A patellar tendon rupture is a complete tear of the tendon that connects the bottom of the kneecap (patella) to the top of the shinbone (tibia). Because this tendon is part of the "extensor mechanism," a rupture makes it impossible to straighten the knee or support the body's weight. This injury is most common in men between the ages of 30 and 50 and often occurs during a forceful jump or a fall.
A rupture is a traumatic event that results in an immediate loss of leg function.
Sudden "Pop" or Snap: A very loud and distinct sound at the moment of the tear.
Immediate, Intense Pain: Severe pain located just below the kneecap.
Inability to Straighten the Knee: The most defining symptom; you cannot lift your leg straight out while sitting or lying down.
Indentation: A visible gap or "soft spot" in the skin directly below the kneecap.
Patella Alta: The kneecap may appear to be sitting higher up on the thigh than usual because the tendon is no longer pulling it down.
Rapid Swelling and Bruising: Significant inflammation throughout the front of the knee.
Clinical diagnosis is usually straightforward due to the obvious loss of the knee’s straightening function.
Physical Exam
X-rays: Used to check the position of the kneecap. If it is sitting too high (Patella Alta), it is consistent with the tendon being severed.
MRI: Provides a clear view of the tear and determines if it is a partial or complete rupture, and if the tendon pulled away from the bone or tore in the middle.
A complete rupture almost always requires surgery to restore the ability to walk and climb stairs.
Non-Surgical Care: Only considered for partial tears where the patient can still straighten the leg; involves a long period of bracing and physical therapy.
Surgical Repair: The primary treatment. The surgeon reattaches the tendon to the kneecap using sutures passed through holes drilled in the bone or using small metal anchors.