Effect of Suture Caliber and Number of Core Strands on Repair of Acute Achilles Ruptures: A Biomechanical Study

2017 ◽  
Vol 38 (5) ◽  
pp. 564-570 ◽  
Author(s):  
Jonathon D. Backus ◽  
Daniel Cole Marchetti ◽  
Erik L. Slette ◽  
Kimi D. Dahl ◽  
Travis Lee Turnbull ◽  
...  
Keyword(s):  
Biomechanical Study ◽  
Published Data ◽  
Postoperative Rehabilitation ◽  
Rehabilitation Protocol ◽  
Advanced Stages ◽  
Number Of Cycles ◽  
Active Patients ◽  
Repair Group ◽  
Cycles To Failure ◽  
The Ideal

Background: Controversy exists regarding the ideal Achilles rupture treatment; however, operative treatment is considered for athletes and active patients. The ideal repair construct is evolving, and the effect of suture caliber or number of core strands has not been studied. Methods: Simulated mid-substance Achilles ruptures were performed in 24 cadavers. Specimens were randomized to three 6-core-strand style repair constructs: (1) 4 No. 2 sutures and two 2-mm tapes (2T); (2) 2 No. 2 sutures and four 2-mm tapes (4T); (3) 12 (double-6-strand) strand repair (12 No. 2-0 sutures [12S]). Repairs were subjected to a cyclic loading protocol representative of postoperative rehabilitation. These data were compared to a previously published standard open repair technique (6-core strands with No. 2 sutures) on 9 specimens tested under the same conditions.6 Results: No significant elongation differences were observed between the repair groups and the previously published standard repair group in the first 2 stages of the simulated rehabilitation protocol. Both the 2T and 12S repairs survived a significantly greater number of cycles to failure ( P = 0.0005, P = 0.0267, respectively) and had a significantly higher failure load ( P = .0005, P = .0118, respectively) compared to the previously published data. These 2 constructs consistently survived the advanced stages of the simulated rehabilitation protocol. The majority of repairs failed at the knots. Conclusions: In this study, the 2T and 12S constructs survived the later stages of our simulated rehabilitation protocol, suggesting that they may be able to accommodate a more aggressive clinical rehabilitation protocol. Substituting suture-tape for 2 core strands or doubling the core strands with a smaller-caliber suture created a biomechanically stronger construct. Clinical Relevance: Achilles repair with an added nonabsorbable, high–tensile strength tape allowed for a stronger construct that may allow for a more aggressive, early rehabilitation protocol and earlier return to function.

Pediatric Replantation after Traumatic Amputation at the Distal Forearm: Rehabilitation Protocol and Outcomes

2020 ◽  
Author(s):  
Nicholas C. Oleck ◽  
Radhika Malhotra ◽  
Haripriya S. Ayyala ◽  
Ramazi O. Datiashvili
Keyword(s):  
Operating Room ◽  
Multidisciplinary Team ◽  
Distal Forearm ◽  
Left Forearm ◽  
Traumatic Amputation ◽  
Postoperative Rehabilitation ◽  
Rehabilitation Protocol ◽  
Microsurgical Technique ◽  
Optimal Function ◽  
And Function

AbstractMajor limb replantation is a formidable task, especially in the pediatric setting. While meticulous microsurgical technique is required in the operating room, the authors aim to highlight the importance of postoperative rehabilitation therapy for optimal function. We highlight the case of a 12-year-old boy who suffered complete traumatic amputation through the distal left forearm. The limb was successfully replanted with successful restoration of sensation and function with the aid of intensive postoperative occupational therapy. A multidisciplinary team is of paramount importance to maximize function of a replanted upper extremity.

