The patellar ligament is the strong, flat band connecting the inferior patella to the tibial tuberosity, completing the extensor mechanism of the knee. Technically a tendon of the quadriceps femoris, it is called a ligament because it connects bone to bone (patella to tibia) rather than muscle to bone. Its rupture produces an inability to extend the knee and requires urgent surgical repair to restore quadriceps function.
| Origin | Apex and anterior surface of the patella |
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| Insertion | Tibial tuberosity |
| Actions | Transmits quadriceps force to the tibia for knee extension; final link in the extensor mechanism |
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Patellar ligament rupture occurs most commonly in men under 40 during an eccentric quadriceps contraction, producing an inability to extend the knee, a palpable gap below the patella, and a high-riding patella on lateral radiograph (patella alta). This is distinguished from patella tendon rupture by the location of the gap and the inferior position of the patella in quadriceps tendon rupture. Surgical repair within days of injury is required for a functional outcome.
Complete disruption producing inability to extend the knee, palpable infrapatellar gap, and patella alta on lateral radiograph, requiring urgent surgical repair.
Degenerative overload at the inferior patellar pole producing anterior knee pain in jumping athletes (jumper knee), managed with load modification and progressive tendon loading before surgical options are considered.
