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OBJECTIVE There are few prior reports of acute pelvic instrumentation failure in spinal deformity surgery. The objective of this study was to determine if a previously identified mechanism and rate of pelvic fixation failure were present across multiple institutions, and to determine risk factors for these types of failures. METHODS Thirteen academic medical centers performed a retrospective review of 18 months of consecutive adult spinal fusions extending 3 or more levels, which included new pelvic screws at the time of surgery. Acute pelvic fixation failure was defined as occurring within 6 months of the index surgery and requiring surgical revision. RESULTS Failure occurred in 37 (5%) of 779 cases and consisted of either slippage of the rods or displacement of the set screws from the screw tulip head (17 cases), screw shaft fracture (9 cases), screw loosening (9 cases), and/or resultant kyphotic fracture of the sacrum (6 cases). Revision strategies involved new pelvic fixation and/or multiple rod constructs. Six patients (16%) who underwent revision with fewer than 4 rods to the pelvis sustained a second acute failure, but no secondary failures occurred when at least 4 rods were used. In the univariate analysis, the magnitude of surgical correction was higher in the failure cohort (higher preoperative T1-pelvic angle [T1PA], presence of a 3-column osteotomy; p < 0.05). Uncorrected postoperative deformity increased failure risk (pelvic incidence–lumbar lordosis mismatch > 10°, higher postoperative T1PA; p < 0.05). Use of pelvic screws less than 8.5 mm in diameter also increased the likelihood of failure (p < 0.05). In the multivariate analysis, a larger preoperative global deformity as measured by T1PA was associated with failure, male patients were more likely to experience failure than female patients, and there was a strong association with implant manufacturer (p < 0.05). Anterior column support with an L5–S1 interbody fusion was protective against failure (p < 0.05). CONCLUSIONS Acute catastrophic failures involved large-magnitude surgical corrections and likely resulted from high mechanical strain on the pelvic instrumentation. Patients with large corrections may benefit from anterior structural support placed at the most caudal motion segment and multiple rods connecting to more than 2 pelvic fixation points. If failure occurs, salvage with a minimum of 4 rods and 4 pelvic fixation points can be successful.

Rat spine fusion model.The present study aimed to determine whether administration of osteoprotegerin (OPG) in a rat model of spinal fusion increases bone volume, bone density, and decreases osteoclasts in the fusion mass.OPG is a soluble RANK-ligand inhibitor that blocks osteoclast differentiation and activation. This makes it a potential agent to control the remodeling process and enhance bone mass during spinal fusion.Forty-eight male Sprague-Dawley rats received a one-level spinal fusion of L4-L5 with bone allograft. Rats were then divided into four groups according to initiation of treatment: (1) saline on day 0 (saline), (2) OPG on day 0 (OPG D0), (3) OPG on day 10 (OPG D10), and (4) OPG on day 21 (OPG D21) postsurgery. After their initial injection, rats received weekly subcutaneous injections of OPG (10 mg/kg) and were euthanized six weeks postsurgery. MicroCT analysis of the fusion site and histological analysis of bone surface for quantification of osteoclast lining was performed.Increased bone volume in the fusion site and around the spinous process was seen in OPG D0 and OPG D10 when compared with saline. Mean trabecular thickness was greater in all groups receiving OPG compared with saline, with OPG D0 and OPG D10 having significantly greater mean trabecular thickness than OPG D21. All OPG groups had less bone surface lined with osteoclasts when compared with Saline, with OPG D0 and OPG D10 having fewer than OPG D21.This study indicates that OPG inhibited osteoclast bone resorption, which led to greater bone at the fusion site. Future studies investigating OPG on its own or in combination with an osteogenic factor to improve spinal fusion outcomes are warranted to further elucidate its potential therapeutic effect.

Study Design Review of current literature and authors experience. Objective Pre-operative planning is an integral part of complex spine surgery. With the advent of computer-assisted planning, multiple surgical plans can be evaluated utilizing alignment parameters, and the best plan for individual patients selected. However, the ability to evaluate and measure surgical correction goals intraoperatively are still limited. The use of patient-specific UNiD rods, created based on pre-operative plans, provided an initial tool for implementation of pre-operative plans in the operative setting. Methods A literature review for the use of patient-specific UNiD rods in thoracolumbar spine complex surgery was performed. The articles were selected and reviewed for the initial experience/outcomes of these techniques. Further, the initial experience of the authors at The University of Colorado is described. Results The use of UNiD patient-specific rods, in combination with pre-operative planning has been shown to provide a higher rate of patients with spinopelvic alignment parameters within currently accepted ranges. This includes improvement of sagittal vertical axis (SVA) < 50 mm and pelvic incidence (PI)–lumbar lordosis (LL) = ± 10°. Multiple authors have shown improvement in pelvic tilt to age adjusted values but note continued difficulties in obtaining correction goals. Conclusions The use of pre-operative planning software and UNiD patient-specific rods has been shown to improve surgeon’s ability to achieve spinopelvic alignment parameters, specifically SVA and PI-LL, along with other possible benefits. Further research is needed regarding long-term value of the technology.

To study factors causing postoperative change of PI after surgical correction of ASD and to assess the effect of this variability on postoperative PI-LL mismatch. PI is used as an individual constant to define lumbar lordosis (LL) correction goal (PI-LL 10°) associated with a |∆PI|> 6°, P = 0.05. Sacroiliac fixation diminished PI variability only during the first postoperative year. Preoperative variability and postoperative instability of PI diminish the applicability of the PI–LL

Intraoperative computed tomography scanning with O-arm and use of Stealth navigation can improve surgical outcomes in a variety of orthopedic subspecialties. In spine surgery, the accuracy, precision, and safety of pedicle screw and interbody implant placement has improved. This technology is now routinely used in percutaneous pedicle screw placement and minimally invasive sacroiliac joint fusion. Other applications include, but are not limited to, isthmic pars defect repair, lumbosacral pseudoarticulation resection in Bertolotti's syndrome, radiofrequency ablation, and en bloc tumor resection. Intraoperative navigation has numerous applications, and use of this technology should continue to evolve as the technology advances. [ Orthopedics . 2023;46(2):e89–e97.]

Background: Recent studies support the need for sagittal alignment restoration when performing lumbar degenerative spinal fusions. The development of patient-specific spine rods (PSSRs) may help maintain or improve sagittal alignment in these surgeries. Methods: A retrospective review was conducted for patients who underwent posterior spinal surgeries involving 4 or less levels. The preplanned PSSR radii of curvature (ROC) was compared with standard prebent rods with a ROC of 125 mm. All surgeries were performed at a single institution by 3 surgeons from September 2016 through October 2018. Data were then compared using a 2-tailed paired t test. PSSR had either 1 or 2 definitive ROCs. Results: For rods with 2 ROCs, the “cranial” curve was measured between the upper instrumented level and L4 or L5. The “caudal” curve was measured between L4 or L5 and the lower instrumented level. The PSSR with 1 ROC and the caudal portion of the rods with 2 ROCs were significantly smaller than the industry standard ROC. Conclusions: PSSR demonstrate more acute ROC than industry standard rods. In PSRs, the most lordosis occurs between L4-S1 and flattens out at the thoracolumbar junction, mimicking the normal distribution of lumbar lordosis. PSSRs could help achieve or maintain sagittal alignment and prevent the sequela of flat back syndrome.

