Sacroiliac Joint Fusion Using Triangular Titanium Implants vs. Non-Surgical Management: Six-Month Outcomes from a Prospective Randomized Controlled Trial

Posterior allograft sacroiliac joint fusion with pre-operative mapping

Background

Low back pain is a highly prevalent and disabling condition. Sacroiliac joint dysfunction is prevalent in up to 62 % of some populations and is a common origin of low back pain. The posterior approach for minimally invasive sacroiliac joint fusion with an allograft is still relatively novel, with limited studies examining its safety and efficacy.

Objective

The objective of our study was to analyze changes in pain and opioid usage for patients who underwent this procedure with pre-operative mapping after exhausting conservative treatment methods.

Methods

This was a single-center, retrospective study with all cases completed by a single interventional pain physician. Outcomes regarding pain and opioid usage were extracted from electronic medical records, Georgia Prescription Drug Monitoring Program reports, and all other available state databases for 208 consecutive patients who underwent the minimally invasive sacroiliac joint fusion procedure with the LinQ Fusion Implant (PainTeq, Tampa, FL) after pre-operative mapping between August 2019 and October 2022. Pain was assessed using the Numerical Rating Scale (NRS), and opioid consumption was measured using Morphine Milligram Equivalents (MME).

Results

NRS scores decreased from 7.23 ± 1.82 at baseline to 1.16 ± 1.35 at the final available follow-up (p < 0.001). Pain improvements ranged from 40 to 100 %, and all patients reported at least some improvement post-intervention. 205 of the 208 patients reported an improvement in pain of at least 50 %. MME reduced from 20.74 ± 26.33 mg to 10.00 ± 18.69 mg (p < 0.001).

Conclusion

Posterior allograft sacroiliac joint fusion significantly reduces pain and opioid consumption. Pre-operative mapping is beneficial but requires more evidence to elucidate its role in optimizing implant placement.

Utility of minimally invasive percutaneous arthrodesis of the sacroiliac joint for the treatment of low back pain: systematic review of the literature

BACKGROUND

The surprising increase observed in recent years in the use of minimally invasive sacroiliac joint arthrodesis techniques as a treatment for low back pain justifies an objective review of this results.

PURPOSE

carry out a systematic review of the literature to evaluate the clinical results of patients with low back pain treated with percutaneous arthrodesis of the SIJ.

STUDY DESIGN

Systematic review.

METHODS

Systematic search of the medical literature. The words used in the Search were: "Hollow screw system", "percutaneous sacroiliac joint stabilization", "sacroiliac joint", "minimally invasive", "sacroiliac pain", "sacroiliac dysfunction". With logical connectors such as "and", "not" and "or".

DATABASES

Pubmed, Scopus, Embase, Ovid, EBSCO host and google scholar. The search extended from the beginning of the databases until September 2024. The "Rayyan" program was used to collect the information and facilitate the analysis process.

INCLUSION CRITERIA

Systematic review from the literature, clinical trials, observational studies and case series. They followed PRISMA principles.

RESULTS

661 articles were found, of which 108 articles were duplicates. The criteria (Inclusion/Exclusion) were applied to the 553 articles identified based on the independent reading of the summaries by each of the authors on the Rayyan platform and 434 articles were excluded. The 119 selected articles were completely reviewed to finally obtain 102 articles included in the review. Epidemiological data were extracted into an Excel table, methodological and related to clinical results and safety of procedures made. The Prisma checklist for systematic reviews was applied in each article. The epidemiological quality of the articles was evaluated based on the checklists STROBE and CONSORT. The results regarding clinical improvement were overwhelming. However, most of the studies were sponsored by industry and with a limited population and follow-up not always prolonged.

CONCLUSIONS

Although the clinical results regarding the effectiveness of SIJ fusion are forceful for their effectiveness, we recommend considering some aspects for their analysis and especially long-term studies.

Clinical outcome measures following lateral versus posterior sacroiliac joint fusion: Systematic review and meta-analysis

Introduction

Sacroiliac joint fusion (SIJF) is indicated in patients with chronic Sacroiliac joint (SIJ) pain or instability and is usually performed using minimally invasive techniques through lateral or posterior approach.

Research question

Our study aims to compare the lateral approach to the posterior one in SIJF through meta-analysis of other studies. The outcome of each approach is measured using the visual analog scale (VAS), Oswestry disability index (ODI), or both.

Materials and methods

The study was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Articles were extracted using Pubmed advance search till February 27th, 2023. Articles included were those limited to either lateral, posterior or both approaches. Articles written in a non-English language, case reports and smaller-than-three case series were excluded from the study. Risk of bias was assessed using the Newcastle-Ottawa and Jadad scales. Stata-17 software program was used for statistical analysis and creation of forest plots.

Results

Forty-eight articles were available for the quantitative analysis, which represents a total of 2562 subjects. The average duration of postoperative follow-up was 21 months (3-72 months) and 17 months (6-72 months) for the VAS and ODI outcomes, respectively. The average percentage of improvement in the VAS was 57% (22-80%) in the lateral approach versus 58% (29-94%) in the posterior approach (p = 0.986). The average percentage of improvement in the ODI was 42% (11-75%) in the lateral approach versus 31% (11-65%) in the posterior one (p = 0.272). A trend towards performing posterior approaches more frequently was noted in studies published after 2017.

Discussion and conclusion

Approach selection for SIJF depends mainly on patient's characteristics and surgeon's experience. Our study demonstrated no difference in VAS outcome between lateral and posterior approach. Lateral approach appeared to be superior in ODI outcome although not statistically significant. The main limitation of the study is the selection-bias as the majority of articles included were observational. Therefore, randomized procedural trials are needed to validate these findings.

Efficacy of Lateral Sacroiliac Joint Fusion With the Trident™ Screw System: A Retrospective Analysis

Background Chronic lower back pain is a significant global health issue, leading to disability and a substantial economic burden. A considerable number of cases are associated with the sacroiliac joint (SIJ), especially among patients with a history of lumbar fusions. Despite various treatments, persistent SIJ pain often requires surgical intervention, with minimally invasive techniques becoming the standard due to their benefits over open surgery. This study examines the clinical outcomes of a novel minimally invasive SIJ fixation technique using the Trident™ system. Methodology The study retrospectively reviewed 39 patients who underwent SIJ fusion with the Trident™ system across four surgical sites by a single surgeon. Strict inclusion and exclusion criteria ensured a homogeneous patient population. The procedure involved placing hollow fenestrated screws in a tri-pronged fashion across the SIJ to achieve fusion. The Oswestry Disability Index (ODI) was used to measure functional outcomes, and statistical analyses were conducted to assess the efficacy of the procedure. Results The study found statistically significant improvements in most ODI categories postoperatively. Subgroup analyses revealed that patients with bilateral SIJ fusions showed the greatest improvement, while those with unilateral fusions without prior lumbar surgery showed the least improvement, though still significant. The results suggest that the Trident™ system is effective in improving patient outcomes. Conclusions Evidence indicates that the novel SIJ fixation technique could influence future standards of care for SIJ-related chronic low back pain. The Trident™ Screw System's minimally invasive approach to SIJ fusion is effective in improving functional outcomes for patients with chronic SIJ-related lower back pain. The technique's efficacy, demonstrated through significant ODI improvements, supports its potential as a valuable treatment option.

The percentage of sacroiliac fusions done in the U.S. by non-surgical specialties has increased

Background

Surgical fusion of the sacroiliac (SI) joint is often performed to manage chronic lower back or buttock pain. When Current Procedural Terminology (CPT) codes were introduced, SI joint fusion procedures were done primarily by orthopaedic surgeons and neurosurgeons. The purpose of this study was to examine the utilization of SI joint fusion CPT codes by physician specialty over time.

Methods

A retrospective cohort study was conducted using the PearlDiver database. The database was queried using CPT codes to identify patients who underwent SI joint fusion via percutaneous, open, or trauma codes. Specialties queried included surgical specialties (orthopaedic surgery and neurosurgery) and non-surgical specialties [physical medicine and rehabilitation (PM&R), neurology, anesthesiology, pain medicine]. Total number and number per year of SI joint fusion procedures were identified for each specialty group. Trends of SI fusion billing for the years 2015 to 2021 were compared between surgical specialties and non-surgical specialties.

Results

Comparing 2015 and 2021, the SI fusion codes submitted across all three groups (percutaneous, open, and trauma) increased for non-surgical specialties compared to surgical specialties. Between 2015 and 2021, the total number of percutaneous procedures submitted by all specialties increased by 294%, while the number of procedures being submitted by non-surgical specialties increased by 25,050%.

Conclusions

Our study demonstrated how quickly and to what degree the procedure market can react to higher work relative value unit (RVU) value codes. Despite requiring less overall time and utilizing an intra-articular rather than a transfixing approach, non-surgical specialties submitted the same CPT code as surgical specialties performing the transfixing procedure at an increasing rate during the study period. With the introduction of new technologies to perform SI fixation and a new code to capture the intra-articular procedure, future studies could examine whether the number of SI fusion procedures performed by the various physician specialties stabilizes over time.

Sacroiliac joint pain: what treatment and when

INTRODUCTION

Spinal and non-spinal pathologies can cause low back pain. Non-spinal sources of low back pain include the sacroiliac joint (SIJ) and the hip. SIJ pain can be treated either conservatively or surgically. Current strategies for managing sacroiliac joint pain are debated, and limited evidence exists.

AREAS COVERED

The present expert opinion updates current evidence on conservative and surgical modalities for SIJ pain.

EXPERT OPINION

Surgical management for SIJ pain is effective. However, it exposes patients to surgery and, therefore, related complications. Conservative management may be implemented in patients with moderate SIJ pain, with less than six months of symptoms, or not eligible for surgery. Several noninvasive modalities are available, mostly centered on intra-articular injections. Corticosteroids, platelet-rich plasma, and stem cells have only midterm lasting effects, at most for nine months. Radiofrequency ablation is another methodology for pain relief. Both continuous and pulsatile radiofrequency ablation are associated with good outcomes. SIJ fusion can be performed using different techniques; however, a clear recommendation on the most appropriate modality for the management of SIJ pain is still debated.

