Search

SummaryObjectivesTo determine the ability of radiographic bone texture (BTX) parameters to quantify subchondral tibia sclerosis and to examine clinical relevance for assessing osteoarthritis (OA) progression. We examined the relationship between BTX parameters and each of (1) location-specific joint space width (JSW) [JSW(x)] and minimum JSW (mJSW) of the affected compartment, and (2) knee alignment (KA) angle in knee radiographs of participants undergoing total knee arthroplasty (TKA).DesignDigitized fixed-flexion knee radiographs were analyzed for run-length and topological BTX parameters in a subchondral region using an algorithm. Medial JSW(x) was computed at x=0.200, 0.225, 0.250 and 0.275 according to a coordinate system defined by anatomic landmarks. mJSW was determined for medial and lateral compartment lesions. KA angles were determined from radiographs using an anatomic landmark-guided algorithm. JSW measures and the magnitude of knee malalignment were each correlated with BTX parameters. Reproducibility of BTX parameters was measured by root-mean square coefficients of variation (RMSCV%).ResultsRun-length BTX parameters were highly reproducible (RMSCV%5%). In TKA participants (17 women, 13 men; age: 66±9 years; body mass index (BMI): 31±6kgm−2; WOMAC: 41.5±16.1; Kellgren–Lawrence score mode: 4), reduced trabecular spacing (Tb.Sp) and increased free ends (FE) were correlated with decreased JSW after accounting for BMI, gender and knee malalignment. These relationships were dependent on site of JSW measurement.ConclusionHigh reproducibility in quantifying bone sclerosis using Tb.Sp and its significant relationship with JSW demonstrated potential for assessing OA progression. Increased trabecular FE and reduced porosity observed with smaller JSW suggest collapsing subchondral bone or trabecular plate perforation in advanced knee OA.

236 – Table I. Correlation between trabecular space (TrSp) & JSW(x=20.0%) and TrSp & JSW(x=27.5%) JSW(x=20.0%) JSW(x=27.5%) Covariate Adjustment β P-value Lower CI Upper CI β P-value Lower CI Upper CI Unadjusted 0.217 0.218 0.000 0.000 0.243 0.166 0.000 0.000 Gender 0.262 0.023 0.000 0.000 0.246 0.033 0.000 0.000 Gender & BMI 0.313 0.008 0.000 0.000 0.304 0.011 0.000 0.000 Abstract 236 – Table II. Correlation between free ends (FE) & JSW(x=20.0%) and FE & JSW(x=27.5%).236 – Table II. Correlation between free ends (FE) & JSW(x=20.0%) and FE & JSW(x=27.5%). JSW(x=20.0%) JSW(x=27.5%) Covariate Adjustment β P-value Lower CI Upper CI β P-value Lower CI Upper CI Unadjusted -0.249 0.156 -0.012 0.002 -0.252 0.151 -0.009 0.001 BMI -0.370 0.027 -0.014 -0.001 -0.397 0.018 -0.011 -0.001 Age & BMI -0.400 0.021 -0.011 -0.001 -0.400 0.021 -0.011 -0.001 Figure 1. Placement of locater-rule endpoints on anatomic landmarks in knee radiograph for identification of subchondral regions of interest. of significance were identified between the JSW(x=20.0%) and JSW(x=27.5%) sites. No significant correlations between either JSW(x=20.0%) or JSW(x=27.5%) and each of BsTv, BvTv, CI, NL and TrTh were revealed (p>0.05). Conclusions: In the subchondral bone of the tibia, lower JSW(x) measures appear to be associated with larger values in trabecular FE and lower amounts of TrSp after accounting for gender, age and BMI. We anticipated that BMI and age would explain some variability in FE since older individuals tend to have higher BMI and more severe JSW narrowing. On the other hand, smaller JSW(x) correlating with lower TrSp after gender and BMI adjustment supports the proposition that severely OA patients with more JSW narrowing may have higher subchondral bone density. The influence of BMI may be similar to that formerly explained, while gender effects may be due to reduced estrogen levels in postmenopausal women. While minimum JSW may act as a surrogate measure for cartilage thickness, we further propose that digital assessment of JSW(x) could allow estimation of subchondral bone texture properties.