Gluteus minimus: an intramuscular EMG investigation of anterior and posterior segments during gait

The association between lateral hip muscle size/intramuscular fat infiltration and hip strength in active young adults with long standing hip/groin pain

OBJECTIVES

To investigate associations between lateral hip muscle size/intramuscular fat infiltration (MFI) and hip strength in active young adults with longstanding hip/groin pain.

DESIGN

Cross-sectional study.

SETTING

University/Clinical.

PARTICIPANTS

Sub-elite soccer and Australian Football players (n = 180; 37 female) with long standing hip/groin pain.

MAIN OUTCOME MEASURES

Muscle size (volume) and MFI of gluteus maximus, medius, and minimis, and tensor fascia latae (TFL) were assessed using magnetic resonance imaging. Isometric hip strength was measured with handheld dynamometry. Associations between muscle size/MFI were assessed using linear regression models, adjusted for body mass index and age, with sex-specific interactions.

RESULTS

Positive associations were identified between lateral hip muscle volume and hip muscle strength, particularly for gluteus maximus and gluteus minimus volume. For all muscles, hip abduction was associated with an increase in strength by up to 0.69 N (R2 ranging from 0.29 to 0.39). These relationships were consistent across sexes with no sex interactions observed. No associations were found between MFI and strength measures.

CONCLUSION

Greater lateral hip muscle volumes are associated with greater hip strength in active young adults with long standing hip/groin pain, irrespective of sex. Gluteus maximus and minimus volume showed the most consistent relationships with hip strength across multiple directions.

Gluteal Muscle Fatty Atrophy: An Independent Risk Factor for Surgical Treatment in Elderly Patients Diagnosed with Type-III Fragility Fractures of the Pelvis

BACKGROUND

Gluteal muscle fatty atrophy (gMFA) might impair pelvic stability and negatively influence remobilization in patients with fragility fractures of the pelvis (FFP). This study aimed to investigate the association between gMFA and surgical indication in patients with FFP.

METHODS AND MATERIALS

A retrospective analysis of 429 patients (age ≥80) diagnosed with FFP was performed. gMFA of the gluteus maximus, medius, and minimus was evaluated using a standard scoring system based on computer tomography images.

RESULTS

No significant difference was found in gMFA between genders or among FFP types. The severity of gMFA did not correlate with age. The severity of gMFA in the gluteus medius was significantly greater than in the gluteus maximus, whereas the most profound gMFA was found in the gluteus minimus. gMFA was significantly more severe in patients who underwent an operation than in conservatively treated patients with type-III FFP, and an independent correlation to surgical indication was found using logistic regression.

CONCLUSION

Our findings imply that gMFA is an independent factor for surgical treatment in patients with type-III FFP. Besides focusing on the fracture pattern, the further evaluation of gMFA could be a feasible parameter for decision making toward either conservative or surgical treatment of type-III FFP.

Evaluating the contribution of fat infiltration in anterior gluteus minimus muscle to walking ability in female with unilateral hip osteoarthritis and candidates for total hip arthroplasty

BACKGROUND

The purpose of this study is to investigate the relationship between gait and fat infiltration in anterior and posterior gluteus minimus in the patients with hip osteoarthritis.

METHODS

Ninety-one female patients who were diagnosed as the unilateral hip osteoarthritis, classified into Kellgren-Lawrence global scoring system grades 3 or 4, and candidate for total hip arthroplasty were retrospectively reviewed. The horizontally cross-sectional regions of interest for the gluteus medius and anterior and posterior gluteus minimus were manually circumscribed in a single transaxial computed tomography image and muscle density of those regions were obtained. The gait was assessed as the step and speed with the 10-Meter Walk Test. The multiple regression analysis was used to compare the step and speed with age, height, range of motion in flexion, the muscle density of anterior gluteus minimus in the affected side, and that of gluteus medius muscle in both affected and unaffected sides.

FINDINGS

Multiple regression analysis for step revealed that the muscle density of anterior gluteus minimus in the affected side and height were the independent predictors for step (R² = 0.389, p < 0.001). That for speed identified the muscle density of anterior gluteus minimus in the affected side as the only factor determining speed (R² = 0.287, p < 0.001).

INTERPRETATION

The fatty infiltration of anterior gluteus minimus muscle in affected side can be a predictor for the gait in in female with unilateral hip osteoarthritis and candidates for total hip arthroplasty.

Electromyographic analysis of the three subdivisions of gluteus medius during two different exercises: Wall press exercise and figure-of-four position

BACKGROUND

Gluteus medius (GM) is a segmented muscle involving three muscular subdivisions. Rehabilitation exercises has been suggested to strengthen specific subdivisions.

OBJECTIVE

This study aimed to evaluate muscular activation of the anterior, middle, and posterior subdivisions of the GM during two different exercises.

METHODS

A total of 28 healthy active subjects participated in this study. Muscle activity using surface electromyography was recorded for the three GM subdivisions during figure-of-four position (FFP) and wall press (WP). Non-parametric Kruskal-Wallis test was used to detect differences between GM subdivisions on each exercise and the Mann-Whitney U test was used to compare muscular activation across exercises.

RESULTS

There were statistically significant differences (P< 0.001) in all GM subdivision during FFP and WP exercises. Both exercises showed greater activation of the posterior subdivision than the middle and anterior subdivisions, with the WP causing highest activation of the posterior subdivision.

CONCLUSION

In line with the WP exercise, the FFP produces sufficient activity to provide potential strength gains on the posterior subdivision and could be a viable option to include in the early stages of the rehabilitation process. Clinicians may use this information to make more informed decisions about exercise selection for strengthening specific GM subdivision.

Comparison between a targeted exercise program and a sham intervention on gluteal muscle activity in people with hip osteoarthritis: Analysis of secondary outcomes from a randomised clinical trial

BACKGROUND

People with hip osteoarthritis (OA) typically display altered gluteus minimus (GMin) and gluteus medius (GMed) activity during gait, in addition to reduced walking speed and stride length. It is unknown if current rehabilitation programs address changes in gluteal muscle activity in people with hip OA.

RESEARCH QUESTION

Can a targeted gluteal intervention restore normal gluteal muscle segment activity during gait in people with hip OA?

METHODS

This study presents secondary outcomes from a multi-site, double-blinded clinical trial in which participants with radiologically confirmed mild-moderate hip OA were randomised into a targeted gluteal or sham intervention for 12-weeks following baseline testing. Electromyography (EMG) outcomes were only conducted at a single site and data were collected from 22 participants. Intramuscular electrodes were inserted into two segments of GMin (anterior, posterior) and three segments of GMed (anterior, middle, posterior) to record average amplitude, peak amplitude and time to peak (TTP) during the first 60 % of the gait cycle (stance phase) at baseline and post-intervention.

RESULTS

Following the targeted gluteal intervention, posterior GMin displayed a decrease in average (P = 0.032, ES=1.04) and peak (P = 0.017, ES=1.17) muscle activity during late stance phase with a shift to an earlier TTP (P = 0.034, ES=1.02). There were no further significant changes between groups for other outcome measures. Similar trends for an earlier TTP were observed for the posterior segment of GMed following the targeted intervention (P = 0.095, ES=0.87). The earlier TTP in the posterior segments of both GMin and GMed post-intervention resembled patterns observed in a healthy young population.

SIGNIFICANCE

A targeted gluteal intervention can positively impact activity in posterior GMin during gait in people with hip OA when compared to a sham intervention.

Natural History of Degenerative Hip Abductor Tendon Lesions

BACKGROUND

The best treatment of degenerative hip abductor tendon lesions remains largely unknown, as the natural course of the disease has not yet been reported. The aim of the present study was to investigate the natural history of symptomatic degenerative hip abductor lesions.

HYPOTHESIS

Nonoperatively treated hip abductor lesions progress over time, resulting in refractory hip pain and low functional outcomes.

STUDY DESIGN

Case series (prognosis); Level of evidence, 4.

METHODS

Consecutive patients with greater trochanteric pain syndrome and degenerative changes on magnetic resonance imaging (MRI) of the symptomatic hip were included. Bilateral hip MRI scans and a clinical examination were performed at a minimum follow-up of 36 months to study the type and location of hip abductor lesion. Progression of a lesion was defined as a more severe lesion as compared with the initial MRI results or if the lesion extended to another, initially not involved, trochanteric facet. The muscle's fatty infiltration (FI) was also described.

RESULTS

From 106 patients identified, 58 patients (64 hips) aged 66 ± 14 years (mean ± SD) agreed to return to the clinic for follow-up MRI and met the inclusion criteria. At a mean 71-month follow-up, an overall 34% (22/64) of lesions had progressed over time: from trochanteric bursitis to tendinopathy (9/64, 14%) or partial tear (5/64, 8%), from tendinopathy to partial tear (4/64, 6%), from a partial to complete tear (3/64, 4.5%), and with 1 complete tear (1/64, 1.5%) extending to another trochanteric facet. Interestingly, 90% of partial tears remained stable or transformed into a scar. Although patients with a progressive lesion experienced more trochanteric pain (visual analog scale, 4.6 vs 2.8; P = .001), the functional outcomes were comparable with patients with a stable lesion. The majority of hips with a partial tear (64%) demonstrated a progression of gluteus minimus FI from a median grade of 1 to 2, whereas only 1 hip (3%) progressed from grade 2 to 3. Only 3 hips (9%) with a partial tear had a progression of gluteus medius FI, which did not differ significantly from the contralateral unaffected side.

