An apparatus and a method for measuring the relationship of triceps surae torques to tibio-tarsal angles in man

Do Muscle Changes Contribute to the Neurological Disorder in Spastic Paresis?

Background

At the onset of stroke-induced hemiparesis, muscle tissue is normal and motoneurones are not overactive. Muscle contracture and motoneuronal overactivity then develop. Motor command impairments are classically attributed to the neurological lesion, but the role played by muscle changes has not been investigated.

Methods

Interaction between muscle and command disorders was explored using quantified clinical methodology-the Five Step Assessment. Six key muscles of each of the lower and upper limbs in adults with chronic poststroke hemiparesis were examined by a single investigator, measuring the angle of arrest with slow muscle stretch (XV1) and the maximal active range of motion against the resistance of the tested muscle (XA). The coefficient of shortening CSH = (XN-XV1)/XN (XN, normally expected amplitude) and of weakness CW = (XV1-XA)/XV1) were calculated to estimate the muscle and command disorders, respectively. Composite CSH (CCSH) and CW (CCW) were then derived for each limb by averaging the six corresponding coefficients. For the shortened muscles of each limb (mean CSH > 0.10), linear regressions explored the relationships between coefficients of shortening and weakness below and above their median coefficient of shortening.

Results

A total of 80 persons with chronic hemiparesis with complete lower limb assessments [27 women, mean age 47 (SD 17), time since lesion 8.8 (7.2) years], and 32 with upper limb assessments [18 women, age 32 (15), time since lesion 6.4 (9.3) years] were identified. The composite coefficient of shortening was greater in the lower than in the upper limb (0.12 ± 0.04 vs. 0.08 ± 0.04; p = 0.0002, while the composite coefficient of weakness was greater in the upper limb (0.28 ± 0.12 vs. 0.15 ± 0.06, lower limb; p < 0.0001). In the lower limb shortened muscles, the coefficient of weakness correlated with the composite coefficient of shortening above the 0.15 median CSH (R = 0.43, p = 0.004) but not below (R = 0.14, p = 0.40).

Conclusion

In chronic hemiparesis, muscle shortening affects the lower limb particularly, and, beyond a threshold of severity, may alter descending commands. The latter might occur through chronically increased intramuscular tension, and thereby increased muscle afferent firing and activity-dependent synaptic sensitization at the spinal level.

A novel treatment for prevention of post-traumatic elbow stiffness using onaBotulinum toxin type A: a prospective placebo controlled randomized trial

Approximately 30% of all upper extremity fractures are elbow fractures which may result elbow stiffness. This study aimed to investigate the efficacy of onaBotulinum Toxin type A injection to prevent post-traumatic pain and elbow-stiffness. All patients were included who presented to a single surgeon with supracondylar/ intraarticular distal humerus fractures, proximal ulna and radius fractures. The study was developed in a randomized placebo controlled study between 2003-2007. The Disabilities of the Arm, Shoulder, and Hand (DASH) score as well as the arc-of-motion (AOM) were assessed after three, six, twelve-months and final follow up for evaluation. Of the 31-patients included, 15-patients (48.4%) received Botox injections. In all patients no complication was observed when injecting a dosage 100-units for the brachialis and biceps brachii muscles. Furthermore, it was an effective method to prevent post-traumatic elbow stiffness, lasting six- months. Significant differences in DASH, VAS-score and ROM after three-months between the Botox and control group (DASH 21.6±11.0 vs. 55.3±11.0 ; VAS 1.2±5.2 vs. 5.7±21.9 ; ROM 103±7.6 vs. 73±6.3 ; p>0.05) were identified in the prospective group. Botulinum toxin is a safe, reliable and effective treatment to prevent post-traumatic elbow stiffness. Our study demonstrates improved early range-of- motion (p<0.05), better extension after 6 weeks and improved functional outcome including VAS and DASH score (p<0.05).

