Acromio-clavicular Joint Separation

Disruption of the right A-C joint, in this case caused by trauma.

Evaluation of Collateral Ligament Injury

No validated rules have been formulated for the use of radiography in patients with suspected ligament injuries, but a decision tree can be used as a guide (Figure below).
Although plain radiographs may be useful in the initial diagnosis of these injuries, magnetic resonance imaging (MRI) is becoming the preferred diagnostic method and is rapidly replacing other techniques as the study of choice for the evaluation of knee injuries. However, the routine use of MRI has been questioned because of its significant cost ($600 to $1,200) and the high accuracy of clinical examination in diagnosing some injuries.

Ottawa knee rule

A knee x-ray is only required for knee injury patients with any of these findings:

• age 55 or over
• isolated tenderness of the patella (no bone tenderness of the knee other than the patella)
• tenderness at the head of the fibula
• inability to flex to 90 degrees
• inability to weight bear both immediately and in the casualty department (4 steps - unable to transfer weight twice onto each lower limb regardless of limping)