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Knee Dislocation
From WikiSM
Contents
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
- Multi Ligament Knee Injury, often bicruciate, including ACL + PCL + LCL/MCL
- ACL Injury
- PCL Injury
- MCL Injury
- LCL Injury
- Biceps tendon avulsions
- Popliteus tendon tears
- Arcuate complex injuries
- 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
- Morbid Obesity is a risk factor for low energy mechanism
Differential Diagnosis
- Fractures
- Dislocations & Subluxations
- Patellar Dislocation (and subluxation)
- Knee Dislocation
- Proximal Tibiofibular Joint Dislocation
- Muscle and Tendon Injuries
- Ligament Pathology
- Arthropathies
- Bursopathies
- Patellofemoral Pain Syndrome (PFPS)/ Anterior Knee Pain)
- Neuropathies
- Other
- Bakers Cyst (Popliteal Cyst)
- Patellar Contusion
- Pediatric Considerations
- Patellar Apophysitis (Sinding-Larsen-Johnansson Disease)
- Patellar Pole Avulsion Fracture
- Tibial Tubercle Avulsion Fracture
- Tibial Tuberosity Apophysitis (Osgood Schalatters Disease)
- Proximal Tibial Metaphyseal Fracture
- Proximal Tibial Physeal Injury
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
- Standard Radiographs Knee
- May be normal depending on mechanism
- look for asymmetric, irregular or widening of joint space
- Segund Fracture, Osteochondral Defect may be seen
- Post reduction or post splinting films are necessary
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
- Full extension in long Hinged Knee Brace or Posterior Long Leg Splint
- If posterior capsule injured, may require 20° of flexion to avoid posterior subluxation
- May require temporary external fixation
- 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
- Internal
- External
- Sports Medicine Review Knee Pain: https://www.sportsmedreview.com/by-joint/knee/
References
- ↑ Rihn JA, Groff YJ, Harner CD, Cha PS. The acutely dislocated knee: Evaluation and management. J Am Acad Orthop Surg. 2004;12:334–46.
- ↑ Richter M, Lobenhoffer P, Tscherne H. Knee dislocation. Long term results after operative treatment. Chirurg. 1999;70:1294–301
- ↑ 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.
- ↑ 4.0 4.1 Green NE, Allen BL. Vascular injuries associated with dislocation of the knee. J Bone Joint Surg Am 1977;59:236-9.
- ↑ Marin EL, Bifluco SS, Fast A. Obesity: a risk factor for knee dislocation. Am J Phys Med Rehabil 1990;69:132-4.
- ↑ 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.
- ↑ Coates M, Stewart N, Morganti V, et al. Magnetic resonance findings in Knee Dislocation: pictorial essay. Australas Radiol 2000;44:373-84.
- ↑ 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.
- ↑ Ng, Jimmy Wui Guan, Yulanda Myint, and Fazal M. Ali. "Management of multiligament knee injuries." EFORT Open Reviews 5.3 (2020): 145-155.
- ↑ 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.
- ↑ 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.
- ↑ 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.
- ↑ https://www.orthobullets.com/trauma/1043/knee-dislocation
- ↑ Medina, Omar, et al. "Vascular and nerve injury after knee dislocation: a systematic review." Clinical Orthopaedics and Related Research® 472.9 (2014): 2621-2629.
- ↑ Shelbourne KD, Klootwyk TE. Low-velocity knee dislocation with sports injuries. Treatment principles. Clin Sports Med. 2000;19:443–56
- ↑ Green NE, Allen BL. Vascular injuries associated with dislocation of the knee. J Bone Joint Surg Am. 1977;59:236–9.
- ↑ McDonough EB Jr , Wojtys EM . Multiligamentous injuries of the knee and associated vascular injuries. Am J Sports Med 2009;37:156–159
- ↑ Meyers MH, Harvey JP. Traumatic dislocation of the knee joint: a study of eighteen cases. J Bone Joint Surg Am 1971;53:16-29.
- ↑ 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
- ↑ 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.
- ↑ Cho D, Saetia K, Lee S, Kline DG, Kim DH. Peroneal nerve injury associated with sports-related knee injury. Neurosurg Focus. 2011;31:E11.
- ↑ 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:
4 October 2022 15:45:15
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