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The hyperabduction test
1Orthopaedic Department, Bicêtre Hospital, Paris-South University and the Institute of Anatomy, France.
The Journal of Bone and Joint Surgery. British Volume
|March 14, 2001
Summary
The range of passive abduction (RPA) in normal shoulders is constant. Increased RPA over 105 degrees in unstable shoulders indicates inferior glenohumeral ligament laxity.
Area of Science:
- Orthopedics
- Anatomy
- Biomechanics
Background:
- The range of passive abduction (RPA) is a key indicator of shoulder joint health.
- The inferior glenohumeral ligament plays a crucial role in shoulder stability.
Purpose of the Study:
- To determine the normal range of passive abduction in healthy shoulders.
- To investigate the relationship between RPA and shoulder instability.
- To identify anatomical factors associated with shoulder instability.
Main Methods:
- Studied 100 fresh human cadaver shoulders (mean age 76).
- Measured RPA in 100 healthy volunteers and 90 patients with shoulder instability over six years.
- Correlated RPA measurements with anatomical findings and clinical tests.
Main Results:
- Passive abduction occurs solely within the glenohumeral joint.
- The inferior glenohumeral ligament controls passive abduction, showing a constant value in 95% of normal shoulders.
- 85% of patients with shoulder instability exhibited an RPA exceeding 105 degrees, compared to 90 degrees in their contralateral shoulder.
- An RPA > 105 degrees is linked to inferior glenohumeral ligament lengthening and laxity.
Conclusions:
- An elevated RPA (> 105 degrees) is a significant indicator of shoulder instability.
- Inferior glenohumeral ligament laxity is a primary factor contributing to increased RPA and instability.
- RPA measurement is a valuable diagnostic tool for assessing shoulder joint stability.