Chondral lesions are a specific type of cartilage injury that involves a focal loss of cartilage, usually due to mechanical wear and tear or traumatic injury. Knee cartilage or lesion could lead to further degeneration and joint damage if left untreated. Chondral knee injuries are particularly tricky due to the slow healing nature of cartilage as it has no blood supply. Additionally, cartilage injury/chondral lesions do not occur in isolation and are often accompanied by ACL injuries.

Cartilage injuries or chondral lesions are graded based on the severity of the damage to the cartilage, such as:

• Grade 1: softening or swelling of the cartilage and superficial lesion also known as blisters. 
• Grade 2: partial thickness or defect with fissures (cracks) that do not reach the subchondral bone. Cartilage appears “shredded”. 
• Grade 3: full-thickness damage to the cartilage bulging over the lesion, and impact on the subchondral bone is present. 
• Grade 4: exposed bone due to complete loss of the cartilage layer.

• Trauma or injury to the knee joint
• Continuous stress on the knee joint
• Degenerative changes due to ageing or osteoarthritis
• Malalignment or abnormal tracking of the patella (kneecap)
• Inflammatory joint diseases like rheumatoid arthritis and osteoarthritis

• A “popping” or “grinding” sound when moving the affected joint
• Swelling and stiffness
• Instability or weakness in the joint
• Limited range of motion
• Severe pain in the affected joint with prolonged walking or climbing up stairs
• Feeling a catching or locking sensation in the joint
• Unable to bear weight on the affected area

Pain may be felt during movement of the joint, and there may be swelling, stiffness, and a grinding or popping sensation in the joint. Pain may also be felt at rest, particularly in more advanced cases.

Risk factors include:

• Age: as we age, the cartilage in our knees becomes more brittle and susceptible to damage.
• Athletes / hobbyists: generally young people may be susceptible if they participate in activities which cause strain on the knee such as runners. 
• Trauma: forceful impacts to the knee can damage the cartilage, which could lead to a chondral ulcer.
• Genetics: some people are born predisposed to cartilage injuries due to their genetics.
• Obesity: being overweight can put extra stress on the knees and increase the chances of developing cartilage injuries.
• Medical history: people with misaligned knees or other joint conditions are more susceptible to developing cartilage injuries.

• Physical examination and medical history: inform your orthopaedist of the potential activities that may have led to an injury such as trauma, exercise, or sports. Physically the area of injury will be examined and several motion tests will be conducted to review the injury.
• Imaging tests: magnetic resonance imaging (MRI) or dynamic ultrasonography would be required to visualise the extent of the damage to the cartilage and to determine if there are other bony defects such as cysts or swelling of the bone. An x-ray may be conducted if osteoarthritis is suspected and to capture any narrowing of the joint. 
• Diagnostic arthroscopy: arthroscopy, a minimally invasive procedure where a small camera is inserted into the knee joint to visualise the structures inside.

• Rest: you would be advised to observe complete rest, while icing the affected area, to relieve pain and reduce swelling.
• Medications: non-steroidal anti-inflammatory drugs (NSAIDs) and painkillers are commonly prescribed as the first course of treatment to reduce inflammation and manage pain.
• Injections: corticosteroid injections may be used to manage pain associated with chondral lesions.
• Brace: to reduce movement of the joint and allow the cartilage to heal.
• Crutches: to limit placing weight on the affected knee.
• Physiotherapy: upon discontinuation of the use of the brace, an active range of motion exercise would be administered via physiotherapy to regain mobility and strengthen muscle.
• Surgery: surgery can vary from a microfracture to an osteoarticular allograft. The surgery employed will depend on the grade of the cartilage injury.