Mechanoreceptors observed in a ligamentous structure between the posterior horn of the lateral meniscus and the anterior cruciate ligament.

PURPOSE: A histological study of a structure between the posterior horn of the lateral meniscus and the anterior cruciate ligament. METHODS: Bilateral fresh-frozen cadaveric knees of two male donors (age 71 and 76 years) with no history of prior knee injury were examined. All dissections were performed by one experienced orthopaedic surgeon. Haematoxylin and Eosin staining was used to reveal tissue morphology. Goldner trichrome staining was used to evaluate the connective tissue. S100 and PGP 9.5 labelling were used for immunohistochemical analysis. RESULTS: In all cadaveric knees, a structure between the posterior horn of the lateral meniscus and the anterior cruciate ligament was identified. Histological analysis confirmed the ligamentous nature of this structure. Furthermore, Golgi tendon organs were observed within the ligamentous structure. CONCLUSION: This is the first study showing the presence of mechanoreceptors within the ligamentous structure between the posterior horn of the lateral meniscus and the anterior cruciate ligament. The ligamentous structure could contribute to stability of the knee by providing proprioceptive input, while preservation of the ligamentous structure might ensure a better functional outcome after surgery.

An anatomical examination of iatrogenic nerve injury during inside out meniscus repair with flexion and extension of the knee.

BACKGROUND: In this study, we aim to assess the safe, risky and high-risky zones by measuring the proximity of the needles to the peroneal and saphenous nerves in millimeters for the repair of tears of the anterior, middle and posterior horns of the medial and lateral menisci at flexion and extension position during inside-out repair technique. METHODS: First, a cadaveric study was conducted on 10 cadaver knees in which both (lateral and medial) menisci were divided into anterior, corpus and posterior with the longitudinal tear simulating in each section. The next phase involved the suture of the simulated tears of the menisci while the knee was at 90° of flexion and full extension. Finally, the distance from the exit points of the K-wire being inserted through meniscal anterior, corpus and posterior tears to the aforementioned nerves was measured with a digital caliper. RESULTS: The distance between K-wire exit points and neurovascular structures concerning corpus and anterior horn tear repair of both menisci were considered far away and not included. However, closer posterior menisci measurements were taken to avoid the risk of iatrogenic nerve injury. The measured distances for lateral meniscus posterior tears were recorded 11±5.2 mm at 90° of flexion and 8±4.5 mm at extension, whereas those recorded 17.3±5.7 mm at 90° of flexion and 13.7±4.7 mm at extension for medial meniscus. These variables were evaluated statistically using a paired t-test; the mean of t value was not considered statistically significant. CONCLUSION: Our results show that the inside-out technique at knee flexion is safe even in the posterior meniscus tears. However, safety distance can be increased with the higher flexion degrees of the knee. Lastly, in posterior meniscal tear repair, we recommend either retractor assisted mini-open technique at knee flexion, or all-inside suture technique, to avoid nerve injury risk in this zone. Although many surgeons do not prefer inside-out techniques for posterior menisci tears, inside-out posterior meniscal repair of both menisci is as safe as an all-inside technique using retractor assisted mini-open technique with the knee at higher than 90° flexion.

Innervation of nociceptors in intact human menisci along the longitudinal axis: semi-quantitative histological evaluation and clinical implications.

BACKGROUND: The mechanism of pain after meniscus injury remains unknown. After injury, some individuals suffered from acute pain, while others suffer from delayed pain. A precise nociceptor distribution pattern may provide the answer to this question. METHODS: Twenty-two intact menisci (paired medial and lateral menisci) were obtained from 11 patients with a mean age of 28.45 years. All menisci were sectioned into five parts: the anterior horn, anterior body, middle body, posterior body, and posterior horn. Two paired menisci were stained by a modified gold chloride method. All other specimens were stained by H&E staining and were subjected to immunohistochemical staining to detect substance-P (SP). Under a microscope, measurements were made in 10 consecutive visual areas at 400x magnification. SP-positive fibres were determined using a three-grade scale, and the mean number of SP-positive fibres was assessed. RESULTS: Nerve fibres and nociceptors stained by H&E and modified gold chloride were found mainly in the vascular outer third of the menisci as observed under a microscope; the positive area was wider in the anterior and posterior horns. There were more SP+ fibres in the anterior horn and posterior horn than in the anterior body, middle body, or posterior body (p < 0.05). Regarding the bodies, the mean number of substance-P fibres was greater in the anterior body or posterior body than in the middle area (p < 0.05). No significant differences were found between the number of substance-P nerve fibres in the anterior horn vs the posterior horn or in the anterior body vs the posterior body of all menisci (p > 0.05). No significant differences were observed in the same location between the paired medial and lateral menisci in all areas of the menisci (p > 0.05). CONCLUSION: The density of nociceptors decreased along the longitudinal axis of the meniscus from both horns to the middle part of the body, which may guide future diagnostic methods and rehabilitation protocols.

