The Ultrasonic Bone Scalpel does not Outperform the High-Speed Drill: A Single Academic Experience.

BACKGROUND: Spinal decompression and osteotomies are conventionally performed using high-speed drills (HSDs) and rongeurs. The ultrasonic bone scalpel (UBS) is a tissue-specific osteotome that preferentially cuts bone while sparing the surrounding soft tissues. There is ongoing investigation into its ability to optimize peri- and postoperative outcomes in spine surgery. The purpose of this study was to compare the intraoperative metrics and complications during a transition period from HSD to UBS. METHODS: A single-institution, single-surgeon retrospective analysis was conducted of patients undergoing spine surgery from January 2020 to December 2021. Statistical analyses were performed to detect associations between the surgical technique and outcomes of interest. A P value < 0.05 was considered statistically significant. RESULTS: A total of 193 patients met the inclusion criteria (HSD, n = 100; UBS, n = 93). Multivariate logistic regression revealed similar durotomy (P = 0.10), nerve injury (P = 0.20), and reoperation (P = 0.68) rates. Although the estimated blood loss (EBL) and length of stay were similar, the operative time was significantly longer with the UBS (192.81 vs. 204.72 minutes; P = 0.03). Each subsequent surgery using the UBS revealed a 3.1% decrease in the probability of nerve injury (P = 0.026) but had no significant effects on the operative time, EBL, or probability of durotomy or reoperation. CONCLUSIONS: The UBS achieves outcomes on par with conventional tools, with a trend toward a lower incidence of neurologic injury. The expected reductions in EBL and durotomy were not realized in our cohort, perhaps because of a high proportion of revision surgeries, although these might be dependent on surgeon familiarity, among other operative factors. Future prospective studies are needed to validate our results and further refine the optimal application of this device in spine surgery.

Sugammadex and blood loss during cervical spine fusion surgery.

Background and Aims: Sugammadex (SUG) has been associated with changes in coagulation studies. Most reports have concluded a lack of clinical significance based on surgical blood loss with SUG use at the end of surgery. Previous reports have not measured its use intraoperatively during ongoing blood loss. Our hypothesis was that the use of SUG intraoperatively may increase bleeding. Material and Methods: This was a single site retrospective study. Inclusion criteria were patients undergoing a primary posterior cervical spine fusion, aged over 18 years, between July 2015 and June 2021. The primary outcomes compared were intraoperative estimated blood loss (EBL) and postoperative drain output (PDO) between patients receiving SUG, neostigmine (NEO) and no NMB reversal agent. The objective was to determine if there was a difference in primary endpoints between patients administered SUG, NEO or no paralytic reversal agent. Primary endpoints were compared using analysis of variance with a P value of 0.05 used to determine statistical significance. Groups were compared using the Chi-squared test, rank sum or student's t test. A logistic regression model was constructed to account for differences between the groups. Results: There was no difference in median EBL or PDO between groups. The use of SUG was not associated with an increase in odds for >500 milliliters (ml) of EBL. Increasing duration of surgery and chronic kidney disease were both associated with an increased risk for EBL >500 ml. Conclusion: Intraoperative use of SUG was not associated with increased bleeding. Any coagulation laboratory abnormalities previously noted did not appear to have an associated clinical significance.

Comparison of Perioperative and Long-term Outcomes Following PEEK and Autologous Cranioplasty: A Single Institution Experience and Review of the Literature.

OBJECTIVE: Three-dimensionally (3D) printed polyether-ether-ketone (PEEK) implants are a relatively novel option for cranioplasty that have recently gained popularity. However, there is ongoing debate with respect to material efficacy and safety compared to autologous bone grafts. The purpose of this study was to offer our institution's experience and add to the growing body of literature. METHODS: A single-institution retrospective analysis of patients undergoing cranioplasties between 2016 and 2021. Patients were divided into PEEK and autologous cranioplasty cohorts. Parameters of interest included patient demographics as well as perioperative (<3 months postoperative) and long-term outcomes (>3 months postoperative). A P value < 0.05 was considered statistically significant. RESULTS: A total of 31 patients met inclusion criteria (PEEK: 15, Autologous: 16). Mean age of total cohort was 48.9 years (range 19-82 years). Modified Frailty Index (mFI) revealed greater rate of comorbidities among the Autologous group (P = 0.073), which was accounted for in statistical analyses. Multiple logistic regression model revealed significantly higher rate of surgical site infection in the Autologous cohort (31.3% vs. 0%, P = 0.011). Minor complications were similar between groups, while the Autologous group experienced significantly more major postoperative complications (50%) versus PEEK (13.3%) (P = 0.0291). Otherwise perioperative and long term complication profiles were similar between groups. Additionally, generalized linear model demonstrated both cohorts had similar mean hospital length of stay (LoS) (Autologous: 16.1 vs. PEEK: 10.7 days). CONCLUSIONS: PEEK cranioplasty implants may offer more favorable perioperative complication profiles with similar long-term complication rates and hospital LoS compared to autologous bone implants. Future studies are warranted to confirm our findings in larger series, and further examine the utility of PEEK in cranioplasty.

