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Little is known about the effect of wearing a facemask on the physiological and perceptual responses to exercise in patients with pulmonary arterial hypertension (PAH). We performed a single-center retrospective study to evaluate whether facemask wearing impacted distanced covered, rating of perceived exertion (RPE), and arterial oxygen saturation (SpO2) during a 6-minute walk test (6MWT) in PAH patients. Forty-five patients being treated for group 1 PAH and who performed a 6MWT before and after implementation of a facemask mandate were included in the analysis. Each included patient performed a 6MWT without (test 1) and with (test 2) a facemask between October 1, 2019, and October 31, 2020. At both time points, all patients also underwent a submaximal cardiopulmonary exercise test, echocardiogram, and blood laboratory tests, with a Registry to Evaluate Early and Long-Term PAH Disease Management Lite 2.0 score calculated. The two 6MWTs were performed 81±51 days apart, and all patients were clinically stable at both testing timepoints. Six-minute walk test distance was not different between test 1 and test 2 (405±108 m vs 400±103 m, P=.81). Similarly, both end-test RPE and lowest SpO2 during the 6MWT were not different in test 1 and test 2 (RPE: 2.5±1.7 vs 2.5±2.1, P=.91; SpO2 nadir: 92.8±3.4% vs 93.3±3.3%, P=.55). Our findings show that wearing a facemask has no discernable impact on the arterial oxygen saturation and perceptual responses to exercise or exercise capacity in patients with moderate-to-severe PAH. This study reinforces the evidence that wearing a facemask is safe in PAH patients, even during exercise.

Pulmonary arterial hypertension is a progressive vascular disease with a high mortality rate without proper therapy. Identification of the appropriate treatment for each patient is critical in regard to adverse effects, health care costs, ease of treatment, and the potential for prognostication. Treatment strategies typically begin with acute vasoreactivity testing, which is performed during a right heart catherization. If positive, a calcium channel blocker may work; however, another pulmonary arterial hypertension–specific medication is necessary when testing is negative. Acute vasoreactivity testing is currently recommended to be performed only in certain subgroups of pulmonary arterial hypertension, but not when related to connective tissue disease. In this report, we describe a patient who had systemic sclerosis–related pulmonary arterial hypertension with a positive acute vasoreactivity test result. The patient was placed on calcium channel blocker monotherapy that has been well tolerated for 12 years, resulting in improved symptoms and exercise capacity. The long-term response to calcium channel blocker therapy in systemic sclerosis–associated pulmonary arterial hypertension has not been previously described. In addition, pulmonary artery pressures have been well controlled. The absence of genetic smooth muscle variants prevalent in vasoresponsive idiopathic pulmonary arterial hypertension is also unique.

Background: Stabilization methods for distal tibiofibular syndesmotic injuries present risk of malreduction. We compared reduction accuracy and biomechanical properties of a new syndesmotic reduction and stabilization technique using 2 suture buttons placed through a sagittal tunnel in the fibula and across the tibia just proximal to the incisura with those of the conventional method. Methods: Syndesmotic injury was created in 18 fresh-frozen cadaveric lower leg specimens. Nine ankles were repaired with the conventional method and 9 with the new technique. Reduction for the conventional method was performed using thumb pressure under direct visualization and for the new method by tightening both suture buttons passed through the fibular and tibial tunnels. Computed tomography was used to assess reduction accuracy. Torsional resistance, fibular rotation, and fibular translation were evaluated during biomechanical testing. Results: The new technique showed less lateral translation of the fibula on CT measurements after reduction (0.06 ± 0.06 mm) than the conventional method (0.26 ± 0.31 mm), P = .02. The new technique produced less fibular rotation during internal rotation after 0 cycles (new –2.4 ± 1.4 degrees; conventional –5.0 ± 1.2 degrees, P = .001), 100 cycles (new –2.1 ± 1.9 degrees; conventional –4.6 ± 1.4 degrees, P = .01), and 500 cycles (new –2.2 ± 1.6 degrees; conventional –5.3 ± 2.5 degrees, P = .01) and during external rotation after 100 cycles (new 3.9 ± 3.3 degrees; conventional 5.9 ± 3.5 degrees, P = .02) and 500 cycles (new 3.3 ± 3.2 degrees; conventional 6.3 ± 2.6 degrees, P = .03). Fixation failed in 3 specimens. Conclusion: The new syndesmotic reduction and fixation technique resulted in more accurate reduction of the fibula in the tibial incisura in the coronal plane and better rotational stability compared with the conventional method. Clinical Relevance: This new technique of syndesmosis reduction and stabilization may be a reliable alternative to current methods.

Study Design: A human cadaveric biomechanical analysis. Objective: The purpose of this study was to evaluate the bone density/trabecular width of the thoracic pedicle and correlate that with its resistance against compressive loading used during correction maneuvers in the thoracic spine (i.e., cantilever bending). Summary Of Background Data: As surgeons perform cantilever correction maneuvers in the spine, it is common to have pedicle screws pullout or displace while placing corrective forces on the construct. Currently, surgeons either compress against the cephalad aspect of the pedicle or vice versa. We set out to establish which aspect of the pedicle was the most dense and to determine the optimal direction for screw compression during kyphosis/deformity correction. Methods: Fifteen fresh-frozen cadaveric vertebrae (n = 15) were examined by micro-computed tomography to determine percent bone volume/total volume (%BV/TV) within the cephalad and caudad aspects of the pedicle. Specimens were sectioned in the sagittal plane. Pedicles were instrumented according to the straightforward trajectory on both sides. Specimens were then mounted and loading to failure was performed perpendicular to the screw axis (either the cephalad or the caudad aspect of the pedicle). Results: Mean failure when loading against the caudad aspect of the pedicle was statistically, significantly greater (454.5 ± 241.3 N vs. 334.79 1 ± 158.435 N) than for the cephalad pedicle (P < 0.001). In concordance with failure data, more trabecular and cortical bones were observed within the caudad half of the pedicle compared with the cephalad half (P < 0.001). Conclusion: Our results suggest that the caudad half of the pedicle is denser and withstands higher forces compared with the cephalad aspect. In turn, the incidence of intraoperative screw loosening and/or pedicle fracture may be reduced if the compressive forces (cantilever bending during deformity correction) placed upon the construct are applied against the caudad portion of the pedicle. [ABSTRACT FROM AUTHOR]

