Color Doppler ultrasonography of lumbar artery blood flow in patients with low back pain.

STUDY DESIGN: Prospective, clinical, noninvasive imaging study. OBJECTIVE: To quantify normal lumbar artery hemodynamics and develop a reference range and lumbar artery hemodynamics in patients with low back pain. SUMMARY OF BACKGROUND DATA: Blood supply to the lumbar spinal tissues, intraosseous capillary circulation, and avascular intervertebral discs derives directly from the lumbar arteries. Pathology may affect this blood supply, impact nutrient delivery and contribute to low back pain and disc degeneration. However knowledge of hemodynamic characteristics of lumbar arteries is lacking. This could improve understanding into pathological tissue function and its relation to lumbar spine circulation in back disorders. METHODS: Sixty-four patients with low back pain and 30 normal controls underwent lumbar spine imaging investigations with color Doppler ultrasonography. Doppler data on blood flow was obtained from arteries at S1 through to L1 bilaterally and angle-corrected peak systolic blood flow velocity (PSV) measured in all vessels. Aortic PSV was used to derive the normalized lumbar artery: Aortic PSV ratio (PSVR) for all subjects' levels L1 to S1 bilaterally. RESULTS: In both the control and low back pain (LBP) groups blood flow PSV in the lumbar arteries increased incrementally from levels L1 to L4, declined to its lowest values at L5 and rose again at S1. Normalized lumbar artery blood flow PSVR in the LBP group is consistently higher at all levels (L1-S1) than in controls (P < 0.001). At level L5, lumbar artery blood flow PSVR was 46% higher in the LBP group than in controls. CONCLUSION: Color Doppler ultrasonography can reliably be used as a clinical tool to visualize and quantify blood flow in lumbar arteries of patients with low back disorders. Findings of increased blood flow PSVR in patients are consistent with the well-documented Doppler changes that occur during inflammatory hyperemia. LEVEL OF EVIDENCE: 3.

The impact of intermittent retraction on paraspinal muscle function during lumbar surgery.

STUDY DESIGN: Prospective cohort study. OBJECTIVE: To study the effect of surgical retraction on paraspinal muscle function and investigate the effect of intermittent muscle retraction. SUMMARY OF BACKGROUND DATA: Paraspinal muscle retraction leads to increased intramuscular pressure with a reduction in local blood flow resulting in ischemic damage. This may lead to muscle dysfunction and increased back pain after surgery. METHODS: Two groups of 20 patients underwent one-level decompressive lumbar surgery. Group A underwent continuous muscle retraction, group B underwent intermittent muscle retraction. All patients completed pain questionnaires and underwent spinal strength assessment, paraspinal needle electromyography (EMG) before and after surgery, and had intraoperative muscle biopsy analysis using the technique of birefringence. RESULTS: Pain questionnaires revealed a reduction in back pain in all patients following surgery; patients with shorter retraction times had less pain (P < 0.05). Paraspinal muscle histochemistry revealed patients with shorter muscle retraction times and patients who underwent intermittent muscle retraction has less damage (P < 0.05). Isometric strength testing revealed patients in the intermittent retraction group had a less profound reduction in strength after surgery (P < 0.05). Needle EMG data and pain questionnaires showed no differences between the continuous and intermittent groups, although EMG data did show that muscle shows evidence of reinnervation after surgery. CONCLUSION: Although histologically there was a reduction in muscle damage in patients that underwent intermittent retraction, there was no benefit on clinical outcome. Paraspinal muscle shows evidence of reinnervation after surgery.

The effect of different insertion points on the security of pedicle screw fixation in bovine vertebrae.

STUDY DESIGN: Cyclic loading of pedicle screws inserted into bovine vertebrae was applied and the security of fixation was assessed as a function of the point of insertion of the screws. OBJECTIVE: To determine which point of insertion is associated with more secure fixation using 2 commonly selected insertion points. SUMMARY OF BACKGROUND DATA: The strength of pedicle screw fixation depends on several factors, some of these have been studied. The present study looked at the difference in fixation security resulting from the use of 2 different insertion points to obtain a more stable fixation and to reduce the risk of loosening. METHODS: Pedicle screws were inserted through a different insertion point on each side of the vertebra, one lateral to the superior articular process and one through the superior articular process and into the pedicle. They were tested by applying cyclic loading in a craniocaudal direction and the vertical displacement was measured. Permanent migration of the screw through the bone was compared using repeated measures analysis of variance. RESULTS: Screws inserted lateral to the process were associated with significantly less displacement than those placed through the process (P = 0.02). CONCLUSION: Using bovine vertebrae, different points of insertion of pedicle screws were associated with different security of fixation. However, further tests using human vertebrae are recommended to confirm the above results.

