The concept of recovery kinetics: an observational study of continuous post-operative monitoring in spine surgery.

Background: The spine surgeon's understanding of an individual patient's burden of disease and functional disability in daily life is shaped by patient-reported outcome measures (PROMs). Although PROMs are useful in understanding the patient's perception of their disease, the use of PROMs constitutes a "snapshot" approach of single timepoint data capture, omitting day-to-day fluctuations in functional status. We introduce the concept of kinetics when considering continuous and objective postoperative patient monitoring with wearable sensors. Methods: A prospective single-centre series was performed using patients either undergoing lumbar decompression for lumbar spinal stenosis (LSS) (n=12), or posterior lumbar fusion for degenerative spondylolisthesis (n=12). The Oswestry Disability Index (PROM) was conducted preoperatively and 12-weeks postoperatively. During this timeframe, continuous measurements of step count and distance travelled were made using a wrist-based wearable accelerometer. Results: Over the 12-week study period, mean daily step count for all participants improved from 4,700 to 7,700 steps per day (P=0.013), following an initial dip in total steps taken. The mean daily distance travelled improved from 3,300 to 5,300 meters per day (P=0.003). Decompression group recovered at a faster rate than the fusion group. Conclusions: Although overall improvement was similar between the decompression and fusion groups, the recovery kinetics varied. The recovery kinetics approach of continuous postoperative monitoring provides additional insight to postoperative patient progress.

Multiple non-contiguous anticoagulation-related spontaneous acute spinal intradural extramedullary hemorrhages.

Background: Spinal intradural extramedullary hemorrhage is a rare and important pathology that may precipitate acute compressive myelopathy. It is most commonly associated with spinal trauma, neoplasia, vasculopathy, and iatrogenesis. In rare circumstances, it occurs spontaneously secondary to anticoagulant and antiplatelet medications without an underlying structural lesion. In these instances, it may be related to vasculopathy and/ or cardiovascular disease risk factors. We highlight the salient clinical and radiological features of this pathology, discuss putative mechanisms of its pathogenesis, and describe surgical considerations related to its management. Case Description: This report describes an elderly gentleman who presented with two discrete spinal hemorrhages associated with separate foci of bleeding, in the context of therapeutic anticoagulation, on a background of significant structural and functional cardiovascular disease with risk factors. Conclusion: Our report is novel in that there are no other cases, to the best of our knowledge, of multiple non-contiguous anticoagulation-related spontaneous acute spinal intradural extramedullary hemorrhages in the medical literature. This article is written with the purpose of assisting clinicians to recognize and expedite treatment of this rare pathology. Prompt diagnosis followed by urgent decompressive surgery provides the best functional outcomes.

Gait assessment tools for degenerative cervical myelopathy: a systematic review.

Background: Degenerative cervical myelopathy (DCM) is a common progressive neurological disorder which may affect one's activities of daily living or even result in paraplegia/tetraplegia if left untreated. Currently, there is lack of consensus of the gait assessment tools for DCM. This systematic review aims to (I) provide an appraisal of the psychometric properties of the available gait assessment tools for DCM, (II) to assess their methodological quality according to The Consensus-based Standards for the selection of health Measurement COSMIN risk of bias checklist and (III) to assess each measurement property result against externally validated criteria. Methods: Six electronic full-text databases [PubMed (via NLM® database], Medline (via OvidSP), CINAHL (via Ebsco), EMBASE (via Ovid), PsycINFO (via CSA) and Web of Science (via Thomson Reuters)] were systematically searched from inception to June 2020. The methodological quality of each study was analysed using the COSMIN risk of bias checklist. The measurement property result and methodological quality of each study were evaluated. Results: Twenty studies were included from 3,339 citations retrieved. Twelve assessment tools for assessing gait in DCM were identified. According to COSMIN criteria, only five studies (25%) included in this review were found to have "very good" methodological quality. For construct validity, five tools had "sufficient" quality. For reliability, two assessment tools [the Total modified Japanese Orthopaedic Association Score (Italian Translation) (mJOA-ITTotal) and the modified Japanese Orthopaedic Association (Italian Translation) Motor dysfunction of the Lower Extremity (mJOA-ITMDLE)] were rated as "sufficient" for interobserver reliability while six assessment tools (the 10 second step test (10 sec ST), 30 minute walk test (30MWT), foot tapping test, mJOA-ITTotal, mJOA-ITMDLE and the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire) were rated as "sufficient" for test-retest reliability. The JOA (6 scores) received a "sufficient" rating for internal consistency. No assessment was available for responsiveness, as only the effect size was available. Discussion: Based upon current evidence, the mJOA in combination with an objective functional test (i.e., 30MWT) is recommended for clinicians assessing gait in DCM, although this may change with an increase in the number of studies completed. Given the importance of assessment tools possessing adequate measurement properties, a focus on studies in this area is warranted.

