PubMed Health⌕ Search

Biomedical subjects

J Krajnik

Publications and source records attributed to J Krajnik.

At least 19 recordsLinked to original sources
PubMed2001

Knee muscle activity during ambulation of trans-tibial amputees.

Gait analysis of trans-tibial amputees brings to light asymmetries of different gait parameters between the amputated and sound legs. The present study investigated the activity of the vastus medialis and biceps femoris muscles during ambulation of trans-tibial amputees. Peak activities of the vastus medialis were reached similarly in both legs (6.06+/-4.9% and 8.84+/-3.6% of gait cycle, in the sound and amputated leg, respectively). Biceps femoris peak activities were reached at 92.43+/-6.6% of gait cycle in the sound leg, and significantly later (at 9.81+/-4.8% of gait cycle) in the amputated leg (p < 0.05). Integrated EMG activity ratios, between swing and stance periods, were similar for the vastus medialis (0.33 in the sound and 0.35 in the amputated leg). However, these ratios differed significantly for the biceps femoris since the amputated leg presented a substantial (p < 0.05) smaller ratio (0.22) compared with the sound leg (0.83). The use of prosthesis in trans-tibial amputees requires further activity of the biceps femoris during stance period to improve support of the amputated leg knee joint.

Adult↗
PubMed1997

Double-limb support and step-length asymmetry in below-knee amputees.

The sequence of gait events and symmetry of kinematic parameters between both lower limbs are compromised in below-knee amputees. In the present study the periods of double-limb support and the step length in below-knee amputees were investigated. The symmetry of the two periods of double-limb support occurring in each stride was obviously abnormal (ratio: 0.74) among temporal and distance parameters. The time of double-limb support (0.211 +/- 0.05 seconds) measured from heel-strike of the amputated leg until toe-off of the normal leg was significantly longer (p = 0.011) when compared with the contralateral leg (0.173 +/- 0.04 seconds). The step length of the normal leg (0.709 +/- 0.07 m) was significantly (p = 0.045) shorter than that of the amputated leg (0.752 +/- 0.08 m). Most of these differences between measured kinematic parameters can be explained by the limited ability of the prosthesis ankle-foot component to reproduce the normal functions of both foot and ankle.

Adult↗
PubMed1996

Ankle muscle activity before and after botulinum toxin therapy for lower limb extensor spasticity in chronic hemiparetic patients.

BACKGROUND AND PURPOSE: Recent studies have been made of the novel treatment of lower limb spasticity after stroke with botulinum toxin A, and the results were based mostly on the clinical assessment made before and after treatment. This study investigated the effects of toxin on ankle muscle activity during gait in patients with severe extensor spasticity. The questions posed were whether the toxin particularly diminishes the so-called premature muscle activity as a major cause of equinovarus deformity and whether different types of altered motor control allow a prediction of the outcome of the treatment. METHODS: In 12 chronic hemiparetic outpatients with pronounced lower limb spasticity, we injected 400 U botulinum toxin A into the soleus and tibialis posterior muscles and both heads of the gastrocnemius muscles. Ankle spasticity and complex gait analysis including kinematic electromyography (EMG) of the soleus and tibialis muscles were assessed before treatment and 4 weeks after the injection. RESULTS: Nine patients profited with a reduction of spasticity, improved gait ability, and a more normal temporal pattern of muscle activity with a prominent reduction of the premature activity of the plantar flexors. Eight patients exhibited a qualitative pattern (type I) corresponding to an increased stretch-reflex excitability. Three patients did not profit; their muscle tone, gait ability, and muscle activation remained stable or even deteriorated. CONCLUSIONS: This study further supports the beneficial effects of botulinum toxin in the treatment of lower limb extensor spasticity. A correlation was observed between the clinical reduction of muscle tone, functional gait parameters, and a more normal EMG pattern with a predominant reduction of the premature activity of the plantar flexors. The qualitative type of EMG pattern corresponding to an increased stretch-reflex excitability (type I) was a positive predictor for the outcome.

Adult↗
PubMed1996

Influence of speed on gait parameters and on symmetry in trans-tibial amputees.

Normal gait is characterised by a high level of inter-leg symmetry of gait parameters. Therefore, efforts in rehabilitation of amputees are directed at the construction of a prosthesis which provides normal leg function and allows a more symmetrical gait. Analysis of the gait of trans-tibial amputees was performed when they were ambulating at their own freely selected speed and at a faster speed. The effect of speed on selected gait parameters in each leg was evaluated and the influence on symmetry established by comparing the inter-leg changes for each of the selected parameters. The faster gait trail affected significantly all temporal and distance parameters in both legs but not the level of symmetry between legs. At the faster speed, the hip angles at heel-strike and during swing and the knee angle during load response, in the normal leg, and the knee angle during swing in the amputated leg, all increased significantly. Speed of gait significantly affected symmetry between knee angles as reflected by the increased differences measured during load response (from 2.62 +/- 5.2 to 7.06 +/- 4.2 degrees) and during toe-off (from 1.80 +/- 7.4 to 9.50 +/- 9.1 degrees). Timing and sequence of selected gait events, as related to stride time, were not significantly affected by speed of gait. These results might contribute to a better understanding of gait characteristics in trans-tibial amputees and provide design guidance for prosthetic components.

