ASSESSMENT OF HUMERAL TORSION BY PALPATION IN BASEBALL PITCHERS: A VALIDATION STUDY.

ABSTRACT

BACKGROUND/PURPOSE: Greater humeral retroversion has been associated with shoulder and elbow injuries. Methods for measuring torsion include radiography, computed tomography (CT) and sonography (US) which may be costly or unavailable. A palpation method might be a reliable alternative to imaging techniques. The purpose of the current study was to examine the construct validity of the palpation technique for humeral torsion by (1) determining if a side-to-side difference in humeral torsion (HT) could be detected in a cohort of baseball pitchers using the palpation technique and (2) compare the side-to-side difference in HT obtained through the palpation method to the US method. HYPOTHESIS: Clinical assessment of HT by palpation is reliable and is as accurate as sonographic HT measurements among overhead athletes. METHODS: Twenty collegiate and high school pitchers were assessed. Bilateral shoulder passive external rotation (ER) and internal rotation (IR) range of motion were measured. Humeral torsion was indirectly measured using sonographic and palpatory methods. Paired t-tests were used to determine HT side-to-side difference measured by US versus palpation. Pearson's correlation coefficient (r) was used to determine the relationship between HT side-to-side difference detected by palpation and US, and relationships among IR and ER of the shoulder and HT side to-side difference measurements. RESULTS: There was significantly greater HT in dominant versus nondominant arm assessed by both palpation (5°±5, p=0.0004) and ultrasound (9°±11, p=0.0007). There was a positive correlation between both methods of HT measurement (r = 0.522, p=0.018). Palpation significantly underestimated HT as compared to US measurements (difference 4°±9, p=0.048). Difference in IR between shoulders correlated with HT measured by palpation (r=-0.651, p=0.002) and US (r=0.569, p=0.009). Increased ER in the dominant versus nondominant arm correlated with the side-to-side difference in HT measured by both palpation (r = 0.509, p=0.02) and US (r = 0.602, p=0.005). CONCLUSION: Greater HT on the dominant versus nondominant shoulder via palpation indicated this method can be used to assess HT in pitchers. HT assessed by palpation correlated with HT assessed by US. However, the magnitude of side-to-side difference in HT was smaller with palpation compared to US, and the two techniques should not be used interchangeably. Nevertheless, assessment of HT via palpation is a reliable and practical method and its use should be encouraged. LEVEL OF EVIDENCE Level 3, measurement study.