Abductor Muscles Research Articles

Hip width and metabolic energy expenditure of abductor muscles.

Despite a paucity of physiological evidence, simplistic biomechanical analyses have led researchers to assume that humans who have wider hips use more energy to walk. Pitting biomechanical first principles against physiological data has led to little deepening of our understanding of bipedalism and its evolution. Both approaches, however, use proxies for the energy used by muscles. We decided to approach the question directly. Using a musculoskeletal model of the human body that estimates the metabolic energy expenditure of muscle activation for 48 people (23 women), 752 trials were evaluated. Metabolic energy consumption for the abductor muscles was summed over a stride to create total abductor energy expenditure. We calculated the maximum hip joint moment acting in the coronal plane and the functional distance between the hip joint centers. We hypothesize that wider hips would be correlated with both maximum coronal plane hip moment and increased total abductor energy expenditure when mass and velocity were controlled. Linear regressions with multiple independent variables, clustered by participant to control for the non-independence of the data points, were performed in Stata. We found that hip width does not predict total abductor energy expenditure, although mass and velocity combine to predict 61% of the variation (both p<0.001). Maximum hip joint coronal plane moment is predicted by pelvic width (p<0.001) and, in combination with mass and velocity (both p<0.001), explains 79% of the variation. Our results indicate that people use their morphology in ways that limit differences in energy expenditure. Consistent with recent discussion, intraspecific variation might not be useful to understand differences among species.

Abductor muscle function after anterolateral approach in patients with unilateral end-stage hip osteoarthritis undergoing total hip arthroplasty: A prospective study.

Total hip arthroplasty (THA) is a successful procedure for treating end-stage hip osteoarthritis (OA). Regarding the surgical approach for THA, the anterolateral (AL) approach, which requires anterior hemimyotomy of the gluteus medius muscle, has shown a long-term favorable outcome. However, to date, complete information related to hip abductor muscle outcomes after the AL approach is unavailable. This study therefore aimed to evaluate the postoperative outcome of patients who undergo THA using the AL approach in terms of hip abductor muscle recovery, pain, function, and muscle healing status. Twenty patients diagnosed with unilateral end-stage hip OA underwent cementless THA with the AL approach. All patient procedures were performed by a single surgeon. Preoperative and postoperative data were collected at 2-week, 6-week, 3-month, and 6-month follow-up periods. Hip abductor muscle power was measured via handheld dynamometer. The healing of the musculotendinous repair was evaluated with magnetic resonance imaging at 9 months. After THA, hip abductor muscle power in the operated hip significantly increased as early as 3 months post-procedure when compared with the preoperative value (p < 0.05). The other parameters-including pain score, Harris hip score, and WOMAC score-significantly improved as early as 2 weeks post-operation (p < 0.05). In all patients, MRI scans showed good healing of the muscle repair site without a gap in the gluteus medius muscle. However, three patients (15%) had some fibrosis and tendon swelling at the repair site. This study demonstrated that patients with end-stage hip OA could experience significantly improved hip abductor motor function as early as 3 months after undergoing THA with the AL approach. Moreover, despite patients experiencing anterior hemimyotomy of the gluteus medius muscle, no significant complications emerged at the muscle repair site in the AL approach.

Effects of Motor-Cognitive Dual-Task Standing Balance Exergaming Training on Healthy Older Adults' Standing Balance and Walking Performance.

