"Successful minimally invasive sacroiliac joint fusion in patients presenting with concomitant sacroiliac joint...

Sacroiliac joint dysfunction is a common cause of lower back pain, especially in patients undergoing lumbar fusion surgery. While spontaneous bony fusion, i.e. auto-fusion, of the sacroiliac joint may provide mechanical stability, the underlying pathophysiology of this disease remains incompletely understood. Here, we present two patients with pre-operative auto-fused joints presenting with sacroiliac joint dysfunction who underwent successful minimally invasive sacroiliac joint fusion.

Two patients presented with pre-existing radiologic auto-fusion of their sacroiliac joints with intra-articular injection-proven sacroiliac joint dysfunction refractory to conservative management. Both patients underwent minimally invasive sacroiliac joint fusion and reported complete and sustained pain relief persisting at one year post-operatively. Radiologic findings confirmed the appropriate placement of fixation hardware without complications.

These cases challenge the conventional understanding that bony fusion resolves sacroiliac joint dysfunction by highlighting the potential role of non-mechanical factors, including neural contributions, in driving persistent pain. Neural innervation of the sacroiliac joint, including lateral branches of the L5-S3 dorsal rami, may be implicated, as supported by recent evidence of effective neural-based interventions.

This report highlights that sacroiliac joint dysfunction may be present in patients with pre-existing auto-fusion. The presence of bony fusion of the sacroiliac joint(s) may not preclude a diagnosis of sacroiliac joint dysfunction, and patients may benefit from minimally invasive fusion surgery. The underlying mechanism of sacroiliac joint dysfunction is complex and incompletely understood.