Catamaran SI Joint Fusion System(R) MAINSAILTM Study: a prospective, single-arm, multi-center, post-market study of six-month clinical outcomes and twelve-month radiographic findings

BACKGROUND

Minimally invasive surgical techniques for sacroiliac joint (SIJ) fixation have the potential to reduce risk and improve patient outcomes, but evidence remains limited. This interim analysis presents initial findings from an ongoing prospective study evaluating the safety and efficacy of the Catamaran System.

METHODS

The primary endpoint of success at 6 months was defined as a ≥20 mm improvement in SIJ pain (Visual Analog Scale, VAS), no neurologic worsening, absence of device-related serious adverse events (SAEs), and no surgical reintervention. Secondary endpoints included 6 month evaluation of the Oswestry Disability Index (ODI), patient satisfaction, and 12 month radiographic CT fusion, performed by an indpendent radiologist.

RESULTS

Thirty-three consecutive patients (mean age: 58.9 years; %-females: 76%; Body Mass Index: 30.5) were treated across six U.S. clinical sites. At the primary endpoint of 6 months, 80% of patients met the criteria for success, with no device-related SAEs and no surgical reintervention reported. VASSIJ-Pain significantly decreased from preoperative levels (mean: 80.9 mm) to 6 months postoperatively (31.1 mm; p < 0.001). Mean ODI scores also showed a significant improvement from preoperative values (51.9%) to 6 months postoperatively (29.6%, p < 0.01). Patients reported high satisfaction rates throughout all follow-ups, with 93.3% of patients being satisfied at 6 months.

CONCLUSION

In patients diagnosed with chronic SIJ pain, minimally invasive inferior-posterior delivery of the Catamaran implant was safe and effective in relieving pain and reducing disability.

Patient-reported outcomes after minimally invasive sacro-iliac joint surgery: a cohort study based on the Swedish Spine Registry

BACKGROUND AND PURPOSE

There is conflicting evidence regarding treatment outcomes after minimally invasive sacroiliac joint fusion for long-lasting severe sacroiliac joint pain. The primary aim of our cohort study was to investigate change in patient-reported outcome measures (PROMs) after minimally invasive sacroiliac joint surgery in daily practice in the Swedish Spine Registry. Secondary aims were to explore the proportion of patients reaching a patient acceptable symptom score (PASS) and the minimal clinically important difference (MCID) for pain scores, physical function, and health-related quality of life outcomes; furthermore, to evaluate self-reported satisfaction, walking distance, and changes in proportions of patients on full sick leave/disability leave and report complications and reoperations.

METHODS

Data from the Swedish Spine Registry was collected for patients with first-time sacroiliac joint fusion, aged 21 to 70 years, with PROMs available preoperatively, at 1 or 2 years after last surgery. PROMs included Oswestry Disability Index (ODI), Numeric Rating Scale (NRS) for low back pain (LBP) and leg pain, and EQ-VAS, in addition to demographic variables. We calculated mean change from pre- to postoperative and the proportion of patients achieving MCID and PASS.

RESULTS

68 patients had available pre- and postoperative data, with a mean age of 45 years (range 25-70) and 59 (87%) were female. At follow-up the mean reduction was 2.3 NRS points (95% confidence interval [CI] 1.6-2.9; P < 0.001) for LBP and 14.8 points (CI 10.6-18.9; P < 0.001) for ODI. EQ-VAS improved by 22 points (CI 15.4-30.3, P < 0.001) at follow-up. Approximately half of the patients achieved MCID and PASS for pain (MCID NRS LBP: 38/65 [59%] and PASS NRS LBP: 32/66 [49%]) and physical function (MCID ODI: 27/67 [40%] and PASS ODI: 24/67 [36%]). The odds for increasing the patient's walking distance to over 1 km at follow-up were 3.5 (CI 1.8-7.0; P < 0.0001), and of getting off full sick leave or full disability leave was 0.57 (CI 0.4-0.8; P = 0.001). In the first 3 months after surgery 3 complications were reported, and in the follow-up period 2 reoperations.

CONCLUSION

We found moderate treatment outcomes after minimally invasive sacroiliac joint fusion when applied in daily practice with moderate pain relief and small improvements in physical function.

5. Sacroiliac joint pain

INTRODUCTION

Sacroiliac (SI) joint pain is defined as pain localized in the anatomical region of the SI joint. The reported prevalence of SI joint pain among patients with mechanical low back pain varies between 15% and 30%.

METHODS

In this narrative review, the literature on the diagnosis and treatment of SI joint pain was updated and summarized.

RESULTS

Patient's history provides clues on the source of pain. The specificity and sensitivity of provocative maneuvers are relatively high when three or more tests are positive, though recent studies have questioned the predictive value of single or even batteries of provocative tests. Medical imaging is indicated only to rule out red flags for potentially serious conditions. The diagnostic value of SI joint infiltration with local anesthetic remains controversial due to the potential for false-positive and false-negative results. Treatment of SI joint pain ideally consists of a multidisciplinary approach that includes conservative measures as first-line therapies (eg, pharmacological treatment, cognitive-behavioral therapy, manual medicine, exercise therapy and rehabilitation treatment, and if necessary, psychological support). Intra- and extra-articular corticosteroid injections have been documented to produce pain relief for over 3 months in some people. Radiofrequency ablation (RFA) of the L5 dorsal ramus and S1-3 (or 4) lateral branches has been shown to be efficacious in numerous studies, with extensive lesioning strategies (eg, cooled RFA) demonstrating the strongest evidence. The reported rate of complications for SI joint treatments is low.

CONCLUSIONS

SI joint pain should ideally be managed in a multidisciplinary and multimodal manner. When conservative treatment fails, corticosteroid injections and radiofrequency treatment can be considered.

Safety, Efficacy, and Durability of Outcomes: Results from SECURE: A Single Arm, Multicenter, Prospective, Clinical Study on a Minimally Invasive Posterior Sacroiliac Fusion Allograft Implant

Introduction

Research suggests that sacroiliac joint (SIJ) dysfunction is responsible for 15% to 30% of reported low back pain cases. Recently, there has been an increasing interest in SIJ fusion using minimally invasive surgery (MIS) due to safety. Initially, devices designed for MIS were intended for lateral approaches. A minimally invasive sacroiliac fusion implant for use with a posterior approach has been developed and is regulated for clinical use under the regulatory framework required for human cells, tissues, or cellular or tissue-based products (HCT/Ps).

Methods

A multi-center, prospective, single-arm study was launched after initial studies provided preliminary data to support safety, efficacy, and durability of this minimally invasive sacroiliac posterior fusion LinQ allograft implant (NCT04423120). Preliminary results were reported previously. Final results for the full participant cohort are presented here.

Results

One-hundred and fifty-nine (159) participants were enrolled across 16 investigational sites in the US between January 2020 and March 2022. One-hundred and twenty-two (122) participants were implanted. At the 1-month follow-up, 82 participants satisfied all criteria for the composite responder endpoint, representing 73.2% of the study cohort. These results stayed consistent across the remaining study timepoints with 66.0%, 74.4%, and 73.5% of participants classified as responders at the 3-, 6- and 12-month follow-up visits, respectively. VAS scores were significantly reduced (p < 0.0001) and ODI scores were significantly improved (p < 0.0001). All domains of the PROMIS-29 were also significantly improved (all p's <0.0001). Only one procedure-related serious AE was reported in the study.

Conclusion

These results suggest that the posterior approach LinQ Implant System is a safe and effective treatment for sacroiliac joint dysfunction at 12 months, with results that are favorable compared to outcomes reported for an FDA-cleared lateral approach.

The effect of minimally invasive sacroiliac joint fusion compared to sham operation: a double-blind randomized placebo-controlled trial

Background

Minimally invasive fusion of the sacroiliac joint as treatment for low back pain may reduce pain and improve function compared to non-operative treatment, although clear evidence is lacking. The aim of this trial was to evaluate the effect of minimally invasive sacroiliac joint fusion compared to sham surgery on sacroiliac joint pain reduction.

Methods

In this double-blind randomized sham surgery-controlled trial patients with clinical diagnosis of sacroiliac joint pain confirmed with sacroiliac joint injection were included at two university hospitals in Sweden and Norway. Patients were randomized by the operating surgeon at each site to minimally invasive sacroiliac joint fusion or sham surgery. The primary endpoint was group difference in sacroiliac joint pain on the operated side at six months postoperatively, measured by the Numeric Rating Scale (0-10). Un-blinding and primary analysis were performed when all patients had completed six months follow-up. The trial is closed for new participants and was registered at clinicaltrials.gov: NCT03507049.

Findings

Between September 1st, 2018 and October 22nd, 2021, 63 patients were randomized, 32 to the surgical group, 31 to the sham group. Mean age was 45 years (range 26-63) and 59 of 63 (94%) patients were female. The mean reduction in the operated sacroiliac joint from baseline to six months postoperative was 2.6 Numeric Rating Scale points in the surgical group and 1.7 points in the sham group (mean between groups difference -1.0 points; 95% CI, -2.2 to 0.3; p = 0.13).

Interpretation

This double-blind randomized controlled trial could not prove that minimally invasive fusion of the sacroiliac joint was superior to sham surgery at six months postoperative.

Funding

Sophies Minde Ortopedi supported a clinical research position for Engelke Marie Randers. Region Stockholm supported the cost for the Swedish ethical application and a clinical research appointment for Paul Gerdhem.

Treatment of an Impending Pathologic Sacral Fracture with a Novel Iliosacral Fusion Construct: A Case Report

CASE

A 49-year-old woman presented with left leg radiculopathy and posterior pelvic pain. Subsequent evaluation demonstrated metastatic multiple myeloma with an impending left S1 sacral fracture. Immediate posterior pelvic ring stabilization was recommended to prevent fracture and disruption of her oncologic recovery. This was performed percutaneously with computer-assisted navigation using a novel cannulated screw design.

