{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,12]],"date-time":"2026-06-12T02:56:59Z","timestamp":1781233019997,"version":"3.54.1"},"reference-count":24,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T00:00:00Z","timestamp":1781049600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background: Vitamin K2 (menaquinone) has been studied as a molecule with important effects on bone metabolism and has been proposed as a potential adjuvant in fracture healing, particularly under osteoporotic conditions. However, its functional impact on osteoporotic fracture healing remains largely undefined. The aim of this study was to evaluate the effects of vitamin K2 supplementation, in the form of menaquinone-4 (MK-4) and menaquinone-7 (MK-7), on fracture healing in an ovariectomized rat model of osteoporosis. Methods: Forty Wistar rats were included in this study and allocated to four equal groups: Sham control, ovariectomized control, MK-4, and MK-7. Osteoporosis was induced by bilateral ovariectomy, and 12 weeks after ovariectomy, a femoral fracture was produced and fixed by intramedullary nailing. Starting on postoperative day 2, the MK-4 group received 5 mg\/kg\/day of MK-4, while the MK-7 group received MK-7 at a dose of 0.05 mg\/kg\/day. Fracture healing was assessed primarily by biomechanical testing using a three-point bending test and was further analyzed by histological and biochemical parameters, including CTXI, PINP, ucOC, BALP, and ALT. Results: Vitamin K2 supplementation did not improve functional fracture healing. In both treatment groups, fractures showed nonunion-like mechanical behavior, precluding meaningful quantitative biomechanical comparison. Although histological and biochemical findings, particularly in the MK-4 group, showed some degree of biological activity, these changes did not translate into mechanically competent bone union. Both treatment groups showed a tendency toward impaired healing, with progression toward nonunion-like behavior under the present experimental conditions. No significant hepatic toxicity was observed. Conclusions: In this ovariectomized rat femoral fracture model, vitamin K2 supplementation with either MK-4 or MK-7 did not enhance functional fracture healing despite evidence of biological activity of the treatment. These findings suggest a discrepancy between molecular or histological effects and biomechanical outcomes, indicating that, under the conditions tested, vitamin K2 is insufficient to overcome impaired healing in osteoporotic bone and may adversely influence fracture repair under these experimental conditions, although the mechanism remains uncertain.<\/jats:p>","DOI":"10.3390\/jcm15124510","type":"journal-article","created":{"date-parts":[[2026,6,11]],"date-time":"2026-06-11T02:59:31Z","timestamp":1781146771000},"page":"4510","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Discrepancy Between Biological Activity and Functional Fracture Healing Following Vitamin K2 Supplementation in an Ovariectomized Rat Model of Osteoporosis"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5268-9343","authenticated-orcid":false,"given":"Alexandru","family":"Jecan","sequence":"first","affiliation":[{"name":"Department of Orthopedics and Traumatology, University of Medicine and Pharmacy \u201cIuliu Ha\u021bieganu\u201d, 400132 Cluj-Napoca, Romania"},{"name":"Orthopedics and Traumatology Clinic \u201cAlexandru Radulescu\u201d, Emergency County Hospital, 400347 Cluj Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6965-4649","authenticated-orcid":false,"given":"R\u0103zvan Marian","family":"Melinte","sequence":"additional","affiliation":[{"name":"Department of Orthopedics and Traumatology, University of Medicine and Pharmacy \u201cIuliu Ha\u021bieganu\u201d, 400132 Cluj-Napoca, Romania"},{"name":"Orthopedics and Traumatology Clinic \u201cAlexandru Radulescu\u201d, Emergency County Hospital, 400347 Cluj Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gheorghe","family":"Tomoaia","sequence":"additional","affiliation":[{"name":"Department of Orthopedics and Traumatology, University of Medicine and Pharmacy \u201cIuliu Ha\u021bieganu\u201d, 400132 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8976-1011","authenticated-orcid":false,"given":"Luciana-M\u0103d\u0103lina","family":"Gherman","sequence":"additional","affiliation":[{"name":"Experimental Centre, University of Medicine and Pharmacy \u201cIuliu Ha\u021bieganu\u201d, 400349 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3706-887X","authenticated-orcid":false,"given":"Vasile","family":"Rus","sequence":"additional","affiliation":[{"name":"Department of Histology, Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine, 400372 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1899-5977","authenticated-orcid":false,"given":"Raluca