PURPOSE: Subacromial impingement syndrome (SIS) is associated with low self-reported shoulder function, impairments in shoulder strength and range of motion (ROM), and pain. It is not known how the symptomatology associated with SIS is reflected in the choice of treatment. This study compares self-reported shoulder function, shoulder strength, ROM, and pain in patients with SIS considered candidates and non-candidates for subacromial decompression (SAD).

METHOD: Self-reported shoulder function (Q-DASH and SPADI), maximum isometric muscle strength in shoulder abduction (Abd-strength) and external rotation (ER-strength), active abduction ROM (Abd-ROM) and passive internal rotation ROM (IR-ROM) were measured in a consecutive cohort of patients with SIS referred to an orthopedic outpatient clinic. Additionally, pain during each test and pain levels during the last week were reported. Patients were categorized as candidates or non-candidates for SAD based on their consultation with an orthopedic specialist blinded to test results and self-reported shoulder function. All outcomes and age, gender, weight and duration of symptoms were compared using the unpaired t test or Mann-Whitney's U test as appropriate.

RESULTS: One-hundred and fifty-seven patients were included. 25 patients were candidates for SAD, while 132 were not. SAD candidates had significantly lower Abd-ROM (87° vs. 112°, p = 0.011, effect size = 0. 15) and IR-ROM (114° vs. 123°, p = 0.026, effect size = 0.58) additional to higher pain during test of Abd-strength (5.3 vs. 3.7, p = 0.02, effect size = 0.21). No other differences were found between the groups.

CONCLUSION: A decrease in abduction and internal rotation range of motion, and increased pain during maximal abduction strength effort are associated with being considered a candidate for subacromial decompression, while self-reported shoulder function, pain during the last week, and rotator cuff strength are not. As SAD candidates primarily differentiates from non-candidates by having more pronounced ROM deficits, it might be important to address ROM in pre- and postsurgical evaluations, but as the overall differences between the two groups seem minor, the relation between impairments and the choice of treatment needs further clarification.

LEVEL OF EVIDENCE: IV.