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Biomedical subjects

D Wardlaw

Publications and source records attributed to D Wardlaw.

At least 19 recordsLinked to original sources
PubMed2006

Mechanical properties of calcium sulphate/hydroxyapatite cement.

Setting times, volume after setting, injectability and hardness (at 37 degrees C in contact with Ringer's solution) were determined for cements made of mixtures of calcium sulphate hemihydrate (CS) and hydroxyapatite (HA) with a range of compositions. The purpose of these experiments was to determine the behaviour of a mixture that could be used as an injectable cement for orthopaedic applications, including spinal fusion. A suitable mixture consisted of 60% CS and 40% HA by mass; a slurry was made by mixing solid (36 g) with water (15 cm(3)). The slurry had initial and final setting times of 5.7+/-1.3 min and 19.6+/-0.7 min (mean +/- standard deviation), respectively. The hardness of the cement did not systematically increase or decrease in the 72 h following the final setting time. The volume of the cement was 99.8+/-0.4% of the volume of the initial slurry, i.e. there was negligible shrinkage on setting. It was able to withstand a pressure of 7.3+/-1.2 MPa, applied by a hemispherical indenter before the onset of permanent damage, indicating adequate strength for spinal fusion.

Biocompatible Materials↗
PubMed2004

Does early imaging influence management and improve outcome in patients with low back pain? A pragmatic randomised controlled trial.

OBJECTIVES: To establish whether the early use of sophisticated imaging techniques influences the clinical management and outcome of patients with low back pain (LBP) and whether it is cost-effective. DESIGN: A pragmatic multicentre randomised controlled trial using a standard two parallel group approach incorporating an economic evaluation. For a subgroup of trial participants, a controlled 'before and after' approach was used to assess the impact of 'early imaging' on clinicians' diagnostic and therapeutic confidence. SETTING AND PARTICIPANTS: A total of 782 participants who had been referred by their general practitioner to a consultant orthopaedic specialist or neurosurgeon because of symptomatic lumbar spine disorders. The study included 14 hospitals in Scotland and one in England over a 24-month period. RESULTS: Participants in both groups reported an improvement in health status at 8 and 24 months with the 'early imaging' group having statistically significantly better outcome. Other than the proportion of participants receiving imaging (90% versus 30%), there were few differences between the groups in the management received throughout the 24-month follow-up. The total number of outpatient consultations in the two groups was similar although more people in the 'early imaging' group had return outpatient appointments during the 8-month follow-up. Clinicians' diagnostic confidence, between trial entry and follow-up, increased significantly for both groups with a greater increase in the 'early imaging' group. The cost of imaging was the main determinant of the difference in total costs between the groups and it was estimated that 'early imaging' could provide an additional 0.07 quality-adjusted life-years (QALYs), at an additional average cost of 61 British pounds over the 24-month follow-up. Using non-imputed costs and QALYs but adjusted for baseline differences in EQ-5D score, the mean incremental cost per QALY of 'early imaging' was 870 British pounds. The results were sensitive to the costs of imaging and the confidence intervals surrounding estimates of average costs and QALYs. CONCLUSIONS: The early use of sophisticated imaging does not appear to affect management overall but does result in a slight improvement in clinical outcome at an estimated cost of 870 British pounds per QALY. Imaging was associated with an increase in clinicians' diagnostic confidence, particularly for non-specialists. Further research is required to determine if more rapid referral to sophisticated imaging and secondary care is important in the acute episode and whether the use of imaging would be more beneficial for particular categories of LBP.

Adult↗
PubMed2003

Aberdeen Colles' fracture brace as a treatment for Colles' fracture. A multicentre, prospective, randomised, controlled trial.

