POSTER ABSTRACTS - ISAKOS

average age was 66 years old(55~74) and the
follow up period was 29 months(12~63 months).
Bone defects were found at proximal tibia in 10
cases, distal femur in 2 cases and both sites in 6
cases. PCL substituting TKA with extension rod
were 15 cases, and PCL retaining TKA were 3
cases. The clinical result was assessed with the
knee score of Hospital for Special Surgery(HSS)
and for assessment of allograft, simple X-ray film
was employed.
Results : Average range of motion was increased
from 71 to 103 and HSS score was increased from
46(18~68) to 83(68~91). With 17 of 18 femoral
head strut allograft, union was seen and no
clinical collapse was present. In one, partial
allograft absorption was occured. The
preoperative alignment was an average of 7
varus(range 5 ~15 ) and postoperative alignment
was averaged 6.1 valgus(range 3 ~7 ). No
radiolucent lines were 2 mm or more in width, and
there was no case of infection or fracture of
allograft.
Conclusions : Femoral head strut allograft was
satisfactory method of managing severe bone
defect in primary or revision TKA.
Key Words : Knee, Bone defect, Primary TKA,
Revision TKA, Femoral head allograft
E-poster #526
Functional Orthosis System Reduces the Peak
Impact Force Loading Rate or Patients with
Osteoarthritis During Partial Weightbearing
Gait
John Nyland, Louisville, KY, USA, Presenter
University of Louisville, Louisville, KY, USA
Introduction: Osteoarthritis represents the late
clinical expression of mechanical fatigue failure
due to deleterious impacts over a prolonged
period of time. Repetitious, uncontrolled
compression causes subchondral bone failure,
articular cartilage detachment, and reduced
proteoglycan synthesis particularly following
articular cartilage repair procedures. The purpose
of this study was to compare the peak plantar
force-time integral and center of peak plantar
force location during the loading response of
partial weight bearing gait on flat surfaces using
either axillary crutches or a functional orthosis
system (Easy Strutter, Orthotic Mobility Systems,
Kensington, MD). Our hypothesis was that the
Easy Strutter device would display a reduced peak
plantar force-time integral and more medial and
anterior peak plantar force locations. Methods:
Forty subjects with history of knee or hip
osteoarthritis were evaluated at > 1 year following
unilateral total knee or hip arthroplasty. The
operative lower extremity was instrumented with a
plantar force sensor (Pedar, Munich, GERMANY).
Subjects were instructed in 50% weight bearing at
the surgical lower extremity during assistive
device use. Subjects ambulated 15.2 m at a selfselected
pace as plantar force data were collected
(50 Hz). Subjects completed the course with each
assistive device with alternating device use order.
Mean peak plantar force-time integral and center
of peak plantar force locations were determined
from the initial 3 steps taken with each device.
One-way ANOVA were used to evaluate condition
differences (P < 0.05). Results: Peak plantar
forces were comparable between devices (Easy
Strutter = 380 ± 209 N, axillary crutches = 388 ±
211 N, P = 0.76). The Easy Strutter device
displayed reduced peak plantar force-time integral
(855.4 ± 480 N/sec vs. 992.3 ± 525 N/sec)
compared to axillary crutches (mean difference =
136.9 N/sec, P = 0.024). Medial-lateral peak
plantar force locations at initial foot-ground
contact (Easy Strutter = 53 ± 13 mm, axillary
crutches = 52.2 ± 12 mm, P = 0.60) and at the
instant of peak plantar force production (Easy
Strutter = 49 ± 7 mm, axillary crutches = 50.9 ± 7
mm, P = 0.06) did not differ. Anterior-posterior
peak plantar force locations displayed significant
differences at initial foot-ground contact (Easy
Strutter = 82.6 ± 68 mm, axillary crutches = 67.1 ±
62 mm, P = 0.04), however significant differences
were not evident at the instant of peak plantar
force production (Easy Strutter = 107.9 ± 45 mm,
axillary crutches = 100.8 ± 44 mm, P = 0.12).
Conclusions: The Easy Strutter Functional
Orthosis System displayed a substantially reduced
peak plantar force-time integral during partial
weight bearing gait on flat surfaces with a
concurrent anterior shift in peak plantar force
location at initial foot-ground contact. Reduced
and better controlled lower extremity joint impact
forces during gait may enable safer, early
progressive weight bearing following arthroscope
assisted surgical interventions for osteoarthritis.
E-poster #527
The Effect of Cruciate Integrity on Joint Motion
Following UniSpacer Arthroplasty
Philip C. Noble, Houston, Texas, USA, Presenter
Michael Conditt, Houston, Texas, USA
Matthew T Thompson, Houston, Texas, USA
Sabir K Ismaily, Houston, Texas, USA