- Email: [email protected]
Shoulder proprioception: Effect of joint laxity, joint position, direction of motion, and muscle fatigue
J. Shoulder Elbow Surg. January~February 1995
$34 Abstracts
69
POSTERIOR GLENOHUMERAL JOINT S T A B I L I Z A T I O N IN A B I O M E C H A N I C A L MODEL R a l n h B B l a s i e r , Louis J Soslowsky, David M Malicky, and Mark L Piamer Orthopaedic Research Laboratories, University of Michigan, Ann Arbor, Michigan, 48109-0328, USA A comprehensive model was used to simultaneously evaluate the relative contributions of the glenohumeral capsular and coracohumeral ligaments, as well as the rotator cuff and biceps muscles on posterior stability through a range of translations. Eight normal shoulders were tested. Four ligamentous zones were defined: the SGHL and MGHL; the IGHL; posterior capsule; and the coracohumeral ligament. Seven muscles were modeled: supraspinatus, subscapularis, combined external rotators, anterior and middle deltoid muscles, pectoralis major, and long biceps. Low friction pneumatic cylinders applied simulated muscle forces. The arm was raised to 90 ° of forward flexion using an active joint positioning technique. Shoulders were tested with internal and external rotation. Posterior shoulder stability was defined as the force required to sublux the joint through a specified displacement. Subscapularis is by far the most important muscular stabilizer against posterior subluxation. In internal rotation, the long biceps is a destabilizer, aggravating posterior instability. The coracohumeral ligament is a dramatic stabilizer at higher displacements. Prior studies of posterior shoulder instability have not been performed with the arm in the clinically most interesting position and have not shown the large stability effects of the subscapularis and the coracohumeral ligament.
71
SENSORY INNVERATION OF THE SHOULDER JOI!~F.K. Golser,G.Sperner,CHauser, G.Hacker,H.Reschy Saria Department of Traumatology University lrmsbruck Materials and methods: Substance-P and calcitonin gene related peptide (CGRP) are nociceptive neuroU'ansmitters, therefore their presence in the soft tissue indicate sensory nerve fibres that may be responsible for pain transmittion and reflex mechanism. The specimens were obtained from a 23 year old male multiorgan donor from the following sites: Supraspinatus tendon. subscapularis tendon, coracoacromial ligament, anterior and posterior capsulo-labral complex and capsular tissue from the axillary pouch. Each specimen was analysed by qualitative double inmaunofluoroscopy to detect substance-P and CGRP nerve fibres histologically, and radio immunoassay to quantify substance-P and CGRP. Results We found very high levels of substance-P and CGRP in the coracoacromial ligament (l 0 to 20 times higher than in all the other specimens), and high levels of both neurotransmitters in the anterior and posterior-inferior capsulo-labral complex. Additionally we foand twice as much higher concentrations ofneuropeptides within tbe interior glenohumeral ligmnents in the axillar3 pouch Conclusion: These results may suggest a clinical correlation between the concentration of nociceptive nerve fibres in the coracoacromial ligament and the positive clinical response alter acromioplast) in the treatment of impingement syndromes. The higher amounts of nociceptive nerve fibres in the inferior capsular complex could explain the proprioceptive function of these anatomical stnmtures in shoulder instability.
70
S H O U L D E R PROPRIOCEPTION: EFFECT OF JOINT LAXITY, JOINT POSITION, DIRECTION OF MOTION, A N D MUSCLE FATIGUE. RB Blasier, MD, JE Carpenter, MD, LJ H u s t o n , MS*, The University of Michigan, Ann Arbor, MI 48109. Recently, considerable i m p o r t a n c e has been ascribed to s h o u l d e r stability w h i c h m a y be provided by active muscle forces. Normal h u m a n s h o u l d e r p r o p r i o c e p t i o n has not yet b e e n thoroughly characterized. In this study, 38 subjects with entirely normal shoulders, including some with generalized joint laxity, had their shoulder p r o p r i o c e p t i o n s t u d i e d by m e a s u r e m e n t of detection by the subjects of humeral axial rotation. Clinically "tight" individuals had significantly smaller detection threshold angle than subjects with "generalized joint laxity" (p<0.002). Proprioception for external rotation was significantly more sensitive than proprioception for internal rotation (p<0.001). Rotation-detection sensitivity to external rotation was f o u n d to vary significantly with position (p= 0.005). In positions of m o r e external rotation, detection was more sensitive. In both internal and external rotation, muscular fatigue resulted in decreased sensitivity to humeral rotation.
