Temperature dependent change in equilibrium elastic modulus after thermally induced stress relaxation in porcine septal cartilage

Protsenko, Dmitriy E.; Zemek, Allison; Wong, Brian J. F.

doi:10.1002/lsm.20611

Cited by 28 publications

(37 citation statements)

References 22 publications

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“…Thicker cartilage also requires a larger region of tissue axially (ie, in the direction of laser light propagation) to be heated to the threshold temperatures needed for shape change. 20,21 Simply put, this is a more challenging task, and the central region of the rabbit ear reshaped herein is more similar to the geometry of the human ear.…”

Section: Commentmentioning

confidence: 99%

Minimally Invasive Ear Reshaping With a 1450-nm Diode Laser Using Cryogen Spray Cooling in New Zealand White Rabbits

Holden

Chlebicki

Wong

2009

Arch Facial Plast Surg

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Background Otoplasty is the current standard of care for treating prominent ears, a psychologically and sometimes functionally disabling disorder. The technically demanding procedure carries many risks such as poor aesthetic outcome, need for revision surgery, and need for general anesthesia. This study investigates the use of laser irradiation combined with cryogen skin cooling and stenting to reshape cartilage in the ears of New Zealand white rabbits. Methods In this prospective, randomized, internally controlled animal study, the right ears of 9 rabbits were mechanically deformed with a jig and then irradiated with a 1450-nm diode laser combined with cryogen skin cooling (14 J/pulse with cryogen spray for 33 milliseconds per cycle and a 6-mm spot size). The left ear served as the control. The ears were splinted for 1, 3, or 4 weeks. The rabbits were then given a lethal dose of intravenous pentobarbital, and the splints were removed and ears examined and photographed. Light and confocal microscopy were performed on the specimens. Results Shape change was observed in all 9 treated rabbit ears, while none of the control ears (stenting alone) showed significant change. Qualitatively, reshaped ears were stiffer after 4 weeks of splinting than after 1 or 3 weeks. None of the rabbits showed evidence of skin injury nor did they show signs of postprocedural pain. Findings from histologic analysis in the treated areas showed evidence of an expanded chondrocyte population in the region of laser irradiation, along with some perichondrial thickening and some fibrosis of the deep dermis. Confocal microscopy revealed minimal cellular death at 1 week and none thereafter. Conclusions Cartilage reshaping using laser energy can be performed safely transcutaneously using cryogen spray cooling in rabbits. This animal model has similarity to human ears with regard to skin and cartilage thickness and is a stepping stone toward developing minimally invasive laser auricle reshaping in humans.

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Section: Commentmentioning

confidence: 99%

Minimally Invasive Ear Reshaping With a 1450-nm Diode Laser Using Cryogen Spray Cooling in New Zealand White Rabbits

Holden

Chlebicki

Wong

2009

Arch Facial Plast Surg

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“…24,25,27–29 Confocal microscopy identified a sharply demarcated, hemispherically shaped region of nonviable cells at the laser target. After irradiation at 6 W for 2 seconds, the largest extent of nonviable cells was 0.8 mm deep with a 1.9-mm surface diameter (Figure 7A).…”

Section: Resultsmentioning

confidence: 99%

“…31,32 The Nd:YAG laser operating at 1.32 μm was selected because of its near-uniform heating through the entire cartilage thickness and because the interaction between cartilage and this laser has been studied extensively by our group. 16,18,24,27,33 Although the Nd:YAG laser is an expensive precision instrument, dozens of commercially available infrared and near-infrared lasers exist that would produce essentially the same tissue effect at a fraction of the cost. Hence, the use of a laser for optimizing the warping process in surgery is economically feasible because many of these lasers are less expensive than electrocautery units.…”

Section: Commentmentioning

confidence: 99%

Stabilization of Costal Cartilage Graft Warping Using Infrared Laser Irradiation in a Porcine Model

Foulad

Ghasri²,

Garg³

et al. 2010

Arch Facial Plast Surg

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Objective To develop a method to rapidly stabilize the shape change process in peripheral slices of costal cartilage by using infrared laser irradiation in a porcine model. Methods Forty peripheral porcine costal cartilage specimens (40×10×2 mm) were harvested. Thirty of these specimens were immediately irradiated with an Nd: YAG laser (λ=1.32 μm; spot size, 2-mm diameter) using 1 of 3 exposure treatments: 6W, 2 seconds, and 4 spots; 8 W, 3 seconds, and 4 spots; or 6 W, 2 seconds, and 8 spots. Ten control specimens were only immersed in 0.9% saline solution. Angle of curvature was measured from photographs taken at 0 minutes, immediately after irradiation, and at 30 minutes, 1 hour, 5 hours, and 24 hours. Infrared imaging was used to measure surface temperatures during irradiation. Cell viability after irradiation was determined using a live/dead assay in conjunction with fluorescent confocal microscopy. Results Compared with the untreated controls, the irradiated grafts underwent accelerated shape change within the first 30 minutes to reach a stable geometry. Thereafter, irradiated grafts underwent little or no shape change, whereas the control group exhibited significant change in curvature from 30 minutes to 24 hours (P<.001). The average peak irradiated spot temperatures ranged from 76°C to 82°C. Cell viability measurements at the laser spot sites demonstrated a hemispherically shaped region of dead cells with a depth of 0.8 to 1.2 mm and a surface diameter of 1.9 to 2.7 mm. Conclusions Laser irradiation of peripheral costal cartilage slices provides an effective method for rapidly stabilizing acute shape change by accelerating the warping process. The temperature elevations necessary to achieve this are spatially limited and well within the limits of tolerable tissue injury.

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“…Previously, the back-scattered light from the cartilage was analyzed as an indicator of the temperature-dependent processes [4]. Uniaxial mechanical compression testing was also irreversibly used to study the temperature dependence of the cartilage elasticity [5]. In order to painlessly achieve a new cartilage shape for patients, an accurate and non-destructive measurement of biomechanical properties during temperature changes is highly desirable.…”

Section: Introductionmentioning

confidence: 99%

Elasticity measurement of nasal cartilage as a function of temperature using optical coherence elastography

et al. 2015

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Current clinical methods of reconstruction surgery involve laser reshaping of nasal cartilage. The process of stress relaxation caused by laser heating is the primary method to achieve nasal cartilage reshaping. Based on this, a rapid, non-destructive and accurate elasticity measurement would allow for a more robust reshaping procedure. In this work, we have utilized a phase-stabilized swept source optical coherence elastography (PhS-SSOCE) to quantify the Young's modulus of porcine nasal septal cartilage during the relaxation process induced by heating. The results show that PhS-SSOCE was able to monitor changes in elasticity of hyaline cartilage, and this method could potentially be applied in vivo during laser reshaping therapies.

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Temperature dependent change in equilibrium elastic modulus after thermally induced stress relaxation in porcine septal cartilage

Cited by 28 publications

References 22 publications

Minimally Invasive Ear Reshaping With a 1450-nm Diode Laser Using Cryogen Spray Cooling in New Zealand White Rabbits

Minimally Invasive Ear Reshaping With a 1450-nm Diode Laser Using Cryogen Spray Cooling in New Zealand White Rabbits

Stabilization of Costal Cartilage Graft Warping Using Infrared Laser Irradiation in a Porcine Model

Elasticity measurement of nasal cartilage as a function of temperature using optical coherence elastography

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