An Unusual Case of Neurenteric Cyst in a Patient with Split Cord Malformation.

Neurenteric cyst in a split cord malformation is a rare finding. We report an adult female becoming acutely symptomatic secondary to an expanding neurenteric cyst, though previous imaging had demonstrated stability. We discuss our workup and management with surgical resection and possible etiologies of her acute decline.

Impact of extent of resection and adjuvant therapy in diffuse gliomas of the spine.

BACKGROUND CONTENT: Diffuse gliomas of the spine (DGS)-consisting of intradural intramedullary glioblastoma, astrocytoma, and oligodendroglioma-are exceedingly rare tumors that account for about 2% of primary spinal cord tumors. Much is unknown about their optimal treatment regimen due to a relative lack of clinical outcome data. PURPOSE: To provide an updated analysis on treatment and outcomes in DGS. STUDY DESIGN/SETTING: Observational cohort study using The National Cancer Database (NCDB), a multicenter prospectively collected oncology outcomes database. A systematic literature review was also performed to compare the resulting data to previous series. PATIENT SAMPLE: Patients with histologically confirmed DGS from 2004 to 2018. OUTCOME MEASURES: Long-term overall survival and short-term 30/90-day postsurgical mortality, 30-day readmission, and prolonged hospital length of stay. METHODS: Impact of extent of resection and adjuvant therapy on overall survival was evaluated using Kaplan-Meier estimates and multivariable Cox proportional hazards regression. Univariate and multivariate logistic regression was used to analyze covariables and their prognostic impact on short-term surgical outcomes. RESULTS: Of the 747 cases that met inclusion criteria, there were 439 astrocytomas, 14 oligodendrogliomas, and 208 glioblastomas. Sixty percent (n=442) of patients received radiation, and 45% (n=324) received chemotherapy. Tumor histology significantly impacted survival; glioblastoma had the poorest survival (median survival time [MS]: 12.3 months), followed by astrocytoma (MS: 70.8 months) and oligodendroglioma (MS: 71.6 months) (p<.001). Gross total resection (GTR) independently conferred a survival benefit in patients with glioblastoma (hazard ratio [HR]: 0.194, p<0.001) and other WHO grade four tumors (HR: 0.223, p=.003). Adjuvant chemotherapy also improved survival in patients with glioblastoma (HR: 0.244, p=.007) and WHO grade four tumors (HR: 0.252, p<.001). Systematic literature review identified 14 prior studies with a combined DGS mortality rate of 1.3%, which is lower than the 4% real-world outcomes calculated from the NCDB. This difference may be explained by selection biases in previously published literature in which only centers with favorable outcomes publish their results. CONCLUSIONS: There remains a paucity of data regarding treatment paradigms and outcomes for DGS. Our analysis, the largest to date, demonstrates that GTR and adjuvant therapy independently improve survival for certain high-grade subgroups of DGS. This best-available data informs optimal management for such patients.

Practical Use of Augmented Reality Modeling to Guide Revision Spine Surgery: An Illustrative Case of Hardware Failure and Overriding Spondyloptosis.