Cardiac arrest in a patient with anterior fascicular block after administration of dexmedetomidine with spinal anesthesia: A case report.

BACKGROUND: Dexmedetomidine is a sedative and analgesic agent that is administered intravenously as an adjunct to spinal anesthesia. It does not suppress the respiratory system significantly, but has adverse effects on the cardiovascular system, for example, bradycardia and hypotension. We here report a patient who underwent cardiac arrest during spinal anesthesia after intravenous infusion of dexmedetomidine. METHODS: A 57-year-old woman with no significant medical history underwent spinal anesthesia for arthroscopic meniscus resection after rupturing the right knee meniscus. Preoperative electrocardiogram revealed sinus bradycardia (54 beats/min) and a left anterior fascicular block. Spinal anesthesia was performed with 11 mg of 0.5% heavy bupivacaine, and the upper level of sensory loss was at T6. Dexmedetomidine infusion was planned at a loading dose of 1.0 mcg kg min over 10 minutes, followed by 0.7 mcg kg min intravenously, as a sedative. Two minutes after dexmedetomidine injection, her heart rate decreased to 31 beats/min and asystole was observed within 10 seconds. RESULTS: After a few minutes of cardiopulmonary resuscitation, spontaneous circulation returned and surgery was completed under general anesthesia. The patient was discharged, and experienced no complications. CONCLUSION: Dexmedetomidine can decrease blood pressure and heart rate, and may cause asystole in some cases. We suggest that dexmedetomidine should be carefully administered under close observation when the parasympathetic nerve system is activated during spinal anesthesia.

Nociceptive and sympathetic innervations in the abaxial part of the cranial horn of the equine medial meniscus: an immunohistochemical approach.

In athletic horses, diseases leading to lameness are of great importance due to the loss of performance and the resultant economic concerns. Although stifle lesions are frequent in the hindlimb, due to the large size and complexity of the joint, and although meniscal tears have been identified as the most common soft tissue injuries in this joint, little is known about the mechanism that causes the painful sensation and thus the lameness. The aim of our study was to highlight any peripheral fibres involved in meniscal nociception in five macroscopically sound cranial horns of the equine medial meniscus, which has been one of the most common sites reported for equine meniscal injuries. Immunohistochemical stainings were performed using antibodies against Substance P in order to identify nociceptive fibres; against tyrosine hydroxylase for detecting postganglionic sympathetic fibres; and against glial fibrillary acidic proteins in order to identify Schwann cells. Our work highlights for the first time the presence of nociceptive and sympathetic fibres in equine menisci. They were found in the abaxial part of the cranial horn of the equine medial meniscus. This study suggests that when the abaxial part is injured, the meniscus itself could be the source of pain. These findings could provide a better understanding of the clinical presentation of horses with meniscal injury and contribute towards improving therapeutic strategies to alleviate pain in cases of equine meniscal injury.

Mechanoreceptors in the Anterior Horn of the Equine Medial Meniscus: an Immunohistochemical Approach.

Lameness due to stifle and especially meniscal lesions is frequent in equine species. In humans, mechanoreceptors involved in proprioceptive function are well studied. Given the high incidence of meniscal injuries in horses, and the lack of information concerning them in equine menisci, our objective was to study these corpuscles in six healthy anterior horns of the equine medial meniscus, which is the most common localisation reported for equine meniscal injuries. Immunohistochemical stainings were performed using antibodies against high molecular weight neurofilaments and glial fibrillary acidic proteins. From a purely fundamental point of view, our work highlights for the first time the presence of Ruffini, Pacini and Golgi corpuscles in equine meniscus. They were found, isolated or in clusters and always located at the vicinity of blood vessels, at the level of the anterior horn of the equine medial meniscus. This morphological approach could serve as a basis for clinical studies, to evaluate the impact of these corpuscles on the poor sportive prognosis in equine meniscal tears.

