Scapular kinematics and impairment features for classifying patients with subacromial impingement syndrome

Subacromial impingement syndrome (SAIS), which is associated with pain and a loss of function, has a high occurrence in the physically active population. Not all patients respond positively to treatment. Classifying patients can improve decision-making. The scapular kinematic and clinical impairments can aid in classifying the patients who are more likely to respond to physical therapy treatment. Thirty-three subjects (males, 20–33 years) presenting SAIS were studied to determine altered scapular kinematics and clinical impairments. Three measurements were collected: (1) three-dimensional scapular kinematics during performing functional tasks; (2) impairment outcomes of range of motion and muscle force; and (3) self-reported measurements of pain, satisfaction, and function. All patients received 6-week (2 times per week) physical therapy treatment. Improvement with treatment was determined using the Global Rating of Change Scale. Scapular kinematics and clinical impairments were first identified by t-test in predicting improvement and then combined into a multivariate prediction method. A prediction method with three variables (Flexilevel Scale of Shoulder Function score < 41, muscle power of serratus anterior < 27.4% body weight, degree of scapular internal rotation at 30° shoulder elevation during descending arm phase in unloaded condition < 0.7°) were identified. It appears that scapular kinematics and impairment features can be used to classify subjects with SAIS in addition to self-report. Prospective validation of the proposed prediction method requires further investigation.