The aim of this study was to determine whether obesity affects pain, surgical and functional outcomes following lumbar spinal fusion for low back pain (LBP). A systematic literature review and meta-analysis was made of those studies that compared the outcome of lumbar spinal fusion for LBP in obese and non-obese patients. A total of 17 studies were included in the meta-analysis. There was no difference in the pain and functional outcomes. Lumbar spinal fusion in the obese patient resulted in a statistically significantly greater intra-operative blood loss (weighted mean difference: 54.04 ml; 95% confidence interval (CI) 15.08 to 93.00; n = 112; p = 0.007) more complications (odds ratio: 1.91; 95% CI 1.68 to 2.18; n = 43858; p < 0.001) and longer duration of surgery (25.75 mins; 95% CI 15.61 to 35.90; n = 258; p < 0.001). Obese patients have greater intra-operative blood loss, more complications and longer duration of surgery but pain and functional outcome are similar to non-obese patients. Based on these results, obesity is not a contraindication to lumbar spinal fusion. Cite this article: Bone Joint J 2015;97-B:1395–1404

Aims. People with severe, persistent low back pain (LBP) may be offered lumbar spine fusion surgery if they have had insufficient benefit from recommended non-surgical treatments. However, National Institute for Health and Care Excellence (NICE) 2016 guidelines recommended not offering spinal fusion surgery for adults with LBP, except as part of a randomized clinical trial. This survey aims to describe UK clinicians’ views about the suitability of patients for such a future trial, along with their views regarding equipoise for randomizing patients in a future clinical trial comparing lumbar spine fusion surgery to best conservative care (BCC; the FORENSIC-UK trial). Methods. An online cross-sectional survey was piloted by the multidisciplinary research team, then shared with clinical professional groups in the UK who are involved in the management of adults with severe, persistent LBP. The survey had seven sections that covered the demographic details of the clinician, five hypothetical case vignettes of patients with varying presentations, a series of questions regarding the preferred management, and whether or not each clinician would be willing to recruit the example patients into future clinical trials. Results. There were 72 respondents, with a response rate of 9.0%. They comprised 39 orthopaedic spine surgeons, 17 neurosurgeons, one pain specialist, and 15 allied health professionals. Most respondents (n = 61,84.7%) chose conservative care as their first-choice management option for all five case vignettes. Over 50% of respondents reported willingness to randomize three of the five cases to either surgery or BCC, indicating a willingness to participate in the future randomized trial. From the respondents, transforaminal interbody fusion was the preferred approach for spinal fusion (n = 19, 36.4%), and the preferred method of BCC was a combined programme of physical and psychological therapy (n = 35, 48.5%). Conclusion. This survey demonstrates that there is uncertainty about the role of lumbar spine fusion surgery and BCC for a range of example patients with severe, persistent LBP in the UK. Cite this article: Bone Jt Open 2024;5(7):612–620

Aims. Lumbar fusion is known to reduce the variation in pelvic tilt between standing and sitting. A flexible lumbo-pelvic unit increases the stability of total hip arthroplasty (THA) when seated by increasing anterior clearance and acetabular anteversion, thereby preventing impingement of the prosthesis. Lumbar fusion may eliminate this protective pelvic movement. The effect of lumbar fusion on the stability of total hip arthroplasty has not previously been investigated. Patients and Methods. The Medicare database was searched for patients who had undergone THA and spinal fusion between 2005 and 2012. PearlDiver software was used to query the database by the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) procedural code for primary THA and lumbar spinal fusion. Patients who had undergone both lumbar fusion and THA were then divided into three groups: 1 to 2 levels, 3 to 7 levels and 8+ levels of fusion. The rate of dislocation in each group was established using ICD-9-CM codes. Patients who underwent THA without spinal fusion were used as a control group. Statistical significant difference between groups was tested using the chi-squared test, and significance set at p < 0.05. Results. At one-year follow-up, 14 747 patients were found to have had a THA after lumbar spinal fusion (12 079 1 to 2 levels, 2594 3 to 7 levels, 74 8+ levels). The control group consisted of 839 004 patients. The dislocation rate in the control group was 1.55%. A higher rate of dislocation was found in patients with a spinal fusion of 1 to 2 levels (2.96%, p < 0.0001) and 3 to 7 levels (4.12%, p < 0.0001). Patients with 3 to 7 levels of fusion had a higher rate of dislocation than patients with 1 to 2 levels of fusion (odds ratio (OR) = 1.60, p < 0.0001). When groups were matched for age and gender to the unfused cohort, patients with 1 to 2 levels of fusion had an OR of 1.93 (95% confidence interval (CI) 1.42 to 2.32, p < 0.001), and those with 3 to 7 levels of fusion an OR of 2.77 (CI 2.04 to 4.80, p < 0.001) for dislocation. Conclusion. Patients with a previous history of lumbar spinal fusion have a significantly higher rate of dislocation of their THA than age- and gender-matched patients without a lumbar spinal fusion. Cite this article: Bone Joint J 2017;99-B:585–91