Increased vascular penetration and nerve growth in the meniscus: a potential source of pain in osteoarthritis.

OBJECTIVES: Meniscal damage is a recognised feature of knee osteoarthritis (OA), although its clinical relevance remains uncertain. This study describes vascular penetration and nerve growth in human menisci, providing a potential mechanism for the genesis of pain in knee OA. METHODS: Menisci obtained post mortem were screened on the basis of high or low macroscopic tibiofemoral chondropathy as a measure of the presence and degree of OA. Forty cases (20 per group) were selected for the study of meniscal vascularity, and 16 (eight per group) for the study of meniscal innervation. Antibodies directed against α-actin and calcitonin gene-related peptide (CGRP) were used to localise blood vessels and nerves by histochemistry. Image analysis was used to compare vascular and nerve densities between groups. Data are presented as median (IQR). RESULTS: Menisci from knees with high chondropathy displayed degeneration of collagen bundles in their outer regions, which were more vascular than the inner regions, with an abrupt decrease in vascularity at the fibrocartilage junction. Vascular densities were increased in menisci from the high compared with low chondropathy group both in the synovium (3.8% (IQR 2.6-5.2), 2.0% (IQR 1.4-2.9), p=0.002) and at the fibrocartilage junction (2.3% (IQR 1.7-3.1), 1.1% (IQR 0.8-1.9), p=0.003), with a greater density of perivascular sensory nerve profiles in the outer region (high chondropathy group, 144 nerve profiles/mm(2) (IQR 134-189); low chondropathy group, 119 nerve profiles/mm(2) (IQR 104-144), p=0.049). CONCLUSION: Tibiofemoral chondropathy is associated with altered matrix structure, increased vascular penetration, and increased sensory nerve densities in the medial meniscus. The authors suggest therefore that angiogenesis and associated sensory nerve growth in menisci may contribute to pain in knee OA.

Saphenous nerve block is an effective regional technique for post-menisectomy pain.

In this study we have evaluated the post menisectomy pain relief offered by Saphenous nerve block. This study was planned on 40 patients with a pre-operative and post operative diagnosis of medial meniscus lesion undergoing partial menisectomy arthroscopically. Patients were randomized into 2 groups where Group I received a preoperative Saphenous block while group 2 did not receive a peripheral block, but received 1 ml of saline as placebo injection. After blocks both groups received general anesthesia and IV patient controlled analgesia (PCA) with tramadol for post operative pain relief. Patients rest and activity pain scores were evaluated on post operative 0, 2, 4, 6, 12 and 24 h using visual analog scale (VAS). Total tramadol consumption as well as pain at rest, when weight bearing and the need for external support while walking were recorded. Group I VAS scores were statistically lower then group II during the time of observation periods at rest as well as active movement periods. Tramadol consumption through IV PCA was statistically significantly lower in group I than in group II (P < 0.05). Pain during walking measured at 24 h was significantly different with better results in group I (P < 0.001). Saphenous nerve block is used for different indications; it can also be a good analgesic method for arthroscopic interventions. We have shown it to be effective after medial partial menisectomies. According to our knowledge this report is the first one utilizing saphenous nerve block for pain after arthroscopic medial menisectomy.

Nociceptive nerve activity in an experimental model of knee joint osteoarthritis of the guinea pig: effect of intra-articular hyaluronan application.

Nociceptive impulse activity was recorded extracellularly from single A delta and C primary afferents of the guinea pig's medial articular nerve after induction of an experimental osteoarthritis in the knee joint by partial medial menisectomy and transection of the anterior cruciate ligament (PMM+TACL). Also, the analgesic effects of intra-articular hyaluronan solutions were evaluated. Healthy, PMM+TACL operated, sham-operated (opening of the joint capsule without PMM and TACL surgery) and acutely inflamed (intra-articular kaolin-carrageenan, K-C) animals were used. The stimulus protocol consisted of torque meter-controlled, standardized innocuous and noxious inward and outward rotations of the joint. This stimulus protocol of 50 s duration was repeated every 5 min for 70 min. One day, one week and three weeks after PMM+TACL, the movement-evoked discharges of A delta articular afferents were increased significantly over values found in sham-operated animals. The discharges of C fibers were significantly augmented only one week after PMM+TACL surgery. Filling of the joint cavity with a high viscosity hyaluronan solution (hylan G-F 20, Synvisc) immediately and three days after surgery reduced significantly the enhanced nerve activity observed in joint afferent fibers one day and one week after surgery. Augmentation of movement-evoked discharges in K-C acutely inflamed knee joints was similar to that observed one week after PMM+TACL. Our results indicate that in the PMM+TACL model of osteoarthritis in guinea pigs, enhancement of nociceptive responses to joint movement was primarily associated to post-surgical inflammation. Intra-articular injection of an elastoviscous hyaluronan solution reduced the augmented nerve activity.

