C. Delaunay et Ai. Kapandji, 10-YEAR SURVIVORSHIP OF THE ZWEYMULLER PROSTHESIS IN CEMENTLESS PRIMARY TOTAL HIP-ARTHROPLASTY, Revue de chirurgie orthopedique et reparatrice de l'appareil moteur, 84(5), 1998, pp. 421-432
Purpose of the study To provide clinical and survival results of a con
secutive series of primary total hip arthroplasties (THA) performed wi
th the Zweymuller grit-blasted titanium total hip prostheses of the 2
last designs (Hg and AIloclassic-SL), and to compare the IO-year survi
vorship with those of other prostheses either cemented or cementless.
Material and methods Of 238 index THAs, 213 hips have been prospective
ly studied with a 2 year minimum follow-up (average, 6.5 years; range,
25 to 146 months). Mean age was 63 years. Hip arthrosis was the main
diagnosis (88 per cent).Results Intra-operative fracture rate (n = 238
primary THAs) was 6.3 per cent, 2.9 per cent and 1.3 per cent, for th
e greater trochanter, the upper femur, and the acetabulum, respectivel
y. Early dislocation rate was 4.6 per cent. Average Postel-Merle d'Aub
igne-Charnley Hip Score raised from 11.3 points pre-operatively, to 16
.7 points at last follow-up. Clinical results were graded excellent an
d good in 93 per cent of hips, fair in 5.1 per cent, and poor in 1.9 p
er cent. At least 19.5 per cent of stems subsided 2-10 mm within the f
irst 2 years. Reactive and lucent lines have been noted in 33 hips (15
.5 per cent) in complete Gruen zones 1 and 7, and in 4 hips (1.9 per c
ent) extending in zones 2 and 6. 1 Hg and I SL components definitively
failed to stabilize, and have been revised, at 5.6 and 2.4 years, res
pectively. Proximal mild stress shielding and Brooker III and IV heter
otopic bone formation were noted in 11.7 per cent and 12.7 per cent of
hips, respectively. Beside one immediate revision, 4 threaded compone
nts failed to achieve initial stability. Two migrated within the first
2 years, then stabilized with good clinical results at 8.5 and 5.2 ye
ars. The 2 others failed their osseointegration, with only 1 revision
thus far. Most immediate post-surgery bone-implant acetabular gaps in
57.8 per cent of hips, have nearly disappeared at last control, with r
esidual lucencies around 7 per cent of rings. Annual linear wear rate
superior to 0.2 mm per year could be detected in only 1 ceramic-PE bea
ring surfaces, but femoral osteolysis was seen in 3 cases. There has b
een no ceramic head breakage thus far. At 10 years, survivorship of th
e 238 index THAs with ''pain graded < 5'' and ''revision for clinical
failure'' (dislocation excluded) as end point was 95.8 per cent and 98
per cent, respectively. With ''definite loosening'' (radiographic fai
lure) as end point, 10 year survivorship was 99.1 per cent for the ste
ms and 98.6 per cent for the threaded cups. Discussion Once osseointeg
ration apparently occured, the authors have never observed any seconda
ry migration indicating failure of the bone-implant anchorage. The fem
oral implantation technique was critical and improved following an una
voidable learning curve. Liner disassociation, evolutive acetabular lu
cencies, worrisome wear and osteolysis were not of great concern thus
far. Results of these grit-blasted threaded cups are much better than
those of former smooth screw rings. Conclusion Ten year survivorships
of the Zweymuller cementless prostheses in primary THA are better than
those of former cemented or cementless prostheses, and are within the
range of the best results published at equivalent follow-up with hybr
id reconstructions with use of stems cemented with up to date techniqu
e and hemispheric cementless press-fit cups with screw fixation.