CONCLUSION

The patient was treated with prophylactic percutaneous posterior pelvic ring fixation with a novel cannulated screw design that provided a durable construct for immediate weight-bearing. The fixation prevented a pathologic fracture and allowed immediate return to activity.

Minimally invasive sacroiliac joint fusion using triangular titanium implants versus nonsurgical management for sacroiliac joint dysfunction: a systematic review and meta-analysis

BACKGROUND

Minimally invasive sacroiliac joint (MISIJ) fusion is a surgical option to relieve SIJ pain. The aim of this systematic review and meta-analysis was to compare MISIJ fusion with triangular titanium implants (TTI) to nonoperative management of SIJ dysfunction.

METHODS

We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials. We included prospective clinical trials that compared MISIJ fusion to nonoperative management in individuals with chronic low back pain attributed to SIJ dysfunction. We evaluated pain on visual analogue scale, Oswestry Disability Index (ODI) score, health-related quality of life (HRQoL) using the 36-Item Short Form Health Survey (SF-36) physical component (PCS) and mental component summary (MCS) scores, patient satisfaction, and adverse events.

RESULTS

A total of 8 articles representing 3 trials that enrolled 423 participants were deemed eligible. There was a significant reduction in pain score with MISIJ fusion compared with nonoperative management (standardized mean difference [SMD] -1.71, 95% confidence interval [CI] -2.03 to -1.39). Similarly, ODI scores (SMD -1.03, 95% CI -1.24 to -0.81), SF-36 PCS scores (SMD 1.01, 95% CI 0.83 to 1.19), SF-36 MCS scores (SMD 0.72, 95% CI 0.54 to 0.9), and patient satisfaction (odds ratio 6.87, 95% CI 3.73 to 12.64) were significantly improved with MISIJ fusion. No significant difference was found between the 2 groups with respect to adverse events (SMD -0.03, 95% CI -0.28 to 0.23).

CONCLUSION

Our analysis showed that MISIJ fusion with TTI shows a clinically important and statistically significant improvement in pain, disability score, HRQoL, and patient satisfaction with a similar adverse event profile to nonoperative management in patients with chronic low back pain attributed to SIJ dysfunction.

Biomechanics of sacroiliac joint fixation using lag screws: a cadaveric study

BACKGROUND

Iliosacral screw placement is ubiquitous and now part of the surgeon's pelvic trauma armamentarium. More recent evidence supports sacroiliac arthrodesis for treating sacroiliac joint (SIJ) dysfunction in select patients. Regardless of the surgical indication, there are currently no studies examining lag screw compression biomechanics across the SIJ. The objective of this biomechanical investigation was to quantify iliosacral implant compressive loads and to examine the insertion torque and compressive load profile over time.

METHODS

Eight human cadaveric pelvic specimens underwent SIJ fixation at S1 and S2 using 11.5 and 10.0 mm iFuse-TORQ Lag implants, respectively, and standard 7.3 mm trauma lag screws. Load decay analysis was performed, and insertion and removal torques were measured.

RESULTS

For both implants at S1 and S2 levels, the load relaxed 50% in approximately 67 min. Compressive load decay was approximately 70% on average occurring approximately 15 h post-insertion. Average insertion torque for the 11.5 mm TORQ implant at S1 was significantly greater than the trauma lag screw. Similarly, at S2, insertion torque of the 10.0 mm TORQ implant was greater than the trauma lag screw. At S1, removal torque for the 11.5 mm TORQ implant was higher than the trauma lag screw; there was no significant difference in the removal torque at S2.

CONCLUSIONS

In this study, we found that a novel posterior pelvic implant with a larger diameter, roughened surface, and dual pitch threads achieved improved insertion and removal torques compared to a standard screw. Load relaxation characteristics were similar between all implants.

Comparative Efficacy of Clinical Interventions for Sacroiliac Joint Pain: Systematic Review and Network Meta-analysis With Preliminary Design of Treatment Algorithm

OBJECTIVE

We aimed to identify the most effective clinical treatment method for sacroiliac joint (SIJ)-related pain based on the systematic review and network meta-analysis (NMA) to evaluate the comparative efficacy of clinical interventions for sacroiliac joint pain by pooling the randomized controlled trials (RCTs).

METHODS

Our team conducted a systematic review and NMA of RCTs to determine the most effective clinical treatment for SIJ-related pain. We searched the PubMed (MEDLINE), Web of Science, Cochrane Library, and Scopus databases for RCTs until February 2023. The PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines were followed. Pairwise and network meta-analyses were conducted using a random effects model.

RESULTS

Based on the search strategy and inclusion criteria, our systematic review and NMA included 9 randomized studies with 652 participants. Research has mainly focused on various radiofrequency sources, but their number is still low. In the network analysis, according to the NMA and mean ranking probabilities for the improvement of pain intensity (PI) and quality of life (QoL), sacroiliac joint fusion and cooled radiofrequency were associated with high treatment rank for improving PI and QoL in patients with sacroiliac joint pain.

CONCLUSION

This NMA suggest that SIJ fusion and cooled radiofrequency could be potential options for improving the QoL and relieving pain in patients with SIJ-related pain. Comparison studies of outcomes between these 2 procedures with solid methodology and a low risk of bias would be very beneficial to identify the optimal treatment option for this challenging disease.

Posterior intra-articular fixation stabilizes both primary and secondary sacroiliac joints: a cadaveric study and comparison to lateral trans-articular fixation literature

BACKGROUND

Posterior and lateral techniques have been described as approaches to sacroiliac joint arthrodesis. The purpose of this study was to compare the stabilizing effects of a novel posterior stabilization implant and technique to a previously published lateral approach in a cadaveric multidirectional bending model. We hypothesized that both approaches would have an equivalent stabilizing effect in flexion-extension and that the posterior approach would exhibit better performance in lateral bending and axial rotation. We further hypothesized that unilateral and bilateral posterior fixation would stabilize both the primary and secondary joints.

METHODS

Ranges of motion (RoMs) of six cadaveric sacroiliac joints were evaluated by an optical tracking system, in a multidirectional flexibility pure moment model, between ± 7.5 N-m applied moment in flexion-extension, lateral bending, and axial rotation under intact, unilateral fixation, and bilateral fixation conditions.

RESULTS

Intact RoMs were equivalent between both samples. For the posterior intra-articular technique, unilateral fixation reduced the RoMs of both primary and secondary joints in all loading planes (flexion-extension RoM by 45%, lateral bending RoM by 47%, and axial RoM by 33%), and bilateral fixation maintained this stabilizing effect in both joints (flexion-extension at 48%, lateral bending at 53%, and axial rotation at 42%). For the lateral trans-articular technique, only bilateral fixation reduced mean RoM of both primary and secondary sacroiliac joints, and only under flexion-extension loads (60%).

CONCLUSION

During flexion-extension, the posterior approach is equivalent to the lateral approach, while producing superior stabilization during lateral bend and axial rotation.

The efficacy of primary sacroiliac joint fusion for low back pain caused by sacroiliac joint pathology: a systematic review and meta-analysis

PURPOSE

Conduct a systematic review to quantify the effect of primary sacroiliac joint fusion (SIJF) for the treatment of sacroiliac (SI) joint pathology on patient reported outcomes.

METHODS

Medline, Embase, Cochrane, PubMed, and Scopus databases were searched prior to August 18th, 2020 for all English-Language studies involving the treatment of SIJ pathology through SIJF and/or conservative management (CM). The quality of included studies was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). Primary outcome measure was the Visual Analogue Scale (VAS) for low back pain. Secondary outcome measure was the Oswestry Disability Index (ODI) and the incidence of adverse reactions.

RESULTS

A total of 564 patients and six studies were included. The overall quality of evidence analyzed by this review was low (GRADE = 0). Five out of the six studies were industry funded. The VAS standardized mean difference (SMD) between SIJF and CM at three months and six months follow-up was - 1.4 [95% confidence interval - 2.3, - 0.6] and - 1.5 [95% CI - 1.8, - 1.1]. The ODI SMD between SIJF and CM scores at three months and 6 months follow-up was - 0.9 [95% CI - 1.1, - 0.7] and - 1.1 [95% CI - 1.6, - 0.5]. The odds ratio of adverse reactions due to SIJF compared to CM was 1.9 [95% CI 0.1, 42.8].

CONCLUSION

Based on the limited number of independent trials with long-term follow-up, SIJF shows potential as a surgical treatment option for SIJ pathology.

PROSPERO REGISTRATION

CRD42020206149 (25th September 2020).

Minimally invasive sacroiliac joint fusion for chronic sacroiliac joint pain: a systematic review

BACKGROUND CONTEXT

Sacroiliac (SI) joint pain causes significant disability and impairment to quality of life (QOL). Minimally invasive SI joint fusion is increasingly used to relieve chronic SI joint pain among patients who do not respond to nonsurgical treatment.

PURPOSE

To systematically review the existing literature to assess the effectiveness and safety of minimally invasive SI joint fusion.

STUDY DESIGN/SETTING

Systematic review.

DATA SOURCES

PubMed, Embase, Cochrane, and a clinical trial registry from database inception to June 30, 2021.

STUDY SELECTION

Eligible studies were primary research studies published in the English language, enrolled adults with SI joint pain, and compared SI joint fusion to nonsurgical interventions or alternative minimally invasive procedures. We included randomized controlled trials (RCTs) or controlled cohort studies (CCSs) that reported effectiveness (pain, physical function, QOL, opioid use) or safety outcomes (adverse events [AEs], revision surgeries) and uncontrolled studies that reported safety outcomes.

DATA ABSTRACTION AND SYNTHESIS

Data were abstracted into structured forms; two independent reviewers assessed risk of bias using standard instruments; certainty of evidence was rated using GRADE.