CONCLUSION

Nonoperative treatment might be a valid long-term option for degenerative hip abductor lesions, especially for partial tears, which demonstrated a low risk of clinically relevant progression or muscle FI and similar clinical outcomes to those reported in the literature for operatively treated hip abductor tendon lesions.

Characteristics of Surface Electromyograph Activity of Cervical Extensors and Flexors in Nonspecific Neck Pain Patients: A Cross-Sectional Study

Background and Objectives: We identified typical surface electromyogram (sEMG) activities of the cervical extensors and flexors during motions in the three anatomical planes in healthy adults. The aim of this study was to explore characteristics of sEMG activities of these cervical muscles in nonspecific neck pain (NSNP) patients based on healthy adults. Materials and Methods: Participants were 24 NSNP patients (NSNP group, mean ± SD of age, 47.5 ± 15.5) and 24 healthy adults (control group, 20.5 ± 1.4). For each participant, sEMG of the cervical extensors and flexors was recorded during neck flexion, extension, bilateral lateral flexion, bilateral rotation, and at the neutral position in Phase I (the neck from the neutral position to the maximum range of motion), Phase II (at the maximum range of motion), and Phase III (from the maximum range of motion to the neutral position), yielding a total of 42 phases. A percentage of maximum voluntary contraction to normalize muscle activity in each phase was calculated to obtain the ratio of muscle activities in the extensors and flexors in each of 36 phases of the motions to the neutral position and ratio of the flexors to extensors in activity for 21 phases. Results: In 28 of 36 phases of the motions, the ratios of muscle activities in the extensors and flexors to the neutral position in the NSNP group were significantly larger than the control group (p < 0.05). In 6 of 21 phases, the ratios of the flexors to extensors in activity in the NSNP group were significantly larger than in the control group (p < 0.05). Conclusions: In NSNP patients, the activity of the cervical extensors and flexors associated with neck motion increased with an imbalance in activity between these muscles compared to their activity in healthy adults. The results of this study will be useful in understanding the pathogenesis of NSNP and in constructing an objective evaluation of the treatment efficacy on NSNP patients.

Effects of a targeted resistance intervention compared to a sham intervention on gluteal muscle hypertrophy, fatty infiltration and strength in people with hip osteoarthritis: analysis of secondary outcomes from a randomised clinical trial

Background

People with hip osteoarthritis are typically offered a combination of education and exercise to address muscle atrophy and weakness. Limited evidence exists to assess the efficacy of exercise programs on muscle structure or function in this population. The aim of this study was to evaluate the effects of targeted resistance exercise on gluteal muscle hypertrophy and strength in people with mild-to-moderate hip osteoarthritis.

Methods

Twenty-seven participants with radiologically confirmed hip osteoarthritis recruited from a single site of a multi-site, double-blind clinical trial were randomly allocated to receive a 12-week targeted gluteal intervention or sham intervention. Magnetic resonance imaging and hand-held dynamometry were used to determine change in gluteal muscle volume, fatty infiltration and hip muscle strength. For gluteal muscle volume and strength outcomes mixed model analyses of variance (ANOVA) were conducted. A general linear model (ANOVA) analysis with fixed effects parameter estimates was used to assess the impact of sex on gluteal muscle size and strength of the affected limb only. For muscle fat index a mixed method ANOVA was used to assess the differences between groups and over time.

Results

In the targeted intervention group, gluteus minimus volume increased from baseline to post-intervention in both limbs (pooled mean difference: 0.06 cm³/kg, 95% confidence interval: 0.01 to 0.11) while no change occurred in the sham group (time x group effect: P = 0.025). Gluteus medius, gluteus maximus and tensor fascia lata volume did not change significantly over time. Hip strength (abduction, adduction, flexion, extension, external and internal rotation) improved similarly in both groups (time main effect: P ≤ 0.042). There was a consistent, albeit non-significant, pattern of reduced fatty infiltration after the targeted intervention.

Conclusion

Targeted resistance exercise resulted in gluteus minimus hypertrophy, but improvements in hip strength occurred in both groups. Clinicians delivering hip osteoarthritis rehabilitation programs might consider implementing a targeted exercise program to attenuate disease associated changes within gluteal muscles.

Trial registration

Australian New Zealand Clinical Trials Registry, ID: ACTRN12617000970347. Registered prospectively on 5 July 2017.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05907-4.

No Difference in Hip Muscle Volumes and Fatty Infiltration in Those With Hip-Related Pain Compared to Controls

Background

Little is known about muscle morphology in people with hip-related pain, without signs of femoro-acetabular impingement syndrome (FAIS). Identifying changes in hip muscle volume, fatty infiltrate and establishing relationships between muscle volume and strength, may provide insight into potential early treatment strategies.

Purposes

To: (i) compare the volumes and fatty infiltrate of gluteus maximus, gluteus medius, gluteus minimis, tensor fascia latae and quadratus femoris between symptomatic and less-symptomatic sides of participants with hip-related pain; (ii) compare the volumes and fatty infiltrate of hip muscles between healthy controls and symptomatic participants; and (iii) explore relationships of hip muscle volumes to muscle strength and patient-reported outcome measures in people with hip-related pain.

Study Design

Cross-sectional study.

Methods

Muscle volume and fatty infiltrate (from magnetic resonance imaging), hip muscle strength, patient-reported symptoms, function and quality of life (QOL) were determined for 16 participants with hip-related pain (no clinical signs of FAIS; 37±9 years) and 15 controls (31±9 years). Using One Way Analysis of Co-Variance tests, muscle volume and fatty infiltrate was compared between the symptomatic and less-symptomatic sides in participants with hip-related pain as well as between healthy controls and symptomatic participants. In addition, hip muscle volume was correlated with hip muscle strength, hip-reported symptoms, function and QOL.

Results

No differences in all the studied muscle volumes or fatty infiltrate were identified between the symptomatic and less-symptomatic hips of people with hip-related pain; or between people with and without hip-related pain. Greater GMED volume on the symptomatic side was associated with less symptoms and better function and QOL (ρ=0.522-0.617) for those with hip-related pain. Larger GMAX volume was associated with greater hip abduction and internal rotation strength, larger GMED volume was associated with greater hip extension strength, and larger QF volume was associated with greater hip abduction strength (rho=0.507-0.638).

Conclusion

People with hip-related pain and no clinical signs of FAIS have hip muscle volumes that are not significantly different than those of matched pain-free controls or their less-symptomatic hip. Larger GMED muscle volume was associated with fewer symptoms and greater strength.

Level of evidence

Level 3a.

The Mode of Activity of Cervical Extensors and Flexors in Healthy Adults: A Cross-Sectional Study

Background and Objectives: The purpose of this study was to investigate the activity of bilateral cervical extensors and flexors on the sagittal, frontal, and horizontal planes of healthy adults during motions of the neck in a sitting position, which has not been satisfactorily investigated by surface electromyogram (sEMG). Materialand Methods: We recruited 35 healthy participants (mean ± standard deviation of age, 20.3 ± 2.4). sEMG recordings of the cervical extensors and flexors were performed for a total of nine seconds in three phases: Phase I involved the motion of the neck from the neutral position to the maximum range of motion; Phase II involved maintaining the neck at the maximum range of motion; and Phase III involved the motion of the neck from the maximum range of motion to the neutral position during neck flexion, extension, right and left lateral flexion, right and left rotation, and maintaining the neck in the neutral position. Muscle activities in each motion were normalized as a percentage of maximal voluntary contraction (%MVC) so that the muscles could be compared. Results: The %MVC of the extensors was significantly larger than that of the flexors in the neutral position (p < 0.001). In addition, the %MVCs of the following were significantly larger than the %MVC in the neutral position: the extensors in flexion (p = 0.014) and extension (p = 0.020), the ipsilateral extensors (p = 0.006) and flexors (p < 0.001) in lateral flexion in Phase I; the flexors in flexion (p < 0.001), the extensors in extension (p = 0.010), and the ipsilateral extensors and flexors in lateral flexion (p < 0.001) in Phase II; the extensors and flexors in flexion (p < 0.001), the flexors in extension (p < 0.001), the ipsilateral flexors (p < 0.001), the contralateral flexors (p = 0.004) and the contralateral extensors (p = 0.018) in lateral flexion in Phase III; and the bilateral extensors and contralateral flexors during rotation in all three phases (p < 0.001). Conclusion: The typical sEMG activities of the extensors and flexors during motion of the neck in healthy adults were identified in this study; this information can be used to understand the pathophysiology of non-specific neck pain and to provide an index for evaluating the effect of treatment.

