Purpose: The rate of dislocation after revision total hip arthroplasty (RTHA) has varied from 8 to 28% in published series. Many causes are involved, but little work has been focused on the incidence of spinal disease in patients with postoperative dislocation. Material and methods: We performed a prospective analysis of 267 patients who had undergone RTHA in search of risk factors of postoperative dislocation. Chi-square test or Student’s t test were used for the statistical analysis as appropriate. P < 0.05 was considered significant. Results: We excluded 37 patients who had undergone first line THA with a restrained cup and who had not experienced dislocation. The 230 patients retained for analysis had undergone primary surgery with no intra or postoperative anti-dislocation measure. Among these, 31 (13.4% experienced dislocation). The cause was evident in ten cases (malposition, fracture of the greater trochanter, sciatic paralysis). For the other 21 patients, age, gender, types of surgery (uni or bipolary), surgical approach, size of the implant, and size of the femoral or acetabular defects were not found to influence the rate of postoperative dislocation. Conversely, a significant relationship was found between increased rate of dislocation and history of repeated dislocations (p < 0.001), prior surgery (p< 0.05), and association with spinal disease (p< 0.02). Characteristically, there was either radicular, or spinal disease, or both. Retrospective analysis of the radiograms showed that the measures of sacral incidence and inclination of lumbar lordosis were not predictive of dislocation. Inversely, the projection of a vertical line passing through the centre of rotation of the hips on L3 was different in patients who had experienced dislocation and those who had not (p< 0.02). Discussion: This study confirms the role of a history of dislocation and prior surgery in the risk of postoperative dislocation. It also shows that associated spinal disease, which may results from radicular disease, as well as altered spinal static can have an influence. A prospective study is currently under way to distinguish these features

Aims. The escalating demand for medical resources to address spinal diseases as society ages is an issue that requires careful evaluation. However, few studies have examined trends in spinal surgery, especially unscheduled hospitalizations or surgeries performed after hours, through large databases. Our study aimed to determine national trends in the number of spine surgeries in Japan. We also aimed to identify trends in after-hours surgeries and unscheduled hospitalizations and their impact on complications and costs. Methods. We retrospectively investigated data extracted from the Diagnosis Procedure Combination database, a representative inpatient database in Japan. The data from April 2010 to March 2020 were used for this study. We included all patients who had undergone any combination of laminectomy, laminoplasty, discectomy, and/or spinal arthrodesis. Results. This investigation included 739,474 spinal surgeries and 739,215 hospitalizations in Japan. There was an average annual increase of 4.6% in the number of spinal surgeries. Scheduled hospitalizations increased by 3.7% per year while unscheduled hospitalizations increased by 11.8% per year. In-hours surgeries increased by 4.5% per year while after-hours surgeries increased by 9.9% per year. Complication rates and costs increased for both after-hours surgery and unscheduled hospitalizations, in comparison to their respective counterparts of in-hours surgery and scheduled hospitalizations. Conclusion. This study provides important insights for those interested in improving spine care in an ageing society. The swift surge in after-hours spinal surgeries and unscheduled hospitalizations highlights that the medical needs of an increasing number of patients due to an ageing society are outpacing the capacity of existing medical resources. Cite this article: Bone Jt Open 2024;5(8):662–670

Study purpose: Cancer patients presenting with symptomatic spinal metastases is an increasing problem. It is widely accepted that surgery plays an important role in the management of these patients and recent studies1 conclude that surgical treatment should be more frequently offered. However, who should be offered surgery remains controversial, largely because of a lack of information about outcome. Our study is a prospective analysis of survival and functional outcome in patients with metastatic spinal disease treated primarily by surgical decompression and stabilisation when indicated. Methods: Sixty two patients with radiologically suspected metastatic spinal disease, managed by one consultant neurosurgeon, were enrolled into a prospective cohort study. Patients presented with pain and or myelopathy. Survival, continence, walking, analogue pain scores and short form 36 (SF-36) scores were analysed. Results: Median age was 62 years (22–79 years, 35 female, 27 male) with the commonest primary tumours being breast (26%), lymphoma (13%) and prostate (10%). Lung cancer was poorly represented (1 patient). Survival rates were 56% at 1 year, 49% at 2 years and 28% at 3 years. Of 16 patients not walking pre-op, 8 gained the ability to walk, while 5 out of 7 incontinent patients gained continence following surgery. Conclusion: Our data indicate that long term survival and favourable functional outcomes can be achieved following surgery in patients with metastatic spinal disease. We strongly advocate that patients presenting with metastatic spinal disease be considered for primary surgical treatment but would highlight the importance of appropriate patient selection

