Internal Rotation Angle Research Articles

ПРОСТРАНСТВЕННАЯ СТРУКТУРА НЕЙРОПЕПТИДА MET-CALLATOSTATIN

In work by the method of molecular mechanics in approximation of atom-atom potential functions is studied the spatial structure and conformational properties of the molecules from allatostatin family, got the name of Met-callatostatin. The researches were based on minimizing of the energy of intramolecular interactions (non-bonded, electrostatic, torsion) in the vicinity of the internal rotation angles corresponding to all combinations of stable conformations of monopeptide residues forming a molecule. There determined ten energetically stable conformations of molecules, implemented under the conditions of implicitly given aqueous environment, the relative conformational energy of which varies in the range of 0-10 kcal / mol. It was shown that the system of hydrogen bonds, despite a small contribution to the total energy of the molecule is essential for the preservation of a stable structure and restriction of Met-callatostatin. Key words: neuropeptides, structure, conformational analysis, peptides, by molecular mechanics

Atomistic simulation of poly (lactic acid) of different regioregularity

In this paper, an atomistic model of poly (lactic acid) (PLA) was developed, and the effect of the relative content of monomer units L and D on the final conformational (distributions of the angles of internal rotation around bonds along the chain, radius of gyration) and thermophysical (density, glass transition temperature) properties of amorphous PLA melts was studied using the molecular dynamics method. It was confirmed that the radius of gyration and the characteristic ratio decrease with decreasing regioregularity of chains. The results obtained are in good quantitative agreement with the available simulation and experimental data. The efficiency of General Amber Force Field with charges calculated for helical poly (L-lactic acid) chain for precise simulation of PLA was justified.

Larger hip external rotation motion is associated with larger knee abduction and internal rotation motions during a drop vertical jump

ABSTRACT Associations among hip motions, knee abduction and internal rotation motion during a drop vertical jump (DVJ), which increases the risk of anterior cruciate ligament injury, remain unclear. The purpose of this study was to examine associations among knee abduction, internal rotation and hip joint motions during a DVJ. Fifty-seven young female participants performed a DVJ from a 30-cm height. Hip and knee kinematics and kinetics were analysed using a three-dimensional motion analysis system and force plates. Multiple regression analysis showed that peak knee abduction angle was negatively associated with knee internal rotation and hip internal rotation excursions from initial contact (IC) to peak knee flexion, and positively associated with peak knee abduction moment (R2 = 0.465, P< 0.001). Peak knee internal rotation angle was negatively associated with the hip flexion excursion from IC to peak knee flexion and peak hip adduction moment (R2 = 0.194, P= 0.001). In addition, hip internal rotation excursion was negatively associated with knee abduction and internal rotation excursion from IC to 50 ms after IC. To avoid a large knee abduction and internal rotation motion during jump-landing training, it might be beneficial to provide landing instructions to avoid a large hip external rotation motion.

Prolonged Running Using Bionic Footwear Influences Lower Limb Biomechanics.

The running biomechanics of unstable shoes have been well investigated, however, little is known about how traditional neutral shoes in combination with unstable design elements and scientifically (bionic) designed shoes influence prolonged running biomechanics. The purpose of this study was to investigate biomechanical changes for a typical 5 km run and how footwear technology may affect outcomes. Sixteen healthy male recreational heel strike runners participated in this study, and completed two prolonged running sessions (neutral shoe session and bionic shoe session), with 7 to 10 days interval between sessions. A two-way repeated-measures analysis of variance (ANOVA, shoe × time) was conducted to determine any differences in joint biomechanics. Main effects for shoe type were observed at the ankle, knee and hip joints during the stance phase. In particular, decreased range of motion (ROM) was observed using the bionic shoes for all three joints, and the joint moments also had significant changes except for the frontal plane of the hip. Main effects for time were also observed at the ankle, knee and hip joints. The ROM of the sagittal plane in the knee and hip decreased post-5 km running. The reduction of ankle dorsiflexion, hip flexion, hip adduction and hip internal rotation angles were observed post-5 km running, as well as the increase of ankle eversion and external rotation, knee adduction and internal rotation angles. The kinetics also exhibited significant differences between pre-5 km running and post-5 km running. The interaction effects only existed in the ROM of the hip sagittal plane, hip adduction angle and hip internal rotation angle. The results suggested that bionic shoes could be beneficial for strengthening muscle control, enhancing postural stability and proprioceptive ability. Footwear personalization could be a solution that benefits runners, reduces injury risk and improves running performance.

