Return to Duty in Military Service Members Following Minimally Invasive Sacroiliac Joint Fusion.

INTRODUCTION: As the utilization of minimally invasive sacroiliac joint fusion (SIJF) continues to expand, a better understanding of postoperative outcomes is needed, particularly in young and active individuals. The purpose of this study is to assess the outcomes of this procedure in an active duty military population by examining return-to-duty (RTD) rates. MATERIALS AND METHODS: A retrospective review of the electronic medical record from a tertiary military medical center was performed for active duty service members undergoing SIJF from January 2013 to January 2019. The primary outcome measured was RTD at 6 months, with active duty status at 1 year, last follow-up, and revision surgery as secondary outcomes. Demographic and surgical variables recorded included patient age, gender, military rank, utilization of navigation, and implant type. RESULTS: Sixteen service members met the inclusion criteria, with a mean age of 40.5 ± 6.7 years. The mean follow-up after surgery was 24 ± 15 months. Patients received either cylindrical (n = 6) or triangular (n = 10) implants placed with (n = 6) or without (n = 10) navigation. Within 6 months of surgery, 56% of patients were able to RTD. Patients undergoing navigation-assisted procedures were significantly more likely to RTD at 6 months (100% vs. 30%, P = .011) compared to those undergoing surgery performed with orthogonal fluoroscopic imaging. Compared to those with cylindrical implants, patients with triangular implants were also more likely to RTD at 6 months (80% vs. 17%, P = .035). CONCLUSIONS: Following SIJF, a small majority of service members were able to return to full active duty status by 6 months. Further studies are needed to assess the potential benefits of navigation and implant selection, as our retrospective review noted differences in outcomes based on these variables.

Minimally Invasive Sacroiliac Fusion Revision: A Technique Guide.

STUDY DESIGN: A retrospective case-series of revision sacroiliac joint (SIJ) fusions. OBJECTIVE: To provide a technique guide for revision minimally invasive SIJ fusion. SUMMARY OF BACKGROUND DATA: SIJ dysfunction is a prevalent, yet underdiagnosed condition. This disparity exists as a result of diagnostic complexity and lack of a viable surgical treatment option. However, the advent of minimally invasive SIJ fusion has created a resurgence of interest in this debilitating condition. Multiple studies have reported on the increased use of minimally invasive SIJ fusion in recent years, but there is a paucity of literature on management in a revision setting. METHODS: A case series of 5 patients from a single academic tertiary referral center over a 3-year period will serve to highlight technical pearls and considerations in SIJ fusion revision. Revision SIJ fusions were identified through a retrospective review of a surgical database and demographic, surgical, and radiographic data were obtained through review of the electronic medical record. RESULTS: Five patients underwent SIJ fusion revision from 2015 to 2018. There were 3 main modes of failure, with indications for revision including nerve root irritation and SIJ pain recurrence. The mean age at time of revision was 48.8 ± 14.3 years, and the mean follow-up after revision was 2.0 + 0.9 years. Familiarity with SIJ anatomy and use of stereotactic navigation can improve implant position and purchase. Additionally, bone graft and bone morphogenetic protein can be used to fill in old implant tracks and to augment bony ingrowth and ongrowth of new implants. CONCLUSIONS: Increased use of SIJ fusion creates a demand for comprehensive revision strategies and necessitates familiarity with SIJ anatomy. Preoperative planning to determine causes of failure and use of intraoperative navigation are essential to help surgeons better understand the preferential trajectory for each implant. LEVEL OF EVIDENCE: 4.

Minimally Invasive Lumbopelvic Fixation for Unstable U-Type Sacral Fractures.

Multi-planar transverse, U-type, and vertical sacral fractures occur from high energy trauma or as pathologic fractures and often have associated neurologic and extremity injuries. Modern treatment algorithms fall into two broad categories: 1) percutaneous posterior pelvic fixation (iliosacral or transiliac-transsacral screws) or 2) lumbopelvic fixation. Posterior pelvic screw fixation is minimally invasive but typically requires restricted weight bearing until fracture union. In many cases, lumbopelvic fixation allows for a closed reduction and provides stability to allow full weight bearing immediately after surgery; however, this fixation is often removed in a second surgery after fracture healing. Lumbopelvic fixation was originally described as an open procedure, minimally invasive lumbopelvic fixation is a recent variation and has shown promising results with less morbidity. We present a case series of unstable U-type sacral fractures treated with minimally invasive lumbopelvic fixation with staged hardware removal to illustrate the advantages and complications associated with this new technique. Ten patients with U-type sacral fractures underwent minimally invasive lumbopelvic fixation from 2016 to 2019. Six patients underwent scheduled hardware removal an average of 3.5 (range 1.9-5.5) months after index surgery. Two patients did not undergo hardware removal due to short life expectancy and diagnosis of pathologic fractures. One patient was lost to follow-up. One patient had failed fracture reduction and went on to sacral malunion that required a late sacral extension osteotomy to restore her ability to stand upright. Final disposition of all nine patients with follow-up was normal standing upright posture and normal ambulation without assistive device. There were no late displacements on postoperative upright radiographs. Complex sacral fractures are a challenging injury that can be treated with percutaneous posterior pelvic or lumbopelvic fixation. Lumbopelvic fixation offers the advantages of closed reduction to restore pelvic incidence and immediate weight bearing but has greater surgical morbidity than percutaneous posterior pelvic fixation and often requires hardware removal. The morbidity of lumbopelvic fixation may be reduced with minimally invasive techniques. Minimally invasive lumbopelvic fixation is a treatment option to be considered for complex sacral fractures.

