Introduction. Herniation pits had been considered as a normal variant, a cystic lesion formed by synovial invagination. On the contrary, it was also suggested that herniation pits were one of the diagnostic findings in femoroacetabular impingement (FAI) because of the high prevalence of herniation pits in the FAI patients. To date, the exact etiology is still unknown. The purpose of this study was to evaluate whether there is an association between the presence of herniation pits and morphological indicators of FAI based on computed tomography (CT) examination. Materials and methods. We reviewed the CT scans of 245 consecutive subjects (490 hips, age: 21–89 years) who had undergone abdominal and pelvic CT for reasons unrelated to hip symptom from September, 2010 to June, 2011. These subjects were mainly examined for abdominal disorders. We confirmed by the questionnaire survey that there were no subjects who had symptoms of hip joints. We reviewed them for the presence of herniation pits and the morphological abnormalities of the femoral head and acetabulum. Herniation pits were diagnosed when they were located at the anterosuperior femoral head-neck junction with a diameter of more than 3 mm. We measured following four signs as indicators for FAI: α angle, center edge angle (CE angle), acetabular index (AI), and acetabular version. Mann-Whitney U-test was used for statistical analysis. Results. Herniation pits were identified in 61 of the 245 subjects or, with respect to individual hips, in 85 (17%) of 490 hips. The prevalence of herniation pits in younger subjects (<60 years, 240 hips) and elderly subjects (≥60 years, 250 hips) were 16.3% and 18.4%, respectively. Among 85 hips, the mean diameter of herniation pits was 5.9 ± 2.4 mm and it was significantly larger (p<0.01) in the elderly subjects (7.1 ± 2.4 mm) than in the younger subjects (4.7 ± 1.7 mm). In terms of the α angle, there were significant differences between the group with (49.8 ± 16.6°) and without herniation pits (40.7 ± 6.7°) in the elderly subjects, whereas not significantly different among the younger subjects. Measurements of the acetabular coverage (CE angle, AI) and the acetabular version showed no significant difference between the subject with and without herniation pits. Discussion. In the present study, the prevalence of herniation pits was 17% in asymptomatic Japanese general population. The fact that the size of the herniation pits enlarge with age may suggest these cystic lesions have degenerative characteristics with no association with FAI. Although large α angles have been recognized as a predictor of cam impingement especially in young population, it was impossible to show the relationship between α angle and presence of herniation pits in young population. These results suggest that the presence of the herniation pits has little relevance to FAI diagnosis

Obesity is an increasing public health concern associated with increased perioperative complications and expense in lumbar spine fusions. While open and mini-open fusions such as transforaminal lumbar interbody fusion (TLIF) and minimally invasive TLIF (MIS-TLIF) are more challenging in obese patients, new MIS procedures like oblique lateral lumbar interbody fusion (OLLIF) may improve perioperative outcomes in obese patients relative to TLIF and MIS-TLIF. The purpose of this study is to determine the effects of obesity on perioperative outcomes in OLLIF, MIS-TLIF, and TLIF. This is a retrospective cohort study. We included patients who underwent OLLIF, MIS-TLIF, or TLIF on three or fewer spinal levels at a single Minnesota hospital after conservative therapy had failed. Indications included in this study were degenerative disc disease, spondylolisthesis, spondylosis, herniation, stenosis, and scoliosis. We measured demographic information, body mass index (BMI), surgery time, blood loss, and hospital stay. We performed summary statistics to compare perioperative outcomes in MIS-TLIF, OLLIF, and TLIF. We performed multivariate regression to determine the effects of BMI on perioperative outcomes controlling for demographics and number of levels on which surgeries were operated. OLLIF significantly reduces surgery time, blood loss, and hospital stay compared to MIS-TLIF, and TLIF for all levels. MIS-TLIF and TLIF do not differ significantly except for a slight reduction in hospital stay for two-level procedures. On multivariate analysis, a one-point increase in BMI increased surgery time by 0.56 ± 0.47 minutes (p = 0.24) in the OLLIF group, by 2.8 ± 1.43 minutes (p = 0.06) in the MIS-TLIF group, and by 1.7 ± 0.43 minutes (p < 0.001) in the TLIF group. BMI has positive effects on blood loss for TLIF (p < 0.001) but not for OLLIF (p = 0.68) or MIS-TLIF (p = 0.67). BMI does not have significant effects on length of hospital stay for any procedure. Obesity is associated with increased surgery time and blood loss in TLIF and with increased surgery time in MIS-TLIF. Increased surgery time may be associated with increased perioperative complications and cost. In OLLIF, BMI does not affect perioperative outcomes. Therefore, OLLIF may reduce the disparity in outcomes and cost between obese and non-obese patients