Side-hops challenge knee control in the frontal and transversal plane more than hops for distance or height among ACL-reconstructed individuals

ABSTRACT We compared knee landing mechanics with presumed relation to risk of anterior cruciate ligament (ACL) injury among three single-leg hop tests and between legs in individuals with unilateral ACL reconstruction. Thirty-four participants (>10 months’ post-surgery, 23 females) performed the standardised rebound side hop (SRSH), maximal hop for distance (OLHD) and maximal vertical hop (OLVH). We calculated the following knee outcomes from motion capture and force plate data: finite helical axis inclination angles (approximates knee robustness), frontal and transversal plane angles at initial contact, peak angles of abduction and internal rotation during landing, and peak external moments of flexion, abduction and internal rotation during landing. Repeated-measures MANOVA analysis (‘sex’ as covariate) confirmed that SRSH induced greater angles and moments, particularly in the frontal plane, compared to OLHD and OLVH. There was between-leg asymmetry for peak knee flexion moment for males during OLHD and OLVH, and for females during SRSH. Our results advocate the SRSH over OLHD and OLVH for assessment of knee landing control to screen for movement patterns potentially related to ACL injury risk. However, clear differences in both knee kinematics and kinetics between OLHD and SRSH motivate the use of both tests to evaluate different aspects of landing control.

Validity and reliability of smartphone applications for measurement of hip rotation, compared with three\u2010dimensional motion analysis

BackgroundMeasurement of hip rotation is a crucial clinical parameter for the identification of hip problems and the monitoring of symptoms. The objective of this study was to determine whether the use of two smartphone applications is valid and reliable for the measurement of hip rotation.MethodsAn experimental, cross-sectional study was undertaken to assess passive hip internal and external rotation in three positions by two examiners. The hip rotational angles were measured by a smartphone clinometer application in the sitting and prone positions, and by a smartphone compass application in the supine position; their results were compared with those of the standard, three-dimensional, motion analysis system. The validities and inter-rater and intra-rater reliabilities of the smartphone applications were evaluated.ResultsThe study involved 24 participants. The validities were good to excellent for the internal rotation angles in all positions (ICC 0.81–0.94), good for the external rotation angles in the prone position (ICC 0.79), and fair for the sitting and supine positions (ICC 0.70–0.73). The measurement of the hip internal rotation in the supine position had the highest ICC value of 0.94 (0.91, 0.96). The two smartphone applications showed good-to-excellent intra-rater reliability, but good-to-excellent inter-rater reliability for only three of the six positions (two other positions had fair reliability, while one position demonstrated poor reliability).ConclusionsThe two smartphone applications have good-to-excellent validity and intra-rater reliability, but only fair-to-good inter-rater reliability for the measurement of the hip rotational angle. The most valid hip rotational position in this study was the supine IR angle measurement, while the lowest validity was the ER angle measurement in the sitting position. The smartphone application is one of the practical measurements in hip rotational angles.Trial registrationNumber 20181022003 at the Thai Clinical Trials Registry (http://www.clinicaltrials.in.th) which was retrospectively registered at 2018-10-18 15:30:29.

