Conference PaperPDF Available

Comparison of ACL hybrid graft stiffness: A porcine biomechanical study

Authors:
  • Perth Orthopaedic and Sports Medicine Centre, Perth ,Western Australia

Abstract

Background Anterior cruciate ligament (ACL) reconstruction is one of the most common orthopaedic procedures performed in Australia. Often patients who require ACL reconstructions are active individuals who value early return to activity and sport. Synthetic grafts offer immediate stability which allows for rapid recovery and early mobilisation but the most common ACL graft in Australia is autologous hamstring tendon which achieves full stability after revascularisation and ligamentisation. Hence there is an interest in hybrid grafts, which would potentially have benefits of both. To date there are no biomechanical studies on hybrid grafts in the current literature. Objectives: To analyse stiffness and load to failure of two proposed hybrid ACL synthetic/tendon hybrid graft options compared to a all tendon control at time zero of implantation. Hypothesis: Hybrid graft will be stiffer with greater load to failure than tendon alone. Methodology: We will use porcine flexor profundus tendons in this biomechanical study, randomly divided equally into 3 groups. The control group will be tendon only, doubled or tripled as necessary to create a graft approximately the usual standard size of 8-9mm diameter. This will be compared to the test groups, one of which will be a combination of tendon and LARS, the other being tendon and FibreTape. Total graft diameter in the hybrid groups should be equivalent to that in the control group and should be of equal length. The grafts will be held at either end in freezing grips. The grafts will be pre tensioned with 20 cycles from 5N to 50N, cyclically loaded from 50N to 200N for 1500 cycles, then finally loaded to failure. Fresh frozen porcine trotters will be acquired and thawed to room temperature before preparation. Flexor profundus tendon will be dissected and each tendon examined for degenerative or pathologic changes. During preparation and testing, tendons should be kept moist by spraying 0.9% saline solution. Total sample size should be calculated following a pilot study of 9 specimens, randomly divided into 3 groups. An a priori method of power analysis will be applied and used to determine final sample sizes before proceeding. Elongation of the grafts will be measured to determine stiffness, as well as load to failure and method of failure for each specimen. Definition for failure will be measured as the maximum traction force at which a sudden decrease or discontinuity of the load-displacement curve occurs. Results: The biomechanical properties of the 3 graft constructs will be presented. Potential differences and the clinical significance will be discussed
2017 Combined Orthopaedic Knee Societies Meeting of Australia, Britain, New Zealand and South Africa (COKS)
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Name: Peter Annear
Email Address: peteandnic@highway1.com.au
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3
Abstract Formatting Guide
To publish the abstract in OJSM, the template below MUST be followed exactly.
1. Article Title (Sentence case, 14 Point Arial Bold)
Comparison of ACL hybrid graft stiffness: A porcine
biomechanical study.
2. Applicant’s name (Sentence case, 12 Point Arial Bold with presenter first)
First Last, DG1, First Last, DG, DG2, First Last DG, DG3
1Institution, City, State, Country, 2Institution, City, Country
Joseph Henry 1, Peter Annear2, Alan Kop 3.
1 Fremantle Hospital, Perth, WA, Australia,2 Perth Orthopaedics and Sports
Medicine Centre, Perth, Australia, 3 Medical Engineering & Physics, Royal Perth
Hospital, Perth, Australia.
3. Body of Abstract (Sentence case, 12 Point Arial)
Maximum 500 words, excluding headings but including references
Do not include graphs or diagrams
Use abbreviations only for common terms; for uncommon terms give abbreviation in brackets after first full use of the term.
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Background
Anterior cruciate ligament (ACL) reconstruction is one of the most common
orthopaedic procedures performed in Australia. Often patients who require
ACL reconstructions are active individuals who value early return to activity
and sport. Synthetic grafts offer immediate stability which allows for rapid
recovery and early mobilisation but the most common ACL graft in
Australia is autologous hamstring tendon which achieves full stability after
revascularisation and ligamentisation. Hence there is an interest in hybrid
grafts, which would potentially have benefits of both. To date there are no
biomechanical studies on hybrid grafts in the current literature.
4
Objectives:
To analyse stiffness and load to failure of two proposed hybrid ACL
synthetic/tendon hybrid graft options compared to a all tendon control at
time zero of implantation.
Hypothesis:
Hybrid graft will be stiffer with greater load to failure than tendon alone.
Methodology:
We will use porcine flexor profundus tendons in this biomechanical study,
randomly divided equally into 3 groups. The control group will be tendon
only, doubled or tripled as necessary to create a graft approximately the
usual standard size of 8-9mm diameter. This will be compared to the test
groups, one of which will be a combination of tendon and LARS, the other
being tendon and FibreTape. Total graft diameter in the hybrid groups
should be equivalent to that in the control group and should be of equal
length. The grafts will be held at either end in freezing grips. The grafts
will be pre tensioned with 20 cycles from 5N to 50N, cyclically loaded from
50N to 200N for 1500 cycles, then finally loaded to failure.
Fresh frozen porcine trotters will be acquired and thawed to room
temperature before preparation. Flexor profundus tendon will be dissected
and each tendon examined for degenerative or pathologic changes.
During preparation and testing, tendons should be kept moist by spraying
0.9% saline solution. Total sample size should be calculated following a
pilot study of 9 specimens, randomly divided into 3 groups. An a priori
method of power analysis will be applied and used to determine final
sample sizes before proceeding.
Elongation of the grafts will be measured to determine stiffness, as well as
load to failure and method of failure for each specimen. Definition for
failure will be measured as the maximum traction force at which a sudden
decrease or discontinuity of the load-displacement curve occurs.
Results: The biomechanical properties of the 3 graft constructs will be
presented. Potential differences and the clinical significance will be
discussed Sentence case, 12 Point Arial
.
5
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Re: { Comparison of ACL hybrid graft stiffness: A porcine biomechanical study.
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