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the ACL remnant may have a positive effect
on the proprioceptive ability of the knee;
• The ACL remnant may contribute to
anteroposterior knee stability and guarantee
mechanical strength in the early postoperative
period.
Potential advantages of ACL augmentation are
attractive in terms of early biological healing of
the grafted tendon. In 1992, Ochi started
performing ACL augmentation, when indica
ted, without sacrificing the ACL remnant by
using an autogenous semitendinosus tendon
under arthroscopy. In 2000, Adachi and Ochi
et
al.
[5] reported that the knee stability and
proprioceptive function of 40 patients who
underwent ACL augmentation were superior to
those of 40 patients who underwent standard
single-bundle ACL reconstruction during the
same period. However, the surgical procedure
of ACL augmentation at this period required
two incisions because the graft was passed
through the over-the-top route on the femoral
side. Therefore, in 1996 Ochi started
performing ACL augmentation using the one-
incision technique with EndoButton-CL [6, 7].
INDICATIONS FOR ACL
AUGMENTATION
It is sometimes difficult to decide whether the
remaining bundle of the ACL represents a
partial rupture or a complete rupture. The
decision is made after thorough consideration
of clinical tests, laxity measurements, MRI,
and arthroscopic findings [1, 4, 7]. Quantitative
evaluation of anteroposterior knee joint laxity
can aid in this decision. We consider patients as
candidates for ACL augmentation when the
side-to-side difference in the anterior dis
placement of the tibia is less than 5mm. MRI
also provides important information to evaluate
the condition of the ACL bundles. However,
the final decision should be made after
arthroscopic confirmation of the status of the
injured ACL.
Partial rupture of the ACL is an ideal indication
for ACL augmentation. However, in our
previous studies, the frequency of partial ACL
tear was only 10% during the study period
between 2002 and 2005 [6], and 20% between
2006 and 2008 [4]. In 2008, we began
performing ACL augmentation even for
patients with continuity of the ACL remnant
between the tibia and the femur after complete
ACL rupture. In this complete rupture group,
indication for the procedure comprises cases
whose ACL remnant maintains a ligamentous
bridge between the intercondylar notch and the
tibia, and whose proximal ACL remnant
diameter is greater than one-third of the original
size. Anatomic central single-bundle or double-
bundle [8] ACL reconstruction with the
remnant preserving technique is performed for
patients in the complete rupture group. Since
2006, ACL augmentation has attracted much
attention in the field of ACL reconstruction.
Several ACL augmentation techniques have
been described, including selective AM or PL
bundle reconstruction [7, 9], the remnant
retensioning technique, anatomic single- or
double-bundleACL augmentation for complete
rupture, and preservation of the ACL tibial
remnant.
SURGICAL TECHNIQUE
In this section, a brief description of the
surgical techniques of single-bundle ACL
augmentation is provided. A quadrupled
semitendinosus tendon or four-strand semi
tendinosus and gracilis tendon is desirable as
the graft for the augmentation. The antero
lateral, anteromedial and the far-anteromedial
portals are used for the surgery.
Femoral bone tunnel
For femoral bone tunnel preparation, the far-
anteromedial portal technique is used because
this technique allows more flexibility in
accurate anatomical positioning for femoral
tunnel drilling than the transtibial technique. A
delicate debridement and bone tunnel
placement is important to preserve the ACL