Biomedical subjects

Douglas Wardlaw

Publications and source records attributed to Douglas Wardlaw.

11 recordsLinked to original sources

PubMed2006

Influence of X Stop on neural foramina and spinal canal area in spinal stenosis.

STUDY DESIGN: Measurements of cross sections of exit foramen and spinal canal were performed before and after placement of X Stop in physiologic postures using positional MR scanner at the stenosed level in patients with lumbar spinal stenosis. OBJECTIVE: To quantify the effect of the implant in vivo on the lumbar spine at the instrumented levels in various postures. SUMMARY OF BACKGROUND DATA: Dimensions of the spinal canal and neural foramen decrease from flexion to extension. Symptoms of spinal stenosis occur typically in standing or extension. The X Stop device is designed to distract the posterior elements of the stenotic segment and place it in flexion to treat neurogenic claudication. We think that the device will improve the dimension of the canal in standing and extension. METHODS: Twenty-six patients with lumbar spine stenosis underwent a one- or two-level X Stop procedure. All had preoperative and postoperative positional MRI in standing, supine, and sitting flexion and extension. Measurements were carried out on the images acquired. RESULTS: Significant increase in the dimensions of the neural foramen and canal area were demonstrated after surgery. CONCLUSIONS: The X Stop device improves the degree of central and foraminal stenosis in vivo.

Aged↗

PubMed2006

Cluster analysis as a method for determining size ranges for spinal implants: disc lumbar replacement prosthesis dimensions from magnetic resonance images.

STUDY DESIGN: Statistical analysis of clinical radiologic data. OBJECTIVE: To develop an objective method for finding the number of sizes for a lumbar disc replacement. SUMMARY OF BACKGROUND DATA: Cluster analysis is a well-established technique for sorting observations into clusters so that the "similarity level" is maximal if they belong to the same cluster and minimal otherwise. METHODS: Magnetic resonance scans from 69 patients, with no abnormal discs, yielded 206 sagittal and transverse images of 206 discs (levels L3-L4-L5-S1). Anteroposterior and lateral dimensions were measured from vertebral margins on transverse images; disc heights were measured from sagittal images. Hierarchical cluster analysis was performed to determine the number of clusters followed by nonhierarchical (K-means) cluster analysis. Discriminant analysis was used to determine how well the clusters could be used to classify an observation. RESULTS: The most successful method of clustering the data involved the following parameters: anteroposterior dimension; lateral dimension (both were the mean of results from the superior and inferior margins of a vertebral body, measured on transverse images); and maximum disc height (from a midsagittal image). These were grouped into 7 clusters so that a discriminant analysis was capable of correctly classifying 97.1% of the observations. The mean and standard deviations for the parameter values in each cluster were determined. CONCLUSIONS: Cluster analysis has been successfully used to find the dimensions of the minimum number of prosthesis sizes required to replace L3-L4 to L5-S1 discs; the range of sizes would enable them to be used at higher lumbar levels in some patients.

Adult↗

PubMed2006

Positional MRI changes in supine versus sitting postures in patients with degenerative lumbar spine.

INTRODUCTION: Back pain is associated with a degree of alteration in the alignment and movement of the lumbar spine. The purpose of this study is to investigate how the degree of lumbar segmental degeneration affects sagittal changes in the lumbar spine as it shifts from the supine to the sitting (load-bearing) posture. MATERIALS AND METHODS: Thirty patients with chronic low back pain were enrolled (14 male and 16 female patients); mean age 44.5 years. Their lumbar spines were initially investigated by conventional supine magnetic resonance imaging (MRI) followed later by positional MRI in the seated posture. Of the 150 discs studied, 87 were classified as healthy grade 1, 16 as grade 2, 34 as grade 3, and 13 as grade 4. RESULTS: As the lumbar spine was loaded from the supine to the sitting position, the end-plate angles were decreased significantly as the degeneration was increased. There were also significant changes in the anterior and middle disc heights between the supine and the sitting postures irrespective of the degree of degeneration. The overall lumbar lordosis did not significantly change between the two postures. CONCLUSIONS: We have found that the changes in the segmental motion were related to the degree of degeneration. With positional MRI, we were able to demonstrate changes in healthy and degenerative discs in the weight-bearing position. More similar studies are needed to understand the complex kinematics of the lumbar spine.

