Reduction - Knee dislocation
This procedure is usually performed using procedural sedation which is covered separately
Indications
Knee dislocation
Contraindications (absolute in bold)
Life- or limb-threatening conditions
Associated fracture
Open dislocation
Fractures of pelvis or femur (risk of displacement during reduction)
Alternatives
Reduction by orthopaedic team in emergency department
Reduction in operating theatre
Informed consent
Medical emergency
Consent is not required if the patient lacks capacity or is unable to consent
Brief verbal discussion is recommended if the situation allows
or
Written consent
More complex non-emergency procedure with higher risk of complications
Potential complications
Failure (of reduction, of immobilisation or recurrence)
Vascular damage (popliteal artery injury leading to ischaemia and loss of limb)
Neurological damage (fibular nerve)
Compartment syndrome
Conversion to an open injury
Fracture
Procedural hygiene
Standard precautions
PPE: non-sterile gloves
Area
Resuscitation bay
Staff
Procedural clinician and assistants
Additional clinicians required for procedural sedation
Equipment
None
Positioning
Supine in a bed with head elevated
Medication (for procedural sedation)
IV pain relief prior to procedure:
Fentanyl 50-100mcg IV or morphine 5-10mg IV titrated to relief of pain
Often followed by procedural sedation:
No single sedative agent recommended for every patient, typically
Nitrous oxide 50-70% titrated to pain relief or
Bolus ketamine or propofol 1mg/kg (dose reduced to 0.3-0.5mg/kg if frail or elderly)
Further titrated 20mg boluses to minimum level required for patient comfort
Sequence
Examination for other injuries and fractures
Neurovascular assessment of foot (pulses, capillary refill, power and sensation)
Bedside pre-reduction X-rays (see discussion)
Analgesia and procedural sedation
Apply steady traction below the knee and counter traction above the knee
If unreduced apply pressure to the lower leg aiming to reduce deformity
Post-procedure care
Check X-ray, circulation and limb function:
Assess joint stability with gentle passive movement of joint
Reassess vascular status (pulses, cap refill, ankle brachial pressure index, pulse oximetry)
Reassess neurological status (sensation, power)
Immobilise in a long leg backslab in 20 degrees of flexion (with window for vascular assessment)
Obtain post-reduction X-ray (patient should not leave the department until confirmed satisfactory)
Obtain CT angiogram and vascular consult
Ongoing care:
Consider tetanus (ADT) and antibiotic cover (cefazolin 2g IV) for open wounds
Discuss with orthopaedics and admit under their care with two-hourly vascular observations
Document procedure, neurovascular assessments, X-ray findings and management plan
Tips
All knee dislocations require admission and vascular observation or investigation
Early orthopaedics involvement is indicated for all knee dislocations
Search for other fractures and serious injuries when treating a dislocated joint
Reassurance, verbal distraction, effective pain relief and sedation all aid successful joint relocation
Slight traction distal to the dislocation is often enough to relocate the joint
Discussion
Bedside pre-reduction X-rays are recommended to confirm dislocation and identify fracture dislocations prior to reduction attempts. Vascular compromise or threatened skin penetration indicate the need for prompt relocation, however there is usually time for an X-ray during preparation for the procedure while pain relief is provided.
Damage to the popliteal artery with risk of limb loss due to ischaemia occurs in 25% of knee dislocations, either with transection or intimal injury which can lead to thrombosis. We have suggested ordering CT angiography for all patients with confirmed or suspected knee dislocation.
There is however good evidence that arterial injury can be diagnosed using ankle brachial pressure indices. If CT is not available, patients with normal pulses and ankle brachial pressure indices of >0.9 after reduction may be observed in hospital with serial examination of vascular status and monitoring for compartment syndrome. Any patient with hard signs of vascular deficit requires either urgent angiography and/or vascular consult for potential operative intervention.
Some knee dislocations are not reducible, and patients should be taken emergently to the operating room for an open reduction.
Peer review
This guideline has been reviewed and approved by the following expert groups:
Emergency Care Institute
Please direct feedback for this procedure to ACI-ECIs@health.nsw.gov.au.
References
Roberts JR, Custalow CB, Thomsen TW. Roberts and Hedges’ clinical procedures in emergency medicine and acute care. 7th ed. Philadelphia, PA: Elsevier; 2019.
Dunn RJ, Borland M, O’Brien D (eds.). The emergency medicine manual. Online ed. Tennyson, SA: Venom Publishing; 2019.
Bachman MC. Knee (tibiofemoral) dislocation and reduction. In: UpToDate. Waltham (MA): UpToDate. 2020 Feb 6. Available from: https://www.uptodate.com/contents/knee-tibiofemoral-dislocation-and-reduction
Boyce RH, Singh K, Obremskey WT. Acute management of traumatic knee dislocations for the generalist. J Am Acad Orthop Surg. 2015;23(12):761-768. doi:10.5435/JAAOS-D-14-00349
Medina O, Arom GA, Yeranosian MG, Petrigliano FA, McAllister DR. Vascular and nerve injury after knee dislocation: a systematic review. Clin Orthop Relat Res. 2014;472(9):2621-2629. doi:10.1007/s11999-014-3511-3