Minimally invasive sacroiliac joint fusion surgery for chronic sacroiliac pain

Evidence-based recommendations on minimally invasive sacroiliac joint fusion surgery for chronic sacroiliac pain in adults. This involves fixing the sacrum to the ilium using 2 or 3 metal implants.

# Recommendations
Current evidence on the safety and efficacy of minimally invasive sacroiliac (SI) joint fusion surgery for chronic SI pain is adequate to support the use of this procedure provided that standard arrangements are in place for clinical governance, consent and audit. Find out what standard arrangements mean on the NICE interventional procedures guidance page.
Patients having this procedure should have a confirmed diagnosis of unilateral or bilateral SI joint dysfunction due to degenerative sacroiliitis or SI joint disruption.
This technically challenging procedure should only be done by surgeons who regularly use image-guided surgery for implant placement. The surgeons should also have had specific training and expertise in minimally invasive SI joint fusion surgery for chronic SI pain.# Indications and current treatments
Chronic pain in the lower back triggered from the sacroiliac (SI) joint occurs in 15% to 30% of patients with low back pain. The causes of SI joint pain include degenerative sacroiliitis, osteoarthritis, SI joint disruptions from trauma or pregnancy, problems after lumbar spinal fixation techniques, anatomical abnormalities such as scoliosis, infection, gout, tumour or idiopathic causes.
Conservative treatments for SI joint pain include analgesics, non-steroidal anti-inflammatory drugs, physiotherapy, manipulative therapy, intra-articular SI joint corticosteroid injections, periarticular injections, botulinum toxin injections and radiofrequency denervation. Surgical treatment is considered for persistent chronic symptoms that are unresponsive to conservative treatment. Surgical techniques include open SI joint fusion surgery or minimally invasive SI joint fusion using percutaneous implants to stabilise the joint and treat joint pain.# The procedure
Minimally invasive surgical fusion of the sacroiliac (SI) joint is done with the patient under general or spinal anaesthesia and in a prone position. Fluoroscopic guidance is used. Using a lateral transarticular approach, the SI joint is accessed laterally through a small incision made in the buttock to reach the ilium. A pin is passed through the ilium across the SI joint into the centre of the sacrum, avoiding the neural foramen. A drill is then used to create a pathway through the ilium to the sacrum. An implant is inserted (with the lateral portion of the implant sitting in the ilium and the medial end in the sacrum), spanning the SI joint. Typically, 3 implants are used.
Treatment of both SI joints can be done at the same time, or in staged procedures. After surgery, patients are advised to make a gradual return to full weight bearing over several weeks, using a walker for assistance, and then have physiotherapy.# Efficacy
This section describes efficacy outcomes from the published literature that the committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedures overview.
In a randomised controlled trial (RCT) of 148 patients with sacroiliac (SI) joint dysfunction comparing minimally invasive SI joint fusion (n=102) with non-surgical management (NSM, n=46), success rates at 6 months were higher in the minimally invasive SI joint fusion group (81%  versus 26% ; Bayesian posterior probability of superiority >0.9999). (Success was defined as a composite of pain reduction from baseline visual analogue scale  pain score by at least 20 mm, absence of device-related serious adverse events or neurological worsening, and absence of surgical re-intervention.) In a prospective case series of 172 patients, intention-to-treat success rate was 80% (119/149) at 24 months (Bayesian posterior probability of superiority >0.9999).
In a systematic review of SI joint fusion in 430 patients, in those who had minimally invasive SI joint fusion (n=299), radiographically confirmed fusion rates (determined by CT or plain radiograph) were 13% to 100% (in 4 out of 9 studies) at a mean follow-up of 21 months. In the prospective case series of 172 patients, CT scan at 1year follow-up showed 97% bone adherence to at least 2 implants on both the iliac and sacral sides, with moderate rates of bone growth across the SI joint.