Study Design: Review article. Objective: To review the indications, operative strategy, and complications of revision cervical spine reconstruction. Summary Of Background Data: With many surgeons expanding their indications for cervical spine surgery, the number of patients being treated operatively has increased. Unfortunately, the number of patients requiring revision procedures is also increasing, but very little literature exists reviewing changes in the indications or operative planning for revision reconstruction. Methods: Narrative and review of the literature. Results: In addition to the well-accepted indications for primary cervical spine surgery (radiculopathy, myelopathy, instability, and tumor), we have used the following indications for revision surgery: pseudarthrosis, adjacent segment degeneration, inadequate decompression, iatrogenic instability, and deformity. Our surgical goal for pseudarthrosis is obviously to obtain a fusion, which can usually be performed with an approach not done previously. Our surgical goals for instability and deformity are more complex, with a focus on decompression of any neurologic compression, correction of deformity, and stability. Conclusion: Revision cervical spine reconstruction is safe and effective if performed for the appropriate indications and with proper planning. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective review of medical records and radiographs. Objective: We assessed the clinical outcomes of lumbosacral dissociation (LSD) after traumatic, combat-related injuries, and to review our management of these distinct injuries and report our preliminary follow-up. Summary Of Background Data: LSD injuries are an anatomic separation of the pelvis from the spinal column, and are the result of high-energy trauma. A relative increase in these injuries has been seen in young healthy combat casualties subjected to high-energy blast trauma. Methods: We performed a retrospective review of inpatient/outpatient medical records and radiographs for all patients treated at our institution with combat-related lumbosacral dissociations. Twenty-three patients met inclusion criteria of combat-related lumbosacral dissociations with one-year follow-up. Patients were treated as follows: no fixation (9), sacroiliac screw fixation (8), posterior spinal fusion (5) and sacral plate (1). All patients with radiographic evidence of a zone III sacral fracture, in addition to associated lumbar fractures indicating loss of the iliolumbar ligamentous complex integrity were included. Results: In 15 patients, the sacral fracture were an H or U type zone III fracture, whereas in the remaining nine, the sacral fracture was severely comminuted and unable to classify (six open fractures). There was no difference in visual analog scale (VAS) between treatment modalities. Two open injuries had residual infections. One patient treated with an L4-ilium posterior spinal fusion with instrumentation required instrumentation removal for infection. At a mean follow-up of 1.71 years (range, 1-4.5), 11 patients (48%) still reported residual pain and the mean VAS at latest follow-up was 1.7 (range, 0-7). Conclusion: Operative stabilization promoted healing and earlier mobilization, but carries a high-postoperative risk of infection. Nonoperative management should be considered in patients whose comorbidities prevent safe stabilization. [ABSTRACT FROM AUTHOR]

We studied patients with combat-related injuries that required delayed amputation at least 4 months after the initial injury due to dysfunction, persistent pain, and patient desires. Late amputations were performed 22 times in 22 patients (21 men, 1 woman) since 2003. Fourteen patients underwent transtibial amputation, 5 transfemoral amputations, 1 knee disarticulation, and 2 transradial amputations. The primary indications for late amputation were neurologic dysfunction in 6 patients, persistent or recurrent infection in 6, neurogenic pain in 3, non-neurogenic pain in 5, and a globally poor functional result in 2. Sixteen of 22 patients reported multiple indications for electing to undergo amputation, with an average of 2.1 specific indications per patient. At final clinical follow-up an average of 13 months after amputation, all patients reported subjectively improved function and reported that they would undergo amputation again under similar circumstances. When medically and functionally practicable, every effort is given to limb salvage following severe combat-related extremity injuries. There is no single risk factor that increases the likelihood of delayed amputation, but the combination of complex pain symptoms with neurologic dysfunction appears to increase the risk, particularly if the initial insult is a severe hindfoot injury or distal tibia fracture. With appropriately selected and counseled patients, elective late amputation results in a high degree of patient satisfaction and subjectively improved function. [ABSTRACT FROM AUTHOR]

