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D. Beverland, E. Doran, S. O’Brien, J. Hill, R. Pagoti
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Revisions
With respect to the group of 270 patients who
are between 6 and 11 years from surgery there
have been 3 revisions.
• One patient
with subsidence of a cementless
tibial tray at three months was revised to a
cemented long-stemmed component. Post-
operatively the patient’s AKS clinical score
improved to 71, ROM is 0-1050 and 7 years
since surgery she remains pain free.
• Two patients
had open washout within
3 weeks of the index operation with change
of the polyethylene insert. Both patients have
since died of unrelated causes free of
infection at 4 and 7 years.
A further 5 knees had additional surgery for
problems relating to their knee :
• One patient had an arthroscopic washout for
infection 32 months after index operation
and remains infection free, 6 years since the
washout;
• One patient had a washout of the knee for
haematoma one week after surgery, with no
further problems;
• Two patients had manipulation under
anesthesia (MUA). The first patient had a
ROM of 10-750 preoperatively, 0-320
6 months post-operatively and, following
MUA, 0-450 one year post-operatively. The
second patient had a ROM of 5-1200 pre-
operatively, 5-600 three months post-
operatively and following MUA, 0-1050 one
year post-operatively;
• There was one non-recurrent “spin out” [5]
of the mobile bearing at 4 weeks managed by
closed reduction and plaster cast in extension
for eight weeks.
Other non-operative complications
One patient required a vacuum pump for wound
dehiscence but at most recent review (77
months) reported no problems.
There were two patients who had severe pre-
operative Patello-Femoral osteoarthritis with
postoperative patellar instability. One patient
responded to six weeks of immobilisation in an
extension knee brace. One year post-operatively
she had a ROM of 0-1000 without further
patellar subluxation. The second patient had a
recurrence of a chronic pre-operative patella
dislocation at three months. Despite eight
weeks of plaster cast treatment she did not
improve and remains dislocated. She has
refused any further treatment and is able to
mobilise with an extension brace. We have had
no cases common peroneal nerve palsy
following a valgus knee.
Discussion
Patellar dislocation as a problem after TKA for
valgus deformity has been reported in up to 2%
to 4% [6]. In the present series there were two
patients with post-operative patellar problems
(0.4%). Higher rates of lateral release have
been reported for valgus knees to prevent
patellar maltracking. Stern
et al.
[7] andAglietti
et al.
[l8] reported a 76 and 67% rate of lateral
patellar release for valgus knees respectively.
In the present study only 14% required lateral
patellar release, and 93.1% achieved central
patello-femoral alignment.
Common peroneal nerve palsy has been
reported in up to 4% [7] of valgus knees. There
were no cases in our series. We feel that a
combination of minimal soft tissue release,
avoidance of over correction and immobilising
the knee in flexion post-operatively decreases
the tension in the nerve.
In the past several studies have shown that
alignment effects the survival of total knee
arthroplasty [9, 10]. However, Smith
et al.
[11]
found that alignment did not affect the incidence
or progression of radiolucent lines or clinical
outcome post-operatively. More recent studies
by Parratte
et al.
[12] suggest that achieving a
neutral mechanical axis may not always be the
right target in TKA as it may not correlate with
long term survival. Other published work
however supports the opposite view (Mullaji A
et al.
[13]. Our Philosophy is to achieve a
balanced extension gap rather than the more
traditional focus on a neutral mechanical axis.
We accepted 70 of MAD as an acceptable