Modified Impingement Test Can Predict the Level of Pain Reduction After Rotator Cuff Repair

Background: Most patients experience a significant reduction in pain after rotator cuff repair. However, there is currently no method to predict the level of pain reduction that each patient will experience. This report explores the usefulness of the modified impingement test for prognosis in cases of rotator cuff repair. Hypothesis: The amount of pain reduction after injection of lidocaine into the subacromial space preoperatively correlates with the level of pain reduction after rotator cuff repair. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: Preoperatively, a visual analog scale for pain was measured in 153 patients (59 males and 94 females) with a rotator cuff tear before and after injection of lidocaine into the subacromial space. Subsequently, rotator cuff repair was performed. At least 1 year after surgery, the visual analog scale for pain and satisfaction, Constant score, Simple Shoulder Test, American Shoulder and Elbow Surgeons (ASES) score, and University of California, Los Angeles shoulder rating scale were evaluated. Correlation analyses were performed between the change in visual analog scale after the modified impingement test and after surgery. Results: The amount of pain reduction after the modified impingement test was significantly related to improvement of pain postoperatively (P<.001), as measured using the visual analog scale for pain. The change in ASES score was also related to the amount of pain reduction after the modified impingement test (P=.001); however, the other tests showed no statistical significance (P>.05). Univariate regression analysis revealed that a 0.621-unit reduction in postoperative pain on the visual analog scale could be expected for each 1 unit (on a scale of 10) reduction in pain after lidocaine injection preoperatively. Conclusion: The amount of pain reduction after the modified impingement test preoperatively correlated with the improvement of pain after rotator cuff repair. This simple preoperative test could help patients understand the subjective level of pain reduction that they may experience after rotator cuff repair.