Niladri Kumar Mahato

The power of the mind: the cortex as a critical determinant of muscle strength/weakness

We tested the hypothesis that the nervous system, and the cortex in particular, is a critical determinant of muscle strength/weakness and that a high level of corticospinal inhibition is an important neurophysiological factor regulating force generation. A group of healthy individuals underwent 4 wk of wrist-hand immobilization to induce weakness. Another group also underwent 4 wk of immobilization, but they also performed mental imagery of strong muscle contractions 5 days/wk. Mental imagery has been shown to activate several cortical areas that are involved with actual motor behaviors, including premotor and M1 regions. A control group, who underwent no interventions, also participated in this study. Before, immediately after, and 1 wk following immobilization, we measured wrist flexor strength, voluntary activation (VA), and the cortical silent period (SP; a measure that reflect corticospinal inhibition quantified via transcranial magnetic stimulation). Immobilization decreased strength 45.1 ± 5.0%, impaired VA 23.2 ± 5.8%, and prolonged the SP 13.5 ± 2.6%. Mental imagery training, however, attenuated the loss of strength and VA by ∼50% (23.8 ± 5.6% and 12.9 ± 3.2% reductions, respectively) and eliminated prolongation of the SP (4.8 ± 2.8% reduction). Significant associations were observed between the changes in muscle strength and VA (r = 0.56) and SP (r = -0.39). These findings suggest neurological mechanisms, most likely at the cortical level, contribute significantly to disuse-induced weakness, and that regular activation of the cortical regions via imagery attenuates weakness and VA by maintaining normal levels of inhibition.

Morphology of sustentaculum tali: Biomechanical importance and correlation with angular dimensions of the talus

SUMMARY OF BACKGROUND DATA The talus and the calcaneus share the bulk of load transmitted from the leg to the skeleton of the foot. The present study analyses the inter-relationship between the superior articular surface and the angular dimensions of the talus with the morphology of the sustentaculum tali. OBJECTIVE Identification of possible relationships between different angular parameters of the talus morphology and the sustentaculum tali in context of load transmission through the foot. METHODS One articular surface and three angular parameters at the junction of the head and the body were measured from dried human talar bones. Corresponding calcaneal samples were measured for four dimensions at the sustentaculum tali. Correlation and regression statistical values between parameters were worked out and analysed. RESULTS Several parameters within the talus demonstrated significant correlations amongst themselves. The neck vertical angle showed a strong correlation with the articulating surface area below the head of the talus. CONCLUSIONS The inter-relationship between articular and angular parameters within the talus demonstrates strong correlation for certain parameters. Data presented in the study may be helpful to adjust calcaneal and talar screw placement techniques, prosthesis designing and bio-mechanical studies at this important region.

Articular and angular dimensions of the talus: Inter-relationship and biomechanical significance

SUMMARY OF BACKGROUND DATA Research on biomechanics of the ankle and foot has demonstrated a complex pattern of load distribution through the ankle joint. OBJECTIVE Investigating possible relationship between articular dimensions, angular parameters and overall talar morphology. METHODS Two linear dimensions, six articular surfaces and three angular parameters were measured from dried human talar bones (left=60; right=82). Angular parameters were measured at the neck of the bone (junction of the head and the body). Correlation and co-variation were worked out between the values of surface area parameters and the angular orientations measured from all the samples in context of load transmission across the talus. RESULTS The total trochlear surface area of the talus totaled approximately equal to the sum of areas at the head and the lower surface of the talus. The vertical angle showed a strong correlation with the articulating surface area below the head of the talus in contact with the spring ligament. CONCLUSIONS Articular surface areas as well as the angular orientations of talar components vary with the magnitude of stress subjected to the bone. The inter-relationship between articular and angular parameters within the talus demonstrates strong correlation for certain parameters.

Entrapment of the Median Nerves and Brachial Arteries in the Lower Arms Bilaterally and Additional Origin of Biceps brachii Muscle: Case Report

No es infrecuente observar atrapamientos neuro-vasculares asociados con variaciones en el origen de los musculos del brazo. A pesar de haberse observado cabezas adicionales del musculo biceps braquial y fibras extra del musculo braquial raramente estas cabezas adicionales bilaterales han sido causantes de la compresion del nervio mediano y de la arteria braquial. En este trabajo presentamos las cabezas del musculo biceps braquial originandose en gran parte en el tabique intermuscular medial compartiendo su origen con el musculo braquial. Los origenes adicionales del musculo forman largos tuneles musculo fasciales. Los tuneles miden 8 cm de longitud, y se extienden desde la parte inferior del brazo hasta la fosa cubital. Tanto el nervio mediano como la arteria braquial pasan por el tunel. La parte inferior del tunel izquierdo dio origen a fibras pertenecientes al musculo flexor superficial del antebrazo. Las estructuras neurovasculares no otorgaron colaterales en el tunel. El conocimiento de estas variaciones puede ayudar a los clinicos en el diagnostico y el tratamiento de neuropatias y compromiso vascular.

