A Prospective Randomized Noninferiority Trial Comparing Upper and Lower One-Third Joint Approaches for Sacroiliac Joint Injections.

BACKGROUND: Sacroiliac intraarticular injection using the upper one-third joint technique is recommended for injections that are difficult with the lower one-third joint technique.

OBJECTIVE: To evaluate the success rate of intraarticular sacroiliac joint (SIJ) injections using the upper and lower one-third joint techniques.

STUDY DESIGN: Prospective randomized noninferiority study.

SETTING: An interventional pain-management practice in a university hospital.

METHODS: In this single-blind, noninferiority trial, 181 patients were randomly assigned to either the upper (group U, 90 patients) or lower (group L, 91 patients) one-third joint techniques. The primary end point was the rate of successful intraarticular injections (%), with a noninferiority margin of 10 percentage points. The secondary end points included numeric rating scale (NRS) pain scores before, during and after the procedure, procedure time, degree of contrast spread, and occurrence of intravascular uptake or complications.

RESULTS: The intraarticular injection rate was 93.3% (84 of 90 patients) in group U and 95.6% (87 of 91 patients) in group L (difference, 2.6 percentage points; 95% confidence interval, -8.9 to 4.4). This study found no significant between-group differences in the degree of contrast spread throughout the joint (88.1% with group U and 87.4% with group L, P = 0.883), intravascular incidence (11.1% and 9.9%, respectively; P = 0.789), rate of complications (1.1% and 1.1%, respectively; P = 1.000), inadvertent spread beyond the joint (12.2% and 19.8%, respectively; P = 0.201), or mean post-procedural NRS score for pain (2.24 ± 1.87 and 2.52 ± 1.97, respectively; P = 0.342). However, the mean procedure time (111.2 ± 72.7 and 77.8 ± 60.4 s, respectively; P = 0.001), and mean NRS score for pain during the procedure differed significantly between the groups (2.28 ± 1.45 and 1.77 ± 0.99, respectively; P = 0.006).

LIMITATIONS: This study was designed as a noninferiority study of successful intraarticular injection rates and did not evaluate long-term outcomes.

CONCLUSIONS: The upper one-third joint technique for performing SIJ injections was not inferior to the lower one-third joint technique in terms of the intraarticular injection success rate.

KEY WORDS: Fluoroscopy, low back pain, lower one-third joint technique, sacroiliac joint, sacroiliac joint injection, upper one-third joint technique.