Standalone titanium/polyetheretherketone interbody cage for anterior lumbar interbody fusion: Clinical and radiological results at 24 months.

Context: Anterior lumbar interbody fusion (ALIF) is a common procedure for patients suffering degenerative, deformity, or posttraumatic pathologies of the lumbar spine. Aims: The aim of this study is to evaluate the clinical and radiological outcomes of a combination Titanium/Polyetheretherketone (Ti/PEEK) 3-screw fixation ALIF cage. Settings and Design: This was a prospective multisurgeon series of 87 patients (105 implants), with a minimum 24-month follow-up. Twelve patients (12/87) were supplemented with posterior percutaneous pedicle screw fixation for additional stability for pars defect spondylolisthesis correction. Radiological follow-up with fine-cut computed tomography (CT) scan occurred at 4-6 months, and again at 18-24 months if no fusion observed on initial CT, was performed to evaluate early and final fusion rates, and integration of the Ti/PEEK cage at the end-plate junction. Clinical follow-up included the subjective measures of pain and functional status and objective wearable device monitoring. Results: The fusion rate was 85% (97/105 implants) 6 months postoperatively, with no implant-related complications, and 95% at 24 months, based on independent radiological assessment. Patients experienced statistically significant improvement in subjective pain and functional outcomes compared to preoperative status. The objective measures revealed a daily step count with a 27% improvement, and gait velocity with a mean increase from 0.97 m/s to 1.18 m/s, at 3 months postoperatively. Conclusions: A Ti/PEEK cage, with allograft and bone morphogenetic protein-2 (BMP-2), achieved rapid interbody progression to fusion and is an effective implant for use in anterior lumbar surgery with high early fusion rates and no peri-endplate lucency. Supercritical CO2 allograft provided an osteoconductive scaffold and combined well with BMP-2 to facilitate fusion.

Gait metrics analysis utilizing single-point inertial measurement units: a systematic review.

BACKGROUND: Wearable sensors, particularly accelerometers alone or combined with gyroscopes and magnetometers in an inertial measurement unit (IMU), are a logical alternative for gait analysis. While issues with intrusive and complex sensor placement limit practicality of multi-point IMU systems, single-point IMUs could potentially maximize patient compliance and allow inconspicuous monitoring in daily-living. Therefore, this review aimed to examine the validity of single-point IMUs for gait metrics analysis and identify studies employing them for clinical applications. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Guidelines (PRISMA) were followed utilizing the following databases: PubMed; MEDLINE; EMBASE and Cochrane. Four databases were systematically searched to obtain relevant journal articles focusing on the measurement of gait metrics using single-point IMU sensors. RESULTS: A total of 90 articles were selected for inclusion. Critical analysis of studies was conducted, and data collected included: sensor type(s); sensor placement; study aim(s); study conclusion(s); gait metrics and methods; and clinical application. Validation research primarily focuses on lower trunk sensors in healthy cohorts. Clinical applications focus on diagnosis and severity assessment, rehabilitation and intervention efficacy and delineating pathological subjects from healthy controls. DISCUSSION: This review has demonstrated the validity of single-point IMUs for gait metrics analysis and their ability to assist in clinical scenarios. Further validation for continuous monitoring in daily living scenarios and performance in pathological cohorts is required before commercial and clinical uptake can be expected.

Objectifying clinical gait assessment: using a single-point wearable sensor to quantify the spatiotemporal gait metrics of people with lumbar spinal stenosis.