The aim of this study was to prospectively assess the outcome of patients with metastatic spinal disease who underwent minimally invasive fixation of the spine for intractable pain or spinal instability. This is a prospective audit of patients with metastatic spinal cord disease who have undergone minimally invasive fixation of the spine from August 2009 until the present date. This was assessed by pre and post-operative Oswestry Disability Index (ODI), EQ5D and Tokuhashi scores. Intra- and post-operative complications, time to theatre, length of inpatient stay, analgesia requirements, mobility, chest drain requirement and post-operative HDU and ITU stays were also recorded. So far, 10 patients have met the criteria. There were no intra-operative complications. Post-operatively, there were no complications, chest drains, increase in analgesia or stay on the HDU or ITU. All patients showed an improvement in mobility. The mean post-operative day of mobilisation was 2 days, post-operative days until discharge 5.3 days and length of inpatient stay was shorter than traditional surgery. Blood loss was minimum except one patient with metastatic renal cell carcinoma who needed transfusion intraoperatively. ODI, VAS and EQ-5D scores were calculated and were significantly improved compared to preoperatively. This novel approach to management of metastatic spinal disease has resulted in improved mobility, short inpatient stays without the need for chest drains, HDU or ITU and an improved the quality of life in pallliative patients. This is a completely new strategy to treat the pain in these patients without the usual associated risks of surgery and has major advantages over traditional surgical techniques which may preclude this group of patients having any surgical stabilisation procedure at all

Introduction: Metastatic spinal disease continues to be a challenge in the management of patients with advanced malignancy. Anterior en bloc spondylectomy and stabilisation, a more extensive procedure, is favoured as it is thought to provide a curative resection and improve the overall outcome (Tomita et al,2002; Wiegel, 1999). Aim: The aim of this study was to see if there is still a role for extensive posterior decompression (Wide laminectomy and transpedicular decompression) with stabilisation in the treatment of these patients which is the mode of treatment used in our institution and favoured by some others (Bauer, 1997). Patients and Methods: We retrospectively reviewed a cohort of patients treated in our institute by extensive posterior decompression and stabilisation between 2000 to 2006. We excluded patients having haematological primaries and anterior surgery and those with inadequate data. Outcome measures used were post operative mortality, Post operative improvement in Frankel score, level of pain perception, level of mobility and ability to perform activities of daily living. Results: 52 patients had posterior surgery with Colarado instrumentation being used in a majority. There was a slight male preponderance with an average age of 67 years. The mean length of follow up was 12 months.57% patients were dead at last review. 52 % patients showed an improvement in Frankel scores. There was a significant decrease in analgesic requirement post operatively with an improvement in pain scores. Similarly there was an improvement in the ability to perform activities of daily living and the level of mobility. No major surgical complications were noted bar a few superficial wound infections. Revision surgery was done in 6 cases. In 2 it was for a tumour recurrence, for broken rods in 2 and converted to anterior in 2. There were 4 immediate peri operative deaths. Conclusion: Our results are comparable to Bauer et al, 1997 and other series. Posterior spinal surgery is very much a viable treatment option to treat selected cases with metastatic spinal disease. It avoids all the complications and morbidity of anterior surgery while producing an overall improvement in pain, the quality of life, level of mobility and neurological status

Assessment and referral of spinal disease in a primary care setting is a challenge for the general practitioner. This has led to establishment of spinal assessment clinic to insure prompt access to the patient who requires treatment by a spinal surgeon. These clinics are run by a trained physiotherapist who liaises with a member of the spinal team and decides the need for referral to the spinal clinic on the bases of the patient’s history and clinical examination. In our clinic each patient is also assessed with Oswestry disability index, Short form-36, visual analogue score and hospital anxiety score (HADS), although these scores do not contribute to the clinical decision-making. The aim of this study is to assess the screening value of Oswestry disability score, Short form-36 scores in diagnosing acute spinal pathology. Sixty-nine patients who were referred to the spine clinic from the assessment clinic between March and December 2001 were recruited. Sixty-nine age and sex-matched patients were randomly chosen from five hundred and twelve patients who were seen in the spinal assessment clinic and did not need referral to the specialised spine clinic. The Oswestry disability score, Short form-36 scores and pain visual analogue scores between the two groups were statistically compared. The correlation between the level of psychological morbidity, length of symptoms and presence of past history of symptoms against the level of disability was statistically assessed. Although there was a significant increase in the level of disability in the referred group with each score (Oswestry Disability Score P< 0.001, SF-36 physical component score P=0.014, Visual analogue pain score P< 0.001). The variation in the scores makes the scoring system unspecific for use as a screening tool. We also found strong relationship between psychological disability and length of symptoms indicating the need for prompt treatment for back pain