Dorsal sural nerve conduction study in vitamin B(12) deficiency with megaloblastic anemia.

Peripheral neuropathy is frequently observed in B(12) deficiency. In spite of this, there is little knowledge about peripheral neuropathy in B(12) deficiency because the severity of clinical involvement of the central nervous system clearly outweighs signs and symptoms due to peripheral nervous system involvement. We primarily investigated peripheral neuropathy with dorsal sural conduction study, which is a new method for detection of early peripheral neuropathy, in B(12) deficiency with megaloblastic anemia. Conventional nerve conduction studies and tibial sensory-evoked potential (SEP) recording were also performed. Twenty-eight B(12)-deficient patients (15 male, 13 female, mean age 65.8 years) with megaloblastic anemia and 18 age- and sex-matched controls were included in the study. Although dorsal sural sensory nerve action potentials (SNAPs) were not recorded in 15 (54%) of 28 patients, only 9 (32%) of them were found to have polyneuropathy by conventional conduction studies. Furthermore, patients with dorsal sural SNAP had mean lower amplitude, mean longer latency, and slower velocity response when compared with controls. Twenty patients (71%) were diagnosed as having myelopathy by the combination of tibial SEP and neurological findings. Two patients whose dorsal sural SNAPs were not recorded had normal tibial SEP responses; therefore, these patients were considered to have isolated peripheral neuropathy. As a result, we conclude that dorsal sural nerve conduction study is a reliable method for detection of early peripheral neuropathy in B(12) deficiency.

Evaluation of the neurosensory function of the medial meniscus in humans.

PURPOSE: Menisci are known to have receptors mainly concentrated at the anterior and posterior horns. Although they are purported to send afferent impulses to the central nervous system, this function has not been thoroughly evaluated. The purpose of the study was to investigate whether stimulation of the menisci initiates a cortical response. The reaction of the end organ to the reflex arc is also evaluated. TYPE OF STUDY: Prospective case series. METHODS: Fourteen patients with normal medial menisci were included in the study. Different parts of the knee joint (the posterior horn and the body of the medial meniscus, the medial femoral condyle, the capsule, and the joint space) were electrically stimulated by a probe during arthroscopy. The cortical response was monitored with somatosensory-evoked potentials (SEPs). The compound muscle action potentials (CMAPs) of the semimembranosus, quadriceps, and biceps femoris muscles were also monitored with electroneuromyography (ENMG). RESULTS: Among the stimulated parts, only the posterior horn of the meniscus produced cortical responses. No response was obtained with stimulation of the medial femoral condyle, the body of the medial meniscus, the capsule, or the joint space. Stimulation of the posterior horn of the medial meniscus produced a measurable amount of CMAP latency for the semimembranosus muscle, but not for the quadriceps and biceps femoris muscles. CONCLUSIONS: Stimulation of the posterior horn of the medial meniscus produces reproducible cortical SEPs and results in ENMG-verified response of the semimembranosus muscle where no response of the semimembranosus muscle is detected with stimulation of the other parts of the knee. CLINICAL RELEVANCE: The knowledge that only the horns of the medial meniscus have mechanoreceptors in the medial compartment of the knee helps to understand patients' signs and symptoms in medial compartment disease.

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

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.