Objective: This study examined the effects of motor-cognitive dual-task exergaming standing balance training on healthy older adults' static, dynamic, and walking balance. Methods: Twenty-four adults older than 70 years (control group: n = 9, males = 6, balance training group: n = 15, males = 8) completed the experiment. Dual-tasking standing balance training comprised the accurate control of a ping-pong ball on a tray held with both hands, while standing on one leg (analog training) and three modules of Wii Fit™ exergaming (digital training). The duration of balance training was ∼15 minutes per day, 2 days per week for 8 weeks, in total 16 sessions. We measured one-leg standing time, functional reach distance, walking balance evaluated by the distance walked on a narrow beam (4-cm long, 4-cm wide, and 2-cm high) with single and dual tasking, habitual and maximal walking speed, and muscle strength of the hip extensor, hip abductor, hip adductor, knee extensor, and plantarflexor muscle groups in the right leg at baseline and after 8 weeks. Results: Control group decreased, but balance training group increased one-leg standing time. Only the balance training group improved functional reach distance and hip and knee extensor strength. There was no change in walking speed and walking balance in either group. In the balance training group, changes in maximal speed correlated with changes in dual-tasking walking balance and changes in one-leg standing time correlated with changes in single-tasking walking balance. Conclusion: These results suggest that 16 sessions of motor-cognitive dual-task standing exergaming balance training substantially improved healthy older adults' static and dynamic balance and leg muscle strength but failed to improve walking speed and walking balance. Balance exercises specific to walking balance need to be included in balance training to improve walking balance.

Clinical utilisation of multimodal quantitative magnetic resonance imaging in investigating muscular damage in Duchenne muscular dystrophy: a study on the association between gluteal muscle groups and motor function

BackgroundDuchennemuscular dystrophy (DMD) is a neuromuscular disease characterised by progressive muscular weakness and atrophy. Currently, studies on DMD muscle function mostly focus on individual muscles; little is known regarding the effect of gluteal muscle group damage on motor function.ObjectiveTo explore potential imaging biomarkers of hip and pelvic muscle groups for measuring muscular fat replacement and inflammatory oedema in DMD with multimodal quantitative magnetic resonance imaging (MRI).Materials and methodsOne hundred fifty-nine DMD boys and 32 healthy male controls were prospectively included. All subjects underwent MRI examination of the hip and pelvic muscles with T1 mapping, T2 mapping and Dixon sequences. Quantitatively measured parameters included longitudinal relaxation time (T1), transverse relaxation time (T2) and fat fraction. Investigations were all based on hip and pelvic muscle groups covering flexors, extensors, adductors and abductors. The North Star Ambulatory Assessment and stair climbing tests were used to measure motor function in DMD.ResultsT1 of the extensors (r = 0.720, P < 0.01), flexors (r = 0.558, P < 0.01) and abductors (r = 0.697, P < 0.001) were positively correlated with the North Star Ambulatory Assessment score. In contrast, T2 of the adductors (r = -0.711, P < 0.01) and fat fraction of the extensors (r = -0.753, P < 0.01) were negatively correlated with the North Star Ambulatory Assessment score. Among them, T1 of the abductors (b = 0.013, t = 2.052, P = 0.042), T2 of the adductors (b = -0.234, t = -2.554, P = 0.012) and fat fraction of the extensors (b = -0.637, t = − 4.096, P < 0.001) significantly affected the North Star Ambulatory Assessment score. Moreover, T1 of the abductors was highly predictive for identifying motor dysfunction in DMD, with an area under the curve of 0.925.ConclusionMagnetic resonance biomarkers of hip and pelvic muscle groups (particularly T1 values of the abductor muscles) have the potential to be used as independent risk factors for motor dysfunction in DMD.

Assessment of the Damage to Hip Abductor Muscles in Primary Total Hip Arthroplasty With a Minimally Invasive Anterolateral Approach With or Without Trochanteric Flip Osteotomy

BackgroundAlthough introduction of minimally invasive techniques via anterolateral approaches considerably decreased prolonged limp after total hip arthroplasty (THA), potential damage to the abductor muscles is still a concern. This study aimed to evaluate the residual damage after primary THA with two types of anterolateral approach by assessing fatty infiltration and atrophy of the gluteus medius (GMed) and gluteus minimus (GMin) muscles. MethodsWe retrospectively analyzed 100 primary THAs using computed tomography; surgeries were performed by detaching the anterior part of the abductor muscles with a bone fragment (anterolateral approach with trochanteric flip osteotomy) or without it (anterolateral approach without trochanteric flip osteotomy). The change in radiodensities (RDs), cross-sectional areas (CSAs), and clinical scores preoperatively and at 1 year after operation were evaluated. ResultsThe RD and CSA of GMed increased 1 year postoperatively in 86 and 81% of patients, respectively, while RD and CSA of GMin decreased in 71 and 94%, respectively. The improvement of RD of GMed was more frequently seen in the posterior rather than the anterior part, while the GMin decreased in both parts. The RD decrease of GMin was significantly lower in the anterolateral approach with trochanteric flip osteotomy group than the anterolateral approach without trochanteric flip osteotomy group (P = .0250). However, there was no difference in the clinical scores between the two groups. The change in the RD of GMed was the only factor that correlated with clinical scores. ConclusionThe two anterolateral approaches both improved the RD of GMed, recovery of which was significantly associated with postoperative clinical scores. Although the two approaches showed different recovery patterns in GMin until 1 year after THA, both showed similar improvements in clinical scores.