Objective: Measuring outcomes from chronic disease in terms of generic, health-related quality of life (HRQoL) instruments is of increasing importance to allow valid comparison of interventions and to accurately assess efficacy of treatment from the patient’s perspective. In this context we sought to establish the role of the generic SF-36 health survey in measuring outcomes from spinal surgery.

Method: A prospective observational study of patients undergoing elective cervical discectomy, lumbar discectomy, and lumbar laminectomy using both disease specific (Myelopathy Disability Index [MDI], Roland Morris Disability Scale [RMDS], Visual Analogue Scales [VAS], Hospital Anxiety and Depression Scales [HADS]) and SF-36 assessment pre-operatively and at 3 months and 12–24 months following surgery. The generic instrument was tested for the components of construct validity in comparison to the established specific measures. Analysis was performed with non-parametric statistics within SPSS.

Results: Six-hundred and twenty patients were followed between 1998 and 2005 (median age 53 years; 203 lumbar discectomy, 177 lumbar laminectomy, 240 cervical discectomy). The principal SF-36 physical domains (Physical Functioning, Bodily Pain) strongly correlated with disease specific scores in all patients (Spearman’s ρ=0.5–0.74, p< 0.001) and similarly SF-36 mental domains correlated with the HADS subscales (ρ=0.30–0.45, p< 0.001) indicating concurrent/convergent validity. Discriminant validity was confirmed by the absence of significant correlation between SF-36 physical domains and the HADS (ρ=0.014–0.14, p> 0.05). In the lumbar laminectomy and cervical discectomy patients disease-specific physical scores prior to surgery strongly predicted early and late outcome (area under the receiver-operating characteristics curve [AUC] = 0.79–0.86, p< 0.001) and the same pattern was mirrored in the SF-36 physical domains (AUC = 0.76–0.78, p< 0.001) demonstrating the predictive validity of the generic measure. Physical Function and Bodily Pain SF-36 domains both had excellent response to change by Cohen’s criteria with effect sizes (standardised mean difference) of 0.86–1.57.

Conclusion: The SF-36 has been shown to possess the necessary features of construct validity in relation lumbar and cervical surgery to be considered as a suitable adjunct or alternative to measuring outcome with disease specific scores. As a widely employed HRQoL instrument the SF-36 should be a convenient means of assessing patients with spinal morbidity in all healthcare settings and the generic measure will permit easier comparison of the clinical and economic efficacy of different interventions.

Back pain screening clinics are established to clinically screen patients with back pain for organic lumbar pathology. The aim of this study is to assess the relationship between clinical signs of organic pathology and the level of disability as measured by functional outcome scores. Methods: Notes from 581 consecutive patients who were seen in the back screening clinic was analyzed. Sixty-nine patients who were found to have clinical signs of organic pathology and 69 age and sex-matched patients from 512 patients who were found to have no signs of organic pathology in the same time period in the back pain screening clinic were selected. The Oswestry disability, Short form-36 and visual analogue (pain) scores between the two groups were statistically analyzed.

The correlation between the level of psychological morbidity, length of symptoms and presence of past history of symptoms against the level of disability was statistically assessed. Results: Although there was a signiþcant increase in the level of disability in the referred group with each score (Oswestry Disability Score P< 0.001, SF-36 physical component score P=0.014, Visual analogue pain score P< 0.001). We also found a strong relationship between psychological disability and the duration of back symptoms. Conclusions: High level of disability is associated with organic pathology. Acute back pain should be treated promptly to reduce it impact on the psychological disability.