Foot flexibility confounds the assessment of triceps surae extensibility in children with spastic paresis during typical physical examinations

Accurate assessment of the talo-crural (ankle) joint angle at physical examination is important for assessing extensibility of m. triceps surae (TS) in children with spastic cerebral paresis (SCP). The main aim of this study was to quantify foot flexibility during standardized measurements of TS muscle-tendon complex extensibility (i.e. based on foot-sole rotation) in SCP children, and typical developed (TD) ones. Additionally, we aim to define a method that minimizes the confounding effects of foot flexibility on estimates of talo-crural joint angles and TS extensibility. Children, aged 6-13 years, with SCP (GMFCS I-III, n = 13) and TD children (n = 14) participated in this study. Externally applied -1 Nm, 0 Nm, 1 Nm and 4 Nm dorsal flexion foot plate moments were imposed. Resulting TS origin-insertion lengths, foot sole (φ_FoSo) rotations, and changes in talo-crural joint angle (φ_TaCr) were measured. Foot flexibility was quantified as Δ(φ_TaCr -φ_FoSo) between the 0 Nm and 4 Nm dorsal flexion conditions. In both groups, φ_FoSo rotations of approximately 20° were observed between 0 Nm and 4 Nm dorsal flexion, of which about 6° (≈30%) was related to foot flexibility. Foot flexibility correlated to φ_FoSo (r = 0.69) but not to φ_TaCr (r = 0.11). For φ_FoSo no significant differences were found between groups at 4 Nm. However, for SCP children the mean estimate of φ_TaCr was 4.3° more towards plantar flexion compared to the TD group (p < 0.05). Normalized TS lengths show a higher coefficient of correlation with φ_TaCr (r² = 0.82) than with φ_FoSo (r² = 0.60), indicating that TS lengths are better estimated by talo-cural joint angles. In both SCP and TD children aged 6-13 year, estimates of TS length and extensibility based on foot sole assessments are confounded by foot flexibility. Assessments of TS extensibility at physical examination will be more accurate when based on measurements of talo-crural joint angles.

Muscle Shortening and Spastic Cocontraction in Gastrocnemius Medialis and Peroneus Longus in Very Young Hemiparetic Children

Objectives

Muscle shortening and spastic cocontraction in ankle plantar flexors may alter gait since early childhood in cerebral palsy (CP). We evaluated gastrosoleus complex (GSC) length, and gastrocnemius medialis (GM) and peroneus longus (PL) activity during swing phase, in very young hemiparetic children with equinovalgus.

Methods

This was an observational, retrospective, and monocentric outpatient study in a pediatric hospital. Ten very young hemiparetic children (age 3 ± 1 yrs) were enrolled. These CP children were assessed for muscle extensibility (Tardieu scale X_V1) in GSC (angle of arrest during slow-speed passive ankle dorsiflexion with the knee extended) and monitored for GM and PL electromyography (EMG) during the swing phase of gait. The swing phase was divided into three periods (T1, T2, and T3), in which we measured a cocontraction index (CCI), ratio of the Root Mean Square EMG (RMS-EMG) from each muscle during that period to the peak 500 ms RMS-EMG obtained from voluntary plantar flexion during standing on tiptoes (from several 5-second series, the highest RMS value was computed over 500 ms around the peak).

Results

On the paretic side: (i) the mean X_V1-GSC was 100° (8°) (median (SD)) versus 106° (3°) on the nonparetic side (p = 0.032, Mann-Whitney); (ii) X_V1-GSC diminished with age between ages of 2 and 5 (Spearman, ρ = 0.019); (iii) CCI_GM and CCI_PL during swing phase were higher than on the nonparetic side (CCI_GM, 0.32 (0.20) versus 0.15 (0.09), p < 0.01; CCI_PL, 0.52 (0.30) versus 0.24 (0.17), p < 0.01), with an early difference significant for PL from T1 (p = 0.03).