BACKGROUND: Wearable accelerometer-containing devices have become a mainstay in clinical studies which attempt to classify the gait patterns in various diseases. A gait profile for lumbar spinal stenosis (LSS) has not been developed, and no study has validated a simple wearable system for the clinical assessment of gait in lumbar stenosis. This study identifies the changes to gait patterns that occur in LSS to create a preliminary disease-specific gait profile. In addition, this study compares a chest-based wearable sensor, the MetaMotionC© device and inertial measurement unit python script (MMC/IMUPY) system, against a reference-standard, videography, to preliminarily assess its accuracy in measuring the gait features of patients with LSS. METHODS: We conduct a cross-sectional observational study examining the walking patterns of 25 LSS patients and 33 healthy controls. To construct a preliminary disease-specific gait profile for LSS, the gait patterns of the 25 LSS patients and 25 healthy controls with similar ages were compared. To assess the accuracy of the MMC/IMUPY system in measuring the gait features of patients with LSS, its results were compared with videography for the 21 LSS and 33 healthy controls whose walking bouts exceeded 30 m. RESULTS: Patients suffering from LSS walked significantly slower, with shorter, less frequent steps and higher asymmetry compared to healthy controls. The MMC/IMUPY system had >90% agreement with videography for all spatiotemporal gait metrics that both methods could measure. CONCLUSIONS: The MMC/IMUPY system is a simple and feasible system for the construction of a preliminary disease-specific gait profile for LSS. Before clinical application in everyday living conditions is possible, further studies involving the construction of a more detailed disease-specific gait profile for LSS by disease severity, and the validation of the MMC/IMUPY system in the home environment, are required.

Objective falls-risk prediction using wearable technologies amongst patients with and without neurogenic gait alterations: a narrative review of clinical feasibility.

OBJECTIVES: The present narrative review aims to collate the literature regarding the current use of wearable gait measurement devices for falls-risk assessment in neurological and non-neurological populations. Thereby, this review seeks to determine the extent to which the aforementioned barriers inhibit clinical use. BACKGROUND: Falls contribute a significant disease burden in most western countries, resulting in increased morbidity and mortality with substantial therapeutic costs. The recent development of gait analysis sensor technologies has enabled quantitative measurement of several gait features related to falls risk. However, three main barriers to implementation exist: accurately measuring gait-features associated with falls, differentiating between fallers and non-fallers using these gait features, and the accuracy of falls predictive algorithms developed using these gait measurements. METHODS: Searches of Medline, PubMed, Embase and Scopus were screened to identify 46 articles relevant to the present study. Studies performing gait assessment using any wearable gait assessment device and analysing correlation with the occurrence of falls during a retrospective or prospective study period were included. Risk of Bias was assessed using the Centre for Evidence Based Medicine (CEBM) Criteria. CONCLUSIONS: Falls prediction algorithms based entirely, or in-part, on gait data have shown comparable or greater success of predicting falls than existing stratification scoring systems such as the 10-meter walk test or timed-up-and-go. However, data is lacking regarding their accuracy in neurological patient populations. Inertial measurement units (IMU) have displayed competency in obtaining and interpreting gait metrics relevant to falls risk. They have the potential to enhance the accuracy and efficiency of falls risk assessment in inpatient and outpatient setting.

Wearable devices for patient monitoring in the early postoperative period: a literature review.

The early postoperative period is a crucial stage in a patient's recovery as they are susceptible to a range of complications, with detection and management the key to avoiding long term consequences. Wearable devices are an innovative way of monitoring patient's post-intervention and may translate into improved patient outcomes, and reduced strain on healthcare resources, as they may facilitate safer and earlier discharge from the hospital setting. Several recent studies have investigated the use of wearable devices in postoperative monitoring. This review outlines the current literature including the range of wearable devices used for postoperative monitoring, the variety of surgeries investigated, and the outcomes assessed. A search of five electronic databases was performed. Data on the range of wearable devices, outcomes and surgeries investigated were extracted and synoptically analysed. Twenty-four articles were retrieved. Data on several different types of surgery were available and discussed. Most studies used wrist-mounted wearable devices and accelerometers or pedometers to assess physical activity metrics, including step counts and physical activity intensity (PAI), as markers of recovery. Wearable devices can provide objective data capture in the early postoperative phase to remotely monitor patients using various metrics including temperature, cardiac monitoring and physical activity. The majority of current research is focussed on wrist-mounted accelerometers and pedometers used to assess physical activity as a marker of postoperative function. Further research is required to demonstrate improved safety and cost-effectiveness of this technology.

