Journal of shoulder and elbow surgery
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J Shoulder Elbow Surg · Nov 1996
Biomechanical analysis of tension band fixation for olecranon fracture treatment.
This study assessed the strength of various tension band fixation methods with wire and cable applied to simulated olecranon fractures to compare stability and potential failure or complications between the two. Transverse olecranon fractures were simulated by osteotomy. The fracture was anatomically reduced, and various tension band fixation techniques were applied with monofilament wire or multifilament cable. ⋯ All fixation methods were more resistant to posterior loading than to an anterior load. Individual comparative analysis for various loading conditions concluded that tension band fixation is more resilient to tensile forces exerted by the triceps than compressive forces on the anterior olecranon tip. Neither wire passage anterior to the K-wires nor the multifilament cable provided statistically significant increased stability.
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J Shoulder Elbow Surg · Sep 1996
Dynamic stability of the elbow: electromyographic analysis of the flexor pronator group and the extensor group in pitchers with valgus instability.
The medical collateral ligament is a common site of injury in baseball pitchers, causing substantial morbidity and loss of pitching time. Twenty-six skilled baseball pitchers with medial collateral ligament insufficiency were studied before surgery with high-speed cinematography and fine-wire electromyography of eight muscles around the elbow. Data from the pitchers with injured elbows were compared with data obtained from uninjured pitchers. ⋯ The extensor muscles revealed slightly increased activity in the injured elbows; however, this was not statistically significant. Although the muscles of the flexor pronator group (especially the flexor carpi ulnaris muscle and the flexor digitorum superficialis muscles) are anatomically positioned to provide dynamic stability of the elbow, they did not demonstrate increased electrical activity in pitchers with medial collateral ligament deficiencies. This finding suggests that the muscles on the medial side of the elbow do not supplant the role of the medial collateral ligament during the fastball pitch.
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J Shoulder Elbow Surg · Jul 1996
Relationship between calcifying tendinitis and subacromial impingement: a prospective radiography and magnetic resonance imaging study.
In a prospective study radiographs and magnetic resonance images of 75 patients with calcifying tendinitis of the rotator cuff were analyzed. The aim was to evaluate any relation between calcifying tendinitis and subacromial impingement. A total of 83% of the calcifications were located in the supraspinatus or the adjoining part of the subscapularis tendon. ⋯ A partial rotator cuff tear was found in one shoulder; in 11% variable aspects of degenerative alteration of the affected tendon were seen. By analysis of the radiographic outlet view 16% of the cases had a type III acromion. In conclusion, little correlation exists between calcifying tendinitis and additional findings associated with subacromial impingement.
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J Shoulder Elbow Surg · May 1995
Shoulder muscle forces and tendon excursions during glenohumeral abduction in the scapular plane.
Muscle force values and tendon excursions across the glenohumeral joint during unconstrained glenohumeral abduction in the scapular plane were evaluated with a dynamic shoulder testing apparatus. This evaluation was achieved by simulated rotator cuff and middle deltoid activity applied in four plausible muscle force ratios: (1) equal force to each tendon, (2) 2:3 ratio of force applied to the middle deltoid/supraspinatus tendons, (3) 3:2 ratio of force applied to the middle deltoid/supraspinatus tendons, and (4) zero force applied to the supraspinatus tendon to simulate supraspinatus paralysis. The glenohumeral joint was then moved to 5 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, and maximum glenohumeral abduction while muscle forces, tendon excursions, and glenohumeral joint kinematics were monitored. ⋯ Tendon excursion for the middle deltoid (6.4 +/- 0.2 cm) and supraspinatus (3.8 +/- 0.2 cm) were proportionately larger than those for the subscapularis and infraspinatus. Humeral head translations on the glenoid were less than 2 mm in all four conditions evaluated; therefore the glenohumeral joint behaves kinematically as a "ball-and-socket" articulation during glenohumeral abduction. Simulated supraspinatus paralysis does not change normal joint kinematics and does not prevent full glenohumeral abduction.
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J Shoulder Elbow Surg · Mar 1995
Incidence and causes of shoulder girdle injuries in an urban population.
In a prospective population-based study of all shoulder injuries seen at Malmö General Hospital during 1987, the incidence and causes of major injuries involving fractures of the clavicle, scapula, or proximal humerus and glenohumeral or acromioclavicular dislocations were investigated in children, adults, and the elderly. Seventy-five shoulder injuries occurred in children. Sixty-five of them were fractures of the clavicle. ⋯ Two hundred one were fractures of the proximal humerus. The incidence was significantly higher in women; 147 of 247 injuries were caused by an indoor fall. The variations among age groups are probably attributable to age-related differences in activity, mobility, and fragility.