Arthroscopic studies of variants of the anterior horn of the medial meniscus

The objective of this study was to arthroscopically analyse the morphology and dynamics of variants of the anterior horn of the medial meniscus of the knee (VAMM) and to then consider the pathological significance of these variants. VAMM was defined as knees in which the anterior horn of the medial meniscus is not attached to the tibia. Between April 1992 and March 1995, arthroscopy was performed on 953 knees of 903 patients. At the time of this examination, observation and probing were performed to determine the condition of the synovium, the synovial plica, the cartilage in all compartments, the meniscus, the cruciate ligaments, and the popliteal tendon. In particular, detailed examination was made of the anterior horn of the medial meniscus with regard to the point of insertion to the tibia and the degree of movement in knee flexion/ extension. Cases of VAMM diagnosed on the basis of the arthroscopic findings were classified into the following four categories: the ACL (anterior cruciate ligament) type, where the anterior horn of the medial meniscus was attached to the ACL; the transverse ligament type, where the anterior horn of the medial meniscus was attached to the transverse ligament; the coronary ligament type, where the anterior horn of the medial meniscus was attached to the coronary ligament; and the infrapatellar fold type, where the anterior horn of the medial meniscus was attached to the infrapatellar synovial fold. These patients were then analyzed with regard to the arthroscopic findings and the intra-articular lesions other than VAMM. In 98 (10.9%) of the total patients, 103 knees were classified as VAMM. Classification of those 103 knees using the above criteria showed 39 ACL type knees, 51 transverse ligament type knees, 11 coronary ligament type knees, and 2 infrapatellar fold type knees. The arthroscopic findings indicated that the anterior horn of the medial meniscus was not attached directly to the tibia in any of these knees. Probing and flexion/extension of the knee revealed hypermobility at the anterior horn of the medial meniscus. In this study, anterior knee pain syndrome was diagnosed in 12 (11.7%) of the 103 VAMM knees. In addition, there was no clear history of trauma in 20 of 23 knees found to have an isolated medial meniscus tear. In these cases, even detailed arthroscopic observation proved the causes of the symptoms or injury. On the basis of these findings, we surmised that the anterior portion shows hypermobility at the time of flexion/extension of the knee, regardless of the type of VAMM. In this study, we discussed the possibility that the existence of VAMM may become the cause of pain or injury to the meniscus.     

膝外下动脉与外侧半月板解剖关系的MRI研究

目的探讨膝外下动脉与外侧半月板解剖关系的MRI表现及其可能的临床意义。方法先通过2例膝关节新鲜冰冻尸体标本大体上观察膝外下动脉的走行及其与外侧半月板的关系。随意选择2010年3～6月门诊膝关节MRI检查100例,以MRI冠状面的腘肌腱层为标准,向前测量5～7个层面,测量膝外下动脉与外侧半月板之间的垂直及水平距离。结果 100例MRI冠状面显示膝外下动脉的走行相对固定,与膝尸体标本的大体观察一致。在腘肌腱层,98%的膝外下动脉开始贴近外侧半月板,位于半月板下缘或下方;随着层面向前,膝外下动脉紧贴外侧半月板自后下向前上走行;在第5层（约半月板前体部）,89%的膝外下动脉位于外侧半月板中部及以上;在第7层（约半月板前角及脂肪垫区）,100%的膝外下动脉位于半月板上方;在第1～5层,膝外下动脉与外侧半月板的平均水平距离为0.8 mm（0～3 mm）。结论膝外下动脉与外侧半月板（尤其是体部）的距离非常接近,在关节镜外侧半月板手术时容易损伤此动脉,增加对于这一解剖的认识,可能减少术后并发症。     

Spatial organization of types I and II collagen in the canine meniscus.

