A quadriceps tendon rupture is a complete tear of the tendon that attaches the quadriceps muscle group (front of the thigh) to the top of the kneecap (patella). This injury disrupts the "extensor mechanism" of the knee. Much like a patellar tendon rupture, it leaves the patient unable to straighten their leg or hold their weight. It most commonly occurs in individuals over the age of 40.
This injury is characterized by a sudden, traumatic loss of function.
Audible "Pop": A loud snapping sound at the moment of injury.
Intense Pain and Swelling: Immediate pain above the kneecap, followed by rapid inflammation.
Inability to Straighten the Knee: An inability to perform a straight leg raise or maintain an extended knee against gravity.
Visible Gap: A palpable "divot" or indentation in the soft tissue just above the kneecap.
Patella Baja: The kneecap may sag or shift lower (Patella Baja) because the anchor from above is gone.
Giving Way: The knee feels completely unstable and will buckle if weight is applied.
Clinical assessment is the most vital tool, though imaging confirms the severity and exact location of the tear.
Physical Exam
X-rays: Used to see if the kneecap has shifted downward and to rule out a patellar fracture.
MRI: Provides a high-definition view to determine if the tear is partial or complete and whether the tendon has "retracted" (pulled back) into the thigh.
Because the quadriceps are essential for walking, a complete rupture almost always necessitates surgical intervention.
Non-Surgical Care: Only indicated for partial tears where the patient can still extend the knee; involves a long period of bracing in extension.
Surgical Repair: The surgeon reattaches the torn tendon to the top of the kneecap using sutures anchored through small holes drilled in the bone.