Osteochondral transplant

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In orthopedics and trauma surgery, osteochondral transplantation (cartilage-bone transplantation) is the transplantation ( transplantation ) of a healthy joint surface section into the area of ​​a cartilage or cartilage-bone defect. The transplantation can be carried out autologously , from the body's own material or homologous (foreign tissue). The cartilage is transplanted "en bloc" together with a piece of the underlying bone.

Cartilage damage

Articular cartilage enables the free mobility of all joints thanks to its ability to slide and its cushioning function. The tissue consists of a small number of cells (<1%) from a single cell type ( chondrocytes , cartilage cells), the products of these cells collagen and proteoglycans (matrix proteins) and a lot of water bound to the proteins. Because articular cartilage does not contain any vessels and therefore has no access to stem cells and is only nourished by the synovial fluid through diffusion , articular cartilage has no possibility of self-healing in the event of injuries or damage. Depending on the size and location of the cartilage damage, its extent even increases and in the medium term can lead to diffuse joint damage ( osteoarthritis ). The cause of cartilage damage are direct injuries, but also exaggerated and improperly performed sport and age changes. The cartilage damage can also be the result of joint fractures (e.g. ankle joint fractures ) or ligament injuries (e.g. cruciate ligament tear ). Bacterial joint infections and rheumatism can also destroy joint cartilage. In young people, cartilage damage is primarily found in the knee and ankle joints . In the elderly, the diffuse cartilage damage to the hip , shoulder and knee joint due to chronic wear and tear is in the foreground.

Symptoms

Cartilage damage can be completely symptom-free, but in most cases it has typical symptoms : joint pain, joint effusion, restricted mobility, blockages, joint cracking, limping. These complaints arise especially when starting an activity, e.g. B. Walking ("initial pain") and stress on the joints. Arthritic joints can cause pain even at rest. Sports or professional activities can be particularly difficult.

Diagnosis

In addition to the individual history (accidents, sports activity, age), the symptoms of the complaint are of decisive importance in the diagnosis . When do the complaints occur, which complaints are leading, since when have the complaints existed? The examination must focus on the symptoms mentioned above. X-ray images only show the bony consequential damage of the cartilage damage in the form of joint space narrowing, bony attachments on joints ( osteophytes ) and compression of the bone lamellae lying under the cartilage ("subchondral sclerosis") only in the case of massive diseases . Magnetic resonance tomography ("nuclear spin") is the diagnostic of choice when indicated, an examination method that shows not only the bony joint structure but also the connective tissue structures: cartilage, ligaments, muscles and joint capsules. Here, cartilage damage can be depicted fairly accurately. The most precise representation is obtained through an operative arthroscopy (joint mirroring), because besides the observation of the cartilage itself it is also possible to touch the tissue with a tactile hook as well as the operative removal of loose cartilage fragments and the smoothing of cartilage edges. Cartilage only performs mechanical tasks in the body, so this aspect of mechanical testing is of the utmost importance.

Therapy options

Due to the low spontaneous healing tendency of articular cartilage, therapeutic interventions are indispensable for complaints. The simplest options are physiotherapeutic measures ( physiotherapy ) to improve joint mobility and muscle control of the joints. Medicines can also be injected into the joint to improve lubricity. Products that contain hyaluronic acid are preferred . Proof of a real cartilage regeneration through these measures cannot be provided. however, the clinical situation of the patients may improve. Due to the lack of vessels in the cartilage tissue, operations to regenerate cartilage have been attempted that enable the cartilage defect to be opened up by vessels, cells and growth factors: Here, drilling ( Pridie drilling ) or the creation of fracture lines ( microfracture ) in the impermeable bone lamellae, on which the cartilage lies and has grown into place (subchondral lamella). These operations can be carried out minimally invasively , i.e. arthroscopically, and sometimes on an outpatient basis. The success rate for minor cartilage damage is high and the effectiveness has been proven by studies. With larger defects, microfractures can worsen the results of cartilage cell transplants . The bone marrow-stimulating interventions (drilling, microfracture) do not result in natural (hyaline) cartilage, but primarily fibrous replacement cartilage, which can perform many mechanical tasks.

Cartilage-bone graft

Cartilage-bone graft implanted in the knee joint

principle

Larger defects of more than one centimeter in diameter must be treated with procedures that bring vital tissue with cells into the defect. However, cartilage alone cannot be transplanted because it cannot withstand the stresses and strains of bones without firm biological contact (attached to it via collagen fibers), but simply swims off when you move. Cartilage tissue with the underlying bone can be taken as a transplant from joint areas that are lightly stressed or located outside the stress zones and therefore do not mechanically depend on an intact joint surface. Here, cartilage zones in the knee joint at the edge of the stressed areas and on the maximum flexion side of the thigh roller ( femoral condyle ) have proven their worth. At these points, cartilage with underlying bone can be removed as a piece (e.g. as a cylinder) and then implanted in a correspondingly prepared defect region. The disadvantage of the method is the defect zone that has arisen, so that in addition to the transplantation into the cartilage defect, implants can also be inserted into the removal defect. Synthetic bone-cartilage cylinders are available for this purpose. In the dorsal (flexor-side) removal areas on the femur, spontaneous defect closure occurs in a majority of cases in the majority of cases in the detection with MR even without the defect filling.

