Background:. Following lumbar spine surgery patients with a high BMI appear to have increased post-operative complications including surgical site infections (SSI), urinary complications, increased anaesthetic/operative time and a greater need for post-operative blood transfusion. There is no current evidence, however, analysing the effect of BMI on functional outcome. Purpose:. We aimed to analyse the effect of BMI on functional outcome following lumbar spine surgery. Study Design:. Retrospective Cohort Study. Patient Sample:. 131. Outcome Measures:. Outcome measures included mean post-operative Oswestry Disability Index (ODI) at six and twelve months, the incidence of SSI, mean operative time and the requirement for post-operative blood transfusion. Methods:. Patients that underwent lumbar spinal surgery between September 2010 and November 2013 were identified retrospectively and categorised into discectomy, decompression, fusion and revision is created. A BMI threshold of 30 was used to group patients as non-obese or obese. Univariate analysis was used to compare the effect of BMI on the above outcome measures. Results:. Post-operative complication rates were higher in the obese group in each category. However, there was no significant difference in the post-operative ODI at six ad twelve months post-operatively. Conclusions:. Increased BMI is related to increased post-operative complications but is not associated with a poorer functional outcome in the short to mid-term

Male retrograde ejaculation is a well-documented but rare complication of anterior approach lumbar spine surgery. Retraction of the soft tissues which encase the superior hypogastric plexus leads to dysfunction of the sympathetic control of the bladder neck sphincter. We postulated that similar nerve root dysfunction in females may lead to bladder problems and sexual dysfunction. The Female Sexual Function Index Questionnaire was sent to 20 consecutive women who had undergone anterior spinal surgery by the senior author (GM). Questionnaires were returned by 11 of the 20 subjects. 6 had undergone disc replacement surgery and 5 anterior lumbar interbody fusion. All procedures used an anterior retroperitoneal approach. The age range was 20 to 49 years (mean 40.2 years). There were no immediate peri-operative complications. The mean time since surgery was 4.9 years (range 3.1 to 5.8 years). The Female Sexual Function Index is a validated questionnaire used internationally as the gold standard measure of sexual dysfunction in women. Urinary frequency and incontinence were also recorded. 9 women (82%) described a degree of post-operative sexual dysfunction with 7 (64%) recording urinary frequency and urge incontinence. Although some sexual dysfunction may be expected from pre-existing conditions, we highlight this complication following anterior lumbar spine surgery in females. We plan to further investigate its incidence and possible resolution of symptoms after a prolonged period in a larger case series

To establish whether incidental durotomy complicating lumbar spine surgery adversely affects long-term outcome. Data was collected prospectively. The study population comprised 200 patients. 19 patients who sustained dural tears (Group A) were compared to a control group of 181 patients with no tear (Group B). Outcomes were measured with the SF-36, Oswestry Disability Index (ODI) and visual analogue scores for back (VB) and leg (VL) pain. Scores for the 2 groups were compared pre-operatively, at 2 and 6 months post-op for all patients and at long-term follow-up (range 2-9 years) for patients in group A. In addition for patients in group A the patients satisfaction with the procedure, ongoing symptoms, employment status and analgesic intake were documented. Pre-operative scores were similar between the 2 groups apart from significantly higher vb scores (63 –A vs 46-B). Results at 2 and 6 months showed no significant differences between the 2 groups. Outcome scores for group A at long-term follow-up do not show any significant decline. Our study demonstrates that incidental dural tears complicating lumbar spine surgery do not adversely affect outcome in the long-term

Purpose. To establish whether incidental durotomy complicating lumbar spine surgery adversely affects long-term outcome. Methods. Data was collected prospectively. The study population comprised 200 patients. 19 patients who sustained dural tears (Group A) were compared to a control group of 181 patients with no tear (Group B). Outcomes were measured with the SF-36, Oswestry Disability Index (ODI) and visual analogue scores for back (VB) and leg (VL) pain. Scores for the 2 groups were compared pre-operatively, at 2 and 6 months post-op for all patients and at long-term follow-up (range 2-9 years) for patients in group A. In addition for patients in group A the patients satisfaction with the procedure, ongoing symptoms, employment status and analgesic intake were documented. Results. Pre-operative scores were similar between the 2 groups apart from significantly higher vb scores (63 –A vs 46-B). Results at 2 and 6 months showed no significant differences between the 2 groups. Outcome scores for group A at long-term follow-up do not show any significant decline. Conclusion. Our study demonstrates that incidental dural tears complicating lumbar spine surgery do not adversely affect outcome in the long-term. Ethics - none, Interest –none

