Evaluation of saline load test for simulated traumatic arthrotomies of the ankle

A tool frequently used for evaluation of a traumatic arthrotomy is the saline load test. No information exists in the current literature guiding what baseline fluid infusion is required to reliably detect or diagnose a traumatic ankle arthrotomy. The purpose of this study was to provide a reliable benchmark when employing the saline load test for complex ankle soft-tissue wounds with suspected intra-articular involvement.

Twenty-one consecutive patients presenting for elective ankle arthroscopy underwent simulated saline load tests. After placement of an approximately 4-mm standard lateral portal, an 18-gauge needle was inserted into the anteromedial ankle joint and normal saline was injected until frank extravasation from the lateral arthrotomy was observed. The amount of saline required to diagnose a simulated traumatic arthrotomy was recorded.

The average amount of normal saline that resulted in extravasation was 10.3 cm(3). In order to identify 90% and 95% of simulated ankle arthrotomies, 23 and 30 cm(3) of saline were required, respectively. The average preoperative range of motion did not correlate with saline infusion requirements (r(2)=0.013368).

Based on these results, a minimum infusion of 30 cm(3) is recommended to identify 95% of traumatic arthrotomies approximately 4mm in size. This value needs to be interpreted with the understanding that this study is limited by its inherently simulated nature. An infusion of 30 cm(3) represents a relatively safe and reasonable standard to apply to any potential ankle injury in which joint violation remains in question.