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Knee

Chondral Defects of Knee (Knee Cartilage Injuries)

Overview of Knee Cartilage Anatomy

The knee joint is made up of three main bones:

  • Femur (thighbone)
  • Tibia (shinbone)
  • Patella (kneecap)

Between these bones lies articular cartilage, a smooth, white tissue that covers the ends of bones and allows them to glide over each other without friction. The meniscus, a different type of cartilage, acts as a shock absorber between the femur and tibia. The meniscus helps to protect or “pad” the articular cartilage

Types of Cartilage in the Knee:

  • Articular cartilage – covers bone surfaces, enabling smooth joint motion.
  • Meniscus cartilage – C-shaped wedges between the femur and tibia, stabilizing the joint and absorbing shock.

Knee cartilage can be damaged by:

  • Acute trauma – sudden impact or twisting injury (e.g., sports injuries).
  • Degenerative changes – from osteoarthritis or aging.
  • Repetitive stress – overuse or chronic joint overload.
  • Previous surgery or injury – e.g., meniscus removal (ie., meniscectomy), ligament tears.

  • Pain – often worsened by increased activity.
  • Swelling or joint effusion – inflammation/ fluid accumulating in the knee. Often a reaction to the presence of damaged cartilage
  • Locking or catching – due to loose cartilage fragments.
  • Stiffness or limited range of motion
  • Instability or a feeling of the knee “giving way”. Often secondary to muscle weakness from as the knee tries to compensate from cartilage damage

Diagnosis involves a combination of:

  • History and physical exam
  • Imaging tests:
    • MRI – best for visualizing cartilage damage.
    • X-rays – assess joint alignment, joint health and fractures but don’t show cartilage directly.
  • Arthroscopy – minimally invasive procedure that allows direct visualization of the cartilage.

Non-Surgical Treatments

  • Best for mild to moderate cartilage deterioration or injury and patients not ready for surgery.
  • Activity modification – avoid high-impact activities (squatting, jumping, running) early on
  • Physical therapy – to improve joint strength and flexibility and help with return to activity or sport
  • Anti-inflammatory medications – such as NSAIDs.
  • Weight loss – if overweight, to reduce joint stress.
  • Injections:
    • Corticosteroids – reduce inflammation and pain.
    • Hyaluronic acid – lubricates the joint.
    • Platelet-rich plasma (PRP) – may promote healing and provide symptom relief in mild to moderate cases
    • Bone Marrow Aspirate Concentrate (BMAC) – similar to PRP. Currently, less studied

Considered when non-surgical options fail or when cartilage loss is severe.

  • Debridement and chondroplasty – smoothing rough cartilage to limit repetitive impact or further cartilage wear
  • Microfracture – creating tiny holes in bone to stimulate new cartilage growth.
  • Osteochondral autograft transfer (OATS) – transplanting cartilage from another area of the joint to the damaged area.
  • Osteochondral allograft transplant – transplanting donor cartilage tissue to the damaged area of the knee. Used for larger cartilage injuries
  • Autologous chondrocyte implantation (ACI) – growing a patient’s own cartilage cells in a lab and re-implanting them.
    • Two stage procedure
  • Realignment (osteotomy) – to offload pressure from the damaged area.
  • Partial or total knee replacement – in advanced cases with arthritis.

  • Non-surgical care can reduce pain and improve function, but may not restore cartilage.
  • Surgical outcomes vary:
    • Microfracture: good short-term results, may degrade over time.
    • OATS or allograft: better for focal (localized) damage in younger patients of variable sizes. Favorable long term data
    • ACI: promising for larger lesions, especially in active adults.
    • Knee replacement: best for widespread damage or advanced arthritis.

Rehabilitation is critical:

  • Post-op rehab can take 4–12 months, depending on the procedure.
  • Long-term outcomes depend on age, activity level, extent of injury, and adherence to rehab.

Seek evaluation if you experience:

  • Persistent or worsening knee pain.
  • Swelling or instability after activity.
  • Locking or clicking of the knee.
  • Inability to return to sports or normal activities after injury.

Knee cartilage injuries are a common source of pain, swelling, and functional limitation and can affect people of all ages and activity levels. Because cartilage plays a critical role in smooth joint movement and shock absorption, damage to this tissue—whether from acute injury, overuse, or degenerative change—can significantly impact daily activities and athletic performance. Early recognition of symptoms and accurate diagnosis are essential to guide appropriate treatment and prevent further joint deterioration.

Treatment for knee cartilage injuries ranges from non-surgical options such as activity modification, physical therapy, medications, and injections to advanced surgical techniques aimed at repairing, restoring, or replacing damaged cartilage. While non-operative care can effectively manage symptoms for many patients, surgical intervention may be necessary for those with persistent pain, mechanical symptoms, or larger defects. Outcomes are influenced by factors such as patient age, activity level, size and location of the injury, and adherence to rehabilitation.

With advances in cartilage restoration techniques and individualized treatment planning, many patients can achieve meaningful pain relief, improved function, and a return to desired activities. Ongoing communication with an orthopedic specialist and commitment to rehabilitation are key components of successful long-term outcomes in managing knee cartilage injuries.

At a Glance

Dr. Hasani Swindell

  • Fellowship-Trained Sports Medicine Specialist
  • Board-Certified Orthopedic Surgeon
  • Summa Cum Laude Graduate from the University of Pittsburgh
  • Medical Degree from Columbia University
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