Extensor Mechanism Ruptures

What is the Extensor Mechanism?

The extensor mechanism includes the quadriceps tendon, patella, and patellar tendon. This structure allows you to extend (straighten) your knee and is crucial for walking, climbing, and standing up from a seated position.

What is an Extensor Mechanism Rupture?

An extensor mechanism rupture occurs when one of the tendons in this system tears, leading to a loss of active knee extension. It often occurs due to high stress, trauma, or degenerative changes.

Types of Ruptures

  1. Quadriceps Tendon Rupture:
    • Typically occurs just above the patella.
    • More common in individuals over 40 due to degenerative changes.
  2. Patellar Tendon Rupture:
    • Occurs below the patella, connecting it to the tibia.
    • More common in younger, active individuals, often due to high-impact activities.

Causes

  • Sudden, forceful contraction of the quadriceps (e.g., jumping or lifting).
  • Trauma, such as a fall or direct blow to the knee.
  • Chronic conditions like tendonitis or degenerative changes.
  • Systemic conditions (e.g., diabetes, rheumatoid arthritis) that weaken the tendons.

Symptoms

  • Inability to actively straighten the knee or lift the leg.
  • Swelling and bruising around the knee.
  • Palpable gap above or below the patella.
  • Patellar displacement: Upward movement (quadriceps rupture) or downward movement (patellar tendon rupture).

Diagnosis

  1. Physical Examination:
    • Assess for active knee extension.
    • Palpation to identify gaps in the tendon.
  2. Imaging:
    • X-rays: To detect patellar displacement (alta or baja).
    • Ultrasound or MRI: Confirm the extent of the tendon rupture.

 

Treatment

  • Non-Surgical Management

    • Rarely an option unless the patient is medically unfit for surgery or has a partial tear.
    • Immobilization with a knee brace in extension and gradual rehabilitation.

    Surgical Repair (Standard for Complete Ruptures)

    • Quadriceps or patellar tendon is surgically reattached to the bone.
    • Strong sutures or anchors are used to restore function.

Rehabilitation

  • Early Phase (0–6 weeks):
    • Immobilization in a brace to protect the repair.
    • Gradual passive range of motion (ROM) exercises.
  • Middle Phase (6–12 weeks):
    • Transition to active ROM exercises.
    • Begin quadriceps strengthening exercises.
  • Late Phase (3–6 months):
    • Progressive strengthening and functional training.
    • Return to normal activities and sports.

Prognosis

  • With proper surgical repair and rehabilitation, most patients regain near-normal function.
  • Delayed treatment may lead to poor outcomes, including chronic weakness and instability.