Aims

To investigate whether the duration of pain has an influence on the clinical outcomes of patients with low back pain (LBP) managed through the North East of England Regional Back Pain and Radicular Pain Pathway (NERBPP).

Background

The BACK To Health programme is part of the wider North of England back pain and radicular pain pathway. The purpose of this programme is to provide a CPPP approach based on the NICE guidelines CG88 for those with back pain that has not responded to early management and simpler therapies. The purpose of this study is to present preliminary results of this programme.

Introduction

ECG contamination of paraspinal EMG measurements is a known issue ^(1,2), with several proposed methods of correction^(3,4). In addition to this some question remains to how much of an effect this contamination actually has on the EMG recordings.

Background

Doubt has been cast over the accuracy of dermatome charts. This study investigated a large group of patients with known lumbar nerve root compression (NRC), and identified whether their radicular pain corresponded with the predicted distribution on a dermatome chart.

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.

Surgery of the spine is associated with blood loss and frequently transfusion, with consequent risk of infection and reactions. It also costly, and puts a strain on national blood banks.

A new blood salvage device works by ‘washing’ and centrifuging the blood lost during surgery; which can then be re-transfused into the patient.

In a retrospective study 46 consecutive spinal surgeries with Cell Saver were compared with 39 matched surgeries without. Blood loss and units transfused was obtained from the transfusion database and the anaesthetic record.

Average blood loss in the Cell saver group was 1382ml compared to 1405ml in the pre-Cell Saver group.

Average allogenic transfusion was 1.30 units with cell saver compared to 2.78 units without. An average 2.3 units of lost blood were re-infused in the Cell Saver group.

26 (57%) of the Cell Saver group require no allogenic blood at all, whereas only 10 (26%) of patients in the pre-Cell Saver group had no transfusions.

One unit of blood costs £130.52, and the Cell saver device costs £100 per patient. The average cost per patient in the Cell saver group was £270 (any transfusion plus cost of Cell Saver), compared to an average of £368.50 in the pre-Cell Saver group: a saving of £92.50.

The Cell Saver decreased blood transfusions by 46% per patient and by 40% overall, a saving of £92.50 per patient. The number of patients receiving no allogenic blood increased by 31%.

Introduction

It has previously been reported ^(1,2,3) that EMG signals from the lumbar spine are highly prone to contamination by ECG artefacts. It has also been reported that Independent Component Analysis is a suitable method for extracting this contamination (4).

Introduction

Previous work(1) has suggested that Spectral Colour Mapping (SCM) may have potential as an objective measurement tool for analysing Electromyography (EMG) data from spinal muscles, but the production and analysis of these maps is a complex undertaking. It would be beneficial for a system to create these maps and be useable with a minimum of training.

Design of study: Prospective, observational

Purpose of the study: Obese and morbidly obese patients undergoing lumbar surgery can be a challenge to the operating surgeon. Reports on the perioperative data in this group of patients are scarce. The purpose of the study is to prospectively compare the perioperative data in patients with normal and high BMI, undergoing lumbar spine surgery.

Method: We conducted a prospective audit of 50 consecutive patients who underwent primary discectomy or single level decompression under the care of single spine surgeon. Initial Low Back Outcome Score, length of incision, distance from skin to spinous process, distance from skin to lamina, length of hospital stay, blood loss and complications were studied in detail.

Results: We used student t test to compare the two groups and Pearson Correlation to correlate the data against high BMI. We were unable to demonstrate a statistically significant difference between those with normal BMI and high BMI in any of the above parameters analysed.

Conclusion: A high BMI was not associated with an increased perioperative morbidity in this patient group. Contrary to other areas of orthopaedic surgery, there is no statistically significant difference in the Initial Low Back Outcome Score and perioperative data between patients with normal and high BMI undergoing lumbar discectomy and single level decompression.

Conflict of Interest: None

Source of Funding: None

Background context: It is frequently stated that referred pain does not travel below the knee. However, for many years studies provoking referred pain have demonstrated pain radiating below the knee.

Methods: Over a twelve month period, 643 patients with mechanical back pain and 185 patients with nerve root compressions were seen. For each patient two body map images (front and back) were obtained. Some patients attended for review, at a minimum of six weeks after their first visit. These images were also analysed.

Composite images were created by combining all images from patients in one diagnosis group. Colour based overlays were used to analyse the body map images, to locate the locations of pain. Colour density was scaled so that the site with the most hits had a pure colour, reducing down to zero colour for sites with no hits.