In the RCT of 148 patients, in the SI joint fusion group (n=102), mean joint pain (measured using a 0100 VAS) improved from 82.3 at baseline to 30.4 at 6month follow-up (p<0.001), 28.3 at 12month follow-up (p<0.001) and 26.7 at the 24month follow-up (p<0.001). In the NSM group, mean SI joint pain improved from 82.2 at baseline to 70.3 at 6 months (p=0.001). Similarly, in the SI joint fusion group, mean Oswestry Disability Index (ODI) decreased from 57.2 at baseline to 29.9 at 6 months (p<0.001), 28.1 at 12 months (p<0.001) and 28.7 at 24 months (p<0.001). In the NSM group, mean ODI decreased from 56.0 at baseline to 51.6 at 6 months (p=0.06). There were clinically important improvements from baseline (VAS more than 20.0 points; ODI more than 15.0 points) and sustained clinical benefit (VAS more than 25.0 or less than 35.0 points; ODI more than 18.8 points) in the SI joint fusion group compared with patients in the NSM group.
In a systematic review and meta-analysis of 432 patients on minimally invasive SI joint fusion using a lateral transarticular approach, the random effects meta-analysis (RMA) mean pain score decreased from a baseline of 8.1 (95% confidence interval  7.8 to 8.4) to 2.8 (95% CI 2.4 to 3.2) at 6 months, 2.7 (95% CI 2.1 to 3.3) at 12 months and 2.0 (95% CI 1.4 to 2.5) at 24 months. ODI decreased from an RMA mean score of 56.6 (95% CI 51.0 to 61.5) at baseline, 30.3 (95% CI 22.5 to 38.0) at 6 months and 25.1 (95% CI 12.3 to 37.9) at 12 months.
In an RCT of 103 patients, SI joint function ratings (measured using the active straight leg raise test on a scale of 0 to 6) decreased statistically significantly more (p<0.0001) in the SI joint fusion group (from 4.0 to 2.0) than in the conservative management group (from 3.8 to 3.7). The proportion of patients who could raise the leg with no difficulty at 6 months was 71% in the SI joint fusion group and 32% in conservative management group (p=0.0002).
In the systematic review and meta-analysis of 432 patients, improvements in quality of life (measured on the SF36 physical component score ) were consistent in 2 studies of triangular implants; scores increased from 30.2 and 30.7 at baseline to 42.8 and 37.0 at 6 months respectively. In the RCT of 148 patients, in the SI joint fusion group (n=102), quality of life (measured with an EQ5D time tradeoff index utility of current health) improved from 0.44 at baseline to 0.72 at 6month follow-up (p<0.001), 0.74 at 12month follow-up (p<0.001) and 0.72 at the 24month follow-up (p<0.001). The mean change was only 0.05 points in the NSM group at 6 months (p=0.17). For patients who crossed over (n=35), the change was small at 6 months (0.02; p=0.66) but, after crossover, improved from 0.47 at 6 months to 0.73 at 12 months (0.26 point increase, p<0.001). In those who did not cross over (n=11), the change from 6 months to 12 months was small (p=0.008). Quality of life (measured using SF36) showed that mean 6month changes in PCS and mental health component summary scores (MCS) were statistically significant (p<0.001) in the fusion group compared with the NSM group. Patients who crossed over from NSM after 6 months had larger improvements in PCS and MCS scores compared with those who did not cross over.
In the systematic review of SI joint fusion of 430 patients, clinical and patient satisfaction with surgery (determined by subjective questionnaires and judged by patients' stated satisfaction with surgery) ranged from 56% to 100% in 299 patients (from 9 studies) who had minimally invasive SI joint fusion, at a mean follow-up of 21 months. In the RCT of 103 patients, satisfaction levels were higher at 3 and 6 months in the SI joint fusion group compared with the conservative management group (p<0.0001 by proportional odds logistic regression). The proportion of patients reporting that they would have the procedure again was also higher in the SI joint fusion group (p=0.0001).
The specialist advisers listed key efficacy outcomes as improvement in pain and function, and reduced length of hospital stay.
Eight commentaries from patients who had experience of this procedure were received, which were discussed by the committee.# Safety
This section describes safety outcomes from the published literature that the committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedures overview.
The overall complication rate was 4% (204/5,319) in a prospective database analysis of post-marketing complaints for patients having minimally invasive sacroiliac (SI) joint fusion for degenerative sacroiliitis and SI joint disruption. Pain was the most commonly reported event (2% ), followed by nerve impingement in less than 1% (n=48) and recurrent SI joint pain in less than 1% (n=43).