Aim. Spinal infection is the most frequent complication of spine surgery. Its incidence varies between 1% and 14% in the literature, depending on various studied populations and surgical procedures. The aim of this study was to describe a consecutive 2706 case series. Method. We analyzed a prospective cohort of 2706 patients operated for spine disease between 2013 and 2016 in a University Hospital. The infection rates, germs, time between surgery and infection and outcomes after surgical revision were assessed with a minimum follow-up of 7 months. We developed a mathematical model to analyze risk factors in this difficult-to-treat population. Results. Among 2706 patient who underwent spinal surgery during the three-year study period, 106 developed a postoperative spine infection. Clinical indicators for infection were the sudden onset of local pain and swelling without fever after an initial pain-free interval. We observed a masculine predominance (68%); the median age was 56 years. The rate of infection was comprised between 0,3% (discal herniation surgery) to over 20% in posterior cervical instrumented surgery (acute cervical fractures), with a global rate of 4%. Polymicrobial infections with more than 3 germs were found in only 2 case, with 3 germs in 8 cases, 2 germs in 27 cases and 1 germ in 69 cases. Staphylococcus aureus, Propionibacterium acnes and Staphylococcus epidermidis were the three main germs identified (53, 36 and 22 respectively). Propionibacterium acnes was involved with a higher rate in instrumented surgery but also in 8% of conventional non-instrumented surgery, with a median relapse time of 24 days (12 days to 4 years). Staphylococcus aureus was involved at a higher rate in posterior non-instrumented surgery with a median relapse time of 18 days (8–66 days). The rate of infection per month was globally stable along the year except an increased rate in February-March. All patients with a suspicion of post-op infection were initially treated with wound/deep tissues revision within the first month after surgery and associated with implant removal after one-month post-op. Pejorative outcomes were associated with incomplete revision surgery, several surgeries and polymicrobial infection. Conclusions. In this study, the rate of postoperative infection is comparable to the literature. In contrast, Propionibacterium incidence is high, especially for acute infections. This unexpected rate can be linked to technical improvements in culture detection but this should also lead us to further discuss the natural process of spine/disk colonization of this germ

Purpose of Study. Discecomy is a common operation peformed for back pain at our hospital. We analysed the theatre register looking at demographic and health data for our patients to shed more light on this cases. Description of Methods. Entries in the spinal unit theatre registers from 2000–2012 were reviewed, and all patients undergoing discectomy for disc herniation recorded analysed regarding demographics and epidemiology. Summary Of Results. A total of 171 patients had operations in our theatres. Of these patients the large majority were females. The age distribution was 45 to 50 years. The lumbar spine was the commonest region operated, especially the lower lumbar spine. We had very low repeat operations from failed surgery or requiring herniation. Conclusion. Surgical registers are an important tool in understanding pathology in the communities we serve. We can track the type of patients treated and then plan appropriate intervention programmes. It also helps to follow-up patients and correlate outcomes, and we can use this data to correlate practices nationally and internationally. NO DISCLOSURES