BACKGROUND AND IMPORTANCE: Augmented reality (AR) is a novel technology with broadening applications to neurosurgery. In deformity spine surgery, it has been primarily directed to the more precise placement of pedicle screws. However, AR may also be used to generate high fidelity three-dimensional (3D) spine models for cases of advanced deformity with existing instrumentation. We present a case in which an AR-generated 3D model was used to facilitate and expedite the removal of embedded instrumentation and guide the reduction of an overriding spondyloptotic deformity. CLINICAL PRESENTATION: A young adult with a remote history of a motor vehicle accident treated with long-segment posterior spinal stabilization presented with increasing back pain and difficulty sitting upright in a wheelchair. Imaging revealed pseudoarthrosis with multiple rod fractures resulting in an overriding spondyloptosis of T6 on T9. An AR-generated 3D model was useful in the intraoperative localization of rod breaks and other extensively embedded instrumentation. Real-time model thresholding expedited the safe explanation of the defunct system and correction of the spondyloptosis deformity. CONCLUSION: An AR-generated 3D model proved instrumental in a revision case of hardware failure and high-grade spinal deformity.

Comparison of One-day Combined versus Staged Anterior and Posterior Cervical Decompression, Fixation, and Fusion.

AIM: To compare the perioperative outcomes between single-day combined or separate-day staged surgeries for cervical spinal stenosis. MATERIAL AND METHODS: A retrospective cohort analysis was conducted on consecutive patients admitted at a single institution between July 2015 and April 2019, who underwent either single-day combined or separate-day staged surgeries during the same hospitalization period. Demographics, comorbidities, hospital length of stay, and perioperative complications were compared between the patient groups. RESULTS: Eighty patients (combined surgery: n=68, staged surgery: n=12) were included. Dysphagia was the most commonly reported postoperative complication in 44/80 patients (55%). There were no significant differences in the baseline demographics between the two groups. The staged surgery group had significantly longer total time in the operating room (7.2 vs. 8.5 hours, p=0.002), longer duration of general anesthesia (6.7 vs. 7.6 hours, p=0.006), and higher incidence of postoperative delirium (12.1% vs. 50% p=0.005) than the combined surgery group. The mean hospital length of stay was similar in the two groups (combined surgery: 7.5 days vs. staged surgery: 15.1 days, p=0.09). CONCLUSION: Staged anterior and posterior cervical decompressions, stabilizations, and fusions are associated with longer total time in the operating room, longer duration of general anesthesia, and higher incidence of postoperative delirium than combined surgeries.

Return-to-active-duty rates after anterior cervical spine surgery in military pilots.

OBJECTIVESymptomatic cervical spondylosis with or without radiculopathy can ground an active-duty military pilot if left untreated. Surgically treated cervical spondylosis may be a waiverable condition and allow return to flying status, but a waiver is based on expert opinion and not on recent published data. Previous studies on rates of return to active duty status following anterior cervical spine surgery have not differentiated these rates among military specialty occupations. No studies to date have documented the successful return of US military active-duty pilots who have undergone anterior cervical spine surgery with cervical fusion, disc replacement, or a combination of the two. The aim of this study was to identify the rate of return to an active duty flight status among US military pilots who had undergone anterior cervical discectomy and fusion (ACDF) or total disc replacement (TDR) for symptomatic cervical spondylosis.METHODSThe authors performed a single-center retrospective review of all active duty pilots who had undergone either ACDF or TDR at a military hospital between January 2010 and June 2017. Descriptive statistics were calculated for both groups to evaluate demographics with specific attention to preoperative flight stats, days to recommended clearance by neurosurgery, and days to return to active duty flight status.RESULTSAuthors identified a total of 812 cases of anterior cervical surgery performed between January 1, 2010, and June 1, 2017, among active duty, reserves, dependents, and Department of Defense/Veterans Affairs patients. There were 581 ACDFs and 231 TDRs. After screening for military occupation and active duty status, there were a total of 22 active duty pilots, among whom were 4 ACDFs, 17 TDRs, and 2 hybrid constructs. One patient required a second surgery. Six (27.3%) of the 22 pilots were nearing the end of their career and electively retired within a year of surgery. Of the remaining 16 pilots, 11 (68.8%) returned to active duty flying status. The average time to be released by the neurosurgeon was 128 days, and the time to return to flying was 287 days. The average follow-up period was 12.3 months.CONCLUSIONSAdhering to military service-specific waiver guidelines, military pilots may return to active duty flight status after undergoing ACDF or TDR for symptomatic cervical spondylosis.

Cost-effectiveness of adult spinal deformity surgery in a military healthcare system.

