BACKGROUND: Cervical spondylosis in the warfighter is a common musculoskeletal problem and can be career-ending especially if it requires fusion. Head-mounted equipment and increased biomechanical forces on the cervical spine have resulted in accelerated cervical spine degeneration. Current surgical gold standard is anterior cervical discectomy and fusion (ACDF). Posterior cervical foraminotomy (PCF) is a nonfusion surgical alternative, and this can be effective in alleviating radiculopathy from foraminal stenosis caused by disc-osteophyte complex. Biomechanical studies have not been done to analyze motion associated with military aircrew personnel following PCF. The aim of this study was to compare the biomechanical responses of the effects of ACDF and PCF with different grades of facet resection under simulated military aircrew conditions using range of motion, disc pressure, and facet loads at the index and adjacent levels.
METHODS: A validated 3D finite element model of the human cervical spinal column was used to simulate various graded PCF and ACDF. All surgical simulations were performed at the most commonly operated level (C5-C6) in warfighters. Pure moment loading under flexion, extension, and lateral bending, and in vivo follower force of 75 N were applied to the intact spine. Hybrid loading protocol was used to achieve 134 degrees of combined flexion-extension and 83 degrees of lateral bending in intact and surgical models to reflect military loading conditions. Segmental motions, disc pressure, and facet load were obtained and normalized with respect to the intact model to quantify the biomechanical effect.
RESULTS: Anterior cervical discectomy and fusion decreased range of motion at the index and increased motion at the adjacent levels, while all graded PCF responses had an opposite trend: increased motion at the index and decreased motion at adjacent levels. The magnitude of changes depended on the level of resection, spinal level, and loading mode. Disc pressure increased at the index level and decreased at the adjacent levels after PCF. These changes were exaggerated with increasing extent of facet resection. Facet load increased at the index level after PCF especially with extension and right (contralateral) lateral bending. Complete facetectomy led to facet load increases greater than ACDF at the adjacent levels in both flexion and extension.
CONCLUSIONS: Posterior cervical foraminotomy is a motion-preserving implant-free surgical alternative to ACDF for warfighters with cervical radiculopathy after failure of conservative management. The treating surgeon must pay close attention to the extent of facet resection to avoid potential spinal instability and future disc and facet degeneration after PCF. Posterior cervical foraminotomy can be more advantageous than ACDF in terms of adjacent segment degeneration, motion preservation, reoperation rate, surgical cost, and retention of warfighters.

BACKGROUND: The cervical spine, pivotal for mobility and overall body function, can be affected by cervical spondylosis, a major contributor to neural disorders. Prevalent in both general and military populations, especially among pilots, cervical spondylosis induces pain and limits spinal capabilities. Anterior Cervical Discectomy and Fusion (ACDF) surgery, proposed by Cloward in the 1950s, is a promising solution for restoring natural cervical curvature. The study objective was to investigate the impacts of ACDF implant design on postsurgical cervical biomechanics and neurorehabilitation outcomes by utilizing a biofield head-neck finite element (FE) platform that can facilitate scenario-specific perturbations of neck muscle activations. This study addresses the critical need to enhance computational models, specifically FE modeling, for ACDF implant design.
METHODS: We utilized a validated head-neck FE model to investigate spine-implant biomechanical interactions. An S-shaped dynamic cage incorporating titanium (Ti) and polyetheretherketone (PEEK) materials was modeled at the C4/C5 level. The loading conditions were carefully designed to mimic helmet-to-helmet impact in American football, providing a realistic and challenging scenario. The analysis included intervertebral joint motion, disk pressure, and implant von Mises stress.
RESULTS: The PEEK implant demonstrated an increased motion in flexion and lateral bending at the contiguous spinal (C4/C5) level. In flexion, the Ti implant showed a modest 5% difference under 0% activation conditions, while PEEK exhibited a more substantial 14% difference. In bending, PEEK showed a 24% difference under 0% activation conditions, contrasting with Ti\'s 17%. The inclusion of the head resulted in an average increase of 18% in neck angle and 14% in C4/C5 angle. Disk pressure was influenced by implant material, muscle activation level, and the presence of the head. Polyetheretherketone exhibited lower stress values at all intervertebral disc levels, with a significant effect at the C6/C7 levels. Muscle activation level significantly influenced disk stress at all levels, with higher activation yielding higher stress. Titanium implant consistently showed higher disk stress values than PEEK, with an orders-of-magnitude difference in von Mises stress. Excluding the head significantly affected disk and implant stress, emphasizing its importance in accurate implant performance simulation.
CONCLUSIONS: This study emphasized the use of a biofidelic head-neck model to assess ACDF implant designs. Our results indicated that including neck muscles and head structures improves biomechanical outcome measures. Furthermore, unlike Ti implants, our findings showed that PEEK implants maintain neck motion at the affected level and reduce disk stresses. Practitioners can use this information to enhance postsurgery outcomes and reduce the likelihood of secondary surgeries. Therefore, this study makes an important contribution to computational biomechanics and implant design domains by advancing computational modeling and theoretical knowledge on ACDF-spine interaction dynamics.