Conclusions

In very young hemiparetic children, the paretic GSC may rapidly shorten in the first years of life. GM and PL cocontraction during swing phase are excessive, which contributes to dynamic equinovalgus. Muscle extensibility (X_V1) may have to be monitored and preserved in the first years of life in children with CP. Additional measurements of cocontraction may further help target treatments with botulinum toxin, especially in peroneus longus.

Resistance to ankle dorsiflexion in hemiparetic stroke patients

The purpose of this study was to measure, compare, and correlate on both the paretic and nonparetic sides of 20 hemiparetic stroke patients, the resistance of the ankle to dorsiflexion with the knee extended and the knee flexed. While resistance to ankle dorsiflexion was measured, the electromyographic (EMG) activity of the ankle plantar flexor muscles was monitored. EMG activitywas virtually nonexistent, except in two of the patients tested. An analysis of variance demonstrated that the resistance to dorsiflexion was significantly greater on the paretic side and with the knee extended. Resistance with the knee extended on the paretic side was significantly correlated with time since onset. The resistances of the ankle of each side with the knee in each position were significantly correlated. The results suggest that the triceps surae muscle group of the paretic side is hypoextensible compared to that of the nonparetic side. The hypoextensibility may contribute to the difficulty that stroke patients have in dorsiflexing their ankles.

Biomechanical characteristics of human ankle-joint muscles

Equivalent biomechanical characteristics of human ankle-joint muscles have been determined by impact and vibration tests. The estimate of the stiffness and damping coefficients has yielded, respectively, (2.67 +/- 0.48) X 10(4) N X m-1 and (811.58 +/- 201.3) N X s X m-1 by impact actions, n = 126; (1.49 +/- 0.35) X 10(4) N X m-1 and (430.1 +/- 36.1) N X s X m-1 -by vibration actions, n = 7. The characteristics of the ankle-joint muscles of subjects representing different kinds of sports have proved to be different.

Effects of muscle length on an increased stretch reflex in children with cerebral palsy

No inhibitory influence of length on the increased stretch reflex was found in the internal gastrocnemius muscle of 19 cerebral palsied children. A facilitory influence of length was found in at least five patients in which quantitative data were obtained. These results were compared with previous data on a facilitory influence in the hamstrings and inhibitory influence in quadriceps muscles.

Maximum isokinetic ankle plantar and dorsal flexion torques in trained subjects

Isokinetic ankle plantar- and dorsal-flexion torques, IPF and IDF, respectively, were measured in twenty-five physically healthy athletes, fifteen males and ten females, with simultaneous recording of rectified, linearly enveloped surface electromyograms, and peak electromyographic tensions (PEMG). Angular delays from the start of motion to occurrence of peak torques were also registered. Manoeuvres were performed in two knee positions. For comparison of strength 30 non-athletic (untrained) controls were included. IPF, but not IDF, was greater in the trained than in the untrained subjects. Formulae for estimation of IPF at 30 degrees differ between trained and untrained subjects. Smaller gender differences in maximum strength for trained than for untrained subjects suggest that habitual rather than genetic dissimilarities cause sex differences in strength. Slope differences in the negative exponential models which characterize IPF and IDF as functions of increasing velocity of angular motion may be caused by different structural properties of ankle flexors and extensors. A lower PEMG of the m. gastrocnemius in the flexed than in the extended knee positions can explain the lower IPFs, suggesting that mechanical rather than supraspinal factors cause postural IPF differences. In contrast, greater IDF in the flexed than in the extended knee positions may indicate that neurogenic mechanisms are involved.

