ABSTRACT
Objective To evaluate the correlation between the Waters classification based on shoulder CT or MRI scan and passive shoulder external rotational angle before operation in the glenohumeral joint deformity caused by shoulder internal rotational contracture secondary brachial plexus birth palsy.Methods 33 patients suffered the shoulder internal rotational contracture secondary brachial plexus birth palsy (Tassin classification Ⅱ 19, Ⅲ 13, Ⅳ 1) including 12 girls and 21 boys, ranging from 10 months to 16 years old with an average of 4.5 years old, underwent either CT or MR examination in shoulder joint. The retroversion of the glenoid (glenoscapular angle) and the ratio of humeral head posterior subluxation were measured on the CT or MRI images according to the method described by Friedman. The deformity of glenohumeral joint was classificated according to the Waters criteria, while the passive shoulder external rotational angle was measured at neutral position in involved shoulder joint. The correlation between the external rotation and the deformity was analysed. Results 33 cases with shoulder internal rotational contracture secondary brachial plexus birth palsy were evaluated according to the Waters criteria. 4 cases were classified as typeⅠdeformity, 4 cases as typeⅡ, 7 cases as type Ⅲ, 6 cases as type Ⅳ; 5 cases as typeⅤ; 7 case as type Ⅵ. The type of glenohumeral deformity was significantly associated with the limited range of passive external rotation of the shoulder joint. Conclusion The Waters classification of the glenohumeral deformity according to the Waters criteria can accurately demonstrated the deformity of the glenohumeral joint caused by shoulder internal rotational contracture secondary to brachial plexus birth palsy.