Internal Rotational Motion Research Articles

Ultrafast internal rotational dynamics of the azido group in (4S)-azidoproline: Chemical exchange 2DIR spectroscopic investigations

The azido group in 4-azidoproline (Azp) derivative, SA (Ac-(4S)-Azp-NHMe), can form an intramolecular electrostatic interaction with the backbone peptide in the s-trans and Cγ-endo conformations of SA. As a result, the azido group exists as two forms, bound and free, which are defined by the presence and absence of such interaction, respectively. The bound and free azido forms are spectrally resolved in the azido IR spectrum of SA in CHCl3. Using the two-dimensional infrared (2DIR) and polarization-controlled IR pump–probe methods, we investigated the internal rotational and orientational relaxation dynamics of the azido group and determined the internal rotational time constant of the azido group to be 5.1ps. The internal rotational motion is found to be responsible for the early part of the orientational relaxation of the azido group in SA. Thus, the femtosecond 2DIR spectroscopy is shown to be an ideal tool for studying ultrafast conformational dynamics of SA.

A Profile of Glenohumeral Internal and External Rotation Motion in the Uninjured High School Baseball Pitcher, Part II: Strength

A database describing the range of normal rotator cuff strength values in uninjured high school pitchers has not been established. Chronologic factors that contribute to adaptations in strength also have not been established. To establish a normative profile of rotator cuff strength in uninjured high school baseball pitchers and to determine whether bilateral differences in rotator cuff strength are normal findings in this age group. Cohort study. Baseball playing field. A total of 165 uninjured male high school baseball pitchers (age = 16 ± 1 years, height=1.8±0.1 m, mass=76.8±10.1 kg, pitching experience =7±2 years). Isometric rotator cuff strength was measured bilaterally with a handheld dynamometer. We calculated side-to-side differences in strength (external rotation [ER], internal rotation [IR], and the ratio of ER:IR at 90° of abduction), differences in strength by age, and the influence of chronologic factors (participant age, years of pitching experience) on limb strength. Side-to-side differences in strength were found for ER, IR, and ER:IR ratio at 90° of abduction. Age at the time of testing was a significant but weak predictor of both ER strength (R(2)=0.032, P = .02) and the ER:IR ratio (R(2)=0.051 , P = .004) at 90° of abduction. We established a normative profile of rotator cuff strength for the uninjured high school baseball pitcher that might be used to assist clinicians and researchers in the interpretation of muscle strength performance in this population. These data further suggested that dominant-limb adaptations in rotator cuff strength are a normal finding in this age group and did not demonstrate that these adaptations were a consequence of the age at the time of testing or the number of years of pitching experience.

A Profile of Glenohumeral Internal and External Rotation Motion in the Uninjured High School Baseball Pitcher, Part I: Motion

The magnitude of motion that is normal for the throwing shoulder in uninjured baseball pitchers has not been established. Chronologic factors contributing to adaptations in motion present in the thrower's shoulder also have not been established. To develop a normative profile of glenohumeral rotation motion in uninjured high school baseball pitchers and to evaluate the effect of chronologic characteristics on the development of adaptations in shoulder rotation motion. Cohort study. Baseball playing field. A total of 210 uninjured male high school baseball pitchers (age = 16 ± 1.1 years, height=1.8±0.1 m, mass=77.5±11.2 kg, pitching experience=6±2.3 years). Using standard goniometric techniques, we measured passive rotational glenohumeral range of motion bilaterally with participants in the supine position. Paired t tests were performed to identify differences in motion between limbs for the group. Analysis of variance and post hoc Tukey tests were conducted to identify differences in motion by age. Linear regressions were performed to determine the influence of chronologic factors on limb motion. Rotation motion characteristics for the population were established. We found no difference between sides for external rotation (ER) at 0° of abduction (t(209) = 0.658, P = .51), but we found side-to-side differences in ER (t(209) =-13.012,P < .001) and internal rotation (t(209) =15.304, P < .001) at 90° of abduction. Age at the time of testing was a significant negative predictor of ER motion for the dominant shoulder (R(2) = 0.019, P = .049) because less ER motion occurred at the dominant shoulder with advancing age. We found no differences in rotation motion in the dominant shoulder across ages (F(4,205) range, 0.451-1.730,P > .05). This range-of-motion profile might be used to assist with the interpretation of normal and atypical shoulder rotation motion in this population. Chronologic characteristics of athletes had no influence on range-of-motion adaptations in the thrower's shoulder.

