CT Scan versus Saline Load Test for Detection of Traumatic Wrist Arthrotomy.

Traumatic arthrotomy of the wrist is most commonly detected using the saline load test (SLT); however, little data exists on the effectiveness of the SLT to this specific joint. The use of computed tomography (CT) scan has been validated as an alternative method to detect traumatic arthrotomy of the knee, as the presence of intra-articular air can be seen when there is violation of the joint capsule.  The purpose of this study was to determine the ability of CT scan to identify arthrotomy of the wrist capsule and compare the diagnostic performance of CT versus traditional SLT.  Ten fresh frozen cadavers which had undergone transhumeral amputation were initially used in this study. A baseline CT scan was performed to ensure no intra-articular air existed prior to intervention. After baseline CT, an arthrotomy was created at the 6R radiocarpal portal site. The wrists then underwent a postarthrotomy CT to identify the presence or absence of intra-articular air. Following CT, the wrists were subjected to the SLT to detect the presence of extravasation from the arthrotomy.  Nine cadavers were included following baseline CT scan. Following arthrotomy, intra-articular air was visualized in eight of the nine cadavers in the postarthrotomy CT scan. Air was seen in the radiocarpal joint in eight of the nine wrists; midcarpal joint in seven of the nine wrists; and distal radioulnar joint in six of the nine wrists. All wrists (nine of the nine) demonstrated extravasation during the SLT. The mean volume of extravasation occurred at 3.7 mL (standard deviation = 2.6 mL), with a range of 1 to 7 mL.  CT scan correctly identified eight of the nine simulated traumatic arthrotomies. Injection of 7 mL during the SLT was necessary to identify 100% of the arthrotomies.  CT scan is a sensitive modality for detection of traumatic arthrotomy of the wrist in a cadaveric model.