The meniscus of the knee joint is a fibrocartilage mainly composed of type I collagen and smaller amounts of type II collagen. The distribution of type II collagen in the canine meniscus and its spatial relationship to type I collagen was examined by immunohistochemistry and confocal microscopy. Dorsal and coronal slices of the mid-section of medial and lateral menisci from the knee joints of skeletally mature dogs were predigested with Streptomyces hyaluronate lyase and bacterial Protease enzyme XXIV. Monoclonal antibodies against type I collagen (CP17L) and type II collagen (II-II6B3) and an anti-type II collagen polyclonal antibody (AB759) were employed. The staining for type II collagen in the extracellular matrix of hyaline articular cartilage was diffuse without any identifiable spatial organization. In striking contrast, type II collagen in the fibrocartilage of the meniscus stained as an organized network. Type II collagen was distributed throughout the meniscus with the exception of the outer zone containing the blood vessels. Coronal and dorsal staining of the meniscus showed bundles of circumferential fibrils of type I that colocalized with type II collagen in specific sites. These bundles were enwrapped in a second organizational fibrillar system of types I and II collagen that also colocalized. Bundles of circumferential fibrils appeared in cross-section in coronal sections as dots within the interstitial spaces framed by the network of types I and II collagen of the second system. Confocal overlays showed that types I and II collagens were superimposed, suggesting a close spatial proximity between the two collagens. The cells were confined to the types I and II collagen fibrils that enwrapped the bundles. A striking feature of the radial tie fibers was patches of type II collagen without colocalized type I collagen. Our study reveals a unique network of type II collagen in fibrocartilage of the meniscus that serves as a morphological distinction between fibro- and hyaline cartilage.     

Soft tissue injury of the knee after tibial plateau fractures

The purpose of this study was to document the pattern of ligament and meniscal injuries that occur during high-energy tibial plateau fractures. One hundred three patients with fractures due to high-energy mechanisms were evaluated with knee magnetic resonance imaging (MRI). All studies were read by a single musculoskeletal radiologist who was blinded to surgical and physical exam findings. Pertinent demographic information was obtained. There were 66 patients with AO/OTA type 41C fractures and 37 patients with AO/OTA type 41B fractures. Seventy-three (71%) patients tore at least one major ligament group, and 55 (53%) patients tore multiple ligaments. There were 53 torn ligaments in AO/OTA type 41C fractures (80%) compared with 20 torn ligaments in AO/OTA type 41B fractures (54%) (p < 0.001, Fisher's exact test). Using Schatzker's classification, we found the following correlation: type I, 13 fractures with 6 ligaments (46%); type II, 11 fractures with 5 ligaments (45%); type IV, 13 fractures with 9 ligaments (69%); type V, 13 fractures with 11 ligaments (85%); and type VI, 53 fractures with 42 ligaments (79%). A significant difference exists between the groups regarding the incidence of ligament injuries (p < 0.05) and also regarding high-energy (type IV, V, VI) versus low-energy (type I, II, III) fracture patterns. The incidence of knee dislocation was 32% for AO/OTA type 41B fractures and 23% for AO/OTA type 41C fractures. Knee dislocations (dislocated on presentation, bicruciate injury, or at least three ligament groups torn with a dislocatable knee) were most common in Schatzker type IV fractures (46%). Fifty patients sustained meniscus tears (49%), with 25 medial menisci and 35 lateral menisci injuries. Tibial plateau fractures frequently have important soft tissue injuries that are difficult to diagnose on physical examination. High-energy fracture patterns (AO/OTA type 41C or Schatzker type IV, V, VI) clearly have a significantly higher incidence of ligament injury, and these patients should be carefully evaluated to rule out a spontaneously reduced knee dislocation. We believe MRI scanning should be considered for tibial plateau fractures due to high-energy mechanism, allowing identification and treatment of associated soft tissue injuries.     

腘半月板纤维束损伤诊治的研究进展

腘半月板纤维束损伤在临床上相对少见,可以是单纯损伤,也可以合并前交叉韧带断裂、外侧半月板破裂等损伤。单纯腘半月板纤维束损伤常引起外侧半月板不稳定,由于其损伤缺乏特异性的症状和体征,影像学改变细微,临床上容易漏诊与误诊,及时的诊断和治疗对于预防膝关节慢性疼痛和不稳至关重要。本文从腘半月板纤维束损伤的解剖特征、生物力学、损伤机制、诊断要点及手术治疗等方面进行总结,以指导临床工作中对腘半月板纤维束损伤的诊断和治疗。     

Arthroscopic one-piece reshaping for symptomatic discoid medial meniscus with anomalous amalgamating into anterior cruciate ligament

Discoid shapes of lateral menisci are relatively common finding, whereas discoid medial menisci are less common. Discoid medial meniscus with associated anomalous variants has been reported. However, symptomatic complex tear of complete type discoid medial meniscus with anomalous blending with anterior cruciate ligament is an extremely rare pathology. A 35-year-old male was admitted to our hospital with left knee pain and loss of terminal extension for 2 years. On physical examination, the patient presented with clicking and restriction during the extension motion of the knee joint. Magnetic resonance imaging and arthroscopy indicated complex tear of complete discoid medial meniscus in association with anomalous connection between entire apical portion of discoid medial meniscus and tibial insertion portion of the anterior cruciate ligament. We obtained a successful outcome with arthroscopic resection and shaping in one-piece method using no. 11 scalpel blade.     

