Posterior Sacroiliac Joint Fusion for Severe Sacroiliac Joint Disorders: A Technical Note on Surgery Using Transarticular Cylindrical Cages Combining Posterior Instrumentation and its Surgical Outcomes.

INTRODUCTION: Anterior sacroiliac joint (SIJ) fusion has been performed for severe SIJ disorders and has demonstrated stable long-term outcomes; however, its relatively high invasiveness remains a significant concern. To overcome this limitation, we developed a posterior fusion using transarticular cylindrical cages combined with posterior instrumentation. This study describes the posterior SIJ fusion technique and evaluates the surgical outcomes. TECHNICAL NOTE: An S1 pedicle screw is inserted toward the sacral promontory, and two S2 alar-iliac screws are placed in the ilium. All three screws are connected to a rod. One or two cylindrical cages filled with cancellous bone are inserted into the SIJ via a trans-iliac bony channel lateral to the posterior superior iliac spine to promote fusion in the anterior-superior portion of the SIJ while preserving the posterior sacroiliac ligaments. Seventeen patients (20 joints) with SIJ disorders were followed for a mean period of 53±23 months. Bone union was obtained in 93.3% of joints. Postoperative SIJ pain evaluated by the visual analog scale significantly improved from 87±18 to 24±25 mm (p<0.0001), and activities of daily living, assessed by the Denver SIJ Questionnaire, improved from 32±11 to 18±16 (p=0.0002). CONCLUSIONS: The posterior SIJ fusion technique using transarticular cylindrical cages via a trans-iliac bony channel combined with posterior instrumentation resulted in favorable postoperative outcomes in patients with SIJ disorders.