eMedicine Specialties > Emergency Medicine > Trauma & Orthopedics

Dislocations, Knee

Author: Diku Mandavia, MD, FACEP, FRCPC, Attending Staff Physician, Department of Emergency Medicine, Cedars-Sinai Medical Center; Clinical Associate Professor of Emergency Medicine, Los Angeles County-USC Medical Center; Co-Editor, Color Atlas of Emergency Trauma
Contributor Information and Disclosures

Updated: Nov 29, 2007

Introduction

Background

Knee dislocation is a relatively rare injury but an important one to recognize because coexistent vascular injury, if missed, often leads to limb loss. In addition, knee dislocation often presents in the context of multisystem trauma or spontaneous relocation, which makes detection more difficult.

Clinical

History

Knee dislocation is classified according to the position of the tibia relative to the femur. The 5 major types of dislocation, which are illustrated in Media file 1, are as follows:

  • Anterior: Anterior dislocation often is caused by severe knee hyperextension. Cadaver research has shown that approximately 30 degrees of hyperextension is required before dislocation will occur.
  • Posterior: Posterior dislocation occurs with anterior-to-posterior force to the proximal tibia, such as a dashboard type of injury or a high-energy fall on a flexed knee. Media file 2 shows a radiograph of a posterior dislocation.
  • Medial, lateral, or rotatory: Medial, lateral, and rotatory dislocations require varus, valgus, or rotatory components of applied force. A lateral dislocation is illustrated in Media file 3.
  • More than half of all dislocations are anterior or posterior, and both of these have a high incidence of popliteal artery injury. Twenty to thirty percent of all knee dislocations are complicated further by open joint injury (see Media file 4).

Physical

  • Most often, the affected limb has a gross deformity around the knee with swelling and immobility. Occasionally, the knee will have relocated spontaneously prior to the patient's arrival at the ED. This makes a careful physical examination very important. The finding of varus or valgus instability in full extension of the knee is suggestive of a grossly unstable knee and of a spontaneously reduced dislocation. In addition, pain out of proportion or absent or decreased pulse should be red flags of such an injury. The above also underscores the importance of joint and vascular examinations, especially in patients with head injuries or in those who are intoxicated and may not be able to communicate symptoms adequately.
  • A careful vascular examination is essential, as popliteal artery injury occurs in 7-45% of all knee dislocations. The popliteal artery may be damaged severely in both closed and open dislocations, and such injury must be ruled out in knees that have relocated spontaneously. Palpation of the dorsalis pedis and posterior tibial arteries along with capillary refill evaluation is necessary. The presence of normal pulses does not rule out the presence of significant vascular injury. Coexistent peroneal nerve injury occurs in 25-35% of patients and manifests with decreased sensation at the first webspace with impaired dorsiflexion of the foot.

Causes

  • The knee is a very stable joint requiring high-energy trauma to produce dislocation. At least 3 major ligaments must rupture for dislocation to occur. Common mechanisms of injury include the following:
    • Motor vehicle collisions
    • Auto-pedestrian impact
    • Industrial injuries
    • Falls
    • Athletic injuries

More on Dislocations, Knee

Overview: Dislocations, Knee
Differential Diagnoses & Workup: Dislocations, Knee
Treatment & Medication: Dislocations, Knee
Follow-up: Dislocations, Knee
Multimedia: Dislocations, Knee
References
[ CLOSE WINDOW ]

References

  1. Barnes CJ, Pietrobon R, Higgins LD. Does the pulse examination in patients with traumatic knee dislocation predict a surgical arterial injury? A meta-analysis. J Trauma. Dec 2002;53(6):1109-14. [Medline].

  2. Browner BD, Jupiter JB, Levine AM. Dislocations and soft tissue injuries of the knee. In: Skeletal Trauma. Vol 2. WB Saunders Co; 1992:1717-1741.

  3. Chhabra A, Cha PS, Rihn JA, Cole B, Bennett CH, Waltrip RL. Surgical management of knee dislocations. Surgical technique. J Bone Joint Surg Am. Mar 2005;87 Suppl 1(Pt 1):1-21. [Medline].

  4. Cone JB. Vascular injury associated with fracture-dislocations of the lower extremity. Clin Orthop. Jun 1989;(243):30-5. [Medline].

  5. Dennis JW, Jagger C, Butcher JL, et al. Reassessing the role of arteriograms in the management of posterior knee dislocations. J Trauma. Nov 1993;35(5):692-5; discussion 695-7. [Medline].

  6. Giannoulias CS, Freedman KB. Knee dislocations: management of the multiligament-injured knee. Am J Orthop. Nov 2004;33(11):553-9. [Medline].

