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Biomedical subjects

K P Singer

Publications and source records attributed to K P Singer.

At least 19 recordsLinked to original sources
PubMed2003

Velocity dependent passive plantarflexor resistive torque in patients with acquired brain injury.

OBJECTIVES: This study sought to determine whether factors other than stretch reflex excitability contribute to velocity dependent passive plantarflexor resistive torque following brain injury. BACKGROUND: In patients with acquired brain injury increased resistance to passive muscle lengthening commonly results from abnormal muscle contraction, secondary to disinhibition of descending motor pathways, in addition to rheologic changes within the musculo-tendinous unit. Hyper-excitable tonic stretch reflex responses (spasticity) have traditionally been considered to be the main factor influencing resistance that is velocity dependent. METHODS: Ten adults with brain injury and eighteen age matched controls were studied. A computer controlled torque measurement system was utilised to evaluate resistance to dorsiflexion stretches at two velocities (5 degrees and 25 degrees s(-1)). Only stretches which did not evoke muscle contraction were included in the data analysis. The mean difference and 95% confidence limits in passive plantarflexor resistive torque at two stretch velocities, measured over a defined portion of the test movement, were compared between subject groups. RESULTS: A velocity dependent increase in passive plantarflexor resistive torque was evident when the ankle was dorsiflexed past the neutral position in both subjects with brain injury and controls. However, the mean difference was approximately 10 times greater in neurologically impaired limbs compared with control values. CONCLUSIONS: These data indicate that an important component of velocity dependent resistance to passive muscle lengthening in adults with brain injury can be mechanical, and unrelated to stretch induced reflex muscle contraction. RELEVANCE: Increased resistive torque during rapid muscle lengthening may represent a compensatory adaptation for reduced distal motor control following brain injury. A velocity dependent increase in passive plantarflexor resistive torque has the potential to improve stability during gait and provide mechanical resistance to sudden external perturbations.

Adult↗
PubMed2003

Evaluation of extensibility, passive torque and stretch reflex responses in triceps surae muscles following serial casting to correct spastic equinovarus deformity.

PRIMARY OBJECTIVE: Spastic equinovarus deformity of the ankle in adults with acquired brain injury can severely limit the achievement of rehabilitation goals. This study examined changes in triceps surae muscle extensibility, passive resistive torque and soleus stretch reflex responses in 10 adult brain injured subjects undergoing serial casting to correct ankle equinovarus deformity. METHOD: Goniometric measurement of maximal passive dorsiflexion was used to evaluate extensibility of the triceps surae muscles. Computer controlled ankle dynamometry and surface electromyography were used to identify passive resistive torque and soleus stretch reflex onset angle in response to stretches at two velocities. RESULTS: The mean casting period was 5 weeks. Casting was discontinued in one subject due to failure to achieve measurable gain in ankle range over three consecutive cast changes. Median improvements in maximal ankle dorsiflexion, with the knee flexed or extended, of 30 degrees and 15 degrees, respectively, were achieved in the remaining nine subjects (p < 0.0001). The median passive ankle range in response to a displacing torque of 10 Nm increased 4.3 degrees over the intervention period (p < 0.0001). Consistent soleus reflex activity in response to passive stretches at 25 degrees x s(-1) was elicited in only four subjects. A trend for the stretch reflex onset to move further into the available range was demonstrated in these subjects. CONCLUSION: In the present study, serial casting contributed to significant change in triceps surae extensibility and passive resistive torque, corresponding with improved maximal passive ankle dorsiflexion range and an increase in the angle achieved with a displacing torque of 10 N.m. Increased stretch reflex threshold was observed in some subjects. The use of pre-determined outcome criteria and careful measurement of responses to this intervention were important to prevent premature discontinuation of casting when gains were slower than expected.

Adolescent↗
PubMed2002

Evaluation of triceps surae muscle length and resistance to passive lengthening in patients with acquired brain injury.

