{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,24]],"date-time":"2026-10-24T05:23:13Z","timestamp":1792819393625,"version":"4.5.0"},"reference-count":42,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2022,6,27]],"date-time":"2022-06-27T00:00:00Z","timestamp":1656288000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"AO Development Incubator"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medicina"],"abstract":"<jats:p>Background and Objectives: Fracture healing is currently assessed through qualitative evaluation of radiographic images, which is highly subjective in nature. Radiographs can only provide snapshots in time, which are limited due to logistics and radiation exposure. We recently proposed assessing the bone healing status through continuous monitoring of the implant load, utilizing an implanted sensor system, the Fracture Monitor. The device telemetrically transmits statistically derived implant parameters via the patient\u2019s mobile phone to assist physicians in diagnostics and treatment decision-making. This preclinical study aims to systematically investigate the device safety and performance in an animal setting. Materials and Methods: Mid-shaft tibial osteotomies of different sizes (0.6\u201330 mm) were created in eleven Swiss mountain sheep. The bones were stabilized with either a conventional Titanium or stainless-steel locking plate equipped with a Fracture Monitor. Data were continuously collected over the device\u2019s lifetime. Conventional radiographs and clinical CT scans were taken longitudinally over the study period. The radiographs were systematically scored and CTs were evaluated for normalized bone volume in the defect. The animals were euthanized after 9 months. The sensor output was correlated with the radiologic parameters. Tissue samples from the device location were histologically examined. Results: The sensors functioned autonomously for 6.5\u20138.4 months until energy depletion. No macroscopic or microscopic adverse effects from device implantation were observed. The relative implant loads at 4 and 8 weeks post-operation correlated significantly with the radiographic scores and with the normalized bone volume metric. Conclusions: Continuous implant load monitoring appears as a relevant approach to support and objectify fracture healing assessments and carries a strong potential to enable patient-tailored rehabilitation in the future.<\/jats:p>","DOI":"10.3390\/medicina58070858","type":"journal-article","created":{"date-parts":[[2022,6,28]],"date-time":"2022-06-28T00:07:02Z","timestamp":1656374822000},"page":"858","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":57,"title":["Continuous Implant Load Monitoring to Assess Bone Healing Status\u2014Evidence from Animal Testing"],"prefix":"10.3390","volume":"58","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8077-6914","authenticated-orcid":false,"given":"Markus","family":"Windolf","sequence":"first","affiliation":[{"name":"AO Research Institute Davos, 7270 Davos, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Viktor","family":"Varjas","sequence":"additional","affiliation":[{"name":"AO Research Institute Davos, 7270 Davos, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dominic","family":"Gehweiler","sequence":"additional","affiliation":[{"name":"AO Research Institute Davos, 7270 Davos, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ronald","family":"Schwyn","sequence":"additional","affiliation":[{"name":"AO Research Institute Davos, 7270 Davos, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2705-0812","authenticated-orcid":false,"given":"Daniel","family":"Arens","sequence":"additional","affiliation":[{"name":"AO Research Institute Davos, 7270 Davos, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Caroline","family":"Constant","sequence":"additional","affiliation":[{"name":"AO Research Institute Davos, 7270 Davos, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8155-4202","authenticated-orcid":false,"given":"Stephan","family":"Zeiter","sequence":"additional","affiliation":[{"name":"AO Research Institute Davos, 7270 Davos, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7778-2480","authenticated-orcid":false,"given":"Robert Geoff","family":"Richards","sequence":"additional","affiliation":[{"name":"AO Research Institute Davos, 7270 Davos, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Manuela","family":"Ernst","sequence":"additional","affiliation":[{"name":"AO Research Institute Davos, 7270 Davos, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,6,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"A916","DOI":"10.1016\/j.jval.2016.08.110","article-title":"Hospital Admissions and Inpatient Costs of Non-Union, Delayed Union and Mal-Union Following Long Bone Fracture","volume":"19","author":"Dunlop","year":"2016","journal-title":"Value Health"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"S3","DOI":"10.1016\/j.injury.2020.11.029","article-title":"Fracture nonunion in long bones: A literature review of risk factors and surgical management","volume":"52","author":"Nicholson","year":"2020","journal-title":"Injury"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"e162775","DOI":"10.1001\/jamasurg.2016.2775","article-title":"Epidemiology of Fracture Nonunion in 18 Human Bones","volume":"151","author":"Zura","year":"2016","journal-title":"JAMA Surg."