Reverse shoulder arthroplasty for the treatment of three-part and four-part proximal humeral fractures in the elderly.

BACKGROUND: The purpose of this study was to review the survivorship, radiologic and clinical outcomes of reverse shoulder arthroplasty (RSA) used for the treatment of 3-part and 4-part proximal humeral fractures in the elderly. METHODS: Between 2003 and 2009, 29 shoulders in 28 elderly patients (87% female) with a 3-part or 4-part fractures were managed with RSA in Brisbane, Australia. Clinical and radiologic outcomes of this continuous cohort were retrospectively reviewed at an average follow-up of 54.9 months. Average age at surgery was 79 years. Survivorship and radiologic outcome assessment for all patients was undertaken. Seven patients died, and 1 was unavailable for clinical review, leaving 21 shoulders in 20 patients available for clinical review. RESULTS: There were no revisions of the reverse prosthesis. Mean average pain was 2.19 of 100 (standard deviation [SD], 6.97). Mean American Shoulder and Elbow Surgeons score was 89.3 (SD, 13.65). Mean normalized Constant score was 88.03 (SD, 11.24). Grade 1 scapular notching was observed radiologically in 4 shoulders. A scapular spur was observed in 7 shoulders. Class 1 heterotopic ossification was seen in 4 shoulders. Nonprogressive lucent lines were seen in 2 shoulders. Nonprogressive radiolucency was observed around the superior screw in 3 shoulders. No loosening of the glenoid baseplate or of the humeral component was observed. There was 1 complication of an axillary nerve palsy, which spontaneously resolved by 12 months after surgery. CONCLUSION: RSA using the shoulder technique described in this series provides good clinical and radiologic outcomes in elderly patients with 3-part and 4-part fractures.

Phosphorylation state defines discrete roles for monopolin in chromosome attachment and spindle elongation.

BACKGROUND: It is unknown how oscillations in Cdk1 activity drive the dramatic changes in chromosome and spindle dynamics that occur at the metaphase/anaphase transition. RESULTS: We show that the Schizosaccharomyces pombe monopolin complex has distinct functions in metaphase and anaphase that are determined by the phosphorylation state of its Mde4 subunit. When Cdk1 activity is high in metaphase, Mde4 is hyperphosphorylated on Cdk1 phosphorylation sites and localizes to kinetochores. A nonphosphorylatable mutant of Mde4 does not localize to kinetochores, appears prematurely on the metaphase spindle, and interferes with spindle dynamics and chromosome segregation, illustrating the importance of Cdk1 phosphorylation in regulating metaphase monopolin activity. When Cdk1 activity drops in anaphase, dephosphorylation of Mde4 triggers monopolin localization to the mitotic spindle, where it promotes spindle elongation and integrity, coupling the late mitotic loss of Cdk1 activity to anaphase spindle dynamics. CONCLUSIONS: Together, these findings illustrate how the sequential phosphorylation and dephosphorylation of monopolin helps ensure the orderly execution of discrete steps in mitosis.