Aims. As the population ages and the surgical complexity of lumbar spinal surgery increases, the preoperative stratification of risk becomes increasingly important. Understanding the risks is an important factor in decision-making and optimizing the preoperative condition of the patient. Our aim was to determine whether the modified five-item frailty index (mFI-5) and nutritional parameters could be used to predict postoperative complications in patients undergoing simple or complex lumbar spinal fusion. Methods. We retrospectively reviewed 584 patients who had undergone lumbar spinal fusion for degenerative lumbar spinal disease. The 'simple' group (SG) consisted of patients who had undergone one- or two-level posterior lumbar fusion. The 'complex' group (CG) consisted of patients who had undergone fusion over three or more levels, or combined anterior and posterior surgery. On admission, the mFI-5 was calculated and nutritional parameters collected. Results. Complications occurred in 9.3% (37/396) of patients in the SG, and 10.1% (19/167) of patients in the CG. In the SG, the important predictors of complications were age (odds ratio (OR) 1.036; p = 0.002); mFI-5 (OR 1.026 to 2.411, as score increased to 1 ≥ 2 respectively. ;. p = 0.023); albumin (OR 11.348; p < 0.001); vitamin D (OR 2.185; p = 0.032); and total lymphocyte count (OR 1.433; p = 0.011) . In the CG, the predictors of complications were albumin (OR 9.532; p = 0.002) and vitamin D (OR 3.815; p = 0.022). Conclusion. The mFI-5 and nutritional status were effective predictors of postoperative complications in the SG, but only nutritional status was successful in predicting postoperative complications in the CG. The complexity of the surgery, as well as the preoperative frailty and nutritional status of patients, should be considered when determining if it is safe to proceed with lumbar spinal fusion. Cite this article: Bone Joint J 2020;102-B(12):1717–1722

Aims. Total hip arthroplasty (THA) patients undergoing or having a prior lumbar spine fusion (LSF) have an increased risk of mechanical complications. The aim of this registry-based, retrospective comparative cohort study is to assess the longer term survival of THA in patients who have undergone a LSF during a 17-year period (2000 to 2017). Methods. A registry-based population study was conducted on 679 patients who underwent both THA and LSF surgeries. Patients were identified from the regional arthroplasty data base and cross linked to patients with LSF from the regional hospital discharge database between 2000 and 2017. Demographic data, diagnosis leading to primary THA, primary implant survival, perioperative complications, number and causes of failure, and patients requiring revision arthroplasty were collated and compared. For comparison, data from 67,919 primary THAs performed during the same time time period were also retrieved and analyzed. Results. Patients undergoing THA and LSF showed homogeneous demographic data compared to those undergoing THA alone, but a significantly lower eight-year THA implant survival (96.7 vs 96.0, p = 0.024) was observed. Moreover, THA plus LSF patients showed increased incidence of mechanical complications in the first two years after THA surgery compared to THA alone patients. Conclusion. This registry-based population study shows that approximately 679 (1%) THA patients were subjected to LSF. Patients undergoing THA and LSF have an increased risk of mechanical complications with their THA and a slightly increased risk of revision arthroplasty. Cite this article: Bone Joint J 2021;103-B(3):486–491

