Ultrasonographic Detection of Thickened Joint Capsules and Tendons As Marker of Dialysis-related Amyloidosis - a Cross-sectional and Longitudinal-study

Dialysis-related amyloidosis is characterized by a beta2-microglobulin (beta2M) infiltration of joint synovia, tendons and capsules. We report a cross-sectional ultrasonographic evaluation of supraspinatus tendon and femoral neck capsule thickness in 49 patients on long-term haemodialysis. Ultrasonographic evaluation was repeated 21 +/- 4 (SD) Months later in 16 patients. Normal values for the supraspinatus tendon and femoral neck capsule were defined in a group of control subjects without history or signs of joint disease. Among the 49 patients, aged 21-86 (median 59) years, dialysed for 1-228 (median 97) months, 33 had at least one abnormal joint. The prevalence of patients with at least one and at least two abnormal joints, the number of abnormal joints per patient, and the thickness of the supraspinatus tendon and femoral neck capsule increased significantly with dialysis duration (P<0.001 for all parameters considered). By multiple linear regression analysis, mean thickness of the supraspinatus tendon was positively related to both dialysis duration (P < 0.0001) and age (P = 0.036) independently. All (n = 11) patients with radiological and/or histological evidence of dialysis-related amyloidosis at the time of ultrasonography had thickened supraspinatus tendon and/or femoral neck capsule; which were also thickened in an additional 22 patients without radiological evidence of dialysis-related amyloidosis. Three died within 5-10 months of the ultrasonographic investigation : post-mortem examination of the periarticular tissue confirmed that the detected thickening was due in all three to beta2M amyloid infiltration. Sixteen patients underwent a second ultrasonographic evaluation 21 +/- 4 months later. In nine patients on dialysis for > 60 months at the time of the first evaluation, mean femoral neck capsule thickness increased significantly (7.0 +/- 0.8 to 8.2 +/- 2.3 mm, P = 0.017) whereas mean supraspinatus tendon thickness increment was not significant (6.6 +/- 0.4 to 7 +/- 0.8 mm, P = 0.23). In the seven other subjects dialysed for < 60 months, neither the supraspinatus tendon nor femoral neck capsule thickness changed. We suggest that ultrasonographic measurement of supraspinatus tendon and femoral neck capsule thickness is a useful, non-invasive tool to detect and monitor dialysis-related amyloidosis.