Insertion of autologous tendon grafts to the bone: a histological and immunohistochemical study of hamstring and patellar tendon grafts

This study examined the structure of the insertion of autologous tendon grafts used for anterior cruciate ligament reconstruction. Biopsy specimens of the femoral ¶and tibial bone graft interface were obtained at revision surgery in 14 patients (6 with hamstring grafts, 8 with a patella tendon graft). The specimens were analyzed by light microscopy and immunohistochemistry (confirming type I, type II, and type III collagen). The insertions of hamstring autografts to the bone tunnel have three characteristic histological zones. Zone 1 is composed of the dense connective tissue of the graft. The collagen fibers of the graft enter the bone under oblique angles. Zone 2 is composed of woven bone with ¶a sharp transition to the lamellar bone of the tibia (zone 3). Immunohistochemistry revealed the presence of type I and type III collagen within the dense connective tissue of the graft. The woven and lamellar bone showed positive immunostaining for antibodies against type I collagen only. This structure resembled a fibrous ligament or tendon insertion. In the majority of patients with a patella tendon graft the structure of the insertion resembled a chondral enthesis. The chondral insertion of the graft to the bone is composed of four characteristic zones. Between the dense connective tissue of the graft (zone 1) and bone (zone 4) there is a zone of fibrocartilage (zone 2). Close to the bone the fibrocartilage is mineralized (zone 3). Within the fibrocartilage the immunohistochemical analysis confirmed type II collagen. This structure resembled the chondral enthesis of the normal anterior cruciate ligament. However, in cases in which the distal bone bloc has been fixated outside the tibial tunnel, the tibial insertion of the patellar tendon graft resembled a fibrous insertion. While both types of tendon grafts heal to the bone of femur and tibia, the insertion of patella tendon grafts healing by bone plug incorporation resembles the chondral insertion of the normal anterior cruciate ligament and may have a more physiological connection to the bone than hamstring grafts.     

The structure of the coracoacromial ligament: fibrocartilage differentiation does not necessarily mean pathology

The coracoacromial ligament forms part of the coracoacromial arch and is implicated in impingement syndrome and acromial spur formation. Here, we describe its structure and the composition of its extracellular matrix. Ligaments were obtained from 15 cadavers, nine from older people (average age 74.7 years) and six from younger individuals (average age 24.2 years). Cryosections of methanol-fixed tissue were cut and sections were immunolabelled with monoclonal antibodies against collagens, glycosaminoglycans, proteoglycans, matrix proteins and neurofilament proteins. Both ligament entheses were highly fibrocartilaginous and immunolabelled strongly for type II collagen, aggrecan and link protein. The area of labelling was more extensive in older people. However, fibrocartilage also characterized the ligament midsubstance, particularly with increased age. Signs of fibrocartilage degeneration were more common in older people. Ligament fat (containing blood vessels and nerve fibers) was conspicuous in both age groups, especially between fiber bundles at the entheses. We conclude that fibrocartilage is a normal feature but becomes more pronounced with age. It is not necessarily pathological, for it simply indicates that the ligament is subject to compression and/or shear. Nevertheless, the prominence of fibrocartilage at the acromial enthesis may relate to the frequency with which enthesophytes develop.     

Histological and ultrastructural evaluation of Leeds-Keio ligament six years after implant A case report

We examined by light and electron microscopy study a Leeds-Keio ligament removed from a patient 6 years and 4 months after implant following rupture. The new ligament presented an outer capsule made up of bundles of collagen fibres running mainly perpendicular to the long axis of the ligament. Septa were seen emerging from the capsule and composed of bundles of collagen fibres surrounding the bundles of Dacron fibres. Each thread of Dacron was surrounded by a layer of connective tissue containing periodic acid-Schiff (PAS)-positive cells. The bundles of collagen fibres making up the outer capsule, the septa and the layer of connective tissue surrounding the Dacron threads were positive for anti-type I collagen antibody. The rehabitated Leeds-Keio ligament presented a specific organization at the septa zone, showing a layer of collagen fibrils alternating with a layer of cells. Our remodelling findings suggest a shoelace effect of the artificial ligament. On the other hand, the presence of type I collagen could be responsible for the good functional behaviour of this composite system. In conclusion, the factors that play an important role in determining this remodelling process and its mechanical function are unknown. Received: 1 August 1996 Accepted: 7 January 1997     

