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Concept: Gracilis muscle


In total hip arthroplasty, determining the impingement free range of motion requirement is a complex task. This is because in the native hip, motion is restricted by both impingement as well as soft tissue restraint. The aim of this study is to determine a range of motion benchmark which can identify motions which are at risk from impingement and those which are constrained due to soft tissue. Two experimental methodologies were used to determine motions which were limited by impingement and those motions which were limited by both impingement and soft tissue restraint. By comparing these two experimental results, motions which were limited by impingement were able to be separated from those motions which were limited by soft tissue restraint. The results show motions in extension as well as flexion combined with adduction are limited by soft tissue restraint. Motions in flexion, flexion combined with abduction and adduction are at risk from osseous impingement. Consequently, these motions represent where the maximum likely damage will occur in femoroacetabular impingement or at most risk of prosthetic impingement in total hip arthroplasty.

Concepts: Hip replacement, Hip, Pelvis, Orthopedic surgery, Extension, Abduction, Adduction, Gracilis muscle


Hip adductor injuries are frequent in football, and players with low adductor strength appear to be at increased risk of injury. High adductor muscle activity has been shown in the Copenhagen Adduction exercise (CA); however, an associated strength gain has not been investigated. This study aims to examine the eccentric hip adduction strength (EHAD) gain using the CA in-season. Two U-19 sub-elite football teams, including 24 football players, were randomized to either an 8-week supervised progressive training program in addition to the usual training (intervention) or to continue training as usual (control). EHAD, eccentric hip abduction strength (EHAB), and side-bridge endurance were measured using reliable test procedures at baseline and follow-up by a blinded tester. There was a significant interaction between group and time on EHAD, EHAB, and EHAD/EHAB ratio (P < 0.025). The intervention group demonstrated a 35.7% increase in EHAD (P < 0.001); a 20.3% increase in EHAB (P = 0.003), and 12.3% increase in EHAD/EHAB ratio (P = 0.019). No significant within-group differences were found in the control group (P > 0.335). Compliance was 91.25%, and median muscle soreness ranged from 0 to 2. The CA implemented in-season with an 8-week progressive training program elicited a large significant increase in EHAD, EHAB, and EHAD/EHAB ratio.

Concepts: Randomized controlled trial, Hip, Abduction, Adduction, Gracilis muscle, Muscles of the hip, Adductor muscles of the hip


A multivector functional muscle flap that closely simulates the biomechanical effects of facial muscle groups is essential for complete smile restoration after facial paralysis.

Concepts: Muscle, Gracilis muscle


Hooper, DR, Szivak, TK, DiStefano, LJ, Comstock, BA, Dunn-Lewis, C, Apicella, JM, Kelly, NA, Creighton, BC, Volek, JS, Maresh, CM, and Kraemer, WJ. Effects of resistance training fatigue on joint biomechanics. J Strength Cond Res 27(1): 146-153, 2013-Resistance training has been found to have a multitude of benefits. However, when performed with short rest, resistance training can result in substantial fatigue, which may have a negative impact on exercise technique. The purpose of this study is to examine the effects of fatigue from resistance exercise on joint biomechanics to determine what residual movement effects may exist after the workout. Twelve men with at least 6 months of resistance training experience (age 24 ± 4.2 years, height 173.1 ± 3.6 cm, weight 76.9 ± 7.8 kg) performed 5 body weight squats before (pretest) and after (posttest) a highly fatiguing resistance training workout. Lower extremity biomechanics were assessed using a 3-dimensional motion analysis system during these squats. Peak angle, total displacement, and rate were assessed for knee flexion, trunk flexion, hip flexion, hip rotation, and hip adduction. Results showed a significant decrease in peak angle for knee flexion (Pre: 120.28 ± 11.93°, Post: 104.46 ± 9.85°), hip flexion (Pre: -109.42 ± 12.49°, Post: -95.8 ± 12.30°), and hip adduction (Pre: -23.32 ± 7.04°, Post: -17.30 ± 8.79°). There was a significant reduction in angular displacement for knee flexion (Pre: 115.56 ± 10.55°, Post: 103.35 ± 10.49°), hip flexion (Pre: 97.94 ± 10.69°, Post: 90.51 ± 13.22°), hip adduction (Pre: 17.79 ± 7.36°, Post: 11.89 ± 4.34°), and hip rotation (Pre: 30.72 ± 12.28, Post: 20.48 ± 10.12). There was also a significant reduction in displacement rate for knee flexion (Pre: 2.20 ± 0.20, Post: 1.98 ± 0.20), hip flexion (Pre: 1.92 ± 0.20, Post: 1.76 ± 0.27), hip adduction (Pre: -0.44 ± 0.17, Post: -0.31 ± 0.17), and hip rotation (Pre: 0.59 ± 0.23, Post: 0.38 ± 0.21). This study demonstrated that there are lasting residual effects on movement capabilities after a high-intensity short rest protocol. Thus, strength and conditioning coaches must be careful to monitor movements and exercise techniques after such workouts to prevent injury and optimize subsequent exercise protocols that might be sequenced in order.

