Biomedical subjects

C J Snijders

Publications and source records attributed to C J Snijders.

At least 19 recordsLinked to original sources

PubMed2001

Reliability and validity of the active straight leg raise test in posterior pelvic pain since pregnancy.

STUDY DESIGN: A cross-sectional analysis was performed in a group of women meeting strict criteria for posterior pelvic pain since pregnancy (PPPP). The scores on the Active Straight Leg Raise Test (ASLR test) were compared with the scores of healthy controls. OBJECTIVES: To develop a new diagnostic instrument for use in patients with PPPP. The objectives of the present study were to assess the validity and reliability of the ASLR test. SUMMARY OF BACKGROUND DATA: Various diagnostic tools are used to diagnose PPPP, but there is still a need for simple tests with high reliability, sensitivity, and specificity. METHODS: Reliability of the ASLR test was assessed in a group of 50 women with lumbopelvic pain of various etiologies and various degrees of severity. Sensitivity was assessed in 200 patients with PPPP and specificity in 50 healthy women. Sensitivity and specificity of the ASLR test were compared with the posterior pelvic pain provocation test (PPPP test). RESULTS: The test-retest reliability measured with Pearson's correlation coefficient between the two ASLR scores 1 week apart was 0.87. The intraclass correlation coefficient (ICC) was 0.83. Pearson's correlation coefficient between the scores of the patient and the scores of a blinded assessor was 0.78; the ICC was 0.77. In the patient group, the ASLR score ranged from 0-10; in the control group it ranged from 0-2. The best balance between specificity and sensitivity was found when scores 1-10 are designated as positive and zero as negative. With this cut-off point sensitivity of the test was 0.87 and specificity was 0.94. The sensitivity of the ASLR test is higher than the sensitivity of the PPPP test; an advantage of the ASLR test is the simplicity of measuring the score. CONCLUSION: The ASLR test is a suitable diagnostic instrument to discriminate between patients who are disabled by PPPP and healthy subjects. The test is easy to perform; reliability, sensitivity, and specificity are high. It seems that the integrity of the function to transfer loads between the lumbosacral spine and legs is tested by the ASLR test.

Adult↗

PubMed2001

Starting from standing; why step backwards?

At push-off, the mass centre of gravity of the body must be positioned in front of the foot to prevent a somersault. When starting a sprint from out the standing position the use of a step backwards is necessary for maximal acceleration. The aim of the present study was to quantify the positive contribution to push off from a backward step of the leg, which seems to be counterproductive. Ten subjects were instructed to sprint start in three different ways: (a) starting from the standing position just in front of the force platform on the subject's own initiative, (b) starting from the standing position on the force platform with no step backward allowed, and (c) starting out of the starting position with one leg in front of the force platform and the push-off leg on the force platform. A step backwards was observed in 95% of the starts from the standing position. The push-off force was highest in starting type (a), which had the shortest time to build up the push-off force. The results indicate a positive contribution to the force and power from a step backwards. We advocate developing a training program with special attention to the phenomenon step backwards.

Adult↗

PubMed2001

The effect of passive vertebral rotation on pressure in the nucleus pulposus.

To study the immediate effects of axial rotation on the intervertebral disc, six pig cadaver lumbar functional spinal units were exposed to rotations of up to 2 degrees, while disc height and intradiscal pressure were measured. The results showed that rotary movements are capable of causing an immediate increase in disc height and drop in nucleus pressure. However, the long-term effects were opposite in direction.

Analysis of Variance↗

PubMed2001

New ergonomic design criteria for handles of laparoscopic dissection forceps.