Magnetic resonance imaging of entheses. Part 1

Entheses are the sites of attachment of a tendon, ligament, or joint capsule to bone. Many features of entheses are adapted to disperse stress and accommodate compressive and shear forces at, or near, boundaries between tendons or ligaments and bone. Of particular interest is calcified and uncalcified fibrocartilage, which has mechanical properties that differ from those of tensile regions of tendons or ligaments, and from bone. Ultrashort echo time (UTE) pulse sequences can identify the specific tissue components of entheses and differentiate cortical bone, calcified fibrocartilage, uncalcified fibrocartilage, and fibrous connective tissue. Magic angle imaging can also differentiate tissues, such as fibrocartilage and tendon, which have different fibre orientations. Understanding the magnetic resonance (MR) appearance of entheses involves consideration of tissue properties, fibre-to-field angle, magic angle effects, pulse sequences, and geometrical factors including fibre-to-section orientation and partial volume effects. New approaches using MR imaging, allow entheses to be visualised with much greater detail than previously possible, and this may help in biomechanical studies, diagnosis of disease including overuse syndromes and spondyloarthropathies, as well as monitoring tissue repair and healing.     

Anatomical study of the femoral and tibial insertions of the anterolateral and posteromedial bundles of human posterior cruciate ligament

For posterior cruciate ligament (PCL) reconstruction, two root, anterolateral and posteromedial bundles restruction are performed. However, little has been mentioned of anatomical measurements of the insertions to the bone of these bundles in previous publications. The aim of this study is to determine the precise anatomical measurements of the femoral and tibial insertions for anterolateral and posteromedial bundles of PCL. A total of 32 femur and 33 tibiae were selected from 50 cadavers after exclusion of knees that displayed macroscopically degenerative changes or evidence of trauma. PCL were divided into anterolateral bundles and posteromedial bundles to the insertion footprint, and those locations were measured and described. The distance from the center of the femoral insertions of the anterolateral and posteromedial bundles, and the Wrisberg ligament to the anterior margin of the medial femoral condyle averaged 9.6, 10.6, and 17.1 mm, respectively. The distance from the center of the femoral insertions of the anterolateral, posteromedial bundles, and Wrisberg ligament to the intercondylar roof averaged 4.8, 11.4, and 10.4 mm, respectively. The distance from the medial margin of the articular cartilage of the tibial plateau to the center of the tibial insertions of the anterolateral and posteromedial bundles averaged 51.0 and 50.0% of the total widest width of the tibial plateau, respectively. The vertical distance from the tibial insertion of the center of the posteromedial bundle to the plane of the tibial articular surface averaged 4.6 mm. This study leads to a better definition of the anatomy of the anterolateral and posteromedial bundles of PCL. It is very important to know the precise anatomy of PCL bundles when performing PCL reconstruction, and to evaluate PCL reconstruction surgery on an anatomical basis.     

