Comparative assessment of groundwater quality indices of Kannur District, Kerala, India using multivariate statistical approaches and GIS.

The aim of the study was to determine the groundwater characteristics of rural and industrial zones in the Kannur region. In 2011, 25 groundwater data were collected from the centre for water resource development management (CWRDM), and in 2019, 25 groundwater samples from rural and near-industrial areas were collected and analysed for major anions (HCO3-, CO32-, Cl-, NO3- and SO42-), and cations (TH, Ca2+, Mg2+, Na+, K+ and Fe2+) using APHA standards. To better understand the link between water quality parameters, multivariate statistical analysis approaches such as principal component analysis (PCA), hierarchical cluster analysis (HCA), correlation matrix analysis (CMA), and Pearson correlation bivariate one-tailed analysis (PCBOTA) were used to analyse the inter-relationship of data. The Inverse Distance Weighed (IDW) method was used to generate the spatial distribution of the groundwater quality index (GWQI). In 2011, the water quality index (WQI) value of groundwater samples was excellent at 24.42% and good at 54.14%, which were used for drinking purposes and moderate at 17.22% and poor at 4.22% for irrigation purposes in this study area. In 2019, excellent 21.62%, good 51.56% were used for drinking purpose, and moderate at 18.14%, and poor at 8.68% for irrigation purposes. By comparing the data with BIS and WHO standards, it is clear that groundwater in Kannur district is of good quality. In groundwater samples, the PCA eigen values were reported in 2011 (84.7%) and 2019 (73.4%) for statistical approaches. This study uses HCA and PCBOTA to analyse the elements, resulting in a better understanding of groundwater quality development. GIS based WQI maps were obtained and utilised to gain a better knowledge of the study area's past and present water quality status. We observed that the quality of groundwater in the study region's north-western portion is insufficient for drinking water.

Exploring the Boundaries of Reality: Investigating the Phenomenon of Artificial Intelligence Hallucination in Scientific Writing Through ChatGPT References.

Background Chatbots are computer programs that use artificial intelligence (AI) and natural language processing (NLP) to simulate conversations with humans. One such chatbot is ChatGPT, which uses the third-generation generative pre-trained transformer (GPT-3) developed by OpenAI. ChatGPT has been praised for its ability to generate text, but concerns have been raised about its accuracy and precision in generating data, as well as legal issues related to references. This study aims to investigate the frequency of AI hallucination in research proposals entirely drafted by ChatGPT. Methodology An analytical design was employed to investigate AI hallucination by ChatGPT. A total of 178 references listed by ChatGPT were verified for inclusion in the study. Statistical analysis was performed by five researchers who entered their data into a Google Form, and the final results were represented using pie charts and tables. Results Out of the 178 references analyzed, 69 references did not have a Digital Object Identifier (DOI), and 28 references neither turned up on Google search nor had an existing DOI. Three references were listed from books and not research articles. These observations suggest that ChatGPT's ability to generate reliable references for research topics may be limited by the availability of DOI and the accessibility of online articles. Conclusions The study highlights the potential limitations of ChatGPT's ability to generate reliable references for research proposals. AI hallucination is a problem that may negatively impact decision-making and may give rise to ethical and legal problems. Improving the training inputs by including diverse, accurate, and contextually relevant data sets along with frequent updates to the training models could potentially help address these issues. However, until these issues are addressed, researchers using ChatGPT should exercise caution in relying solely on the references generated by the AI chatbot.

Do design variations in the artificial disc influence cervical spine biomechanics? A finite element investigation.

Various ball and socket-type designs of cervical artificial discs are in use or under investigation. Many artificial disc designs claim to restore the normal kinematics of the cervical spine. What differentiates one type of design from another design is currently not well understood. In this study, authors examined various clinically relevant parameters using a finite element model of C3-C7 cervical spine to study the effects of variations of ball and socket disc designs. Four variations of ball and socket-type artificial disc were placed at the C5-C6 level in an experimentally validated finite element model. Biomechanical effects of the shape (oval vs. spherical ball) and location (inferior vs. superior ball) were studied in detail. Range of motion, facet loading, implant stresses and capsule ligament strains were computed to investigate the influence of disc designs on resulting biomechanics. Motions at the implant level tended to increase following disc replacement. No major kinematic differences were observed among the disc designs tested. However, implant stresses were substantially higher in the spherical designs when compared to the oval designs. For both spherical and oval designs, the facet loads were lower for the designs with an inferior ball component. The capsule ligament strains were lower for the oval design with an inferior ball component. Overall, the oval design with an inferior ball component, produced motion, facet loads, implant stresses and capsule ligament strains closest to the intact spine, which may be key to long-term implant survival.

