There are two types of cartilage inside the knee. Both can be injured in different ways. The lateral and medial menisci are C-shaped and made of tough, rubbery fibrocartilage. They are located within the knee joint and function like washers, helping with shock absorption and aiding joint stability. Joint (articular) cartilage is the solid layer of cartilage that covers the bony surfaces inside the knee joint (between the tibia and femur, and between the kneecap and its groove on the femur).
Tell me more about knee cartilage.
Meniscal injuries are generally classed as sudden onset (acute) or wear and tear (degenerative). Joint (articular) cartilage provides a shiny, smooth, friction-free surface for the joint to glide. It also protects the underlying bone. It can be injured through traumatic injury, wear and tear, or by other conditions. Injuries around growth areas (eg, the epiphyseal plate and apophysis) can occur in children and adolescents.
What causes a knee cartilage injury?
Injuries to the menisci generally fall into two categories:
Injuries to the articular cartilage also occur in several ways:
Trauma or acute injury
If a person’s knee sustains a high force injury (eg, a fall from height or a heavy awkward landing in sport), this can result in chipping of the articular cartilage or a cartilage compression injury.
Via a patellar dislocation
Sometimes when a person sustains a patellar (kneecap) dislocation, a piece of articular cartilage on the surface of the patella can be chipped or fractured.
Conditions such as osteochondritis dissecans (OCD)
This is a condition mainly found in adolescents and young adults in which a small patch of bone beneath a portion of articular cartilage develops a lesion. This is considered a stress injury to the developing articular cartilage, and can cause the cartilage and bone piece to weaken and occasionally separate from the bone beneath it. With unloading, the OCD lesion can heal without any further consequence, but with repeated and sustained loading, the lesion doesn’t heal and can became separated and displaced and lead to ‘locking’ and clicking’ of the knee.
Wear and tear (OA)
Joint surfaces can accumulate injury via the process of ageing. Wear and tear of the articular cartilage can occur earlier in people who have had previous traumatic knee injuries, highly physical jobs, or who have movement patterns (biomechanics) that put extra stress on areas of joint cartilage.
Related to growth and load, this is where the cartilage is transitioning to bone at the tendon insertion, with injury also in the adjacent tendon and bone. Most common around the knee is the attachment of the patella tendon at the tibial tub (Osgood-Schlatters disease) or the bottom of the kneecap.
How do I know if I have a knee cartilage injury?
Your physiotherapist, doctor or surgeon can examine your knee to accurately diagnose your knee symptoms. They may also refer you for imaging (eg, X-ray, ultrasound or MRI) if required. Symptoms of knee cartilage injuries often include:
In acute tears, a person generally remembers the particular movement that caused the injury. It’s often felt as sharp pain and an inability to continue activity. In degenerative tears, there may not be a specific incident. Depending on the severity of the meniscal tear, these injuries are often associated with: mild to moderate swelling; localised, sharp knee joint pain with walking, twisting and turning; reduced knee bending and straightening (‘locking’); clicking or catching sensations, which may or may not be painful; and they may also cause aching at night.
Bucket-handle meniscal injuries are a particular (severe) form of acute meniscal injury where a torn portion folds and gets stuck within the joint. This causes the knee to become locked in a certain position.
Articular cartilage injuries
Symptoms vary depending on the location of the injury within the knee along with its severity and how it occurred.
Those that arise from trauma are generally very painful, especially when trying to weight-bear or in particular joint positions. They are often quite swollen and have restricted range of movement.
Articular cartilage injuries that occur due to OCD can have variable symptoms such as limping due to pain or pain with higher impact sporting activities. If an OCD lesion is more significant, the knee may swell, click, clunk and have limited movement.
Wear and tear (OA) type of articular cartilage injuries can cause more gradual onset of symptoms. They generally lead to swelling and pain in a portion of the knee, often with long periods of activity. The knee may ache at night or be stiff after periods of rest. When OA is more advanced, the knee might also change in appearance (eg, ‘bow leg’ or ‘knock knee’, depending on the location of the wear and tear). For more information, read about knee osteoarthritis.
How can physiotherapy help with knee cartilage injuries?
