Szivek J A, Anderson P L, DeYoung D W
Department of Surgery, University of Arizona, Tucson 85724, USA.
J Invest Surg. 1997 Sep-Oct;10(5):263-73. doi: 10.3109/08941939709032165.
Identification of the strains and the strain changes caused by implants is critical to the understanding of bone remodeling and can identify design changes needed to prevent bone loss near orthopedic implants. Calcium phosphate ceramic (CPC) coated strain gauges have been developed to allow long-term in vivo strain measurements. Previously used cyanoacrylate-bonded gauges have uncharacterizable sensing accuracy because the adhesive is resorbed from the instant it is placed in vivo. In this study CPC-coated strain gauges were used to measure physiologically "normal" bone strains collected from the proximal femora of dogs at a series of gait speeds and the postmortem sensing accuracy of the gauges was evaluated. Three male dogs were surgically implanted with up to six wired CPC-coated strain gauges placed around the circumference of their proximal femora. The dogs were trained to run on a treadmill, and in vivo strain measurements were collected following a 12-week period. The animals were tetracyline labeled and then euthanized and their femora explanted. Gauges were attached with cyanoacrylate to the intact contralateral control femora in the same position as the CPC-coated gauges on the test femora. Both femora were tested in cantilever bending to assess the functionality of the gauges and quality of the CPC-bone bond. After testing, all bones were embedded, sectioned, and ground. Sections from each femur were stained with mineralized bone stain and examined with transmitted and ultraviolet light to assess bone formation. Additional sections were examined with backscattered electron microscopy to confirm bone bonding to coatings. Wired gauges attached with the CPC coatings measured strain patterns during gait at several treadmill speeds. Patterns were similar and peak strains the same over a 2-week period. Mechanical testing showed bonding of CPC-coated gauges, and histologic examination showed intimate contact between gauge coatings and bone surfaces. Further development of CPC-bonded strain gauges is expected to result in a measurement system that provides ease of placement, and consistent longer term bone strain measurements with characterizable accuracy.
识别植入物引起的菌株及其变化对于理解骨重塑至关重要，并且可以确定防止骨科植入物附近骨质流失所需的设计变更。已开发出磷酸钙陶瓷（CPC）涂层应变片，用于长期体内应变测量。以前使用的氰基丙烯酸酯粘结应变片具有无法表征的传感精度，因为粘合剂从放入体内的那一刻起就会被吸收。在本研究中，使用CPC涂层应变片测量从不同步态速度的犬近端股骨收集的生理“正常”骨应变，并评估应变片的死后传感精度。三只雄性犬通过手术植入多达六个有线CPC涂层应变片，围绕其近端股骨的圆周放置。训练犬在跑步机上奔跑，并在12周后收集体内应变测量值。对动物进行四环素标记，然后实施安乐死并取出其股骨。将应变片用氰基丙烯酸酯附着在完整对侧对照股骨上，位置与测试股骨上的CPC涂层应变片相同。对两根股骨进行悬臂弯曲测试，以评估应变片的功能和CPC与骨的粘结质量。测试后，将所有骨骼包埋、切片和研磨。用矿化骨染色剂对每根股骨的切片进行染色，并用透射光和紫外光检查以评估骨形成。用背散射电子显微镜检查其他切片以确认骨与涂层的粘结。带有CPC涂层的有线应变片在几种跑步机速度的步态期间测量应变模式。在两周内，模式相似且峰值应变相同。力学测试显示CPC涂层应变片的粘结良好，组织学检查显示应变片涂层与骨表面紧密接触。预计CPC粘结应变片的进一步发展将产生一种易于放置且能以可表征精度进行一致的长期骨应变测量的测量系统。
