Impingement of the rotator cuff

Shoulder overuse injuries in athletes often occur when they perform many repeated movements. The tendons of the muscles can also be injured if they become impinged between bones in the shoulder joint during certain movements, such as throwing.

Injury to rotator cuff tendons usually happens gradually. In the early stages, pain can actually be felt without the occurrence of any structural damage. In later stages the tendon tissue can become weaker. This is known as tendinosis, and it can ultimately result in the partial or complete rupture (tearing) of the tendon.

Tendinosis of the rotator cuff is very common among athletes in sports that involve a lot of movement with the arms raised above shoulder height. This activity places extreme demands on the shoulder. For example, a handball player at the elite level has on average 48 000 throws a season, while a professional swimmer completes 1.5 million strokes per arm! A study found that over 80% of professional handball players have tendinosis in the rotator cuff (shown on an MRI). The good news is that only a small percentage of these players had any pain or reduced function.

Impingement

Impingement is one of the most common causes of shoulder pain in the rotator cuff. It results from a tendon becoming pinched between the upper arm and the shoulder blade (scapula) in certain positions when the arm is raised.

There are two main types of impingement: subacromial impingement. This is when the arm is raised straight up above the head, and posterior impingement, which occurs when the arm is held all the way back in a throwing position.

Subacromial impingement

Subacromial impingement occurs in the so-called subacromial space between the head of the upper arm and the top of the shoulder blade where they make up the shoulder joint. The supraspinatus tendon (one of the rotator cuff muscles) is most often affected. In addition, other structures such as a fat pad (subacromial bursa) can also be affected. Given that several structures can be involved, we often refer to this as impingement syndrome.

Subacromial impingement syndrome can be caused by variations in shoulder anatomy, muscle tightness, a stretched joint capsule or due to a lack of stability from the muscles around the shoulder blade. A common and effective way to treat this is to use a individualised training program. If conservative treatment fails, surgery can be performed to increase the subacromial space. Subacromial impingement is most common among people aged above 45, but it can also occur in younger athletes.

Posterior impingement

Posterior impingement is common amongst athletes in sports where the main activity is above shoulder height.  The condition concerns the tendons of the infraspinatus and supraspinatus muscles and occurs when the shoulder is held all the way back in a throwing position (see picture below). Typically, athletes with posterior impingement experience pain in the back of the shoulder when in this position.

Posterior impingement can be caused by a lack of control and stability of the shoulder blade when throwing. Poor throwing technique can be a contributing factor.

Treatment and rehabilitation

The first step in treatment for almost all injuries of the rotator cuff is an individualised rehabilitation program. During rehabilitation, the athlete should be removed from the activity or sport that caused the injury. A physiotherapist should supervise the program and focus should be on specific factors such as:

• Mobility of the shoulder
• Strength and coordination of the rotator cuff
• Control of the shoulder blade
• Sport specific training (for example, in throwing sports strength and mobility of the hip, upper back, and shoulder are very crucial)

It is imperative that the load and demands on the shoulder are increased gradually so that the athlete can fully participate in the sport without experiencing pain. This approach is successful in the majority of cases, even when there is considerable structural damage to the tendon such as with a full thickness tear. It often takes up to 6 months of rehabilitation before any significant improvements are noticeable.

If conservative treatment is unsuccessful, surgery should be considered. However, surgery should not be viewed as a quick-fix solution. Recent research shows that around 25% of athletes in throwing sports don't return to sport following surgery to the rotator cuff, and only a small percentage of those who do return manage to do so at their pre-injury level of performance. Also, rehabilitation following surgery takes a long time. The average duration for a return to sport is 12 months.