Working Diagnosis:
Anterior tibial dislocation, Grade 3 ACL and LCL tears, extensive grade 2 PCL sprain, grade 1 MCL sprain, posterolateral corner injuries

Treatment:
Manual Reduction in the Emergency room followed by staged surgical repair of the ACL, PCL, MCL, LCL.

Outcome:
Patient underwent manual reduction on presentation to the Emergency room. Orthpopedic surgeon subsequently performed a right knee posterolateral corner reconstruction. Post-operatively the patient worked with physical therapy and was cleared for discharge home with 24 hour assist and a bariatric rolling walker. She was instructed to follow up with ortho outpatient for planning of staged ACL and PCL reconstruction.

Author's Comments:
Knee pain is common, but knee dislocation is rare and accounts for less that 0.2% or orthopedic injuries. Dislocation requires multi-ligament injury and a force typically associated with high velocity trauma. However, damaging forces may also be achieved with smaller accelerations if the patient has a large body mass. This is concerning because it requires clinicians to approach their obese patients cautiously when evaluating knee pain after seemingly minor injuries.

Editor's Comments:
True knee dislocation (not to be confused with patellar dislocation) can only result from multiligamentous injury and typically requires high force but unusually can happen with large body mass as illustrated in this case. Knee dislocation is considered a musculoskeletal emergency and vascular status must be carefully evaluated to rule out popliteal artery injury.

References:
1. Robertson A, Nutton RW, Keating JF. Dislocation of the knee. J Bone Joint Surg Br. 2006;88(6):706-711
2. Nickless J, Chandran S, Mohan V. Recognition to Rehabilitation: Treating Traumatic Knee Injuries. Consultant. 2015;55(8):601-613
3. Georgiadis, AG., Mohammad F, Mizerik KT, Nypaver TJ, Shepard AD. Changing presentation of knee dislocation and vascular injury from high-energy trauma to low-energy falls in the morbidly obese. Journal of Vascular Surgery. 2013;57(5) 1196-203

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