Hip External Rotation Research Articles

Total Hip Arthroplasty or Arthroscopy for Pigmented Villonodular Synovitis of the Hip: A Retrospective Study with 3‐Year Follow‐Up at Minimum

Pigment Villonodular synovitis of the hip, a rare pain proliferation of the synovium, was treated successfully with total hip arthroplasty and arthroscopy. Most recent results come from small case series with no study comparing arthroscopy and arthroplasty. In this study, we aimed to show and compare the clinical outcomes of arthroscopy and total hip arthroplasty (THA) in pigment Villonodular synovitis of the hip. This was a retrospective clinical trial with data from patients with pigment Villonodular synovitis of the hip between 2010 and 2019. The study included 17 patients in the THA group, and 20 patients in the arthroscopy group. The clinical outcomes were evaluated at 3, 6, and 12months, at 1 and 2 years, and every 5 years afterward. The clinical efficacy was measured using the Harris hip scores (HHSs) and visual analogue scale (VAS) score. The mean HHS improved from 45.24 ± 10.36 to 78.94 ± 19.11 in the THA group (t=-6.394, P=0.000) and 45.30 ± 11.08 to 71.60 ± 19.78 (t=-5.187, P=0.000) in the arthroscopy group from pre-operation to the final follow-up. There is no significant difference between the two groups (t=1.051, P=0.301). The mean VAS improved from 3.65 ± 0.79 to 0.35 ± 0.70 (t=12.890, P=0.000) in the THA group and 4.05 ± 0.94 to 1.35 ± 1.79 (t=5.979, P=0.001) in the arthroscopy group postoperatively. There is no significant difference between the two groups (t=1.329, P=0.193). Recurrence of PVNS was diagnosed in four patients (20%) of the arthroscopy group and they underwent THA after arthroscopy, and the mean interval was 44.25 ± 6.98months. All patients reached level 5 muscle strength by the final follow-up. All the patients' buckling ranges were over 105 degrees. Their internal and external hip rotation was over 15 degrees. Their hip adduction was over 20 degrees, and abduction over 30 degrees. Both THA and arthroscopy in the setting of PVNS can improve patients' function and lead to a low rate of local recurrence. By selecting patients well for each approach, one can expect a reasonable result.

Do Highly Trained Mountain Runners Differ from Recreational Active Non-Runners on Range of Motion and Strength in the Hip and Ankle as Well as Postural Control?

The rules governing mountain running force athletes to implement into their training programmes uphill and downhill running on unstable surfaces, which are demanding for hip and ankle as well as for the postural control system. The aim of the present cross-sectional study was to compare highly trained mountain runners (MR) and recreational active non-runners (NR) on range of motion (ROM) and strength in the hip and ankle, as well as dynamic postural control. Thirty MR and thirty-two NR were included in the study. ROM was assessed using a digital inclinometer. Strength was measured using a hand-held dynamometer. Postural control was evaluated using the lower quarter Y-balance test (YBT-LQ). The results showed that MR, in relation to NR, had statistically significant smaller hip external rotation ROM (p = 0.007), lower hip external rotator (p = 0.006) and extensor (p = 0.023) strength and greater normalised anterior reach in the YBT-LQ (p = 0.028). Mountain running training may reduce hip external rotation ROM as well as hip external rotator and extensor strength. Moreover, such training may improve postural control. MR should implement exercises targeted at developing hip ROM and strength. Furthermore, it seems that mountain running training may be a good way to improve postural control.

The AIUM Practice Parameter for the Performance of the Musculoskeletal Ultrasound Examination.

The AIUM Practice Parameter for the Performance of the Musculoskeletal Ultrasound Examination.