Adult↗

PubMed2006

Effects of X-STOP device on sagittal lumbar spine kinematics in spinal stenosis.

The X-Stop device is designed to distract the posterior elements of the stenotic segment and place it in flexion to treat neurogenic claudication. Previous biomechanical studies on X Stop have been done in vitro on cadavers looking at disc pressures and segmental range of movements. The objective of this study is to understand the sagittal kinematics in vivo of the lumbar spine at the instrumented and adjacent levels. Twenty-six patients with lumbar spine stenosis underwent 1 or 2 level X-Stop procedure. All had pre- and postoperative positional magnetic resonance imaging (MRI) in standing, supine, and sitting in flexion and extension. Measurements of disc heights, endplate angles, segmental and lumbar range of movement were performed after placement of X Stop at the stenosed level in patients with lumbar spinal stenosis. No significant changes were seen in disc heights, segmental and total lumbar spine movements postoperatively. The X-Stop device does not affect the sagittal kinematics of the lumbar spine in vivo.

Aged↗

PubMed2005

The positional magnetic resonance imaging changes in the lumbar spine following insertion of a novel interspinous process distraction device.

STUDY DESIGN: Patients with symptomatic lumbar spinal stenosis underwent magnetic resonance imaging to study changes in the lumbar spine in various postures before and after implantation of the X STOP Interspinous Process Distraction Device (St. Francis Medical Technologies, Concord, CA). OBJECTIVE: To visualize the effect of the device in vivo. SUMMARY OF BACKGROUND DATA: Previous studies have shown vertebral canal and exit foraminal area to reduce from flexion to extension. Recently, reports on improved kinematics in vitro at the implantation level of the X STOP device have also been published. METHODS: Using positional magnetic resonance imaging, patients were scanned before and 6 months after surgery. Images were taken with the patient in sitting flexed, extended, neutral, and standing positions. The total range of motion of the lumbar spine and individual segments were measured, along with changes in disc height, areas of the exit foramens, and dural sac. RESULTS: In 12 patients with 17 distracted levels, the area of the dural sac at these levels increased from 77.8 to 93.4 mm after surgery in the standing position (P = 0.006), with increase in the exit foramens, but no change in lumbar posture. CONCLUSIONS: This study shows that the X STOP device increases the cross-sectional area of the dural sac and exit foramens without causing changes in posture.

Aged↗

PubMed2004

Correlation between inter-vertebral disc morphology and the results in patients undergoing Graf ligament stabilisation.

BACKGROUND: Previous studies have shown Graf ligament stabilisation procedure to give mixed results in the short to medium term. The aim of this study was to correlate the pre-operative state of the disc, multifidus muscles, age of the patient, levels operated and the clinical outcome after a mean follow-up of 47 months. METHODS: Graf ligament stabilisation procedure was carried out in 38 patients between 1996 and 1999. Their post-operative status was assessed using MacNab criteria. The post-operative follow-up was by postal questionnaires and review of the clinical notes. Disc morphology and multifidus muscle wasting was graded blindly and independently. The intra- and interobserver reliability was measured with kappa score and classified using the kappa classification of Landis and Koch. Correlation was measured with the help of Spearman correlation coefficient. RESULTS: Thirty-eight patients (100%) returned the questionnaires. Mean follow-up time was 47.55 months. Fifty-nine levels were operated on. Mean age was 39.68 years. The overall re-operation rate was 15.8%. The intra- and interobserver reliability was graded as good to substantial. Twenty-two patients (57.89%) were satisfied with the procedure. There was no statistically significant correlation between disc morphology, multifidus muscle wasting, sex, age, number of levels operated, the levels operated, and the satisfaction rate. CONCLUSIONS: The indications of Graf ligament stabilisation procedure are not clear. Further work is necessary to clearly identify the indication for the procedure.

Adolescent↗

PubMed2004

Low back pain: influence of early MR imaging or CT on treatment and outcome--multicenter randomized trial.