Identification of potent HDAC 2 inhibitors using E-pharmacophore modelling, structure-based virtual screening and molecular dynamic simulation.

Histone deacetylase 2 (HDAC 2) of class I HDACs plays a major role in embryonic and neural developments. However, HDAC 2 overexpression triggers cell proliferation by diverse mechanisms in cancer. Over the decades, many pan and class-specific inhibitors of HDAC were discovered. Limitations such as toxicity and differential cell localization of each isoform led researchers to hypothesize that isoform selective inhibitors may be relevant to bring about desired effects. In this study, we have employed the PHASE module to develop an e-pharmacophore model and virtually screened four focused libraries of around 300,000 compounds to identify isoform selective HDAC 2 inhibitors. The compounds with phase fitness score greater than or equal to 2.4 were subjected to structure-based virtual screening with HDAC 2. Ten molecules with docking score greater than -12 kcal/mol were chosen for selectivity study, QikProp module (ADME prediction) and dG/bind energy identification. Compound 1A with the best dock score of -13.3 kcal/mol and compound 1I with highest free binding energy, -70.93 kcal/mol, were selected for molecular dynamic simulation studies (40 ns simulation). The results indicated that compound 1I may be a potent and selective HDAC 2 inhibitor. Further, in vitro and in vivo studies are necessary to validate the potency of selected lead molecule and its derivatives.

Incidence, etiology, classification, and management of neuralgia after posterior lumbar interbody fusion surgery in 226 patients.

BACKGROUND CONTEXT: Neurological symptoms are a well-recognized complication after posterior lumbar interbody fusion (PLIF) surgery. Concerns about this potential problem may deter surgeons from performing the procedure. PURPOSE: To determine the incidence, etiology, prevention, and management of neuralgia after PLIF surgery. STUDY DESIGN/SETTING: This study is a retrospective review of patients who underwent PLIF surgery at a university hospital in the north east of England. PATIENT SAMPLE: Two hundred sixty patients who met the inclusion criteria of degenerative disc disease, spondylolisthesis, disc herniation, and postlaminectomy/postdiscectomy syndrome underwent PLIF surgery. OUTCOME MEASURES: The outcome measure of neuralgia was assessed postoperatively by a subjective description of leg pain. Patients were considered to have post PLIF neuralgia if they complained of severe radiculopathy, which was not present before surgery. METHODS: During the study period April 1996 to April 2002, all patients who met the inclusion criteria underwent the PLIF procedure. Outcome was assessed postoperatively. In all but the first 20 cases, interbody cages were used. A subtotal superior facetectomy was performed on the first 103 patients. The subsequent 123 patients had a total removal of the superior facet. Autogenous bone and pedicle screws and plates were used in all cases. RESULTS: The study group comprised 226 patients (121 women, 105 men; mean age at surgery, 44.1 years; age range, 12-81 years). Duration of symptoms ranged from 5 to 480 months (mean, 90.6 months; median, 60.0). Overall, there were 16 cases of neuralgia in 226 patients (7.1%). In the subtotal facetectomy group, 10 of the 103 patients (9.7%) had neuralgic symptoms. In the total facetectomy group, 6 of the 123 patients (4.9%) had neuralgic symptoms. The difference in incidence was not statistically significant (p=.158). CONCLUSIONS: This study describes our experiences of post-PLIF neuralgia. It outlines strategies for prevention and management of the problem.

Primary erector spinae pyomyositis causing an epidural abscess: case report and literature review.

