ABSTRACT
[Objective]To evaluate the effect of transepicondylar axis of different position on volume rendering technique measuring the humeral head retroversion angle with multi slice spiral CT.[Method]Fifty-one dry humerus specimens were scanned with 16 slice spiral CT scanner,At top view the three-group humeral head retroversion angle decided by the transepicondylar axis of different position were measured by volume rendering technique,As to two-dimension CT method,the distal reference axis of the humeral head retroversion angle was defined by three sections of different levels,the total six-group data on humeral head retroversion angle were analyzed by Statistics.[Result]The humeral head retroversion angle ranged from 4? to 59.8?,the humeral head retroversion angle of six groups were(25.5?10.2)?,(25.0?10.8)?,(25.7?10.8)?,(27.3?10.3)?,(26.3?10.2)?,(25.8?10.4)? respectively.The Statistics showed that the results have no significant difference among them.The more distal the humerus was,the smaller humeral head retroversion angle defined by a line between the epicondyles on two-dimension CT method was.[Conclusion]The humeral head retroversion angle is markedly variable,the humeral head retroversion angle of shoulder joint prosthetic design should be individual.The transepicondylar axis of different position has no effect on volume rendering technique measuring the humeral head retroversion angle with multi slice spiral CT.The top view at which lateral epicondyle of the humerus showing mini-triangulum and the anterior surface of the distal humerus articulation with the forearm being shaded is more simple,faster and precise for the volume rendering technique measuring the humeral head retroversion angle with multi slice spiral CT.
ABSTRACT
A reduced retroversion angle of humeral head may predispose to recurrent anterior shoulder dislocation and may also be a factor in persistent instability after soft tissue procedures. Rotation osteotomy of proximal humerus is one of many surgical modalities proposed for recurrent anterior shoulder dislocation. To support such an operation, fundamental knowledge of shoulder anatomy is essential. The semi-axial view by Soderlund have been regarded as simple and reliable method for measuring humeral head retroversion angle. The purpose of this study was to evaluate validity of the semi-axial view and to assess reference values for humeral head retroversion angle in Korean. Humeral head retroversion angle was determined from 80 healthy subjects, 48 men and 32 women. Radiographs which shown less than 10degrees between humeral shaft axis and epicondylar axis were defined as acceptable radiographs by Soderlund. Acceptable radiographs were selected and two orthopedic surgeons measured retroversion angle, separately. Acceptable radiographs were obtained in only 70 shoulders (43.8%). The mean angle was 35.2+/-8.24degrees for dominant hand and 32+/-6.27degrees for nondominant in Korean. The mean angle was 35.3+/- 7.78degrees for right side and 31.9+/-6.8degrees for left. The interobserver difference was 2.9degrees. The semi-axial view by Soderlund was not reproducible solely. But if correct arm position is considered, the method presented is easy to use daily.