Pathologic conditions of the ligaments and tendons of the knee

Excellent spatial resolution and unparalleled contrast resolution have allowed MRI to emerge as the dominant imaging modality for diagnosis of ligament and tendon pathology of the knee joint This article presents several important mechanisms of injury associated with tendon and ligament disruptions. When present, the pattern of bone contusions may reveal the vector of force. When one is aware of the mechanism of injury, it is possible to analyze systematically the structures of the knee and maximize the detection of pathology. Recognition of a knee dislocation pattern is important because the diagnosis may be unsuspected, and the clinician may have to be alerted to the possibility of vascular and neural injury.     

MR imaging evaluation of the postoperative knee: ligaments, menisci, and articular cartilage

The surgical management of knee injuries has increased in recent years. Postoperative magnetic resonance (MR) imaging of the knee following surgical intervention serves an important role in the diagnostic evaluation of patients with recurrent or residual symptoms following surgical intervention. MR imaging additionally assists in the noninvasive documentation of temporal changes at the surgical site potentially reflective of procedural success, or failure. Background understanding of the common surgical procedures performed, their normal postoperative MR imaging appearance, and imaging features of potential procedural complications are essential in the accurate evaluation of patients following prior knee surgery. The focus of the following article is to review the clinical and MR imaging features of the postoperative knee following prior surgical treatment of ligamentous, meniscal, and articular cartilage injuries of the joint.     

Nonoperative and postoperative rehabilitation of the collateral ligaments of the knee

Injuries of the knee joint are the most common problem seen by the sports medicine clinician. The medial collateral ligament (MCL) and medial capsular structures are frequently the site of many injuries in sports. Conversely, injuries to the lateral and posterolateral capsular structures are less common than those of the medial capsule, but can produce significant functional limitations and dysfunction. Either the medial or lateral capsule may be injured in isolation or in combination with other supporting structures. The nonoperative treatment and postoperative treatment of medial and lateral knee capsular injuries is based on several critical factors. These factors include the accurate determination of an isolated injury, status of the cruciate ligaments, type of onset, degree of instability, status of dynamic stabilizers, and patient's activity level. The treatment of isolated MCL injuries has been subject to considerable evolution and diversity. The rehabilitation of isolated MCL injuries is extremely aggressive with emphasis on immediate motion, strengthening, and early functional exercise drills. Conversely, the rehabilitation approach for posterolateral and/or lateral capsular injuries tends to be slightly slower. In this article the rehabilitation of the medial and lateral capsular structures nonoperatively and after surgical repair will be discussed.     

Effect of cyclic preconditioning on the tensile properties of human quadriceps tendons and patellar ligaments

Preconditioning of soft tissues has become a common procedure in tensile testing to assess the history dependence of these viscoelastic materials. To our knowledge, this is the first study comparing tensile properties of soft tissues before and after cyclic preconditioning with high loads. Sixteen quadriceps tendon-bone (QT-B) complexes and 16 patellar ligament-bone (PL-B) complexes from a young population (mean age 24.9 ± 4.4 years) were loaded to failure with a deformation rate of 1 mm/s. Half of the QT-B and the PL-B complexes underwent 200 uniaxial preconditioning cycles from 75 to 800 N at 0.5 Hz before ultimate failure loading. High-load preconditioning was made possible by the development of a highly reliable and easy-to-use cryofixation device to attach the free tendon end. PL-B complexes were more influenced by preconditioning than the QT-B complexes. Ultimate failure load, stiffness at 200 N and stiffness at 800 N were significantly higher for PL-B complexes after preconditioning, while the structural properties of QT-B complexes exhibited no significant alterations. The values of the mechanical properties like Young’s modulus at 200 N and 800 N were much higher for both preconditioned specimen groups. In addition, ultimate stress was augmented by preconditioning for PL-B complexes. Hysteresis and creep effects were highest during the first few loading cycles. More than 160 cycles were needed to reach a steady state. Beyond 160 cycles there was no further creep, and hysteresis was almost constant. Creep values were 2.2% of the initial testing length for the QT-B and 3.2% of the initial testing length for the PL-B complexes. The effect of cyclic preconditioning seems to be caused by progressive fiber recruitment and by alterations of the interstitial fluid milieu.     