BACKGROUND CONTEXT: Primary pyomyositis (PM) is a rare bacterial infection of skeletal muscle usually restricted to tropical zones. Typically caused by Staphylococcus aureus, primary staphylococcal PM associated with an epidural abscess has not been reported before. PURPOSE: We present the first case of staphylococcal PM associated with an epidural abscess. STUDY DESIGN: Case report. PATIENT SAMPLE: A 56-year-old woman. OUTCOME MEASURES: Clinical follow-up at 9 months. METHODS: This 56-year-old woman presented with a sudden onset of left lumbar back pain and sciatica without prior illness. She was pyrexial on admission, with elevated inflammatory markers but with no obvious systemic source of sepsis. RESULTS: Spinal magnetic resonance imaging and subsequent surgery revealed an erector spinae abscess causing an epidural abscess via the left L4/5 intervertebral foramen. Both back pain and sciatica were immediately improved postoperatively. Culture revealed S aureus as the sole organism sensitive to flucloxacillin. Intravenous therapy was converted to oral after 12 days once the erythrocyte sedimentation rate had normalized and she was asymptomatic. She remains asymptomatic and without clinical signs at the 9-month follow-up. CONCLUSION: Spinal infection must always be considered when back pain and sciatica are associated with clinical signs of sepsis. We present the first case of staphylococcal PM associated with an epidural abscess.

Subsidence and malplacement with the Oblique Maverick Lumbar Disc Arthroplasty: technical note.

BACKGROUND: The A-Mav (Medtronic, Sofamor Danek, Memphis, TN) is a well-established lumbar total disc arthroplasty device. The O-Mav (Medtronic) is a more recent innovation designed to minimize the potential vascular complications associated with A-Mav insertion at L4/5. No study has hitherto studied the relative accuracy or safety of the two techniques. PURPOSE: To compare the accuracy of lumbar disc arthroplasty placement by using the anterior technique (A-Mav) with the oblique (O-Mav) technique. STUDY DESIGN: Technical report. PATIENT SAMPLE: Fourteen patients. OUTCOME MEASURES: Implant placement accuracy on high-resolution computed tomography scan. Comparative morbidity, mortality, blood loss, and operating time were also assessed. METHODS: Patients were considered for lumbar disc arthroplasty who had suffered chronic discogenic low back pain unresponsive to nonoperative management for at least 6 months. All patients were operated on at the L4/5 level. A-Mavs were inserted in 7 patients and O-Mavs in 7. Implant placement was analyzed postoperatively by using computer software on high-resolution computed tomography scan with respect to four parameters: (1) off-center malplacement, (2) axial rotational malplacement, (3) coronal tilt, and (4) vertebral body susbsidence. Comparative morbidity, mortality, blood loss, and operating time were also assessed. RESULTS: Subsidence, off-center malplacement, and rotational malplacement were significantly increased in O-Mavs compared with A-Mavs (4.3+/-0.6 mm vs. 1.6+/-0.6 mm, p=.008; 3.1+/-0.4 mm vs. 1.3+/-0.4 mm, p=.006; 6.5 degrees +/-1.2 degrees vs. 3.8 degrees +/-0.4 degrees , p=.046). No significant differences were found between O-Mavs and A-Mavs in tilt, operating time, blood loss, or morbidity and mortality. CONCLUSIONS: O-Mav insertion appears to be complicated by significantly greater vertebral body subsidence and malplacement than A-Mav insertion. A-Mav insertion therefore appears to be more accurate and less complicated yet equally as safe as O-Mav insertion.

Donor site morbidity following iliac crest bone harvesting for cervical fusion: a comparison between minimally invasive and open techniques.

We have studied the occurrence of donor site morbidity, cosmesis and overall satisfaction with graft procedure in 76 patients who had undergone iliac crest bone harvesting for anterior cervical discectomy and fusion (ACDF). Totally 24 patients underwent an open procedure and 52 a minimally invasive trephine harvesting method. Although our study demonstrated substantial donor site pain and its effect on ambulation in both groups, this was of limited duration. Two patients, one in each group, suffered long-term pain that was eventually resolved. Totally 8.3% of patients in the open group suffered minor complications and 11.5% in the trephine group. There were two cases of meralgia parasthetica. There were no major complications in either group. There was no statistically significant difference in morbidity between the open and trephine groups. There was a trend towards significance (P = 0.076) for pain at the donor site, with less pain reported by patients who underwent the trephine procedure for harvesting.

Lumbar total disc arthroplasty: coronal midline definition and optimal TDA placement.

