Acute Knee Trauma

Farhan Quader

June 2013

Eliona Corrigan, MD

• 55 y/o female with hx of total knee arthroplasty presented to ED after fall– height of 3-5’ onto concrete– point of impact = left knee

• Could not ambulate after fall• Endorsed tingling around the site which later

resolved– +Pain around site, 10/10

H&P

• PMH: – HTN, obesity, sickle cell trait

• PSH:– Total Knee Arthroplasty

• Physical exam: Left knee deformed, tibia anteriorly translocated. No ankle nor hip pain. Brisk cap refill, however, palpable dp/pt on right side with weakly palpable dp on left and non-palpable pt

Ddx:– Knee dislocation– Contusion– Ligament sprain/tear– Things to consider: arterial/venous insufficiency

Screening:- Knee radiograph- Ultrasound- CT- MRI

DDx and Screening

Screening Modality

• Patient falls under variant 2: inability to bear weight

• Procedure of choice is X-ray knee

• Ottawa Knee Rule: patients with acute knee pain with 1 or more should have X-ray:– Are 55 years of age or older– Have palpable tenderness over the

head of the fibula– Have isolated patellar tenderness– Cannot flex the knee to 90 degrees– Cannot bear weight immediately

following the injury,– Cannot walk in the emergency

room (after taking four steps).

Left Knee Radiograph AP and Lateral Knee

5299990

AP view unremarkable Lateral view remarkable

Left Knee

Left Knee Radiograph AP and Lateral (previous)

5299990

Knee

Knee Radiograph, Lateral view s/p reduction

5300218

Left Knee Xray

Left Knee Radiograph AP and lateral s/p reduction

5300218

Left Knee

Popliteal Ultrasound ultrasound

Left Popliteal artery

Ultrasound longitudinal

Left Popliteal artery

Popliteal arteriogram

Conclusion

- Anterior dislocations are most common after knee trauma- Dislocations characterized in terms of tibial displacement with

respect to femur (anterior, posterior, medial, lateral, and rotary)- Further characterized into high velocity and low velocity

- High: violent force such as car accident; result in damage to the structures of the knee complex

- Low-velocity: occur in sports settings and seen in athletic trainers; lower rates of neurovascular and associated soft-tissue damage

- Predisposing factor = injury to ACL or MCL- Damage to neurovascular system is one of the greatest concerns - Popliteal artery is injured in approximately 20-40% of all knee

dislocations- Peroneal nerve can still be injured due to it’s anatomical location

as it passes around the fibular neck; 33% of knee dislocations