OBJECTIVE: As there are no substantial selection criteria for determining the lowest instrumented vertebra (LIV) in adolescent idiopathic scoliosis (AIS) Lenke 5C/6C, thus, many surgeons base their selection on experience. The study aims to compare the selection of the lowest instrumented vertebrae (LIV) lumbar vertebra three (L3) with the use of direct vertebrae rotation (DVR) to the lowest instrumented vertebrae (LIV) lumbar vertebra four (L4) with the use of non-DVR for the correction of adolescent idiopathic scoliosis (AIS) Lenke 5C/6C when the lower end vertebrae (LEV) is at lumbar vertebrae four (L4).
METHODS: This prospective study involved 101 patients who were divided into two groups based on different techniques. The patients were prospectively followed up for at least four years. All patients included in the study had a lower end vertebra (LEV) at L4, while patients older than 18 years and patients with prior surgical procedures were excluded. The DVR group consisted of 49 patients, and the non-DVR group included 51 patients.
RESULTS: The preoperative mean LIV disc angle was 3.1 ± 3 and 3.1 ± 1, P = 0.097, which corrected to 1.2 ± 0 and 1.1 ± 0 in both groups at 4-year follow-up without statistical significance. The LIVDA and LIVT were statistically insignificant at the preoperative, and there were no significant differences at the follow-up visitation. The DVR group achieved a satisfactory coronal and Cobb\'s angle correction compared to the NDVR group; however, there were no statistical differences at the follow-up visitations. Both groups achieve a satisfactory correction rate without substantial significance in clinical and radiological outcomes. Furthermore, no post-surgical complications were recorded in either group.
CONCLUSIONS: DVR is suitable for selecting L3 as the LIV in AIS Lenke 5C/6C compared to L4 in non-DVR. DVR preserved more segments without substantial complications during the follow-up visitations. Nevertheless, both groups will continue to be followed up to prevent adding-on post-surgical complications.

OBJECTIVE: Implanted devices used in metastatic spine tumor surgery (MSTS) include pedicle screws, fixation plates, fixation rods, and interbody devices. A material to be used to fabricate any of these devices should possess an array of properties, which include biocompatibility, no toxicity, bioactivity, low wear rate, low to moderate incidence of artifacts during imaging, tensile strength and modulus that are comparable to those of cortical bone, high fatigue strength/long fatigue life, minimal or no negative impact on radiotherapy (RT) planning and delivery, and high capability for fusion to the contiguous bone. The shortcomings of Ti6Al4V alloy for these applications with respect to these desirable properties are well recognized, opening the field for an investigation about novel biomaterials that could replace the current gold standard. Previously published reviews on this topic have exhibited significant shortcomings in the studies they included, such as a small, heterogenous sample size and the lack of a cost-benefit analysis, extremely useful to understand the practical possibility of applying a novel material on a large scale. Therefore, this review aims to collect information about the clinical performance of these biomaterials from the most recent literature, with the objective of deliberating which could potentially be better than titanium in the future, with particular attention to safety, artifact production and radiotherapy planning interference. The significant promise showed by analyzing the clinical performance of these devices warrants further research through prospective studies with a larger sample size also taking into account each aspect of the production and use of such materials.
METHODS: The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used to improve the reporting of the review. The search was performed from March 2022 to September 2023.
RESULTS: At the end of the screening process, 20 articles were considered eligible for this study. Polyetheretherketone (PEEK), Carbon-fibre reinforced polyetheretherketone (CFR-PEEK), long carbon fiber reinforced polymer (LCFRP), Polymethylmethacrylate (PMMA), and carbon screw and rods were used in the included studies.
CONCLUSIONS: CFR-PEEK displays a noninferior safety and efficacy profile to titanium implanted devices. However, it also has other advantages. By decreasing artifact production, it is able to increase detection of local tumor recurrence and decrease radiotherapy dose perturbation, ultimately bettering prognosis for patients necessitating adjuvant treatment. Nonetheless, its drawbacks have not been explored fully and still require further investigation in future studies. This does not exclude the fact that CFR-PEEK could be a valid alternative to titanium in the near future.

