Biomechanical benefits of anterior offsetting of humeral head component in posteriorly unstable total shoulder arthroplasty: A cadaveric study.

Restoration of joint stability during total shoulder arthroplasty can be challenging in the face of severe glenoid retroversion. A novel technique of humeral head component anterior-offsetting has been proposed to address posterior instability. We evaluated the biomechanical benefits of this technique in cadaveric specimens. Total shoulder arthroplasty was performed in 14 cadaveric shoulders from 7 donors. Complementary shoulders were assigned to either 10° or 20° glenoid retroversion, with retroversion created by eccentric reaming. Two humeral head component offset positions were tested in each specimen: The anatomic (posterior) and anterior (reverse). With loads applied to the rotator cuff and deltoid, joint contact pressures and the force and energy required for posterior humeral head translation were measured. The force and energy required to displace the humeral head posteriorly increased significantly with the anterior offset position compared to the anatomic offset position. The joint contact pressures were significantly shifted anteriorly, and the joint contact area significantly increased with the anterior offset position. Anterior offsetting of the humeral head component increased the resistance to posterior humeral head translation, shifted joint contact pressures anteriorly, and increased joint contact area, thus, potentially increasing the joint stability in total shoulder arthroplasty with simulated glenoid retroversion.

[Immunologic function of palatine tonsil B lymphocyte].

OBJECTIVE: To study cellular immune function of palatine tonsil B lymph cell. METHOD: The phenotype of palatine tonsil cells (PTC) and that of peripheral blood mononuclear cell (PBMC) were compared using fluorescence staining and flow cytometry (FCM) analysis, then immunomagnetic beads were used to separate CD3- cell in PTC and PBMC. The proliferation function of CD3- lymph cell of PTC and PBMC was tested after stimulated by CD20mAb. RESULT: FCM analysis founding that 71.2% PTC express CD20 with higher mean fluorescence intensity, MFI, compared to the 15.5% in PBMC. There's no significant difference between the proliferation of PTC and PBMC B lymph cell. CONCLUSION: CD20 expression is different in PTC and PBMC, but corresponding function is still unknown.

[Setup a model for study the interfere between chemokine and immunocyte].

OBJECTIVE: To investigated the effect of chemoattractant of rhTNF-alpha on TB-LCL. Set up a model for study the interaction between cytokine and B cells. METHOD: PTC were transfected with Epstein Barr virus, to get tonsil B lymphoblastic cell line(TB-LCL). RESULT: It was found rhTNF-alpha can chemotactic TB-LCL, in a dose-dependent manner and this chemotactic effect can be blocked by the neutralizing antibody E6 against TNF. CONCLUSION: This is an useful model in study the interfere between chemokine and immunocyte.