Vanadate ingestion enhances the organization and collagen fibril diameters of rat healing medical collateral ligaments

Although an injured medial collateral ligament (MCL) will naturally heal, the quality of healing tissue is inferior to the uninjured MCL tissue. Previous studies have shown promising results of sodium orthovanadate (vanadate) in enhancing the quality of rat skin wounds. This study therefore investigated whether vanadate enhances the quality of the rat healing MCL in terms of the collagen fibril organization and diameter. Six mature male Sprague–Dawley rats, with weight ranges of 475–505 g and ages of 25 weeks, were used in this study. Three rats in the experimental group received vanadate (0.2 mg/ml) in their saline drinking water (150 mM NaCl), whereas three rats in the control group were only given saline water. Three weeks after transection, the rat MCLs were harvested for hematoxylin and eosin (H&E) staining and transmission electron microscopy. It was found that vanadate promoted organization of collagen fibrils and significantly increased the diameters of collagen fibrils by 14% in healing MCL (P<0.001). These results indicate that application of vanadate may be a promising tissue engineering approach to enhance the quality of healing tissues such as injured MCLs.     

Effect of joint position and ligament tension on the MR signal intensity of the cruciate ligaments of the knee

Six cadaveric lower extremities were imaged with T1-weighted spin-echo pulse sequences with the knees extended and flexed to 90°. Magnetic resonance signal intensities of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) were compared. Changing from extension to flexion resulted in decreased signal intensity in six of six ACLs and five of six PCLs. Two of the knees were then imaged with and without tension applied to the ACL. Both specimens showed a decrease in signal intensity with tension, followed by an increase in signal intensity with release of the tension. Finally, in three of the limbs the ACL was surgically reconstructed and then imaged with and without tension applied to the tension graft. Signal intensity decreased with tension and increased with release of the tension in all three specimens. Thus, joint position and changes in ligament tension affect the signal intensity of the ACL and PCL, generally resulting in a signal intensity decrease with tension.     

Ultrasonographic evaluation of normal extrinsic and intrinsic carpal ligaments: preliminary experience

Objective To determine normal anatomy of extrinsic and intrinsic carpal ligaments at ultrasonography (US).Design and volunteers In the first part of the study, two musculoskeletal radiologists retrospectively reviewed in consensus the photographs of anatomic sections and dissections derived from 20 cadaveric wrists. This cadaveric study gave the two readers the opportunity to learn the anatomy and orientation of the various extrinsic and intrinsic carpal ligaments and, thus, to develop a US protocol to facilitate the recognition of each carpal ligament. In the second part of the study, these two radiologists prospectively and independently evaluated the visibility of extrinsic and intrinsic carpal ligaments in 30 wrists of volunteers, using the same US protocol.Results With regard to extrinsic carpal ligaments, the radioscaphocapitate ligament (partially visible, 38%; completely visible, 62%), the radiolunotriquetral ligament (partially visible, 27%; completely visible, 73%), the palmar ulnotriquetral ligament (partially visible, 12%; completely visible, 88%), and the dorsal radiotriquetral ligament (partially visible, 7%; completely visible, 93%) were visualized at US. The dorsal ulnotriquetral ligament (partially visible, 21%; completely visible, 74%), the ulnolunate ligament (partially visible, 5%; completely visible, 70%), and the radial collateral ligament (partially visible, 18%; completely visible, 12%) were more difficult to recognize. The radioscapholunate ligament was never seen. With regard to intrinsic carpal ligaments, the dorsal (partially visible, 11%; completely visible, 89%) and palmar (partially visible, 38%; completely visible, 62%) scaphotriquetral ligaments as well as the dorsal scapholunate ligament (partially visible, 3%; completely visible, 97%) were visualized at US. The dorsal lunotriquetral ligament (partially visible, 39%; completely visible, 61%) and the palmar scapholunate ligaments (partially visible, 12%; completely visible, 81%) were more difficult to recognize.Conclusion US may be helpful in identifying the major extrinsic and intrinsic carpal ligaments.     

The role of vasculature and angiogenesis for the pathogenesis of degenerative tendons disease