Study design Retrospective case series. Objective To evaluate the short- and long-term treatment effect (TE) of spinopelvic parameters after surgical correction of adult spine deformity (ASD) utilizing preoperative planning and patient-specific spine rods (PSSRs), and to assess the correspondence between planned and real outcomes. Summary of background data PSSR have been used in ASD correction for the last decade. However, a TE and predictability of spinopelvic alignment at long-term follow-up has not been studied. Methods Inclusion criteria: male or female; age more than 20 years; correction of ASD with PSSR; 24-month follow-up (or revision surgery). Studied parameters: sagittal vertical axis; lumbar lordosis (LL); pelvic tilt (PT); sacral slope; pelvic incidence (PI); and PI-LL. The measurement error, TE (the differences between postoperative and preoperative values), standardized TE, and predictability of the studied parameters assessed. The variables included categorical (optimal/nonoptimal) and continuous obtained by direct measurements and weighted by individual optimal values. Statistical significance was set at P ≤ 0.05. Results Thirty-four patients were included: 56% women; the mean age, 63.4 (standard deviation, 12.7); at each follow-up: 32 at 1 to 3 months, 34 at 11 to 13, and 14 at 23 to 25 with 9 followed to the revision surgery. Strong or moderate TE was shown for sagittal vertical axis, LL, and PI-LL. The TE of PT and sacral slope was less significant and lower than planned. PI was not stable in 18%. The changes of continuous variables were more prominent and statistically significant then categorical. The mean values did not show significant differences between planned and postoperative outcomes except for PT. However, the individual deviations were substantial for all parameters. Significant predictability was shown only for LL and PI. Conclusion Use of PSSR showed strong and relatively stable TE in ASD during 2 postoperative years. However, improvement of the planning accuracy may contribute to further enhancement of the method's efficacy. Level of evidence 4.

As coronavirus disease 2019 (COVID-19) reached pandemic status, in-person orthopedic clinics across the United States were forced to close as many states adopted stay-at-home orders. Previously, the use of telemedicine in orthopedic practices was minimal for a variety of reasons, one being the inability to perform a physical examination in a specialty reliant on direct patient contact for diagnosis and treatment. A prospective cohort of 52 patients consented to participate in a novel virtual physical examination protocol during routine telemedicine visits at a large, tertiary orthopedic spine practice. Participants were asked to perform a series of carefully designed physical maneuvers using readily available household objects to allow their provider to better assess sensory and motor function in the tele-medicine setting. Patients were then asked to complete a short satisfaction survey. In total, 52 patients completed the physical examination and survey. Males and females were distributed evenly among the cohort at 50%. The mean age was 52.1±15.5 years. The average score for ease of understanding the examination (1=easiest, 5=hardest) was 1.1, while the average score for ease of performance was 1.5. Most participants (97.56%) felt their provider was better able to understand their condition using the virtual examination findings. This study highlights the utility of a virtual physical examination for assessment of spine patients in the telemedicine setting. Furthermore, this study illustrates the ease with which such an examination can be implemented and performed to improve patient evaluation and satisfaction. [ Orthopedics . 2022;45(1):e7–e10.]

Supplemental Digital Content is Available in the Text., Background: Chronic opioid use and polypharmacy are commonly seen in chronic pain patients presenting for spine procedures. Substance abuse and misuse have also been reported in this patient population. Negative perioperative effects have been found in patients exposed to chronic opioid, alcohol, and recreational substances. Toxicology screening testing (TST) in the perioperative period provides useful information for adequate preoperative optimization and perioperative planning. Methods: We designed a pilot study to understand this population's preoperative habits including accuracy of self-report and TST-detected prescribed and unprescribed medications and recreational substances. We compared the results of the TST to the self-reported medications using Spearman correlations. Results: Inconsistencies between TST and self-report were found in 88% of patients. Spearman correlation was 0.509 between polypharmacy and intraoperative propofol use, suggesting that propofol requirement increased as the number of substances used increased. Conclusions: TST in patients presenting for spine surgery is a useful tool to detect substances taken by patients because self-report is often inaccurate. Discrepancies decrease the opportunity for preoperative optimization and adequate perioperative preparation.

To study factors causing postoperative change of PI after surgical correction of ASD and to assess the effect of this variability on postoperative PI-LL mismatch.PI is used as an individual constant to define lumbar lordosis (LL) correction goal (PI-LL 10). Postoperative changes of PI were shown but with opposite vectors. The impact of the PI variability on the postoperative PI-LL has not been studied.The medical and radiographic data analyzed for patients who underwent long posterior instrumented spinal fusion. Inclusion criteria are age, ≥ 20 years old; ASD due to degenerative disk disease (DDD) or scoliosis (DS); ≥ 3 levels fused; and 2-year follow-up or revision. Studied parameters are LL (L1-S1), PI, sacral slope (SS), pelvic tilt (PT), and PI-LL. Measurement error and postoperative changes were defined. Statistical analysis includes ANOVA, correlation, regression, and risk assessment by odds ratio; P ≤ 0.05 considered statistically significant.Eighty patients were included: mean age, 62.4 years-old (SD, 11.1); female, 63.7%; mean body mass index (BMI), 27.1 (SD, 5.6). Distribution of patients by follow-ups includes preoperative 100%; postoperative (1-3 weeks), 100%; 11-13 months. 90%; 22-26 months, 58%; and revision: 24%. Pre- versus postoperative PI (∆PI) changed both positively and negatively and the absolute value of change|∆PI| exceeded measurement error (P ≤ 0.05) reaching as high as 31°, and progressed with time; RPreoperative variability and postoperative instability of PI diminish the applicability of the PI-LL 10° goal to plan correction of LL. An alternative method is offered.IV.

What is overlooked in clinical studies are the possibilities of manufacturing and design aspects of the instrumentation that could initiate rod fracture. Although revision because of hardware fracture is a small fraction of the overall revision rates (12.1% to 13.7%), there are sufficient numbers of revision cases where hardware removed can undergo a thorough metallurgic analysis. This study is unique in that rod characteristics, such as alloy, surface markings, and fracture type, seen at fracture surfaces are considered in the analysis.This work was conducted under both a retrospective and prospective IRB. Patients considered for this study were between the ages of 18 and 85 years who underwent or were undergoing revision spine surgery with previous instrumentation in the cervical, thoracic, or lumbar region and evidence of at least one of the following: catastrophic hardware failure, pseudarthrosis, implant loosening, or nonfusion. Inclusion criteria were determined through radiographic and medical records review.Fifty-six patients who had revision procedures because of different indications were included; 101 rods were removed, tested for fracture, and included in the analysis. Laser marking is significantly (P0.0001) associated with rod fracture. Detailed analysis showed notable surface and subsurface changes as the result of the marking, such as surface melting, cracking, and notching, creating locations to initiate a fracture. The three most informative variables to clinical rod fracture using multiple regression modeling were body mass index, presence or absence of laser mark (yes/no), and length of posterior fusion (≤2 spinal levels/2 spinal levels). It was found that the relative risk of rod fracture is 23 times higher during 20 postoperative years than in cases with this index0.4.For a patient with a given body mass index, if they require a multilevel fixation greater than two levels and rods with laser marks are used, the risk of early rod fracture increases by 40%.