PURPOSE: To establish whether early use of magnetic resonance (MR) imaging or computed tomography (CT) influences treatment and outcome of patients with low back pain (LBP) and whether it is cost-effective. MATERIALS AND METHODS: In a multicenter randomized study, two imaging policies for LBP were compared in 782 participants with symptomatic lumbar spine disorders who were referred to orthopedists or neurosurgeons. Participants were randomly allocated to early (393 participants; mean age, 43.9 years; range, 16-82 years) or delayed selective (389 participants; mean age, 42.8 years; range, 14-82 years) imaging groups. Delayed selective imaging referred to imaging restricted to patients in whom a clear clinical need subsequently developed. Main outcome measures were Aberdeen Low Back Pain (ALBP) score, Short Form 36 (SF-36) score (for multidimensional health status), EuroQol (EQ-5D) score (for quality-adjusted life-year [QALY] estimates), and healthcare resource use at 8 and 24 months after randomization. Data were evaluated with analysis of covariance, ordinal logistic regression analysis, and chi(2) and Mann-Whitney tests. RESULTS: Both groups showed improvement in ALBP score, but this was greater in the early group (adjusted mean difference between groups, -3.05 points [95% CI: -5.16, -0.95; P =.005] and -3.62 points [95% CI: -5.92, -1.32; P =.002] at 8 and 24 months, respectively). Scores for SF-36 (bodily pain domain) and EQ-5D were also significantly better at 24 months. Clinical treatment was similar in both groups. Differences in total costs reflected cost of imaging. Imaging provided an adjusted mean additional QALY of 0.041 during 24 months at a mean incremental cost per QALY of $2,124. CONCLUSION: Early use of imaging does not appear to affect treatment overall. Decisions about the use of imaging depend on judgments concerning whether the small observed improvement in outcome justifies additional cost.

Adolescent↗

PubMed2003

A ligamentum flavum-preserving approach to the lumbar spinal canal.

STUDY DESIGN: This is a retrospective study of a consecutive series of patients undergoing spinal decompression or disc enucleation with preservation of the ligamentum flavum. MacNab criteria and Prolo scoring was used to assess them pre- and after surgery. OBJECTIVES: The aim of the study was to assess the incidence of perioperative complications and long-term clinical outcome of the procedure. SUMMARY OF THE BACKGROUND DATA: One previous study has shown this technique to be effective in reducing the rate of perioperative complications and recurrences in patients undergoing microscopic disc enucleation. However, this study does not comment on the long-term clinical results or the use of the technique in a wider range of spinal procedures. METHODS: Between 1991 and 1999, we operated on 214 patients for peripheral lumbar radiculopathy. MacNab criteria and Prolo scoring was used for their pre- and postoperative assessment. Postoperative assessment was with the help of a postal questionnaire. In addition, clinical notes were studied to look for any further procedures or operative complications. RESULTS: All 214 patients returned the postoperative questionnaires. There were 104 males and 110 females. The mean follow-up was 5.97 years. Thirty-eight patients had an associated fusion or Graf ligament stabilization. Two hundred ninety-six levels were operated in all. There were four instances of dural tear and one of nerve root injury. Five patients underwent revision. There was a statistically significant improvement in the MacNab criteria (P < 0.001) and Prolo score (P < 0.001) after surgery. CONCLUSIONS: We recommend a ligamentum flavum preserving approach because it decreases the rate of perioperative complications while giving comparable long-term results.

Adolescent↗

PubMed2003

Scott wiring for direct repair of lumbar spondylolysis.

