Disclosures: Annemarie K. Leonard, BS: No financial relationships or conflicts of interest

Case Diagnosis: An 18-year-old female with Marfan Syndrome and BMI of 34 kg/m2 experienced ultra-low velocity posterior knee dislocation complicated by closed tibial plateau fracture, popliteal artery dissection, and soft tissue injury requiring surgical management.

Case Description: An 18-year-old female with Marfan syndrome and BMI 34 kg/m2 stepped off a curb resulting in right posterior knee dislocation with closed tibial plateau fracture, dissection of right popliteal artery, and ligamentous injury. She underwent Open Reduction Internal Fixation (ORIF) of right tibial plateau, arthroscopic medial meniscus repair, and external fixation of the knee. She underwent a right femoral-popliteal artery bypass. MRI was notable for complex tears of both menisci, complete PCL disruption, partial ACL and patellar tendon tears, and popliteus tendon avulsion. Post-operatively, she developed foot drop due to common peroneal nerve traction. She presented for inpatient rehabilitation with right sided external fixation device in place, decreased mobility, and activity of daily living (ADL) impairments.

Setting: Inpatient Rehabilitation FacilityAssessment/

Results: The patient was discharged home at an independent level with imminent orthopedic follow up to determine further surgical management.

Discussion: Ultra-low velocity (ULV) injuries, rare injuries due to same-level fall, are reported to occur in patients with BMI 30 to 68 kg/m2. Obesity is hypothesized to contribute to hyperlaxity, increasing the risk of ULV knee dislocations. The patient’s hyperlaxity in the setting of connective tissue disease and obesity combined with the force exerted on the knee from her weight resulted in significant morbidity. Due to associated ligamentous and vascular injury, external fixation was applied for improved post-operative outcomes. However, this resulted in functional deficits requiring admission to an Inpatient Rehabilitation Facility (IRF) for pain control, improvement in mobility, and ADL management.

Conclusion: This case demonstrates significant injury and functional impairment from ULV trauma in the setting of hyperlaxity due to both secondary genetic and acquired factors.

Level of Evidence: Level V

« Back to AAPM&R Annual Assembly 2021

PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/ultra-low-velocity-posterior-knee-dislocation/