Shoulder Centration Posterior Cuff Eccentrics




Assessment: 

An essential part of evaluating the shoulder is determining ROM / length / extensibility / ability to eccentrically load the posterior rotator cuff and glenohumeral joint capsule. Evaluating internal rotation in multiple planes and horizontal adduction upon a stabilized scapula will help us determine which parts of the posterior cuff and/or GHJ capsule is restricted. Note that the presence of posterior capsular contracture is likely much less common than previously reported. Indeed a review of the literature will identify the most common assessment of the posterior capsule to be ROM. ROM, active or passive, cannot isolate the capsule from the rotator cuff. The only way to differentiate posterior capsule restriction or contracture from the posterior cuff is via glenohumeral glide, which will rarely demonstrate restriction (aside from adhesive capsulitis effecting the posterior capsule, which is uncommon). And to be honest, in terms of the approach to manual therapy or rehabilitation, in the presence of restriction it probably doesn’t matter whether it is rotator cuff or capsule in most patients. It will matter when there is a restriction in ROM in the presence of posterior capsular laxity or instability. The posterior cuff will often become tight (read: neurological tightness) and may become fibrotic in the presence of posterior capsular laxity or instability; this will definitely change your approach to manual therapy and rehabilitation. 

Back to the assessment… so, the assessment is to specifically look at ROM in internal rotation at 90 degrees elevation in the scapular plane and again at 90 degrees flexion, then horizontal adduction. Standard parameters for these assessments are:

IR in Scapular Plane: 70 degrees (observing the ‘180 degree’ rule)
IR at 90 degrees flexion: 40 (30 degrees less than IR in Scapular Plane)
Horizontal Adduction: 30 degrees
Note: Not included in this video is the medial rotation extension test. It is no less important and will test a totally different part of the rotator cuff and capsule, namely, the posterior to posterior superior capsule and rotator cuff, SGHL and CHL.

Intervention

DNS 5 month Side Support: 

Preface: For those unfamiliar with postural ontogenesis and developmental kinesiology, I should clarify the language used in “5 month side support”. DNS or Dynamic Neuromuscular Stabilization is a strategy of rehabilitation based on postural ontogenesis and developmental kinesiology. “5 months” refers to the posture that a baby can ideally achieve by 5 months. At 5 months an ideally developing baby can roll from supine to the side. They are not yet able to raise up onto the elbow, but, they can support on the side with the support zones being down side lateral border of scapular toward acromium, posterior shoulder toward medial epicondyle of the elbow and the down side posterior to lateral gluteal fascia / hip and lateral condyle of the femur. Like this:

For more information on Dynamic Neuromuscular Stabilization please refer to the Prague School web-site, www.rehabps.com, which has numerous articles and studies that describes the approach and a few of the studies supporting its concepts. Clare Frank’s article HERE (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3578435/)  is a nice one to review the concepts behind the strategy.

The reason the 5 month side support position is preferred and considered an ideal starting point for this exercise is because it promotes ideal patterns and loading of the shoulder complexThe ability to eccentrically load the posterior cuff is directly proportional to the ability to stabilize the scapula on the thorax. If the position of the humerus is determined by either closed chain function or the hand having a predetermined path of motion in open chain function, and the scapula moves toward the posterior humerus via medial rotation of the scapula, this will limit lengthening or loading the posterior cuff eccentrically. Ideal kinesiological patterns aside this position is also more comfortable for the patient. 

Set Up

Position the lower extremity with knees and hips in semi-flexion. Holding true to DNS concepts the lower extremity position in this video is differentiated. However, it is not mandatory that you be super specific with leg position as long as they feel well supported (i.e. having the top leg lay on the bottom, in an undifferentiated position, is acceptable for the ‘motor challenged’ individual or just to reduce the complexity of the exercise on introduction).

Ask the patient to move the shoulder caudally, such that they are resting on the lateral posterior edge of the scapulatoward acromion. Done correctly the patient will not be supporting on the humerus in the starting position. The head should be supported in a neutral position. The shoulder is in 90 degrees flexion with the GHJ in external rotation with forearm resting on table. 

Note: if you start with the GHJ in internal rotation and there is true restriction of the posterior cuff this will result in the scapula moving into protraction, anterior tilt and elevation, decentrating the scapulothoracic and glenohumeral complex and diminishing the effect of the exercise.

Technique #1

1. Have the patient engage their shoulder into the table by slightly lifting their body away from the table. This will activate those muscles that create upward rotation, protraction and support of the thorax on the scapula.

2. Internally rotate their GHJ to neutral with the elbow partially pronated. 

3. Load the pattern – the pattern is reaching and turning over the downside shoulder and hipThere is an “up-righting” mechanism involved here; the development of this pattern is toward prone or up onto the elbow. In other words, don’t allow the patient to sink into the shoulder. This will facilitate centration and scapulothoracic stability / motor control, and appropriate loading of the posterior cuff. Done correctly the patient will feel a lot of work in the posterior cuff and importantly, the loading is eccentric in nature all the while facilitating ideal motor control / stability of the scapula and trunk.

Note: eccentric loading of the posterior cuff while facilitating stability of trunk and scapula will “release the brakes” and allow tone of the posterior cuff to reduce and ROM increase.

Generally I will load the position between 10-30 seconds and repeat 2-6 times for total time under tension of 1 min to 2 min, then re-assess. Assuming success (based on re-assessment) I would go back to the technique, asking the patient to perform the exercise again, with me guiding them as needed to review the technique in preparation for home exercise. Note that if the patients shoulder is reactive / irritable we can reduce loading time and reduce threat bymoving in and out of the loaded, pain free position for repetitions (say 10). 

Technique #2 & 3

Demonstrating the progression of position and options to increase exercise variability for the shoulder, but also address dysfunction of the thorax and hip. Progressing to a month side support position, up on the elbow-forearm, we demonstrate an exercise to promote elongation and rotation of the thorax. Then we progress to an exercise that challenges the downside hip, eccentrically loading the gluteal muscles and hip rotators – this is a great exercise for FAI or anterior hip pain as well as loading the gluteal muscles / hip rotators eccentrically (think lumbopelvic-hip stability or gluteal tendonopathy).

For a quick video demonstrating the 5 month and 7 month side support positions, including transitions, check out this video: https://www.youtube.com/watch?v=IK8WbrMyTng