Pulmonary function testing in spinal cord injury: effects of abdominal muscle stimulation.

The purpose of this study was to assess the effects of applying transcutaneous electrical stimulation to paralyzed abdominal muscles during pulmonary function testing (PFT) of individuals with spinal cord injury (SCI). Ten male subjects with anatomical level of SCI between C5-T7 were studied. Subjects performed PFTs with and without electrical stimulation delivered to the abdominal muscles. Subjects with the lowest percentage of predicted expiratory volumes and flows demonstrated the greatest improvement when electrical stimulation was delivered during forced expiration. The overall increases seen in percent of predicted for the study sample were 23 percent for forced vital capacity (FVC), 16 percent for forced expiratory flow in 1 s (FEV1), and 22 percent for peak expiratory flow rate (PEF). Contractions of paralyzed expiratory muscles in response to electrical stimulation during the performance of PFT maneuvers can significantly improve FVC, FEV1, and PEF in some individuals with SCI.

Multichannel electrical stimulation of gait in motor disabled patients.

Effects of surface multichannel electrical stimulation of the leg muscles during gait were evaluated by a clinical kinesiological analysis of gait and measurements of average step length, gait velocity, ground reaction forces, and joint angles. Direct effects in 11 stimulated motor disabled patients showed 56% improvement at the kinesiological gait analysis during the stimulation. Long term effects of the multichannel therapy were compared in a threeyear control study with a group of ten nonstimulated patients. At the kinesiological analysis, the stimulated group improved 1.75 times better after 2.5 months of the treatment. The other measurements revealed higher and faster improvement at the stimulated group with a partial decrease of the therapeutic effects after a longer period without treatment. Orthotic multichannel stimulation was indicated after the multichannel therapy in the clinical environment, where the stimulation of proximal leg muscles was favored.

Enhancement of hemiplegic patient rehabilitation by means of functional electrical stimulation.

This presentation will review briefly the current practice and state of the art in functional electrical stimulation (FES) as applied to stroke, head injured or brain tumour operated patients. A similar application is used in paretic patients following trauma or other aetiology. Over 20 years experience in the application of FES, as practised in Ljubljana, will be highlighted and the devices currently in use will be described. The statistics show the results obtained on 2,500 hemiplegic patients examined for FES application during the last 10 years. The statistics and results of the Slovenian population indicate 0.15-0.20% new cases annually or 1,500 new cases per million inhabitants. Up to 63% of annual cases are candidates for an FES based therapeutic locomotion rehabilitation programme. Experience indicates that 60% of hemiplegic patients received single-channel stimulation to correct equinovarus or foot drop, 30% obtained dual or even three channel stimulation treatment and only 10% of patients were involved in multichannel FES of four to six or even eight channels of stimulation. The benefits and outcome of rehabilitation will be presented and discussed in regard to current trends in the field of FES for hemiplegic and paretic patients. The partly inactive but very important field of FES application to the upper extremity in hemiplegic and paretic patients will be discussed and the relatively modest achievements presented. Future developments will be presented together with advances foreseen by steadily improving technology.

The required resultant abductor force and the available resultant abductor force after operative changes in hip geometry.

The required abductor force (Freq) and the available abductor force (Fav) are calculated for different positions of the hip rotation center (RC) and different greater trochanter (GT) shifts in the frontal plane of the body in the one-legged stance. It is biomechanically favorable that Fav exceeds Freq and that the magnitude of the resultant hip joint force (R) after the operation is decreased. The difference between Fav and Freq, which represents the relative abductor strength, increases after medialization of RC and after lateralization of GT. On the contrary, after medialization of GT and after lateralization of RC, the difference decreases, which has unfavorable biomechanical effects. Distalization of GT is favorable because it increases the relative abductor strength.

[Anterior cruciate ligament function: a non-invasive quantitative technique]. / Laximétrie du ligament croisé antérieur: une technique quantitative non invasive.