Comparing Lumbar Disc Space Preparation With Fluoroscopy Versus Cone Beam-Computed Tomography and Navigation: A Cadaveric Study.

STUDY DESIGN: Cadaveric study. OBJECTIVE: This cadaveric study sought to evaluate the efficacy of disc space preparation with cone beam-computed tomography with navigation (CBCT+N) for instrument placement compared with instrument placement with conventional fluoroscopy. SUMMARY OF BACKGROUND DATA: Disc space preparation from a transforaminal lumbar approach is challenging with respect to visualization, and surgeons currently rely on tactile feel and two-dimensional imaging in the operating room to assess instrument positioning. METHODS: Two orthopedic spine surgeons performed 40 disc space preparations after eight cadavers were randomly assigned to fluoroscopy versus CBCT+N. Digital images of each vertebral endplate were captured and the percent disc removed by area for the total disc and by quadrants was determined using digital imaging software. RESULTS: There were 20 lumbar disc levels prepared in the fluoroscopy group. There were 3 thoracolumbar, and 17 lumbar disc levels prepared in the experimental group. Percent disc removed relative to the total area of the disc, as determined by the digital imaging software, was higher in the CBCT+N group (P ≤ 0.0001). More disc was removed in both the anterior contralateral and posterior contralateral quadrants in the CBCT+N group (P = 0.0006 and P ≤ 0.0001 respectively). The intraclass correlation coefficient among blinded reviewers for percent disc removed was 0.759 (95% confidence interval, 0.587-0.866)]. There was no difference in time to complete disc space preparation, number of instrument passes, or number of endplate violations between the two groups (P = 0.28, P = 0.92, and P = 0.34 respectively). CONCLUSION: The results of this cadaveric investigation reveal that CBCT+N guidance may be used to assess instrument placement for interbody disc space preparation in a similar length of time, with no difference in instrument passes or endplate violations, in comparison with fluoroscopy. LEVEL OF EVIDENCE: 5.

Neuroforaminal Bone Growth Following Minimally Invasive Transforaminal Lumbar Interbody Fusion With BMP: A Computed Tomographic Analysis.

STUDY DESIGN: Computed tomographic analysis. OBJECTIVE: To identify radiographic patterns of symptomatic neuroforaminal bone growth (NFB) in patients who have undergone a single-level minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) augmented with bone morphogenetic proteins (BMP) utilizing computed tomography (CT). SUMMARY OF BACKGROUND DATA: BMP induces osteoblast differentiation leading to new bone formation. The association of BMP utilization and heterotopic bone formation after an MIS-TLIF has been described. However, studies have been limited in their patient population and details regarding diagnosis and treatment of NFB. MATERIALS AND METHODS: Postoperative CT scans of the symptomatic and asymptomatic patients were analyzed to identify patterns of heterotopic bone growth on axial and sagittal views. The area of bone growth at the disk level, lateral recess, adjacent foramen, and retrovertebral area were measured. Mann-Whitney U test was used to compare the areas of bone growth between cohorts. RESULTS: Postoperative CT images between 18 symptomatic and 13 asymptomatic patients were compared. On axial views, the symptomatic patients demonstrated greater areas of bone growth at the disk level (164.0±92.4 vs. 77.0±104.9 mm), and lateral recess (69.6±70.5 and 5.9±12.5 mm) as well as in the total cross-sectional area (290.3±162.1 vs. 119.4±115.6 mm). On sagittal imaging, the mean bone growth at the subarticular level (148.7±185.1 vs. 35.8±37.4 mm) and the total cross-sectional area (298.4±324.4 vs. 85.8±76.3 mm) were greater in symptomatic patients (P<0.01). Amount of BMP utilized and operative levels were no different between cohorts. CONCLUSIONS: The findings of the present study suggest that an anatomic association exists between recalcitrant postoperative radiculopathy and NFB following an MIS-TLIF with BMP. Increased total bone growth as measured on serial axial and sagittal sections was associated with postoperative radiculopathy. The association between radiculopathy and the extension of BMP-induced bone growth toward the traversing nerve root appeared the most significant.

Functional outcomes of hip arthroplasty in active duty military service members.

There are few reports on outcomes after hip arthroplasty in the military population despite increases among young, active patients. U.S. Army service members with coded hip arthroplasty between 2004 and 2010 were reviewed. Patient demographic variables were correlated with occupational outcomes. Of 183 patients, the occupational outcomes at a minimum 2 years postoperatively for service members undergoing primary hip arthroplasty were medically separated (n = 44, 24%), retired (n = 82, 45%), and returned to active duty (n = 57, 31%). Multivariate analysis identified that age less than 40 years [odds ratio (OR), 3.41; 95% confidence interval (CI), 1.14, 10.12] and enlisted rank (OR, 3.63; 95% CI, 1.29, 10.20) as major independent risk factors for medical separation. Univariate analysis revealed that officer rank had an increased likelihood of postoperative combat deployment than enlisted rank (OR, 3.39; 95% CI, 1.50, 7.94). Despite encouraging results in the civilian literature, this study documents modest retention rates on active duty at a minimum of 2 years after primary hip arthroplasty.