Hip Joint Instability After Surgery Performed Through the Surgical Dislocation Approach.

Safe surgical dislocation of the hip is a versatile approach to the hip joint with a low complication rate. Hip joint instability is a devastating complication with poor prognosis. All hips treated surgically through the safe surgical dislocation approach were entered in a database and the complication of hip joint instability was studied prospectively from 2000 to 2021. Instability was diagnosed by intraoperative stress examination and on postoperative radiographs. The initial deformities treated, type of instability, presumed causes, treatment provided, response to the treatment, and final result were recorded as they happened during the course of the treatment. We considered patient's age, sex, body mass index (BMI), and initial diagnosis as risk factors. We evaluated the radiographs for femoral neck shortening, lack of greater trochanteric advancement, acetabular deformity, and incongruity of the hip joint. Anterior hip precautions were initiated in the middle of the study period. 22/459 hips developed hip joint instability after surgical dislocation approach performed for hip preservation. Acetabular deficiency, coxa breva, coxa valga, posterior impingement, increased anteversion, lax soft tissues, medial thigh obesity and lack of postoperative precautions seemed to contribute to instability. 50% of the hips became normal. Chondrolysis and residual subluxation were common in the others. Surgical dislocation approach disrupts the soft tissue restraints of the hip and joint stability depends on bony morphology, abductor muscle tension, and postoperative precautions. Several risk factors were subjective and speculative, but awareness of all the potential risk factors and prevention and treatment options should decrease this complication. IV Case series.

Analysis of the adductors and abductors' maximum isometric strength on the level of speed and agility in basketball players

Introduction: his study investigated the relationship between hip abductor strength (Abd), adductor strength (Add), straight accelerations and decelerations, and during changes of direction (COD 90°) performance in basketball players. Material and Methods: Fourteen basketball players participated (age = 23.6 ± 4.4 years, body mass = 86.3 ± 5.9 kg, body height = 192.3 ± 6.2 cm, training experience = 6.7 ± 2.6 years). Straight running results and running with a change of direction (COD 90°) have been described as the time (s) obtained for a given length. Following tests were carried out: maximum isometric strength test, 20-m linear sprint and 20-m COD sprint with 90° direction change angles. Following the warm-up, all athletes performed two maximal 20-m linear sprints, interspersed with 5 min rest intervals. Following the 20-m linear sprint test, the participants were provided with a 5 min rest interval before completing the COD tests. Additionally, the balance in isometric strength of the dominant and non-dominant hip Abd-Add muscles were evaluated. Two maximum attempts interspersed with one-minute rest intervals were performed. Results: The t-test revealed statistically significant higher absolute and relative isometric strength of AddR (adductor right) in comparison to AddL (adductor left). Conclusion: The results of this study show that the maximum isometric force and the relative strength of the abductor muscle group have a significant effect on changing direction running. Moreover, hip Abd and Add are typical for strength bilateral strength imbalances. Therefore, the evaluation and development of these qualities are essential for coaches to monitor and prescribe adequate training regimens.