Introduction. Kinematics analyses of the spine have been recognized as an effective method for functional analysis of the spine. CT is suitable for obtaining bony geometry of the vertebrae but radiation is a clinical concern. MRI is noninvasive but it is difficult to detect bone edges especially at endplates and processes where soft tissues attach. Kinematics analyses require tracking of solid bodies; therefore, bony geometry is not always necessary for kinematics analysis of the spine. This study aimed to develop a reliable and robust method for kinematics analysis of the spine using an innovative MRI-based 3D bone-marrow model. Materials and Methods. This IRB-approved study recruited 17 patients undergoing lumbar decompression surgery to treat a single-level symptomatic herniation as part of a clinical trial for a new dynamic stabilization device. T1 & T2 sagittal MRI scans were acquired as part of the pre-operative evaluation in three positions: supine and with the shoulders rotated 45° to the left and right to induce torsion of the lumbar spine. 3D bone-marrow models of L5 and S1 at the neutral and rotated positions were created by selecting a threshold level of the bone-marrow intensity at bone-marrow/bone interface. Validated 3D-3D registration techniques were used to track movements of L5 and S1. Segmental movements at L5/S1 during torsion were calculated. Results. Bone-marrow models were created not only in the vertebral body but also in superior/inferior, transverse and spinous processes, pedicles and laminae. Segmental rotation (mean±SD) at L5/S1 was shown to be symmetric for both left and right motions (p=0.149; Left: 1.04°±0.93° and Right: 1.33°±0.80°). The range of motion recorded was: left [0.05°-3.70°] and right [0.35°-3.25°]. These values were equivalent to previously reported values of axial lumbar rotation measured by 3D CT lumbar models. Conclusions. This study demonstrated feasibility of kinematic analyses using the 3D bone-marrow model created with clinical MRI. The bone-marrow model shows the bone-marrow/bone interface geometry –the internal structure of the vertebra rather than outside geometry usually used for kinematic analyses– that is easily and consistently detected due to its high-contrast interface MRI intensity, which does not require lengthy manual tracing of the bony contour. The bone-marrow model includes key elements of the vertebra including posterior elements and the 3D-3D registration technique used for 3D-CT model can be applied (Fig.1). This type of methodology can be used in the clinic to evaluate with sufficient accuracy subject-specific spinal kinematics without exposure to additional radiation. The MRI-based 3D bone-marrow model may also be useful for kinematic analyses of other major joints such as hip, knee, ankle and shoulder joints

Background. There have been limited published reports on the clinical results of cervical artificial disc replacement. Goffin et al reported a 90% rate of good to excellent results at 1 to 2 yrs after Bryan disc replacement. Wigfield et al reported a 46% improvement in pain and 31% improvement in disability 2 yrs after Prestige cervical disc replacement. Objectives. The study was designed to determine whether new functional cervical disc prosthesis can provide improvement in the ability to perform activities of daily living, decrease pain and segmental motion. Methods. All patients who had Prestige cervical disc replacement over last 2yrs 3 months were identified. Oswestry disability index score and SF36 Quality of life instrument were administered to each patient. Site specific pain scores were obtained using visual analogue scale. Clinical and operative details were reviewed and correlated. Results. 35 Patients underwent 48 Prestige cervical disc replacement during study period. There was 48%, 54% and 70% improvement in Oswestry disability index at 6 weeks, 6 months and 19 months follow-ups respectively. There was significant improvements in both neck and arm pain during immediate post op period and during further follow-ups. There was one neck wound haematoma and one left sided Horner's syndrome as complications. Conclusion. Anterior cervical disc replacement is a viable surgical alternative to fusion for cervical disc degenerative disease and herniation with preservation of motion and alignment without compromising clinical outcomes. At least 5yrs follow-up will be needed to assess the long term functionality of the prosthesis and protective influence on the adjacent levels