Introduction. There is growing evidence that patients with lumbar spine fusion are at greater risk for postoperative dislocation following total hip arthroplasty. The purpose of this study is to review one author's experience with the modified direct lateral approach in patients with prior or subsequent lumbar spine fusion and total hip arthroplasty. Methods. Our IRB approved clinical database was queried for all primary total hip arthroplasties performed by the senior author from 1/1/2004 to 12/31/2016. All were performed via a modified direct lateral approach. Of these 1902 hips (1656 patients), 59 were identified in our medical records as patients who had a prior spine fusion or a spine fusion following THA. The extent of fusion was identified and reported. Radiographs were reviewed for acetabular position (abduction and anteversion) and leg length discrepancies. Records were reviewed and patients were contacted to determine if there were dislocations. Results. Of the 59 patients with concomitant spine fusion and total hip arthroplasty, 47 had the fusion prior to THA and 12 following THA. All patients were seen in the office or contacted by phone for a mean follow up of 5.8 years (2 to 15 years)(3 deceased, 3 lost). The direct lateral approach was used in all cases and in no cases was a dual mobility, lipped liner, or constrained component used. Head size ranged from 32 to 40. There were no postoperative dislocations in any of these patients. Acetabular position was a mean 43.6 degrees abduction (range 30–50), and a mean anteversion of 23.7 degrees (range 17 – 34). Average postoperative LLD was 2.8mm long on operated side (range −2mm to + 12mm). Spine fusion extent was a mean 2.1 levels (range 1 – 9) with 15 that included the sacrum/pelvis. Discussion. As surgeons have become aware of the elevated risk of hip dislocation associated with spine fusion/stiffness, several approaches have been proposed to address this risk. Our findings suggest that using the modified direct lateral approach for primary total hip arthroplasty significantly reduces the risk of such a complication. For any tables or figures, please contact the authors directly

Chronic low back pain (CLBP) is the most common cause of disability worldwide, and lumbar spine fusion (LSF) is often chosen to treat pain caused by advanced degenerative disease when clinical treatment failed certain cases, the post-surgical outcomes are not what was expected. Several studies highlight how important are. In psychological variables during the postoperative spine surgery period. The aim of this study is to assess the role of preoperative depression on postoperative clinical outcomes. We included patients who underwent LSF since December 2021. Preoperative depression was assessed administering Beck Depression Inventory questionnaire (BDI). And pain and disability were evaluated at 1, 3, and 6 months, administering respectively Visual Analogic Scale (VAS) and Oswestry Disability Index (ODI). As statistical analysis Mann-Whitney test was performed. We included 46 patients, 20 female (43,5%) and 26 male (56,5%) with an average age of 64,2. The population was divided in two groups, fixing the BDI cut-off point at 10. Patients with BDI < 10 points (N=28) had normal mental health status, instead patients with BDI > 10 points (N=16) had depressive disorders. At 3 months patients with healthy mental status reported statistically significant reduction of pain (U = 372,5, p = .006) and improvement of disability but without statistical significancy (U = 318, p = 0,137). At 6 months patients without psychological disease reported statistically significant reduction of pain (U = 342, p = 0,039) and disability (U = 372,5, p = 0,006). This study demonstrates the correlation between pre-existing depressive state and poorer clinical outcomes after spine surgery. These results are consistent with the literature. Therefore, during the surgical decision making it is crucial to take psychological variables into account in order to predict the results after surgery and inform patients on the potential influence of mental status

