PROXIMITY OF ROTATOR CUFF TENDONS TO POTENTIAL IMPINGING
STRUCTURES DURING CLINICAL IMPINGEMENT TESTS
Seely KT, Beranek KA, Burandt AR, Blom KM, Sarkar S, Braman JP, Ludewig PM
Program in Physical Therapy and Department of Orthopaedic Surgery, University of
Minnesota, Minneapolis, MN
This study was approved by the University of MN Institutional Review Board. All
subjects provided informed consent for participation.
This study was supported in part by the National Institutes of Health, NICHD/NCMRR,
K01 HD042491.
ABSTRACT (Limited to 300 Words):
BACKGROUND AND PURPOSE: The two main types of impingement, subacromial and
internal, may benefit from differential treatment approaches. Several clinical
impingement tests exist, however little is known about which structures a positive test
may implicate. The purpose of this study was to determine the proximity of rotator cuff
tendons to potential impinging structures during clinical impingement tests.
SUBJECT(S): 16 subjects were tested (9 males, 7 females; 50% symptomatic).
Average age for asymptomatic subjects was 30, and for symptomatic was 37.
METHODS AND MATERIALS: CT scans were used to generate subject specific
anatomical models of bone edges and tendon insertion footprints. Position data for the
Neer, Hawkins-Kennedy, and posterior impingement tests and scapular plane abduction
were captured using electromagnetic sensors rigidly attached using bone pins.
Anatomical models were moved into test positions according to collected data. Threedimensional distances from subscapularis, infraspinatus, and supraspinatus tendons to
the acromion, coracoacromial ligament, and glenoid were calculated.
ANALYSES: Two-way ANOVA’s determined differences between tests and groups for
each pair of structures (i.e. supraspinatus to glenoid).
RESULTS: For subacromial impingement, the Hawkins-Kennedy test demonstrated
greatest proximity to the coracoacromial arch; however, the distance was no less than
that for 90° of scapular plane abduction. For internal impingement, there was no test
that had a significantly smaller distance than that at 120° scapular plane abduction. The
subscapularis tendon never came closer than 10mm to any external structure during any
test position. There were no differences between groups.
CONCLUSIONS: No test consistently demonstrates greater propensity for impingement
of any type.
IMPLICATIONS: Proximity of impinging structures should be considered when using
clinical impingement tests to diagnose rotator cuff tendon pathology. For specific
tendons, some tests create greater impingement risk than others.