Characterization of the Performance of a Custom Program for Image Processing of Pressure Sensitive Film

Muriuki, Muturi; Gilbertson, Lars G.; Harner, Christopher D.

doi:10.1115/1.3005150

Cited by 12 publications

(14 citation statements)

References 31 publications

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“…The scanned images were converted into contact congruency measures via a previously developed calibration program relating the image intensity to contact pressure. 30 All image processing and analyses were performed using custom MATLAB programs (Mathworks Inc).…”

Section: Methodsmentioning

confidence: 99%

Vertical Tears of the Lateral Meniscus

Goyal

Pan

Tran

et al. 2014

Orthopaedic Journal of Sports Medicine

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Background:Lateral meniscal tears are often seen with acute anterior cruciate ligament (ACL) injury and may be left in situ, repaired, or treated with meniscectomy. Clinical studies have shown good outcomes with vertical tears left in situ and poor outcomes following meniscectomy. However, clinically relevant studies are needed to establish a biomechanical foundation for treatment of these tears, particularly regarding the effects of meniscectomy.Purpose:To compare tibiofemoral joint mechanics following vertical lateral meniscal tears and meniscectomies. We hypothesized that a peripheral vertical tear of the lateral meniscus would alter joint mechanics, increasing contact pressure and area, and that more drastic effects would be seen following meniscectomy, at higher knee flexion angles, and with increased loads.Study Design:Controlled laboratory study.Methods:Ten fresh-frozen cadaveric knees (average age, 55 ± 12 years) were tested with 5 lateral meniscus states: intact, short vertical tear, extended vertical tear, posterior horn partial meniscectomy (rim intact), and posterior horn subtotal meniscectomy (rim excised). The specimens were loaded axially at knee flexion angles of 0°, 30°, and 60°, and musculotendinous forces were applied, simulating a 2-legged squat. Intra-articular contact pressures were measured using pressure-sensitive Fuji film. Kinematic data were acquired through digitization of fiducial markers.Results:Vertical tears did not cause a significant change in contact pressure or area. Partial meniscectomy increased maximum contact pressures in the lateral compartment at 30° and 60° from 5.3 MPa to 7.2 MPa and 7.6 MPa, respectively (P = .02, P = .007). Subtotal meniscectomy (8.4 MPa) significantly increased contact pressure compared with partial meniscectomy (7.6 MPa) at 60° (P = .04). Both meniscectomy states significantly increased contact pressures with increasing flexion from 0° to 60° (P < .001, P < .001).Conclusion:Vertical tears of the lateral meniscus during a simulated 2-legged squat did not significantly change contact pressures and areas compared with an intact meniscus. However, treating these tears with partial and complete meniscectomy significantly increased maximum contact pressures.Clinical Relevance:Biomechanical evidence supports treating vertical lateral meniscus tears with meniscal-sparing techniques as opposed to meniscectomy, which may lead to progressive degenerative joint disease from altered joint biomechanics.

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Section: Methodsmentioning

confidence: 99%

Vertical Tears of the Lateral Meniscus

Goyal

Pan

Tran

et al. 2014

Orthopaedic Journal of Sports Medicine

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“…A limitation of this study is that although we followed a filtering method that is validated against commercial packages, 46 defining the size of the averaging area remains subjective, thereby affecting the level of the estimated pressure values. A second limitation is that in order to reduce measurement error caused by the limited resolution of the pressure films, 49 the area of the end effector was scaled up about 8-10 times compared to laparoscopic end effectors.…”

Section: Discussionmentioning

confidence: 99%

“…The literature suggests a variety of filtering techniques, including matching positionally corresponding pixels of several stains obtained by the same object under the same pressure and calculating their mean to generate ‘average stain image’ data, 45 or replacing each pixel colour value with the average value of the pixels in a surrounded pixel area of certain size. 46 We followed the latter approach. To identify the size of the surrounded pixel area that would be the most appropriate for smoothening, stain images were generated for averaging areas ranging between 9 × 9 and 121 × 121 pixels, which, for a resolution of 1200 dpi, correspond to areas between 0.036 and 6.56 mm 2 .…”

Section: Methodsmentioning

confidence: 99%

Methods for reducing peak pressure in laparoscopic grasping

Bos

Doornebosch

Engbers

et al. 2013

Proc Inst Mech Eng H

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During tissue retraction with a laparoscopic grasper, tissue-damaging pressures can occur. Past research suggests that peak pressures can be considerably reduced by rounding the edges or covering the tip of the end effector with a silicon sleeve. To identify grasping methods that limit tissue damage, the effects of (a) Young's modulus of the end effector, (b) curvature of the end effector, and (c) angle with which the tissue is pulled relative to the plane of the end effector, on the pressure generated on the tissue were investigated. Artificial skin was placed between two non-serrated jaws, a pressure-sensitive film was interposed between the skin and upper jaw, and the end effector was loaded with 13 N. End effectors with Young's moduli of 0.09, 0.67, 1.49 MPa, and 69 GPa, and with non-rounded and 5 mm rounded edges were tested under pulling angles of 25°, 50°, and 75°. For non-rounded end effectors, the maximum pressure and the area across which pressure exceeded the safety threshold for tissue damage increased with Young's modulus and pulling angle. For rounded end effectors, maximum pressure did not increase monotonically with Young's modulus. Instead, the end effector with the second lowest Young's modulus yielded significantly lower maximum pressure than the end effector with the lowest Young's modulus. For rounded end effectors, pressures were below the safety threshold for all Young's moduli. This indicates that to prevent tissue damage, soft graspers may not be needed; rounding the edges of metal graspers could suffice for preventing tissue damage.

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“…The test fixture was composed of two parts: the first, a precision ground base onto which the film was placed and the second component was a precision ground cylindrical shaped indenter, which was placed in the hydraulic grips of a servo-hydraulic test frame tension/compression testing machine. The use of indenter-type calibration methods for pressure film is not new, and a variety of researchers 15–17 have used variations on the indenter technique to produce calibration curves relating stain intensity and applied pressure. Slight variations in the uniformity of the stain were taken care of using image averaging techniques similar to those used by Liggins and Finlay.…”

Section: Experimental Methodsmentioning

confidence: 99%

A comparison of the effect of riveting and cold expansion on the strain distribution and fatigue performance of fiber metal laminates

Bäckman

Patterson

2013

The Journal of Strain Analysis for Engineering Design

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Fatigue tests carried out on three configurations (unexpanded, cold expanded and riveted) of fiber metal laminate material clearly demonstrated the beneficial effect of riveting compared to cold expansion in zero load transfer joints, for an approximately equivalent level of interference. Digital image correlation was used to measure the in-plane surface strain on cold expanded and riveted coupons during fatigue loading, and for the first time, digital image correlation was combined with pressure sensitive films to measure the strains resulting from the application of the rivet, including those under the rivet head. A comparison of the resultant strain field showed that the application of a rivet significantly reduces the stress concentration at the central hole and is effective in extending fatigue life. Some rivet heads were removed by milling, and the results from subsequent fatigue tests were used together with closed-form calculations to explain the findings of this study. It was concluded that the beneficial effect of riveting was less as a result of interference hole filling on the part of the rivet shank, but more a combination of the effect of interference and compression through the joint thickness.

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Characterization of the Performance of a Custom Program for Image Processing of Pressure Sensitive Film

Cited by 12 publications

References 31 publications

Vertical Tears of the Lateral Meniscus

Vertical Tears of the Lateral Meniscus

Methods for reducing peak pressure in laparoscopic grasping

A comparison of the effect of riveting and cold expansion on the strain distribution and fatigue performance of fiber metal laminates

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