PURPOSE OF THE STUDY: The purpose of the study was to develop a new non-invasive and quantitative method for evaluation of the anterior cruciate ligament function. PATIENTS AND METHODS: The new method was tested in 24 asymptomatic subjects and in 58 patients (39 males and 19 females) with arthroscopically proven unilateral rupture of the anterior cruciate ligament. Anterior displacement of the tibia with the knee in 20 degrees flexion was achieved by using a redesigned device, constructed originally for stress-radiography, and detected by a 3-D optical motion analysis system. RESULTS: In the normal group, the average difference (d) in anterior displacement of the tibia between the left and the right side under a displacement force of 250N was 0.56 mm (range 0.1 mm to 1.9 mm) or 17 p. 100 (range 2 p. 100 to 64 p. 100), while in patients the average difference (d) in anterior displacement of the tibia between the injured and uninjured side under a displacement force of 250N was 4.02 mm (range 0.6 mm to 9.4 mm) or 133.6 p; 100 (range 26 p. 100 to 451 p. 100). By the criteria for false negative results, i.e. the maximum value of the parameter d in normal subjects (1.9 mm and 64 p. 100), 10 p. 100 of the patients (6 patients) fell into the normal group. According to the criteria of false positive results, i.e. the minimum value of the parameter d in patients (0.6 mm and 26 p. 100), 17 p. 100 of the normal subjects (4 normal subjects) fell into the group of patients. The achieved level of differentiation is in the similar range as the most frequently used present methods. DISCUSSION: The main advantage of the newly developed noninvasive optical measurement technique is that the direction of force and the amplitude and site of application are accurately defined and documented, and that dislocation movement of the tibia towards the femur during the application of a growing force is continuously monitored with the 3-D optical system and that it allows for several consecutive assessments based on statistical data.

Resultant hip joint force after total hip replacement.

Bending moments acting on the LIMA-LTO femoral stem were calculated using a 3D mathematical model of the hip in the one-legged stance based on muscle anatomical data. The effects of 1 cm medialization and lateralization of the hip joint rotation centre (RC) on the bending moments were determined for different body weights. It was found that the bending moments and hence the stem loosening incidence are higher in lateralization compared to medialization of the RC. In order to diminish the bending moments, body weight should be reduced.

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.

Present state and prospects in the design of multichannel FES stimulators for gait correction in paretic patients.

Use of multichannel electrical stimulators (MES) for the rehabilitation of patients with plegic or paretic extremity muscles in one of the most promising trends in rehabilitation. Two clinically oriented therapeutic stimulators are described. The aim and the realization of walking rate dependent functioning, gradually modulated stimulation sequences, mini-computer and hardware closed-loop control of stimulation amplitude are described. The difficulties arising from the poor interface between the technical and biological part of the system prevent the described stimulators from being used as orthotic devices. Experiments with three types of electrodes are given, and the problem of an excessive mounting time for most clinical environments is also stressed.

Ventilatory assistance using electrical stimulation of abdominal muscles.

Nine neurologically intact subjects were studied to demonstrate the feasibility of stimulating the muscles of expiration during, and in synchrony with, naturally occurring breathing. A breath-by-breath analysis showed that both tidal volume and the frequency of respiration could be increased during periods of electrical stimulation. A single subject with complete spinal cord injury was studied to eliminate the possibility that the results from the normal subjects could be attributed entirely to either subconscious or conscious volitional response to the stimulation. The results provide a basis for future studies with patients in borderline ventilatory failure.

Functional electrical stimulation of abdominal muscles to augment tidal volume in spinal cord injury.

Functional electrical stimulation (FES) of abdominal muscles as a method of enhancing ventilation was explored in six neurologically intact subjects and five subjects with spinal cord injury (SCI) who had levels of injury between C4 and C7. Pulmonary ventilation was augmented in both groups predominantly due to an increase in tidal volume. The average increase in tidal volume during FES for the neurologically intact group was 350 ml, while in the SCI group it was 220 ml. The FES caused active volume decreases in both the lower thorax and upper abdomen, which together appear to be the mechanism behind the increases seen in tidal volume. Therefore, the proposed method might be useful in future clinical practice. The results indicate that FES of abdominal muscles should be more thoroughly explored as a potential technique of ventilatory support in SCI. The results also point to the necessity for further studies of maintaining the condition of the chest wall in the pulmonary rehabilitation of individuals with tetraplegia.