Purpose. To perform an Interrater reliability study determining the agreement between an Orthopaedic team and a Radiology team on the MRI features of prolapsed uncontained cervical discs in Flexion-Distraction injuries of the cervical spine. This leads us to determine how many patients demonstrated evidence of a ‘dangerous’ disc: an uncontained disc herniating posteriorly that may be drawn into the spinal canal during closed reduction. Methods. One hundred and ten patients who had pre-reduction MRI scans managed during the last 10 years were included. Variables were chosen and defined by the senior Author and explained to both teams prior to reviewing the scans. The review was performed by each team independently and without any access to clinical information. Data collection and interpretation was designed by a statistician to reduce risk of data entry errors. Interrater reliability/agreement was determined using the Cohen Kappa value. Results. Disc Protrusion across Posterior Body Line, Interrater agreement Cohen-Kappa=0.46 (moderate agreement) Disc protrusion across Inferior Body Line Interrater agreement Cohen-Kappa=0.4 (moderate agreement) Disc protrusion across Corner to Corner Line, Interrater agreement Cohen-Kappa=0.15 (poor agreement) Disc disruption Line, Interrater agreement Cohen-Kappa=0.33 (moderate agreement) Disc Contained, Interrater agreement Cohen-Kappa=0.41 (moderate agreement) PLL, Interrater agreement Cohen Kappa=0.22 (Fair agreement). Prevalence of posterior disc herniation 42% (orthopaedic team), 51%(Radiology team). Prevalence of uncontained discs 70% (orthopaedic team), 76%(Radiology team). The most agreed upon variables were posterior herniation and the impression of whether the disc was contained. Conclusion. Interrater agreement on the presence of an uncontained herniated disc between Orthopaedic surgeons and Radiologists in this study was never excellent. This leads us to believe it imperative for the surgeon to review MRI's in addition to reading the radiologists report. NO DISCLOSURES

Introduction. The Two Week Waiting Time Standard, which requires that patients with suspected cancer referred by general practitioners should be seen within 2 weeks, was introduced in 2000. We reviewed the performance of this standard with regards to proportion of patients seen and tumour detection rates. Methods and results. We reviewed all the referrals sent under the ‘two week’ rule from January 2004 to December 2005, to our bone and soft tissue sarcoma service. These referrals were evaluated for:. Whether or not the referral met established referral guidelines for bone and soft tissue tumours. The proportion of patients seen within two weeks. The proportion of patients referred under the guidelines that had malignant tumours. This was compared with the total number of referrals to the unit and their tumour detection rates. A total of 40 patients were referred under the ‘two week’ rule. 95% of these were seen within two weeks of referral. Of the 40 patients, three patients had soft tissue metastasis from a primary tumour elsewhere, and six had primary malignant soft tissue tumours. 13 had a benign bone/ soft tissue tumour. 18 (45%) patients had a non neoplastic pathology (6 Muscle tear/ herniation; 4 ganglion/bursa; 2 lumps that disappeared) During the same period a total of 507 patients were referred by other routes. Conclusion. Only 10 of 40 patients referred under the 2-week rule had malignant tumours. The majority of referrals to our service do not fall under this rule. Significant numbers of referral under the rule are not in line with the referral guidelines. It is our impression that the 2-week rule, whilst highlighting the need of these patients to be seen urgently, may distort clinical priorities and disadvantage patients referred from other sources

Stable thoracolumbar fracture is a common injury. The factors that determine its outcome are unclear. Aspects of injury severity were analysed for their ability to predict outcome by controlling other outcome-affecting factors (patient's pre-injury health status, legal aspects, associated injuries, etc.). No reliable disc injury severity grading system was available and therefore a new system was developed. A prospective observational study of 44 conservatively treated patients with stable fractures between T11 and L5 was conducted. Bony injury severity was scored based on comminution, apposition and kyphosis parameters. Disc injury severity was scored by the new scale based on variables – Herniation, Indentation, Height decrease and Signal change – seen in MRI. Ten outcome domains (five domains of pain and function each) were assessed at 1 to 2 years from injury. The data was analysed by non-parametric correlation and stepwise-linear regression analysis to assess the predictive value of different variables (patient factors, injury factors and social factor) to outcome. The correlation coefficients between injury severity and outcome were consistently higher with disc injury severity than bony. Disc injury severity showed highest predictive value for both pain (29%) and functional (16%) outcomes, whereas the bony injury severity parameters (kyphosis, etc.) and the posterior ligament injury severity provided no prediction of outcome. According to AO classification, the fractures were A1, A2, A3 and B1; in this spectrum of injuries, the AO classification had no prediction of outcome. The disc injury score also had a good predictive value for final disc degeneration. Disc injury severity should be gauged in advising prognosis and treatment. The new disc injury severity grading system showed good construct validity