Articular cartilage repair operations

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Cartilage damage scale according to Outerbridge:

0 - proper condition of cartilage,
I - softening and blistering of the cartilage,
II - the presence of incomplete cartilage defects,
III - damage reaching the subcartilage layer of the bone, but without exposing it,
IV - full exposure of the subcartilage layer of the bone.
The aim of surgical treatment of cartilage defects is to restore the continuity of the articular surface (so that the cartilage is slippery and smooth), thus eliminating pain and slowing down the further progression of degenerative changes. The reconstruction of the proper multilayer structure of hyaline cartilage with its full biomechanical properties is not entirely possible. By stimulating auto-repair processes or stimulating cartilage regeneration, we obtain fibrocartilage tissue, which has only properties similar to hyaline cartilage.

Generally, better treatment outcomes are achieved in treating acute post-traumatic cartilage lesions than in treating extensive damage resulting from joint degeneration. The greater the area and depth of the cartilage defect, the more difficult it is to restore a biomechanically efficient articular surface. Age is also important as well as individual factors related to e.g. the presence of inflammatory diseases or disorders of the joint axis.

The choice of the method of surgical treatment depends on the above factors, and in addition, the profession and sports activity of the patient should be taken into account.

Biological methods are based on stimulating the processes of repair or regeneration of cartilage. The biological methods performed surgically include:

The method of micro-fractures (microfraction),
Induced Chondrogenesis (AMIC),
Autologous Chondrocyte Implantation (ACI),
To obtain cartilage repair, three conditions should be met:

the presence of progenitor cells and other cells required for the synthesis of new cells included in the cartilage tissue,
providing scaffolding for the new tissue under development in the form of a special membrane (scaffold), e.g. a collagen membrane,
providing an appropriate environment in the pond that allows the process of creating new tissue to take place
Before introducing the correct repair procedure, it is necessary to thoroughly remove the dead cartilage from the defect and clean the subcartilage bone to prepare the appropriate substrate for the accumulation of new cartilage. If, along with the damage to the cartilage, there is damage to the subcartilage layer of the bone, it is necessary to use bone grafts.

It is also possible to transplant ready-made cartilage-bone tissue taken previously from another unloaded place in the joint. This is called osteochondral autografts method (OATS).

Non-biological methods consist in implanting an artificial material or prosthesis to supplement the local defect in the articular surface or the entire joint. The non-biological methods include:

Carbon pins,
Joint arthroplasty, including superficial Arthrosurface.

Micro fracture method (microfraction)

The micro-fracture method consists in making small holes in the subcartilage layer of the bone in order to cause deliberate bleeding of the bone marrow onto the surface of the defect. The holes are made at a distance of about 3-4 mm from each other and can be 3 mm deep or more (even up to 9 mm, then they are called nano-fractures). The resulting clot stimulates the myeloid cells to differentiate into chondrocytes and to create new fibrous-cartilaginous tissue filling the defect. The formed tissue contains less type II collagen and proteoglycans, and more type I collagen, which makes it less flexible and less load-bearing compared to hyaline cartilage. Therefore, after 3-5 years, the fibrous tissue may degrade, causing pain recurrence. In this case, treatment must be resumed. One of the possible complications of the microfracture or nano-fracture method is the formation of a cyst in the subcartilage layer of the bone at the site of drilled bone tunnels. To reduce the risk of their formation, some patients undergo abrasion or scarification, which involves superficial scratches on the bones. The advantages of the microfraction method or its derivatives undoubtedly include the simplicity and low cost of the procedure.

Induced Chondrogenesis (AMIC)

The AMIC method uses a three-dimensional membrane called a scaffold, which is applied to the defect after performing a micro-fracture technique. The scaffold prevents bleeding into the joint, stabilizing the clot that is formed. Thanks to the membrane, the system of cells flowing from the marrow is orderly, and the course of the collagen fibers being formed more closely reflects the structure of natural cartilage. This significantly improves the quality of the formed fibrocartilage tissue. The membrane can be fixed with a fibrin glue or self-adhesive (self-adhering) to the defect site.

Autologous Chondrocyte Implantation (ACI)

Autologous chondrocyte transplantation is a method of reconstructing the cartilage at the site of the defect based on chondrocytes obtained from previously collected cartilage from the unloaded part of the joint. The chondrocyte transplant procedure requires two surgical procedures. The various stages of the procedure include:

Cartilage collection (1st treatment) and venous blood collection
In the first stage, arthroscopy of the joint is performed to assess the size and depth of the defect. The surgeon then collects cartilage from non-stressed sites (e.g. from the proximal femoral epiphysis). Blood is drawn on the same day as the cartilage collection procedure. Blood and cartilage are transported to the Tissue Bank as soon as possible.
Breeding of chondrocytes in the Tissue Bank
Chondrocytes are obtained from cartilage in the process of digestion and isolation, when the cartilage is under the influence of enzymes (e.g. collagenase II or hyaluronidase). The number of chondrocytes isolated from one mg of cartilage depends on age - the younger the patient, the more chondrocytes are obtained. The serum obtained from the blood taken from the patient is a supplement to the nutrient medium for chondrocytes - it contains, among others: transport proteins, antioxidants, cytokines.
Preparation of the transplant in fibrinogen
To achieve the desired integrity of the graft, chondrocytes are embedded in fibrinogen.
Chondrocyte implantation (2nd procedure)
The chondrocyte implantation procedure is usually performed one month after collecting the patient's cartilage. Before implantation, the joint is cleaned and the defect site is prepared. In this case, microfraction is not performed so as not to mix blood from the bone marrow with the chondrocyte implant. If the damage was in the subcartilage layer of the bone, the defect is first filled with bone grafts, and then chondrocytes are implanted.

