41.
The Oxford® Partial Knee Femoral Components: Are 2 pegs better
than 1?
Maiken Stilling, Frank Madsen, Claus Fink Jepsen, Kjeld Søballe, Per Wagner
Kristensen, Anders Odgaard
Department of Orthopaedics Aarhus University Hospital; Department of
Orthopaedics, Aarhus University Hospital; Department of Orthopaedics,
Aarhus University Hospital; Department of Orthopaedics, Aarhus University
Hospital; Department of Orthopaedics, Vejle Regional Hospital; Department
of Orthopaedics, Aarhus University Hospital
Background:
Traditionally, the femoral component (FC) of the Oxford®
Partial Knee Replacement had a single-peg (SP). Recently, a double-pegged
(
DP) FC has been developed to better resist rotational torques.
Purpose / Aim of Study:
to compare fixation of SP and DP cemented
Oxford® Partial Knee FC, and further, to compare fixation of cemented and
cementless DP FC up to 1 years.
Materials and Methods:
79
patients (48 men) randomly were allocated to
surgery with cementless hydroxylapatite-coated or cemented Oxford® Partial
Knee (Biomet Inc) at two hospitals. Refobacin bone cement (Biomet Inc) was
used. There were 3 groups: A) SP cemented FC, B) DP cemented FC, and C)
DP cementless FC. Evaluation of implant migration, radiolucent lines (RLL),
and clinical outcomes (AKSS and OKS) was performed at 6 weeks, 3 months,
6
months and 1 year.
Findings / Results:
At 1 year maximum total point motion (MTPM) for A
(0.41
mm, SD 0.35) and B (0.40mm, SD 0.20) was similar (p=0.59). The
MTPM for C (0.53mm, SD 0.18) was higher than for A (p<0.01) and B
(
p=0.02). Fixation was similar between the 3 FCs until 6 months. Between 6
months and 1 year posterior rotation (0.37°, SD 0.40) and internal rotation
(0.27
°, SD 0.32) for C was larger (p=0.01) compared with A and B. Between 6
months and 1 year 12% (3/25) of A, 25% (6/26) of B, and 17% (4/24) of C
migrated more than 0.2mm (MTPM), but there was no statistical difference
between the groups (p>0.24). Analysis of RLL is ongoing. At 1 year the
clinical results was similar between groups (p>0.17). Satisfaction was high.
Conclusions:
Double-pegs does not improve fixation of cemented Oxford®
Partial Knee femoral components as compared with a single-peg. Cementless
fixation with double-pegs is stable until 6 months, but after 6 months these
components rotate internally and posteriorly as compared with cemented
fixation. Longer follow-up is needed.
