title: Telemetric assessment of bone healing with an instrumented internal fixator: a preliminary study.
abstract: In an interdisciplinary project involving electronic engineers and clinicians, a telemetric system was developed to measure the bending load in a titanium internal femoral fixator. As this was a new device, the main question posed was: what clinically relevant information could be drawn from its application? As a first clinical investigation, 27 patients (24 men, three women) with a mean age of 38.4 years (19 to 66) with femoral nonunions were treated using the system. The mean duration of the nonunion was 15.4 months (5 to 69). The elasticity of the plate-callus system was measured telemetrically until union. Conventional radiographs and a CT scan at 12 weeks were performed routinely, and healing was staged according to the CT scans. All nonunions healed at a mean of 21.5 weeks (13 to 37). Well before any radiological signs of healing could be detected, a substantial decrease in elasticity was recorded. The relative elasticity decreased to 50% at a mean of 7.8 weeks (3.5 to 13) and to 10% at a mean of 19.3 weeks (4.5 to 37). At 12 weeks the mean relative elasticity was 28.1% (0% to 56%). The relative elasticity was significantly different between the different healing stages as determined by the CT scans. Incorporating load measuring electronics into implants is a promising option for the assessment of bone healing. Future application might lead to a reduction in the need for exposure to ionising radiation to monitor fracture healing.
authors.affiliation: BG Trauma Hospital Hamburg, Department of Traumatology, Orthopaedics and Sports Traumatology, Bergedorfer Straße 10, 21033 Hamburg, Germany. K.Seide@buk-Hamburg.de
authors.forename: K
authors.initials: K
authors.lastname: Seide
authors.forename: M
authors.initials: M
authors.lastname: Aljudaibi
authors.forename: N
authors.initials: N
authors.lastname: Weinrich
authors.forename: B
authors.initials: B
authors.lastname: Kowald
authors.forename: C
authors.initials: C
authors.lastname: Jürgens
authors.forename: J
authors.initials: J
authors.lastname: Müller
authors.forename: M
authors.initials: M
authors.lastname: Faschingbauer
mesh_terms: D000328:Adult; D000368:Aged; D001860:Bone Plates; D004548:Elasticity; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods; D017102:Fracture Healing; D005599:Fractures, Ununited / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D016268:Internal Fixators; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011182:Postoperative Care / Q000379:methods; D011446:Prospective Studies; D011859:Radiography; D013686:Telemetry / Q000295:instrumentation* / Q000379:methods; D055815:Young Adult