It is a general principle with arthroplasty insertion that precise implant centering is critical for long term function and outcome. Whilst some authors have proclaimed that lumbar total disc arthroplasty (TDA) may be different, and that off -centre placement may be functionally well tolerated, these claims are premature: significantly worse clinical results have already been reported with poorly placed TDA at 2 years. Accurate TDA placement requires a precise and consistent definition of the desired coronal midline target (which is currently lacking), as well as a procedural mechanism to optimize placement at that target. We summarize our experience, as well as others', in achieving these two requirements. Long-term outcomes after lumbar TDA insertion should only be compared with results from fusion where TDAs have been implanted accurately.

Reverse transformation of Modic type 2 changes to Modic type 1 changes during sustained chronic low-back pain severity. Report of two cases and review of the literature.

Modic Type 2 (MT2) neuroimaging changes are considered stable or invariant over time and relatively quiescent, whereas Modic Type 1 (MT1) changes are considered unstable and more symptomatic. The authors report two cases in which MT2 changes were symptomatic and evidently unstable, and in which chronic low-back pain severity remained unaltered despite a MT2-MT1 reverse transformation. Two women (41 and 48 years old) both presented with chronic low-back pain. Magnetic resonance (MR) images demonstrated degenerating discs at L5-S1 associated with well-established MT2 changes in adjacent vertebrae. Repeated MR imaging in these two patients after 11 months and 7 years, respectively, revealed reverse transformation of the MT2 changes into more florid MT1 changes, despite unaltered chronic low-back pain severity. Following anterior discectomy and disc arthroplasty, immediate abolition of chronic low-back pain was achieved in both patients and sustained at 3-year follow up. Modic Type 2 changes are therefore neither as stable nor as quiescent as originally believed. Each type can change, with equal symptom-generating capacity. More representative imaging-pathological correlates are required to determine the precise nature of MT changes.

Conservative management of psoas haematoma following complex lumbar surgery.

We report psoas hematoma communicating with extradural hematoma and compressing on lumbar nerve roots during the postoperative period in a patient who underwent L3/4 level dynamic stabilization and L4/5 and L5/S1 posterior lumbar interbody fusion. Persistent radicular symptoms occurring soon after posterior lumbar surgery are not an unknown entity. However, psoas hematoma communicating with the extradural hematoma and compressing on L4 and L5 nerve roots soon after surgery, leading to radicular symptoms has not been reported. In addition to the conservative approach in managing such cases, this case report also emphasizes the importance of clinical evaluation and utilization of necessary imaging techniques such as computed tomography (CT) scan and magnetic resonance imaging (MRI) scan to diagnose the cause of persistent severe radicular pain in the postoperative period.

Prevalence of insomnia in patients with chronic back pain.

PURPOSE: To estimate the prevalence of insomnia in patients with chronic back pain, and to correlate insomnia with severity of back pain and disability. METHODS: 63 women and 57 men aged 24 to 83 (mean, 55) years who presented with chronic back pain for >6 months were asked to complete a self-administered questionnaire to evaluate the Insomnia Severity Index (ISI), Oswestry Disability Index (ODI), and Numerical Rating Scale (NRS) for back pain. RESULTS: Of the 120 patients, 25 had no insomnia, 39 had sub-threshold insomnia, and 56 had clinically significant insomnia. According to the ODI, disability was minimal in 12 patients, moderate in 38, severe in 43, bed-binding in 26, and crippling in one. Of the 120 patients, 91 rated their NRS for back pain as 5 to 10 and 29 rated it as 1 to 4. Correlation was stronger between ISI and ODI than between ISI and NRS for back pain (r=0.59 vs. r=0.38). CONCLUSION: 47% of patients with chronic back pain had insomnia. The ODI was more reliable than the NRS for back pain to detect insomnia. Back pain should be treated early to avoid serious health problems associated with insomnia.

Effect of psychological status on outcome of posterior lumbar interbody fusion surgery.

