Overview
A chondral defect of the knee is an injury or breakdown of the articular cartilage that covers the ends of the bones inside the knee joint. Because cartilage helps the joint glide smoothly and absorb impact, a defect can lead to pain with activity, swelling or irritation, and stiffness. Symptoms can fluctuate depending on how deep or unstable the cartilage injury is and how much weight-bearing you do. Over time, an untreated cartilage defect can contribute to ongoing joint irritation and, in some people, to early degenerative changes.
Symptoms
Pain is often felt in a specific area of the knee, commonly with running, squatting, climbing stairs, or prolonged standing. Some people notice swelling after activity, stiffness after sitting, or a catching/locking sensation. You may also feel reduced tolerance for impact activities and a sense that the knee does not feel stable or smooth. Symptoms can worsen with twisting motions, deep knee bending, or long days on your feet.
Causes
Chondral defects most often follow an injury such as a direct blow to the knee, a twisting injury, or repetitive overloading that gradually irritates cartilage. The defect can also develop after prior knee instability episodes, altered mechanics, or inflammation in the joint. Even without a major injury, cartilage can deteriorate when forces exceed what the tissue can tolerate over time.
Risk Factors
Higher risk is seen in people with a history of knee trauma, meniscal injury, or recurrent knee instability. Poor lower-limb alignment, weak hip or thigh muscles, increased body weight, and sudden increases in training load can increase stress on cartilage. Certain activities that involve impact, deep bending, or frequent pivoting can also raise risk by repeatedly stressing the affected cartilage area.
Prevention
You can reduce risk by avoiding sudden spikes in running or jumping volume and by building strength in the hips and thighs to improve knee alignment. Using technique changes for squats, lunges, and landing mechanics can lower cartilage stress. Maintaining a healthy weight and choosing lower-impact conditioning during flare-ups can also help protect the joint. If you play sports, addressing training errors and any biomechanical issues early can reduce the chance of recurrent cartilage overload.
How the Diagnosis Is Evaluated
Clinicians usually start with a detailed history of injury timing, location of pain, swelling pattern, and activities that trigger symptoms. A physical exam may look for joint line tenderness, pain with specific knee movements, swelling, range-of-motion limits, and signs of maltracking or instability. Imaging typically begins with X-rays to rule out other causes such as arthritis or loose bodies; cartilage injury is often better evaluated with MRI when symptoms persist or the diagnosis is unclear. Not every patient needs advanced imaging immediately if symptoms are mild and improve with conservative care.
Nonsurgical Treatment Options
Treatment focuses on reducing pain and inflammation, improving knee mechanics, and allowing the cartilage environment to calm down. Activity modification and physical therapy are often the foundation, including strengthening of the quadriceps and hip muscles, flexibility work, and neuromuscular training to improve tracking. Anti-inflammatory and pain-relieving medications such as NSAIDs, when appropriate for you, can help control symptoms during flare-ups. A corticosteroid injection may be used in some cases to reduce inflammatory pain, while platelet rich plasma (PRP) injections and hyaluronic acid injections (including orthovisc) are sometimes considered to help symptoms in selected patients. Bracing, footwear adjustments, and short-term assistive strategies (like limiting impact) can further reduce stress on the defect. A clinician may also recommend a home exercise program and, if needed, targeted injections only after confirming the pain generator matches the suspected cartilage area.
When to Seek Medical Attention
Seek prompt medical attention if you cannot bear weight, if there is significant or rapidly increasing swelling, or if you experience a true locking episode where the knee will not move. Get urgent care if you have fever, redness and warmth in the joint, or severe pain that is rapidly worsening. Contact a clinician sooner if symptoms persist beyond a few weeks despite conservative measures, if you feel progressive instability, or if you develop new numbness, weakness, or symptoms extending below the knee.
Frequently Asked Questions
It often causes localized pain with activity, stiffness, and sometimes swelling or catching sensations depending on the size and stability of the cartilage injury.
Cartilage injuries are commonly assessed with MRI when symptoms persist or the diagnosis is uncertain, because X-rays mainly show bone alignment and arthritis.
Next Steps
If your knee pain is localized and activity-related or not improving with basic measures, schedule a clinical evaluation to confirm the pain source and assess alignment, strength, and stability. In the meantime, consider relative rest from impact activities, gentle range-of-motion, and a gradual strengthening program as tolerated.