Concepts: Physical exercise, Exercise, Knee, Strength training, Weight training, Resistance training, Flexion, Gracilis muscle


PURPOSE: Prospectively, a consecutive group of patients troubled by recurrent patella dislocation and trochlear dysplasia has been followed after a combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament. The purpose of this follow-up study is to report the clinical results. METHODS: Indications for combined arthroscopic deepening trochleoplasty and reconstruction of the medial patellofemoral ligament were two or more patellar dislocations with a persistent apprehension sign above 20° of flexion and trochlear dysplasia grade B or more. Prospectively, the Tegner, Kujala and KOOS scores were recorded. Thirty-one consecutive patients (37 knees), 21 women and 10 men, with a median age of 19 (12-39) underwent the procedure. RESULTS: Results were obtained for 29 knees with a minimum of 12-month follow-up (average 29 months; range 12-57). No complications, redislocations or arthrofibrosis have been recorded. Five patients needed further surgery. The median pre- and postoperative scores (range) are as follows: Kujala 64 (12-90) to 95 (47-100); Tegner 4 (1-6) to 6 (4-9); KOOS score pain 86-94; symptoms 82-86; ADL 91-99; sport 40-86; QDL 25-81. No significant correlation was found with respect to the results and recorded parameters. Significant improvement for all of the scores was observed (p < 0.001). CONCLUSIONS: The use of arthroscopic deepening trochleoplasty in combination with reconstruction of the medial patellofemoral ligament was found to be a safe and reproducible procedure. Considering the stability achieved, the knee scores and the patient's level of satisfaction, the results are encouraging. LEVEL OF EVIDENCE: Prospective consecutive case series, with evaluation of confounding factor. No control group, Level IV.

Concepts: Scientific method, Knee, Anterior cruciate ligament, Joint, Flexion, Patella, Medial collateral ligament, Gracilis muscle


The purpose of this study was to quantify the relative changes in fascicle (FL) and muscle-tendon unit (LMTU) length of the long head of the biceps femoris (BFlh) at different combinations of hip and knee joint positions. Fourteen participants performed passive knee extension trials from 0°, 45° and 90° of hip flexion. FL, LMTU, pennation angle (PA) and effective FL (FL multiplied by the cosine of the PA) of the BFlh were quantified using ultrasonography (US). Three-way analysis of variance designs indicated that at each hip angle, FL and LMTU increased and PA decreased from 90° to 0° of knee flexion. Increasing hip flexion angle from 0° to 90° led to a higher FL and LMTU and a lower PA (p < .05). The average lengthening of the LMTU and effective FL was 28.00 ± 1.82% and 85.88 ± 21.92%, respectively. The average effective FL change accounted for 51.36 ± 7.39% of LMTU change. The relationship between effective FL and LMTU was almost linear with a slope equal to 0.49 ± 0.06 (r2 = 0.52 to 0.97). To achieve greater lengthening of the fascicles of the BFlh, passive stretch with the hip flexed at least 45° and the knee reaching full extension is necessary.

Concepts: Knee, Joint, Sartorius muscle, Flexion, Extension, Semitendinosus muscle, Semimembranosus muscle, Gracilis muscle


The purpose of this study was to compare the relationship between several measures of single-joint, isometric, eccentric, and squat strength and unilateral and bilateral landing mechanics at the hip and knee in females. Twenty six healthy female subjects with previous athletic experience (height 165.1 ± 7.01 cm, mass 60.91 ± 7.14 kg, age 20.9 ± 1.62 yrs) participated in this study. Hip and knee mechanics were measured using the MotionMonitor capture system (Innovative Sports Training Inc, Chicago, IL.) with 3-dimensional electromagnetic sensors during bilateral (60 cm) and unilateral drop jumps (30 cm). On a separate day, isometric hip extension, external rotation, and abduction strength (lbs) were measured using a handheld dynamometer (Hoggan Health Industries, Inc., West Jordan, Utah). Eccentric and isometric knee strength were measured on the Biodex IV Isokinetic Dynamometer (Biodex Medical Systems, Inc., Shirley, NJ). Free weight was used to measure the bilateral squat and a modified single-leg squat. The strongest correlations were found between squat strength and knee valgus (-0.77 ≤ r ≤ -0.83) and hip adduction (-0.5 ≤ r ≤ -0.65). After controlling for squat strength, hip external rotation strength and unilateral knee valgus (-0.41), hip abduction strength and bilateral knee valgus (-0.43), and knee flexion strength and bilateral hip adduction (-0.57) remained significant. Eccentric knee flexion strength and unilateral knee internal rotation was the only significant correlation for eccentric strength (-0.40). Squat strength appears to be the best predictor of knee valgus and was consistently related to hip adduction. Isometric and eccentric measures demonstrated few significant correlations with hip and knee excursion while demonstrating a low to moderate relationship. Hip and knee flexion and rotation do not appear to be related to strength. Squat strength should receive consideration during risk assessment for non-contact knee injury.

