Treating a Rare Injury: Patellofemoral Dislocation

Patellofemoral dislocation accounts for less than 3% of knee injuries seen by most orthopedic surgeons. Evaluation of patellofemoral dislocation, and determining whether surgical or non-surgical management would be optimal for a particular patient, is difficult due to anatomical complexity and challenges in determining the cause of the problem.

A Nuanced Plan

“These patients require a nuanced evaluation and treatment plan that’s developed by knee specialists who see a high volume of patellofemoral dislocation,” says Rodney Benner, MD, an orthopedic surgeon at Shelbourne Knee Center. Dr. Benner and K. Donald Shelbourne, MD, another orthopedic surgeon at Shelbourne Knee Center, have treated more than 700 patella dislocations.

Instability due to an anatomic predisposition or a traumatic injury in an otherwise normal knee are the two causes of patellofemoral dislocation. In patients with instability due to an anatomic predisposition, dislocation often occurs in both knees and can be caused by mild trauma, daily activities or major trauma. Treatment for patients with patellofemoral dislocation due to an anatomic predisposition is different than treatment for those whose injury is due to trauma.

Research-Based Management Algorithm

Shelbourne Knee Center has developed an algorithm for evaluating and managing patellofemoral dislocation that starts with a thorough history and imaging. The number of previous dislocations and whether the patient experienced a traumatic injury are key factors in the history.

Using a plain radiograph-based classification system developed at Shelbourne Knee Center1, Dr. Benner and Dr. Shelbourne classify the patellofemoral dislocation according to two criteria: symmetry between the knees and evidence of predisposing anatomy. The radiographs are the bilateral Merchants’ view and 60-degree lateral view of both knees.

Patients are put into one of four classifications:

  • Type I: Symmetrical radiographs and no predisposing anatomy
  • Type II: Asymmetrical lateral tilt/displacement on the involved knee compared to the uninvolved, knee with no predisposing anatomy
  • Type III: Symmetric radiographs, but evidence of predisposing anatomy
  • Type IV: Combined asymmetry and evidence of predisposing anatomy.

Surgical Versus Non-Surgical Treatment

The history and classification, along with the impact of patellofemoral dislocation on the patient’s life and goals for athletic participation and activity, help Dr. Benner and Dr. Shelbourne determine the optimal treatment. If surgery is recommended, the patient’s classification is used to determine the optimal procedure.

Most patients with first-time dislocations are treated with Shelbourne Knee Center’s research-based physical therapy program after swelling has been minimized. “Soft tissues will heal on their own. We help the patient reduce swelling and then regain range of motion through our rehab program,” says Dr. Benner. “Once the patient can straighten the knee, he/she transitions to low-impact exercise and strengthening to return strength to normal.”  

Surgery is recommended for patients experiencing their first patellofemoral dislocation if they have asymmetry and a malaligned patella, and usually for patients who have experienced multiple patellofemoral dislocations. “Since we see a relatively high volume of these patients, we can discern which first-time dislocations may do better with an operation,” says Dr. Benner. Traumatic patellofemoral dislocation with a fracture also requires surgery.

Physical Therapy  

Surgical patients participate in Shelbourne Knee Center’s research-based physical therapy program before and after surgery. Pre-op therapy prepares patients for surgery by reducing swelling and restoring normal range of motion. Post-op therapy focuses on:

  • Controlling swelling
  • Regaining range of motion
  • Returning full leg strength and function.

For more information about management of patellofemoral dislocation at Shelbourne Knee Center, call 888-FIX-KNEE or email


  1. Benner RW, Shelbourne KD, Bailey JM. A Novel Radiograph System for Classifying Patellofemoral Instability Based on Symmetry