Carrington Nathan T, Forrester Savannah R, Milhouse Paul W, Behrend Caleb J, Pace Tom B, Jeray Kyle, Anker Jeffrey N, DesJardins John D
Department of Chemistry, Clemson University, Clemson, SC, USA.
Aravis BioTech LLC, Greenville, SC, USA.
Sci Rep. 2025 Jun 5;15(1):19725. doi: 10.1038/s41598-025-03216-z.
Bone healing after internal fixation of intertrochanteric hip fractures is difficult to monitor with radiography, particularly with sliding hip screws (SHS). In this proof-of-concept study, we develop an ovine hip fracture model and use it to evaluate a novel sliding hip screw system with a sensor that can non-invasively detect bending of the screw implant during healing. An existing SHS implant was modified and implanted in a Suffolk Ewe sheep. A straight, radiodense 1 mm tungsten rod was attached to the screw in the cannula to enable quantification of screw bending by radiographically observing relative position of the rod compared to the screw tip. After surgery, weekly loaded and unloaded radiographs were taken of the femur. Once fracture stabilization had been indicated for at least three weeks, the femur was extracted and potted and radiographs were taken under simulated axial loading from 5 to 400 N. By week 3, full in vivo weight bearing over the fractured femur was achieved. In response, implant loading was clearly observed with the novel sensor. This observed implant loading continued until week 8, wherein it ceased entirely. Upon extraction, the femur showed a fully developed and very stable callus surrounding the fracture site. Subsequent mechanical tests confirmed no measurable implant loading under axial loads of up to 400 N. This test indicates that the proposed ovine model produces sufficient force over an SHS implant in an induced fracture. This allowed our sensor to indicate fracture healing through radiography in load scenarios greater than 25 kg.
股骨转子间髋部骨折内固定后的骨愈合情况很难通过X线摄影进行监测，尤其是使用滑动髋螺钉（SHS）时。在这项概念验证研究中，我们开发了一种绵羊髋部骨折模型，并用它来评估一种新型的滑动髋螺钉系统，该系统带有一个传感器，能够在愈合过程中无创检测螺钉植入物的弯曲情况。对现有的SHS植入物进行了改良，并植入一只萨福克母羊体内。在套管内的螺钉上连接一根1毫米直的、具有放射性密度的钨棒，通过X线摄影观察该棒相对于螺钉尖端的相对位置，从而对螺钉弯曲进行量化。术后，每周对股骨进行负重和非负重X线摄影。一旦显示骨折稳定至少持续三周，就取出股骨并进行盆栽，然后在5至400牛的模拟轴向载荷下拍摄X线片。到第3周时，骨折的股骨已实现完全体内负重。相应地，通过新型传感器可清楚观察到植入物的负荷情况。这种观察到的植入物负荷一直持续到第8周，之后完全停止。取出后，股骨在骨折部位周围显示出一个完全发育且非常稳定的骨痂。随后的力学测试证实，在高达400牛的轴向载荷下，没有可测量的植入物负荷。该测试表明，所提出的绵羊模型在诱导骨折中能在SHS植入物上产生足够的力。这使得我们的传感器能够在大于25千克的负荷情况下通过X线摄影显示骨折愈合情况。