The effects of weight gain over time on gait in children with cerebral palsy: Comparison to a matched healthy weight cerebral palsy control group

BackgroundChildren with cerebral palsy (CP) have demonstrated higher rates of overweight and obesity than their typically developed peers. Limited studies have assessed how being overweight or obese affect lower limb kinematics during gait in these children. Research questionHow are lower limb kinematics during gait affected in children with CP who progress from a healthy weight to being overweight or obese compared to a well-matched healthy weight CP control group? MethodsA retrospective analysis of the movement analysis laboratory database was conducted.Children with CP were included if they were aged between 4 and 17 years at baseline,had a follow-up assessment with a minimum of 12 months between assessments, and had no orthopaedic interventions between assessments. A matched control group of children with CP with the same inclusion criteria, except for a requirement of healthy BMI at follow-up, was included. Temporal-spatial and full 3-dimensional lower limb kinematic data were examined. ResultsNormalized speed and step length reduced from baseline to follow-up for both groups,with no difference in the amount of change between groups. Children with increased BMI demonstrated increased external hip rotation during stance at follow-up not evident in the control group. SignificanceResults demonstrated similar changes over time between groups. Increased external hip rotation in children with increased BMI was considered small and within the threshold of error associated with transverse plane kinematics. Our results suggest that being overweight or obese does not result in a meaningful change in lower limb kinematics in children with CP.

Comparison of muscle activity of hamstrings as knee flexors and hip extensors and effect of tibial and hip rotation on the contribution of hamstrings

BackgroundLimited studies have compared the muscle activity of the medial and lateral hamstrings as knee flexors with tibial internal and external rotation and hip extensors with hip internal and external rotation. In particular, hamstring activity during hip extension with hip rotation has rarely been investigated. ObjectiveThis study aimed to compare the muscle activity of the medial and lateral hamstrings as knee flexors and hip extensors and to compare the activity of these muscles according to tibial rotation during isometric knee flexion and hip rotation during isometric hip extension. MethodsA total of 23 healthy adults participated in the study. The electromyographic (EMG) activity of the hamstrings was measured during maximal isometric knee flexion and maximal isometric hip extension. In addition, tibial rotation was applied actively during maximal isometric knee flexion, whereas hip rotation was applied actively during maximal isometric hip extension. ResultsEMG activity during maximal isometric knee flexion with tibial internal and external rotation was significantly higher than that during maximal isometric hip extension with hip internal and external rotation, respectively. For EMG activity according to tibial and hip rotation, there was no significant difference between tibial internal and external rotation during maximal isometric knee flexion, whereas there was a significant difference between hip internal and external rotation during maximal isometric hip extension. ConclusionHamstring activity was higher for knee flexors than for hip extensors. However, hip rotation during maximal isometric hip extension is an effective intervention for selective muscle activation of the medial and lateral hamstrings.

Predictive simulation of single-leg landing scenarios for ACL injury risk factors evaluation.

The Anterior Cruciate Ligament (ACL) rupture is a very common knee injury during sport activities. Landing after jump is one of the most prominent human body movements that can lead to such an injury. The landing-related ACL injury risk factors have been in the spotlight of research interest. Over the years, researchers and clinicians acquire knowledge about human movement during daily-life activities by organizing complex in vivo studies that feature high complexity, costs and technical and most importantly physical challenges. In an attempt to overcome these limitations, this paper introduces a computational modeling and simulation pipeline that aims to predict and identify key parameters of interest that are related to ACL injury during single-leg landings. We examined the following conditions: a) landing height, b) hip internal and external rotation, c) lumbar forward and backward leaning, d) lumbar medial and lateral bending, e) muscle forces permutations and f) effort goal weight. Identified on related research studies, we evaluated the following risk factors: vertical Ground Reaction Force (vGRF), knee joint Anterior force (AF), Medial force (MF), Compressive force (CF), Abduction moment (AbdM), Internal rotation moment (IRM), quadricep and hamstring muscle forces and Quadriceps/Hamstrings force ratio (Q/H force ratio). Our study clearly demonstrated that ACL injury is a rather complicated mechanism with many associated risk factors which are evidently correlated. Nevertheless, the results were mostly in agreement with other research studies regarding the ACL risk factors. The presented pipeline showcased promising potential of predictive simulations to evaluate different aspects of complicated phenomena, such as the ACL injury.

Definition of High-Risk Motion Patterns for Female ACL Injury Based on Football-Specific Field Data: A Wearable Sensors Plus Data Mining Approach.