Efficacy of Exercise-Based Rehabilitation Programs for Improving Muscle Function and Size in People with Hip Osteoarthritis: A Systematic Review with Meta-Analysis

Objective: To determine the effect of exercise-based rehabilitation programs on hip and knee muscle function and size in people with hip osteoarthritis. Methods: Seven databases were systematically searched in order to identify studies that assessed muscle function (strength or power) and size in people with hip osteoarthritis after exercise-based rehabilitation programs. Studies were screened for eligibility and assessed for quality of evidence using the GRADE approach. Data were pooled, and meta-analyses was completed on 7 of the 11 included studies. Results: Six studies reported hip and/or knee function outcomes, and two reported muscle volumes that could be included in meta-analyses. Meta-analyses were conducted for four strength measures (hip abduction, hip extension, hip flexion, and knee extension) and muscle size (quadriceps femoris volume). For hip abduction, there was a low certainty of evidence with a small important effect (effect size = 0.28, 95% CI = 0.01, 0.54) favouring high-intensity resistance interventions compared to control. There were no other comparisons or overall meta-analyses that identified benefits for hip or knee muscle function or size. Conclusion: High-intensity resistance programs may increase hip abduction strength slightly when compared with a control group. No differences were identified in muscle function or size when comparing a high versus a low intensity group. It is unclear whether strength improvements identified in this review are associated with hypertrophy or other neuromuscular factors.

Gluteal Muscle Atrophy and Increased Intramuscular Lipid Concentration Are Not Mitigated by Daily Artificial Gravity Following 60-Day Head-Down Tilt Bed Rest

Exposure to spaceflight and head-down tilt (HDT) bed rest leads to decreases in the mass of the gluteal muscle. Preliminary results have suggested that interventions, such as artificial gravity (AG), can partially mitigate some of the physiological adaptations induced by HDT bed rest. However, its effect on the gluteal muscles is currently unknown. This study investigated the effects of daily AG on the gluteal muscles during 60-day HDT bed rest. Twenty-four healthy individuals participated in the study: eight received 30 min of continuous AG; eight received 6 × 5 min of AG, interspersed with rest periods; eight belonged to a control group. T1-weighted Dixon magnetic resonance imaging of the hip region was conducted at baseline and day 59 of HDT bed rest to establish changes in volumes and intramuscular lipid concentration (ILC). Results showed that, across groups, muscle volumes decreased by 9.2% for gluteus maximus (GMAX), 8.0% for gluteus medius (GMED), and 10.5% for gluteus minimus after 59-day HDT bed rest (all p < 0.005). The ILC increased by 1.3% for GMAX and 0.5% for GMED (both p < 0.05). Neither of the AG protocols mitigated deconditioning of the gluteal muscles. Whereas all gluteal muscles atrophied, the ratio of lipids to intramuscular water increased only in GMAX and GMED muscles. These changes could impair the function of the hip joint and increased the risk of falls. The deconditioning of the gluteal muscles in space may negatively impact the hip joint stability of astronauts when reexpose to terrestrial gravity.

Hip muscle activity in male football players with hip-related pain; a comparison with asymptomatic controls during walking

OBJECTIVES

Compare muscle activity between male football players with and without hip-related pain. Morphological and intra-articular features of hip-related pain are proposed pre-cursors to hip osteoarthritis. Altered muscle activity is a feature of severe hip osteoarthritis, but it is not known whether differences exist earlier in the pathological spectrum.

DESIGN

Cross-sectional; SETTING: University laboratory; PARTICIPANTS: Forty-two male football players with hip-related pain; and 19 asymptomatic controls.

MAIN OUTCOME MEASURES

Hip muscle activity (Gluteus maximus, gluteus medius, tensor facia latae, adductor longus and rectus femoris) was recorded during walking using surface electromyography (EMG).

RESULTS

Men with hip-related pain had sustained rectus femoris activity prior to toe-off (47-51% of the gait cycle) (p = 0.01, ES = 0.51) unlike controls who had reduced activity. In men with severe hip-related pain, gluteus maximus EMG was sustained into mid-stance (12-20% of the gait cycle) (F = 6.15, p < 0.01) compared to controls.

CONCLUSIONS

Differences in rectus femoris and gluteus maximus activity were identified between male footballers with and without hip-related pain. The pattern of gluteus maximus EMG relative to peak, approaching mid-stance in severe hip-related pain, is consistent with observations in severe hip osteoarthritis. This supports the hypothesis that symptom severity may influence muscle activity across the spectrum of hip degeneration.

Functional characteristics associated with hip abductor torque in severe hip osteoarthritis

BACKGROUND

Hip abductor weakness due to the progression of hip osteoarthritis (OA) commonly causes poor functional mobility. The hip abductor strength has also been identified as a clinically relevant factor for successful functional outcomes after total hip arthroplasty.

OBJECTIVES

This study aimed to examine the functional characteristics related to hip abductor torque in patients with hip OA.

DESIGN

A cross-sectional survey study.

METHODS

One hundred and eight female patients with severe unilateral hip OA participated in this study. Hip abductor torque and pain were measured. The muscle cross-sectional area (CSA) and skeletal muscle density (SMD) of the gluteal muscles were also measured using computed tomography. To identify the hip parameters associated with hip abductor torque, multiple regression analysis was performed. The healthy model included the CSA and SMD of gluteus maximus, gluteus medius, and gluteus minimus; range of motion in hip abduction; age; and body mass index. The affected model included hip pain in addition to the healthy model.

RESULTS

In the affected limb, multiple regression analysis identified pain and angle of hip abduction as factors that determine hip abductor torque (Adjusted R² = 0.39). In contrast, our analysis identified CSA and SMD of the gluteus medius and SMD of the gluteus minimus as the significant variables related to hip abductor torque in the healthy limb (Adjusted R² = 0.40).

CONCLUSION

The findings of this study indicated that it is necessary to consider that hip pain may inhibit muscle exertion and contraction while training to improve the hip abductor torque in the affected limb.

The immediate effect of foot orthoses on gluteal and lower limb muscle activity during overground walking in healthy young adults

BACKGROUND

Although foot orthoses are often used in the management of lower limb musculoskeletal conditions, their effects on muscle activation is unclear, especially in more proximal segments of the lower limb.

RESEARCH QUESTION

Primary aim: Is there an immediate effect of foot orthoses on gluteal muscle activity during overground walking in healthy young adults? Secondary aim: Is there an immediate effect of foot orthoses on the activity of hamstring, quadriceps and calf muscles?

METHODS

In eighteen healthy young adults, muscle activity was recorded using fine wire electrodes for gluteus minimus (GMin; anterior, posterior) and gluteus medius (GMed; anterior, middle, posterior); and surface electrodes for gluteus maximus (GMax), hamstring, quadriceps and calf muscles. Participants completed six walking trials for two conditions; shoe and shoe with prefabricated foot orthoses. Muscle activity was normalised to the peak activity of the shoe condition and analysed using one-dimensional statistical non-parametric mapping to identify differences across the gait cycle.

RESULTS

Activity of GMed (anterior, middle, posterior) and GMin (posterior) was reduced in early stance phase when the orthosis was worn in the shoe (p < 0.05). GMin (anterior) activity was significantly reduced during swing (p < 0.05). Muscle activity was also significantly reduced during the orthoses condition for the lateral hamstrings and calf muscles (p < 0.05).

SIGNIFICANCE

Using foot orthoses may provide a strategy to reduce demand on GMin, GMed, lateral hamstring and calf muscles while walking.

Associations Between Measures of Physical Activity and Muscle Size and Strength: A Systematic Review

Objective

To determine whether physical activity is associated with lower limb muscle size and strength within the general population.

Data Sources

Six databases were systematically searched from inception using 3 main constructs: lower extremity, muscle volume, and muscle strength.

Study Selection

Studies that measured physical activity (using either objective or subjective measurements), lower limb muscle size, and strength were included. Available discrete group data were standardized using previously published age- and sex-specific normative values prior to analysis.

Data Extraction

The final analysis included 47 studies from an initial yield of 5402 studies. Standardized scores for outcome measures were calculated for 97 discrete groups.

Data Synthesis

As anticipated, lower limb muscle size was positively correlated with lower limb muscle strength (r=0.26, P<.01; n=4812). Objectively measured physical activity (ie, accelerometry, pedometry) (n=1944) was positively correlated with both lower limb muscle size (r=0.30, P<.01; n=1626) and lower limb strength (r=0.24, P<.01; n=1869). However, subjectively measured physical activity (ie, questionnaires) (n=3949) was negatively associated with lower limb muscle size (r=–0.59, P<.01; n=3243) and lower limb muscle strength (r=–0.48, P<. 01; n=3882).

Conclusions

This review identified that objective measures of physical activity are moderately associated with lower limb muscle size and muscle strength and can, therefore, be used to predict muscle changes within the lower limbs associated with exercise-based rehabilitation programs.

Gluteal atrophy and fatty infiltration in end-stage osteoarthritis of the hip: a case-control study

Aims

The gluteus minimus (GMin) and gluteus medius (GMed) have unique structural and functional segments that may be affected to varying degrees, by end-stage osteoarthritis (OA) and normal ageing. We used data from patients with end-stage OA and matched healthy controls to 1) quantify the atrophy of the GMin and GMed in the two groups and 2) describe the distinct patterns of the fatty infiltration in the different segments of the GMin and GMed in the two groups.

