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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

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