STUDY DESIGN: Prospective longitudinal study. PURPOSE: To determine if preoperative psychological status affects outcome in spinal surgery. OVERVIEW OF LITERATURE: Low back pain is known to have a psychosomatic component. Increased bodily awareness (somatization) and depressive symptoms are two factors that may affect outcome. It is possible to measure these components using questionnaires. METHODS: Patients who underwent posterior interbody fusion (PLIF) surgery were assessed preoperatively and at follow-up using a self-administered questionnaire. The visual analogue scale (VAS) for back and leg pain severity and the Oswestry Disability Index (ODI) were used as outcome measures. The psychological status of patients was classified into one of four groups using the Distress and Risk Assessment Method (DRAM); normal, at-risk, depressed somatic and distressed depressive. RESULTS: Preoperative DRAM scores showed 14 had no psychological disturbance (normal), 39 were at-risk, 11 distressed somatic, and 10 distressed depressive. There was no significant difference between the 4 groups in the mean preoperative ODI (analysis of variance, p = 0.426). There was a statistically and clinically significant improvement in the ODI after surgery for all but distressed somatic patients (9.8; range, -5.2 to 24.8; p = 0.177). VAS scores for all groups apart from the distressed somatic showed a statistically and clinically significant improvement. Our results show that preoperative psychological state affects outcome in PLIF surgery. CONCLUSIONS: Patients who were classified as distressed somatic preoperatively had a less favorable outcome compared to other groups. This group of patients may benefit from formal psychological assessment before undergoing PLIF surgery.

Less invasive posterior lumbar interbody fusion and obesity: clinical outcomes and return to work.

STUDY DESIGN: Single-center retrospective study. OBJECTIVE: The purpose of this study was to examine the relationship between obesity (body mass index [BMI] >30) and the incidence of perioperative complications, outcome of surgery, and return to work in a cohort of patients undergoing elective less invasive posterior lumbar interbody fusion (LI-PLIF) of the lumbar spine for low back pain and leg pain. SUMMARY OF BACKGROUND DATA: Spine surgery in the obese is challenging and an increasing problem. There are few reported studies that have assessed the incidence of perioperative complications in obese patients undergoing elective lumbar fusion procedures. To our knowledge, the effect of obesity on LI-PLIF and return to work has not been evaluated in the published data. METHODS: We identified 15 patients with BMI >30 who underwent LI-PLIF by reviewing the clinical notes and the preoperative admission sheet between April 2005 and March 2007. Patients who had suffered chronic low back pain for a minimum of 2 years that had proven unresponsive to conservative treatment were included. All patients underwent pre- and postoperative evaluations for Oswestry Disability Index, short-form 36, and visual analogue scores. Minimum follow-up was for 12 months. RESULTS: Blood loss was dependent on BMI, number of levels, and surgical time. Postoperative complication was 33.3%, which was more in the morbidly obese group than the in the obese group. Ten patients (66.6%) returned to their normal preoperative employment within 12 months of the index procedure. There was a significant improvement in the Oswestry Disability Index (14.78 ± 6.0, P = 0.03), in the visual analogue scores for back pain (3.2 ± 0.76, P = 0.001). Length of hospital stay was a mean of 3.35 days (range, 1-7). CONCLUSION: Surgical decision-making in the obese and morbidly obese patient is a challenge for the operating surgeon. Although surgery is technically more demanding, our experience with less invasive posterior interbody fusion has shown less incidence of postoperative complication, less intraoperative blood loss, and short in-patient hospital stay. Furthermore (66.6%) returned to their normal preoperative employment within 12 months of the index procedure. We conclude that a high BMI should not be a contraindication to surgery in patients with degenerative low back pain.

Does symptom duration correlate negatively with outcome after posterior lumbar interbody fusion for chronic low back pain?