Colour doppler ultrasound of the lumbar arteries: a novel application and reproducibility study in healthy subjects.

Lumbar arteries are important because they are the main source of blood supply to the lumbar spine structures. However, these vessels and their flow characteristics have received little attention and their role in conditions such as low back pain remains unclear. The present study 1. describes the application of duplex ultrasonography in the assessment of lumbar artery blood flow and 2. evaluates the interobserver and intraobserver reproducibility of lumbar artery Doppler velocimetry. A total of 13 healthy volunteers were evaluated by two different examiners successively on the same day and measurements repeated by the same examiners 1 week later. Peak systolic velocities of lumbar arteries were recorded at an optimal angle below 60 degrees . Overall mean peak systolic velocity (+/-SD) for lumbar arteries was 0.158 +/- 0.051 m/s, and mean Doppler angle (+/-SD) was 24.6 +/- 14.5 degrees . For interobserver variability, the coefficient of variation was 23.4% and SD of differences 0.037 m/s. Reliable results of lumbar artery Doppler velocimetry demonstrate its applicability in future clinical investigations in patients with low back disorders. (E-mail: ).

Does preoperative hip rehabilitation advice improve recovery and patient satisfaction?

The goal of the current study was to investigate whether preoperative rehabilitation advice reinforced by a patient information booklet can aid recovery after total hip arthroplasty in terms of pain, function, satisfaction, and quality of life. Thirty-five patients awaiting primary total hip arthroplasty were recruited into this study and randomly allocated before admission to receive either the standard pathway of care or the rehabilitation program and booklet. All patients showed increases in function and psychological variables with time. The preoperative class and booklet, however, seemed to have the greatest impact on length of hospital stay, reducing the hospital stay by 3 days, and therapy input required, significantly influencing the cost of the procedure (the rehabilitation class led to a cost saving of 587 British pounds; approximately 810 dollars, per patient). In addition, patients attending the class reported higher levels of satisfaction (99% satisfied in the preoperative rehabilitation class compared with 80% in the control group 3 months postoperatively) and had more realistic expectations of surgery.

Back pain and disability after lumbar laminectomy: is there a relationship to muscle retraction?

OBJECTIVE: Preliminary studies have suggested that prolonged retraction of the paraspinal muscle during spinal surgery may produce ischemic damage. We report the continuous measurement of intramuscular pressure (IMP) during decompressive lumbar laminectomy and its relationship to subsequent back pain and disability. METHODS: Twenty patients undergoing two-level decompressive lumbar laminectomy for lumbar canal stenosis were recruited. Back pain and disability were assessed by use of the Visual Analog Score (VAS), Oswestry Disability Index (ODI), and Short-Form 36 (SF-36) Health Survey. During surgery, IMP was recorded continuously from the multifidus muscle by use of a pressure transducer. The intramuscular perfusion pressure (IPP) was estimated as the difference between the patient's mean arterial pressure and IMP. RESULTS: Two muscle retractors were used: the Norfolk and Norwich (n = 10) and the McCulloch (n = 10). The mean duration of deep muscle retraction was 62.7 +/- 8 minutes (range, 19-133 min). On application of deep muscle retraction, there was a rapid and sustained increase in IMP (P < 0.001), and overall, the calculated mean IPP approached 0 mm Hg or less during this period (P < 0.001). On release of deep muscle retraction, there was a rapid decrease in IMP to preoperative levels. The IPP was greater with the Norfolk and Norwich than the McCulloch retractor (P < 0.001). Compared with preoperative values, there was a decrease in ODI (P < 0.001) and VAS for back pain (P < 0.001) at discharge and 4 to 6 weeks and 6 months after surgery. In addition, there was a decrease in SF-36 scores at 6 months compared with preoperative values (P < 0.001). Total duration of muscle retraction greater than 60 minutes was associated with worse VAS scores for back pain and ODI and SF-36 scores for disability at 6 months after surgery (P < 0.05). There was no relationship between the VAS, ODI, and SF-36 scores and other parameters measured, including the mean IPP, retractor type, operating surgeon, and wound length. CONCLUSION: The McCulloch retractor generates a higher IMP than the Norfolk and Norwich retractor. However, postoperative improvement in VAS, ODI, and SF-36 scores in these patients was associated with a shorter duration of muscle retraction and not the degree of IMP or IPP generated. In this respect, periodic relaxation of the paraspinal muscle retractors during surgery to allow muscle perfusion may help to reduce postoperative back pain and disability.

MR imaging of degenerative disc disease in the lumbar spine with ultrashort TE pulse sequences.

