US Features of the Shoulder in Ankylosing Spondylitis
US Features of the Shoulder in Ankylosing Spondylitis
Thirty eight patient with AS and 38 age and sex-matched healthy controls were enrolled. All patients with AS fulfilled the modified New York criteria for ankylosing spondylitis. We collected demographic and clinical data including; disease duration, form of AS, presence of coxitis and previous or current shoulder pain.
AS activity was assessed by the bath ankylosing spondylitis disease activity index (BASDAI), and we used the bath ankylosing spondylitis function index (BASFI) to evaluate function. Each patient and control subject provided informed written consent to participate in this study at baseline and the study received approval from the ethic committee of biomedical research of Faculty of Medicine and Pharmacy of Rabat.
Bilateral US examination of shoulders, for each patient and control subject, was realized by a rheumatologist with 2 years of experience in musculoskeletal US, assisted by a rheumatologist with 7 years of experience in musculoskeletal US. Toshiba Xario equipment with a 14-MHz linear array transducer was used.
We realized standarized sections to scan each tendon of cuff rotator in both longitudinal and transverse planes as following: 1) neutral position of shoulder, elbow flexed 90, scaning of biceps tendon between the greater and less tuberosities in ventral transverse and longitudinal planes for visualisation of the tendon and detection of minute fluid accumulations and detection of tenosynovitis, 2) during maximal external rotation with the elbow flexed 90 and fixed on the iliac crest, scaning of the subscapularis tendon with visualisation of its enthese on the lesser tuberosity 3) supraspinatus was evaluated along its long and short-axis while the patient was placing the arm posteriorly and the palmar side of the hand on the superior aspect of the iliac wing, its insertion on the greater tuberosity was examined 4) the patient placing the hand on the opposite shoulder, infraspinatus was scanned with its enthese on the greater tuberosity. Blood flow was examined at the entheseal sites using power Doppler mode with a pulse repetition frequency of 750 Hz and a power Doppler gain of 60 dB.
In B mode, we explored cuff rotator tendon morphology to detect tendinopathy by searching partial or full-thickness tears and intra-tendinous calcifications. Presence of tenosynovitis of the long biceps tendon was assumed when the echogenic tendon was surrounded by a hypoechogenic band on the transverse and longitudinal sections. At tendon insertion, we searched for the following abnormal findings, and any one of them was considered as a feature of enthesitis; tendon thickening at the level of bony attachment, enthesophytes, bony erosion and presence of Doppler signal at the level of bony attachment. While assessing rotator cuff, subacromial or subdeltoid bursitis was searched.
Gleno-humeral and acromio-clavicular joints were also assessed as following: dorsal transverse section through the infraspinous fossa laterally below the scapular spine and axillary longitudinal section, for detection of synovitis, synovial proliferation, and erosion of the humeral head; and ventral transverse section over the acromio-clavicular joint.
Continuous variables were expressed by median ± standard deviation or median (interquartile ranges), and categorical variables as number (percentage). Comparison of categorical variables between patients and control subjects were done by chi-square or Fisher's exact test. Continuous variables were compared by t-student test. Furthermore, we used chi-square test to compare the frequency of enthesitis between subgroups in patient group, these subgroups were defined functions of AS subtypes.
Thereafter, we performed a logistic regression to determine predictive factors for enthesitis in AS patients; firstly univariate logistic regression were done, and the remaining factors (P < 0.05) were entered into a final global multivariate logistic regression model, so multivariate analysis were secondly performed.
Results were considered significant for p < 0.05, and Confidence intervals (CI) were computed at the 95% level. A computer software package (SPSS, version 13; SPSS, Chicago, IL) was used to perform all statistical calculations.
Methods
Thirty eight patient with AS and 38 age and sex-matched healthy controls were enrolled. All patients with AS fulfilled the modified New York criteria for ankylosing spondylitis. We collected demographic and clinical data including; disease duration, form of AS, presence of coxitis and previous or current shoulder pain.
AS activity was assessed by the bath ankylosing spondylitis disease activity index (BASDAI), and we used the bath ankylosing spondylitis function index (BASFI) to evaluate function. Each patient and control subject provided informed written consent to participate in this study at baseline and the study received approval from the ethic committee of biomedical research of Faculty of Medicine and Pharmacy of Rabat.
Ultrasound
Bilateral US examination of shoulders, for each patient and control subject, was realized by a rheumatologist with 2 years of experience in musculoskeletal US, assisted by a rheumatologist with 7 years of experience in musculoskeletal US. Toshiba Xario equipment with a 14-MHz linear array transducer was used.
We realized standarized sections to scan each tendon of cuff rotator in both longitudinal and transverse planes as following: 1) neutral position of shoulder, elbow flexed 90, scaning of biceps tendon between the greater and less tuberosities in ventral transverse and longitudinal planes for visualisation of the tendon and detection of minute fluid accumulations and detection of tenosynovitis, 2) during maximal external rotation with the elbow flexed 90 and fixed on the iliac crest, scaning of the subscapularis tendon with visualisation of its enthese on the lesser tuberosity 3) supraspinatus was evaluated along its long and short-axis while the patient was placing the arm posteriorly and the palmar side of the hand on the superior aspect of the iliac wing, its insertion on the greater tuberosity was examined 4) the patient placing the hand on the opposite shoulder, infraspinatus was scanned with its enthese on the greater tuberosity. Blood flow was examined at the entheseal sites using power Doppler mode with a pulse repetition frequency of 750 Hz and a power Doppler gain of 60 dB.
In B mode, we explored cuff rotator tendon morphology to detect tendinopathy by searching partial or full-thickness tears and intra-tendinous calcifications. Presence of tenosynovitis of the long biceps tendon was assumed when the echogenic tendon was surrounded by a hypoechogenic band on the transverse and longitudinal sections. At tendon insertion, we searched for the following abnormal findings, and any one of them was considered as a feature of enthesitis; tendon thickening at the level of bony attachment, enthesophytes, bony erosion and presence of Doppler signal at the level of bony attachment. While assessing rotator cuff, subacromial or subdeltoid bursitis was searched.
Gleno-humeral and acromio-clavicular joints were also assessed as following: dorsal transverse section through the infraspinous fossa laterally below the scapular spine and axillary longitudinal section, for detection of synovitis, synovial proliferation, and erosion of the humeral head; and ventral transverse section over the acromio-clavicular joint.
Statistical Analysis
Continuous variables were expressed by median ± standard deviation or median (interquartile ranges), and categorical variables as number (percentage). Comparison of categorical variables between patients and control subjects were done by chi-square or Fisher's exact test. Continuous variables were compared by t-student test. Furthermore, we used chi-square test to compare the frequency of enthesitis between subgroups in patient group, these subgroups were defined functions of AS subtypes.
Thereafter, we performed a logistic regression to determine predictive factors for enthesitis in AS patients; firstly univariate logistic regression were done, and the remaining factors (P < 0.05) were entered into a final global multivariate logistic regression model, so multivariate analysis were secondly performed.
Results were considered significant for p < 0.05, and Confidence intervals (CI) were computed at the 95% level. A computer software package (SPSS, version 13; SPSS, Chicago, IL) was used to perform all statistical calculations.
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