Study Design: Literature Review., Objective: The goal of this study was to provide a comprehensive outline of spinal injuries that may transpire over the course of military service from traumatic to repetitive stress injuries and chronic sequalae. We considered studies that assessed spinal injuries in the combat and non-combat settings as reported in the literature over the last 15-20 years., Summary of Background Data: Military service places servicemembers under substantial physical demands, while also exposing them to dangerous, unpredictable environments. As a result, servicemembers are at an increased risk of spinal injuries from combat-related trauma and other causes. They may have different care needs and recovery profiles when compared to civilians with spinal disorders., Methods: We performed a review of the available literature on spinal injuries and spinal care in the Military Health System from 2001-present., Results: The studies discussed in this review were primarily focused on the conflicts in both Iraq and Afghanistan from over ten years ago and do not fully capture the present-day advancements in military technology that may have an impact on the potential for spinal injuries. The long-term effects of sustained military service and the relative influence of high demand versus sedentary military occupations on the development of spinal disorders remains poorly understood. Given the changing nature of military service, both with respect to the demographic in uniform and the ever-evolving nature of modern combat, we believe that only a long-term prospective observational study dedicated to the surveillance of spinal problems could effectively answer these questions., Conclusion: Further research into the present-day characterization of spinal injuries is warranted given the advancements in both military technology and spine care that have occurred over the last ten years., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: Low back pain (LBP) is highly prevalent after lower limb amputation (LLA) and contributes to substantial reductions in quality of life and function. Towards understanding pathophysiological mechanisms underlying LBP after LLA, this article compares lumbar spine pathologies and muscle morphologies between individuals with LBP, with and without LLA., Materials and Methods: We queried electronic medical records of Service members with and without LLA who sought care for LBP at military treatment facilities between January 2002 and May 2020. Two groups with cLBP, one with (n = 15) and one without unilateral transtibial LLA (n = 15), were identified and randomly chosen from a larger sample. Groups were matched by age, mass, and sex. Lumbar muscle morphology, Pfirrmann grades, Modic changes, facet arthrosis, Meyerding grades, and lordosis angle were determined from radiographs and magnetic resonance images available in the medical record. Independent t-tests compared variables between cohorts while multiple regression models determined if intramuscular fat influenced Pfirrmann grades. Chi-square determined differences in presence of spondylolysis and facet arthrosis., Results: Lordosis angle was larger with LLA (P = 0.01). Spondylolysis was more prevalent with LLA (P = 0.008; 40%) whereas facet arthrosis was similar between cohorts (P = 0.3). Muscle area was not different between cohorts, yet intramuscular fat was greater with LLA (P ≤ 0.05). Intramuscular fat did not influence Pfirrmann grades (P > 0.15)., Conclusions: Despite similar lumbar muscle size, those with unilateral LLA may be predisposed to progress to symptomatic spondylolisthesis and intramuscular fat. Surgical and/or rehabilitation interventions may mitigate long-term effects of diminished spinal health, decrease LBP-related disability, and improve function for individuals with LLA., (Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2024. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

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., Competing Interests: The authors declare no conflict of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Low back pain due to spaceflight is a common complaint of returning astronauts. Alterations in musculoskeletal anatomy during spaceflight and the effects of microgravity (μg) have been well-studied; however, the mechanisms behind these changes remain unclear. The National Aeronautics and Space Administration has released the Human Research Roadmap to guide investigators in developing effective countermeasure strategies for the Artemis Program, as well as commercial low-orbit spaceflight. Based on the Human Research Roadmap, the existing literature was examined to determine the current understanding of the effects of microgravity on the musculoskeletal components of the spinal column. In addition, countermeasure strategies will be required to mitigate these effects for long-duration spaceflight. Current pharmacologic and nonpharmacologic countermeasure strategies are suboptimal, as evidenced by continued muscle and bone loss, alterations in muscle phenotype, and bone metabolism. However, studies incorporating the use of ultrasound, beta-blockers, and other pharmacologic agents have shown some promise. Understanding these mechanisms will not only benefit space technology but likely lead to a return on investment for the management of Earth-bound diseases., Competing Interests: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

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., (Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2022. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

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., (© The Association of Military Surgeons of the United States 2023. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

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., Competing Interests: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

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 ., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJS/H41).

Competing Interests: The authors declare no conflict of interest.

Background: The effect of preoperative mental health on outcomes after anterior cervical discectomy and fusion (ACDF) is of increasing interest. The purpose of this study was to utilize patient-reported outcome measures (PROMs) to compare outcomes after ACDF in patients with and without poor mental health. We hypothesized that patients with worse baseline mental health would report worse outcomes after surgery., Methods: Patients undergoing ACDF for degenerative cervical spondylosis with at least 12 months of follow-up were included. Outcomes collected before and after surgery included the RAND-36, Neck Disability Index (NDI), EuroQol 5-dimension (EQ-5D), and Single Assessment Numeric Evaluation (SANE) score., Results: Seventy-one patients were included and assigned to the depression or nondepression group based on baseline mental health. The depression group had worse baseline preoperative scores across all PROMs: NDI (44.2 vs 36.8, P = 0.05), RAND (1511.4 vs 2198.18, P < 0.001), EQ-5D (12.55 vs 10.14, P < 0.001), and SANE (56.3 vs 72.9, P < 0.001). Postoperatively, the depression group had worse scores at the final follow-up for RAND (2242.8 vs 2662.2, P = 0.03) and SANE (71.5 vs 80.8, P = 0.02). Both groups experienced improvements with ACDF across all PROMs. The changes in each PROM were not statistically significant between groups. There were no statistically significant differences in the percentage of patients achieving the minimal clinically important difference across PROMs., Conclusion: This study is the first to utilize the RAND-36, EQ-5D, NDI, and SANE scores to assess preoperative mental health and its effect on postoperative outcomes after ACDF. While poor preoperative mental health status yielded significantly worse baseline and postoperative outcomes scores, patients experienced significant improvement in symptoms after ACDF., Clinical Relevance: Clinicians should be aware of the effects of poor mental health status on clinical outcomes in patients undergoing anterior cervical fusion, but can still expect significant clinical improvements after surgery., Competing Interests: Declaration of Conflicting Interests: The following authors have the following interests to disclose: Ahmad Nassr: Receives fellowship and research funding from AO Spine North America, research funding from Pfizer, and research funding from Premia Spine. Benjamin Elder: Consultant for Johnson & Johnson and is on the Medical Advisory Board for InjectSense. Melvin Helgeson, Scott Wagner, and Donald Colantonio are employees of the United States government. Drs. Mohamad Bydon, Brett Freedman, Christopher Kepler, and Arjun Sebastian have no interests to disclose., (This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2022 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.)

