Knee tendinitis (also called tendonitis) is the inflamed and irritated condition of tendons in the knee, due to overuse or repetitive actions. As a result, this condition is mostly observed in athletes such as runners, jumpers, and basketball/ volleyball players.
Tendinitis or tendonitis is not to be confused with tendinosis, which is a chronic condition where, instead of the tendon becoming inflamed, it becomes gradually thicker and develops microscopic tears progressively. Both conditions have similar symptoms, however they are treated differently.
A tendon is the flexible, fibrous band of tissue that connects muscles to bones. Tendons have a surrounding vascular tissue lining, to provide blood supply and nutrition to the tendon. Tendons are very important in every movement because they transmit the pull of each muscle to the bone.
The knee joint has a complex network of tendons and ligaments. The patellar tendon connects the patella (kneecap) to the shin bone. The patellar tendon, kneecap quadriceps tendon and the popliteus tendon, are all part of the extensor mechanism of the knee, which allow the knee to extend, straighten out, and provide strength for a kicking motion.
Types of Knee Tendinitis
- Patellar tendinitis (also known as Jumper’s Knee): inflammation of the patellar tendon just below the kneecap. This is usually found in athletes who repeatedly jump or land heavily on their feet, causing stress on the patellar tendon.
- Quadriceps tendinitis: inflammation of the patellar tendon just above the kneecap. This condition is related to sports activities involving rapid acceleration and deceleration.
- Popliteus tendinitis: inflammation of the popliteus tendon on the lateral epicondyle of the femur bone. Running uphill or downhill repeatedly is known to cause this condition.
The patellar variety is the most common, so Patellar Tendonitis or Jumper’s Knee is used synonymously with Knee Tendonitis.
What causes Knee Tendinitis?
- Knee tendinitis is caused by repetitive stress, motion or overuse injuries in the affected tendon. Repetitive actions cause repeated muscle contraction and tendon elongation, and the stress eventually leads to microscopic tears, which then develop into larger tears and inflammation.
- With age and overuse, tendons become less flexible with age, and more prone to injury. As a result, tendonitis occurs more often in persons of advancing age.
- Both athletes (runners, jumpers) and workers (such as gardeners, carpenters) who perform activities that require repetitive motions or place stress on the knee joints are at higher risk for developing tendonitis.
- Infection, arthritis, gout, thyroid disease, and diabetes can also cause tendonitis.
What are the main symptoms?
- Pain directly over the patellar tendon.
- Tender and swollen knee.
- Movement of the knee may cause a crunching sensation.
- Aggravated pain with activities, especially jumping or kneeling.
How is it diagnosed?
Physical examination and X-ray tests are usually performed to diagnose knee tendonitis. MRI may also be used to look inflammation or partial tears within the tendon.
How is it treated?
Rest is usually the most helpful treatment to ease the symptoms, and allow the tissue to recover from the stress. Conservative treatment applied soon after symptoms are observed, can prevent worsening of the condition. Left untreated or in elderly people, tendonitis heals more slowly and usually progresses to a chronic condition (tendinosis).
The common methods of treating knee tendonitis are:
- Rest and restriction of the offending activity·
- Ice or heat treatment on the knee joint
- Use of knee brace to support the knee joint
- Self-massage with heat-inducing creams
- Non-steroidal anti-inflammatory drugs (NSAIDs) for short-term pain relief.
- Corticosteroid injections at the knee joint. However, this can cause long-term damage to the joint, so should be used with caution.
- Platelet-Rich Plasma injection is found to be more beneficial than steroid injections
- Physiotherapy and sufficient stretching before activity are often beneficial
- Surgery is indicated only in very severe cases, where the tendon is completely torn.