Quadriceps Tendonitis · What It Is, Causes, Symptoms, Treatment, and More

Quadriceps tendonitis, also known as “jumper’s knee,” is a musculoskeletal condition characterized by inflammation of the quadriceps tendon. The quadriceps tendon connects the quadriceps muscles located at the front of the thigh to the patella, or kneecap. The patellar tendon then connects the patella to the tibia, or shinbone. Collectively, the quadriceps tendon and patellar tendon coordinate the quadriceps muscles, which help straighten the knee and absorb the shock of heel strike. Both tendons also stabilize the hip during bent-knee positions, which allows individuals to participate in sports and activities that require walking, running, and jumping such as volleyball and basketball. 

Quadriceps tendonitis is often associated with overuse injury, and knee pain and swelling that is aggravated with activities that involve bending or straightening the knee, such as climbing stairs.  Chronic quadriceps tendonitis may lead to quadriceps tendinopathy (i.e., degeneration of the quadriceps tendon). In the early stages of quadriceps tendinopathy, micro-trauma to the tendon causes inflammation and with repeated stress, if the rate of breakdown exceeds the body’s ability to repair the injury, then structural degradation and degeneration of the tendon can occur.

Quadriceps tendonitis is caused by recurrent micro-trauma to the quadriceps tendon, which activates the body’s inflammatory and repair pathways. When the tendon is subjected to excess load or stress, the cross-linked collagen fibers that make up the tendon begin to break, which initiates the degenerative process. Matrix metalloproteinases (i.e., proteins that degrade the collagen fibers), inflammatory cytokines (i.e., proteins involved in cell signaling), and prostaglandins (i.e., a hormone-like substance that promotes inflammation) are all involved in the pathogenesis of quadriceps tendinopathy. It is also hypothesized that the body may undergo neovascularization, a compensatory mechanism in which new, abnormal vessels form, in an attempt to increase the blood supply to the tendon. Unfortunately, these small vessels contain many branches that are non-functional (i.e., unable to deliver oxygen and nutrients), thereby worsening tendinopathy.

Quadriceps tendonitis can be caused by overuse injury which is often seen in sports that involve jumping, running, or quick directional changes (e.g., basketball, soccer, volleyball); imbalanced or weak quadriceps muscles, which can increase the stress on the quadriceps tendon; or a sudden increase in duration or intensity of physical activity. 

Signs and symptoms of quadriceps tendonitis include pain that is located above the patella and is exacerbated during exercises that involve bending and/or straightening the knee (e.g., climbing stairs). There may also be swelling around the kneecap, tenderness to palpation of the quadriceps tendon, or knee stiffness with prolonged inactivity. 

The diagnosis of quadriceps tendonitis is clinical and begins with a thorough review of symptoms and history that is focused on the individual’s degree and duration of physical activity, quality of pain, and any alleviating or aggravating factors. A focused physical exam can assess strength and function of the quadriceps muscles, and range of motion in the knee. Although imaging modalities are not necessary for the diagnosis, they may be helpful in excluding other musculoskeletal pathologies that can present similarly. For example, computed tomography (CT) or magnetic resonance imaging (MRI) of the knee can exclude any acute bony injuries, meniscus tears, or ligament injuries. Radiographic changes seen in quadriceps tendonitis include tendon calcifications and increased density within the patellar tendon matrix.

Quadriceps tendonitis is treated with a combination of non-pharmacologic and pharmacologic modalities. Individuals are advised to undergo an initial period of rest and icing of the affected area if swollen, with a gradual increase to normal activity. A knee brace may also be recommended to help support and protect the knee. After the acute phase of injury, rehabilitative and physical therapy may also be helpful in increasing the flexibility and mobility of the quadriceps muscles. For example, a physical therapist may recommend strengthening exercises such as heavy, slow resistance training that aims to gradually increase the load exerted on the quadriceps and patellar tendons over time. Non-steroidal anti-inflammatory medications (i.e., ibuprofen) may be used on a short-term basis to treat the pain and inflammation. While corticosteroids are known to decrease inflammation, they are contraindicated in quadriceps tendonitis since they increase the risk of tendon rupture. If the pain persists despite conservative measures, arthroscopic surgery (i.e., a procedure where a narrow tube attached to a small camera is inserted through a small incision) may also be considered to repair the tendon. Another viable option includes injections of plasma rich protein (PRP) or sclerosing agents into the tendon to alleviate symptoms in more severe cases.

Quadriceps tendonitis is a condition characterized by inflammation of the quadriceps tendon. The quadriceps tendon is located above the patella and connects the quadriceps muscles located in the front of the thigh to the patella. The patellar tendon is located beneath the patella and connects the patella to the shinbone. Both the quadriceps tendon and patellar tendon coordinate the quadriceps muscles, which help straighten the knee and absorb the shock of heel strike. Quadriceps tendonitis is caused by recurrent microtrauma to the quadriceps tendon, which activates the body’s inflammatory and repair pathways. Other causes include overuse injury or weak quadriceps muscles. Signs and symptoms of quadriceps tendonitis include pain that is located above or below the patella and exacerbated during exercises that involve bending and/or straightening the knee. The diagnosis is clinical and treatment includes a combination of rehabilitative exercises and pharmacologic modalities including non-steroidal anti-inflammatory medications. In severe refractory cases, PRP injections or arthroscopic surgery may be considered to repair the tendon.