Methods

A total of 39 patients with end-stage OA and 12 age- and sex frequency-matched healthy controls were prospectively enrolled in the study. Fatty infiltration within the different segments of the GMin and the GMed was assessed on MRI according to the semiquantitative classification system of Goutallier and normalized cross-sectional areas were measured.

Results

The GMin was smaller in the OA-group (p < 0.001) compared to the control group, but there was no group difference in the size of the GMed (p = 0.101). Higher levels of fatty infiltration were identified in the anterior segment of the GMin (p = 0.006) and the anterior (p = 0.006) and middle (p = 0.047) segments of the GMed in the OA group. All subjects in the control group had fatty infiltration of the anterior segment of the GMin, but all except one had no fatty infiltration in the entire GMed.

Conclusion

End-stage OA was associated with significant atrophy of the GMin and higher levels of fatty infiltration, particularly in the anterior segments of the GMin and GMed. Minor fatty infiltration of the anterior segment of GMin appears to be a normal part of ageing. Our study has demonstrated different patterns of atrophy and fatty infiltration between patients with end-stage OA and healthy matched peers.

Cite this article: Bone Jt Open 2021;2(1):40–47.

A SYSTEMATIC REVIEW AND META-ANALYSIS OF COMMON THERAPEUTIC EXERCISES THAT GENERATE HIGHEST MUSCLE ACTIVITY IN THE GLUTEUS MEDIUS AND GLUTEUS MINIMUS SEGMENTS

Background

The gluteus medius (GMed) and gluteus minimus (GMin) muscle segments demonstrate different responses to pathology and ageing, hence it is important in rehabilitation that prescribed therapeutic exercises can effectively target the individual segments with adequate exercise intensity for strengthening.

Purpose

The purpose of this systematic review was to evaluate whether common therapeutic exercises generate at least high ( > 40% maximum voluntary isometric contraction (MVIC)) electromyographic (EMG) activity in the GMed (anterior, middle and posterior) and GMin (anterior and posterior) segments.

Methods

Seven databases (MEDLINE, EMBASE, CINAHL, AusSPORT, PEDro, SPORTdiscus and Cochrane Library) were searched from inception to May 2018 for terms relating to gluteal muscle, exercise, and EMG. The search yielded 6918 records with 56 suitable for inclusion. Quality assessment, data extraction and data analysis were then undertaken with exercise data pooled into a meta-analysis where two or more studies were available for an exercise and muscle segment.

Results

For the GMed, different variations of the hip hitch/ pelvic drop exercise generated at least high activity in all segments. The dip test, and isometric standing hip abduction are other options to target the anterior GMed segment, while isometric standing hip abduction can be used for the posterior GMed segment. For the middle GMed segment, the single leg bridge; side-lying hip abduction with hip internal rotation; lateral step-up; standing hip abduction on stance or swing leg with added resistance; and resisted side-step were the best options for generating at least high activity. Standing isometric hip abduction and different variations of the hip hitch/ pelvic drop exercise generated at least high activity in all GMin segments, while side-lying hip abduction, the dip test, single leg bridge and single leg squat can also be used for targeting the posterior GMin segment.

Conclusion

The findings from this review provide the clinician with confidence in exercise prescription for targeting individual GMed and GMin segments for potential strengthening following injury or ageing.

Level of Evidence

Level 1.

What is known about the subject

Previous reviews on GMed exercises have been based on single electrode, surface EMG measures at middle GMed segment. It is not known whether these exercises effectively target the other segments of GMed or the GMin at a sufficient intensity for strengthening.

What this study adds to existing knowledge

This review provides the clinician with confidence in exercise prescription of common therapeutic exercises to effectively target individual GMed and GMin segments for potential strengthening.

The pathological features of hip abductor tendon tears - a cadaveric study

Background

The hip abductors are crucial in maintaining pelvic stability. Tears in these tendons are common and often debilitating. There is uncertainty regarding both the histological and macroscopic features of hip abductor tears. This study aims to clarify both the macroscopic and microscopic features of the tendon and enthesis in hip abductor tendon tears.

Methods

Thirty-six cadavers with an average age of 81 were dissected, and the hip abductor mechanisms removed en-bloc. The presence, location and size of the tears were recorded and analysed. The samples were processed into histological blocks and viewed using both transmitted and polarised light. Tendon histology was graded using the modified Movin’s score in three sections (deep, middle and superficial layers) and the enthesis graded separately using 5-point criteria. Analysis of variance was used to confirm histological features associated with tears.

Results

Tears were found in 24 of 36 samples (67%). The most common finding was an isolated tear in the gluteus minimus (46%), followed by concurrent gluteus medius and gluteus minimus tears (33%). Histology revealed significantly more degeneration in both the tendon (p = 0.0005) and enthesis (p = 0.0011) when tears were present. Furthermore, these changes were concentrated in the deeper layers of the tendon (p = 0.0002) and enthesis (p = 0.003).

Conclusion

This study demonstrated degeneration as the primary pathology underlying hip abductor tendon tears. Degenerative changes occur in both the tendon and enthesis, with the deeper layers predominantly affected. These findings are important for guiding surgical repair techniques and to aid the development of novel materials and biologics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03784-3.

Pericapsular hip muscle activity in people with and without femoroacetabular impingement. A comparison in dynamic tasks

OBJECTIVES

Compare anterior pericapsular muscle activity between individuals with and without femoroacetabular impingement syndrome (FAIS) during dynamic tasks, to investigate whether muscle activity is consistent with a role in retracting the capsule to prevent impingement and active restraint of the femoral head in walking.

DESIGN

Cross-sectional.

SETTING

University-laboratory.

PARTICIPANTS

Thirteen athletes with FAIS and 13 pain-free controls.

MAIN OUTCOME MEASURES

Muscle activity was recorded using fine-wire (Iliocapsularis, iliacus and anterior gluteus minimus) and surface (rectus femoris) electromyography (EMG), during three hip flexion tasks (active and assisted hip flexion; squatting) and four walking trials.

RESULTS

Iliocapsularis EMG amplitude was no different between active and assisted hip flexion tasks around 90° of hip flexion in FAIS. There was no difference in EMG between groups in squatting. The pattern of burst activity preceding peak hip extension in iliacus, iliocapsularis, and anterior gluteus minimus was similar in both groups during walking.

CONCLUSION

In FAIS, similar activation of iliocapsularis during active and assisted hip flexion, despite reduced flexion torque demand in the latter, suggests a role in capsular retraction or enhanced hip joint protection. Pericapsular muscle activity in advance of peak hip extension during walking is consistent with a proposed contribution to femoral head control.

Gluteal muscle activity during running in asymptomatic people

BACKGROUND

Hip abductor muscle function is associated with running-related injuries. Previous electromyography (EMG) studies that reporting gluteal muscle activity when running have failed to account for the multiple segments of the gluteals, and have used surface electrodes, which may be contaminated by cross-talk of surrounding muscles.

RESEARCH QUESTION

This study aimed to: (i) develop EMG profiles of gluteus medius (GMed - anterior, middle and posterior) and gluteus minimus (GMin - anterior and posterior) segments during running; (ii) compare the activation patterns of each gluteal segment between running and walking; and (iii) compare surface EMG signals of running and walking to fine wire EMG signals of middle GMed.

METHODS

Ten physically active and asymptomatic people participated. Gluteal segment activation was assessed during running and walking over 10 m. Muscle activation was assessed using bipolar fine wire intramuscular EMG electrodes and GMed activation was also assessed using surface EMG.

RESULTS

During running, all gluteal segments presented peak amplitude during the stance phase and anterior GMin presented additional second peak amplitude during the swing phase. All gluteal segments evaluated demonstrated consistently higher amplitudes during the stance and swing phases of running compared to walking. The mean amplitude assessed using surface EMG was 32-87% higher compared to fine wire during both phases for running and walking.

SIGNIFICANCE

Greater activation of GMed segments during the stance phase and the increased anterior GMin activity during the swing phase indicate a potentially important role for pelvis and hip stabilization, respectively, which should be considered during development of targeted rehabilitation for running populations. The overestimated activation using surface electrodes highlights a limitation of using surface EMG during running and walking.

Gluteus medius and minimus activity during stepping tasks: Comparisons between people with hip osteoarthritis and matched control participants

BACKGROUND

Altered gluteus minimus (GMin) activity has been identified in people with hip osteoarthritis (OA) during gait with some evidence of altered gluteus medius (GMed) activity in patients with advanced OA. It is not known whether these muscles also exhibit altered activity during other functional tasks.

RESEARCH QUESTION

Does gluteal muscle activity during stepping tasks differ between people with hip OA and healthy older adults?

METHODS

Participants included 20 people with unilateral hip OA and 20 age-and sex-matched controls. Muscle activity in the three segments within GMed and two segments of GMin were examined using intramuscular electromyography during step-up, step-down and side-step tasks.

