The use of the contact Nd:YAG laser in arthroscopic surgery: effects on articular cartilage and meniscal tissue

The contact Nd:YAG laser's small size, tip variety, fiberoptic application, and suitability for use in a saline medium make it a particularly appealing tool for use in arthroscopic procedures. This study was performed to investigate the laser's effects on articular cartilage and meniscal tissue with respect to depth of damage (canine cadaver model) and healing response (rabbit model). Depth of damage in the canine cadaver model was greater in meniscal tissue than in articular cartilage at each wattage level. In the presence of a saline bath, depth damage in both tissues was diminished. Scalpel articular cartilage lesions showed no response over time. Electrocautery lesions uniformly showed significant wide margins of hyaline cartilage necrosis which increased over time. Laser articular cartilage lesions showed vigorous healing responses characterized by fibrocartilage healing by 6 weeks. Scalpel meniscectomies showed characteristic fibrocartilagenous remodeling by 6 weeks, while electrocautery meniscectomies showed wide margins of necrosis with no specimen showing remodeling capability. Laser meniscectomies showed an intermediate response with a small number of menisci remodeling in a normal fashion. This article represents the first comprehensive look at the effects of the Nd:YAG laser on articular cartilage and meniscal tissue in terms of depth of damage and healing response over time, and indicates this laser's biological advantage over scalpel and electrocautery in arthroscopic procedures.     

Cartilage repair in the knee joint

Full thickness defects of the articular cartilage in the knee joint have lower regenerative properties compared to chondral lesions of the ankle. In order to avoid early osteoarthritis, symptomatic articular cartilage defects in younger patients should undergo biological reconstruction as early as possible. There are different surgical procedures available to achieve a biological resurfacing of the articular joint line. Numerous animal experiments and clinical studies have shown that early biological reconstruction of circumscribed cartilage defects in the knee is superior to a conservative or delayed operative treatment. This effect refers not only to the defect healing but also to the elimination of changes following secondary osteoarthritis. The different surgical procedures can be differentiated concerning the various indications and the final outcome. Additional malalignment, meniscus tears, and/or ligament instabilities should be treated simultaneously together with the cartilage resurfacing. The mid- and long-term results of the different current techniques are promising, but further modifications and improvements are needed.     

Management of focal chondral lesion in the knee joint

Articular cartilage does not contain vascular, nervous and lymphatic tissue and chondrocytes hardly participate in the healing or repair process of chondral tissue because of being surrounded by plenty of extracellular matrix. Therefore, the injury to articular cartilage frequently requires an operative treatment. The goal of surgical repair of articular cartilage is to regenerate nearly normal chondral tissue and prevent degenerative arthritis caused by the articular cartilage defect. Microfracture is a kind of cartilage repair procedure that makes a fibrin clot containing mesenchymal stem cells in the chondral lesion. Microfracture is a simple procedure but it has a disadvantage that the repaired tissue is fibrocartilage. Autologous chondrocyte implantation has an advantage that it implants fully differentiated chondrocytes to the lesion, which theoretically produces hyaline cartilage. Its disadvantages are that it is a two stage and a costly procedure. Osteochondral autograft transplantation is a one stage procedure and repairs the lesion with hyaline cartilage. But its limitation is the lack of donor site availability. Surgeons who understand the theoretical background, indications, surgical methods, rehabilitation, complications, and clinical course of cartilage repair procedures can achieve the goal of preventing degenerative arthritis.     

Articular cartilage defects in the knee--basics, therapies and results

Full-thickness defects of the articular cartilage in the knee joint have lower regenerative properties than chondral lesions of the ankle. In order to avoid early osteoarthritis, symptomatic articular cartilage defects in younger patients should undergo biological reconstruction as soon as possible. Various surgical procedures are available to biologically resurface the articular joint line. Numerous animal experiments and clinical studies have shown that early biological reconstruction of circumscribed cartilage defects in the knee is superior to conservative or delayed surgical treatment. This superiority refers not only to defect healing but also to the elimination of changes following secondary osteoarthritis. The various surgical procedures can be differentiated by the range of indications and the final outcome. Additional malalignment, meniscus tears and/or ligament instabilities should be treated simultaneously with the cartilage resurfacing. The mid- and long-term results of the various current techniques are promising, but further modifications and improvements are needed.     