Preliminary Evidence That Excitatory Transcranial Direct Current Stimulation Extends Time to Task Failure of a Sustained, Submaximal Muscular Contraction in Older Adults

BACKGROUND Decreased cortical excitability has been proposed as a potential mechanism underlying task failure during sustained muscular contractions, and cortical excitability may decrease with old age. We tested the hypothesis that transcranial direct current stimulation, which has been reported to raise cortical excitability, would prolong the time to task failure during a sustained muscular contraction in older adults. METHODS Thirteen older adults (68.3±2.0 years; eight women and five men) performed isometric, elbow flexions to failure while receiving sham or anodal transcranial direct current stimulation. Order of stimulation was randomized, and the subjects and investigators were blinded to condition. Time to task failure was measured alongside selected psychological indices of perceived exertion and affect. RESULTS Anodal transcranial direct current stimulation prolonged mean time to task failure by approximately 15% (16.9±2.2 vs 14.7±1.8 minutes) and slowed the rate of increase in rating of perceived exertion (0.29±0.03 vs 0.31±0.03) relative to the sham condition. CONCLUSIONS These preliminary findings suggest that anodal transcranial direct current stimulation enhances time to task failure of a sustained, submaximal contraction in older adults by potentially increasing cortical excitability and/or influencing the perception of exertion. These results raise the question of whether interventions that acutely increase cortical excitability could enhance physical function and/or exercise-induced adaptations in older adults.

Implications of structural variations in the human sacrum: why is an anatomical classification crucial?

PurposeAn array of diversity in sacral anatomy including lumbosacral transitional variations is commonly found in the general population. These anatomical variations involve alterations in number of sacral segments, auricular surface area, and neural arch dimensions and are associated with biomechanical, surgical and obstetric implications.MethodsThe present study reports screening >300 dried human sacral specimens and grouping them based on the common variations observed specifically in context of the number of sacral segments, position of the auricular surfaces, and type of the neural arch components.ResultsScreening and grouping of the samples presented a five-group classification and coding system that incorporates specific structural characteristic in a sacrum.ConclusionThe grouping and coding system developed in this study classifies variabilities associated with sacral anatomy along a common-to-rare anatomical spectrum that may provide handy information needed in a clinical, biomechanical, obstetric or medico-legal context.

Metric analysis of loading magnitudes at articular and non-articular weight-bearing surfaces in human calcaneus

The calcaneus is axially loaded at its articular interface with the talus. A large bulk of this load is transmitted to the ground across the non-articular tubercles at the plantar surface of the bone. A small part of the incumbent load sustained by the calcaneus is directed towards the forefoot at the calcaneo-cuboid junction. This study investigates the proportion of load distributed across the articular and non-articular surfaces of the calcaneus. The present study demonstrates strong and significant correlation between some of the load bearing variables and suggests the need for further investigations to understand the effect of angular aspects of axial loading on the calcaneus. Accounting for the relative distribution of weight across the articular and non-articular areas may enable us to appreciate the internal trabecular structure of the calcaneus in light of its clinical importance.

Anatomy of Lumbar Interspinous Ligaments: Attachment, Thickness, Fibre Orientation and Biomechanical Importance

La literatura relacionada con el estudio del ligamento interespinoso en la region lumbar es escasa. Pocos estudios han permitido comprender la orientacion de las fibras de este ligamento en diferentes niveles lumbares. Fueron disecados cadaveres de 19 hombres 6 y mujeres para exponer los ligamentos interespinosos debajo de las vertebras lumbares. La union de las fibras y su direccion se observo en todos los espacios interespinosos lumbares. El grosor de los ligamentos se midieron en todos los niveles. Las fibras del ligamento interespinoso se encontro orientada de manera diferente en los espacios lumbares interespinosos. En los dos espacios superiores las fibras eran mas horizontales. En los dos espacios centrales (por debajo de L3 y L4) las fibras se curvaban y extendian postero-superiormente. Las fibras eran mas gruesas en los ligamentos de los espacios inferiores en comparacion con los superiores. La media de espesor presentada por region fue: Alta (0,22 mm), Medio (0,37 mm) y L5-S1 (0,72 mm). Los ligamentos en mujeres fueron ligeramente mas delgados. Tambien se observo que las fibras de los ligamentos interespinosas se adhieren a las superficies internas del ligamento supraespinoso. La union de los ligamentos en L5-S1 eran relativamente mas verticales y robustas. En ningun caso se observo ausencia o cavitaciones de los ligamentos, excepto en un caso con ligamento bilaminar a nivel L3-L4. La anatomia de los ligamentos interespinosos senala su probable rol en la restriccion de la flexion aguda en la columna lumbar.