72
ANATOMIC EVALUATION OF THE SUPERIOR LABRUM AND SLAP LESIONS WITH CT ARTHROGRAPHV AND MR ARTHROGRAPH¥
Blum, A., Resler, F.B., Regent, D., Roland, J., Mole, D. (France) Purpose : to study the value of CT arthrography and MR arthrography (without gadolinium) in the detection of slap lesions. Material and methods : 23 fresh cadaveric shoulders underwent CT arthrography (Telebrix 70 mg I/ ml), Mr arthrography (using the same contrast material) and subsequently underwent anatomic verification. CT arthrography was performed with axial and coronal contiguous 3 mm thick slices. Mr arthrography was performed on a 1,5 T unit wiih a surface coil and axial and coronal FSE T2 weighted images with fat supression and 3 mm thick slices. Slap lesions were classified according to snyder classification. Hypertrophic or hypotrophic labra were not consider pathological. Results : after anatomic verification, there were 1 type 4, 2 type 3, 1 type 2 and 1 type 1 slap lesions. In 15 cases a partial or complete rotator cuff tear was present. In one case, a Bankart lesion was noted. The sensitivity and specificity of CT arthrography in the diagnosis of slap lesions were repectively 60 % and 94 %. They were respectively of 80 % and 83 % with MR arthrography. C O N C L U S I O N : in ideal condition, type 3 and 4 slap lesions are well detected with CT arthrography and MR arthrography. These techniques are probably less efficient in patients, and a normal exam should not rule out the diagnosis of slap lesions.
$34 Abstracts
69
POSTERIOR GLENOHUMERAL JOINT S T A B I L I Z A T I O N IN A B I O M E C H A N I C A L MODEL R a l n h B B l a s i e r , Louis J Soslowsky, David M Malicky, and Mark L Piamer Orthopaedic Research Laboratories, University of Michigan, Ann Arbor, Michigan, 48109-0328, USA A comprehensive model was used to simultaneously evaluate the relative contributions of the glenohumeral capsular and coracohumeral ligaments, as well as the rotator cuff and biceps muscles on posterior stability through a range of translations. Eight normal shoulders were tested. Four ligamentous zones were defined: the SGHL and MGHL; the IGHL; posterior capsule; and the coracohumeral ligament. Seven muscles were modeled: supraspinatus, subscapularis, combined external rotators, anterior and middle deltoid muscles, pectoralis major, and long biceps. Low friction pneumatic cylinders applied simulated muscle forces. The arm was raised to 90 ° of forward flexion using an active joint positioning technique. Shoulders were tested with internal and external rotation. Posterior shoulder stability was defined as the force required to sublux the joint through a specified displacement. Subscapularis is by far the most important muscular stabilizer against posterior subluxation. In internal rotation, the long biceps is a destabilizer, aggravating posterior instability. The coracohumeral ligament is a dramatic stabilizer at higher displacements. Prior studies of posterior shoulder instability have not been performed with the arm in the clinically most interesting position and have not shown the large stability effects of the subscapularis and the coracohumeral ligament.