A 3D motion capture analysis of a giving-way ankle episode during a 180-degree pivot turn: A case report

Lateral ankle sprains are highly prevalent during sporting activities, as it accounts for approximately 60% of all athletic injuries. There is currently a paucity of research which provides kinetic and kinematic assessments of sprains and giving-way episodes of the ankle joint. The aim of this case study was to examine the kinetics and kinematics of the ankle and knee during a giving-way episode in a female ice hockey player during a 180-degree pivot turn, which was conducted in a 3D motion capture laboratory. Three trials were conducted on this participant (one accident trial, two control trials). Kinetic and kinematic analysis was conducted on the outside leg during a left 180-degree pivot turn (right leg). The plantarflexion angle of the giving-way trial was larger than the control trials from the point of initial contact until the end of the trial. Inversion was also 27-degrees greater 150 ms after initial contact in the giving-way trial and 26-degrees greater compared to control trials 1 and 2. Substantially greater plantarflexion, inversion and internal rotation angles of the ankle were observed during the giving-way trial compared to control trials. The maximum vertical and horizontal ground reaction forces, as well as ankle inversion and internal rotation moments, were lower for the giving-way trial in comparison to the control trials. Further research is needed to understand the influence of plantarflexion angle with a giving-way episode of the ankle. This study provides valuable kinetic and kinematic information regarding a giving-way episode of the ankle.

Effects of deep friction massage and dry needling therapy on night pain and shoulder internal rotation in subacromial pain syndrome: 1-year follow up of a randomised controlled trial

Background/AimsShoulder problems are common in the general population. The aim of this research was to compare the short and long-term effects of trigger point deep friction massage and trigger point dry needling therapy on rest, activity, and the intensity of night shoulder pain and shoulder internal rotation in Subacromial Pain Syndrome.MethodsOut of 73 outpatients diagnosed with Subacromial Pain Syndrome, 40 were selected according to agreed criteria and were randomly assigned to two groups. A total of 19 patients received trigger point deep friction massage and 21 received trigger point dry needling therapy. The trigger point deep friction massage group received treatment over 3 weeks and the trigger point dry needling therapy group received treatments over 4 weeks. Both groups received six treatment sessions and a programme of post-treatment exercises. The shoulder internal rotation angle was measured using a goniometer, and pain intensities were measured using a visual analogue scale before the first session, after six sessions and after 1 year.ResultsAccording to both the short- and long-term data, significant improvements were seen in both groups for all parameters. However, when the groups were compared, no significant difference was found between the two interventions, although the trigger point deep friction massage intervention showed earlier improvements as the treatments could be carried out in 3 weeks, rather than the 4 weeks required for the trigger point dry needling therapy sessions.ConclusionsBoth trigger point deep friction massage and trigger point dry needling therapy are effective in improving pain and shoulder internal rotation. Both groups maintained significant clinical improvement throughout the year. Although both interventions produced good results, trigger point deep friction massage treatments were completed in a shorter time and so demonstrated earlier improvements. Therefore, Trigger point deep friction massage may be regarded as the preferred option, particularly as no equipment is needed and is a non-invasive method of treatment.

Evaluation of Knee Kinematics and Moments during Active Deep Flexion Activity after Oxford Mobile-Bearing Medial UKA-A Two-Year Follow-Up Study.

Few studies have assessed knee range of motion (ROM) and moments of patients with mobile-bearing unicompartmental knee arthroplasty (MB UKA) during active deep flexion activities. We analyze knee kinematic and kinetic parameters during postoperative squatting-standing activity, aiming to evaluate the efficacy of MB UKA and postoperative rehabilitation progress. This was a clinical cohort study. We followed up with 37 patients diagnosed with medial knee osteoarthritis (OA) with primary UKA. After screening 31 patients were recruited to take gait tests. Squatting-standing activities were performed under the test of 10-camera motion analysis system and force plates preoperatively at different stages after UKA (12, 18, and 24 months). The average duration of follow-up was 24.4 months (from 22.8 to 26.7 months). Hip-knee-ankle angle improved significantly compared with pre-UKA as well as scores of American Knee Society Score, numeric rating scale, ORS, and Western Ontario and McMasters. University Osteoarthritis Index. About 83.6% (31/37) of follow-up patients completed squatting-standing activity independently. At 1-year follow-up, peak varus angle (20.6 ± 2.8 degrees), internal rotation angle (13.6 ± 1.8 degrees), extensor moment (1.44 ± 0.04N*m/kg), and internal rotator moment (0.02 ± 0.005N*m/kg) of UKA knees were inferior to contralateral knees. Peak adductor moment (0.76 ± 0.05N*m/kg) was superior to contralateral knees. At 2-year follow-up, peak flexion angle (125.0 ± 2.8 degrees) showed a growing trend meanwhile extensor (1.70 ± 0.03N*m/kg) and adductor (0.68 ± 0.06 N*m/kg) moment closely resembled those of the contralateral knee. MB UKA could alleviate the affected knee mainly in flexion-extension ROM and moment meanwhile did not affect the biomechanical indicators of healthy limbs. OA knees in the early postoperative period showed decreased extensor moment and increased adductor moment during active deep flexion activity. Better ROM and relatively more natural extensor and adductor moment of UKA knee with rehabilitation time increasing may predict ideal rehabilitation outcome in the medium or longer term.

