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Torque-velocity relationships of the knee extensor and flexor muscles in individuals sustaining injuries of the anterior cruciate ligament.

Muscle deficits in 58 patients with chronic anterior cruciate ligament (ACL) insufficiency were evaluated after completion of a 6 month rehabilitation program. Quadriceps and hamstring torques were measured on a modified Cybex II isokinetic dynamometer. Twenty-nine of our patients were tested just prior to undergoing ACL reconstruction, and patients who were continuing to tolerate their conditions served as controls. For the surgical group, significant quadriceps deficits (P less than 0.01) were found for all speeds and at both the 30 and 60 degrees positions. The nonsurgical group had significant deficits at the 30 degrees position at 180 degrees/sec, and at 60 degrees for the 0 degree/sec and 30 degrees/sec. However, in comparing the two groups no significant differences were noted. Regarding hamstring deficits in the surgical group, significant deficits were seen only at 30 degrees of flexion at 180 degrees/sec. The nonsurgical group had similar deficits. Of interest was the observation that the hamstring:quadriceps (H:Q) ratio was found to be both speed-position dependent. Overall, no correlation was found between the presence of strength deficits following a rehabilitation program and the need for surgery.

Adolescent↗

Ground reaction torque and pathway of point of application of ground reaction force during gait of intoeing children.

One hundred twenty-four children with intoeing and 80 age-matched controls were investigated with the Kistler force plate. Tr2, reflecting the maximum external rotational ground reaction torque, is reduced by 30% to 40% in all intoeing children. There also is an appreciably shorter pathway of the point of application of the ground reaction force in the Y-direction (from 20% to 25%) and an obvious medial shift of the point of application of the ground reaction force in the X-direction (from 105% to 290%), from heel strike to toe-off as compared with controls. In spontaneous correction of intoeing, point of application of the ground reaction force in the X-direction becomes more close to normal. The "foot progression angle," which can easily be calculated from the force plate measurements to judge the degree of intoeing, is different from the values in the literature.

Biomechanical Phenomena↗

A high pull torquing auxiliary for use with the Begg appliance.

Treatment of the severe Class II division 2 malocclusion is difficult whatever appliance system is used. A small auxiliary, for use with the Begg appliance, is described. This enables torque and intrusive forces to be delivered to the upper central incisors, using High Pull Headgear. A case treated using this device is shown, and the changes brought about are demonstrated.

Adolescent↗

Torque-in-base: another straight-wire myth?

The theoretical inaccuracies of straight-wire systems which incorporate torque in the bracket face are discussed, with the conclusion that this variation from the original design is unlikely to be of any practical significance.

Dental Stress Analysis↗

Hereditary determinants of manual torque.

Data from a longitudinal study of twin children and siblings, 155 girls and 134 boys (aged 4 to 9 yr.), on a torque test confirmed that during this age period manually produced circling patterns change from clockwise to counterclockwise orientation. A genetic influence is suggested.

Aging↗

Changes in peak torque arm-shoulder strength of high school baseball pitchers during the season.

Pre- and postseason measurements of peak torque arm strength were made at 180 deg./sec. and 300 deg./sec. on both throwing and nonthrowing arms of five male high school varsity baseball pitchers. The major findings were significant losses in adduction strength in both throwing and nonthrowing shoulders at 180 deg./ sec. and internal rotation strength for both sides at both speeds. The primary implication from these preliminary findings is that significant losses of arm-shoulder strength may be associated with injuries to the pitching arm.

Adolescent↗

Gain and delay of human vestibulo-ocular reflexes to oscillation and steps of the head by a reactive torque helmet. I. Normal subjects.

Vestibulo-ocular reflexes (VOR) were evaluated with a reactive torque helmet that imposed high-frequency oscillation (2-20 Hz) or step displacements of the head in the horizontal plane. The present paper describes the experimental and analytical techniques and the results for normal subjects, which will serve as a baseline for the evaluation of vestibular pathology. For comparison, manually controlled head steps were also applied, as described in the literature. Eye and head movements were recorded with magnetic search coils. Non-vestibular effects were avoided by the use of high stimulus frequencies and the analysis of short time-windows (< 100 msec) after steps. Helmet-imposed steps caused a virtually uniform head acceleration (average magnitude 770 degrees/sec) in the first 90 msec. This resulted in a linear relation between eye and head velocities; the gain and delay of the VOR could be calculated independently from the slope and offset of this relation. Such estimates appear more reliable than those obtained with conventional techniques. Normal subjects had a VOR gain of about 0.9 and a delay of about 5 msec. The results of sinusoidal head oscillation were in agreement with the results for steps. The responses to manually generated head steps agreed in general with those to helmet-induced steps, but because of the non-uniform acceleration they allowed a less exact analysis of function.

