I recently was reading JOSPT on clinical guidelines for adhesive capsulitis and was excited to see them mention the influence of the subscapularis on frozen shoulder. The Subscapularis (subscap) is a very influential shoulder muscle, playing a large part in internal rotation and elevation; specifically motor control of the humeral head (assists in gliding humeral head inferiorly with elevation). The subscap typically refers pain into the posterior shoulder along with scapular pain and pain down the triceps. It also has a band of pain at the wrist which can easily be misdiagnosed as carpal tunnel syndrome. Patients may have writ pain and believe it is not correlated to their shoulder pain (do not let this misdirect your clinical judgement).
Subscap pathology can occur, like most trigger points, by muscle overload and overuse. This can occur in repetitive overuse in sports or yard/house work. Further, long periods of immobilization or non-use secondary to pain can lead to impairments along with prolonged loading of a forward shoulder which can occur from sleeping on one’s involved side.
So how do we know if the subscap is involved, well here are a few things I look for. The more symptoms you see, the more likely the subscap is a big player. Here's my
'Subscap Clinical Prediction Rule':
1. increased loss of ER at 45degr versus loss of ER at 90degr of ABD. ie: 20degr of ER at 45degr ABD and 45degr ER at 90degr ABD may indicate subscap restriction.
subscapular surgical releases suggest that subscapularis muscle flexibility deficits are responsible for glenohumeral external rotation limitations in the lower ranges of
abduction. A contrasting clinical and cadaver finding in where glenohumeral external rotation becomes more limited as the humerus moves toward 90° of abduction, suggestive of glenohumeral capsular restrictions. Thus, a patient who has greater limitation of glenohumeral external rotation at 45° of abduction, when compared to the available external rotation at 90° of abduction, may have a subscapularis muscle flexibility deficit rather than a glenohumeral capsular restriction”. Therefore soft tissue interventions will be more effective for the subscap when increased tightness is seen in the 0 to 45 degree range. Conversely, joint mobs will be indicated with more of a capsular pattern restriction. And in fact, the research had good success with soft tissue techniques for ER with this criteria alone (they improved ER by an average of 16 degrees after one treatment).
2. posterior shoulder pain. with the referral pattern mentioned above
3. poor scapulohumeral rhythm at 45-90degr; specifically superior humeral glide. A patient who has poor shoulder rhythm is clearly not activating their subscap (and infra) well enough. This can be seen in the over and mis-diagnosed “frozen shoulder”.
Intervention:
1. subscap TrP release with Dry needling. (There’s also a subscap release that I'm not too familiar with nor would I enjoy having my fingers in their armpit for 8 minutes)
2. Followed by PNF contract-relax external rotation at 45-90degr ABD, than max pain-free ER hold, than PNF repeated contractions. perform 3-5 times.
The best part is when you “release” the subscap you get some really awesome results! LIke going from 45degr ABD to 155degr ABD after 15 minutes of manual.