Adult↗
PubMed1988

A quantitative method of evaluation of gait under the influence of electrical stimulation in hemiparetic patients.

To improve the procedure of selecting stimulation parameters for the best functional movement, quantitative gait evaluation was investigated. Based on the information obtained by force measuring shoes and a goniometric system, the method consists of computing average values and standard deviations of ground reaction and its point of action, goniometric functions, as well as the ankle joint torque in the sagittal and frontal plane, and their graphic representation. Deviation of the measured variables with respect to the normal gait pattern is the measure of the gait quality. Stimulation parameters were adjusted so that the patient's gait pattern approached normal.

Electric Stimulation↗
PubMed1987

The use of ground reaction measuring shoes in gait evaluation.

Ground reaction force is one of the most relevant parameters in the assessment of human gait. It is, however, difficult to measure without encumbering natural locomotion. A description of a system for measuring the vertical component of the ground reaction force and its distribution under the foot is given. The calibration procedure for the measuring shoes is described. The results of measurements are compared with those obtained from a force plate. Illustrative examples of the changes in pathological gait patterns of a hemiplegic patient during therapy by functional electrical stimulation are also given.

Biomechanical Phenomena↗
PubMed1987

Therapeutic effects of multisite electric stimulation of gait in motor-disabled patients.

Therapeutic effects in ten hemiplegic patients and one paraparetic patient treated by multisite electric stimulation of gait were compared with effects in ten hemiplegic patients treated by standard rehabilitation methods after 2.6 months of extensive therapy. Average step length and gait velocity, ground reaction forces and their distribution under both feet, and crutch loading were measured; goniograms of joint angles, kinesiologic gait analysis, and EMG recordings from the main muscles used in ambulation and in standing, were made while patients in both groups walked without stimulation. Quantitative measurements before, during, at the end, and 8.4 months posttherapy were taken based on at least 40 strides per patient. The results for the stimulated group in midtherapy indicated faster recovery rates (3.15 times in step length and 2.25 times in gait velocity) than in the control group, and at the end of therapy the stimulated group had higher improvement levels (2.14 times in step length, 1.42 times in gait velocity, and 1.63 times in kinesiologic gait analysis). The differences between the two groups faded after 8.4 months without treatment, and some kinesiologic deficits reappeared, mostly those in the more distal muscle groups. These findings indicate a need for a simpler orthotic electric stimulation after multisite therapy in several cases. Immediate effects of the six-site stimulation were also considered for orthotic possibilities after the therapy.

Electric Stimulation Therapy↗
PubMed1983

Gait restoration in paraplegic patients: a feasibility demonstration using multichannel surface electrode FES.

Recent advances in science have aided research toward the restoration of biped gait in paraplegic patients by means of functional electrical stimulation (FES). In this paper it is shown how FES-restrengthened muscles of paraplegic patients have been used for simple FES-assisted standing. Those experiments subsequently led to biped gait-initializing experiments and to simple forms of biped gait synthesis. The purpose of this paper is to show the feasibility of using FES for standing and for restoring biped gait in many paraplegic patients--to present the past achievements, focus on problems, and highlight directions for future research. The results of gait obtained in three complete spinal cord injured patients (out of a series of 17) are shown, using four to six channels of FES. It is also shown how preserved reflex mechanisms of the transected spinal cord can be incorporated and employed for obtaining improved function while at the same time simplifying the FES hardware. Of the three patients reported on in detail here, two patients have managed to walk in parallel bars while the third patient has mastered independent unassisted walking over shorter distances with the aid of a roller walker. The biomechanical and control problems of this last patient's gait are presented in detail.

Adult↗
PubMed1978

[The treatment of mandibular fractures, complicated by inflammations in the fracture area, by means of xenogenic cartilage].

The authors used a personal technique for the management of infected jaw fractures. If the fracture cleft was not wider than 1 cm, they performed a surgical revision (having made an incision through the mucoperiosteum of the oral vestibule) and replaced the excochleated gra-ulation tissue (including sequestrums) by lyophilized cartilage. The bone fragments were immoblized by bone sutures previously applied and also by additional plastic splints. The substitution of the cartilage by bone begun 6-8 weeks after the surgical intervention (as evidenced by radiographs); the process had terminated in about 6-10 months, the implanted cartilage being completely replaced by newly formed bone. The observation involved 16 cases. The method is also recommended for treatment on an out-patient basis.

Adolescent↗