Acceleration↗

Gain and delay of human vestibulo-ocular reflexes to oscillation and steps of the head by a reactive torque helmet. II. Vestibular-deficient subjects.

Vestibulo-ocular reflexes (VOR) were evaluated with a reactive torque helmet that imposed high-frequency oscillation (2-20 Hz) or step displacements of the head in the horizontal plane. The present paper describes the results in patients with vestibular deficiencies (labyrinthine defective; LD); experimental and analytical techniques and results for normal subjects were described in Part 1 of this paper. The patient groups included: total unilateral LD (related to acoustic neuroma; n = 40); severe (clinically total) bilateral LD (n = 7); bilateral hyporeflexia (n = 14); unilateral hyporeflexia (n = 11); and patients with LD phenomena that had subsided (n = 3). Helmet-induced head steps provided the most specific information. Characteristically, gain was lowered in one direction or both directions after unilateral or bilateral vestibular lesions, respectively; in general, the magnitude of the gain reduction correlated well with the degree of complaints and disability. Surprisingly, delay was systematically prolonged (up to several tens of milliseconds) in all groups of subjects with manifest vestibular pathology. These results suggest that the determination of delay, in addition to gain of the VOR, is feasible and important in the evaluation of vestibular function. The results of head oscillation generally supported the results for steps, but were somewhat less specific. The responses to manually generated head steps roughly agreed with those to helmet-induced steps, but because of the non-uniform acceleration they allowed a less exact analysis of VOR function.

Acceleration↗

Evaluation of a dynamometer for measurement of isometric and isokinetic torques.

A modified version of the original Cybex II dynamometer with a temperature compensated strain gauge transducer has been evaluated. It was found that the calibration constant was dependent of the vertical load of the device. The ratio (k) between the applied and the recorded torque is angle independent during extension and k is equal to 1.18 and during flexion k is angle dependent and can be expressed as k = -.0008 theta + 1.208, where theta is the angle of flexion.

Biomechanical Phenomena↗

Effects of alignment variables on thigh axial torque during swing phase in AK amputee gait.

It is suggested that a major source of discomfort for above-knee amputees during the swing phase of walking, is the thigh axial torque (TAT) transferred at the stump--socket interface. The relation between TAT and variations in its six relevant alignment adjustments, has been investigated. A computerized routine has been established which indicates optimum choice of alignment setting, based on minimal TAT peaks. Feasibility for attenuating swing phase TAT has been demonstrated in three simulated patterns of amputee gait. As a conclusion, it is suggested that a useful clinical tool could be based on the presented alignment optimization procedure and may be expanded to include other factors associated with swing and stance phase comfort and performance.

Amputation, Surgical↗

Removal torque for bone-cement and titanium screws implanted in rabbits.

Screw-shaped implants of commercially pure titanium and polymerized methyl methacrylate were inserted into the rabbit tibia. The animals were divided into two groups, and the implants were unscrewed after 5 weeks and 9 months, respectively. After both intervals, removal torque was greatest for the titanium implants. This difference was probably due to lower biocompatibility for the plastic material.

Animals↗

Tuning of Magnetic Anisotropy in Hexairon(III) Rings by Host-Guest Interactions: An Investigation by High-Field Torque Magnetometry.

Full chemical control of magnetic anisotropy in hexairon(III) rings can be achieved by varying the size of the guest alkali metal ion. Dramatically different anisotropies characterize the Li(I) and Na(I) complexes of [Fe(6)(OMe)(12)(L)(6)] (L=1,3-propanedione derivatives; a schematic representation of the Li(I) complex is shown), as revealed by high-field torque magnetometry-Iron: (g), oxygen: o, carbon: o, Li(+): plus sign in circle.

Journal Article↗

The role of limb torque, muscle action and proprioception during closed kinetic chain rehabilitation of the lower extremity.

This paper defines the differences between open and closed kinetic chain exercise and explains the role of limb torque, muscle action, and proprioception during rehabilitation of the lower extremity. Closed kinetic chain rehabilitation is shown to decrease shear forces, increase proprioception, and increase muscle group coordination through examples of progressive exercises. The authors conclude that closed kinetic chain rehabilitation is an economical, efficient, and effective means of rehabilitation, with the ultimate goal of enhancing proprioception, thus gaining lower extremity joint stability.

Journal Article↗