关节镜下盘状半月板的治疗

目的　探讨关节镜下盘状半月板的治疗方法与疗效。　方法　 37例 (37膝 )盘状半月板 ,33例行关节镜下成形术 ,4例肌腱部自关节囊缘较广泛撕裂因无法成形而行全切术。 1例自R区纵向撕裂在成形后行缝合修补术。　结果　按Ikeuchi氏膝关节评价等级 :优 19例 (5 1.4% ) ,好 13例(35 1% ) ,良 5例 (13 5 % )。　结论　关节镜下盘状半月板成形术可获得优良疗效 ,主张尽可能施行关节镜下成形术治疗盘状半月板。     

Lubricin distribution in the torn human anterior cruciate ligament and meniscus

The objective of this study was to: (1) determine the distribution of lubricin in the human torn anterior cruciate ligament (ACL) and meniscus; (2) determine the distribution of lubricin in the human intact ACL and meniscus; (3) and identify potential cellular sources of lubricin in these tissues. Ten torn ACLs and six torn menisci were obtained from surgeries; for comparison, 11 intact ACLs and 13 intact menisci were obtained from total knee replacements. Samples were formalin fixed and processed for immunohistochemical staining with a monoclonal antibody for lubricin. In torn ACLs and menisci, lubricin was generally found as a discrete layer covering the torn surface. No surface lubricin staining was found on the transected edges produced during excision. Lubricin was also found on the native surfaces of intact ACLs and menisci. In all tissues, lubricin was found in the matrix and intracellularly. The surface layer of lubricin coating torn edges of ACLs and menisci may interfere with the integrative healing process needed for repair. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1916–1922, 2011     

Meniscus structure in human,sheep, and rabbit for animal models of meniscus repair

Meniscus injury is a frequently encountered clinical orthopedic issue and is epidemiologically correlated to osteoarthritis. The development of new treatments for meniscus injury is intimately related to the appropriateness of animal models for their investigation. The purpose of this study was to structurally compare human menisci to sheep and rabbit menisci to generate pertinent animal models for meniscus repair. Menisci were analyzed histologically, immunohistochemically, and by environmental scanning electron microscopy (ESEM). In all species, collagen I appeared throughout most menisci, but was absent from the inner portion of the tip in some samples. Collagen II was present throughout the inner main meniscal body, while collagen VI was found in pericellular and perivascular regions. The glycosaminoglycan‐rich inner portion of menisci was greater in area for rabbit and sheep compared to human. Cells were rounded in central regions and more fusiform at the surface, with rabbit being more cellular than sheep and human. Vascular penetration in rabbit was confined to the very outermost region (1% of meniscus length), while vessels penetrated deeper into sheep and human menisci (11–15%). ESEM revealed a lamellar collagenous structure at the articulating surfaces of sheep and human menisci that was absent in rabbit. Taken together, these data suggest that the main structural features that will influence meniscus repair—cellularity, vascularity, collagen structure—are similar in sheep and human but significantly different in rabbit, motivating the development of ovine meniscus repair models. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res     

Unusual solitary ganglion cysts of the anterior segment of the lateral meniscus

Generally, ganglion or synovial cysts have been reported to originate from numerous structures in and around the knee joint, including the anterior cruciate ligament, posterior cruciate ligament, popliteal tendon, and menisci. Nevertheless, a ganglion is not a synovial cyst and there is no synovial lining. Meniscal cysts present a subgroup of ganglion cysts that occur in association with meniscal tears. We report 2 cases of unusual meniscal cyst from the anterior segment of the lateral meniscus without any meniscal tear and discuss the possibility of their pathogenesis and treatment.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 3 (March), 2003: pp E16     

Prevention of ligament and meniscus atrophy by active joint motion in a non-weight-bearing model

This study describes the effect of active joint motion on the maintenance of ligament and meniscus mass in a non-weight-bearing model of disuse. Denervation and fixation models of immobilization have shown that resorption of isotope and atrophy of mass occurred for hard tissue (bone) and soft tissues (ligament, tendon, or meniscus). A unilateral ankle disarticulation model of disuse that maintains active knee motion without weight bearing was studied for 8 weeks in dogs that were chronically prelabeled with three different isotopes. The effects of non-weight-bearing without denervation or fixation were analyzed for the resorption of isotopes, and net atrophy of bone mass (femur or tibia) and soft-tissue mass (collateral or cruciate ligaments, menisci). A large and similar loss of all three isotopes, as well as collagen and calcium mass occurred for whole femur and tibia; this indicated that mass loss was equivalent to bone resorption and suggests little replacement with new bone. No loss of isotope or mass per whole tissue occurred for the collateral and cruciate ligaments or menisci. The strength of the femur-anterior cruciate ligament-tibia complex was analyzed by a tensile failure test when a fast rate of deformation was applied; the results did not differ qualitatively or quantitatively between control and experimental limbs. The absence of weight bearing for 8 weeks resulted in marked bone atrophy without resorption or atrophy of soft tissues, or decrease of the mechanical strength for the femur-ligament-tibia complex.     

