerve endings were found in the synovium and interfascicular connective tissue. The nerves were myelinated and/or unmyelinated and had terminal nerve structures with free nerve endings which provide nociception and supply the blood vessels, Ruffini corpuscles and Pacini corpuscles, which are mechanoreceptors in the ligaments.

Within a 3-year period (1985-1988), 60 children and adolescents with knee injuries sustained mainly while skiing or playing football (soccer) underwent clinical examination, X-radiography and arthroscopy. Nearly all the patients still had open epiphyseal plates in the knee region. Arthroscopy revealed more severe intra-articular trauma than had been suspected on the basis of clinical findings. The skiing injuries most commonly involved anterior cruciate ligament tears, whereas injuries of the patellar retinaculum and medial meniscus lesions predominated in soccer injuries. On comparison with arthroscopic diagnosis, clinical diagnosis was erroneous in about 45%. The most common mistaken clinical diagnosis was "medial meniscus tear". Of the 60 knee joints subjected to arthroscopy, 40 were severely enough injured to warrant surgery. Only one had normal intra-articular findings. The study demonstrates that children and adolescents can suffer knee trauma requiring surgery, despite open growth plates. Downhill skiing and soccer are particularly risky sports in this respect. Therefore, sports injuries involving haemarthrosis are clearly an indication for arthroscopy, even in childhood and adolescence. Arthroscopy enables early identification of the type and extent of intra-articular trauma and subsequent early initiation of appropriate therapy.

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.