Abstractband 17 - DVSE

Poster, Jahreskongress DVSE 2010 – Rosenheim 7. – 8. Mai 2010
P2
Fixation of a Novel Minimally-Cemented, Posteriorly-Augmented
Glenoid Prosthesis
P.H. FLURIN, C. ROCHE; T. WRIGHT, S. GREY, J. STEFFENS, J. ZUCKERMAN –
MERIGNAC
Fragestellung
Glenoid loosening is a common failure mode of total shoulder arthroplasty, particularly in patients with conditions
that could result in compromised initial fi xation. To this end, a novel minimally-cemented glenoid prosthesis
was developed to improve fi xation for patients with posteriorly worn glenoids. This prosthesis is composed
of a 4mm UHMWPE articular bearing surface modularly connected to a grit-blasted Ti-6Al-4V central
bone cage and 3 grit-blasted Ti-6Al-4V peripheral pegs. Initial fi xation is achieved via press-fi t of the Ti-6Al-4V
pegs and PMMA cement on the backside surface of the glenoid. The prosthesis has 8° of posterior build-up to
preserve bone by limiting the amount of eccentric glenoid reaming necessary to correct the patient’s glenoid
version. The fi xation of the proposed device was compared to that of the “gold standard” UHMWPE cemented
glenoid to demonstrate clinical effi cacy.
Methodik
An edge displacement test was conducted according to ASTM F 2028 on a quantity of 6 of the XL posterior
augment cage glenoids; a quantity of 6 of the XL UHMWPE cemented pegged glenoid were used as controls.
Each was implanted in a 30 lb/ft3 polyurethane bone substitute block (Pacifi c Research Laboratories; Vashon,
WA) according to the surgical technique. Each device had a similar radial mismatch when articulated with the
53mm humeral head. The susceptibility to loosening was established by comparing the maximum glenoid
edge displacement before and after cyclic loading (100,000 cycles at 2 Hz) of a 750 N compressive load applied
by a 53 mm humeral head as it was translated along both the superior/inferior and anterior/posterior glenoid
axes. Each glenoid was cyclically loaded in a water-enclosed chamber heated to 37° C. The magnitude of edge
displacement was quantifi ed before and after cyclic loading with an LVDT.
Ergebnisse
The results of this study demonstrate that regardless of the axes tested, no discernable difference in edge displacement
(distraction or compression) occurred before or after cyclic, eccentric loading for either glenoid
design; no difference in compression or distraction was observed between either glenoid design. Additionally,
each glenoid component tested remained fi rmly fi xed after testing; no incidence of dissociation occurred.
Schlussfolgerung
The proposed minimally-cemented, posteriorly-augmented glenoid prosthesis and the traditional “gold standard”
UHMWPE pegged glenoid provide an equal resistance to loosening when subjected to a worst-case cyclic
edge load.
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