Abstract:Current orthopaedic clinical methods do not provide an objective measure of fracture healing or weight bearing for lower extremity fractures. The following report describes a novel approach involving insitu strain sensors to objectively measure fracture healing. The sensor uses a cantilevered indicator pin that responds to plate bending and an internal scale to demonstrate changes in the pin position on plain film radiographs. The long lever arm amplifies pin movement compared to interfragmentary motion, and t… Show more
“…We previously reported on a mechanical sensor with similar pin-and-scale readout to measure orthopedic implant bending under load to track fracture healing. 25 The sensor described here provides complementary local chemical information relevant for monitoring implantassociated infections.…”
The constructed biosensor enhances the capability of traditional plain film radiography, enabling the noninvasive measurement of postoperative infection indicating chemical concentration such as pH on the implant surfaces.
“…We previously reported on a mechanical sensor with similar pin-and-scale readout to measure orthopedic implant bending under load to track fracture healing. 25 The sensor described here provides complementary local chemical information relevant for monitoring implantassociated infections.…”
The constructed biosensor enhances the capability of traditional plain film radiography, enabling the noninvasive measurement of postoperative infection indicating chemical concentration such as pH on the implant surfaces.
“…However, the difference between least squares mean for treatment and the 95% CI calculated (Table ) for each variable that did not reach statistical difference between groups did not justify that conclusions be changed. In human medicine, inability to perform antemortem biomechanical testing as well as limitations of radiography as a sole gauge of fracture healing has led to the development of more objective methods of fracture evaluation, such as implantation of a strain sensor across a healing fracture . This device was created to be used adjunctively with radiographic union assessment for evaluation of fracture healing.…”
Section: Discussionmentioning
confidence: 99%
“…In human medicine, inability to perform antemortem biomechanical testing as well as limitations of radiography as a sole gauge of fracture healing has led to the development of more objective methods of fracture evaluation, such as implantation of a strain sensor across a healing fracture. 49 This device was created to be used adjunctively with radiographic union assessment for evaluation of fracture healing.…”
Objective
To determine the influence of short‐term administration of carprofen on bone healing in dogs.
Study design
Randomized controlled experimental study.
Animals
Eighteen purpose‐bred sexually mature hound dogs.
Methods
Tibial osteotomies were performed, and dogs were divided into three groups: no carprofen (n = 6), 2‐week administration of carprofen at 2.2 mg/kg twice daily (n = 6), and 8‐week administration of carprofen at 2.2 mg/kg twice daily (n = 5). Bone healing was evaluated radiographically at 4 and 8 weeks postoperatively. Postmortem, fracture healing was assessed via biomechanical testing (three‐point bending), histological cartilage:callus ratio, and bone mineral density (BMD) with quantitative computed tomography.
Results
No biomechanical difference was detected between dogs that received no carprofen and those that received 2 weeks of carprofen or between those that received 2 weeks vs 8 weeks of carprofen. Stiffness (P = .035) and maximum stress (P = .042) were higher in dogs that received no carprofen than in those that received 8 weeks of carprofen. Radiographic healing did not differ between dogs without carprofen and those with 2‐week administration of carprofen (P = .9923). However, tibias of dogs without carprofen and those with 2‐week administration of carprofen were more healed compared with those in the 8‐week‐carprofen group at 4 and 8 weeks after surgery (P = .0011). No treatment effect was detected by cartilage:callus ratio or BMD.
Conclusion
Long‐term administration of carprofen had a negative effect on bone healing compared with short‐term or no administration of carprofen.
Clinical significance
Nonsteroidal anti‐inflammatory drugs should be used cautiously in dogs at risk for delayed bone healing, and administration should be discontinued beyond the perioperative period in dogs with fractures or osteotomies.
“…[15], [21] Previously, we made a plate attachment with a tungsten pin that moved against a scale to quantitatively indicate plate bending via plain radiography. [24] However, the 12 cm long pin was surgically cumbersome, and reducing pin length would require a protruding scale and much smaller displacement. To address this concern, herein we developed a smaller device which uses hydraulic gain to amplify the signal from plate bending and increase precision for tracking healing bone.…”
We describe a fluidic X-ray visualized strain indicator under applied load (X-VISUAL) to quantify orthopedic plate strain and inform rehabilitative care. This sensor uses a liquid-level gauge with hydro-mechanical amplification and is visualized in plain radiographs which are routinely acquired during patient recovery to find pathologies but are usually insufficient to quantify fracture stiffness. The sensor has two components: a stainless-steel lever which attaches to the plate, and an acrylic fluidic component which sits between the plate and lever. The fluidic component has a reservoir filled with radio-dense solution and an adjoining capillary wherein the fluid level is measured. When the plate bends under load, the lever squeezes the reservoir, which pushes the fluid along the channel. A tibial osteotomy model (5 mm gap) was used to simulate an unstable fracture, and allograft repair used to simulate a stiffer healed fracture. A cadaveric tibia and a mechanically equivalent composite tibia mimic were cyclically loaded five times (0 – 400 N axial force) while fluid displacement was measured from radiographs. The sensor displayed reversible and repeatable behavior with a slope of 0.096 mm/kg and fluid level noise of 50 to 80 micrometers (equivalent to 5-10 N). The allograft-repaired composite fracture was 13 times stiffer than the unstable fracture. An analysis of prior external fracture fixation studies and fatigue curves for internal plates indicates that the threshold for safe weight bearing should be 1/5th −1/10th of the initial bending for an unstable fracture. The precision of our device (<2% body weight) should thus be sufficient to track fracture healing from unstable through safe weight bearing.
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