Unusual case of right atrial reinfarction

It is well known that atrial infarctions are rare comparing to the ventricular. They cannot easily be verified on ECG and the standard autopsy technique does not include a detailed review of the atrial wall, so the atrial infarction often remains undiagnosed. A 63-year-old male was treated and died in an intensive care unit due to decompensated liver insufficiency and cardiac disease following long-lasting alcohol abuse. At autopsy, the extreme cardiomegaly was found, severe atherosclerosis of the anterior descending branch of left coronary artery. The posterior wall of the right atrium was thickened (cca 9 mm) in diameter of cca 3 × 3 cm, and this area was yellowish in the luminal part, while the central part was filled with dark red blood. A detailed dissection of the coronary arteries showed the complete occlusion of the atrial branch of the right coronary artery wreath as far as the place of sinoatrial artery branching, which corresponded anatomically to the described area of infarction on the posterior wall of the right atrium. Histopathological examination of the previously described area of the posterior wall of the right atrium, showed four zones of heart muscle changes: 1. zone of partially preserved structure of the heart muscle, 2. zone of cellular (immature) connective tissue, 3. areas of bleeding in cellular connective tissue, and 4. zone of acellular (old) connective tissue. These histopathological changes indicated that the posterior wall of the right atrium was affected by myocardial necrosis in at least two and possibly more times. It is reasonable to think that bleeding in the third zone of the posterior wall of the right atrium contributed greatly to the death due to the anatomical proximity to the sinoatrial node. It was confirmed by the existence of bradycardia with a prolonged PR interval, PR segment elevation in D1 and aVL lead and PR depression in the D3 lead on the ECG. These ECG changes appeared immediately before asystolia and the death of the patient, but not ventricular fibrillation or electromechanical dissociation due to ventricular infarction. The presented case shows that detailed autopsy examination of atrial wall and blood vessels can sometimes be crucial in disclosing the cause and mode of death if the ischemia and necrosis attack only the atrial wall, especially in the region of the heart conduction system.     

膝关节后交叉韧带及板股韧带临床解剖学研究

目的:探讨后交叉韧带分束情况及板股韧带的作用,为临床重建后交叉韧带提供解剖学基础。方法:30例成人膝关节标本,在无载荷与后抽屉试验两种条件下分别观察其后交叉韧带纤维束及板股韧带的紧张-松弛模式,根据纤维束紧张与松弛情况对后交叉韧带分束,确定各束中最能代表该束功能的纤维束,即"功能束"及其止点位置,明确板股韧带的作用。结果:后交叉韧带中未见等长纤维束。无载荷条件下屈伸膝关节,后交叉韧带中各纤维束处于较松弛状态(过伸与过屈位除外);后抽屉试验条件下,不同纤维束紧张,维持胫骨后向稳定性。后交叉韧带可以恒定地分为前外侧束与后内侧束,两束作用不同。前外侧束与后内侧束中均存在"功能束",两者的"功能束"联合作用可基本维持膝关节活动范围内胫骨的后向稳定性,"功能束"止点与两束止点中心不吻合。前、后板股韧带的出现率分别为3%与90%,二者横截面积均较小,前者的紧张-松弛模式类似于后交叉韧带前缘纤维,后者则与后内侧束相一致,二者均有维持胫骨后向稳定性的作用,后者还有在最大屈膝位防止后交叉韧带与股骨髁间窝后缘发生撞击的作用。结论:后交叉韧带是不等长的复杂的纤维结合体,其双束重建应根据"功能束"止点位置进行骨道定位,板股韧带在有条件时应予以保留。     

Attachment sites of the coracoclavicular ligaments are characterized by fibrocartilage differentiation: a study on human cadaveric tissue

We analyzed the immunohistochemical labeling patterns of the extracellular matrix of the coracoclavicular ligaments (CCL) in order to relate the molecular composition of the attachment sites to their mechanical environment. Ligaments were exposed from 12 fresh‐frozen human cadaveric samples (four males, mean age: 48.6±12.1 years). Cryosection of methanol‐fixed and decalcified tissue was cut and sections were labeled with a panel of monoclonal antibodies directed against collagens, proteoglycans and proteins of vascular components. Attachment sites of both ligaments showed characteristic fibrocartilaginous labeling of collagen type II, aggrecan and link protein in all samples. Labeling for type II collagen was most conspicuous at the insertion of the coracoid process. Morphometry of adjacent samples revealed a fibrocartilage zone of 10–15% in relationship with the ligament proper, where labeling for type II collagen, aggrecan and link protein was negative. The presence of fibrocartilage at both entheses of the trapezoid and conoid ligament suggests that the CCL complex is subject to shear/compression forces. A variable fibrocartilage differentiation at the entheses of both ligaments may be related to the marked change in loading and insertion angle that the ligaments undergo during shoulder movement.     