BACKGROUND: The shape of laparoscopic instrument handles can cause physical discomfort. This problem may be ascribed to a lack of standards for instrument design. In this study, new ergonomic requirements for the design of laparoscopic dissection forceps were created. Three representative handles (a Karl Storz [click-line] scissors handle, an Access Plus scissors handle, and an Aesculap cylindrical handle) currently available on the market were evaluated according to the new list of ergonomic criteria. MATERIALS AND METHODS: The handles were subjectively (questionnaire) and objectively (video analyses) tested in order to find out whether the new requirements are valid for the evaluation and design of instrument handles. RESULTS: The outcome of the subjective and objective tests matched the predictions by the new criteria list. New criteria were introduced (neutral wrist excursions), and existing general criteria were specified (e.g., a minimal contact area of 10 mm). Significant differences were found among the three handles. The Storz handle met 8 of the 10 requirements, the Access handle met 5, and the Aesculap handle met only 4. CONCLUSIONS: The new list of ergonomic requirements is a valid tool to determine the ergonomic value of a handle for laparoscopic dissecting tasks. It gains its strength from its specialized character. Significant differences were found among the three tested handles. Cylindrical handles were inferior to scissors handles.

Dissection↗

PubMed2000

Biomechanical analysis of the dimensions of pilot seats in civil aircraft.

The dimensions of pilot seats from five different types of civil aircraft were measured and the results compared with existing standards and biomechanical criteria. It was apparent that these seats failed to meet requirements, particularly in the effective depth and inclination of the seat and in the height of the lumbar support and the armrests. Hence, none of these seats made it possible for the pilot to establish a comfortable sitting posture. In comparison with aviation standards, the anthropometric dimensions were not satisfactory, meeting only 4-7 out of 10 requirements. The dimensions based on biomechanics were even less satisfactory, meeting only between 1 and 3 requirements out of 7.

Aircraft↗

PubMed2000

Mechanical effects of continuous passive motion on the lumbar spine in seating.

The aim of this study was to develop a model which describes the mechanical spinal response to small alternating pelvic stimulation induced by an active rotational movement of a normal chair. The rotary continuous passive motion (RCPM) of the seat about a vertical axis of only 0.6 degrees resulted in an increased in spinal length as opposed to the normal daily shrinkage, and back patients experienced pain relief. Passive and active exercies have been broadly applied for treating and healing spinal disorders. A rigid body package (ADAMS Android) was used to translate the stimulation of the ischial tubersoity in caudo-cranial handing-over visualisation. The parameters of the model were set so that the values of the global stiffness and geometry of the intervertebral discs could be changed. In vivo validation of the model was based on force and moment measurements using an internal AO fixator. The predicitons of the model concerning natural frequency (4.5Hz) in vertical direction and the axial torsion response on small pelvic torsion are comparable with experimental data.

Algorithms↗

PubMed2000

Doppler imaging of vibrations as a tool for quantifying first tarsometatarsal joint stiffness.

OBJECTIVE: To assess whether first tarsometatarsal joint stiffness can be measured by Doppler imaging of vibrations and if so, to assess reference values. DESIGN: Repeated in vivo Doppler imaging of vibrations measurements at the first tarsometatarsal joint in healthy persons. BACKGROUND: Clinical hypermobility of the first tarsometatarsal joint is an important factor in a hallux valgus deformity. No objective and non-invasive test is available to quantify first tarsometatarsal joint mobility. Doppler imaging of vibrations, a technique recently developed to measure joint stiffness, might be an effective tool to quantify stiffness of this joint. METHODS: Vibrations were applied to the head of the first metatarsal in 46 feet of 23 healthy subjects and picked up by a transducer at both sides of the first tarsometatarsal joint. A pilot study was performed on three patients with hypermobility of the first tarsometatarsal joint. Measurements are expressed in threshold units related to colour Doppler imaging. RESULTS: The values of the threshold units were found to be very similar in healthy persons, with a good repeatibility; 95% of the healthy persons had a threshold unit below 3.4. No significant difference was found between the left and right foot, or between male and female subjects. Also there was no significant correlation with age or weight of the subjects. In the three patients with first tarsometatarsal hypermobility we found threshold units above 5. CONCLUSIONS: With Doppler imaging of vibrations first tarsometatarsal joint stiffness can be measured in healthy persons in a non-invasive and objective way. In a pilot study, three patients with first tarsometatarsal hypermobility showed lower stiffness values than the healthy subjects. Relevance This study presents a new method for quantification of first tarsometatarsal joint stiffness and provides reference values in healthy persons. First measurements on patients gave promising results to future use of this method for assessment of clinical hypermobility in hallux valgus patients.