A theoretical study of the inversion and rotation barriers in Methyl-substituted Amines

Barrier heights of the internal rotation and inversion motions of methylamine, dimethylamine and trimethylamine molecules were calculated with the CCSD(T)//B3LYP methodology in combination with the cc-pVTZ, cc-pVQZ, and cc-pCVTZ basis sets of Dunning. The complete basis set (CBS) extrapolation procedure and core-valence (CV) correlation effects are also examined to the barrier heights. Our best estimate results (CCSD(T)/CBS+CV//B3LYP/cc-pVQZ) are in very good agreement with the experimental data, indicating the use of this methodology to provide accurate predictions of structures and barrier heights for other systems

Quantum instanton calculation of rate constants for the C2H6 + H → C2H5 + H2 reaction: anharmonicity and kinetic isotope effects

Thermal rate constants and kinetic isotope effects for the title reaction are calculated by using the quantum instanton approximation within the full dimensional Cartesian coordinates. The obtained results are in good agreement with experimental measurements at high temperatures. The detailed investigation reveals that the anharmonicity of the hindered internal rotation motion does not influence the rate too much compared to its harmonic oscillator approximation. However, the motion of the nonreactive methyl group in C(2)H(6) significantly enhances the rates compared to its rigid case, which makes conventional reduced-dimensionality calculations a challenge. In addition, the temperature dependence of kinetic isotope effects is also revealed.

Branched-chain organic compounds. Part 11: Validation of a new method for determination of the potential energy of cohesion of an organic crystal and deduction of the heat capacity of the vapour

The cohesion energy of ethyl 3-cyano-3-(3,4-dimethyloxyphenyl)-2,2,4-trimethylpentanoate, as obtained from the change of kinetic and potential energies in the heat of sublimation of the crystal, E p,coh = −46.7 kJ mol−1 (78.6 °C), has been validated. A safe physicomathematic test based on the balance of entropy for the sublimation and Planck’s equation for changes of state, extended to entropy, was devised to ascertain the kinetic energies of the crystal and the gas molecule. Entropic equations were developed for the phase equilibrium to find precisely and with simplicity the vibrational energy of the crystal by using the vapour pressure exclusively and independently from the internal rotational and vibrational motion of the gas molecule. The heat capacity of the vapour was determined in this way, which in this case releases the solid allowing vibrational movement in the gas phase to meet the pressure of sublimation, C p (T)/J K−1 mol−1 = 1.268 T/K + 58.62 (71.1–86.1 °C). An independent variational method of deducing the vibrational entropy, energy, or heat capacity of the gas molecule from each other was compared with the equations and was shown to yield the quantities with high accuracy. Values of the Nernst–Lindemann functions are tabulated.

Correlation of Glenohumeral Internal Rotation Deficit and Total Rotational Motion to Shoulder Injuries in Professional Baseball Pitchers

Background: Glenohumeral internal rotation deficit (GIRD) indicates a 20° or greater loss of internal rotation of the throwing shoulder compared with the nondominant shoulder. Purpose: To determine whether GIRD and a deficit in total rotational motion (external rotation + internal rotation) compared with the nonthrowing shoulder correlate with shoulder injuries in professional baseball pitchers. Study Design: Case series; Level of evidence, 4. Methods: Over 3 competitive seasons (2005 to 2007), passive range of motion measurements were evaluated on the dominant and nondominant shoulders for 170 pitcher-seasons. This included 122 professional pitchers during the 3 seasons of data collection, in which some pitchers were measured during multiple seasons. Ranges of motion were measured with a bubble goniometer during the preseason, by the same examiner each year. External and internal rotation of the glenohumeral joint was assessed with the participant supine and the arm abducted 90° in the plane of the scapula, with the scapula stabilized anteriorly at the coracoid process. The reproducibility of the test methods had an intraclass correlation coefficient of .81. Days in which the player was unable to participate because of injury or surgery were recorded during the season by the medical staff of the team and defined as an injury. Results: Pitchers with GIRD (n = 40) were nearly twice as likely to be injured as those without but without statistical significance (P = .17). Pitchers with total rotational motion deficit greater than 5° had a higher rate of injury. Minor league pitchers were more likely than major league pitchers to be injured. However, when players were injured, major league pitchers missed a significantly greater number of games than minor league pitchers. Conclusion: Compared with pitchers without GIRD, pitchers with GIRD appear to be at a higher risk for injury and shoulder surgery.