Background: Current techniques for ulnar collateral ligament (UCL) reconstruction do not reproduce the anatomic ulnar footprint of the UCL. The purpose of this study was to describe a novel UCL reconstruction technique that utilizes proximal-to-distal ulnar bone tunnels to better re-create the anatomy of the UCL and to compare the biomechanical profile at time zero among this technique, the native UCL, and the traditional docking technique., Hypothesis: The biomechanical profile of the anatomic technique is similar to the native UCL and traditional docking technique., Study Design: Controlled laboratory study., Methods: Ten matched cadaveric elbows were potted with the forearm in neutral rotation. The palmaris longus tendon graft was harvested, and bones were sectioned 14 cm proximal and distal to the elbow joint. Specimen testing included (1) native UCL testing performed at 90° of flexion with 0.5 N·m of valgus moment preload, (2) cyclic loading from 0.5 to 5 N·m of valgus moment for 1000 cycles at 1 Hz, and (3) load to failure at 0.2 mm/s. Elbows then underwent UCL reconstruction with 1 elbow of each pair receiving the classic docking technique using either anatomic (proximal to distal) or traditional (anterior to posterior) tunnel locations. Specimen testing was then repeated as described., Results: There were no differences in maximum load at failure between the anatomic and traditional tunnel location techniques (mean ± SD, 34.90 ± 10.65 vs 37.28 ± 14.26 N·m; P = .644) or when including the native UCL (45.83 ± 17.03 N·m; P = .099). Additionally, there were no differences in valgus angle after 1000 cycles across the anatomic technique (4.58°± 1.47°), traditional technique (4.08°± 1.28°), and native UCL (4.07°± 1.99°). The anatomic group and the native UCL had similar valgus angles at failure (24.13°± 5.86° vs 20.13°± 5.70°; P = .083), while the traditional group had a higher valgus angle at failure when compared with the native UCL (24.88°± 6.18° vs 19.44°± 5.86°; P = .015)., Conclusion: In this cadaveric model, UCL reconstruction with the docking technique utilizing proximal-to-distal ulnar tunnels better restored the ulnar footprint while providing valgus stability comparable with reconstruction with the docking technique using traditional anterior-to-posterior ulnar tunnel locations. These results suggest that utilization of the anatomic tunnel location in UCL reconstruction has similar biomechanical properties to the traditional method at the time of initial fixation (ie, not accounting for healing after reconstruction in vivo) while keeping the ulnar tunnels farther from the ulnar nerve. Further studies are warranted to determine if an anatomically based UCL reconstruction results in differing outcomes than traditional reconstruction techniques., Clinical Relevance: Current UCL reconstruction techniques do not accurately re-create the ulnar UCL footprint. The UCL is a dynamic constraint to valgus loads at the elbow, and a more anatomic reconstruction may afford more natural joint kinematics. This more anatomic technique performs similarly to the traditional docking technique at time zero, and the results of this study may offer a starting point for future in vivo studies.

Purpose: To evaluate the biomechanical profile of onlay distal biceps repair with an intramedullary unicortical button versus all-suture anchors under cyclic loading and maximal load to failure., Methods: Twenty paired fresh-frozen human cadaveric elbows were randomized to onlay distal biceps repair with either a single intramedullary button or with two 1.35-mm all-suture anchors. A 1.3-mm high tensile strength tape was used in a Krackow stitch to suture the tendons in both groups. Specimens and repair constructs were loaded for 3,000 cycles and then loaded to failure. Maximum load to failure, mode of failure, and construct elongation were recorded., Results: Mean (± standard deviation) maximum load to failure for the unicortical intramedullary button and all-suture anchor repairs were 503.23 ± 141.77 N and 537.33 ± 262.13 N (P = .696), respectively. Mean maximum displacement after 3,000 cycles (± standard deviation) was 4.17 ± 2.05 mm in the button group and 2.06 ± 1.05 mm in the suture anchor group (P = .014). Mode of failure in the button group was suture tape rupture in 7 specimens, failure at the tendon-suture interface in 2 specimens, and button pullout in 1 specimen. Anchor pullout was the mode of failure in all suture anchor specimens. There were no tendon ruptures or radial tuberosity fractures in either group., Conclusions: This study demonstrates that onlay distal biceps repair with 2 all-suture anchors has similar maximum strength to repair with an intramedullary button and that both are viable options for fixation., Clinical Relevance: All-suture anchors and unicortical intramedullary button have similar maximum strength at time zero. Both constructs provide suitable fixation for onlay distal biceps repair., (Published by Elsevier Inc.)

Competing Interests: The authors declare no conflict of interest.

