POSTER ABSTRACTS - ISAKOS

graft that could potentially compromise the
mechanical integrity of the reconstruction.
Methods: The first arm of the study utilized two
cadaveric ACL reconstructions with the Rigidfix
system (DePuy Mitek, Norwood, MA) to evaluate
the direct effect of cross pin fixation on the gross
structure of a standard four bundle
semitendinosus and gracilis hamstring graft. The
second arm of the study involved cross pin
fixation of double-looped tibialis anterior or fourbundle
hamstring grafts ex vivo. The specimens
were sectioned for histological evaluation and the
collagen fibers were inspected to assess whether
cross pin passage had caused compression or
disruption of the fibers. The effect exerted upon
the collagen fibers by the cross pins was
compared to that of suture that had been passed
through the grafts during preparation.
Results: The cadaveric knees demonstrated
compression of the graft against the femoral
tunnel walls during pin transfixion and no tearing,
fraying, or damage to the tendons following cross
pin fixation was detected. Histologic analysis
demonstrated that cross pin passage resulted in
near total collagen fiber compression in 2/4
hamstring grafts, compression with minor
collagen tearing in 1/4 hamstring grafts and 4/4
tibialis anterior grafts, and possible predominant
tearing in 1/4 hamstring grafts. Suture placement
resulted in minor collagen fiber tearing in 1/3
hamstring grafts and 5/8 tibialis anterior grafts
and predominant collagen tearing in 2/3
hamstring grafts and 3/8 tibialis anterior grafts.
Conclusion: Transfixion of a soft tissue graft with
cross pins results in graft compression within the
femoral tunnel and results in minimal collagen
fiber disruption that is proportionately less than
that seen with suture passage. These results
provide reassurance to the surgeon that cross pin
fixation allows for secure graft fixation without
jeopardizing the structural integrity of the graft.
E-poster #348
Successful ACL Reconstruction with
Regenerated Semitendinosus and Gracilis
Tendon Grafts. Report of Two Cases.
Manuel Leyes, Madrid, SPAIN, Presenter
Raul Torres, Madrid, SPAIN
Pedro Guillen, Madrid, SPAIN
Clinica Cemtro, Madrid, SPAIN
INTRODUCTION
In recent clinical, morphologic and MRI studies a
regeneration potential of the semitendinosus and
gracilis tendons has been observed. The aim of
this study was to report two cases of successful
ACL reconstruction with regenerated ST and
gracilis tendons. To our knowledge there are no
studies in the literature where these tendons have
been harvested a second time and used for a new
ACL reconstruction.
MATERIAL AND METHODS
This study included two males, ages 38 and 30,
who had undergone a previous ACL
reconstruction (9 and 6 years earlier) with a ST
and gracillis tendon graft. Full length and
thickness harvesting of the tendon grafts had been
performed using a tendon stripper. Both patients
ruptured their ACL graft in a sport injury. Prior to
their second reconstructive procedure, they were
examined by MRI and found to have regenerated
ST and gracilis tendons. Both tendons were
reharvested and the findings were documented
macroscopically and morphologically through
tendon biopsies. The reharvested tendons were
used to reconstruct the ACL preserving their distal
tibial insertion and fixing them proximally with
staples.
RESULTS
Macroscopically the regenerated tendons had a
nearly normal appearance. Both tendons had
regenerated to their full thickness and length (the
diameter of the tunnels was the same in the first
and second ACL reconstructions)
The histological evaluation showed normal
tendon with some areas of irregularly arranged
collagen bundles, increased fibroblastic
proliferation and capillary formation
After a follow-up of 14 and 17 months, both
patients have returned to their previous level of
activity and their knees are stable (side to side
difference less than 3 mm)
CONCLUSION
Harvesting of the ST and gracilis tendon results in
full length tendon regeneration. Although the
mechanical properties of this regenerated tissue
are still unknown, clinically it seems appropriate
for a second time ACL reconstruction.
E-poster #349
Anterior Cruciate Ligament Reconstruction: A
Study of the Effect of Radiological Image
Guidance on Tunnel Placement
Gareth Stables, Lymm, UNITED KINGDOM,
Presenter
Yiannis Pengas
Michael J McNicholas, Cheshire, UNITED KINGDOM