Adolescent↗

PubMed2000

Upper limb tension tests as tools in the diagnosis of nerve and plexus lesions. Anatomical and biomechanical aspects.

OBJECTIVE: To analyse the validity of nerve tension tests used in the diagnosis of nerve (root) and plexus lesions of the upper extremity. DESIGN: In six arms of embalmed human bodies, in situ measurements were performed to assess the effect of nerve tension tests on the median, ulnar and radial nerves and the cords of the brachial plexus. BACKGROUND: In clinical practice it is useful to have fast, easy and cheap tests for the diagnosis of nerve (root) lesions of the upper extremity, analogous to Lasègue's Straight Leg Raising test.Methods. The Upper Limb Tension Tests for the median, ulnar and radial nerves, as well as the Upper Limb Tension Tests combined with contralateral rotation and lateral bend of the cervical spine (Upper Limb Tension Test+) were used to generate tension to these nerves. Buckle force transducers were used to assess tensile forces in the nerves and in the medial, lateral and posterior cords of the brachial plexus. RESULTS: Nerve tension introduced in the distal part of the median, ulnar and radial nerves was transmitted upward to the cords of the brachial plexus. Exclusively the median nerve Upper Limb Tension Test and Upper Limb Tension Test+ turned out to be sensitive and specific tension tests. Mechanical tension caused by the Upper Limb Tension Test+ was not significantly higher than that caused by the Upper Limb Tension Tests. The Upper Limb Tension Tests cannot be used to selectively stress cervical nerve roots. The findings justify investigation of exclusively the median nerve Upper Limb Tension Test and Upper Limb Tension Test+ on their clinical validity. RELEVANCE: Before nerve tension tests for the median, ulnar and radial nerves can be introduced to clinical practice it is necessary to assess their validity quantitatively.

Arm↗

PubMed2000

Passive stiffness characteristics of ankle plantar flexors in hemiplegia.

OBJECTIVE: To assess the feasibility and reliability of ankle plantar flexor stiffness measurements in hemiplegia. DESIGN: Repeated measurements in five consecutive weeks. BACKGROUND: In hemiplegia, an equinovarus positioning of the foot might be caused by an increased stiffness of the m. triceps surae. METHODS: In eight hemiplegic patients the net joint torque of passive muscle stretch was measured as a function of ankle-angle by a dynamometer, at both sides. Ankle-stiffness was characterised and also a biomechanical model of the passive muscle was fitted. RESULTS: In the vast majority of measurements it was possible to obtain measurements that were not distorted by involuntary muscle contraction. These measurements showed for the angle at which a passive plantar moment of 10 N m was reached a standard error of measurement of less than 2.7 degrees. The muscle model showed the increased stiffness as a shortening of the muscle-fibre-length. CONCLUSION: The feasibility of this method to measure muscle stiffness was fair to good in hemiplegic patients. Provided the abandoning of involuntary muscle activity, the reproducibility warrants application in clinical practice at an individual level. The use of the model relates this changes to a shortened m. soleus and/or m. gastrocnemius. RelevanceEffective clinical decisions for treatment of equinovarus positioning of the foot in the hemiplegic individual, should consider excessive involuntary contractions of the m. triceps surae complex (i.e., spasticity), as well as shortened muscle tissue resulting in high stiffness. Despite the importance of increased stiffness there have been no validated methods of measurement.

Adult↗

PubMed2000

Diagonal trunk muscle exercises in peripartum pelvic pain: a randomized clinical trial.

