Acromio-humeral distance variation measured by ultrasonography and its association with the outcome of rehabilitation for shoulder impingement syndrome.

OBJECTIVE: First, to validate an ultrasonographic measure of the acromio-humeral distance (AHD); second, to compare the AHD variation during active abduction in patients with shoulder impingement syndrome (SIS) and healthy subjects; and third, to evaluate the relationship between functional status and AHD variations before and after rehabilitation in SIS subjects.
DESIGN: This study has 3 components: (1) a reliability study, (2) a case-control study, and (3) a preliminary pretreatment/posttreatment clinical trial.
SETTING: Primary care hospital setting. PARTICIPANTS: Seven SIS patients and 13 healthy subjects.
INTERVENTIONS: For the clinical trial, the SIS subjects participated in 12 sessions of a rehabilitation program over 4 weeks. MAIN OUTCOME MEASURES: First, intraclass correlation coefficient for interobserver reliability; second, AHD measured at 0 degrees, 45 degrees, and 60 degrees of active abduction; and third, Western Ontario Rotator Cuff Index.
RESULTS: Intraclass correlation coefficient for interobserver reliability ranged from 0.86 to 0.92 for the 3 shoulder positions. A significant reduction of the AHD was found within groups between rest and active abduction (P < 0.05). Comparison of AHD between groups was not statistically different (P = 0.06; beta < 0.80). In pre-post rehabilitation analysis, improvement of the Western Ontario Rotator Cuff Index score was positively correlated to the reduction of the AHD narrowing as the arm was abducted (r = 0.86; P = 0.01).
CONCLUSIONS: The ultrasound measure of AHD is reliable and sensitive. Although a distinct pattern of AHD variation in SIS patients could not be confirmed, a strong positive relationship was found between the reduction of AHD narrowing and functional improvement following rehabilitation. Ultrasound measurement of AHD might help identify SIS patients who will benefit from rehabilitation.