A knee dislocation is a complete displacement of the tibia from the femur, disrupting multiple knee ligaments simultaneously. It is one of the most severe orthopaedic injuries because the popliteal artery and peroneal nerve pass close to the knee and are at risk of injury during dislocation. Knee dislocations require urgent evaluation, vascular assessment, and prompt reduction, followed by reconstructive surgery in most cases.
What Is a Knee Dislocation?
A knee dislocation is the complete loss of contact between the femur and tibia. The knee is stabilized by four major ligaments (ACL, PCL, MCL, and the lateral collateral/posterolateral corner). For the knee to dislocate, multiple ligaments must tear simultaneously, typically at least three of the four.
Knee dislocations are classified by direction (anterior, posterior, medial, lateral, rotatory) and by which ligaments are torn (KD I through KD V in the Schenck classification). The injury patterns drive the surgical reconstruction plan.
A critical feature: many knee dislocations spontaneously reduce before the patient reaches medical care. The knee may appear normal on initial inspection, and the dislocation event may only be inferred from the multi-ligament injury pattern on examination and MRI.
Causes and Risk Factors
- High-energy trauma: motor vehicle collisions, falls from height, industrial accidents
- Contact sports collisions (football, rugby, skiing)
- Ultra-low-velocity dislocations in obese patients (a distinct pattern with high vascular risk)
- Hyperextension injuries with rotational force
- Sequential ligament loading during severe valgus or varus injury
Symptoms
- Severe knee pain and gross instability following the injury
- Visible deformity at the time of dislocation, often resolving with spontaneous reduction
- Inability to bear weight
- Signs of vascular injury: cool foot, decreased pulses, expanding hematoma (an emergency)
- Foot drop or sensory loss from peroneal nerve injury
- Examination reveals laxity in multiple directions
Diagnosis
Dr. Chudik’s evaluation prioritizes vascular and neurologic assessment. Pulses, capillary refill, and ankle-brachial index (ABI) are documented. CT angiography is performed when vascular injury is suspected. X-rays evaluate associated fractures. MRI characterizes the specific ligament injury pattern, meniscus involvement, and cartilage status. The Westmont office has on-site high-field MRI and X-ray.
Treatment
Acute management:
- Reduction of any persistent dislocation
- Vascular evaluation; vascular surgery consultation and repair when indicated
- Immobilization in a brace until ligament reconstruction
- Compartment syndrome monitoring
Definitive treatment is multi-ligament knee reconstruction, typically performed two to three weeks after injury for collateral and posterolateral corner repair, with cruciate reconstruction at the same operation or in a staged approach. Dr. Chudik performs combined ACL, PCL, MCL, and PLC reconstruction depending on the specific injury pattern.
Non-surgical management is reserved for older or low-demand patients who accept significant residual instability.
Recovery and Outcomes
Recovery is among the longest in orthopaedic surgery. Brace protection for six to eight weeks with controlled motion. Progressive weight-bearing over the same period. Progressive strengthening over three to four months. Return to sport is typically nine to 12 months at minimum, with some patients requiring longer.
Outcomes depend on the specific ligaments reconstructed, the quality of reconstruction, vascular and nerve status, and rehabilitation adherence. Return to pre-injury sport is lower than for isolated ACL reconstruction.
When to See Dr. Chudik
Schedule urgent evaluation after any high-energy knee injury with gross instability, after any knee dislocation (even one that self-reduced), or any knee injury with foot numbness or pulse changes. Call 630-324-0402 or request an appointment online.