Digital Subtraction Air Arthrography: An Innovative Technique for Needle Tip Location Confirmation

This article describes an innovative technique to confirm needle tip positioning using digital subtraction fluoroscopy and air within a targeted joint. Digital subtraction fluoroscopy with air was utilized to confirm intra-articular needle tip position in 12 joints over a 14-month period at a single institution. Procedural details were recorded for each joint including: joint location, fluoroscopy time, patient age, patient body mass index, and change in subjective pain rating following the injection. Shoulder and hip phantoms were utilized to compare radiation dose differences between fluoroscopy with digital subtraction technique and fluoroscopy without digital subtraction technique. All of the 12 injections were technically successful with air clearly visualized within each targeted joint and subjective pain ratings either did not change or decreased following the injection. Patient age ranged from 51 to 87 years old and body mass index values ranged from 19.2 to 37.1 kg/m2. Fluoroscopy times ranged from 11.1 to 32.9 seconds. There were no complications during or immediately following the injections. The addition of digital subtraction technique increased the skin dose at the shoulder by approximately 2.6 times and at the hip by approximately 2.2 times. Likewise, the cumulative dose at the shoulder increased by approximately 2.7 times and at the hip by 2.0 times. Fluoroscopic digital subtraction air arthrography is a valuable option for needle tip confirmation when using air as a contrast agent. This novel combination of established fluoroscopic techniques can be incorporated into most clinical practices.