The overall complication rate was 13% (57/432) in a systematic review and meta-analysis of 432 patients from 12 cohort studies on minimally invasive SI joint fusion using a lateral transarticular approach. The most common events were surgical wound problems (4%, 17/432), trochanteric bursitis (2%, 8/432), facet pain (less than 1%, 3/432), recurrent SI pain (less than 1%, 3/432), toe and foot numbness (less than 1%, 2/432), and nerve root impingement needing revision in 2% (9/432) patients. In a systematic review on SI joint fusion including 430 patients, for those having minimally invasive SI joint fusion (n=299 in 9 studies), complications reported were new-onset facet joint pain, trochanteric bursitis, deep wound infections, new onset of low back or buttock pain, worsening knee or leg pain, superficial cellulitis, radiculopathy, large haematomas, vascular necrosis of the hip, piriformis syndrome, implant penetration into the sacral neural foramen, peripheral neuropathy, a non-displaced fracture, pulmonary embolism and deep vein thrombosis.
The device-related adverse event rate was 1% (75/5,319) in the prospective database analysis of post-marketing complaints. These were related to issues with binding, bending or breakage of the Steinmann pin (n=43), pin advancement difficulties (n=14), radiographic halo (n=13) and device migration (n=4). In a randomised controlled trial (RCT) of 148 patients, device-related events were reported in 3% (3/102) in the SI joint fusion group at 6month follow-up. Two events (1 implant-related impingement on a sacral nerve causing pain and needing immediate revision and 1 hairline ilium fracture adjacent to implant causing pain resolved after revision surgery) were definitely related to the device and 1 event (SI joint pain because of suboptimal placement of implants, which needed revision surgery) was deemed probably related to the device.
The procedure-related adverse event rate was 2% (108/5,319) in the prospective database analysis of post-marketing complaints. Improper implant placement was reported in 1% (n=72) of patients. Improper device length was reported in less than 1% (n=36) of patients, with most implants deemed to be too short (n=30). In the RCT of 148 patients, 19% (19/102) of the events were probably or definitely related to the SI joint fusion and 11% (5/46) of the events were related to non-surgical management (NSM) at 6month follow-up. Events related to surgical procedure included neuropathic symptoms (n=1), postoperative medical problems (n=4; urinary retention, nausea/vomiting, atrial fibrillation), SI joint pain or trochanteric bursitis (n=7), surgical wound problems (n=5), iliac fracture (n=1) and asymptomatic physical examination findings (n=1). With NSM, 3 patients reported SI joint pain after treatment; 1 had flushing and shortness of breath after SI joint injection and 1 had worsening SI joint pain related to physiotherapy.
The revision rate was 2% (9/432) in the systematic review and meta-analysis of 432 patients. Reoperation rate ranged from 0% to 17% (mean 6%) in the 299 patients who had minimally invasive SI joint fusion surgery in the systematic review of 430 patients (in 9 studies; mean follow-up of 21 months). In the prospective database analysis of post-marketing complaints, the reoperation rate was 2% (n=96/5,319) at a median follow-up of 4 months. Revisions were typically done in the early postoperative period (median 19 days) for treatment of a symptomatic wrongly positioned implant (less than 1%, n=46), or to correct an improperly sized implant in an asymptomatic patient (less than 1%, n=10). Revisions in the late postoperative period were done (at a median of 297 days) to treat symptom recurrence (n=34) or for continued pain of undetermined aetiology (n=6). Revision outcomes and management in these patients were not reported.
Postoperative infection rate was 4% (n=19) at 6 months in a retrospective analysis of 469 patients treated by minimally invasive SI joint fusion.
In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers listed the following anecdotal adverse events: non-union and implant loosening, which would be similar to pseudoarthrosis. They considered that the following were theoretical adverse events: residual pain and injury to L5 or sacral nerve roots by wrong positioning of the screw (implant).
Eight commentaries from patients who had experience of this procedure were received, which were discussed by the committee.# Further information
For related NICE guidance, see the NICE website.
Patient commentaries supported use of the procedure. They were largely positive and many patients described having pain relief.

# Information for patients
NICE has produced information on this procedure for patients and carers (Information for the public). It explains the nature of the procedure and the guidance issued by NICE, and has been written with patient consent in mind.
ISBN: 978-1-4731-2414-1