Objective: To assess the feasibility, patient/provider satisfaction, and perceived value of telehealth spine consultation after rapid conversion from traditional in-office visits during the COVID-19 pandemic., Methods: Data were obtained for patients undergoing telehealth visits with spine surgeons in the first 3 weeks after government restriction of elective surgical care at 4 sites (March 23, 2020, to April 17, 2020). Demographic factors, technique-specific elements of the telehealth experience, provider confidence in diagnostic and therapeutic assessment, patient/surgeon satisfaction, and perceived value were collected., Results: A total of 128 unique visits were analyzed. New (74 [58%]), preoperative (26 [20%]), and postoperative (28 [22%]) patients were assessed. A total of 116 (91%) visits had successful connection on the first attempt. Surgeons felt very confident 101 times (79%) when assessing diagnosis and 107 times (84%) when assessing treatment plan. The mean and median patient satisfaction was 89% and 94%, respectively. Patient satisfaction was significantly higher for video over audio-only visits (P < 0.05). Patient satisfaction was not significantly different with patient age, location of chief complaint (cervical or thoracolumbar), or visit type (new, preoperative, or postoperative). Providers reported that 76% of the time they would choose to perform the visit again in telehealth format. Sixty percent of patients valued the visit cost as the same or slightly less than an in-office consultation., Conclusions: This is the first study to demonstrate the feasibility and high patient/provider satisfaction of virtual spine surgical consultation, and appropriate reimbursement and balanced regulation for spine telehealth care is essential to continue this existing work., (Copyright © 2021 Elsevier Inc. All rights reserved.)

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 (β = -0.239; P = .007) and greater maximum load at failure in tape (β = 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., (Copyright © 2021 Arthroscopy Association of North America. All rights reserved.)

Intervertebral body fusion devices (IBFDs) are commonly used in the treatment of various spinal pathologies. Intra-operative fractures of polyether-ether-ketone (PEEK) implants have been reported in the literature and to the FDA as device-related adverse events. The device and/or implant inserter failures typically occur during device impaction into the disc space and require implant removal and replacement. These additional steps may cause further complications along with increased surgical time and cost. Currently, there are no standardized test methods that evaluate clinically relevant impaction loading conditions on IBFDs. This study aims to develop an in vitro test method that would evaluate implant resistance to failure during intra-operative impaction. To achieve this, (1) surgical implantations of IBFDs were simulated in nine lumbar cadaver specimens by three different orthopedic spine surgeons (n = 3/surgeon). Impact force and mallet speed data were acquired for each surgeon. (2) Based on the acquired surgeon data, a benchtop mechanical test setup was developed to differentiate between two TLIF IBFD designs and two inserter designs (for a total of four IBFD-inserter combinations) under impaction loading. During implant insertion, impact force measurements indicated that lumbar IBFDs are subjected to high energy forces that may exceed their mechanical strength. Our test method successfully replicated clinically-relevant loading conditions and was effective at differentiating failure parameters between different implant and inserter instrument designs. The mechanical test method developed shows promise in its ability to assess impaction resistance of IBFD/inserter designs and evaluate potential risks of device failure during intraoperative loading., (Published by Elsevier Ltd.)

Study Design: Multicenter study., Objectives: The COVID-19 pandemic has obligated physicians to recur to additional resources and make drastic changes regarding the standard physician-patient encounter. In the last century, there has been a substantial improvement in technology, which over the years has opened the door to a new form of medical practicing known as telemedicine., Methods: Healthcare workers from three hospitals involved in the care for COVID-19 patients in the united states were invited to share their experience using telemedicine to deliver clinical care to their patients., Results: Since the appearance of this worldwide outbreak, social distancing has been a key factor in preventing the spread of the virus, for which measures have been taken to limit physical contact. Because of the ongoing situation, telemedicine has been progressively incorporated into the physician-patient encounters and quickly has become an essential component in the day-today medical practice., Conclusions: It is feasible to deliver viable spine practice with the use of telemedicine. A proper patient selection of patients requiring virtual treatment versus those requiring in-person visits should be considered.

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., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: Bundled payments for spine surgery, which is known for having high overall cost with wide variation, have been previously studied in older adults. However, there has been limited work examining bundled payments in working-age patients. We sought to identify the variation in the cost of spine surgery among working age adults in a large, national insurance claims database., Methods: We queried the TRICARE claims database for all patients, aged 18-64, undergoing cervical and non-cervical spinal fusion surgery between 2012 and 2014. We calculated the case mix adjusted, price standardized payments for all aspects of care during the 60-, 90-, and 180-day periods post operation. Variation was assessed by stratifying Hospital Referral Regions into quintiles., Results: After adjusting for case mix, there was significant variation in the cost of both cervical ($10,538.23, 60% of first quintile) and non-cervical ($20,155.59, 74%). Relative variation in total cost decreased from 60- to 180-days (63 to 55% and 76 to 69%). Index hospitalization was the primary driver of costs and variation for both cervical (1st-to-5th quintile range: $11,033-$19,960) and non-cervical ($18,565-$36,844) followed by readmissions for cervical ($0-$11,521) and non-cervical ($0-$13,932). Even at the highest quintile, post-acute care remained the lowest contribution to overall cost ($2070 & $2984)., Conclusions: There is wide variation in the cost of spine surgery across the United States for working age adults, driven largely by index procedure and readmissions costs. Our findings suggest that implementing episodes longer than the current 90-day standard would do little to better control cost variation.

