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By Jeffrey Burch, Certified Advanced Rolfer®
ABSTRACT This article describes aspects of shoulder-joint impingement including a definition of the condition, the contribution of anatomic variants, features of normal kinematics, and directions for assessment of some of these features. Awareness of these aspects can support a Rolfing® Structural Integration (SI) practitioner in providing superior individualized service to clients.
In general terms impingement in a joint refers to bony prominences approaching each other toward end range to an extent that they pinch a bursa, tendon, or cartilage. For any joint, impingement can occur with normal bony contours. Due to the inherent structure of normal bony contour, some joints are much more prone to impingement than others. The shoulder (glenohumeral) joint is particularly prone to impingement. The substantial variability in anatomy between individuals makes some people’s shoulders more prone to impingement than other people’s. The growth of osteophytes (bone spurs) presents new and idiosyncratic impingement opportunities.
For shoulder impingement the central osseous issue is collision of the greater tubercle of the humerus with the acromium process of the scapula during elevation of the arm. This impingement opportunity is greater in abduction than in forward elevation (flexion) and may be greatest in the scapular plane. The greater tubercle of the humerus is a prominence located on the posterolateral aspect of the proximal shaft of the humerus just below the humeral head. Adjacent and medial to this is the lesser tubercle. In between these two prominences lies the bicipital groove through which passes the tendon of the long head of the biceps brachii.
The greater tubercle serves as the insertion of the tendons of the supraspinatus, infraspinatus, and teres minor muscles, with the supraspinatus tendon most central at the apex of the tubercle. Repeated impingement of the bony prominences of the greater tubercle of the humerus and the acromium process may damage the supraspinatus tendon. Superficial to the rotator cuff tendons is the subacromial bursa. This bursa is also forcibly pinched during the impingement described. The resulting damage to the bursa leads to chronic bursa inflammation and fibrosity.
The altitude of the greater tubercle of the humerus is variable. Just as some people have more prominent noses or longer fingers than others, the height of the greater tubercle varies. A taller tubercle presents an earlier and/or more severe impingement opportunity. With a taller tubercle the angle of motion will be less.
The length of the acromium process is highly variable. In some people, the acromium processes extend much farther over than the head of the humerus than in other people. A longer acromium process presents an earlier and more severe impingement opportunity.
Humeral torsion describes the angular difference between the orientation of the proximal humeral head and the axis of the elbow at the distal humerus. The angle between these changes during development, much like the similar relationship between the distal and proximal ends of the tibia expressed as tibial torsion, will determine the amount of humeral torsion. Normal variability in adults has a range of more than 20°.
The arm may be abducted on the scapula in a frontal plane. The shoulder may be flexed (or forward elevated) in a sagittal plane or at any angle in between. When the shoulder is elevated in the plane in which the scapula lies, this is referred to as scapular plane movement. Scapular plane elevation of the humerus is often the plane in which shoulder impingement will occur at the least degree of elevation. The blade of the scapula does not lie fully in the frontal plane. The scapula, lying on the curve of the rib cage, sits at a variable angle as if protracted from where it would be if it were in the frontal plane.
When the shoulder is internally rotated, this brings the greater tubercle more anterior, more in line with the acromial process. Thus, impingement will occur significantly earlier during elevation of the arm when the humerus is internally rotated. Some tasks require that we have the arm internally rotated as we reach overhead. Avoiding or minimizing internal rotation of the arm when reaching overhead will reduce the likelihood of impingement.
As we elevate the arm the humerus rotates upward on the scapula. Normally the scapula also rotates in the same direction and at the same time so that the shoulder joint and the shoulder girdle share the motion of elevation of the arm. This shared movement reduces load on the individual joints and reduces the possibility of impingement. Many texts describe that the humerus can be elevated to a certain degree before the scapula must also upwardly rotate. This limit of independent humeral movement is where impingement has already occurred. That the humerus can rotate up to a certain degree before the scapula must also rotate has sometimes been misunderstood to mean that this sequence of glenohumeral movement, followed by scapular rotation, is the way we should move. This is incorrect. The two ideally share the movement from early in the movement process.
Humeral torsion is the angular relationship between a line through the lateral and medial condyles at the distal end of the humerus and the plane demarcating the base of the ball at the proximal end of the humerus. The base of the ball can be located in this way. Place the fingertips at the location where the glenohumeral joint line is thought to be. Have the client slowly make small slow internal and external rotations of the arm to feel for the actual joint line. Feeling the head of the humerus rotating on the scapula refines awareness of the location of the glenohumeral joint line.
Next, immediately distal to the perceived joint line, gently present a fingernail to the tissue aligned with the long axis of the tip of the fingernail more or less perpendicular to the scapular plane. Now use your other hand on the client’s elbow to slowly make small passive internal and external rotations of the humerus on the scapula. When the groove at the base of the humeral ball presents at the line of the fingernail, the fingernail will sink into this. This line defines the base of the ball. From here look down at the direction in which the elbow is pointing and the line between the elbow condyles perpendicular to that. The angular difference between the head of the humerus and the inter-condylar line is the degree of humeral torsion.