RESULTS

Participants in the OA group demonstrated reduced muscle activity early in the step-up task and a later time to peak activity in most muscle segments. Greater activity was identified in anterior GMin in people with hip OA during the side-step task. A delay in time to peak activity was identified in most muscle segments in people with OA during the side-step task.

SIGNIFICANCE

For participants with OA, reduced activity in most muscle segments and increased time spent in double limb stance during the step-up task could reflect the decreased strength and pain associated with single limb stance on the affected limb. This study provides further evidence of altered function of the deep gluteal muscles in people with hip OA and highlights the importance of addressing these muscles in rehabilitation.

Lower-Limb Biomechanics in Football Players with and without Hip-related Pain

PURPOSE

This study aimed to evaluate the differences in lower-limb biomechanics between adult subelite competitive football players with and without hip-related pain during two contrasting tasks-walking and single-leg drop jump (SLDJ)-and to determine whether potential differences, if present, are sex dependent.

METHODS

Eighty-eight football players with hip-related pain (23 women, 65 men) and 30 asymptomatic control football players (13 women, 17 men) who were currently participating in competitive sport were recruited. Biomechanical data were collected for the stance phase of walking and SLDJ. Pelvis, hip, knee, and ankle angles, as well as the impulse of the external joint moments, were calculated. Differences between groups and sex-specific effects were calculated using linear regression models.

RESULTS

Compared with their asymptomatic counterparts, football players with hip-related pain displayed a lower average pelvic drop angle during walking (P = 0.03) and a greater average pelvic hike angle during SLDJ (P < 0.05). Men with hip-related pain displayed a smaller total range of motion (excursion) for the transverse plane pelvis angle (P = 0.03) and a smaller impulse of the hip external rotation moment (P < 0.01) during walking compared with asymptomatic men. Women with hip-related pain displayed a greater total range of motion (excursion) for the sagittal plane knee angle (P = 0.01) during walking compared with asymptomatic women.

CONCLUSION

Overall, few differences were observed in lower-limb biomechanics between football players with and without hip-related pain, irrespective of the task. This outcome suggests that, despite the presence of symptoms, impairments in lower-limb biomechanics during function do not appear to be a prominent feature of people with hip-related pain who are still participating in sport.

Rehabilitation Exercises for the Gluteus Minimus Muscle Segments: An Electromyography Study

CONTEXT

The gluteus minimus (GMin) muscle consists of 2 uniquely oriented segments that have potential for independent function and have different responses to pathology and aging. For healthy young adults, it is unknown that which rehabilitation exercises specifically target the individual segments.

OBJECTIVE

To quantify segmental GMin activity for 6 common lower-limb rehabilitation exercises in healthy young adults and determine if significant differences exist in segmental activity levels between the exercises.

METHOD

Six common lower-limb rehabilitation exercises were performed by 10 healthy young adults with fine-wire electromyography (EMG) electrodes inserted into the anterior and posterior segments of the GMin muscle.

MAIN OUTCOME MEASURES

Electromyography signals were recorded, and median normalized exercise activity levels were reported and compared for each GMin segment across the 6 exercises.

RESULTS

High activity levels were generated in the anterior segment by the resisted hip abduction-extension exercise (51% maximum voluntary isometric contraction [MVIC]), whereas for the posterior segment, high activity levels were produced by the single-leg bridge (49% MVIC), the side-lie hip abduction (43% MVIC), the resisted hip abduction-extension exercise (43% MVIC), and the single-leg squat (40% MVIC). There were significant differences (P < .05) in the median electromyography activity levels for the anterior GMin segment but not for the posterior GMin segment across some of the exercises with large effect sizes.

CONCLUSION

Targeted rehabilitation exercises graded by exercise intensity can be prescribed specifically for the anterior and posterior GMin segments to aid in restoration of hip function following injury or aging.

The effect of altered stride length on iliocapsularis and pericapsular muscles of the anterior hip: An electromyography investigation during asymptomatic gait

BACKGROUND

Anterior pericapsular muscles potentially contribute to active hip joint stability in walking by controlling anterior femoral translation in peak extension. Alternatively, these muscles could flex the hip and tension the anterior capsule to aid initiation of swing. Although never investigated, the location of Iliocapsularis and its extensive anterior hip capsule attachment imply a potential role in these functions. We hypothesised if these muscles contribute to control of femoral head translation (rather than hip flexion), their activation would decrease when peak hip extension is reduced during shorter stride walking.

RESEARCH QUESTIONS

To provide the first description of iliocapsularis activity during walking and challenge the hypothesised roles of the anterior pericapsular hip muscles in gait by walking with shortened strides.

METHODS

Fifteen healthy volunteers walked with self-selected and shortened stride lengths. Electromyographic recordings were made from iliocapsularis, iliacus and anterior gluteus minimus with intramuscular electrodes, and rectus femoris with surface electrodes. Stride characteristics were measured using force sensors and 3D motion capture. Ensembles of burst activity profiles for each stride length were compared.

RESULTS

Iliocapsularis displayed a consistent EMG burst around toe-off (terminal hip extension) that peaked during early swing phase with self-selected strides. In shortened strides, iliocapsularis EMG increased during mid to late stance (p = 0.03), with no difference in other muscles. Iliocapsularis, iliacus and rectus femoris activity decreased during early stance (p < 0.01) in short strides, whereas gluteus minimus EMG increased (p = 0.03).

SIGNIFICANCE

Iliocapsularis displayed an EMG burst around toe-off during walking, and greater EMG during mid-late stance in short stride walking, which was not seen in other pericapsular muscles. Shortened strides increase the demand for active tensioning of the hip joint capsule in initial swing, and suggests a role for iliocapsularis during active hip flexion in pain free young individuals.

ESB Clinical Biomechanics Award 2018: Muscle atrophy-related increased joint loading after total hip arthroplasty and their postoperative change from 3 to 50 months

BACKGROUND

Hip joint loading is dominated by muscular activity. Thus, contact forces exceeding many times one's body weight are a consequence of imbalanced muscular activity. The objective was to analyze the influence of muscle atrophy after total hip arthroplasty on in vivo hip joint contact loading initially and long term. We hypothesized that an impaired periarticular muscle will lead to increase in vivo joint load, specifically in the long term.

METHODS

Using a group of nine patients with instrumented hip implants, contact forces and muscle status were analyzed one day prior to 3 and 50 months after joint arthroplasty. In vivo load measurements were performed for different activities of daily living (ADL). Pre- and postoperative pelvic CT scans were analyzed to assess the periarticular muscle status. Finally, the muscle morphologies and in vivo contact forces were compared.

RESULTS

At 3 months after total hip arthroplasty we found a significant correlation of lower lean gluteus minimus muscle (GMin) volume with higher loads during all tested activities of daily living. 50 months postoperatively statistical analysis revealed lower lean volume of the gluteus maximus to be correlated with higher joint loads in walking.

CONCLUSION

Our data generally show a good comparability between muscle status and joint contact forces and thus support our hypothesis that an impairment of periarticular musculature contributes to an increase of the in vivo joint loads after total hip arthroplasty. Effects were most pronounced during stair climbing and sit-down/stand-up from a chair at 3 months and during level walking at 50 months.

Hip abductor muscle volumes are smaller in individuals affected by patellofemoral joint osteoarthritis

OBJECTIVE

The aims of this study were twofold: firstly, to compare hip abductor muscle volumes in individuals with patellofemoral joint (PFJ) osteoarthritis (PFJ OA) against those of healthy controls; and secondly, to determine whether hip muscle volumes and hip kinematics during walking are related in individuals with PFJ OA and healthy controls.

METHODS

Fifty-one individuals with PFJ OA and thirteen asymptomatic, age-matched healthy controls ≥40 years were recruited. Volumes of the gluteus medius, gluteus minimus and tensor fasciae latae were obtained from magnetic resonance (MR) images. Video motion capture was used to measure three-dimensional hip joint kinematics during overground walking.

RESULTS

Significantly smaller gluteus medius (P = 0.017), gluteus minimus (P = 0.001) and tensor fasciae latae (P = 0.027) muscle volumes were observed in PFJ OA participants compared to controls. Weak correlations were observed between smaller gluteus minimus volume and larger hip flexion angle at contralateral heel strike (CHS) (r = -0.279, P = 0.038) as well as between smaller gluteus minimus volume and increased hip adduction angle at CHS (r = -0.286, P = 0.046).

CONCLUSION

Reduced hip abductor muscle volume is a feature of PFJ OA and is associated with increased hip flexion and adduction angles during the late stance phase of walking for PFJ OA participants and healthy controls.

Muscle size and composition in people with articular hip pathology: a systematic review with meta-analysis

OBJECTIVE

To synthesise and evaluate the current evidence investigating muscle size and composition in non-inflammatory articular hip pathology.

METHODS

A systematic review of five electronic databases, using three concepts; articular hip pathology (e.g., osteoarthritis (OA)); hip muscles; and outcomes (e.g., muscle size and adiposity) was undertaken. Studies addressing non-inflammatory or non-traumatic articular hip pain, using measures of muscle size and adiposity were included and appraised for risk of bias. Data was extracted to calculate standardised mean differences (SMD) and pooled where possible for meta-analysis.