Rotator cuff repair augmentation using a novel polycarbonate polyurethane patch: preliminary results at 12 months’ follow-up

Preventing anatomic failure after rotator cuff repair (RCR) remains a challenge. Augmentation with a surgical mesh may permanently reinforce the repair and decrease failure rates. The purpose of this study is to assess the postoperative outcomes of open RCR augmented with a novel reticulated polycarbonate polyurethane patch. Ten patients with supraspinatus tendon tears underwent open RCR augmented with a polycarbonate polyurethane patch secured in a 6-point fixation construct placed over the repaired tendon. Patients were evaluated with preoperative and postoperative outcome measures, including the Simple Shoulder Test, visual analog pain scale, American Shoulder and Elbow Surgeons shoulder score, Cumulative Activities of Daily Living score, and University of California, Los Angeles shoulder scale, as well as range of motion. Postoperative magnetic resonance imaging was used to evaluate repair status. Patients showed significant improvements in visual analog pain scale, Simple Shoulder Test, and American Shoulder and Elbow Surgeons shoulder scores at both 6 and 12 months postoperatively (P < .05 and P < .01, respectively). The University of California, Los Angeles postoperative score was good to excellent in 7 patients at 6 months and in 8 patients at 12 months. Range of motion in forward flexion, abduction, internal rotation, and external rotation was significantly improved at both 6 and 12 months postoperatively (P < .05 and P < .01, respectively). Magnetic resonance imaging at 12 months showed healing in 90%; one patient had a definitive persistent tear. We found no adverse events associated with the patch, including the absence of fibrosis, mechanical symptoms, or visible subacromial adhesions. The polycarbonate polyurethane patch was designed to support tissue in growth and enhance healing as shown by preclinical animal studies. Clinically, the patch is well tolerated and shows promising efficacy, with a 10% retear rate at the 12-month time point.

The immediate effects of diacutaneous fibrolysis on pain and mobility in patients suffering from painful shoulder: a randomized placebo-controlled pilot study

Objectives: To describe the immediate effects of diacutaneous fibrolysis on pain and mobility in patients suffering from painful shoulder, and to assess the ability of the placebo technique to blind participants to group allocation. Design: A double-blind before–after randomized placebo-controlled pilot study. Setting: Two public centres of Primary Health Care of the Spanish National Health System. Participants: Fifty patients (29 women, 21 men) with a diagnosis of painful shoulder of subacromial origin were included. Intervention: Participants were randomly allocated to one of two groups. The intervention group (N = 25) was actually treated with diacutaneous fibrolysis, while the placebo group (N = 25) was treated with placebo diacutaneous fibrolysis. Measurements: Active range of motion (flexion, abduction, extension, external and internal rotation) and pain intensity in the hand-behind-back position were measured. Participants were also asked about their perception in terms of comfort of the technique and results obtained. Results: Between-groups differences were significant in flexion (mean 11.4 degrees; 95% confidence interval (CI) 5.7–17.1), abduction (mean 7.2 degrees; 95% CI 2.0–12.5) and internal rotation movements (mean 3.1 cm; 95% CI 0.1–6.1). There were no significant differences between groups in pain intensity, extension or external rotation movements. The placebo technique showed its ability to blind participants to group allocation. None of the participants suffered any adverse effects from diacutaneous fibrolysis. Conclusion: Diacutaneous fibrolysis may be an effective and safe therapeutic option to improve active range of motion in patients suffering from painful shoulder.

