Læknablaðið - 15.04.2007, Page 62

ÞING SKURÐLÆKNA, SVÆFINGA- OG GJÖRGÆSLULÆKNA / ÁGRIP ERINDA
sign based on modern joint replacement technology including;
unconstrained over normal ROM, semi-constrained in maxi-
mum ROM, interna! geometry and mechanics provides “soft”
stops, mechanically stable against dislocation or subluxation,
”press fit” provided by milled endplates, porous coated shells
that provides for bone ingrowth, polished shell that results in
low friction between shell / nucleus.The aims of the study were:
To determine if and when the Bryan cervical disc prosthesis is
stable at the bone-metal interface and to detect any significant
motion / migration of the implant over 2 years at the interface
using RadioStereometric Analysis (RSA). RSA is the most
precise radiological method to study small motions / migra-
tions between e.g. vertebrae in vivo by using tantalum beads
implanted at surgery. Accuracy in the study: 95 %, CI: Rotation
<1.7 degrees and translation <0.1 mm.
Material and methods: 11 consecutive patients that were operat-
ed on one level cervical radiculopathy and/or myelopathy were
included. Discectomy and implantation of a specifically “RSA
manufactured” Bryan cervical disc prosthesis was performed.
RSA examinations were performed postoperatively and at the
2,6,12,26 week and 1 year and 2 year follow-up. Results. 6 pros-
thesis were immediately stable, 9 were stable at 3 months all 11
were stable at the other follow-up examinations.
Discussion: This is a small series of patients but sufficient to
calculate RSA numbers. The maximum motion/migration of the
shell before stabilization reached 0.4 mm translation and 4.5°
rotation. Similar findings in RSA-studies on cementless total hip
and knee prostheses i.e. migration up to 3-6 months is common.
The results imply that the prosthesis will stay safely fixed to the
bone for a longer period of time meaning >6-7 years, compared
to similar data on hip and knee surgery
E-39 Mortality after knee arthroplasty in Sweden
Grétar Ottó Róbertsson1'3, Anna Stefánsdóttir1, Jonas Ranstam2, Lars
Lidgren1
otto. robertsson@med. ltt.se
'Dept. of Orthopedics, Lund University Hospital, 2National Swedish Competence
Center for Musculoskeletal Disorders, Lund, Sweden, ’Dept. of Orthopedics,
Landspítali, Reykjavík
Introduction: Hip and knee arthroplasties are most often per-
formed in an elderly population and are associated with some
operative risks. Although reports on early postoperative mor-
tality after knee arthtroplasty have been somewhat divergent,
several studies have reported an increased overall longevity of
patients with osteoarthritis undergoing arthroplasty. This ob-
servation has commonly been interpreted as general conse-
quence of selecting comparatively healthy patients for surgery.
However, the Norwegian arthroplasty register has also reported
that young hip arthroplasty patients with osteoarthritis have
an increased 10-year mortality rate as compared to the general
population. All these observations have been based on rela-
tively short time of observation.The Swedish Knee Arthroplasty
Register (SKAR) was established in 1975 and is the oldest
national arthroplasty register. This allowed us to follow knee
arthroplasty patients for a longer period of time than previously
possible with respect to mortality and underlying diseases caus-
ing the death.
Material and methods: 65,515 patients with osteoarthritis were
registered as having their first primary knee arthroplasty during
1975 and 2003. For these a survival curve was calculated using the
Kaplan-Meier method and the related expected survival curve
was estimated using the Hakulinen method. Cause of death data
for the period 1980-2002 were contributed by the Swedish cause
of death register and for a subset of 57,969 patients operated
during this period we calculated the cause specific mortality in
terms of standardized mortality ratios (SMR).
Results: There was a reduced overall mortality during the 12
first postoperative years after which the mortality increased
and became significantly higher than for the general population.
Age-specific analyses indicated an inverse correlation between
age and mortality; the younger the patients, the higher their
mortality. The shift at 12 years was caused by a relative over-
representation of younger patients with a longer follow-up.
Analyses of specific causes of death showed higher mortality for
cardiovascular, gastrointestinal and urogenital diseases.
Conclusion: Our findings could indicate a correlation between
an early debut of osteoarthritis and some other co-morbidity
which would be in accordance with reports linking osteoarthritis
with an increased risk of cardiovascular death. Another possible
explanation is that the selection of patients for operation is age
dependent. Thus, that in young age there is a tendency to offer
surgery to those with co-morbidities and less life expectancy but
in old age to those relatively healthy and more likely to endure
the operation. Further research into postoperative mortality is
to be recommended.
E-40 A prospective randomized study evaluating the
clinical effects of ADCON-L applications in patients under-
going lumbar microdiscectomy
Björn Zoéga', Katarina Rönnberg2
bjornz@landspitali. is
'Landspitali, Reykjavík, Iceland, 2Dept. of Orthopedics, Sahlgrenska
University Hospital, Göteborg, Sweden
Introduction: Recurrent leg pain after lumbar microdiscectomy
occurs in some patients. One suggested explanation is scarring
around the exposed nerve root. ADCON-L is a carbohydrate
polymer gel that has been demonstrated to prevent scar forma-
tion when applied on nerve roots in animal models. However,
there is conflicting data regarding the clinical effects.
Materia) and mcthods: A prospective randomized study with
2 years follow-up was undertaken to investigate the effects of
ADCON-L on clinical outcome in patients undergoing lumbar
microdiscectomy. 109 consecutive patients (50 men, 59 women,
mean age 39, range 18-66) with lumbar disc herniation at the
level L4-L5 or L5-S1 undergoing lumbar microdiscectomy were
included in the study. 58 patients received ADCON-L perope-
ratively and 51 patients served as controls. Patients’ function and
satisfaction were assessed with questionnaires at baseline and 12
and 24 months postoperatively. Pain was assessed by VAS for
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