Elbow Valgus Laxity May Result in an Overestimation of Apparent Shoulder External Rotation During Physical Examination

• Published in: The American journal of sports medicine Vol. 36; no. 5; pp. 978 - 982
• Main Authors: Minata, Teruhisa, Safran, Marc R., McGarry, Michelle H., Abe, Muneaki, Lee, Thay Q.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA American Orthopaedic Society for Sports Medicine 01-05-2008; SAGE Publications; Sage Publications, Inc; Sage Publications Ltd
• Subjects: Aged; Aged, 80 and over; Biological and medical sciences; Cadaver; Diseases of the osteoarticular system; Dislocation; Elbow; Elbow Joint - physiopathology; Humans; Joint Instability; Knee; Ligaments; Medical sciences; Methods; Physical Examination; Physical therapy; Range of Motion, Articular; Shoulder; Shoulder dislocation; Shoulder joint; Shoulder Joint - physiopathology; Sports medicine; Therapeutics, Physiological; United States; elbow valgus laxity; physical examination; shoulder external rotation; Ergonomics; Laxity; Shoulder; External; Elbow; Rotation
• ISSN: 0363-5465; 1552-3365
• DOI: 10.1177/0363546507313086

Background: The contributions of the scapulothoracic articulation and spine when measuring shoulder range of motion have been well described;
however, the effect of elbow valgus laxity has not.
Hypothesis: Increased elbow valgus laxity affects the assessment of shoulder external rotation measured during physical examination at
90° of elbow flexion.
Study Design: Controlled laboratory study.
Methods: Seven cadaveric upper extremities were tested with an elbow valgus laxity–testing device. Shoulder external rotation was
assessed with 2.8 N · m of external torque by measuring a change in the angle of the forearm axis at 90° of elbow flexion.
Elbow valgus laxity was measured in degrees of valgus angulation with 1.5 N · m of valgus torque with the humerus fixed. Shoulder
external rotation and elbow valgus laxity were recorded at each of the following conditions: (1) intact, (2) after splitting
the pronator muscles and venting the capsule, (3) after cutting the posterior band of the anterior oblique ligament of the
ulnar collateral ligament, and (4) after cutting the anterior oblique ligament completely.
Results: After the posterior band of the anterior oblique ligament of the ulnar collateral ligament was cut, apparent shoulder external
rotation and elbow valgus laxity were increased by 4.1° ± 1.7° ( P < .01) and 3.1° ± 1.3° ( P < .001), respectively, when compared with the intact condition. Complete cutting of the anterior oblique ligament resulted
in an apparent increased shoulder external rotation and an increased elbow valgus laxity of 11.0° ± 1.1° ( P < .001) and 9.1° ± 1.2° ( P < .001), respectively, when compared with the intact condition.
Conclusion: Shoulder external rotation as assessed by physical examination, which was defined as the angle of the forearm axis, as well
as elbow valgus laxity, was significantly increased after the anterior oblique ligament of the ulnar collateral ligament was
cut, although the glenohumeral joint condition was not changed.
Clinical Relevance: Elbow valgus laxity may cause an overestimation of shoulder external rotation on clinical examination of the shoulder.
Keywords:
elbow valgus laxity
shoulder external rotation
physical examination