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Patellar Fractures

Background and Etiology

The knee is the largest joint in the body. It is built for weight bearing, stability and mobility. The knee complex is composed of four bones and three osseous bone-to-bone joints. The four bones in the knee are the tibia or lower leg bone or shin, the patellar or kneecap, the femur or thighbone, and the fibula a long thin bone in the lower leg. A patellar fracture is a break to the kneecap.

A fracture is defined as a partial or complete crack in a bone. Fractures can be minor with little or no displacement of the bone, or more severe with complete displacement of the two ends of the bone that requires surgery to realign. There are closed fractures that do not break the skin, and open fractures that do break the skin.


the most common cause of a patellar fracture is trauma from a direct blow to the knee. Patellar fractures occur predominately in people who are 20-50 years old. Men are more likely than women to facture the patellar. Common causes of patellar fracture include:

  • Trauma from a fall or motor vehicle accident
  • Direct blow to the knee (for example, being kicked) perhaps during sports
  • Indirect trauma, for example violent contractions of the thigh muscles than can pull the patellar apart.


A fracture is an acute injury therefore a patient may begin to experience symptoms immediately.

  • Immobility when attempting to move the leg or knee
  • Severe loss of active motion of the knee.
  • Severe pain in the knee
  • Difficulty placing weight on the leg on the affected side
  • Stiffness, bruising or swelling at the knee
  • Weakness in the knee


In the event that an individual suspects they may have sustained a patellar fracture, a radiographic evaluation (X-Ray) will be essential to a proper diagnosis. Stable patellar fractures, where the ends of the bone still line up properly do not require surgery to heal. However, more severe patellar fractures where the ends of the bone do not line up correctly, the bone is broken into several pieces, or the surrounding tendons and ligaments are injured typically require surgery to realign and stabilize the injury.

How much movement should be restricted following the fracture will depend on the severity of the break. Once cleared by the physician, a physical therapy program should be initiated to restore knee motion. In more involved fractures recovery can be long and arduous. Formal therapy and compliance with an extensive home program is the mainstay to restoring function of the knee.

Physical therapy interventions

Goals for physical therapy post patellar fracture are increasing weight bearing as tolerated, restoration of normal tissue relationships to improve motion, strength and the ability to perform functional activities of daily living.

  • Manual Therapeutic Technique (MTT): hands on care including soft tissue massage, and joint mobilization by a physical therapist to modulate pain and reduce any soft tissue or tendon irritation and restore normal joint mechanics and range of motion.
  • Therapeutic Exercises (TE) including exercises to improve range of motion, strength and performance of the knee and surrounding muscles.
  • Neuromuscular Reeducation (NMR) to restore stability, retrain the lower extremity, improve joint stability and improve movement technique and mechanics (for example: walking, stairs, squatting, and running) in use of the involved lower extremity in daily activities.
  • Modalities that can include the use of ultrasound, electrical stimulation, ice, cold and laser to decrease pain, improve mobility and reduce inflammation of the knee joint and surrounding muscles and tendons.
  • Home program development should include strengthening, stretching and stabilization exercises as well as instructions to help the person perform daily tasks and advance to the next functional level.

Medical Treatment

Most fractures can be diagnosed with X-Ray studies and when necessary a CAT scan. The use of pain medications, rest and ice are the first line of treatment. Surgical intervention is typically required to realign and repair severe patellar fractures.


Rate of recovery and the prognosis from a patellar fracture will depend on a number of factors:

  • Severity – Minor fractures do well with immobilization and physical therapy, while fractures that are more severe and require surgery or effect joint integrity take longer to recover. Patients may have residual motion and strength deficits.
  • Age- Younger individuals recover faster and are less likely to have residual deficits. Younger individuals heal quicker, have better circulation, are stronger and usually their pre-injury tissue integrity is better.
  • Prior activity level plays an important role in post-injury recovery. Those who exercise regularly are stronger and more flexible, and generally have an easier and more complete recovery.
  • Compliance- Patients that are committed to their rehabilitation program and are compliant with their home program are more successful in returning to full function.