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CURRENT STATUS
In spite of the generally satisfactory results
reported for the LARS in the above systematic
reviews, questions remain about its role.
Indeed, in many countries it has either not been
approved for use, is not available, or has fallen
from favor. One explanation for this apparent
contradiction is the potential for publication
bias, whereby poor outcomes are less likely to
be reported. This potential needs to be
acknowledged when interpreting the results of
systematic reviews. This was highlighted by
Waterman and Johnson in a response to the
Batty
et al.
review [11]. However, their
response also included the following statement
with regard to the LARS device; “Anyone who
has worked with this graft option is well aware
of its high failure rate in active cohorts.” Such
anecdotal experience is obviously not included
in a systematic review and can be quite at odds
with the findings of a review.
In a recent study, Tiefenboeck
et al.
came to a
conclusion in keeping with this sentiment [10].
They stated that the LARS device should “not
be suggested as a potential graft for the primary
reconstruction of the ACL”. Twenty-six
patients underwent primary isolated ACL
reconstruction with the LARS between 2000
and 2004. Final evaluation was completed in
18 at the mean age of 29, with a mean follow-
up period of 151 months. The high failure rate
was the authors’ principal source of concern.
Eleven patients had either KT-2000 side-to-
side difference in anterior knee laxity of more
than 5mm (4 patients) or a revision procedure
due to re-injury (5 patients) or revision due to
deep infection (2 patients). Feller
et al.
have
also reported a high (60%) failure rate of the
LARS device in professional footballers,
despite a 100% rate of return to sport [3].
Disabling synovitis has also been reported [4].
The LARS device has also been used as an
augmentation of hamstring autografts. Hamido
et al.
reported on its use as an augmentation for
small diameter or short grafts in 112 patients
with a mean age of 26 at the time of surgery [5].
The follow-up period was 45months. Relatively
little detail about post-operative assessment is
provided. However, on IKDC evaluation 67%
patients rated normal and 28.6% rated nearly
normal. Eighty-two percent of patients returned
to their pre-injury sports activities. No patient
had a graft rupture, synovitis, screw loosening
or bone-tunnel enlargement on radiological
examination. Annear
et al.
have also reported
high rates of an early return to sport with a
LARS/hamstring hybrid graft (n=16) compared
to a double-bundle hamstring graft (n=9), with
one graft rupture in each group, at 3 years and
18 months respectively [1].
CONCLUSION
Historically, the results of synthetic grafts for
ACL reconstruction have been poor due to high
failure rates, synovitis, tunnel widening and
screw loosening. Recent systematic reviews
suggest that the results of the LARS device
may be more encouraging, but the lack of high
quality studies is a recurrent theme in their
analyses. Selection bias is a particular problem
with included patients often being older.
Publication bias may mean that poor results are
less frequently reported. If synthetic ligaments
have a role in ACL reconstruction it may be as
a graft in older, lower demand patients who
require an early return of function, or as an
augmentation of autografts to allow an earlier
return to sport. However, the potential for
synovitis remains a concern. High quality
studies using modern and appropriate
assessment tools are still required to establish
the place of synthetic ligaments.