Clin Orthop Surg.  2014 Jun;6(2):173-179. 10.4055/cios.2014.6.2.173.

A Comparison of the Fixation Strengths Provided by Different Intraosseous Tendon Lengths during Anterior Cruciate Ligament Reconstruction: A Biomechanical Study in a Porcine Tibial Model

• Yang DL
• Cheon SH
• Oh CW
• Kyung HS

• KMID: 1784663
• DOI: http://doi.org/10.4055/cios.2014.6.2.173

Abstract

BACKGROUND
The purpose of this study was to determine the tibial fixation strength provided by different intraosseous soft tissue graft lengths within the tibial tunnel.
METHODS
Porcine tibial bones and digital flexor tendons were used for testing. Bone mineral densities of proximal tibial medial condyles were measured, and two-strand tendon bundles of 8 mm diameter were used. An intraosseous graft length of 2 cm was used in group 1 (n = 10), and a graft length of 4 cm was used in group 2 (n = 10). Tunnels were 4 cm in length and 8 mm in diameter. Tibial fixation was performed using a suture tied around a screw post with a washer and an additionally inserted 7 x 20 mm bioabsorbable screw. After applying preconditioning loading of 10 cycles, 1,000 cycles between 70-220 N were applied at a frequency of 1 Hz. Graft slippage and total graft movement were recorded. Ultimate tensile strength was measured by pull-out testing at an Instron crosshead speed of 1,000 mm/min.
RESULTS
No significant intergroup difference was found for total graft movement after cyclic loading (slippage in group 1, 1.2 mm and group 2, 1.2 mm, respectively, p = 0.917; and total graft movement in group 1, 3.3 mm and group 2, 2.7 mm, respectively, p = 0.199). However, mean ultimate tensile strength in group 2 was significantly higher than that in group 1 (group 1, 649.9 N; group 2, 938 N; p = 0.008).
CONCLUSIONS
In a porcine model, ultimate tensile strength was greater for a 4 cm long intraosseous flexor tendon in the tibial tunnel. However, no intergroup difference in graft slippage or total graft movement was observed. The results show that a 2 cm intraosseous graft length in the tibial tunnel is safe and has sufficient strength (> 450 N) for adequate rehabilitation after anterior cruciate ligament reconstruction.

Keyword

Fixation strength; Tendon length; Anterior cruciate ligament reconstruction; Biomechanical study

MeSH Terms

Animals
Anterior Cruciate Ligament/injuries/*physiopathology/surgery
*Anterior Cruciate Ligament Reconstruction
Biomechanical Phenomena
Bone Density
Models, Animal
Swine
Tendons/*transplantation
Tensile Strength
Tibia/*surgery

Figure

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  Fig. 1 Graft preparation.

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  Fig. 2 Grafts in tibial tunnels. Drawing of a 2-cm long graft (A) and a 4-cm long graft (B) in intraosseous tunnels. *Indicates a bioabsorbable interference screw. (C) Tendon graft was fixed at the tibial tunnel by a post-tie suture and a bioabsorbable screw.

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  Fig. 3 Experimental set-up for load testing, showing tension being applied parallel to the tibial bone tunnel.

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  Fig. 4 Tibial graft slippage under cyclical loading.

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  Fig. 5 Ultimate tensile strength of fixation.

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