Biphasic calcium phosphate (BCP) with a characteristic needle-shaped submicron surface topography (MagnetOs) has attracted much attention due to its unique bone-forming ability which is essential for repairing critical-size bone defects such as those found in the posterolateral spine. Previous in vitro and ex-vivo data performed by van Dijk LA and Yuan H demonstrated that these specific surface characteristics drive a favorable response from the innate immune system. This study aimed to evaluate and compare the in vivo performance of three commercially-available synthetic bone grafts, (1) i-FACTOR Putty. ®. , (2) OssDsign. ®. Catalyst Putty and (3) FIBERGRAFT. ®. BG Matrix, with that of a novel synthetic bone graft in a clinically-relevant instrumented sheep posterolateral lumbar spine fusion (PLF) model. The novel synthetic bone graft comprised of BCP granules with a needle-shaped submicron surface topography (MagnetOs) embedded in a highly porous and fibrillar collagen matrix (MagnetOs Flex Matrix). Four synthetic bone grafts were implanted as standalone in an instrumented sheep PLF model for 12 weeks (n=3 bilateral levels per group; levels L2/3 & L4/5), after which spinal fusion was determined by manual palpation, radiograph and µCT imaging (based on the Lenke scale), range-of-motion mechanical testing, and histological and histomorphological evaluation. Radiographic fusion assessment determined bilateral robust bone bridging (Lenke scale A) in 3/3 levels for MagnetOs Flex Matrix compared to 1/3 for all other groups. For µCT, bilateral fusion (Lenke scale A) was found in 2/3 levels for MagnetOs Flex Matrix, compared to 0/3 for i-FACTOR Putty. ®. , 1/3 for OssDsign. ®. Catalyst Putty and 0/3 for FIBERGRAFT. ®. BG Matrix. Fusion assessment for MagnetOs Flex Matrix was further substantiated by histology which revealed significant graft resorption complemented by abundant bone tissue and continuous bony bridging between vertebral transverse processes resulting in bilateral spinal fusion in 3/3 implants. These results show that MagnetOs Flex Matrix achieved better fusion rates compared to three commercially-available synthetic bone grafts when used as a standalone in a clinically-relevant instrumented sheep PLF model

Introduction:. Several reports showed superior fusion rates, as high as 100%, using rhBMP-2 with ALIF cages. This has led to the widespread off-label use of rhBMP-2 in several other lumbar fusion procedures. There is paucity of reports analysing the clinic-radiological outcome of using rhBMP-2 to promote bone union in cases of symptomatic pseudoarthosis following lumbar spine fusion. Methods:. 52 consecutive patients who underwent revision spinal surgery for symptomatic pseudoarthosis utilizing rhBMP-2 between 2008 and 2013 were included in the study. Demographic, and surgical data were collected from medical records. Functional outcomes were recorded using the ODI. All patients had preoperative fine-cut CT scan to confirm pseudoarthosis. Postoperative CT-scan at 6 months was routinely done to confirm fusion. Results:. Average age at time of revision surgery was 54years (range 28–73). Average follow up was 3 years 5 months (range 2–5 years). Overall fusion rate of 92.3% (48/52) was achieved. The average ODI has improved from 56% preoperatively to 49% postoperatively. We had 1 infection case, and 5 complications related to metalwork. One case with neuronal complications was recorded. No rhBMP-2 related complications. There was no record of heterotopic bone formation in the spinal canal or the neuroforamen. Conclusion:. Recombinant BMP-2 is a safe and effective adjunct to revision lumbar spinal fusion surgery to alleviate back pain symptoms from pseudoarthosis. The limitations of the study include: retrospective review, lack of matched cohort utilising iliac crest bone graft, and relatively short follow-up