Background: Stabilization methods for distal tibiofibular syndesmotic injuries present risk of malreduction. We compared reduction accuracy and biomechanical properties of a new syndesmotic reduction and stabilization technique using 2 suture buttons placed through a sagittal tunnel in the fibula and across the tibia just proximal to the incisura with those of the conventional method., Methods: Syndesmotic injury was created in 18 fresh-frozen cadaveric lower leg specimens. Nine ankles were repaired with the conventional method and 9 with the new technique. Reduction for the conventional method was performed using thumb pressure under direct visualization and for the new method by tightening both suture buttons passed through the fibular and tibial tunnels. Computed tomography was used to assess reduction accuracy. Torsional resistance, fibular rotation, and fibular translation were evaluated during biomechanical testing., Results: The new technique showed less lateral translation of the fibula on CT measurements after reduction (0.06 ± 0.06 mm) than the conventional method (0.26 ± 0.31 mm), P = .02. The new technique produced less fibular rotation during internal rotation after 0 cycles (new -2.4 ± 1.4 degrees; conventional -5.0 ± 1.2 degrees, P = .001), 100 cycles (new -2.1 ± 1.9 degrees; conventional -4.6 ± 1.4 degrees, P = .01), and 500 cycles (new -2.2 ± 1.6 degrees; conventional -5.3 ± 2.5 degrees, P = .01) and during external rotation after 100 cycles (new 3.9 ± 3.3 degrees; conventional 5.9 ± 3.5 degrees, P = .02) and 500 cycles (new 3.3 ± 3.2 degrees; conventional 6.3 ± 2.6 degrees, P = .03). Fixation failed in 3 specimens., Conclusion: The new syndesmotic reduction and fixation technique resulted in more accurate reduction of the fibula in the tibial incisura in the coronal plane and better rotational stability compared with the conventional method., Clinical Relevance: This new technique of syndesmosis reduction and stabilization may be a reliable alternative to current methods., Competing Interests: Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Babar Shafiq, MD, reports grants and non-financial support from Arthrex, Inc, during the conduct of the study. ICMJE forms for all authors are available online., (© The Author(s) 2020.)

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.

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., (Published by Elsevier Ltd.)

Case: We present an 11-year-old girl with adolescent idiopathic scoliosis who underwent uncomplicated posterior spinal fusion and developed transient upper extremity weakness secondary to a cervical cord injury several hours after the conclusion of the case., Conclusions: Perioperative hypotension, positioning, and mild cervical canal stenosis contributed to cervical cord injury following posterior thoracic instrumentation. Optimal perioperative resuscitation and awareness of cervical spine anatomy along with proper positioning may prevent this rare but potentially serious complication.

Several approaches (anterior, posterior, lateral, and transforaminal) are used in lumbar fusion surgery. However, it is unclear whether one of these approaches has the greatest subsidence risk as published clinical rates of cage subsidence vary widely (7-70%). Specifically, there is limited data on how a patient's endplate morphometry and trabecular bone quality influences cage subsidence risk. Therefore, this study compared subsidence (stiffness, maximum force, and work) between anterior (ALIF), lateral (LLIF), posterior (PLIF), and transforaminal (TLIF) lumbar interbody fusion cage designs to understand the impact of endplate and trabecular bone quality on subsidence. Forty-eight lumbar vertebrae were imaged with micro-ct to assess trabecular microarchitecture. micro-ct images of each vertebra were then imported into image processing software to measure endplate thickness (ET) and maximum endplate concavity depth (ECD). Generic ALIF, LLIF, PLIF, and TLIF cages made of polyether ether ketone were implanted on the superior endplates of all vertebrae and subsidence testing was performed. The results indicated that TLIF cages had significantly lower (p < 0.01) subsidence stiffness and maximum subsidence force compared to ALIF and LLIF cages. For all cage groups, trabecular bone volume fraction was better correlated with maximum subsidence force compared to ET and concavity depth. These findings highlight the importance of cage design (e.g., surface area), placement on the endplate, and trabecular bone quality on subsidence. These results may help surgeons during cage selection for lumbar fusion procedures to mitigate adverse events such as cage subsidence., (Copyright © 2019 by ASME.)

Background: Acute low back pain is one of the most common reasons for individuals to seek medical care in the United States. The US Military Health System provides medical care to approximately 9.4 million beneficiaries annually. These patients also routinely suffer from acute low back pain. Within this health system, patients can receive care and treatment from physicians, or physician extenders including physician assistants and nurse practitioners. Given the diversity of provider types and their respective training programs, it would be informative to evaluate variation in care delivery, adherence to clinical guidelines, and differences within the MHS among a complex mix of provider types., Methods: This study was a retrospective, cross-sectional quantitative analysis that examined variations in treatment between provider types within the Military Health System in 2015 for treatment of acute low back pain using administrative data. In addition to descriptive and summary statistics, binomial logistic regression models were used to assess variation in practice patterns among physicians and mid-level practitioners for prescribing of non-steroidal anti-inflammatory, opioids, plain radiography, computed tomography, and magnetic resonance imaging., Results: With regard to prescribing practices, results indicated that the odds of receiving non-steroidal anti-inflammatory prescriptions increased significantly for both physician assistants and nurse practitioners when compared to physicians. For basic radiological referrals, odds increased significantly for ordering plain radiography for physician assistants and nurse practitioners when compared to physicians. For more advanced imaging, odds significantly decreased for ordering computed tomography (CT) and slightly decreased for magnetic resonance for physician assistants, nurse practitioners and physician residents compared to the physician group. Additionally this study discovered differences in the prescribing patterns between provider categories. Both contractors and civilians had higher odds of prescribing opioids compared to active duty providers., Conclusions: As physician assistants and nurse practitioners continue to gain popularity as physician extenders in the US and in addressing provider shortages for the Military Health System, further research should be conducted to determine what impact, if any, the differences found in this study have on patient outcomes. In addition, provider type warrants further investigation to determine if labor mix and outsourcing decisions within a single payer system impacts health delivery and value based care.