OBJECTIVE: To examine changes in muscle length and resistance to passive lengthening in the triceps surae muscles in patients with recently acquired brain injury. BACKGROUND: Increased passive resistance in the triceps surae muscles is common following acquired brain injury. Adaptive shortening secondary to relative immobility, and increased stiffness due to rheologic changes within the musculo-tendinous unit, may be exacerbated by plantarflexor muscle overactivity related to the brain injury itself. DESIGN: Three variables representing resistance to passive lengthening and soleus muscle length were compared between subjects with recent brain injury and age matched normal controls. Comparison between limbs was made for subjects with unilateral neurological impairment. METHODS: Slow passive dorsiflexion stretches were performed using a computer controlled dynamometer. Muscle stiffness in the initial and latter portion of the range, and the angles achieved at torques of 5 and 10 N m were determined from torque-angle curves. Maximal ankle dorsiflexion with the knee flexed was considered to reflect soleus muscle length. RESULTS: Significant differences were demonstrated for all variables, except passive stiffness near the end of available range. The limb ipsilateral to unilateral brain injury differed from control limbs in that significantly less passive range of dorsiflexion was available and initial resistance to passive stretch was significantly less. CONCLUSIONS: The reduction in soleus muscle length evident in subjects with recent acquired brain injury, even in neurologically unaffected limbs, may reflect the influence of relative immobility. Although plantarflexor muscle overactivity was found to be associated with increased resistance to slow passive stretch, the mechanism was unable to be elucidated from these data. The limb ipsilateral to unilateral neurological impairment cannot be considered to be a 'normal' control for comparative purposes. RELEVANCE: Adaptive shortening and increased resistance to passive lengthening limit active ankle dorsiflexion, and alter ankle biomechanics. Tonic muscle overactivity has the potential to exacerbate these changes. Prophylactic management of inappropriate muscle activity and maintenance of muscle length may facilitate the achievement of rehabilitation goals and reduce subsequent disability following acquired brain injury.

Adolescent↗
PubMed2001

Serial plaster casting to correct equino-varus deformity of the ankle following acquired brain injury in adults.

PURPOSE: Proposed mechanisms via which serial casting might effect increased joint range, muscle extensibility and reduced reflex excitability are outlined in this review. Support for these mechanisms stems largely from animal experimental studies. The applicability of these data to human muscle is unknown. ISSUES: Equino-varus deformity of the ankle is a common secondary complication of acquired brain injury. It results from a combination of sequelae of the brain injury and subsequent immobility, including hypertonia, reduced muscle length and increased stiffness. Some evidence exists for the efficacy of serial plaster casts in the treatment of equino-varus deformity, although most reported studies are uncontrolled and involve small numbers of subjects. Serial casting has been shown to result in decreased resistance to passive lengthening and a reduction in dynamic reflex excitability within the lengthened muscles in children with cerebral palsy. Currently documented effects of serial casting in brain injured adults are limited to changes in range of maximal passive dorsiflexion. CONCLUSION: Serial casting should be considered as an adjunct to therapy aimed at improving functional mobility. A variety of therapeutic interventions have been used to augment the effect of the casting regime. Factors that have been demonstrated to be associated with a favourable outcome from serial casting, and recommendations for future research are also discussed in this review.

Brain Injuries↗
PubMed2000

Magnetic resonance-based vertebral morphometry of the thoracic spine: age, gender and level-specific influences.

OBJECTIVE: The aim of this study was to examine age, gender, and segmental trends in thoracic vertebral body shape, utilising thoracic spine magnetic resonance images involving an age range spanning the life span. DESIGN: A quantitative, cross-sectional, retrospective study design involving a sample of convenience. BACKGROUND: Thoracic vertebral shape data are commonly derived from radiographic resources. The non-ionising properties of magnetic resonance imaging and availability of digital data for image analysis suggest potential for MR-based morphometric studies. For the thoracic spine, there is limited vertebral shape data on males, while few studies have examined the pattern of age-related changes across the life span. METHODS: Morphometry was performed on 220 mid sagittal T1-weighted MR images using image analysis software. Three indices of vertebral shape were utilised: the antero-posterior height ratio or anterior wedge index, mid-posterior height ratio or biconcavity index, and ratio of posterior vertebral height to mid antero-posterior diameter or compression index. RESULTS: Different segmental patterns were noted for the vertebral shape indices. Significantly lower mean values were noted in males for the compression index. Age trends were significant, with a linear age-related decline demonstrated for the anterior wedge and biconcavity indices, and a quadratic trend noted for the compression index. CONCLUSIONS: Thoracic vertebral body shape may be uniquely described using specific shape indices, for examining various segmental, gender and age-associated changes. RELEVANCE: These results suggest the importance of defining specific reference criteria for thoracic vertebral body shape indices, particularly age-related data encompassing a wide age range. Magnetic resonance studies enable interpretation of vertebral shape data in relation to the wide spectrum of pathologies afflicting the thoracic spine, without the concerns of ionising radiation.

