Osteochondritis dissecans

Osteochondritis dissecans ( OCD or OD short, Anglo American also osteochondritis dissecans ) is a circumscribed bone lesion beneath the articular cartilage that may end with the overlying cartilage as loose bodies ( joint mouse ) with the rejection of the bone affected area. There then remains a joint surface defect ( mouse bed). The OCD can affect most joints of the human body, but it occurs mainly in the knee, ankle and elbow joint. Due to concentrated mechanical action, however, the OD occurs only in convex joint proportions as the femoral condyle, the Talusrolle and the radial condyle of the humerus. This article focuses especially on the localization knee. In veterinary medicine, it occurs particularly in large dogs (shoulder, elbow, knee, ankle, etc.) and in fattening pigs.

Etiology (cause)

From different in the past controversial emergence theories mechanical factors ( repetitive pulse loads ) appear to represent the most likely main cause. Therefore, active to highly active children and young people are most often affected. Maybe in the ( typical ) OCD on the medial femoral condyle a disorder of the movement sequence during running and jumping plays a crucial role: It comes as show motion analysis, a short-term rotation in the knee with the following striking the femoral condyle to the cheek of the intercondylar eminence. In osteochondritis dissecans of the lateral femoral condyle rarer often ( eg a discoid meniscus ) and possibly also childlike rheumatism plays a meniscal pathology involved. The OCD also frequent the medial Talusschulter and the central Talusrolle ankle is a real OCD with sports -related repetitive overload. When Knorpelknochenläsion the lateral (outer) Talusschulter it is exclusively the result of repeated Umknickverletzungen, ie an increase of traumatic osteochondral flakes, cartilage, bony scales with a completely different therapeutic approach. In the OCD of the elbow armbelastende throwing sports ( handball, volleyball) are causally involved. But not all forms of OCD of the elbow, the mechanical genesis can be so unequivocally as documented at the knee. What role the bone structure and quality of play in the emergence of OCD, is the subject of further studies of the osteology. Thus we find in almost all affected a part pronounced vitamin D3 deficiency with corresponding disorders of calcium metabolism.

Also, circulatory disorders of the epiphyseal growth plate appear to play according to recent studies, a role: this is of great importance that the cartilaginous growth plate is not only important for femoral shaft for linear growth, but also as a continuous layer on the epiphyseal center for the growth in thickness of the femoral condyles ( fig ). This growth plate is the articular cartilage. The growth plate is supplied with blood from the bone side, making it vulnerable to mechanical influences. Studies in foals and piglets show that there is Knorpelnekrosen the growth zone beneath the cartilage. The necrotic reach in the course of normal growth in the epiphyseal bone area and mark there as bony osteochondrosis zone. Their healing (remodeling ) is likely to be delayed by a vitamin D3 reduced supply.

Pathogenesis ( disease progression )

The disease occurs on the bottom of a bony structure disturbance below the cartilage ( subchondral Vaskularisationsstörung ). This will take place at the epiphyseal center in the border area between articular and growth cartilage. At the beginning it is in this area of osteonecrosis, later to connective tissue demarcation ( rejection) compared to the surrounding vital bone. The overlying articular cartilage shows the Osteochondroseherd initially no changes, it is vital and mechanically stable because its (normal ) diet is ensured by the joint synovial fluid. Later, it occurs due to the unstable nascent bony base, and an increase in volume in the border area between dissecate and bearing bone secondary to cartilage changes in the form of over-stretching and tears. This contour changes in effective joint surface was now able to carry out entrapment (impingement ) to intermittent blockages. Then under continuous stress leads to a loosening of the dead bone from the vital environment and according to plan of elastic cartilage ceiling in the late phase to a solution of the whole piece of bone cartilage and thus to joint mouse ( osteochondral ). The osteochondral fragment can then remain in the mouse bed (often in talus ) or acute deploy ( often to the femoral condyle ), ie be moved by articulation to other parts of the joint cavity. This stage gives the disease the name ( dissecans ): . Earlier, before X-ray and MRI scan, the disease was recognized only by the replacement of the "mouse" and resulting blockage in the last stage of the disease ( dissection ), the cartilage bone fragment also decompose and break down into barely detectable parts., it remains definitely in the dissection a relevant, the mouse size corresponding joint surface defect ( mouse bed)