Effects on torque angle curve of differences between the recorded tibia-calcaneal angle and the true anatomical angle

The present study gives the results of a comparison of the recorded and true tibia-calcaneal angles in 17 normal subjects and in 14 patients with abnormally hypoextensible non contracting triceps. 1. For a minimal passive torque, the difference between true and recorded angles varied considerably from one individual to another. The mean and ranges for the two groups were respectively: -8 degrees (+7 degrees, -21 degrees) and -7 degrees (+5 degrees, -20 degrees). 2. When the passive torque increased as a result of slow passive lengthening of the muscle, the true curve was steeper than the recorded one, owing to differences between the two angle measurements. For each of the two groups the differences in means and ranges were respectively: 6 degrees (0 degrees, +13.5 degrees) and 8 degrees (3 degrees, 12 degrees). 3. Subjects made isometric voluntary contractions of the triceps surae at fixed angles which corresponded to step by step muscle lengthening. The resulting true curve was much steeper than the recorded curve. The differences in means and ranges were: 7 degrees (1.5 degrees, +15 degrees) in children of the two groups and respectively 3 degrees (0 degrees, +9 degrees) and 12 degrees (10 degrees, 14 degrees) in adults of the two groups. The present results show that this methodology was the only reliable way of correctly obtaining passive and active torque-angle curves, measuring differences between subjects, appreciating the effects of treatments and these by ascertaining whether or not trophic muscle regulation was defective.

Isokinetic and static plantar flexion characteristics

Isokinetic and static maximum plantar flexion torques were measured in 135 adults with sedentary professions. Close associations between isokinetic and static peak torques were found. Between the ages 20--49 years strength did not differ. Thereafter strength declined as a function of age. Maximum strength was 35% lower in females than in males. The right plantar flexion strength was slightly lower than the left. Maximum plantar flexion strength was about 15% lower with flexed than with extended knees. A negative exponential model characterized the decline of strength as a function of increased isokinetic velocity of angular motion. Seventy per cent or more of the variations in maximum static and isokinetic strength could be explained by anthropometric variables and by age, and by the extent of physical activity in subjects younger than 50 years. Formulas for estimation of expected static and isokinetic strengths are given.

Trophic muscle regulation in children with congenital cerebral lesions

A decrease in sarcomere number and hypoextensibility of ankle extensors was observed in certain children with congenital cerebral lesions. This phenomenon was reproducible and reversible in normal animals, i.e. trophic regulation adapted the muscle to the imposed length. The form of the torque-ankle angle curve was studied in 30 children. Its modification after treatment was considered as a sign of muscle adaptation. This adaptation was present in one group of 14 children. The steepness of the curve increased or diminished depending on the initial disorder and the treatment administered. In another group, treatment failed to modify the shape of the curve. In certain cases trophic regulation of the muscle appeared to be absent.

Relationship of triceps surae torques to photographed tibia-calcaneum angles in man (II)

A previous paper described an apparatus and method for giving the relationship between triceps surae torque and the tibia-calcaneum angle. As a first approximation we took the angle between the calcaneum and the foot-plate as being invariable in all subjects, when the torque was zero. The aim of the present work is to measure the inter-individual variations of the angle. 1. Guide-marks are selected on the skin; showing the axes of the calcaneum and of the leg. Metal rods indicate the axes thus defined and the true angle between the leg and the calcaneum is measured by photography. The curves drawn from these true angles differ from the preceding curves by 0 degrees to 10 degrees for normal children and +12 degrees to -15 degrees for cerebral palsied children. 2. The photographic method verifies the exactitude of the trigonometrical method of correcting angles that we proposed in the previous paper.

To what extent is the tibia-calcaneum angle a reliable measurement of the triceps surae length? Radiological correction of the torque-angle curve (III)

Previous papers gave some methods for the reliable measurement of the tibia-calcaneum angle. It is of common use to evaluate the physical properties of triceps surae on the basis of torque-angle curves. However this method is reliable only if each tibia-calcaneum angle corresponds to a defined distance between the insertions of the muscle in subjects of the same height. Evidence is given by radiological measurements that this correspondance is correct in normal children. However, this is no longer true in certain cerebral palsied children because of abnormal translation of the calcaneum and/or abnormal ratio of bone sizes. In this case the torque-angle curves do not define properly the torque-length curves. A method of correction is given. This correction may be as high as 15 degrees.