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Knee Dislocation

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Other Names

  • Tibiofemoral Dislocations
  • Knee Subluxation

Background

  • This page refers to dislocation of the articulation of the Femur and Tibia, commonly referred to as a knee dislocation
    • Defined by loss of tibiofemoral congruity

History

Epidemiology

  • True incidence likely underestimated as up to half of dislocations are missed on initial evaluation (need citation)
  • Account for less than < 0.02% of all orthopedic injuries[1]
  • Account for less than < 0.5% of all joint dislocations[2]
  • Arom et al reviewed a large insurance database, identifying 8050 dislocations from 2004-2009[3]
    • Estimated incidence of 0.072 events per 100 patient-years
    • 1333 (17%) were open and 6717 (83%) were closed
    • Males were slightly increased risk compared to females (1.09)
    • Mean age was 35
  • In India, the estimated incidence was 29.12 knee dislocations per 1 million person-years (need citation)
  • Anterior dislocation is most common, account for approximately 40%[4]

Pathophysiology

  • Definition
    • Not all patients will present with an acutely dislocated knee or with an obvious deformity
    • Often, knee dislocation will reduce spontaneously or easily
  • Direction of dislocation
    • Anterior (40%), due to forced hyperextension
    • Posterior (30%), common mechanism tibia impacting the dashboard during deceleration in motor vehicle accidents
    • Medial (18%)
    • Lateral (4%)
    • Rotational (less than 5%)

Etiology

  • High energy trauma including motor vehicle accidents, falls from height, and industrial injuries
  • Can occur in lower energy sports and sport-related activities
  • Spontaneous injuries during ambulation in the morbidly obese[5]

Associated Injuries

  • Most commonly injured are the major knee stabilizers
  • Less commonly injured orthopedic structures
    • Meniscal Tear in about 50% of cases[6]
    • Chondral injuries
    • Bone bruises are seen in the majority of cases[7]
    • Fractures are seen in about 1/3 of cases[8]
    • Extensor Mechanism Injuries

Risk Factors

  • Sports with reported cases
    • Soccer
    • Wrestling
    • Rugby
    • Kabaddi
    • Long jump
    • Skating
    • Cycling
    • Skiing
    • Gymnastics
    • Motor sports
    • Extreme adventure sports
  • Other

Differential Diagnosis


Clinical Features

  • History
    • Most commonly high energy trauma and deformity of the knee
    • May also report lower energy mechanism with pain +/- deformity
    • Also endorses instability if attempting to ambulate
  • Physical Exam: Physical Exam Knee
    • About 50% of cases will have no obvious deformity and gross appearance may be normal!
    • Dimple Sign: buttonholing of of medial femoral condyle through medial capsule
    • Very important to document a thorough vascular exam
    • Presence of peripheral pulses does not exclude vascular injury
    • Serial vascular exam is mandatory
    • Assess Peroneal Nerve, Tibial Nerve
  • Special Tests
    • Ankle Brachial Index: can be used to compare vascular flow to contralateral limb
    • Need to perform structural exam assessing ACL, PCL, MCL and LCL

Evaluation

Knee dislocation algorithim proposed by Ng et al[9]

Ankle Brachial Index

  • Excellent screening tool since arteriography is impractical in all patients
    • If ABI < 0.9, must pursue further vascular workup
  • Mills et al: ABI <0.9 has 100% sensitivity, specificity and PPD for vascular injuries in knee dislocations[10]

Radiographs

MRI

  • Indicated in most cases
    • After reduction, prior to surgical intervention if possible
  • Helpful to identify degree of soft tissue injury
    • Especially in the multi-ligament knee injury
  • Consider angiography

CT

  • Useful to evaluate for fracture patterns
  • Findings
    • Tibial eminence fracture
    • Tibial tubercle fracture
    • Tibial Plateau fracture
  • Consider angiography

Ultrasound

  • Duplex arterial sonography may be useful to evaluate arterial supply

Classification

Kennedy Position Classification

  • Anterior
    • Frequency: 40% (most common)
    • Mechanism: Hyperextension
    • Typically no medial or lateral damage
    • PCL can be intact
    • Vascular injury is common
  • Posterior
    • Frequency: 30%
    • Mechanism: Direct anterior-posterior force
    • Sometimes ACL is intact
    • Vascular damage is common
  • Lateral/ Lateral
    • Frequency: Rare in isolation (often with anterior or posterior)
    • Most of the time is posterolateral or posteromedial
    • Bicruciate injury with ACL and PCL
    • Vascular damage
    • Nerve damage in medial dislocations
  • Rotatory
    • Frequency: Rare
    • Often complex lesions

