Establishing Robot-Navigated Sacroiliac Joint Fusion as a Novel and Viable Salvage Procedure for Lumbopelvic Fixation Failure

Introduction: Lumbopelvic fixation failure (LFF) remains prevalent in adult spinal deformity patients undergoing fusions with pelvic fixation, yielding downstream pain, pseudoarthrosis, and loss of deformity correction. Studies have found failure rates ranging from 23.74-34.3%, with risk factors including fixation type (traditional iliac vs. S2-iliac (S2AI)), and number of fused levels. Sacroiliac joint fusions (SIJF) may demonstrate promise as a salvage procedure for LFF. As spine surgery has shifted towards minimally invasive approaches, robotic navigation has previously been explored as a feasible method for primary SIJF. In this study, we aim to establish the viability of robot-navigated SIJF as a salvage surgery for LFF.

Methods: Case logs of a single surgeon were reviewed and patients undergoing robot-navigated revision SIJF for previous LFF were identified. Length of surgery, type of previous fixation/instrumentation, reason for revision, estimated blood loss, and patient-reported percent improvement in pain were collected.

Results: 5 patients were identified as having undergone robot-navigated SIJF for previous LFF. 4 LFF were from loosened S2AI screws and 1 was from dislodged S2AI set caps. Mean length of surgery was 44.4±9.4min and estimated blood loss was 7.0±5.6ml. At 1.5 months post-op 4 of 5 patients reported pain improvement of at least 50%. At 3 months post-op, 2 of 4 available patient reports showed at least 90% improvement, and at 6 months post-op both available patient reports showed at least 62.5% improvement. At most recent available follow-up across all patients, pain improvement was reported at an average of 83.4±18.5%, with all patients showing >50% improvement at some point post-op.

Conclusion : Robot-navigated SIJF offers a viable method for revision surgeries in instances of LFF. Further randomized controlled trials and investigations evaluating traditional versus robotic SIJF long-term fusion rates, outcomes, and complications are needed.