Background: The major problem achieving lumbar spinal fusion is developing pseudarthrosis. At present the gold standard in achieving fusion is the use of autograft from pelvis or posterior elements of the spine. However the potential limitations of insuffient quantity and donor site morbidity have led to search for bone graft alternatives like DBM which contains osteinductive BMPs. Aims & Methods: A Prospective Randomized Control trial comparing the effectiveness of demineralised Bone Matrix (DBM Putty)/autograft composite with autograft in lumbar spinal fusion. 35 patients were included in the trial; they were randomized to have DBM and autograft on one side, and autograft alone on other side to side. Patients were followed up with interval radiographs for total of 24mons. To date 20 patients have completed minimum 12mons follow up. The mineralization of fusion mass lateral to the instrumentation on each side was graded Absent, Mild (< 50%), Moderate (> 50%) or Complete fusion (100%). The assessment was made by two orthopaedic consultants and a musculoskeletal radiologist who were blinded to graft assignment. Results: The sex distribution was 11:9 male to females with a mean age of 55.2 (21–87 years) and an average follow up of 18mons (12–24mons). Nine patients had single level fusion and the remainder had more than one level fusion. At 12 months on the side of DBM, 15% (6 of 20) had complete fusion, 80% (16 of 20) had moderate fusion, and 5% had no fusion mass. During the same period on the other side, 25% did not show any sign of fusion. There was no correlation with number of levels, age or sex. Conclusions: Osteoinductive properties of DBM would appear to help in achieving early and higher union rates in lumbar spinal fusion. DBM reduces the amount of harvested autograft graft and also minimises the morbidity of donor site complications

Introduction. Patients undergoing primary total hip arthroplasty (THA) with prior lumbar spine fusion (LSF) are at high risk for instability with reported incidence of dislocation as high as 8.3%. The use of dual mobility cups in patients undergoing revision THA, another high risk group, has demonstrated decreased incidence of instability. Purpose of this study was to evaluate the risk of instability in patients undergoing primary THA with a history of prior LSF using dual mobility cups. Methods. This was a multi-center retrospective study with 93 patients undergoing primary THA using a dual mobility cup with prior history of instrumented LSF. The primary outcome investigated was instability. Secondary variables investigated included number of levels fused, approach, length of stay, and other complications. The minimum follow-up time was 1 year since the majority of dislocations occur during first year following the primary THA. Results. There were 56 females and 47 males with average age of 66 years (46–87) and average BMI of 30. Mean follow up was 31 months (range 12 – 124.2). Surgical approach included: posterior (63), direct lateral (15), anterior (11), direct superior (4). 44% had one level fusion, 29% with 2 levels, and 15% with 3 or more levels fused. There were no dislocations or infections in this study group. There was one intraoperative fracture and one DVT. Conclusions. Patients undergoing primary THA with prior LSF are a high risk group with an increased risk for instability due to the loss of normal spino-pelvic relationship. The use of dual mobility cups in a high risk group of patients in this study demonstrated excellent results with no incidence of dislocation. Despite the limitations in this study with varying approaches and multiple sites, the use of dual mobility cups to decrease the incidence of instability in patients with prior LSF appears promising. For any tables or figures, please contact the authors directly

Introduction This review evaluates the clinical outcomes and complications of lumbar spinal fusion procedures for patients with a variety of degenerative disorders. Methods Patients were evaluated with respect to outcome and complications. Further analysis allowed us to compare results in patients who had spinal instrumentation versus in situ fusion. In addition, our patients who underwent primary lumbar fusion were compared with those who underwent revision surgery. One author performed 148 spinal fusion procedures for degenerative disorders between 1990 and 1995. Outcomes were classified using Odom’s Criteria by the co-author. Patients were analyzed in groups so that we could compare primary versus revision procedures and instrumented versus non-instrumented fusions. The 148 patients ranged in age from 22 to 88, with 86 being female. Diagnostic categories included: instability (3%), stenosis (47%), spondylolisthesis (34%), disc herniation (10%), degenerative scoliosis (9%), and spondylosis (4%). Eighty-one patients had primary procedures; 104 patients were instrumented with pedicle screw systems, 127 patients (86%) were fused using iliac crest autograft. Results Fifteen percent of primary patients developed complications compared to 24% of revision patients. Twenty-one percent of instrumented patients developed complications compared to 16% of non-instrumented patients. Transition syndrome developed in 13% of patients following spinal instrumentation. Average follow-up was 49.5 months. Seventy percent of primary patients had good/excellent results compared with 69% for the revision patients. Seventy-two percent of instrumented patients had good/excellent results compared to 65% of non-instrumented patients. Conclusions Our retrospective review suggests that well selected revision surgery patients can have similar outcomes to patients who undergo initial lumbar fusion procedures. Although complications occur more frequently in patients who have revision fusions and/or instrumented fusions, clinical outcomes are similar

