9.14 Knee Sprain
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agk's Library of Common Simple Emergencies

Presentation
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An athlete may have planted the foot while 
decelerating, torn the anterior cruciate 
ligament allowing the tibia to dislocate 
anteriorly, fallen to the ground where it 
spontaneously relocated, and not been able to 
get up. Alternatively, he may have been clipped 
on the lateral knee, causing a valgus deformity 
which tore the medical collateral ligament and 
perhaps the medial meniscus and anterior 
cruciate as well. An adolescent girl may have 
dislocated her patella laterally, tearing the 
medial retinaculum. These sorts of injury tend 
to come to the ED within an hour or two, in 
pain, holding the knee flexed ten to twenty 
degrees, with a tense joint effusion and 
quadriceps spasm which prevents detailed 
diagnosis by physical examination.

What to do:
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- If the patient has not already done so, ice 
    and elevate the injury. 
- Load with anti-inflammatory analgesics like 
    ketorolac (Toradol) 60mg im or ibuprofen 
    (Motrin) 800mg po.
- Examine as permitted by pain. Clear the back 
    and pelvis. Check hip flexion, extension, 
    and rotation. Thump the sole of the foot as 
    an axial loading clue to a tibia or femur 
    fracture. Document any effusion, 
    discoloration, heat, deformity, loss of 
    function, circulation, sensation, movement.
- Document the range of motion, then carry out 
    the rest of the exam with the knee slightly 
    flexed, always comparing to the uninjured 
    knee. Palpate the medial and lateral 
    collateral ligament and test them with 
    varus and valgus stress. Palpate the joint 
    line anteriorly to assess the menisci and 
    tibial plateaux. Draw the tibia anterior 
    and posterior to test the cruciates (the 
    Lachman test).
- Obtain x-rays. 
- Aspirate the joint only if you need to rule 
    out infection or obtain a few hours of 
    mobility.
- Discharge the patient with the knee 
    immobilized in a splint or Jones dressing, 
    crutches, a prescription for NSAIDs, and an 
    appointment for orthopedic re-evaluation in 
    3-4 days.

Discussion
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Chronic injuries can also be treated with 
NSAIDS, immobilization, and crutches. Examples 
include meniscal tears and joint mice, which 
may present with a history of the knee catching 
or giving way, and even flareups of osteo- 
arthritis, degenerative joint disease, and 
pseudogout.

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 from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES
 Longwood Information LLC 4822 Quebec St NW Wash DC
 1.202.237.0971 fax 1.202.244.8393 electra@clark.net
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