  7. Harner CD, Waltrip RL, Bennett CH, et al. Surgical management of knee dislocations. J Bone Joint Surg Am. Feb 2004;86-A(2):262-73. [Medline].

  8. Henrichs A. A review of knee dislocations. J Athl Train. Oct-Dec 2004;39(4):365-9. [Medline].

  9. Kennedy JC. Complete dislocation of the knee joint. J Bone Joint Surg Am. Jul 1963;45:889-904. [Medline].

  10. Klineberg EO, Crites BM, Flinn WR, et al. The role of arteriography in assessing popliteal artery injury in knee dislocations. J Trauma. Apr 2004;56(4):786-90. [Medline].

  11. Mills WJ, Barei DP, McNair P. The value of the ankle-brachial index for diagnosing arterial injury after knee dislocation: a prospective study. J Trauma. Jun 2004;56(6):1261-5. [Medline].

  12. Rihn JA, Groff YJ, Harner CD, Cha PS. The acutely dislocated knee: evaluation and management. J Am Acad Orthop Surg. Sep-Oct 2004;12(5):334-46. [Medline].

  13. Rihn JA, Groff YJ, Harner CD, Cha PS. The acutely dislocated knee: evaluation and management. J Am Acad Orthop Surg. Sep-Oct 2004;12(5):334-46. [Medline].

  14. Robertson A, Nutton RW, Keating JF. Dislocation of the knee. J Bone Joint Surg Br. Jun 2006;88(6):706-11. [Medline].

  15. Rockwood CA, Green DP, Bucholz RW. Injuries of the knee. In: Fractures in Adults. Vol 2. Lippincott Williams & Wilkins Publishers; 1996:2112-2126.

  16. Stannard JP, Sheils TM, Lopez-Ben RR, McGwin G Jr, Robinson JT, Volgas DA. Vascular injuries in knee dislocations: the role of physical examination in determining the need for arteriography. J Bone Joint Surg Am. May 2004;86-A(5):910-5. [Medline].

  17. Varnell RM, Coldwell DM, Sangeorzan BJ, Johansen KH. Arterial injury complicating knee disruption. Third place winner: Conrad Jobstaward. Am Surg. Dec 1989;55(12):699-704. [Medline].

  18. Welling RE, Kakkasseril J, Cranley JJ. Complete dislocations of the knee with popliteal vascular injury. J Trauma. Jun 1981;21(6):450-3. [Medline].

[ CLOSE WINDOW ]

Further Reading

[ CLOSE WINDOW ]

Keywords

knee dislocation, dislocated knee, anterior dislocation, posterior dislocation, medial dislocation, lateral dislocation, rotatory dislocation, open dislocation, closed dislocation, popliteal artery injury, knee hyperextension, trauma to the knee

[ CLOSE WINDOW ]

Contributor Information and Disclosures

Author

Diku Mandavia, MD, FACEP, FRCPC, Attending Staff Physician, Department of Emergency Medicine, Cedars-Sinai Medical Center; Clinical Associate Professor of Emergency Medicine, Los Angeles County-USC Medical Center; Co-Editor, Color Atlas of Emergency Trauma
Disclosure: Nothing to disclose.

Medical Editor

James E Keany, MD, FACEP, Medical Director, JetWest International Air Ambulance, Van Nuys, California; Consulting Staff, Department of Emergency Services, Mission Hospital Regional Medical Center, Mission Viejo, California
James E Keany, MD, FACEP is a member of the following medical societies: American College of Emergency Physicians, American College of Sports Medicine, and California Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Tom Scaletta, MD, President, American Academy of Emergency Medicine; Chairperson, Department of Emergency Medicine, Edward Hospital; Assistant Professor of Emergency Medicine, Rush Medical College/Cook County Hospital
Tom Scaletta, MD is a member of the following medical societies: American Academy of Emergency Medicine and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

CME Editor

John Halamka, MD, Chief Information Officer, CareGroup Healthcare System, Assistant Professor of Medicine, Department of Emergency Medicine, Beth Israel Deaconess Medical Center; Assistant Professor of Medicine, Harvard Medical School
John Halamka, MD is a member of the following medical societies: American Academy of Emergency Medicine and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Barry E Brenner, MD, PhD, FACEP, Program Director, Department of Emergency Medicine, University Hospitals, Case Medical Center
Barry E Brenner, MD, PhD, FACEP is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Chest Physicians, American College of Emergency Physicians, American College of Physicians, American Heart Association, American Thoracic Society, Arkansas Medical Society, New York Academy of Medicine, New York Academy of Sciences, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

 
 
HONcode

We subscribe to the
HONcode principles of the
Health On the Net Foundation

All material on this website is protected by copyright, Copyright© 1994- by Medscape.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.