Malalignment and subchondral bone turnover in contralateral knees of overweight/obese women with unilateral osteoarthritis: implications for bilateral disease.
OBJECTIVE
To explore whether the risk of incident tibiofemoral (TF) osteoarthritis (OA) in the radiographically normal contralateral knee of overweight/obese women with unilateral knee OA is mediated by malalignment and/or preceded by increased turnover of subchondral bone.


METHODS
We used data of post hoc analyses from a randomized controlled trial. Cross-sectional analyses evaluated the baseline association between frontal plane alignment and bone turnover in the medial TF compartment in 78 radiographically normal contralateral knees. Longitudinal analyses ascertained whether incident radiographic OA (TF osteophyte formation within 30 months) was associated with malalignment and/or increased bone turnover at baseline. Alignment subcategories (varus/neutral/valgus) were based on the anatomic axis angle. (99m)Tc-methylene diphosphonate uptake in a late-phase bone scan was quantified in regions of interest in the medial tibia (MT) and medial femur (MF) and adjusted for uptake in a reference segment of the ipsilateral tibial shaft (TS).


RESULTS
MF and MT uptake in varus contralateral knees was 50-55% greater than in the TS. Adjusted MT uptake in varus contralateral knees was significantly greater than that in neutral and valgus contralateral knees (mean 1.55 versus 1.38 and 1.43, respectively; P < 0.05). Among 69 contralateral knees followed longitudinally, 22 (32%) developed TF OA. Varus angulation was associated with a marginally significant increase in the odds of incident OA (adjusted odds ratio 3.98, P = 0.067).


CONCLUSIONS
While the small sample size limited our ability to detect statistically significant risk factors, these data suggest that the risk of developing bilateral TF OA in overweight/obese women may be mediated by varus malalignment.
Indiana University School of Medicine, Indianapolis, USA. smazzuca@iupui.edu
Steven A
SA
Mazzuca
Kenneth D
KD
Brandt
Kathleen A
KA
Lane
Rafael
R
Chakr
D017760:Bone Malalignment / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology; D016723:Bone Remodeling; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D016015:Logistic Models; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D016017:Odds Ratio; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology; D054850:Osteophyte / Q000000981:diagnostic imaging / Q000473:pathology*; D050177:Overweight / Q000150:complications*; D011237:Predictive Value of Tests; D011859:Radiography; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D018570:Risk Assessment; D012307:Risk Factors; D013669:Technetium Tc 99m Medronate
D019275:Radiopharmaceuticals; D013669:Technetium Tc 99m Medronate