Introduction. Treatment of spinal metastatic disease has evolved with the advent of advanced interventional, surgical and radiation techniques. Spinal Oligometastatic disease is a low volume disease state where en bloc resection of the tumour, based on oncological principles, can achieve maximum local control (MLC). Hybrid therapy incorporating Separation surgery (>2mm clearance of the thecal sac) and Stereotactic Ablative Radiotherapy (SABR) offer an alternative approach to achieving MLC. Hybrid therapy is also a viable option in patients eligible for SBRT who have failed conventional radiation therapy. En-bloc surgery may be a suitable option for those patients who are ineligible for or have failed SBRT. A multidisciplinary approach is particularly important in the decision-making process for these patients. Metal free instrumentation is aiding the optimization of these surgeries. The authors present a supra-regional centre's experience in managing spinal oligometastases. Methods. Retrospective review of oligometastatic spinal disease at a supra-regional centre between 2017 and 2021. Demographics, operative course, complications and Instrument type are examined. Results. Demographics: 24 patients with mean age 53.8y (range 12–77), 44% (40y–59y), 40% (60y–69y); 51% Male. Histology: Breast, Renal and Sarcoma accounted for 16.7% each; Thyroid, Prostate and Chordoma accounted for 8.3% each. Primary disease 7%, Synchronous 15%, Metachronous 78%. Instrumentation: Carbon-fibre (85%), TiAl (11%), Non-Instrumented (3%). Separation Surgery (70%), En-bloc resection/Tomita surgery (30%); SABR/Proton Beam Planned: 70%. Average length of hospital stays 19.1 days; twenty patients required intensive care admission for an average 2.7 days. 30 Day Mortality 8.3% (n=2: COVID-19 during admission and ventriculitis post discharge), 1y Mortality – 16.7%, 3y Mortality – 25%; Synchronous Mortality 75% (n=3) at 3 years. 30 Day infection rate 3%; 1y infection rate 7%. 1 Non-instrumented case developed proximal junctional failure post proton beam therapy and required a vascularised fibular strut graft. 2-year Revision for Local Recurrence 5% (Revision at 23 months). Conclusion. There are very few case series of oligometastatic spinal disease due to the relatively new concept of adjuvant SABR and its limited availability. Solid tumours pre-dominated the histology in our series with metachronous disease being the most commonly operated disease state. 92% of cases were eligible for SABR. The majority (85%) of cases were performed with Carbon-fibre instrumentation and has been shown to be safe with no mechanical failures in this series. Infection rates are in keeping with patients requiring radical radiotherapy with 3% early and 7% late. 30-day mortality was 8.3%, 1y=16.7% and 25% at last follow up. Mortality, as expected, is highest within the synchronous disease group and should be operated on sparingly. With the current management strategy, there was no local recurrence at 1 year and excellent local recurrence rate at 2 years (5%). Although radical en bloc surgery carries significant morbidity, it should be considered in selective cases to achieve MLC. All Oligometastatic cases deserve extra consideration and specialist MDT as not all are suitable for SABR. Multimodal Hybrid therapy, incorporating less invasive surgical techniques and SABR, represents a paradigm shift in achieving MLC in oligometastatic spinal disease

During the pandemic of COVID-19, some patients with COVID-19 may need emergency surgeries. As spine surgeons, it is our responsibility to ensure appropriate treatment to the patients with COVID-19 and spinal diseases. A protocol for spinal surgery and related management on patients with COVID-19 has been reviewed. Patient preparation for emergency surgeries, indications, and contraindications of emergency surgeries, operating room preparation, infection control precautions and personal protective equipments (PPE), anesthesia management, intraoperative procedures, postoperative management, medical waste disposal, and surveillance of healthcare workers were reviewed. It should be safe for surgeons with PPE of protection level 2 to perform spinal surgeries on patients with COVID-19. Standardized and careful surgical procedures should be necessary to reduce the exposure to COVID-19

Spinal diseases such as unstable fractures, infections, primary or secondary tumors or deformities require surgical stabilization with implants. The long-term success of this treatment is only ensured by a solid bony fusion. The size of the bony defect, the often poor bone quality and metabolic diseases increase the risk of non-union and make the case a great burden for the patient and a challenge for the surgeon. The goal of spinal fusion can only be achieved if the implants used offer sufficient mechanical stability and the local biological regeneration potential is large enough to form sufficient bone. The lecture will present challenging clinical cases. In addition, implant materials and new surgical techniques are discussed. Local therapeutic effects are achieved through the release of osteopromotive or anti-resorbtive drugs, growth factors and antibiotics. By influencing biological pathways, basic orthopedic research has strong potential to further positively change future spinal surgery

