Superior Labral Strain during the Throwing Motion: A Cadaveric Study

We studied the strain on the superior labrum of 10 fresh-frozen cadaveric shoulders with the arm in simulated positions of a pitching motion. We used linear transducers to measure the strain in both the anterior and posterior superior labrum with the arm in various planes and rotations simulating th...

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Bibliographic Details
Published in:The American journal of sports medicine 2001-07, Vol.29 (4), p.488-492
Main Authors: Pradhan, Rabindra L., Itoi, Eiji, Hatakeyama, Yuji, Urayama, Masakazu, Sato, Kozo
Format: Article
Language:English
Subjects:
Aged
Aged, 80 and over
Arm - physiology
Biological and medical sciences
Cadaver
Humans
Humerus - physiology
Medical sciences
Middle Aged
Movement - physiology
Range of Motion, Articular - physiology
Scapula - physiology
Shoulder
Shoulder Joint - physiology
Sport (general aspects)
Sports - physiology
Sports injuries
Sports medicine
Stress, Mechanical
Traumas. Diseases due to physical agents
Citations: Items that this one cites
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Summary:We studied the strain on the superior labrum of 10 fresh-frozen cadaveric shoulders with the arm in simulated positions of a pitching motion. We used linear transducers to measure the strain in both the anterior and posterior superior labrum with the arm in various planes and rotations simulating the motions of pitching: early cocking, late cocking, acceleration, deceleration, and follow-through. Predetermined loads, according to the percent of maximum voluntary contraction of the biceps muscle during each phase of pitching, were calculated and applied to the long head of the biceps tendon using a spring device. Only during the late cocking phase, when the arm was in maximal external rotation, was the increase in strain statistically significant for the anterior and posterior portions and the strain on the posterior portion significantly greater than that on the anterior portion of the labrum. The increased strain in the posterior portion may be due to the anatomic orientation of the long head of the biceps tendon at the superior labrum. The increased strain in the late cocking phase may contribute to the detachment of the labrum with the eccentric contraction of the biceps muscle that occurs with rapid extension of the elbow.
ISSN:0363-5465
1552-3365
DOI:10.1177/03635465010290041801