Research of bone defects associated with shoulder stability
Objective To examine the impact of bone defects on shoulder stability,provide a theoretical basis for clinical studies.Methods The bone defect models of glenoid and humeral head were made respectively,and the amount of defect was increased gradually.First,anterior translation of humeral head before the dislocation of glenohumeral joint was measured from 60° of abduction and neutral position to the dislocation by increasing external rotation angle.Then,maintaining 60° of abduction of the glenohumeral joint,the axial stress was increased at 60° of external rotation and neutral position respectively until the dislocation of glenohumeral joint,and then the stress intensity of humeral head was measured before the dislocation.Results With the increase of glenoid and humeral head defects and external rotation angle,the stability of shoulder joint decreased,the anterior translation of humeral head increased.There was a significant difference among each group(P0.01).At 60° of abduction and neutral position of the glenohumeral joint,the stress intensity of humeral head increased with the amount of bone defect,increasing rapidly from 1.68 to 4.62 Mpa.There was a significant difference among each group(P0.01).At 60° of abduction and 60° of external rotation of the glenohumeral joint,the normal stress intensity of humeral head was 1.94 Mpa,increasing rapidly to 6.65 Mpa with increased bone defects.There was a significant difference among each group(P0.01).Contact pressure mechanical characteristics of shoulder joint showed that the amount of bone defect had tremendous influence on the stability of shoulder joint.Conclusion With the increase of glenoid and the humeral head defects,the stability of the shoulder joint decreased,and the anterior translocation and stress intensity of humeral head increased,resulting in the dislocation of glenohumeral joint in advance.