RESULTS

Forty studies (2 RCTs, 3 CCSs, and 35 uncontrolled studies) were included. Minimally invasive SI joint fusion with the iFuse Implant System appeared to result in larger improvements in pain (two RCTs: mean difference in visual analog scale -40.5 mm, 95% CI, -50.1 to -30.9; -38.1 mm, p<.0001) and larger improvements in physical function (mean difference in Oswestry Disability Index -25.4 points, 95% CI, -32.5 to -18.3; -19.8 points, p<.0001) compared to conservative management at 6 months. Improvements in pain and physical function for the RCTs appeared durable at 1- and 2-year follow-up. Findings were similar in one CCS. The two RCTs also found significant improvements in QOL at 6 months and 1 year. Opioid use may be improved at 6 months and 1 to 2 years. AEs appeared higher in the fusion group at 6 months. The incidence of revision surgery varied by study; the highest was 3.8% at 2 years. Two CCSs compared the effectiveness of alternative minimally invasive fusion procedures. One CCS compared iFuse to the Rialto SI Fusion System and reported no differences in pain, function, QOL, and revision surgeries from 6 months to 1 year. One CCS compared iFuse to percutaneous screw fixation and reported significantly fewer revisions among iFuse participants (mean difference -61.0%, 95% CI, -78.4% to -43.5%). The 35 uncontrolled studies had serious limitations and reported heterogeneous safety outcomes. Two of the larger studies reported a 13.2% incidence of complications from minimally invasive SI joint fusion at 90 days using an insurance claims database and a 3.1% incidence of revision surgery over 2.5 years using a postmarket surveillance database.

CONCLUSIONS

Among patients meeting diagnostic criteria for SI joint pain and who have not responded to conservative care, minimally invasive SI joint fusion is probably more effective than conservative management for reducing pain and opioid use and improving physical function and QOL. Fusion with iFuse and Rialto appear to have similar effectiveness. AEs appear to be higher for minimally invasive SI joint fusion than conservative management through 6 months. Based on evidence from uncontrolled studies, serious AEs from minimally invasive SI joint fusion may be higher in usual practice compared to what is reported in trials. The incidence of revision surgery is likely no higher than 3.8% at 2 years. Limited evidence is available that compares different minimally invasive devices.

Six Month Interim Outcomes from SECURE: A Single arm, Multicenter, Prospective, Clinical Study on a Novel Minimally Invasive Posterior Sacroiliac Fusion Device

INTRODUCTION

Sacroiliac joint disease is a prominent diagnosis across the world. A novel fixation technique employing a posterior approach, single point, bone allograft tranfixation has proven to be helpful anecdotally. The purpose of this is study is to investigate prospectively the safety and efficacy of this approach.

METHODS

A multicenter, prospective, single arm study was performed after patient identification and treatment with the novel posterior fusion, single-point transfixation system and followed for 24 months. Target enrollment is 100 patients. Interim results on the first 69 consecutive patients at 6 months is presented. Primary endpoint at 6-month analysis was Pain Intensity reduction by visual analogue scale and functional improvement by Oswestry Disability Index. Adverse events were assessed for safety analysis.

RESULTS

: 69 patients were identified for this analysis. At 6 months, a mean improvement of 34.9 was identified by a reduction in VAS and functional improvement was demonstrated by a mean reduction in ODI of 17.7. There were three adverse events, all unrelated to the device.

CONCLUSION

The posterior single point transfixation is safe and efficacious for the treatment of sacroiliac joint dysfunction with statistical improvements in pain and function.

Minimally Invasive Sacroiliac Joint Fusion vs Conservative Management in Patients With Sacroiliac Joint Dysfunction: A Systematic Review and Meta-Analysis

BACKGROUND

The sacroiliac joint (SIJ) is affected in 14% to 22% in individuals presenting with chronic low back or buttock pain. This percentage is even higher in patients who underwent lumbar fusion surgery: 32% to 42%. Currently, there is no standard treatment or surgical indication for SIJ dysfunction. When patients do not respond well to nonsurgical treatment, minimally invasive sacroiliac joint fusion (MISJF) seems to be a reasonable option. This systematic review and meta-analysis evaluates the current literature on the effectiveness of MISJF compared to conservative management in patients with SIJ dysfunction.

METHODS

A systematic search of health-care databases was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Inclusion criteria were randomized controlled trials (RCTs) or prospective and retrospective comparative cohort studies that compared MISJF with conservative management. Primary outcome measures were pain, disability, and patient satisfaction measured by patient-reported outcome measures. Secondary outcomes were adverse events (AEs), serious AEs, financial benefits, and costs.

RESULTS

Two RCTs and one retrospective cohort study were included comparing MISJF and conservative management with regard to pain and disability outcome, encompassing 388 patients (207 conservative and 181 surgical). In a pooled mean difference analysis, MISJF demonstrated greater reduction in visual analog scale-pain score compared to conservative management: -37.03 points (95%CI [-43.91, -30.15], P < 0.001). Moreover, MISJF was associated with a greater reduction in Oswestry Disability Index outcome: -21.14 points (95% CI [-24.93, -17.35], P < 0.001). AEs were low among the study groups and comparable across the included studies. One cost-effectiveness analysis was also included and reported that MISJF is more cost-effective than conservative management.001). AEs were low among the study groups and comparable across the included studies. One cost-effectiveness analysis was also included and reported that MISJF is more cost-effective than conservative management.

CONCLUSIONS

This systematic review and meta-analysis suggest that MISJF, using cannulated triangular, titanium implants, is more effective and cost-effective than conservative management in reducing pain and disability in patients with SIJ dysfunction. Further well-powered, independent research is needed to improve the overall evidence.

LEVEL OF EVIDENCE: 1

Best Practices for Postoperative Management of Posterior Sacroiliac Joint Fusion

Sacroiliac joint (SIJ) pain is a common cause of low back pain. Traditionally, treatment for SIJ joint pain and dysfunction has consisted of physical therapy, medication management, SIJ injections, and SIJ ablations. Improved recognition of the SIJ as an etiology for back pain has led to advances in treatment options. Radiofrequency of the lateral sacral branches has been shown to be effective, though evidence is fraught with inconsistent patient selection, study design and procedural technique. It also does not directly address the mechanical dysfunction of the SIJ. In order to create a more enduring approach SIJ fusion has become an attractive option to reduce pain and to improve function. This method of SI joint treatment requires guidance in the perioperative phase of care from both the physicians and advanced practice providers (APP). In order to improve care and outcomes of those undergoing posterior SI joint fusion the American Society of Pain and Neuroscience appointed an expert panel of physicians and advanced practice providers to create a best practice for the post operative care of this approach. As with any best practice, the panel considered current peer reviewed literature and clinical expertise to create guidance today. This is intended to be a living document with modifications as additional evidence comes to light in data publication. The goals of this paper are to focus on (1) wound care, (2) medication use, (3) physical activity and (4) therapeutic exercises.

Sacral Dysmorphism Increases the Risk of Superior Gluteal Artery Injury in Percutaneous Sacroiliac Joint Fusion: Case Report and Literature Review

Sacroiliac (SI) joint dysfunction is a significant contributor to low back pain. Percutaneous SI joint fusion is a minimally invasive procedure that can provide excellent pain relief for patients, but it is not without complications, especially in patients with abnormal lumbosacral anatomy. We report the case of a 71-year-old man with sacral dysmorphism who had a painful SI joint that was refractory to conservative therapy. After undergoing an elective percutaneous SI joint fusion, he was discharged in stable condition. He returned in a delayed fashion with a large subgluteal hematoma. Imaging revealed disruption of a branch of the superior gluteal artery (SGA). Surgical exploration and ligation of the SGA were undertaken. Sacral dysmorphism affects SI joint fusion procedures by altering sacral anatomy and the safe zones for SI joint implants. Variations in lumbosacral anatomy can also alter the course of the SGA and adjacent nerves. Due to the wide prevalence of sacral dysmorphism, especially in the setting of low back pain, pre-surgical planning to avoid iatrogenic injuries must be considered with advanced imaging studies such as a computed tomography angiogram of the pelvis or catheter-based angiogram, or alternative surgical approaches to the SI joint must be taken.

Adjacent segment syndrome after failed back surgery: biomechanics, diagnosis, and treatment

The adjacent segment syndrome is defined as the changes in the adjacent structures of an operated spinal level that produce symptoms of pain and disability, which worsen the quality of life of a patient. Pain management specialists must be aware of these biomechanical changes brought by spinal surgeries, as well as of the symptoms associated with pain after surgery, to reach an appropriate diagnosis and provide an adequate treatment. Specialized pain literature contains few reports on specific management of patients using the terms "adjacent segment syndrome, degeneration or disease"; most of the literature comes from surgical journals. It is necessary to perform studies with a population sample comprising patients with adjacent segment syndrome after spinal surgery, since almost all treatments applied in this group are extrapolated from those used in patients with pain originating in the same area but who have not previously undergon spine surgery. Therefore, we consider necessary for pain physicians to understand the underlying biomechanics, promote the diagnosis of this condition, and analyze possible treatments in patients with adjacent segment disease to alleviate their pain and improve their quality of life.

Pain Relief Salvage with a Novel Minimally Invasive Posterior Sacroiliac Joint Fusion Device in Patients with Previously Implanted Pain Devices and Therapies

Background

Sacroiliac joint (SIJ) pain is a common cause of low back pain, a problem experienced by two-thirds of adults in the United States population. Traditionally, the management of persistent SIJ-related pain has involved conservative therapies (physical therapy, topical medications, oral anti-inflammatory medications), interventional therapies (SIJ steroid injections or ablation), and surgery (SIJ fusion; open and lateral approach). Recent advancements in technology have paved the way for SIJ fusion via a posterior approach, which aims to minimize complications and enhance recovery.

Objective

The purpose of this study is to introduce the concept of the posterior approach to SIJ fusion as a feasible adjunct and salvage technique for patients with inadequate pain relief from other minimally invasive surgical procedures, and to validate its efficacy through a retrospective multicenter data analysis.

Design

Multicenter retrospective observational study.