Several different algorithms attempt to estimate life expectancy for patients with metastatic spine disease. The Skeletal Oncology Research Group (SORG) has recently developed a nomogram to estimate survival of patients with metastatic spine disease. Whilst the use of the SORG nomogram has been validated in the international context, there has been no study to date that validates the use of the SORG nomogram in New Zealand. This study aimed to validate the use of the SORG nomogram in Aotearoa New Zealand. We collected data on 100 patients who presented to Waikato Hospital with a diagnosis of spinal metastatic disease. The SORG nomogram gave survival probabilities for each patient at each time point. Receiver Operating Characteristic (ROC) Area Under Curve (AUC) analysis was performed to assess the predictive accuracy of the SORG score. A calibration curve was also performed, and Brier scores calculated. A multivariate Cox regression analysis was performed. The SORG score was correlated with 30 day (AUC = 0.72) and 90-day mortality (AUC = 0.71). The correlation between the SORG score and 90-day mortality was weaker (AUC = 0.69). Using this method, the nomogram was correct for 79 (79%) patients at 30-days, 59 patients (59%) at 90-days, and 42 patients (42%) at 365-days. Calibration curves demonstrated poor forecasting of the SORG nomogram at 30 (Brier score = 0.65) and 365 days (Brier score = 0.33). The calibration curve demonstrated borderline forecasting of the SORG nomogram at 90 days (Brier score = 0.28). Several components of the SORG nomogram were not found to be correlated with mortality. In this New Zealand cohort the SORG nomogram demonstrated only acceptable discrimination at best in predicting life 30-, 90- or 356-day mortality in patients with metastatic spinal disease

Pelvic tilt can vary over time due to aging and the possible appearance of sagittal spine disorders. Cup position in total hip arthroplasty (THA) can be influenced due to these changes. We assessed the evolution of pelvic tilt and cup position after THA and the possible appearance of complications for a minimum follow-up of ten years. 343 patients received a THA between 2006 and 2009. All were diagnosed with primary osteoarthritis and their mean age was 63.3 years (range, 56 to 80). 168 were women and 175 men. 250 had no significant lumbar pathology, 76 had significant lumbar pathology and 16 had lumbar fusion. Radiological analysis included sacro-femoral-pubic (SFP), acetabular abduction (AA) and anteversion cup (AV) angles. Measurements were done pre-operatively and at 6 weeks, and at five and ten years post-operatively. Three measurements were recorded and the mean obtained at all intervals. All radiographs were evaluated by the same author, who was not involved in the surgery. There were nine dislocations: six were solved with closed reduction, and three required cup revision. All the mean angles changed over time; the SFP angle from 59.2º to 60º (p=0.249), the AA angle from 44.5º to 46.8º (p=0.218), and the AV angle from 14.7º to 16.2º (p=0.002). The SFP angle was lower in older patients at all intervals (p<0.001). The SFP angle changed from 63.8 to 60.4º in women and from 59.4º to 59.3º in men, from 58.6º to 59.6º (p=0.012). The SFP angle changed from 62.7º to 60.9º in patients without lumbar pathology, from 58.6º to 57.4º in patients with lumbar pathology, and from 57.0º to 56.4º in patients with a lumbar fusion (p=0.919). The SFP cup angle was higher in patients without lumbar pathology than in the other groups (p<0.001), however, it changed more than in patients with lumbar pathology or fusion at ten years after THA (p=0.04). Posterior pelvic tilt changed with aging, influencing the cup position in patients after a THA. Changes due to lumbar pathology could influence the appearance of complications long-term

Background. Carbon fibre (CF) instrumentation is known to be radiolucent and has a tensile strength similar to metal. A specific use could be primary or oligometastatic cancer where regular surveillance imaging and Stereotactic Radiotherapy are required. CT images are inherently more prone to artefacts which affect Hounsfield unit (HU) measurements. Titanium (Ti) screws scatter more artefacts. Until now it has been difficult to quantify how advantageous the radiolucency of carbon fibre pedicle screws compared to titanium or metallic screws actually is. Methodology. In this retrospective study, conducted on patients from 2018 to 2020 in SGH, we measured the HU to compare the artifact produced by CF versus Ti pedicle screws and rods implanted in age and sex matched group of patients with oligometastatic spinal disease. Results. Eleven patients were included in each group. We compared the change of HU between preoperative and postoperative cases of both CF & Ti screws, which clearly shows Ti screws scatter lot more artefacts than CF screws. We are proposing a CT artefact grading system from grade 0 to grade 4 based on the percentage change of HU for unequivocal understanding of the CT artefacts. Conclusion. This study clearly shows the artefacts produced by the metallic implants are significantly higher than the carbon fibre implants. Considering the efficacy of the RT and the increased life expectancy as a consequence, carbon instrumentation MAY BE superior to titanium or metallic instrumentation. The artefact grading system will help the clinicians in describing and planning where the artefacts need to be factorized

