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Clinical Procedures > Musculoskeletal Procedures
Joint Reduction, Patella Dislocation
Article Last Updated: Aug 11, 2008
AUTHOR AND EDITOR INFORMATION
Section 1 of 13  
Author: Moira Davenport, MD, Attending Physician, Departments of Emergency Medicine and Orthopedic Surgery, Allegheny General Hospital
Moira Davenport is a member of the following medical societies: American College of Emergency Physicians and Society for Academic Emergency Medicine
Coauthor(s):
Adam J Rosh, MD, MS, Assistant Professor, Department of Emergency Medicine, Wayne State University/Detroit Receiving Hospital
Editors: Andrew K Chang, MD, Associate Professor, Department of Emergency Medicine, Albert Einstein College of Medicine, Montefiore Medical Center; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine; Luis M Lovato, MD, Assistant Clinical Professor, David Geffen School of Medicine at UCLA; Director of Critical Care, Department of Emergency Medicine, Olive View/UCLA Medical Center; Gil Z Shlamovitz, MD, Assistant Professor of Emergency Medicine, University of Connecticut School of Medicine; Attending Physician, Emergency Department, Windham Community Memorial Hospital, Willimantic, CT; Attending Physician, Emergency Department, Hartford Hospital, Hartford, CT; Rick Kulkarni, MD, Medical Director, Assistant Professor of Surgery, Section of Emergency Medicine, Yale-New Haven Hospital
Author and Editor Disclosure
Synonyms and related keywords:
patellar dislocation, patella dislocation, dislocated patella, dislocated kneecap, orthopedic reduction, subluxation, immobilization, knee dislocation, patella dislocation, kneecap, patella, patella injury, patella reduction, kneecap reduction, kneecap injury
Patellar dislocations are common, particularly in adolescent females and athletes. Patients usually present with an inability to extend an obviously deformed knee. A sizable effusion is usually also seen. This injury may be due to direct trauma to the patella or a valgus stress combined with flexion and external rotation. For more information on common injuries in athletes, see Medscape’s Exercise and Sports Medicine Resource Center.
The incidence of patellar dislocation is 5.8 per 100,000 but is as high as 29 per 100,000 in the adolescent population.1 The most common type of dislocation is lateral; however, horizontal, vertical, superior, and intercondylar dislocations occur. Reduction of the patella is a simple and safe procedure.
- Any lateral or medial dislocation of the patella
- Any dislocation associated with vascular or neurologic compromise of the distal extremity
- A patellar dislocation associated with a fracture of the proximal tibia or distal femur should not be reduced in this manner.
- A high index of suspicion should be maintained for osteochondral fractures.
- Any superior, intercondylar, or horizontal dislocation should be examined by an orthopedic surgeon.
- Any dislocation with suspected locked osteophyte should be examined by an orthopedic surgeon.
- Anesthesia is usually not required for this procedure, though some patients have significant anxiety and pain.
- Procedural sedation should be used as needed to facilitate the patient's comfort during the reduction. Click here to complete a Medscape CME activity on pediatric procedural sedation.
- No equipment is needed for the reduction.
- A knee immobilizer, crutches, or both are needed for aftercare.
- Place the patient supine or with the legs hanging off the side of a gurney.
- Explain the procedure, risks, and benefits to the patient.
- Obtain informed consent for the reduction (and the procedural sedation if necessary).
- Stand on the lateral side of the patient.
Positioning for a lateral patellar reduction.
Conducting a patellar reduction. - Slightly flex the injured leg at the hip to decrease tension on the quadriceps muscles.
- Extend the knee while applying gentle, anteromedially directed force on the lateral patellar edge to lift the patella over the femoral condyle.
- For a medial dislocation, use the same technique, but stand medial to the dislocation and apply an anterolateral force.
- When reduction is complete, apply a knee immobilizer so that the knee is in full extension.
- Arrange a follow-up appointment for the patient with an orthopedic surgeon, as some patients with complete dislocation may require surgery to prevent recurrence.
- Lateral patellar dislocations are the most common type of dislocation.
- Lateral or medial reduction is a safe and technically simple procedure.
- Obtain prereduction and postreduction radiographs to rule out any osteochondral fractures.
- To optimize successful rehabilitation, educate the patient regarding aftercare.
- The literature reports controversy regarding which patients should have operative repair of primary dislocations. Most patients do well with a short course of immobilization followed by physical therapy.2
- Following up with an orthopaedic surgeon is recommended for all patients with patellar dislocations.3, 4, 5, 6, 7
- No complications are secondary to reduction.
- Related complications of the dislocation itself may include recurrent dislocations, degenerative arthritis, or osteochondral fractures.
Wheeless’ Textbook of Orthopaedics: Subluxation/Dislocation of the Patella
- Mehta VM, Inoue M, Nomura E, Fithian DC. An algorithm guiding the evaluation and treatment of acute primary patellar dislocations. Sports Med Arthrosc. Jun 2007;15(2):78-81. [Medline].
- Hawkins RJ, Bell RH, Anisette G. Acute patellar dislocations. The natural history. Am J Sports Med. Mar-Apr 1986;14(2):117-20. [Medline].
- Gerbino PG, Zurakowski D, Soto R, Griffin E, Reig TS, Micheli LJ. Long-term functional outcome after lateral patellar retinacular release in adolescents: an observational cohort study with minimum 5-year follow-up. J Pediatr Orthop. Jan-Feb 2008;28(1):118-23. [Medline].
- Nomura E, Inoue M, Kobayashi S. Generalized joint laxity and contralateral patellar hypermobility in unilateral recurrent patellar dislocators. Arthroscopy. Aug 2006;22(8):861-5. [Medline].
- Palmu S, Kallio PE, Donell ST, Helenius I, Nietosvaara Y. Acute patellar dislocation in children and adolescents: a randomized clinical trial. J Bone Joint Surg Am. Mar 2008;90(3):463-70. [Medline].
- Sillanpää P, Mattila VM, Iivonen T, Visuri T, Pihlajamäki H. Incidence and risk factors of acute traumatic primary patellar dislocation. Med Sci Sports Exerc. Apr 2008;40(4):606-11. [Medline].
- Stefancin JJ, Parker RD. First-time traumatic patellar dislocation: a systematic review. Clin Orthop Relat Res. Feb 2007;455:93-101. [Medline].
- Kling MP. Patellar dislocation reduction. In: Reichman EF, Simon RR, eds. Emergency Medicine Procedures. New York: McGraw-Hill Professional; 2003:640.
- Simon RR, Koenigsknecht SJ. Dislocations of the knee, fibula, and patella. In: Emergency Orthopedics: The Extremities. 4th ed. New York: McGraw-Hill; 2001:480-1.
- Ufberg J, McNamara R. Management of common dislocations. In: Roberts JR, Hedges RJ, eds. Clinical Procedures in Emergency Medicine. 4th ed. Philadelphia: WB Saunders Company; 2004:982-3.
Joint Reduction, Patella Dislocation excerpt Article Last Updated: Aug 11, 2008
Topic originally published: Feb 6, 2007
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