Evaluation of Knee Complaints

History

• locking: mechanical block to extension
  • torn meniscus/loose body in joint
• pseudo-locking: limited ROM without mechanical block
  • effusion, muscle spasm after injury, arthritis
• painful clicking (audible)
  • torn meniscus
• giving way: instability
  • cruciate ligament or meniscal tear, patellar dislocation

Knee Hx. (CLIPS)
Clicking Locking Instability Pain (locat Swelling

Special Tests of the Knee

• physical examination can be difficult in acute knee injuries, immobilize leg reexamine in one week

Anterior and Posterior Drawer Tests

• demonstrate torn ACL and PCL, respectively
• knee flexed at 90o, foot immobilized, hamstring
• if able to sublux tibia anteriorly then ACL may be torn
• if able to sublux tibia posteriorly then PCL may be torn

Lachmann Test

• demonstrates torn ACL (most sensitive)
• hold knee in 10-20o flexion, stabilizing the femur
• try to sublux tibia anteriorly on femur
• similar to anterior drawer test, more reliable due to less muscular stabilization

Common Causes of Acute Hemarthrosis
ACL or PCL tear Peripheral meniscal tear Osteochondral # Capsular tear

Posterior Sag Sign

• demonstrates torn PCL
• may give a false positive anterior draw sign
• flex knees and hips to 90o, hold ankles and knees
• view from the lateral aspect
• if one tibia sags posteriorly compared to the other, its PCL is torn

Pivot Shift Sign

• demonstrates torn ACL
• start with the knee in extension
• internally rotate foot, apply valgus force to knee
• look and feel for anterior subluxation of lateral tibial condyle
• slowly flex while palpating knee and feel for pivot (which is the tibiofemoral reduction)
• reverse pivot shift (start in flexion, externally rotate, apply valgus and extend knee) suggests torn PCL

Collateral Ligament Stress Test

• palpate ligament for “opening” of joint space while testing
• with knee in full extension apply valgus force to test MCL, apply varus force to test LCL. Repeat tests with knee in 20 degrees flexion to relax joint capsule
• opening only in 20 degrees flexion due to MCL damage only
• opening in 20 degrees of flexion and full extension is due to MCL, cruciate, and joint capsule damage
  
  
  Tests for Meniscal Tear
• crouch compression test
  • joint line pain when squatting (anterior pain suggests patellofemoral pathology)
• McMurray’s test
  • with knee in flexion palpate joint line for painful "pop/click"
• internally rotate foot, varus stress, and extend knee to test lateral meniscus
• externally rotate foot, valgus stress, and extend knee to test medial meniscus

X-Rays

• AP standing, lateral
• skyline – tangential view with knees flexed at 45 degrees to see patellofemoral joint
• 3-foot standing view – useful in evaluating leg length and varus/valgus alignment

A very common problem in the emergency department. These can be difficult to assess and important injuries are frequently missed.



History:

1. Mechanism? – Find out exactly the injury occurred, the direction and amount of force.
2. "Snap, crackle and pop"? – did the patient feel or hear anything.
3. Swelling? – was this immediate (likely haemarthrosis) or slow onset over a few hours.
4. Pain? – onset, severity and site (medial, lateral, anterior, posterior)
5. Activity? – could he/she finish the game/walk/move the knee after the injury

Physical:



The patient with an acute knee injury is anxious! Unless he/she is relaxed the knee exam will be useless. Get the patient to put their head back on a pillow, place their hands on their stomach and let them know you will not hurt them

1. Look for open injury, bruising, swelling, deformity and malalignment.
2. Feel gently for swelling and local tenderness.
3. Test straight leg raise and active ROM ? progress to passive ROM
4. With the knee at 90? check MCL/LCL and joint-line tenderness.
5. Check for MCL/LCL laxity, the Lachman, anterior and posterior drawer.

Common Problems

MCL Tear

• valgus injury;
• may have a mild effusion;
• often unable to fully extend knee (can be confused with a medial meniscus tear);
• more tender over femoral condyle or medial tibial insertion of ligament than the joint line;
• pain on valgus stress.

Grade I mild sprain, painful, no opening on valgus stress

• rest, ice, compression, rehab.

Grade II severe sprain/mild tear, very painful, slight opening

• splint (leg Zimmer), rest, ice, rehab

Grade III complete tear, less pain, marked opening

• conservative Rx if isolated.
• consider surgery if associated with other injuries.

Medial Meniscus

• twisting injury with medial pain and swelling over 2-4 hours;
• may present with "locked knee" (inability to fully extend) with "spongy painful block;
• tender over medial joint line,
• positive McMurray test.

Full ROM – Jones bandage/Zimmer splint, crutches, rest/ice, return for Reassessment 1 week


"Locked" – Admit acutely for arthroscopy.

ACL

• frequently missed at the time of injury.
• valgus injury, twist on planted foot, landing from a jump;
• immediate swelling to give painful, tense haemarthrosis;
• minimal tenderness unless associated with MCL or Medical Meniscus tear;
• positive Lachman/Anterior Drawer (but may be difficult to elicit.)

Treatment:

• controversial!
• most try a course of rehabilitation/activity modification +/- a brace.

Patellar Dislocation

• often referred as a "dislocated knee" (a very serious high-energy injury).
• often occurs in less fit individuals, the "weekend athlete".
• history of sudden twist, severe knee pain, "out of joint" immediate swelling.
• may reduce spontaneously.

Treatment:

• reduce under sedation by gentle knee extension and pushing the patella medially. (It dislocates laterally!).
• if already reduced then severe medial patellar tenderness, swelling and positive apprehension to attempted lateral subluxation is diagnostic.
• check X-ray carefully for osteochondral fracture, particularly on skyline view. Immobilize in extension in a Jones dressing with plaster.
• Cylinder cast/Zimmer splint for 3-4 weeks ? rehab