BACKGROUND: The number of surgical trials is increasing but such trials can be complex to deliver and pose specific challenges. A multi-centre, Phase III, RCT comparing Posterior Cervical Foraminotomy versus Anterior Cervical Discectomy and Fusion in the Treatment of Cervical Brachialgia (FORVAD Trial) was unable to recruit to target. A rapid qualitative study was conducted during trial closedown to understand the experiences of healthcare professionals who participated in the FORVAD Trial, with the aim of informing future research in this area.
METHODS: Semi-structured interviews were conducted with 18 healthcare professionals who had participated in the FORVAD Trial. Interviews explored participants\' experiences of the FORVAD trial. A rapid qualitative analysis was conducted, informed by Normalisation Process Theory.
RESULTS: Four main themes were generated in the data analysis: (1) individual vs. community equipoise; (2) trial set-up and delivery; (3) identifying and approaching patients; and (4) timing of randomisation. The objectives of the FORVAD trial made sense to participants and they supported the idea that there was clinical or collective equipoise regarding the two FORVAD interventions; however, many surgeons had treatment preferences and lacked individual equipoise. The site which had most recruitment success had adopted a more structured process for identification and recruitment of patients, whereas other sites that adopted more \"ad hoc\" screening strategies struggled to identify patients. Randomisation on the day of surgery caused both medico-legal and practical concerns at some sites.
CONCLUSIONS: Organisation and implementation of a surgical trial in neurosurgery is complex and presents many challenges. Sites often reported low recruitment and discussed the logistical issues of conducting a complex surgical RCT. Future trials in neurosurgery may need to offer more flexibility and time during set-up to maximise opportunities for larger recruitment numbers. Rapid qualitative analysis informed by Normalisation Process Theory was able to quickly identify key issues with trial implementation so rapid qualitative analysis may be a useful approach for teams conducting qualitative research in trials.
BACKGROUND: ISRCTN, ISRCTN reference: 10,133,661. Registered 23rd November 2018.

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BACKGROUND: Although early hemivertebra (HV) resection and short fusion (within 4 segments) have been successful in treating congenital HV, there is limited research comparing the outcomes of the shortest-segment fusion (2 segments) versus 3 or 4 segments, particularly in young children. To evaluate the efficacy of posterior hemivertebrectomy combined with two or more segments fusion in children under the age of 10 years with a solitary simple lower thoracic or lumbar HV (T8-L5).
METHODS: This retrospective study included patients under the age of 10 with lower thoracic or lumbar solitary simple HV who underwent hemivertebra resection (HVR) and transpedicular short fusion and were divided into HV ± 1 group (2 segment fusion) and HV ± 2 group (3 or 4-segment fusion). The study recorded preoperative, postoperative (1 week), and the latest follow-up radiographic parameters and complications. The results of the coronal and sagittal planes were analyzed, and the main curve, segmental scoliosis curve, compensatory scoliosis curve, segmental kyphosis curve, and trunk shift were compared.
RESULTS: The study included 35 patients (15 in the HV ± 1 group and 20 in the HV ± 2 group) with a mean age of 5.26 ± 2.31 years and a mean follow-up of 22.54 months (12-68). The mean preoperative Cobb angle was 32.66° ± 7.339° (HV ± 1) and 29.31°±6.642° (HV ± 2). The final Cobb angle was 10.99°± 7.837° (HV ± 1) and 8.22° ± 4.295° (HV ± 2). The main curve corrected by 72% (HV ± 1), 75% (HV ± 2) postoperatively and 67% (HV ± 1), 72% (HV ± 2) at the final follow-up (P > 0.05). There were no significant differences in the correction of the segmental scoliosis curve, compensatory scoliosis curve, segmental kyphosis curve, and trunk shift between the HV ± 1 and HV ± 2 groups (P > 0.05). The unplanned reoperation rate for HV in the thoracolumbar region (T11-L2) is significantly higher (P = 0.038).
CONCLUSIONS: In the context of solitary simple lower thoracic or lumbar HV (T8-L5), HV ± 1 segment fusion suffices and yields comparable correction outcomes in the midterm period when compared to HV ± 2. The reoperation rate exhibited a statistically significant increase in the thoracolumbar region.

