Association of incident symptomatic hip osteoarthritis with differences in hip shape by active shape modeling: the Johnston County Osteoarthritis Project.
OBJECTIVE
To investigate hip shape by active shape modeling (ASM) as a potential predictor of incident radiographic hip osteoarthritis (RHOA) and symptomatic hip osteoarthritis (SRHOA).


METHODS
All hips developing RHOA from baseline (Kellgren/Lawrence [K/L] grade 0/1) to mean 6-year followup (K/L grade ≥2, 190 hips) and 1:1 control hips (K/L grade 0/1 at both times, 192 hips) were included. Proximal femur shape was defined on baseline anteroposterior pelvis radiographs and submitted to ASM, producing a mean shape and continuous variables representing independent modes of shape variation. Mode scores (n = 14, explaining 95% of shape variance) were simultaneously included in logistic regression models with incident RHOA and SRHOA as dependent variables, adjusted for intraperson correlations, sex, race, body mass index (BMI), baseline K/L grade, and/or symptoms.


RESULTS
We evaluated 382 hips from 342 individuals: 61% women and 83% white, with mean age 62 years and mean BMI 29 kg/m(2) . Several modes differed by sex and race, but no modes were associated with incident RHOA overall. Among men only, modes 1 and 2 were significantly associated (for a 1-SD decrease in mode 1 score: odds ratio [OR] 1.7 [95% confidence interval (95% CI) 1.1-2.5] and for a 1-SD increase in mode 2 score: OR 1.5 [95% CI 1.0-2.2]) with incident RHOA. A 1-SD decrease in mode 2 or 3 score increased the odds of SRHOA by 50%.


CONCLUSIONS
This study confirms other reports that variations in proximal femur shape have a modest association with incident hip OA. The observation of proximal femur shape associations with hip symptoms requires further investigation.
University of North Carolina, Chapel Hill.
Amanda E
AE
Nelson
Felix
F
Liu
John A
JA
Lynch
Jordan B
JB
Renner
Todd A
TA
Schwartz
Nancy E
NE
Lane
Joanne M
JM
Jordan
D001741:Black or African American; D016022:Case-Control Studies; D005260:Female; D005269:Femur / Q000473:pathology*; D005500:Follow-Up Studies; D006621:Hip Joint / Q000473:pathology*; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D008954:Models, Biological; D009657:North Carolina; D015207:Osteoarthritis, Hip / Q000453:epidemiology* / Q000208:ethnology*; D044469:Racial Groups; D012307:Risk Factors; D012737:Sex Factors; D044465:White People