Background: A common complication of lumbar spine surgery is incidental tear of the dural sac and subsequent leakage of the cerebrospinal fluid intraoperatively. Studies have reported a wide variation in the rates of dural tears in spine surgery (1%–17%). The rates were higher after revision surgery. Objective: To establish a baseline rate of incidence of dural tears after lumbar surgery in Morriston Hospital Neurosurgical Unit and to compare it with the results reported in the literature. Methods and Results: A prospective review of the operation notes of 65 consecutive patients who had undergone lumbar surgery (Primary lumbar discectomy, primary lumbar laminectomy and revision lumbar discectomy) over a period of 3 months from Jan 2008. Patients were operated on by different neurosurgical consultants. 40 patients had primary lumbar discectomy of which 2 (5%) had dural tears. 20 patients had primary lumbar laminectomy of which 1 (5%) had a dural tear and 5 patients had revision lumbar discectomy of which 1 (20%) had a dural tear. All dural tears were repaired intraoperatively. Conclusion: This study shows that the highest percentage of incidental durotomy was in revision lumbar surgery which was also slightly higher than the reported rates (8.1%–17.4%). The percentage of dural tears after primary discectomy and primary laminectomy was within range of the percentages reported in the literature (1%–7.1%) and (3.1%–13%) respectively. A multicentre prospective larger study which includes all different surgical procedures performed on the lumbar spine is needed to establish a more accurate incidence rate for this common complication

The aim of this study was to test the effectiveness of a nurse practitioner-led clinic for managing the pre and postoperative care of patients undergoing lumbar spine surgery, against traditional clinic treatment. Ninety patients were randomised- 46 (Group 1) attended a nurse practitioner run pre-operative class and post-operative follow-up clinic and 44 (Group 2) were seen by the surgeon before and after the operation. All patients completed the Low Back Outcome Score, MSPQ and Zung score, pre-operatively and at six months post-op. There were 46 male and 44 female patients, and mean age was 45.4 years (range 20–77). The two groups were demographically similar (p = 0.418). The mean pre-op outcome score was 23.49 in group 1 and 17.41 in group 2 (p = 0.038) and the mean post-op scores were 44.67 and 35.38 for group 1 and 2 respectively (p = 0.021). Intra-group comparison showed an improvement in post-op outcome score for all patients (p = 0.001), but those in group 1 were significantly more satisfied (p = 0.008). Four theatre slots were lost in group 2 but none in group 1. A nurse practitioner-led pre-op counselling and post-op follow-up is more effective than the traditional clinic attendance for patients undergoing lumbar spine surgery and prevented waste of theatre time

Prolonged length of stay (LOS) is a significant contributor to the variation in surgical health care costs and resource utilization after elective spine surgery. The primary goal of this study was to identify patient, surgical and institutional variables that influence LOS. The secondary objective is to examine variability in institutional practices among participating centers. This is a retrospective study of a prospectively multicentric followed cohort of patients enrolled in the CSORN between January 2015 and October 2020. A logistic regression model and bootstrapping method was used. A survey was sent to participating centers to assessed institutional level interventions in place to decrease LOS. Centers with LOS shorter than the median were compared to centers with LOS longer than the median. A total of 3734 patients were included (979 discectomies, 1102 laminectomies, 1653 fusions). The median LOS for discectomy, laminectomy and fusion were respectively 0.0 day (IQR 1.0), 1.0 day (IQR 2.0) and 4.0 days (IQR 2.0). Laminectomy group had the largest variability (SD=4.4, Range 0-133 days). For discectomy, predictors of LOS longer than 0 days were having less leg pain, higher ODI, symptoms duration over 2 years, open procedure, and AE (p< 0.05). Predictors of longer LOS than median of 1 day for laminectomy were increasing age, living alone, higher ODI, open procedures, longer operative time, and AEs (p< 0.05). For posterior instrumented fusion, predictors of longer LOS than median of 4 days were older age, living alone, more comorbidities, less back pain, higher ODI, using narcotics, longer operative time, open procedures, and AEs (p< 0.05). Ten centers (53%) had either ERAS or a standardized protocol aimed at reducing LOS. In this study stratifying individual patient and institutional level factors across Canada, several independent predictors were identified to enhance the understanding of LOS variability in common elective lumbar spine surgery. The current study provides an updated detailed analysis of the ongoing Canadian efforts in the implementation of multimodal ERAS care pathways. Future studies should explore multivariate analysis in institutional factors and the influence of preoperative patient education on LOS