The aim of the present study was to investigate if the presence of anterior cruciate ligament (ACL) injury risk factors depicted in the laboratory would reflect at-risk patterns in football-specific field data. Twenty-four female footballers (14.9 ± 0.9 year) performed unanticipated cutting maneuvers in a laboratory setting and on the football pitch during football-specific exercises (F-EX) and games (F-GAME). Knee joint moments were collected in the laboratory and grouped using hierarchical agglomerative clustering. The clusters were used to investigate the kinematics collected on field through wearable sensors. Three clusters emerged: Cluster 1 presented the lowest knee moments; Cluster 2 presented high knee extension but low knee abduction and rotation moments; Cluster 3 presented the highest knee abduction, extension, and external rotation moments. In F-EX, greater knee abduction angles were found in Cluster 2 and 3 compared to Cluster 1 (p = 0.007). Cluster 2 showed the lowest knee and hip flexion angles (p < 0.013). Cluster 3 showed the greatest hip external rotation angles (p = 0.006). In F-GAME, Cluster 3 presented the greatest knee external rotation and lowest knee flexion angles (p = 0.003). Clinically relevant differences towards ACL injury identified in the laboratory reflected at-risk patterns only in part when cutting on the field: in the field, low-risk players exhibited similar kinematic patterns as the high-risk players. Therefore, in-lab injury risk screening may lack ecological validity.

Association Between Nondominant Leg-Side Hip Internal Rotation Restriction and Low Back Pain in Male Elite High School Soft Tennis Players.

The incidence of low back pain (LBP) is high among high school male soft tennis players. In some sports for which the rotational component of the body is important, an association between restricted hip internal rotation of the nondominant leg and LBP has been reported; however, whether this association holds in soft tennis is unknown. Therefore, this study aimed to evaluate the association between hip internal rotation, hip external rotation, hamstring flexibility, iliopsoas flexibility, and LBP incidence. This study was designed as a cross-sectional study, conducted at a sports training center. Participants comprised 113 male elite high school soft tennis players (age: 16.1 [0.7]y) from 9 elite-level teams. The main outcome measures were the hip internal and external rotation range of motion, hamstring flexibility on the straight leg raise test, and iliopsoas flexibility on the Thomas test. Multiple logistic regression analysis was performed to examine the influence of main outcomes on LBP incidence in the past 1year. A total of 35 participants had LBP (LBP group); 78 participants did not have LBP (non-LBP group). Multiple logistic regression analysis revealed that the odds ratio for height was 1.08 (95% confidence interval, 1.00-1.16; P = .043) and for the hip internal rotation range of motion in the nondominant leg was 0.90 (95% confidence interval, 0.85-0.95; P < .001), indicating significant associations with LBP. Hip internal rotation range of motion in the nondominant leg and height were crucial factors related to LBP in male elite high school soft tennis players.

Hip Abduction Can Be Considered the Sole Posterior Precaution Strategy to Lower the Rate of Impingement After Posterior Approach Total Hip Arthroplasty With Large Femoral Head: A Computer Simulation Study

BackgroundStudies suggest that posterior hip precautions are unnecessary after total hip arthroplasty; however, many surgeons and patients choose to follow these precautions to some extent. In this study, we hypothesized that 20° of hip abduction would be sufficient to prevent impingement and dislocation in motions requiring hip flexion when using larger prosthetic heads (≥36 mm) when the acetabular implant is placed within a reasonable orientation (anteversion:15-25° and inclination: 40-60°). MethodsUsing a robotic hip platform, we investigated the effect of hip abduction on prosthetic and bony impingement in 43 patients. For the flexed seated position, anterior pelvic tilt angles of 10 and 20° were chosen, while anterior pelvic tilt angles of 70 and 90° were chosen for the bending forward position. An additional 10° of hip external rotation and 10 or 20° of hip internal rotation were also added to the simulation. One hip received a 32-mm head; otherwise, 36-, 40-mm, or dual-mobility heads were used. The study power was 0.99, and the effect size was 0.644. ResultsIn 65% of the cases, bone-bone impingement between the calcar and anterior-inferior iliac spine was the main type of impingement. The absolute risk of impingement decreased between 0 and 16.3% in both tested positions with the addition of 20° hip abduction. ConclusionWith modern primary total hip arthroplasty stems (low neck diameter) and an overall acceptable cup anteversion angle, small degrees of hip abduction may be the only posterior hip precaution strategy required to lower the risk of dislocation among patients. Future studies can potentially investigate the concept of personalized hip precautions based on preoperative computer simulations, utilized implants, hip-spine relations, and final implant orientation.

