Biomechanical study of gait using an intelligent brace.

We have developed a new long leg brace fitted with a computer-controlled knee joint that allows the user to go up and down a slope and stairs. Using this new brace, we analyzed gait under various conditions in ten normal men in terms of dynamic electromyography. Walking up a slope with normal step produced discharges in the leg muscles other than the gastrocnemius lateral head before and after the heel-strike on the ground, which indicated the absorption of the impact of landing. Going down a slope with controlled step resulted in lower activities of the tibialis anterior and the gastrocnemius lateral head than doing so with non-locked step or locked step. In subjects walking up stairs with tandem gait, the large discharges of the gastrocnemius lateral head that were observed in the late stance phase with normal step disappeared when the brace was applied. These results indicated that the muscle activity levels decreased during controlled walking with this new brace, and that the new brace can compensate for reduced muscle strength of the lower leg during walking. Kinematic analysis of walking revealed no significant difference between normal walking and controlled walking under any walking conditions.

Activity of rheumatoid arthritis and urinary pyridinoline and deoxypyridinoline.

The aims of this study were to examine levels of the crosslinking components of collagen, pyridinoline (Pyr) and deoxypyridinoline (D-Pyr) which are bone resorption markers, in patients with rheumatoid arthritis (RA), and to determine their association with disease activity and bone mineral density (BMD). These bone resorption markers were measured in 35 postmenopausal women with RA, 30 age-matched female patients with osteoarthritis of the knee (controls), and 47 patients with bone fracture. The mean BMD in the RA patients was lower than that in the control group, and the Z-score (number of standard deviations above and below the normal mean after comparison with age and sex matched normal control values) was significantly lower. Mean levels of Pyr and D-Pyr were significantly higher in the RA patients than in the control group, and the Pyr/D-Pyr ratio was also higher in the RA patients than in the other groups. Regarding the relationship between the bone resorption markers and RA activity, Pyr increased as the Lansbury's joint score (number of swollen joints corrected for joint size according Lansbury) rose, showing a normal correlation; D-Pyr also showed a normal correlation. Pyr and D-Pyr were high in patients with a high erythrocyte sedimentation rate, showing a normal correlation. Only Pyr increased with increases in C-reactive protein (CRP), showing a normal correlation. These findings suggested that a high value for Pyr (which includes a large amount of collagen type II) indicated that RA activity was affected more by synovitis, rather than by systemic osteoporosis.

Control engineering and electromyographic kinesiology analyses of normal human gait.

In this study, we analyzed the electrical activity patterns of the antagonistic bi-articular and mono-articular muscles of both legs during normal gait cycles, in terms of electromyographic (EMG) kinesiology and control engineering. For control engineering analyses, we utilized a mechanical two-joint link model equipped with antagonistic pairs of bi-articular and mono-articular muscles. It was confirmed that the coordinated activity pattern, in which the bi-articular muscles of the rectus femoris (Rf) and the medial hamstrings (Mh) showed criss-cross EMG patterns, and the mono-articular muscles of the gluteus maximus and the vastus medialis showed sustained activities during the early stance phase in the gait cycle, contributed to the output force control and the output force direction control. Reversal of Rf and Mh activities was responsible for changes in the output force direction during the heel contact period. The results obtained here strongly highlight the importance of and necessity for control engineering evaluation of coordinated muscle activities of bi-articular and mono-articular antagonistic muscles for analyses not only of gait but also of sports injuries.

Medical check of competitive canoeists.