Core Strength Training Can Alter Neuromuscular and Biomechanical Risk Factors for Anterior Cruciate Ligament Injury

Background: Core stability is influential in the incidence of lower extremity injuries, including anterior cruciate ligament (ACL) injuries, but the effects of core strength training on the risk for ACL injury remain unclear. Hypothesis: Core muscle strength training increases the knee flexion angle, hamstring to quadriceps (H:Q) coactivation ratio, and vastus medialis to vastus lateralis (VM:VL) muscle activation ratio, as well as decreases the hip adduction, knee valgus, and tibial internal rotation angles. Study Design: Controlled laboratory study. Methods: A total of 48 male participants were recruited and randomly assigned to either the intervention group (n = 32) or the control group (n = 16). Three-dimensional trunk, hip, knee, and ankle kinematic data and muscle activations of selected trunk and lower extremity muscles were obtained while the participants performed side-step cutting. The core endurance scores were measured before and after training. Two-way analyses of variance were conducted for each dependent variable to determine the effects of 10 weeks of core strength training. Results: The trunk endurance scores in the intervention group significantly increased after training (P < .05 for all comparisons). The intervention group showed decreased knee valgus (P = .038) and hip adduction angles (P = .032) but increased trunk flexion angle (P = .018), rectus abdominis to erector spinae coactivation ratio (P = .047), H:Q coactivation ratio (P = .021), and VM:VL activation ratio (P = .016). In addition, the knee valgus angle at initial contact was negatively correlated with the VM:VL activation ratio in the precontact phase (R2 = 0.188; P < .001) but was positively correlated with the hip adduction angle (R2 = 0.120; P < .005). No statistically significant differences were observed in the trunk endurance scores, kinematics, and muscle activations for the control group. Conclusion: Core strength training altered the motor control strategies and joint kinematics for the trunk and the lower extremity by increasing the trunk flexion angle, VM:VL activation ratio, and H:Q activation ratio and reducing the knee valgus and hip adduction angles. Clinical Relevance: Training core muscles can modify the biomechanics associated with ACL injuries in a side-step cutting task; thus, core strength training might be considered in ACL injury prevention programs to alter the lower extremity alignment in the frontal plane and muscle activations during sports-related tasks.

Rotational kinematics differ between mild and severe valgus knees in total knee arthroplasty

BackgroundThere is no consensus regarding femorotibial rotational kinematics in total knee arthroplasty (TKA) for valgus knee deformity. Additionally, whether the degree of valgus deformity influences intraoperative rotational kinematics and postoperative clinical scores remains unclear. The objectives of this study were to investigate whether the valgus angle is associated with intraoperative rotational kinematics in TKA for valgus knee deformity and to examine the relationship between rotational kinematics and postoperative clinical results. Materials and methodsA total of 24 knees with valgus deformity for TKA were included in this study and were divided into two groups depending on the femorotibial angle (FTA); there were 11 knees in the severe valgus group (FTA < 160°) and 13 knees in the mild valgus group (FTA ≥ 160°). Intraoperative femorotibial rotational kinematics from knee extension to flexion were evaluated using an image-free navigation system and postoperative clinical results (range of motion and subjective outcomes) were evaluated 1 year postoperatively. All parameters were compared between the two groups. ResultMild valgus knee showed tibial internal rotation during knee flexion before implantation, whereas severe valgus knee showed tibial external rotation during knee flexion before implantation. The postoperative flexion angle was positively correlated with the tibial internal rotation angle after implantation in the mild valgus group only. ConclusionIntraoperative rotational kinematics before implantation differed between mild and severe valgus knee deformity in TKA. Intraoperative tibial rotation influenced the postoperative knee flexion angle in mild, but not severe, valgus knee deformity. Ideal postoperative rotational kinematics may be different between the two groups and the difference may be taken into consideration in implant selections and surgical techniques.

BIOMECHANICAL MEASURES DURING TWO SPORT-SPECIFIC TASKS DIFFERENTIATE BETWEEN SOCCER PLAYERS WHO GO ON TO ANTERIOR CRUCIATE LIGAMENT INJURY AND THOSE WHO DO NOT: A PROSPECTIVE COHORT ANALYSIS.

Decelerating and cutting are two common movements during which non-contact anterior cruciate ligament (ACL) injuries occur in soccer players. Retrospective video analysis of ACL injuries has demonstrated that players are often in knee valgus at the time of injury. To determine whether prospectively measured components of valgus collapse during a deceleration and 90 ° cut can differentiate between collegiate women's soccer players who go on to non-contact ACL injury. Secondary analysis of prospectively collected data. 51 NCAA women's soccer players completed motion analysis of a deceleration and 90 ° before the competitive season. Players were classified as Injured (noncontact ACL injury during the season) or Uninjured at the end of the season. Differences between groups for peak hip adduction, internal rotation, and knee abduction angles, and knee valgus collapse were analyzed with a MANOVA. Four non-contact ACL injuries were reported at the end of the season. There was a significant difference between groups for hip adduction angle during the 90 ° cut (p = 0.02) and deceleration (p = 0.03). Players who went on to ACL injury were in more hip adduction. Hip adduction angle is larger in players who go on to ACL injury than those who do not during two sport-specific tasks. The components of knee injury prevention programs that address proximal control and strength are likely crucial for preventing ACL injuries. 2b.

Theoretical investigation on hub structure design of subsea connectors

Subsea processing of oil/gas is performed by production system facilities, which are linked into a complete system by subsea connectors. High reliability and long service life of the connectors, defined by strict requirement of deepwater oil fields, raise the challenge of the design of the structure components to which the ASME-VIII code has been applied. The theoretical design problems of the main parameters of subsea connector's hub structure are detailed in this paper in comparison with the shortage of the ASME design method. Therefore, a new analytical model is developed, and is named stress analytical method (SAM). The hub structure is separated into two parts, i.e. a thick-walled cylinder and a hollow annular plate, and axisymmetric bending deformation problems of the thick-walled cylinder are proposed. The geometric equations, the constitutive equations, the physical equations and the equilibrium equations are developed to obtain the displacement analytical solution of the hub structure's thick-walled cylinder. The deformation continuity relationships between the thick-walled cylinder and the hollow annular plate are also established, and the analytical solutions of internal forces, displacements, rotation angles and stress components are acquired accordingly. The accuracy of SAM is investigated by comparing stress calculation results with Finite Element Method (FEM) results. A case study is carried out to compare SAM with ASME design method.

Arthroscopic versus open treatment for femoroacetabular impingement: A systematic review and meta-analyses.

Background:Femoroacetabular impingement (FAI) is a common cause of hip pain and restricted range of motion in young adults and athletes. This study aims to compare clinical results and complications between patients treated for FAI who underwent either arthroscopic or open treatment.Methods:The 7 studies were acquired from PubMed, Medline, Embase, and Cochrane Library. The data were extracted analyzed by RevMan5.3. Mean differences (MDs), odds ratios (ORs), and 95% confidence intervals (CIs) were calculated. The Newcastle–Ottawa Scale were used to assess risk of bias.Results:Seven observational studies were assessed. The methodological quality of the trials indicated a low risk of bias. The pooled results of the modified Harris Hip Score (mHHS), the Non-Arthritic Hip Score (NAHS), the Visual Analogue Scale (VAS), and satisfaction rate showed that the differences were not statistically significant between arthroscopic treatment (AT) and open treatment (OT). The difference of postoperative alpha angle was statistically significant, and OT was more effective [MD = 3.08, 95% confidence interval (95% CI) = 1.45–4.70, P = .0002]. The difference of postoperative internal rotation angle was statistically significant, and OT had better internal rotation angle (MD = -3.21, 95% CI = -6.14 to -0.28, P = .03). However, the difference of complications was statistically significant and AT achieved better result than OT (OR = 0.41, 95% CI = 0.22–0.74, P =0.003).Conclusion:AT had comparable effect and lower complications than OT, but had less improvement in alpha angle and internal rotation angle.