OBJECTIVEAdult spinal deformity surgery is an effective way of treating pain and disability, but little research has been done to evaluate the costs associated with changes in health outcome measures. This study determined the change in quality-adjusted life years (QALYs) and the cost per QALY in patients undergoing spinal deformity surgery in the unique environment of a military healthcare system (MHS).METHODSPatients were enrolled between 2011 and 2017. Patients were eligible to participate if they were undergoing a thoracolumbar spinal fusion spanning more than 6 levels to treat an underlying deformity. Patients completed the 36-Item Short Form Health Survey (SF-36) prior to surgery and 6 and 12 months after surgery. The authors used paired t-tests to compare SF-36 Physical Component Summary (PCS) scores between baseline and postsurgery. To estimate the cost per QALY of complex spine surgery in this population, the authors extended the change in health-related quality of life (HRQOL) between baseline and follow-up over 5 years. Data on the cost of surgery were obtained from the MHS and include all facility and physician costs.RESULTSHRQOL and surgical data were available for 49 of 91 eligible patients. Thirty-one patients met additional criteria allowing for cost-effectiveness analysis. Over 12 months, patients demonstrated significant improvement (p < 0.01) in SF-36 PCS scores. A majority of patients met the minimum clinically important difference (MCID; 83.7%) and substantive clinical benefit threshold (SCBT; 83.7%). The average change in QALY was an increase of 0.08. Extended across 5 years, including the 3.5% discounting per year, study participants increased their QALYs by 0.39, resulting in an average cost per QALY of $181,649.20. Nineteen percent of patients met the < $100,000/QALY threshold with half of the patients meeting the < $100,000/QALY mark by 10 years. A sensitivity analysis showed that patients who scored below 60 on their preoperative SF-36 PCS had an average increase in QALYs of 0.10 per year or 0.47 over 5 years.CONCLUSIONSWith a 5-year extended analysis, patients who receive spinal deformity surgery in the MHS increased their QALYs by 0.39, with 19% of patients meeting the $100,000/QALY threshold. The majority of patients met the threshold for MCID and SCBT at 1 year postoperatively. Consideration of preoperative functional status (SF-36 PCS score < 60) may be an important factor in determining which patients benefit the most from spinal deformity surgery.

Cervical and Thoracolumbar Spine Injury Evaluation, Transport, and Surgery in the Deployed Setting.

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.

Performance of Cervical Arthroplasty at a Pseudarthrosed Level of a MultiLevel Anterior Cervical Discectomy and Fusion: Case Report.

OBJECTIVE: To present a conversion from an anterior cervical discectomy and fusion (ACDF) to cervical arthroplasty in a 40-year-old, active duty member and perform a review of the literature. METHODS: A helicopter pilot in the U.S. Army underwent a three-level ACDF in 2010 at a nonmilitary institution for symptoms of bilateral upper-extremity radiculopathy. His symptoms resolved; however, per regulations, he was grounded. The patient recently presented at our clinic for evaluation of axial neck and intrascapular pain with radiographic evaluation revealing pseudarthrosis at C6-7 with segmental motion without facet joint degeneration. Surgery was performed to remove the existing allograft and replace it with an artificial disc, thus restoring a motion segment. RESULTS: Postoperative imaging reveals appropriate placement of the artificial disc and range of motion at C6-7 with the patient reporting improvement in neck pain. He has since been granted a waiver to return to active flight status. CONCLUSIONS: Revision of ACDF to arthroplasty is an exceedingly rare procedure with only two cases reported in the literature. Here, the authors demonstrate use of the procedure for a military career-specific application. When facet joint degeneration or ankylosis is absent, restoration of motion can successfully, and safely, be achieved.

Results of the AANS membership survey of adult spinal deformity knowledge: impact of training, practice experience, and assessment of potential areas for improved education: Clinical article.