OBJECTIVE: The objective of this study was to assess the feasibility of using ultrashort TE (UTE) pulse sequences to image the lumbar spine. MATERIALS: Pulse sequences of TE=0.08 ms were used to image the lumbar spine in 5 normal subjects and 14 patients with degenerative disease. Contrast enhancement was administered in 11 cases. RESULTS: The sequences showed high signal in the anterior and posterior longitudinal ligaments, the cartilaginous end plate, the annulus fibrosus, the ligamentum flavum, interspinous ligaments and insertions of ligaments. Normal contrast enhancement was seen in these structures. Enhancement of hypertrophied ligaments and scar tissue was readily identified. Long T2 suppression techniques were useful in distinguishing enhancement of scar tissue from veins. Enhancement in discs was more obvious than with conventional sequences. In a case of thalassaemia bands of high signal were seen in the intervertebral discs parallel to the end plates. CONCLUSION: The UTE sequences offer new options for visualizing discs, scar tissue, ligaments and other structures of the lumbar spine in health and disease.

The impact of self-retaining retractors on the paraspinal muscles during posterior spinal surgery.

STUDY DESIGN: This was a prospective pilot study examining pre-, intra- and postoperative measures. OBJECTIVES: The aim of the study was to investigate the effect of muscle retractors on the posterior spinal muscles during posterior spinal surgery. SUMMARY OF BACKGROUND DATA: Previous studies have identified changes in the structure and function of the back extensor mechanism as a result of low back pain. However, the effect of surgery on the functioning of these muscles, particularly surgical retraction, has received less attention. METHODS: Twenty patients undergoing posterior spinal surgery were recruited into this study, and recordings of intramuscular pressure during surgery were performed using a pressure-monitoring system before insertion of retractors, 5, 30, and 60 minutes into surgery, and on removal of retractors. Before and following use of the retractors, muscle biopsies were taken from the multifidus muscle for analysis using birefringence techniques. RESULTS: A significant increase in intramuscular pressure (P < 0.001) was observed during surgery. On removal of retractors, this pressure returned to or near to the original value. Analysis of muscle biopsies using calcium activated adenosine triphosphatase birefringence revealed a reduction in muscle function following prolonged use of self-retaining retractors. CONCLUSIONS: A substantial rise in pressure in the erector spinae muscle during posterior spinal surgery was observed, and this appeared to be associated with marked changes in the function of the muscles. This could be an important factor in the generation of operative scar tissue and postoperative dysfunction of the spinal muscles.

The use of interventional open MRI to assess the kinematics of the lumbar spine in patients with spondylolisthesis.

STUDY DESIGN: Open interventional MRI techniques were used to investigate the intervertebral mobility of the lumbar spine in subjects with isthmic and degenerative spondylolisthesis. The findings were compared with those in a published database of subjects with no history of low back pain. OBJECTIVE: To investigate patterns of intervertebral mobility in subjects with spondylolisthesis to determine the level of spinal instability in this population. SUMMARY OF BACKGROUND DATA: Subjects with spondylolisthesis have been considered to present with a special form of spinal instability. Consequently, this condition is frequently managed by spinal fusion. However, confusion exists regarding whether there is excessive motion at the level of the defect. METHODS: For this study, 29 subjects presenting to spinal clinics with spondylolisthesis (15 isthmic and 14 degenerative) were recruited and compared with an existing database of control subjects. The motion characteristics of these subjects in flexed and extended positions were investigated using interventional open MRI of known precision. In all the subjects, the level of resting pain, the grade of slip, and the level of the defect were noted. RESULTS: No mobility differences, in terms of both angular and translational motion, were found between the subjects with spondylolisthesis and those with no history of low back pain, suggesting that subjects with spondylolisthesis do not present with either instability or hypermobility. CONCLUSION: A spondylolytic defect does not lead to detectable instability or hypermobility in the lumbar spine.

The evaluation of the surgical management of nerve root compression in patients with low back pain: Part 1: the assessment of outcome.