Computer analysis of PCL fibres during range of motion

An understanding of the orientation of posterior cruciate ligament (PCL) fibres can contribute to current knowledge of PCL biomechanics and potentially improve the effectiveness of PCL surgical reconstruction. In this paper, the orientation of PCL fibres with respect to the tibia and femur was analysed by means of a new computer method. The antero-lateral (AL) and postero-medial (PM) bundles of the PCL showed an increasing slope with respect to the tibial plateau during flexion and a statistically significant difference between them (AL: 37–65°, PM: 47–60°). PCL bundles showed similar orientation with respect to the femur and varied 14° average during flexion. The study also measured 84° twisting of PCL bundles during passive range of motion.     

Radiographic and histologic analysis of the tibial tunnel after allograft anterior cruciate ligament reconstruction in goats

BACKGROUND: Several problems have been reported with use of allogenic grafts in anterior cruciate ligament reconstruction, including local immune response to allograft tendon within the synovial fluid, delayed maturation and ligamentization, and progressive tibial tunnel enlargement. HYPOTHESIS: There is a correlation between the use of allograft and tibial tunnel enlargement. STUDY DESIGN: Controlled laboratory study. METHODS: Twenty healthy adult female goats underwent allograft anterior cruciate ligament reconstruction and were followed with serial radiographs at 6-week intervals. Animals were randomly chosen for sacrifice between 18 and 36 weeks for histologic assessment. RESULTS: Significant radiographic increases in tunnel size were noted within the first 6 weeks of healing and remained up to 36 weeks with no further remodeling noted. Histologic analysis showed progressive ligamentization of the allografts with tendon-to-tunnel wall biologic fixation with dense connective tissue. Remodeling and incorporation of the bone plug was seen in all cases. The allograft tendon underwent early fibrous attachment within the tunnel and remodeled toward ligament histologic structure. Remodeling and incorporation of the bone plug was seen by 18 weeks. CONCLUSION: Tibial tunnel enlargement, consistent with that seen in humans after allograft anterior cruciate ligament reconstruction, did not appear to affect the ultimate incorporation of the allograft on a histologic level.     

Immunolocalization of types I, II, and X collagen in the tibial insertion sites of the medial meniscus

The medial meniscus of the rabbit knee joint attaches to the tibial plateau via anterior and posterior insertions. Intact meniscal tibial insertions are essential for meniscal function. In the present study the distributions of types I, II, and X collagen in meniscal tibial insertions were investigated by indirect immunohistochemistry in a rabbit model. Four tissue zones were histologically identified in the anterior insertion site, including the ligamentous zone, uncalcified and calcified fibrocartilaginous zones and bone; the ligamentous zone was not observed in the posterior insertion site. Labeling for type I collagen was found to be strong in the ligament tissue and bone, and weak in the fibrocartilages which were also labeled for type II collagen. Tissues positive for different types of collagen overlapped and formed an irregular interface with various angles and depths, especially at the interface between the calcified fibrocartilage and bone. Positive labeling for type X collagen was identified only in the calcified fibrocartilage zone. The coexistence of types I and II collagen in the meniscal tibial insertions may indicate that this structural unit is subjected to both compressive and tensile loads. Type X collagen may play a role in maintaining the calcifying status of this tissue zone, so that its mechanical stiffness is kept between that of uncalcified fibrocartilage and hard bone. Restoration of the insertional structure including the distinct collagen distribution should be considered for a functional meniscal substitution. Received: 22 June 1999/Accepted: 27 September 1999     

Double tunnel technique forreconstruction of the posterior cruciate ligament

Excellent biomechanical evidence supports the theory that the posterior cruciate ligament (PCL) acts primarily as two separate functional bundles, with the anterolateral or anterocentral portion of the ligament acting predominantly in flexion, and the posteromedial or posterior oblique portion of the ligament acting predominantly in extension. Because of the size of the sites of origin and insertion of the PCL, reconstruction of the ligament using a single graft necessitates that only one of these two bundles is reconstructed. Therefore, we prefer to reconstruct both bundles of the PCL, and pass two separate grafts through two separate femoral tunnels. The grafts are then passed through a single tibial tunnel, with the anterolateral/ anterocentral graft being tensioned at 90° of flexion, and the posteromedial/posterior oblique graft being tensioned at 30° of flexion. The improved reproduction of PCL anatomy and biomechanics should result in a decreased incidence of late laxity in the PCL-reconstructed knee.     

