Biomechanical Comparison of Anterior Cervical Plate Fixation Versus Integrated Fixation Cage for Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Cadaveric, biomechanic study. OBJECTIVE: To compare the range of motion profiles of the cervical spine following one-level anterior cervical discectomy and fusion (ACDF) constructs instrumented with either an interbody cage and anterior plate or integrated fixation cage in a cadaveric model. SUMMARY OF BACKGROUND DATA: While anterior plates with interbody cages are the most common construct of fixation in ACDF, newer integrated cage-plate devices seek to provide similar stability with a decreased implant profile. However, differences in postoperative cervical range of motion between the 2 constructs remain unclear. METHODS: Six cadaveric spines were segmented into 2 functional spine units (FSUs): C2-C5 and C6-T2. Each FSU was nondestructively bent in flexion-extension (FE), right-left lateral bending (LB), and right-left axial rotation (AR) at a rate of 0.5°/s under a constant axial load until a limit of 2-Nm was reached to evaluate baseline range of motion (ROM). Matched pairs were then randomly assigned to undergo instrumentation with either the standard anterior cage and plate (CP) or the integrated fixation cage (IF). Following instrumentation, ROM was then remeasured as previously described. RESULTS: For CP fixation, ROM increased by 61.2±31.7% for FE, 36.3±20.4% for LB, and 31.7±19.1% for AR. For IF fixation, ROM increased by 64.2±15.5% for FE, 56.7±39.8% for LB, and 94.5±65.1% for AR. There was no significant difference in motion between each group across FE, LB, and AR. CONCLUSION: This biomechanical study demonstrated increased motion in both the CP and IF groups relative to the intact, un-instrumented state. However, our model showed no differences in ROM between CP and IF constructs in any direction of motion. These results suggest that either method of instrumentation is a suitable option for ACDF with respect to constructing stiffness at time zero.

Hooks Versus Pedicle Screws at the Upper Instrumented Level: An In Vitro Biomechanical Comparison.

STUDY DESIGN: Controlled laboratory study. OBJECTIVE: The aim was to compare motions at the upper instrumented vertebra (UIV) and supra-adjacent level (UIV+1) between two fixation techniques in thoracic posterior spinal fusion constructs. We hypothesized there would be greater motion at UIV+1 after cyclic loading across all constructs and bilateral pedicle screws (BPSs) with posterior ligamentous compromise would demonstrate the greatest UIV+1 range of motion. SUMMARY OF BACKGROUND DATA: Proximal junctional kyphosis is a well-recognized complication following long thoracolumbar posterior spinal fusion, however, its mechanism is poorly understood. MATERIALS AND METHODS: Twenty-seven thoracic functional spine units were randomly divided into three UIV fixation groups (n=9): (1) BPS, (2) bilateral transverse process hooks (TPHs), and (3) BPS with compromise of the posterior elements between UIV and UIV+1 (BPS-C). Specimens were tested on a servohydraulic materials testing system in native state, following instrumentation, and after cyclic loading. functional spine units were loaded in flexion-extension (FE), lateral bending, and axial rotation. RESULTS: After cyclic testing, the TPH group had a mean 29.4% increase in FE range of motion at UIV+1 versus 76.6% in the BPS group ( P <0.05). The BPS-C group showed an increased FE of 49.9% and 62.19% with sectioning of the facet joints and interspinous ligament respectively prior to cyclic testing. CONCLUSION: BPSs at the UIV led to greater motion at UIV+1 compared to bilateral TPH after cyclic loading. This is likely due to the increased rigidity of BPS compared to TPH leading to a "softer" transition between the TPH construct and native anatomy at the supra-adjacent level. Facet capsule compromise led to a 49.9% increase in UIV+1 motion, underscoring the importance of preserving the posterior ligamentous complex. Clinical studies that account for fusion rates are warranted to determine if constructs with a "soft transition" result in less proximal junctional kyphosis in vivo .

Biomechanical Analysis of Multilevel Posterior Cervical Spinal Fusion Constructs.

