Glenohumeral-Rotation-Deficits In High School, College, And Professional Baseball Pitchers With And Without An Mucl Injury

Abstract

PURPOSE: To assess if a glenohumeral-internal-rotation-(IR)-Loss (GIRLoss), a glenohumeral-external-rotation-(ER)-gain (GERGain) or a total-rotational-motion-(TRM)-deficit (TRMD) predict medial ulnar-collateral-ligament (MUCL) injury-risk among high-school (HS), college (COLL), and professional (PRO) baseball-pitchers with-and-without-MUCL-injury. It was hypothesized that pitchers with MUCL injury would have ˃GIRLoss and TRMD compared to pitchers without MUCL injury, with no differences in IR, ER, TRM, GIRLoss, GERGain, and TRMD. METHODS: Two-hundred-sixteen-male HS, COLL, and PRO pitchers were equally divided into MUCL-injury-group (n=108) and control-group (n=108) without MUCL injury. Controlgroup was matched with the MUCL-injury-group according to number, level &age. Bilateral shoulder passive IR/ER were measured and GIRLoss, GERGain, TRM, and TRMD calculated. A two-way-analysis-of-variance (p<0.05) was employed to assess shoulder-rotational-differences among the two-groups and three-pitching-levels. RESULTS: Compared to control-group, MUCL-injured-group had ˃GIRLoss (21°±14°-versus-13°±8°;p<0.001), GERGain (14°±9°-versus-10°±9°;p=0.004), and TRMD (7°±13°-versus3°±9°;p=0.008). For all pitching levels ~60% of subjects in MUCL-injury-group had GIRLoss>18°, compared to ~30% of subjects in control-group. ~60% of subjects in MUCL-injury-group had TRMD >5°, compared to 50% of subjects in control group. No differences were observed among HS, COLL, and PRO pitchers for GIRLoss (16°±12°,17°±11°,19°±13°, respectively; p=0.131), GERGain (11°±9°,11°±10°,13°±10°, respectively; p=0.171), TRMD (5°±11°,6°±11°,5°±14°,respectively; p=0.711), throwing shoulder ER (111°±10°,111°±11°,113°±9°,respectively; p=0.427), throwing shoulder IR (50°±11°,49°±11°,48°±10°, respectively; p=0.121),& throwing shoulder TRM (162°±14°,160°±15°,161°±14°,respectively;p=0.770). CONCLUSIONS: Greater GIRLoss, GERGain, and TRMD in MUCL-injured-pitchers compared to uninjured-pitchers implies these variables may be related to increased-MUCL-injury-risk, especially since GIRLoss>18° and TRMD>5° demonstrate an increased MUCL injury risk. Shoulder rotational motion and deficits do not vary among HS, COLL, and PRO levels of pitchers.