Los fibrocartílagos de la articulación femoro-tibial. Morfología y función / The knee joint menisci: morphology and function

Los meniscos de la articulación de la rodilla son estructuras fundamentales en la mecánica articular pues actúan en la distribución de las solicitaciones; la absorción de cargas; la regulación de la lubricación y en la propiocepción y estabilidad articular. Los meniscos son estructuras intermedias entre el tejido fibroso y el cartílago con fibras de colágeno dispuestas con distintas orientaciones para permitir un comportamiento mecánico adecuado. Tienen una pobre vascularización e inervación limitada al tercio externo y a los cuernos anterior y posterior aunque la superficie de la zona avascular presenta unos poros que sirven de entrada a los nutrientes del líquido synovial (AU)

The meniscus of the knee joint are fundamental structures in the articular mechanic because they act in the distribution of stresses; the absorption of loadings; the regulation of lubrication and in the proprioception and articular stability. The meniscus are intermediate structures between the fibrous tissue and the cartilage with collagen fibres disposed with different orientations to allow an appropriate mechanical behavior. They have a poor vascularization and innervation limited to the external third (vascular or red area) and the anterior and posterior horns although the avascular or white area surface presents some pores that serves as entrance to the nutriente of the synovial fluid (AU)

Neural and vascular anatomy of the menisci of the human knee.

STUDY DESIGN: Review of literature. OBJECTIVES: To review the general anatomy, vascular anatomy, healing potential, neural anatomy, and sensory functions of the menisci of the human knee. BACKGROUND: Recent research has revealed important roles and functions of the menisci of the human knee. METHODS AND MEASURES: A Medline search was performed using the following title and key words: menisci, meniscus, meniscal, vascular, blood, neural, nerve, anatomy, healing, sensory, mechanoreceptors, proprioception, nociceptors, surgery, meniscectomy, repair, and rehabilitation. The references from each article obtained were then reviewed in order to find additional articles not already located through the Medline search. RESULTS: In adults, the blood supply to the menisci of the knee reaches the outer 10% to 33% of the body of the menisci. This portion of the menisci is capable of inflammation, repair, and remodeling. Neural innervation with nociceptors and type I, II, and III mechanoreceptors reaches the outer 66% of the body of the menisci. The anterior and posterior horns of the menisci have a rich supply of both blood vessels and nerves. CONCLUSIONS: The menisci of the human knee are an important source of proprioceptive information regarding the position, direction, velocity, and acceleration and deceleration of the knee. Rehabilitation following injury or surgery to the menisci of the knee should, therefore, incorporate a proprioceptive retraining program that respects both the abilities and inabilities of different portions of the menisci to follow through with repair and remodeling.

Evaluation of the anatomy of the common peroneal nerve. Defining nerve-at-risk in arthroscopically assisted lateral meniscus repair.

A two-part study was undertaken to clarify the anatomy of the common peroneal nerve at the level of the lateral joint line and risk factors associated with arthroscopically assisted inside-out lateral meniscus repair. In part I, 70 legs in 35 preserved cadavera were dissected to evaluate the relevant anatomy of the common peroneal nerve; 7 (10%) manifested division of the common peroneal nerve into deep and superficial branches proximal to the knee joint. A cutaneous branch not previously described in the literature emanated from the common peroneal trunk in 21 of the legs (30%). In part II, arthroscopically assisted inside-out lateral meniscus repair was performed on 10 fresh-frozen cadaveric knees. Divergence between suture arms increased as suture position was sequentially posterior. Capture of a nerve branch occurred in 2 knees (20%) when posterior retraction was not used. Nerve involvement was eliminated when a retractor was employed. There was significant anatomic variability in the course and branching pattern of the common peroneal nerve at the level of the lateral joint line. During arthroscopically assisted inside-out lateral meniscus repair, risk of injuring the peroneal nerve was related to suture position because of the proximity of anatomic structures and the tendency for suture divergence with soft tissue tethering.

Medial meniscal cyst imitating a tumor, with compression of the saphenous nerve.

We report a case of large medial meniscal cyst responsible for symptomatic saphenous nerve compression in a 49-year-old male with a history of mild trauma to the affected knee. We are not aware of any similar cases in the literature. The lesion was delineated by ultrasonography and even more clearly by magnetic resonance imaging. At surgery, the saphenous nerve was seen to be displaced by the cyst. Cystectomy and partial meniscectomy were performed. The outcome was favorable.

Dermatitis complicating saphenous nerve injury after arthroscopic debridement of a medial meniscal cyst.

We report the case of a patient who developed hypesthesia in the distribution of the saphenous nerve after an arthroscopic debridement of a medial meniscal cyst. Dermatitis developed in the area of the hypesthesia 3 months later, Both complications responded to symptomatic treatment. A review of the literature confirms the unusual nature of these complications.

