Accuracy of augmented reality-assisted pedicle screw placement: a systematic review.

OBJECTIVE: Conventional freehand methods of pedicle screw placement are associated with significant complications due to close proximity to neural and vascular structures. Recent advances in augmented reality surgical navigation (ARSN) have led to its adoption into spine surgery. However, little is known regarding its overall accuracy. The purpose of this study is to delineate the overall accuracy of ARSN pedicle screw placement across various models. METHODS: A systematic review was conducted of Medline/PubMed, Cochrane and Embase Library databases according to the PRISMA guidelines. Relevant data extracted included reports of pedicle screw placement accuracy and breaches, as defined by the Gertzbein-Robbins classification, in addition to deviation from pre-planned trajectory and entry point. Accuracy was defined as the summation of grade 0 and grade 1 events per the Gertzbein-Robbins classification. RESULTS: Twenty studies reported clinically accurate placed screws. The range of clinically accurate placed screws was 26.3-100%, with 2095 screws (93.1%) being deemed clinically accurate. Furthermore, 5.4% (112/2088) of screws were reported as grade two breaches, 1.6% (33/2088) grade 3 breaches, 3.1% (29/926) medial breaches and 2.3% (21/926) lateral breaches. Mean linear deviation ranged from 1.3 to 5.99 mm, while mean angular/trajectory deviation ranged 1.6°-5.88°. CONCLUSION: The results of this study highlight the overall accuracy of ARSN pedicle screw placement. However, further robust prospective studies are needed to accurately compare to conventional methods of pedicle screw placement.

Comparative surgical outcomes of navigated vs non-navigated posterior spinal fusions in ankylosing spondylitis patients.

INTRODUCTION: Ankylosing Spondylitis (AS) patients with acute spinal fractures represent a challenge for practicing spine surgeons due to difficult operative anatomy and susceptibility to complications. RESEARCH QUESTION: Does intraoperative CT-navigation improve outcomes in patients with ankylosing spondylitis undergoing surgery? METHODS: A retrospective review was carried out at our centre from 05/2016-06/2021 to identify AS patients presenting with a traumatic spinal fracture, managed surgically with posterior spinal fusion (PSF). Cohorts were categorised and compared for outcomes based on those who underwent PSF with intraoperative CT-navigation versus those surgically managed with traditional intraoperative fluoroscopy. RESULTS: 37 AS patients were identified. 29/37 (78.4%) underwent PSF. Intraoperative navigation was used in 14 (48.3%) cases. Mean age of the entire cohort was 67.6 years. No difference existed between the navigated and non-navigated groups for mean levels fused (5.35 vs 5.07; p â€‹= â€‹0.31), length of operation (217.9mins vs 175.3mins; p â€‹= â€‹0.07), overall length-of-stay (12 days vs 21.9 days; p â€‹= â€‹0.16), patients requiring HDU (3/14 vs 5/15; p â€‹= â€‹0.09) or ICU (5/14 vs 9/15; p â€‹= â€‹0.10), postoperative neurological improvement (1/14 vs 1/15; p â€‹= â€‹0.48) or deterioration (1/14 vs 0/15; p â€‹= â€‹0.15), intraoperative complications (2/14 vs 3/15; p â€‹= â€‹0.34), postoperative complications 4/14 vs 4/15; p â€‹= â€‹0.46), revision surgeries (3/14 vs 1/15; p â€‹= â€‹0.16) and 30-day mortality (0/14 vs 0/15). CONCLUSION: This is the first study that compares surgical outcomes of navigated vs non-navigated PSFs for AS patients with an acute spinal fracture. Although limited by its retrospective design and sample size, this study highlights the non-inferiority of intraoperative navigation as a surgical aid in a challenging cohort.

Epidemiology of Traumatic Spinal Cord Injury in Ireland, 2010-2015.

