Ultrasonic measurement of the anterior translation in the shoulder joint

A new method for measuring the anterior translation in the shoulder joint b y dynamic ultrasound was evaluated. We placed a 3.5-MHz transducer on the s houlder anteriorly. By using 3 bony landmarks, we then measured the anterio r translation of the humeral head with a force of 90 N applied posteriorly We performed such measurements in 20 subjects with healthy shoulders and in 20 patients with unilateral shoulder instability. There was a mean transla tion of 1.9 mm in healthy shoulders and 4.9 mm in unstable shoulders (P < . 01) The mean difference between the 2 sides in subjects with normal shoulde rs was 0.7 mm, whereas the mean difference in patients with instability was 2.8 mm (P < .01). The normal shoulders were examined by 2 examiners to det ermine the degree to which different examiners' measurements might vary. Al though one examiner recorded higher values than the other, the new method s eems suitable for measuring increased laxity in unstable shoulders.