This Cervical and Thoracolumbar Spine Injury Evaluation, Transport, and Surgery Clinical Practice Guideline (CPG) is designed to provide guidance to the deployed provider when they are treating a combat casualty who has sustained a spine or spinal cord injury. The CPG objective for the treatment and the movement of these patients is to maintain spinal stability through transport, perform decompression when urgently needed, achieve definitive stabilization when appropriate, avoid secondary injury, and prevent deterioration of the patient's neurological condition. Thorough and accurate documentation of the patient's neurological examination is crucial to ensure appropriate management decisions are made as the patient transits through the evacuation system. The use of this CPG should be in conjunction with good clinical judgment.

Background Context: Commercially available lumbar integrated fixation cages (IFCs) have variable designs. For example, screw-based designs have up to four screws inserted at different locations across the vertebral end plate as well as at different angles in the sagittal and transverse planes. This is important as end plate and trabecular bone quality may vary across the vertebra and may affect the screw's fixation ability, particularly if bone purchase at the bone-screw interface is poor., Purpose: This study aimed to evaluate whether variations in local bone quality surrounding IFC screws inserted at different locations in the vertebrae would affect their mechanical performance., Study Design: This study is an in vitro human cadaveric biomechanical analysis., Materials and Methods: Fourteen lumbar (L3 and L4) vertebrae from 10 cadavers (age: 76±10 years, bone mineral density: 0.89±0.17 g/cm 2 ) were used for this study. Pilot holes (3.5-mm diameter×15-mm length) representing three different IFC screw orientations (lateral to medial [LM], midsagittal [MS], and medial to lateral [ML]) were created in vertebrae using an IFC guide and bone awl. The screw locations and trajectories chosen are representative of commercially available IFC designs. These pilot holes were then imaged with high-resolution microcomputed tomography to obtain a three-dimensional structure of the bone surrounding the pilot hole. Local bone morphology was then quantified by evaluating a 3-mm-thick circumferential volume surrounding the pilot hole. Integrated fixation screws were implanted into pilot holes while recording maximum screw insertional torques. Screws were toggled in the cranial direction from 10 to 50 N for first 10,000 cycles, and the maximum load was increased by 25 N for every 5,000 cycles for a total of 25,000 cycles., Results: Total bone volume (BV) and trabecular bone volume fraction surrounding ML screws were significantly greater (p<.03) compared with those around MS screws and LM screws. The maximum insertional torque for ML screws were greater (p=.06) than LM and significantly greater (p<.02) than MS screws. The number of cycles to failure for the ML screw was significantly greater (p<.04) than that for the LM and the MS screws. Total BV (R 2 ≤46.2%, p<.03) and the maximum insertional torque (R 2 ≤59.6%, p<.03) provided better correlations to screw loosening compared with all the other bone quality parameters., Conclusions: Our findings indicate that bone quality in the vertebral body varied spatially depending on the orientation and the insertion location of the IFC screw. These alterations in local bone quality significantly affected the screw's ability to fixate to bone. These variations in bone quality may be assessed intraoperatively using screw insertional torque measurements. By understanding available bone purchase at the bone-implant interface, the appropriate implant design can be selected to maximize the fixation strength., (Published by Elsevier Inc.)

OBJECTIVE Lumbar cages with integrated fixation screws offer a low-profile alternative to a standard cage with anterior supplemental fixation. However, the mechanical stability of integrated fixation cages (IFCs) compared with a cage with anterior plate fixation under fatigue loading has not been investigated. The purpose of this study was to compare the biomechanical stability of a screw-based IFC with a standard cage coupled with that of an anterior plate under fatigue loading. METHODS Eighteen functional spinal units were implanted with either a 4-screw IFC or an anterior plate and cage (AP+C) without integrated fixation. Flexibility testing was conducted in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) on intact spines, immediately after device implantation, and post-fatigue up to 20,000 cycles of FE loading. Stability parameters such as range of motion (ROM) and lax zone (LZ) for each loading mode were compared between the 2 constructs at multiple stages of testing. In addition, construct loosening was quantified by subtracting post-instrumentation ROM from post-fatigue ROM. RESULTS IFC and AP+C configurations exhibited similar stability (ROM and LZ) at every stage of testing in FE (p ≥ 0.33) and LB (p ≥ 0.23) motions. In AR, however, IFCs had decreased ROM compared with AP+C constructs at pre-fatigue (p = 0.07) and at all post-fatigue time points (p ≤ 0.05). LZ followed a trend similar to that of ROM in AR. ROM increased toward intact motion during fatigue cycling for AP+C and IFC implants. IFC specimens remained significantly (p < 0.01) more rigid than specimens in the intact condition during fatigue for each loading mode, whereas AP+C construct motion did not differ significantly (p ≥ 0.37) in FE and LB and was significantly greater (p < 0.01) in AR motion compared with intact specimens after fatigue. Weak to moderate correlations (R 2 ≤ 56%) were observed between T-scores and construct loosening, with lower T-scores leading to decreased stability after fatigue testing. CONCLUSIONS These data indicate that a 4-screw IFC design provides fixation similar to that provided by an AP+C construct in FE and LB during fatigue testing and better stability in AR motion.