Methods

Patients with refractory SIJ pain were treated by interventional pain physicians at one of the eight different pain management centers. All patients underwent posterior SIJ fusion via the LinQ^TM sacroiliac fusion procedure. Demographical data were collected, in addition to patient-reported pain relief.

Results

A total of 111 patients were included in the study and underwent posterior SIJ fusion for refractory SIJ-related pain following the use of spinal cord stimulation (SCS), interspinous spacer (ISS), intrathecal drug delivery (IDDS), and/or minimally invasive lumbar decompression (MILD). Overall, the mean patient reported pain relief following posterior SIJ fusion was 67.6%. In patients with a history of failed back surgery syndrome, the mean patient reported pain relief was 76.5%.

Conclusion

In this retrospective case series of patients with continued intolerable pain following SCS, ISS, IDDS, or MILD, a novel posterior SIJ fusion device provided significant pain relief in a salvage manner. These early results suggest that this intervention may be a therapeutic option to consider in these patients.

CT Scan and Clinical Outcomes of Novel Lateral-Oblique Percutaneous Sacroiliac Joint (SIJ) Fixation: Technique and Literature Review

Purpose The sacroiliac joint (SIJ) is estimated to be a source of pain in 15%-30% of patients presenting for the evaluation of low back pain. The SIJ may develop symptoms in an estimated 43% of patients who have had previous lumbar fusion surgeries. With increased awareness of SIJ as a pain source and for those patients who have intractable pain and who fail nonoperative treatment, surgery to stabilize the SIJ is becoming more common. Thus multiple different technologies and techniques need to be evaluated. The purpose of this study is to report on the clinical and radiographic follow-up of percutaneous lateral-oblique sacroiliac joint fusion with a threaded compression screw performed in an outpatient ambulatory surgery center (ASC). Methods Three consecutive patients were chosen for this technique, and after completion, were followed for at least 24 months as part of a pilot study to see how they responded to the treatment. The medical charts of these patients were reviewed along with follow-up radiographs and computed tomography (CT) scans to assess for radiographic fusion designated as bridging bone across the SIJ with no signs of implant loosening such as haloes around the screws, change in position, or screw breakage. The SacroFuse (Sacrix LLC, Boston, MA) SIJ screws were 12 mm x 60 mm at S1 and 12 mm x 50 mm at S2 with threads for compressive fixation and cannulated for percutaneous placement over a guidewire. We evaluated patients' demographics, the pain visual analog scale (VAS) score, and the Oswestry Disability Index (ODI) preoperatively and postoperatively. Results Our first patient was a 51-year-old male body mass index (BMI) 33.3 kg/m² with a previous lumbar fusion. He underwent a two-staged SIJ fusion. The first surgery was done as an open direct lateral surgery, and the second stage was performed three months later using a direct percutaneous lateral-oblique technique for three months. The second and third patients, respectively, were 22-year-old female status prior L5-S1 anterior lumbar interbody fusion (ALIF) plus right posterior unilateral pedicle screws. She had a BMI of 38.3 kg/m². The third patient was a 41-year-old male with a BMI of 29.5 kg/m² who underwent lateral-oblique bilateral percutaneous SIJ fixation. The latest CT imaging of each patient demonstrated increased bone density adjacent and within implants with intra-articular osseous bridging. There were no implant failures or complications. Conclusion This pilot study demonstrated the feasibility and effectiveness of a new percutaneous lateral-oblique SIJ fusion technique with a threaded compression screw done safely in an ASC. Patients demonstrated early pain relief and long-term fusion of their SIJ. We introduced the Sacrix line as a key fluoroscopic landmark for the success of this percutaneous technique.

Robot-assisted revision of sacroiliac joint fusion using a triangular titanium implant in an S2-alar-iliac trajectory: illustrative case

BACKGROUND

Sacroiliac joint (SIJ) dysfunction can lead to significant pain and disability, greatly impairing quality of life. Arthrodesis may take up to 1 year to occur, after which revision can be considered. There is a need for highly accurate and reproducible techniques for revision that allow for purchase through undisturbed bone to prevent prolonged pain and disability. Moreover, a minimally invasive technique for revision would be favorable for recovery, particularly in elderly patients.

OBSERVATIONS

An 84-year-old man with a prior history of lumbar fusion presented with severe buttock pain limiting ambulation and sitting because of the failure of arthrodesis after SIJ fusion 1 year earlier. He underwent revision using a triangular titanium implant (TTI) in an S2-alar-iliac (S2-AI) trajectory under robotic guidance, which is a novel technique not yet described in the literature. The patient’s pain largely resolved, he was able to ambulate independently, and his quality of life improved tremendously. There were no complications of surgery.

LESSONS

Placement of a TTI using an S2-AI trajectory is a safe and effective method for revision that can be considered for elderly patients. Robot-assisted navigation can be used to facilitate an accurate and reproducible approach using a minimally invasive approach.

Robotic navigation system utilization for percutaneous sacroiliac screw placement: surgical setup and technique

Sacroiliac joint (SIJ) pathology is a common cause of significant pain and disability, and operative treatment consisting of SIJ fusion can be performed in cases where non-operative measures fail to provide sustained relief. Through the years, SIJ fusion has evolved from an open invasive procedure, to more recently, being performed through minimally invasive techniques. Intraoperative navigation systems and robotic guidance are becoming popularized for SIJ fusion, as well as other routine and complex spinal cases. The utility of navigation and robotics is the enhanced ability of the surgeon to place instrumentation more accurately, with less dissection, blood less, and overall operative time. We present a technique guide for robotic instrumented SIJ fusion with intraoperative navigation that we have put into practice at our institution and found to be very beneficial to patients for the above reasons. We describe the setup and utilization of these technologies intraoperatively, and provide specific case examples to highlight our technique. The described methods have been found to be effective and reproducible, allowing for minimally invasive SIJ screw placement with high accuracy and safety. We emphasize that utilizing intraoperative navigation and robotics is not meant to substitute for surgeon knowledge of case steps or anatomy, but rather to enhance safety and efficacy. To our knowledge, robotic SIJ fusion has not been previously described in the literature.

Minimally Invasive Sacroiliac Joint Fusion with Triangular Titanium Implants: Cost-Utility Analysis from NHS Perspective

OBJECTIVE

The aim was to identify the cost-effectiveness of minimally invasive sacroiliac joint fusion (MI SIJF) surgery with titanium triangular implants for patients with sacroiliac joint (SIJ) pain who have failed conservative management, compared to non-surgical management (NSM) from a National Health Service (NHS) England perspective.

METHODS

Over a time horizon of 5 years, a cohort state transition model compared the costs and outcomes of treating patients with MI SIJF to those of traditional NSM treatment pathways. The NSM arm included two treatments: grouped physical therapy and corticosteroid injections (PTSI) or radiofrequency ablation (RFA). Three different strategies were considered: (1) a stepped pathway, (2) patients split between PTSI and RFA, and (3) RFA only. The outcome measure was incremental cost-effectiveness ratio (ICER), reported in 2018 British pounds per quality-adjusted life year (QALY) gained. One-way and probabilistic sensitivity analyses were used to test the robustness of the model results.

RESULTS

Patients undergoing MI SIJF accrued total procedure-related and pain-management costs of £8358, while NSM treatment strategy 1 had total costs of £6880. The MI SIJF cohort had 2.98 QALYs compared to strategy 1 with 2.30 QALYs. This resulted in an ICER for MI SIJF versus strategy 1 of £2164/QALY gained. Strategy 2 of the NSM arm had lower costs than strategy 1 (£6564) and 2.26 QALYs, and this resulted in an ICER of £2468/QALY gained for MI SIJF. Strategy 3 of the NSM arm had lower costs than strategy 1 (£6580), and this resulted in 2.28 QALYs and an ICER of £2518/QALY gained for MI SIJF. Probabilistic sensitivity analysis shows that at a threshold of £20,000/QALY gained, MI SIJF has a probability of being cost-effective versus NSM strategies of 96%, 97%, and 91% for strategies 1, 2, and 3, respectively.

CONCLUSION

MI SIJF appears to be cost-effective over a 5-year time horizon when compared to traditional NSM pathways in an NHS context.

Enhancing perioperative landmark detection during sacroiliac joint fusion in patients suffering from low back pain

Over the past decade, minimally invasive sacroiliac joint (SIJ) fusion has become an effective treatment for patients suffering from low back pain (LBP) originating from the SIJ. Perioperative C-arm fluoroscopy-assisted surgical navigation during SIJ fusion remains challenging due to the lack of 3D spatial information. This study developed and assessed a 3D CT/2D fluoroscopy integration approach based on digitally reconstructed radiographs (DRRs) obtained from pre-operative CT scans. Development of this approach proved feasible and landmarks were successfully translated, in retrospect, to perioperatively acquired fluoroscopies. Further expansion of and research into the proposed approach to increase perioperative navigation is indicated and additional validation should be performed.

Invasive Treatments for Low Back Disorders

OBJECTIVE

This abbreviated version of the American College of Occupational and Environmental Medicine's Low Back Disorders guideline reviews the evidence and recommendations developed for invasive treatments used to manage low back disorders.

METHODS

Comprehensive systematic literature reviews were accomplished with article abstraction, critiquing, grading, evidence table compilation, and guideline finalization by a multidisciplinary expert panel and extensive peer-review to develop evidence-based guidance. Consensus recommendations were formulated when evidence was lacking and often relied on analogy to other disorders for which evidence exists. A total of 47 high-quality and 321 moderate-quality trials were identified for invasive management of low back disorders.

RESULTS

Guidance has been developed for the invasive management of acute, subacute, and chronic low back disorders and rehabilitation. This includes 49 specific recommendations.

CONCLUSION

Quality evidence should guide invasive treatment for all phases of managing low back disorders.