The possibility of using carbon material in surgery of joints]

The experiments consisting in replacement of a dissected anterior cruciate ligament of the knee in rabbits with a bundle of parallel carbon fibers and a braided carbon covered with animal collagen lyophilized dura mater have been performed. Similar experiments have been performed on dogs. The lateral ligaments of the knee were also restored, longitudinally cut menisci and the Achilles tendon were sutured. The produced carbon plate and metal screws were used to fix bone fracture. The positive results of the experiments on animals with the use of carbon fibers of Polish make have proved the possibility of their employment for periarticular ligament reconstruction, suturing, Achilles tendon injuries and juxta capsular meniscus rupture. The union of bone fracture with a composite carbon plate has shown the superiority of "carbon" osteosynthesis over "metal" one. It is believed that carbon materials will be used clinically more widely.     

The popliteus tendon and its fascicles at the popliteal hiatus: gross anatomy and functional arthroscopic evaluation with and without anterior cruciate ligament deficiency

Gross anatomical dissection of the popliteus muscle, the popliteus tendon and its fascicles, and their relation to the lateral meniscus was carried out in 14 human adult cadaver knees. Videoarthroscopy through an anterolateral portal was then used to assess and document the functional integrity of the popliteus tendon and its fascicles forming the popliteal hiatus in vivo. A control group of cruciate ligament intact knees (n = 107) was compared with an anterior cruciate ligament (ACL)-deficient group (n = 68). The incidence of structural lesions of the popliteus system was 18.7% in the control knees, 95% in 40 acute ACL disruptions, and 85.7% in 28 chronic ACL-deficient knees. Functional arthroscopic evaluation of the popliteus tendon and its fascicles blending into the lateral meniscus was a valuable adjunct in assessing secondary posterolateral restraints in acute and chronic ACL-incompetent knees.     

The effects of hyaluronan on the meniscus in the anterior cruciate ligament-deficient knee

Anterior cruciate ligament (ACL) deficiency often induces meniscal tears and, ultimately, degenerative joint disease. The hypothesis of this study was that hyaluronan (HA; MW = 8 × 10⁵) may have a protective effect on the medial meniscus following a period of ACL deficiency. The animal model consisted of creating an ACL deficiency by ACL transection (ACLT) in 51 mature New Zealand white rabbits. Postoperative injections started 4 weeks after ACLT to allow the ACL deficiency to create a degenerative change in the meniscus. The first group (n = 26) was injected with HA and the second group (n = 25) was injected with vehicle (phosphate-buffered saline) in their ACL-deficient knees once a week for 5 weeks, in a protocol similar to that used clinically. At the end of the injections, the HA-treated menisci showed a reduced meniscus area histomorphometrically (P < 0.01), as well as a decrease in water content (P < 0.01) when compared with the vehicle-treated menisci. The matrix composition of the menisci was assessed by the total glycosaminoglycans (GAGs) content, which decreased in the vehicle-treated menisci (P < 0.05) but did not decrease in the HA-treated menisci. In our model, a positive effect of HA was observed biochemically on the preservation of the meniscus matrix composition in the ACL-deficient knee. Received for publication on Oct. 15, 1998; accepted on Aug. 30, 1999     

Discoid meniscus

The discoid meniscus is an uncommon but not remote meniscal anomaly. Watanabe classified discoid menisci into three types: complete, incomplete, and Wrisberg-ligament type. These menisci vary in size, shape, presence of a posterior meniscal attachment, and mode of presentation.The complete and incomplete types are usually incidental arthroscopic findings unless they present with symptoms of an associated meniscal tear. The Wrisberg variant presents with the snapping knee syndrome, with visible, and often audible dunking with flexion and extension of the knee. The complete and incomplete types should be left alone unless there is an associated meniscal tear, in which case a saucerization procedure should be performed. The Wrisberg variant should have attachment of its hypermobile posterior horn.     

