• BACKGROUND
    • Knee dislocations resulting in multiligament knee injuries (MLIs) are usually associated with high-energy mechanisms such as motor vehicle accidents or sports injuries; however, obese patients are at risk of MLIs from simple falls. Termed "ultra-low velocity" (ULV) dislocations, these injuries occur in obese patients during activities of daily living and may be associated with higher associated risks and complications.
  • HYPOTHESIS
    • Ultra-low velocity knee dislocations occur more commonly in obese female patients, are associated with higher risks of neurovascular injuries, and have more significant perioperative complications compared with other MLIs.
  • STUDY DESIGN
    • Case series; Level of evidence, 4.
  • METHODS
    • The records of 215 consecutive patients with MLIs were identified over a 12-year period. Their charts were reviewed to identify a cohort of patients with mechanisms consistent with ULV dislocations (n = 23). This cohort was compared with all patients with MLIs. Additionally, ULV patients with neurovascular injuries were compared with those without neurovascular injuries.
  • RESULTS
    • The average body mass index (BMI) was significantly higher in the ULV cohort (49.1 kg/m2) compared with all patients with MLIs (34.1 kg/m2). Injuries occurred more commonly in female patients in the ULV cohort (69.6%) compared with all patients with MLIs (24.3%). Peroneal nerve injuries occurred more commonly in the ULV cohort (39.1%) compared with all patients with MLIs (8.4%), as did vascular injuries (28.1% vs. 4.7%, respectively). Postoperative complications were common among all ULV-MLI patients regardless of neurovascular injury status. Seventeen patients (6/12 in the intact group and 11/11 in the neurovascular injury group) had significant complications postoperatively. A significantly higher overall complication rate was noted in the ULV-MLI group (73.9%) compared with the entire MLI cohort (21.4%). Additionally, the ULV-MLI cohort had a higher reoperation rate, wound infection rate, deep venous thrombosis rate, and presence of vascular claudication.
  • CONCLUSION
    • Ultra-low velocity knee injuries occur in patients with a greater BMI, more frequently in female patients, and with higher rates of concomitant neurovascular injuries compared with other MLIs. Additionally, a significantly greater incidence of postoperative complications can be expected after ligament reconstruction in this population compared with other MLIs.