We carried out a randomised, prospective, multicentre clinical trial of the treatment of Colles' fractures. A total of 339 patients was placed into two groups, those with minimally displaced fractures not requiring manipulation (151 patients) and those with displaced fractures which needed manipulation (188 patients). Treatment was by either a conventional Colles' plaster cast (a control group) or with a prefabricated functional brace (the Aberdeen Colles' fracture brace). Similar results were obtained in both groups with regard to the reduction and to pain scores but the brace provided better grip strength in the early stages of treatment. This was statistically significant after five weeks for both manipulated and non-manipulated fractures. At the tenth day the results were statistically significant only in manipulated fractures. There was no significant difference in the functional outcome between the two treatment groups. However, younger patients and those with less initial displacement had better functional results.

Adult↗
PubMed2001

Slippage of a spinous process hook during flexion in a flexible fixation system for the lumbar spine.

This study was undertaken to measure the amount of slippage of a spinous process hook (that forms part of a flexible fixation system) during flexion. Human cadaveric lumbar spines (10) were fitted with the device. A rig was designed to apply flexural displacements to a spine using a materials testing machine. Spherical markers were attached to the spine and hook. As a spine was flexed a digital video camera was used to record the positions of the markers. The movements of the markers were measured using interactive computer software to assess any slippage of the spinous process hook. During flexion the overall mean hook slippage was measured to be 0.10mm (standard deviation 0.04mm). The mean hook slippage, for each of the 10 specimens, was in the range of 0.05-0.14mm. The results imply that slippage of a spinous process hook during flexion is small.

Adult↗
PubMed2001

Diagnosis of lumbosacral nerve root anomalies by magnetic resonance imaging.

This study evaluates the use of magnetic resonance imaging (MRI) in the diagnosis of lumbosacral nerve root anomalies. Prevalence of anomalous nerve roots has been based on anatomic dissection or preoperative neuroradiologic investigations. Three hundred seventy-six patients with low back pain and/or radicular pain who underwent MRI of the lumbar spine were reviewed. Sixty-five cases of nerve root anomalies were found (an incidence of 17.3%) of which 1 case of cranial origin, 5 cases of caudal origin, 2 cases of conjoined nerve root, and 57 cases of furcal nerve roots (15.1%) were identified. Furcal nerve roots were most commonly found at L3 and L4 levels and were classified, according to their division, into intra-and extraforaminal. MRI provided accurate information on lumbosacral nerve root anomalies.

Humans↗
PubMed2001

Influence of imaging on clinical decision making in the treatment of lower back pain.

PURPOSE: To assess the impact of cross-sectional imaging with magnetic resonance (MR) imaging or computed tomography (CT) on clinical decision making for patients with lower back pain (LBP). MATERIALS AND METHODS: A randomized controlled before-and-after study was performed in 145 patients who had symptomatic lumbar spinal disorders and had been referred to orthopedists or neurosurgeons. Participants were a subgroup within a multicenter pragmatic randomized comparison of two imaging policies on LBP treatment: "imaging" versus "no imaging," unless a clear indication developed. Paired assessments were made of diagnosis, diagnostic confidence, proposed treatment, treatment confidence at trial entry and follow-up, and expectations of imaging. Data were analyzed according to the groups as randomized. RESULTS: At follow-up, there were no statistically significant differences between the groups with respect to diagnosis or treatment plans. Significant increases in diagnostic and therapeutic confidence between trial entry and follow-up were observed for both groups, with a significantly greater increase in diagnostic confidence (P =.01) in the imaging group. CONCLUSION: Imaging may increase diagnostic confidence but has minimal influence on diagnostic or therapeutic decisions for patients with LBP. The results highlight the need for evidence-based guidelines for imaging in LBP treatment.

Adult↗
PubMed2000

Correlation between the MRI changes in the lumbar multifidus muscles and leg pain.