Schenck Anatomic Knee Dislocation (KD) Classification

  • KD I: Knee dislocation with either cruciate intact
  • KD II: Bicruciate with collateral intact
  • KD III: Bicruciate injury with one collateral ligament injury
    • KD IIIM: Bicruciate + MCL injury
    • KD IIIL: Bicruciate + LCL injury
  • KD IV: Bicruciate with both colateral ligaments injured
  • KD V: Periarticular fracture dislocation

Management

Prognosis

  • Levy et al systematic review compared operative to nonoperative management[11]
    • Overall, operative treatment results in better functional outcome as compared to nonoperative treatment
    • International Knee Documentation Committee [IKDC] excellent/good results 58% operative vs 20% nonoperative
    • Return to sport is 29% in operative group vs 10% in nonoperative group
    • Range of motion (126° vs. 123°) and flexion (4° vs. 3°) loss were similar among groups
  • Levy looked at timing of surgery[12]
    • More likely to return to sport if surgery done within 3 weeks
    • No difference in functional outcomes between early and late surgery

Acute

  • Follow ATLS protocol when appropriate
  • Physicians should be suspicious based on mechanism and examination, regardless of whether deformity is present or not
  • Reduction
    • Perform after XR only to confirm diagnosis, exclude fracture
    • Recommend procedural sedation
    • Gentle extension is often all that is required
    • Will often self reduce with minimal manipulation
  • Examination
    • Thorough structural examination
    • Confirm palpable dorsalis pedis, posterior tibia and popliteal artery pulses
  • Immobilization
  • Imaging
    • Pre and post-reduction radiographs
    • Consider CT (with angiography), emergent MRI
    • Vascular- consider ABI, duplex arterial sonography
  • Emergent surgery
    • Irreducible knee dislocation
    • Open knee dislocation
    • Vascular injury

Nonoperative

  • Indications
    • Elderly
    • Patients who are not good surgical candidates or multiple comorbidities

Operative

  • Indications
    • Most patients
  • Open reduction indications[13]
    • Irreducible knee
    • Posterolateral dislocation
    • Open fracture-dislocation
    • Obesity (may be difficult to obtain closed)
    • Vascular injury
  • External fixation indications
    • Vascular repair (takes precedence)
    • Open fracture-dislocation
    • Compartment syndrome
    • Obese (if difficult to maintain reduction)
    • Polytrauma patient
  • Delayed ligamentous reconstruction/repair

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play

  • Needs to be updated

Complications

  • Amputation
    • Rate reported to be up to 85% for injuries not corrected in 8 hours[4]
  • Traumatic Osteoarthritis
  • Chronic pain
    • 25% to 68% complain of chronic pain
  • Arthrofibrosis
    • 5% to 71% develop arthrofibrosis making it the most common complication
    • 29% of patients will eventually require adhesiolysis
  • Knee stiffness
    • Higher risk with 3 or more ligaments repaired
  • Persistent knee instability
    • Instability in at least one plane ranges from 18% to 100% (mean 42%)
  • Popliteal Artery injury
    • Reported in 18 to 64% of knee dislocations[14]
    • Approximately 80% are repaired, 12% require amputation
    • Lower risk in sports-related injuries than high-velocity injuries[15]
    • Early interventions within 8 hours (11%) is associated with lower rates of amputation than beyond (86%)[16]
    • Highest risk with KD IV injuries
    • McDonough case series on popliteal artery injuries following MLKI[17]
      • 4/12 identified by physical exam, 5/12 identified with arteriography and 3/12 identified in OR with vascular exam and arteriography
  • Peroneal Nerve Injury
    • Most commonly the Common Peroneal Nerve, however Superficial Peroneal Nerve, Deep Peroneal Nerve also affected
    • Injured in between 25% and 33% of dislocations, particular posterior and lateral[18][19]
    • As high as 41% in posterlateral corner injuries[20]
    • Among sports, skiing and football are most commonly associated[21]
    • Approximately 30% have a complete palsy, with only 38.4% of them having a functional recovery
    • Approximately 70% have an incomplete palsy, 87.3% of them have a functional recovery[22]

