Patellar tendinitis, also known as jumper's knee, is an overuse injury of the

tendon A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...

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 hu ...

. Symptoms include pain in the front of the knee. Typically the pain and tenderness is at the lower part of the

kneecap The patella (: patellae or patellas), 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 m ...

, 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 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 more than ...

. It is particularly common in athletes who are involved in jumping sports such as basketball and volleyball. Other risk factors include sex, age, occupation, and physical activity level. It is increasingly more likely to be developed with increasing age. 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 and patellofemoral syndrome. Treatment often involves resting the knee and

physical therapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...

. Evidence for treatments, including rest, however is poor. Recovery can take 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 whe ...

where it attaches to the

patella The patella (: patellae or patellas), 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 m ...

and may progress by tearing or degenerating the

. People present with an ache over the patella tendon. Magnetic resonance imaging can reveal

edema Edema (American English), also spelled oedema (British English), and also known as fluid retention, swelling, dropsy and hydropsy, is the build-up of fluid in the body's tissue (biology), tissue. Most commonly, the legs or arms are affected. S ...

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

Causes

Patellar tendinitis is an overuse injury from repetitive overloading or repetitive stress of the patellar tendon of the knee leading to microtears and inflammation that do not have time to heal before the next use. Patellar tendonitis is common in athletes who participate in activities that include a lot of jumping, changing directions, or running. Risk factors for patellar tendonitis are low ankle

dorsiflexion Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...

(stiff ankles) and ankle sprains, weak

gluteal muscles The gluteal muscles, often called glutes, are a group of three muscles which make up the gluteal region commonly known as the buttocks: the gluteus maximus muscle, gluteus maximus, gluteus medius muscle, gluteus medius and gluteus minimus muscl ...

, and muscle tightness, particularly in the calves,

quadriceps muscle The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large ...

, and

hamstrings A hamstring () is any one of the three posterior thigh muscles in human anatomy between the hip and the knee: from anatomical_terms_of_location#Medial_and_lateral, medial to anatomical_terms_of_location#Medial_and_lateral, lateral, the semimembra ...

Diagnosis

Diagnosis is generally based on symptoms and a

physical examination In a physical examination, medical examination, clinical examination, or medical checkup, a medical practitioner examines a patient for any possible medical signs or symptoms of a Disease, medical condition. It generally consists of a series of ...

Ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

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

may help clarify how severe the problem is. Having a clinical diagnosis is the preferred way to diagnose patellar tendonitis, due to ultrasonographic abnormality.

Treatment

Evidence for treatment is poor. In the early stages rest, ice, compression, and elevation may be tried. Tentative evidence supports exercises involving eccentric muscle contractions of the

quadriceps The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large ...

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. NSAIDs are generally recommended. Without proper rest and rehabilitation, patellar tendonitis can worsen, causing persistent pain.

Procedures

Dry needling, sclerosing injections,

platelet-rich plasma Platelet-rich plasma (PRP), also known as autologous conditioned plasma, is a concentrate of plasma protein derived from whole blood, centrifuged to remove red blood cells but retaining platelets. Though promoted for treating various medical con ...

, extracorporeal shock wave treatment (ESWT), and heat therapy have been tried. According to a systematic review comparing extracorporeal shock wave treatment to conservative treatment, it was found with low certainty that ESWT has a large treatment effect to reduce short term pain.

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

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