POSTER ABSTRACTS - ISAKOS

•E-poster w/ Standard #428
Femoral Fixation of Patellar Tendon Graft in
ACL Reconstruction. A Mechanical Analysis
Giuseppe Milano, Sassari, ITALY, Presenter
Pier Damiano Mulas, Sassari, ITALY
Donatella Zarelli, Sassari, ITALY
Stefano Piras, Sassari, ITALY
Laura Deriu, Sassari, ITALY
Angelino Sanna, Sassari, ITALY
Fabio Ziranu Sassari, ITALY
Carlo Fabbriciani, Rome, ITALY
Department of Orthopaedics - University of
Sassari, Sassari, ITALY
Purpose of the study: To evaluate the mechanical
properties of femur-PT graft- complex in ACL
reconstruction using different femoral fixation
devices. Type of the study: Mechanical ex-vivo
study. Material and Methods: An ACL
reconstruction was performed on 40 cadaver
porcine knees, using PT graft. Femoral fixation was
achieved using four different fixation mechanisms
interference fixation (absorbable screw), lateral
compression (Setscrew), suspension (Rigidfix),
and a combination of compression and
suspension (CrossPress). Other 10 knees were
used as controls. On each sample, after femoral
graft fixation, tibia was removed and the femur-PT
graft complex underwent a mechanical evaluation
consisting of a cyclic loading test (loading range:
10-150 N, strain rate: 200 mm/min), then a loadto-failure
test (strain rate: 200 mm/min).
Elongation after 1000 loading cycles, maximum
load, yield load, stiffness, deformation at the yield
point, and mode of failure were recorded. Kruskal-
Wallis test was used to compare the differences
between groups for each variable. A post hoc
analysis with Tukey test was also carried out for all
possible pairwise comparisons. Alpha level was
assumed .05. Results: Cyclic loading test series
showed lowest mean elongation for Setscrew (1.7
mm) and CrossPress (1.2 mm). Load-to-failure
test series showed no significant differences in
maximum load between CrossPress (1021.8 N)
and normal ACL (1091.2 N). All other groups
showed significantly lower mean maximum load,
without differences between them. For mean
stiffness, only absorbable screw (104.3 N/mm) was
significantly lower than normal ACL (162.5
N/mm). Mode of failure was graft pullout for
absorbable screw and Setscrew fixation, distal pin
breakage for Rigidfix fixation, and midsubstance
graft rupture for most of CrossPress fixation
samples. Conclusions: Compression screw
fixation (Setscrew and CrossPress) minimized PT
graft elongation under cyclic loading. CrossPress
fixation only showed maximum load not
significantly different respect to normal ACL.
Furthermore, it reduced the risk of graft pullout or
hardware breakdown in comparison with other
fixation devices. Significance: Combination of
compression and suspension fixation
mechanisms of PT graft gives structural properties
of femur-graft complex similar to those of normal
ACL.
E-poster w/ Standard #429
Knee Proprioception Gender Differences in
Collegiate Soccer
Henry Thomas Goitz, Toledo, OH, USA, Presenter
Lynsey Ebel, Toledo, Ohio USA
Rebecca Lynn Mocniak, Toledo, Ohio USA
Jeffrey B Noftz, Bowling Green, OH USA
Medical College of Ohio, University of Toledo,
Toledo, OH, USA
INTRODUCTION: Women are more likely to injure
their ACL than men. While a multitude of factors
have been suggested, isolated proprioception
differences have not been specifically studied,
particularly in a functional or standing position.
We evaluated collegiate female soccer players and
compared them to their male counterparts in a
functional manner not previously described in
athletes.
METHODS: Thirty-three male and thirty-three
female collegiate soccer players were included in
this study. Data regarding each athlete's
proprioception skills via reproducible knee flexion
angles from a standing position were collected.
These angle deviations were measured with an
electronic goniometer with digital readout and
accuracy to within one degree (Biometrics
Electrogoniometer, Model ADU301). The
electrogoniometer was secured to the subjects'
dominant leg. The subject was then verbally
instructed to squat/flex to a specific angle for a
designated period of time and subsequently
replicated the angle previously positioned.
Deviations between the set angles and the
reproduced angles were recorded and used to
evaluate the athlete's proprioceptive skills in a
standing closed chain position. The protocol was
carried out for a flexion range between 10 and 75
at 5 intervals, where set angles were randomly
chosen.
RESULTS: The average deviation between set and
reproduced angles were calculated for both male