See Also


References


  1. Rihn JA, Groff YJ, Harner CD, Cha PS. The acutely dislocated knee: Evaluation and management. J Am Acad Orthop Surg. 2004;12:334–46.
  2. Richter M, Lobenhoffer P, Tscherne H. Knee dislocation. Long term results after operative treatment. Chirurg. 1999;70:1294–301
  3. Arom, Gabriel A., et al. "The changing demographics of knee dislocation: a retrospective database review." Clinical Orthopaedics and Related Research® 472.9 (2014): 2609-2614.
  4. 4.0 4.1 Green NE, Allen BL. Vascular injuries associated with dislocation of the knee. J Bone Joint Surg Am 1977;59:236-9.
  5. Marin EL, Bifluco SS, Fast A. Obesity: a risk factor for knee dislocation. Am J Phys Med Rehabil 1990;69:132-4.
  6. Yu JS, Goodwin D, Salonen D, et al. Complete dislocation of the knee: spectrum of associated soft-tissue injuries depicted by MR imaging. AJR 1995;164:135-9.
  7. Coates M, Stewart N, Morganti V, et al. Magnetic resonance findings in Knee Dislocation: pictorial essay. Australas Radiol 2000;44:373-84.
  8. Richter M, Bosch U, Wippermann B, et al. Comparison of surgical repair or reconstruction of the cruciate ligaments versus nonsurgical treatment in patients with traumatic knee dislocation. Am J Sports Med 2002;30:718-27.
  9. Ng, Jimmy Wui Guan, Yulanda Myint, and Fazal M. Ali. "Management of multiligament knee injuries." EFORT Open Reviews 5.3 (2020): 145-155.
  10. 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 2004;56:1261–1265.
  11. Levy BA, Dajani KA, Whelan DB, Stannard JP, Fanelli GC, Stuart MJ, et al. Decision making in the multiligament-injured knee: An evidence-based systematic review. Arthroscopy. 2009;25:430–8.
  12. Levy BA, Dajani KA, Whelan DB, Stannard JP, Fanelli GC, Stuart MJ, et al. Decision making in the multiligament-injured knee: An evidence-based systematic review. Arthroscopy. 2009;25:430–8.
  13. https://www.orthobullets.com/trauma/1043/knee-dislocation
  14. Medina, Omar, et al. "Vascular and nerve injury after knee dislocation: a systematic review." Clinical Orthopaedics and Related Research® 472.9 (2014): 2621-2629.
  15. Shelbourne KD, Klootwyk TE. Low-velocity knee dislocation with sports injuries. Treatment principles. Clin Sports Med. 2000;19:443–56
  16. Green NE, Allen BL. Vascular injuries associated with dislocation of the knee. J Bone Joint Surg Am. 1977;59:236–9.
  17. McDonough EB Jr , Wojtys EM . Multiligamentous injuries of the knee and associated vascular injuries. Am J Sports Med 2009;37:156–159
  18. Meyers MH, Harvey JP. Traumatic dislocation of the knee joint: a study of eighteen cases. J Bone Joint Surg Am 1971;53:16-29.
  19. Samson D , Ng CY , Power D . An evidence-based algorithm for the management of common peroneal nerve injury associated with traumatic knee dislocation. EFORT Open Rev 2017;1:362–367
  20. Niall DM, Nutton RW, Keating JF. Palsy of the common peroneal nerve after traumatic dislocation of the knee. J Bone Joint Surg Br. 2005;87:664–7.
  21. Cho D, Saetia K, Lee S, Kline DG, Kim DH. Peroneal nerve injury associated with sports-related knee injury. Neurosurg Focus. 2011;31:E11.
  22. Woodmass JM, Romatowski NP, Esposito JG, Mohtadi NG, Longino PD. A systematic review of peroneal nerve palsy and recovery following traumatic knee dislocation. Knee Surg Sports Traumatol Arthrosc. 2015;23:2992–3002.
Created by:
John Kiel on 25 June 2019 19:03:58
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Last edited:
3 May 2021 14:06:38
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