STUDY DESIGN: Original report. OBJECTIVE: To investigate the putative negative correlation between the duration of symptoms (DOS) and outcome after surgery for chronic low back pain (CLBP). SUMMARY OF BACKGROUND DATA: Posterior lumbar interbody fusion (PLIF) is a well established treatment for CLBP. Anecdotally, a prolonged DOS is associated with a poor prognosis for recovery of CLBP. In one recent study, a DOS greater than 3 years predicted a poor prognosis for subsequent clinical improvement with CLBP. METHODS: Patients (n = 209) underwent PLIF for CLBP who had proven unresponsive to nonoperative management for at least 6 months. A wide variety of physical and mental outcome scores were simultaneously assessed pre- and after surgery: i.e., the Oswestry Disability Index (ODI), SF-36 body score, SF-36 mental score, Visual Analogue Score (VAS) for back pain, VAS for leg pain, Hospital Anxiety Score (HAS), and Hospital Depression Score. RESULTS: Despite a prolonged mean DOS of 84.3 ± 6.6 months, there was a significant postoperative improvement in all 7 outcome scores after PLIF. Significant improvement occurred in 181 patients (i.e., 86.6%) and was sustained at 51.6 ± 12.0 months follow-up. No significant correlation was found between DOS and any outcome score (ODI: rs = 0.013, P = 0.877; SF-36 bodily pain: rs = 0.013, P = 0.87; VAS for back pain: rs = 0.038, P = 0.656; VAS for leg pain: rs = 0.086, P = 0.310; HAS: rs = 0.511, P = 0.056; Hospital Depression Score: rs = 0.056, P = 0.509, or SF-36 mental score rs = 0.007, P = 0.935). No arbitrary DOS "cut-off" was found for which significantly different outcomes were recorded either side of the cut-off; or for which a significant correlation was revealed either side of the cut-off. Finally, no significant partial correlation was found between DOS and any outcome score after controlling for pain severity (VAS(back pain)) before surgery. There were no significant differences in terms of age, sex, or DOS between those with improved ODI scores less than 10 compared with those with improved ODI scores greater than 10. CONCLUSION: The putative negative correlation between DOS and outcome was not observed under any analysis in our study. PLIF procured a rapid and sustained improvement in CLBP, even where the DOS was excessively prolonged; and even after having allowed for pain severity. Symptom chronicity, therefore, does not represent a poor prognostic indicator for CLBP outcome after PLIF: PLIF should be considered irrespective of DOS. Because DOS and pain severity are likely mediators of "central sensitization," the hypothesis that central sensitization may be prevalent in CLBP patients selected for PLIF is therefore questioned.

Are high-intensity zones and Modic changes mutually exclusive in symptomatic lumbar degenerative discs?

OBJECT: Modic changes (MCs) and high-intensity zones (HIZs) potentially serve as variably sensitive markers for discogenic chronic low-back pain (CLBP). No study has hitherto assessed the phenomenon of MC-HIZ coexistence at a single level, and the goal in this study was to assess the nature and frequency of this phenomenon. METHODS: One hundred twenty consecutive patients with discogenic CLBP in whom lumbar MR imaging studies had demonstrated an HIZ, an MC, or both were included. RESULTS: This cohort (120 consecutive patients with 193 degenerative discs) had discogenic CLBP in at least 1 lumbar level associated with either an HIZ (77 discs), an MC (67 discs), or both (16 patients); there were 55 coexistent non-HIZ/non-MC degenerative discs. Painful MC-HIZ coexistence at 1 level occurred in 6 patients (5 of whom were female). If HIZs and MCs were random, independent entities, then MC-HIZ coexistence at 1 level would have been expected in 67 x 77/193 (that is, 27) discs. The observed frequency was therefore significantly lower (chi(2) = 41, p < 0.001). There were no significant demographic differences between groups. The HIZ disc height (8 +/- 0.2 mm) was significantly greater than the MC (6.6 +/- 0.2 mm) or MC-HIZ (6.7 +/- 0.2 mm) disc heights (p < 0.001). CONCLUSIONS: In patients with discogenic CLBP associated with HIZ or MC lesions, MC-HIZ coexistence at 1 level was significantly rarer than expected even by chance; thus, despite both being manifestations of a seemingly common degenerative process, HIZ and MC more closely represent "either/or" phenomena. Because HIZ disc height was significantly greater, HIZs may develop earlier in the disc degenerative ontogeny. If any degenerative disc may only display an HIZ first, yet may ultimately display an MC instead, then HIZs must invariably regress as MCs supervene (or even vice versa). The MC-HIZ coexistence would therefore represent either a rare stable state (possibly more common in females) or a transitory state, as one lesion gradually replaces the other. Longitudinal studies would confirm or refute these hypotheses, although significantly larger sample sizes would be required.

Significantly improved outcomes with a less invasive posterior lumbar interbody fusion incorporating total facetectomy.

