Wednesday, September 26, 2018 1:00 PM – 2:00 PM What's New in MIS: 38. Retrospective analysis of Sacroiliac Joint (SIJ) fusions comparing the percutaneous transgluteal approach to the posterior oblique approach

Abstract

BACKGROUND CONTEXT For many years, low back pain originating from the sacroiliac joint was either overlooked or misdiagnosed and therefore untreated. This is perhaps due to a number of factors. For example, spine surgeons were trained to look at the spine for sources of pain and not the sacroiliac joint. Additionally the diagnostic technique for identifying the sacroiliac joint as a pain generator were not refined. If the saroiliac joint was identified as the problem, orthopedic surgeons were reluctant to address the sacroiliac joint surgically due to its high morbidity rates. However, with a significant percentage of the patient population having the sacroiliac joint as the pain generator, it makes sense to try to alleviate this pain in a way that is as minimally invasive as possible. One such technique is a lateral transgluteal approach. Another technique for accessing the sacroiliac joint in a minimally invasive fashion is through the posterolateral approach. The author has experience with both approaches and device types. It was the author's intent to compare the two approaches to ascertain which achieved better outcomes. PURPOSE We want to compare the transgluteal approach with posterior oblique approach and look at the adverse events and complications related to these two different approaches. STUDY DESIGN/SETTING Retrospective analysis cohort of two groups of patients. One group underwent transgluteal approach with insertion of triangular SI bone implants and the other group underwent posterior oblique approach with insertion of cannulated Rialto screws packed with Grafton paste as a bone graft substitute. PATIENT SAMPLE Group A consisted of patients treated with a transgluteal approach receiving the SI- Bone iFuse Implant System. Group B consisted of patients treated posterolaterally with the Medtronic Rialto SI Fusion System. For the sake of this study, only patients receiving unilateral implants were enrolled. Only patients with a diagnosis of sacroilitis or SIJ disruption were enrolled. Patients with other SIJ pathologies were excluded. Revision SIJ fusions were likewise excluded. The following date was collected from 20 to 30 patients in both groups. OUTCOME MEASURES Data collected consisted of Pre-op VAS, Post-op VAS, Revision Rate, Complication Rate, Blood Loss and Surgical Time. METHODS Refer to Patient Sample and Outcome Measures section. RESULTS Eighty percent of patients receiving the transgluteal approach showed an improvement in VAS scores, with 45% showing significant VAS improvement. A total of 96.7% of patients receiving the posterolateral approach showed improvement in VAS scores with 65% showing significant improvement. The transgluteal group had a 20% adverse event rate versus 6.7% for the posterolateral group. Lastly, the average blood loss for the posterolateral group was 33cc versus 60cc for the transgluteal group. CONCLUSIONS The posterolateral approach appears to be the superior approach. It is the author's belief that the increased bleeding associated with the transgluteal approach increases the potential for a postoperative hematoma, thereby yielding the higher adverse event rate. It is the author's opinion that the higher rate of patients in the posterolateral group reporting significant VAS improvement is due to the lack of disruption of the gluteal muscles associated with the trajectory. Bypassing these muscles altogether enables the patient to return to weight-bearing sooner, subsequently ambulating sooner and ultimately return to normal activities sooner. One of the adverse events in the transgluteal approach was the result of the nerve insult due to a malpositioned implant. While potentially the result of implantation technique, impacted vs. screwed, it is important to note that the trajectory of the lateral transgluteal approach does place the sacral nerve roots at risk. It was beyond the scope of this study to look at the impact of the individual implant design differences and placement techniques on clinical outcomes. Rialto (Approved for this indication), Grafton Bone Paste (Investigational/Not approved) FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.