Study Design  Retrospective review. Objective  To compare clinical outcomes after transforaminal lumbar interbody fusion (TLIF) in patients with and patients without osteoporosis. Methods  We reviewed all patients with 6-month postoperative radiographs and computed tomography (CT) scans for evaluation of the interbody cage. CT Hounsfield unit (HU) measurements of the instrumented vertebral body were used to determine whether patients had osteoporosis. Radiographs and CT scans were evaluated for evidence of implant subsidence, migration, interbody fusion, iatrogenic fracture, or loosening of posterior pedicle screw fixation. Medical records were reviewed for persistence of symptoms or recurrence of symptoms. Results  The final data analysis included 18 (20.5%) patients with osteoporosis and 70 (79.5%) patients without osteoporosis. Males comprised 50% of patients with osteoporosis, and 64.3% of patients without osteoporosis. The mean age was significantly higher in the osteoporotic group (65.2 years) versus the nonosteoporotic group (56.9 years; p  < 0.0001). We found significantly higher rates of subsidence (72.2 versus 45.7%, p  = 0.05) and iatrogenic fractures (16.7% versus 1.4%, p  = 0.03) in the osteoporotic group. In addition, the osteoporotic group had significantly higher radiographic complication rates compared with the nonosteoporotic group (77.8 versus 48.6%, p  = 0.03). There was no difference between groups for revision surgery (16.6 versus 14.3%, p  = 0.78) or postoperative symptoms (44.4% versus 50.0%, p  = 0.69). Conclusions  Our data demonstrated significantly increased rates of cage subsidence, iatrogenic fracture, and overall radiographic complications in patients with osteoporosis. However, these radiographic complications did not predispose patients with osteoporosis to an increased risk of surgical revision or worse clinical outcomes.

Study Design: Retrospective analysis., Objective: The aim of the study was to report the incidence of undiagnosed osteoporosis in patients undergoing lumbar spine fusion using computed tomography (CT) Hounsfield units (HU)., Summary of Background Data: We used a recent technique utilizing HU to estimate bone mineral density (BMD) of the lumbar spine and hypothesized that this technique would reveal a high percentage of undiagnosed osteoporotic patients undergoing transforaminal lumbar interbody fusion (TLIF)., Methods: We reviewed patients older than 50 years undergoing TLIF from a single-center and multiple surgeons. We determined the mean HU of L4 on axial CT. Average HU values for patients with diagnosed lumbar osteoporosis (DEXA BMD <0.75 g/cm) were compared to patients with osteopenia and normal BMD (between 0.75 and 0.9 g/cm and >0.9 g/cm, respectively). The percentage of patients with HU values consistent with osteoporosis, but without any formal evaluation, was also calculated., Results: Over 10 years, 143 patients older than 50 years underwent TLIF, and 128 had available perioperative lumbar CT scans. Men and Women comprised 60.2% and 39.8% of the population, respectively. Average age was 61.5 years (range: 50.0-83.5 years). Twenty-nine patients had both dual-energy X-ray absorptiometry and CT data available for analysis. There was a significant association with decreased HU in patients with lumbar BMD less than 0.75 g/cm (105.6 HU, 95% confidence interval [CI] 6.76) in comparison to patients with osteopenia (146.0 HU, 95% CI 4.09) and with normal BMD (165.9, 95% CI 21.35). Ten men (7.8%) and 15 women (11.7%) had HU values consistent with osteoporosis. Sixty-four percent of patients with osteoporotic HU values had never been formally evaluated for the disease., Conclusion: HU may be an alternative to screening preoperative dual-energy X-ray absorptiometry scan and can minimize costs and resource utilization. We found a large proportion of patients older than 50 years undergoing TLIF had HU levels consistent with undiagnosed osteoporosis of the lumbar spine., Level of Evidence: 4.

Background Context: Numerous integrated fixation cages (IFCs) have recently been introduced to the market with "zero-profile" designs that incorporate screw fixation through the vertebral endplate. It is unclear whether differences in bone quality and quantity in this insertion location may affect fixation compared with screws used in traditional anterior plate (AP) fixation. Moreover, endplate preparation for IFC implantation may affect fixation strength., Purpose: This study aimed to compare pullout strength of screws used in IFCs with screws used for AP implantations., Study Design: A biomechanical cadaveric study., Methods: T12 and L1 vertebrae from 13 human cadaver spines were prepared for pullout testing. End plates in T12 vertebrae were scraped according to surgical practice for fusion procedures. Conversely, endplates in L1 vertebrae were kept intact (unscraped). Integrated fixation cage screws were implanted at a 45° angle into the endplate and AP screws were implanted horizontally into the same vertebral body. Pullout testing was performed on all screws, and peak pullout force (PPF) and work were compared between groups to determine fixation strength. In addition, micro-CT imaging was used to assess bone quantity and quality parameters such as trabecular bone volume fraction, endplate and anterior cortex thickness at screw insertion location, endplate mineralization, and anterior cortex mineralization., Results: Peak pullout force for IFC screws (176±68 N) with scraped endplates was similar (p=.26) to AP screws (192±84 N). However, PPF for IFC screws (231±75 N) with unscraped endplates was significantly greater (p<.01) than AP screws (176±50 N). Peak pullout force for IFC screws with scraped endplates was significantly lower (p=.03) than IFC screws with unscraped endplates. Scraped endplates group (0.17±0.05 mm) were thinner (p=.05) than unscraped endplates (0.21±0.06 mm) by approximately 40 µ on average., Conclusions: These data indicate that IFC and AP screws exhibited similar fixation behavior when the endplate is prepared according to common surgical practices. However, endplate scraping reduces endplate thickness by 20% on average, resulting in a decrease in fixation strength when compared with the unscraped endplates and provides bounds for IFC screw fixation strength., (Published by Elsevier Inc.)