Assessment and Post-Intervention Recovery After Surgery for Lumbar Disk Herniation Based on Objective Gait Metrics from Wearable Devices Using the Gait Posture Index.

OBJECTIVE: Surgery for lumbar disk herniation (LDH) presents an option for patients when conservative measures fail. The objective of this clinical study is to investigate a novel, objective outcome measure in patients undergoing lumbar microdiscectomy. METHODS: Twenty-four patients were evaluated pre- and postoperatively using the Oswestry Disability Index (ODI), and a novel objective scoring tool, the Gait Posture index (GPi). The score is calculated from 4 key physical health metrics: daily step count, walking speed, step length, and walking posture. The GPi ranges from 0 (nonambulant) to 100 (excellent walking performance). Wearable accelerometers and observational recordings were used to evaluate the components of the GPi. The GPi was calculated and compared with the ODI, pre- and postintervention. The study was designed as a proof of concept and confirmation of validity for use of the GPi in LDH. RESULTS: At follow-up (average 66 ± 36 days), 23 of 24 patients had an improvement in their GPi after surgery. The average GPi of the cohort improved from 59.33 ± 16.06 to 85.75 ± 9.22 with P < 0.001, with significant changes in all 4 components. The average preoperative ODI was 54.54 ± 20.70, improving to 16.33 ± 14.095 with P < 0.001. The Pearson correlation coefficient was r = 0.56, indicating a correlation between change in ODI and change in GPi. CONCLUSIONS: The GPi score is a new, objective descriptor of mobility in spinal surgery which can be used to augment traditional subjective outcome scoring surveys such as the ODI. Significant changes are seen in the GPi and its constituent metrics in patients undergoing surgery for LDH.

Correction to: 3D-printed spine surgery implants: a systematic review of the efficacy and clinical safety profile of patient-specific and off-the-shelf devices.

Unfortunately, 3rd author's first name was incorrectly published in the original publication. The complete correct name is given below.

Degenerate-disc infection study with contaminant control (DISC): a multicenter prospective case-control trial.

BACKGROUND: A bacterial cause of disc degeneration has evoked several controversies and, if true, would lead to a major shift in treatment paradigm. Earlier studies analyzing the relationship of bacterial disc infection within a degenerative cohort featured prolonged cultures susceptible to contamination. The degenerate-disc infection study with contaminant control (DISC) trial aims to investigate this theory further by examining infection rates using a non-degenerative control cohort in comparison to a degenerative internal control cohort and a sham cohort (sampling only sterile paraspinal tissue). To our knowledge, the current study is the largest evaluating the growth of organisms (or possible contamination rate) in paraspinal tissue if prolonged cultures are performed. Protocols on methodology have been previously published. PURPOSE: (1) To investigate the infection rates across cohorts (degenerative vs. nondegenerative control; paraspinal and/or disc controls vs. combined sampling cohorts) using stringent standardized aseptic surgical technique and laboratory processing. (2) To compare our findings to that of the literature and make a statement in support and/or against a possible contamination theory to positive cultures. STUDY DESIGN: Multicenter, multisurgeon case-control trial. PATIENT SAMPLE: In all, 812 surgical samples were retrieved across a 3.5-year period (2013-2016) including 25 trauma controls (nondegenerative), 550 "disc and paraspinal" samples (degenerative cases with internal control), 190 disc-only samples (degenerative cases without internal control), and 46 paraspinal only controls (sham group). OUTCOME MEASURES: Growth and/or Contamination rate (%) per cohort. Chi-square of growth in disc versus paraspinal samples as a means of examining the distribution of false positive and contaminant growth. The impact of previous injections and/or surgery on positive disc or paraspinal growth. Correlation of Modic changes with positive growth rates analyzed with the Kruskal-Wallis Test. The distribution of species in positive samples were also analyzed. METHODS: The DISC trial is registered under Australian and New Zealand clinical trials registry-ACTRN12616000541404. Institutional ethics review was obtained (HREC northern sector 13/218) at the primary center and further centers (n=6) were recruited. Patients undergoing spinal surgery with discectomy were eligible for trial entry with tissue specimens obtained using strict aseptic technique for microbiological examination. All specimens were handled with sterile instruments only and by a fresh instrument to a sterile pot that was closed immediately. Separate pots were used for the disc and paraspinal tissue respectively with similar stringent processing during microbiological assessment. A cohort of the degenerative cases at one single institution also underwent an additional histopathological examination. RESULTS: There was an expected significant difference in gender and age associated with the non-degenerative control group (due to trauma patients) compared with other cohorts. There was a higher percentage of positive-growth in the control group in comparison to the disc and paraspinal and disc only groups across positive disc growth (48% vs. 27% vs. 17%, p<.001). A similar infection rate was observed in the paraspinal samples across the equivalent controls (44% vs. 36% vs. 37%, p=.739). There was a significant difference in the proportions of positive growth with a large proportion of false positives (growth in both disc and paraspinal samples; p<.001). There was no difference in true positive growth between the case and control groups (16.0 vs. 7.7%, p=.112). These trends were preserved across all cohorts and when stratifying by spinal segment (cervical or lumbar). There was no correlation between Modic changes and positive disc culture growth (p=.398, n=144 samples). Cutibacterium (formerly Propionibacterium) acnes was the most dominant pathogen isolated, representing between 50% and 70% of positive disc and paraspinal specimens, followed by staphylococcal species. CONCLUSIONS: Our study failed to find a difference in true infection rates between the nondegenerative and degenerative disc populations. These findings are suggestive of a contamination theory and against a common infective etiology in the setting of discogenic back and neck pain. We believe the rationale for antibiotic therapy in the management of discogenic back pain warrants further evidence to establish efficacy.

