ULTRASONOGRAPHIC EVALUATION OF ANTERIOR SHOULDER TRANSLATION IN NORMAL SHOULDERS

The purpose of this study was to assess the technique of ultrasonographic evaluation of anterior shoulder translation from an anterior approach. Anterior translation in the right shoulders of 23 volunteers was evaluated using ultrasound with a 10 MHz, 6 cm wide linear transducer. A translatory force of 90 Newtons (N) was used to translate the humeral head in the adduction and internal rotation position (Position 1), while 60 N was used in the more clinically relevant position of 90° abduction and external rotation position (Position 2). The overall intraobserver coefficients of variation ranged from 0–13% (mean 3.8 ± 2.5%) for examiner 1 and 0.5–20.9% (mean 5.1 ± 3.9%) for examiner 2. The overall interobserver variation ranged from 0–29.8% (mean 9.3 ± 7.3%). The anterior translation in Position 1 ranged from –2.6 to 12.9 mm (mean 2.1 ± 3.1 mm) for examiner I and from −4.1 to 4.7 mm (mean 1.1 ± 2.2 mm) for examiner II. The anterior translation in Position 2 ranged from −3.3 to 3.7 mm (mean 0.3 ± 1.9 mm) for examiner I and from −8.3 mm to 4.5 mm (mean −0.7 ± 2.6 mm) for examiner II. The intraclass correlation coefficients (r) for the measured anterior translation between the 2 examiners for the 2 positions were 0.029 and −0.058 respectively. The interobserver coefficient of variation remains excessive and there was poor agreement in the measured anterior translation. The finding of negative values in the measured anterior translation despite translatory force raises further concerns about the prospective clinical use of this technique at the present moment.