STUDY DESIGN: This was a prospective study investigating the outcome of decompression surgery using validated measures of outcome. OBJECTIVES: To investigate the outcome of lumbar decompressive surgery in the initial postoperative year period in terms of function, disability, general health, and psychological well-being. SUMMARY OF BACKGROUND DATA: The majority of studies investigating the outcome of lumbar decompression surgery have been retrospective and have not used validated measures of outcome. This limits their interpretation and usefulness. METHODS: Eighty-four patients undergoing lumbar spinal stenosis surgery were recruited into this study. Patients were assessed by use of validated measures of outcome including the Oswestry Disability Index and the Short Form SF-36 General Health Questionnaire before surgery and 6 weeks, 6 months, and 1 year after surgery. RESULTS: A significant reduction in pain (P < 0.001) was observed at the 6-week postoperative stage; this did not change at the subsequent assessment stages. Only some of the SF-36 categories were sensitive to change. The subcategories that were sensitive to change were physical function (P < 0.05), bodily pain (P < 0.001), and social function (P < 0.05). Improvements were observed in these categories at the 6-week and 6-month reviews. A gradual reduction in the Oswestry Disability Index was observed with time, with changes principally being observed between the 6-week and 6-month review and the 6-week and 1-year review stages (P < 0.05). Minimal changes were observed in the psychological assessments with time. The outcome of surgery could not be predicted reliably from psychological, functional, or pain measures. CONCLUSIONS: The visual analogue pain scales, the Oswestry Disability Index, and certain categories of the SF-36 Questionnaire, namely bodily pain and physical and social function, appeared to be the most sensitive outcome measures, with significant improvements occurring at the 6-week and 6-month reviews.

The evaluation of the surgical management of nerve root compression in patients with low back pain: Part 2: patient expectations and satisfaction.

STUDY DESIGN: This was a prospective study investigating patient expectations of and satisfaction with the outcome of decompression surgery. OBJECTIVES: To investigate patient expectations of surgery and short- and long-term satisfaction with the outcome of decompression surgery in terms of pain, function, disability, and general health. SUMMARY OF BACKGROUND DATA: Information is scarce regarding patient-rated expectations of surgery and measures of satisfaction with surgery in terms of specific outcome measures such as pain. METHODS: Eighty-four patients undergoing spinal stenosis surgery were recruited into this study. Before surgery, patients were also asked to rate their expectations in terms of improvement in pain, general health, function, and other such characteristics. In addition, at each postoperative review stage, patients were asked to rate their satisfaction with their improvement in these key outcome measures. RESULTS: The results demonstrated that patients had very high expectations of recovery, particularly in terms of pain and function, and that patients were confident of achieving this recovery (76.8%). Levels of satisfaction, however, varied considerably: 41% of patients were 50% satisfied with the outcome, and 30% were dissatisfied. Most patients felt that they had made the right decision to have surgery, although the surgery had achieved only 43.4% +/- 37.8 of the outcome they had expected. CONCLUSIONS: Examination of patients' expectations of and satisfaction with surgery revealed that patients frequently had unrealistic expectations of their surgery and as a consequence tended to have lower levels of satisfaction.

Nerve fibers in lumbar spine structures and injured spinal roots express the sensory neuron-specific sodium channels SNS/PN3 and NaN/SNS2.

STUDY DESIGN: This prospective study examined the innervation of lumbar spine in tissues from patients with lower back pain and spine nerve roots from patients with traumatic brachial plexus injuries. OBJECTIVES: To demonstrate the presence of nerve fibers in lumbar spine structures and spine nerve roots, and to determine whether they express the sensory neuron-specific sodium channels SNS/PN3 and NaN/SNS2. SUMMARY OF BACKGROUND DATA: The anatomic and molecular basis of low back pain and sciatica is poorly understood. Previous studies have demonstrated sensory nerves in the facet joint capsule and prolapsed intervertebral disc, but not in the ligamentum flavum. The voltage-gated sodium channels SNS/PN3 and NaN/SNS2 are expressed by sensory neurone that mediate pain, but their presence in the lumbar spine is unknown. METHODS: Tissue samples of ligamentum flavum (n = 32), facet joint capsule (n = 20), intervertebral disc (n = 15), and spine roots (n = 8) were immunostained with specific antibodies to protein gene product 9.5 (a panneuronal marker), SNS/PN3, and NaN/SNS2. RESULTS: Protein gene product 9.5 immunoreactive nerve fibers were detected in 72% of the ligamentum flavum specimens and 70% of the facet joint capsule specimens, but in only 20% of the intervertebral disc specimens. The study detected SNS/PN3- and NaN/SNS2-positive fibers, respectively, in 28% and 3% of the ligamentum flavum specimens and 25% and 15% of the facet joint capsule specimens. Numerous SNS/PN3- and NaN/SNS2-positive fibers were found in the acutely injured spine roots, and some were still present in the dorsal roots in the chronic state. CONCLUSIONS: As the findings showed, SNS/PN3- and NaN/SNS2-immunoreactivity is present in a subset of nerve fibers in lumbar spine structures, including ligamentum flavum, and in injured spine roots. Selective SNS/PN3- and NaN/SNS2-blocking agents may provide new therapy for back pain and sciatica.