Introduction. Instability remains a common complication following total hip arthroplasty (THA) and continues to account for the highest percentage of revisions in numerous registries. Many risk factors have been described, yet a patient-specific risk assessment tool remains elusive. The purpose of this study was to apply a machine learning algorithm to develop a patient-specific risk score capable of dynamic adjustment based on operative decisions. Methods. 22,086 THA performed between 1998–2018 were evaluated. 632 THA sustained a postoperative dislocation (2.9%). Patients were robustly characterized based on non-modifiable factors: demographics, THA indication, spinal disease, spine surgery, neurologic disease, connective tissue disease; and modifiable operative decisions: surgical approach, femoral head size, acetabular liner (standard/elevated/constrained/dual-mobility). Models were built with a binary outcome (event/no event) at 1-year and 5-year postoperatively. Inverse Probability Censoring Weighting accounted for censoring bias. An ensemble algorithm was created that included Generalized Linear Model, Generalized Additive Model, Lasso Penalized Regression, Kernel-Based Support Vector Machines, Random Forest and Optimized Gradient Boosting Machine. Convex combination of weights minimized the negative binomial log-likelihood loss function. Ten-fold cross-validation accounted for the rarity of dislocation events. Results. The 1-year model achieved an area under the curve (AUC)=0.63, sensitivity=70%, specificity=50%, positive predictive value (PPV)=3% and negative predictive value (NPV)=99%. The 5-year model achieved an AUC=0.62, sensitivity=69%, specificity=51%, PPV=7% and NPV=97%. All cohort-level accuracy metrics performed better than chance. The two most influential predictors in the model were surgical approach and acetabular liner. Conclusions. This machine learning algorithm demonstrates high sensitivity and NPV, suggesting screening tool utility. The model is strengthened by a multivariable dataset portending differential dislocation risk. Two modifiable variables (approach and acetabular liner) were the most influential in dislocation risk. Calculator utilization in “app” form could enable individualized risk prognostication. Furthermore, algorithm development through machine learning facilitates perpetual model performance enhancement with future data input

Cervical spinal arthrodesis is the standard of care for the treatment of spinal diseases induced neck pain. However, adjacent segment disease (ASD) is the primary postoperative complication, which draws great concerns. At present, controversy still exists for the etiology of ASD. Knowledge of cervical spinal loading pattern after cervical spinal arthrodesis is proposed to be the key to answer these questions. Musculoskeletal (MSK) multi-body dynamics (MBD) models have an opportunity to obtain spinal loading that is very difficult to directly measure in vivo. In present study, a previously validated cervical spine MSK MBD model was developed for simulating cervical spine after single-level anterior arthrodesis at C5-C6 disc level. In this cervical spine model, postoperative sagittal alignment and spine rhythms of each disc level, different from normal healthy subject, were both taken into account. Moreover, the biomechanical properties of facet joints of adjacent levels after anterior arthrodesis were modified according to the experimental results. Dynamic full range of motion (ROM) flexion/extension simulation was performed, where the motion data after arthrodesis was derived from published in-vivo kinematic observations. Meanwhile, the full ROM flexion/extension of normal subject was also simulated by the generic cervical spine model for comparative purpose. The intervertebral compressive and shear forces and loading-sharing distribution (the proportions of intervertebral compressive and shear force and facet joint force) at adjacent levels (C3-C4, C4-C5 and C6-C7 disc levels) were then predicted. By comparison, arthrodesis led to a significant increase of adjacent intervertebral compressive force during the head extension movement. Postoperative intervertebral compressive forces at adjacent levels increased by approximate 20% at the later stage of the head extension movement. However, there was no obvious alteration in adjacent intervertebral compressive force, during the head flexion movement. For the intervertebral shear forces in the anterior-posterior direction, no significant differences were found between the arthrodesis subject and normal subject, during the head flexion/extension movement. Meanwhile, cervical spinal loading-sharing distribution after anterior arthrodesis was altered compared with the normal subject's distribution, during the head extension movement. In the postoperative loading-sharing distribution, the percentage of intervertebral disc forces was further increased as the motion angle increased, compared with normal subject. In conclusion, cervical spinal loading after anterior arthrodesis was significantly increased at adjacent levels, during the head extension movement. Cervical spine musculoskeletal MBD model provides an attempt to comprehend postoperative ASD after anterior arthrodesis from a biomechanical perspective

