Mechanical Assessment of Tripled Hamstring Tendon When Using Suspensory Fixation for Cruciant Ligament Reconstruction-Dr. I. Geethan

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


Strobel. Manual of Arthroscopy

What’s the trouble?

The preferred femoral fixation option is Suspensory fixation


Snow et al, KSSTA 2012

Compared tripled tendon to double

Found no benefit with triple spite of increased thickness

Recommended against tripling


Many methods of tripling


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


Materials

Bovine hind foot hoof extensor tendon

Similar structural and mechanic properties as young adult


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


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


Advantages of this study

Compares three different techniques of tripling

Isolated the graft-loop interface

Suspensory fixation device, Graft thickness and length standardised


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


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?

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

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Mechanical Assessment of Tripled Hamstring Tendon When Using Suspensory Fixation for Cruciant Ligament Reconstruction-Dr. I. Geethan