STUDY DESIGN: Controlled Laboratory Study. OBJECTIVE: To compare multilevel posterior cervical fusion (PCF) constructs stopping at C7, T1, and T2 under cyclic load to determine the range of motion (ROM) between the lowest instrumented level and lowest instrumented-adjacent level (LIV-1). SUMMARY OF BACKGROUND DATA: PCF is a mainstay of treatment for various cervical spine conditions. The transition between the flexible cervical spine and rigid thoracic spine can lead to construct failure at the cervicothoracic junction. There is little evidence to determine the most appropriate level at which to stop a multilevel PCF. METHODS: Fifteen human cadaveric cervicothoracic spines were randomly assigned to 1 of 3 treatment groups: PCF stopping at C7, T1, or T2. Specimens were tested in their native state, following a simulated PCF, and after cyclic loading. Specimens were loaded in flexion-extension), lateral bending, and axial rotation. Three-dimensional kinematics were recorded to evaluate ROM. RESULTS: The C7 group had greater flexion-extension motion than the T1 and T2 groups following instrumentation (10.17±0.83 degree vs. 2.77±1.66 degree and 1.06±0.55 degree, P <0.001), and after cyclic loading (10.42±2.30 degree vs. 2.47±0.64 degree and 1.99±1.23 degree, P <0.001). There was no significant difference between the T1 and T2 groups. The C7 group had greater lateral bending ROM than both thoracic groups after instrumentation (8.81±3.44 degree vs. 3.51±2.52 degree, P =0.013 and 1.99±1.99 degree, P =0.003) and after cyclic loading. The C7 group had greater axial rotation motion than the thoracic groups (4.46±2.27 degree vs. 1.26±0.69 degree, P =0.010; and 0.73±0.74 degree, P =0.003) following cyclic loading. CONCLUSION: Motion at the cervicothoracic junction is significantly greater when a multilevel PCF stops at C7 rather than T1 or T2. This is likely attributable to the transition from a flexible cervical spine to a rigid thoracic spine. Although this does not account for in vivo fusion, surgeons should consider extending multilevel PCF constructs to T1 when feasible. LEVEL OF EVIDENCE: Not applicable.

Rates and Predictors of Surgery for Lumbar Disc Herniation Between the Military and Civilian Health Care Systems.

STUDY DESIGN: Retrospective review (level of evidence III). OBJECTIVE: Surgical care patterns for lumbar disc herniation (LDH), a common musculoskeletal condition of high relevance to the Military Health System (MHS), have not been described or compared across the direct care and purchased care MHS components. This study aimed to describe surgery rates in MHS beneficiaries who were diagnosed with LDH in direct care versus purchased care and to evaluate characteristics associated with the location of surgery. Differences in care patterns for LDH may suggest unexpected variation within the centrally managed MHS. METHODS: We described 1-year rates of surgery among beneficiaries who were diagnosed with LDH in direct care versus purchased care. Among beneficiaries who were diagnosed in direct care and had surgery, multivariable logistic regression models were used to identify characteristics associated with surgery location. RESULTS: We identified 726,638 MHS beneficiaries who were diagnosed with LDH in direct care or purchased care during the 9-year study period. One-year surgery rates were 10.1% in beneficiaries who were diagnosed in direct care versus 11.3% in beneficiaries who were diagnosed in purchased care. Among the 7467 patients who were diagnosed in direct care and had surgery within 1 year, characteristics associated with lower probability of surgery in purchased care versus direct care included diagnosing facility type (hospital with a neurosurgery or spine specialty versus clinic (odds ratio [OR], 0.12 (95% CI, 0.10-0.15)), Navy versus Army (OR, 0.24 (95% CI, 0.21-0.28)), and diagnosing facility specialty (Medical Expense and Performance Reporting System) (surgical care (OR, 0.33 (95% CI, 0.27-0.40)) and orthopedic care (OR, 0.39 (95% CI, 0.33-0.46)) versus primary care. The presence of comorbidities was associated with higher probability of surgery in purchased care versus direct care (OR, 1.20 (95% CI, 1.06-1.36)). CONCLUSIONS: The 1-year rate of surgery for LDH was modestly higher in beneficiaries who were diagnosed in purchased care versus direct care. Among patients who were diagnosed in direct care, several patient-level and facility-level characteristics were associated with receiving surgery in purchased care, suggesting potentially unexpected variation in care utilization across components of the MHS.

Lumbar Degenerative Disease and Muscle Morphology Before and After Lower Limb Loss in Four Military Patients.

