POSTER ABSTRACTS - ISAKOS

E-poster #560
New Method of Intra-operative Registration for
Computer-assisted Total Knee Arthroplasty
Ten Sobue, Niigata City, Niigata JAPAN, Presenter
Yoshio Koga, Niigata City, JAPAN
Takashi Sato, Niigata City, Niigata JAPAN
Go Omori, Niigata City, JAPAN
Daisuke Miyakoshi, Niigata city, JAPAN
Niigata kobari hospital, Niigata city, JAPAN
INTRODUCTION:
We have developed the three-dimensional lower
extremity alignment assessment system
(3DLEAAs) to evaluate the alignment of entire
lower extremity in standing position, by
superimposing 3-D CT model to biplanar x-ray
images. Pre-operative planning of total knee
arthoplasty (TKA) can be performed by fitting 3-D
component model to the x-ray images, and intraoperative
registration can be controlled by
applying image-scan technique. In this
presentation, we give a preliminary report of the
new method for registration as well as bone
cutting of femur during computer-assisted TKA.
MATERIALS AND METHODS:
Pre-operative planning - Simultaneous biplanar
long-leg x-rays (AP and 60-degree oblique) were
taken in standing position. Long leg CT was also
taken and 3-D bone model was constructed and fit
to x-ray images. 3-D component model was
superimposed to CT bone model and was moved
to suitable position at surgeon’s preference. The
red marker was placed to roof of intercondylar
space of femur. Then, the positions of distal
femoral cutting level and two pegs for femoral
component were determined and saved to
personal computer.
Intra-operative registration - Red marker was
placed to roof of intercoindylar space. By imagescan
technique, three images of distal femur
(coronal, sagittal, and axial) with marker were
taken and downloaded to personal computer
immediately. 3-D CT bone model with preoperative
planning was superimposed and moved
to fit the position of red marker in each computer
image. Throughout these procedures, the
positions of distal femoral cutting level and pegs,
which were determined preoperatively, were
indicated in the surgical field.
RESULTS AND DISCUSSION:
There are several methods for the registration of
pre-operative planning in the surgical field. We
have used fluoroscopy to take biplanar images
during surgery. The new method we described has
several advantages: the positions of cutting level
and pegs can be indicated directly under
visualization of surgeon’s eyes: simple procedure:
no irradiation needed during surgery. We will
evaluate the efficacy of this method by error
analysis, comparing with the old method.
KNEE - LIGAMENT/PATELLA
E-poster #600
Evaluation of Patella Alta Prevalence and
Causes Related to it on Taleghani Hospital
Kamran Badizadeh, Tehran, IRAN
Soheil Mehdipoor, Tehran, IRAN, Presenter
Taleghani Hospital, Tehran, IRAN
Patella alta is brought up as one of the most
common causes of anterior knee pain that yet it
has not been studued in our country (IRAN). Due
to this reason, for 2 years, since 1997, study was
done on 400 patients based on patella lta
prevalance and its risk factors and approximately
50 quantitative variables were analyzed. The
research method was descriptive and its
technique was interview and observation and
inspection of patient with information forms. The
acquired information was analyzed by computer.
In this study the general prevalance of patella alta
in patella alta in patients with anterior knee pain
was 27.6% also the insall index in our mentioned
population was 1.09 which is near 10 % more than
the average of this index in population of western
countries. Osgood Schlatter, generalized joint
laxity and patella dx and subluxation Wiberg Type
3, Hypermobile Patella and some other conditions
had meaningful (statistical) higher incidence with
patella alta in our study. On the result of this
study we introduce a test which we named it
“Inferior Pole Compression Test” that sets forths
for as a suggestions of patella alta diagnosis,
which consists of feeling pain, while there is
pressure on inferior pole of patella in knee in full
extension. Also there was not any meaningful
correlation between Iranian life style (toilet
manner, less exercise, kind of sitting manner..)and
the incidence of patella lata. The accomplishment
research of great inforamtion about recognition
and diagnosis of patellat malalignment in anterior
knee pain and it could be used as a good
guidance for orthopaedists in order to think about
patella alta as a reason for anterior knee pains
and use suitable radiological methods.