More than 100 years ago Wilhelm Roux (1895) introduced the term "functional adaptation to anatomy and physiology". Compared with other organ systems the functional adaptation processes are best identifiable in the locomotor system, like for example in the two types of tendons: traction and gliding tendons. Traction tendons are tendons where the direction of pull is in line with the direction of the muscle (e.g. Achilles tendon). Gliding tendons (e.g. tibialis posterior tendon) change direction by turning around a bony or fibrous hypomochlion. In this region the tendon is subjected to intermittent compressive and shear forces and the extracellular matrix consists of avascular fibrocartilage. Avascularity is considered to be a key factor for the etiology of degenerative tendon disease. The repair capability after repetitive microtrauma is strongly compromised in avascular tissue of gliding tendons. Reduced vascularity is not a specific feature of gliding tendons; several studies have shown that the number and size of blood vessels are largely shortened in the waist of the Achilles tendon. However, histological biopsies from degenerated Achilles tendons and Doppler flow examinations revealed a high blood vessel density in patients with degenerative tendon disease. Angiogenesis is mediated by angiogenic factors and recent studies have shown that the vascular endothelial growth factor (VEGF) is highly expressed in degenerative Achilles tendons, whereas VEGF expression is nearly completely downregulated in healthy tendons. Several factors are able to upregulate VEGF expression in tenocytes: hypoxia, inflammatory cytokines and mechanical load. Since VEGF has the potential to stimulate the expression of matrix metalloproteinases and inhibit the expression of tissue inhibitors of matrix metalloproteinases tissue inhibitor of metalloproteinases (TIMP) in various cell types (e.g. endothelial cells, fibroblasts, chondrocytes), this cytokine might play a significant role for the pathogenetic processes during degenerative tendon disease. An animal experiment in the rabbit has shown that local injection of VEGF reduced the material properties of the Achilles tendon. These experimental findings are in accordance with clinical results that a locally administered (in the area with neovascularization) sclerosing drug (Polidocanol) has a beneficial effect on chronic mid-portion Achilles tendinosis. In conclusion, decreased and increased vascularity might be involved in the pathogenesis of degenerative Achilles tendon disease.     

MR imaging of tendons and ligaments of the midfoot

Disorders of ligaments and tendons at the midfoot are less common than those around the ankle and at the hindfoot. Nevertheless, disorders of the distal portions of the anterior and posterior tibialis tendons (ATT and PTT) and the spring ligament complex have an important clinical impact and can be treated with surgery. In this article, we discuss important factors for the magnetic resonance (MR) protocol and review the normal MR anatomy and MR findings in disorders of the distal ATT and PTT as well as of the spring ligament complex. In addition, we discuss clinical aspects of these disorders.     

Dynamic high-resolution ultrasound of intrinsic and extrinsic ligaments of the wrist: How to make it simple

Wrist ligaments are crucial structures for the maintenance of carpal stability. They are classified into extrinsic ligaments, connecting the carpus with the forearm bones or distal radioulnar ligaments, and intrinsic ligaments, entirely situated within the carpus. Lesions of intrinsic and extrinsic ligaments of the wrist have been demonstrated to occur largely, mostly in patients with history of trauma and carpal instability, or rheumatoid arthritis. Ultrasound allows for rapid, cost-effective, non-invasive and dynamic evaluation of the wrist, and may represent a valuable diagnostic tool. Although promising results have been published, ultrasound of wrist ligaments is not performed in routine clinical practice, maybe due to its technical feasibility regarded as quite complex. This review article aims to enlighten readers about the normal sonographic appearance of intrinsic and extrinsic carpal ligaments, and describe a systematic approach for their sonographic assessment with detailed anatomic landmarks, dynamic manoeuvres and scanning technique.     

Immunohistochemical localization of collagen types I and VI in human skin wounds

Summary A total of 74 human skin wounds were investigated and collagen types I and VI were localized in the wound area by immunohistochemistry. Collagen type I appeared in the form of ramifying string-like structures after approximately 5–6 days, but positive reactions in the form of a spot-like staining around isolated fibroblasts also occurred in a skin wound aged 4 days. Collagen VI was detectable after a post-infliction interval of at least 3 days showing a strongly positive reacting network associated with fibroblasts in the wound area. Both collagens appeared almost constantly after a wound age of 6–7 clays and could also be found in wounds aged a few months. Therefore, although a positive reaction for collagen type I in the form of string-like and ramifying structures around wound fibroblasts indicates a wound age of at least 5–6 days, a spot-like positive staining for collagen type I cannot exclude a wound age of at least 4 days. A positive staining for collagen type VI represents a post-infliction time of 3 days or more. The almost constant appearance of these collagen types suggests that negative results in a sufficient number of specimens indicate a wound age of less than 6–7 days, but cannot completely exclude longer post-infliction intervals. Since collagen type I and VI are also found in the granulation/scar tissue of lesions with advanced wound age, the immunohistochemical analysis of these proteins provides no further information for an age determination of older skin wounds.     