BACKGROUND AND PURPOSE: Exercises for low back and pelvic pain are supposed to increase muscle force to reduce symptoms, but they could exacerbate symptoms by loading of the spinal and pelvic structures. The purpose of this study was to investigate the value of graded exercises of the diagonal trunk muscle systems. SUBJECTS: The subjects were 44 women with persistent pelvic pain after pregnancy (mean age=31.7 years, SD=3.2, range=23.6-37.5; mean period postpartum=4.1 months, SD=2.2, range=1.7-5.6). METHODS: Subjects were randomly assigned to 1 of 3 groups: (1) a group that performed exercises to increase the force of the diagonal trunk muscle systems, (2) a group that received training of the longitudinal trunk muscle systems, and (3) a group that was instructed to refrain from exercises. Pain, fatigue, perceived general health, and mobility of the pelvic joints as measured with radiographs were the outcome measures. RESULTS: After 8 weeks, no differences were found among the 3 groups. CONCLUSION AND DISCUSSION: In treating patients with persistent pelvic pain, training of the diagonal trunk muscle systems, without individual coaching, has no additional value above instructions and use of a pelvic belt without exercises. Whether the treatment is ineffective or whether exacerbation of symptoms due to loading of the spinal and pelvic structures obscures any potential benefit of increased muscle force cannot be determined from the study design.

Abdominal Muscles↗

PubMed1999

The active straight leg raising test and mobility of the pelvic joints.

Objective signs to assess impairment in patients who are disabled by peripartum pelvic girdle pain hardly exist. The purpose of this study was to develop a clinical test to quantify and qualify disability in these patients. The study examined the relationship between impaired active straight leg raising (ASLR) and mobility of pelvic joints in patients with peripartum pelvic girdle pain, focusing on (1) the reduction of impairment of ASLR when the patient was wearing a pelvic belt, and (2) motions between the pubic bones measured by X-ray examination when the patient was standing on one leg, alternating left and right. Twenty-one non-pregnant patients with peripartum pelvic girdle pain in whom pain and impairment of ASLR were mainly located on one side were selected. ASLR was performed in the supine position, first without a pelvic belt and then with a belt. The influence of the belt on the ability to actively raise the leg was assessed by the patient. Mobility of the pelvic joints was radiographically visualized by means of the Chamberlain method. Assessment was blinded. Ability to perform ASLR was improved by a pelvic belt in 20 of the 21 patients (binomial two-tailed P = 0.0000). When the patient was standing on one leg, alternating the symptomatic side and the reference side, a significant difference between the two sides was observed with respect to the size of the radiographically visualized steps between the pubic bones (binomial two-tailed P = 0.01). The step at the symptomatic side was on average larger when the leg at that side was hanging down than when the patient was standing on the leg at that side. Impairment of ASLR correlates strongly with mobility of the pelvic joints in patients with peripartum pelvic girdle pain. The ASLR test could be a suitable instrument to quantify and qualify disability in diseases related to mobility of the pelvic joints. Further studies are needed to assess the relationship with clinical parameters, sensitivity, specificity and responsiveness in various categories of patients. In contrast with the opinion of Chamberlain, that a radiographically visualized step between the pubic bones is caused by cranial shift of the pubic bone at the side of the standing leg, it is concluded that the step is caused by caudal shift of the pubic bone at the side of the leg hanging down. The caudal shift is caused by an anterior rotation of the hip bone about a horizontal axis near the sacroiliac joint.

Adult↗

PubMed1999

A biomechanical model on muscle forces in the transfer of spinal load to the pelvis and legs.

Based on musculoskeletal anatomy of the lower back, abdominal wall, pelvis and upper legs, a biomechanical model has been developed on forces in the load transfer through the pelvis. The aim of this model is to obtain a tool for analyzing the relations between forces in muscles, ligaments and joints in the transfer of gravitational and external load from the upper body via the sacroiliac joints to the legs in normal situations and pathology. The study of the relation between muscle coordination patterns and forces in pelvic structures, in particular the sacroiliac joints, is relevant for a better understanding of the aetiology of low back pain and pelvic pain. The model comprises 94 muscle parts, 6 ligaments and 6 joints. It enables the calculation of forces in pelvic structures in various postures. The calculations are based on a linear/non-linear optimization scheme. To gain a better understanding of the function of individual muscles and ligaments, deviant properties of these structures can be preset. The model is validated by comparing calculations with EMG data from the literature. For agonistic muscles, good agreement is found between model calculations and EMG data. Antagonistic muscle activity is underestimated by the model. Imposed activity of modelled antagonistic muscles has a minor effect on the mutual proportions of agonistic muscle activities. Simulation of asymmetric muscle weakness shows higher activity of especially abdominal muscles.

