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Introduction

The patella or kneecap is a small bone present in the front of your knee where the thigh bone meets the shinbone. It provides protection to your knee and attachment to muscles in the front of the thigh. An injury to the knee can result in a break or fracture of the patella.

The patella may break into two pieces or several pieces depending on the nature of the injury. Any part of the patella may be involved.

Causes

Patellar fractures may be caused by:

  • A direct fall onto your knee
  • A head-on vehicular collision causing your knee to hit against the dashboard
  • Or even sudden, severe contraction of the thigh muscles.

Types

A patella fracture may be categorized into different types. Your fracture may be described as a:
Stable fracture in which the broken bones are properly aligned and do not move out of place while healing.

  • Displaced fracture where the broken bones are separated and out of alignment. This type of fracture often requires surgery to reposition the bone fragments and stabilize the patella.
  • Comminuted fracture where the patella shatters into three or more pieces.
  • Open fracture where there is damage to the surrounding soft tissues resulting in exposure of the fracture site. Bone fragments may protrude through the skin or a wound can penetrate down to the patella.

Signs and Symptoms

The common symptoms of a patellar fracture include:

  • Swelling and pain in the front of your knee
  • Bruising
  • Inability to straighten or extend the knee
  • Difficulty walking

Diagnosis

A patellar fracture can be diagnosed by reviewing your symptoms and performing a physical examination during which your doctor examines your knee to evaluate the fracture and other abnormalities.
Hemarthrosis, a painful swelling caused by bleeding into the joint space, is a condition that may be identified. X-rays are ordered to visualize the fracture fragments.

Treatment

A patellar fracture can be treated with a splint or cast if the broken pieces of the patella are not displaced and the fracture site is not exposed.

If the pieces are out of place, your doctor will recommend surgery. Often this happens due to pulling forces of the tendons attached to the patella.

Surgery may be delayed to allow swelling or minor soft tissue injuries to heal. However, if you have an open fracture, there is a high risk of infection at the site and emergency surgery is recommended to clean out the wounds and repair the fracture.

The choice of surgery depends on the type of fracture.

  • If the patella fractures in two pieces and these pieces are displaced, your doctor will reposition the fragments and secure them with screws, pins, and plates. A tension band may be used to bring the pieces together.
  • When the bottom or top of the patella is broken into several small pieces and the adjoining tendon is disrupted, your doctor removes the broken pieces of the patella and attaches the tendon back to the remaining patellar bone.
  • If the center of the patella is broken into several pieces, then your doctor may use a combination of wires and screws to fix it back into position.
  • For severely comminuted fractures, the kneecap may have to be removed completely.

Recovery

  • While in a cast or splint, your leg will remain straight and depending on the severity of the injury, your doctor may recommend that you avoid weight-bearing for about 4-6 weeks. You will gradually be allowed to bear weight on the leg once healed.
  • Your doctor will prescribe medications to help manage your pain. Application of ice and keeping the leg elevated can also help ease your symptoms.
  • Once the fracture is adequately healed, physical therapy or exercises are recommended to avoid knee stiffness, improve knee movement and strengthen your leg muscles.
  • American Orthopaedic Society for Sports Medicine
  • American Association for Hand Surgery
  • American Academy Of Orthopaedic Surgeons
  • The American Board of Pediatrics
  • North American Spine Society
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