Introduction: Accurate & ethical coding is challenging and directly impacts on Payment by Results (PbR). The objectives were to review the existing pattern of coding for lumbar spinal surgery and ascertain its appropriateness & accuracy for surgical procedures, medical comorbidities and post-op complications. Methods: A retrospective review of 100 consecutive lumbar spine surgeries operated from Apr2006–Jan2007 was conducted. The coding excel sheet, hospital notes and laboratory reports were reviewed. Results: The primary procedural accuracy was 96%, however this reduced to 79% for the entire description of performed surgery. The procedural codes did not specifically reflect the surgery performed and lacked reproducibility. Spinal fusion codes were omitted and revision cases were coded as primary surgeries in 2 instances each. Surgical levels were coded incorrectly in 12 and harvest of iliac crest bone graft omitted in 4 cases respectively. Medical comorbidities were coded appropriately in 70%. The commonly missed comorbidities were drug allergies, hypercholesterolemia, smoking and alcoholism. Post-op adverse events were coded in 62.5% of the cases(5/8). Conclusion: Coding is a universal language of communication amongst healthcare professionals. Its accuracy is important not just for PbR, but also for data quality, audit and research. The financial implications regarding PbR governed by Healthcare Resource Group (HRG) codes (dictated by Official population and census surveys [OPCS4.4] & International classification of diseases [ICD–10] codes) are discussed. The awareness of clinical coding is low amongst junior doctors. Literature emphasises qualification of coders, legible documentation by physicians and interaction between coders & clinicians

Introduction: The ideal regimen for safe and effective post operative pain relief inspinal surgery remains elusive. Numerous studies have been conducted comparing epidural with patient controlled analgesia with no firm conclusion as to which is best. Aims: To determine the efficacy of acute pain relief between surgical placed epidural catheter and patient controlled analgesia for lumbar spinal surgery. Method: A 42 month retrospective survey of 82 spinal surgery patients case notes and anaesthetic charts performed by a consultant spinal surgeon and his registrar from 2002 to 2005. There were 34 epidural and 48 PCA patients. Visual analogue Score (0–10) at 6 hourly intervals up to 36 hours, complications and age of patient were looked at. Exclusion criteria for epidural were dural tear, history of hypotension, unexplained neurological symptoms, and bleeding disorders and surgeon choice. Epidural infusion consisted of bupivacaine 0.1% with 5mls loading dose and 10mls/ hour infusion and PCA consisted of morphine sulphate 2mg/ml with a 1ml loading dose and 5 minute lockout interval.All patients were on standard analgesia which included oromorph 5mg four hourly orally and paracetamol 1gram six hourly as required orally. No radiographic evidence of epidural catheter placement was performed. Post-operative complications which included hypotension, nausea, vomiting, and drowsiness were monitored. Results: The average age for the epidural group was 46.9 and PCA group 49.8. The most striking finding was that the average pain score at each six hourly interval waslower in the epidural group. This was significant in the first 18 hours post-operatively.However, 3 complications occurred in the epidural group which included hypotension. In addition, 3 epidural infusions were stopped and changed to PCA most likely due to improper placement of catheter. There were no complications with the PCA group. Conclusion: This observational study demonstrates clinically and statistically that in the acute post-operative phase and up to 36 hours that epidural analgesia for lumbar spine surgery is more effective than PCA. From this survey, the risk of epidural was higher, although no serious complications occurred. Surgeon placement of catheter is also important in the effective delivery of epidural pain relief. The lower efficacy of the PCA may have been due to poor patient understanding of the concept of PCA and thereforeits