Study Design Electronic survey administered to Scoliosis Research Society members. Objective To determine the prevalence of minimally invasive surgery (MIS) techniques for the treatment of adult spinal deformity. Summary of Background Data There is a paucity of data available on the practice pattern, prevalence of minimally invasive spine surgery, and the preferred minimally invasive techniques in the treatment of adult spine deformity. Methods An electronic nine-question survey regarding individual usage pattern of minimally invasive spine surgery techniques was administered in 2016 to the members of the Scoliosis Research Society. Determinants included complexity in condition of patient population, prevalence of use of minimally invasive techniques in the surgeon's practice, prevalence of use of a particular MIS technique, strategy elected during surgery, adoption of staging of procedures and timing between staging of procedures. Results A total of 357 surgeons responded (61.3% response rate), and 154 (43.1%) of the respondents said that they use MIS as a part of their surgical treatment of adult spinal deformity. However, of these 154 respondents, 67 (43.5%) said that their MIS usage in deformity practice was between 1% and 20%. Only 11 (7.2%) said that they used MIS 81% to 100% of the time. The top MIS approaches that surgeons chose were MIS lateral lumbar interbody fusion 109 (70.59%) and MIS percutaneous screws 91 (58.8%). Conclusions The low rate of adoption of these techniques among the SRS members may be due to the false perception that there is not enough data to support that MIS techniques are better. This and the fact that a practitioner needs to be facile at different MIS techniques may be the true impediment to the adoption of MIS techniques in the treatment of ASD. Level of Evidence Level IV.

Retrospective single-center.To investigate changes in pelvic incidence from flexion to extension. To assess interobserver error in the measurement of pelvic incidence.Pelvic incidence (PI) has been considered a static parameter since it was originally described. But recent studies have shown that PI can change with age and after spinal procedures. Changes in PI based on position have not been investigated.Seventy-two patients who had obtained flexion and extension radiographs of the lumbar spine were identified using strict inclusion and exclusion criteria. PI along with pelvic tilt (PT), sacral slope (SS), and lumbar lordosis were measured in both flexion and extension by two independent measurers. Variations in all parameters and interobserver measurement reliability were analyzed for the entire group.PI changed significantly from flexion to extension with a general tendency to decrease: mean (-0.94°), p.044. However, these changes might have had opposite vectors, and exceeded | 6°| (measurement error) in 20% of cases, with a maximum of 12°. Inconsistencies in changes of SS, as opposed to PT from flexion to extension, were found to be the major factor determining changes in PI (p.001). Obesity significantly contributed to differences in PI between flexion and extension (p = .003).PI is a dynamic parameter that changes between flexion and extension. Changes in SS are the main factor involved in these changes, implicating movement through the sacroiliac joints as the cause. Obese patients have greater changes in PI from flexion to extension.Level II.

STUDY DESIGN Description of a navigated, single-step, minimally invasive technique for the placement of pedicle screws. OBJECTIVE To describe a new technique for minimally invasive placement of pedicle screws in the lumbar spine using O-arm and StealthStation navigation in combination. SUMMARY OF BACKGROUND DATA Minimally invasive surgical techniques are described in the literature as safe and effective methods for pedicle screw instrumentation. These techniques increase radiation exposure and prompt multiple instrument passes through the pedicle. MATERIALS AND METHODS In total, 35 adult patients (187 screws) underwent lumbar surgery with pedicle screw placement using the 1- (8 patients/48 screws) or 2-step (27 patients/139 screws) technique. Complications associated with instrumentation were noted. Pedicle screw position was evaluated. RESULTS Of 187 screws placed, 181 (96.8%) were found to be fully contained within the pedicle (grade 1) and 4 (2.1%) had a breach of

BACKGROUND CONTEXT To minimize complications associated with adult spinal deformity (ASD) surgery, many surgeons pre-operatively plan sagittal plane correction. Unfortunately, it is unclear how the native spine will react postoperatively. In attempts to account for this compensatory response after fusion with upper instrumented level in the lower thoracic region, these authors initially planned thoracic kyphosis restoration to 40° (or left as is if initial kyphosis >40°). After measuring actual compensatory responses postoperatively, this preoperative planning underwent iterative improvement and now utilizes a complex predictive model to simulate compensation. PURPOSE The aim was to determine if a predictive model can simulate changes in thoracic kyphosis (TK) and pelvic tilt (PT) after ASD surgery and to compare it to the prior planning strategy. STUDY DESIGN/SETTING This is a retrospective study evaluating a complex predictive model's use in ASD surgery planning. PATIENT SAMPLE The study population consisted of 42 patients who had surgeries previously planned using the older planning technique. OUTCOME MEASURES Outcome measures included predictive model, prior planning strategy, and postoperative TK and PT values. METHODS Radiographic data from over 500 patients was utilized in training and testing the model. The model used projected lumbar lordosis and number of instrumented levels to predict postoperative TK and PT. With the model, 12- and 24-month postoperative TK and PT were simulated for the patients who had previously planned surgeries. The model and previous planning method were compared to actual postoperative values. RESULTS There were significant differences between measured pre- and postoperative TK and PT. The predictive postoperative values at 12- and 24-M for TK and PT did not significantly differ from actual postoperative values, with better correlative values to actual TK than the previous plan. CONCLUSIONS Patients undergo significant long-term compensatory TK and PT changes, indicating need for pre-operative predictive modeling to aid in surgical planning. The predictive model can project thoracolumbar spine compensation after deformity correction surgery. It is better than the prior planning strategy at anticipating long-term TK and possibly PT. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Different types of mechanical complications after surgical correction of adult spine deformity with osteotomy

STUDY DESIGN A systematic review with meta-analysis. OBJECTIVE To combine published data, focusing on the development of optimal spinopelvic parameters in adult asymptomatic subjects without spine deformity while taking into consideration the impact of potential confounders. SUMMARY OF BACKGROUND DATA A well-grounded approach to define the optimal spinopelvic parameters is necessary for planning surgical correction of spine deformity. MATERIALS Selection criteria: (1) randomized and nonrandomized prospective, cross-sectional, and retrospective studies; (2) participants: asymptomatic subjects without spine deformity aged above 18 years; (3) studied parameters: lumbar lordosis (LL), pelvic incidence, sacral slope, and pelvic tilt; (4) potential confounders: method of measurement, sex, age, ethnicity, weight, height, and body mass index. Search method: Ovid MEDLINE (1946-current) and EMBASE (1980-current), all years through October 2015 were included. Data were collected: number of enrolled subjects, means of the studied characteristics, SD, SE of the means, 95% confidence intervals. A meta-analysis was performed to evaluate the pooled means and range of optimal values (pooled mean±pooled SD) taking into consideration the impact of confounders. The GRADE approach was applied to evaluate the level of evidence. RESULTS Seventeen of 1018 studies were included (2926 subjects from 9 countries). The pooled means and the optimal ranges were: LL (L1-S1), 54.6 (42-67) degrees; LL (L1-L5), 37.0 (22-53) degrees; pelvic incidence, 50.6 (39-62) degrees; sacral slope, 37.7 (28-48) degrees; pelvic tilt, 12.6 (3-22) degrees. The pooled results were statistically significant (P

Current explanations of biomedical alloy degradation are focused on the physicochemical mechanisms of galvanic, pitting, crevice, and fretting corrosion. Ultimately, these studies dismiss the corrosion mechanism as a function of the local microbiome. Sixty spine hardware constructs were examined immediately after explantation for biofilm formation. Marked rod sections were imaged using scanning electron microscopy with energy dispersive x-ray spectroscopy. Backscatter mode was employed to better image the topology of the surface. There is clear differentiation between discoloration due to corrosion vs mechanical damage. Under scanning electron microscopy backscatter electron shadow examination, the authors noted that not all biofilm was removed using the surgical wipes. Corrosion pits were noticeably larger and numerous in areas of biofilm. In areas not associated with biofilms, there were few pits even if mechanical wear was evident. There is no evidence that the surface corrosion is modified between clinically diagnosed infected and noninfected patients. The surface damage present on explanted Ti6Al4V spine rods is uniquely similar to damage found in other industries where microbial-influenced corrosion is prevalent. Given that similar anaerobic, sulfur-reducing bacteria reside in and on human tissues, it is most likely that corrosion observed on explanted hardware is the result of microbial-influenced corrosion and not from inflammatory or other processes. Using analysis methods from other industries to characterize the microbiome present on explanted hardware is necessary. In so doing, a new definition of hardware-induced infection will be forthcoming. [ Orthopedics . 2020;43(1):62–67.]