A microwave study of hydrogen-transfer-triggered methyl-group rotation in 5-methyltropolone

We present here the first experimental and theoretical study of the microwave spectrum of 5-methyltropolone, which can be visualized as a seven-membered "aromatic" carbon ring with a five-membered hydrogen-bonded cyclic structure at the top and a methyl group at the bottom. The molecule is known from earlier studies in the literature to exhibit two large-amplitude motions, an intramolecular hydrogen transfer and a methyl torsion. The former motion is particularly interesting because transfer of the hydrogen atom from the hydroxyl to the carbonyl group induces a tautomerization in the molecule, which then triggers a 60° internal rotation of the methyl group. Measurements were carried out by Fourier-transform microwave spectroscopy in the 8-24 GHz frequency range. Theoretical analysis was carried out using a tunneling-rotational Hamiltonian based on a G(12)(m) extended-group-theory formalism. Our global fit of 1015 transitions to 20 molecular parameters gave a root-mean-square deviation of 1.5 kHz. The tunneling splitting of the two J=0 levels arising from a hypothetical pure hydrogen-transfer motion is calculated to be 1310 MHz. The tunneling splitting of the two J=0 levels arising from a hypothetical pure methyl top internal-rotation motion is calculated to be 885 MHz. We have also carried out ab initio calculations, which support the structural parameters determined from our spectroscopic analysis and give estimates of the barriers to the two large-amplitude motions.

Comparison of Shoulder Range of Motion, Strength, and Playing Time in Uninjured High School Baseball Pitchers Who Reside in Warm- and Cold-Weather Climates

Background: There is an assumption that baseball athletes who reside in warm-weather climates experience larger magnitude adaptations in throwing shoulder motion and strength compared with their peers who reside in cold-weather climates. Hypotheses: (1) The warm-weather climate (WWC) group would exhibit more pronounced shoulder motion and strength adaptations than the cold-weather climate (CWC) group, and (2) the WWC group would participate in pitching activities for a greater proportion of the year than the CWC group, with the time spent pitching predicting throwing shoulder motion and strength in both groups. Study Design: Cross-sectional study; Level of evidence, 3. Methods: One hundred uninjured high school pitchers (50 each WWC, CWC) were recruited. Rotational shoulder motion and isometric strength were measured and participants reported the number of months per year they pitched. To identify differences between groups, t tests were performed; linear regression was used to determine the influence of pitching volume on shoulder motion and strength. Results: The WWC group pitched more months per year than athletes from the CWC group, with the number of months spent pitching negatively related to internal rotation motion and external rotation strength. The WWC group exhibited greater shoulder range of motion in all planes compared with the CWC group, as well as significantly lower external rotation strength and external/internal rotation strength ratios. There was no difference in internal rotation strength between groups, nor a difference in the magnitude of side-to-side differences for strength or motion measures. Conclusion: Athletes who reside in cold- and warm-weather climates exhibit differences in throwing shoulder motion and strength, related in part to the number of months spent participating in pitching activities. The amount of time spent participating in pitching activities and the magnitude of range of motion and strength adaptations in athletes who reside in warm-weather climates may make these athletes more susceptible to throwing-related injuries.

ChemInform Abstract: Conformational Studies by Liquid Crystal NMR and ab initio Calculations: Methyl Nicotinate and Methyl Isonicotinate.

Abstract Conformational properties of methyl nicotinate and methyl isonicotinate have been studied by liquid crystal 1 H-NMR spectroscopy combined with ab initio calculations. The solvent used is a mixture of 80 mol.% of EBBA and 20 mol.% of MBBA.Ab initio calculations have been performed with 4-21G and MINI-4 basis sets to estimate molecular structures and the potential functions for internal rotation. Some structural parameters and the energy difference between rotational isomers have been refined by using observed dipolar coupling constants. The correlation between internal rotation and reorientational molecular motion has been taken into account according to the theory of Emsley, Luckhurst and Stockley. The parameters of the mean external potential are found to take similar values for methyl nicotinate and methyl isonicotinate. The energy difference of the two stable conformers of methyl nicotinate is in agreement with the analysis neglecting the correlation between the two motions.