We gave a sports injury questionnaire survey to 821 active canoeists, members of the Japan Canoe Association (JCA), and performed a medical check of 63 top competitive JCA canoeists, including physical and laboratory tests and radiographic examinations of the chest, spine, shoulder, elbow, and wrist joints. Completed questionnaires were returned by 417 canoeists, whose reported racing styles were: kayak, 324; Canadian canoe, 71; slalom, 13; and not specified, 9. Of the 417 respondents, 94 canoeists (22. 5%) reported that they experienced lumbago; 20.9% experienced shoulder pain; 3.8%, elbow pain; and 10.8%, wrist pain. On medical examinations, lumbago was found to be mainly of myofascial origin or due to spondylolysis. Impingement syndrome was also observed in 4 canoeists with shoulder problems. The competitive canoeists had low blood pressure, and some had bradycardia. On laboratory examinations, serum hemoglobulin, hematocrit, high-density lipoprotein cholesterol (HDL-CHO), creatine phosphokinase (CK), and creatine (CRTN) in the top competitive canoeists showed high values in comparison with those of an age-matched control group. However, low serum total cholesterol (TP) values were observed in the top competitive canoeists.

Asymptomatic brain abscess as a complication of halo orthosis: report of a case and review of the literature.

The halo external orthosis has been used extensively for cervical immobilization after spine surgery or trauma, usually without serious complications. However, nine brain abscesses have been reported as complications following the use of halo orthosis. We report on a 53-year-old man who underwent anterior cervical fusion for cervical myelopathy, followed by the application of a halo orthosis. Approximately 4 weeks postfusion, loosening of the right anterior pin was recognized and the pin was tightened, as the pin-site was clean. One week later, purulent material was discharged from the pin hole when the pin was removed after it had loosened again. Enhanced computed tomography (CT) demonstrated an abscess on the right side of the brain. After the administration of antibiotics, the abscess resolved without surgical intervention. We describe asymptomatic brain abscess complicating the use of a halo orthosis and review the clinical features, symptoms, and outcomes; we also discuss the mechanism that induced brain abscess. Most reported cases of abscess have been associated with pin-site infection or tightening after late pin loosening. The present case indicates the importance of early recognition of symptoms and signs associated with brain abscess in patients with a halo orthosis.

Newly designed computer controlled knee-ankle-foot orthosis (Intelligent Orthosis).

The authors have developed a knee-ankle-foot orthosis with a joint unit that controls knee movements using a microcomputer (Intelligent Orthosis). The Intelligent Orthosis was applied to normal subjects and patients, and gait analysis was performed. In the gait cycle, the ratio of the stance phase to the swing phase was less in gait with the knee locked using a knee-ankle-foot orthosis than in gait without an orthosis or gait with the knee controlled by a microcomputer. The ratio of the stance phase to the swing phase between controlled gait and normal gait was similar. For normal subjects the activity of the tibialis anterior was markedly increased from the heel-off phase to the swing phase in locked gait. The muscle activities of the lower limb were lower in controlled gait than in locked gait. The ground reaction force in locked gait showed spikes immediately after heel-contact in the vertical component, and unusual patterns were observed at heel-contact in the sagittal and lateral component. Therefore, compared to locked gait, gait with the Intelligent Orthosis is smooth and close to normal gait from the viewpoint of biomechanics. Even in patients with muscle weakness of the quadriceps, control of the knee joint using the Intelligent Orthosis resulted in a more smooth gait with low muscle discharge.

[MEPs by transcranical magnetic stimulation in experimental acute spinal cord injury].

The efficacy of motor evoked potentials (MEPs) induced by magnetic brain stimulation was investigated experimentally for assessing acute spinal cord injury. Twenty-five rabbits were employed for the acute spinal cord injury model. Following laminectomy under intravenous and intraperitoneal anesthesia, the spinal cord at the level of the fifth lumbar vertebra wsa injured by Allen's weight drop method. MEPs from the tibialis anterior muscle (M-MEP) were recorded using bipolar electrodes: prior to the injury; immediately after the injury; at 30 min, 1 hour, 3 hours, and at 5 hours after the injury. MEPs from the spinal cord (S-MEP) were recorded proximal to and distal from the injury site using epidural tube electrodes. Subjects were divided into two groups; complete and incomplete paralysis, according to the degree of motor dysfunction at 1 week after the injury. All the 13 subjects with incomplete paralysis had shown immediately after the trauma a prolongation in the M-MEP latency, with a polyphasic wave form seen in 5 of them. In 3 cases, the amplitude of the M-MEPs was decreased without any change in wave form. In others, there was some variation in the change of wave form, but there was no relationship found between the change of wave form and the degree of motor dysfunction in this group. Histopathologically, infiltration of the inflammatory cells and diffuse hemorrhaging were seen in the gray matter of the injured spinal cord in the incomplete paralysis group. In 7 of the 10 cases with complete paralysis, the M-MEP disappeared within 3 hours. Histopathologically, large areas of the nerve cells disappeared from the gray matter in this group. The S-MEP disappeared immediately after trauma in the group with complete paralysis as well as in those with incomplete paralysis. This study indicated that MEPs taken immediately after a trauma may predict the severity of a spinal cord injury and were useful for evaluating the prognosis of motor function during the acute phase of a spinal cord injury.