Maria","family":"Pop","sequence":"additional","affiliation":[{"name":"Department of Pharmacology, Toxicology and Clinical Pharmacology, University of Medicine and Pharmacy \u201cIuliu Ha\u021bieganu\u201d, 400012 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4188-1169","authenticated-orcid":false,"given":"C\u0103t\u0103lin","family":"Popa","sequence":"additional","affiliation":[{"name":"Department of Materials Science and Engineering, Technical University of Cluj-Napoca, 400641 Cluj-Napoca, Romania"},{"name":"EUt+ Institute of Nanomaterials & Nanotechnologies EUTINN, European University of Technology, European Union"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Diana","family":"Jecan-Toader","sequence":"additional","affiliation":[{"name":"Department 2, Faculty of Nursing and Health Sciences, University of Medicine and Pharmacy \u201cIuliu Ha\u021bieganu\u201d, 400132 Cluj-Napoca, Romania"},{"name":"2nd Pediatric Clinic, Emergency Clinical Hospital for Children, 400124 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Drago\u0219","family":"Apostu","sequence":"additional","affiliation":[{"name":"Department of Orthopedics and Traumatology, University of Medicine and Pharmacy \u201cIuliu Ha\u021bieganu\u201d, 400132 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-8399-0785","authenticated-orcid":false,"given":"Marian Andrei","family":"Melinte","sequence":"additional","affiliation":[{"name":"Faculty of Medicine, University of Medicine and Pharmacy \u201cGeorge Emil Palade\u201d, 540139 T\u00e2rgu Mure\u0219, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8094-8963","authenticated-orcid":false,"given":"Daniel","family":"Oltean-Dan","sequence":"additional","affiliation":[{"name":"Department of Orthopedics and Traumatology, University of Medicine and Pharmacy \u201cIuliu Ha\u021bieganu\u201d, 400132 Cluj-Napoca, Romania"},{"name":"Orthopedics and Traumatology Clinic \u201cAlexandru Radulescu\u201d, Emergency County Hospital, 400347 Cluj Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"356","DOI":"10.1089\/rej.2015.1682","article-title":"Ovariectomy-Induced Osteopenia Influences the Middle and Late Periods of Bone Healing in a Mouse Femoral Osteotomy Model","volume":"18","author":"Pang","year":"2015","journal-title":"Rejuvenation Res."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Sato, T., Inaba, N., and Yamashita, T. (2020). MK-7 and Its Effects on Bone Quality and Strength. Nutrients, 12.","DOI":"10.3390\/nu12040965"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Wang, H., Zhang, N., Li, L., Yang, P., and Ma, Y. (2021). Menaquinone 4 Reduces Bone Loss in Ovariectomized Mice through Dual Regulation of Bone Remodeling. Nutrients, 13.","DOI":"10.3390\/nu13082570"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"104571","DOI":"10.1016\/j.jmbbm.2021.104571","article-title":"Microstructural and Mechanical Recovery of Bone in Ovariectomized Rats: The Effects of Menaquinone-7","volume":"120","author":"Iwamoto","year":"2021","journal-title":"J. Mech. Behav. Biomed. Mater."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2499","DOI":"10.1007\/s00198-013-2325-6","article-title":"Three-Year Low-Dose Menaquinone-7 Supplementation Helps Decrease Bone Loss in Healthy Postmenopausal Women","volume":"24","author":"Knapen","year":"2013","journal-title":"Osteoporos. Int."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"142","DOI":"10.1007\/s00774-013-0472-7","article-title":"Low-Dose Vitamin K2 (MK-4) Supplementation for 12 Months Improves Bone Metabolism and Prevents Forearm Bone Loss in Postmenopausal Japanese Women","volume":"32","author":"Koitaya","year":"2014","journal-title":"J. Bone Miner. Metab."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"234","DOI":"10.1007\/s00223-010-9333-8","article-title":"Vitamin K2 Promotes Bone Healing in a Rat Femoral Osteotomy Model with or without Glucocorticoid Treatment","volume":"86","author":"Iwamoto","year":"2010","journal-title":"Calcif. Tissue Int."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"17","DOI":"10.5152\/j.aott.2023.21013","article-title":"Morphological and Biomechanical Effects of Vitamin K2 on Fracture Healing: An Animal Study on the Rat Tibia Fracture Model","volume":"57","year":"2023","journal-title":"Acta Orthop. Traumatol. Turc."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"579","DOI":"10.1007\/s00198-025-07422-3","article-title":"Update on the Role of Bone Turnover Markers in the Diagnosis and Management of Osteoporosis: A Consensus Paper from The European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO), International Osteoporosis Foundation (IOF), and International Federation of Clinical Chemistry and Laboratory Medicine (IFCC)","volume":"36","author":"Bhattoa","year":"2025","journal-title":"Osteoporos. Int."