Results: There were 720 nerve root compression images. 216 (30%) showed no leg pain, 91 (12.6%) showed upper leg pain, 134 (18.6%) showed lower leg pain and 279 (38.8%) showed upper and lower leg pain.

There were 1964 mechanical back pain images. 674 (34.3%) showed no leg pain, 528 (26.9%) showed upper leg pain, 308 (15.7%) showed lower leg pain and 454 (23.1%) showed upper and lower leg pain.

Conclusion: A large proportion (39%) of the mechanical back pain images indicated that the patient experienced referred pain below the knee. This has significant implications in the diagnosis of nerve root compressions, potentially leading to inappropriate surgery.

Conflicts of Interest: None

Source of Funding: None

Introduction: It has previously been reported(1,2,3) that EMG signals from the lumbar spine are highly prone to contamination by ECG artefacts. As the ECG spectrum overlaps an area of interest in the EMG spectrum this has obvious implications for the accurate analysis of EMG data.

Methods: EMG data was recorded from 192 subjects across two years (initial contact, 12 months and 24 months). When a moving average filter was applied to this raw data an obvious ECG trace could be observed in the case of a large proportion of the tests. The application of a Fast Fourier Transform on this raw data demonstrated a large low frequency spike, with little known correlation to lumbar muscle spectral characteristics, but highly indicative of an ECG signal.

As multiple source signals were recorded per test, the Independent Component Analysis technique was able to be used to split the EMG raw signal into statistically independent components. This technique is designed to take the multiple signal inputs, and convert them into multiple outputs, where the inputs are distinguishable by electrode location; the outputs are distinguishable by signal biological origin.

Results: Upon extraction, one of the signal traces showed a clear ECG trace. The Fourier Transform of this trace showed the low frequency spike, with no other signal components present. The Fourier Transform of the EMG trace showed the original EMG graph, with no low frequency peak. Specific spatial information has been exchanged for a much cleaner signal.

Conflicts of Interest: None

Source of Funding: None

Introduction: In the current political climate ensuring the correct information is distributed to the correct recipient is of paramount importance. Clinical departments often find themselves needing to provide information in order to educate the general public regarding general clinic information and the procedures it carries out.

Methods: The Spinal Assessment Clinic (SAC) at the James Cook University Hospital consists of a multi-disciplinary team. As a result of this many treatment options are available to patients attending the clinic. Due to the necessary time constraints in the SAC, a system was required to help educate patients and the general public about the various diagnoses and the treatments available.

This information was provided by the specialist nurses and orthopaedic surgeons within the SAC team. A multi-portal website was created to allow patients easy access to this information: and to also allow, the information to be updated as and when needed. A facility was also included to allow the provision of external resources that would be of benefit to the patient.

Results: Initial feedback showed that this provided an effective means of achieving the established goals. An online rating system was implemented which currently allows visitors to grade articles along with optionally leaving feedback. This will be presented.

Introduction: Surgical Site Infection (SSI) in spinal surgery at the James Cook University Hospital was investigated and compared with the published rates of 1–12%. Variables of instrumentation, laminar air flow, duration of operation, and blood units transfused in the first 48 hours were examined.

Methods: 556 spinal operations were carried out in 2005–6. 147 of these involved the use of instrumentation. Infections were defined as positive wound or blood cultures. The duration of surgery, presence of laminar air flow and units of blood transfused were recorded. Statistical analysis was performed using the Fisher’s Exact Test.

Results: Nine cases of SSI were identified in the 147 instrumented spinal operations in comparison to Zero in the 409 non-instrumented patients (p < 0.0001)

The mean duration of instrumented surgery was 4 hours 19mins. The infection rates for operation duration < 5 h versus operation duration > 5 h (3/96 Vs 6/51) were not statistically significant (p = 0.065)

Of the 147 instrumented spinal operations, 8 of 117 operations performed in a laminar air flow system and 1 of 30 performed without laminar air flow were infected (p = 0.69)

Infection rates for those patients transfused < 2 units (4/85) were not significantly different to those in patients transfused > 2 units (5/62), p = 0.49.

Conclusion: The rate of SSI at the James Cook University Hospital in instrumented spinal surgery was 6%.

SSI in spinal surgery was heavily influenced by instrumentation, but was not reduced by laminar airflow. Duration of operation and number of units of blood transfused were not significant factors.

