cadera / hip - Active Congress.......

MARTES / TUESDAY
80
CEMENTLESS THA IN
PATIENTS LESS THAN 50
– LONG TERM RESULTS.
C. H. Rorabeck, MD
Health Sciences Centre, Ontario, Canada
Providing a long-lasting total hip arthroplasty
(THA) for patients under 50 years of age
with hip arthritis remains one of the greatest
challenges for modern arthroplasty surgery.
Between 1983 and 2000, 221 patients less
than 50 years old underwent 299 uncemented
THAs at our institution. A minimum 5 and
maximum 15-year survival was assessed,
with revision as the end-point. Latest radiographs
were assessed for polyethylene
wear, component loosening and osteolysis.
Femoral stem survival was 99.3 (98.4-100)
%, 98.9(97.7-100) % and 96.8(92.5-100)
% at 5, 10 and 15 years for all designs.
Including all acetabular component designs
survival was 98.7(97.4-100) %, 84.6(78.8-
90.4) % and 52.5(40.7-64.3) % at 5, 10
and 15 years. Excluding polyethylene liner
exchange, acetabular survivorship increased
to 98.9(97.8-100) % (5 yr), 90.6(85.7-95.5) %
(10yr), and 65.3(52.8-77.8) % (15yr). THAs
performed for hip dysplasia had lower 10 and
15-year survival (p=0.009; p=0.006). 69 revisions
have been performed, the commonest
indication being polyethylene wear (n=33).
Zirconium on polyethylene articulations had
signifi cantly lower acetabular revision rates
compared with cobalt-chrome on polyethylene
(p=0.02). Uncemented femoral stems
provided over 90% survivorship at a minimum
15-year follow-up in patients younger than 50
at their index operation. Contemporary bearing
surfaces in association with such stems
may provide long lasting THAs even in young
active patients.
CLINICAL RESULTS AND
HISTOLOGICAL FINDINGS OF
A LOW MODULUS
COMPOSITE STEM
V. M. Goldberg, M.D.
Department of Orthopaedics
Case Western Reserve University
University Hospitals of Cleveland
Cleveland, Ohio, USA
Introduction: Osteolysis secondary to stress
shielding has been attributed to high femoral
stem stiffness in total hip arthroplasty (THA).
The EPOCH (Zimmer, Warsaw, IN) stem has
reduced stiffness due to a smaller cobalt alloy
core, surrounded by polyaryletherketone
and titanium mesh for bony ingrowth. Our
fi ndings from a prospective clinical trial of
this implant, including histological analysis
of retried implants from autopsy.
Materials and methods: Twenty-eight (19
males, 9 females, average age 51.3 years,
range 23-67) with primary or secondary osteoarthritis
underwent a primary THA using
the EPOCH stem and were followed by an
average of 10.2 years. Harris Hip Scores
were obtained preoperatively and at 2 year
intervals post-operatively. Two femurs were
obtained at autopsy 13 and 48 months after
surgery. The femurs were sectioned proximally-distally
and evaluated histologically by
quadrants: anteromedial (AM); anterolateral
(AL); posteromedial (PM); posterolateral (PL).
They were graded by two observers for bone
ingrowth into the mesh (0-2), ongrowth onto
the mesh (0-4), and extent of bone fi ll (new
and old) around the implant (0-3).
Results: Preoperative hip scores averaged
55.5 (range 33-78) and improved to
97.2 (range 78-100) at last follow-up, with 2
patients having scores below 90 (thigh pain
was present in one of these patients). For