Clinic ( complaints )

First symptoms appear as non-specific stress-related pain in the affected joint. These are often misinterpreted in children than injuries, growing pains or rheumatism. The duration of the first symptoms until definitive diagnosis is today still about a year. Morning symptoms do not occur, rather they occur during or after physical activity. Typically, the port must be set due to the pain in already long history. Consistent sports break or relief reduces the discomfort. A joint effusion (thick knee) or a soft tissue swelling is not one of the signs of OCD. After detachment of a joint mouse it can be tucked in and it comes to joint lock (blocking), and sudden onset of severe pain as in a large meniscal tear. Mechanical symptoms ( blockades, extension deficit ) in addition to pain is always a warning signal and a reference to a joint surface changes, instability or an incipient dissection of the cartilage-bone fragment.

Diagnosis

Often the disease is discovered by chance on a radiograph that is made ​​after an accident from the knee region, from the ankle or the elbow. In case of complaints typical type for active children and young people can be provided with a simple X-ray image, the definite diagnosis because of dead bone can be identified below the joint surface at typical location on the femoral condyle. Sometimes a so-called tunnel view with the knee flexed show the necrotic even better. For a more detailed analysis, a magnetic resonance imaging ( MRI ) should be performed in most cases. Can measure the exact location and size of the lesion, the depth extent and especially the involvement of the overlying cartilage in the images produced thereby. There are also to take statements on the stability of the findings. This then results in therapeutic consequences. For assessing the course of the disease, especially the MRI, but again the simple X-ray examination is.

Therapy

The treatment of osteochondritis dissecans is dependent on the relative size of the change and on the location in relation to the joint. There are OCD on the medial and the lateral femoral condyle ( the condyle ). Rarely, the change also comes on plain bearing against the kneecap and the kneecap before himself. Another important consideration is the stage ( stable / unstable) of the lesion. As signs of instability occurs in an MRI cyst formation, a protrusion of Dissekates and crack formation in cartilage clearly. An important clinical sign of instability are blockages in the joint function that occur as a sign of the articular surface on the disease process. Additionally, the age of the patient plays a certain role. In still wide open growth plates - so in boys to 14 and for girls up to the age of 13 - are the spontaneous cure rates slightly better. On average, 50 % of OD cases the knee heal without surgical measures. The healing always takes months to years because of bone remodeling (remodeling ) takes the necrotic zone by osteoclasts and osteoblasts long time.

Conservative therapy

First, it should always be made except with dissected or dissektionsgefährdeten ( unstable ) findings, a conservative attempt without surgery. For this purpose, the mechanical stress of the relevant joint is massively reduced by a consistent sports ban. With sustained complaints is also a relief to crutches in lesions of the knee or ankle may be necessary to alleviation of pain. Immobilizations of joints, such as in a plaster cast or unloading with the example a Thomas splint, no longer apply in the current treatment concepts.

Surgical treatment

In case of persistent or increasing despite systematic Sports pause complaints at the knee or ankle, especially with new onset of mechanical symptoms such as blockages or joint snapping and increase in size or instability instructions in the MRT an arthroscopy ( arthroscopic ) is the relevant joint recommended in order to assess the condition of the articular cartilage may which is not reliably achieved with magnetic resonance imaging. Hard criteria for surgery are a very large stove or signs of instability.

Is in the arthroscopic diagnosis of cartilage intact and joint side to recognize no demarcation of the affected area, is indicated ( from outside the joint) drilling the sclerotic zone for the revitalization of the bone retrograde. For this special cannulated drills are used, in which a guide wire first checked the correct position, and then definitely overdrilled. Through the holes and vessels stem cells can penetrate into the necrotic area and the bone regeneration. The location of the drill holes is controlled during surgery with the aid of an X-ray fluoroscopy.

