What happens in the joint
Articular cartilage rests on a thin layer of bone called the subchondral plate. With osteochondritis dissecans, a section of this bone loses its blood supply, softens, and the border between it and the healthy bone turns into a kind of crack. The cartilage on top remains intact for some time, so complaints are vague. Over time, the fragment may stabilize and grow, or it may separate and fall into the joint cavity. A loose osteochondral fragment injures the opposite surface and accelerates wear of the joint, so if the lesion is unstable, you should not delay treatment.
- Stable lesion - the fragment is in place, the cartilage above it is intact
- Unstable lesion - the fragment is mobile, the cartilage is torn
- Free body - a fragment has separated and moves in the joint
- The internal condyle of the femur is most often affected
- Possible damage to the ankle and elbow joints
Causes and risk factors
There is no single reason. The main hypothesis is repeated microtrauma of a bone area during sports activity against the background of the peculiarities of the blood supply to this area. The axis of the limb, increased load on one part of the joint, and early sports specialization without sufficient recovery play a role. Not everyone has a history of direct severe trauma. Sometimes lesions are found in several joints, which indicates a systemic predisposition.
- Football, basketball, gymnastics, wrestling, tennis classes
- Age 10–20 years, period of active growth
- Male gender
- Varus or valgus deformity of the legs
- Repeated microtraumas without proper rest
- Familial cases and multi-joint involvement
Symptoms
At an early stage, a person complains of vague pain deep in the joint, which appears after exercise and goes away with rest. There may be some swelling and a feeling of stiffness. As the fragment separates, clicks, crunching and episodes of jamming are added, when the joint is fixed in a half-bent position, and after a few minutes it suddenly releases. Such blockades are an alarming sign indicating a moving fragment.
- Aching pain in the joint after exercise
- Swelling that gets worse in the evening
- Clicking and crunching noises when moving
- Episodes of joint blockade
- Feeling of instability, shaking
- Lameness and gentle gait
Diagnostics
They start with an x-ray of the joint in two projections; for the knee, they additionally do a tunnel installation - it better shows the femoral condyles. X-ray reveals a focus of clearing with a dense fragment, but does not answer the main question about stability. This is solved by MRI: by the swelling of the bone marrow and the strip of fluid around the fragment, the doctor understands whether it is holding on or has already peeled off. A CT scan shows the bone part of the defect in detail and helps plan the operation. If the second joint is affected, both sides are examined.
- X-ray of the joint in two projections
- MRI of the affected joint is a key study
- CT for bone defect assessment and surgical planning
- Ultrasound of the joint to assess effusion
- Examination with tests for blockade and instability
Treatment
In children and adolescents with open growth plates and a stable lesion, they begin with conservative treatment: limit axial load, exclude sports for several months, use crutches and an orthosis if necessary, and simultaneously engage in physical therapy to preserve muscles. A follow-up MRI shows whether healing is progressing. In case of an unstable fragment, a loose body, or no effect in adults, arthroscopic surgery is performed: the fragment is fixed with screws, the base of the lesion is tunneled, or the defect is replaced with its own osteochondral columns. After surgery, step-by-step rehabilitation is required - without it, the result is lost.
- Unloading the joint and giving up sports for the period prescribed by the doctor
- Therapeutic exercise and strengthening of thigh muscles
- Arthroscopic fragment fixation
- Removing the loose body and processing the stock
- Osteochondral autoplasty for large defects
- Return to sports only after a doctor's permission