Previous studies of EMG recordings from lumbar para-spinal muscles have shown correlations between some EMG variables and low back pain. However there are discrepancies in the literature concerning the usefulness of some of these variables. It has been suggested that ordinary fatigue influences the reproducibility of these measurements, introducing a confounding factor.

In this study we have investigated changes in EMG variables, following a day of normal activity. Forty six subjects participated in this study. EMG recordings were performed at the beginning of their shift (time 1) and at 6 h 20 ±5 min afterwards (time 2) under isometric condition at 60% and 40% of their lean body mass (LBM). Variables studied were initial medial frequency (IMF), median frequency slope (MFS) and half width (HW).

At 60% LBM, IMF measurements at time 1 and time 2 were highly correlated (r2= 0.84, p> 0001) and this was the case for HW measurements (r2=0.84, p> 0001) and MF slope (r2=0.52, p=0> 001). Conducting paired sample t-test also showed no significant change in the IMF from time 1 (M=48.6, SD=8.9) to time 2 (M=49.2, SD=7.3), t(45)=−0.9, p=0.38, or in HW from time 1 (M=47.2, SD=15.5) to time 2 (M=45.9, SD=13.9), t(45)=1.7, p=0.29, or MF slope from time 1 (M=−0.2, SD=0.17) to time 2 (M=−0.24, SD=0.16), t(45)=1.67, p=0.10). The relations observed at 40% LBM almost mirrored those reported at 60 % LBM but with even less significant difference from time1 to time2.

We conclude that IMF, HW and MFS are highly reproducible EMG variables that are not affected by ordinary fatigue and may therefore be valuable in examining differences between subjects or over longer time periods. However they are not useful in assessing changes due to daily exertion.

Introduction: Surgical Site Infection (SSI) in spinal surgery at the James Cook University Hospital was investigated and compared with the published rates of 1 – 12%. Variables of instrumentation, laminar air flow, duration of operation, and blood units transfused in the first 48 hours were examined.

Methods: 556 spinal operations were carried out in 2005–6. 147 of these involved the use of instrumentation. Infections were defined as positive wound or blood cultures. The duration of surgery, presence of laminar air flow and units of blood transfused were recorded. Statistical analysis was performed using Fishers exact test.

Results: 9 cases of SSI were identified in the 147 instrumented spinal operations in comparison to zero in the 409 non-instrumented patients (p < 0.0001).

The mean duration of surgery was 4 hours 19mins. The results for operation duration < 5hours vs. operation duration > 5hours (3/96 vs 6/51) were not statistically significant. (p=0.065)

Of the 147 instrumented spinal operations, 8 of the infected were performed in a laminar air flow system and 1 without (not statistically significant, p=0.69).

The results for blood transfusion < 2units vs. blood transfusion ≥2 units (4/85 vs 5/62) were not significant (P=0.49).

Conclusion: The rate of SSI at the James Cook University Hospital in instrumented spinal surgery was 6%.

SSI in spinal surgery was heavily influenced by instrumentation, but was not reduced by laminar airflow. Duration of operation and number of units of blood transfused were not significant factors.

Purpose: Low frequency peaks (LFP) commonly observed in EMG spectra of paraspinal muscles. These peaks have frequency of 11–15Hz (Median=13, SD=4) and commonly observed in 40% of EMG recordings. We examined the correlation of these peaks with variation in within individuals change in load, between individuals load, gender, age, history of back pain and HW.

Methods and results: Nineteen healthy volunteers were recruited for study of within subject variation in load and data from 106 subjects was examined for the remaining analysis reported here. EMG acquisition was performed using the method described by Oliver et al (Oliver et al., 1996) at a range of load varying from a kilogram to 100% MVC in increments of 10% MVC. The tests were performed in a random order. This method was used for acquisition of data from the second group (n=106) with an exception that only one load fixed at 2/3MVC was used. All parameters including Low frequency peaks and Half Width (HW) was calculated by an automated software developed for this purpose

No correlation between within individual change in load and presence or absence of LFP was found. Only one subject showed a significant correlation between individual change in load with the magnitude of LFPs (r=−0.75, p=0.012). However, when the cumulative data from all 19 subjects was analysed, small correlation between the change in load and magnitude of LFPs (r=−0.17, n=187, p=0.022) was observed, with greater load associated with smaller LFP. No other correlation between gender, individuals load, age and fitness was found.

Conclusion: The appearance of the LFP has been previously described. As yet the underlying cause is not understood, but may be related to a load/feedback loop. The results of this study suggest that load is a factor that may affect LFP and this should be taken into consideration when methods such as HW are used.