Fatigue Life of the Human Teeth: A Continuum Damage Approach

2019 ◽  
Vol 43 ◽  
pp. 1-19
Author(s):  
Theddeus Tochukwu Akano
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Stress Amplitude ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Elastoplastic Model ◽  
Human Teeth ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Cycles To Failure

Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

In search of the perfect orthography

2005 ◽  
Vol 7 (2) ◽  
pp. 139-163 ◽  
Author(s):  
Richard L. Venezky
Keyword(s):  
Writing System ◽  
Writing Systems ◽  
International Phonetic Alphabet ◽  
Experienced Reader ◽  
Cultural Considerations ◽  
Advanced Stages ◽  
One To One ◽  
The One ◽  
Psychological Processing ◽  
The Ideal

Philologists, linguists, and educators have insisted for several centuries that the ideal orthography has a one-to-one correspondence between grapheme and phoneme. Others, however, have suggested deviations for such functions as distinguishing homophones, displaying popular alternative spellings, and retaining morpheme identity. If, indeed, the one-to-one ideal were accepted, the International Phonetic Alphabet should become the orthographic standard for all enlightened nations, yet the failure of even a single country to adopt it for practical writing suggests that other factors besides phonology are considered important for a writing system. Whatever the ideal orthography might be, the practical writing systems adopted upon this earth reflect linguistic, psychological, and cultural considerations. Knowingly or unknowingly, countries have adopted orthographies that favour either the early stages of learning to read or the advanced stages, that is, the experienced reader. The more a system tends towards a one-to-one relationship between graphemes and phonemes, the more it assists the new reader and the non-speaker of the language while the more it marks etymology and morphology, the more it favours the experienced reader. The study of psychological processing in reading demonstrates that human capacities for processing print are so powerful that complex patterns and irregularities pose only a small challenge. Orthographic regularity is extracted from lexical input and used to recognise words during reading. To understand how such a system develops, researchers should draw on the general mechanisms of perceptual learning.

Unification proposals for fatigue crack propagation laws

2017 ◽  
Vol 13 (2) ◽  
pp. 262-283 ◽  
Author(s):  
Vladimir Kobelev
Keyword(s):  
Differential Equation ◽  
Crack Propagation ◽  
Crack Length ◽  
Closed Form ◽  
Crack Growth ◽  
Stress Ratio ◽  
Elementary Functions ◽  
Content Type ◽  
Number Of Cycles ◽  
Cycles To Failure

Purpose The purpose of this paper is to propose the new dependences of cycles to failure for a given initial crack length upon the stress amplitude in the linear fracture approach. The anticipated unified propagation function describes the infinitesimal crack-length growths per increasing number of load cycles, supposing that the load ratio remains constant over the load history. Two unification functions with different number of fitting parameters are proposed. On one hand, the closed-form analytical solutions facilitate the universal fitting of the constants of the fatigue law over all stages of fatigue. On the other hand, the closed-form solution eases the application of the fatigue law, because the solution of nonlinear differential equation turns out to be dispensable. The main advantage of the proposed functions is the possibility of having closed-form analytical solutions for the unified crack growth law. Moreover, the mean stress dependence is the immediate consequence of the proposed law. The corresponding formulas for crack length over the number of cycles are derived. Design/methodology/approach In this paper, the method of representation of crack propagation functions through appropriate elementary functions is employed. The choice of the elementary functions is motivated by the phenomenological data and covers a broad region of possible parameters. With the introduced crack propagation functions, differential equations describing the crack propagation are solved rigorously. Findings The resulting closed-form solutions allow the evaluation of crack propagation histories on one hand, and the effects of stress ratio on crack propagation on the other hand. The explicit formulas for crack length over the number of cycles are derived. Research limitations/implications In this paper, linear fracture mechanics approach is assumed. Practical implications Shortening of evaluation time for fatigue crack growth. Simplification of the computer codes due to the elimination of solution of differential equation. Standardization of experiments for crack growth. Originality/value This paper introduces the closed-form analytical expression for crack length over number of cycles. The new function that expresses the damage growth per cycle is also introduced. This function allows closed-form analytical solution for crack length. The solution expresses the number of cycles to failure as the function of the initial size of the crack and eliminates the solution of the nonlinear ordinary differential equation of the first order. The different common expressions, which account for the influence of the stress ratio, are immediately applicable.

scholarly journals Retear rates after rotator cuff surgery: a systematic review and meta-analysis