Action

In most cases, such an operation will be open; H. performed with an open access to the joint with severing of the skin, subcutaneous tissue, connective tissue joint capsule and the synovial membrane. One prepares towards the cartilage defect in order to then measure and assess it, if this has not yet been done arthroscopically. The defect zone is then punched out with a punch to a depth of about 1.5 cm in the knee joint, i.e. H. The tissue punch mainly contains bones ( cancellous bone ; "spongy bones ") with the destroyed cartilage adhering to it. It turns out that the subchondral bone also shows massive changes as part of the cartilage damage. A similarly large punch of healthy cartilage with bone underneath is then removed from another suitable area of ​​the joint with the same instruments and transplanted into the defect area. It is crucial to remove the graft cylinder exactly the same length as the defect cylinder so that the grafts fit perfectly and can be loaded immediately after a few days without sinking into the thigh bone under load. These cylinders grow in a few days to weeks through fracture healing from bone in the bed to the graft bone, whereas interestingly (here, too, the low healing tendency of the cartilage tissue is shown) the cartilage in the joint surface never heals without gaps, but always the boundary between the graft and the environment (microscopic ) remains visible as a gap. The reason for this behavior of the cartilage healing will be the hyaluronic acid as a component within the synovial fluid, the actual physiological task of which is to prevent any kind of adhesions within the joint through its viscous properties.

Aftercare

When the graft has been inserted correctly, the joint is closed again in layers with sutures and a bandage is made. After the operation, the patient has to relieve pressure with crutches for a few days so that the grafts can heal well and the sutures heal well. Already a few weeks after the operation, the operated joints can be loaded again and at the latest 3 months after the operation you can even play sports again. In contrast, the follow-up treatment of autologous cartilage cell transplantation takes many months until a cartilage-like load-bearing regeneration has taken place. Clinically, the cartilage-bone transplants mostly show a very good function and durability. There are seldom minor complaints in the area of ​​the cartilage removal, but these are significantly less than the previous complaints.

Accompanying damage

In the case of a cartilage-bone transplant, it should be noted that the causes of the cartilage damage must be considered during the operation and also during the planning stage. B. to be able to surgically correct cruciate ligament damage or meniscus lesions as the cause at the same time or beforehand. Joint steps or misalignments after joint fractures must be compensated for by corrective operations. The same applies to any existing axis errors of the leg, which can be responsible for the cartilage damage through chronic incorrect stress. Axis correction (e.g. growth control or osteotomy ) must also be carried out here in order to ensure that the cartilage transplantation is permanently successful.

literature

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  • E. Lexer: Substitution of whole or half joints from freshly amputated extremities by free plastic operations . In: Surg Gynecol Obstet . tape 6 , 1908, pp. 601-609 .
  • H. Wagner: Possibilities and experiences with cartilage transplantation . In: Journal for Orthopedics and Your Frontier Areas . tape 110 , 1972, p. 705-708 .
  • K. Messner, J. Gillquist: Cartilage repair. A critical review . In: Acta Orthopedica Scandinavica . tape 67 , no. 5 , 1996, pp. 523-529 .
  • NM Meenen, B. Rischke: Autogenous osteochondral transplantation (AOT) for cartilage defects on the femoral condyle . In: Operative Orthopedics and Traumatology . tape 15 , 2003, p. 38-56 .
  • JP Petersen, A. Ruecker, D. von Stechow, P. Adamietz, R. Poertner, JM Rueger, NM Meenen: Present and future therapies of articular cartilage defects . In: European Journal of Trauma . tape 29 , no. 1 , 2003, p. 1-10 .
  • K. Baumbach, JP Petersen, P. Ueblacker, J. Schröder, C. Göpfert, A. Stork, JM Rueger, M. Amling, NM Meenen: The fate of osteochondral grafts after autologous osteochondral transplantation . a one-year follow-up study in a minipig model. In: Archives Orthopedic Trauma Surgery . tape 128 , no. 11 , 2008, p. 1255-1263 .
  • PJ Evans, A. Miniaci, MB Hurtig: Manual punch versus power harvesting of osteochondral grafts . In: Arthroscopy . tape 20 , no. 3 , 2004, p. 306-310 .
  • U. Horas, D. Pelinkovic, G. Herr, T. Aigner, R. Schnettler: Autologous chondrocyte implantation and osteochondral cylinder transplantation in cartilage repair of the knee joint . A prospective, comparative trial. In: Journal of Bone Joint Surgery American . 85 (A), no. 2 , 2003, p. 185-192 .
  • KH Frosch et al: Removal of osteochondral cylinders from the medial dorsal femoral condyle via a minimally invasive approach . In: Operative Orthopedics Traumatology . tape 22 . Urban and Vogel, 2010, p. 212-220 (English).