NHS Patients can wait up to 15 months for non-urgent spine surgery. The intended procedure is determined by the outpatient MRI scan. Do changes occur within the spine during the wait for surgery? Would the changes affect the operative decision?. In a prospective study, 105 patients listed for elective lumbar spine surgery at a district general hospital If the MRI scan is over 6 months old, a second scan is performed prior to surgery. Changes that alter the operative decision are noted. 44% Discectomy, 17% decompression, and 19% fusion plus decompression patients cancelled surgery due to improvement in symptoms. None of the spinal fusion patients cancelled. 14% discectomy; 12.5% decompression; 25% fusion; 19% fusion plus decompression and 65% fusion plus discectomy patients had different procedures after the second MRI. Changes seen include disc resolution, prolapse at a new level, progressive modic changes and compression at other levels. We do not support the fact that patients may have to wait upto 18 months before having elective spinal surgery. However, we found that significant numbers of discectomy and decompression patients found that their symptoms improved enough to decline surgery. No patient that had been listed for fusion alone got better. Due to changes seen on the second MRI scan, 1 in 6 operations were different to the initial planned procedure. Could a surgeon failing to request a further up to date scan prior to surgery therefore be considered negligent?

Objective: NHS Patients can wait up to 18 months for non-urgent spine surgery. The intended procedure is determined by the outpatient MRI scan. Do changes occur within the spine during the wait for surgery? Would the changes affect the operative decision?. Design: A Prospective study. Subjects: 105 patients listed for elective lumbar spine surgery at a district general hospital. Outcome Measures: If the MRI scan is over six months old, a second scan is performed prior to surgery. Changes that alter the operative decision are noted. Results: Forty-four percent discectomy, 17% decompression, and 19% fusion plus decompression patients cancelled surgery due to improvement in symptoms. None of the spinal fusion patients cancelled. Fourteen percent discectomy; 12.5% decompression; 25% fusion; 19% fusion plus decompression and 65% fusion plus discectomy patients had different procedures after the second MRI. Changes seen include disc resolution, pro-lapse at a new level, progressive modic changes and compression at different levels. Conclusions: We do not support the fact that patients may have to wait up to 18 months before having elective spinal surgery. However, a significant numbers of discectomy and decompression patients found that their symptoms improved enough to decline surgery. No patient who had been listed for fusion alone got better. Due to changes seen on the second MRI scan, one in six operations were different to the initial planned procedure. Could a surgeon failing to request a further up to date scan prior to surgery therefore be considered negligent?

Background: Retrograde ejaculation has been reported to range from 2% to 16% following anterior surgical approaches to lower lumbar spine, but the exact incidence is not known. It has been felt for sometime that transecting or extensive dissection of the hypogastric plexus about the lumbo sacral junction could interrupt the sympathetic control of urogenital system and interfere with sexual function. Invasive tests such as urodynamic tests, anorectal manometry and post ejaculatory urine sample would precisely determine its incidence. As a first step we, along with Urogynaecologist devised and validated a questionnaire to determine the urogenital function post operatively. Aims & Methods: To retrospectively determine the incidence of sympathetic dysfunction in anterior lumbar spine surgery. 46 of 60 patients (76% response) who had anterior lumbar spinal surgery answered a validated questionnaire with urinary and bowel function, International Index of Erectile Function (IIEF) for men and Female Sexual Function Index (FSFI). Results: All the females post operatively had retained bowel function and there were no reported cases of sense of urgency, incontinence of stools or flatus. But only one patient reported urinary stress incontinence. There was no change of sexual function as concluded from FSFI score. In males we had 3 cases of retrograde ejaculation which affected the sexual function (based on IIEF score), and were reported to be resolving slowly. There was no incidence of any urinary or bowel dysfunction postoperatively. Conclusions: This retrospective study only showed the overall picture of the incidence of pelvic floor dysfunction following anterior spinal surgery. A prospective trial is underway to determine its incidence

Resident involvement in the operating room is a vital component of their medical education. Conflicting and limited research exists regarding the effects of surgical resident participation on spine surgery patient outcomes. Our objective was to determine the effect of resident involvement on surgery duration, length of hospital stay and 30-day post-operative complication rates.