Introduction. Pelvic tilt can vary over time due to aging and the possible appearance of sagittal spine disorders. Cup position in total hip arthroplasty (THA) can be influenced due to these changes. We assessed the evolution of pelvic tilt and cup position after THA and the possible appearance of complications for a minimum follow-up of ten years. Materials and methods. 343 patients received a cementless THA between 2006 and 2009. All were diagnosed with primary osteoarthritis and their mean age was 63.3 years (range, 56 to 80). 168 were women and 175 men. 250 had no significant lumbar pathology, 76 had significant lumbar pathology and 16 had lumbar fusion. Radiological analysis included sacro-femoral-pubic (SFP), acetabular abduction (AA) and anteversion cup (AV) angles. Measurements were done pre-operatively and at 6 weeks, and at five and ten years post-operatively. Three measurements were recorded and the mean obtained at all intervals. All radiographs were evaluated by the same author, who was not involved in the surgery. Results. There were nine dislocations: six were solved with closed reduction, and three required cup revision. All the mean angles changed over time; the SFP angle from 59.2º to 60º (p=0.249), the AA angle from 44.5º to 46.8º (p=0.218), and the AV angle from 14.7º to 16.2º (p=0.002). The SFP angle was lower in older patients at all intervals (p<0.001). The SFP angle changed from 63.8 to 60.4º in women and from 59.4º to 59.3º in men, from 58.6º to 59.6º (p=0.012). The SFP angle changed from 62.7º to 60.9º in patients without lumbar pathology, from 58.6º to 57.4º in patients with lumbar pathology, and from 57.0º to 56.4º in patients with a lumbar fusion (p=0.919). The SFP cup angle was higher in patients without lumbar pathology than in the other groups (p<0.001), however, it changed more than in patients with lumbar pathology or fusion at ten years after THA (p=0.04). Conclusions. Posterior pelvic tilt changed with aging, influencing the cup position in patients after a THA. Changes due to lumbar pathology could influence the appearance of complications at mid and long-term

Introduction. Although pelvic tilt does not significantly change after primary total hip arthroplasty (THA) at a short term, can vary over time due to aging and the possible appearence of sagittal spine disorders. Cup positioning relative to the stem can be influenced due to these changes. Purpose. We assessed the evolution of pelvic tilt and cup position after THA for a minimum follow-up of five years and the possible appearence of complications. Materials and methods. 47 patients underwent same single THA between 2008 and 2012. All were diagnosed with primary osteoarthritis and their mean age was 70.2 years (range, 63 to 75). There were 28 male patients, 19 had a contralateral THA, 17 were studied for lumbar pathology and three were operated for lumbo-sacral fusion. Radiological analysis included sacro- femoral-pubic and acetabular abduction angles on the anteroposterior pelvic view; and cup anteversion angle on the lateral cross-table hip view according to Woo and Morrey. All assessments were done pre-operatively and at 6 weeks, one, two and five years post-operatively. Three measurements were recorded and mean was obtained at all intervals All radiographs were evaluated by the same author, who was not involved in surgery. Results. There were four dislocations: one early and two contralateral dislocations which were solved wiith closed reduction, and one late recurrent dislocation five years after surgery which required cup revision. No other revision surgeries were performed. Mean sacro-femoral pubic angle decreased at all intervals from 60.6º preoperatively, to 60.0º at one year and 58.8 º at five years. This decrease was more significant in female, 63.3º preoperatively to 59.3º, than in male patients, 58.7º to 58.3º at five years. Mean acetabular abduction angle increased from 47.3º at 6 weeks to 48.2º at five years. Mean cup anteversion increased from 24.3º at 6 weeks to 26.4º at one year and 34.3º at five years. Conclusions. Posterior pelvic tilt increased with aging over time, particularly in women. These changes increased cup inclination and anteversion which may result in more dislocations after primary THA