Concepts in gene therapy for cartilage repair

Once articular cartilage is injured, it has a very limited capacity for self repair. Although current surgical therapeutic procedures for cartilage repair are clinically useful, they cannot restore a normal articular surface. Current research offers a growing number of bioactive reagents, including proteins and nucleic acids, that may be used to augment various aspects of the repair process. As these agents are difficult to administer effectively, gene-transfer approaches are being developed to provide their sustained synthesis at sites of repair. To augment regeneration of articular cartilage, therapeutic genes can be delivered to the synovium or directly to the cartilage lesion. Gene delivery to the cells of the synovial lining is generally considered more suitable for chondroprotective approaches, based on the expression of anti-inflammatory mediators. Gene transfer targeted at cartilage defects can be achieved by either direct vector administration to cells located at or surrounding the defects, or by transplantation of genetically modified chondrogenic cells into the defect. Several studies have shown that exogenous cDNAs encoding growth factors can be delivered locally to sites of cartilage damage, where they are expressed at therapeutically relevant levels. Furthermore, data is beginning to emerge indicating that efficient delivery and expression of these genes is capable of influencing a repair response toward the synthesis of a more hyaline cartilage repair tissue in vivo. This review presents the current status of gene therapy for cartilage healing and highlights some of the remaining challenges.     

Meniscal repair and transplantation: indications, techniques, rehabilitation, and clinical outcome

The purpose of this paper is to provide current knowledge regarding the indications, operative techniques, rehabilitation programs, and clinical outcomes of meniscus repair and transplantation procedures. Meniscus tears that occur in the periphery may be repaired using a variety of operative procedures with high success rates. Complex multiplanar tears that extend into the central one-third avascular zone can also be successfully repaired using a meticulous vertically divergent suture technique. The outcome of these repairs justifies preservation of meniscal tissue, especially in younger athletic individuals. Meniscal transplantation is a valid treatment option for patients who have undergone meniscectomy and have related tibiofemoral joint pain, or in whom articular cartilage deterioration in the meniscectomized compartment is present. Rehabilitation after these operations includes knee motion and quadriceps-strengthening exercises initiated the first day postoperatively. The initial goal is to prevent excessive weight bearing and joint compressive forces that could disrupt the healing meniscus repair or transplant. The protocol contains modifications according to the type of meniscal tear, if a concomitant procedure is done (such as a ligament reconstruction) or if noteworthy articular cartilage deterioration is present. Patients who have repairs of peripheral meniscus tears are generally progressed more rapidly than those who have repairs of tears extending in the central one-third region or those who undergo meniscal transplantation. The safety and effectiveness of the rehabilitation program has been demonstrated in several clinical studies. We recommend preservation of meniscal tissue, regardless of age, in active patients whenever possible.     

Biologische Knorpelrekonstruktion im Kniegelenk

Full thickness defects of the articular cartilage in the knee joint have lower regenerative properties compared to chondral lesions of the ankle. In order to avoid early osteoarthritis, symptomatic articular cartilage defects in younger patients should undergo biological reconstruction as early as possible. There are different surgical procedures available to achieve a biological resurfacing of the articular joint line. Numerous animal experiments and clinical studies have shown that early biological reconstruction of circumscribed cartilage defects in the knee is superior to a conservative or delayed operative treatment. This effect refers not only to the defect healing but also to the elimination of changes following secondary osteoarthritis. The different surgical procedures can be differentiated concerning the various indications and the final outcome. Additional malalignment, meniscus tears, and/or ligament instabilities should be treated simultaneously together with the cartilage resurfacing. The mid- and long-term results of the different current techniques are promising, but further modifications and improvements are needed.     

Meniscus repair and transplantation: a comprehensive update

Preservation of meniscal tissue is paramount for long-term joint function, especially in younger patients who are athletically active. Many studies have reported encouraging results following repair of meniscus tears for both simple longitudinal tears located in the periphery and complex multiplanar tears that extend into the central third avascular region. This operation is usually indicated in active patients who have tibiofemoral joint line pain and are less than 50 years of age. However, not all meniscus tears are repairable, especially if considerable damage has occurred. In select patients, meniscus transplantation may restore partial load-bearing meniscus function, decrease symptoms, and provide chondroprotective effects. The initial postoperative goal after both meniscus repair and transplantation is to prevent excessive weight bearing, as high compressive and shear forces can disrupt healing meniscus repair sites and transplants. Immediate knee motion and muscle strengthening are initiated the day after surgery. Variations are built into the rehabilitation protocol according to the type, location, and size of the meniscus repair, if concomitant procedures are performed, and if articular cartilage damage is present. Meniscus repairs located in the periphery heal rapidly, whereas complex multiplanar repairs tend to heal more slowly and require greater caution. The authors have reported the efficacy of the rehabilitation programs and the results of meniscus repair and transplantation in many studies.     