Axial oblique MR imaging of the intrinsic ligaments of the wrist: initial experience

Objective To evaluate two separate MR sequences acquired in the axial oblique plane, parallel to the long axis of the scapholunate (SL) and lunotriquetral (LT) ligaments, to determine whether the addition of these sequences to the standard MR wrist examination improves visualization of the intrinsic ligaments, and the evaluation of their integrity. To our knowledge, this plane has not been described in the literature previously.Design and patients In total we evaluated 26 patients with chronic wrist pain or instability, referred for MR imaging following assessment by an orthopedic surgeon or physiatrist. All patients underwent initial conventional tri-compartment wrist arthrography, which served as the reference standard. This was immediately followed by MR arthrography, in the standard coronal and true axial planes, as well as in the axial oblique plane. The SL and LT ligaments were initially assessed for the presence or absence of tear, using the standard coronal and true axial sequences, and subsequently re-evaluated with the addition of the axial oblique planes.Results A total of ten intrinsic ligament tears were identified with conventional arthrography: six SL and four LT tears. Five of the six SL tears were identified on the standard sequences. All six were diagnosed with the addition of the oblique sequences. There were three false-positive SL tears identified using standard MR imaging, and two false-positives with the addition of the oblique sequences. No LT tear was identified on standard sequences, whereas all four were confidently seen with the addition of oblique images. No false-positives of the LT ligament were recorded with either standard or axial oblique sequences.Conclusion The study suggests that the addition of axial oblique MR sequences helps identify tears to the intrinsic ligaments of the wrist, particularly the LT ligament. In addition, the axial oblique images assist in localization of the tear.     

Analysis of the immunohistochemical localization of collagen type III and V for the time-estimation of human skin wounds

Summary Collagen type III and V were visualized immunohistochemically in 79 surgically treated human skin wounds with a wound age between 8 h and 2.5 months. Network-like structures positively staining for collagen type III and associated with fibroblastic cells in the wound area were first detectable in a 2.5-day-old skin lesion and occurred regularly in wounds more than 5 days old. Collagen type V appeared first in the wound area after about 3 days, slightly later than collagen type III, and was detectable regularly in wounds with a survival time of 6 days or more. The immunohistochemical detection of collagen type III or type V thus indicates a wound age of at least 2–3 days. The lack of a positive reaction in a sufficient number of specimens indicates a wound age of less than 6 days. Even though both collagen types could also be detected in older wounds (wound age 2.5 months), further information for the time-estimation of older skin wounds cannot be given due to the observation that the time period during which reparative processes can be observed depends on the extent of the wound area.     

MR imaging of the normal ligaments and tendons of the ankle

The 10 major ligaments and nine major tendons of the ankle were evaluated in 17 ankle MR studies to determine the incidence of visualization of each structure in each of the three orthogonal planes. High-resolution technique was used, with 3 mm slice thickness and an in-plane resolution of 0.6 mm. Of the 19 ligaments and tendons evaluated, 18 demonstrated more than 70% frequency of visualization in at least one imaging plane. However, seven ligaments and three tendons demonstrated 0% visualization in at least one of the three orthogonal planes. Seven ligaments showed more than 70% visualization in only one plane (three coronal, two axial, two sagittal). Only the Achilles tendon and anterior tibial tendon demonstrated 100% visualization in all three planes. We conclude that all three orthogonal planes are essential to achieve optimal visualization of all of the major ligaments and tendons of the ankle. For specific evaluation of selected ligaments or tendons, only one or two planes may be required.     

Effects of training, immobilization and remobilization on tendons

Since a tendon is a living tissue, it is not a surprise that tendon shows the capacity to adapt its structure and mechanical properties to the functional demands of the entire muscle-tendon unit. However, compared with muscle, the experimental knowledge of the effects of strength or endurance-type training on tendon tissue is scarce and clinical human experiments are completely lacking (1). Research should, however, be able to improve the true understanding of the biomechanical, functional, morphological and biochemical changes that occur in tendons due to training and physical activity, since understanding of the basic physiology of a tissue is the key to understanding its pathological processes (1,2). Compared with muscle tissue, the metabolic turnover of tendon tissue is many times slower due to poorer vascularity and circulation (1, 3). The adaptive responses of tendons to training are therefore also slower than those in muscles, but they may finally be considerable if the time frame is long enough (3, 4).     

Clinical evaluation of sodium hyaluronate in the treatment of patients with sopraspinatus tendinosis under echographic guide: experimental study of periarticular injections

Purpose

The purpose of this study was to examine the effect of periarticular injection of hyaluronate into shoulders with supraspinatus tendinosis under echographic guide.

