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Lumbar disc arthroplasty lessons learnt in 6
years
Dick J. Zeilstra MD PhD, Neurosurgical Center
Zwolle, The Netherlands
Introduction Lumbar Total Disc Replacement (TDR)
was introduced in 1987. In view of the technical
difficulties and implant characteristics it did
not become more widespread until the beginning of
this century. In our centre TDR has been
performed since March 2002. Patients are included
into a prospective non-randomized cohort study
following strict criteria. Aim of the study is to
show efficacy of the procedure, identify implant
problems and observe long term results.
VAS score
Material and methods Since March 2002 TDR has
been performed in 48 men and 36 women, average
age 41,1 years. Mean BMI was 24,7, complaints had
lasted for an average of 65 months. Thirty
patients were smokers. Treated levels were L3/4
(4 cases), L4/5 (41) and lumbosacral joint (40).
Five patients had a two level treatment, being
and anterior cage at L5/S1 and TDR at L4/5.
Implants used was Prodisc in the first 17 cases
and Maverick in the 67 cases thereafter. The
approach was transperitoneal in 18 and
retroperitoneal in 66 cases. Average operating
time was 112 min for L4/5 and 89 min for L5/S1.
Blood loss was 366 and 525 ml respectively. Averag
e hospital stay was 3,8 days. Intra-operatively
there were two perforations of the iliac vein
which could be repaired but led to about 1600 ml
of blood loss. In one case the segment could not
be mobilized. Post operative complications were
seen in 11 patients abdominal pain for three
days (1), wound haematoma (5), subsidence into
upper endplate (3), retrograde ejaculation (1),
retroperitoneal haematoma (1). Two patients with
subsidence were free of symptoms, one complained
of back pain, after failing conservative
treatment was finally fused with good result for
6 months, after which the problems recurred. He
was seen as an example of bad patients selection.
There was no case of migration, no revision of
any of the implants. Patients were see after 6
weeks, 6 months, 1 year, 2 years and will be seen
at 5 years and further on.
VAS score
Number of patients (y-axis) and their VAS score
(x-axis) at different intervals
Results No patients were lost to follow up. One
patient was fused after subsidence and persisting
back pain, but the result was still unsuccessful.
Mean total follow up is 38 months. 64 patients
were followed up for 2 years or more, 74 for one
year or more. In view of the fact that no obvious
change was observed in the second year (VAS and
ODI scores showed no significant change), the
results of these two groups combined will be
presented. VAS scores dropped from pre-op 7,6 to
3,7 after 6 weeks (plt0,0001), 2,6 after one year
(p0,0043) and 2,3 after two years (n.s.). ODI
scores were 55, 26, 17 and 14 respectively. 55
patients had an improvement of 25 percent points
or more (74). In 57 patients VAS improved 2 or
more points (77). Of the 37 patients not working
before operation, 4 returned to partial and 16 to
full employment (6 were unemployed or
housewives). Only two patient who were working
partially did not return to work. Personal
satisfaction was present in 51 (69) patients, 70
(96) would have the operation again and 50 (68)
were off medication or had significantly reduced
painkiller intake. Average motion of the operated
segment was 7,6 after 6 weeks and 11,7 at the
last visit. L4/5 moved significantly (plt0,001)
better (14,5) than L5/S1 (9,3). Motion of 5or
less was seen in 9 patients, all at the L5/S1
segment. If these patients were excluded the
difference in motion was still highly significant.
Oswestry Disability Index
Discussion and conclusion TDR was introduced to
prevent adjacent segment disease that is thought
to be seen after fusion procedures. Conclusive
proof of this condition has still not been seen.
Nevertheless, if there is such a condition and a
also viable alternative to fusion, it would be
preferable to preserve motion on theoretical
grounds. This limited cohort study shows that the
procedure is both safe and effective, but long
and very long term results need to be
awaited. From the study also emerges a
significant difference in motion between the
lumbo-sacral joint and the more cranial segments.
The fact that 25 of the lumbosacral devices
showed so little motion that it is equivalent to
a fusion and the remaining 75 moved
significantly less than the more cranial
segments, questions the value of TDR in this
lowest segment. With the advent of minimal
invasive fusion procedures it seems that these
may just as well or better be advised to patients
with a L5/S1 discopathy.
Percent points change in ODI (y-axis), each bar
representing one patient
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Return to work (number of patients on y-axis)