Current concepts for rehabilitation and return to sport after knee articular cartilage repair in the athlete

Articular cartilage injury is observed with increasing frequency in both elite and amateur athletes and results from the significant acute and chronic joint stress associated with impact sports. Left untreated, articular cartilage defects can lead to chronic joint degeneration and athletic and functional disability. Treatment of articular cartilage defects in the athletic population presents a therapeutic challenge due to the high mechanical demands of athletic activity. Several articular cartilage repair techniques have been shown to successfully restore articular cartilage surfaces and allow athletes to return to high-impact sports. Postoperative rehabilitation is a critical component of the treatment process for athletic articular cartilage injury and should take into consideration the biology of the cartilage repair technique, cartilage defect characteristics, and each athlete's sport-specific demands to optimize functional outcome. Systematic, stepwise rehabilitation with criteria-based progression is recommended for an individualized rehabilitation of each athlete not only to achieve initial return to sport at the preinjury level but also to continue sports participation and reduce risk for reinjury or joint degeneration under the high mechanical demands of athletic activity.     

Delayed Incorporation of a TruFit Plug: Perseverance Is Recommended

TruFit plugs (Smith & Nephew, Andover, MA) are synthetic polymer scaffolds that are inserted into an articular surface to provide a stable scaffold to encourage the regeneration of a full thickness of articular cartilage to repair chondral defects. Our unit has shown promising early results for the repair of small articular cartilage defects within the knee. Other series have reported “failures” in which patients have complained of persistent symptoms and joint effusion at 6 months after plug insertion and arthroplasty has been undertaken. We report a case of delayed incorporation of an articular cartilage defect of the lateral femoral condyle treated with 3 TruFit plugs. The patient eventually reported symptom alleviation and resumption of functional activity after 24 months of continued rehabilitation. We recommend that patients with continued symptoms persevere with rehabilitation and allow the regenerating articular cartilage time to mature fully before considering undertaking irreversible arthroplasty procedures.     

Gene therapy for cartilage repair

AIM: Articular cartilage has very limited intrinsic healing capacity. Although numerous attempts to repair full-thickness articular cartilage defects have been conducted, no methods have successfully regenerated long-lasting hyaline cartilage. One of the most promising procedures for cartilage repair is tissue engineering accompanied by gene therapy. METHOD: With gene therapy, genes encoding for therapeutic growth factors can be expressed at a high level in the injured site for an extended period of time. Chondrocytes have been intensively studied for cell transplantation in articular cartilage defects. RESULTS: However, recent studies have shown that chondrocytes are not the only candidate for cartilage repair. Muscle-derived cells have been found capable of delivering genes and represent a good vehicle to deliver therapeutic genes to improve cartilage repair. More importantly, recent studies have suggested the presence of pluripotent stem cells in muscle-derived cells. CONCLUSION: New techniques of cell therapy and molecular medicine for the treatment of cartilage lesions are currently undergoing clinical trials. This paper will summarize the current status of gene therapy for cartilage repair and its future application.     

Physical therapy and rehabilitation in chondral lesions

Although most patients with articular cartilage defects are asymptomatic, some may have symptoms such as pain, effusion, muscle weakness, and limited range of motion. The goals of rehabilitation in chondral lesions are to relieve clinical symptoms, obtain painless full range of motion and muscle strength, and improve function. The key point in the rehabilitation program is to improve sensorimotor function and decrease pain and disability without increasing cartilage degeneration. Basic principles in the postoperative rehabilitation period are the same as those in conservative treatment. However, the rehabilitation program should be modified depending on the surgical procedure. Each phase of the rehabilitation program should be designed considering the type of surgical procedure, estimated healing time, restoration of joint mobility and muscle strength, and the extent of pain and effusion. Exposing the healing cartilage to shear stress under compression may have adverse effects on the healing process. For this reason, the early stage of rehabilitation (0-6 weeks) is comprised of passive, active-assistive and non-weight bearing range of motion exercises. Postoperative weight-bearing depends on the size, nature, and location of the lesion and the surgical procedure. Restriction in weight bearing is recommended in all treatment procedures except for cartilage debridement. For a successful outcome, open communication should exist between the rehabilitation team and the surgeon and the rehabilitation program should be individualized.     

