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. / Graduation date: 2001
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/32564 |
| Date | 05 June 2000 |
| Creators | Sauers, Eric L. |
| Contributors | Borsa, Paul A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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