Background Few data have been published about the diagnostic value of standard AP view and Schuss X rays association
Objectives Our objective is to compare the contribution to diagnosis of the association standard AP view and Schuss X rays versus the single Schuss X ray.
Methods Studied population: From 2007 to 2009, a general population, two-phase study was conducted in 6 French centers to estimate the prevalence of knee and/or hip OA gather a cohort which included only patients with Kellgren Laurence (KL) ≥2 (KHOALA (1)). During this prevalence study we obtained X-rays from 3707 subjects aged 40 to 75 years old. For the current work, we selected the first 304 participants regardless of their stage. X-rays reading: A first reading of standard AP + Schuss views was carried out by an expert rheumatologist (BM), and then a second reading of Schuss X-rays only was carried out remotely (blinded to the results of the first lecture), by the same examiner. Delay between the two readings was 2 years. Analysis focused on the comparison of KL stage of each knee, as well as on osteophytes detection and localization (Medial Condyle (MC), Lateral (LC), Medial Tibial Plateau (MTP) or Lateral (LTP) ranked from 0 to 3), Joint space narrowing (JSN) (ranked from 0 to 4) and bone sclerosis (MC, LC, MTP, LTP).
Results Mean age was 58 years (8.6), Body Mass Index (BMI) was 29.8 (5.4).
Comparison of 2 readings showed a significantly higher proportion of patients with a KL ≥2 with the two X-ray combined (right knee: p<0.0001; left knee: p<0.0003). In contrast, a finer analysis taking into account JSN (respectively p=0.8 and 0.07), osteophytes (0.8 and 0.3), and bone condensation (0.6 and 0.6) didn't show any significant differences. Our data suggested a less value of Schuss X-ray alone when BMI is high. A comparison of Schuss versus standard AP X-rays alone showed a Schuss superiority to detect JSN and osteophytes (p=0.0001 and p=0.0001).
Conclusions Combined procedure detect more radiological OA than Schuss X ray alone. However, when assessing separately the two main features of OA (JSN and osteophytes), no significant difference appeared in spite of a trend favouring the combined procedure. The partly subjective global KL scoring system is probably more robust to detect OA than separated assessment of JSN and osteophytes alone.Finally, regarding higher cost and irradiation of both radiographs compared to schuss alone, the choice of the procedure will depend on the aim of the study: in epidemiological studies only schuss may be realised, while in a clinical diagnosis perspective both views should be recommended.
Guillemin F et al; KHOALA cohort study. The KHOALA cohort of knee and hip osteoarthritis in France. Joint Bone Spine. 2012;79(6):597-603
Disclosure of Interest : None declared
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