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S. Parratte, M. Ollivier, X. Flecher, J.-M. Aubaniac, J.-N. Argenson
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All patients receved an autocentric patello
femoral prosthesis (DePuy, Warsaw, IN) with a
cemented polyethylene (PE) patella and a Co-
Cr femoral component. The design characte
ristics and the surgical technique regarding this
device have been described in a previous paper.
Concomitant procedures done at the time of
PFA included eight osteotomies (three cases of
upper tibial osteotomy for varus correction,
and five cases of lower femoral osteotomy for
valgus correction aiming in every cases for
neutral alignment) and five realignments of the
anterior tibial tuberosity for medialization.
Clinical knee scores were calculated using the
Knee Society Score, and follow-up radiographs
were assessed for signs of loosening and
complete degeneration of the tibiofemoral
joint. The clinical and radiographic evaluations
were done by a single observer independent
from the operating surgeons. Revision of the
PFA for any reason was considered an end
point for survival.
Results
Degeneration of the unreplaced tibiofemoral
joint was the most frequent cause of failure of
PFA. Revision surgery was done in 14 of the 57
living patients for progression of osteoarthritis
in the tibiofemoral compartment and the PFAs
were converted toTKAat an average of 7.3 years
(range, 1-12 years) after the implantation of the
patellofemoral prostheses.
Progressive degeneration was noted mainly in
the primary osteoarthritis etiologic group (8 of
18 patients) compared with the two other
groups (three of 21 patients in the instability
group and three of 18 patients in the post
traumatic group). Eleven patients were revised
for loosening after an average follow-up of
4.5 years (range, 1-10 years) with an equal
occurrence in the three groups. All the revisions
for loosening were done on the femoral
component except in one patient who had a
patellectomy for patellar fracture. Among these
11 revisions for loosening three were caused by
infection, in patients who had at least one
previous surgery. Early aseptic loosening in
three patients with uncemented femoral
components were treated successfully with
insertion of a cemented femoral component.
The remaining four patients who had revision
surgery for loosening of their PFA components
had conversion to TKA. The knees of six
patients were revised for stiffness; two were
treated by manipulation under anesthesia and
four(thesepatientswerepartoftheposttraumatic
etiologic group) required conversion to TKA.
Additionally, five patients required a secondary
lateral release with resection of the lateral
patellar facet (which was not done routinely at
the beginning of our experience) and had good
results. The cumulative survival rate for the all
group, including the 9 patients died of unrelated
causes, was 58% at 16 years [95% confidence
intervals (CI)].
Most patients had a substantial and persistent
improvement in knee function for patients
affected by isolated patellofemoral arthritis and
treated by PFA. For the 29 of 57 patients (51%)
who still had their original PFA prostheses in
place at the time of follow-up the mean Knee
Society pain score had improved from
53.1 points preoperatively (range, 43-70 points)
to 78.5 points (range, 60-100 points) at the final
follow-up. The mean Knee Society function
score improved from 40.6 points (range, 10-80
points) preoperatively to 81.2 points (range,
40-100 points) at final follow-up. Twenty-one
patients had no complaints of pain whereas
11 complained of moderate pain.
Twenty patients had a range of motion (ROM)
greater than 105°, 10 had a ROM between 90°
and 105°, and two had a ROM less than 90°. The
radiographic analysis of the knees with the PFA
still in place showed no evidence of mechanical
failure or loosening and no detrimental
degeneration of the tibiofemoral joint.
Discussion
The long-term evaluation of PFA presented in
this study showed a high rate of conversion to
TKA after a 16 years’ average followup. The
most frequent reason for failure was progression
of arthritis in the tibiofemoral joint, occurring