Treatment of drop foot using an implantable peroneal underknee stimulator.

An implantable peroneal stimulator has been developed to improve the rehabilitation of the drop foot patients who cannot use or refuse the use of conventionally applied peroneal braces. The small size promotes convenient attachment on the stimulation site after a minor surgical intervention. During the past two years twenty implants have been applied. The influence of different stimulation parameters upon the correction of anomalies during walking has been studied using clinical and computer-supported assessment. Possible noxious effects on the peroneal nerve have been studied by measuring nerve conduction velocity. The stimulator is well accepted by patients. Clinical observations show a significant correction of equinovarus and improved gait.

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.

Gait evaluation in hemiparetic patients using subcutaneous peroneal electrical stimulation.

In hemiparetic patients with an implantable peroneal stimulator for correction of drop foot the gait pattern was studied over several years. The gait parameters and M-waves of subcutaneously stimulated muscles were compared with the results obtained before implantation and their variation was observed over time. Of a group of 35 patients with previously implanted electrodes 19 were evaluated. Significant improvements of gait were found although in some cases an excessive eversion of the foot was observed. Nine of these patients had reimplantation because of displacement of the stimulation electrodes after an average time of 3.5 years of proper functioning of the implant. After the reimplantations, similar gait patterns and muscular responses to stimulation were observed as after the initial implantation.

Standardization of kinematic gait measurements and automatic pathological gait pattern diagnostics.

The estimation of patients gait in the field of rehabilitation is the starting point for an appropirate therapy decision and convenient prosthesis or orthosis choice. The measurement and estimation of human locomotion is increasingly being transferred to every day clinical use. In recent times many systems are intended for kinematic gait parameters measurements: stroboscopic photography, movie camera, TV picture analysis, TV signal analysis, chronocyclographical measurement, polarised light goniometer, the "Selspot" system, parallelgram goniometers, exoskeleton goniometers. In the paper the role of the computer in gait measurements is also determined. The problems of the choice of parameters to be measured, unique reference coordinate systems and normal gait pattern are encountered in this work. Finally two versions of pathological gait pattern estimation are described: clinical gait analysis and mathematical quantitative gait analysis. A combination of both methods provides an efficient, compact automatic pathological gait pattern diagnostics.

Recent applications of functional electrical stimulation to stroke patients in Ljubljana.

Functional movements can be restored after stroke by portable neuroelectric stimulator controlled by the patient. This field of activity is called functional electrical stimulation (FES). A common example of FES is electric stimulation of the peroneal to prevent dropfoot. A more sophisticated multichannel enables stimulation of more than one paralyzed muscle of the leg. This system is used temporarily to facilitate recovery of muscle function following stroke. Upper extremity FES systems have proven more difficult to develop than lower extremity systems designed to improve walking. A single-channel hand stimulator is available to assist finger movements.

Increased muscle stiffness after anterior cruciate ligament reconstruction--memory on injury?

Residual impairment of knee function was tested in 25 patients 6 to 12 months after successful unilateral reconstruction of the anterior cruciate ligament. The control group comprised 25 healthy individuals. Jumping onto one foot from a height of 20 cm was taken as a prototype of similar everyday activities. We measured maximum flexion of the knee during the landing phase of the jump, and the degree of knee flexion at the time of maximum deceleration of the knee against gravity during jumping using the three-dimensional optical motion analysis system-ELITE. In the group of patients, measured parametres were significantly smaller on the operated side than on the unaffected side. These two measured values were significantly smaller on both legs in group of patients as compared to the values in the control group. The results of our study indicate that functional disturbance persisted for 6 to 12 months after anterior cruciate reconstruction. This may be due to the changed muscle activation pattern of the knee causing increased stiffness of knee muscles. It seems that re-programming of the central nervous system occurred in order to protect the injured lower extremities from another injury.