Comprehensive Impairment-Based Exercise and Manual Therapy Intervention for Patients With Subacromial Impingement Syndrome: A Case Series

Case series. Few studies have defined the dosage and specific techniques of manual therapy and exercise for rehabilitation for patients with subacromial impingement syndrome. This case series describes a standardized treatment program for subacromial impingement syndrome and the time course and outcomes over a 12-week period. Ten patients (age range, 19-70 years) with subacromial impingement syndrome defined by inclusion and exclusion criteria were treated with a standardized protocol for 10 visits over 6 to 8 weeks. The protocol included a 3-phase progressive strengthening program, manual stretching, thrust and nonthrust manipulation to the shoulder and spine, patient education, activity modification, and a daily home exercise program of stretching and strengthening. Patients completed a history and measures of impairments and functional disability at 2, 4, 6, and 12 weeks. Treatment success was defined as both a 50% improvement on the Disabilities of the Arm, Shoulder, and Hand (DASH) score and a global rating of change of at least "moderately better." At 6 weeks, 6 of 10 patients had a successful (mean +/- SD) DASH outcome score (initial, 33.9 +/- 16.2; 6 weeks, 8.1 +/- 9.2). At 12 weeks, 8 of 10 patients had a successful DASH outcome score (initial, 33.1 +/- 14; 12 weeks, 8.3 +/- 6.4). As a group, the largest improvement was in the first 2 weeks. The most common impairments for all 10 patients were rotator cuff and trapezius muscle weakness (10 of 10 patients), limited shoulder internal rotation motion (8 of 10 patients), and reduced kyphosis of the midthoracic area (7 of 10 patients). A program aimed at strengthening rotator cuff and scapular muscles, with stretching and manual therapy aimed at thoracic spine and the posterior and inferior soft-tissue structures of the glenohumeral joint appeared to be successful in the majority of patients. This case series describes a comprehensive impairment-based treatment which resulted in symptomatic and functional improvement in 8 of 10 patients in 6 to 12 weeks. Therapy, level 4.

Does slower rehabilitation after arthroscopic rotator cuff repair lead to long-term stiffness?

Conservative rehabilitation after arthroscopic rotator cuff repair does not result in long-term stiffness and improves rates of tendon healing. We retrospectively evaluated 43 patients with full-thickness rotator cuff tears who underwent a standardized, conservative protocol of full-time sling immobilization without formal therapy for 6 weeks after arthroscopic repair. At 6 to 8 weeks of follow-up, we categorized patients as "stiff" if they demonstrated forward elevation of less than 100° and external rotation of less than 30° passively; all others were designated "nonstiff." Active range of motion in forward elevation, external rotation, and internal rotation was assessed at 3 months, 6 months, and 1 year. American Shoulder and Elbow Surgeons (ASES) and Constant-Murley scores were assessed at 1 year. Follow-up magnetic resonance imaging (MRI) was obtained in all patients to assess tendon healing. Ten patients (23%) were considered stiff after rotator cuff surgery. At 1 year, there was no difference in mean forward elevation (166° vs 161°, P = .2), external rotation (62° vs. 58.4°, P = .5), or internal rotation (T7.4 vs T8.2, P = .07) between the stiff and nonstiff groups, respectively. There were no differences in final ASES (83 vs 79, P = .57) and Constant-Murley scores (77 vs. 74, P = .5). Repeat MRI suggested a trend toward a lower retear rate among the stiff patients (70% intact in stiff group vs 36% in nonstiff group, P = .079). Two clinically significant cuff retears occurred in the nonstiff cohort. Concerns for recalcitrant stiffness have led some to favor early postoperative therapy. We found that early restriction of motion did not lead to long-term stiffness after arthroscopic rotator cuff repair, even in patients who were clinically stiff in the early postoperative period. Sling immobilization for 6 weeks after arthroscopic rotator cuff repair does not result in increased long-term stiffness and may improve the rate of tendon healing.