The traditional ACI procedure requires an arthrotomy, i.e. opening the joint, and chondrocytes are administered in the form of a suspension under the periosteal flap. Currently, this method is very rarely used. In the second generation ACI treatment, chondrocytes are placed under the collagen membrane, which prevents excessive cell migration and stabilizes the implant.

The latest third-generation ACI treatments include the use of a chondrocyte carrier, i.e. scaffold. This type of procedure is often referred to as MACI (Matrix Assisted Autologus Chondrocyte Implantation). Scaffold organizes the structure of the newly created tissue and facilitates the regulation of the transformation of cells into a chondrogenic type. Second and third generation ACI procedures can be performed under arthroscopy, during which only 2-3 small holes are made in the knee, so there is no need to open the joint. Surgical instruments and a special "tube" are inserted through the holes, through which the scaffold with chondrocytes is placed in the area of ​​the cartilage defect.

The advantage of autologous chondrocyte transplantation is the high quality of the obtained cartilage with a more similar structure to hyaline cartilage (compared to the cartilage obtained by the microfracture method and AMIC). The disadvantage of this method is the high costs associated with the need to perform two separate surgical procedures and the process of chondrocyte cultivation in the Tissue Bank.

Chondro-bone grafts (OATS, Osteochondral Autografts)

The OATS procedure consists in taking cartilage-bone blocks from unloaded parts of the joint, and then implanting them in a previously prepared place of the defect. The site of damage is prepared in such a way as to create a tunnel for one or more chondro-bone blocks. The material is usually taken from the medial or lateral part of the femoral block. The diameter of a single graft (graft) must be identical to the bone tunnel made in the defect site. The graft is carefully driven into the bone tunnel with a special hammer so that the level of the implant is identical to the surrounding cartilage. This allows for a relatively even distribution of pressure on the surface of the loaded joint.

The advantages of the OATS method are:

one-stage nature of the treatment,
lower costs compared to autologous chondrocyte transplantation (ACI),
possibility of early loading of the joint after surgery,
preservation of the hyaline cartilage at the repair site (when treating small defects).
The cartilage-bone grafting method works best in the case of focal cartilage-bone lesions (defect area up to 1-2 cm2). Larger defects require the collection and placement of several grafts next to each other, and the spaces between them are filled with fibrous cartilage. In this case, the articular surface after OATS repair may be uneven, which may lead to the development of degenerative changes on the opposite surface of the cartilage.

Proceedings after biological cartilage repair procedures

Following cartilage repair procedures, the integrity and stability of the implant are monitored through the analysis of magnetic resonance imaging (MRI) images of the knee. MRI protocols enable the morphological and biochemical assessment of cartilage regeneration. This allows you to start safely increasing the range of motion in the joint and gradually loading the limb in a timely manner. In most cases, gradual loading is possible in the 6th week after the procedure, previously the patient moves on crutches and only marks the phases of walking by touching the floor with his fingers. In general, the course of rehabilitation is very individual - its progress depends on the location of the repaired cartilage, the type of surgical method used and the patient's individual health conditions. In most cases, it is possible to return to light activities (cycling, jogging) within 3-4 months after the procedure.

Carbon pins

Carbon pins are biomaterials placed at the site of focal cartilage and bone lesions. Pins slowly overgrow with cartilage-like connective tissue and they achieve proper hardness on average 1 year after implantation. The effect of using pins is a quick reduction of joint pain. Carbon pins are mainly used in young people and in the event of failure of other repair methods.

The advantages of carbon pins are:

the possibility of modeling the shape and structure of the biomaterial,
no allergic reactive reaction,
adequate strength.

Arthrosurface surface prostheses

Surface prostheses are used in the case of local chondro-bone lesions with an area of ​​2-4 cm2 and a depth of more than 2 cm. The advantage of implanting a surface prosthesis is the preservation of the current biomechanics of the joint and the possibility of performing a total knee replacement in the future. The procedure can be performed with a minimally invasive approach, which significantly accelerates the return to normal activity. Gradual loading of the operated limb is possible already in the second week after the surgery.

Additional treatments correcting the axis of the joint

In the event of disturbances in the axis of the joint (varus, valgus of the knees or ankles), it is necessary to perform a corrective procedure. This is to prevent excessive local compression of the implant, allow it to be accepted and extend the life of the formed cartilage. In the area of ​​the knee joint, the so-called popliteal osteotomy (HTO, high tibial osteotomy).

Important information

The most common questions about the surgical treatment of articular cartilage damage: