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Characterization of glenohumeral joint laxity and stiffness using instrumented arthrometry
The purpose of this study was to characterize glenohumeral joint laxity and
stiffness using instrumented arthrometry. To evaluate the validity of an instrumented
measurement system we compared cutaneous and bone-pinned measures of laxity and
stiffness that replicate previously reported in vivo methodology. Characterization of
capsular laxity was achieved through determination of the sagittal plane translational area
at increasing levels of quantified force. Finally, a method for increasing the objectivity of
the standard manual laxity examination was developed for the orthopaedic clinician to
quantify humeral head translation and capsular volume in vivo. We hypothesized that: 1)
cutaneous measures could accurately predict bone-pinned measures, 2) capsular laxity
would increase with increasing levels of applied force, and 3) manual cutaneous, manual
bone-pinned, and force-displacement bone-pinned measures of translation would be
equal.
Thirty fresh frozen cadaveric shoulder specimens (mean age=70±14 years)
were tested. The shoulders were thawed and mounted to a custom-made shoulder-testing
apparatus. Displacement was measured using an electromagnetic tracking system.
Sensors were secured cutaneously and with bone-pins to the scapula and humerus.
Force-displacement testing was performed using a load applicator and manual
displacement testing utilized the anterior/posterior drawer and inferior sulcus tests.
A comparison of cutaneous and bone-pinned measures of laxity and stiffness
revealed good to excellent criterion validity (r=0.68 to 0.79). Examination of
displacement measures at increasing levels of force revealed increasing capsular laxity
with symmetric directional compliance. No significant difference was observed between
anterior and posterior translation (0.4 mm, p=.55), with significant differences between
inferior and anterior (4.6 mm, p<.0001) and between inferior and posterior (5.1 mm,
p<.0001). A comparison of manual cutaneous to bone-pinned manual and kinetic
measures of translation revealed a significant difference between methods (p=.0024)
and between directions (p<.0001) with no significant interaction (p=.0948). Estimations
of the force required to achieve clinical end-point suggest that greater force is required in
the anterior (173 N) direction compared to posterior (123 N) and inferior (121 N).
We have developed two new methods to measure glenohumeral joint kinematics
and reported new information regarding normal kinematics of the glenohumeral joint
Instrumented measurement of glenohumeral joint laxity: reliability and normative data
This study assessed shoulder laxity using an instrumented arthrometer. We compared anterior and posterior translations at various force levels to determine the reliability of our measurement technique and to provide normative data in healthy shoulders. Fifty shoulders were assessed for glenohumeral joint laxity in two directions (anterior and posterior) and at four force levels (67, 89, 111, and 134 N). The dependent measure was joint displacement. Laxity values were widely, yet normally, distributed in our group of healthy shoulders. Intraclass correlation coefficients revealed excellent between-trial reliability (0.92) and fair between-session (0.73) and between-examiner (0.74) reliability. The average standard error of measurement between trials (0.56 mm), sessions (1.5 mm), and examiners (1.7 mm) demonstrated an unprecedentedly high degree of precision for quantifying glenohumeral joint laxity. Paired t tests revealed no significant laxity differences between sides ( P >0.05), indicating bilateral symmetry. A 2 (direction) Ă— 4 (force) analysis of variance revealed significant differences in laxity between directions ( P <0.0001) and force levels ( P <0.0001). Our results show that our instrumented technique for quantifying glenohumeral joint laxity is precise and reproducible. Posterior translation was significantly greater than anterior, and a significant increase in translation was observed between increasing levels of force.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41911/1/167-9-1-34_s001670000174.pd
The association between generalized joint hypermobility and active horizontal shoulder abduction in 10–15 year old competitive swimmers
Lawson criterion for ignition exceeded in an inertial fusion experiment
For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37Â MJ of fusion for 1.92Â MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion
Chemical ionization pathways of polyfluorinated chemicals—A connection to environmental atmospheric processes
The proton affinity of proline analogs using the kinetic method with full entropy analysis
The Effect of Carbohydrate, Caffeine and Combined Rinses on College Aged Females’ Cycling Endurance Performance
Please view abstract in the attached PDF fil
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