Overview
Osteochondritis dissecans (OCD) is a joint condition in which a small area of bone underneath the cartilage does not get enough blood, causing the cartilage surface to become painful and, in some cases, unstable or partially detached. It most often affects the knee, especially around the femoral condyles, but it can occur in other joints. The cartilage over the weakened bone can wear unevenly, which may lead to pain, swelling, stiffness, and episodes of the knee catching or giving way. In children and adolescents, healing is sometimes possible when the lesion is stable and stress is reduced.
Symptoms
Patients often notice vague or sharp pain in the affected knee, sometimes along with swelling after activity. Symptoms may worsen with running, jumping, squatting, or climbing stairs, and they may improve with rest. Some people experience stiffness after sitting, reduced ability to fully bend or straighten the knee, or mechanical symptoms such as catching, locking, or a feeling that the knee might "give way." When the fragment becomes unstable, pain can be more persistent and function can decline.
Causes
Osteochondritis dissecans usually develops after repeated stress or a single injury that disrupts blood supply to a small area of bone beneath the cartilage. Over time, the bone and cartilage interface may weaken, leading to cartilage damage and possible fragmentation. The exact cause of impaired healing varies, but mechanical overload and susceptibility to microtrauma are common contributors.
Risk Factors
OCD is more common in children, adolescents, and young athletes because their growth plates and developing cartilage-bone interface may be more vulnerable. Participation in high-impact sports, frequent jumping or pivoting, and training errors that allow excessive load without adequate recovery can increase risk. A prior knee injury and having structural or alignment factors that increase joint stress may also contribute.
Prevention
You can reduce risk by avoiding training spikes and ensuring gradual progression in intensity, volume, and impact. If knee pain starts during sports, early activity modification and temporary reduction in pounding or pivoting can help protect the joint while symptoms settle. Building hip and thigh strength, maintaining flexibility, and using good movement mechanics can lower repetitive stress on the cartilage surface. Maintaining a healthy weight and using appropriate footwear and surfaces can further reduce cumulative load.
How the Diagnosis Is Evaluated
Clinicians start with a history of pain timing, sports or injury triggers, swelling, and any catching or locking sensations. A physical exam focuses on joint tenderness, effusion, range of motion limits, and provocative maneuvers, and it helps determine whether the lesion seems stable or mechanically unstable. X-rays are often used first to look for bone changes, but MRI is commonly the test of choice to assess cartilage integrity and lesion stability; not every patient needs advanced imaging immediately. In select cases, ultrasound for effusion or CT for bony detail may be considered, depending on symptoms and initial imaging.
Nonsurgical Treatment Options
Non-surgical care aims to reduce pain, protect the cartilage-bone lesion, and give it the best chance to heal or remain stable. Treatment often includes activity modification, reduced weight-bearing or protected loading (sometimes with a brace or crutches), and anti-inflammatory or pain-control medications as appropriate. Physical therapy is commonly recommended to restore controlled range of motion and build strength and stability around the knee, especially the quadriceps and hip musculature. For persistent symptoms, clinicians may consider intra-articular corticosteroid injections for short-term pain relief, while recognizing that they do not "repair" cartilage. Some patients also try biologic or cartilage-supportive injections such as platelet rich plasma (PRP) or hyaluronic acid (including orthovisc), though results vary by lesion characteristics and the evidence is mixed; adipose-derived or stem-cell based injections are generally considered more experimental and are not a guaranteed solution.
When to Seek Medical Attention
Seek prompt medical evaluation if knee pain persists beyond a couple of weeks despite rest, if swelling is recurrent, or if you have catching, locking, or a feeling of instability. Get urgent care if you cannot bear weight, have a significant new injury with rapid swelling, or develop fever and marked redness over the joint. Also seek immediate attention if symptoms are rapidly worsening or if you have severe weakness or inability to move the knee normally.
Frequently Asked Questions
It is a condition where a piece of bone under the cartilage becomes stressed and may lose stability, causing knee pain and sometimes mechanical catching.
Imaging-especially MRI-helps assess whether the cartilage surface is intact and whether there are signs of instability.
High-impact loading like running, jumping, and deep squats is often limited until pain settles and strength and mechanics improve.
Next Steps
If you suspect osteochondritis dissecans because of persistent knee pain, swelling, or catching/locking, arrange an evaluation with an orthopedic clinician or sports medicine specialist. Early assessment and load management can improve outcomes, especially in younger patients with potentially stable lesions. Follow the recommended activity limits and physical therapy plan, and ask whether MRI is appropriate to determine stability.