BACKGROUND CONTEXT As COVID-19 reached pandemic status, in-person orthopedic clinics across the United States were forced to close as many states adopted stay-at-home orders. Previously, the use of telemedicine in orthopedic practices was minimal for a variety of reasons, one being the inability to perform a physical exam in a specialty reliant on direct patient contact for diagnosis and treatment. PURPOSE To evaluate the administration of a novel virtual physical exam for evaluation of spine patients in the telehealth setting. STUDY DESIGN/SETTING Prospective consecutive cohort at a large academic spine center. METHODS A prospective cohort of 52 patients consented to participating in a novel virtual physical exam protocol during routine telemedicine visits at a large, tertiary orthopedic spine practice. Participants were asked to perform a series of carefully designed physical maneuvers using readily available household objects to allow their provider to better assess sensory and motor function in the telemedicine setting. Patients were then asked to complete a short satisfaction survey. RESULTS In total, 52 patients completed the physical exam and survey. Males and females were distributed evenly among the cohort at 50%. The average age was 52.1 +/- 15.5 years. The average score for ease of understanding the exam (1 = easiest, 5 = hardest) was 1.1 while the average score for ease of performance was 1.5. There were 97.56% of participants who felt their provider was better able to understand their condition using the virtual exam findings. CONCLUSIONS This study highlights the utility of a virtual physical exam for assessment of spine patients in the telemedicine setting. Furthermore, this study illustrates the ease with which such an exam can implemented and performed to improve patient evaluation and satisfaction. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

BACKGROUND CONTEXT Lumbar decompression is a viable treatment option for spinal stenosis with neurogenic claudication that has failed conservative treatment. However, given the relatively high rates of reoperation with decompression alone (up to 23%) and the increased surgical burden associated with fusion, alternative stabilization techniques such as dynamic interlaminar spacers have been utilized with the goal of providing stabilization while also preserving motion and native biomechanics. PURPOSE The purpose of this study is to evaluate whether interlaminar spacers can effectively augment lumbar decompression in the treatment of symptomatic spinal stenosis. STUDY DESIGN/SETTING Retrospective cohort study at a single institution. PATIENT SAMPLE Ninety-seven patients were included for analysis. Forty-three of these patients underwent lumbar decompression with placement of an interlaminar spacer, and 54 underwent lumbar decompression alone. OUTCOME MEASURES Radiographic parameters: anterior disc height, posterior disc height, segmental alignment, lumbar lordosis, lumbar range of motion, and foraminal height were measured before and after surgery. Outcome measures such as complication rates, and reoperation rates were also compared between the two cohorts. METHODS This is a retrospective cohort study at a single institution between January 2013 and November 2016. Ninety-seven patients were included for analysis. Forty-three of these patients underwent lumbar decompression with placement of an interlaminar spacer, and 54 underwent lumbar decompression alone. Radiographic parameters such as anterior disc height, posterior disc height, segmental alignment, lumbar lordosis, lumbar range of motion, and foraminal height were measured before and after surgery. Outcome measures, complication rates, and reoperation rates were also compared between the two cohorts. RESULTS Patients in the interlaminar spacer cohort had a significant increase in mean posterior disc height (4.5 to 5.1, p = 0.04) and decrease in mean anterior disc height (9.2 to 8.5 mm, p = 0.02). No significant anterior or posterior disc height change occurred in the laminectomy alone cohort. Both groups had a statistically significant decrease in segmental lumbar lordosis, although there was no observed difference in this degree of change between the two groups and no change in overall lumbar lordosis from L1-S1 in either cohort. Both cohorts demonstrated significant improvement in both Visual Analog Scores (VAS) and Oswestry Disability Index (ODI) postoperatively. The two cohorts had similar rates of postoperative complications, and the interlaminar spacer group had a slightly lower rate of reoperation (11.6% vs 20.4%, p = 0.28). CONCLUSIONS These results indicate that lumbar decompression supplemented with interlaminar spacers can lead to substantial improvement in both clinical and radiographic outcomes. We also found that the interlaminar spacer cohort had similar rates of complications and a lower reoperation rate, which deviates from previously published studies that demonstrate a substantially higher complication rate with interlaminar spacers. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Objectives: This was an analytic retrospective observational study. The aims were (1) to validate patient-specific templating process by comparing postoperative range of motion (ROM) with that predicted by the model, (2) to retrospectively determine the ideal implant size, height, configuration, and location to evaluate if the ROM achieved could have been improved, and (3) to correlate postoperative ROM and clinical outcome. Background: Previous research revealed that after total disc replacement surgery, 34% of patients with less than 5° of postoperative ROM developed adjacent segment disease. The match between patient anatomy (size, facet orientation, disc height) and implant parameters are likely to affect postoperative ROM and clinical outcomes. Methods: Seventeen consecutive patients were implanted with 22 ProDisc-L devices between 2008 and 2015. Three-dimensional finite element (FE) models of the implanted segment were constructed from preoperative computed tomography scans and virtually implanted with the ProDisc-L implant. ROM was determined with the endpoints of facet impingement in flexion and implant contact in extension. FE templating was used to determine the optimal implant size and location. ROM was then measured directly from flexion and extension radiographs and compared to predicted ROM. Pre and postoperative Oswestry Disability Index (ODI) data were used to correlate ROM with clinical outcomes. Results: No significant difference was found between the actual and predicted ROM. The computational templating procedure identified an optimal ROM that was significantly greater than actual ROM. The ROM in our cohort could have been improved by an average of 1.2° or 12% had a different implant size or position been used. Conclusions: FE analyses accurately predicted ROM in this cohort and can facilitate selection of the optimal implant size and location that we believe will increase the chance of achieving clinical success with the application of this technology.

STUDY DESIGN This was an innovative concept and a preliminary prospective series. OBJECTIVE The aim of this study was to present the concept and the technical aspects of patient-specific rods (PSR), and compare preoperative and postoperative sagittal parameters (after PSR implantation), with a special focus on the difference pelvic incidence (PI)-lumbar lordosis (LL). BACKGROUND Despite established techniques for planning and proven correlations between quality of life and sagittal alignment, some patients do not achieve optimal radiologic outcomes after surgery and are still hypolordotic and imbalanced. We hypothesize that the use of PSR could improve the correspondence between planning and surgical realization. METHODS The planning was based on spinopelvic parameters evaluated on a full-spine x-ray. The surgical procedure including osteotomies was simulated using a dedicated program to reach the following objectives: PI-LL

Fusion outcomes and costs of stand-alone anterior lumbar interbody fusion (ALIF), transforaminal lumbar interbody fusion (TLIF) in association with posterior fusion, and anterior/posterior (A/P) fusion were compared using clinical, radiographic, and billing data. Adult patients with symptomatic 1- or 2-level degenerative disk disease in isolation or in association with a grade 1 or 2 degenerative or lytic spondylolisthesis and canal and/or foraminal stenosis who underwent elective stand-alone ALIF, TLIF, or A/P fusion were compared. The analysis focused primarily on fusion rates and costs and secondarily on radiographic and clinical parameters. One hundred six patients at least 2 years beyond surgery (ALIF, 53; TLIF, 17; A/P fusion, 36) were reviewed. Demographics were similar except for age, with the ALIF group being younger (mean, 37.8 years) than the other groups (TLIF, 53.1 years; A/P fusion, 48.2 years). There were no differences between the groups in fusion rates or outcomes as assessed by the Numeric Rating Scale. Compared with the other 2 groups, the ALIF group had a significantly shorter operative time, less blood loss, and a shorter stay ( P P P P =.001) favoring ALIF and A/P fusion over TLIF. Stand-alone ALIF should be considered in the management of patients with 1- or 2-level lumbar degenerative disk disease for which the pathology can be addressed adequately via this approach. [ Orthopedics . 2018; 41(5):e655–e662.]