Novel Lateral Approach for MIS Sacroiliac Joint Arthrodesis: An Assessment of Feasibility and Outcomes

OBJECTIVE

The prevalence of physicians experiencing work-related musculoskeletal disorders is high. Traditionally, minimally invasive surgery (MIS) sacroiliac joint (SIJ) fusions are performed with the patient oriented in the prone position, with an incision made inferior to the iliac crest. However, a novel technique that orients the patient in the lateral decubitus position has the potential of significantly enhancing ergonomics and ease of approach. The primary objectives of this study were to quantify surgical parameters, describe this 'lateral-decubitus MIS' technique, and identify imaging angle parameters that predict feasibility.

METHODS

A prospective cohort of patients who underwent MIS SIJ arthrodesis in the lateral decubitus position was evaluated at a single institution between 2017 and 2020. Medians and ranges of intraoperative blood loss, operative time, revision rate, infection, and total radiation dose were recorded. Sacral inlet and outlet angles were defined and collected to assess for operative candidacy.

RESULTS

Thirty-nine cases were identified in 34 patients who underwent the technique with an age range of 31-78 years. Median blood loss was 22.5 mL, operating room time was 32.5 minutes, and radiation dose was 30.9 rads. Average sacral inlet was 24.51° and average sacral outlet was 65.44°. Median length of stay was 0.94 days. No cases were aborted or required revision. A total of 93% of study participants reported improvement in pain. Operative parameters were comparable to the traditional prone approach.

CONCLUSIONS

The aim was to provide an insight into outcomes and metrics observed from pioneering this style of procedure. A future study comparing traditional perioperative parameters together with surgical ergonomics is needed.

International Society for the Advancement of Spine Surgery Policy 2020 Update-Minimally Invasive Surgical Sacroiliac Joint Fusion (for Chronic Sacroiliac Joint Pain): Coverage Indications, Limitations, and Medical Necessity

The index 2014 International Society for the Advancement of Spine Surgery Policy Statement-Minimally Invasive Surgical Sacroiliac Joint Fusion-was generated out of necessity to provide an International Classification of Diseases, Ninth Revision (ICD-9)-based background and emphasize tools to ensure correct diagnosis. A timely ICD-10-based 2016 update provided a granular threshold selection with improved level of evidence and a more robust and relevant database (Appendix Table A1). As procedures and treatment options have evolved, this 2020 update reviews and analyzes the expanding evidence base and provides guidance relating to differences between the lateral and dorsal surgical procedures for minimally invasive surgical sacroiliac joint fusion.

Minimally Invasive Sacroiliac Joint Fusion: A Lateral Approach Using Triangular Titanium Implants and Navigation

Background:

Minimally invasive sacroiliac (SI) joint fusion is indicated for low back pain from the SI joint that is due to degenerative sacroiliitis and/or sacroiliac joint disruption. This technique is safe and effective in relieving pain uncontrolled by nonoperative management^1-4. There is some controversy, but there continues to be increasing evidence of effectiveness.

Description:

This procedure is performed, with the patient under general anesthesia and in the prone position, using fluoroscopy or 3-dimensional (3D) navigation such as cone-beam computed tomographic (CT) imaging. After navigation setup, a navigated probe is used to approximate the desired location of each implant and trajectory. These positions are marked on the skin, and the skin is incised. A 3 to 5-cm lateral incision is made. The gluteal fascia is bluntly dissected to the outer table of the ilium. A guide pin is passed across the SI joint and into the center of the sacrum lateral to the neural foramina, which is confirmed with imaging. This is then drilled and broached. Triangular titanium rods are placed. Typically, 3 implants are placed, 2 in S1 and 1 in S2. Multiplanar postplacement imaging of the pelvis is obtained. The wound is irrigated and closed in layers.

Alternatives:

Nonsurgical alternatives have been reported to include pharmacological therapies, such as nonsteroidal anti-inflammatory drugs, therapeutic SI joint blocks⁵, and physical therapy, such as core stabilization, orthotics (SI belts), and radiofrequency ablation^1,2,6-8. The surgical alternative is an open anterior or posterior approach with SI joint arthrodesis. The anterior approach differs by the resection of the SI joint cartilage, the use of a plate or screws across the joint for stabilization, and the packing of bone graft to facilitate fusion⁹. These are more morbid and have a much longer recovery.

Rationale:

Conservative management for SI joint pain is inadequate for all patients. Having 3 of 5 positive physical examination maneuvers⁷, having confirmatory diagnostic block(s)¹⁰, and ruling out the hip or spine as the pain generator provide a success rate of >80%. These patients have early and sustained clinically important and significantly improved outcomes across varying measures compared with conservative treatment^1-4,11,12.

Expected Outcomes:

Patients can expect to experience decreased pain, reduced disability, increased daily function, and improved quality of life soon after the procedure is performed. These patients typically have an improvement of ≥50% in the Oswestry Disability Index score and a clinically significant decrease in visual analog pain scores¹³. The procedure appears durable through at least 5 years¹⁴. Complete pain relief is rare, but clinically important improvement is typical.

Important Tips:

Proper setup of the navigation system or fluoroscopy is needed to ensure accurate starting points.

For 3D navigation, use a reference pin in the contralateral posterior superior iliac spine.

Although navigation is used, radiographic images are made periodically to confirm proper placement of guide pins and implants. Images provide the greatest benefit when establishing navigation, after guide-pin placement when an outlet view allows for evaluation of pin depth, and after implant placement to confirm proper placement.

Blood loss is generally low, but care should be taken to avoid vascular injury. Although rare, improper placement has led to injury of the superior gluteal artery¹⁵ and iliac artery¹⁶. This can be avoided by staying in bone.

Proper placement of the implant is imperative in this procedure. There is the potential for nerve injury with improper placement of the implant: an L5 nerve injury if the implant is too ventral or an S1 or S2 nerve injury if the implant is too deep and into the foramen. Revision surgery is commonly due to nerve root impingement and/or malpositioning.

Preoperative 3D imaging is indicated when it is necessary to rule out differential diagnoses that mimic SI joint pain. This enables the surgeon to rule out intrapelvic pathology, assess sacral bone density¹⁷, and identify dysmorphic sacra or transitional vertebrae.

iFuse Implant System for Treating Chronic Sacroiliac Joint Pain: A NICE Medical Technology Guidance

Treatment and management of sacroiliac joint pain is often non-surgical, involving packages of care that can include analgesics, physiotherapy, corticosteroid injections and radiofrequency ablation. Surgical intervention is considered when patients no longer respond to conservative management. The iFuse Implant System is placed across the sacroiliac joint using minimally invasive surgery, stabilising the joint and correcting any misalignment or weakness that can cause chronic pain. The iFuse system was evaluated in 2018 by the UK National Institute for Health and Care Excellence (NICE) as part of the Medical Technologies Evaluation Programme (MTEP). Clinical evidence for iFuse suggests improved pain, Oswestry disability index (ODI) and quality of life compared to non-surgical management. The company (SI-Bone^®) submitted two cost models indicating that iFuse was cost saving compared with open surgery and non-surgical management. Clinicians advised that non-surgical management was the most appropriate comparator and Cedar (a health technology research centre) made changes to the model to test the impact of higher acquisition and procedure costs. Cedar found iFuse to be cost incurring by approximately £560 per patient at 7 years. During the consultation period, the company reduced the cost of some iFuse consumables, and Cedar extended the time horizon to test the assumption that iFuse would become cost saving over time. These changes indicated that iFuse becomes cost saving at 8 years (approximately £129 per patient), after which the cost saving continues to increase. NICE published guidance in October 2018 recommending that the case for adoption of the iFuse system in the UK National Health Service (NHS) was supported by the evidence.

Superiority Claims for Spinal Devices: A Systematic Review of Randomized Controlled Trials

STUDY DESIGN

Systematic review.

OBJECTIVES

Superiority claims for medical devices are commonly derived from noninferiority trials, but interpretation of such claims can be challenging. This study aimed to (a) establish the prevalence of noninferiority and superiority designs among spinal device trials, (b) assess the frequency of post hoc superiority claims from noninferiority studies, and (c) critically evaluate the risk of bias in claims that could translate to misleading conclusions.

METHODS

Study bias was assessed using the Cochrane Risk of Bias Tool. The risk of bias for the superiority claim was established based on post hoc hypothesis specification, analysis of the intention-to-treat population, post hoc modification of a priori primary outcomes, and sensitivity analyses.

RESULTS

Forty-one studies were identified from 1895 records. Nineteen (46%) were noninferiority trials. Fifteen more (37%) were noninferiority trials with a secondary superiority hypothesis specified a priori. Seven (17%) were superiority trials. Of the 34 noninferiority trials, 14 (41%) made superiority claims. A medium or high risk of bias was related to the superiority claim in 9 of those trials (64%), which was due to the analyzed population, lacking sensitivity analyses, claims not being robust during sensitivity analyses, post hoc hypotheses, or modified endpoints. Only 4 of the 14 (29%) noninferiority studies provided low bias in the superiority claim, compared with 3 of the 5 (60%) superiority trials.

CONCLUSIONS

Health care decision makers should carefully evaluate the risk of bias in each superiority claim and weigh their conclusions appropriately.

Minimally Invasive Sacroiliac Joint Fusion Using Triangular Titanium versus Cylindrical Threaded Implants: A Comparison of Patient-Reported Outcomes

BACKGROUND

Minimally invasive fusion of the sacroiliac (SI) joint has gained popularity for the treatment of refractory dysfunction. The purpose of this study was to compare the clinical outcomes of minimally invasive SI joint fusion between cylindrical threaded implants (CTIs) and triangular dowel implants (TDIs).

METHODS

We retrospectively reviewed consecutive patients who underwent SI joint fusions with either CTIs or TDIs. Data collected included patient demographics, perioperative data, and all patient-reported outcomes (PROs) including postoperative visual analog scale (VAS), Oswestry Disability Index, and Short Form-12 at 6 months and 1 year. The change from baseline PROs between the cohorts was analyzed as the primary outcome. Secondary outcomes included revision rates and time to revision between the two cohorts. A P value <0.05 was considered significant.

