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Biomedical subjects

I Jonkers

Publications and source records attributed to I Jonkers.

6 recordsLinked to original sources
PubMed2004

Performance specification for lower limb orthotic devices.

OBJECTIVE: To establish the range of forces and moments applied to lower limb orthoses during ambulation by routine users. DESIGN: Well-established gait analysis techniques were used to determine the loading at the major joints. It was assumed that the joint moments were transmitted by the orthosis encompassing any particular joint. Two hundred and five assessments of 164 patients were successfully completed by a consortium of four gait laboratories in Europe. The orthosis specification and patient clinical data were also recorded. BACKGROUND: The design and development of orthoses has occurred largely by evolution rather than by formal engineering methods. In particular, formal design has been hampered by a lack of information on the forces and moments applied during ambulation. METHODS: A standard gait analysis procedure was employed to capture the data. In-house biomechanical models were used to calculate the joint loading. Data were normalised with respect to patient weight and leg length. RESULTS: It was found that the median maximum normalised ankle moment transmitted by an ankle foot orthosis was 0.15 and the maximum knee moment was 0.09. The greatest moment transmitted by the hip joint of a hip knee ankle foot orthosis was also 0.09. There was a wide variation in the data due to differences in the impairments of the test subjects. CONCLUSION: It is possible to estimate the loads transmitted by an orthosis using established gait analysis procedures without the need for load measurement transducers. There is now a need both to collect a larger representative dataset and to perform validation studies with transducers.

Adolescent↗
PubMed2004

Muscular effort in multiple sclerosis patients during powered wheelchair manoeuvres.

BACKGROUND: This study applied EMG analysis methods to identify muscle group activity profiles and potential overload risks in powered wheelchair use. METHODS: We quantified muscle effort and fatigue using EMG analysis methods during powered wheelchair manoeuvres by 10 multiple sclerosis patients. Video recordings of the different sub-tasks were related to information on surface EMG amplitude (rectified EMG) and spectral information (Median frequency) from M. trapezius, M. deltoideus (pars medius), M. deltoideus (pars anterior), M. pectoralis, M. biceps, M. triceps, wrist extensors and flexors, using Joint Analysis of EMG Spectrum and Amplitude (JASA analysis). FINDINGS: Task durations and subjective data indicated that tasks requiring finer motor control took longer and were perceived as more difficult. Kinesiological functions of all muscle groups identified forward steering to be associated with activation of M. deltoideus (pars anterior), M. pectoralis, M. trapezius and M. deltoideus (pars medius); backwards steering with predominant activation of M. deltoideus (pars medius), M. biceps brachii and wrist flexors; left steering with maximal activation of M. biceps and wrist flexors, and right steering with maximal activation of M. triceps and wrist extensors. These profiles were confirmed in analysis of the functional tasks. JASA analysis documented muscle fatigue in the wrist extensors, whereas increased activation was found in M. trapezius, M. deltoideus (pars anterior) and wrist flexors. INTERPRETATION: EMG based kinesiological analysis gives insight in muscle activity and fatigue during powered wheelchair manoeuvres.

Adult↗
PubMed2001

A randomized study of combined botulinum toxin type A and casting in the ambulant child with cerebral palsy using objective outcome measures.

It is recognized that objective gait analysis is of great value in planning a multilevel botulinum toxin type A (BTX-A) treatment. After BTX-A treatment, objective outcome measures can provide new and interesting information for each individual child with cerebral palsy (CP). Moreover, by studying group results, we may evaluate our treatment hypotheses. The present prospective study attempts to document the effect of integrated multilevel BTX-A treatment on objective gait parameters and to define the optimal strategy for the combined treatment of BTX-A with casting in children with cerebral palsy. Objective three-dimensional gait analysis (3DGA) data were collected pre- and 2 months post-treatment, in two randomized patient groups: a first group of 17 children treated with lower leg casting prior to BTX-A injections, and a second group of 17 patients who received casting immediately after injections. The present study demonstrates that improved gait can be achieved after a multilevel BTX-A treatment, combined with casting, using a set of 90 gait parameters. The most pronounced improvement was seen at the ankle joint. The results in the knee, hip and pelvis imply that multilevel treatment of the child with CP should start at an early age, in order to prevent development of muscle contractures. Slightly more pronounced benefits, mainly in the proximal joints, were seen for the children who were casted after injections as compared to the children who were casted before injections.

Biomechanical Phenomena↗
PubMed2001

Single event multilevel botulinum toxin type A treatment and surgery: similarities and differences.

The present study attempts to provide objective evidence of two treatment options for children with cerebral palsy (CP): multilevel botulinum toxin type A (BTX-A) injections and multilevel surgery. The purpose of the study was to clarify the differences and the similarities, and common treatment principles of both treatment strategies. Objective three dimensional gait analysis data were studied retrospectively in two patient groups pre- and post-treatment (randomly selected from a group of children that were treated between 1998 and 1999). In the first group, 29 children with CP were managed with BTX-A injections according to an integrated multilevel approach (Molenaers et al., 1999a). A second group of 23 children with CP were managed by a more traditional single event multilevel surgery, also according to an integrated approach. Our aim was to evaluate the differences as well as the similarities between both patient groups, using a set of 56 parameters selected from three-dimensional gait analysis. The unifying concept between management with BTX-A injections and orthopaedic surgery was the adoption of a multilevel approach at one session. The groups demonstrated considerable differences with respect to age, pretreatment condition and amount and level of improvement after treatment. The children who received BTX-A were typically younger, and showed primary gait problems in the distal joints, whereas the children who underwent surgery demonstrated a higher frequency of gait deviations in the transverse plane and had more complications. Although the benefit of both treatments was confirmed by the present study, a difference in the amount and level of improvement was also demonstrated. In conclusion, these treatment modalities should be regarded as complementary rather than mutually exclusive treatments, with both calling for an integrated approach.

Adult↗
PubMed1996

Acute effects of intravenous injection of beta-adrenoreceptor- and calcium channel at antagonists and agonists in myasthenia gravis.

The effect of intravenous injection of propranolol, verapamil, terbutaline, calcium, and edrophonium on neuromuscular transmission has been studied with repetitive nerve stimulation and clinical tests in 10 patients with myasthenia gravis (MG). The drugs were given intravenously in doses commonly used in clinical practice. Only minor clinical effects were noted except for edrophonium. The mean decrement of the deltoid muscle was not significantly changed after injection of propranolol (before 31%, 15 min after injection 27%) and verapamil (before 29%, 15 min after injection 26%). Terbutaline applied after propranolol and calcium applied after verapamil improved the decrement substantially. Edrophonium applied after propranolol or verapamil also greatly improved the decrement. We conclude that there is no rapid deterioration of neuromuscular transmission in patients with moderately severe MG after injections with therapeutic doses of propranolol and verapamil. However, we do not know if the most severely disabled MG patient could have reacted otherwise. We consider that, in cardiovascular emergencies, propranolol and verapamil may be used even in severe MG but with resuscitation equipment as well as specific antidotes available.

Adult↗