The objectives of this study were to describe the process of preoperative planning and using patient-specific rods. This retrospective case series involved 18 patients with adult spinal deformity who were treated with posterior instrumentation and spine fusion, with lumbar or thoracic osteotomies, using patient-specific rods. Data extracted included demographic/surgical variables and preoperative, predicted (surgical plan), and postoperative spinopelvic parameters. The outcome analysis involved assessment of preoperative, planned, and postoperative variables. Treatment effect evaluation involved assessing differences between preoperative and postoperative values and correspondence between planned and achieved results. Surgery using preoperative planned patient-specific rods led to excellent adult spinal deformity correction and spinopelvic alignment. [ Orthopedics. 2016; 39(2):79–86.]

The characteristic trait of metallosis is the presence of tissue staining. Analyzing explanted revision hardware from spine surgeries and performing ICPMS/AES analysis on removed tissue samples, a clinically relevant definition for metallosis may be developed. Results of the analysis identified hardware fretting wear and corrosion, and ICP-MS/AES analysis identified elevated metal ion concentrations in all cases. This supports the hypothesis that corrosion may be linked to poor health outcomes and potential need for revision surgery. Using failure analysis methods, corrosion products from orthopedic spine implants can be identified to begin to characterize metallosis in a clinically relevant manner. Failure analysis for patients undergoing revision spine surgery for other causes. Using failure analysis methods we conducted a retrieval analysis of explanted hardware and tissue. Implant failure with surrounding tissue metal staining is a current issue in the field of orthopedics. Specifically in spine, this issue is under reported and over looked as a clinically significant finding. Metallosis is most commonly used to describe the presence of tissue staining however this is not a clinically relevant definition. There is a need for further research to provide a better understanding of metallosis leading to better patient outcomes. Patients were screened for this study during a radiological review prior to surgery. All explanted hardware was documented and inspected for signs of wear and corrosion using non-destructive testing. A tissue sample that is normally removed and discarded was collected for ICP-MS/AES analysis. The presence of fretting corrosion, galling and corrosion fatigue was found on all explanted hardware. Cr levels are significantly higher than what was previously published as normal in muscle 0.03 μg/g. One case was a 4 order of magnitude elevation with the other 2 approximately 2 orders of magnitude increase. Titanium and Co concentrations are also significantly increased. The Ca to P ratio for all samples is approximately 1.7:1 suggesting some form of apatitic crystal present due to drying of the tissues. In all cases, the Al, Mo, V, Co, content in surrounding tissue is significantly elevated >10× above "normal," 8.4 ± 4.8; 1.61 ± 1.41; 0.06 ± 0.03; 1.35 ± 1.97 μg/g respectively. A "normal" reference titanium level could only be found for whole blood, 0.00072 ± 0.1412 μ/g. Iron and Ni measurements are within typical values presented in previous studies. No single mechanism for the release of metal ion in a patient is clear. Evidence suggests a tribocorrosive process due to both wear and environmental factors. Specific biologic mechanisms, such as the possible presence of bacteria may affect the fretting and corrosion of spinal instrumentation must be explored in conjunction with thorough review of patient outcomes. Such an effort can potentially reduce patient readmission and increase successful patient outcomes.

In a previous study, the authors examined the elastic and short-term anelastic springback of Ti6Al4V, CoCrMoC and A316L stainless steel spine rods to observe how the rods mechanically respond in OR contouring. In that study rods were 200 mm long and only the movement at the tip was recorded. The implication of that work was that rods will straighten in-vivo, however, in order for the mechanism of straightening to be determined, the movement of individual bends over time must first be elucidated. Spine rods used were, commercially pure titanium (CP Ti) a primarily α-phase; Ti-6Al-4V; α/β-phase titanium alloy from two different suppliers (denoted by, Ti-6Al-4V (L) and Ti-6Al-4V); β-phase titanium (TNTZ) and CoCrMoC. Following contouring the rods were aged unconstrained, in normal atmosphere or simulated body fluid (SBF) in a CO2 incubator for up to 288 h. Elastic springback is significantly different between alloys with different microstructures. Both types of Ti6Al4V rods, while meeting the ASTM F136 industry standard, have significantly different properties, most importantly yield strength, flexural modulus, and springback. Environment showed no significant impact on anelasticity. The anelastic response of Ti6Al4V L sample, which has relatively more beta phase than the Ti6Al4V sample, follows the pure beta phase TNTZ in its extended time response. CoCrMoC and CP Ti have a very reduced anelastic response compared to the other alloys. This potentially can have unanticipated effects on the outcome of spine procedures, as the surgeon is reliant on the rods having similar properties to achieve a desired outcome.

The purpose of the study was to identify patient-specific and procedure-specific risk and protective factors associated with post-operative surgical site infections (SSIs) among surgical spine patients.CINAHL, PubMed, Ovid, Medline, and EBSCO databases were searched for articles within the past 10 years (January 2003-March 2015). The keywords and combinations used in the search included: Spine surgery, post-operative infection, risk factors, orthopedic infections. The search resulted in 842 articles of which 29 met inclusion criteria. This systematic review adheres to preferred reporting items for systematic reviews and meta-analyses guidelines.Evidence about patient-specific and procedure-specific factors associated with increased risk of post-operative SSIs among patients undergoing orthopedic spinal surgery is inconclusive. Gender (male), age, body mass index, cigarette smoking, diabetes mellitus, a history of infection and alcohol abuse were identified as common patient-specific risk factors. Blood transfusion, implantation, and steroid use were found to increase SSIs in certain studies and associated with no significant difference in other studies. Protective factors include the implementation of pre-operative elements to reduce infection; protocols addressing patient-related factors (smoking, weight, glucose) and operation-related factors (antibiotic prophylaxis, prosthetics, length of operation, and pre-operative cultures); incision drains placed intra-operatively; anterior approach; laminar-flow operating theater, and skin antisepsis using chlorhexidine.Interventions focusing on minimizing patient-specific risk factors and operation-specific risk factors and optimizing patient-specific protective factors and operation-specific protective factors are most effective in minimizing the likelihood of a post-operative infection among patients undergoing orthopedic spinal surgical procedures. The studies reviewed provide conflicting evidence relative to risk and protective factors.