A randomized control trial to determine the effectiveness and physiological effects of spinal manipulation and spinal mobilization compared to each other and a sham condition in patients with chronic low back pain: Study protocol for The RELIEF Study

BACKGROUND Low back pain (LBP) is one of the most common reasons for seeking medical care. Manipulative therapies are a common treatment for LBP. Few studies have compared the effectiveness of different types of manipulative therapies. Moreover, the physiologic mechanisms underlying these treatments are not fully understood. Herein, we present the study protocol for The Researching the Effectiveness of Lumbar Interventions for Enhancing Function Study (The RELIEF Study). METHODS AND STUDY DESIGN The RELIEF Study is a Phase II RCT with a nested mechanistic design. It is a single-blinded, sham-controlled study to test the mechanisms and effectiveness of two manual therapy techniques applied to individuals (n = 162; 18-45 years of age) with chronic LBP. The clinical outcome data from the mechanistic component will be pooled across experiments to permit an exploratory Phase II RCT investigating the effectiveness. Participants will be randomized into one of three separate experiments that constitute the mechanistic component to determine the muscular, spinal, and cortical effects of manual therapies. Within each of these experimental groups study participants will be randomly assigned to one of the three treatment arms: 1) spinal manipulation, 2) spinal mobilization, or 3) sham laser therapy. Treatments will be delivered twice per week for 3-weeks. DISCUSSION This data from this will shed light on the mechanisms underlying popular treatments for LBP. Additionally, the coupling of this basic science work in the context of a clinical trial will also permit examination of the clinical efficacy of two different types of manipulative therapies.

Lumbosacral loadbearing, sagittal shift in the line of gravity and joint surface areas

This author reads with great interest the article by Ezemagu et al. (2018) where the authors, in a male-only sample study, have quantified and analyzed L4 and L5 lower body and facet articulating areas to demonstrate loadbearing patterns at the lumbosacral junction (LSJ). The authors conclude that a chunk of loading at the L5 vertebra is routed through its facets, resulting in a proportionate reduction in the inferior surface area of the L5 vertebral body. The authors show a strong correlation between this reduction and a matching increase in the L5 inferior facet surface area that corresponds to the magnitude of loading diverted to the facets. The author of this letter would humbly like to comment on a few observations from the aforesaid article. In a series of articles, Pal and colleagues have described detailed relationships between changing features in the vertebral anatomy and the dynamic of loadbearing through the spine (Pal 1989; Pal et al. 2001; Pal and Routal 1987, 1986, 1999). Given the limited scope of this letter, this author would like to enumerate a few minor observations first, followed by discussing more pertinent aspects related to the conclusions made by Ezemagu et al. (1) Studying a collection of randomly arranged bones from anatomical museums may be inappropriate for loadbearing studies. However, the study of cataloged, disarticulated collections of the spinal skeleton from separate individual subjects is an invaluable source of information. (2) The differences in mean surface area variables reported by Ezemagu et al. (2018) with Aruna et al. (2003) may have appeared not only due to the racial factors as proposed by the authors, but also could have resulted from the male-only and younger age group samples used by the former. (3) The regression equation offered by the authors may not be a fit-all formula for reasons such as (a) the exclusivity of the male-only sample selected for the study; and (b) the wide range and distribution of the measured variables secondary to race, variations in individual bio-mechanics and developmental patterns (Cihák 1970; Davis 1961; Denis 1983; Hey et al. 2018). Pal and Routal have proposed modifications to Dennis’ three-column theory by analyzing the continuum of anatomical changes between the anterior and posterior vertebral elements. They suggested a relative shift of the line of gravity (LG) as a possible mechanism for these structural changes (Fig. 1) (Davis 1961; Denis 1983; Pal and Routal 1986). Pal and colleagues quantified the L4 inferior surface area to be larger than the lower body area of L5 and objectively validated that a greater percentage of compressive loading on L5 was routed to the facets through the strong L5 pedicles and laminae. Formulating the pedicle index (with several other indices) and body area ratios, they proposed a mechanistic explanation of sagittal cross-transfer of loading patterns between the anterior to posterior elements in vertebrae ( including the L5), depending upon the position of the LG in the mid sagittal plane, relative to the spine. Progressive increase in L1–L4 inferior body surface and facet areas, with sudden decrease in the inferior L5 body and increase in L5 facet joint areas have been reported in the literature (Pal and Routal 1987). In this study, the authors calculated increased percentile loadbearing at the laminae (17.62%) and at the facets (21.52%) at the L5, thereby suggesting several clinic-pathological implications of laminectomy-induced instability, vulnerability of spine fractures (specifically at the transition zones) and, as subsequently seen in their later studies, mechanisms of kyphoscoliotic deformities (Pal 1991; Pal and Routal 1996, 1996; Pal and Sherk 1988). The claim for ‘exceptionality’ by Ezemagu et al. of finding the mean deference of the total inferior surface area between L4 and L5 to be ‘insignificant’, may be an overexpectation for two reasons. Firstly, it is well understood that the reduction in the inferior L5 surface area is accompanied * Niladri Kumar Mahato nm620511@ohio.edu