The Impact of Varying Femoral Head Length on Hip External Rotation During Posterior-approach Total Hip Arthroplasty

BackgroundPrior investigations of total hip arthroplasty (THA) have studied the effects of prosthetic femoral head size and stem offset on hip range of motion (ROM), impingement risk, and overall hip stability to optimize the return to activities of daily living. However, the relationship between femoral head length and hip ROM, specifically external rotation (ER), has not been evaluated. The aim of our study was to intraoperatively assess how femoral head length affects hip ROM during a posterior approach THA. MethodsThirty-two patients undergoing a primary elective THA through a posterior approach were prospectively included. After final femoral stem insertion, femoral head trials were performed using the targeted head length, followed by the shorter (−3.0 to −3.5 mm) and longer (+3.0 to +4.0 mm) head length configurations. At each length, hip ER was measured using an intraoperative goniometer from an imageless navigation system. ER values across the three head lengths were compared using a repeated-measures analysis of variance and paired t-tests. ResultsVarying femoral head lengths demonstrated a statically significant and reproducible effect on intraoperative ER range (analysis of variance; P < .001) in each patient. An increased femoral head length (mean 3.4 mm) significantly decreased (P < .001) ER range by 10.8 ± 3.3° while a shortened femoral head length (mean 3.5 mm) significantly increased (P < .001) the ER ROM by 6.0 ± 3.8°. ConclusionsThe results of this study demonstrate the sensitivity of hip ROM to incremental changes in femoral head length. As ER is important for activities of daily living, inadvertent lengthening should be avoided.

Influência da idade e do sexo na força isométrica do joelho e do quadril de indivíduos jovens e de meia idade praticantes recreacionais de atividades físicas

ABSTRACT Muscle strength is an essential part of the functional assessment of health professionals to select and analyze the effects of clinical interventions. This study aimed to determine the influence of gender and age on isometric strength of hip and knee muscle groups. A total of 127 subjects (50.4% men), aged from 20 to 49 years (stratified into three groups: 20-29 years; 30-39 years; and 40-49 years) participated in this study. A hand-held dynamometer was used to measure isometric normalized torque of the hip abductors, hip external rotators, knee extensors, and knee flexors muscles. Regressions and a two-way analysis of variance were used to identify the influence of age and gender on torque of each muscle group. Age and gender were included in the regression model for all groups. Generally, men aged 20-29 and 30-39 were stronger than age-paired women. For participants aged 40-49, torque was similar for men and women for all muscle groups. There was no difference among age groups for women. Generally, young men were stronger than older men. The association between age and gender in hip and knee strength was proved and liable of subgroup stratification after measurements with a hand-held isometric dynamometer.

Relationship Between Posterior Shoulder Tightness and Lower-Limb Flexibility in College Baseball Players.

Posterior shoulder tightness evaluated as limited glenohumeral internal rotation and horizontal adduction is a risk factor for throwing-related shoulder and elbow injuries. Given that the throwing motion uses the entire body kinematics, limited lower-limb flexibility might be associated with posterior shoulder tightness. Therefore, we aimed to investigate the relationships between posterior shoulder tightness and lower-limb flexibility in college baseball players. Cross-sectional study. University laboratory. Twenty-two college baseball players (20 right-handed and 2 left-handed). To investigate the relationships between glenohumeral range of motion and lower-limb flexibility using simple linear regression analysis, we measured passive range of motion of glenohumeral internal rotation and horizontal adduction, hip internal/external rotation in the prone/sitting position, ankle dorsiflexion, and quadriceps and hamstrings flexibility from both shoulders and legs. Our analysis indicated that decreases in the lead leg hip external rotation in the prone position were moderately associated with limitations in glenohumeral internal rotation (R2 = .250, β [95% confidence interval, CI] = 0.500 [0.149 to 1.392], P = .018) and horizontal adduction (R2 = .200, β [95% CI] = 0.447 [0.051 to 1.499], P = .019) on the throwing shoulder. Furthermore, there were significant moderate relationships between decreases in glenohumeral internal rotation and limited lead leg quadriceps flexibility (R2 = .189, β [95% CI] = 0.435 [0.019 to 1.137], P = .022), and between decreases in glenohumeral horizontal adduction and limited stance leg ankle dorsiflexion (R2 = .243, β [95% CI] = 0.493 [0.139 to 1.438], P = .010). College baseball players with limited lower-limb flexibilities including the lead leg hip external rotation in the prone position, the lead leg quadriceps flexibility, and the stance leg ankle dorsiflexion showed excessive posterior shoulder tightness. The current results support the hypothesis that lower-limb flexibility is associated with posterior shoulder tightness in college baseball players.