Dynamic myelopathy as a result of C1 posterior arch aplasia and os odontoideum. A case report.

The atlas (C1) and axis (C2) have distinct morphologies to support the skull and facilitate head rotation and neck flexion. Congenital defects of C1 posterior arch are rare. We present a case of a 59-year-old man with both an absent C1 posterior arch with concomitant os odontoideum. The patient presented with neck crepitus, moderate neck pain and progressive worsening upper limbs paraesthesia and pain. Computed tomography (CT) revealed non-union between the odontoid process and body of axis as well as absence of C1 posterior arch. An occiput C0-C3 fusion was performed. The patient's symptoms improved significantly, and he is functioning well at 12 months. CT showed solid fusion without implant migration. Concomitant os odontoideum with aplastic C1 posterior arch is rare with limited evidence to guide management. Posterior fixation and fusion may be a potential solution to prevent dynamic compression, thereby preventing further myelopathy and related complications.

Three-Dimensional Morphometric Analysis of Lumbar Vertebral End Plate Anatomy.

BACKGROUND: Information on the three-dimensional (3D) shape of vertebral end plates is lacking. Previous studies have analyzed two-dimensional shape; however, 3D data are important because they may help improve our understanding of how differences in shape are related to age, gender, race, size, and other parameters, which may subsequently help improve device design for interbody prosthesis. OBJECTIVE: To study the 3D shape of lumbar vertebral end plates from normal adult lumbar spines and correlate them with age, gender, spinal/end plate level, end plate surface area, concave depth, and size. METHODS: An in vivo analysis was undertaken of lumbar vertebral end plate 3D shape. A total of 136 patients' computed tomography scans were used to create 3D models of the lumbar spine for each patient, which were subsequently analyzed. RESULTS: The shape of the superior end plates is different compared with inferior end plates. Across the lumbar spine (L1-S1), the shape of inferior end plates is similar; however, the shape of the superior end plate varies between spinal levels significantly. There was no clear relationship between age and principal component (PC) shapes but there was a strong correlation between end plate concave depth and end plate PC shape scores. CONCLUSIONS: Future interbody (disc replacement and fusion) device designs could use the findings that inferior end plate shape is similar throughout the length of the lumbar spine, whereas superior end plate shape changes. Further, future implants could be level-specific because the present study shows that end plate shape varies through the length of the lumbar spine.

3D-printed spine surgery implants: a systematic review of the efficacy and clinical safety profile of patient-specific and off-the-shelf devices.