OBJECT: Adult spinal deformity (ASD) surgery is increasing in the spinal neurosurgeon's practice. METHODS: A survey of neurosurgeon AANS membership assessed the deformity knowledge base and impact of current training, education, and practice experience to identify opportunities for improved education. Eleven questions developed and agreed upon by experienced spinal deformity surgeons tested ASD knowledge and were subgrouped into 5 categories: (1) radiology/spinopelvic alignment, (2) health-related quality of life, (3) surgical indications, (4) operative technique, and (5) clinical evaluation. Chi-square analysis was used to compare differences based on participant demographic characteristics (years of practice, spinal surgery fellowship training, percentage of practice comprising spinal surgery). RESULTS: Responses were received from 1456 neurosurgeons. Of these respondents, 57% had practiced less than 10 years, 20% had completed a spine fellowship, and 32% devoted more than 75% of their practice to spine. The overall correct answer percentage was 42%. Radiology/spinal pelvic alignment questions had the lowest percentage of correct answers (38%), while clinical evaluation and surgical indications questions had the highest percentage (44%). More than 10 years in practice, completion of a spine fellowship, and more than 75% spine practice were associated with greater overall percentage correct (p < 0.001). More than 10 years in practice was significantly associated with increased percentage of correct answers in 4 of 5 categories. Spine fellowship and more than 75% spine practice were significantly associated with increased percentage correct in all categories. Interestingly, the highest error was seen in risk for postoperative coronal imbalance, with a very low rate of correct responses (15%) and not significantly improved with fellowship (18%, p = 0.08). CONCLUSIONS: The results of this survey suggest that ASD knowledge could be improved in neurosurgery. Knowledge may be augmented with neurosurgical experience, spinal surgery fellowships, and spinal specialization. Neurosurgical education should particularly focus on radiology/spinal pelvic alignment, especially pelvic obliquity and coronal imbalance and operative techniques for ASD.

A team approach to anterior lumbar spine surgery in the military.

We report a five year military experience with anterior retroperitoneal spine exposure combining vascular and neurosurgical spine teams. From August 2005 through April 2010 (56 months), hospital records from a single institution were retrospectively reviewed. Complications, estimated blood loss, transfusions, operative time and length of stay were documented. Eighty-four patients with lumbar spondylosis underwent primary (63, 75%) or secondary exposure (21, 25%) of a single- (66, 79%) or multilevel disc space (18, 21%). Median operative time and estimated blood loss were 127 minutes (range, 30-331 minutes) and 350 mL (range, 0-2940 mL). The overall complication rate was 23.8%. Postoperative complications included six blood transfusions (7%), three patients with retrograde ejaculation (3.57%) or surgical site infection; two with a prolonged ileus (2.38%) or ventral hernia and one each with a bowel obstruction (1, 1.19%), deep venous thrombosis or lymphocele. All-cause mortality was 1%. In conclusion, a team approach can minimize complications while offering the technical benefits and durability of an anterior approach to the lumbar spine.

Adjacent vertebral body osteolysis with bone morphogenetic protein use in transforaminal lumbar interbody fusion.

BACKGROUND CONTEXT: Recent studies have demonstrated cases of adjacent vertebral body osteolysis when assessing the effect of bone morphogenetic protein (BMP) on fusion rates. However, no study to date has evaluated the course of osteolysis at different periods. PURPOSE: To determine the incidence and resolution of osteolysis associated with BMP used in transforaminal lumbar interbody fusions (TLIF). STUDY DESIGN: Retrospective review. PATIENT SAMPLE: All TLIF cases using BMP performed at one institution with routine postoperative computed tomography (CT) scans at defined intervals. OUTCOME MEASURES: Area of osteolysis and fusion as determined by CT scan. METHODS: We performed a retrospective analysis of all patients at our facility who underwent TLIF with BMP. Included were all patients who had obtained a CT scan within 48 hours of surgery, 3 to 6 months postoperatively, and 1 to 2 years postoperatively. Areas of osteolysis were defined as lucency within the vertebral body communicating with the interbody spacer that was not present on the immediately postoperative CT scan. Areas of osteolysis were measured in all three planes and the volume used for comparison of the 3 to 6 months CT scans with the greater than 1 year CT scan. RESULTS: Twenty-three patients who underwent TLIF with BMP had obtained CT scans at all time periods required for evaluation. Seventy-eight vertebral bodies/end plates were assessed for osteolysis (39 levels). The incidence of osteolysis 3 to 6 months postoperatively in the adjacent vertebral bodies was 54% compared with 41% at 1 to 2 years. The mean volume of osteolysis was at 0.216 cm(3) at 1 to 2 years compared with 0.306 cm(3) at 3 to 6 months (p=.082). The area/rate of osteolysis did not appear to significantly affect the rate of fusion or final outcome with an overall union rate of 83%. CONCLUSIONS: The rate of osteolysis decreased at 1 year compared with 3 to 6 months, but only 24% of the vertebral bodies with evidence of osteolysis at 3 to 6 months completely resolved by 1 year.

