96 / 242
F. Lavoie, K. Iguer, F. Al-Shakfa
96
the bicruciate-retaining implants and, as
acknowledged by the authors, in an
inappropriate fashion, probably resulting in
insufficient tibial resections and femoro-tibial
overstuffing. Considering this and the fact that
other series didn’t suggest decreased flexion
with bicruciate-retaining implants [4, 7-9], it is
reasonable to think that knee stiffness after a
bicruciate-retaining knee replacement may
result more from technical errors than from an
intrinsic design flaw.
ACL degeneration and
Long-term survival
Based on histological studies suggesting that
the ACL is often degraded in osteoarthritic
knees [10-12], concerns have been expressed
about the risk of preserving it during
arthroplasty as it may eventually rupture and
lead to knee instability and failure of the
implant. Reported survival rates for the
bicruciate-retaining variant of the LCS system
(DePuy Orthopedics, Warsaw, Indiana, USA)
,
however, do not substantiate such a fear: 90.9%
survival at twelve years for Buechel and Pappas
[7] and 79% survival at fourteen years for
Hamelynck
et al.
[13]; none of these two
studiesmentionsACLrupture or knee instability
as a cause of failure. A series of 163 bicruciate-
retaining knee replacements
(Hermes 2C,
Ceraver Osteal, Roissy, France)
in 130 patients
had a 95% survival rate at ten years [8] and
82% at 22.4 years [14], also not providing
evidence that a degenerated ACL may threaten
the survivorship of the knee implant. On the
contrary, the latter study didn’t show any
difference in survival, Knee Society scores,
and polyethylene wear between the knees in
which the ACL was visually deteriorated but
functional (41%) and the knees in which it was
visually intact (59%). In the same study,
symptomatic knee instability was noted in eight
knees (4.9% of the initial cohort, 27.6% of
revised knees) after a mean follow-up of 15.5
years (11.7 to 22.3) and was always associated
with severe wear of the tibial polyethylene
inserts, suggesting polyethylene wear to be the
primary cause of instability rather than ligament
rupture. Our hypothesis is that scarring occurs
in the intercondylar notch after bicruciate-
retaining TKA; the properties of this scar tissue
have not yet been studied but may be involved
in ACL protection and may be correlated to
post-operative range of motion. Regardless of
the mechanism, current evidence shows that
bicruciate-retaining knee arthroplasty is a
viable option in terms of survival, even when
the ACL is visually deteriorated.
A bone-preserving
surgery
Retention of the anterior cruciate ligament
during total knee arthroplasty involves
preserving the intercondylar eminence of the
tibia and requires no bone resection in the
intercondylar notch of the femur, making
bicruciate-retaining TKA a bone-preserving
procedure and, logically, making revision
surgery easier if it becomes indicated. This
theoretical advantage was confirmed by
Sabouret
et al.
who reported that no
intramedullary stems or metal augments were
necessary for 26 of the 29 bicruciate-retaining
TKAs (90%) that required revision in their
series [14]. Osteolysis was not a significant
problem in their series as it was noted in seven
revised knees but required stemmed components
in only one case. The bone-preserving nature of
bicruciate-retaining arthroplasty could make
this design a better option than PS and CR TKA
for younger and more active patients requiring a
knee replacement as multiple revision surgeries
can be expected for such patients. This
hypothesis remains to be verified, however.
Surgical technique
evolution
In a bicruciate-retaining arthroplasty, stability
and motion rely completely on the ligaments
and capsule of the knee, consistent with the
principle of minimal prosthetic constraint
articulated by Cloutier. Consequently, ligament
balancing is a critical aspect of this surgery.
Cloutier tackled this challenge by devising an
instrumentation that featured extra-articular