PURPOSE: Three-dimensional printing (3DP), or additive manufacturing, is an emergent fabrication technology for surgical devices. As a production method, 3DP enables physical realisation of surgical implants from geometrically complex digital-models in computer-aided design. Spine surgery has been an innovative adopter of 3DP technology for both patient-specific (PS) and market-available 'Off-The-Shelf' (OTS) implants. The present study assessed clinical evidence for efficacy and safety of both PS and OTS 3DP spinal implants through review of the published literature. The aim was to evaluate the clinical utility of 3DP devices for spinal surgery. METHODS: A systematic literature review of peer-reviewed papers featured on online medical databases evidencing the application of 3DP (PS and OTS) surgical spine implants was conducted in accordance with PRISMA guidelines. RESULTS: Twenty-two peer-reviewed articles and one book-chapter were eligible for systematic review. The published literature was limited to case reports and case series, with a predominant focus on PS designs fabricated from titanium alloys for surgical reconstruction in cases where neoplasia, infection, trauma or degenerative processes of the spine have precipitated significant anatomical complexity. CONCLUSION: PS and 3DP OTS surgical implants have demonstrated considerable utility for the surgical management of complex spine pathology. The reviewed literature indicated that 3DP spinal implants have also been used safely, with positive surgeon- and patient-reported outcomes. However, these conclusions are tentative as the follow-up periods are still relatively short and the number of high-powered studies was limited. Single case and small case series reporting would benefit greatly from more standardised reporting of clinical, radiographic and biomechanical outcomes. These slides can be retrieved under Electronic Supplementary Material.

Proposed objective scoring algorithm for assessment and intervention recovery following surgery for lumbar spinal stenosis based on relevant gait metrics from wearable devices: the Gait Posture index (GPi).

BACKGROUND: Lumbar spinal stenosis (LSS) results in significant pain and disability. As spine healthcare providers, monitoring patient's outcomes is of the highest importance, and guides everything we do. However, a large amount of our data has been based solely on subjective, single time-point outcome tools limited by their subjective nature. METHODS: We herein propose a novel, simple objective scoring system, the Gait Posture index (GPi). Four key objective health metrics, which can be measured using wearable devices have been identified to correlate with health status: (I) step count; (II) gait velocity; (III) step length; (IV) posture. An algorithm combining the above metrics was established to 'score' patient's ambulation from 0 (bed bound)-100 (excellent mobility and gait function). Thirteen surgical patients were assigned to the GPi scoring algorithm and compared with traditional subjective scoring systems Oswestry Disability Index (ODI) and Patient Satisfaction Index (PSI) as a proof of concept and confirmation of validity. RESULTS: At 3 months, 11 out of 13 patients following decompression for LSS had an improvement with their GPi 20.79±17.44, P=0.001. In addition, Pearson correlation revealed positive correlation between change in GPi with change in ODI (r=0.682, n=13, P=0.01) and negative correlation between change in GPi with PSI (r=-0.618, n=13, P=0.024). CONCLUSIONS: The GPi algorithm correlates accurately with preoperative and post-operative mobility which are comparable to traditional subjective scoring systems. GPi affords the health care provider with a relevant measure of patient outcome, and real-time recovery dynamics following decompression for LSS.

Three-Dimensional Planning and Patient-Specific Drill Guides for Repair of Spondylolysis/L5 Pars Defect.

BACKGROUND: Incomplete ossification of the pars interarticularis will result in a pars defect, a common cause of low back pain in youth and strongly associated with participation in high-impact sports. If left untreated, it can result in spondylolisthesis, causing dynamic canal stenosis, low back pain, and radiculopathy. The treatment of pars defect was first described by Bucks in 1970, who used screws in the lamina placed through an upward and outward direction. However, because of the multiple inclusion and exclusion criteria and narrow margin of error, the Bucks pars repair technique is not commonly performed. METHODS: A 28-year-old woman had with low back pain that she had been experiencing since mid-adolescence. Computed tomography revealed a bilateral L5 pars defect without spondylolisthesis. Her L5 vertebra was reconstructed virtually. The screw trajectories, a 3-dimensional (3D) model of the vertebra, and a patient-specific drill guide (PSDG) were designed and printed using positioning guide software (MySpine MC Guides [Medacta International SA, Castel San Petro, Switzerland]). A modified Bucks procedure using cannulated compression screws and the PSDG was performed. RESULTS: Follow-up computed tomography revealed accurate placement of the compression screws, mirroring the planned trajectory. The patient was pain free at 3 months postoperatively, and early union across the defect was visualized on the 5-month radiographic imaging study. CONCLUSION: Using 3D planning software, complex surgical procedures can be planned using the patient's anatomy and computed tomography. With the aid of 3D-printed PSDGs, screw placement in narrow corridors, such as was shown in our case, is safe, efficient, and achievable.