Lumbar interbody fusion (LIF) is a surgical procedure for treating lumbar spinal stenosis and deformities. It removes a spinal disc and insert a cage or bone graft to promote solid fusion. Extensive research on LIF has been supported by numerous animal studies, which are being developed to enhance fusion rates and reduce the complications associated with the procedure. In particular, the anterior approach is significant in LIF research and regenerative medicine studies concerning intervertebral discs, as it utilizes the disc and the entire vertebral body. Several animal models have been used for anterior LIF (ALIF), each with distinct characteristics. However, a comprehensive review of ALIF models in different animals is currently lacking. Medium-sized and large animals, such as dogs and sheep, have been employed as ALIF models because of their suitable spine size for surgery. Conversely, small animals, such as rats, are rarely employed as ALIF models because of anatomical challenges. However, recent advancements in surgical implants and techniques have gradually allowed rats in ALIF models. Ambitious studies utilizing small animal ALIF models will soon be conducted. This review aims to review the advantages and disadvantages of various animal models, commonly used approaches, and bone fusion rate, to provide valuable insights to researchers studying the spine.

Scleroderma is a complex autoimmune disorder that primarily affects the connective tissue. Its key pathogenesis comprises vascular abnormalities, autoimmunity, and tissue fibrosis. While the exact etiology of the disease is unclear, patients may exhibit a wide array of symptoms. Scleroderma can rarely induce systemic effects that alter normal cervical spine anatomy. The effects on the cervical spine may be mediated through autoimmune phenomena or dystrophic calcinosis along the vertebral column. We discuss a rare case involving a 60-year-old female with a four-month history of scleroderma, who presented with cervical kyphosis, neck pain, impaired ambulation, dysphagia, edema, and reduced range of motion.

BACKGROUND The proper installation for pedicle screws by the traditional method of surgeons dependent on experience is not guaranteed, and educational solutions have progressed from chalkboards to electronic teaching platforms. We designed a case of 3-dimensional printing drill guide template as a surgical application, which can accurately navigate implantation of pedicle screws, and assessed its effect for simulative training. MATERIAL AND METHODS We randomly selected a set of computed tomography data for spondylolisthesis. A navigational template of pedicles and screws was designed by software Mimics and Pro-E, where trajectories of directions and angles guiding the nail way were manipulated for screwing based on anatomy, and its solid model was fabricated by a BT600 3D printer. The screws were integrated and installed to observe their stability. RESULTS The navigational model and custom spine implants were examined to be compatibly immobilized, because they are tolerant to radiation and stable against hydrolysis. The screw size and template were fit accurately to the vertebrae intraosseously, because the pilot holes were drilled and the trajectories were guided by cannulas with visible routes. During the surgical workflow, the patient reported appreciation and showed substantial compliance, while having few complications with this approach. Compared with fluoroscopy-assisted or free-hand techniques, the effect of simulative training during processing was excellent. CONCLUSIONS The surgical biomodel is practical for the procedural accuracy of surgical guides or as an educational drill. This fostering a style of \"practice substituting for teaching\" sets a paragon of keeping up with time and is worthy of recommendation.