| Purpose:The purpose of this article is to,on the one hand,put forward a new static 2d method for glenohumeral fulcrum condition measurement,validate its accuracy via vitro experiment,and on the other hand evaluate in vivo kinematic pattern among different groups of RCTs divided by shoulder functional using a 3d dynamic method.Materials and Methods:In vitro study: Radiography of 12 shoulder specimen were taken in static position as well as “dynamic” position under varied fluoroscopic angle in sagittal and horizontal plane.Glenohumeral fulcrum conditions were evaluated with methods based on height of rotational center measurement and acromio-humeral interval measurement respectively.Results were compare to standard data obtained by 3d method to validate the accuracy of HRC method.In vivo study: 12 RCT patients were divided into 3 groups termed functional RCTs,dysfunctional RCTs and pseudo-paralysis respectively according to their shoulder function.The shoulder motion were tested under a dual fluoroscopic image system and evaluated by means of image-model registration technique.The differences of kinematic behavior among groups were described.Results:In vitro study: under circumstance of AP tangential view in horizontal plane,the minimal deviation of HRC method is 1.924±1.661 mm when the fluoroscopic angle is 0 deg and the deviation climbs up as X-ray beam grows up inclination angle.The maximal deviation takes place as 3.098±1.720 mm at 40 deg inclination angle.When fix the fluoroscopic angle to 0 deg in sagittal plane,the minimal deviation is 1.924±1.661 mm when the anterior rim of glenoid overlies the posterior one.The maximal deviation is 2.770±1.111 mm when the X-ray beam comes at 15 deg from the sternal side.Under standard fluoroscopic angle,the deviation of HRC method(1.924±1.661mm)is lower than which of AHI method(3.461±1.110mm),with p<0.05.In vivo study: regard to group of functional RCTs,the maximal glenohumeral abduction angle is 48.684±2.645 deg.The maximal anterior translation is 1.071±0.850 mm taking place at maximal glenohumeral abduction.The maximal superior translation is 2.047±0.491 mm,taking place at 27.3% of the motion process when glenohumeral abducts by 18.827±3.515 deg.Regard to group of dysfunctional RCTs,the maximal glenohumeral abduction angle is 40.641±1.496° deg.The maximal anterior translation is 1.167±0.633 mm taking place at 45.5% of the motion process when glenohumeral abducts by 20.699±2.684 deg.The maximal superior translation is 2.270±0.452 mm,taking place at 36.4% of the motion process when glenohumeral abducts by 17.112±1.781 deg.Regard to group of pseudo-paralysis,the maximal glenohumeral abduction angle is 11.888±2.763 deg.The maximal anterior translation is 11.888±2.763 mm taking place at maximal glenohumeral abduction.The maximal superior translation is 0.289±0.195 mm mm,taking place at maximal glenohumeral abduction.Varied dynamic patterns of humeral rotational center migration are observed among groups.Conclusion:The first part of this study has described a new method for glenohumeral fulcrum condition evaluating based on 2d static radiography which is clinically feasible,reliable and easily accessible,and its accuracy has been validated under standard fluoroscopic angle comparing to traditional AHI-based method.The second part of the study has demonstrated the varied kinematic behavior derived from different groups of RCTs divided by shoulder function,including anterior-posterior translation and superior-inferior migration of humeral rotational center,glenohumeral fulcrum condition as well as glenohumeral maximal abduction angle.The differences may be related to varied functional condition of rotator cuff or pathological anatomic pattern of osseous structure,of which further study is required. |
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