Review Question - QID 2233

This patient needs to be evaluated for a traumatic arthrotomy. At least 155cc of saline should be used to provide a 95% sensitivity.

A saline load test (SLT) is an effective method by which the diagnosis of intra-articular penetration can be made. Traumatic arthrotomy is established if injected fluid is visualized to extravasate through the traumatic wound. Management is dictated by accurate diagnosis of a traumatic arthrotomy, and surgical intervention is indicated in this setting in order to decrease the risk of septic arthritis due to direct communication of the joint with the external environment. CT-imaging may also be used as an adjunct to assess for free-air within the joint.

Voit et al. reviewed the use of a saline load test in 50 consecutive patients with periarticular lacerations of various joints concerning for arthrotomy. The authors reported 100% sensitivity and specificity for the diagnosis of arthrotomy. Comparatively, surgeon prediction of traumatic arthrotomy resulted in false-positive and false-negative rates of 39% and 43%, respectively. They concluded that the use of a saline load test significantly improved diagnostic accuracy of periarticular lacerations.

Nord et al. evaluated the volumes of saline needed in a saline load test to accurately evaluate for a traumatic arthrotomy of the knee. The authors reported that the diagnostic sensitivity was 75%, 90%, 95%, and 99% for volumes of 110, 145, 155, and 175 mL, respectively. They concluded that in order to achieve a 95% sensitivity, at least 155mL of saline should be used.

Figure A shows a normal AP radiograph of the knee.
Figure B shows a normal lateral radiograph of the knee.

Incorrect Answers:
Answer 1: This patient has not been appropriately evaluated for the presence of a traumatic arthrotomy. Closure of a wound that may have intra-articular involvement increases the risk of a septic arthritis.
Answer 3: An arthroscopic debridement and irrigation may be indicated if a traumatic arthrotomy has occurred. However, the diagnosis has not been made and 100cc of saline provides <75% sensitivity in the detection of a traumatic arthrotomy, which is insufficient for the diagnosis.
Answer 4: While CT-imaging may be used as an adjunct to evaluate for intra-articular air, an MRI is not routinely used.
Answer 5: This patient has not been appropriately evaluated for the presence of a traumatic arthrotomy. Without excluding traumatic arthrotomy, allowing the wound to heal by secondary intention would increase the risk of a septic arthritis.