Methods and materials

The subjects were 56 patients with clinical, echographic and magnetic resonance diagnosis of supraspinatus tendinosis. They were divided in two groups by random sampling; 28 patients were assigned in SH group (sodium hyaluronate) and 28 patients in SC group (sodium chloride).The test drug was 20 mg sodium hyaluronate (2 ml, Hyalgan^®, Fidia SpA, Abano T., P.M. 500–700.000, 20 mg/2 ml).

Results

Preliminary results showed that sodium hyaluronate presented the highest efficacy in the improvement of clinical symptoms and recovery of functional status in patients with supraspinatus tendinosis in fact the mean V.A.S. score (Visual Analogue Scale) at 1 month after the end of the infiltrative cycle was 8.0 in the SC group vs. 2.8 in SH group and these numerical data were substantially unchanged also after 3 and 4 months.

Conclusion

Hyaluronate injection under echographic guide should be use not only as a lubricant but also to prevent articular cartilage degeneration and cover and protect the articular cartilage; indeed sodium hyaluronate can decrease inflammatory joint process.     

Multidetector computed tomography in acute knee injuries: assessment of cruciate ligaments with magnetic resonance imaging correlation

Purpose: To evaluate whether non-contrast multidetector computed tomography (MDCT) for suspected acute knee fractures can also be used to evaluate cruciate ligament pathology.

Material and Methods: A total of 42 patients (17-65 years) underwent four-section MDCT. The images were independently evaluated at clinical workstations by four radiologists. They assessed the integrity (normal or torn) and the best slice direction (axial, sagittal, or coronal) for visualization of the cruciate ligaments. Magnetic resonance imaging (MRI), performed within 4 weeks (mean 6 days) in relation to MDCT, was considered the gold standard.

Results: Ligament integrity at MDCT: the mean interobserver proportion of agreement for a normal anterior cruciate ligament (ACL) was 0.73, for a torn ACL 0.41, for a normal posterior cruciate ligament (PCL) 0.96, and for a torn PCL 0.54. Interobserver variation for ACL was significant (P = 0.0136-0.0260), but insignificant for PCL (P = 0.3389-0.7212). Intra-observer variation was insignificant. Visualization was best in the axial and sagittal direction for ACL and PCL, respectively. At MRI, 29 normal, one partially, and 12 completely torn ACLs, and 37 normal, four partially and one completely torn PCL were found.

Conclusion: MDCT can detect an intact ACL and PCL with good specificity, accuracy, and negative predictive value. The assessment of torn ligaments is unreliable.     

Morphometry of the semitendinosus and gracilis tendons with application to anterior cruciate ligament reconstruction

The length and cross-sectional area of human semitendinosus and gracilis tendons were measured in both single- and multi-strand configurations for the purpose of anterior cruciate ligament graft preparation. The average lengths of the semitendinosus and the gracilis tendons were 235±20 mm (mean±SD) and 200±17 mm, respectively. The cross-sectional area of a doubled semitendinosus tendon (two strands) was significantly less than that of a 10-mm-wide patellar tendon graft (P<0.001). The cross-sectional area of the tripled semitendinosus tendon (three strands) and the 10-mm-wide patellar tendon were similar. Doubling of the combined semitendinosus and gracilis tendons (four strands) and tripling of this combination (six strands) resulted in a significantly greater cross-sectional area in comparison to the 10-mm-wide patellar tendon (P<0.05, four strands;P<0.001 six strands). This investigation demonstrates that anterior cruciate ligament grafts fashioned using multiple-strand combinations of the semitendinosus and gracilis tendons result in a cross-sectional area that is comparable to the bone-patellar tendon-bone graft. This is an important finding since cross-sectional area reflects the intra-articular volume of collagenous tissue. This information should be helpful to surgeons considering using the hamstring tendons as an anterior cruciate ligament graft.     

浮膝损伤中膝关节稳定性的恢复与重建

目的 探讨浮膝损伤中骨和韧带等稳定装置的恢复与重建的方法和疗效. 方法 对2000年1月-2006年1月我院收治的38例浮膝损伤合并急性膝关节不稳患者的治疗方法进行总结,评定术后疗效. 结果 38例患者术后均得到随访,时间1～4年,平均1.5年,骨折均愈合.术后伤口感染3例,内固定松动2例,前交叉韧带松弛1例,骨关节炎2例.按照改良美国特种外科医院(Hospital for Special Surgery,HSS)系统评价膝关节功能:优良32例,中上5例,下中1例,优良率占84%. 结论 浮膝损伤治疗中不仅仅要重视骨结构连续性的重建,更要重视韧带、半月板、关节囊、肌肉等稳定结构的恢复.