INTRODUCTION: Low back pain (LBP) is highly prevalent after lower limb amputation (LLA). Reports describing longitudinal changes in spine health before and after amputation are rare. This study describes lumbar spine pathology, muscle morphology, and the continuum of care for LBP before and after LLA. MATERIALS AND METHODS: We queried electronic medical records of patients who sought care for LBP before and after unilateral LLA between January 2002 and April 2020 and who had documented lumbar imaging pre- and post-LLA. Patient demographics, muscle morphology, spinal pathology, premorbid and comorbid conditions, self-reported pain, and treatment interventions were assessed. RESULTS: Four patients with LBP and imaging before and after LLA were identified. Intervertebral disc degeneration progressed after amputation in three patients, whereas facet arthrosis progressed in both female patients. The fat content of lumbar musculature generally increased after amputation. Conservative management of LBP before and after amputation was standard, with progression to steroidal injections. CONCLUSIONS: Lumbar spine health may degrade after amputation. Here, lumbar muscle size did not change after LLA, yet the fat content increased in combination with increases in facet and intervertebral disc degeneration.

ALIF Versus TLIF for L5-S1 Isthmic Spondylolisthesis: ALIF Demonstrates Superior Segmental and Regional Radiographic Outcomes and Clinical Improvements Across More Patient-reported Outcome Measures Domains.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The purpose of this study was to compare segmental and regional radiographic parameters between anterior interbody fusion (ALIF) and posterior interbody fusion (TLIF) for treatment of L5-S1 isthmic spondylolisthesis, and to assess for changes in these parameters over time. Secondarily, we sought to compare clinical outcomes via patient-reported outcome measures (PROMs) between techniques and within groups over time. SUMMARY OF BACKGROUND DATA: Isthmic spondylolistheses are frequently treated with interbody fusion via ALIF or TLIF approaches. Robust comparisons of radiographic and clinical outcomes are lacking. METHODS: We reviewed pre- and postoperative radiographs as well as Patient-Reported Outcomes Measurement Information System (PROMIS) elements for patients who received L5-S1 interbody fusions for isthmic spondylolisthesis in the Mass General Brigham (MGB) health system (2016-2020). Intraclass correlation testing was used for reliability assessments; Mann-Whitney U tests and Sign tests were employed for intercohort and intracohort comparative analyses, respectively. RESULTS: ALIFs generated greater segmental and L4-S1 lordosis than TLIF, both at first postoperative visit (mean 26 days [SE = 4]; 11.3° vs. 1.3°, P  < 0.001; 6.2° vs. 0.3°, P  = 0.005) and at final follow-up (mean 410days [SE = 45]; 9.6° vs. 0.2°, P < 0.001; 7.9° vs. 2.1°, P = 0.005). ALIF also demonstrated greater increase in disc height than TLIF at first (9.6 vs. 5.5 mm, P < 0.001) and final follow-up (8.7 vs. 3.6 mm, P < 0.001). Disc height was maintained in the ALIF group but decreased over time in the TLIF cohort (ALIF 9.6 vs. 8.7 mm, P = 0.1; TLIF 5.5 vs. 3.6 mm, P < 0.001). Both groups demonstrated improvements in Pain Intensity and Pain Interference scores; ALIF patients also improved in Physical Function and Global Health - Physical domains. CONCLUSION: ALIF generates greater segmental lordosis, regional lordosis, and restoration of disc height compared to TLIF for treatment of isthmic spondylolisthesis. Additionally, ALIF patients demonstrate significant improvements across more PROMs domains relative to TLIF patients.Level of Evidence: 3.

Comparison of Radiation Exposure Between Anterior, Lateral, and Posterior Interbody Fusion Techniques and the Influence of Patient and Procedural Factors.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: The aim of this study was to elucidate the relative influence of multiple factors on radiation usage for anterior, lateral, and posterior based lumbar interbody fusion techniques. SUMMARY OF BACKGROUND DATA: There has been substantial global growth in the performance of lumbar interbody fusions, due to evolution of techniques and approaches and increased attention to sagittal alignment. Utilization of intraoperative imaging guidance has similarly expanded, with a predominance of fluoroscopy and consequent increased radiation exposure. There have been no larger-scale studies examining the role of patient and procedural factors in driving radiation exposure across different interbody techniques. METHODS: We used a clinical registry to review all single-level lumbar interbody fusions performed between January 2016 and October 2020. Operative records were reviewed for the amount of radiation exposure during the procedure. Patient age, biologic sex, body mass index (BMI), operative surgeon, surgical level, surgical time, and fusion technique were recorded. Multivariable adjusted analyses using negative binomial regression were used to account for confounding. RESULTS: We included 134 interbody fusions; 80 performed with a posterior approach (TLIF/PLIF), 43 via an anterior approach (ALIF) with posterior pedicle fixation, and 9 performed with a lateral approach (LLIF/XLIF). Average radiation per case was 136.4 mGy (SE 17.3) for ALIF, 108.6 mGy (16.9) for LLIF/XLIF, and 60.5 mGy (7.4) for TLIF/PLIF. We identified lateral approaches, increased BMI, minimally invasive techniques, and more caudal operative levels as significantly associated with increased radiation exposure. CONCLUSION: We identified several novel drivers of radiation exposure during interbody fusion procedures, including the relative importance of technique and the level at which the fusion is performed. More caudal levels of intervention and lateral based techniques had significantly greater radiation exposure.Level of Evidence: 4.