This study was a multicenter retrospective analysis of the prospectively collected American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database. All anterior cervical or posterior lumbar fusion surgery patients were identified. Patients who had missing trainee involvement information, surgery for cancer, preoperative infection or dirty wound classification, spine fractures, traumatic spinal cord injury, intradural surgery, thoracic surgery and emergency surgery were excluded. Propensity score for risk of any complication was calculated to account for baseline characteristic differences between the attending alone and trainee present group. Multivariate logistic regression was used to investigate the impact of resident involvement on surgery duration, length of hospital stay and 30 day post-operative complication rates.

1441 patients met the inclusion criteria: 1142 patients had surgeries with an attending physician alone and 299 patients had surgeries with trainee involvement. After adjusting using the calculated propensity score, the multivariate analysis demonstrated that there was no significant difference in any complication rates between surgeries involving trainees compared to surgeries with attending surgeons alone. Surgery times were found to be significantly longer for surgeries involving trainees. To further explore this relationship, separate analyses were performed for tertile of predicted surgery duration, cervical or lumbar surgery, instrumentation, inpatient or outpatient surgery. The effect of trainee involvement on increasing surgery time remained significant for medium predicted surgery duration, longer predicted surgery duration, cervical surgery, lumbar surgery, lumbar fusion surgery and inpatient surgery. There were no significant differences reported for any other factors.

After adjusting for confounding, we demonstrated in a national database that resident involvement in surgeries did not increase complication rates, length of hospital stay or surgical duration of more routine surgical cases. We found that resident involvement in surgical cases that were generally more complexed resulted in increased surgery time. Further study is required to determine the relationship between surgery complexity and the effect of resident involvement on surgery duration.

Aim

To use Patient Reported Outcome Measures (PROMs) to determine the effectiveness of lumbar spinal surgery at a single UK institution.

Healthcare interventions are under increasing scrutiny regarding cost-effectiveness and outcome measures have revolutionised clinical research.

To identify all available outcome questionnaires designed for lowback, lumbar spine pathologies and to perform qualitative analysis of these questionnaires for their clinimetric properties.

A comprehensive e-search on PUBMED & EMBASE for all available outcome measures and published review articles for lowback and lumbar spine pathologies was undertaken over a two month period (Nov-Dec 2009). Twenty-eight questionnaires were identified in total. These outcomes questionnaires were evaluated for clinimetric properties viz:-

Validity (content, construct & criterion validity)

Reliability (internal consistency & reproducibility)

Responsiveness and scored on a scale of 0-6 points.

Eight outcomes questionnaires had satisfied all clinimetric domains in methodological evaluation (score 6/6).

Oswestry disability index (ODI)

Roland-Morris disability questionnaire (RMDQ)

Aberdeen lowback pain scale

Extended Aberdeen spine pain scale

Functional rating index

Core lowback pain outcome measure

Backpain functional scale

Maine-Seattle back questionnaire.

Sixteen of these questionnaires scored =5 when evaluated for clinimetric domains. RMDQ had the highest number of published and validated translations followed by ODI. Criterion validity was not tested for NASS-AAOS lumbar spine questionnaire.

32%(9/28) of the outcome instruments have undergone methodological evaluation for =3 clinimetric properties. Clinicians should be cautious when choosing appropriate validated outcome measures when evaluating therapeutic/surgical intervention. We suggest use of few validated outcome measures with high clinimetric scores (=5/6) to be made mandatory when reporting clinical results.

Study Design: Prospective observational study.

Objective: To establish the sensitivity, specificity and cost-effectiveness of motor evoked potential (MEP) monitoring of lower lumbar nerve roots during instrumented spinal fusion.

Subjects: 161 patients undergoing elective lumbar spinal fusion monitored with the Neurosign 800 machine.

Outcome Measures: MEP evidence of pedicle breaches and nerve root over-distraction. Symptoms and signs of new neurological deficits postoperatively. EMG confirmation of neurological deficits in symptomatic post-operative patients.

