Patellar tendon rupture is the complete tear of the tendon resulting from a fall or a jump, characterized by pain, swelling, and difficulty in flexing the knee.
Muscles are attached to the bones by cord-like fibrous tissues called tendons. Quadriceps muscles are attached to the tibia or the shin bone through the patellar tendon. The upper portion of the patellar tendon is attached to the lower portion of the knee cap, and the lower part of the tendon is attached to the tibial tubercle. The quadriceps muscles are attached by the quadriceps tendon to the upper portion of the kneecap. The quadriceps muscles and tendon, along with the patellar tendon, help during walking, running, flexing, and extending the knee.
An injury to the patellar tendon resulting in a tear or rupture is called a patellar tendon rupture. It is a rare condition usually seen in males under the age of 40 years. It may be a partial or complete tear, leading to difficulty stretching or flexing the knee.
Patients with autoimmune diseases of the joint, like rheumatoid arthritis and systemic lupus erythematosus, or those patients on long-term corticosteroid therapy, are prone to patellar tendon rupture due to the swelling of the synovial membrane that covers the knee joint.
Patellar tendon rupture is associated with patients undergoing dialysis for chronic kidney failure.
Patients with metabolic diseases like diabetes mellitus and high cholesterol levels are at high risk for tendon rupture due to weak tendons that cause disruption in the blood supply.
Some of the causes of patellar tendon rupture are:
High-velocity force injuries have a direct impact on the knee from a blow, a fall from height, or landing with a bent knee following a jump.
Inflammation of the patellar tendon (patellar tendinitis) causes weakness in the tendons, leading to ruptures. It is commonly seen in sports persons or athletes and is called the jumper’s knee.
Patients on medications with corticosteroid injections given around the patella can lead to weakness.
Some of the signs and symptoms of patellar tendon rupture are:
Severe pain and tenderness below and around the knee cap.
Deep lacerations and soft tissue abrasions in case of injuries.
Difficulty in walking and extending the knee.
Swelling around the knee cap.
Difficulty in weight bearing.
A popping sound or a sense of giving way in flexing the knee.
A complete medical history is taken along with the presenting complaints, which includes the onset, characteristics, location, and duration of pain, aggravating, and relieving factors. A pre-existing pain around the kneecap or at the level of the patella may indicate patellar tendonitis. Decreased range of motion and loss of active knee extension is seen in the affected knee. Complete tears can be diagnosed by radiographs and physical examination, but partial tears are confirmed only by MRI scans.
Physical examination is done to evaluate any injuries of the surrounding soft tissues in case of direct trauma. Palpation is done to evaluate the swelling and its extension; a palpable defect is present, usually below the inferior pole of the patella. The patellar height is measured bilaterally, and the affected side is elevated than the unaffected knee.
In some cases, aspiration of the tissue fluid on the affected knee is done, followed by an injection of local anesthesia. The patient would be unable to perform straight leg raises, despite the anesthesia; this may clinically confirm the diagnosis.
Radiological investigations include:
X-Rays: Anteroposterior and lateral views may reveal a superiorly displaced patella (patella alta). It also shows the presence of any associated fractures or concomitant injuries.
Magnetic Resonance Imaging (MRI): It is usually preferred in tendon ruptures as it helps differentiate a partial or complete rupture, the exact location of rupture, the position of the patella, and the presence of degeneration or other soft tissue injuries.
Ultrasound: It may be preferred in some cases, which is usually less expensive and more convenient than MRI but effective in diagnosing and localizing tendon disruption.
Treatment of patellar tendon rupture mainly depends on the severity of the injury, the patient’s activity level, age, and general health. Patellar tendon rupture is usually managed by surgical treatment to reattach the tendon to the patella.
Non-surgical treatment is carried out in cases of partial tendon tears and mainly includes knee immobilization in full extension for about three to six weeks, followed by weight-bearing exercise therapy. Knee immobilization is done with hinge braces or a knee immobilizer to keep the knee straight and promote healing. Crutches are then advised to prevent the weight load on the knee.
Surgical treatment comprises primary tendon repair and reconstruction. The type of repair employed depends on the location of the tendon rupture. Primary tendon repair is advised in cases of complete tendon rupture or in cases where tendon ends can be approximated. The two ends of the torn tendons are sewed back together with a series of sutures.
In cases of rupture wherein the tendon is completely separated from the patella, and the ends cannot be approximated, or in proximal avulsion of the tendon, a series of holes are drilled into the patellar bone, and metal screws are placed, which acts as an anchor site for suturing the tendon back into place. The end-to-end repair is done if the rupture is in the middle of the tendon.
Reconstruction is done in severe ruptures or in cases of degeneration of the tendon. It is done by using an autograft or an allograft.
Re-rupture may occur when the repaired tendon detaches from the kneecap.
Inability to completely extend the knee.
Wasting or thinning of the quadriceps muscles, known as quadriceps atrophy.
The stiffness of the knee is the most complicated.
Infections at the surgical site following the surgery may delay wound healing.
Persistent pain and weakness following the injury.
Patellar tendon rupture occurs following a fall or landing from a jump with the knee bent and foot planted. It is associated with severe pain and swelling below and around the kneecap. It is usually seen in males around 30 to 40 years of age, especially in sportspersons and athletes. Surgical treatment is usually followed to manage patellar tendon ruptures, followed by physical therapy. Early repair, with patient cooperation and commitment, can help in the successful management of the condition.
Last reviewed at:
24 Nov 2022 - 4 min read
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