Coronal alignment on the single-limb stance radiograph in posterolateral rotatory instability, osteoarthritis and healthy knees.
BACKGROUND
We aimed to determine whether coronal alignment measured on the single-limb stance (SLS) radiographs differs from those on the double-limb stance (DLS) images. We also investigated whether the size of such differences was affected by the knee pathology, lower limb alignment, and geometry of the tibia or femur.


METHODS
We measured coronal alignment with mechanical tibiofemoral angle (MTFA) on the DLS and SLS radiographs in patients with posterolateral rotatory instability (PLRI, 30 knees), osteoarthritis (OA) with varus deformity who were scheduled for high tibial osteotomy (HTO) (60 knees), and in normal control (60 knees). The measurements on the SLS radiographs were compared with those on DLS images and the size of the differences were compared between the three groups. The correlation between the radiograph-related differences of coronal alignment and the limb alignment or geometry of tibia/femur was investigated. In the OA group, the size of the radiograph-related differences before HTO were compared with those after surgery.


RESULTS
The coronal alignment on the SLS radiographs indicated varus accentuation compared to those on the DLS radiographs in the PLRI and OA groups (1.6 and 2.4°, respectively), while it was negligible in the normal group. Greater varus inclination of the tibial plateau was related to greater varus accentuation (r=0.249). The HTO decreased the extent of varus accentuation in the OA group (reduction of varus accentuation=1.5°).


CONCLUSIONS
Coronal alignment on the SLS radiograph is different from static alignment measured on the DLS radiograph, which may reflect dynamic alignment.
Department of Orthopaedic Surgery, CM Hospital, Seoul, Republic of Korea. Electronic address: orthonyg@gmail.com.
Young Gon
YG
Na
Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul National University Boramae Hospital, Seoul, Republic of Korea. Electronic address: moonjongchang@gmail.com.
Moon Jong
MJ
Chang
Joint Reconstruction Center, Seoul National University Bundang Hospital, 82 Gumi-ro, 173 Beon-gil Bundang-gu, Seongnam-si, Gyeonggi-do 13620, Republic of Korea. Electronic address: eomsh22@hanmail.net.
Sang Hwa
SH
Eom
Joint Reconstruction Center, Seoul National University Bundang Hospital, 82 Gumi-ro, 173 Beon-gil Bundang-gu, Seongnam-si, Gyeonggi-do 13620, Republic of Korea. Electronic address: eclipse36@naver.com.
Seok Jin
SJ
Kim
Joint Reconstruction Center, Seoul National University Bundang Hospital, 82 Gumi-ro, 173 Beon-gil Bundang-gu, Seongnam-si, Gyeonggi-do 13620, Republic of Korea. Electronic address: neoz0708@gmail.com.
Seong Cheol
SC
Park
Joint Reconstruction Center, Seoul National University Bundang Hospital, 82 Gumi-ro, 173 Beon-gil Bundang-gu, Seongnam-si, Gyeonggi-do 13620, Republic of Korea. Electronic address: osktk@snubh.org.
Tae Kyun
TK
Kim
D000368:Aged; D017760:Bone Malalignment / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D010027:Osteotomy; D011859:Radiography; D013977:Tibia / Q000000981:diagnostic imaging*
Double-limb stance; Dynamic alignment; Osteoarthritis; Posterolateral rotatory instability; Single-limb stance