RESULTS

Thirteen cross-sectional studies were included; all studies measured muscle size and 5/13 measured adiposity. In OA, there was low to very low quality evidence of no difference in hip muscle size, compared with matched controls. In unilateral OA, there was low to very low quality evidence of smaller size in gluteus minimus (SMD -0.38; 95% confidence interval (CI) -0.74, -0.01), gluteus medius (-0.44; 95% CI: -0.83, -0.05) and gluteus maximus (-0.39; 95% CI: -0.75, -0.02) muscles in the symptomatic limb. Individual studies demonstrated non-uniform changes in muscle size in OA. No significant difference was observed in muscle size in other pathologies or in adiposity for any group.

CONCLUSION

There is some low quality evidence that specific hip muscles are smaller in unilateral hip OA. Variation in the magnitude of differences indicate changes in size are not uniform across all muscles or stage of pathology. Studies in larger cohorts investigating muscle size and composition across the spectrum of articular pathologies are required to clarify these findings.

Targeted gluteal exercise versus sham exercise on self-reported physical function for people with hip osteoarthritis (the GHOst trial - Gluteal exercise for Hip Osteoarthritis): a protocol for a randomised clinical trial

BACKGROUND

Clinical practice guidelines recommend exercise as the first line of management for hip osteoarthritis, yet high-quality evidence from Cochrane reviews suggest only slight benefits for pain and physical function; and no benefit on quality of life (low-quality evidence). However, the scope of physical impairments identified in people with hip osteoarthritis may not have been adequately addressed with targeted rehabilitation options in previous randomised controlled trials (RCTs). Potential targeted options include gait retraining to address spatio-temporal impairments in walking; motor control training to address deep gluteal (gluteus minimus) dysfunction; and progressive, high-intensity resistance exercises to address atrophy of the gluteal muscles. The aim of this study is to investigate the effect of a targeted gluteal rehabilitation programme that incorporates gait retraining, motor control and progressive, high-intensity resistance-strength training, to address physical activity levels and self-reported physical function in people with mild to moderate disability from hip osteoarthritis.

METHODS

Ninety people diagnosed with mild to moderately disabling hip osteoarthritis will be recruited and randomised to receive one of two exercise programmes (sham or GHOst programme). Interventions will be 12 weeks in duration, with weekly, supervised physiotherapy sessions, and daily home exercises. Both groups will receive standardised education. Outcomes will be assessed at baseline, 7 weeks, 13 weeks (primary time-point) and 25 weeks. The primary outcome will be self-reported physical function measured with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Secondary outcomes include physical activity measured with a tri-axial accelerometer, physical function tests, self-reported physical activity, isometric hip-muscle strength tests, hip-related patient-reported outcome measures, pain thoughts and depressive symptoms, quality of life, global rating of change, gluteal-muscle activity (electromyography (EMG)) and gluteal-muscle size and adiposity (magnetic resonance imaging (MRI)).

DISCUSSION

This will be the first study to compare a targeted gluteal rehabilitation programme to a sham exercise programme. The targeted GHOst programme includes exercises designed to address gait impairments as well as gluteal-muscle atrophy and dysfunction.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry, ID: ACTRN12617000970347 . Registered retrospectively on 5 July 2017. Protocol version 3.0.

Sub-elite Football Players With Hip-Related Groin Pain and a Positive Flexion, Adduction, and Internal Rotation Test Exhibit Distinct Biomechanical Differences Compared With the Asymptomatic Side

Background Hip-related groin pain is common in sub-elite football players and may be associated with altered hip biomechanics. Objectives To compare the hip biomechanics, bony hip morphology associated with femoroacetabular impingement (FAI) syndrome, and hip strength and range of motion (ROM) between the symptomatic and asymptomatic limbs of sub-elite football players with unilateral hip-related groin pain and a positive flexion, adduction, and internal rotation (FADIR) test. Methods Fifteen sub-elite football (soccer) players with unilateral hip-related groin pain and a positive FADIR test were recruited for this observational cross-sectional study. Three-dimensional motion analysis and ground reaction force data were recorded for walking and a single-leg drop-jump (SLDJ) task. Participants also underwent a standard anterior-posterior hip radiograph and hip strength and ROM assessment. Between-limb differences were assessed using paired t tests or Wilcoxon signed-rank tests. Results The symptomatic limb displayed a smaller peak hip extension angle (P = .01) and a lower peak hip adduction moment (P = .03) compared with the asymptomatic limb during the stance phase of walking. Additionally, during the SLDJ, the symptomatic limb demonstrated less total sagittal plane ROM (P = .04). The symptomatic limb also demonstrated less external rotation ROM (P = .03). However, no differences were found between limbs for bony hip morphology associated with FAI syndrome or hip strength. Conclusion This study found between-limb asymmetries in low- and high-impact functional tasks, such as walking and an SLDJ, in football players with unilateral hip-related groin pain. Despite unilateral pain, bony morphology associated with FAI syndrome did not differ between limbs. J Orthop Sports Phys Ther 2018;48(7):584-593. Epub 8 May 2018. doi:10.2519/jospt.2018.7910.

Fat infiltration in the gluteus minimus muscle in older adults

Purpose

Fat infiltration (FI) in the gluteus minimus muscle (GMin) has been reported as being restricted to the anterior part. The aim of this study was to verify whether FI is localized only to the anterior part of the GMin through the dissection of large number of elderly cadavers and to clarify the underlying mechanism of FI localized to a specific region.

Materials and methods

Thirty-eight hips from 20 embalmed elder cadavers were dissected for verification of FI localization. The samples of three regions – the fat infiltrated region of the anterior part (FI), the region without FI (non-FI), and the posterior region – were harvested from nine hips for the histological fiber type assessment.

Results

The FI area was distributed at 2.6°–38° from the anterior border within the anterior part, of which function is responsible for hip extension and internal rotation and is likely reduced by disuse following aging. The number of type I fibers was lowest in FI, followed by non-FI, while the number of type I fibers was highest in the posterior. Meanwhile, the number of type II fibers was equivalent across the three regions. Atrophic type II fibers were observed in overall samples of the three regions, and grouped atrophy, which is evidence of denervation, was observed in FI and non-FI samples. Type grouping, which suggests to be reinnervated, was found in the non-FI and posterior samples but very little in the FI samples.

Conclusion

FI in the GMin in older adults restricted to deep within the anterior part is secondary to disuse and is strongly related to impaired denervation–reinnervation process.

Adductor magnus: An EMG investigation into proximal and distal portions and direction specific action

Cadaveric studies indicate that adductor magnus is structurally partitioned into at least two regions. The aim of this study was to investigate the direction-specific actions of proximal and distal portions of adductor magnus, and in doing so determine if these segments have distinct functional roles. Fine-wire EMG electrodes were inserted into two portions of adductor magnus of 12 healthy young adults. Muscle activity was recorded during maximum voluntary isometric contractions (MVICs) across eight tests (hip flexion/extension, internal/external rotation, abduction, and adduction at 0°, 45°, and 90° hip flexion). Median activity within each action (normalized to peak) was compared between segments using repeated measures nonparametric tests (α = 0.05). An effect size (ES = z-score/√sample size) was calculated to determine the magnitude of difference between muscle segments. The relative contribution of each muscle segment differed significantly during internal rotation (P < 0.001; ES = 0.88) and external rotation (P = 0.003, ES = 0.79). The distal portion was most active during extension [median (interquartile range); 100(0)% MVIC)] and internal rotation [58(34)% MVIC]. The proximal portion was most active during extension [100(49)% MVIC] and adduction [59(64)%MVIC], with low level activity during external rotation [15(41)%MVIC]. This study suggests that adductor magnus has at least two functionally unique regions. Differences were most evident during rotation. The different direction-specific actions may imply that each segment performs separate roles in hip stability and movement. These findings may have implications on injury prevention and rehabilitation for adductor-related groin injuries, hamstring strain injury, and hip pathology. Clin. Anat. 31:535-543, 2018. © 2018 Wiley Periodicals, Inc.

Atrophy of hip abductor muscles is related to clinical severity in a hip osteoarthritis population

Osteoarthritis mainly affects weight-bearing joints such as the hip and knee and is the most common form of arthritis. Greater muscle atrophy with fatty infiltration of gluteal muscles and decreased hip abduction strength has previously been identified with increasing severity of radiological hip OA. However, it is well documented that radiographic findings of OA do not always correlate with clinical severity. The aim of this secondary analysis was to examine whether atrophy and strength of gluteus maximus (GMax), medius (GMed), minimus (GMin), and tensor fascia lata (TFL) is associated with the clinical severity of OA. Twenty participants with unilateral hip OA and 20 age- and sex-matched asymptomatic controls were classified on the basis of clinical severity (mild, moderate-severe and asymptomatic groups) using the Oxford hip score. Muscle volumes of GMax, GMed, GMin, and TFL were determined using magnetic resonance imaging and expressed as asymmetry between limbs. A hand-held dynamometer was used to identify hip rotation and abduction strength. Regression analyzes were used to identify the association between muscle asymmetry and patient-reported severity of hip OA. Both symptomatic groups (mild and moderate-severe) demonstrated significant asymmetry in GMax (P < 0.01) and GMin (P < 0.01). GMed asymmetry was associated with only the moderate-severe symptomatic group. Hip abduction strength was reduced in both symptomatic groups. Gluteal muscle atrophy was associated with the clinical severity of OA. Clinical severity could be a useful tool for clinicians interpreting likely gluteal muscle changes and planning rehabilitation strategies for hip OA patients. Clin. Anat. 31:507-513, 2018. © 2018 Wiley Periodicals, Inc.