Long-term prescription opioid use among US military service members injured in combat.

INTRODUCTION: During the Global War on Terrorism, many US Military service members sustained injuries with potentially long-lasting functional limitations and chronic pain. We sought to understand the patterns of prescription opioid use among service members injured in combat. METHODS: We queried the Military Health System Data Repository to identify service members injured in combat between 2007 and 2011. Sociodemographics, injury characteristics, treatment information, and costs of care were abstracted for all eligible patients. We surveyed for prescription opioid utilization subsequent to hospital discharge and through 2018. Negative binomial regression was used to identify factors associated with cumulative prescription opioid use. RESULTS: We identified 3,981 service members with combat-related injuries presenting during the study period. The median age was 24 years (interquartile range [IQR], 22-29 years), 98.5% were male, and the median follow-up was 3.3 years. During the study period, 98% (n = 3,910) of patients were prescribed opioids at least once and were prescribed opioids for a median of 29 days (IQR, 9-85 days) per patient-year of follow-up. While nearly all patients (96%; n = 3,157) discontinued use within 6 months, 91% (n = 2,882) were prescribed opioids again after initially discontinuing opioids. Following regression analysis, patients with preinjury opioid exposure, more severe injuries, blast injuries, and enlisted rank had higher cumulative opioid use. Patients who discontinued opioids within 6 months had an unadjusted median total health care cost of US $97,800 (IQR, US $42,364-237,135) compared with US $230,524 (IQR, US $134,387-370,102) among those who did not discontinue opioids within 6 months (p < 0.001). CONCLUSION: Nearly all service members injured in combat were prescribed opioids during treatment, and the vast majority experienced multiple episodes of prescription opioid use. Only 4% of the population met the criteria for sustained prescription opioid use at 6 months following discharge. Early discontinuation may not translate to long-term opioid cessation in this population. LEVEL OF EVIDENCE: Epidemiology study, level III.

Variability and contributions to cost associated with anterior versus posterior approaches to lumbar interbody fusion.

OBJECTIVE: Lumbar interbody fusions are being performed with increased frequency in the last decade. Anterior and posterior interbody techniques have demonstrated relatively similar success rates. Nonetheless, despite increased attention to cost-effective care delivery, approach-related differences in procedural cost and predictors for these differences remain poorly defined. The purpose of this investigation was to characterize the variability in cost for anterior versus posterior-based lumbar interbody fusions and to identify key predictors of procedural cost. METHODS: We evaluated the records of all patients who underwent a primary anterior (ALIF) or posterior/transforaminal (PLIF/TLIF) lumbar interbody fusion with concomitant posterior fusion from 2016 to 2020 at four hospitals in a major metropolitan area. We reviewed the records of all included patients and abstracted demographics, insurance status, approach, operative time, diagnosis, surgeon, institution, open versus minimally invasive technique, and components of procedural costs. Costs based upon interbody approach were compared via multivariable adjusted analyses using negative binomial regression. RESULTS: We included 139 interbody fusion procedures; 98 were performed via posterior approach (TLIF/PLIF) and 41 using an anterior approach. Anterior techniques were associated with significantly increased costs as compared to posterior procedures (anterior, $16316 [SE 556] vs. posterior, $9415 [SE 345]; p < 0.001). This determination remained significant following multivariable adjusted analysis (regression coefficient -0.22, 95% CI -0.34, -0.10, p < 0.001). Multivariable analysis also indicated that surgeon, invasiveness, and procedure time were significant predictors of total cost. CONCLUSION: Our findings demonstrate that anterior interbody techniques are, on average, 173% (anterior, $16316 [SE 556] vs. posterior, $9415 [SE 345]; p < 0.001) more expensive than posterior-based procedures. Given the relative equipoise of these different approaches for many clinical applications, these findings should be considered in an ecosystem increasingly attentive to cost effective care delivery. This work has also provided specific procedural variables for surgeons and systems to target when optimizing procedural costs.