Introduction: It has previously been reported that EMG variables recorded from the lumbar spinal muscles may be recorded reproducibly, are able to discriminate low back pain subjects from normal volunteers and are predictive of future back pain. At present, however, an experienced operator is required to acquire the signals and to determine the value of some variables. This has hindered the transfer of the technique from the laboratory to the clinical setting.

Methods: The EMG signal is subjected to a Fast Fourier Transform and a power spectrum is produced. An Expert System has been developed to examine this power spectrum. In accordance to a rule base several variables are generated including the half width. The error analysis can detect a number of possible errors of recording that can affect test results and unusual traces are flagged for further consideration. In some defined cases a correction is automatically applied.

Results: The Standard error between tshe manually generated half width and the automatically calculated value is 30%. Using the automated system 5% of subjects were found to change classification from normal to at risk. The sensitivity and specificity of detecting recording errors was 0.5 and 0.4 respectively. Work is ongoing.

Conclusions: The new system has reduced data set analysis from days to minutes, thus many different methods of analysis can be compared and contrasted readily. The automatic calculation of half width and other variables has brought clinical usage one step closer, and allow EMG analysis to provide a useful tool for monitoring treatment and measuring outcome.

Introduction: EMG recording from lumber spine muscles can be a reliable discriminator and predictor of low back pain (LBP). Multi variant analysis shows age influences these variables.

Aim: to determine in a longitudinal study if age is a significant factor.

Method: EMG recording from 9 subjects was carried out at time1 and 12 years afterwards (time 2);

at the same load and

Results: At the same load there was no significant change in the Mean Half Width (HW) from time1 (M=45.9, SD=19.1) to time 2 (M=51.4, SD=18.7), t(8)= −0.98, p=0.36. No difference was observed when the load set at time 1 was used at time 2 (M=51.4, SD=18.7) and compared with a load set from the MVC obtained at time 2 (M=45.9, SD=12.0), t(8)=1.75, p=0.118.. There was no statistically significant difference between Initial Median Frequency (IMF) at time1 (M=50.6, SD=12.0) and time 2, either using the same load (M=51.7, SD=8.6), t(8)=− 0.273, p=0.79) or the load based on current MVC.

Discussion: In this 12 year longitudinal study, age did not appear to affect the HW or IMF measurement. Both of these variables might be used in long term studies.

Introduction: Delay in active management reduces the prognosis for simple low back pain. The aim of this project was to develop a tool for use in GP surgeries to assist the doctor in his/her diagnosis of lower back pain and allow prompt management with confidence.

Methods: Three different systems for the automated diagnosis of low back pain were developed. With each, the patient answered a series of questions presented by the system. Three different strategies were employed, one using variable weighting, one a logic tree and one an inference engine. For the purpose of testing the systems against each other, a database was constructed containing the answers to all possible questions from each system for one hundred patients attending a low back pain clinic. The “true” diagnosis was that made by the treating clinician who saw the patients.

The original data contained a number of diagnoses:

Spinal Stenosis (central or lateral)

For the purpose of the comparison two groups were considered – patients with radicular symptoms (groups 1 to 4) and patients with pure MBP.

Conclusions: The different approaches to development showed that a number of factors play a crucial role for the accuracy of the systems, including the number of rules used to try to cover every possibility, the interpretation of the questions by the patients and the weighting and approach taken for the different Certainty Factors. The use of any of these three approaches did not allow the development of a system accurate enough for clinical use and it seems that successful development of such a system might require a wholly different approach.

Introduction: Outcome data is essential for clinical governance and research purposes, and will inform decisions on resource re-distribution. The Spinal Assessment Clinic (SAC) treats patients with low back pain referred by their GPs.

Method: Low Back Outcome Score (LBOS) data was collected at presentation (Q1) for 691 patients and on review (Q2) for 98 patients. At presentation further administrative information is also collected. At review Q2 patient satisfaction is recorded as well as the patient’s perception of the status of their LBP. Results were compared between three clinic locations; inner city (CIT), urban (URB) and semi-rural (RUR).

Results: Significantly more patients at the inner city clinic cancelled and re-appointed, and significantly fewer could be discharged after the first consultation. Equal numbers were employed in the three locations.

Despite failure of improvement of perceived LBP, many patients reported an improvement of LBOS.

Conclusion: Social and environmental factors influence behaviour within a treatment program. Patients can appreciate the difference between a satisfactory treatment experience and an actual change in their low back pain. Function can increase even when reported pain does not.