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IS THERE A PLACE FOR A SYNTHETIC LIGAMENT?
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reported on ACL reconstruction with the
Trevira-Hochfest device. One of these studies
also reported on two other PET devices, the
Proflex and Pro-Pivot. All studies were
prospective cases series and included a total of
265 reconstructions. Only one of the three
studies used multiple outcome measurements.
The mean follow-up time ranged from 40 to
225 months. Overall, the failure rate was 9.4%
(25 failures from 265 reconstructions).
As mentioned previously, more recent designs
of synthetic ligament devices include the
LARS and LK II. Fourteen studies in the Batty
et al
. systematic review reported outcomes for
these designs LARS (n=13) and the LK II
(n=1). The 14 included studies reported an
overall low failure rate of 2.6%, over a follow-
up period that ranged from 22 to 95 months.
However, the single report on the LK II device
had the shortest mean follow up time and
meaningful interpretation of the results is
difficult as only 13 patients were included.
On the basis of the systematic review, the results
of the LARS device appear encouraging, with
[19] documented failures in 736 patients (2.6%).
In those studies that reported Lysholm scores,
the mean post-operative score was 88,
compared to a mean pre-operative score of 54.
KT-1000 arthrometer side-to-side difference
was measured in 7 studies in 394 knees with a
mean side-to-side difference of 2.2mm (range,
1.2 to 4.2mm). Pivot-shift was recorded for
497 patients in 4 studies with a grade 2 pivot
(clear shift and visible reduction) present in
6.4%. The overall reported incidence of synovitis
was 0.2% (one reported case from 483 knees).
In terms of comparative studies, the 1 RCT
compared 26 LARS devices with 27 patellar
tendon autografts. At 24 months there was no
significant difference between the groups in
terms of IKDC or KOOS scores. One
retrospective study compared 30 patellar
tendonautograftswith32LARS reconstructions
with a minimum follow-up of 4 years. There
were no differences between the groups in
terms of Lysholm, Tegner, IKDC, and KT-1000
assessments. In a second retrospective study,
32 four-strand hamstring ACL reconstructions
were compared with 28 LARS ACL
reconstructions, also with a minimum follow-
up of 4 years. Again, there was no difference in
Lysholm, IKDC, or Tegner scores, but the
LARS group had significantly less anterior
displacement as measured by KT-1000.
However, it should also be noted that in the
Batty
et al.
systematic review, the MINORS
score was used to assess the methodologic
quality of included studies. The ideal score was
16 points for non-comparative studies and case
series and 24 points for comparative studies.
The mean MINORS score for the non-
comparative LARS studies was only 7.6 points
(SD, 1.2 points) and 17.3 points (SD, 1.5 points)
for the comparative studies.
Given such low levels of evidence, the findings
of the systematic review should therefore be
interpreted with caution. For example, although
the overall rate of synovitis and effusion for the
LARS device was lower than reported for
earlier synthetic devices, half of the included
studies made no mention of these outcomes.
Closer analysis of individual papers can also be
revealing. Parchi
et al.
reported on 26 of
29 patients at mean follow-up of 7.9 years [9].
The mean age of the patients at the time of
follow-up was 38.5 years. Joint stability and
range of motion were reported to be satisfactory
in 24 patients. For the KOOS score, 11 patients
(42.3%) rated optimal (
＞
90) and 13 (50%)
good (70-89). However, there was a wide range
of scores, from 10 to 100. Similar findings were
found for the Cincinnati knee rating scale with
92.3% rating optimal (61.5%) or good (30.8%).
Again, there was a wide range was from 22 to
100. Although the authors’ message was that
the LARS device might be “a suitable option
for ACL reconstruction in carefully selected
cases”, the following points should be noted;
there was no control group, the patients were
relatively older compared to the usual group
reported in follow-up of ACL reconstruction,
included patients elected to have a LARS
procedure (potential for selection bias), despite
generally satisfactory outcomes some patients
did badly, and no data was provided regarding
return to pre-injury activities.