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"149","DOI":"10.3945\/an.112.001834","article-title":"Vitamin K-Dependent Carboxylation of Osteocalcin: Friend or Foe?","volume":"3","author":"Gundberg","year":"2012","journal-title":"Adv. Nutr."},{"key":"ref_11","unstructured":"Moriles, K.E., Zubair, M., and Azer, S.A. (2026). Alanine Aminotransferase (ALT) Test. StatPearls, StatPearls Publishing."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"499","DOI":"10.3177\/jnsv.41.499","article-title":"Distribution of Menaquinone-4, a Therapeutic Agent for Osteoporosis, in Bone and Other Tissues of Rats","volume":"41","author":"Sano","year":"1995","journal-title":"J. Nutr. Sci. Vitaminol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"336","DOI":"10.1111\/jpn.13458","article-title":"The Effects of Eggshell Calcium (Biomin H\u00ae) and Its Combinations with Alfacalcidol (1\u03b1-hydroxyvitamin D3) and Menaquinone-7 (Vitamin K2) on Ovariectomy-induced Bone Loss in a Rat Model of Osteoporosis","volume":"105","author":"Omelka","year":"2021","journal-title":"Anim. Physiol. Nutr."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"106581","DOI":"10.1016\/j.vph.2019.106581","article-title":"Vitamin K2-MK-7 Improves Nitric Oxide-Dependent Endothelial Function in ApoE\/LDLR\u2212\/\u2212 Mice","volume":"122\u2013123","author":"Bar","year":"2019","journal-title":"Vasc. Pharmacol."},{"key":"ref_15","first-page":"29","article-title":"The calcium and phosphorus content of the bone tissue in ovariectomized rats with a fracture of the tibia: The effect of vitamin K and vitamin D metabolites","volume":"38","author":"Kodentsova","year":"1992","journal-title":"Fiziol. Zhurnal"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1302\/2058-5241.5.190037","article-title":"Nonunion\u2014Consensus from the 4th Annual Meeting of the Danish Orthopaedic Trauma Society","volume":"5","author":"Schmal","year":"2020","journal-title":"EFORT Open Rev."},{"key":"ref_17","first-page":"e97599","article-title":"Nonunion in Long Bone Fractures: A Comprehensive Review of Current Treatment Strategies","volume":"17","author":"Mohamed","year":"2025","journal-title":"Cureus"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Bowers, K.M., and Anderson, D.E. (2024). Delayed Union and Nonunion: Current Concepts, Prevention, and Correction: A Review. Bioengineering, 11.","DOI":"10.3390\/bioengineering11060525"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Zhang, Z., Li, Y., Li, J., Yuan, Y., Liu, K., and Shi, X. (2025). The Effect of Vitamin K2 Supplementation on Bone Turnover Biochemical Markers in Postmenopausal Osteoporosis Patients: A Systematic Review and Meta-Analysis. Front. Endocrinol., 16.","DOI":"10.3389\/fendo.2025.1703116"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"11","DOI":"10.11005\/jbm.2021.28.1.11","article-title":"Effect of Vitamin K2 Alone or in Combination on Various Bone Turnover Markers Amongst Postmenopausal Females","volume":"28","author":"AlHajri","year":"2021","journal-title":"J. Bone Metab."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"983","DOI":"10.1359\/jbmr.081254","article-title":"Vitamin K Treatment Reduces Undercarboxylated Osteocalcin but Does Not Alter Bone Turnover, Density, or Geometry in Healthy Postmenopausal North American Women","volume":"24","author":"Binkley","year":"2009","journal-title":"J. Bone Miner. Res."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1080\/09513590600900402","article-title":"Effect of Vitamin K2 Treatment on Carboxylation of Osteocalcin in Early Postmenopausal Women","volume":"22","author":"Yasui","year":"2006","journal-title":"Gynecol. Endocrinol."},{"key":"ref_23","first-page":"97","article-title":"Biochemical Markers of Bone Turnover: Part I: Biochemistry and Variability","volume":"26","author":"Seibel","year":"2005","journal-title":"Clin. Biochem. Rev."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"750","DOI":"10.1302\/2046-3758.1312.BJR-2024-0053.R1","article-title":"Effects of Vitamin K Supplementation on Bone Mineral Density at Different Sites and Bone Metabolism in the Middle-Aged and Elderly Population","volume":"13","author":"Xie","year":"2024","journal-title":"Bone Jt. Res."}],"container-title":["Journal of Clinical Medicine"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/12\/4510\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,12]],"date-time":"2026-06-12T02:15:19Z","timestamp":1781230519000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2077-0383\/15\/12\/4510"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,10]]},"references-count":24,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2026,6]]}},"alternative-id":["jcm15124510"],"URL":"https:\/\/doi.org\/10.3390\/jcm15124510","relation":{},"ISSN":["2077-0383"],"issn-type":[{"value":"2077-0383","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,10]]}}}