BACKGROUND: The International Spinal Cord Society and World Health Organisation recommend the collection of epidemiological data on traumatic spinal cord injury (TSCI). A 1-year prospective study is ongoing in Ireland. While the results of this study are awaited, it was concluded from a feasibility exercise that a complete retrospective dataset, 2010-2015, could be obtained and would be useful for service planning. METHODS: All patients with TSCI discharged from the national SCI acute and rehabilitation centres were included. Data was collected on gender, age, aetiology, level of injury, American Spinal Injuries Association impairment scale, length of rehabilitation admission and discharge destination. Population denominators were national census figures 2006 and 2011, rolled forward. RESULTS: The incidence of TSCI remained constant throughout the study period, 11.5-13.3 per million per year. The mean age of injury onset was 48.9 (SD 19.8) years. Males accounted for 71.5%. The most common injury level/AIS was incomplete tetraplegia, accounting for 43.2% of all TSCI. Leading aetiology was falls, accounting for 53.3% of injuries. Patients with incomplete tetraplegia were older than those with all other injuries (p < 0.001). CONCLUSIONS: The epidemiological trends identified are similar to those prevalent elsewhere in the developed world. More incomplete tetraplegia among an older patient population necessitates a review of how acute care and rehabilitation services are delivered.

Multifidus innervation and muscle assessment post-spinal surgery.

PURPOSE: Assessment of the integrity of the multifidus muscles and corresponding nerve roots, post-open (OSS) versus minimally invasive spinal surgery (MISS) for lumbar spine fractures. METHODS: We investigated the first six patients undergoing MISS in our institution and age- and sex-matched them with 6 random patients who previously had OSS. All had a similar lumbar fracture configuration without evidence of spinal cord injury. All were assessed using ultrasound muscle quantification and electromyographic studies at a minimum of 6 months post-operatively. Mean cross-sectional area (CSA) was measured at sequential levels within and adjacent to the operative field. Concentric needle electromyography was performed at instrumented and adjacent non-instrumented levels in each patient. RESULTS: Mean CSA across all lumbar multifidus muscles was 4.29 cm(2) in the MISS group, 2.26 cm(2) for OSS (p = 0.08). At the instrumented levels, mean CSA was 4.21 cm(2) for MISS and 2.03 cm(2) for OSS (p = 0.12). At non-instrumented adjacent levels, mean CSA was 4.46 cm(2) in the MISS group, 2.87 cm(2) for OSS (p = 0.05). Electromyography at non-instrumented adjacent levels demonstrated nerve function within normal limits in 5/6 levels in the MISS group compared to 1/6 levels in the OSS (p = 0.03). Instrumented levels demonstrated nerve function within normal limits in 5/12 levels in the MISS group compared with 4/12 in the OSS group, including moderate-severe denervation at 5 levels in the OSS group (p = 0.15). CONCLUSIONS: Posterior instrumented MISS demonstrates a significantly superior preservation of the medial branch of the posterior ramus of the spinal nerve and less muscle atrophy, particularly at adjacent levels when compared to OSS.

Trends in spinal cancers: Primary & metastatic. An Irish epidemiological perspective.

Background: The incidence and histological type of spinal cancer is diverse. It is our role as physicians to explore the epidemiology of spinal cancers so that several projections can be made. Resource allocation, cost analyses, and the requirement of rehabilitation facilities all need to be considered.The objective of this paper is to provide an account of the acute spinal oncological admissions to the National Spinal Injuries Unit (NSIU) in both 2010 and 2020 with the hypothesis that upward trends will be noted. Only by exemplifying this trend, will it highlight the need to give spinal cancer the attention it deserves in the Republic of Ireland. Methods: All patients who were to undergo spinal surgery for primary or metastatic spinal cancer in the Mater Misericordiae University Hospital (MMUH) in 2010 and 2020 were included in this retrospective cohort study. A list of medical record numbers (MRNs) for all patients who underwent spinal surgery in the MMUH were included. Data pertaining to patient demographics were noted. Results: 90 patients were included in this retrospective cohort study. 37 patients in 2010, had increased to 53 by 2020. Metastatic disease to the spine was still the most prominent reason for referral. The most common spinal region affected was the thoracic spine. Breast cancer was the most prevalent metastatic cancer to the spine in 2010. Lung cancer became the most prevalent by 2020. Posterior spinal fusion was the most frequent surgical procedure performed. The length of stay in higher care facilities decreased from 5.4 days in 2010, to 4 days in 2020. Decreased were also seen in the mean length of hospital stay, plummeting from 23.6 days in 2010, to 7.6 days in 2020. The same could not be said for the 30-day mortality rate, increasing from 5.4% in 2010, to 9.4% in 2020. Conclusion: The results of this study show a substantial rise in the incidence and prevalence of both primary and metastatic spinal disease here in Ireland. One can see clear improvements in operative technique, with less patients proceeding to higher levels of post-operative care, and earlier discharge times. This data can be used for future planning. The paper highlights the economic cost of spinal oncological care, but it also identifies key areas where preventative campaigns can be targeted.