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Umile Giuseppe Longo ◽  
Arianna Carnevale ◽  
Ilaria Piergentili ◽  
Alessandra Berton ◽  
Vincenzo Candela ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Meta Analysis ◽  
Fatty Infiltration ◽  
Surgical Techniques ◽  
Postoperative Rehabilitation ◽  
Rehabilitation Protocol ◽  
Factors Influencing ◽  
Main Factors ◽  
Tear Size

Abstract Background Rotator cuff retear (RCR) is one of the main postoperative drawbacks. RCR can be considered a multifactorial issue, which causes are related either to biological than biomechanical factors. The aim of this study was to define the incidence of RCR after surgical treatment at different time points and to identify the main factors influencing the postoperative rotator cuff (RC) healing. Methods A systematic review and meta-analysis were performed following the PRISMA guidelines. A comprehensive search of the literature was carried out in July 2020, using PubMed and Cochrane Library databases. Only level 1 and 2 clinical evidence studies were included. Studies were included if patients with preoperative repairable full-thickness RC tears were treated surgically, and if studies reported postoperative RCR confirmed by imaging diagnostic. The association between timing of retear and follow-up time points were investigated using an inverse-variance method of pooling data. A subgroup meta-analysis was performed using the DerSimonian and Laird method for the estimation of the between-study variance, i.e., τ2. The association between retear rate after surgery and patients’ age, preoperative tear size, fatty infiltration, postoperative rehabilitation protocol, surgical techniques, and RC repairs was determined by expressing the effect measure in terms of odds ratio (OR) with 95% confidence interval (CI). The Mantel-Haenszel method with 95% CIs was used. Results Thirty-one articles were included in this study. The percentage of RCR after surgery was 15% at 3 months follow-up, 21% at 3–6 months follow-up, 16% at 6–12 months follow-up, 21% at 12–24 months follow-up, 16% at follow-up longer than 24 months. The main factors influencing RC healing are both patient-related (i.e., age, larger tear size, fatty infiltration) and not patient-related (i.e., postoperative rehabilitation protocol, surgical techniques, and procedures). Conclusions Postoperative RC healing is influenced by patient-related and non-patient-related factors. Further high-level clinical studies are needed to provide highly relevant clinical results.

scholarly journals 4SM: A Novel Self-calibrated Algebraic Ratio Method for Satellite Derived Bathymetry and Water Column Correction

2017 ◽  
Author(s):  
Yann George MOREL
Keyword(s):  
Water Column ◽  
Radiative Transfer Equation ◽  
Atmospheric Correction ◽  
Ratio Method ◽  
Published Data ◽  
Deep Waters ◽  
Bare Land ◽  
Depth Sounding ◽  
Radiance Data ◽  
The Ideal

All empirical water column correction methods have consistently been reported to require existing depth sounding data for the purpose of calibrating a simple depth retrieval model; they yield poor results over very bright or very dark bottoms. In contrast, we set out to (i) use only the relative radiance data in the image along with published data, and several new assumptions, (ii) in order to specify and operate the simplified radiative transfer equation (RTE), (iii) for the purpose of retrieving both the satellite derived bathymetry (SDB) and the water column corrected spectral reflectance over shallow seabeds. Sea truth regressions show that SDB depths retrieved by the method only need tide correction. Therefore it shall be demonstrated that, under such new assumptions, there is no need (i) for formal atmospheric correction, (ii) nor for conversion of relative radiance into calibrated reflectance , (iii) nor for existing depth sounding data, to specify the simplified RTE and produce both SDB and spectral water column corrected radiance ready for bottom typing. Moreover, the use of the panchromatic band for that purpose is introduced. Altogether, we named this process the Self-Calibrated Supervised Spectral Shallow-sea Modeler (4SM). This approach requires a trained practitioner, though, to produce its results within hours of downloading the raw image. The ideal raw image should be a “near-nadir” view, exhibit homogeneous atmosphere and water column, include some coverage of optically deep waters and bare land, and lend itself to quality removal of haze, atmospheric adjacency effect, and sun/sky glint.