Association Between Knee- and Hip-Extensor Strength and Running-Related Injury Biomechanics in Collegiate Distance Runners.

Running-related injuries are common in distance runners. Strength training is used for performance enhancement and injury prevention. However, the association between maximal strength and distance-running biomechanics is unclear. To determine the relationship between maximal knee- and hip-extensor strength and running biomechanics previously associated with injury risk. Cross-sectional study. Research laboratory. A total of 36 collegiate distance runners (26 men, 10 women; age = 20.0 ± 1.5 years, height = 1.74 ± 0.09 m, mass = 61.97 ± 8.26 kg). Strength was assessed using the 1-repetition maximum (1RM) back squat and maximal voluntary isometric contractions of the knee extensors and hip extensors. Three-dimensional running biomechanics were assessed overground at a self-selected speed. Running variables were the peak instantaneous vertical loading rate; peak forward trunk-lean angle; knee-flexion, internal-rotation, and -abduction angles and internal moments; and hip-extension, internal-rotation, and -adduction angles and internal moments. Separate stepwise linear regression models were used to examine the associations between strength and biomechanical outcomes (ΔR2) after accounting for sex, running speed, and foot-strike index. Greater 1RM back-squat strength was associated with a larger peak knee-flexion angle (ΔR2 = 0.110, ΔP = .045) and smaller peak knee internal-rotation angle (ΔR2 = 0.127, ΔP = .03) and internal-rotation moment (ΔR2 = 0.129, ΔP = .03) after accounting for sex, speed, and foot-strike index. No associations were found between 1RM back-squat strength and vertical loading rate, trunk lean, or hip kinematics and kinetics. Hip- and knee-extensor maximal voluntary isometric contractions were also not associated with any biomechanical variables. Greater 1RM back-squat strength was weakly associated with a larger peak knee-flexion angle and smaller knee internal-rotation angle and moment in collegiate distance runners. Runners who are weaker in the back-squat exercise may exhibit running biomechanics associated with the development of knee-related injuries.

Use of a 3D Virtually Reconstructed Patient-Specific Model to Examine the Effect of Acetabular Labral Interference on Hip Range of Motion.

Background:The labrum is likely to influence impingement, which may also depend on acetabular coverage. Simulating impingement using 3-dimensional (3D) computed tomography (CT) is a potential solution to evaluating range of motion (ROM); however, it is based on bony structures rather than on soft tissue.Purpose:To examine ROM when the labrum is considered in a 3D dynamic simulation. A particular focus was evaluation of maximum flexion and internal rotation angles before occurrence of impingement, comparing them in cases of cam-type femoroacetabular impingement (FAI) and borderline developmental dysplasia of the hip (BDDH).Study Design:Descriptive laboratory study.Methods:Magnetic resonance imaging (MRI) and CT scans of 40 hips (20 with cam-type FAI and 20 with BDDH) were reviewed retrospectively. The thickness and width of the labrum were measured on MRI scans. A virtual labrum was reconstructed based on patient-specific sizes measured on MRI scans. The impingement point was identified using 3D dynamic simulation and was compared with the internal rotation angle before and after labral reconstruction.Results:The thickness and width of the labrum were significantly larger in BDDH than in FAI (P < .001). In FAI, the maximum internal rotation angles without the labrum were 30.3° at 90° of flexion and 56.9° at 45° of flexion, with these values decreasing to 18.7° and 41.4°, respectively, after labral reconstruction (P < .001). In BDDH, the maximum internal rotation angles were 48.0° at 90° of flexion and 76.7° at 45° of flexion without the labrum, decreasing to 31.1° and 55.3°, respectively, after labral reconstruction (P < .001). The differences in the angles before and after labral reconstruction were larger in BDDH than in FAI (90° of flexion, P = .03; 45° of flexion, P = .01).Conclusion:As the labrum was significantly more hypertrophic in BDDH than in FAI, the virtual labral model revealed that the labrum’s interference with the maximum internal rotation angle was also significantly larger in BDDH.Clinical Relevance:The labrum has a significant effect on impingement; this is more significant for BDDH than for FAI.