A Biomechanical Comparison of High-Tensile Strength Tape Versus High-Tensile Strength Suture for Tendon Fixation Under Cyclic Loading.

PURPOSE: To compare the biomechanical properties of high-tensile strength tape and high-tensile strength suture across 2 selected stitch techniques, the Krackow and whip stitch, in securing tendinous tissue during 5,000 cycles of nondestructive loading followed by a load to failure. METHODS: Fourteen matched pairs each of cadaveric Achilles, quadriceps, and patellar tendons (n = 84) were randomly assigned to either Krackow or whip stitch and sutured with either 2-mm high-tensile strength tape or No. 2 high-tensile strength suture. Specimens were preloaded to 20 N, cyclically loaded from 20 to 200 N for 5,000 cycles at 2 Hz, and then loaded to failure at 200 mm/min. Linear mixed models evaluated the effects of suture material and stitch technique on cyclic normalized tendon-suture elongation, total normalized tendon-suture elongation at 5,000 cycles, and maximum load at failure. RESULTS: Across all suture constructs, normalized elongation was greater during the initial 10 cycles, compared with all subsequent cycling intervals (all P < .001). There was less total normalized elongation (ß = -0.239; P = .007) and greater maximum load at failure in tape (ß = 163.71; P = .014) when used in the Krackow stitch compared with the whip stitch. CONCLUSIONS: Our findings indicate that tape used in the Krackow stitch maintains the most favorable fixation strength after enduring cyclic loading, with greater maximum load at failure. In addition, overall normalized elongation during long-term cyclic loading was predominately affected by the stitch technique used, regardless of the suture material; however, tape allowed less normalized elongation during the initial loading cycles, especially when placed in the whip stitch. CLINICAL RELEVANCE: Understanding the potential short- and long-term outcomes of suture material and stitch technique on securing tendinous tissue under repetitive stresses can help inform clinicians on optimal tendon fixation techniques for early postoperative activities.

Factors Associated With Progression to Surgical Intervention for Lumbar Disc Herniation in the Military Health System.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: To determine surgery-free survival of patients receiving conservative management of lumbar disc herniation (LDH) in the military healthcare system (MHS) and risk factors for surgical intervention. SUMMARY OF BACKGROUND DATA: Radiculopathy from LDH is a major cause of morbidity and cost. METHODS: The Military Data Repository was queried for all patients diagnosed with LDH from FY2011-2018; the earliest such diagnosis in a military treatment facility (MTF) was kept for each patient as the initial diagnosis. Follow-up time to surgical intervention was defined as the time from diagnosis to first encounter for lumbar microdiscectomy or lumbar decompression in either a MTF or in the civilian sector. The Military Data Repository was also queried for history of tobacco use at any time during MHS care, age at the time of diagnosis, sex, MHS beneficiary category, and diagnosing facility characteristics. Multivariable Cox proportional hazards models were used to evaluate the associations of patient and diagnosing facility characteristics with time to surgical intervention. RESULTS: A total of 84,985 MHS beneficiaries including 62,771 active duty service members were diagnosed with LDH in a MTF during the 8-year study period. A total of 10,532 (12.4%) MHS beneficiaries, including 7650 (10.9%) active duty, failed conservative management onto surgical intervention with lumbar microdiscectomy or lumbar decompression. Median follow-up time of the cohort was 5.2 (interquartile range 2.6, 7.5) years. Among all healthcare beneficiaries, several patient-level (younger age, male sex, and history of tobacco use) and facility-level characteristics (hospital vs. clinic and surgical care vs. primary care clinic) were independently associated with higher risk of surgical intervention. CONCLUSION: LDH compromises military readiness and negatively impacts healthcare costs. MHS beneficiaries with LDH have a good prognosis with approximately 88% of patients successfully completing conservative management. However, strategies to improve outcomes of conservative management in LDH should address risks associated with both patient and facility characteristics.Level of Evidence: 4.

Lumbar disc height and vertebral Hounsfield units: association with interbody cage subsidence.