STUDY DESIGN: Original study. OBJECTIVE: Prospective comparison of clinical outcomes after a standard posterior lumbar interbody fusion (ST-PLIF) and after a limited exposure PLIF incorporating total facetectomy (LI-PLIF). SUMMARY OF BACKGROUND DATA: Most groups have reported significantly improved clinical outcomes after ST-PLIF. To our knowledge, however, a comparison of outcomes between ST-PLIF and the LI-PLIF that we herein describe has not been reported before. METHODS: Patients were included who had suffered chronic low back pain for a minimum of 2 years that was unresponsive to conservative treatment. N = 114 consecutive patients underwent ST-PLIF, whereas n = 209 underwent LI-PLIF. All patients underwent pre- and postoperative evaluations for Oswestry Disability Index (ODI), short-form 36 (SF-36), and visual analogue scores (VAS). The minimum follow-up for either group was 2 years. RESULTS: There was a significant improvement in the ODI (22.5 +/- 1.0, P < 0.001), VAS for back pain (3.8 +/- 0.1, P = 0.003), VAS for leg pain (4.0 +/- 0.2, P = 0.002), and SF-36 for bodily pain (14.7 +/- 0.9, P = 0.012) after ST-PLIF. However, there was a significantly greater improvement in all scores after LI-PLIF: ODI (28.8 +/- 1.4 vs. 22.5 +/- 1.0, P < 0.001), VAS for back pain (5.4 +/- 0.2 vs. 3.8 +/- 0.1, P = 0.001), VAS for leg pain (5.1 +/- 0.2 vs. 4.0 +/- 0.2, P < 0.001), and SF-36 for bodily pain (18.5 +/- 0.8 vs. 14.7 +/- 0.9, P = 0.003). There was a significantly shorter duration of hospital stay after LI-PLIF (2.24 +/- 0.057 days) than after ST-PLIF (4.04 +/- 0.13 days) (P = 0.005). Operative complications occurred in 19.3% of ST-PLIF and in 6.7% of LI-PLIF. CONCLUSION: Clinical outcomes were significantly improved after both ST-PLIF and LI-PLIF. However, outcomes were significantly better after LI-PLIF than after ST-PLIF. Significantly shortened hospital stay with LI-PLIF probably reflected the "less invasive" technique per se. Significantly better clinical outcomes with fewer complications after LI-PLIF, however, potentially reflected maneuvers singular to LI-PLIF: (1) preservation of posterior elements, (2) avoidance of far lateral dissection over the transverse processes, (3) bilateral total facetectomy, (4) fewer neurologic complications, and (5) avoidance of iliac crest autograft. LI-PLIF is therefore recommended over ST-PLIF.

The accuracy and validity of "routine" X-rays in estimating lumbar disc arthroplasty placement.

STUDY DESIGN: Original study. OBJECTIVE: To compare the accuracy of radiograph (XR) estimates of lumbar total disc arthroplasty placement with high-resolution computed tomography (CT). SUMMARY OF BACKGROUND DATA: Most lumbar disc arthroplasties are inserted and subsequently analyzed using anteroposterior and lateral XR: XR estimates are often correlated with clinical outcomes. No study has hitherto assessed the relative accuracy of XR estimates with CT. METHODS: Patients (N = 36) had recently undergone uncomplicated lumbar total disc arthroplasty for unresponsive discogenic back pain. Interpedicular midline malplacement and vertebral body penetration (VBP) were estimated after surgery, by "blinded" independent review, using computer software on both nonrotated XR and high-resolution CT at the same clinic attendance. RESULTS: Results were obtained in N = 36 patients. No significant differences were found between XR and CT in the mean +/- standard error estimation of either midline malplacement (1.7 +/- 0.2 mm vs. 1.8 +/- 0.2 mm, P = 0.86) or VBP (1.5 +/- 0.3 mm vs. 1.6 +/- 0.3 mm, P = 0.79). However, the correlation between XR and CT for midline malplacement appeared strong (r = 0.72, P < 0.001), whereas the correlation between XR and CT for VBP was poor (r = 0.23 P > 0.10). The standard deviation of XR-CT differences for VBP (2.2 mm) was almost twice that for midline malplacement (1.2 mm). XR-CT differences exceeded the 95% limit of agreement in 6% of midline placement estimates, and in 8% for VBP. CONCLUSION: Nonrotated XR permitted an accurate and valid estimate of midline malplacement relative to CT in most cases. However, the correlation was biased toward XR underestimation of CT-derived malplacement, and highly significant XR-CT differences occurred in 6% of estimates: early postoperative CT is therefore recommended to enhance the estimation of midline placement. XR-CT agreement for VBP was poor: CT is therefore indicated in all cases for this parameter. This is the first study to compare the accuracy of XR in estimating lumbar total disc arthroplasty placement with CT.