Association Between Hip Rotation and Activation of the Quadriceps and Gluteus Maximus in Male Runners.

Background:Although running can provide health benefits, knee joint injuries are frequently reported by recreational runners. To date, the precise mechanism responsible for anterior knee pain remains elusive, and the source of symptoms is debated. Inconsistencies are found in the literature pertaining to the relationship between hip mechanics and activity in the quadriceps and gluteus maximus (GMax) during the running gait.Purpose/Hypothesis:To investigate the correlations between hip rotation and the activity in the quadriceps and GMax during running. We hypothesized that increased hip rotation is correlated with decreased activity in these muscles.Study Design:Descriptive laboratory study.Methods:A cohort of 30 healthy recreational runners volunteered to participate in the study (mean ± SD age, 28.8 ± 5.66 years; height, 1.73 ± 0.05 m; mass, 69 ± 6.3 kg; body mass index, 23.02 ± 1.42 kg/m2). Surface electromyography (EMG) data were obtained from the GMax, vastus medialis obliquus (VMO), and vastus lateralis obliquus (VLO). These data were synchronized with a motion capture system during a level-surface running activity at a speed of 3.2 m/s.Results:A significantly strong, negative correlation was found between the hip internal rotation angle and EMG activity of the GMax and the VMO. However, the VLO showed a significant, moderate, and positive correlation of activity with the hip internal rotation angle.Conclusion:The present study showed that during level-surface running, decreased GMax activity may be the cause of distal joint injuries and alteration in quadriceps muscle activity.Clinical Relevance:Because GMax activity is important for controlling the lower body mechanics during running, evaluating GMax activity and internal hip rotation angle is important to prevent the running-related knee injuries that are linked to quadriceps deficits, such as patellofemoral pain. Additionally, clinicians and trainers should consider strengthening the GMax while rehabilitating running-related knee injuries.

Gait and Knee Flexion In Vivo Kinematics of Asymmetric Tibial Polyethylene Geometry Cruciate Retaining Total Knee Arthroplasty.

The preservation of the posterior cruciate ligament in cruciate retaining (CR) total knee arthroplasty (TKA) designs has the potential to restore healthy knee biomechanics; however, concerns related to kinematic asymmetries during functional activities still exist in unilateral TKA patients. As there is a limited data available regarding the ability of the contemporary CR TKA design with concave medial and convex lateral tibial polyethylene bearing components to restore healthy knee biomechanics, this study aimed to investigate in vivo three-dimensional knee kinematics in CR TKA patients during strenuous knee flexion activities and gait. Using a combined computer tomography and dual fluoroscopic imaging system approach, in vivo kinematics of 15 unilateral CR TKA patients (comparison of replaced and contralateral nonreplaced knee) were evaluated during sit-to-stand, step-ups, single-leg deep lunge, and level walking. The patient cohort was followed-up at an average of 24.5 months ( ± 12.6, range 13-42) from surgical procedure. Significantly smaller internal knee rotation angles were observed for the contemporary CR TKA design during step-ups (2.6 ± 5.8 vs. 6.3 ± 6.6 degrees, p < 0.05) and gait (0.6 ± 4.6 vs. 6.3 ± 6.8 degrees, p < 0.05). Significantly larger proximal and anterior femoral translations were measured during sit-to-stand (34.7 ± 4.5 vs. 29.9 ± 3.1 mm, p < 0.05; -2.5 ± 2.9 vs. -8.1 ± 4.4 mm, p < 0.05) and step-ups (34.1 ± 4.5 vs. 30.8 ± 2.9 mm, p < 0.05; 2.2 ± 3.2 vs. -3.5 ± 4.5 mm, p < 0.05). Significantly smaller ranges of varus/valgus and internal/external rotation range of motion were observed for CR TKA, when compared with the nonoperated nee, during strenuous activities and gait. The preservation of the posterior cruciate ligament in the contemporary asymmetric bearing geometry CR TKA design with concave medial and convex lateral tibial polyethylene bearing components has the potential to restore healthy knee biomechanics; however, the study findings demonstrate that native knee kinematics were not fully restored in patients with unilateral asymmetric tibial polyethylene bearing geometry CR TKA during functional activities.

