Mechanical assessment of tripled hamstring tendon when using
suspensory fixation for cruciate ligament reconstruction
DR. GEETHAN I MS(ORTH) DNB(ORTH)
Triple = trouble?
Dr. David V Rajan
Dr. Clement J Joseph
Dr. Santhosh Sahanand
Dr. Ashwin Vijay
No conflicts of interest in the authorship and presentation of this paper.
Co-Authors
Background
ACL reconstruction is one of the commonly performed arthroscopic procedures
Hamstring graft is used by many surgeons
Chechik et al, SICOT 2013
An international survey on anterior cruciate ligament reconstruction practices
Why triple?
Usual length of semitendinosus tendon is 28 – 32 cm.
Double 15 cm
Triple 10 cm
Quadruple 7-8 cm
2 cm
4 cm
2.5- 3 cm
Total 9 cm
Chiang et al, KSSTA 2012
Triple without trouble, IASCON 2014
Lavery et al, Arthroscopy Techniques 2014 (3)
Lee KSSTA 2013
Snow et al KSSTA 2012
Triple without trouble, IASCON 2014
Strobel. Manual of Arthroscopy
What’s the trouble?
The preferred femoral fixation option is Suspensory fixation
Triple without trouble, IASCON 2014
Snow et al, KSSTA 2012
Compared tripled tendon to double
Found no benefit with triple spite of increased thickness
Recommended against tripling
Triple without trouble, IASCON 2014
Many methods of tripling
Triple without trouble, IASCON 2014
Lavery et al, Arthroscopy Techniques 2014 (3)
Lee KSSTA 2013
Snow et al KSSTA 2012
Strobel. Manual of Arthroscopy
Purpose To compare to mechanical properties of tripled
graft prepared by three different methods
Hypothesis Tripled graft will have variable mechanical
properties depending on the way of preparation
Triple without trouble, IASCON 2014
Materials
Bovine hind foot hoof extensor tendon
Similar structural and mechanic properties as young adult
Triple without trouble, IASCON 2014
Tripled Graft Configurations
Group II Group III Group IV
Group I
Test Construct
• Instron Material testing system- fully automated
• All parameters entered into software
• All data measured by the system and read off the computer screen, and output print outTriple without trouble, IASCON 2014
Mechanical assessmentTest Protocol
Preloading 10 to 50 N at 0.1 Hz for 10 cycles
Cyclic Loading 1000 cycles ; 50 and 250N at a frequency of 0.5 Hz.
Distraction to failure 50mm/min
As reported by Petre et al, AJSM; 2013
Results
Displacement
Group I 1.13 ± 0.11 mm
Group II 4.91 ± 0.49 mm
Group III 1.822 ± 0.55 mm
Group IV 1. 126 ± .018 mm
All samples survived cyclical loading
3mm is considered acceptable displacementDaniel DM, Stone ML, Sachs R, Malcom L. Instrumented measurement of anterior
knee laxity in patients with acute anterior cruciate ligament disruption. Am J Sports Med. 1985;13(6):401-407
Group
s
Observed ‘t’
value
Table ‘t’ value ‘p’ value
Displacemen
t
I Vs. II 16.92 3.355 ( p =
0.01)
p < 0.01
I Vs. III 11.15 3.355 ( p =
0.01)
p < 0.01
I Vs. IV 0.044 1.806 ( p =
0.10)
P > 0.10
Ultimate load at failure
Group I 957 ± 23.30 N
Group II 590.8 ± 26.55 N
Group III 682.6 ± 59.28 N
Group IV 963.4 ± 21.72 N
Grafts may be subjected to loads of upto 600N during normal rehabilitation
Group
s
Observed ‘t’
value
Table ‘t’
value
‘p’ value
Load at
failure
I Vs. II 24.27 3.355 ( p =
0.01)
p < 0.01
I Vs. III 9.63 3.355 ( p =
0.01)
p < 0.01
I Vs. IV 0.45 1.806 ( p =
0.10)
P > 0.10
Ettinger M, Petri M, Kwisda S, Krettek C, Jagodzinski M. Biomechanical Considerations for Graft Fixation in ACL Reconstruction. Techniques in Orthopaedics. 2013;28(2): 126-132.
Mode of failure
Group I Group IV
Triple without trouble, IASCON 2014
Mode of Failure
Group II Group III
Prior studies…Snow et al, KSSTA 2012 No difference between double and triple
All the failures at interference screw
Uneven distribution of load across three strands
Triple without trouble, IASCON 2014
Advantages of this study
Compares three different techniques of tripling
Isolated the graft-loop interface
Suspensory fixation device, Graft thickness and length standardised
Triple without trouble, IASCON 2014
Limitations
Tibial fixation is with a vice grip
In vitro study Loading represents extreme case scenario
Unidirectional loading
Role of graft healing is not studied
Stiffness is not reported
Differential loading is not studied
Triple without trouble, IASCON 2014
Conclusions Hypothesis that tripled tendon configuration
have variable mechanic properties is found true.
Triple strand configurations studied in Group II and Group III in our study are significantly mechanically inferior.
Suturing the three strands together as in Group IV has equivalent mechanical properties as quadrupled strand in our controlled laboratory study
Triple without trouble, IASCON 2014
Triple without trouble?
What this study tells the surgeon?
Tripled grafts have variable mechanical properties and the surgeon should consider the inferior mechanical properties while choosing to triple graft.
Surgeon should consider suturing the three strands of graft together increase ultimate failure load.
Thank You