The role of wearable devices and objective gait analysis for the assessment and monitoring of patients with lumbar spinal stenosis: systematic review.

BACKGROUND: The purpose of this systematic review was to evaluate the accuracy and reliability of wearable devices for objective gait measurement of Lumbar Spinal Stenosis (LSS) patients, with a focus on relevant gait metrics. METHODS: Systematic searches were conducted of five electronic databases to identify studies that assessed gait metrics by wearable or portable technology. Data was collected according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines. RESULTS: Four articles were identified for inclusion in this review. The objectives, methodology and quality of the studies varied. No single gait metric was investigated in all four studies, making comparison difficult. The most relevant metrics reported included gait cycle, gait velocity, step length and cadence, which were reported in two studies. Two studies explored gait symmetry. Differences between LSS patients and normal healthy subjects are demonstrable using wearable technology. CONCLUSIONS: The measurements of gait cycle, cadence, step length, gait velocity, and number of steps with wearable devices can be used in the gait measurement of LSS patients for initial assessment, and objective outcomes following interventions. However, data and analysis are limited, and further studies are necessary to comment on reliability.

History of Integral Fixation for Anterior Lumbar Interbody Fusion (ALIF): The Hartshill Horseshoe.

OBJECTIVE: Anterior lumbar interbody fusion (ALIF) is a common spinal fusion option for different spinal pathologies. In the early years, implant migrations/expulsions were potential complications of ALIFs due to the lack of integral fixation. We present a historical vignette on the inception and development of the first stand-alone ALIF (SA-ALIF) implant-the Hartshill Horseshoe (HH). METHODS: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic search was carried out for 3 online databases focusing on implant development for ALIF, refining the search to before 1995. A personal communication with the original patent holders of the HH was used due to the lack of formal publication of the HH during its early years. RESULTS: Since 1932, the idea of anterior lumbar fusion was proposed and was carried out in 1933 using a tibial peg. Autografts were first reported in 1936 as interbody spacers for ALIF. Since then, bone grafts were commonly used for ALIF. However, ALIFs were not commonly performed due to variable reported outcomes. A pilot study in 1971 reported the use titanium mesh blocks as interbody implants in 6 patients. No articles reporting the use of integral fixation for SA-ALIF implants were found before the development of the HH in 1984. CONCLUSIONS: The HH was the first synthetic SA-ALIF implant developed. Since the HH, multiple SA-ALIF implants have been designed. The benefits of integral fixation in a SA-ALIF device include immediate implant stability, ability to reduce and correct deformity postimplantation, prevention of implant migration, and increased implant-bony endplate contact for early osseointegration.

Technical Note: Pedicle Cement Augmentation with Proximal Screw Toggle and Loosening.

BACKGROUND: Cement augmentation is a technique used to increase the stability and purchase of pedicle screws in poor quality bone. Various methods can be applied for cement delivery, such as cement injection before screw placement and the use of fenestrated screws. However, potential problems can arise with the use of cement augmentation. CASE PRESENTATION: A 66-year-old man with a lower trunk deformity, severe kyphosis, and sagittal imbalance following fusion (L2-5 ), with minimal comorbidities, was referred to our unit 9 months after surgery. Pain and progressive kyphosis were investigated clinically and radiographically with computed tomography (CT) scans to assess the status of the hardware and fusion. CT imaging revealed that cement was present only at the distal tip of the fenestrated screws at the L4 vertebral level. A non-union was present along with loosening and a halo around the body of the pedicle screws, and there was evidence of pullout of inferior screws. CONCLUSION: Single-level cement augmentation of pedicle screw in a posterior construct and distal tip cement augmentation of the screw results in a fixed pivot point. Micromotion in cranio-caudal loading during flexion and extension may result in screw toggling with the single-level cement-augmented tip as a fulcrum. This may cause screw loosening, which can lead to pullout and loss of construct stability. The halo around the screw suggests bone loss and/or a fibrous tissue interface, which further complicates revision surgery. Stress shielding and polymethylmethacrylate cement present additional difficulties. The findings of this technical note question the risks and benefits of cement-augmented fenestrated pedicle screw fixation for spinal fusion. Although incidences of such cases are uncommon, surgeons should perform this technique with caution. Accurate restoration of lumbar lordosis during index procedures is important to minimize the risk of construct failure.