Patellar tendinitis, also known as jumper's knee, is an

overuse injury A repetitive strain injury (RSI) is an injury to part of the musculoskeletal or nervous system caused by repetitive use, vibrations, compression or long periods in a fixed position. Other common names include repetitive stress disorders, cumu ...

of the

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

that straightens the

knee In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the ...

. Symptoms include pain in the front of the knee. Typically the pain and tenderness is at the lower part of the kneecap, though the upper part may also be affected. Generally there is no pain when the person is at rest. Complications may include patellar tendon rupture. Risk factors include being involved in athletics and being

overweight Being overweight or fat is having more body fat than is optimally healthy. Being overweight is especially common where food supplies are plentiful and lifestyles are sedentary. , excess weight reached epidemic proportions globally, with m ...

. It is particularly common in athletes who are involved in jumping sports such as basketball and volleyball. The underlying mechanism involves small tears in the

connecting the kneecap with the shinbone. Diagnosis is generally based on symptoms and examination. Other conditions that can appear similar include infrapatellar bursitis,

chondromalacia patella Chondromalacia patellae (also known as CMP) is an inflammation of the underside of the patella and softening of the cartilage. The cartilage under the kneecap is a natural shock absorber, and overuse, injury, and many other factors can cause i ...

and patellofemoral syndrome. Treatment often involves resting the knee and

physical therapy Physical therapy (PT), also known as physiotherapy, is one of the allied health professions. It is provided by physical therapists who promote, maintain, or restore health through physical examination, diagnosis, management, prognosis, pat ...

. Evidence for treatments, including rest, however is poor. Recovery can take between months and persist over years.Plinsinga M.L., Meeus M., Brink M., Heugen N., Van Wilgen P. Evidence of Widespread Mechanical Hyperalgesia but Not Exercise-Induced Analgesia in Athletes with Mild Patellar Tendinopathy Compared with Pain-Free Matched Controls: A Blinded Exploratory Study. ''Am. J. Phys. Med. Rehabil..'' 2021;100(10):946-951. doi:10.1097/PHM.0000000000001673 It is relatively common with about 14% of athletes currently affected; however research reflects that more than half of athletes with this injury end their careers as a result. Males are more commonly affected than females. The term "jumper's knee" was coined in 1973.

Signs and symptoms

People report anterior knee pain, often with an aching quality. The symptom onset is insidious. Rarely is a discrete injury described. Usually, the problem is below the kneecap but it may also be above. Jumper's knee can be classified into 1 of 4 stages, as follows: Stage 1 – ''Pain only after activity, without functional impairment'' Stage 2 – ''Pain during and after activity, although the person is still able to perform satisfactorily in his or her sport'' Stage 3 – ''Prolonged pain during and after activity, with increasing difficulty in performing at a satisfactory level'' Stage 4 – ''Complete tendon tear requiring surgical repair'' It begins as inflammation in the

patellar tendon The patellar tendon is the distal portion of the common tendon of the quadriceps femoris, which is continued from the patella to the tibial tuberosity. It is also sometimes called the patellar ligament as it forms a bone to bone connection when ...

where it attaches to the

patella The patella, also known as the kneecap, is a flat, rounded triangular bone which articulates with the femur (thigh bone) and covers and protects the anterior articular surface of the knee joint. The patella is found in many tetrapods, such as ...

and may progress by tearing or degenerating the

. People present with an ache over the patella tendon. Most people are between 10 and 16 years old. Magnetic resonance imaging can reveal

edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels tight, the area ma ...

(increased T2 signal intensity) in the proximal aspect of the patellar tendon.

Causes

It is an overuse injury from repetitive overloading of the extensor mechanism of the

. The microtears exceed the body's healing mechanism unless the activity is stopped. Among the risk factors for patellar tendonitis are low ankle dorsiflexion, weak gluteal muscles, and muscle tightness, particularly in the calves, quadriceps muscle, and hamstrings. It may be associated with stiff ankle movement and ankle sprains.

Diagnosis

Diagnosis is generally based on symptoms and a

physical examination In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the pati ...

Ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...

may help clarify how severe the problem is.

Treatment

Evidence for treatment is poor. In the early stages

rest, ice, compression, and elevation RICE is a mnemonic acronym for the four elements of a treatment regimen that was once recommended for soft tissue injuries: rest, ice, compression, and elevation. It was considered a first-aid treatment rather than a cure and aimed to control ...

may be tried. Tentative evidence supports exercises involving eccentric muscle contractions of the quadriceps on a decline board. Specific exercises and stretches to strengthen the muscles and tendons may be recommended, e.g. cycling or swimming. Use of a strap for jumper's knee and suspension inlays for shoes may also reduce the problems.

Corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are inv ...

injections and NSAIDs are generally recommended.

Procedures

Dry needling, sclerosing injections, platelet-rich plasma, extracorporeal shock wave treatment, and heat therapy have been tried.

Surgery

Surgery may be tried if other measures fail. This may involve removal of myxoid degeneration in the tendon. This is reserved for people with severe pain for 6–12 months despite conservative measures. Novel treatment modalities targeting the abnormal blood vessel growth which occurs in the condition are currently being investigated. Knee operations in most cases have no better effects than exercise programs.

Epidemiology

It is relatively common with about 14% of athletes currently affected. Males are more commonly affected than females.

References

External links

{{Use dmy dates, date=August 2020 Overuse injuries Soft tissue disorders Patella Wikipedia medicine articles ready to translate