Management of Secondary Osteoarthritis with Proximal Femoral Deformity due to Previous Coxitis Hip – A case report

IntroductionMost proximal femoral deformities encountered during hip arthroplasty are secondary to degenerative processes, previous osteotomy, or fracture and could be a challenged for surgeons. Femoral deformity may be angular, rotational, or one of bone diameter or length. Fully understanding the anatomy of the deformity is the first element in deciding how to best treat the deformity during Total Hip Arthroplasty (THA). Presentation of CaseFemale 31 years old complaint of pain on her left hip with restricted motion, with a leg length discrepancy (LLD) of 2 cm and a history of operation due to left hip infection when she was a baby. THA was performed with carefully evaluating the abductor muscle to maintain hip stability. Postoperatively the patient has an equal leg length, with less pain on the hip, a good ROM, and able to walk dependently using a cane. Slight tightness on the abductor and adductor muscle was noted postoperatively and the patient undergone physiotherapy. DiscussionMultiple important factor must be considered before considering THA in patients with proximal femoral deformity, including abductor function, osseous anatomy, hip stability and LLD. One must be careful of correction of LLD greater than 3 cm because possible effect on abductor strength, hip stability and sciatic nerve function. In this case, we demonstrated that a successful THA can be achieved despite altered anatomy due to secondary developmental changes. ConclusionIn the setting of sufficient abductor strength and bony stock amenable to implant fixation, THA is a viable option for management and careful preoperative planning helps predict prosthesis requirements and technical challenges. KeywordsOsteoarthritis, Proximal Femoral Deformities, Total Hip Arthroplasty, Abductor Muscle

Increased femoral anteversion may not cause hip abductor muscle weakness during walking

Increased femoral anteversion may not cause hip abductor muscle weakness during walking

Effects of orthoses on muscle activity and synergy during gait.

An orthosis is often used in rehabilitation to improve kinetic and kinematic parameters during gait. However, whether changes in neural control depend on wearing an orthosis during gait is unclear. We measured the muscle activity and synergy of the lower limb muscles without orthosis and with two types of orthoses: ankle-foot orthosis (AFO) and knee-ankle-foot orthosis (KAFO). Muscle activity during gait was measured in 15 healthy adults, and muscle synergies were extracted using non-negative matrix factorization. The results revealed that some muscle activities were significantly different among the three conditions. Post-hoc analysis indicated differences between each condition. Knee extensor muscle activity related to the loading response was significantly increased by wearing the AFO. In the KAFO condition, hip abductor muscle activity related to weight bearing was significantly decreased, and ankle dorsiflexor muscle activity was increased to secure clearance during the swing phase. However, the number of muscle synergies and complexity of muscle synergy did not significantly change among these conditions. However, along with changes in muscle activity, the activation pattern and weightings of muscle synergies tended to change with the use of orthoses. Each muscle activity was changed by wearing the orthosis; however, the immediate mechanical constraint did not change the framework of muscle synergy.

Protocol for a Randomized Crossover Trial to Evaluate the Effect of Soft Brace and Rigid Orthosis on Performance and Readiness to Return to Sport Six Months Post-ACL-Reconstruction.

A randomized crossover trial was designed to investigate the influence of muscle activation and strength on functional stability/control of the knee joint, to determine whether bilateral imbalances still occur six months after successful anterior cruciate ligament reconstruction (ACLR), and to analyze whether the use of orthotic devices changes the activity onset of these muscles. Furthermore, conclusions on the feedforward and feedback mechanisms are highlighted. Therefore, twenty-eight patients will take part in a modified Back in Action (BIA) test battery at an average of six months after a primary unilateral ACLR, which used an autologous ipsilateral semitendinosus tendon graft. This includes double-leg and single-leg stability tests, double-leg and single-leg countermovement jumps, double-leg and single-leg drop jumps, a speedy jump test, and a quick feet test. During the tests, gluteus medius and semitendinosus muscle activity are analyzed using surface electromyography (sEMG). Motion analysis is conducted using Microsoft Azure DK and 3D force plates. The tests are performed while wearing knee rigid orthosis, soft brace, and with no aid, in random order. Additionally, the range of hip and knee motion and hip abductor muscle strength under isometric conditions are measured. Furthermore, patient-rated outcomes will be assessed.