Finite element study of matched paired posterior disc implant and dynamic stabilizer (360° motion preservation system).

BACKGROUND: Anterior lumbar disc replacements are used to restore spinal alignment and kinematics of a degenerated segment. Compared to fusion of the segment, disc replacements may prevent adjacent segment degeneration. To resolve some of the deficiencies of anterior lumbar arthroplasty, such as the approach itself, difficulty of revision, and postoperative facet pain, 360° motion preservation systems based on posterior disc and posterior dynamic system (PDS) designs are being pursued. These systems are easier to revise and address all the pain generators in a motion segment, including the nerves, facets, and disc. However, biomechanics of the 360° posterior motion preservation system, including the contributions of the 2 subsystems (disc and PDS), are sparsely reported in the literature.nds. METHODS: An experimentally validated 3-dimensional finite element model of the ligamentous L3-S1 segment was used to investigate the differences in biomechanical behavior of the lumbar spine. A single-level 360° posterior motion preservation system and its individual components in various orientations were simulated and compared with an intact model. Appropriate posterior surgical procedures were simulated. The PDS, a curved device with male and female components, was attached to the pedicle screws. The finite element models were subjected to 400 N of follower load plus 10Nm moment in extension and flexion. RESULTS: The PDS restored flexion/extension motion to normal. The artificial disc led to increases in range of motion (ROM) compared with the intact model. ROM for the 360° system at the implanted and adjacent levels were similar to those of the respective intact levels. ROM was similar whether the discs were placed (a) both parallel to the midsagittal plane, (b) both angled 20° to the midsagittal plane, and (c) one at 20° and one parallel to the midsagittal plane. However, the stresses were slightly higher in the nonparallel disc configuration than in the parallel disc configuration, both in flexion and extension modes. CONCLUSIONS: Posterior disc replacement with PDS restored the kinematics of the spine at all levels to near normal. In addition, placing the discs in a nonparallel configuration with respect to the midsagittal plane does not affect the functionality of the discs compared with parallel placement. Posterior disc replacement alone is not sufficient to restore the segment biomechanics to normal levels. CLINICAL RELEVANCE: Finite element analysis results show that, unlike implants for fusion, PDS and posterior discs together (360° motion preservation system) are needed to preserve ROM. Such systems will prevent adjacent level degeneration and address pain from various spinal components, including facets.

Significantly improved lumbar arthroplasty placement using image guidance: technical note.

STUDY DESIGN: Technical report. OBJECTIVE: To compare the accuracy of lumbar total disc arthroplasty placement using an image-guidance system (IGS) with conventional fluoroscopy. SUMMARY OF BACKGROUND DATA: Most disc arthroplasties are inserted and analyzed using fluoroscopy. One previous cadaveric study demonstrated beneficial, but insignificant, effects of IGS on total disc arthroplasty placement compared with conventional fluoroscopy. METHODS: Patients were considered for lumbar total disc arthroplasty who had chronic discogenic low back pain unresponsive to nonoperative management for at least 6 months. Total disc arthroplasty was performed in n = 6 with IGS and in n = 14 without IGS. Implant placement was analyzed after surgery using computer software on high-resolution CT with respect to 3 parameters: 1) off-center mal-placement, 2) axial rotational mal-placement, and 3) coronal tilt. RESULTS: Arthroplasties inserted with IGS were positioned with significantly greater accuracy than non-IGS arthroplasties with respect to all 3 parameters measured (off-center: 1.1 +/- 0.3 vs. 2.3 +/- 0.3 mm, P = 0.031; rotation: 88.8 degrees +/- 0.2 degrees vs. 87.1 degrees +/- 0.4 degrees; P = 0.0084; and tilt: 1.0 degrees +/- 0.5 degrees vs. 2.6 degrees +/- 0.3 degrees, P = 0.01). There was no significant difference in operating time between non-IGS controls (123 +/- 5 minutes) and IGS (139 +/- 10 minutes) groups (P = 0.129). CONCLUSION: This is the first clinical study to demonstrate significantly improved accuracy of lumbar total disc arthroplasty placement on CT using IGS compared with conventional fluoroscopy. IGS should be considered for routine use with lumbar total disc arthroplasty insertion.