Forces across the middle of the intact clavicle during shoulder motion

The optimal management of displaced middle third clavicle fractures is currently under investigation. Advances in fracture fixation technology have expanded the indications for operative fracture management. Data are currently unavailable regarding the normal forces and moments that occur in the middle clavicle with motion of the glenohumeral joint. This study tested our null hypothesis that active range of motion in internal rotation, external rotation, and abduction would produce a similar magnitude of force across the middle clavicle. Clavicle forces were measured in 6 whole fresh frozen cadavers using a 6 degree-of-freedom load cell mounted to the middle third of the clavicle. The rotator cuff tendons were isolated, divided, and connected to a system of weights. The forces across the clavicle in 3 orthogonal directions were quantified during simulated active abduction, internal rotation, and external rotation. There were statistically greater axial compressive force and torque in the clavicle during humeral abduction compared with internal or external rotation. During external rotation, there were statistically greater tensile forces compared with abduction or internal rotation. There were no statistical differences in the superior-inferior or anterior-posterior forces with the 3 motions studied. Overall, active abduction caused the greatest increase in middle clavicle forces and torque. Abduction resulted in the most significant axial compressive force, whereas active external rotation caused the greatest tensile force across the intact middle clavicle. To our knowledge, these findings represent the first results describing the forces across the intact clavicle during glenohumeral motion. These data can be used to aid clinicians in treating these fractures, guide the design of future biomechanical studies, and develop rehabilitation protocols.

Calculated cross sections for transport coefficients of H 2 dilute in He and HI gas

Relaxation cross sections determining transport coefficients of the binary systems He–H 2 and HI–H 2 have been calculated by using the Waldmann–Snider formalism of the linearized collision operator. After starting with the rotational relaxation times, which are determined by inelastic rotational transitions only, all the following contributions of relaxation cross sections to the binary transport coefficients of the viscosity, heat conductivity, and diffusion have been confined to the valid isotropic approximations, i.e. containing results of elastic collisions, which are only slightly corrected by inelastic effects. Cross sections of the pure gas components have not been done in this paper. The prepared input data have been differential cross sections of a sufficient number of energies and enough initial rotational j states of the molecules to produce converged results at temperatures from 5 K up to 1000 K. Convergence with regard to the contributed j states are shown in figures, the resulting numbers of the cross sections are printed in tables for temperatures up to 600 K. The results show almost identical cross sections for the ortho-H 2 and para-H 2 gas components in relaxation cross sections of purely translational motion, whereas cross sections pertaining purely internal rotational motion are significantly different for para-H 2 and ortho-H 2, and cross sections pertaining coupling of rotational–translational motion could be shown to be negligible as demonstrated in figures.

Ankle Stability in Simulated Lateral Ankle Ligament Injuries

We performed a laboratory-based study of the ankle-hindfoot complex in normal cadaveric ankles with simulated lateral ankle ligament injuries, utilizing an ankle stability testing device. The ankle stability testing device distinguished between intact, injury to anterior talofibular ligament (ATFL) and combined injury to ATFL and calcaneofibular ligament (CFL). Ankles were tested in an ankle stability testing device, with a specified inversion torque applied through the range of sagittal plane motion, then internal rotation torque applied through the entire range of sagittal plane motion. Three-dimensional motion of the calcaneus and talus in relation to the tibia were determined with a magnetic tracking system. The specimens were tested in the intact condition, then after sectioning the ATFL, then the CFL. Upon sectioning the ATFL, there was a significant increase in the internal rotation motion at the tibiotalar joint. Subsequent sectioning of the CFL did not significantly increase ankle-hindfoot internal rotation, but it did significantly increase the motion in inversion testing. This increase occurred primarily at the tibiotalar level. The isolated ATFL injury was clearly distinguished from the intact condition by increased talar-tibial internal rotation, but not inversion. The more severe combined ATFL/CFL injury was distinguished from the ATFL injury condition with inversion torque. Inversion torque may disclose combined ATFL/CFL injury, and internal rotation torque may be the key to distinguish isolated ATFL and combined ATFL/CFL injuries.