中药治疗损伤半月板的动物实验观察(一)

本文通过动物实验探讨了中药对损伤半月板愈合的机制,实验表明中药能改善损伤局部的血液循环,对损伤半月板的修复有良好作用,并指出愈合情况与损伤类型及部位有关。     

Patella-tibial transfixation for posterior cruciate ligament repair and reconstruction: a biomechanical analysis

The posterior cruciate ligament (PCL) restricts posterior translation of the tibia on the femur. Because flexion of the knee increases tension on the PCL, the knee is usually immobilized in extension after PCL repair or reconstruction. Patella-tibial transfixation (olecranization), however, has been proposed to reduce the tension on the PCL without requiring immobilization of the knee. The objective of this study was: (1) to evaluate the distribution of strain in the anterolateral and posterior oblique fiber bundles of the PCLs in eight cadaveric knees before and after olecranization and (2) to measure the patellofemoral contact pressures at various degrees of knee flexion. Olecranization significantly (P < 0.05) reduced the strain on the anterolateral fiber bundles of the PCL at 15°–45° of flexion. No significant strain reduction was observed in the posterior oblique fiber bundles. Patellofemoral contact pressures measured from digitized Fuji sensitive film indicated significantly increased contact pressures (P < 0.05) following olecranization from 0°–60° of knee flexion. Increased parapatellar soft tissue tightness limited knee flexion to 90° and patella lift-off occurred at 75°. Although olecranization of the patella does reduce strain on the intact PCL within a selected range of motion, the beneficial effect of allowing early motion may be negated by the potentially harmful effects imposed upon the patellofemoral articular cartilage by increased contact pressures. Received: 20 December 1996 Accepted: 24 June 1997     

Anatomy of the anterior cruciate ligament

The anterior cruciate ligament (ACL) is a band of dense connective tissue which courses from the femur to the tibia. The ACL is a key structure in the knee joint, as it resists anterior tibial translation and rotational loads. When the knee is extended, the ACL has a mean length of 32 mm and a width of 7–12 mm. There are two components of the ACL, the anteromedial bundle (AMB) and the posterolateral bundle (PLB). They are not isometric with the main change being lengthening of the AMB and shortening of the PLB during flexion. The ACL has a microstructure of collagen bundles of multiple types (mostly type I) and a matrix made of a network of proteins, glycoproteins, elastic systems, and glycosaminoglycans with multiple functional interactions. The complex ultrastructural organization and abundant elastic system of the ACL allow it to withstand multiaxial stresses and varying tensile strains. The ACL is innervated by posterior articular branches of the tibial nerve and is vascularized by branches of the middle genicular artery.     

Magnetic resonance imaging of thehand and wrist

The application of magnetic resonance imaging (MRI) to the hand and wrist has lagged behind its use in larger joints. Recent advances in hardware and software technology have allowed faster imaging with excellent anatomic resolution. After routine radiography, MRI is the imaging procedure of choice for evaluation of chronic wrist pain. The most common indications for MRI within the hand and wrist include scapholunate-lunate ligament tears, triangular fibrocartilage complex (TFCC) tears, avascular necrosis, and soft tissue masses. MRI may occasionally help evaluate tendon abnormalities, atypical or postoperative recurrent carpal tunnel syndrome, and complications of inflammatory arthritides. Future applications of MRI will likely include improved anatomic imaging of smaller structures such as the lunatotriquetral ligament and the extrinsic ligaments, as well as MR angiography (MRA).     