AIM: In the assessment of the lumbar spine by magnetic resonance imaging (MRI), changes in the paraspinal muscles are frequently overlooked. In this study, our objective was to investigate the relationships between lumbar multifidus (MF) muscle atrophy and low back pain (LBP), leg pain and intevertebral disc degeneration. METHODS: A retrospective study of 78 patients (aged 17-72) with LBP presenting with back pain with or without associated leg pain was undertaken. Their MR images were visually analysed for signs of lumbar MF muscle atrophy, disc degeneration and nerve root compression. The clinical history in each case was obtained from their case notes and pain drawing charts. RESULTS: MF muscle atrophy was present in 80% of the patients with LBP. The correlation between MF muscle atrophy and leg pain was found to be significant (P < 0.01). However, the relationships between muscle atrophy and radiculopathy symptoms, nerve root compression, herniated nucleus pulposus and number of degenerated discs were statistically not significant. CONCLUSION: Examination of the paraspinal muscles looking for atrophy of MF muscle should be considered when assessing MR images of lumbar spine. This may explain the referred leg pain in the absence of other MR abnormalities.

Adolescent↗
PubMed2000

Design of spinous process hooks for flexible fixation of the lumbar spine.

A prototype flexible fixation system for the lumbar spine was subjected to tensile testing to failure and cyclic tensile testing in order to determine any regions of weakness. The system consisted of a spinous process hook and two laminar hooks made of stainless steel (316L). Each laminar hook was attached to the spinous process hook by a loop of polyester braid secured by a crimped metal sleeve. In five tensile tests, the system failed by irreversible deformation of the spinous process hook at 2.5 +/- 0.3 kN (mean +/- standard deviation). In three cyclic tests, in which the applied tension varied sinusoidally between 0.04 and 0.4 kN at a frequency of 5 Hz, failure occurred after less than 400,000 loading cycles. This occurred as a result of fatigue crack initiation and propagation in the spinous process hook. A finite element model showed a stress concentration in the region where the crack occurred, which raised the applied stress above the tensile fatigue strength of this stainless steel. The spinous process hook was redesigned for manufacture in a titanium alloy (Ti-6AI-4V ELI) to minimize artefacts in magnetic resonance imaging. Further finite element models showed no unacceptable stress concentrations.

Alloys↗
PubMed2000

Development of surgical instruments for implanting a flexible fixation device for the lumbar spine.

A new flexible fixation device for the lumbar spine has been developed. This paper describes the development and evaluation of two surgical instruments required for implanting this device. Prototypes were designed, manufactured and then evaluated for use in surgery. Further evaluation was performed, if necessary, and the design finalized, in accordance with BS EN 12011. This process involved close collaboration between engineers and surgeons.

Equipment Design↗
PubMed1999

Biomechanical assessment of gait in below-knee walking casts.

The introduction of modern synthetic casting bandages for splinting of fractures and soft tissue injuries has allowed the development of new casting techniques. Casts can be constructed with a greater degree of function so that controlled motion and stabilisation can be provided within the same cast. This study has shown that a very efficient gait can be achieved with modern synthetic bandages, if they are correctly applied. The authors have compared the gait of volunteer subjects fitted respectively with below-knee walking casts constructed from a rigid glass fibre bandage and a flexible glass fibre bandage which is reinforced. These casts were wrapped so that minimal amounts of bandage were used whilst appropriate strength and stiffness was provided. The temporal and spatial factors of cast gait were not statistically different from normal gait. The cast gait was found to be slightly more asymmetrical (dominant versus non-dominant leg) when a cast was worn and there was also a greater Physiological Cost Index (PCI). The flexible bandage has some advantages compared with the rigid bandage as normal footwear can be worn, the casts are more comfortable and they could be removed with shears, obviating the need for a power saw.

Adult↗
PubMed1999

Functional bracing of Colles' fractures.

Colles' fracture is one of the most common injuries encountered in orthopaedic practice and yet there is no optimum method for its management. Various operative treatments have been proposed because of the instability of the fracture following reduction. However, considering the epidemiology of the fracture, the majority of these injuries will continue to be treated conservatively with closed reduction and immobilization of the wrist in a cast. Functional bracing is an alternative to cast immobilization, allowing early return of function while maintaining fracture reduction, and is an accepted method of treatment for a number of injuries. Although various methods of functional treatment of Colles' fractures have been described, it has not proved a popular management modality in this injury. We review previous studies of functional bracing and describe a novel method of bracing that we have developed.

