Scapulohumeral Rhythm: What is it?

        Scapulohumeral rhythm is defined as the ratio of movement between the scapula and humerus, and is focused on the relationship between the scapulothoracic and glenohumeral joint. For example, if a client has 150 degrees of shoulder ROM; 100 degrees of movement would be attributed to the glenohumeral joint, while 50 degrees would be the measure of scapulothoracic movement. Scapulohumeral humeral rhythm is clinically relevant because it establishes a healthy length tension relationship in the shoulder, allowing shoulder muscles to produce an optimal force during movement across the two joints. A deficit in scapulohumeral rhythm can lead to a decrease in muscle force and injuries sustained from joint weakness.

    

    With injury, the balance between the two joints can be disrupted; making movements essential to performing daily activities (ADL's) very difficult. If a client can not achieve full shoulder ROM, then they often will perform compensatory movements in order to help them move the affected extremity. These compensatory movements, such as the client laterally flexing their trunk while abducting the shoulder, can lead to skewed measurements and improper intervention plans. When measuring ROM in these cases, it is very important for the practitioner to give clear instructions for test positioning and carefully watch for any signs of pain. The practitioner must be able to palpate the correct bony landmarks to ensure that the client is properly moving through the range of motion being tested. With proper testing, a deficiency in scapulohumeral rhythm can be identified and a treatment plan will be implemented in order to restore a functional ROM necessary to meet the client's needs.