DOS Kongressen 2014 ·
61
Promising migration Pattern at 1 year follow-up of the
short Primoris Femoral Stem
Mogens Berg Laursen, Janus Duus Christiansen, Gordon Blunn, Poul Torben
Nielsen
Northern Ortopaedic Division, Aalborg University Hospital; University College
London, RNOHT, Stanmore, United Kingdom
Background:
In order to save proximal bone stock in primary total hip arthro-
plasty (THA), short femoral stems are introduced.
Purpose / Aim of Study:
Designed for perfect fit within the femoral neck, the
Primoris® femoral stem has been released for clinical studies in coherence with
the stepwise introduction of new implants. This is the preliminary report of the
Radio Stereometric Analysis (RSA) results after 1 year follow-up (FU).
Materials and Methods:
We carried out a prospective cohort study of 52 pa-
tients scheduled for surgery with the femoral neck-preserving Primoris® stem.
Migration was analyzed by RSA, and the Harris hip score, UCLA activity score,
WOMAC, EQ5D health questionnaire and Oxford Hip scores were recorded.
Findings / Results:
2 patients were excluded intra-operatively and 1 patient
was revised due to aseptic loosening after 3 months, leaving 47 patients for
analysis. Further 2 patients were excluded from the RSA analysis due to techni-
cal problems. RSA showed minor micromotion of the stem: Mean subsidence
was 0.35 mm (precision: 0.10 ) and mean rotation around the longitudinal axis
was 0.10º (precision: 0.64) after 1 year.
Conclusions:
The stems showed very small migration—as it is characteristic
for stable uncemented implants. If they stay stable until the 2 year FU, we will
go on with a multi center study.
8.
