We thank Drs. Alarcón, Lopez-Ben, and Ceccarelli et al for their interest in our work, and we welcome both their comments and research findings in relation to the use of US in the setting of early inflammatory arthritis.
Ceccarelli et al note the possible contrast in definition between the terms “synovitis” and “synovial hypertrophy.” Histologically, both names relate to a pathologic process within the joint, resulting from current or previous inflammatory change within the synovium. We used the word synovitis according to the US description outlined by Szkudlarek et al, who defined it as “a noncompressible hypoechoic intracapsular area (synovial thickening)” (1). This is similar to the OMERACT definition, which describes synovial hypertrophy as “abnormal hypo-echoic, intra-articular tissue that is non-displaceable and poorly compressible and which may exhibit Doppler signal” (2). It is therefore reasonable to assume that these terms are interchangeable for the purposes of US studies.
With regard to the use of a warm-water bath, we believe that although this could potentially vasodilate cutaneous and subcutaneous vasculature, it is unlikely to influence deeper structures, including the synovium. The use of cold gels, extremes of ambient temperature, or exercise prior to US examination are additional variables that are not normally measured in these studies. We therefore conclude that the use of a warm-water bath did not unduly affect our findings.
Ceccarelli et al observed no significant difference between patients with rheumatoid and undifferentiated arthritis regarding the presence of erosions of the fifth MTP joint. In both studies, the number of patients was small and it is possible that variations in disease duration, genetic profiles, and other factors may contribute to divergent findings in such a heterogeneous disease. Both papers confirm that US is a useful and expeditious modality in the assessment of patients with early inflammatory arthritis, and the extension of these findings to larger numbers would be helpful.
We would like to acknowledge the work of Dr. Alarcón and her colleagues in relation to the ultrasonographic detection of erosions in the hands and feet in the absence of radiographic damage (3). As our paper was submitted under the category of Contributions From the Field, the word count and number of references we could include was restricted. In addition, our study focused solely on the US imaging of the fifth MTP joint in patients with both differentiated and undifferentiated early inflammatory arthritis. Taken together, these and other studies highlight the role of US in the early detection of joint damage.