Contact between the coracoacromial arch and the rotator cuff tendons in nonpathologic situations: A cadaveric study

A recent ultrasound study has shown that impingement phenomenon was observed in healthy shoulders. We hypothesized that nonpathologic contact beneath the coracoacromial arch occurs in normal shoulders. Seven fresh-frozen cadaveric shoulders were studied. Each specimen was attached to a custom-designed shoulder-positioning device. A 22-N force was applied to the humeral head to keep it centered in the glenoid fossa. Contact pressure beneath the coracoacromial arch was measured by a flexible force sensor during flexion, abduction, internal and external rotation, extension, and horizontal abduction motions. Bending deformation of the coracoacromial ligament was measured by a linear variable differential transducer sensor. Data were recorded with the arm from 0 degrees to maximum range of motion with 10 degrees increments. Contact pressure with the coracoacromial ligament and acromion was not zero in the neutral position and increased during particular motions, such as flexion, abduction, horizontal abduction, and extension, whereas it was almost constant during internal and external rotation. Bending deformation of the coracoacromial ligament during flexion, abduction, and horizontal abduction motions was also shown to be greater than that during internal and external rotation. It is possible that repetitive contact of the coracoacromial ligament may cause degenerative changes, and a ridge of proliferative acromial spurs may be the result of nonpathologic contact. Contact phenomenon of the coracoacromial arch was observed during all motions. Nonpathologic contact beneath the coracoacromial arch may be present in normal shoulders.

Establishment of 3-dimensional finite element model of human knee joint and its biomechanics

To establish a 3-dimensional (3-D) finite element knee model in healthy Chinese males, to verify the validity of the model, and to analyze the biomechanics of this model under axial load, flexion moment, varus/valgus torque, and internal/external axial torque. A set of consecutive transectional computerized tomography images of normal male knee joints in upright weight-bearing position was selected. With image processing and inversion technology, the 3-D finite element model of the normal knee joint was established through the software ABAQOUS/STANDARD Version-6.5.Biomechanical analysis of this model was processed under axial load, flexion moment, varus/valgus torque, and internal/external axial torque. A 3-D finite element model of healthy Chinese males was successfully established. The ranges of motion of varus and valgus were both small and the difference between them has no statistical significance (P>0.05). The motion of internal and external rotation of the knee took place only in flexion situation.The range of motion of external rotation was larger than that of internal rotation in the same knee (P<0.05). The 3-D geometrical model of the knee resembles the actual knee segments. It can imitate the knee response to different loads. This model could be used for further study on knee biomechanics.

Influence of Lower Limb Clinical Physical Measurements of Female Athletes on Knee Motion During Continuous Jump Testing

Objectives: To assess the relationship between dynamic knee motion in female athletes during landing after jumping and lower limb clinical physical measurements, considered risk factors for anterior cruciate ligament (ACL) injury. We proposed that (1) knee valgus and flexion angles during landing are correlated with clinical physical measurements; (2) combining these measurements enables prediction of the knee valgus and flexion angles during landing. Methods: Sixty-one female collegiate basketball athletes performed a continuous jump test; the peak knee valgus and flexion angles were measured. The Q-angle, the ranges of motion (ROMs) of hip internal rotation (IR) and external rotation (ER), as well as ankle dorsiflexion (DF), navicular drop, leg-heel alignment, and balance ability as assessed by the Star Excursion Balance Test (SEBT) were measured. Stepwise linear regression analyses were used to assess whether these factors can predict the peak knee valgus or flexion angle. Results: Increased ROM of hip IR and navicular drop predicted 7.9% of the peak knee valgus angle variance. Increased ROMs of ankle DF and hip IR, navicular drop, and anterior balance predicted 29.0% of the peak knee flexion angle variance. The knee valgus and flexion angles during the continuous jump test were slightly correlated with clinical physical measurements. Conclusions: Proximal and distal joint alignment and balance ability influence knee motion during landing. The relationship between knee motion during landing and these factors is weak; therefore, lower limb movement during landing is almost independent of clinical physical measurements, and knee movement should be evaluated by itself.