Graft fixation in cruciate ligament reconstruction

Cruciate ligament reconstruction has progressed dramatically in the last 20 years. Anatomic placement of ligament substitutes has fostered rehabilitation efforts that stress immediate and full range of motion, immediate weightbearing, neuromuscular strength and coordination, and early return to athletic competition (3 months). This has placed extreme importance on secure graft fixation at the time of ligament reconstruction. Current ligament substitutes require a bony or soft tissue component to be fixed within a bone tunnel or on the periosteum at a distance from the normal ligament attachment site. Fixation devices have progressed from metal to biodegradable and from far to near-normal native ligament attachment sites. Ideally, the biomechanical properties of the entire graft construct would approach those of the native ligament and facilitate biologic incorporation of the graft. Fixation should be done at the normal anatomic attachment site of the native ligament (aperture fixation) and, over time, allow the biologic return of the histologic transition zone from ligament to fibrocartilage, to calcified fibrocartilage, to bone. The purpose of this article is to review current fixation devices and techniques in cruciate ligament surgery.     

MRI of the wrist

In the past, the diagnostic imaging algorithm for evaluating the painful wrist included initial plain radiographic examination followed by arthrography, tomography, bone scintigraphy, or computed tomography. In recent years, magnetic resonance imaging (MRI) has been proven efficacious for diagnosing a number of maladies of the bones, ligaments, and soft tissues. MRI can be of aid in evaluation of carpal instability, disorders of the triangular fibrocartilage, ulnar impaction syndrome, distal radioulnar joint (DRUJ) instability, fracture, avascular necrosis (AVN), tendinopathy, nerve entrapment syndromes, synovial abnormalities, and soft tissue masses.     

Anatomy of the posterior cruciate ligament and the meniscofemoral ligaments

This paper describes the anatomy of the posterior cruciate ligament (PCL) and the meniscofemoral ligaments (MFLs). The fibres of the PCL may be split into two functional bundles; the anterolateral bundle (ALB) and the posteromedial bundle (PMB), relating to their femoral attachments. The tibial attachment is relatively compact, with the ALB anterior to the PLB. These bundles are not isometric: the ALB is tightest in the mid-arc of knee flexion, the PMB is tight at both extension and deep flexion. At least one MFL is present in 93% of knees. On the femur, the anterior MFL attaches distal to the PCL, close to the articular cartilage; the posterior MFL attaches proximal to the PCL. They both attach distally to the posterior horn of the lateral meniscus. Their slanting orientation allows the MFLs to resist tibial posterior drawer.     

The bone-ligament junction: A comparison between biological and artificial ACL reconstruction

The physiological bone-ligament junction is composed of four zones: ligament, fibrocartilage, calcified fibrocartilage and bone. It plays a very important part in the distribution of mechanical loads applied to ligaments so as to diminish stress concentration or shearing at the interface. This paper examines types of bone and neoligament insertion after anterior cruciate ligament (ACL) reconstruction with a Dacron prothesis, the Leeds-Keio scaffold ligament (LK), patellar tendon with LAD augmentation (PT+LAD) and bone patellar tendon bone alone (PT). The anterior cruciate reconstructions were implanted in 16 sheep via double-isometric bone tunnels without postoperative knee immobilization. Histological examination of the new insertions (using haematoxylin-cosin, Giemsa, Masson, and Mallory stains) was performed following animal sacrifice after 2, 3, 6 and 9 months. A layer of fibrocartilage between the bone and the ligament was observed with PT, followed by a nearly normal insertion after 6 months. With PT, followed by PT+LAD, the augmentation was surrounded by fibrous tissue (also noted inside the LAD). The PT insertion was virtually physiological after 3–6 months. With the LK scaffold, fibrous tissue was noted in and around the scaffold, even after 6 and 9 months. With the Dacron prosthesis, fibrous tissue around the ligament was unaccompanied by ingrowth into the prosthesis. Nerve endings (pacinian corpuscles) were only present in the PT. These findings show that even after 9 months artificial ligaments are separated from bone by fibrous tissue and devoid of the histological and biomechanical features of a physiological junction. PT alone was the only technique that resulted in formation of a structure very similar to the physiological junction, capable of protecting the bone against excessive shearing stress and the tendon against excessive strains.