Adolescent↗
PubMed2000

Influence of age and gender on thoracic vertebral body shape and disc degeneration: an MR investigation of 169 cases.

There are limited data detailing the pattern of age and gender-related changes to the thoracic vertebral bodies and intervertebral discs. A retrospective MR investigation, involving T1-weighted midsagittal images from 169 cases, was undertaken to examine age influences on the anterior wedge (anteroposterior height ratio or Ha/Hp), biconcavity (midposterior height ratio or Hm/Hp), and compression indices (posterior height/anteroposterior diameter or Hp/D) of the thoracic vertebral bodies. Disc degenerative changes in the annulus, nucleus, end-plate and disc margin were noted on T2-weighted sagittal images for the 169 cases, based on a 3-level grading system. A linear age-related decline in the Ha/Hp and Hm/Hp indices was noted. The Hp/D index increased during the first few decades of life, then decreased gradually thereafter. The prevalence of abnormal findings in the annuli, nuclei and disc margins increased with increasing age, particularly in the mid and lower thoracic discs. Greater disc degenerative changes were observed in males. These findings provide further insight into the nature of thoracic vertebral shape changes across the lifespan, and the typical patterns of degeneration of the thoracic intervertebral discs.

Adolescent↗
PubMed2000

MRI evaluation of lumbar spine flexion and extension in asymptomatic individuals.

Flexion and extension movements or positions have been advocated in the treatment of various forms of low back dysfunction due to the potential pain relieving effects attributed to displacements of the intervertebral disc (IVD). Objective in vivo determination of the segmental behaviour of the disc to contrasting positions has until recently been difficult. Magnetic resonance imaging (MRI) was used in this study to evaluate the influence of sagittal plane positions on lumbar IVD height and nucleus displacement in a small asymptomatic population.T2-weighted sagittal plane images from L1 to S1 were obtained from 10 subjects (mean age: 30+/-5 years) positioned supine in lumbar flexion, followed by extension. Changes in disc height and localization of nucleus position (determined by peak MRI signal intensity) between the two positions were calculated. Discs were classified for degenerative changes using a semi-quantitative grading scale. The mean range of lumbar sagittal movement achieved in the MRI was 44 degrees (range: 22-77 degrees ). Between flexion and extension, a significant increase in measured anterior disc height of 1.1 mm (P<0.0001) and anterior displacement of the nucleus of 6.7% (P<0.0001) was observed. Despite the anterior displacement of the nucleus in extension observed in the pooled analysis, 30% of discs did not follow this trend. Nucleus degeneration was observed in at least one disc in nine subjects and in 26% of all discs examined. Lumbar spine position was found to be associated with small measured changes in anterior disc height and nucleus position, however, this response was variable within and between individuals. The theoretical concept of a stereotypical effect of spinal position on the lumbar IVD is challenged by these initial data. Since the health of the disc is often unknown in clinical practice, manual therapy treatment for lumbar spine pain should be based on the symptomatic response to movement and position rather than biomechanical theory.

Adult↗
PubMed2000

Navigating the internet maze.