Effect of gait training using Welwalk on gait pattern in individuals with hemiparetic stroke: a cross-sectional study.

We aimed to explore the effect of gait training using Welwalk on gait patterns by comparing differences in gait patterns between robotic-assisted gait training using Welwalk and gait training using an orthosis in individuals with hemiparetic stroke. This study included 23 individuals with hemiparetic stroke who underwent gait training with Welwalk combined with overground gait training using an orthosis. Three-dimensional motion analysis on a treadmill was performed under two conditions for each participant: during gait training with Welwalk and with the ankle-foot orthosis. The spatiotemporal parameters and gait patterns were compared between the two conditions. The affected step length was significantly longer, the step width was significantly wider, and the affected single support phase ratio was significantly higher in the Welwalk condition than in the orthosis condition. The index values of abnormal gait patterns were significantly lower while using Welwalk than in the orthosis condition. The following four indices were lower in the Welwalk condition: contralateral vaulting, insufficient knee flexion, excessive hip external rotation during the paretic swing phase, and paretic forefoot contact. Gait training using Welwalk increased the affected step length, step width, and single support phase while suppressing abnormal gait patterns as compared to gait training using the ankle-foot orthosis. This study suggests that gait training using Welwalk may promote a more efficient gait pattern reacquisition that suppresses abnormal gait patterns. Prospectively registered in the Japan Registry of Clinical Trials (https://jrct.niph.go.jp; jRCTs042180152).

The Relationship between Patellofemoral Pain Syndrome and Hip Biomechanics: A Systematic Review with Meta-Analysis

(1) Background and purpose: Muscular control and motor function in a patient with Patellofemoral pain syndrome (PFPS) have not yet been investigated systematically. Therefore, this review synthesis the previous results about the association of PFPS with gluteus muscle activation, hip strength, and kinematic characteristic of the hip and knee joint, to deepen understanding of the PFPS etiology and promote the establishment of an effective treatment strategy. (2) Methods: A literature search was conducted from January 2000 to July 2022 in four electronic databases: Medline, Embase, Google scholar, and Scopus. A total of 846 articles were initially identified, and after the screening process based on the inclusion criteria, 12 articles were eventually included. Means and SDs of gluteus medius (GMed), gluteus maximus (GMax), hip strength, and kinematic variation of hip and knee were retrieved from the present study. (3) Results and conclusion: Regarding kinematic variation, moderate evidence indicates that an increased peak hip adduction was found in PFPS groups during running and single leg (SL) squat activities. There is no difference in the GMed and GMax activation levels between the two groups among the vast majority of functional activities. Most importantly, strong evidence suggests that hip strength is weaker in individuals with PFPS, showing less strength of hip external rotation and hip abduction compared to the control group. However, without prospective studies, it is difficult to determine whether hip strength weakness is a cause or a result of PFPS. Therefore, further research is needed to evaluate the hip strength level in identifying individuals most likely to associated with PFPS development is needed.

Effect of external isometric hip rotation force on lower extremity muscles activities during pelvic drop with different hip positions

Gluteus medius muscle (Gmed) dysfunction has been confirmed as a functional defect in subjects with Genu Valgum Deformity (GVD). The purpose of this study was to determine whether the change in the positions of hip rotation and applying isometric hip external rotation during pelvic drop (PD) can affect muscles activity in subjects with GVD. A total of thirty recreational female athletes with (n = 15) and without (n = 15) GVD participated in this study. Surface electromyography measured Gmed, tensor fascia latae (TFL), and quadratus lumborum (QL) muscles activity when subjects performed PD in three different positions of hip rotations with and without applied isometric hip external rotation force. There were differences in muscle activity between GVD and healthy subjects. The Gmed/TFL and Gmed/QL muscles activity ratio altered while placing the hip in different rotation positions and applying isometric load. The lower extremity muscles’ activity is affected by GVD, and changing the positions of the hip rotation in the PD task can be associated with altered muscle activity in both GVD and healthy Groups. However, applying isometric hip external rotation during PD can be suggested as an effective intervention to increase Gmed activity.

