Amplitude threshold criteria improve surface electrode specificity during walking and functional movements

Tensor Fascia Latae Muscle Structure and Activation in Individuals With Lower Limb Musculoskeletal Conditions: A Systematic Review and Meta-Analysis

BACKGROUND

Dysfunction of the tensor fascia latae (TFL) muscle is often clinically implicated in many musculoskeletal disorders.

OBJECTIVE

To systematically review the literature of the TFL muscle to determine whether there are differences in its structure and activation between individuals with and without lower limb musculoskeletal conditions.

DATA SOURCES

A comprehensive search in MEDLINE, EMBASE, CINHAL, and LILACS was undertaken from year of inception to 9 July 2019.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies that directly investigated the structure or activity of the TFL muscle between individuals with a lower limb musculoskeletal condition and a pain-free control group.

RESULTS

Seventeen studies were included (n = 556 participants), eight reporting structure and ten activation of the TFL muscle. Conditions included lateral hip pain, hip joint pathology, ACL injury, iliotibial band syndrome, and patellofemoral joint osteoarthritis. Meta-analysis identified with low confidence (p value = 0.07) a small tendency towards hypertrophy in the affected side of participants with hip joint diseases (SMD 0.37, 95% CI [- 0.02, 0.77]). Moderate effect sizes were found for a higher cross-sectional area of the TFL/sartorius ratio in abductor tendon tear (SMD 0.74; 95% CI [0.05, 1.43, p value = 0.04), and for a smaller body mass normalized TFL volume in patellofemoral joint osteoarthritis (SMD - 0.61; 95% CI [- 1.23, 0.00], p value = 0.05). Normalised electromyography (EMG) amplitude did not differ between groups for any condition, but when EMG was analysed as linear envelopes or synergies, some differences in pattern of TFL activation were observed between individuals with lateral hip pain and controls. Timing of TFL activation did not differ between individuals with knee conditions and controls.

CONCLUSIONS AND IMPLICATIONS

Common clinical assumptions of the role of TFL muscle in lower limb musculoskeletal conditions are not well investigated and poorly supported by current research. There are contradictory findings on the muscle size of TFL. Differing methodology in muscle activation studies precludes a clear interpretation for comparison between groups.

PROSPERO REGISTRATION NUMBER

CRD42017076160.

A method to estimate EMG crosstalk between two muscles based on the silent period following an H-reflex

The crosstalk phenomenon consists in recording the volume-conducted electromyographic activity of muscles other than that under study. This interference may impair the correct interpretation of the results in a variety of experiments. A new protocol is presented here for crosstalk assessment between two muscles based on changes in their electrical activity following a reflex discharge in one of the muscles in response to nerve stimulation. A reflex compound muscle action potential (H-reflex) was used to induce a silent period in the muscle that causes the crosstalk, called here the remote muscle. The rationale is that if the activity recorded in the target muscle is influenced by a distant source (the remote muscle) a silent period observed in the electromyogram (EMG) of the remote muscle would coincide with a decrease in the EMG activity of the target muscle. The new crosstalk index is evaluated based on the root mean square (RMS) values of the EMGs obtained in two distinct periods (background EMG and silent period) of both the remote and the target muscles. In the present work the application focused on the estimation of the degree of crosstalk from the soleus muscle to the tibialis anterior muscle during quiet stance. However, the technique may be extended to other pairs of muscles provided a silent period may be evoked in one of them.

Elderly unilateral transtibial amputee gait on an inclined walkway: a biomechanical analysis

The greatest population of amputees in developed nations are elderly dysvascular transtibial amputees. Conventional prostheses, e.g. the solid ankle cushioned heel (SACH) foot, create difficulties in walking on inclines. The aim of this study was to analyse the gait characteristics of elderly amputees walking on an incline, through quantitative three-dimensional biomechanical analysis, by comparing them to age-matched controls. Participants walked up and down an inclined (5 degrees) instrumented walkway at a self-selected pace. A Vicon System 370 was used to acquire gait data, including temporo-spatial characteristics, ground reaction forces (GRF), electromyography (EMG), kinematics, and kinetics of the lower limb. Compared to the age-matched controls, the amputees demonstrated reduced speed, knee and hip range of motion, hip moments, vertical GRF, along with increased amplitude and periods of muscle activation. The residual limb also had shorter single support stance phase, small stance phase knee moments, and the smallest moments and powers. These differences demonstrate instability in stance of the residual limb. The sources of this instability include the prosthesis' limited range of ankle motion and ankle power generation, coupled with the residual limb's limited proprioception and tolerance of force. For these amputees to regain a gait pattern equivalent to their able-bodied counterparts on inclined walkways, they must be equipped with a prosthesis that has a full range of ankle motion and active power generation at the ankle. Prosthesis design and rehabilitation training should also improve the proprioception of their residual limb and increase their tolerance of force through the residual limb.