Systematic review with meta-analysis.To compare the perioperative and long-term postoperative effectiveness of bone morphogenetic protein (BMP) for lumbar arthrodesis in skeletally mature adults with degenerative disk disease (DDD) to that of the current golden standard treatment, iliac crest autologous bone graft (ICBG).The treatment efficacy of lumbar arthrodesis in DDD is a complex clinical and economic issue for patients and health care providers.Comprehensive electronic literature search was performed using following databases: Ovid MEDLINE; Embase; Cochrane Library; Central Register of Controlled Trials (CENTRAL); Database of Abstracts of Reviews of Effects; Methodology Register; Technology Assessment Database; and Economic Evaluation Database. The full year ranges of each database until May of 2012 were included.Eight randomized controlled clinical trials of 383 citations were selected. The included studies involved 1138 participants. The pooled 2-year postoperative clinical outcomes were equivalent in BMP and ICBG groups, and exceeded minimum clinically important differences for Oswestry Disability Index, SF-36 (physical scale), and numeric rating scale (back pain). ICBG was associated with increased pain and complications at the donor site (P0.01). The pooled average operative time was 21 minutes less in BMP versus ICBG (P0.001). The pooled rate of additional surgical treatment was 2 times less in the BMP than in the ICBG groups (P=0.006). The pooled risk of nonunion at 24-month follow-up was 2 times less in the BMP than in the ICBG groups (P=0.037), however, this effect was likely biased.BMP, in particular rhBMP-2, is a good alternative to autogenous bone graft, especially in cases when harvesting of autologous bone is contraindicated or undesirable, operation time is limited, and there are no contraindications for BMP use.However, the current study did not reveal evidence robust enough to develop strong medical recommendations concerning BMP use for lumbar arthrodesis in degenerative disk disease.

Background Context. There is no general accepted theory on the etiology of idiopathic scoliosis (IS). An important role of the vertebrae endplate physes (VEPh) and intervertebral discs (IVD) in spinal curve progression is acknowledged, but ultrastructural mechanisms are not well understood.Purpose. To analyze the current literature on ultrastructural characteristics of VEPh and IVD in the context of IS etiology.Study Design/Setting. A literature review.Results. There is strong evidence for multifactorial etiology of IS. Early wedging of vertebra bodies is likely due to laterally directed appositional bone growth at the concave side, caused by a combination of increased cell proliferation at the vertebrae endplate and altered mechanical properties of the outer annulus fibrosus of the adjacent IVD. Genetic defects in bending proteins necessary for IVD lamellar organization underlie altered mechanical properties. Asymmetrical ligaments, muscular stretch, and spine instability may also play roles in curve formation.Conclusions. Development of a reliable, cost effective method for identifying patients at high risk for curve progression is needed and could lead to a paradigm shift in treatment options. Unnecessary anxiety, bracing, and radiation could potentially be minimized and high risk patient could receive surgery earlier, rendering better outcomes with fewer fused segments needed to mitigate curve progression.

Total intravenous anesthesia (TIVA) is usually recommended during spinal surgery when transcranial motor evoked potentials (tcMEPs) are used to monitor. A shortage of propofol has prompted a search for an alternative sedative-hypnotic agent. We explored the use of methohexital as an alternative. TIVA was provided for two adult patients having spinal surgery using an infusion of methohexital. TcMEPs and somatosensory evoked potentials were acquired to monitor neurological function and electroencephalogram was used to titrate the methohexital dose. Two cases are presented in which the anesthesia and monitoring that was provided were successful. These cases indicate that methohexital can be a suitable alternative to propofol in some patients.

Indications for spinal deformity surgery in the thoracic spine are similar to those in the cervical or lumbar spine. The major differences in the procedure include the special considerations needed to accommodate the anatomical variations in the orientation of the facet joints and pedicles, as well as the anterior approach to the spine. These surgeries have evolved to include approaches both through the chest cavity, as well as from posterior. Further, as clinical understanding of spinal sagittal plane deformity has progressed and surgical techniques evolved, procedures involving shortening, lengthening, and/or angular correction through the thoracic spinal column are being performed.

Several anterior cervical plating systems recently have been designed to allow for controlled movement between fused vertebrae to increase load sharing across an interbody graft. The purpose of this study was to determine whether dynamic translating cervical plates are associated with improved radiographic outcomes as compared with variable-angle screw plates in patients undergoing anterior cervical discectomy and fusion (ACDF). We retrospectively reviewed medical records and postoperative radiographic films (3, 6, and 12 months) of patients who underwent single and multilevel ACDF using either dynamic translating or variable-angle plates. Data were analyzed relative to mean displacement of vertebrae, number of vertebrae fused, fusion status, and Cobb angle. Of the 50 patients in this study, 24 received translating plates and 26 received variable-angle plates. Radiographic outcomes were similar between the two groups when looking at mean displacement of vertebrae, number of vertebrae fused, and fusion status. We observed a higher rate of Cobb angle change greater than 3° with translating plates. Additionally, we observed a trend toward loss of lordosis in the translating group and increased lordosis in the variable-angle group. Our study failed to confirm our hypothesis that translating plates are associated with higher fusion rates than variable-angle plates. A higher rate of Cobb angle change along with a decrease in mean Cobb angle was observed in the translating group. Loss of lordosis in the translating group may suggest a negative impact with these plates, including less ideal alignment of the spine.

Background Ehlers-Danlos syndrome (EDS) is a heterogeneous collection of connective tissue disorders characterized by varying degrees of skin hyperextensibility, joint hypermobility, and tissue fragility. Surgical treatment of EDS patients is complicated by the extreme fragility of their vessels and tissues. The purpose of this case report is to present the management of an EDS patient with debilitating low-back pain. Methods A 52-year-old woman with a clinical diagnosis of EDS presented with degenerative disc disease at L4-5 that had not been alleviated by previous microdiscectomies. The clinical course, decision-making process, and treatment are discussed in this case report. Results The patient was referred for genetic evaluation, which classified her with type III EDS, or hypermobility type. We presented the patient with the risks and benefits of fusion versus artificial disc replacement (ADR), particularly with regard to her EDS diagnosis of the hypermobility subtype. Given the patient's lack of extreme spinal hypermobility on examination and the absence of clear contraindications regarding ADR in type III EDS, the decision was made to proceed with ADR. There were no surgical complications, and the patient's low-back pain and radicular symptoms resolved with no evidence of implant migration or hypermobility at 1 year postoperatively. Conclusions In this case report, the referral to a geneticist and consultation with a vascular surgeon were integral steps in the decision to proceed with surgery. Although the clarified diagnosis of type III EDS did not eliminate the potential risk for vascular compromise during surgery, it placed the patient at lower risk than patients with other subtypes of EDS. Similarly, her lack of extreme hypermobility made us more comfortable with pursuing ADR. Although we emphasize extreme caution when considering surgical treatment, this case report suggests that some patients with less severe forms of EDS may be able to successfully undergo anterior spine surgery, including ADR.