Enhanced phasic sensory afferents paired with controlled constraint force improve weight shift toward the paretic side in individuals post-stroke

PurposeThe goal of this study was to determine whether enhanced phasic sensory afferent input paired with the application of controlled constraint force during walking would improve weight shift toward the paretic side and enhance use of the paretic leg. MethodsFourteen stroke survivors participated in two experimental conditions, sessions that consisted of 1 min treadmill walking without force and stimulation (baseline), 7 min walking with either “constraint force and sensory stimulation (constraint+stim)” or “constraint force only (constraint)” (adaptation), and then 2 min walking without force and stimulation (post-adaptation). Kinematics of the pelvis and legs, and muscle activity of the paretic leg were recorded. ResultsParticipants showed greater increases in hip abductor (p < 0.001) and adductor (p = 0.04) muscle activities, weight shift toward the paretic side (p = 0.002), and step length symmetry (p < 0.01) during the late post-adaptation period in the “constraint+stim” condition, compared with the effect of the “constraint” condition. In addition, changes in overground walking speed from baseline to 10 min post treadmill walking was significantly greater for the “constraint force and stimulation” condition than for the “constraint force only” condition (p = 0.04). ConclusionEnhanced targeted sensory afferent input during locomotor training may facilitate recruitment of targeted muscles of the paretic leg and facilitate use-dependent motor learning of locomotor tasks, which might retain longer and partially transfer from treadmill to overground walking, in stroke survivors.

Age estimation of puppies based on the radiographically assessed development of ossification centres in the carpal and metacarpal regions.

The need for proper age determination in puppies has increased enormously due to the growing illegal trade in puppies that are too young to be removed from the litter or too young to have been properly vaccinated against rabies. Dorsopalmar and mediolateral radiographs of the (meta)carpal region, either taken from puppy cadavers or from the Faculty's patient database, were studied in a cross-sectional study of 252 puppies of various sizes, aged 6-212 days. The appearance and development of ossification centres as a function of age in five regions of interest in the (meta)carpal region were scored using a two- to six-step scoring system based on shape and delineation. A positive correlation with age was found for all investigated regions. Intra- and interrater agreement between two observers was excellent, except for the distal epiphyses of the metacarpal bones. Postnatal ossification started after the second week of life with the carpal bones, closely followed by the radial trochlea. All ossification centres were present in all puppies from 84 days, except for the sesamoid bone in the tendon of the long abductor muscle of the first digit. Timing of appearance differed significantly between different sized breeds. There were no significant differences between the sexes. Age distribution was not balanced for all breed size classes. The radiographic timing of the appearance and development of ossification centres in the carpal region is a promising method for age estimation in puppies.

Woman with dyspnea after skin rash.

Woman with dyspnea after skin rash.

Do Different Approaches Make a Difference in Isokinetic Performance in Elderly Patients With Femoral Neck Fracture Who Underwent Bipolar Endoprosthesis?

Background There are ongoing doubts about the effects of the commonly used anterolateral approach (ALA) and posterolateral approach (PLA) for bipolar hemiarthroplasty (BHA) on hip muscle strength after surgery. In this study, it was aimed to evaluate the isokinetic performance of the operated and non-operated hips in patients with femoral neck fractures who underwent BHA with PLA or ALA and to compare the isokinetic performance of the hips and functional results between the two approaches. Materials and methods Forty-one patients who underwent unilateral BHA with PLA or ALA for femoral neck fracture between February 2019 and December 2020 were enrolled. The isokinetic performance of the flexor, extensor, and abductor muscles of the operated and non-operated hips were evaluated by measuring peak torque, total work, and average power. Functional status was assessed using Harris Hip Score and Short Form 36. Results The patients were divided into two groups; those operated with PLA (n=22) and with ALA (n=19). The groups had similar demographic and clinical characteristics. All isokinetic parameters of the operated hips did not differ between the groups (all p>0.05). In both groups, all isokinetic parameters were significantly lower in the operated hips than in the non-operated hips. Conclusion Although there are debates about potential extensor muscle injury with PLA and potential abductor muscle injury with ALA, this study showed that functional results and the isokinetic performance of both approaches were not different.