Purpose: Analysis of the sagittal balance of the spine is a fundamental step in understanding spinal disease and proposing appropriate treatment. The objectives of this prospective study were to establish the physiological values of pelvic and spinal parameters of sagittal spinal balance and to study their interrelations. Material and methods: Two hundred fifty lateral views of the spine taken in the standing position and including the head, the spine and the pelvis were studied. The following variables were noted: lumbar lordosis, thoracic kyphosis, sagittal tilt at 9, sacral slope, pelvic incidence, pelvic version, intervertebral angle, and the vertebral wedge angle from T9 to S1. These measures were taken after digitalising the x-rays. Two types of analysis were performed. A descriptive univariate analysis was used to characterise angular parameters and a multivariate analysis (correlation, principal component analysis) was used to compare interrelations between the variables and determine how economic balance is achieved. Results and discussion: Mean angular values were: maximal lumbar lordosis 61±12.7°, maximal thoracic kyphosis 41.4±9.2°, sacral slope 42±8.5°, pelvic version 13±6°, pelvic incidence 55±11.2°, sagittal tilt at T9 10.5±3.1°. There was a strong correlation between sacral slope and pelvic incidence (r=0.8), lumbar lordosis and sacral slope (r=0.86), pelvic version and pelvic incidence (r=0.66), lumbar lordosis pelvic incidence pelvic version and thoracic kyphosis (r=0.9), and finally between pelvic incidence and sagittal tilt at T9, sacral slope, pelvic version, lumbar lordosis, and thoracic kyphosis (r=0.98). Multivariate analysis demonstrated three independent parameters influencing sagittal tilt at T9, reflecting the lateral balance of the spine. The first was a linear combination of the pelvic incidence, lumbar lordosis and sacral slope. The second was pelvic version and the third thoracic kyphosis. Conclusion: This work provides an aid for analysis and comprehension of anteroposterior imbalance observed in spinal disease and also to calculate with the linear regression equations describing the corrections to be obtained with treatment

Patients may present with concurrent symptomatic hip and spine problems, with surgical treatment indicated for both. Controversy exists over which procedure, total hip arthroplasty (THA) or lumbar spine procedure, should be performed first. Clinical scenarios were devised for 5 fictional patients with both symptomatic hip and lumbar spine disorders for which surgical treatment was indicated. An email with survey link was sent to 110 clinical members of the NA Hip Society requesting responses to: which procedure should be performed first; the rationale for the decision with comments, and the type of THA prosthesis if “THA first” was chosen. The clinical scenarios were painful hip osteoarthritis and (1) lumbar spinal stenosis with neurologic claudication; (2) lumbar degenerative spondylolisthesis with leg pain; (3) lumbar disc herniation with leg weakness; (4) lumbar scoliosis with back pain; and (5) thoracolumbar disc herniation with myelopathy. Surgeon choices were compared among scenarios using chi-square analysis and comments analyzed using text mining. Complete responses were received from 51 members (46%), with a mean of 30.8 (± 10.4) years of practice experience. The percentages of surgeons recommending “THA first” were 59% for scenario 1; 73% for scenario 2; 47% for scenario 3; 47% for scenario 4; and 10% for scenario 5 (χ. 2. =44.5, p<0.001). Surgeons were significantly more likely to choose “THA first” despite radicular leg pain (scenario 2), and less likely to choose “THA first” with the presence of myelopathy (scenario 5). The choice of “THA first” in scenarios 1, 3, and 4 were more equivocal, dependent on surgeon impression of clinical severity. For type of THA prosthesis, dual mobility component was chosen by: 12% in scenario 1; 16% in scenario 2; 8% in scenario 3; 24% in scenario 4; and 10% in scenario 5. Surgeons were more likely to choose dual mobility in scenario 4, but with the numbers available this was not statistically significant (χ. 2. =6.6, p=0.16). The analysis of comments suggested the importance of injection of the joint for decision making, the merit of predictable outcome with THA first, the concern of THA position with spinal deformity, and the urgency of myelopathy. With the presence of concurrent hip and spine problems, the question of “THA or lumbar surgery first” remains controversial even for a group of experienced hip surgeons. Outcome studies of these patients are necessary for appropriate decision making