Objective: To determine the influence of arthroscopy and injection volume on post-procedure intra-articular (IA) injection extravasation.
Study design: Ex vivo prospective study.
Sample population: A total of 40 paired canine cadaver forelimbs.
Methods: After radiographs and computed tomography (CT) scans with three-dimensional (3D) digital bone model reconstructions, elbows were randomly assigned to the arthroscopy or control group and randomly assigned to receive an IA injection of 2 or 4 mL of contrast. Elbow arthroscopy was performed on assigned specimens, followed by IA injections of contrast in all elbows, and imaging was repeated. 3D digital model volumes were compared. Images were interpreted and scored for extravasation by a radiologist unaware of treatment and volume assignments.
Results: Based on CT images and regardless of treatment group, IA injections of 4 mL resulted in a mean extravasation score of 2.25 (SD 0.97) versus 1.55 (SD 1.05) (p = .02) for 2 mL IA injections. The change in 3D model volumes after IA injections was a mean of 13.2 cm3 (SD 5.85) after 4 mL injections, compared to 6.97 cm3 (SD 6.28) (p = .003) after 2 mL injections. On radiographic evaluation, but not CT, the mean extravasation scores were 2.45 (SD 1.15) for the arthroscopy group and 1.25 (SD 0.79) for the control group (p < .001).
Conclusion: A larger volume of IA injection resulted in higher CT extravasation scores and larger 3D volumes regardless of arthroscopic treatment.
Clinical significance: IA injections performed immediately after arthroscopy resulted in 50% or less extravasation, especially with a smaller IA injection volume.
