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To compare the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of a baseline late-phase bone scan and assessments of the radiographic and symptomatic severity of knee osteoarthritis (OA) at baseline as predictors of loss of articular cartilage thickness, as reflected in joint space narrowing (JSN) in the medial tibiofemoral compartment.Subjects (174 obese women, 45-64 yrs of age, with unilateral knee OA) were a subset of a larger cohort who participated in a placebo controlled trial of a disease modifying OA drug. Uptake of technetium medronate (99mTc-MDP) in anteroposterior (AP) and lateral views of a late-phase bone scan was measured at baseline in a region of interest drawn around the medial tibia, and was adjusted for (i.e., expressed as a ratio to) uptake in a reference segment of the tibial shaft, which served as an internal standard. Each subject underwent a fluoroscopically standardized radiographic examination of the knees (semiflexed AP view) and a pain assessment with the WOMAC OA Index at baseline, 16 months, and 30 months.Controlling for baseline joint space width and treatment group, multiple linear regression models showed that the adjusted 99mTc-MDP uptake at baseline was a significant predictor of joint space narrowing (JSN) in the index knee at 16 months (b = 0.180, p = 0.015) and 30 months (b = 0.221, p = 0.049). In the contralateral knee, uptake was only a marginally significant predictor of JSN at 30 months (b = 0.246, p = 0.083). Uptake in the upper and middle tertiles of the distribution predicted subjects who would exhibit JSN/= 0.50 mm within 16 months with 65% sensitivity (PPV 23%) and 36% specificity (NPV 77%). In contrast, a prediction rule based solely on the presence of Kellgren-Lawrence grade 3 OA severity and greater than median WOMAC Pain score identified progressors with 65% sensitivity (PPV 48%) and 79% specificity (NPV 88%).Although the level of adjusted 99mTc-MDP uptake was significantly associated with JSN in knees with established radiographic OA, baseline bone scintigraphy is inferior to the radiographic severity of OA and knee pain (alone or in combination) as a predictor of loss of articular cartilage in subjects with knee OA.

To determine the predictive value of bone scintigraphy with respect to joint space narrowing (JSN) in patients with knee osteoarthritis (OA), based on quantitative estimates of uptake of a bone-seeking radiopharmaceutical and fluoroscopically standardized knee radiography.Our study group included 86 obese women, 45-64 years of age, with unilateral knee OA. Uptake of technetium medronate (99mTc-MDP) in late-phase bone scans was measured at baseline in 5 regions of interest (ROI: lateral femur, lateral tibia, medial femur, medial tibia, and patellofemoral joint) and was adjusted for uptake (i.e., expressed as a ratio to uptake) in a ROI in the shaft of the tibia, which served as an internal standard. Each subject underwent a fluoroscopically standardized radiograph of the knees (semiflexed anteroposterior view) at baseline, 16, and 30 months. Magnification-corrected minimum joint space width in the medial tibiofemoral compartment was measured by digital image analysis.Followup was available for 79 patients (92%) at 16 months and from 73 patients (85%) at 30 months. On average, 99mTc-MDP uptake in each ROI and in the whole knee (average of 4 tibiofemoral ROI) was 170-240% of that in the tibial shaft. Uptake in the medial tibia and in the whole knee was significantly correlated with JSN at 16 and 30 months (r = 0.22-0.30, p0.05). However, after controlling for age, body mass index, and radiographic severity of OA, the associations between adjusted uptake and JSN were not significant. The rate of JSN in knees of patients with OA who were in the lower tertile with respect to adjusted 99mTc-MDP uptake in the medial tibia was significantly less rapid than in patients in whom uptake was in the middle and upper tertiles (0.04 mm/yr vs 0.18 mm/yr; p0.05). However, after controlling for overall radiographic severity at baseline, the difference in 30-month JSN in knees of patients with OA in the lower versus middle/upper tertiles was not significant.The predictive utility of bone scintigraphy is confirmed by these data. However, its practical value is considerably diminished, insofar as similarly predictive information may be obtained by routine radiographic examination, without the radiation exposure and cost of scintigraphy.

To determine the reproducibility of x-ray technologists, 26 in North America (NA), 24 in Europe (EU), in reliably repositioning patient's osteoarthritic (OA) knees, from computerized measurements of minimum joint space width (JSW) and reproducibility in joint repositioning, during their training for the clinical trial.Technologists from 12 NA and 12 EU clinical radiology units received identical training, at one site on each continent, in performing the fluoroscopically assisted semiflexed knee examination and in quality control criteria (QCC) for film acceptance. Subjects recruited were 129 in NA and 70 in EU, with both knees radiographed for some subjects. Each technologist radiographed 5 OA knees and repeated the process on the same knees 2 to 7 days later. Minimum medial JSW was measured at a single center on digitized images with computer software that corrected for radiographic magnification. Technologists' reproducibility in joint repositioning and JSW measurement was determined from the difference between test and retest.In all, only 3/50 technologists failed qualification criteria with a repeat-film JSW difference0.50 mm. The mean, standard deviation (SD) of the difference in JSW between test/retest for 146 NA film-pairs of -0.020 (0.16) mm was not statistically different from that in 120 EU film-pairs: -0.001 (0.18) mm. In NA and EU 45% of examinations achieved high quality, i.e., JSW difference between repeat films0.1 mm, and 92% achieved excellent to good quality with a difference between repeat films0.3 mm. NA and EU technologists' reproducibility was unaffected by subject's sex, age, and degree of JSW loss. Reproducibility in joint reposition for all technologists was excellent.Between-continent precision of JSW measurements from all accepted pairs of semiflexed views was excellent to very good and similar to the high technical quality achieved in the authors' original report. The value of training incorporating both test/retest radiographs and film QCC is essential for the high technical quality required for multinational clinical trials.