An evaluation of the effectiveness of an advanced practice physiotherapist in the emergency department setting in Ireland.

BACKGROUND: One of the means of easing increased pressure on emergency care worldwide has been the development of advanced musculoskeletal physiotherapy practice in the emergency department setting. This model of care is in its infancy in Ireland. AIMS: To evaluate the effectiveness of an advanced practice physiotherapist working as a primary contact clinician in the emergency department at St. James's Hospital, Dublin. METHODS: A three-month retrospective chart review was undertaken for patients assigned the advanced practice physiotherapist as their primary clinician during their emergency department attendance. Three widely accepted measures of quality in emergency medicine were used to evaluate effectiveness, namely, time from attendance to discharge, time from triage to assessment, and unplanned reattendance within seven days. RESULTS: A total of 129 patients were included in this study. Time from attendance to discharge was significantly less in the APP group (mean 208.5 min, standard deviation 122.4 min) than in the ED group (mean 377.1 min, standard deviation 314.7 min) (mean difference - 168.61 (95% C.I - 191.24- - 145.98)) (p < 0.001). Time from triage to assessment was significantly less in the APP group (mean 72.1 min, standard deviation 51.9 min) than in the ED group (mean 94.1 min, standard deviation 96.5 min) (mean difference - 22.08 (95% C.I - 31.28- - 12.89)) (p < 0.001). The unplanned reattendance rate was 3.9%. No adverse events were identified. CONCLUSIONS: The findings of this study indicate that an advanced practice physiotherapist can provide a timely, effective, and safe service for patients attending the emergency department with musculoskeletal complaints in Ireland.

Morbidity and mortality of traumatic cervical spinal cord injuries in a geriatric cohort.

BACKGROUND: Traumatic injuries are among the leading causes of death and disability worldwide. Major trauma presentations have seen a demographic shift recently from the young to the elderly, with significant associated neurological deficit. AIMS: To review the presentation and outcome of elderly patients presenting with cervical spinal injuries and associated neurological deficit that underwent surgical intervention in order to optimise treatment strategies. METHODS: A retrospective review was conducted at a national tertiary referral centre to analyse admission trends from June 2016 to July 2020 for outcomes of elderly patients (≥ 65) presenting with traumatic cervical spine injuries associated with spinal cord injuries (SCI). Demographic, clinical, and radiological characteristics were collected and analysed. RESULTS: Forty-two patients met the inclusion criteria. The most common mechanisms of injury (MOIs) were falls from standing (38.1%) and falls from height (≥ 2 m) (33.3%). Complete SCIs had increased mean LOS (57.6 vs 21.6 days; p = 0.013), postoperative complications (100% vs 60.6%; p = 0.022), life-threatening complications (57.1% vs 9.1%; p = 0.001), and 90-day mortality (37.5% vs 5.9%; p = 0.007) compared to incomplete SCIs. CONCLUSION: Elderly patients with complete SCIs have poorer outcomes and mortality than those with less extensive SCIs. They require more resources, have greater risk of complications, and have higher mortality than those with incomplete SCIs, with subsequent implications on optimal treatment strategies. More robust studies are needed to derive improved risk stratification tools for geriatric patients with spinal injuries.

Neurological recovery after early versus delayed surgical decompression for acute traumatic spinal cord injury.