The functional role of hip muscles during gait in patients with increased femoral anteversion

BackgroundFemoral anteversion affects the lever arm and moment-generating capacity of the hip abductors, while an increased hip internal rotation during walking was proposed to be a compensatory mechanism to restore the abductive lever arm. Children with isolated increased femoral anteversion, however, do not always present a deficit in the net hip abduction moment during gait, suggesting that a more comprehensive understanding of the effect of morphology and motion on muscle forces and moments is needed to aid clinical decision making. Research questionAre muscle contributions to hip joint moments and muscle forces altered in patients with increased femoral anteversion and internally rotated gait pattern compared to a control group of typically developing children? And how would the functional role of the muscle be altered if the patients walked straight? MethodsThis follow-up study compared patients with increased femoral anteversion (n = 42, 12.8 ± 1.9 years, femoral anteversion: 39.6 ± 6.9°) to controls (n = 9, 12.0 ± 3.0 years, femoral anteversion: 18.7 ± 4.1°). Muscle forces and moment contributions were calculated using personalized musculoskeletal models. Additionally, a hypothetical scenario, in which the gait of the controls was modelled with an anteverted femoral morphology, was used to understand what would happen if the patients walked straight. ResultsGluteus medius abductive contribution was lower in patients compared to controls, despite a comparable net abduction moment around the hip. Patients presented lower muscle forces. However, if modelled to walk straight, they would require higher forces as well as a larger co-contraction of both hip internal and external rotators in the transversal plane. SignificanceThis study suggests that patients with increased femoral anteversion walking with an internally rotated gait pattern present lower muscle forces, but when modelled to walk straight muscle forces increase. The current results provide important information to better understand this condition and improve treatment recommendations in these patients.

Greater Hip Moments in Rear-Foot-Elevated Split Squats Than in Conventional Back Squats With the Same Relative Intensity of Loads.

Arakawa, H, Mori, M, and Tanimoto, M. Greater hip moments in rear-foot-elevated split squats than in conventional back squats with the same relative intensity of loads. J Strength Cond Res 37(5): 1009-1016, 2023-Rear-foot-elevated split squat (RFESS) is often performed as an alternative to conventional double-leg back squat (DLBS). This study aimed to compare 3-dimensional joint kinetics of DLBS and RFESS using the same relative intensity of loads. Eight male college rugby players performed 3 repetitions of DLBS and RFESS at 10-repetition-maximum (RM) loading. Before testing, both exercises were incorporated into the subjects' training program with a progressive increase in loads for 4 months. A 3-dimensional optical motion capture system and force platform were used for data collection. The 3-dimensional moments at the knee and hip joints in each of the 3 axes were calculated based on the inverse dynamic procedure. p values < 0.05 were considered statistically significant. The hip extension moment was 44% greater in the RFESS than in the DLBS at the bottom position ( p < 0.01) and 47% greater for the peak value ( p < 0.01) on harmonic averages. The hip abduction and external rotation moments at the bottom position were also greater in the RFESS than in the DLBS. The findings suggest that the magnitude of hip extension moment per leg in DLBS tends to be restricted to less than that expected from the given strength level. In conclusion, the mechanical contribution of hip extensors per leg can be greater in RFESS than in DLBS when using respective 10RM loads, even if the absolute load is smaller and the trunk is more upright in RFESS.

