Anatomy of the Shoulder
The shoulder joint is made up of two main bones, the scapula
(shoulder blade) and humerus; two joints, glenohumeral and
acromioclavicular; and two articulations, scapulothoracic and
acromiohumeral. The head of the humerus contacts the glenoid of the
scapula to form the glenohumeral joint. The acromion is the part of
the scapula that extends forward and forms a roof at the top of the
shoulder joint. Under the acromion, there are a number of soft
tissue structures - ligaments, tendon and bursae. These structures
act to provide stability at the shoulder joint. The rotator cuff
muscle tendons pass under the acromion and attach at the humerus
and act to move the arm out to the side (abduction), and rotate the
arm inwards (internal rotation) and outwards (external rotation).
The long head of the biceps tendon attaches to the scapula at the
coracoid process. This muscle works to stabilize the shoulder and
bend the elbow. Bursae are fluid filled sacs, which allow smooth
movement and cushioning between muscles in the shoulder joint.
Together, these joints, muscles, ligaments, tendons and bursae
allow smooth and full motion of the healthy shoulder.
What is impingement?
Impingement occurs when the structures under the acromion (roof
of the shoulder blade) are being compressed. Often times, the bursa
or rotator cuff tendon are involved. This can be the result of
repeated overhead activity, weakness in the rotator cuff muscles,
over activation of the deltoid muscle, decreased joint capsule
mobility, decreased length of the anterior shoulder muscles and
even poor posture. Often, the result is shoulder pain and limited
mobility.
What are the typical signs and symptoms of
impingement?
- Mild pain in the front of the shoulder that is present with
activity and rest, which may radiate to the side of the arm
- Sudden pain with lifting and reaching movements
- Pain with overhead activities and reaching behind the back
- There may be stiffness and pain when the arm is both lifted
from a resting position and also when the arm is lowered
- Pain at night
- Loss of strength and motion
Can physical therapy help?
Recent randomized, controlled clinical trials support physical
therapy as an effective intervention in the treatment of shoulder
impingement. A physical therapist will complete a thorough
evaluation of postural alignment, shoulder range of motion,
strength, joint mobility, muscle length and flexibility. The
findings of the evaluation will allow the physical therapist to
develop an individualized plan to address the greatest deficits and
determine the appropriate treatment to return a patient to full
pain-free function.