Hughes, Richard E.

Normative data are useful for assessing isometric shoulder strength in patients with bilateral shoulder abnormalities. The purpose of this study was to develop a normative database for shoulder strength in the clinically relevant positions and movements. Twenty combinations of exertions and postures—including flexion, extension, abduction, adduction, internal rotation, and external rotation—were tested for both the dominant and nondominant sides. Strength was measured isometrically using a modified Cybex II dynamometer. The cross-sectional study design included 120 subjects (60 women and 60 men) ranging in age from 20 to 78 years from southern Minnesota. Tables of normative strength data were constructed. Multivariate analyses were performed to assess the effect of age, sex, and weight on strength. Age was negatively associated with all strength measures, and weight was positively associated with them. Men were stronger than women when controlling for age and weight. Statistically significant differences between dominant and nondominant shoulders were found for only some of the strength measures taken. These normal data will be useful to the clinician, as they permit a standard against which to compare shoulder strength.

The goal of this study was to visualize the supraspinatus tendon three-dimensionally using fast spin-echo (FSE) MRI and validate the accuracy of measuring the dimensions of the supraspinatus tendon based on 3D reconstructed images. Nine cadaver shoulders (51–84 y/o, mean 70.0 y/o) were imaged at conventional T2-weighted spin-echo (CSE), gradient echo (GRE), and 3D T2-weighted FSE sequences. Each "object" of the supraspinatus muscle, tendon and scapula was three-dimensionally reconstructed using ANALYZE™ image data processing software. The FSE images revealed significantly higher contrast of the tendon and contrast-to-noise ratios of the fat-to-tendon and fat-to-muscle. The length of the anterior, middle, and posterior portions of the tendon were measured in two ways: (1) from the three-dimensional reconstructed images, and (2) directly from the cadaver specimen using calipers. No statistically significant differences were found between the ANALYZE™ and caliper measurements using a paired t-test for the anterior (p = 0.55), middle (p = 0.57) and posterior (p = 0.44) portions of the supraspinatus. The 3D FSE sequence exhibits higher spatial resolution, spends shorter acquisition time, and constructs a voxel data set. These advantages can prevent blurring artifacts when imaging the supraspinatus tendon of a human body. Tendon length measurements derived from three-dimensional reconstructions using ANALYZE™ were found to be good estimates of actual tendon length. Therefore, the combination of FSE sequence and 3D image data processing provides a method for noninvasive quantitative analysis of supraspinatus tendon morphology. The results lay the groundwork for future quantitative studies of cuff pathology.

Reduced shoulder endurance in rotator cuff tear patients has been observed clinically. A simple and inexpensive shoulder endurance test protocol was developed. This study reports the test-retest reliability of the protocol. Twenty healthy volunteers without a history of shoulder pathology participated in the study. Each subject was tested twice, each on a separate day. Test-retest correlation coefficients of the arm endurance times were 0.59 and 0.60 for the dominant and nondominant sides, respectively. The protocol appears promising for assessing shoulder function.