What are the causes and treatment options for patellar dislocation (kneecap dislocation)?

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Last updated: April 18, 2025View editorial policy

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From the Guidelines

Patella dislocation treatment should prioritize individualized knee-targeted exercise therapy, with a focus on hip and knee strengthening, as well as education on pain management and load modification, as supported by the most recent evidence 1.

Key Considerations

  • Initial treatment involves the RICE protocol: Rest, Ice, Compression, and Elevation, along with pain management using acetaminophen or NSAIDs for 5-7 days.
  • For acute dislocations, immediate medical attention is necessary to manually reposition the patella, followed by the use of a knee immobilizer or brace for 2-4 weeks.
  • Physical therapy should focus on quadriceps strengthening, particularly the vastus medialis obliquus muscle, to stabilize the patella and prevent recurrence.
  • Surgical intervention may be necessary for patients with recurrent dislocations, significant cartilage damage, or anatomical abnormalities that predispose to instability.

Rehabilitation and Prevention

  • Individualized exercise therapy should be delivered based on symptom severity and irritability, with a focus on hip and knee strengthening 1.
  • Education should underpin all interventions, providing a rationale for the delivery of a specific intervention plan and promoting autonomy and reducing fear 1.
  • Supporting approaches, such as prefabricated foot orthoses, taping, and manual therapy, should be considered as adjuncts to successful exercise delivery 1.

Imaging and Diagnosis

  • Radiographs, including anteroposterior and lateral views, should be obtained to evaluate the acutely injured knee, with additional views as necessary to assess for fractures or dislocations 1.
  • The Ottawa Knee Rule and Pittsburgh Decision Rule can be used to guide the decision to obtain radiographs in patients with acute knee injuries 1.

From the Research

Patella Dislocation Overview

  • Patella dislocation is a condition where the patella (kneecap) moves out of its normal position, often causing pain and instability in the knee.
  • The incidence of patellar subluxation or dislocation has been documented up to 43/100,000, with females being more prevalent than males 2.

Causes and Risk Factors

  • Contributing factors to patellar subluxation include weakness of the vastus medialis oblique (VMO) and adductors, increased tightness in the iliotibial band, and overpowering of the vastus lateralis 2.
  • Patella alta can predispose an individual to lateral dislocation due to the patella placement outside of the femoral trochlear groove, resulting in a disadvantage of boney stability 2.
  • Other factors that may cause the patella to laterally sublux or dislocate during a functional activity or sporting activity include a position of femoral external rotation, tibial internal rotation, and excessive contraction of the vastus lateralis 2.

Treatment and Management

  • Nonoperative treatment of a lateral patellar dislocation produces favorable functional results, but as high as 35% of individuals experience recurrent dislocations 3.
  • Medial patellofemoral ligament reconstruction is an effective treatment to prevent recurrent dislocations and yield excellent outcomes with a high rate of return to sport 3, 2.
  • Post-operative management should include a physical therapy treatment progression, including proprioceptive-focused and dynamic rehabilitation, along with a home exercise program 2.
  • Lateral retinacular lengthening is recommended over lateral release owing to the potential of iatrogenic medial instability with release, and a lateral patellofemoral ligament reconstruction can be performed to effectively treat medial instability 4.

Rehabilitation and Return to Sport

  • Both nonoperative and postoperative rehabilitation should center on resolving pain and edema, restoring motion, and incorporating isolated and multijoint progressive strengthening exercises targeting the hip and knee 3.
  • Prior to return to sports, both functional and isolated knee strength measurements should be used to determine leg symmetry strength, and patient-reported outcome measures should be used to assess the patient's perceived physical abilities and patellofemoral joint stability 3.
  • Consensus-based guidelines recommend physical therapy starting within the first month post-injury, with return to sport after 2 to 4 months, and further follow-up as needed 5.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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