STUDY DESIGN: This is a retrospective study of consecutive patients who underwent Scott wiring for symptomatic lumbar spondylolysis using the MacNab criteria. OBJECTIVE: The aim of the study was to assess the clinical outcome of the procedure after a mean follow-up period of more than 10 years. SUMMARY OF THE BACKGROUND DATA: Previous studies have shown this technique to be effective in the management of patients up to the age of 25 years who have symptomatic lumbar spondylolysis with or without a Grade 1 slip. No study has been published with regard to the long-term outcome of Scott wiring. METHODS: Between 1986 and 1993, Scott wiring was performed for 15 patients younger than 25 years of age who had symptomatic lumbar spondylolysis. MacNab criteria were used to assess their pre- and postoperative status. A postal questionnaire was used to assess their clinical outcome. Their notes also were studied to find subsequent episodes of low back pain. RESULTS: The postoperative questionnaires were returned by 14 patients. The mean follow-up period was 10.9 years. Of the 14 patients, 12 had a "good" or "excellent" result according to MacNab criteria. The two patients classified as "poor" required further procedures for continued low back pain. CONCLUSIONS: The Scott wiring technique is recommended for the treatment of symptomatic lumbar spondylolysis in patients younger than 25 years because it gave "good" or "excellent" results in approximately 86% of the patients with a mean follow-up period of 10.9 years.

Adolescent↗

PubMed2003

The role of caudal epidural injections in the management of low back pain.

The value of caudal epidural steroid injections (CEI) in treatment of low back pain and sciatica is controversial. It is believed that CEI are mainly effective in treating acute radiculopathy at intermediate term follow up and have no long-term benefit. The objective of this study was to evaluate the role of CEI in the management of low back pain. This study reviews all patients with low back pain and sciatica treated with CEI in a one-year period (1997) in the orthopaedic department at Aberdeen. The case notes of 163 out of a possible 175 patients (87 female 76 male) with mean age of 51 years (range: 17 to 88 years) were reviewed. Data collected included primary symptoms, presentation time, presumed diagnosis, MRI diagnosis, grade of the surgeon ordering and performing the procedure, the quality and duration of response, and final outcome. Patients were regarded as having an Excellent response if they had good or excellent pain relief for more than 3 months, a Good response (6 weeks to 3 months), Fair (4 to 6 weeks), Brief (any pain relief for less than 4 weeks), and No relief. Forty-one percent of patients had either an excellent/good response to CEI while 34% were no better or worse. Patients presenting acutely or with predominantly leg pain symptoms did not respond any better to the CEI than chronic presentations or low back pain alone. Only 36 of 73 patients who were discharged had an Excellent/Good response. Therefore the response to CEI did not influence the decision to discharge half of the patients. The experience of the surgeon performing the procedure did not make a difference in the outcome. We found that the outcome of CEI was unpredictable. The clinical value of CEI remains unproven. The decision to perform the procedure may well remain a matter of personal choice and experience.

Adolescent↗

PubMed2002

Allograft versus autograft in instrumented posterolateral lumbar spinal fusion: a randomized control trial.

STUDY DESIGN: To evaluate the clinical outcome respective of the type of bone graft used, 69 patients undergoing instrumented lumbar spinal fusion were randomized to receive either their own bone (harvested from the iliac crest) or allograft bone (fresh-frozen femoral head from donors undergoing total hip joint arthroplasty). Self-completed questionnaires were administered before surgery and at intervals thereafter. OBJECTIVES: To compare the clinical outcome of lumbar spinal fusion carried out using either allograft or autograft bone. SUMMARY OF BACKGROUND DATA: Previous studies have suggested that allograft bone is effective in cervical and thoracic fusion operations but that it is less effective in lumbar spinal fusions. Most of these studies used a radiographic means of determining fusion. However, no reliable radiologic assessment method has yet been agreed upon. It has also been shown that radiographic appearance does not correlate with clinical outcome. METHODS: A total of 69 patients undergoing instrumented posterolateral lumbar spinal fusion surgery were randomized to receive either allograft bone from the North East of Scotland Blood Transfusion Service or autologous bone from the iliac crest. The patients were then followed up at 1-year intervals over 6 years regarding clinical outcome. RESULTS: Patients receiving allograft bone had outcome scores similar to those who had received their own bone, except that in the autograft group there was a significant incidence of donor site pain that was persistent in about one sixth of patients. CONCLUSIONS: Allograft bone, in the form of fresh-frozen human femoral head, gives clinical results at least as good as autograft bone in instrumented posterolateral lumbar spinal fusion and completely avoids any donor site complications.

Adult↗