SPORTS MEDICINE  ·  SURGERY OF THE KNEE  ·  SURGERY OF THE SHOULDER  

Impingement Syndrome Print

Irritation and injury of the rotator cuff are the most common shoulder problems encountered the sports medicine community. While these problems can occur after a specific traumatic injury, they are more commonly associated with repetitive use. "Wear and tear" over time leads to the development of rotator cuff symptoms in a large portion of the population as they enter their 40's and 50's.

 

Anatomy

The rotator cuff is composed of the supraspinatus, infraspinatus, subscapularis, and teres minor muscle tendons. (Figure 1). A tendon is the attachment of  muscle to bone. The tendon of the long head of the biceps muscle is also closely associated with the rotator cuff. The muscles of the rotator cuff originate from the shoulder blade and attach the to ball of the shoulder.

When the rotator cuff tears, its tendon usually pulls away from the ball of the shoulder (humeral head). After a tear, the tendon often retracts and leaves a large hole which uncovers the ball of the shoulder (Figure 2).

Impingement Syndrome, Dr. Allen F. Anderson, Nashville, Orthopaedic Sports Medicine, Figure 2

Figure 2 Figure

 

A portion of the shoulder blade lies directly over the rotator cuff. This structure, known as the acromion, creates a very small space in which the rotator cuff passes to attach to the humeral head. In addition, there is a ligament (coracoacromial ligament) which passes from the acromion to another portion of the shoulder blade (the coracoid) and further reduces the amount of space available for the rotator cuff to pass to the humeral head. As we shall see, abnormalities of the acromion and coracoacromial ligament are thought to cause compression of the rotator cuff and to be associated with rotator cuff inflammation and tearing.

The space between the undersurface of the acromion and the rotator cuff is known as the subacromial bursa. The term "bursitis" is commonly used to describe inflammation of this area.

Bursitis is a term which can be thought of as synonymous with early rotator cuff inflammation. In medical terms, the phrase "subacromial impingement" is also used to describe early inflammation of the rotator cuff with associated bursitis. This term has evolved from the belief that the rotator cuff impinges or hits on the undersurface of the acromion when the arm is elevated (Fig. 3).

shoulder, impingement syndrome, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 4 shoulder, impingement syndrome, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 5

Figure 3

This arthroscopic view shows fraying of the acromion (large arrow) and bursitis (small arrow)

                              Figure 4

 Fraying of the rotator cuff that occurs  in association with an impingement syndrome.

Classically, many authors have believed that there is an area of poor blood supply in the rotator cuff close to its insertion on the humeral head. This would help to explain the fact that most rotator cuff tears tend to occur less than an inch from the attachment onto the ball of the shoulder. However, recent studies have challenged this theory. Rotator cuff tears may be partial or complete. A small partial thickness tear is demonstrated in Figure 5A-B, a small full-thickness tear in Figure 6, a large tear in Figure 7, and absence of the rotator cuff inFigure 8.

 

Impingement Syndrome, Dr. Allen F. Anderson, Nashville, Orthopaedic Sports Medicine, Figure 6

shoulder, impingement syndrome, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 7

Figure 5A

Figure 5B


shoulder, impingement syndrome, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 8 shoulder, impingement syndrome, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 9
Figure 6 Figure 7


shoulder, impingement syndrome, Dr. Allen F. Anderson, nashville, orthopaedic surgery, sports medicine, figure 10
Figure 8

 

 

 

 
© Allen F. Anderson, M.D. 2017