RESULTS

One hundred fifty-six consecutive patients underwent SI joint fusion, 74 patients with CTIs and 82 with TDIs. There was a significant difference in procedure length with CTI averaging 60.0 minutes (confidence interval: 55.7-64.3) and TDI averaging 41.2 minutes (confidence interval: 38.4-43.9, P < 0.0005). In both cohorts, there was a significant improvement in all PROs at 6 months when compared with preoperative values. However, when compared, there was no significant difference between the cohorts at 6-month follow-up or 1-year follow-up for either VAS-back, VAS-leg, Oswestry Disability Index, or Short Form-12. A 6.1% revision rate in the CTI cohort was observed compared with a 2.4% revision rate in the TDI cohort (P = 0.11).

CONCLUSIONS

SI joint fusions with TDI or CTI offer a significant improvement in pain, disability, and quality of life. However, no difference was observed between devices to suggest superior clinical outcomes. Increased revision rates in the Rialto group warrants further investigation.

A biomechanical investigation of the sacroiliac joint in the setting of lumbosacral fusion: impact of pelvic fixation versus sacroiliac joint fixation

OBJECTIVE

The sacroiliac joint (SIJ) is a known source of low-back pain. Randomized clinical trials support sacroiliac fusion over conservative management for SIJ dysfunction. Clinical studies suggest that SIJ degeneration occurs in the setting of lumbosacral fusions. However, there are few biomechanical studies to provide a good understanding of the effect of lumbosacral fusion on the SIJ. In the present study, researchers performed a biomechanical investigation to discern the effect of pelvic versus SIJ fixation on the SIJ in lumbosacral fusion.

METHODS

Seven fresh-frozen human cadaveric specimens were used. There was one intact specimen and six operative constructs: 1) posterior pedicle screws and rods from T10 to S1 (PS); 2) PS + bilateral iliac screw fixation (BIS); 3) PS + unilateral iliac screw fixation (UIS); 4) PS + UIS + 3 contralateral unilateral SIJ screws (UIS + 3SIJ); 5) PS + 3 unilateral SIJ screws (3SIJ); and 6) PS + 6 bilateral SIJ screws (6SIJ). A custom-built 6 degrees-of-freedom apparatus was used to simulate three bending modes: flexion-extension (FE), lateral bending (LB), and axial rotation (AR). Range of motion (ROM) was recorded at L5-S1 and the SIJ.

RESULTS

All six operative constructs had significantly reduced ROM at L5-S1 in all three bending modes compared to that of the intact specimen (p < 0.05). In the FE mode, the BIS construct had a significant reduction in L5-S1 ROM as compared to the other five constructs (p < 0.05). SIJ ROM was greatest in the FE mode compared to LB and AR. Although the FE mode did not show any statistically significant differences in SIJ ROM across the constructs, there were appreciable differences. The PS construct had the highest SIJ ROM. The BIS construct reduced bilateral SIJ ROM by 44% in comparison to the PS construct. The BIS and 6SIJ constructs showed reductions in SIJ ROM nearly equal to those of the PS construct. UIS and 3SIJ showed an appreciable reduction in unfused SIJ ROM compared to PS.

CONCLUSIONS

This investigation demonstrated the effects of various fusion constructs using pelvic and sacroiliac fixation in lumbosacral fusion. This study adds biomechanical evidence of adjacent segment stress in the SIJ in fusion constructs extending to S1. Unilateral pelvic fixation, or SIJ fusion, led to an appreciable but nonsignificant reduction in the ROM of the unfused contralateral SIJ. Bilateral pelvic fixation showed the greatest significant reduction of movement at L5-S1 and was equivalent to bilateral sacroiliac fusion in reducing SIJ motion.

Sacroiliac Pain: Structural Causes of Pain Referring to the SI Joint Region

BACKGROUND

The currently reported incidence of primary sacroiliac joint (SIj) pathology ranges from 15% to 30%. The differential diagnosis of SIj region pain includes pain generated from the lumbar spine, the SIj, and the hip joint. The origins of SIj dysfunctions are controversial and pain generation from this joint has been questioned.

PURPOSE

Retrospectively analyze the relative incidence of lumbar spine, SIj, and hip joint etiologies in patients complaining of ≥50% SIj region pain.

STUDY DESIGN

This is a retrospective cohort case series.

METHODS

Inclusion criteria: chief complaint SIj pain (≥50% of overall complaint). In total, 124 patients charts were reviewed from a single spine surgeon's clinic. All patients were evaluated by the same 2 practitioners and all cases were reviewed for clinical examination findings, diagnostic tests performed, final diagnosis, treatment, and clinical follow-up.

RESULTS

After complete diagnostic workup, 112 (90%) had lumbar spine pain, 5 (4%) had hip pain, 4 (3%) had primary SIj pain, and 3 (3%) had an undetermined source of pain upon initial diagnosis. SIj pain generation was confirmed via fluoroscopy-guided diagnostic injections. Following designated treatment, 11 (9%) patients returned to clinic at an average of 2.4 years complaining of continued/recurrent SIj region pain. Further investigation revealed 6 patients had confirmed pain generation from the lumbar spine, 3 patients had confirmed pain generation from the SIj, and 2 patients had undetermined sources of pain.

CONCLUSIONS

The SIj is a rare pain generator (3%-6%) in patients complaining of ≥50% SIj region pain and is a common site of referral pain from the lumbar spine (88%-90%). Clinicians ought to quantify areas of pain (via percent of overall complaint) when interviewing their patients complaining of low back pain to distinguish potential pain generators. Recommended breakdown of areas of interest include axial low back, SIj region, buttock/leg, groin/anterior thigh.

Incidence, diagnosis and management of sacroiliitis after spinal surgery: a systematic review of the literature

The sacroiliac joint (SIJ) is a possible source of persistent or new onset pain after lumbar or lumbosacral fusion. The aim of this paper is to systematically review and analyze the available literature related to the incidence, diagnosis and management of sacroiliitis after spinal arthrodesis. The authors independently screened the titles and abstracts of all articles identified concerning sacroiliac joint pain after lumbar or lumbosacral fusion, to assess their suitability to the research focus. The average incidence of sacroiliitis after lumbar or lumbosacral arthrodesis was found to be 37 ± 28.48 (range 6-75), increasing directly to the number of fused segments involved, especially when the sacrum is included. The most accurate evaluation is the image-guided injection of anesthetic solutions in the joint. Surgery treatment may be considered when conservative therapy fails, with open surgery or with minimally invasive SIJ fusion. Although the risk of developing SIJ degeneration is unclear, the results indicate that pain and degeneration of SIJ develop more often in patients undergoing lumbosacral fusion regardless of the number of melting segments. The treatment of sacroiliitis appears to be independent of his etiology, with or without previous instrumentation on several levels.

Mini-open sacroiliac joint fusion with direct bone grafting and minimally invasive fixation using intraoperative navigation

Background

Describe a novel technique for sacroiliac arthrodesis using intraoperative navigation, direct bone grafting, and minimally invasive implants. Report on the outcomes of the first cohort of these patients.

Methods

Institutional review board (IRB) approved, single center, two surgeon, retrospective study.

Results

All patients were 18 years or older, primary sacroiliac fusions, and underwent novel technique described. Fifty patients underwent 57 surgeries. Twelve male/38 female patients. All received three sacroiliac implants. Average blood loss 42.8 mL. Average length of stay 1.9 nights. Average follow-up 13.96±13 months. Statistically significant improvements in Visual Analogue Scale (VAS) scores (<0.001) for all time periods 6 weeks, 3 months, 6 months, 12 months compared to preop. Other outcomes scores [Oswestry Disability Index (ODI), and Denver Sacroiliac Joint Questionnaire (DSIJQ)] also showed a general trend for clinical improvement at all postoperative time periods. Of 2/57 (3.5%) complications were identified. No patients required surgical revision within the study window.

Conclusions

Limited open sacroiliac arthrodesis using minimally invasive implants, intraoperative navigation, and direct open bone grafting is safe and demonstrates clinical benefit, similar to other techniques for minimally invasive sacroiliac arthrodesis. There is potential for improved long-term outcomes from increased union rates.

Keywords

Sacroiliac dysfunction; minimally invasive sacroiliac fusion; open sacroiliac fusion; navigation.

Minimally Invasive Sacroiliac Joint Fusion with Cylindrical Threaded Implants Using Intraoperative Stereotactic Navigation

BACKGROUND

Significant progress in hardware and surgical techniques for sacroiliac joint (SIJ) fusion surgeries has facilitated safer and more efficacious procedures for patients. Triangular-shaped implants for SIJ fusions are the most-studied devices and have demonstrated good short-term and long-term clinical outcomes. Reports on cylindrical threaded implants are very limited. Owing to biomechanical differences in the implants and the surgical techniques required for their placement, previously reported results may not be applicable to cylindrical threaded implants. The aim of this study was to report preliminary clinical experience with minimally invasive SIJ fusion using intraoperative stereotactic navigation and the Rialto SI Fusion System.

METHODS

We retrospectively reviewed 24 patients who underwent SIJ fusions between May 2015 and October 2017 performed by a single surgeon.

RESULTS

Mean total satisfaction score was 89.0% ± 27.6%. A statistically significant reduction (P = 0.0028) in low back pain scores was noted from an average baseline score of 6.6 ± 2.4 to 3.7 ± 3.3 postoperatively. Leg pain scores decreased from 4.8 ± 3.8 to 1.5 ± 2.9 (P = 0.0034). Mean surgical time was 53.0 ± 13.9 minutes. It took significantly longer (P = 0.0089) to perform the initial 13 cases (59.9 ± 15.2 minutes) compared with subsequent cases (45.4 ± 7.3 minutes). Estimated blood loss was minimal (10.4 ± 5.2 mL).

CONCLUSIONS

Minimally invasive SI joint fusion using cylindrical threaded implants can be safely performed with minimal morbidity and good clinical outcomes.

