KNEE
Changes in patellar alignment after total knee arthroplasty
Shingo Fukagawa
•
Shuichi Matsuda
•
Hideki Mizu-uchi
•
Hiromasa Miura
•
Ken Okazaki
•
Yukihide Iwamoto
Received: 17 March 2009 / Accepted: 3 May 2010 / Published online: 5 June 2010
Ó Springer-Verlag 2010
Abstract Although the results of total knee arthroplasty
continue to improve, problems related to the patellofemoral
joint remain significant. This study examined the factors
affecting patellar alignment after total knee arthroplasty
and subsequent changes in 56 knees during a postoperative
period of 5.3 years. None of the knees examined displayed
any clinical complications of the patellofemoral joint; no
revision surgeries were necessary, with acceptable patellar
alignment on average. The patellar resection angle had a
strong influence on patellar alignment. Thinning of the
patellar remnant on the medial side can increase postop-
erative lateral tilt, which leads to a need for lateral reti-
nacular release. Although the changes in patellar alignment
were minimal, the tendency that postoperative varus
alignment resulted in patellar lateral tilt was observed.
As postoperative femorotibial misalignment can lead to
patellofemoral problems after total knee arthroplasty,
surgeons need to pay scrupulous attention to femorotibial
alignment and proper patellar preparation to decrease
patellofemoral complications.
Keywords Total knee arthroplasty Á Patellar alignment Á
Postoperative change
Introduction
Biomechanical studies have demonstrated the mechanism
by which femorotibial alignment contributes to patel-
lofemoral osteoarthritis; valgus malalignment results in
an increased Q-angle and increased lateral force on the
patella, while varus malalignment leads to a decreased
Q-angle and a decrease in lateral force on the patella
[10, 11]. Radiographic studies have indicated that medial
patellofemoral osteoarthritis is associated with a varus
alignment [5, 7]. Therefore, the bony alignment of the
femorotibial joint has a possibility to affect patellar
alignment even after knee surgery. As yet, however, no
studies have evaluated the influence of femorotibial
alignment on patellar alignment after total knee arthro-
plasty (TKA).
While it is thought that patellar alignment after TKA
is influenced by soft tissue tension, knee alignment, and
patellar preparation [1, 2, 4, 6, 8, 9, 17–20, 27], a few
studies have addressed changes in the patellar alignment
[14, 21, 22]. To our knowledge, no study has evaluated
the relationship between changes in patellar alignment
and surgical technique, including patellar preparation and
femorotibial alignment.
This study sought to determine the effect of pre-
operative patellar alignment and surgical factors, such
as patellar resection angle, patellar resection thickness,
and femorotibial alignment, on postoperative patellar
alignment after TKA. This study also examined post-
operative changes in patellar alignment during a post-
operative period of 5.3 years and the influence of
surgical factors on these changes. We hypothesized
that postoperative varus alignment would lead patella
to move medially, which would also lead to tilt
laterally.
S. Fukagawa Á S. Matsuda (&) Á H. Mizu-uchi Á H. Miura Á
K. Okazaki Á Y. Iwamoto
Department of Orthopaedic Surgery,
Graduate School of Medical Sciences, Kyushu University,
3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
e-mail: mazda@ortho.med.kyushu-u.ac.jp
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Knee Surg Sports Traumatol Arthrosc (2011) 19:99–104
DOI 10.1007/s00167-010-1164-7