Cervical hybrid arthroplasty with 2 unique fusion techniques.

OBJECTIVE: Multilevel cervical arthroplasty achieved using the Prestige ST disc can be challenging and often unworkable. An alternative to this system is a hybrid technique composed of alternating total disc replacements (TDRs) and fusions. In the present study, the authors review the safety and radiological outcomes of cervical hybrid arthroplasty in which the Prestige ST disc is used in conjunction with 2 unique fusion techniques. METHODS: After obtaining institutional review board approval, the authors completed a retrospective review of all hybrid cervical constructs in which the Prestige ST disc was used between August 2007 and November 2009 at the Walter Reed Army Medical Center. A Prestige ST total disc replacement was performed in 119 patients. Thirty-one patients received a hybrid construct defined as a TDR and fusion (TDR-anterior cervical decompression and fusion [ACDF]) or as 2 TDRs separated by a fusion (TDR-ACDF-TDR). A resorbable plate and graft system (Mystique) or stand-alone interbody spacer (Prevail) was implanted at the fusion levels. Plain radiographs were compared and evaluated for cervical lordosis, range of motion, implant complications, development of adjacent-level disease, and pseudarthrosis. In addition, charts were reviewed for clinical complications related to the index surgery. RESULTS: Thirty-one patients (18 men and 13 women; mean age 50 years, range 32-74 years) received a hybrid construct. All patients were diagnosed with radiculopathy and/or myelopathy. Twenty-four patients received a 2-level and 7 a 3-level hybrid construct. In 2 patients in whom a 2-level hybrid construct was implanted, a noncontiguous TDR was also performed. The mean clinical and radiological follow-up duration was 18 months. There was no significant difference in preoperative (19.3° ± 13.3°) and postoperative (19.7° ± 10.5°) cervical lordosis (p = 0.48), but there was a significant decrease in range in motion (from 50.0° ± 11.8° to 38.9° ± 12.7°) (p = 0.003). There were no instances of screw backout, implant dislodgement, progressive kyphosis, formation of heterotopic bone, pseudarthrosis, or symptomatic adjacent-level disease. Seven patients had dysphasia and 1 patient had vocal cord paralysis at 6 weeks. By 3 months, both the dysphasia and the vocal cord paralysis were resolved in all patients. CONCLUSIONS: Hybrid cervical arthroplasty involving the placement of a Prestige ST disc and either the Mystique resorbable plate or Prevail stand-alone interbody device is a safe and effective alternative to multilevel fusion for the management of cervical radiculopathy and myelopathy.

Does the Wilson frame assist with optimizing surgical exposure for minimally invasive lumbar fusions?

OBJECT: Minimally invasive lumbar spine surgery has dramatically evolved over the last decade. Minimally invasive techniques and transforaminal lumbar interbody fusion (TLIF) often require a steep learning curve. Surgical techniques require pre-positioning the patient in maximal kyphosis to optimize visualization of the disc space and prevent unnecessary retraction of neural structures. The authors describe their experience in validating the surgical technique recommendation of Wilson frame-induced kyphosis. METHODS: Over the past 6 months, data obtained in 20 consecutive patients (40 total levels) undergoing minimally invasive TLIF were reviewed. In each patient, preincision intraoperative radiographs were reviewed at L4-5 and L5-S1 with the patient on a Wilson frame in maximal lordosis and then in maximal kyphosis. The change in disc space angle at L4-5 and L5-S1 after changing from maximal lordosis to maximal kyphosis was reviewed. Descriptive statistics were calculated for sagittal plane angular measures at L4-5 and L5-S1 in lordosis and kyphosis, including absolute differences and percentage of change between positions. Inferential statistics were calculated using paired t-tests with alpha= 0.05. RESULTS: Twenty patients underwent single- or multilevel minimally invasive TLIF. Inducing kyphosis with the Wilson frame aided in optimizing exposure and decreasing the need for neural structure retraction. Both L4-5 and L5-S1 showed statistically significant (p < 0.001) and clinically meaningful changes with increased segmental flexion in the kyphotic position. At L4-5 the mean increase in flexion was 4.5 degrees (95% CI 2.9-6.0 degrees), representing an average 47% change. The mean increase in flexion at L5-S1 was 3.2 degrees (95% CI 2.3-4.2 degrees), representing an average 20.8% change. In lordosis the mean angle at L4-5 was 10.6 +/- 4.4 degrees and at L5-S1 was 17 +/- 7.0 degrees. In kyphosis the mean angle at L4-5 was 6.1 +/- 4.5 degrees and at L5-S1 was 13.8 +/- 6.5 degrees. Additionally, there was a statistically significant difference (p < 0.05) in percentage of change between the 2 levels, with L4-5 showing a greater change (27% more flexion) between positions, but the absolute mean difference between the levels was small (1.3 degrees). CONCLUSIONS: Minimally invasive TLIF is challenging and requires a significant learning curve. The recommended surgical technique of inducing kyphosis with the Wilson frame prior to incision significantly optimizes exposure. The authors' experience demonstrates that this technique is essential when performing minimally invasive lumbar spinal fusions.

