Do persons with asymmetric hip pain or radiographic hip OA have worse pain and structure outcomes in the knee opposite the more affected hip? Data from the Osteoarthritis Initiative.
OBJECTIVE
To determine if asymmetry between hips in pain or radiographic osteoarthritis (RHOA) is associated with worse pain and joint space narrowing (JSN) at baseline and longitudinally in knees contralateral to more affected hips.


METHODS
We studied 279 participants in the Osteoarthritis Initiative with baseline asymmetry between hips in pain and 483 with asymmetry in RHOA none of whom had a hip replacement for ≥4 years after baseline. RHOA assessed from pelvis radiographs was categorized as none, possible or definite and hip pain on most days of a month in the past year as present/absent. Knee pain (WOMAC scale) and JSN (fixed flexion radiographs) were categorized as none, mild and moderate-severe. We compared knees contralateral and ipsilateral to more affected hips on baseline knee pain and JSN using clustered multinomial regression and on change in knee pain and JSN over 4-5 years using generalized linear and logistic estimating equations.


RESULTS
Knees contralateral to painful hips had less baseline pain ("moderate-severe" vs "none", relative risk ratio [RRR]: 0.39, 95% CI = 0.27-0.57), but greater baseline JSN ("moderate-severe" vs "none", RRR: 1.62, 95% CI = 1.09-2.38) and greater worsening of pain during follow-up (P = 0.001). Knees contralateral to hips with worse RHOA had nonsignificant trends for greater baseline JSN (P = 0.10) and JSN progression (P = 0.17).


CONCLUSIONS
These findings provide limited support for the hypothesis that early asymmetry in hip pain and RHOA is associated with worse pain and structural outcomes in knees contralateral to the more affected hip.
Musculoskeletal and Quantitative Imaging Research, Department of Radiology and Biomedical Imaging, University of California San Francisco, 185 Berry Street, Suite 350, San Francisco, CA 94107, USA.
G B
GB
Joseph
Department of Epidemiology and Biostatistics, University of California San Francisco, Mission Hall, 550 16th St. 2nd Floor, Campus Box #0560 San Francisco, CA 94158, USA.
J F
JF
Hilton
Department of Radiology, Technische Universitaet Muenchen, Ismaninger Strasse 22, 81675 Munich, Germany.
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PM
Jungmann
Department of Epidemiology and Biostatistics, University of California San Francisco, Mission Hall, 550 16th St. 2nd Floor, Campus Box #0560 San Francisco, CA 94158, USA.
J A
JA
Lynch
Department of Internal Medicine, UC Davis Medical Center, Sacramento, CA 95817, USA.
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NE
Lane
Department of Epidemiology and Biostatistics, University of California San Francisco, Mission Hall, 550 16th St. 2nd Floor, Campus Box #0560 San Francisco, CA 94158, USA.
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F
Liu
Department of Epidemiology and Biostatistics, University of California San Francisco, Mission Hall, 550 16th St. 2nd Floor, Campus Box #0560 San Francisco, CA 94158, USA.
C E
CE
McCulloch
Department of Epidemiology and Biostatistics, University of California San Francisco, Mission Hall, 550 16th St. 2nd Floor, Campus Box #0560 San Francisco, CA 94158, USA.
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I
Tolstykh
Musculoskeletal and Quantitative Imaging Research, Department of Radiology and Biomedical Imaging, University of California San Francisco, 185 Berry Street, Suite 350, San Francisco, CA 94107, USA.
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Link
Department of Epidemiology and Biostatistics, University of California San Francisco, Mission Hall, 550 16th St. 2nd Floor, Campus Box #0560 San Francisco, CA 94158, USA. Electronic address: mnevitt@psg.ucsf.edu.
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Nevitt
D000368:Aged; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D010146:Pain / Q000209:etiology* / Q000473:pathology; D010147:Pain Measurement / Q000379:methods; D011859:Radiography / Q000379:methods
Hip osteoarthritis; Joint pain; Knee osteoarthritis; Structural outcomes