Abdominal Muscles↗

PubMed1999

Measurement of sacroiliac joint stiffness in peripartum pelvic pain patients with Doppler imaging of vibrations (DIV).

OBJECTIVES: The research question of the present study was: are sacroiliac joint stiffness levels of peripartum pelvic pain patients different from those of healthy subjects? STUDY DESIGN: A cross-sectional comparative sacroiliac joint stiffness analysis of peripartum pelvic pain patients with healthy subjects. In previous studies we introduced a new technique, Doppler imaging of vibrations (DIV), to assess sacroiliac joint stiffness using colour Doppler imaging and vibrations. The measurements were performed on a group of peripartum pelvic pain patients (n=56) and on a control group (n=52). The differences in sacroiliac joint stiffness between the patient group and the control group were tested statistically by means of the Wilcoxon's two sample test, the chi-square test and Student's t-tests. RESULTS: Both patients and controls displayed stiff as well as unstiff joints with no significant difference. There was a significant difference between the groups with regard to the relative difference of sacroiliac joint stiffness between left and right. CONCLUSIONS: A diagnostic tool which can possibly be developed in the future could demonstrate an objective finding among women with peripartum pelvic pain. DIV is easy to apply and non-invasive. Asymmetric stiffness of the sacroiliac joints seems to be more directly related to low back pain and pelvic pain, not the stiffness level of a single sacroiliac joint.

Adult↗

PubMed1999

Mobility of the first tarsometatarsal joint in relation to hallux valgus deformity: anatomical and biomechanical aspects.

Hypermobility of the first tarsometatarsal (TMT 1) joint is suggested to be an important factor in the cause and progression of hallux valgus deformity. Hypermobility of the TMT 1 joint is tested clinically in the sagittal plane, but an important deformation also exists in the transversal plane: metatarsus primus varus. This in vitro study was undertaken to investigate the relation between the mobility of the TMT 1 joint in these two planes and to investigate the correlation of the mobility with morphological variables. A second aim was to study the possible stabilizing effect of the tibialis anterior muscle, flexor hallucis longus muscle, and peroneus longus muscle on the TMT 1 joint. Nine embalmed human specimens were tested under standardized conditions. A 30-N force was applied to the head of the first metatarsal (MT 1) to pull in either the dorsal or medial direction. To simulate muscle force, 21 N was applied to the three tendons: all seven possible combinations of muscle action were tested in each plane of motion. Angular displacements were measured using 2-dimensional LED video registration. TMT 1 mobility is a relevant factor in MT 1 mobility in the sagittal and transversal planes, the peroneus longus has a stabilizing effect on this joint, and the effect of the flexor hallucis longus on this joint is different in both planes. When considering a Lapidus procedure for surgically correcting a hallux valgus, the mobility of MT 1 in the transversal plane should also be assessed, but so far no objective clinical test in this plane has been described.

Aged↗

PubMed1999

Tennis elbow, natural course and relationship with physical activities: an inquiry among physicians.