The aim of this study was to determine whether early surgical treatment results in better neurological recovery 12 months after injury than late surgical treatment in patients with acute traumatic spinal cord injury (tSCI). Patients with tSCI requiring surgical spinal decompression presenting to 17 centres in Europe were recruited. Depending on the timing of decompression, patients were divided into early (≤ 12 hours after injury) and late (> 12 hours and < 14 days after injury) groups. The American Spinal Injury Association neurological (ASIA) examination was performed at baseline (after injury but before decompression) and at 12 months. The primary endpoint was the change in Lower Extremity Motor Score (LEMS) from baseline to 12 months. The final analyses comprised 159 patients in the early and 135 in the late group. Patients in the early group had significantly more severe neurological impairment before surgical treatment. For unadjusted complete-case analysis, mean change in LEMS was 15.6 (95% confidence interval (CI) 12.1 to 19.0) in the early and 11.3 (95% CI 8.3 to 14.3) in the late group, with a mean between-group difference of 4.3 (95% CI -0.3 to 8.8). Using multiply imputed data adjusting for baseline LEMS, baseline ASIA Impairment Scale (AIS), and propensity score, the mean between-group difference in the change in LEMS decreased to 2.2 (95% CI -1.5 to 5.9). Compared to late surgical decompression, early surgical decompression following acute tSCI did not result in statistically significant or clinically meaningful neurological improvements 12 months after injury. These results, however, do not impact the well-established need for acute, non-surgical tSCI management. This is the first study to highlight that a combination of baseline imbalances, ceiling effects, and loss to follow-up rates may yield an overestimate of the effect of early surgical decompression in unadjusted analyses, which underpins the importance of adjusted statistical analyses in acute tSCI research.

Clavicle hook plate fixation for displaced lateral-third clavicle fractures (Neer type II): a functional outcome study.

BACKGROUND: Controversy exists with the use of the acromioclavicular hook plate for the treatment of lateral-third clavicle fractures (Neer type II). This is thought to stem from problems associated with the hook plate causing impingement symptoms, which can cause long-term limitation of movement and pain. Our aim was to evaluate the functional outcomes of patients with lateral-third clavicle fractures treated with the hook plate. METHODS: We prospectively reviewed all patients who underwent surgery from July 2005 to August 2009 using our prospectively recorded electronic patient information database. All patients were assessed in the clinic to determine both Oxford and Constant shoulder scores. RESULTS: We identified 36 patients who underwent surgery with the hook plate, 26 men and 10 women. The mean age was 36.2 years (range, 22-60 years). Of the patients, 46% were smokers. The median length of hospital stay was 2 days (interquartile range [IQR], 1-3). The median follow-up was 28 months (IQR, 23-37). The median time from date of injury to surgery was 7 days (IQR, 4-76). The mean time to union was 3 months (IQR, 2-4), and the union rate was 95%. In total, 92% of plates were removed. The median time to removal was 4.5 months (IQR, 3-8.75). There were no complications. Two patients presented months later after falls with fractures around the medial end of the hook plate. CONCLUSION: Hook plates are an effective form of treatment for lateral third clavicle fractures. The best outcomes occur with plate removal before 6 months postoperatively, provided that the fracture has healed.

Epidemiology of non-traumatic spinal cord injury in Ireland - a prospective population-based study.

Objective: To carry out a study of non-traumatic spinal cord injury (NTSCI) epidemiology in IrelandDesign: Prospective study of all new incident cases of NTSCI during 2017Setting: Republic of IrelandParticipants: All persons with a newly acquired NTSCIInterventions: NoneOutcome measures: Crude and age/sex specific incidences; ISCoS core dataset and non-traumatic dataset; population denominator was 2016 national census figures, adjusted to 2017.Results: Overall crude incidence of NTSCI in the Republic of Ireland in 2017 was 26.9 per million per year. Mean age at onset was 56.6 (SD 17.7) years. Females accounted for 51.2% of cases. Most frequent grade of ASIA impairment scale (AIS) was AIS D. Most common etiology was degenerate conditions (48.8%) followed by neoplastic (26.4%). The most common pattern of onset (51.2%) was lengthy (greater than one month).Conclusions: Incidence of NTSCI is more than double that for traumatic SCI in the Republic of Ireland. This suggests that the delivery of rehabilitation services to patients with spinal cord injuries requires prompt review and expansion.

