Abstract
Introduction
Tendon injuries remain challenging, secondary healing and prolonged immobilisation result in suboptimal outcome. Previous study by our group showed that demineralised bone matrix (DBM) can result in faster healing of a tendon enthesis. The aim of this study is to test different ways augmenting tendon with DBM to enhance tendon repair and regeneration.
Methods
DBM strips were prepared from tibias of mature ewes. Patella, patellar tendon and tibias were dissected and the distal 1 cm of the patellar tendon was excised.
4 models were designed;
Model-1, DBM strip was used to bridge the gap between the tendon and the tibial tuberosity. The DBM strip was stitched to the tendon using one bone anchor.
Model-2, similar to model 1 with the use of 2 anchors.
Model-3, similar to model 2, construct was off loaded by continuous thread looped twice through bony tunnels sited in the patella and in the tibial tuberosity.
Model-4, similar to model 3 with 3 threads as off loading loop.
All models were tested for pullout force and mode of failure.
Results
The median failure force for model-1 (N=5) was 250N while for model-2 (N=5) was 290N. In model-3 and model-4 failure of the off loading loop was used as end point, 6 samples were tested in each model. Median failure force of model-3 was 767N and for model-4 was 934N.
There was no statistical significance between model-1 and model-2 (p=0.249), however statistical significance was found between other models (p=< 0.006).
Discussion
A study published in 1996 proved that cortical DBM can be used as ACL graft with evidence of ligamentisation. DBM provides a biologic scaffold with potential for use as ligament and tendon replacement. Our study shows that a tendon rupture can be augmented with DBM giving intial appropriate mechanical strength suitable for in-vivo use.