Lower limb biomechanics in femoroacetabular impingement syndrome: a systematic review and meta-analysis

Objective

(1) Identify differences in hip and pelvic biomechanics in patients with femoroacetabular impingement syndrome (FAIS) compared with controls during everyday activities (eg, walking, squatting); and (2) evaluate the effects of interventions on hip and pelvic biomechanics during everyday activities.

Design

Systematic review.

Data sources

Medline, CINAHL, EMBASE, Scopus and SPORTDiscus until February 2017.

Methods

Primary aim: studies that investigated hip or pelvic kinematics and/or joint torques of everyday activities in patients with FAIS compared with the asymptomatic contralateral limb or a control group. Secondary aim: studies that evaluated effects of conservative or surgical interventions on patients with FAIS using pre-post or controlled clinical trial designs. Biomechanical data must have been collected using three-dimensional motion capture devices. Reporting quality was assessed using the Epidemiological Appraisal Instrument and data were pooled (standardised mean difference (SMD), 95% CI) where populations and primary outcomes were similar.

Results

Fourteen studies were included (11 cross-sectional and three pre/post intervention), varying between low and moderate reporting quality. Patients with FAIS walked with a lower: peak hip extension angle (SMD −0.40, 95% CI −0.71 to −0.09), peak internal rotation angle (−0.67, 95% CI −1.19 to −0.16) and external rotation joint torque (−0.71, 95% CI −1.07 to −0.35), and squatted to a lesser depth with no difference in hip flexion range. Pre/post intervention data were limited in number and quality, and to surgical cohorts.

Conclusion

This review suggests that patients with FAIS may demonstrate hip biomechanical impairments during walking and squatting, with minimal literature available to comment on other tasks.

Clinical relevance

The information presented in the review provides insight into the biomechanical differences associated with FAIS; however, the between-group differences were small to moderate. This information may aid in the development of management strategies for people with the condition.

PROSPEROregistration number

CRD42016038677.

Gluteal muscle damage leads to higher in vivo hip joint loads 3 months after total hip arthroplasty

Background

Total hip arthroplasty (THA) is in most cases improving patients´ life quality immediately after surgery. However, a closer look at these patients, especially with modern gait analysis methods, reveals also negative consequences due to the surgical approach related injury to the pelvic muscles. We hypothesized that this damage will have a negative impact on hip joint contact forces during activities of daily living (ADL).

Methods

10 patients undergoing THA received an instrumented hip joint implant enabling real time in vivo measurements of hip joint loads using a direct lateral approach. Pre- and 3 months postoperative computed tomography (CT) scans were used for evaluation of the periarticular muscle status, using muscle volume, fat ratio and lean muscle volume as parameters. An analysis of in vivo hip contact forces was made 3 months after THA during ADL (walking, stair climbing, chair rising and sitting) and correlated with the morphology of the periarticular muscles.

Results

We found a significant decrease of volume by 25% (-3 to -45, p = 0.005) and increase in fat ratio of the Gluteus Minimus (Gmin), resulting in a decrease in lean muscle volume of 28% (-48 to 0, p = 0.008). This was accompanied by an inverse development in the Tensor Fasciae Latae (TFL) resulting in a lean muscle volume increase of 34% (-2 to -102, p = 0.013). Changes in Gluteus Medius (Gmed) and Gluteus Maximus (Gmax) have not been observed in the short-term follow up. A decreased Gmin lean muscle volume was found to strongly correlate with high in vivo joint contact forces in all tested ADL.

Conclusion

The decrease of Gmin volume can be seen as a direct effect of THA surgery, whereas the increase of TFL might compensate for loss of Gmin volume. Lean muscle volume and fat ratio were better predictors for joint contact forces than total muscle volume. These effects were most pronounced during sitting down and standing up due to the higher demand on the gluteal muscles during these activities.

Gluteus Minimus and Gluteus Medius Muscle Activity During Common Rehabilitation Exercises in Healthy Postmenopausal Women

Study Design Controlled laboratory study, cross-sectional. Background The gluteus medius (GMed) and gluteus minimus (GMin) provide dynamic stability of the hip joint and pelvis. These muscles are susceptible to atrophy and injury in individuals during menopause, aging, and disease. Numerous studies have reported on the ability of exercises to elicit high levels of GMed activity; however, few studies have differentiated between the portions of the GMed, and none have examined the GMin. Objectives To quantify and rank the level of muscle activity of the 2 segments of the GMin (anterior and posterior fibers) and 3 segments of the GMed (anterior, middle, and posterior fibers) during 4 isometric and 3 dynamic exercises in a group of healthy, postmenopausal women. Methods Intramuscular electrodes were inserted into each segment of the GMed and GMin in 10 healthy, postmenopausal women. Participants completed 7 gluteal rehabilitation exercises, and average normalized muscle activity was used to rank the exercises from highest to lowest. Results The isometric standing hip hitch with contralateral hip swing was the highest-ranked exercise for all muscle segments except the anterior GMin, where it was ranked second. The highest-ranked dynamic exercise for all muscle segments was the dip test. Conclusion The hip hitch and its variations maximally activate the GMed and GMin muscle segments, and may be useful in hip muscle rehabilitation in postmenopausal women. J Orthop Sports Phys Ther 2017;47(12):914-922. Epub 15 Oct 2017. doi:10.2519/jospt.2017.7229.

Does hip joint positioning affect maximal voluntary contraction in the gluteus maximus, gluteus medius, tensor fasciae latae and sartorius muscles?

BACKGROUND

Minimally invasive total hip arthroplasty (THA) is presumed to provide functional and clinical benefits, whereas in fact the literature reveals that gait and posturographic parameters following THA do not recover values found in the general population. There is a significant disturbance of postural sway in THA patients, regardless of the surgical approach, although with some differences between approaches compared to controls: the anterior and anterolateral minimally invasive approaches seem to be more disruptive of postural parameters than the posterior approach. Electromyographic (EMG) study of the hip muscles involved in surgery [gluteus maximus (GMax), gluteus medius (GMed), tensor fasciae latae (TFL), and sartorius (S)] could shed light, the relevant literature involves discordant methodologies. We developed a methodology to assess EMG activity during maximal voluntary contraction (MVC) of the GMax, GMed, TFL and sartorius muscles as a reference for normalization. A prospective study aimed to assess whether hip joint positioning and the learning curve on an MVC test affect the EMG signal during a maximal voluntary contraction.

HYPOTHESIS

Hip positioning and the learning curve on an MVC test affect EMG signal during MVC of GMax, GMed, TFL and S.

METHODS

Thirty young asymptomatic subjects participated in the study. Each performed 8 hip muscle MVCs in various joint positions recorded with surface EMG sensors. Each MVC was performed 3 times in 1 week, with the same schedule every day, controlling for activity levels in the preceding 24h. EMG activity during MVC was expressed as a ratio of EMG activity during unipedal stance. Non-parametric tests were applied.

RESULTS

Statistical analysis showed no difference according to hip position for abductors or flexors in assessing EMG signal during MVC over the 3 sessions. Hip abductors showed no difference between abduction in lateral decubitus with hip straight versus hip flexed: GMax (19.8±13.7 vs. 14.5±7.8, P=0.78), GMed (13.4±9.0 vs. 9.9±6.6, P=0.21) and TFL (69.5±61.7 vs. 65.9±51.3, P=0.50). Flexors showed no difference between hip flexion/abduction/lateral rotation performed in supine or sitting position: TFL (70.6±45.9 vs. 61.6±45.8, P=0.22) and S (101.1±67.9 vs. 72.6±44.6, P=0.21). The most effective tests to assess EMG signal during MVC were for the hip abductors: hip abduction performed in lateral decubitus (36.7% for GMax, 76.7% for GMed), and for hip flexors: hip flexion/abduction/lateral rotation performed in supine decubitus (50% for TFL, 76.7% for S).

DISCUSSION

The study hypothesis was not confirmed, since hip joint positioning and the learning curve on an MVC test did not affect EMG signal during MVC of GMax, GMed, TFL and S muscles. Therefore, a single session and one specific test is enough to assess MVC in hip abductors (abduction in lateral decubitus) and flexors (hip flexion/abduction/lateral rotation in supine position). This method could be applied to assess muscle function after THA, and particularly to compare different approaches.

LEVEL OF EVIDENCE

III, case-matched study.

Estimates of individual muscle power production in normal adult walking

Background

The purpose of this study was to determine the contribution of individual hip muscles to the net hip power in normal adult self-selected speed walking. A further goal was to examine each muscle’s role in propulsion or support of the body during that task.