Lumbar spinal intraosseous schwannoma: a non-operative approach.

Intraosseous schwannomas are benign tumours composed of nerve sheath cells, most commonly affecting the mandible and sacrum. Such intraosseous schwannomas in the vertebra can result in spinal instability causing deformity, pain and even neurological compression. Vertebral involvement in the lumbar spine is extremely rare. A case of a schwannoma of the lumbar spine at the level of L3/L4 is presented. It resulted in progressive lower back pain and right lower limb radiculopathy. The clinical findings, radiological reports and histological diagnosis of this case, along with a review of the literature, are presented. The rationale for non-surgical management of this rare benign tumour is also explored.

The impact of the SARS-CoV-2 pandemic on referral characteristics in a national tertiary spinal injuries unit.

BACKGROUND: The SARS-CoV-2 pandemic has had profound implications on healthcare institutions. AIMS: This study aims to assess and compare referral patterns during COVID-19 to corresponding dates for the preceding 3 years (2017-2019), in order to preemptively coordinate the logistics of the surgical unit for similar future experiences. METHODS: Retrospective review for our institution, a national tertiary referral centre for spine pathology. Two distinct time-points were chosen to represent the varied levels of social restriction during the current pandemic: (i) study period 1 (SP1) from 11 November 2020 to 08 June 2020 represents a national lockdown, and (ii) study period 2 (SP2) from 09 June 2020 to 09 September 2020 indicates an easing of restrictions. Both periods were compared to corresponding dates (CP1: 11 March-08 June and CP2 09 June-09 September) for the preceding 3 years (2017-2019). Data collected included age, gender, and mechanism of injury (MOI) for descriptive analyses. MOIs were categorised into disc disease, cyclist, road-traffic-accident (RTA), falls < 2 m, falls > 2 m, malignancy, sporting injuries, and miscellaneous. RESULTS: All MOI categories witnessed a reduction in referral numbers during SP1: disc disease (-29%), cyclist (-5%), RTAs (-66%), falls < 2 m (-39%), falls > 2 m (-17%), malignancy (-33%), sporting injuries (-100%), and miscellaneous (-58%). Four of 8 categories (RTAs, falls < 2 m, malignancy, miscellaneous) showed a trend towards return of pre-lockdown values during SP2. Two categories (disc disease, falls > 2 m) showed a further reduction (-34%, -27%) during SP2. One category (sporting injuries) portrayed a complete return to normal values during SP2 while a notable increase in cyclist-related referrals was witnessed (+ 63%) when compared with corresponding dates of previous years. CONCLUSION: Spinal injury continues to occur across almost all categories, albeit at considerably reduced numbers. RTAs and falls remained the most common MOI. Awareness needs to be drawn to the reduction of malignancy-related referrals to dissuade people with such symptoms from avoiding presentation to hospital over periods of social restrictions.

A combined experimental and computational study of mechanical properties after balloon kyphoplasty.

Vertebral compression fractures rank among the most frequent injuries to the musculoskeletal system, with more than 1 million fractures per annum worldwide. The past decade has seen a considerable increase in the utilisation of surgical procedures such as balloon kyphoplasty to treat these injuries. While many kyphoplasty studies have examined the risk of damage to adjacent vertebra after treatment, recent case reports have also emerged to indicate the potential for the treated vertebra itself to re-collapse after surgery. The following study presents a combined experimental and computational study of balloon kyphoplasty which aims to establish a methodology capable of evaluating these cases of vertebral re-collapse. Results from both the experimental tests and computational models showed significant increases in strength and stiffness after treatment, by factors ranging from 1.44 to 1.93, respectively. Fatigue tests on treated specimens showed a 37% drop in the rate of stiffness loss compared to the untreated baseline case. Further analysis of the computational models concluded that inhibited PMMA interdigitation at the interface during kyphoplasty could reverse improvements in strength and stiffness that could otherwise be gained by the treatment.

A Multiscale Finite Element Analysis of Balloon Kyphoplasty to Investigate the Risk of Bone-Cement Separation In Vivo.