Aims: To evaluate the outcome of surgery in patients with lumbar spine degenerative disease or isthmic spon-dylolisthesis. Methods: Lumbar spine fusion with or without decompression was performed in 132 consecutive patients. Altogether 115 patients attended to follow-up an average 3.4 years after operation. The overall result was assessed by the patient and by an independent observer. Moreover, the disability was measured using Oswestry questionnaire and fusion rate was assessed from flexion and extension radiographs. Results: The complications of surgery were: misplacement of screws in 2 patients, paresis of peroneal nerve in 1 patient, superficial wound infection in 4 patients, breakage of fixation device in 1 patient and spinal fluid fistulas in 2 patients. According to patient’s own opinion the result of surgery was excellent, good or fair in 86 percent of the patients and even 89.6% of them benefited from the surgery. The average postoperative Oswestry score was 28. According to radiographs the fusion rate was 93 percent. At the time of operation 40 patients were retaired and 66 (93%) out of the 75 patients who were still at working age returned to work. Conclusion: Lumbar spine fusion is an effective and safe treatment of degenerative lumbar spine disease and isthmic spondylolisthesis. However, the careful selection of patients is an important factor for success

Chronic pain at the donor site was reported by 25% of 290 patients who had undergone anterior lumbar spine fusion for low back pain. Donor site pain has characteristic clinical features, may be severely disabling and is stubbornly resistant to treatment. The highest prevalence was in patients who had a tricortical full thickness graft taken through a separate incision overlying the iliac crest. Patients with a clinically unsatisfactory result from the spine fusion also had a significantly higher prevalence of donor site pain

Purpose: A lack of consensus regarding the radiologic criteria to diagnose spinal non-union limits inferences from clinical research. This systematic review aimed to examine the spectrum of radiologic investigations used to assess lumbar spinal fusion and the definitions of successful spine union used in the spine literature. Method: We comprehensively searched three electronic databases from 1950 to 2009 (MEDLINE, Embase and the Cochrane Central Register of Controlled Trials) for clinical studies involving posterolateral fusion of the lumbar spine. English-language studies including adult patients and reporting a definition of successful fusion were included. Studies examining the reliability and validity of radiologic investigations were also identified. Key measures included. radiologic investigations,. definition of successful lumbar fusion and. reliability, sensitivity and specificity of the investigations used to assess the spinal fusion. Results: Among 1165 potentially eligible studies, 91 met our inclusion criteria. Of the studies 78% (n = 71) used plain radiographs to diagnose non-union, 4% (n = 4) used CT scans and 18% (n = 16) used both. Fifty-one studies used both static (xray or CT) and dynamic (flexion-extension xray) images, 35 used only static images and five used only dynamic radiographs. In total, we identified fifty-two different radiographic definitions of successful fusion. More than half of the studies (n = 50, 55%) failed to provide a reference for the definition used. The most common definition of fusion (7 studies) used static radiographs and defined fusion as continuous intertransverse bony bridging with this quality of fusion at all intended levels. Seven studies evaluated reliability of xray criteria but no studies provided complete validation of the definitions. Only 3 studies provided some validation and reliability estimates of thin-slice CT scanning in diagnosing spinal non-union. Significant variability in reliability, sensitivity and specificity exists for all radiologic investigations in the diagnosis of spinal non-union. Conclusion: The radiologic investigations and definitions of successful posterolateral fusion used in the spine literature vary substantially. Choice of radiologic criteria should be based upon reliability and validity testing. Studies using fusion criteria that have not been shown to be reliable or valid should be interpreted with caution

