Patellar tendon rupture is a tear 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 connects the

knee cap 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 m ...

(patella) to the

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

. Often there is sudden onset of pain and walking is difficult. In a complete rupture, the ability to extend that

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 ...

is decreased. A pop may be felt when it occurs. Injury to 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 t ...

generally requires a significant force such as falling directly on the knee or jumping from a height. Risk factors include

patellar tendinitis Patellar tendinitis, also known as jumper's knee, is an overuse injury of the tendon that straightens the knee. Symptoms include pain in the front of the knee. Typically the pain and tenderness is at the lower part of the kneecap, though the upp ...

kidney failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

, and

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

fluoroquinolone A quinolone antibiotic is a member of a large group of broad-spectrum bacteriocidals that share a bicyclic core structure related to the substance 4-quinolone. They are used in human and veterinary medicine to treat bacterial infections, as wel ...

use. There are two main types of ruptures: partial and complete. In most cases, the patellar tendon tears at the point where it attaches to the knee cap. Diagnosis is based on symptoms, examination, and

medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...

. Small tears may be treated with rest and splinting, followed by

physiotherapy 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, patient ...

. Larger tears typically require surgery within a couple of weeks. Outcomes are generally good. Rates in the general population are not clear; however, in certain high-risk groups it occurs about 1 in 10,000 per year. They occur most often in those under the age of 40.

Signs and symptoms

The sign of a ruptured patella tendon is the movement of the patella further up the quadriceps. When rupture occurs, the patella loses support from the tibia and moves toward the hip when the quadriceps muscle contracts, hindering the leg's ability to extend. This means that those affected cannot stand, as their knee buckles and gives way when they attempt to do so.

Mechanism

The upper part of the

attaches on the lower part of the knee cap, and the lower part of the patella tendon attaches to the

tibial tubercle The tuberosity of the tibia or tibial tuberosity or tibial tubercle is an elevation on the proximal, anterior aspect of the tibia, just below where the anterior surfaces of the lateral and medial tibial condyles end. Structure The tuberosity o ...

on the front of the

. Above the knee cap, the

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 ...

via the quadriceps tendon attaches to the top of the knee cap. This structure allows the knee to flex and extend, allowing use of basic functions such as walking and running.

Diagnosis

Patellar tendon rupture can usually be diagnosed by physical examination. The most common signs are: tenderness, the tendon's loss of tone, loss of ability to raise the straight leg and observation of the high-riding patella. Radiographically,

patella alta Attenuated patella alta is an extremely rare condition affecting mobility and leg strength. It is characterized by an unusually small knee cap (patella) that develops out of and above the joint. Typically, as the knee cap sits in the joint, it ...

can be detected using the

Insall and Salvati method People with the surname Insall include: * Donald Insall (born 1926), British architect, conservationist and author * Gilbert Stuart Martin Insall (1894–1972), British pilot in the Royal Flying Corps and Royal Air Force * John Insall (1930–2000) ...

when the patella is shorter than its tendon. Partial tears may be visualized using MRI scans.

Treatment

Patellar tendon rupture must be treated surgically. With a tourniquet applied, the tendon is exposed through a midline longitudinal incision extending from the upper patellar pole to the tibial tuberosity. The tendon is either avulsed (detached) from the lower patellar pole or lacerated. Even so, the continuity and tone of the tendon should be restored, taking into consideration the patellar height. A

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brace Brace(s) or bracing may refer to: Medical * Orthopaedic brace, a device used to restrict or assist body movement ** Back brace, a device limiting motion of the spine *** Milwaukee brace, a kind of back brace used in the treatment of spinal cur ...

is then put over where the operation took place. The cast or brace remains for at least 6 weeks followed by an unidentified time of

rehabilitation Rehabilitation or Rehab may refer to: Health * Rehabilitation (neuropsychology), therapy to regain or improve neurocognitive function that has been lost or diminished * Rehabilitation (wildlife), treatment of injured wildlife so they can be retur ...

of the knee. The usual risks of surgery are involved, including: infection, stiffness, death, suture reaction, failure of satisfactory healing, risks of

anesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), ...

phlebitis Phlebitis (or Venitis) is inflammation of a vein, usually in the legs. It most commonly occurs in superficial veins. Phlebitis often occurs in conjunction with thrombosis and is then called thrombophlebitis or superficial thrombophlebitis. Unlike ...

pulmonary embolus Pulmonary embolism (PE) is a blockage of an artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include shortness of breath, chest pain particularly upon breathing ...

, and persistent pain or weakness after the injury and repair. If the tendon rupture is a partial tear (without the two parts of the tendon being separated), then non-surgical methods of treatment may suffice. The future of non-surgical care for partial patella tendon ruptures is likely bioengineering. Ligament reconstruction is possible using mesenchymal stem cells and a silk scaffold. These same stem cells have been shown to be capable of seeding repair of damaged animal tendons. In 2010, a clinical study proved that mechanical loading of the tendon callus during the remodelling phase leads to healing by regeneration.

References

External links

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