Biomedical subjects

M Urayama

Publications and source records attributed to M Urayama.

22 records · Page 2Linked to original sources

PubMedDate not supplied

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 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.

Aged↗

PubMedDate not supplied

Effect of superior capsule and coracohumeral ligament release on strain in the repaired rotator cuff tendon. A cadaveric study.

Twelve cadaveric shoulders were used to determine the effects of release of the superior capsule and the coracohumeral ligament on the strain in the repaired rotator cuff tendon. A rotator cuff tear (2 cm wide and 1.5 cm long) was created and repaired under a 3-kg tensile force. The strain in the repaired tendon was measured with use of linear transducers with the arm in 50 different positions. Release of either the superior capsule or the coracohumeral ligament diminished the tension of the repaired rotator cuff by an average of 25% with the arm in adduction. Release of both of these structures further reduced the tension by an average of 44% in adduction and 43% to 60% with the arm in 15 degrees of elevation. The maximum reduction of tension in the repaired rotator cuff occurred when both the superior capsule and coracohumeral ligament were divided and when the arm was positioned in adduction and in 60 degrees of external rotation. Release of the coracohumeral ligament is equally as efficient as releasing the superior capsule in reducing the strain of the repaired rotator cuff. Releasing both structures seems to be desirable when releasing one structure or the other is not sufficient.

Aged↗

PubMedDate not supplied

Effect of arm elevation and rotation on the strain in the repaired rotator cuff tendon. A cadaveric study.

In 14 cadaveric shoulders, a rotator cuff tear (2 cm wide and 1.5 cm long) was created and repaired under a 3-kg tensile force with the arm in adduction. Strain on the repaired tendon was measured at 0 degrees, 15 degrees, 30 degrees, and 45 degrees of elevation in the sagittal, scapular, and coronal planes and from 60 degrees of internal rotation to 60 degrees of external rotation. The strain in all of the planes decreased significantly with the arm elevated more than 30 degrees. With 30 degrees of elevation in the scapular and coronal planes, the strain increased in internal rotation and decreased in external rotation. In all of the positions measured, the strain in the sagittal plane was significantly greater than in the other planes. We concluded that more than 30 degrees of elevation in the coronal or scapular plane and rotation ranging from 0 degrees to 60 degrees of external rotation compose the safe range of motion after repair of the rotator cuff.

Aged↗

PubMedDate not supplied

Which is more useful, the "full can test" or the "empty can test," in detecting the torn supraspinatus tendon?

The purpose of this study was to determine the clinical usefulness of the full can and empty can tests for determining the presence of a torn supraspinatus tendon. The two tests were performed in 143 shoulders of 136 consecutive patients. In each test, the muscle strength was determined by manual muscle testing, and the presence of pain during the maneuver was recorded. We interpreted the tests as positive when there was 1) pain, 2) muscle weakness, or 3) pain or muscle weakness or both. Shoulders were examined by high-resolution magnetic resonance imaging with 95% accuracy for full-thickness rotator cuff tears. There were 35 shoulders with full-thickness tears of the supraspinatus tendon. The accuracy of the tests was the greatest when muscle weakness was interpreted as indicating a torn supraspinatus tendon in both the full can test (75% accurate) and the empty can test (70% accurate). However, there was no significant difference between the accuracy of the tests when this criterion was used. Pain was observed in 62 shoulders (43%) during the full can test and in 71 shoulders (50%) during the empty can test, but the difference was not statistically significant. Muscle weakness should be interpreted as indicative of supraspinatus tendon tear. Using this indicator, both tests are equivalent in terms of accuracy, but considering pain provocation, the full can test may be more beneficial in the clinical setting.

Adolescent↗