Resident learning curve for minimal-access transforaminal lumbar interbody fusion in a military training program.

OBJECT: Minimal-access transforaminal lumbar interbody fusion (TLIF) has gained popularity as a method of achieving interbody fusion via a posterior-only approach with the aim of minimizing injury to adjacent tissue. While many studies have reported successful outcomes, questions remain regarding the potential learning curve for successfully completing this procedure. The goal of this study, based on a single resident's experience at the only Accreditation Council for Graduate Medical Education-approved neurosurgical training center in the US military, was to determine if there is in fact a significant learning curve in performing a minimal-access TLIF. METHODS: The authors retrospectively reviewed all minimal-access TLIFs performed by a single neurosurgical resident between July 2006 and January 2008. Minimal-access TLIFs were performed using a tubular retractor inserted via a muscle-dilating exposure to limit approach-related morbidity. The accuracy of screw placement and operative times were assessed. RESULTS: A single resident/attending team performed 28 minimal-access TLIF procedures. In total, 65 screws were placed at L-2 (1 screw), L-3 (2 screws), L-4 (18 screws), L-5 (27 screws), and S-1 (17 screws) from the resident's perspective. Postoperative CTs were reviewed to determine the accuracy of screw placement. An accuracy of 95.4% (62 of 65) properly placed screws was noted on postoperative imaging. Two screws (at L-5 in the patient in Case 17 and at S-1 in the patient in Case 9) were lateral, and no revision was needed. One screw (at L-4 in Case 24) was 1 mm medial without symptoms or the need for revision. In evaluating the operative times, 2 deformity cases (Grade III spondylolisthesis) were excluded. The average operating time per level in the remaining 26 cases was 113.25 minutes. The average time per level for the first 13 cases was 121.2 minutes; the amount of time decreased to 105.3 minutes for the second group of 13 cases (p = 0.25). CONCLUSIONS: In summary, minimal-access TLIF can be safely performed in a training environment without a significant complication rate due to the expected learning curve.

Cranioplasty complications following wartime decompressive craniectomy.