BACKGROUND: During the past decade there has been a significant increase in the number of vertebral fractures being treated with the balloon kyphoplasty procedure. Although previous investigations have found kyphoplasty to be an effective treatment for reducing patient pain and lowering cement-leakage risk, there have been reports of vertebral recollapse following the procedure. These reports have indicated evidence of in vivo bone-cement separation leading to collapse of the treated vertebra. METHODS: The following study documents a multiscale analysis capable of evaluating the risk of bone-cement interface separation during lying, standing, and walking activities following balloon kyphoplasty. RESULTS: Results from the analysis found that instances of reduced cement interlock could initiate both tensile and shear separation of the interface region at up to 7 times the failure threshold during walking or up to 1.9 times the threshold during some cases for standing. Lying prone offered the best protection from interface failure in all cases, with a minimum safety factor of 2.95. CONCLUSIONS: The results of the multiscale analysis show it is essential for kyphoplasty simulations to take account of the micromechanical behavior of the bone-cement interface to be truly representative of the in vivo situation after the treatment. The results further illustrate the importance of ensuring adequate cement infiltration into the compacted bone periphery during kyphoplasty through a combination of new techniques, tools, and biomaterials in a multifaceted approach to solve this complex challenge.

The diagnostic and prognostic value of artificial intelligence and artificial neural networks in spinal surgery : a narrative review.

In recent years, machine learning (ML) and artificial neural networks (ANNs), a particular subset of ML, have been adopted by various areas of healthcare. A number of diagnostic and prognostic algorithms have been designed and implemented across a range of orthopaedic sub-specialties to date, with many positive results. However, the methodology of many of these studies is flawed, and few compare the use of ML with the current approach in clinical practice. Spinal surgery has advanced rapidly over the past three decades, particularly in the areas of implant technology, advanced surgical techniques, biologics, and enhanced recovery protocols. It is therefore regarded an innovative field. Inevitably, spinal surgeons will wish to incorporate ML into their practice should models prove effective in diagnostic or prognostic terms. The purpose of this article is to review published studies that describe the application of neural networks to spinal surgery and which actively compare ANN models to contemporary clinical standards allowing evaluation of their efficacy, accuracy, and relatability. It also explores some of the limitations of the technology, which act to constrain the widespread adoption of neural networks for diagnostic and prognostic use in spinal care. Finally, it describes the necessary considerations should institutions wish to incorporate ANNs into their practices. In doing so, the aim of this review is to provide a practical approach for spinal surgeons to understand the relevant aspects of neural networks. Cite this article: Bone Joint J 2021;103-B(9):1442-1448.

Prospective epidemiological update on traumatic spinal cord injury in Ireland.

Study design: Prospective population-based epidemiological study on traumatic spinal cord injury in Ireland. Objectives: To provide updated data for the global TSCI repository. Setting: Republic of Ireland. Methods: All cases of TSCI acquired during 2016 were included. ISCoS core dataset was collected on all cases. Descriptive statistics are reported. Results: Overall crude incidence of TSCI was 12.8 per million (61 cases). Males accounted for 75.4%. Mean age at onset was 52.8 (19.9) years. Falls was the most common aetiology, 60.7% and AIS D was the most common injury level/AIS classification, 32.8%. The majority of patients (59%) were discharged home. Conclusions: Overall incidence of TSCI has changed very little since 2000 but many aspects of injury such as age and aetiologies are different. This data can now be included in the next TSCI global mapping update. Sponsorship: Health Research Board, Ireland.

Metastasis Affecting Craniocervical Junction: Current Concepts and an Update on Surgical Management.

STUDY DESIGN: Literature review. OBJECTIVES: Metastatic disease affecting the craniovertebral junction (CVJ) only accounts for 0.5% of all spine metastases. The management of these disease processes is complex, which involves multimodality radiological studies and various surgical approaches. We aimed to review the available evidence and summarize the findings in this review. METHODS: The authors conducted search of PubMed and Google Scholar with the following search terms: metastasis, craniovertebral junction (CVJ), occipitocervical, approaches, stability, and radiotherapy. Articles were reviewed by the authors and determined for inclusion based on relevance and level of evidence. RESULTS: The majority of relevant research reviewed composed of literature reviews of particular aspects regarding metastatic disease affecting the craniovertebral junction, including diagnosis, surgical approach, and radiotherapy. CONCLUSIONS: Prompt evaluation of rotational neck pain with or without occipital neuralgia may reveal early metastatic disease within a stable CVJ. Magnetic resonance imaging appears to be the gold standard imaging modality in detecting this pathology, with nuclear bone scan playing a role in distinguishing benign and malignant processes. Unfortunately, no level 1 evidence exists for use of either radiotherapy or surgery in these cases; however, from the available literature, spinal instability and evidence of progressive neurology are relative indications for operative intervention.

