Ch. 27 Immediate Swelling After Trauma to the Knee

Question 1

Knee maneuvers for:

• ACL
• PCL
• Meniscal cartilage
• LCL
• MCL

Answer 1

Question 2

Why is it important to perform a careful vascular exam with knee dislocation or proximal tibia fracture?

Answer 2

Can damage popliteal vessels creating dysvascular limb which may lead to amputation if not recognized and treated

Pulses should always be assessed and ABI performed if there is any uncertainty

Question 3

What is the terrible (aka “unhappy”) triad of the knee?

Answer 3

MCL, ACL, and medial meniscus injuries

Question 4

What is the distribution of blood supply to the meniscus and why is it important?

Answer 4

The menisci receive blood peripherally from outside-in to cover only the outer 25-30% of their diameter.

Tears occurring in the outer “red” zone have the potential to heal and are often repaired. Inner tears in the “white zone” without a direct blood supply have little healing potential and are not repaired, but surgically debrided if needed.

Question 5

What injury would you expect from a dashboard knee injury?

Answer 5

Occurs in MVC when flexed knee hits the dashboard subjecting it to an anterior force

This mechanism is associated with PCL injury and positive posterior drawer test

Question 6

What is the normal range of motion of the knee?

Answer 6

ROM of the knee is tested with the patient lying supine and the hip partially flexed

Normal range is 0-5 degrees extension to 130-140 degrees flexion

Question 7

What is the significance of being unwilling (vs. unable) to range the knee?

Answer 7

Fracture or septic arthritis should be highly suspected

Without an acute trauma or x-rays showing fracture, septic arthritis should be considered and arthrocentesis (tapping the knee and sending the fluid for laboratory analysis) performed

Question 8

Why is it important to examine the patella and its tracking?

Answer 8

The patella has often been called the “low back” of the knee, meaning its problems are often as difficult to treat as chronic low back pain. Patellar dislocations occur laterally and involve an increased Q-angle. Flat feet and knock-knees (valgus) increase the Q-angle.

Question 9

What are the characteristic radiographic features of osteoarthritis of the knee and why is it important to consider after ACL injury?

Answer 9

Radiographic changes consistent with degenerative arthritis in the knee:

• Joint space narrowing
• Osteophytes (bone spurs)
• Subchondral sclerosis
• Subchondral cysts

These changes are critical to recognize as ACL surgery is not appropriate in the setting of significant arthritis of the knee.

Question 10

What imaging would you use to confirm a suspected ACL injury?

Answer 10

MRI

Question 11

What are the different types of ACL grafts used?

Answer 11

• Autograft harvested from pt (bone-patellar tendone-bone or hamstring tendon)
• Allograft from cadaver