Physiotherapy plays an important role in the management of knee cartilage injuries. Treatment will vary depending on the type of cartilage injury an individual has, though commonly includes exercises to optimise knee bending and straightening, exercises to improve muscle strength and coordination of leg position, and advice about general activity and pain management.
The management of meniscal injuries varies between acute and degenerative meniscal tears, and the type of symptoms experienced by the individual.
In the first few weeks following an acute meniscal injury, the knee is often quite inflamed. Your physiotherpist can help you settle your knee using strategies such as ice, activity reduction and gentle stretches, while doing simple pain-free strength exercises to prevent muscle weakness developing. Once your knee has settled, your physiotherapist can guide you through a rehabilitation program of exercises and progressive return to full activity.
If the knee continues to have significant mechanical symptoms (painful clicking, locking or catching) once the initial inflammatory period has settled, and despite a structured program of physiotherapy, your physiotherapist may recommend you consult a sports doctor or orthopaedic surgeon.
In the case of a bucket-handle meniscal tear, early surgical repair of the meniscus is required to allow the joint to regain movement and to preserve the meniscus. Following such surgery, physiotherapy rehabilitation is essential to safely regain full strength and knee function.
Articular cartilage injuries
Physiotherapy is recommended for the management of knee osteoarthritis.
In the case of traumatic articular cartilage injuries, often the opinion of a knee surgeon is required. If surgery is needed, physiotherapy is very important post-operatively to help you fully rehabilitate and return to activity safely.
If the cartilage injury is mainly in the patellofemoral joint (the articular surfaces of the kneecap and its groove), physiotherapy generally includes exercises to strengthen the muscles around the knee, hip and lower leg, and improve the coordination of limb movement. This helps the kneecap track better in its groove, reducing load on the area of injury, and helping to minimise further degeneration.
In stable OCD lesions, physiotherapists can provide advice on activity modification and rest while also prescribing exercises to maintain knee strength and flexibility. This is important to allow the cartilage and bone to heal. Physiotherapy also plays a significant role in rehabilitating a person’s knee after surgery if they have an unstable OCD lesion.
In children with overuse injury (apophysitis), which typically occurs after repetitive activities of the muscles attached to the growth cartilage (apophysis), your physiotherapist can help with managing loading, activity modification, an exercise program, taping and advice on self-massage.
How effective is physiotherapy for treating knee cartilage injuries?
Physiotherapy for meniscal injuries
In the case of degenerative meniscal tears, there is a growing amount of evidence to show that physiotherapy, including specific strength and control exercises, is as effective as keyhole knee surgery (arthroscopy). A study of a 12-week supervised knee strength and neuromuscular control (stability and leg position) exercise program compared to knee arthroscopy (including trimming the torn part of the meniscus) demonstrated no difference in pain, function or quality of life between the groups at two years. At three months following the trial, the exercise group showed improvements in quadriceps muscle strength compared to the arthroscopy group.
One significant review concluded that for degenerative meniscal tears, the first-line treatment should be non-operative. This should include simple pain medications (as recommended by your GP) and physiotherapy in order to improve the mechanics of the knee joint and manage pain. This has been shown to be less-invasive and to have fewer risks than arthroscopic surgery, while being equally effective. This study advises that arthroscopic surgery to trim degenerative meniscal tears should only be used as a last resort for people who have not experienced improvements with a comprehensive well-structured physiotherapy exercise program.
Physiotherapy for knee OA
Many studies have investigated the effect of physiotherapy in knee OA and have shown good results. You can read about them on the knee osteoarthritis page.
What can I do at home?
Once your knee has been assessed by your physiotherapist, GP or surgeon, a home treatment plan can be individually tailored to address the contributing factors to your knee injury. Home management plans for people with cartilage injuries generally include:
How long until I feel better?
This is very dependent on the type and severity of cartilage injury that the individual person has in their knee joint. Some people will experience a reduction or resolution of their symptoms within a few weeks or months with appropriate physiotherapy treatment, though others will need to manage their knee symptoms long-term. Your physiotherapist can give you specific advice about what you can expect with your knee condition and how to safely keep active in the meantime. They can also discuss with you whether you might need the opinion of a sports doctor or a surgeon if your knee cartilage injury doesn’t respond to physiotherapy treatment, or if your injury is more significant.