OBJECTIVE: Postoperative subsidence of transforaminal lumbar interbody fusion (TLIF) cages can result in loss of lordosis and foraminal height, and potential recurrence of nerve root impingement. The objectives of this study were to determine factors associated with TLIF cage subsidence. Specifically, the authors sought to determine if preoperative disc height compared to cage height could be used to predict TLIF interbody cage subsidence, and if decreased postoperative vertebral Hounsfield units (HUs) predisposed to cage subsidence. METHODS: The authors retrospectively reviewed all patients undergoing instrumented TLIF from two institutions between July 2004 and June 2014. The preoperative disc height was measured for the operative and adjacent-level disc on MRI. The difference between cage and disc heights was measured and compared between the subsidence and nonsubsidence groups. The average HUs of the L1 vertebral body were measured on CT scans. RESULTS: Eighty-nine patients were identified with complete imaging and follow-up information. Forty-five patients (50.6%) had evidence of interbody cage subsidence on follow-up CT. The average cage subsidence was 5.5 mm (range 2.2-10.8 mm). The average implant height was significantly higher in the subsidence group compared to the nonsubsidence group (12.6 vs 11.2 mm). Additionally, the difference between cage height and preoperative adjacent-level disc height was also significantly larger in the subsidence group (3.8 vs 1.2 mm). First lumbar vertebral body (L1) HUs were significantly higher in the nonsubsidence versus the subsidence group (167.8 vs 137.71 HUs, p = 0.002). Multivariate logistic regression analysis identified suprajacent disc height and L1 HUs to be independent predictors of interbody cage subsidence. Receiver operating characteristic curves identified a suprajacent to cage height difference > 1.3 mm to have a 93.3% sensitivity for cage subsidence. CONCLUSIONS: This study is the first of its kind to demonstrate the association between vertebral body HUs and suprajacent disc height with the development of interbody cage subsidence after TLIF. The authors found that patients with lower HUs in the L1 vertebral body were more likely to experience subsidence, regardless of surgical level. Additionally, the study demonstrated that interbody cage height > 1.3 mm above the height of the suprajacent level is an independent risk factor for cage subsidence, with 93.3% sensitivity. These findings suggest that these factors may be utilized to create a template preoperatively for intraoperative cage selection.

Intrasite Antibiotic Powder for the Prevention of Surgical Site Infection in Extremity Surgery: A Systematic Review.

INTRODUCTION: Although the role of intrasite antibiotic powder in preventing surgical site infections (SSIs) has been extensively explored in spinal surgery, it remains underevaluated in the other orthopaedic subspecialties. This systematic review examines the utilization of intrawound antibiotic powder as a prophylactic measure against SSIs in orthopaedic procedures. METHODS: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, electronic searches were conducted on Ovid MEDLINE, and PubMed. Only English language, nonspine clinical studies published before May 2018 were included. RESULTS: The initial search identified 179 individual citations, and 11 studies met the eligibility criteria. All included studies were level III retrospective studies. Represented subspecialties included total joint arthroplasty, upper extremity, foot and ankle, and trauma. Eight studies demonstrated a statistically significant decrease in SSIs with the use of intrasite antibiotic powder. DISCUSSION: There are no current guidelines for the use of intrasite antibiotic powder for the prevention of SSIs in orthopaedic procedures. Despite the lack of high-quality evidence available in the literature, published smaller studies do suggest a significant protective effect. However, recommendations with regard to this technique after common orthopaedic procedures cannot yet be made.

The effect of lumbar corticosteroid injections on postoperative infection in lumbar arthrodesis surgery.

We sought to characterize the association between lumbar corticosteroid injections and postoperative infection rate for patients in the Military Health System undergoing lumbar arthrodesis. The Military Health System Data Repository was searched for all patients undergoing lumbar arthrodesis from 2009 to 2014. Current Procedural Terminology (CPT) codes were used to identify the subset of patients who also received preoperative lumbar corticosteroid injections. These patients were stratified by timing, type, and number of injections. Infection rates were compared to the control group of patients who did not receive preoperative lumbar corticosteroid injections. The search identified 3403 patients who had undergone lumbar arthrodesis from 2009 to 2014 within the Military Health System. 612 patients had received lumbar corticosteroid injections prior to surgery (348 epidural, 264 facet). The control group consisted of the remaining 2791 patients. Overall post-operative infection rate was 1.47% with an infection rate in the injection group of 1.14% versus 1.54% in the control group. When stratified by time, infection rates ranged from 0% to 1.85% in the injection groups. No differences between injection and control groups reached statistical significance in any subgroup analysis. Post-operative infection rate is not significantly increased in patients receiving lumbar corticosteroid injections (LCSIs) prior to lumbar arthrodesis. No differences were observed in infection rates based on timing, type, or number of injections prior to surgery.