A radiological measure of shoulder subluxation in hemiplegia: its reliability and validity.

This study describes the reliability and validity of a new radiological method to measure shoulder subluxation that is based on taking a single x-ray of the affected shoulder in the plane of the scapula. A digitizer and a computer are used to quantify the measurements directly from the x-ray. One single radiological view of the shoulder taken in a standardized position provides four measures of subluxation including a measure of vertical subluxation, horizontal subluxation, a normalized distance sensitive to both vertical and horizontal subluxation, and an angular measure. A total of 72 volunteers with cerebrovascular accidents participated in the study. Thirty-six subjects had a clinical shoulder subluxation and 36 had no clinical subluxation. The construct validity analysis showed significant differences (p < .001) between the mean scores for subluxed and nonsubluxed groups on all four measures of subluxation. The concurrent validity of the x-ray measures in relation to external clinical measures (finger's breadth, measures in centimeters with calipers or a plexiglass jig) was moderate. Three measures were found to be reliable and valid whereas the fourth, a measure of horizontal subluxation has lower reliability. However, it does have clinical significance. The clinical and research implications of this study are presented.

Biomechanical analysis of wheelchair propulsion for various seating positions.

The pattern of propulsion was investigated for five male paraplegics in six seating positions. The positions consisted of a combination of three horizontal rear-wheel positions at two seating heights on a single-purpose-built racing wheelchair. To simulate wheelchair propulsion in the laboratory, the wheelchair was mounted on high rotational inertia rollers. For three trials at each seating position, the subjects propelled the designed wheelchair at 60 percent of their maximal speed, which was determined at the beginning of the test session. At each trial, the propulsion technique of the subject was filmed at 50 Hz with a high-speed camera for one cycle, and the raw electromyographic (EMG) signal of the biceps, brachii, triceps brachii, pectoralis major, deltoid anterior, and deltoid posterior muscles were simultaneously recorded for three consecutive cycles. The digitized film data were used to compute the angular kinematics of the upper body, while the EMG signals were processed to yield the linear envelope (LE EMG) and the integrated EMG (IEMG) of each muscle. The kinematic analysis revealed that the joint motions of the upper limbs were smoother for the Low positions-since they reached extension in a sequence (wrist, shoulder, and elbow), when compared to the High positions. Also, the elbow angular velocity slopes were found to be less abrupt for the Backward-Low position. It was observed that in lowering the seat position, less IEMG was recorded and the degrees of contact were lengthened. Among the seat positions evaluated, the Backward-Low position had the lowest overall IEMG and the Middle-Low position had the lowest pushing frequency. It was found that a change in seat position caused more variation in the IEMG for the triceps brachii, pectoralis major, and deltoid posterior. The trunk angular momentum was not found to be affected by a change in seat position which may be related to the variability among the subject's technique of propulsion or to a posture compensation.

Electromyographic versus rhythmic positional biofeedback in computerized gait retraining with stroke patients.

This research provides a preliminary investigation of the relative efficacy of electromyographic (EMG) versus a novel biofeedback (BFB) approach to improve ankle control and functional gait in stroke patients. A computerized system was designed to provide audiovisual feedback of either muscle activity or ankle position during dorsiflexion and plantar flexion. The novel approach also included rhythmic pacing to emphasize the rapid timing of ankle motion necessary to switch from stance to swing during walking. Thirty-seven subjects were randomly assigned to one of the following groups: (1) no-treatment control, (2) EMG BFB, and (3) rhythmic positional BFB. Blind evaluations of ankle performance, gait, and perceived exertion were performed at regular intervals. Analyses of covariance revealed that subjects receiving rhythmic positional BFB significantly increased their walking speeds relative to other groups at posttest (p = .02) and at three-month follow-up (p = .035), without any increase in subjectively reported energy cost. The ability of positional BFB to emphasize the timing events during walking provided optimistic results for carry-over into gait functioning. The degree of sensorimotor recovery and time since onset of stroke were considered important factors in determining outcomes.

Foot shields for wheelchairs.

The dangers experienced by wheelchair users, particularly those who are quadriplegic, are discussed and a practical solution is described: construction of a foot shield which can be fitted to most wheelchairs, manual or electric. The shield is simple to construct and protects the feet of the user in a collision with a second wheelchair or other external object.

Regenerative processes in peripheral nerve injury: a new method for their evaluation.

The objective of this study was to evaluate a new quantitative electrophysiologic method and instrumentation for assessing the regenerative process in peripheral nerve injuries. The method was based on spectrum analysis of myoelectric signals. Myoelectric data were obtained longitudinally from affected muscles of the upper limb in patients with traumatic brachial plexus injuries, and quantitatively subjected to on-line analysis. Bipolar surface recordings were made during voluntarily mediated motor unit activity at both a low level of activity (nonfatiguing state) and a maximal level (fatiguing state). The results over time for the low-level activity have shown a significant increase in mean frequency of the myoelectric signal in some muscles, a significant decrease in other muscles, and no change in still other muscles. A significant increase in amplitude was observed in every instance. During the maximal level of activity there was a reduction in mean frequency and the amount of reduction was shown to increase over time. The results are useful in indicating the occurrence of peripheral sprouting, axonal regrowth, of central reorganization, and in indicating improved metabolic activity in a muscle. It is concluded that the method is reliable in the study of the regenerative process.

The electromyographic response to sudden stretches of limb muscles in normal human subjects.

The electromyographic (EMG) activity following a sudden stretch applied to wrist flexor or extensor muscles was investigated using a method which enabled the individual records and cumulative results of 30 trials to be observed simultaneously. The results showed that in each case the spinal reflex EMG burst was followed by one or two additional reflex bursts. The second of these latter bursts, when present, occurred in one of two distinct latency ranges. Thus, three distinct latency ranges were observed for reflex bursts following the spinal reflex burst. A possible explanation for these results is that there are three distinct long-loop reflexes, one or two of which may be active following a muscle stretch. The present results do not distinguish whether any or all of these long-loop reflexes are segmental or supraspinal in origin.

The influence of a visual cue on muscle stretch reflexes.

Evidence has recently been presented indicating that muscle stretch reflexes have a large supraspinal component. The finding introduces the possibility that stretch reflex parameters may be modifiable by stimuli involving other modalities besides stretch. In this investigation, the effects of a visual cue on the reflex portions of the EMG activity following a sudden muscle stretch were examined. The results, obtained from the flexor carpi radialis muscles of six normal awake subjects, failed to show any significant change in the EMG parameters as a result of visual cues occurring at the instant of onset of muscle stretch. This was interpreted as indicating that visual inputs do not reach the areas of brain involved in the supraspinal reflex in sufficient time to modify the reflex.