Temporal Variations in a Modified Neer Impingement Test Can Confound Clinical Interpretation

High variability in the time required for patients to have substantial pain relief after Neer-type subacromial impingement tests might help explain conflicting data regarding their effectiveness in guiding treatment and predicting surgical outcomes. To focus on quantifying temporal variability associated with a modified (local anesthetic and corticosteroid) impingement test, we hypothesized that substantial pain relief (greater than 75% reduction) can occur beyond the 10-minute interval many clinicians use for determining results of this test. Fourteen females and 12 males (mean age, 55.6 years) who received subacromial injections for Stage II impingement completed 10-cm visual analog scales for pain at 5, 10, 20, 30, and 40 minutes postinjection. There were 11 patients (42%) who attained at least 75% relief by 10 minutes compared with nine (35%) additional patients who subsequently attained 75% relief after 10 minutes. On average, 75% reduction in pain did not occur until after 30 minutes postinjection. Data analysis also revealed two groups: (1) rapid responders with greater than 50% pain relief by 10 minutes; and (2) delayed responders with greater than 50% pain relief after 10 minutes. Assessing pain at 10 minutes for a Neer-type impingement test can fail to accurately determine a positive test in a substantial percentage of patients.