STUDY DESIGN A retrospective cohort study. OBJECTIVE To compare the incidence of retrograde ejaculation (RE) after anterior lumbar spine surgery with disc replacement versus fusion with the use of recombinant human bone morphogenetic protein-2 (BMP). SUMMARY OF BACKGROUND DATA Anterior lumbar interbody fusion (ALIF) has become a popular choice for treating a number of pathologies, largely because it preserves the posterior paravertebral muscles and ligaments. Despite these advantages, the anterior approach is also associated with various complications, one of which is RE. A recent study has questioned whether the risk of RE is increased by the use of BMP in ALIF procedures rather than by the approach alone. METHODS We conducted a retrospective review of all male patients who received ALIF using BMP or artificial disc replacement (ADR) on at least the L5-S1 level between 2004 and 2011. Medical records were evaluated for the occurrence of RE, and patients were contacted via the phone to obtain current information. The incidence of RE was then compared between the 2 anterior lumbar surgery procedures. RESULTS Of the 95 cases of anterior surgery including L5-S1, 54 patients underwent ALIF with BMP (56.8%) and 41 patients were treated with ADR (43.2%). Postoperative RE occurred in 4 of the 54 ALIF patients (7.4%) and in 4 of the 41 ADR patients (9.8%). The incidence of RE was not significantly different between groups (P = 0.7226). At latest follow-up, 1 ALIF and 1 ADR patient reported resolution of the RE. CONCLUSION This study found that RE occurred at a similar rate in patients treated with ADR and ALIF with BMP. The overall rate of RE after retroperitoneal anterior lumbar surgery was higher than expected, which underscores the importance of counseling patients about this risk and specifically questioning patients about the symptoms of RE at postoperative visits.

Study design Case report. Objective To demonstrate a 36-year follow-up of a rare operation. Summary of background data There have been no reports of follow-up of pediatric hemivertebra excision and fusion into midadult life. Methods A chart and radiological review at 36 years after surgery. Results The patient is alive and well and leading a normal life. Her Oswestry Disability Index is 0. Mild degenerative radiological signs are evident at the adjacent level above (T10-T12) and below (sacroiliac joints). Conclusion Early excision of the L5 hemivertebra would have been preferable, but the long-term results are good.

Objective: The purpose of this comparison case study is to show a potential complication associated with atlantoaxial fusion, and the preoperative evaluation that could help to avoid it. Background data: The use of lateral mass screw fixation in atlantoaxial fusion has provided surgeons the ability to create rigid fixation, with a high success rate of fusion. While the use of screws for fixation is relatively easy to adopt, the risk of causing neurological damage to the patient is ever present. Many major structures, such as the vertebral artery, carotid artery, and spinal cord, must all be considered during surgery. Methods: A comparison of two patients who underwent the same procedure was reviewed—the first had no complications from surgery and the second underwent revision surgery because of the C1 screw impinging on the C1 nerve exiting the foramen. Results: After removal of the C1 screw and converting to a cable technique, the patient made a full recovery and neurological function was restored. Conclusions: When considering C1-C2 lateral mass screw fixation for atlantoaxial fusion, the size of the foramen should be considered. If the foramen is significantly narrowed, alternate fixation should be selected.

Background context Containment plates are often placed anteriorly in anterior cervical discectomy and fusion (ACDF) to provide stability and prevent migration of the interbody device or autograft. The main advantage of a bioresorbable plate over the typical metallic plate is that it will resorb after fusion has occurred, thus mitigating any long-term instrumentation-related complications. Furthermore, the plates are radiolucent, allowing complete visualization of the fusion site and eliminating imaging artifact. Purpose To evaluate radiographic fusion, mechanical success rates, and histologic characteristics of a bioresorbable containment plate and screws in a 3-month ovine model of ACDF. Study design An in vivo prospective analysis of resorbable anterior cervical plates and screws for use in ACDF in an ovine model. Methods Six sheep underwent C2–C3 and C4–C5 discectomies. Fusions were performed using a polyetheretherketone cage filled with autograft bone. A polymeric plate (70/30 poly- dl -lactic acid), and four screws were placed over an intervertebral disc spacer at each of these two levels. After 3 months, the animals were euthanized and radiographically imaged. Radiographs were analyzed for fusion and instrumentation failures. Functional spinal units were harvested for histologic processing and evaluation. Results Radiographic fusion was noted in three of the 12 levels with no evidence of device failure at any of the levels. However, at necropsy, it was observed that six of the 12 specimens had either a broken screw or a cracked plate. These gross observations were confirmed within the histologic sections. Fusion was verified histologically at C2–C3 in three of the six sheep; none of the fusions were successful at C4–C5. Histologic analysis also found that the tissue surrounding the plate and disc spacer consisted of vascularized fibrous tissue with islands of active woven bone. Inflammatory cells were rarely observed. Conclusions Although the bioresorbable plates and screws did not elicit an iatrogenic tissue response, a high percentage of them failed mechanically. This phenomenon was difficult to observe radiographically, as the radiolucent markers were not able to convey these instrumentation failures. Additionally, there was only a 25% fusion rate. These findings suggest that resorbable implant materials with the current biomechanical and chemical properties are inadequate for cervical fusion. The results of this study strongly suggest that radiographic outcomes alone may not be adequate and that gross or histologic methods should accompany radiographs in studies of bioresorbable materials in animal models.

ObjectAxial lumbar interbody fusion (AxiaLIF) is a novel minimally invasive approach for fusion of L4–5 and L5–S1. This technique uses the presacral space for percutaneous access to the anterior sacrum. The AxiaLIF procedure has the potential to decrease patient recovery time, length of hospital stay, and overall occurrence of surgical complications. It can be used alone or in combination with minimally invasive or traditional open fusion procedures. The purpose of this study was to evaluate complications of the AxiaLIF procedure at the authors' institutions.MethodsPatients who underwent AxiaLIF surgery between October 2005 and June 2009 at the authors' institutions were identified. The authors retrospectively reviewed these patients' charts, including operative reports and postoperative medical records, to determine what complications were encountered.ResultsA total of 68 patients underwent AxiaLIF surgery, with an average follow-up time of 34 months. Sixteen patients (23.5%) experienced a total of 18 complications (26.5%); this group included 8 men and 8 women (mean age 52.1 years). These complications included pseudarthrosis (8.8%), superficial infection (5.9%), sacral fracture (2.9%), pelvic hematoma (2.9%), failure of wound closure (1.5%), transient nerve root irritation (1.5%), and rectal perforation (2.9%).ConclusionsThe complication rate associated with AxiaLIF in the present study was relatively low (26.5%). The most common complications were superficial infection and pseudarthrosis. There were 2 cases of rectal perforation associated with AxiaLIF; one case was found intraoperatively and the other presented 4 days postoperatively. Both patients underwent emergency repair by a general surgeon and had no long-term sequelae as a result of the rectal injuries. It is important for surgeons to be aware of the potential for these complications. Many of these complications can probably be avoided with proper patient selection and operative planning. Preoperative MR imaging, a detailed patient physical examination and history, full bowel preparation, and the use of live fluoroscopy can all help to prevent complications with AxiaLIF surgery.

Bending characteristics were studied in rods used for spinal instrumentation at in-situ contouring conditions. Five groups of five 6 mm diameter rods made from: cobalt alloy (VITALLIUM), titanium-aluminum-vanadium alloy (SDI™), β-titanium alloy (TNTZ), cold worked stainless steel (STIFF), and annealed stainless steel (MALLEABLE) were studied. The bending procedure was similar to that typically applied for in-situ contouring in the operating room and included two bending cycles: first—bending to 21–24° under load with further release of loading for 10 min, and second—bending to 34–37° at the previously bent site and release of load for 10 min. Applied load, bending stiffness, and springback effect were studied. Statistical evaluation included ANOVA, correlation and regression analysis. TNTZ and SDI™ rods showed the highest (p < 0.05) springback at both bending cycles. VITALLIUM and STIFF rods showed mild springback (p < 0.05). The least (p < 0.05) springback was observed in the MALLEABLE rods. Springback significantly correlated with the bend angle under load (p < 0.001). To reach the necessary bend angle after unloading, over bending should be 37–40% of the required angle in TNTZ and SDI™ rods, 27–30% in VITALLIUM and STIFF rods, and around 20% in MALLEABLE rods. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.