The 'internet-driven information age' is a term in common usage, implying that everyone can access all the information they need, when they need it. The purpose of this brief paper is to outline some web sources that highlight the possibilities and potential for accessing web-based knowledge. From this the clinician will be encouraged to follow leads along the labyrinth of links to a greater appreciation of how this resource can be used to shape their practice. Examples of web links are provided for: search engines; library-based sources, including medical databases and electronic journals; evidence-based practice databases, mail-groups; electronic conferences; research centres; and general health sources. Importantly, this review does not aspire to be all-inclusive, for the web changes, chameleon-like, to the seasons. The web is here to stay. It will provide the framework for much education and will guide clients to a greater appreciation of their disease or disability than ever before. It may ultimately be the tool through which health fund agents will promote best practice, including self-help to clients, and therefore direct discriminating individuals to select health practitioners who have been endorsed by professional and fund agencies as providing a contemporary service which conforms to evidence-based practice.

Humans↗
PubMed2000

A comparison of three methods for measuring thoracic kyphosis: implications for clinical studies.

OBJECTIVES: To compare the Cobb technique for measuring kyphosis with an alternative Cobb method and a computer-assisted curve assessment technique, and to examine the influence of vertebral body and disc shape on kyphosis. METHODS: Kyphosis measurements were derived from 93 lateral spinal radiographs or sagittal computed tomography images of cadaveric spines, using: (i) a computer-assisted method for estimating radius of curvature; (ii) the traditional Cobb method; and (iii) an alternative Cobb method. Regression models were applied for agreement analyses, and to examine the relative contribution of vertebral body and disc shape on the extent of curvature. Results and conclusions. Strong associations existed between curvature and angle data derived from the three methods, confirming the clinical utility of these techniques for the quantification of thoracic kyphosis. However, the traditional Cobb method tended to overestimate kyphosis in the presence of vertebral body end-plate deformation. The degree of kyphosis was strongly reflective of the extent of deformity of the vertebral bodies, and to a lesser extent the shape of the thoracic discs.

Cadaver↗
PubMed2000

Normal values of plantar pressure measurements determined using the EMED-SF system.

Plantar pressure-measurement technology is being increasingly used by podiatric physicians and surgeons in both clinical practice and research. The authors present normal reference-range values for peak pressure, mean pressure, and pressure-time integral obtained from 30 healthy subjects using a two-step recording technique and the EMED-SF system, as background for proposed clinical trials. Normative data of this type are essential for clinical practice in the comparison of plantar pressure-measurement values of individual patients with those of normal, asymptomatic feet.

Adult↗
PubMed1999

Measurement of vertebral body heights: ex vivo comparisons between morphometric X-ray absorptiometry, morphometric radiography and direct measurements.

Morphometric X-ray absorptiometry (MXA) offers some potential advantages over spinal radiography for the quantitative evaluation of vertebral fractures in individuals with spinal osteoporosis. This ex vivo study examined the accuracy of MXA and quantitative morphometry (QM) for the evaluation of vertebral height, in relation to direct measurements from cadaveric vertebral columns. Spinal radiographs and MXA scans were obtained from nine cadaveric vertebral columns (mean age at death 64 years). Anterior, middle and posterior vertebral body heights of all segments from T4 to L4 were measured interactively using MXA software and QM (from the spinal radiographs), and compared with direct measurements derived using digital callipers following cadaveric dissection. Coefficients of variation for repeat QM and MXA scan analysis were less than 2%. The QM and MXA measurements were both strongly correlated (r(2) = 0.99) with the direct measurements, with accuracy errors of between 2.6% and 4.3%, and 4.5% and 4.8%, for QM and MXA respectively. At the three measurement sites, analysis of measurement differences showed that QM tended to overestimate the true height and MXA tended towards under-estimation. The mean difference between the direct measurements and QM measurements ranged from 2.7% to 8.7%, and the mean difference between direct and MXA measurements ranged from -2. 9% to 4.1%. There was strong linear association between the MXA and QM measurements (r(2) = 0.99) with mean differences at the three measurement sites ranging from -4.1% to -5.9%. Under the optimal (ex vivo) scanning conditions used in this study, MXA is comparable to spinal radiography for the assessment of vertebral height. Further studies are required to determine the conditions under which satisfactory MXA image resolution and measurement accuracy can be achieved in a clinical population.

Absorptiometry, Photon↗
PubMed1999

The relative influence of vertebral body and intervertebral disc shape on thoracic kyphosis.