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1186\/s10195-019-0528-0","article-title":"The \u2018diamond concept\u2019 for long bone non-union management","volume":"20","author":"Andrzejowski","year":"2019","journal-title":"J. Orthop. Traumatol."},{"key":"ref_5","first-page":"917","article-title":"Study of consolidation of fractures by deformation gauges in clinical medicine","volume":"34","author":"Burny","year":"1968","journal-title":"Acta Orthop. Belg."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"207","DOI":"10.3109\/17453677208991258","article-title":"Measurements of stability of crural fractures treated with Hoffmann osteotaxis. 2. Measurements on crural fractures","volume":"3","author":"Jorgensen","year":"1972","journal-title":"Acta Orthop. Scand."},{"key":"ref_7","first-page":"354","article-title":"Measuring bone healing in osteosynthesis with external fixator using the Fraktometer FM 100","volume":"62","author":"Claes","year":"1991","journal-title":"Chir. Z. Geb. Oper. Med."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"398","DOI":"10.1302\/0301-620X.94B3.27550","article-title":"Telemetric assessment of bone healing with an instrumented internal fixator: A preliminary study","volume":"94","author":"Seide","year":"2012","journal-title":"J. Bone Jt. Surg."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1302\/2046-3758.55.2000611","article-title":"An electronically instrumented internal fixator for the assessment of bone healing","volume":"5","author":"Kienast","year":"2016","journal-title":"Bone Jt. Res."},{"key":"ref_10","first-page":"9021","article-title":"Smart implants in fracture care-buzzword or real opportunity?","volume":"52","author":"Ernst","year":"2020","journal-title":"Injury"},{"key":"ref_11","unstructured":"Windolf, M., Ernst, M., Schwyn, R., Perren, S.M., Mathis, H., Wilke, M.R.G.R., and Richards, R.G. (2014, January 3\u20134). A biofeedback system for continuous monitoring of bone healing. Proceedings of the International Conference on Biomedical Electronics and Devices, Angers, France."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"110188","DOI":"10.1016\/j.jbiomech.2020.110188","article-title":"Clinical feasibility of fracture healing assessment through continuous monitoring of implant load","volume":"116","author":"Ernst","year":"2020","journal-title":"J. Biomech."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"516","DOI":"10.1097\/BOT.0000000000000390","article-title":"Determination of Radiographic Healing: An Assessment of Consistency Using RUST and Modified RUST in Metadiaphyseal Fractures","volume":"29","author":"Litrenta","year":"2015","journal-title":"J Orthop. Trauma."},{"key":"ref_14","unstructured":"Brooker, A.F., and Edwards, C.C. (1979). Strain Gauge Measurement of Fracture Healing. A study of 350 cases. External Fixation-The Current State of the Art, The Williams & Wilkins Company."},{"key":"ref_15","first-page":"895","article-title":"Clinical use of strain gauges. Current situation and future prospects","volume":"44","author":"Burny","year":"1978","journal-title":"Acta Orthop. Belg."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"146","DOI":"10.1007\/s00423-002-0306-x","article-title":"Monitoring and healing analysis of 100 tibial shaft fractures","volume":"387","author":"Claes","year":"2002","journal-title":"Langenbecks Arch. Surg."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1964","DOI":"10.1007\/s11999-009-0752-7","article-title":"Monitoring the mechanical properties of healing bone","volume":"467","author":"Claes","year":"2009","journal-title":"Clin. Orthop. Relat. Res."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"64","DOI":"10.1016\/0141-5425(88)90028-3","article-title":"Design and performance of a fracture monitoring transducer","volume":"10","author":"Evans","year":"1988","journal-title":"J. Biomed. Eng."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1361","DOI":"10.1016\/j.jbiomech.2003.12.025","article-title":"Three-dimensional load measurements in an external fixator","volume":"37","author":"Seide","year":"2004","journal-title":"J. Biomech."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"103","DOI":"10.1007\/s10039-007-1227-2","article-title":"Entwicklung eines elektronischen Steifigkeitsmesssystems mit permanenter Datenspeicherung","volume":"9","author":"Schmickal","year":"2007","journal-title":"Trauma Berufskrankh."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1016\/S0268-0890(05)80065-9","article-title":"The Use of Strain Gauges to Measure Bone Fracture Healing\u2014A Review","volume":"8","author":"Jenkins","year":"1994","journal-title":"Curr. Orthop."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1823","DOI":"10.3928\/0147-7447-19841201-08","article-title":"Twenty Years Experience in Fracture Healing Measurement with Strain Gauges","volume":"7","author":"Burny","year":"1984","journal-title":"Orthopedics"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1016\/0021-9290(72)90021-8","article-title":"Measurement of the stiffness of fracture callus in vivo. A theoretical study","volume":"5","author":"Bourgois","year":"1972","journal-title":"J. Biomech."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"849","DOI":"10.1016\/S0021-9290(01)00037-9","article-title":"Loads acting in an intramedullary nail during fracture healing in the human femur","volume":"34","author":"Schneider","year":"2001","journal-title":"J. Biomech."