Anatomy and pathophysiology of the popliteal tendon area in the lateral meniscus: 2. Clinical investigation.

Treatment of abnormal mobility of the popliteal tendon area of the lateral meniscus is described. Twenty-seven patients who exhibited an abnormally mobile posterior segment with no obvious ruptures in the lateral meniscus were directly examined by us after an average of 4 years and 3 months from the time of the arthroscopic procedure. The main complaints associated with this condition before the surgery were pain and locking during deep knee flexions. The patients were divided into three groups according to surgical method: partial meniscectomy, subtotal meniscectomy, or meniscal repair. The subtotal meniscectomy and repair groups showed significantly higher scores than the partial meniscectomy group. A locking phenomenon recurred in one case of the meniscal repair group. In this case, the menisco-femoral coronary ligament posterior to the popliteal tunnel could not be sutured.     

Early changes in lapine menisci during osteoarthritis development: Part I: cellular and matrix alterations

OBJECTIVE: Osteoarthritis (OA) is the most common form of arthritis and patients with meniscal and ligament injuries of the knee are at high risk to develop the disease. The purpose of this study was to evaluate changes occurring in both medial and lateral menisci from the knees of anterior cruciate ligament (ACL) transected rabbits during the early stages of OA development. DESIGN: Meniscal tissues from control and experimental rabbits were processed for histology and immunohistochemistry for assessment of matrix organization and composition. RESULTS: At 3 and 8 weeks following ACL transection, histological examination demonstrated extensive extracellular matrix deterioration. Altered cell distribution, areas depleted of cells, and areas of cell clusters were found within the medial but not in the lateral meniscus. Immunohistochemistry of both medial and lateral menisci demonstrated significant changes in collagen distribution. Type I and III collagen staining was increased in both medial and lateral menisci. In contrast, type II collagen staining was overtly increased only in the medial meniscus. CONCLUSION: These results demonstrate that after ACL transection, extracellular matrix deposition as well as altered matrix organization and altered cell distribution occur early in the medial meniscus.     

Type I versus type II lunates: Ligament anatomy and presence of arthrosis.

One hundred-seventy embalmed cadaver wrists were dissected. The type of lunate (type I, no medial hamate facet; type II, medial hamate facet), the incidence and location of arthrosis (exposed subchondral bone) in the lunohamate joint, and the anatomic relationship of the volar triquetrocapitate (T-C) and the volar triquetrohamate (T-H) ligaments were identified and measured. The relationship between the T-C and T-H ligaments was classified into 3 types. In type A the T-C ligament was completely separate from the T-H ligament, in type B the T-C ligament overlapped the T-H ligament, and in type C the T-C ligament had an additional ligament from the triquetrum to the proximal pole of the hamate. Eighty-two percent of type I lunates were associated with a type A relationship between the T-C and the T-H ligaments and 96% of type II lunates were associated with a type C relationship between the T-C and the T-H ligaments. Arthrosis at the proximal pole of the hamate was more commonly associated with the type II lunates (49%) and with the type C relationship (57%) of the T-C and T-H ligaments. The incidence of arthrosis in the lunohamate joint was also significantly greater in the type II lunate with a medial facet of 3 mm or more.     

Ligaments of the knee

The ligaments of the knee can be divided into four groups. Ventral reinforcements are the patellar retinaculae. The posteromedial complex stabilizes the valgus stress. It consists of the medial collateral ligament, the thickened posteromedial capsule and a branch of the tendon of the semimembranosus muscle as well as the oblique popliteal ligament. On the lateral side the posterolateral complex protects the knee against varus stress. Here the lateral collateral ligament, the tendon of the popliteus muscle and the so-called popliteofibular fibres work together. The cruciate ligaments control the contact between femoral condyles and tibial plateau during flexion-extension of the knee. They course between the two layers of the capsule, the membranous and the synovial layer.     

异体半月板库的建立及临床初步应用

[目的]建立同种异体半月板库，为半月板移植的临床应用研究打下基础。[方法]作者利用组织库供体来源的优势，结合低温冷冻技术保存半月板，初步建立了异体半月板库。临床进行半月板移植时，根据患者的需要和半月板库的记录资料合理选择，并注名有关操作规程。[结果]从2005-2006年底，作者已经建立了大约有300个不同大小半月板的半月板库，为临床提供了14个同种异体半月板。[结论]半月板库的建立为临床半月板移植的开展打下了基础；异体半月板移植手术的近期疗效是令人满意的，远期疗效尚需更进一步观察和更多病例的积累。