Adolescent↗
PubMed1995

A new functional brace for the treatment of Colles' fractures.

A new prefabricated brace for the functional treatment of Colles' fractures has been developed. It is applied at fracture reduction and maintains fracture position by the application of three-point loading. In a prospective randomized clinical trial treating 85 displaced Colles' fractures, with blind independent follow-up, the brace gave better functional results than conventional plaster treatment. The improved function was apparent up to 6 months after injury. Finger function and pinch strength were also better in the brace-treated patients. Anatomical results were similar in the two groups.

Adult↗
PubMed1995

Traumatic dislocation of the lateral sesamoid of the great toe: nonoperative management.

A case of traumatic dislocation of the lateral sesamoid of flexor hallucis brevis tendon associated with metatarsal neck fractures due to a crush injury is reported. This patient was treated nonoperatively by elevation, application of plaster, and then free mobilisation. The patient has now fully recovered and remains completely asymptomatic despite residual sesamoid dislocation 1 year after the injury. The nonoperative management of this injury has not, to our knowledge, been reported previously.

Adult↗
PubMed1994

Developing a valid and reliable measure of health outcome for patients with low back pain.

OBJECTIVE: The authors developed and validated a measure of health outcome for patients with low back pain. RESULTS: A questionnaire was developed incorporating the type of questions asked when taking a clinical history. After testing on a sample of 568 patients, three questions were discarded from the questionnaire. The final questionnaire was found to be reliable and valid in the sense that patients' scores correlated highly with their scores on a general health profile and with GP perceptions of severity. Health status in patients with low back pain was significantly impaired when compared with the general population. CONCLUSION: A clinically based questionnaire, together with a general measure of health, can provide a valid and reliable package for the routine assessment of perceived health in patients with low back pain.

Activities of Daily Living↗
PubMed1992

Glass fibre versus non-glass fibre splinting bandages.

We have assessed the current range of synthetic splinting bandages, comparing glass with non-glass fabrics and plaster-of-Paris. Physical and mechanical tests have been carried out and the opinions of patients, volunteers and orthopaedic staff were recorded. Modern bandages have some better properties than standard plaster bandage but do not conform as well, are more expensive and potentially more hazardous. However, non-glass bandages are lighter, less brittle, more radiolucent and less hazardous than glass fibre bandages and are preferred by both patients and applicators.

Attitude to Health↗
PubMed1991

On immediate functional bracing of Colles' fracture.

A prospective randomized trial was carried out in 60 consecutive patients with Colles' fractures requiring manipulation. They were treated by either a standard Colles' plaster (control group) or in a functional plaster brace applied immediately after reduction of the fracture. The brace extended from the proximal radius and ulna to the level of the radial styloid and allowed a full range of movement at the radiocarpal joint. Both groups comprised 30 patients and were matched for age, sex and dominance of hand. There was no significant difference in initial severity of fracture or the quality of reduction. Radiological results on cast removal (35-42 days) were significantly better in the brace group compared with those treated with a below-elbow cast (P less than 0.05). Wrist function was also significantly better in the brace treated group at 12 weeks after fracture (P less than 0.05). This brace has a number of advantages over standard plaster treatment, but requires a degree of skill and experience in its application. A prefabricated brace has now been developed with a similar 'built in' three-point loading which will be easier for inexperienced staff to apply.

Adult↗
PubMed1991

Intracast pressure measurements in Colles' fractures.

Intracast pressures were recorded in conventional plaster-of-Paris below-elbow casts and compared with a new prefabricated brace for the functional treatment of Colles' fractures. Interface pressures were consistently higher in the brace than in the conventional plaster cast throughout the treatment period, and demonstrated more specific loading to the fracture site.

Adolescent↗