Lifetime estimation for a land-fast ice sheet subjected to ocean swell

2001 ◽  
Vol 33 ◽  
pp. 333-338 ◽  
Author(s):  
P. J. Langhorne ◽  
V. A. Squire ◽  
C. Fox ◽  
T. G. Haskell
Keyword(s):  
Sea Ice ◽  
Strain Field ◽  
Field Experiments ◽  
Ice Sheet ◽  
Lifetime Estimation ◽  
Spectral Content ◽  
Fast Ice ◽  
Damage Law ◽  
Number Of Cycles ◽  
Cycles To Failure

AbstractIt is well known that an incoming ocean swell produces a strain field in a land-fast ice sheet. The attenuation and spectral content of this strain field can be calculated and has been measured. The response of the sea ice to this type of cyclic forcing has also been measured, and in particular we are able to estimate the number of cycles to failure for sea ice loaded at constant amplitude. In this paper we consider the response of the land-fast ice sheet or vast floe to a measured ice-coupled wave field of variable amplitude. We use the Palmgren-Miner cumulative damage law and stress-lifetime curves taken from field experiments to predict the lifetime of the sea-ice sheet as a function of significant wave height and sea-ice brine fraction. Calculations are performed to account for the swell entering a land-fast sea-ice sheet at arbitrary angle, and the influence of c-axis alignment and the presence of pre-existing cracks are discussed.

Staple-Plate Plus Screw vs Screw Alone in Talonavicular Arthrodesis: A Cadaveric Biomechanical Study

2020 ◽  
Vol 41 (11) ◽  
pp. 1427-1431
Author(s):  
Joseph T. O’Neil ◽  
Pooyan Abbasi ◽  
Brent G. Parks ◽  
Stuart D. Miller
Keyword(s):  
Mechanical Stability ◽  
External Rotation ◽  
Biomechanical Study ◽  
Cannulated Screw ◽  
Talonavicular Joint ◽  
Fusion Procedure ◽  
Plate Group ◽  
Significant Difference ◽  
Implant Selection ◽  
Cycles To Failure

Background: This study evaluated whether the addition of a nitinol staple-plate to a single cannulated screw increased the mechanical stability for a talonavicular fixation construct. Methods: Twenty matched pairs of cadaveric feet were randomized to fusion with either a single 5.5-mm cannulated screw or a screw and a plate with 2 screws and a slot with an 18-mm nitinol staple. After in situ fusion procedure, the talonavicular joint complex was dissected free and the ends were embedded in epoxy. The specimens were then cyclically loaded on a servohydraulic load frame (1000 cycles at 20 N, increasing at intervals of 20 N until failure), half of them for cantilever bending and the other half for torsion. Results: In the bending arm of the study, the staple-plate group showed significantly higher stiffness, failure load, and cycles to failure. In the torsion arm of the study, the staple-plate group also had higher cycles to failure, stiffness in external rotation, and torque to failure. No significant difference was noted in stiffness in internal rotation. Conclusion: We found a significant increase in stability of the talonavicular joint when a nitinol staple-plate construct was placed to augment a single cannulated screw for the purpose of a talonavicular fusion. Clinical Relevance: This information may be helpful to surgeons in implant selection for this common arthrodesis procedure.

Mechanical Fatigue Limit for Rubber

1966 ◽  
Vol 39 (2) ◽  
pp. 348-364 ◽  
Author(s):  
G. J. Lake ◽  
P. B. Lindley
Keyword(s):  
Fatigue Limit ◽  
Growth Behavior ◽  
Energy Characteristics ◽  
Mechanical Fatigue ◽  
Tearing Energy ◽  
Number Of Cycles ◽  
Cycles To Failure ◽  
Limiting Value ◽  
Mechanical Rupture

Abstract Investigations of the dynamic cut growth behavior of vulcanized rubbers indicate that there is a minimum tearing energy at which mechanical rupture of chains occurs. The limiting value is characteristic of each vulcanizate, but is in the region of 0.05 kg/cm. The mechanical fatigue limit, below which the number of cycles to failure increases rapidly, is accurately predicted from this critical tearing energy. Characteristics of cut growth at low tearing energies, and effects of polymer, vulcanizing system, oxygen, and fillers on the critical tearing energy and fatigue limit are discussed.

Sign in / Sign up

Export Citation Format

Share Document