Introduction. Both intra- and post-operative radiographs are traditionally obtained after instrumented lumbar spinal surgery; however the clinical advantage of routine post operative images has not been demonstrated. Aim. To explore the usefulness of routine pre-discharge postoperative radiographs in patients undergoing instrumented spinal surgery. Methodology. Patients (n = 124) who underwent a lumbar spinal fusion were identified from a retrospective database, 58 patients were excluded. Unaltered intra-operative and pre-discharge post-operative PACS images for 66 patients were reviewed and were scored for: i) Quality (0 = non-diagnostic, 1 = suboptimal, 2 = diagnostic, 3 = good quality), ii) Focus (number of vertebra and disc seen), iii) Centering using a numbered (1–9) grid system, and iv) Rotation. Results. 66 radiographs were analysed for i) Quality: 60 AP and 56 lateral intra-operative images while 57 AP and 39 lateral postoperative images were diagnostic, ii) Focus: average number of unnecessary vertebra seen in intra-operative AP and lateral images were 0.89 and 1.09, while on post-operative AP and lateral images were 8.05 and 6.45 respectively, iii) Centering: 48 AP and 51 lateral intra-operative images, while 27 AP and 20 lateral post-operative images were adequately centered and iv) Rotation was adequate in both intra-operative and post-operative images. Conclusion. Intra-operative images scored higher in all parameters suggesting that routine post-operative pre-hospital discharge radiographs are unnecessary unless specifically indicated and this practice should be discontinued with benefits including reduction of radiation dose (and subsequent sequelae), fiscal burden and length of stay

Objectives. Loss of motion following spine segment fusion results in increased strain in the adjacent motion segments. However, to date, studies on the biomechanics of the cervical spine have not assessed the role of coupled motions in the lumbar spine. Accordingly, we investigated the biomechanics of the cervical spine following cervical fusion and lumbar fusion during simulated whiplash using a whole-human finite element (FE) model to simulate coupled motions of the spine. Methods. A previously validated FE model of the human body in the driver-occupant position was used to investigate cervical hyperextension injury. The cervical spine was subjected to simulated whiplash exposure in accordance with Euro NCAP (the European New Car Assessment Programme) testing using the whole human FE model. The coupled motions between the cervical spine and lumbar spine were assessed by evaluating the biomechanical effects of simulated cervical fusion and lumbar fusion. Results. Peak anterior longitudinal ligament (ALL) strain ranged from 0.106 to 0.382 in a normal spine, and from 0.116 to 0.399 in a fused cervical spine. Strain increased from cranial to caudal levels. The mean strain increase in the motion segment immediately adjacent to the site of fusion from C2-C3 through C5-C6 was 26.1% and 50.8% following single- and two-level cervical fusion, respectively (p = 0.03, unpaired two-way t-test). Peak cervical strains following various lumbar-fusion procedures were 1.0% less than those seen in a healthy spine (p = 0.61, two-way ANOVA). Conclusion. Cervical arthrodesis increases peak ALL strain in the adjacent motion segments. C3-4 experiences greater changes in strain than C6-7. Lumbar fusion did not have a significant effect on cervical spine strain. Cite this article: H. Huang, R. W. Nightingale, A. B. C. Dang. Biomechanics of coupled motion in the cervical spine during simulated whiplash in patients with pre-existing cervical or lumbar spinal fusion: A Finite Element Study. Bone Joint Res 2018;7:28–35. DOI: 10.1302/2046-3758.71.BJR-2017-0100.R1

The success of lumbar spine fusion depends on good patient selection and bone grafting technique. Instrumentation of the fusion, now popular, improves fusion rates, eliminates the need for postoperative braces and allows early mobilisation. However, the stress shielding caused by rigid internal fixation is thought to lead to osteopoenia and degeneration of adjacent segments. Theatre times, intra-operative complications and costs are increased when pedicle screw fixation is added. This is a report of a pilot study of eight patients who had one-level fusion and unilateral instrumentation between 1998 and 2000. Theatre time, fusion rate and functional outcomes were evaluated. The minimum follow-up time was eight months. Fusion was achieved in all patients and there was no metal failure. One patient continued to have back and leg pain in spite of a solid fusion. Although this is a small study undertaken over a short period, the results suggest that unilateral pedicle screw fixation can be safely undertaken

