BACKGROUND: Approximately, one-third of patients with tumors of proximal humerus will require an extra-articular resection to achieve oncologic margins. This procedure yields poor functional outcomes with a considerable rate of revisions. Unconstrained implants are prone to instability hindering also function of the elbow and hand, whereas constrained shoulder reconstructions suffer from early aseptic loosening of the glenoid component due to bone overload. The purpose of this study was to develop a constrained implant suitable for extra-articular resection with loss of function in deltoid and rotator cuff, which would provide both stability and passive motion, whilst also decreasing the risk of aseptic loosening of the glenoid component. METHODS: In cooperation with Czech Technical University in Prague, we devised an implant consisting of two constrained joints in series connected by a dumbbell piece. The biomechanical analysis showed a reduction of load transfer to the glenoid component with a torque of 8.6 Nm capable of generating an 865-N pulling force on bone screw to just 0.07 Nm, hence shielding the glenoid component from undesired forces and decreasing the risk of aseptic loosening. Three patients with extra-articular resection with a total loss of function of both rotator cuff and deltoid muscle received this type of reconstruction. The average follow-up was 16 months. RESULTS: The surgical technique is straightforward. The surgery took 175 min on average with average blood loss of 516 ml. There were no surgical- or implant-related complications. All three patients were pain-free and had a stable shoulder joint after the reconstruction. All had fully functional elbow, wrist, and hand joints. The average Musculoskeletal Tumor Society (MSTS) score was 21/30 (70%). All patients were pleased with the results. CONCLUSION: The presented innovative implant design has demonstrated to be a promising alternative for reconstruction in these challenging cases.

• Klíčová slova
• Extra-articular resection, Sarcoma, Shoulder reconstruction, Tumor,
• MeSH
• artroplastiky kloubů * MeSH
• humerus chirurgie   MeSH
• lidé MeSH
• lopatka MeSH
• nádory kostí * chirurgie   MeSH
• pooperační komplikace etiologie   MeSH
• ramenní kloub * chirurgie   MeSH
• rameno MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

The main objective of this study was to analyze changes in the antiproliferative effect of vitamin D3, in the form of calcitriol and calcidiol, via its combined application with all-trans retinoic acid (ATRA) in osteosarcoma cell lines. The response to treatment with calcitriol and calcidiol alone was specific for each cell line. Nevertheless, we observed an enhanced effect of combined treatment with ATRA and calcitriol in the majority of the cell lines. Although the levels of respective nuclear receptors did not correlate with the sensitivity of cells to these drugs, vitamin D receptor (VDR) upregulation induced by ATRA was found in cell lines that were the most sensitive to the combined treatment. In addition, all these cell lines showed high endogenous levels of retinoic acid receptor α (RARα). Our study confirmed that the combination of calcitriol and ATRA can achieve enhanced antiproliferative effects in human osteosarcoma cell lines in vitro. Moreover, we provide the first evidence that ATRA is able to upregulate VDR expression in human osteosarcoma cells. According to our results, the endogenous levels of RARα and VDR could be used as a predictor of possible synergy between ATRA and calcitriol in osteosarcoma cells.

• Klíčová slova
• all-trans retinoic acid, calcidiol, calcitriol, osteosarcoma, retinoic acid receptor α, vitamin D receptor,
• MeSH
• alfa receptor kyseliny retinové metabolismus   MeSH
• kalcifediol aplikace a dávkování   MeSH
• kalcitriol aplikace a dávkování   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• osteosarkom farmakoterapie   metabolismus   MeSH
• protinádorové látky aplikace a dávkování   MeSH
• protokoly protinádorové kombinované chemoterapie MeSH
• receptory kalcitriolu metabolismus   MeSH
• screeningové testy protinádorových léčiv MeSH
• tretinoin aplikace a dávkování   MeSH
• vitaminy aplikace a dávkování   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• alfa receptor kyseliny retinové MeSH
• kalcifediol MeSH
• kalcitriol MeSH
• protinádorové látky MeSH
• receptory kalcitriolu MeSH
• tretinoin MeSH
• vitaminy MeSH