Results: True positive results consisted of pedicle breaches detected in 15 patients (9.3%). Nerve root irritation on distraction was found in 9 patients (5.6%). These results allowed modification of the surgical technique to prevent subsequent neural injury. True negative results on active pedicle probing occurred in 134 patients (83.2%) and in 146 patients (90.7%) on passive monitoring. False positive results were detected in 7 patients (4.3%). Four patients had electrical connection problems and in three patients pedicle probing was positive but direct screw testing was negative. True negative results consisted of a failure of monitoring to detect clinically significant neurological events in five patients (3.1%). In four the symptoms and signs were transient, resolving within six weeks of surgery. In one, revision decompression of the L5 nerve roots was required.

Conclusions: MEP monitoring in our hands has a specificity of 95.4% and a sensitivity of 75%. The cost per case is around £75.

We reported the first single surgeon series comparing outcome of microscopic and open primary single level unilateral lumbar decompression or discectomy. We aimed to determine any difference in outcomes between the two techniques.

Forty-six decompressions were performed with use of an operating microscope (microscopic), and forty without (open) at two different hospitals. All procedures were performed by the senior author. Information was obtained by analysis of the patients' notes. The average age of the patients in both groups was comparable. Operating time was shorter in the microscopic group (68min, range 30-130) compared to the open group (83 mins, range 30-180). Dural tear rate was 4.3% with use of a microscope (0% symptomatic dural tear rate) and 7.5% without (2.5% symptomatic dural tear rate). Nerve damage incidence was 0% with use of a microscope and 5% (two patients) without. One of these was a neurapraxia and the patient made a full recovery. Wound infection rates, diagnosed on grounds of clinical suspicion, were 4.3% and 2.5% for microscopic and open respectively. There were no incidences of deep infection or post-operative discitis. Average inpatient stay was under 48 hours in both groups.

Using the modified Macnab criteria, results using the microscope were 0% poor, 14% fair, 32% good, and 55% excellent. The results for the open group were 0% poor, 10% fair, 37% good and 53% excellent. Average follow-up was six months (1-19) for the microscope group, and seven months (2-16) for the open group.

We conclude that primary single level unilateral lumbar decompressive surgery, performed without the use of a microscope, has a higher dural tear rate than the same surgery performed with the benefit of an operating microscope. Surgical time and incidence of nerve damage are also reduced by use of the microscope.

The purpose of this study is to determine whether the mode of anaesthesia chosen for patients undergoing lumbar microdiscectomy surgery has any significant influence on the immediate outcome in terms of safety, efficacy or patient satisfaction.

This prospective randomised study compared safety, efficacy and satisfaction levels in patients having spinal versus general anaesthesia for single level lumbar microdiscectomy.

Fifty consecutive healthy and cooperative patients were recruited and prospectively randomised into two equal groups; half the patients received a spinal anaesthetic (SA), the remainder a general anaesthetic (GA). Each specific mode of anaesthesia was standardised.

Comprehensive post-operative evaluation concentrated on documenting any complications specific to the particular mode of anaesthesia, recording the pace at which the various milestones of physiological and functional recovery were reached, and the level of patient satisfaction with the type of anaesthesia used.

The results showed no serious complication specific to their particular mode of anaesthesia in either group. Thirteen out of 25 SA patients required temporary urinary catheterisation (9 males, 4 females) while among the GA group 4 patients required urinary catheterisation (4 males and 1 female). Post-operative pain perception was significantly lower in the SA group. The SA patients achieved the milestones of physiological and functional recovery more rapidly. While both groups were satisfied with their procedure, the level of satisfaction was significantly higher in the SA group.

In conclusion, lumbar spinal microdiscectomy can be carried out with equal safety, employing either spinal or general anaesthesia. While they require more temporary urinary catheterisation associated with the previous use of intrathecal morphine, patients undergoing SA suffer less pain in association with their procedure and recover more rapidly. Blinded to an extent by not having experienced the alternative, both groups appeared satisfied with their anaesthetic. However, the level of satisfaction was significantly higher in the SA group.