As the population ages, the prevalence of degenerative spinal conditions is estimated to increase. With soaring healthcare costs, we must be vigilant in our accountability for proper resource allocation to ensure universal access. Significant recent increases in lumbar fusion rates have been observed in the US. Less is known regarding the Canadian experience. Our objective was to evaluate recent trends in lumbar fusion and determine how surgeon factors influence reoperation for spinal stenosis (SS) surgery. Longitudinal follow-up study of lumbar surgical procedures for SS using administrative databases. Data was gathered on patient-hospital encounters from April 1, 1995 to December 31, 2001. We analyzed trends in spinal fusion. Index procedures (decompressions or fusions) and surgeon variables, such as specialty (orthopaedics, neurosurgery) and volume (above or below thirty cases/year), were selected as predictors of patient reoperation for SS. Adjustments were made for age, gender, and comorbidity. Reoperation rates were evaluated at six weeks, one and two years and until maximal follow-up. 6128 patients were identified (4200 decompressions and 1928 fusions). Proportionally more fusions were performed over the study period when compared to decompressions (1:2.6 in 1995 versus 1:1.5 in 2001). Orthopaedic specialty and higher surgical volume were associated with increased proportion of fusions (p< 0.0001). Reoperation rate was higher for decompressions at two years (OR 1.4) but not at long-term follow-up to ten years. Surgeon specialty had no impact on reoperation rates. Lower surgical volume demonstrated a higher reoperation rate after adjusting for specialty (Hazard Ratio 1.28). Rates of lumbar spinal fusion have been increasing in Ontario, but at a lesser rate compared with the US. There is wide variation in surgical procedures between surgeon specialty and volume. Surgeon specialty had little impact on reoperation rates. Better long-term survival was observed in spinal surgeons with volumes over thirty cases per year after adjusting for surgeon specialty. Due to increasing rates of spinal fusion, the benefit of improved long-term survival in SS surgery with higher volume surgeons requires more detailed analysis before policy recommendations can be made

Purpose: It is widely agreed that fusion of a spinal segment modifies the mechanical behaviour of sub-jacent vertebrae. The mean centre of rotation (MCR) is defined to study changes in the mechanical behaviour at junctions. This parameter describes the relative movement of an object moving from one position to another. The purpose of this study was to describe changes in the position of the MCR after posterolateral lumbar spine fusion and to determine factors influencing these changes. Material and methods: Fifty-one patients with posterolateral fusion with or without instrumentation of the lumbar spine limited to one or two levels were reviewed. Preoperative and last follow-up stress x-rays of the lumber spine were studied. The following parameters were determined with Spinview, a devoted software, at the level of fusion, at the three suprajacent levels, and when appropriate, at subjacent levels: disc height, intervetebral angular mobility, position of the MCR. Pre and postoperative positions of the MCR were compared with the Wilcoxon test for paired variables. Univariate and multivariate analyses were performed to search for factors influencing changes in the position of the MCR. Variables studied were: age, follow-up, extent of the fusion and its anatomic position, instrumentation, preoperative mobility of the zone to be fused, and quality of the arthrodesis at last follow-up. Results: There were no significant changes in the position of the MCR of the first suprajacent level. Two variables exhibited significant correlation with these changes: pre and postoperative angular mobility of the future zone of fusion, and use of instrumentation. Instrumentation significantly increased variability in the position of the MCR. Postoperative mobility of the zone of fusion minimised this variability. Discussion: Studying variations in the position of the MCR appears to reflect well changes in the mechanical behaviour of levels adjacent to the spinal fusion. Use of appropriate software should be helpful for routine applications. In our series, changes in the position of the MCR correlated well with significant increase in angular and anteroposterior mobility and also with decreased disc height at the first suprajacent level. These observations explain early degradation of junction zones observed after arthrodesis