Shoulder problems in children with BPBP

SHOULDER DYSPLASIA OR GLENOHUMERAL DYSPLASIA

What is internal rotation contracture of the shoulder (IRCS) and shoulder dysplasia or glenohumeral dysplasia (GHD)?

• The IRCS is the fixed position of the shoulder in internal rotation, which cannot be rotated out.
   
• The GHD is a deformity of the shoulder joint, characterized by a posterior dislocation of the humeral head and a smaller size.
   

Some shoulder concepts

The shoulder joint is a "ball-hole" type. The humeral head is spherical, and is situated in the hollow of the scapula called the glenoid cavity. Being a ball joint, it allows movements in the shoulder in many directions, including rotational movements (Figure 1).

 

Figure 1. Shoulder joint. The ball of the humerus (1) is articulated with a hole
(2, glenoid cavity) of the scapula. Being a ball joint, it allows movements in many
directions, including rotational momevents.

Rotational motion of the shoulder. Subscapularis muscle and external rotator muscles (Figure 2). There are many muscles in the shoulder. The subscapularis muscle is a deep muscle, located on the anterior aspect of the scapula and is the most important for shoulder internal rotation. In the back of the scapula, lie the external rotator muscles that rotate the shoulder outward.

Figure 2. Anterior view of chest and shoulder. The subscapularis is ahead of the scapula,
and does shoulder internal rotation. (1) scapula (2) subscapularis muscle (3) humeral head

Figure 3. Posterior view of the chest and shoulder. External rotator muscles
are located behind the scapula, and perform shoulder external rotation.
(1) scapula (2) humeral head (3) external rotator muscles.

 

Figure 4. Cross section at the level of both shoulders. The subscapularis muscle (3) is ahead
of the scapula and does shoulder internal rotation. The external rotator muscles (4)
are placed behind the scapula and perform shoulder external rotation. (1) humeral head (2) scapula.
 

Measuring of the movement of external rotation. Passive external rotation exercises of the shoulder. The way to measure shoulder external rotation and to do passive exercises, is with the arm close to the chest and the elbow flexed 90 °. Stabilize the scapula against the chest with one hand, and with the other hand rotate out the forearm and hand (Figure 5).

Figure 5. One hand stabilizes the scapula, while the other hand rotates the upper limb
outward, keeping the arm close to the chest and the elbow at a right angle.
These exercises are essential in children with BPBP, in order to prevent shoulder anomalies.
 

Why IRCS occurs?

The internal rotation contracture is due to a shortening of the subscapularis muscle.

Experimental studies conducted by Dr Soldado show that the shortening of the subscapularis muscle is due to a lack of cyclic stretching caused by paralysis of the external rotator muscles of the shoulder. The external rotators generally require a longer time to regain the ability to contract. By not doing shoulder external rotation, the subscapularis muscle is not stretched, thus causing a lesser length growth of the muscle.

The position held in internal rotation causes the humeral head to move back and gradually gets out of its hole (glenoid cavity) (Figure 6). As it dislocates, the joint will deform more and more, the worse the movement or function of the limb and the worse are the results of treatment. If IRCS is left untreated, deformity of the shoulder occurs progressively at an early age; at 3 months old. Without treatment, at 2 years old, the deformities are severe.
 

 
Figure 6. MRI. Cross section at the shoulders, showing the dislocation of the humeral head
backwards (arrow on the left); compare with the other side. If untreated, subluxation (dislocation)
progresses, thus causing shoulder motion impairment. (1) humeral head (2) scapula.