Biomedical Engineering Reference
In-Depth Information
the native ligament and is believed to be beneficial to the
reconstruction as it increases the mechanical strength and resistance to
loading. Indeed, the silk matrix displayed mechanical properties close
to those of the native ligament. The advantages of this technique come
from the high mechanical properties of the structures, the excellent
biocompatibility of the silk, once the sericin had been removed, and
from the very slow degradation pattern of the material which can
potentially enable a full ligamentization before the programmed
breakdown of the artificial structure. A recent study reported on the
combination of a bioceramic and a silk artificial ligament [LI 14b]. In
this approach, the silk ligament is inserted into a rapid prototyped
tricalcium phosphate scaffold whose function is to promote
osteoconduction and enhance bone to ligament contact. A pilot study
in pigs involving 2 animals displayed promising results in terms of
mechanical stability and tissue colonization 3 months post-surgery.
However, longer pre-clinical evaluation is required to fully establish
the efficacy and safety of this novel artificial ligament [LI 14b]
especially 12 to 24 months post-implantation to ensure that the
ligament does not experience excessive wear.
7.2.3.
Natural materials for ACL replacement
Natural tissues from animal origin have been utilized in the past
due to their excellent biocompatibility, rapid biointegration and high
collagenous content which has rendered them highly attractive. This is
the case for example for the Small Intestinal Submucosa better known
as SIS. This tissue was popularized by Babylak's group in the mid-
1990s and applied to some extent in ligament reconstruction. However
the limited mechanical properties of the decellularized tissue hinder its
implementation in full load-bearing application such as
ACL replacement. Nevertheless, it has been used as an augmentation
device for tendon regeneration [GIL 07] or rotator cuff ligament
reconstruction [DEJ 01] in dogs with some success. Another drawback
of the current decellularized SIS is the slow cellular infiltration once
implanted. Indeed, it has been demonstrated that the dense ECM
structure resulting from the decellularized process is not prone to rapid
tissue colonisation. The source of SIS, decellularization and
sterilization methods have also been demonstrated to impact