Hip abductor dysfunction following total hip arthroplasty by modified direct lateral approach: Assessment by quantitative electromyography

Abstract Background The use of the direct lateral approach and its modifications for total hip arthroplasty (THA) may lead to postoperative abductor weakness. Assessment of abductor muscle function by the use of quantitative electromyography (EMG) aims to investigate the nature of abductor muscle dysfunction. Methods We conducted a study on 40 patients who had hip replacement through the modified direct lateral approach. EMG was performed before surgery on the affected and normal sides and repeated on the operated side after surgery by 6 and 12 weeks. Analysis of EMG of the three abductor muscles was done in all patients. Results EMG evidence of acute denervation of hip abductors was present in 15 hips (37.5%) after 6 weeks. Improvement of EMG findings occurred in 8 out of 15 patients. Quantitative electromyography (QEMG) showed early significant increase in amplitude in all muscles and decrease in duration in gluteus medius (G. Med) with a pattern of acute nerve injury. At 12 weeks, the values of duration, amplitude, and phase were insignificantly different from the preoperative values signifying the return of near normal muscle activity. Conclusion The use of modified direct lateral approach can cause denervation of hip abductors. It is common in the early postoperative weeks. However, it tends to improve and the residual weakness in some patients is not marked. Quantitative electromyography showed that partial denervation is related to superior gluteal nerve stretching and not to direct injury of the terminal branches of the nerve through the incision.

Outcomes After Abductor Reattachment to Proximal Femur Endoprosthesis After Tumor Resection

Resection of the proximal femur raises several challenges including restoration of the abductor mechanism. Few evaluated the outcomes of different techniques of abductor fixation to the proximal femur endoprosthesis. A retrospective review of patients who underwent proximal femoral arthroplasty with a minimum follow-up of 12 months was conducted. Patients were divided into two groups: (1) those with preserved greater trochanter (GT) reattached to the implant and (2) those with direct abductor muscle reattachment. Both groups were compared for surgical and functional outcomes. Group 1 patients were subdivided into those who received GT reinsertion using grip and cables and those reattached using sutures. Fifty-three patients were included with a mean follow-up of 49 months. There were 22 patients with reinserted GT and 31 patients with soft-tissue repair. The endoprosthesis revision rate was comparable between groups (P = 0.27); however, the incidence of dislocations was higher in group 2 (0/22 versus 6/31; P = 0.035). Trendelenburg gait (77% versus 74%), use of walking aids (68% versus 81%), and abductor muscle strength were comparable between both groups (P > 0.05). In group 1, 15 patients had GT reinsertion with grip and cables. Of those, five patients (33%) had cable rupture within 13 months of follow-up. GT displacement reached 12 mm at 12 months of follow-up in patients with grip and cables compared with 26 mm in patients with GT suture reinsertion (P < 0.05). Although GT preservation did not improve functional outcomes, it was associated with a lower dislocation rate despite frequent cable failure. Less displacement was observed when GT reattachment used grip and cables.

Effectiveness of Manual Therapy and Specific Exercise Conditioning on Clinical Outcome Measures among Participants with Subacromial Impingement Syndrome

Shoulder subacromial impingement syndrome (SIS) is a mechanical disturbance caused by a multifactorial aetiology, and conservative treatment is the first choice. This study aims to investigate the combined short-term effect of manual therapy and eccentric exercise conditioning on clinical outcomes in the acute phase. We recruited 126 subjects with a SIS of 3 months' duration and divided them into two groups of 63 people each. The experimental group received manual therapy and eccentric exercise; the control group received concentric exercise, spread over 3 weeks, followed by a home program for another 9 weeks. Pain intensity, shoulder elevation range, abductor and external rotator muscle strength, and regional function were obtained at baseline, after 10 sessions of treatment and follow-up at 12 weeks. After the first session and by the end of 3 weeks, a global rating of change (GRC) questionnaire was administered to determine self-perceived improvement. An analysis of variance with repeated measures was applied, and the results showed that there were statistically significant differences in both groups; all outcomes improved after treatment and during follow-up (&lt;i&gt;P&lt;/i&gt; &amp;#60; 0.005). However, on intergroup analysis, significant improvement was observed with pain intensity (&lt;i&gt;P&lt;/i&gt; &amp;#60; 0.0005), elevation range of motion (&lt;i&gt;P&lt;/i&gt; &amp;#60; 0.05) and external rotator muscle strength (&lt;i&gt;P&lt;/i&gt; &amp;#60; 0.016) after treatment, and external rotator muscle strength and SPADI score (&lt;i&gt;P&lt;/i&gt; &amp;#60; 0.0005) at follow-up by 12 weeks in the experimental group. The between-group comparison revealed that pain reduction by 3 weeks, external rotator muscle strength by 3 and 12 weeks, had resulted in a large effect size. Manual therapy and eccentric exercise can reduce pain intensity, improve shoulder elevation range, and gleno-humeral muscle strength after 12 weeks of training better than concentric exercises. The improvement in shoulder function with the experimental group exceeded the MCID of 13 points, resulting in a large and significant effect size (d &amp;#61; 1.08). The self-perceived improvement (GRC) was significant in the experimental group (&lt;i&gt;P&lt;/i&gt; &amp;#60; 0.001) with a clinically significant change greater than the MCID (3 points).

