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cases. Despite initial promising results, longer-
term follow-up showed high failure rates,
osteolysis, synovitis and high rates of
osteoarthritis and the device was subsequently
withdrawn from the market.
The Goretex device made from expanded
polytetrafluoroethylene (PTFE) was used
between the mid 1980s and mid 1990s.
Intended as a permanent implant, an important
property was its ultimate tensile strength of
approximately 5300N, higher than any
counterparts. However, once again initial
promising results were overtaken by poor
outcomes in the mid-term, with ligament
failure and effusion being the predominant
adverse findings. Importantly, poor positioning
of the graft was recognized as a factor
contributing to the risk of graft abrasion and
failure. The device was eventually withdrawn
from the market.
In the early 1980s Kennedy proposed the use
of a polypropylene braid as a Ligament
Augmentation Device (LAD) to protect patellar
tendon grafts in the early post-operative period.
It was sutured to the autograft to form a
composite graft. It was supposed that the LAD
could protect the autograft during its
remodelling and it was assumed that potential
stress shielding of theautograft would be
minimized by the relatively low tensile strength
of the LAD and the fact that only one end of
device was fixed. Studies failed to show any
advantage over autografts alone and failures
with intra-articular debris and effusions were
reported. As a result, usage of the Kennedy
LAD ceased.
MODERN DEVICES
A second generation Leeds Keio (LKII) device
was made available in 2003 with the addition
of radio-frequency generated glow discharge
treatment. A number of polyethylene
terephthalate (PET) devices have also been
developed and include the Trevira-Hochfest,
Proflex, Pro-Pivot and Ligament Advanced
Reinforcement System (LARS) devices. Of
these, the LARS device has been most widely
used and reported. The results are discussed
below in more detail.
SYSTEMATIC REVIEWS
There have been three recent systematic
reviews of the results of synthetic ligaments for
cruciate ligament injury.
Mulford
et al.
evaluated the efficacy of PET
artificial ligaments in the ACL reconstruction
[7]. A total of 23 papers published between
1970 and 2010 were included. Twelve papers
were related to the LARS and the remaining 11
focused on the long-term outcomes of other
PET ligaments. In studies of the LARS, the
mean follow-up period was 28 months (range
4-60 months. In 655 cases the documented
graft rupture rate was 2% (14 cases). The
authors did however note the poor methodo
logical quality of the included studies.
In their 2013 systematic review that included
many of the papers included in the review by
Mulford
et al.
, Newman
et al.
evaluated studies
of the LARS device for ACL reconstruction
[8]. There were nine papers, including one
randomized control trial, and all were published
between 1990 and 2010. Not surprisingly, there
was a similar failure rate of 2.5%. Most failures
were attributed to tunnel malposition. Again,
only one case of synovitis was reported. Return
to sports took two to six months, earlier than
that for patients having an autograft procedure.
However, the poor methodological quality of
the papers and the need for high quality longer-
term studies was once again highlighted.
More recently, Batty
et al.
systematically
reviewed the literature related to the clinical
application of artificial ligaments in cruciate
ligament surgery [2]. With regard to the ACL,
the highest failure rate was observed with the
Dacron device with a cumulative failure rate of
33.6%. Non-infective synovitis and effusion
were most frequently seen with the Gore-Tex
artificial ligament (up to 27.6%).
With regard to more recent synthetic devices,
three studies published between 1994 and 2010