Study design A basic science study monitoring changes in the curvature of hand contoured commercially pure titanium (CPTi), titanium-aluminum-vanadium alloy (Ti-6Al-4V), and stainless steel (SS) rods maintained at different temperature conditions. Objective To quantify changes in rod-shape at temperatures representative of those used in clinical practice. Summary of background data The shape of implanted rods can be displaced due to thermo-mechanical properties of the materials. Warmer temperatures likely initiate this effect. A study of shape loss characteristics of various rod implants may help eliminate undesirable outcomes caused by shape displacement. Methods Three different types of rods (CPTi, SS, and Ti-6Al-4V) were hand contoured and then maintained in one of following temperature conditions for 35 days: (1) room temperature (20 °C-25 °C) without autoclaving before contouring; (2) preliminary autoclaving (1, 5, 10, 20 cycles) at 135.0 °C ± 2 °C before contouring followed by body temperature (37.2 °C ± 2 °C). Each rod was 5 mm in diameter and 200 mm long. The rods were mounted over graph paper in fixed positions and photographed to measure displacement of the tip as a function of the curvature. RESULTS.: Statistically significant shape loss of the rods manufactured from all the tested materials was found. The hand contoured CPTi rods displayed considerably higher loss of curvature over time than Ti-6Al-4V and SS rods at all tested temperature conditions. Preliminary autoclaving at 135 °C before contouring tended to amplify this effect, in particular 1 cycle of autoclaving. If the number of preliminary autoclaving cycles was higher (5-10), a tendency of decrease of shape loss effect was observed in Ti-6Al-4V and CPTi rods. Conclusion The shape of the hand contoured CPTi rods was the least stable of the rods across all applied temperature conditions. The SS and Ti-6Al-4V rods were more stable than CPTi rods. Autoclaving before handcontouring tended to increase rods' shape loss.

Study Design. Case series. Objective. To describe the presentation, diagnostic challenges, and treatment of five patients with piriformis syndrome after lumbar artificial disc replacement. Summary of Background Data. Until recently, spinal fusion was considered the standard for surgical treatment of severe lumbar degenerative disc disease. However, artificial disc replacement now offers an alternative solution. Piriformis syndrome results from entrapment of the sciatic nerve at the greater sciatic notch, with symptoms of pain and numbness radiating from the buttock to the foot, mimicking radiculopathy. Methods. In this case series, we report five patients who developed piriformis at our institution after artificial disc replacement. Results. Five patients, aged 35 to 46 years, developed some or all of the following symptoms in the affected leg after artificial disc replacement: posterior leg and buttock pain, calf weakness, and toe and ball of foot numbness and tingling. The onset of symptoms ranged from 6 days to 8 months postoperative, and became debilitating over time. Each patient was diagnosed with piriformis syndrome through physical examination. Three of the patients received a piriformis injection and reported 50% to 100% pain relief lasting 1 to 3 weeks. The patients subsequently underwent physical therapy that provided relief of their piriformis syndrome–related pain and enabled them to resume their normal activities. Conclusion. Piriformis syndrome has not previously been described in the literature as a sequela of lumbar artificial disc replacement. Our case series indicates that this complication may be underdiagnosed. Careful consideration after artificial disc replacement is required if the patient presents with buttock, leg or foot pain, and/or numbness. It is important for physicians to recognize the symptoms of piriformis syndrome and to differentiate piriformis syndrome from nerve root compression and irritation or referred pain from spinal structures. Although controversial, the proper diagnosis of piriformis syndrome may have prevented some of these patients from undergoing unnecessary surgical procedures.

Case Low back pain affects >50% of pregnant women. However, cauda equina syndrome (CES) during pregnancy is rare. Because a delay in treatment increases the risk of irreversible neurologic damage, acute onset is regarded as a surgical emergency. We describe 3 cases of CES in pregnant women at 24, 27, and 30 weeks' gestation, respectively. Conclusion All 3 of the patients underwent surgical decompression in the prone position under general anesthesia with continuous external monitoring of the fetal heart rate. Intraoperative findings were noteworthy for epidural venous plexus engorgement in 2 of the patients. There were no complications for the patients or the fetuses, and all 3 of the patients had postoperative resolution of the neurologic symptoms.

STUDY DESIGN A case report. OBJECTIVE To report a case of high rectal injury during trans-1 axial Lumbar Interbody Fusion (axiaLIF) L5-S1 fixation. SUMMARY OF BACKGROUND DATA Trans-1 axiaLIF procedure is gaining in popularity for L5-S1 fusion due to the ease of access to the sacrum through the presacral space. Normally, the midline of the sacrum at S1-S2 is relatively free from neurovascular and intra-abdominal structures, making this level a safe entry point for the axiaLIF procedure. We report a case of high rectal injury during Trans-1 axiaLIF L5-S1 procedure due to altered intra-abdominal anatomy as a result of multifactorial adhesions formation. METHODS A 44-year-old female patient with a history of previous anterior and posterior spinal surgeries, pelvic inflammatory disease, and non-disclosed previous diverticulitis, developed a high rectal injury during Trans-1 axiaLIF L5-S1 fixation. RESULTS After Trans-1 axiaLIF L5-S1, the patient presented with an episode of melena and hypogastric pain with nausea and vomiting. A computed tomography (CT) scan of the abdomen with intravenous and oral contrast showed presacral soft tissue fluid density with fat stranding and extraluminal rectal contrast and gas with some areas of soft tissue enhancement compatible with probable high rectal perforation. Patient's symptoms gradually subsided during a period of 6 months with aid from a temporary diverting ileostomy and a course of i.v. antibiotics. No spine implants were removed. CONCLUSION We report a case of high rectal injury during Trans-1 axiaLIF L5-S1 fixation and strongly advice that patients who are candidates for this surgery and have any risk factors for intra-abdominal adhesion formation, undergo a pelvic CT with rectal contrast before the surgery to evaluate for any signs of altered rectal-sacral anatomy.

Although thorough preoperative planning is the best method of achieving appropriate levels of lumbar spinal decompression, current methods for intraoperative assessment of the extent of spinal decompression are inadequate. Underdecompression leads to poor clinical outcomes and overdecompression can lead to instability. The purpose of this study is to evaluate the use of multiplanar, fluoroscopic images reconstructed in 3-dimensional format, combined with spinal myelography to intraoperatively assess lumbar spinal decompression. Patients scheduled for lumbar spinal decompression surgery were recruited for intraoperative evaluation using multiplanar imaging and myelography. After performing the minimal necessary decompression of the preoperatively planned areas of spinal stenosis, 13 mL of omnipaque contrast dye was injected into the subarachnoid space. Iso-C sequential fluoroscopic images were acquired and reconstructed into multiplanar images. Images were evaluated for quality, and spinal decompression was evaluated for completeness. The average time for this technique was 13 minutes 42 seconds (range, 9 min 59 s to 19 min 57 s). The average time for injecting the dye was 3 minutes 3 seconds and for assessing the images was 3 minutes 24 seconds. There was a notable decrease in the time required for the technique as the surgeon and staff became more proficient at the procedure. All patients had adequate visualization of the spinal canal and nerve roots. Three patients had additional decompression after review of the images. It is feasible to obtain multiplanar myelograph enhanced C-arm fluoroscopic images in the operating room setting and these are useful for the evaluation of decompression of lumbar spinal stenosis.