The association between hip strength, physical function and dynamic balance in people with unilateral knee osteoarthritis: A cross-sectional study

BackgroundIn people with knee osteoarthritis, the association between multidirectional hip strength and physical function or balance is unknown. ObjectiveTo determine the relationship between hip flexion, extension, abduction, adduction, external and internal rotation strength and (1) physical function and (2) dynamic balance. DesignCross-sectional. MethodsForty-seven participants (20 men and 27 women, age 66.2 ± 8.2 years) with unilateral knee osteoarthritis were included. Hip strength was assessed with hand-held dynamometry; physical function was assessed with the 40m fast-paced walk test (40mFPWT), 30-s chair-stand test (30sCST), and stair-climb test (SCT); and dynamic balance was assessed in 3 directions using the Star Excursion Balance Test. Multivariable linear regression analysis was used to determine the strength of relationships between measures. ResultsHip strength, in all directions except for internal rotation, was positively associated with better physical function (40mFPWT: R2 = 0.48 to 0.65; SCT: R2 = 0.5 to 0.54; 30sCST: R2 = 0.39 to 0.42), and dynamic balance (anterior: R2 = 0.33 to 0.45; posteromedial: R2 = 0.32 to 0.45; posterolateral: R2 = 0.27 to 0.35). Hip strength, after adjusting for knee extension strength, explained an additional 8%–12% (p < 0.05) and 5%–12% (p < 0.05) reach in the anterior and posteromedial directions of the Star Excursion Balance Test, respectively. ConclusionsHip strength in multiple directions is associated with measures of physical function and dynamic balance in people with unilateral knee osteoarthritis. Clinicians are encouraged to consider hip strength in multiple directions in the context of the patients’ functional and/or balance goals when developing exercise programs for people with knee osteoarthritis.

The effect of fatigue on the ankle and knee kinematics and kinetics in moderately and highly trained healthy non-rearfoot runners

ABSTRACT The aim of this study was to compare selected ankle and knee kinematic and kinetic parameters before and after a prolonged exhaustive treadmill run between two groups of non-rearfoot footstrike pattern (NRFP) runners with different training volumes. Twenty-eight habitual NRFP runners were assigned to two groups based on their weekly training volume (Highly-trained (HT)/Moderately-trained (MT)). Participants underwent the VO2max test, and the exhaustive treadmill ran with biomechanical analysis at the beginning and the end. The two-way RMANOVA was used to assess differences between the groups and the phase of the run. A paired t-test was used for post-hoc analysis in case of significant interaction effect. Kinetic results showed significant group effect for ankle plantarflexion moment and hip external rotation moment (end-phase: both greater in MT group). Kinematic results showed significant group×phase interaction for ankle dorsiflexion angle (end-phase: greater in MT group) at initial contact (IC), peak knee flexion angle (end-phase: greater in MT group), and peak ankle eversion angle during the stance phase (end-phase: greater in HT group). Additionally, a group effect was found for knee flexion angle at IC (end-phase: greater in HT group). This study suggests that HT healthy NRFP runners may have less potential for increased biomechanical risk of AT overload during an exhaustive run.

Effect of Different Pelvic-Drop Exercises On Muscle Activity In Patients With Gluteus Medius Muscle Weakness

<h3>Research Objectives</h3> To determine the effects of pelvic-drop exercise with three different hip rotations on gluteus medius, tensor fasciae latae, gluteus maximus activity, and gluteus medius:tensor fasciae latae activity ratio in patients with gluteus medius weakness. <h3>Design</h3> Cross-sectional study. The effects of different hip rotation positions on hip abductor activity during pelvic-drop exercise were analyzed using a one-way repeated-measures analysis of variance. <h3>Setting</h3> University research laboratory. <h3>Participants</h3> Eighteen patients with gluteus medius weakness participated in the study. <h3>Interventions</h3> The patients performed three different forms of pelvic-drop exercise with neutral hip, hip internal rotation, and hip external rotation. <h3>Main Outcome Measures</h3> Surface electromyography was performed to quantify the activity of gluteus medius, tensor fasciae latae, and gluteus maximus. <h3>Results</h3> Pelvic-drop exercise with hip internal rotation showed significantly greater gluteus medius activity than pelvic-drop exercise with neutral hip and hip external rotation. Tensor fasciae latae also showed significantly greater activity during pelvic-drop exercise with hip internal rotation than pelvic-drop exercise with neutral hip. <h3>Conclusions</h3> Pelvic-drop exercise with hip internal rotation is recommended to stimulate greater gluteus medius activity while preserving gluteus medius:tensor fasciae latae muscle activity ratio. <h3>Author(s) Disclosures</h3> The authors declare no conflict of interest.