OBJECTIVES: Clinical studies investigating shoulder complaints have found that active exercises and passive manipulation are not equally effective treatments, perhaps because active and passive movements align the individual shoulder girdle components differently. This study sought to investigate whether a significant difference exists in scapulohumeral rhythm of the healthy shoulder when the humerus is elevated actively or passively. STUDY DESIGN: Both shoulders of 10 healthy volunteers (9 men; mean age 50 yrs) were studied using an electromagnetic coordinate system to locate the position of the scapula relative to the humerus and trunk. Scapula position in three dimensions was recorded at 10 degrees intervals during active and passive humeral elevation in the coronal plane between 10 degrees and 50 degrees. Each shoulder was measured three times. RESULTS: Analysis of variance showed that in all three planes of scapula movement (lateral rotation, backward tip, and retraction) the components of variance attributable to the differences in active and passive movement were less than 5%. CONCLUSIONS: During humeral elevation between 10 degrees and 50 degrees no significant difference exists between active and passive shoulder complex motion in healthy individuals. These findings may help to explain why passive manipulation is an effective treatment for shoulder complaints.
OBJECTIVES: Clinical studies investigating shoulder complaints have found that active exercises and passive manipulation are not equally effective treatments, perhaps because active and passive movements align the individual shoulder girdle components differently. This study sought to investigate whether a significant difference exists in scapulohumeral rhythm of the healthy shoulder when the humerus is elevated actively or passively. STUDY DESIGN: Both shoulders of 10 healthy volunteers (9 men; mean age 50 yrs) were studied using an electromagnetic coordinate system to locate the position of the scapula relative to the humerus and trunk. Scapula position in three dimensions was recorded at 10 degrees intervals during active and passive humeral elevation in the coronal plane between 10 degrees and 50 degrees. Each shoulder was measured three times. RESULTS: Analysis of variance showed that in all three planes of scapula movement (lateral rotation, backward tip, and retraction) the components of variance attributable to the differences in active and passive movement were less than 5%. CONCLUSIONS: During humeral elevation between 10 degrees and 50 degrees no significant difference exists between active and passive shoulder complex motion in healthy individuals. These findings may help to explain why passive manipulation is an effective treatment for shoulder complaints.