OBJECT: In support of Operation Iraqi Freedom (OIF) and Operation Enduring Freedom-Afghanistan (OEF-A), military neurosurgeons in the combat theater are faced with the daunting task of stabilizing patients in such a way as to prevent irreversible neurological injury from cerebral edema while simultaneously allowing for prolonged transport stateside (5000-7000 miles). It is in this setting that decompressive craniectomy has become a mainstay of far-forward neurosurgical management of traumatic brain injury (TBI). As such, institutional experience with cranioplasty at the Walter Reed Army Medical Center (WRAMC) and the National Naval Medical Center (NNMC) has expanded concomitantly. Battlefield blast explosions create cavitary injury zones that often extend beyond the border of the exposed surface wound, and this situation has created unique reconstruction challenges not often seen in civilian TBI. The loss of both soft-tissue and skull base support along with the need for cranial vault reconstruction requires a multidisciplinary approach involving neurosurgery, plastics, oral-maxillofacial surgery, and ophthalmology. With this situation in mind, the authors of this paper endeavored to review the cranial reconstruction complications encountered in these combat-related injuries. METHODS: A retrospective database review was conducted for all soldiers injured in OIF and OEF-A who had undergone decompressive craniectomy with subsequent cranioplasty between April 2002 and October 2008 at the WRAMC and NNMC. During this time, both facilities received a total of 408 OIF/OEF-A patients with severe head injuries; 188 of these patients underwent decompressive craniectomies in the theater before transfer to the US. Criteria for inclusion in this study consisted of either a closed or a penetrating head injury sustained in combat operations, resulting in the performance of a decompressive craniectomy and subsequent cranioplasty at either the WRAMC or NNMC. Excluded from the study were patients for whom primary demographic data could not be verified. Demographic data, indications for craniectomy, as well as preoperative, intraoperative, and postoperative parameters following cranioplasty, were recorded. Perioperative and postoperative complications were also recorded. RESULTS: One hundred eight patients (male/female ratio 107:1) met the inclusion criteria for this study, 93 with a penetrating head injury and 15 with a closed head injury. Explosive blast injury was the predominant mechanism of injury, occurring in 72 patients (67%). The average time that elapsed between injury and cranioplasty was 190 days (range 7-546 days). An overall complication rate of 24% was identified. The prevalence of perioperative infection (12%), seizure (7.4%), and extraaxial hematoma formation (7.4%) was noted. Twelve patients (11%) required prosthetic removal because of either extraaxial hematoma formation or infection. Eight of the 13 cases of infection involved cranioplasties performed between 90 and 270 days from the date of injury (p = 0.06). CONCLUSIONS: This study represents the largest to date in which cranioplasty and its complications have been evaluated in a trauma population that underwent decompressive craniectomy. The overall complication rate of 24% is consistent with rates reported in the literature (16-34%); however, the perioperative infection rate of 12% is higher than the rates reported in other studies. This difference is likely related to aspects of the initial injury pattern-such as skull base injury, orbitofacial fractures, sinus injuries, persistent fluid collection, and CSF leakage-which can predispose these patients to infection.

Can surgery improve neurological function in penetrating spinal injury? A review of the military and civilian literature and treatment recommendations for military neurosurgeons.

OBJECT: Penetrating spinal injury (PSI), although an infrequent injury in the civilian population, is not an infrequent injury in military conflicts. Throughout military history, the role of surgery in the treatment of PSI has been controversial. The US is currently involved in 2 military campaigns, the hallmark of both being the widespread use of various explosive devices. The authors reviewed the evidence for or against the use of decompressive laminectomy to treat PSI to provide a triservice (US Army, Navy, and Air Force) consensus and treatment recommendations for military neurosurgeons and spine surgeons. METHODS: A US National Library of Medicine PubMed database search that identified all literature dealing with acute management of PSI from military conflicts and civilian urban trauma centers in the post-Vietnam War period was undertaken. RESULTS: Nineteen retrospective case series (11 military and 8 civilian) met the study criteria. Eleven military articles covered a 20-year time span that included 782 patients who suffered either gunshot or blast-related projectile wounds. Four papers included sufficient data that analyzed the effectiveness of surgery compared with nonoperative management, 6 papers concluded that surgery was of no benefit, 2 papers indicated that surgery did have a role, and 3 papers made no comment. Eight civilian articles covered a 9-year time span that included 653 patients with spinal gunshot wounds. Two articles lacked any comparative data because of treatment bias. Two papers concluded that decompressive laminectomy had a beneficial role, 1 paper favored the removal of intracanal bullets between T-12 and L-4, and 5 papers indicated that surgery was of no benefit. CONCLUSIONS: Based on the authors' military and civilian PubMed literature search, most of the evidence suggests that decompressive laminectomy does not improve neurological function in patients with PSI. However, there are serious methodological shortcomings in both literature groups. For this and other reasons, neurosurgeons from the US Air Force, Army, and Navy collectively believe that decompression should still be considered for any patient with an incomplete neurological injury and continued spinal canal compromise, ideally within 24-48 hours of injury; the patient should be stabilized concurrently if it is believed that the spinal injury is unstable. The authors recognize the highly controversial nature of this topic and hope that this literature review and the proposed treatment recommendations will be a valuable resource for deployed neurosurgeons. Ultimately, the deployed neurosurgeon must make the final treatment decision based on his or her opinion of the literature, individual abilities, and facility resources available.