If the affected area is not yet solved, the cartilage intact, but an incipient differentiation recognizable, you can through a drill hole retrograde bone grafting or by the lifted findings ( bone-cartilage cap) an open bone grafting and drilling carry. This method is used especially in the persistent findings on the anklebone ( talus ) application that seldom heal spontaneously.

When loosened or dissolved dissecate the reattachment of Dissekats in adolescent patients is indicated. To this end, absorbable pins or screws are used. The osteochondral fragment and the " mouse bed " must be debrided to and possible tissue defects are filled with autologous bone graft. At destroyed or devitalized dissecate in adults a bone - cartilage transplantation is usually the treatment of choice. Such operations are in contrast to the pure bore holes open on a hinge opening carried out. the advantage of the cartilage - bone transplantation is the availability even at low bony lesions, as they are frequently found in OD. however this caused sampling defects, but usually do not produce clinically relevant symptoms.

Newer methods of chondrocyte transplantation contact transplantation in the laboratory cultured autologous ( autologous ) chondrocytes in the cartilage defects in under a protective layer of autologous periosteum or of collagenous matrix fleeces as autologous chondrocyte implantation (ACI ) or matrix substances as matrix -associated chondrocyte implantation ( MACI ). Success is now also the cell-free implantation of collagenous matrix into the prepared defect microfractured camp as AMIC ( autogenous matrix induced chondrogenesis ). The advantage here is that avoiding the extensive cell culture with known only incomplete differentiation into chondrocytes. The result of a hyaline regeneration can be achieved by such an improved micro- fracture. At low bony necrosis of cartilage regeneration, these methods alone are however not suitable. It should be additionally performed an autologous (autologous ) spongiosa of the cartilage layer.

Furthermore, some groups are trying to revitalize with an extracorporeal shock wave therapy, the osteochondral fragment again, if it has not yet eliminated as joint mouse. Other groups try hyperbaric oxygen therapy. Evidence of the success there is not both experimental approaches.

Results

The goal of treatment is a complete recovery of the structure and function of the affected joint. For this purpose, a revitalization and restructuring (remodeling ) is the change in bone areas prerequisite. As bone remodels and can generally heal completely without scarring and in physiological structure, no anatomical or mechanical residual damage are primarily expected as long as the cartilaginous joint surface is not affected. Smaller and stable findings in adolescents may regress spontaneously with consistent sport break in at the earliest one year, respectively heal. For larger, also stable, non- dissected findings may take several years to complete healing despite operational measures ( tapping ). After healing of such findings, the results can usually be described as very good and good.

Unstable conditions in which an osteochondral osteochondral fragment is partially or completely fallen out of the joint compound, the goal is the anatomical fit of the joint part in the " mouse bed " and its stable fixation., The mouse bed and the osteochondral fragment are initially free of all loose tissue with sharp instruments until the osseous base is achieved. Subsequently far drilled from the contact surface in the healthy bone to here allow vessels and stem cells ingrowth. Then, the resulting by removing the scrim bone defect is filled with a bone graft. the Dissekatschuppe is then fixed mechanically stable polymer with absorbable pins. Here at optimal technique can also be good and sometimes very good results are obtained.

Installation and remodeling processes take a long time (years). The load capacity of such affected joint is significantly limited for many months.

Also good results can be obtained at dissezierter osteochondrosis with loss or decay of Dissekates if an osteochondral transplantation of a cartilage-bone cylinders from a lightly loaded joint complex is carried out in the defect district. Only autologous chondrocyte transplantation can not compensate for the bony defect and are therefore not suitable for profound damage to the articular surfaces. The results of cell transplantation are therefore comparable only in connection with simultaneous bone grafting or by use of synthetic matrix substances of osteochondral transplantation.