The effects of immobilization on the characteristics of articular cartilage: current concepts and future directions

OBJECTIVE: The purpose of this paper is to review current data and concepts concerning the effect of immobilization on articular cartilage in animal models. We also evaluate the methods to measure articular cartilage changes in humans. METHODS: Studies looking at the effects of immobilization on morphological, biochemical, and biomechanical characteristics of articular cartilage are reviewed. RESULTS: Articular cartilage changes in immobilized animals include altered proteoglycan synthesis, as well as thinning and softening of the tissue. The overall thickness of articular cartilage in the knee decreases up to 9% after 11 weeks of immobilization and the deformation rate under test load increases up to 42%. Quantitative data about changes in human articular cartilage following immobilization are not available. This is mainly due to the lack of an accurate, reproducible, and non-invasive method to characterize articular cartilage. DISCUSSION: An understanding of the alterations in articular cartilage following short and long term immobilization in humans is essential for the optimization of rehabilitation programs. Refined imaging techniques combined with state-of-the-art visualization tools could allow the systematical monitoring of articular cartilage morphology changes in immobilized humans.     

Chondral and osteochondral injuries: mechanisms of injury and repair responses

Acute and repetitive impact and torsional loading of joints can damage the articular surface, causing pain, joint dysfunction and effusions, and in some instances, progressive joint degeneration. These injuries often remain undetected and their incidence, pathogenesis, natural history, and optimal treatment remain poorly understood. Advances in arthroscopy and joint imaging have improved the ability of physicians to identify articular surface injuries, and reports of new methods of promoting restoration of articular surfaces have increased interest in their treatment. Three classes of chondral and osteochondral injuries can be identified based on the type of tissue damage and the repair response: (1) damage to the joint surface that does not cause visible mechanical disruption of the articular surface but does cause chondral damage and may cause subchondral bone injury, (2) mechanical disruption of the articular surface limited to articular cartilage, and (3) mechanical disruption of articular cartilage and subchondral bone. In most instances joints can repair damage that does not disrupt the articular surface if they are protected from further injury. Mechanical disruption of articular cartilage stimulates chondrocyte synthetic activity, but it rarely results in repair of the injury. Disruption of subchondral bone stimulates chondral and bony repair, but it rarely restores an articular surface that duplicates the biological and mechanical properties of normal articular cartilage. The extent and effectiveness of the chondral and osseous repair responses vary with age: in general younger individuals, especially skeletally immature people, have more effective repair of articular surface injuries. To be of value to patients a treatment of an articular surface injury must produce better short- and long-term results than the natural repair response. Thus, before selecting a treatment for a patient with a chondral or osteochondral injury the surgeon should define the type of injury and understand its likely natural history.     

关节软骨损伤生物学修复的研究进展

随着社会的现代化进程和人口的老龄化,由于外伤和退变引起的关节软骨损伤患者显著增多,为此如何解决关节软骨修复的问题日益显得重要。本文主要对关节软骨损伤的生物愈合与再生的研究进展做一综述。     

Osteochondritis dissecans of the talus treated by the transplantation of tissue-engineered cartilage

Management of osteochondral lesions of the joint has been difficult, because articular cartilage has a poor healing capacity as a result of its lack of vessels, nerve supply, and its isolation of systemic regulation. Although a lot of basic research and surgical treatments for cartilage repair have focused on osteochondral lesions in the knee joint, orthopedic surgeons have recently diverted their attention to osteochondral lesions in the ankle joint, partly because of the widespread introduction of arthroscopy in ankle surgery. There have been many attempts to treat articular cartilage defects in the ankle joint as well as in the knee joint. However, no treatment has achieved efficient healing with hyaline cartilage. Recently, tissue engineering technique for cartilage repair has been gaining much attention in the orthopedic field. In this study, we reported on a patient with osteochondritis dissecans of the talar dome, successfully treated by transplantation of tissue-engineered cartilage made ex vivo using atelocollagen gel and low tibial osteotomy.     