OBJECTIVE: The aim of this study was to quantify the morphology or shape of thoracic vertebral bodies and intervertebral discs, and to examine the ex vivo association of thoracic kyphosis with these shape parameters. DESIGN: A quantitative, retrospective study design was applied to define vertebral body and disc influences on thoracic kyphosis. BACKGROUND: Age-related progression of thoracic kyphosis is a well-defined process that is influenced by the morphology of vertebral bodies. However, little is known about the contribution of intervertebral disc shape to the thoracic curvature. METHODS: Vertebral and disc morphology, as represented by antero-posterior height ratios, were quantified in 93 lateral spine radiographs and midsagittal computed tomography films of ex vivo spines. Kyphosis was indicated by the Cobb angle. Linear and stepwise regression were applied to examine relationships for cumulative (T1-T12) and regional (T4-T9) analyses. RESULTS: Vertebral morphology was highly predictive of thoracic curvature, while a poorer association was noted for disc morphology. The combined influence of both accounted for >85% of the variability in kyphosis. There was a trend for a more pronounced anterior wedge configuration of the midthoracic vertebral bodies and discs. Higher associations between variables were also noted in this region. CONCLUSIONS: The normal kyphosis of the thoracic spine reflects the morphological adaptation of both the vertebral bodies and intervertebral discs. RELEVANCE: This study contributes new data on the thoracic spine, particularly the characteristics of thoracic discs and their contribution to kyphosis genesis. Future directions for morphology studies should encompass more detailed examination of the thoracic discs and greater emphasis on the midthoracic segments, considering the prevalence of osteoporosis related fractures and subsequent deformity at these levels.

Adult↗
PubMed1999

Assessment of combined movements of the lumbar spine in asymptomatic and low back pain subjects using a three-dimensional electromagnetic tracking system.

Combined movement examination (CME) is used by physiotherapists to assess and treat patients with low back pain (LBP). However, this method has not been subjected to quantitative assessment. The purpose of this study was to discover if CME of the lumbar spine could be measured with acceptable intra-examiner reliability and to make a preliminary investigation of the effect of LBP on the results of CME. Combined movement examination of the human thoracolumbar spine was measured using a three-dimensional electromagnetic goniometer (3SPACE Fastrak Polhemus, Colchester, Vermont, USA). 1. Intra-examiner reliability of CME was evaluated using a test-retest design; examination was repeated in 23 subjects without LBP and 16 with LBP. 2. A sample of 31 subjects without LBP and 23 subjects with LBP underwent CME, which involved measuring right and left sideflexion in the flexed, neutral and extended position. Pearson's r and the intraclass correlation coefficient for all variables ranged from 0.79 to 0.93 (P < 0.05). A MANOVA test (P < 0.05), comparing the combined effects of the two variables for each position, was used to test for a difference between the positions attained by the subjects with LBP and those without. Generally LBP subjects showed smaller ranges of movement than those without LBP. Each position was recorded as a degree of rotation around the x-axis (flexion/extension) and around the y-axis (left and right sideflexion). CME can be carried out with acceptable intra-examiner reliability; preliminary evidence is presented concerning the effectiveness of CME in identifying reduced spinal movement in LBP subjects.

Adult↗
PubMed1999

The effect of hallux valgus correction on chronic plantar ulceration. A case report.

Plantar pressure-measurement technology may provide the clinician with valuable objective information for monitoring the effects of therapeutic intervention on the foot. The use of this technology is described in the preoperative and postoperative assessment of a patient undergoing hallux valgus surgery for the treatment of a chronic neuropathic skin ulcer over the medioplantar aspect of her first metatarsophalangeal joint.

Aged↗
PubMed1998

Review of radiographic measurements following Austin bunionectomy.

This study compared preoperative and postoperative results for selected radiographic measurements of 30 patients undergoing the modified Austin bunionectomy procedure for the correction of hallux abducto valgus. Significant reductions in all postoperative radiographic values were demonstrated, including hallux abductus angle, metatarsus primus adductus angle, tibial sesamoid position, and first metatarsal protrusion distance.

Adult↗