In Vitro Biomechanical Evaluation of a Novel, Minimally Invasive, Sacroiliac Joint Fixation Device

Background

Sacroiliac (SI) joint pathology may result in low-back pain, which causes substantial disability. Treatment failure with operative management of SI pain may be related to incomplete fusion of the joint and to fixation failure. The objective of this study was to evaluate the initial biomechanical stability of SI joint fixation with a novel implantable device in an in vitro human cadaveric model.

Methods

The right and left sides of 3 cadaveric L4-pelvis specimens were tested (1) intact, (2) destabilized, and (3) instrumented with an implantable SI joint fixation device using a simulated single-stance load condition. Right-leg and left-leg stance data were grouped together for a sample size of 6, and angular range of motion (ROM) was determined during application of flexion-extension, lateral bending, and axial rotation bending moments to a limit of 7.5 Nm.

Results

Following intact testing, destabilization by severing the posterior SI joint capsule and ligaments and the pubic symphysis reliably produced a significantly destabilized joint with the mean angular ROM more than doubling in flexion-extension and lateral bending and more than tripling in axial rotation (P ≤ .003) compared to the intact condition. Instrumentation with the SI screw fixation device significantly reduced mean joint ROM compared to the destabilized condition in all 3 anatomic planes tested (P < .001). When compared to the intact condition, the SI-instrumented condition significantly reduced lateral bending (P = .01) and had a similar ROM in flexion-extension (P = .14) and axial rotation (P = .85).

Conclusions

Instrumentation with the SI screw fixation device significantly reduced mean joint ROM compared to the destabilized condition, with similar ROM in flexion-extension and axial rotation, and it significantly reduced ROM in lateral bending compared to that for the intact joint. The ROM values observed with the instrumented condition were comparable to levels of mobility considered favorable for spinal fusion.

Individuals with sacroiliac joint dysfunction display asymmetrical gait and a depressed synergy between muscles providing sacroiliac joint force closure when walking

Walking is often compromised in individuals with low back and hip disorders, such as sacroiliac joint dysfunction (SIJD). The disorder involves reduced coactivation of the gluteus maximus and contralateral latissimus dorsi, which together provide joint stability during walking. The purpose of our study was to compare the kinematics and contributions of selected muscles to identified synergies during walking between healthy individuals and those with SIJD. Six women with unilateral SIJD and six age-matched healthy controls walked on a force-measuring treadmill at 1 m/s while we recorded kinematics and the activity of 16 muscles with surface EMG. Non-negative matrix factorization was used to identify patterns of EMG activity (muscle synergies). Individuals with SIJD exhibited less hip extension and lower peak vertical ground reaction forces on the affected side than the unaffected side. In contrast to controls, the SIJD group also displayed a depressed muscle synergy between gluteus maximus on the affected side and the contralateral latissimus dorsi. The results indicate that individuals with SIJD exhibited both reduced activation of gluteus maximus during a loading synergy present in walking and greater asymmetry between legs when walking compared with age-matched controls.

Patients with sacroiliac joint dysfunction exhibit altered movement strategies when performing a sit-to-stand task

OF BACKGROUND DATA

The ability to rise from a chair is a basic functional task that is frequently compromised in individuals diagnosed with orthopedic disorders in the low back and hip. There is no published literature that describes how this task is altered by sacroiliac joint dysfunction (SIJD).

PURPOSE

The objective of this study was to compare lower extremity biomechanics and the onset of muscle activity when rising from a chair in subjects with SIJD and in healthy persons.

STUDY DESIGN

Six women with unilateral SIJD and six age-matched healthy controls performed a sit-to-stand task while we measured kinematics, kinetics, and muscle activity.

MATERIALS AND METHODS

Subjects stood up at a preferred speed from a seated position on an armless and backless adjustable stool. We measured kinematics with a 10-camera motion capture system, ground reaction forces for each leg with force plates, and muscle activity with surface electromyography. Joint angles and torques were calculated using inverse dynamics. Leg-loading rate was quantified as the average slope of vertical ground reaction (VGRF) force during the 500-millisecond interval preceding maximal knee extension.

RESULTS

Between-leg differences in loading rates and peak VGRFs were significantly greater for the SIJD group than for the control group. Maximal hip angles were significantly less for the SIJD group (p=.001). Peak hip moment in the SIJD group was significantly greater in the unaffected leg (0.75±0.22 N⋅m/kg) than in the affected leg (0.47±0.29 N⋅m/kg, p=.005). There were no between-leg or between-group differences for peak knee or ankle moments. The onset of activity in the latissimus dorsi muscle on the affected side was delayed and the erector spinae muscles were activated earlier in the SIJD group than in the control group.

CONCLUSIONS

Subjects with SIJD have a greater VGRF on the unaffected leg, generate a greater peak hip moment in the unaffected leg, use a smaller range of motion at the hip joint of the affected leg, and delay the onset of a key muscle on the affected side when rising from a seated position.

Biomechanical evaluation of sacroiliac joint fixation with decortication

BACKGROUND CONTEXT

Fusion typically consists of joint preparation, grafting, and rigid fixation. Fusion has been successfully used to treat symptomatic disruptions of the sacroiliac joint (SIJ) and degenerative sacroiliitis using purpose-specific, threaded implants. The biomechanical performance of these systems is important but has not been studied.

PURPOSE

The objective of this study was to compare two techniques for placing primary (12.5 mm) and secondary (8.5 mm) implants across the SIJ.

STUDY DESIGN

This is a human cadaveric biomechanical study of SIJ fixation.

MATERIALS AND METHODS

Pure-moment testing was performed on 14 human SIJs in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) with motion measured across the SIJ. Specimens were tested intact, after destabilization (cutting the pubic symphysis), after decortication and implantation of a primary 12.5-mm implant at S1 plus an 8.5-mm secondary implant at either S1 (S1-S1, n=8) or S2 (S1-S2, n=8), after cyclic loading, and after removal of the secondary implant. Ranges of motion (ROMs) were calculated for each test. Bone density was assessed on computed tomography and correlated with age and ROM. This study was funded by Zyga Technology but was run at an independent biomechanics laboratory.

RESULTS

The mean±standard deviation intact ROM was 3.0±1.6° in FE, 1.5±1.0° in LB, and 2.0±1.0° in AR. Destabilization significantly increased the ROM by a mean 60%-150%. Implantation, in turn, significantly decreased ROM by 65%-71%, below the intact ROM. Cyclic loading did not impact ROM. Removing the secondary implant increased ROM by 46%-88% (non-significant). There was no difference between S1-S1 and S1-S2 constructs. Bone density was inversely correlated with age (R=0.69) and ROM (R=0.36-0.58).

CONCLUSIONS

Fixation with two threaded rods significantly reduces SIJ motion even in the presence of joint preparation and after initial loading. The location of the secondary 8.5-mm implant does not affect construct performance. Low bone density significantly affects fixation and should be considered when planning fusion constructs. Findings should be interpreted in the context of ongoing clinical studies.

A consideration for the utility of the post-operative Oswestry Disability Index for measuring outcomes after sacroiliac joint fusion

Sacroiliac joint (SIJ) dysfunction and its surgical treatment remain a controversial topic in spine surgery. Determining success after SIJ fusion may be difficult due to preexisting back pain, lumbar fusion (LF), and functional disability. We examine the utility of Oswestry Disability Index (ODI) as a measure of clinical outcomes after minimally invasive SIJ fusion. A retrospective review of 24 patients with at least 12- months follow-up. Patients were divided into two groups based on presence of previous LF. Their post-operative ODI was compared with overall satisfaction, pain reduction, and return to work status. No difference in demographics was found in patients with and without prior LF with 92% of patients reporting lower post-operative pain and 96% being satisfied. Presence of LF did not show any statistically significant differences in pain or satisfaction. However, patient with prior LF reported lower ODI than those without LF at 1-year post-operatively (P=0.015). Postoperative ODI may give a falsely pessimistic impression of outcomes in SIJ fusion patients with prior LF, and its use and limitations should be carefully considered in future studies.

Biomechanics of unilateral and bilateral sacroiliac joint stabilization: laboratory investigation

OBJECTIVE Bilateral symptoms have been reported in 8%-35% of patients with sacroiliac (SI) joint dysfunction. Stabilization of a single SI joint may significantly alter the stresses on the contralateral SI joint. If the contralateral SI joint stresses are significantly increased, degeneration may occur; alternatively, if the stresses are significantly reduced, bilateral stabilization may be unnecessary for patients with bilateral symptoms. The biomechanical effects of 1) unilateral stabilization on the contralateral SI joint and 2) bilateral stabilization on both SI joints are currently unknown. The objectives of this study were to characterize bilateral SI joint range of motion (ROM) and evaluate and compare the biomechanical effects of unilateral and bilateral implant placement for SI joint fusion. METHODS A lumbopelvic model (L5-pelvis) was used to test the ROM of both SI joints in 8 cadavers. A single-leg stance setup was used to load the lumbar spine and measure the ROM of each SI joint in flexion-extension, lateral bending, and axial rotation. Both joints were tested 1) while intact, 2) after unilateral stabilization, and 3) after bilateral stabilization. Stabilization consisted of lateral transiliac placement of 3 triangular titanium plasma-sprayed (TPS) implants. RESULTS Intact testing showed that during single-leg stance the contralateral SI joint had less ROM in flexion-extension (27%), lateral bending (32%), and axial rotation (69%) than the loaded joint. Unilateral stabilization resulted in significant reduction of flexion-extension ROM (46%) on the treated side; no significant ROM changes were observed for the nontreated side. Bilateral stabilization resulted in significant reduction of flexion-extension ROM of the primary (45%) and secondary (75%) SI joints. CONCLUSIONS This study demonstrated that during single-leg loading the ROMs for the stance (loaded) and swing (unloaded) SI joints are significantly different. Unilateral stabilization for SI joint dysfunction significantly reduces the ROM of the treated side, but does not significantly reduce the ROM of the nontreated contralateral SI joint. Bilateral stabilization is necessary to significantly reduce the ROM for both SI joints.