Promotion of the intrinsic damage-repair response in articular cartilage by fibroblastic growth factor-2

OBJECTIVE: To identify the effect of fibroblastic growth factor-2 (FGF-2) on the intrinsic damage-repair response in articular cartilage in vitro. METHODS: Articular equine cartilage explants, without subchondral bone, had a single impact load of 500 g applied from a height of 2.5 cm. Explants were then cultured in 0, 12, 25, 50 or 100 ng/ml FGF-2 for up to 28 days. Unimpacted discs served as controls for each time-point. Histological and immunohistochemical techniques were used to quantify and characterise the response of putative chondrocyte progenitor cells (CPC) to damage and FGF-2 treatment. RESULTS: FGF-2 significantly accelerated the appearance and increased the numbers of de novo repair cells identified histologically at the cartilage surface. The response was affected by the dose of FGF-2. The repair cells were shown to be chondrocytes by their expression of collagen types II, IX/XI, but not of type I collagen. In addition, these cells, and those underlying the articular surface, were shown to be immunopositive for Notch-1 and PCNA, markers for proliferating cartilage progenitor cells. CONCLUSIONS: The results of this study indicate that, following single impact load, CPC can be stimulated in mature articular cartilage in vitro. These CPC and the cells arising from them appear to represent the cartilage's response to damage. The timing of the appearance of CPC and their overall numbers can be significantly increased by FGF-2, providing further evidence for an important role for FGF-2 in modulating cartilage repair. These results indicate that further study into the mechanisms of repair in mature cartilage using this in vitro model are vital in understanding the repair capacity of mature cartilage.     

The role of mandibular condylar cartilage in articular cartilage repair.

The articular hyaline cartilage of synovial joints has a very limited capacity for repair after injury. In contrast, the mandibular condylar cartilage of the temporomandibular joint possesses as intrinsic potential for regeneration. This study aimed to test the hypothesis that cultured allografts of mandibular condylar cartilage could be used to promote biological repair of injured orthotopic joint surfaces. Using a primate animal model, cultures of mandibular condylar cartilage cells were grafted into surgically created defects in a recipient hyaline cartilage joint surface. Articular wound healing was assessed macroscopically and histologically over a postoperative period of 52 weeks. Mandibular condylar cartilage cells scheduled for allogenous transplantation were initially characterised in vitro. Expansion of primary colonies in organ culture provided the allogenic cellular material for in vivo grafting. Grafting of osteochondral articular wounds with 5-week cultures of mandibular cartilage cells led to wound regeneration with complete reconstitution of articular surface continuity by 52 weeks. There was novel synthesis of cartilage collagens and sulphated glycosaminoglycans within the repair tissue and no evidence of immunological rejection. Healing of grafted defects was thought to occur by a combination of donor cell proliferation and ingress of host mesenchymal cells. In contrast, grafted control wounds underwent largely fibrous repair with incomplete articular regeneration. In conclusion, transplanted allografts of cultured mandibular condylar cartilage appeared to have the ability, in this primate model, to promote cartilaginous repair and regeneration of orthotopic articular wounds.     

Current concepts of articular cartilage repair

Articular cartilage provides a vital function in the homeostasis of the joint environment. It possesses unique mechanical properties, allowing for the maintenance of almost frictionless motion over a lifetime. However, cartilage is vulnerable to traumatic injury and due to its poor vascularity and inability to access mesenchymal stem cells, unable to facilitate a satisfactory healing response. Untreated chondral defects are thus likely to predispose patients to the development of osteoarthritis. Reconstitution and repair of articular cartilage is dependent on the neosynthesis or implantation of cartilage matrix elements, a goal which can be achieved through a variety of surgical means. Commonly used repair techniques include marrow stimulation, structural osteo-articular autografts or chondrocyte implantation. Despite substantial differences in the complexity and technical application of each method, all are united in the endeavour to restore joint function and prevent joint degeneration. Anyone attempting to treat cartilage defects must possess a basic understanding of the physiology of cartilage growth, and relevant factors affecting cartilage healing and repair. Furthermore, knowledge of the biomechanics and kinematics of the knee are essential in order to appreciate the forces acting on joint surfaces and repair tissues. Although clinical success is dependent on appropriate patient selection, accurate clinical assessment, definition of root causes and application of the right choice of treatment modality, the ultimate outcome of any intervention remains heavily reliant on the surgeon's proficiency in the technical aspects of the chosen surgical procedure.     

镁元素及镁材料在关节软骨损伤修复中的作用及机制研究进展

软骨损伤是由炎症、创伤、肿瘤等造成的,由于关节软骨自身解剖因素,使其损伤后的愈合能力较差,制备组织工程材料促进软骨损伤修复备受研究者关注。镁元素及镁材料因其良好的生物安全性、生物相容性、可降解性及可获得性受到广泛关注,其在骨关节炎等软骨损伤修复中起到重要作用,笔者就镁元素及镁材料在关节软骨损伤修复中的作用及机制作一综述。