Radiation exposure of the hands and thyroid gland during percutaneous wiring of wrist and hand procedures.

The aim of this study was to investigate the radiation exposure of the hands and thyroid glands of orthopaedic surgeon and assistant during procedures involving percutaneous wiring of the hand and wrist. The radiation dose to the hand and thyroid glands was prospectively studied from a total of 30 percutaneous hand and wrist procedures. Four thermolucent densitometers were used to measure the radiation exposure. Cases were divided depending on fracture location (ie. wrist, metacarpal, phalangeal) and surgical experience (i.e. Senior House Officer, Registrar, Consultant). Mean radiation exposure in the hand for the surgeon was 0.80 mSv and 0.87 mSv for the assistant. There was a significant difference in the unshielded thyroid group compared to the shielded thyroid group (p < 0.05). The duration and number of exposure decreases with increasing experience. We also found a trend whereas we operate from proximal to distal (wrist to phalangeal), the total direct hand exposure increases. Radiation exposure in the hands and thyroid glands during percutaneous wiring of hand and wrist procedures were within the recommended limit. However, for the junior orthopaedic trainee, the risk of over radiating oneself is higher as the duration and number of exposure increases. We recommended the use of thyroid shield and adherence to the ALARA principle in any fluoroscopic assisted procedures. Routine monitoring of radiation exposure is essential in preventing radiation related disease.

Strong similarities in the creep and damage behaviour of a synthetic bone model compared to human trabecular bone under compressive cyclic loading.

Understanding the failure modes which instigate vertebral collapse requires the determination of trabecular bone fatigue properties, since many of these fractures are observed clinically without any preceding overload event. Alternatives to biological bone tissue for in-vitro fatigue studies are available in the form of commercially available open cell polyurethane foams. These test surrogates offer particular advantages compared to biological tissue such as a controllable architecture and greater uniformity. The present study provides a critical evaluation of these models as a surrogate to human trabecular bone tissue for the study of vertebral augmentation treatments such as balloon kyphoplasty. The results of this study show that while statistically significant differences were observed for the damage response of the two materials, both share a similar three phase modulus reduction over their life span with complete failure rapidly ensuing at damage levels above 30%. No significant differences were observed for creep accumulation properties, with greater than 50% of creep strains being accumulated during the first quarter of the life span for both materials. A significant power law relationship was identified between damage accumulation rate and cycles to failure for the synthetic bone model along with comparable microarchitectural features and a hierarchical composite structure consistent with biological bone. These findings illustrate that synthetic bone models offer potential as a surrogate for trabecular bone to an extent that warrants a full validation study to define boundaries of use which compliment traditional tests using biological bone.

A parametric finite element analysis of the compacted bone-cement interface following balloon kyphoplasty.

Treating fractures of the spine is a major challenge for the medical community with an estimated 1.4 million fractures per annum worldwide. While a considerable volume of study exists on the biomechanical implications of balloon kyphoplasty, which is used to treat these fractures, the influence of the compacted bone-cement region properties on stress distribution within the vertebral body remains unknown. The following article describes a novel method for modelling this compacted bone-cement region using a geometry-based approach in conjunction with the knowledge of the bone volume fractions for the native and compacted bone regions. Three variables for the compacted region were examined, as follows: (1) compacted thickness, (2) compacted region Young's modulus and (3) friction coefficient. Results from the model indicate that the properties of the compacted bone-cement region can affect stresses in the cortical bone and cement by up to +28% and -40%, respectively. These findings demonstrate the need for further investigation into the effects of the compacted bone-cement interface using computational and experimental methods on multi-segment models.