Background. Surgical site infection following spine surgery is associated with increased morbidity, mortality and increased cost for the health care system. The reported pooled incidence is 3%. Perioperative antibiotic prophylaxis is a key factor in lowering the risk of acquiring an infection. Previous studies have assessed perioperative cefuroxime concentrations in the anterior column of the cervical spine with an anterior surgical approach. However, the majority of surgeries are performed in the posterior column and often involve the lumbar spine. Accordingly, the objective was to compare the perioperative tissue concentrations of cefuroxime in the anterior and posterior column of the same lumbar vertebra using microdialysis in an experimental porcine model. Method. The lumbar vertebral column was exposed in 8 female pigs. Microdialysis catheters were placed for sampling in the anterior column (vertebral body) and posterior column (posterior arch) within the same vertebra (L5). Cefuroxime (1.5 g) was administered intravenously over 10 min. Microdialysates and plasma samples were continuously obtained over 8 hours. Cefuroxime concentrations were quantified by Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry. Microdialysis is a catheter-based pharmacokinetic tool, that allows dynamic sampling of unbound and pharmacologic active fraction of drugs e.g., cefuroxime. The primary endpoint was the time with cefuroxime above the clinical breakpoint minimal inhibitory concentration (T>MIC) for Staphylococcus aureus of 4 µg/mL as this has been suggested as the best predictor of efficacy for cefuroxime. The secondary endpoint was tissue penetration (AUC. tissue. /AUC. plasma. ). Results. Mean T>MIC 4 µg/mL (95% confidence interval) was 123 min (105–141) in plasma, 97 min (79–115) in the anterior column and 93 min (75–111) in the posterior column. Tissue penetration (95% confidence interval) was incomplete for both the anterior column 0.48 (0.40–0.56) and posterior column 0.40 (0.33–0.48). Conclusions. Open lumbar spine surgery often involves extensive soft tissue dissection, stripping and retraction of the paraspinal muscles which may impair the local blood flow exposing the lumbar vertebra to postoperative infections. A single intravenous administration of 1.5 g cefuroxime resulted in comparable T>MIC between the anterior and posterior column of the lumbar spine. Mean cefuroxime concentrations decreased below the clinical breakpoint MIC for S. aureus of 4 µg/mL after 123 min (plasma), 97 min (anterior column) and 93 min (posterior column). This is shorter than the duration of most lumbar spine surgeries, and therefore alternative dosing regimens should be considered in posterior open lumbar spine surgeries lasting more than 1.5 hours

Aims. Repeated lumbar spine surgery has been associated with inferior clinical outcomes. This study aimed to examine and quantify the impact of this association in a national clinical register cohort. Methods. This is a population-based study from the Norwegian Registry for Spine surgery (NORspine). We included 26,723 consecutive cases operated for lumbar spinal stenosis or lumbar disc herniation from January 2007 to December 2018. The primary outcome was the Oswestry Disability Index (ODI), presented as the proportions reaching a patient-acceptable symptom state (PASS; defined as an ODI raw score ≤ 22) and ODI raw and change scores at 12-month follow-up. Secondary outcomes were the Global Perceived Effect scale, the numerical rating scale for pain, the EuroQoL five-dimensions health questionnaire, occurrence of perioperative complications and wound infections, and working capability. Binary logistic regression analysis was conducted to examine how the number of previous operations influenced the odds of not reaching a PASS. Results. The proportion reaching a PASS decreased from 66.0% (95% confidence interval (CI) 65.4 to 66.7) in cases with no previous operation to 22.0% (95% CI 15.2 to 30.3) in cases with four or more previous operations (p < 0.001). The odds of not reaching a PASS were 2.1 (95% CI 1.9 to 2.2) in cases with one previous operation, 2.6 (95% CI 2.3 to 3.0) in cases with two, 4.4 (95% CI 3.4 to 5.5) in cases with three, and 6.9 (95% CI 4.5 to 10.5) in cases with four or more previous operations. The ODI raw and change scores and the secondary outcomes showed similar trends. Conclusion. We found a dose-response relationship between increasing number of previous operations and inferior outcomes among patients operated for degenerative conditions in the lumbar spine. This information should be considered in the shared decision-making process prior to elective spine surgery. Cite this article: Bone Joint J 2023;105-B(4):422–430