BACKGROUND: The main purposes of the study were to answer the following two questions: is a restrictive therapeutic management in case of tennis elbow (TE) better or worse than a regular therapeutic approach and do racket sports and other physical activities influence the risk to get TE and to what extent. METHODS DESIGN: Cross-sectional study by means of a postal questionnaire. The impression was verified that physicians are reserved about medical interventions when treating themselves for tennis elbow. The frequency of therapeutic measures and their results were compared with data reported in literature. Physical activities of physicians who had TE were compared with those of physicians who never had TE. SETTING: Physicians who attended postgraduate courses on diagnosis and treatment in orthopedic medicine from 1984 to 1992. PARTICIPANT: 72 physicians who had TE and 266 with no history of TE. MEASURE: The study is based on self-assessment of therapeutic approaches and their results, reported physical activities at the onset of TE and at the moment of the inquiry. By a team of experts the grade of grasping and/or dorsiflexion of the physical activities was classified. RESULTS: Compared with patients in general practice, physicians treating themselves for TE were more restrictive to use NSAID's, ointments or local steroid injections or to consult a specialist. No-one was treated with surgery and no-one interrupted her/his work because of TE. In all but two of the 72 cases the TE resolved within two years. The odds ratio for TE for playing racket sports versus not playing racket sports was 2.8 (95% confidence interval 1.64-4.82). The odds ratio for activities with low-grade grasping and/or dorsiflexion versus "no sports or hobbies" was 0.11 (0.02-0.50). CONCLUSIONS: Absence from work and therapeutic measures for TE are (in physicians) not necessary for a good result on the long term. Playing racket sports increases the risk to get TE by a factor of 2.8. Performing weekly activities with low grade grasping and/or dorsiflexion of the wrist may have a protective effect against developing tennis elbow.

Adult↗

PubMed1998

An evaluation of a modified Macintosh laryngoscope in a manikin.

PURPOSE: In this manikin study a modified Macintosh blade was prospectively compared with its original focussing on the forces exerted on the maxillary incisor teeth and intubation success. The modified blade, a standard Macintosh blade with a reduced proximal flange, was intended to reduce the forces exerted on the maxillary incisors. METHODS: A manikin equipped with two sensors, to measure forces applied to the maxillary incisors in the axial and the transverse direction, was used. Fourteen staff anaesthetists and 16 residents each performed two laryngoscopies with both blades. RESULTS: All laryngoscopies resulted in successful tracheal intubation. The maximal and mean forces exerted on the teeth in the axial direction were 12 N and 5.8 N smaller (P < 0.0005 and P < 0.0005, respectively) when the modified blade was used. CONCLUSION: The use of the modified blade resulted in a reduction of the forces on the maxillary incisors whereas the intubation success rate was the same as with the original. Studies in manikins can be useful in comparative laryngoscope testing.

Humans↗

PubMed1998

Recognition of daily life motor activity classes using an artificial neural network.

OBJECTIVE: To investigate a possible role of artificial neural networks for the automated recognition and classification of daily life activities (eg, sitting, lying, standing, walking, etc) in an attempt to reduce the cost of manual recognition and classification. METHODS: Data from sessions of about 10 hours of continuous recording of eight ambulatory patients were used to train and evaluate eight probabilistic neural networks, each of which is configured for one subject. To provide the reference data for building the training set, the instrumented subject follows a 15- to 30-minute protocol consisting of several daily life activities. To properly evaluate the networks, the remaining manually labeled data of each subject were compared with the output of each trained network. RESULTS: The average recognition rate of the trained neural networks was equal to 95% good classification of all presented cases of the daily life activity. Automatic misclassification of 5% resulted from certain activities being too short or the occurrence of activities that were not included in the training set. CONCLUSION: The preliminary results of the trained neural networks have indicated that the probabilistic neural network is a potentially useful tool for the recognition of daily life motor activities.

Activities of Daily Living↗

PubMed1998

Tendon excursion measurements with colour Doppler imaging.

We assessed the applicability of tendon excursion measurement by means of Colour Doppler Imaging (CDI) on human specimens, and also assessed the correlation between values measured by Doppler and by displacement meters. Muscles were separately connected to a mass of 1 kg with a steel wire running over a pulley. This weight moved the telescopic end of a digital displacement meter up and down during passive extension and flexion of the fingers. Excursion was measured with a pulsed multi-channel CDI scanner on the same arm. Assessment of finger tendon excursion with CDI correlated well with the mechanical micro displacement meter, the latter being considered the most accurate method in cadaver studies.

Aged↗