Concepts: Knee, Hip, Sartorius muscle, Flexion, Extension, Semimembranosus muscle, Adduction, Gracilis muscle


This study aimed to clarify the mechanical gait changes caused by achilles tendinopathy by comparing gait parameters and changes in hip, knee, and ankle moments between an experimental group (EG) and a control group (CG). Twenty runners with achilles tendinopathy were included in the EG (male/female: 10/10, age: 27.00 ± 4.63), and 20 CG (male/female: 10/10, age: 27.25 ± 4.33) participants were recruited. Subjects walked a 13-m distance at their normal walking speed 5 times to obtain motion analysis and joint moment data. Gait parameter analysis showed significant differences in double-limb support (EG: 22.65 ± 4.26%, CG: 20.37 ± 4.46%), step length (EG: 0.58 ± 0.0 7m, CG: 0.64 ± 0.08 m), step width (EG: 0.16 ± 0.04 m, CG: 0.14 ± 0.05 m), stride time (EG: 1.09 ± 0.10 second, CG: 1.05 ± 0.08 second), and walking speed (EG: 1.09±0.18 m·s(-1), CG: 1.23 ± 0.17 m·s(-1)) between the 2 groups (p < 0.05). Significant differences were found in hip joint moment for initial contact, mid-stance, terminal stance, and pre-swing phases; knee joint moment for initial contact and pre-swing phases; and ankle joint moment for pre-swing and terminal swing phases (p < 0.05). Gait parameters and hip, knee, and ankle moments were altered in runners with achilles tendinopathy. Thus, clinical features of gait changes should be understood for optimal treatment of achilles tendinopathy; further research is required in this field. Key pointsA reduction in gait parameters, namely, step length, stride length, and walking speed, and an increase in double-limb support occurs in runners with achilles tendinopathy.A reduction in the hip extension moment occurs during the initial contact, as well as a reduction in the knee flexion moment from the mid-stance to pre-swing phases, a continuous decrease in the knee flexion moment from the early stance phase, and a reduction in the extension moment during the terminal stance phase.A reduction in the ankle plantar flexion moment occurs from the mid-stance phase and that a reduction in the dorsiflexion moment occurs during the terminal swing phase.

Concepts: Knee, Sartorius muscle, Joints, Flexion, Extension, Walking, Semimembranosus muscle, Gracilis muscle


We sought to determine if an in-field gait retraining program can reduce excessive impact forces and peak hip adduction without adverse changes in knee joint work during running. Thirty healthy at-risk runners who exhibited high-impact forces were randomized to retraining [21.1 (±1.9) years, 22.1 (±10.8) km/week] or control groups [21.0 (±1.3) years, 23.2 (±8.7) km/week]. Retrainers were cued, via a wireless accelerometer, to increase preferred step rate by 7.5% during eight training sessions performed in-field. Adherence with the prescribed step rate was assessed via mobile monitoring. Three-dimensional gait analysis was performed at baseline, after retraining, and at 1-month post-retraining. Retrainers increased step rate by 8.6% (P < 0.0001), reducing instantaneous vertical load rate (-17.9%, P = 0.003), average vertical load rate (-18.9%, P < 0.0001), peak hip adduction (2.9° ± 4.2 reduction, P = 0.005), eccentric knee joint work per stance phase (-26.9%, P < 0.0001), and per kilometer of running (-21.1%, P < 0.0001). Alterations in gait were maintained at 30 days. In the absence of any feedback, controls maintained their baseline gait parameters. The majority of retrainers were adherent with the prescribed step rate during in-field runs. Thus, in-field gait retraining, cueing a modest increase in step rate, was effective at reducing impact forces, peak hip adduction and eccentric knee joint work.

Concepts: Knee, Joint, Sartorius muscle, Synovial joint, Gait analysis, Adduction, Gracilis muscle


Patellofemoral Pain and Iliotibial Band Syndromes are common running injuries. Excessive hip adduction (HADD), hip internal rotation (HIR) and contralateral pelvic drop (CLPD) during running have been suggested as causes of injury in female runners. This study compared these kinematic variables during barefoot and shod running.

Concepts: Hip, Classical mechanics, Kinematics, Centripetal force, Adduction, Gracilis muscle, Iliotibial band syndrome, Barefoot running