Methods

An EMG-to-force processing (EFP) model was developed which scaled muscle-tendon unit (MTU) force output to gait EMG. Active muscle power was defined as the product of MTU forces (derived from EFP) and that muscle’s contraction velocity. Passive hip power was estimated from passive moments associates with hip position (angle of flexion (extension)) and the hip’s angular velocity. Net hip EFP power was determined by summing individual active hip muscle power plus the net passive hip power at each percent gait cycle interval. Net hip power was also calculated for these study participants via inverse dynamics (kinetics plus kinematics, KIN). The inverse dynamics technique – well accepted in the biomechanics literature – was used as a “gold standard” for validation of this EFP model. Closeness of fit of the power curves of the two methods was used to validate the model.

Results

The correlation between the EFP and KIN methods was sufficiently close, suggesting validation of the model’s ability to provide reasonable estimates of power produced by individual hip muscles. Key findings were that (1) most muscles undergo a stretch-shorten cycle of muscle contraction, (2) greatest power was produced by the hip abductors, and (3) the hip adductors contribute to either hip adduction or hip extension (but not both).

Conclusions

The EMG-to-force processing approach provides reasonable estimates of individual hip muscle forces in self-selected speed walking in neurologically-intact adults.

Hip abductor muscle volume in hip osteoarthritis and matched controls

OBJECTIVE

Hip abductor muscle strength and function is negatively impacted by the presence of hip osteoarthritis (OA). This study aimed to quantify differences in hip abductor muscle volume, fatty infiltration and strength in a unilateral hip OA population when compared to a control group. Impact of radiographic severity of OA on these variables was also examined.

METHODS

Volumes of gluteus maximus (GMax), medius (GMed) minimus (GMin) and tensor fascia lata (TFL) was measured using MRI and muscle volume asymmetry between limbs was calculated. Fatty infiltrate within muscles was graded using the Goutallier classification system. Hip abduction and rotation strength was tested using a dynamometer. Differences between groups or limbs were analysed using t-tests and differences in fatty infiltration using non-parametric tests.

RESULTS

A statistically significant decrease in muscle volume was identified in GMax (P < 0.01), GMed (P < 0.02) and GMin (P < 0.01) on the affected side in the OA group compared to both the contralateral side and the control group and differences were related to severity of OA. Hip abduction and internal rotation strength was reduced in the OA group. Increased levels of fatty infiltration were identified in the affected limbs of the OA group for GMax (P = 0.01) and GMin (P = 0.04).

CONCLUSION

Gluteal muscle atrophy, increased gluteal fatty infiltration and hip strength deficits were evident in the affected hips of OA participants. Since severity of OA was related to the extent of atrophy and fatty deposits, rehabilitation programs targeting these muscles could reverse or halt the progression of these structural and functional deficits.

Hip Strength Deficits in People With Symptomatic Knee Osteoarthritis: A Systematic Review With Meta-analysis

Study Design Systematic review with meta-analysis. Background A complete understanding of impairments associated with knee osteoarthritis would optimize exercise interventions for people with knee osteoarthritis. Our current understanding of hip strength deficits in this population is based on studies with conflicting findings and small samples. There is a need to systematically review and pool current evidence. Objectives To determine whether hip strength deficits exist in people with symptomatic knee osteoarthritis. Methods Electronic databases (MEDLINE, CINAHL, Embase, the Cochrane Library, and PsycINFO) were searched through February 2016. Studies comparing hip strength in people diagnosed with symptomatic knee osteoarthritis to healthy control participants were included in the review. A meta-analysis with random effects was applied to relevant data from included studies and a modified Grading of Recommendations Assessment, Development and Evaluation approach was used to evaluate the quality of evidence for each pooled analysis. Results Five studies were included in the review. Meta-analysis revealed moderate-quality evidence of weaker isometric and isokinetic hip abduction strength in people with knee osteoarthritis (moderate difference: 7% to 24% weaker) and very low-quality evidence of no difference in isometric hip adduction strength. There was very low- to moderate-quality evidence of weaker isokinetic hip strength in the remaining planes of motion (moderate to large differences: 14% to 55% weaker). Conclusion Significant hip strength deficits exist in people with knee osteoarthritis. Hip strength assessment should be considered in clinical practice and may assist with directing targeted management strategies. Level of Evidence Symptom prevalence, level 1a-. J Orthop Sports PhysTher 2016;46(8):629-639. Epub3 Jul 2016. doi:10.2519/jospt.2016.6618.

M-Mode Ultrasound Reveals Earlier Gluteus Minimus Activity in Individuals With Chronic Hip Pain During a Step-down Task

STUDY DESIGN

Controlled laboratory study.

BACKGROUND

The hip abductor muscles are important hip joint stabilizers. Hip joint pain may alter muscle recruitment. Motion-mode (M-mode) ultrasound enables noninvasive measurements of the onset of deep and superficial muscle motion, which is associated with activation onset.

OBJECTIVES

To compare (1) the onset of superficial and deep gluteus medius and gluteus minimus muscle motion relative to the instant of peak ground reaction force and (2) the level of swing-phase muscle motion during step-down between subjects with chronic hip pain and controls using M-mode ultrasound.

METHODS

Thirty-five subjects with anterior, nontraumatic hip pain for more than 6 months (mean ± SD age, 54 ± 9 years) and 35 controls (age, 57 ± 7 years) were scanned on the lateral hip of the leading leg during frontal step-down onto a force platform using M-mode ultrasound. Computerized motion detection with the Teager-Kaiser energy operator was applied on the gluteus minimus and the deep and superficial gluteus medius to determine the time lag between muscle motion onset and instant of peak ground reaction force and the level of gluteus minimus motion during the swing phase. Time lags and motion levels were averaged per subject, and t tests were used to determine between-group differences.

RESULTS

In participants with hip pain, gluteus minimus motion onset was 103 milliseconds earlier (P = .002) and superficial gluteus medius motion was 70 milliseconds earlier (P = .047) than those in healthy control participants. The level of gluteus minimus swing-phase motion was higher with pain (P = .006).

CONCLUSION

Increased gluteus minimus motion during the swing phase and earlier gluteus minimus and superficial gluteus medius motion in individuals with hip pain suggest an overall increase of muscle activity, possibly a protective behavior.

Kinematics and kinetics during walking in individuals with gluteal tendinopathy

BACKGROUND

Lateral hip pain during walking is a feature of gluteal tendinopathy but little is known how walking biomechanics differ in individuals with gluteal tendinopathy. This study aimed to compare walking kinematics and kinetics between individuals with and without gluteal tendinopathy.

METHODS

Three-dimensional walking-gait analysis was conducted on 40 individuals aged 35 to 70 years with unilateral gluteal tendinopathy and 40 pain-free controls. An analysis of covariance was used to compare kinematic and kinetic variables between groups. Linear regression was performed to investigate the relationship between kinematics and external hip adduction moment in the gluteal tendinopathy group.

FINDINGS

Individuals with gluteal tendinopathy demonstrated a greater hip adduction moment throughout stance than controls (standardized mean difference ranging from 0.60 (first peak moment) to 0.90 (second peak moment)). Contralateral trunk lean at the time of the first peak hip adduction moment was 1.2 degrees greater (P=0.04), and pelvic drop at the second peak hip adduction moment 1.4 degrees greater (P=0.04), in individuals with gluteal tendinopathy. Two opposite trunk and pelvic strategies were also identified within the gluteal tendinopathy group. Contralateral pelvic drop was significantly correlated with the first (R=0.35) and second peak (R=0.57) hip adduction moment, and hip adduction angle with the second peak hip adduction moment (R=-0.36) in those with gluteal tendinopathy.

INTERPRETATION

Individuals with gluteal tendinopathy exhibit greater hip adduction moments and alterations in trunk and pelvic kinematics during walking. Findings provide a basis to consider frontal plane pelvic control in the management of gluteal tendinopathy.

Quadratus femoris: An EMG investigation during walking and running

Dysfunction of hip stabilizing muscles such as quadratus femoris (QF) is identified as a potential source of lower extremity injury during functional tasks like running. Despite these assumptions, there are currently no electromyography (EMG) data that establish the burst activity profile of QF during any functional task like walking or running. The objectives of this study were to characterize and compare the EMG activity profile of QF while walking and running (primary aim) and describe the direction specific action of QF (secondary aim). A bipolar fine-wire intramuscular electrode was inserted via ultrasound guidance into the QF of 10 healthy participants (4 females). Ensemble curves were generated from four walking and running trials, and normalized to maximum voluntary isometric contractions (MVICs). Paired t-tests compared the temporal and amplitude EMG variables. The relative activity of QF in the MVICs was calculated. The QF displayed moderate to high amplitude activity in the stance phase of walking and very high activity during stance in running. During swing, there was minimal QF activity recorded during walking and high amplitudes were present while running (run vs walk effect size=4.23, P<0.001). For the MVICs, external rotation and clam produced the greatest QF activity, with the hip in the anatomical position. This study provides an understanding of the activity demands placed on QF while walking and running. The high activity in late swing during running may signify a synergistic role with other posterior thigh muscles to control deceleration of the limb in preparation for stance.