The attachments of the rabbit medial meniscus. A morphological investigation using image analysis and immunohistochemistry.

In the search for a suitable experimental model the rabbit has increasingly been used for investigations on the meniscus. The present study focused on the morphology and innervation of the anterior and posterior medial meniscal attachments in adolescent and adult rabbits in comparison with man. Grossly, the posterior attachment has a similar anatomical position as in man, but the anterior is inserted more anteriorly and more laterally, with a long ligament-like structure between the osseous insertion and the meniscal horn. As in man, the attachment resembles a ligamentous insertion and contains zones of uncalcified and calcified fibrocartilage and subchondral bone. The proportion of the calcified cartilaginous zone in the attachment increases during maturation as in articular cartilage. Nerve fibres were found not only at the horns but also in the uncalcified and calcified fibrocartilaginous zones and the underlying bone. The differences between rabbit and human menisci should be borne in mind when interpreting data from animal experiments.

Distribution of substance P and calcitonin gene related peptide immunoreactivity in the normal feline knee.

OBJECTIVE: There is substantial evidence that the intraarticular release of the neuropeptides substance P (SP) and/or calcitonin gene related peptide (CGRP) can contribute to the development and perpetuation of joint inflammation. However, there is a paucity of data examining whether SP and CGRP containing fibers are present in articular tissues other than synovium. Our objective was to comprehensively examine all innervated tissues in the normal feline knee for the presence of these neuropeptides. METHODS: The normal right knee joints from 5 cats were harvested and dissected into 10 regions. These regions included the cruciate and collateral ligaments, menisci, fat pad and synovium, capsule and popliteus tendon. Each area was examined for the immunocytochemical presence of SP and CGRP. RESULTS: Nerve fibers immunoreactive (Ir) for SP or CGRP were found in all of the joint tissues examined. In general, Both SP-Ir and CGRP-Ir nerve fibers were most often associated with blood vessels. However, there were "free" SP and CGRP fibers present in all 10 articular structures which were not associated with any vascular profiles. CONCLUSION: Our data demonstrate that articular SP and CGRP-Ir fibers are not limited to the synovium. Both neuropeptides are widely distributed to all joint tissues except articular cartilage, which is devoid of neural tissue. These findings, in conjunction with an increasing appreciation of the functional interrelationship between SP and CGRP, argue cogently for consideration of the effects generated by nonsynovial sources of SP and CGRP when assessing the role of these neuropeptides in both normal joint function and in articular inflammatory processes.

[Clinical and sonographic meniscus diagnosis]. / Klinische und sonographische Meniskusdiagnostik.

Clinical examination still plays an important role in diagnosing meniscal tears. The types of sensitive nerves in the knee joint are responsible for nonspecific pain, which is often correlated with too little specificity in meniscal tests. Ultrasound examination of meniscal structures of the knee joint has been debated extensively in recent years. Criticism of this noninvasive technique was due to small patient groups, improper technical and inaccurate manual standards. Since 1988 ultrasound of the tibial meniscus has become a standard technique in our Department of Orthopaedic Surgery with defined criteria of the intersecting plane and evaluation of ultrasound images. A prospective follow-up study during 6/1988 and 5/1993 including 1186 ultrasound examinations before arthroscopy, was performed. The sensitivity for ultrasound of the lateral meniscus was 58% and for the medial meniscus 83%. Specificity with 98% for the lateral and 90% for the medial meniscus was good. Sonographic detection of meniscal tears depends on the shape and location of meniscal tears. This has been shown by experimental studies in cadavers. A follow-up study including 113 knee joints was performed to prove the value of clinical and ultrasound examination in relation to arthroscopy. The sensitivity of sonography for medial meniscus was 81% and 40% for the lateral meniscus. Although the sensitivity of the clinical examination was 81% (medial) and 47% (lateral), the low specificity of 70% for meniscus tears indicated that it was because of false-positive clinical evaluation of meniscal disorders. In young patients with reflectory muscle spasm and those with acute trauma of the knee joint, clinical examination of the meniscal structures showed poor results. In these cases, too, ultrasound examination showed advantages. Ultrasound of the knee joint meniscus is noninvasive, reproducible and low cost. In cases of uncertain clinical results, ultrasound offers a good opportunity to visualize meniscal disorders.