Ankylosis

Pathology is formed as a result of the fusion of articular surfaces during inflammation, tissue repair after damage or prolonged absence of movement. In practical traumatology and orthopedics , the following main causes of ankylosis are distinguished:

• Infectious arthritis. The articular ends of the bones can fuse with acute purulent nonspecific arthritis or chronic specific inflammation, for example, tuberculosis.
• Rheumatic diseases. Autoimmune and metabolic pathologies involving joints are accompanied by inflammation and, as a consequence, the formation of scar bridges between the ends of bones.
• Osteoarthritis. With degenerative lesions, the structure of tissues changes, bone growths appear, the volume of movements is gradually limited, sometimes to complete loss of mobility.
• Injuries. Ankylosis usually occurs with severe intra-articular fractures and fractures, especially against the background of incomplete reposition. The risk of developing pathology increases with open injuries with infection of the wound.
• Prolonged immobilization. With prolonged absence of movement, muscles shorten, fibrous changes form in the area of ligaments and tendons, soft-tissue structures fuse together, which leads to the formation of contractures, and in severe cases, ankylosis.

In some cases, ankylosis is formed with improper treatment of arthrogryposis, a congenital condition characterized by multiple contractures.

Movements in the joint are carried out by sliding the articular surfaces covered with cartilage relative to each other. The possibility of movement is provided by the elasticity of the capsule and the surrounding soft tissues. The normal configuration during movements is preserved due to strong inelastic ligaments that connect the bones together.

With ankylosis, one or two links suffer, on which the mobility of the joint depends. The most common options are complete or partial loss of cartilage, followed by fusion of articular surfaces and the proliferation of inelastic fibrous tissue inside or around the joint. Less often, the cartilages fuse together.

Taking into account the type of fusion , there are three variants of joint ankylosis:

• Fibrous. Occurs with prolonged immobilization, chronic non-purulent processes. The bones are interconnected by fibrous tissue. On radiographs, the articular gap is preserved, deformed. The functionality of the joint is lost, minor movements remain.
• Bone. It becomes the result of purulent arthritis and intra-articular fractures. The bones in the joint area coalesce to form a single array. The articular gap is not detected in the pictures, there are no movements at all.
• Cartilaginous. It is formed with arthrogryposis, it is detected in young children. It is characterized by the absence of movements in violation of the configuration of the articular ends of bones on radiographs.
• Depending on the extent, ankylosis can be partial or total, at the location – intra-articular, extra-articular or combined.

The patient complains about the lack of movement in the joint. With fibrous fusion, pain syndrome is usually present, with bone ankylosis there is no pain. During external examination, the joint is in a fixed position, which can be both functionally advantageous (providing the greatest opportunity for movement or self-service) and functionally disadvantageous.

An advantageous position for the shoulder joint is considered to be a moderate retraction with a slight deviation in front and a turn outward. For an ankylosed elbow joint, the optimal condition is bending at a right angle. The hip joint is most functional in the position of slight flexion and retraction, the knee joint – slight flexion, the ankle joint - flexion at an angle slightly exceeding 90 °. All other provisions are considered as functionally unprofitable and in need of correction.

External changes in ankylosis can vary significantly - from gross deformities (sometimes in combination with shortening or curvature of the limb) to a local violation of the configuration of the joint. The symptoms of attempting passive movements depend on the type of fusion. With bone ankylosis, there are no movements and pains, with fibrous, rocking movements are determined, accompanied by increased pain.

The presence of ankylosis has a negative effect on the rest of the musculoskeletal system, since it violates the biomechanics of movements. A healthy limb constantly suffers from overload, so arthrosis and enthesopathy are more often formed in it. With ankylosis of the lower extremities, the load on the spine increases and becomes asymmetric, which leads to curvature, osteochondrosis, intervertebral hernias.

The diagnosis is made by an orthopedic surgeon based on the results of an external examination and data from visualization techniques. Laboratory tests are carried out to determine the inflammatory diseases that led to the formation of ankylosis. The survey plan includes the following procedures:

• Radiography of the joint. It is prescribed to clarify the type and prevalence of fusion, in some cases it identifies diseases that caused the formation of ankylosis.
• CT and MRI of the joint. They are used to detail changes, assess the feasibility of surgical correction, and select the type of surgical intervention.
• Laboratory tests. Performed to determine rheumatoid factor, specific autoantibodies, hyperimmunoglobulinemia, reduction of complement fractions and other laboratory signs of rheumatic diseases.
• Differential diagnosis is carried out between ankylosis of various etiologies. Sometimes pathology needs to be distinguished from severe contractures.

Any conservative measures in this condition are of auxiliary importance, are prescribed to eliminate the etiological factor, reduce pain syndrome, at the stage of preparation for surgery and in the postoperative period. The only effective way to correct ankylosis in the absolute majority of cases is surgical intervention.

Conservative therapy

It is mainly used for fibrotic ankylosis. To eliminate pain , patients are recommended:

• mud treatment;
• electrophoresis with painkillers;
• massage;
• spa treatment.

With a small length of fibrous bridges, the return of mobility can sometimes be achieved using mechanotherapy.

Surgical treatment

The purpose of surgery for ankylosis is to restore the volume of movements or to bring the limb into a functionally advantageous position. The following techniques are used:

• Resection of splices. It is indicated with an extra-articular arrangement of fibrous or bony bridges. Allows you to restore the mobility of the joint. The volume of movements after the intervention depends on the condition of the articular surfaces surrounding soft-tissue structures.
• Arthrodesis. It is performed with a vicious limb position. They provide for partial removal of bone tissue and the creation of a new fixed fusion. After the operation, the patient gets the opportunity to lean on his leg or use his arm for self-care while maintaining ankylosis.
• Arthroplasty. Assumes modeling of articular surfaces for the resumption of movements. The joint is opened, the joints are excised, defects are replaced with auto- or homografts, soft tissue pads are placed between the bones to prevent re-fusion.
• Endoprosthetics. The affected articular surfaces are removed and replaced with an endoprosthesis. The most effective technique that provides full restoration of joint functionality.

After the operation, standard rehabilitation measures are carried out – physical therapy, massage, physiotherapy are prescribed. In the process of physical therapy, patients restore old or master new motor stereotypes.

The prognosis for ankylosis is determined by the type of fusion, the severity of deformities in the joint area, the condition of muscles, tendons and ligaments, and other factors. After arthrodesis, the functional capabilities of the limb increase, partial or complete disability persists. After arthroplasty, there is usually a partial return of mobility, possibly the re-formation of ankylosis. After the endoprosthetics, the working capacity is restored.

Prevention of ankylosis consists in timely reposition of intra-articular fractures with accurate restoration of the configuration of the articular surface, early initiation of treatment of inflammatory diseases of the joints. Immobilization cannot be abused unnecessarily. With a high probability of ankylosis formation, the limb should be fixed in advance in the desired position with a plaster bandage.