Sex-Specific Differences in Hip Muscle Cross-sectional Area and Fatty Infiltration in Patients With Femoroacetabular Impingement Syndrome.

Patients with femoroacetabular impingement syndrome (FAIS) show sex-specific differences in hip muscle function, hip morphology, and symptoms. Possible differences in hip muscle characteristics between men and women with FAIS are unknown. To compare hip muscle cross-sectional area (CSA) and fatty infiltration between men and women with FAIS and investigate possible associations with patient-reported outcomes. Cohort study; Level of evidence, 3. We retrospectively analyzed preoperative axial pelvic magnetic resonance imaging scans of 104 patients (54 women) who underwent hip surgery for FAIS. The main outcome measures were side-to-side percentage asymmetry in hip muscle CSA and involved-side fatty infiltration as measured with the Goutallier scale for a total of 10 hip muscles. Patient-reported outcomes included duration of hip symptoms, iHOT-12 (12-item International Hip Outcome Tool), and Hip Sports Activity Scale. Women showed larger hip abductor muscle CSA asymmetry than men (P = .018), particularly for the gluteus medius (P = .049), while men exhibited more fatty streaks (grade 1) in the gluteus medius (P = .015) than women. Duration of symptoms was associated only with fatty infiltration of obturator externus in men (r S = -0.55, P = .018). iHOT-12 was associated with CSA asymmetry of the gluteus minimus (r = -0.41, P = .011) and iliopsoas (r = -0.36, P = .028) in men and with piriformis fatty infiltration (r S = -0.56, P = .030) in women. The Hip Sports Activity Scale was associated with iliopsoas CSA asymmetry (r S = 0.32, P = .026) and with fatty infiltration of the tensor fasciae latae (r S = -0.45, P = .046) and obturator externus (r S = -0.50, P = .023) in women. Patients with FAIS demonstrated few sex-specific quantitative and qualitative alterations of hip muscles. Women showed greater hip abductor muscle atrophy than men, particularly for the gluteus medius, while men showed a higher degree of fatty infiltration in this same muscle. The duration of hip symptoms was not associated with muscle atrophy. Patient-reported hip pain/function and sport activity level were only moderately associated with isolated muscular variables.

Examination of hip function and muscle activity during clam exercise.

[Purpose] Clam exercise is commonly used to strengthen hip abductor muscles. This study aimed to classify the directions of greater trochanter movement during clam exercise and examine whether this classification reveals any differences in the characteristics of muscle activities. [Participants and Methods] Twenty healthy male participants were included and were divided into three groups according to the direction of greater trochanter movements during clam exercise: diagonally upward, backward, and upward. Muscle activity of the gluteus medius, gluteus maximus, tensor fascia lata, and external oblique was measured during clam exercise, along with the direction of greater trochanter movement and maximum muscle strength in the clam exercise limb position. [Results] In the diagonally upward group, the gluteus medius muscles showed higher activity than the other three muscles, and their activity was higher in the diagonally upward and backward groups than in the upward group. [Conclusion] The tension and action vector of the muscles changed due to differences in the direction of the greater trochanter movement caused by the movement pattern of each participant. The muscle activity around the hip joint changes with the direction of greater trochanter movement during clam exercise.