Tetracycline labeling as a measure of humeral head viability after 3- or 4-part proximal humerus fracture

HypothesisSpecifically located humeral head biopsies from three-part proximal humerus fractures taken at the time of hemiarthroplasty will show greater tetracycline labeling under fluorescent microscopy than those biopsies taken from four-part fractures. Additionally, biopsies from younger patients would show greater fluorescence than older patients.Material and methodsNineteen consecutive adult patients (range 43-83 years) underwent hemiarthroplasty as definitive treatment for 20 displaced three- and four-part proximal humerus fractures after having received 500mg of tetracycline hydrochloride orally every six hours for the immediate five preoperative days. Humeral head biopsies were taken from four pre-determined locations intraoperatively. The biopsies were prepared and analyzed with fluorescent microscopy.ResultsAll specimens in each biopsy location demonstrated fluorescence. There was no difference between the mean rank gray values for the four biopsy locations (p = 0.78 with the Friedman test). There was no difference between the mean rank gray values for the four biopsy locations when analyzed according to three-part vs four-part fracture (p > 0.05 with the Mann-Whitney test). There was an inverse relationship between age and fluorescence for the anterosuperior biopsy location (p = 0.033 with Spearman correlation).DiscussionVascular supply is preserved in displaced three- and four-part proximal humerus fractures. With intact vascularity to the humeral head, head-preserving techniques utilizing stable, site-specific fixation and minimal dissection should be considered in the treatment of displaced three- and four-part proximal humerus fractures.ConclusionVascular supply is preserved in displaced three- and four-part proximal humerus fractures, especially in younger patients in the anterosuperior aspect of the humeral head.Level of evidenceBasic Science Study.