Ideally the ball of the humerus should rest in a neutral position in the glenoid fossa, neither internally nor externally rotated, and be freely mobile from there. If it is held internally or externally rotated this is an issue to address in the course of SI practice.
With the humeral head in a rotationally neutral position the direction in which the elbow points will vary considerably between individuals. Ida Rolf wanted everyone’s elbows pointing straight out to the side in a frontal plane. Her knowledge of biomechanics was slight. Lacking more detailed knowledge of the body she tended to apply cartesian coordinates to the body as ideals. For most people, elbows out to the side has the humerus held very much in internal rotation. If the arm is elevated from here shoulder impingement is likely.
The subscapularis muscle has more than one action. It is often described as an internal rotator of the shoulder. This rotary action comes into play when the arm is less elevated. As the humerus is elevated on the scapula, another action of the subscapularis comes into play. As the humerus is elevated contraction of the subscapularis draws the head of the humerus inferior with respect to the scapula, which substantially reduces the opportunity for shoulder joint impingement. This protective action of the subscapularis muscle is sometimes reduced or lost, with painful and damaging results for the shoulder. It is simple to assess for this motion. With the client standing or seated place two fingers on the top of the shoulder, one on the distal acromium, and the other on the head of
the humerus. Ask the client to raise his/ her arm in a scapular plane at a moderate pace. The head of the humerus should be felt to descend a few millimeters with respect to the scapula. Frequently the humerus will be felt not to descend.
If the subscapularis muscle is not active in depressing the humerus with respect to the scapula during elevation of the arm there are a number of possibilities. The client may have a severe tear of the subscapularis muscle or more often its tendon. The subscapularis muscle may be weak. There may simply be an unconscious movement habit that excludes this depressive action of the subscapularis muscle.
To begin to differentiate among these possibilities:
1. Inquire about any known history of rotator-cuff injury. Make medical referral for further investigation as appropriate.
2. With the client’s arm at his/her side and the elbow flexed, place your hand on the palmar side of the client’s wrist. In this position ask the client to push into your hand while holding his/her arm at his/her side, which internally rotates the arm. Note the apparent strength of the muscles used to do this. This test is not exclusive for the subscapularis but prominently includes the subscapularis. If this is weak but doing it produces no shoulder pain, giving exercise to strengthen this internal rotation movement may be useful. If moderate exercise produces subscapular and/or shoulder joint pain, again consider medical referral.
3. Offer an awareness exercise. As with the test above, place two of your fingers on the posterior portion of the shoulder joint to monitor the acromium and head of humerus. Invite the client to reach across and place two fingers of his/her other hand similarly on the same two bones more anteriorly. Ask the client to stay aware of this contact as s/he slowly starts to abduct the arm. Ask the client to note that the humerus does not descend on the scapula. Ask the client to lower and relax his/her arm. Now ask the client to gently begin to abduct the arm while searching for a way to gently glide the humerus inferior with respect to the scapula, while minimizing descent of the scapula with respect to the rib cage. With a little trial and error many people can do this. Suggest that the client practice this, and feel for the muscle deep under the scapula that is doing this. The biomechanical advantage of this movement pattern is great enough that the person’s nervous system usually learns this with a modest number of repetitions, and it becomes automatic.
Take-aways from this article include:
1. The scapula and the humerus should both lift together during all phases of arm elevation to share the load and minimize the opportunity for impingement.
2. Internal rotation of the humerus during elevation of the arm is to be avoided.
3. Humeral torsion is quite variable. Very few people’s elbows should point out to the side. For most people, ‘elbows out’ has the humerus in substantial internal rotation, which increases the likelihood of shoulder impingement. The head of the humerus resting centered in the glenoid fossa is a much more appropriate indicator of appropriate shoulder position than is olecranon process direction.
4. Some people’s arms will be able to lift higher than others. We are all built differently. In the goals for your work seek ease.
5. The action of the subscapularis muscle depressing the humerus on the scapula to protect against impingement is often not working well. This is often easy to retrain.
Jeffrey Burch was born in Eugene, Oregon in 1949. He grew up there except for part of his teen years lived in Munich, Germany. Jeffrey received bachelor degrees in biology and psychology, and a master’s degree in counseling from the University of Oregon. He was certified as a Rolfer in 1977 and completed his advanced Rolfing SI certification in 1990. Jeffrey studied cranial manipulation in three different schools, including with French etiopath Alain Gehin. Starting in 1998 he began studying visceral manipulation with Jean-Pierre Barral and his associates, completing the apprenticeship to teach visceral manipulation. Although no longer associated with the Barral Institute, Jeffrey has Barral’s permission to teach visceral manipulation. Having learned assessment and treatment methods in several osteopathically derived schools, Jeffrey then developed several new assessment and treatment methods that he now teaches, along with established methods.
In recent years he has developed original methods for assessing and releasing fibrosities in joint capsules, bursas, and tendon sheathes, which he is also beginning to teach. Jeffery is the founding editor of the IASI Yearbook; he contributes regularly to this Journal and elsewhere. He was for many years a member of the Dr. Ida Rolf Institute® Ethics Committee. He has served on the Dr. Ida Rolf Institute Board of Directors. For more information visit www.jeffreyburch.com.Aspects of Shoulder Impingement[:]
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