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"815","DOI":"10.1016\/0021-9290(82)90046-X","article-title":"Telemetering in vivo loads from nail plate implants","volume":"15","author":"Brown","year":"1982","journal-title":"J. Biomech."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"469","DOI":"10.1016\/S1350-4533(00)00062-X","article-title":"Concept, design and fabrication of smart orthopedic implants","volume":"22","author":"Burny","year":"2000","journal-title":"Med. Eng. Phys."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1463","DOI":"10.1109\/TBME.2015.2496237","article-title":"Monitoring of Postoperative Bone Healing Using Smart Trauma-Fixation Device with Integrated Self-Powered Piezo-Floating-Gate Sensors","volume":"63","author":"Borchani","year":"2015","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1007\/s10039-007-1238-z","article-title":"Winkelstabile Osteosyntheseimplantate-Intraoperativ montierbares, telemetrisches Lastmesssystem","volume":"9","author":"Capanni","year":"2007","journal-title":"Trauma Berufskrankh."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1016\/j.medengphy.2018.06.006","article-title":"Simple implantable wireless sensor platform to measure pressure and force","volume":"59","author":"Drazan","year":"2018","journal-title":"Med. Eng. Phys."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"115311","DOI":"10.1016\/j.bone.2020.115311","article-title":"Wireless sensor enables longitudinal monitoring of regenerative niche mechanics during rehabilitation that enhance bone repair","volume":"135","author":"Klosterhoff","year":"2020","journal-title":"Bone"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1164","DOI":"10.1002\/jor.24275","article-title":"Direct electromagnetic coupling for non-invasive measurements of stability in simulated fracture healing","volume":"37","author":"Labus","year":"2019","journal-title":"J. Orthop. Res."},{"key":"ref_32","first-page":"1","article-title":"Smart bone plates can monitor fracture healing","volume":"9","author":"Lin","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1439","DOI":"10.1002\/jor.22918","article-title":"Implantable microelectromechanical sensors for diagnostic monitoring and post-surgical prediction of bone fracture healing","volume":"33","author":"McGilvray","year":"2015","journal-title":"J. Orthop. Res."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1489","DOI":"10.1038\/s41598-017-01009-7","article-title":"Implantable strain sensor to monitor fracture healing with standard radiography","volume":"7","author":"Pelham","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_35","first-page":"12477","article-title":"Elementary Implantable Force Sensor: For Smart Orthopaedic Implants","volume":"2","author":"Wachs","year":"2013","journal-title":"Adv. Biosens. Bioelectron."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"702","DOI":"10.1097\/BOT.0b013e3181b01c49","article-title":"A Single-Channel Telemetric Intramedullary Nail for In Vivo Measurement of Fracture Healing","volume":"23","author":"Wilson","year":"2009","journal-title":"J. Orthop. Trauma"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1873","DOI":"10.1002\/jor.24325","article-title":"Utilizing Multiple BioMEMS Sensors to Monitor Orthopaedic Strain and Predict Bone Fracture Healing","volume":"37","author":"Wolynski","year":"2019","journal-title":"J. Orthop. Res."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"S1","DOI":"10.1016\/j.injury.2014.04.001","article-title":"The bottleneck of evidence-based fracture care","volume":"45","author":"Bottlang","year":"2014","journal-title":"Injury"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"62","DOI":"10.2106\/JBJS.G.01556","article-title":"Outcome Assessment in Clinical Trials of Fracture-Healing","volume":"90","author":"Morshed","year":"2008","journal-title":"J. Bone Jt. Surg."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"610","DOI":"10.1302\/2046-3758.610.BJR-2017-0301","article-title":"The forgotten phase of fracture healing: The need to predict nonunion","volume":"6","author":"Simpson","year":"2017","journal-title":"Bone Jt. Res."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1016\/j.injury.2020.10.050","article-title":"The relation between fracture activity and bone healing with special reference to the early healing phase\u2014A preclinical study","volume":"52","author":"Windolf","year":"2020","journal-title":"Injury"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1089\/ten.teb.2015.0123","article-title":"Monitoring healing progression and characterizing the mechanical environment in preclinical models for bone tissue engineering","volume":"22","author":"Fountain","year":"2016","journal-title":"Tissue Eng. Part B Rev."}],"container-title":["Medicina"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1648-9144\/58\/7\/858\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:39:11Z","timestamp":1760139551000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1648-9144\/58\/7\/858"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,6,27]]},"references-count":42,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2022,7]]}},"alternative-id":["medicina58070858"],"URL":"https:\/\/doi.org\/10.3390\/medicina58070858","relation":{},"ISSN":["1648-9144"],"issn-type":[{"value":"1648-9144","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,6,27]]}}}