POSTER ABSTRACTS - ISAKOS

E-poster #335
Simplified MRI Sequences for Postoperative
Control of Hamstring ACL-reconstruction
Jens Agneskirchner, Hannover, GERMANY,
Presenter
Mellany Galla, Hannover, GERMANY
Peter Landwehr, Hannover, GERMANY
Philipp Lobenhoffer, Hannover, GERMANY
Department of Surgery Henriettenstiftung
Hannover, Hannover, GERMANY
Background: Usually standard radiographs are
used for postoperative quality control after ACLreconstruction.
However with the use of hamstring
grafts and bioabsorbable implants accurate
assessment of the tunnel- and implant-position is
impossible. The graft and its relation to
anatomical landmarks cannot be evaluated
directly. MRI is an alternative to radiography
permitting direct graft visualization and 3-
dimensional assessment of tunnel position.
However for routine use it is expensive and time
consuming. The aim of this study was to develop a
simplified MRI protocol with less time
consumption and to evaluate it for routine
postoperative quality control after ACL
reconstruction.
Materials and Methods: Various scanning
protocols were tested in a series of 105 patients
and evaluated for image sharpness, clarity of the
structures, susceptibility to artefacts, applicability
regarding precise analysis of graft and tunnel
position and time consumption. One simplified
specific scan protocol was then defined and
applied in a series of 60 consecutive patients after
hamstring ACL-replacement. The position of the
femoral and tibial tunnels was measured in the
sagittal, coronal and axial sections and classified
according to Harner (femoral) and Staeubli
(tibial). Impingement of the graft in the
intercondylar roof was analysed according to
Howell. The position of the bioabsorbable
interference screws was assessed.
Results: Scan protocol: T2 weighted gradient echo
sequences (GRE) with TR=246ms, TE 11ms, flip
angle 25 , 2mm sections and a 256*256 matrix
yielded the best image quality of tendon grafts
and bone tunnels with tolerable time
consumption (average scanning time per patient 1
min 40 sec). Altogether 8-16 sections were obtained
in every patient. Tunnel placement: 46/60
(77%) of the femoral tunnels were in zone 4, 13/60
(21%) at the border zone 3 to zone 4, 1/60 (2%) in
zone 3 in the sagittal plane (Harner). The femoral
tunnels in the axial plane were at 10:30 o’clock in
32/60 (53%), at 11:00 o’clock at 24/60 (40%) and at
10:00 o’clock in 4/60 (4%) pa-tients. The mean
distance of the anterior border of the tibial tunnel
from the anterior cortex was 39% (+/- 4,9%) related
to the total sagittal diameter of the tibia. There
was no graft impingement. The position of the
interference screws was anterior to the grafts in all
cases.
Conclusion: Simplified MRI sequences can be
used for postoperative quality control after ACLreplacement
and are an alternative to standard
radiographs giving more specific and precise
information regarding tunnel position and screw
placement. Analyzing the bone tunnels in a series
of 60 patients demonstrated that correct
assessment of tunnel placement after
arthroscopic ACL-reconstruction is feasible using
this simplified MRI technique.
E-poster #336
The Use of Allograft Bone Screws and Aperture
Fixation in Allograft Bone Patellar Bone ACL
Reconstructions
Stephen Houseworth, USA, Presenter
Audubon Surgery Center, Colorado Springs, CO,
USA
Hypothesis: Is the Use of allograft bone screws
conbined with aperture fixation an effective
means of fixation of allograft bone tendon bone
grafts for ACL reconstruction surgery and does
this method prevent tunnel widening?
Methods: This is a retrospective review of 30
consecutive patients undergoing intra-articular
allograft patellar bone tendon bone ACL
reconstructions. Each patient had sustained and
ACL tear between 6 weeks and 14 years prior to
the procedure and had symptomatic ACL
insufficiency. All patients had undergone a preoperative
MRI which documented the torn or
absent ACL. Each patient had been counselled
extensively about options of ACL reconstruction
graft choices and had agreed to the use of
allograft tissue. All patients were informed about
the need for their need to follow a carefully
supervised post-operative physical therapy
program. X-rays were obtained during the postoperative
course to follow for possible tunnel
widening.
Results: A total of 30 patients (16 male, 14
female, average age 43 years) underwent this
procedure. An allograft bone screw was used for
''interference fit'' fixation at the anterior aspect of