[Electrophysiological and MRI study on poor outcome after surgery for cervical myelopathy].

Occasionally, the outcome from laminoplasty for cervical spondylosis is disappointing despite an adequate operation. Before surgery, it is difficult to diagnose the pathological extent of the involvement of the spinal cord. The purpose of this study is to determine the efficacy of magnetic resonance imaging (MRI) and of the motor evoked potentials (MEPs) for the indication of the surgery and prognosis. Retrospectively, we investigated the MEPs and the MRI image of 31 patients in surgery for cervical myelopathy, involving 21 cases with cervical spondylosis and 10 cases with ossification of the posterior longitudinal ligamentum, and compared the findings from those with a poor outcome (n = 31) with the findings from those with a good outcome (n = 32). The MEPs from the thenar muscle and the tibialis anterior were evoked by transcranial magnetic brain stimulation. In the poor-outcome patients, the spinal canal was narrow and lumbar spinal canal stenosis was seen in 5 cases which required lumbar laminectomy. Before operation, the MEPs from the thenar muscle could not be evoked in 5 cases while there was a remarkably prolonged central motor conduction time in the other 26 cases. MRI revealed the deformed spinal cord in the involved area, and the signal intensity of the involved spinal cord in the T2 weighted image was remarkable high. The signal intensity ratio was significantly higher in the poor-outcome patients than in the good-outcome patients. This study suggested that a high signal intensity in the T2 weighted image and a prolonged conduction time or absence of MEPs largely corresponded to the clinical and other investigative features of myelopathy responsible for a poor outcome.

Transcranial magnetic stimulation of the motor cortex in cervical spondylosis and spinal canal stenosis.

STUDY DESIGN: This study investigated the clinical usefulness of motor evoked potentials and a silent period after motor evoked potentials produced by transcranial magnetic stimulation of the brain. OBJECTIVE: The results were correlated with the clinical state of the patients with myelopathy, whereas no abnormality of the conduction time was observed in the patients with spinal canal stenosis. SUMMARY OF BACKGROUND DATA: Magnetic stimulation has been widely used for examination of the descending excitatory motor pathways in the central nervous system, but little attention has been paid to cervical spondylosis and spinal canal stenosis. METHODS: Motor evoked potentials were examined in 35 normal subjects, 67 patients with cervical spondylotic myelopathy, and 24 patients with spinal canal stenosis. Motor evoked potentials were evoked by transcranial brain stimulation during relaxation and during maximum voluntary contraction of the target muscle. RESULTS: The central motor conduction time was found to correlate with the clinical state of the myelopathy patients, whereas no abnormality of the conduction time was observed in the patients with spinal canal stenosis. During maximum voluntary contraction of the target muscle, a silent period was always observed after the motor evoked potentials in the normal subjects, and its duration was markedly shortened in the myelopathy patients. CONCLUSIONS: In cervical myelopathy patients, the central motor conduction time was correlated with clinical evaluation and the silent period was significantly shortened. These findings about duration of the central motor conduction time and the silent period might be a useful parameter of spinal pathology.

Reinforcement of motor evoked potentials by remote muscle contraction.