71
SENSORY INNVERATION OF THE SHOULDER JOI!~F.K. Golser,G.Sperner,CHauser, G.Hacker,H.Reschy Saria Department of Traumatology University lrmsbruck Materials and methods: Substance-P and calcitonin gene related peptide (CGRP) are nociceptive neuroU'ansmitters, therefore their presence in the soft tissue indicate sensory nerve fibres that may be responsible for pain transmittion and reflex mechanism. The specimens were obtained from a 23 year old male multiorgan donor from the following sites: Supraspinatus tendon. subscapularis tendon, coracoacromial ligament, anterior and posterior capsulo-labral complex and capsular tissue from the axillary pouch. Each specimen was analysed by qualitative double inmaunofluoroscopy to detect substance-P and CGRP nerve fibres histologically, and radio immunoassay to quantify substance-P and CGRP. Results We found very high levels of substance-P and CGRP in the coracoacromial ligament (l 0 to 20 times higher than in all the other specimens), and high levels of both neurotransmitters in the anterior and posterior-inferior capsulo-labral complex. Additionally we foand twice as much higher concentrations ofneuropeptides within tbe interior glenohumeral ligmnents in the axillar3 pouch Conclusion: These results may suggest a clinical correlation between the concentration of nociceptive nerve fibres in the coracoacromial ligament and the positive clinical response alter acromioplast) in the treatment of impingement syndromes. The higher amounts of nociceptive nerve fibres in the inferior capsular complex could explain the proprioceptive function of these anatomical stnmtures in shoulder instability.
70
S H O U L D E R PROPRIOCEPTION: EFFECT OF JOINT LAXITY, JOINT POSITION, DIRECTION OF MOTION, A N D MUSCLE FATIGUE. RB Blasier, MD, JE Carpenter, MD, LJ H u s t o n , MS*, The University of Michigan, Ann Arbor, MI 48109. Recently, considerable i m p o r t a n c e has been ascribed to s h o u l d e r stability w h i c h m a y be provided by active muscle forces. Normal h u m a n s h o u l d e r p r o p r i o c e p t i o n has not yet b e e n thoroughly characterized. In this study, 38 subjects with entirely normal shoulders, including some with generalized joint laxity, had their shoulder p r o p r i o c e p t i o n s t u d i e d by m e a s u r e m e n t of detection by the subjects of humeral axial rotation. Clinically "tight" individuals had significantly smaller detection threshold angle than subjects with "generalized joint laxity" (p<0.002). Proprioception for external rotation was significantly more sensitive than proprioception for internal rotation (p<0.001). Rotation-detection sensitivity to external rotation was f o u n d to vary significantly with position (p= 0.005). In positions of m o r e external rotation, detection was more sensitive. In both internal and external rotation, muscular fatigue resulted in decreased sensitivity to humeral rotation.
72
ANATOMIC EVALUATION OF THE SUPERIOR LABRUM AND SLAP LESIONS WITH CT ARTHROGRAPHV AND MR ARTHROGRAPH¥
Blum, A., Resler, F.B., Regent, D., Roland, J., Mole, D. (France) Purpose : to study the value of CT arthrography and MR arthrography (without gadolinium) in the detection of slap lesions. Material and methods : 23 fresh cadaveric shoulders underwent CT arthrography (Telebrix 70 mg I/ ml), Mr arthrography (using the same contrast material) and subsequently underwent anatomic verification. CT arthrography was performed with axial and coronal contiguous 3 mm thick slices. Mr arthrography was performed on a 1,5 T unit wiih a surface coil and axial and coronal FSE T2 weighted images with fat supression and 3 mm thick slices. Slap lesions were classified according to snyder classification. Hypertrophic or hypotrophic labra were not consider pathological. Results : after anatomic verification, there were 1 type 4, 2 type 3, 1 type 2 and 1 type 1 slap lesions. In 15 cases a partial or complete rotator cuff tear was present. In one case, a Bankart lesion was noted. The sensitivity and specificity of CT arthrography in the diagnosis of slap lesions were repectively 60 % and 94 %. They were respectively of 80 % and 83 % with MR arthrography. C O N C L U S I O N : in ideal condition, type 3 and 4 slap lesions are well detected with CT arthrography and MR arthrography. These techniques are probably less efficient in patients, and a normal exam should not rule out the diagnosis of slap lesions.