• Knee joint dislocations are a surgical emergency and are associated with injuries to multiple ligaments of the knee with or without an associated fracture.

• Initial management of MLKI is in line with best practice including emergent assessment using ATLS protocol, clear limb assessment and documentation of neurovascular status and appropriate plain imaging.

• Reduction in an emergency setting is mandated as a pain-relieving measure, to relieve pressure on neurovascular structures, soft tissues and to limit damage to the joint. Further plain imaging should confirm appropriate reduction.

• Clear guidance presented on temporary immobilisation and when to consider external fixation.

• Clear guidance presented on further imaging including a computed tomography angiogram (CTA) and magnetic resonance imagining (MRI).

• Escalation as appropriate to clinical team responsible for definitive care of these injuries.

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Abbreviations

Background

• A knee dislocation is loss of articular congruency between the tibio-femoral joint,

• A Multiple Ligament Knee Injury (MLKI) occurs when two or more of the four major knee ligaments are torn: Anterior Cruciate Ligament (ACL), Posterior Cruciate Ligament (PCL), the medial side (often collectively referred to as the Posteromedial Corner, PMC), or the lateral side/complex (the Posterolateral Corner, PLC / LCL). ⁽¹⁾

• Epidemiology / Rarity: MLKI are rare — accounting for < 0.02% of all orthopaedic injuries in the general population.

• Common cause: Many MLKIs result from a Knee Dislocation — often high-energy trauma (e.g. motor-vehicle accidents, falls) but also low and ultra-low energy mechanisms (e.g. sports injuries, hyperextension in obese patients). ⁽²⁾

• Complexity and heterogeneity: MLKI rarely affects only ligaments. Typically, there is associated damage: soft-tissue envelope, menisci, articular cartilage (chondral injury), sometimes fractures; plus, risk of neurovascular injury (popliteal artery, peroneal nerve). ⁽³⁾

Why is this a problem?

• Limb-threatening — vascular / nerve risk: There is a high risk of vascular injury, particularly to the popliteal artery. In MLKIs, incidence of vascular insult (or delayed thrombosis) is substantial. If not identified and treated urgently, risk of amputation or permanent neurovascular compromise is real. ⁽³⁾

• Missed knee dislocation - many knee dislocations reduce spontaneously before presentation — without obvious dislocation on initial radiograph — leading to under-recognition of multiple ligament tears. Without high index of suspicion, associated cartilage, meniscal or soft-tissue injuries may be overlooked

• Functional prognosis unpredictable: Even after surgical treatment, long-term outcomes are variable. Patients may have residual instability, reduced range of motion (ROM), stiffness, or poor return to sport / pre-injury activity. The heterogeneity in injury patterns (ligament combinations, cartilage/meniscus involvement, soft-tissue compromise) means each case behaves differently. ⁽³⁾

• Risk of complications: Early (acute) surgery is associated with a higher risk of stiffness, loss of flexion, and need for secondary procedures for arthrofibrosis; but delayed or staged surgery may prolong instability, limit early mobilization, and complicate soft-tissue healing.

• Need for high surgical expertise and tailored approach: Successful treatment requires appropriate emergent management, followed by early expert involvement in order to plan the appropriate definitive treatment tailored to the patient.

This guideline outlines the assessment, investigation, acute stabilisation, surgical management and rehabilitation of all knee dislocations and multi-ligament knee injuries in both adults and children. It applies to high-energy and low-energy mechanisms, including sports-related and spontaneous reductions, and encompasses associated complications such as neurovascular compromise, fractures, meniscal and chondral injury. The guideline is intended for use by clinicians involved in emergency, orthopaedic, trauma and rehabilitation care. ⁽⁴⁾

1. All patients to be initially assessed using ATLS principles

2. A detailed neurovascular examination with clear documentation of capillary refill time, distal pulses, function of all lower limb compartments and common peroneal/tibial nerve function should be carried out at initial presentation

3. An initial attempt to reduce a dislocated knee should be performed under adequate analgesia/sedation in ED resus by the orthopaedic on-call team clear documentation of neurovascular status pre and post reduction.

4. Knee plain radiographs to be performed post reduction and immobilisation to assess reduction

5. All cases of knee dislocation/suspected knee dislocation should have an emergency CT angiogram to assess vascularity

6. If vascularity intact, mild subluxation can be accepted without the need for an external fixator

7. The knee should then be immobilised in 20degrees of flexion either in a brace or plaster of paris

8. Indications for external fixation should ONLY be considered when:

   a. An acceptable reduction cannot be achieved with a brace/plaster of paris

   b. Vascular injury is present and/or vascular repair is required

   c. Locked knee dislocations not amenable to closed reduction and requiring open reduction

   d. Open injuries

   e. Associated fracture of the plateau or distal femur

9. If an external fixator is required this should be placed AWAY from the zone of injury, with the femoral pins being lateral/anterolateral (NOT ANTERIOR), and tibial pins distal to the region of the pes anserinus. A good marker is 10-15cm proximal (femoral pins) and distal (tibial pins) to the joint line.

10. If there is any suspicion of vascular injury clinically despite normal ABPI/Angiogram studies, then this should be discussed with the vascular surgeons regardless.

11. Knee dislocation cases to be referred to the knee team at the earliest opportunity for definitive work-up and planning.

12. If there are any concerns about the form of stabilisation (i.e. unclear as to whether an external fixator may be required), then this can be discussed with a member of the knee team prior to external fixation.