We investigated the effects of remote muscle contraction on the amplitude and latency of motor-evoked potentials (MEPs) recorded from tibialis anterior and lateral gastrocnemius after transcranial magnetic stimulation of the motor cortex. In particular, consideration was given to the effects of unilateral handgrip of different strengths, jaw clench, and combined bilateral handgrip (Jendrassik maneuver) and jaw clench. Eight healthy adult volunteer subjects (six women, two men) participated in the main study. The clinical usefulness of this form of facilitation was subsequently demonstrated in three patients with myelopathy. Transcranial magnetic stimulation of the motor cortex was delivered from a Cadwell MES-10 (100% intensity) with a 9.5-cm circular coil positioned with the rim over the vertex. Stimuli were delivered ∼ 1 s after initiation of reinforcement. In the main study of normal subjects, surface recordings of the evoked compound muscle action potentials were made bilaterally from anterior tibialis and lateral gastrocnemius. In the individual studies of patients, MEPs were also recorded from abductor pollicis brevis and other muscles innervated from roots below the level of lesion. The principal results showed that unilateral handgrip (50 and 100% maximum voluntary contraction, MVC) of either hand enhanced the amplitude of MEPs bilaterally in both tibialis anterior and lateral gastrocnemius in all normal subiects (p < 0.05). The mean increase in amplitude associated with 100% MVC unilateral handgrip was >300% of the control value when the subject was relaxed (p < 0.01). The bilateral Jendrassik maneuver and jaw clench were also effective in increasing (p < 0.05) MEP amplitude in both muscle groups. These two procedures did not yield the same degree of reinforcement as 100% unilateral handgrip. Remote muscle contractions induced a reduction in MEP latency of 1-2 ms (p < 0.05). The clinical importance of these observations was demonstrated by the fact that remote muscle reinforcement enabled identification of low-amplitude MEPs that might otherwise have been missed in the three patients with spinal cord trauma.

Electric discharge patterns of ankle muscles during the normal gait cycle.

EMG patterns in ankle muscles were examined during normal gait cycles in 147 healthy asymptomatic adults. In all subjects, the tibialis anterior (Ta) showed marked activities around the toe-off and before the heel-strike, and the gastrocnemius lateral head (Gl) showed marked activity during the midstance phase but no activity in the early part of the swing phase. The Ta activity contributed to ground clearance, prevention of foot-drop, and shock absorption at the heel-strike. The Gl activity contributed to push-off from the ground and prevention of foot-drop. The Ta activity consisted of double bursts with (15% of subjects) or without (44%) electric silence in the midswing phase, continuous discharge (33%), and triple discharge patterns (8%). The Gl activity consisted of a single-peak (95%) pattern or double-peak (5%) patterns.

Pseudarthrosis of the radius associated with neurofibromatosis: report of a case and review of the literature.

An 11-year-old child with pseudarthrosis of the radius associated with neurofibromatosis was treated by conventional bone graft. Five years after the operation, the pseudarthrosis united, but the grafted bone was slightly sclerotic and bowed. This article describes the clinical findings and postoperative results, and discusses the current surgical approaches in the treatment of pseudarthrosis of the radius.

Methodological considerations contributing to variability of the quadriceps H-reflex.

The clinical usefulness of the quadriceps H-reflex is limited because of the difficulty of elicitation and its inherent variability in amplitude. In the present study we attempted to identify the influence of methodological variables (head position and remote muscle contractions) on the amplitude of the H-reflex evoked in vastus medialis, vastus lateralis and rectus femoris from the right leg of 13 healthy adult subjects. Square wave stimuli (1-ms duration) were delivered percutaneously to the femoral nerve. The 50% maximal amplitude H-reflexes were evoked while the subject reclined with head facing to the right, left, up and down or while the subject performed Jendrassik's maneuver. The results show a significant increase in the reflex amplitude when the subject's head was turned to the right; there was either a mild increase or no change in amplitude of the response when the subjects faced to the left, up and down. The evoked potential tended to decrease when the subjects closed their eyes; however, the tendency to increase with neck position was not changed. Remote muscle contractions enhanced the amplitude of the response. These results present further evidence of the characteristics of the quadriceps H-reflex and identify postural influences as one controllable source of variability in the L3-L4 root electrodiagnostic test.