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I t p a y s t o b e A B M P C e r t i f i e d : w w w. a b m p . c o m / g o / c e r t i f i e d c e n t r a l 107 A joint's normal range of motion is defined by the connective tissue that binds it. The muscles, tendons, and fascia that cross a joint dictate approximately 80 percent of its stability with less than 20 percent entrusted to the ligaments. Ideal body balance requires some muscles to act as stabilizers and others to act as mobilizers, depending on the joint position and movement required for the particular task. A perfect balance of mobilizers and stabilizers results in optimal alignment, or joint centration. Think of joint centration like a wheel on a car. If the center of rotation is aligned with the center of the hub, it will deliver the most efficient performance. Conversely, when this neutral position becomes misaligned, the wheel spins incorrectly and can result in future mechanical problems. We commonly see this in upper-crossed syndrome (UCS) postures where slumped shoulders and a head-forward carriage lead to scapular winging and decentration of the glenohumeral joint (GHJ) (Image 1). Clinically, I've found this to be a common source of rotator cuff impingement, particularly involving the supraspinatus tendon. technique MYOSKELETAL ALIGNMENT TECHNIQUES The Wobbly Wheel Syndrome Addressing Joint Misalignment By Erik Dalton 1 A key function of the cuff muscles is to maintain the head of the humerus centrated within the glenoid cavity (concavity compression), and at the same time, impose an inferiorly directed force to the humeral head. In those with rounded shoulder postures, the glenoid fossa's mechanical axis of rotation is altered, causing the brain to activate muscles that are typically at rest, such as the upper trapezius, levator scapula, pectoralis minor, and deltoids. Postural overdevelopment of these muscles undermines rotator cuff stability, causing a deltoid shear that elevates and crams the humeral head into the top part of the glenoid fossa (Image 2). As the person abducts the arm to 90 degrees, the supraspinatus tendon abuts the acromion, causing micro-fraying, fibrosis, and possible tendinosis. Until upper- crossed postures and core instability issues are addressed, it does little good to myofascially lengthen the deltoids or offer home retraining exercises to strengthen the rotator cuff. In a debate earlier this year at Stanford Sports Medicine Center, Gray Cook, PT, stated, "When I say 'mobility first,' it is not simply an invitation 2 Deltoid shear Elevated and internally rotated humeral head As hypertonic deltoid muscles overpower the rotator cuff stabilizers, the humeral head is pulled into the top part of the glenoid fossa. Arm abduction causes supraspinatus tendon impingement (green circle) and possible tendinosis. Upper-crossed syndrome postures can lead to scapular winging and decentration of the glenohumeral joint. Glenoid fossa Supraspinatus tendon Subacromial bursa It pays to be ABMP Certified certified member Are you an ABMP Professional, Supporting, or Student Member? Upgrade and begin enjoying these Certified benefits today! 800-458-2267 Treat your clients to four new albums of music from At Peace Media To learn more, go to www.abmp.com/go/certifiedcentral Proudly display your membership with custom materials Learn and earn–oncology ebook, with free CE hours From 10-25% OFF products you need: BodyworkMall, Custom Craftworks, Earthlite, Oakworks, 3B Scientific, Primal Pictures Top listing on Massagetherapy.com: where clients look for therapists every day