Inclusion of the Acetabular Labrum Reduces Simulated Range of Motion of the Hip Compared With Bone Contact Models

PurposeTo determine whether inclusion of the acetabular labrum affects the maximum range of motion (ROM) during simulation of the flexion–adduction–internal rotation impingement examination.MethodsThree-dimensional surface reconstructions of the femur, hemi-pelvis, and labrum from computed tomography arthrography images of 19 participants were used to simulate maximum ROM during the flexion–adduction–internal rotation examination. Simulations were conducted for positions between 70° and 110° flexion and 0° and 20° adduction at 10° increments to measure maximum internal rotation and the position of contact between the femur and acetabular rim (bone-to-bone) or the femur and labrum (bone-to-labrum). Internal rotation angles and clock-face position values were compared between the 2 contact scenarios for each position.ResultsThe ROM in the bone-to-labrum contact model was significantly less than that of the bone-to-bone contact model for all evaluated positions (P ≤ .001, except at 110° flexion and 20° adduction, P = .114). The inclusion of the labrum reduced internal rotation by a median [interquartile range] of 18 [15, 25]° while altering the position of contact on the acetabular clock-face by –0:01 [–0:27, 0:16]. The variability in contact location for the bone-to-labrum contact scenario was nearly double that of the bone-to-bone contact scenario, as indicated by the interquartile range.ConclusionsInclusion of the anatomy of the acetabular labrum in collision models used to simulate impingement examinations reduced the internal rotation ROM by approximately 20° and increased variability in the location of contact relative to the acetabular rim.Clinical RelevanceWhile standard bone-to-bone contact ROM simulations may be informative with respect to the relative change in ROM based on a surgical intervention (e.g., pre- and post-osteochondroplasty for cam-type femoroacetabular impingement), they may not accurately represent the clinical ROM of the joint or the kinematic position at which damage may occur due to shape mismatch between the femur and acetabulum.

Absolute Photoabsorption Cross-Sections of Methanol for Terrestrial and Astrophysical Relevance.

We investigate the methanol absorption spectrum in the range 5.5-10.8 eV to provide accurate and absolute cross-sections values. The main goal of this study is to provide a comprehensive analysis of methanol electronic-state spectroscopy by employing high-resolution vacuum ultraviolet (VUV) photoabsorption measurements together with state-of-the-art quantum chemical calculation methods. The VUV spectrum reveals several new features that are not previously reported in literature, for n > 3 in the transitions (nsσ(a') ← (2a″)) (1A' ← X̃1A') and (nsσ, npσ, npσ', ndσ ← (7a')) (1A' ← X̃1A'), and with particular relevance to vibrational progressions of the CH3 rocking mode, v11'(a″), mode in the (3pπ(a″) ← (2a″)) (21A' ← X̃1A') absorption band at 8.318 eV. The measured absolute photoabsorption cross-sections have subsequently been used to calculate the photolysis lifetime of methanol in the Earth's atmosphere from the ground level up to the limit of the stratosphere (50 km altitude). This shows that solar photolysis plays a negligible role in the removal of methanol from the lower atmosphere compared with competing sink mechanisms. Torsional potential energy scans, as a function of the internal rotation angle for the ground and first Rydberg states, have also been calculated as part of this investigation.