Osteochondritis dissecans (OCD) is a joint disorder affecting the bone just beneath the cartilage surface, commonly seen in young, growing individuals. This condition involves damage where a segment of bone and its overlying cartilage partially or fully separates from the rest of the bone within a joint. OCD is a concern among adolescents who participate in competitive sports, often leading to chronic joint pain and dysfunction.
Defining the Condition
Osteochondritis dissecans is defined by a focal area of subchondral bone undergoing necrosis, or tissue death, due to a lack of blood supply. Subchondral bone is the layer directly below the joint cartilage. This interruption weakens the affected segment of bone, leading to a structural defect, and the overlying articular cartilage loses its necessary bony support.
As the condition progresses, the weakened bone and cartilage segment begins to separate from the surrounding healthy bone, creating a lesion. Lesions are classified by their stability, determined by the integrity of the overlying cartilage. A stable lesion means the fragment is still held firmly in place by intact cartilage, despite the underlying bone damage.
An unstable lesion occurs when the cartilage fissures, allowing the bone fragment to loosen or detach completely. If the fragment breaks off and moves freely within the joint space, it is referred to as a “loose body.” This separation causes mechanical interference within the joint, leading to more pronounced symptoms. The stability of the lesion is a primary factor in determining the appropriate treatment strategy.
Common Locations and Affected Populations
The condition most frequently affects the knee, accounting for approximately 75% of all cases, specifically on the lateral aspect of the medial femoral condyle. Other common sites include the elbow, particularly the capitellum, and the ankle, focusing on the talus bone. These locations are subject to significant stress and compression during physical activity.
While the exact cause of osteochondritis is not fully established, repetitive microtrauma and stress to the joint are strongly suspected contributing factors. This is particularly relevant for young athletes involved in sports requiring jumping, running, or throwing, which place high compressive forces on the joints. OCD primarily affects adolescents and young adults between the ages of 10 and 20, especially those who are skeletally immature with open growth plates.
Boys are generally affected more frequently than girls, though the incidence in female athletes is increasing as competitive sports participation grows. The rapid skeletal growth during adolescence, combined with repetitive high-impact activity, makes this age group uniquely susceptible. Lesions found in younger patients with open growth plates, known as juvenile OCD, typically have a better potential for healing compared to those in skeletally mature patients.
Recognizing the Signs
The presentation of osteochondritis dissecans varies, but the most common symptom is chronic, poorly localized joint pain that worsens with physical activity. This pain is often described as a dull ache and can persist for months or even years before diagnosis. Early signs may be subtle, especially if the lesion is small and stable.
As the lesion advances, patients may experience additional symptoms, including swelling, tenderness, and joint stiffness following activity. A reduced range of motion in the affected joint is also a noticeable sign. If the fragment becomes unstable or detaches, mechanical symptoms are likely to develop.
These mechanical symptoms include clicking, catching, or locking of the joint, which occur when the loose fragment interferes with normal joint movement. Patients may also report a feeling that the joint is “giving way” or is unstable. The presence of these symptoms often indicates a more advanced stage of the condition, requiring prompt medical attention.
Treatment Approaches
Management of osteochondritis dissecans is tailored to the patient’s skeletal maturity, the size and location of the lesion, and its stability. For stable lesions in skeletally immature patients, non-surgical treatment is the preferred initial approach, aiming to promote natural healing of the bone.
Non-surgical management involves a period of rest and activity modification, requiring the patient to avoid high-impact and strenuous activities. Immobilization using a brace or cast may be necessary for several weeks to protect the joint, often combined with partial or non-weight-bearing using crutches. Once pain subsides, physical therapy is initiated to restore strength and range of motion.
Surgical intervention is necessary for unstable lesions, those that fail to heal after conservative treatment, or those presenting with a detached fragment. Surgical procedures are designed to either restore blood flow to the damaged area or secure the fragment back into place. Techniques like retro-articular drilling create channels in the bone to stimulate circulation and promote healing without disturbing the joint surface.
Surgical Procedures
For unstable fragments that can be salvaged, internal fixation secures the piece back to the parent bone using specialized screws or pins. If the fragment is unsalvageable or if there is a significant cartilage defect, more advanced reconstructive procedures may be performed. These include:
- Osteochondral autograft transfer (OAT), which uses healthy bone and cartilage plugs from a non-weight-bearing area of the joint to fill the defect.
- Microfracture, which stimulates the growth of fibrocartilage to cover the exposed bone.