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Similar rates of medial elbow changes in Little Leaguers may imply that the roentgenological changes of the medial epicondyle could be an adaptive yet physiological reaction to the excessive valgus stress of throwing. The higher incidence of medial epicondylar separation and fragmentation in catchers that has not been reported before may be secondary to the increased stress placed on the elbow when throwing from the squatting position.

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With advances in ceramics technology, calcium phosphate bioceramics have been applied as bone substitutes for several decades. The focus of this work is to elucidate the biocompatibility of the particulates of various calcium phosphate cytotoxicities. Four different kinds of calcium phosphate powders, including beta-tricalcium phosphate (beta-TCP), hydroxyapatite (HA), beta-dicalcium pyrophosphate (beta-DCP), and sintered beta-dicalcium pyrophosphate (SDCP), were tested by osteoblast cell culture. The results were analyzed by cell count, concentration of transforming growth factor-beta 1 (TGF-beta 1), alkaline phosphatase (ALP), and prostaglandin E2 (PGE2) in culture media. The changes were most significant when osteoblasts were cultured with beta-TCP and HA bioceramics. The changes in cell population of the beta-TCP and HA were quite low in the first 3 days, then increased gradually toward the seventh day. The changes in TGF-beta 1 concentration in culture medium inversely related to the changes in cell population. The ALP titer in the culture media of the beta-TCP and HA were quite high in the first 3 days, then decreased rapidly between the third and seventh days. The concentrations of PGE2 in the culture media tested were quite high on the first day, decreased rapidly to the third day, and then gradually until the seventh day. The changes in the beta-DCP and SDCP were quite similar to those of HA and beta-TCP but much less significant. We conclude that HA and beta-TCP have an inhibitory effect on the growth of osteoblasts. The inhibitins effects of the HA and beta-TCP powders on the osteoblast cell cultures possibly are mediated by the increased synthesis of PGE2.

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The operative method reported here has the advantages of minimal tissue trauma, minimal hardware application, sufficient fixation, and easy operative technique, and it can be a worthy alternative for the treatment of severely displaced surgical neck fractures of the humerus.

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