Introduction: The proximal humerus is a common location for primary and non-primary tumors. Reconstruction of the proximal humerus is commonly performed with an endoprosthesis with low rates of structural failure. The incidence and risk factors for stress shielding are under reported.
Methods: Thirty-nine (19 male, 20 female) patients underwent resection of the proximal humerus and reconstruction with a cemented modular endoprosthesis between 2000 and 2018. The mean resection length was 12 ± 4 cm and was most commonly performed for metastatic disease (n = 26, 67%).
Results: Stress shielding was observed in 9 (23%) patients at a mean of 29 (6-132) months postoperatively. Patients with stress shielding were noted to have shorter intramedullary stem length (87 vs. 107 mm, p < .001), longer extramedullary implant length (16 vs. 14 cm, p = .01) and a higher extramedullary implant to stem length ratio (2.1 vs. 1.1, p < .001). The incidence of stress shielding was higher (p = .003) in patients reconstructed with 75 mm stem (n = 6, 67%) lengths.
Conclusion: Stress shielding of the humerus was associated with the use of shorter stems and long extramedullary implants. The long-term ramifications of stress shielding on implant stability, complications at the time of revision surgery, and overall patient outcomes remain unknown.
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http://dx.doi.org/10.1002/jso.26300 | DOI Listing |
Unlabelled: Melanin pigments block genotoxic agents by positioning on the sun-exposed side of human skin keratinocytes' nucleus. How this position is regulated and its role in genome photoprotection remains unknown. By developing a model of human keratinocytes internalizing extracellular melanin into pigment organelles, we show that keratin 5/14 intermediate filaments mechanically control the 3D perinuclear position of pigments, shielding DNA from photodamage.
View Article and Find Full Text PDFNutr Clin Pract
January 2025
Department of Nutrition, Centre Hospitalier Universitaire Sainte-Justine Research Center, Université de Montréal, Montréal, Québec, Canada.
Background: When exposed to ambient light, parenteral nutrition (PN) contamination with peroxides almost doubles, which increases oxidative stress in preterm infants, contributing to the development of bronchopulmonary dysplasia. The American Society for Parenteral and Enteral Nutrition (ASPEN) recommends complete PN photoprotection to reduce peroxide contamination and optimize its integrity but acknowledges the challenges of its implementation. In this study, a novel photoprotection procedure was tested for its effectiveness in reducing peroxide load and limiting ascorbic acid degradation, and for its feasibility and effectiveness in reducing urinary peroxide levels in preterm infants.
View Article and Find Full Text PDFBrain Res
January 2025
Neuropharmacology Division, Department of Pharmacology, ISF College of Pharmacy, Moga 142001, Punjab, India. Electronic address:
Neurodegenerative disorders are characterized by a progressive loss of neurons, causing substantial deficits in motor and cognitive functioning. Bilirubin is a yellow by-product of heme, existing in two primary isoforms namely unconjugated and conjugated, while initially produced unconjugated isomer is lipophilic and cytotoxic in nature. At physiological levels, bilirubin has an important role in brain function by acting as a powerful antioxidant, preventing brain tissues from oxidative damage by eliminating reactive oxygen species (ROS).
View Article and Find Full Text PDFJ Shoulder Elbow Surg
January 2025
Department of Orthopaedic Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea. Electronic address:
Background: Few comparative studies on the correlation between stem length, stem alignment, and/or stress shielding have been conducted in reverse total shoulder arthroplasty (rTSA). This study aimed to investigate the effects of different humeral stem lengths on stem alignment and proximal stress shielding after rTSA.
Methods: A total of 320 patients who underwent primary rTSA from October 2010 to May 2020 with at least 2 years of follow-up (mean follow-up: 32.
Polymers (Basel)
January 2025
Department of Dental Medicine and Nursing, Faculty of Medicine, Lucian Blaga University of Sibiu, 550169 Sibiu, Romania.
Following implantation, infections, inflammatory reactions, corrosion, mismatches in the elastic modulus, stress shielding and excessive wear are the most frequent reasons for orthopedic implant failure. Natural polymer-based coatings showed especially good results in achieving better cell attachment, growth and tissue-implant integration, and it was found that the inclusions of nanosized fillers in the coating structure improves biomineralization and consequently implant osseointegration, as the nanoparticles represent calcium phosphate nucleation centers and lead to the deposition of highly organized hydroxyapatite crystallites on the implant surface. In this study, magnetic nanoparticles synthesized by the co-precipitation method were used for the preparation of cellulose acetate composite coatings through the phase-inversion method.
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