Swimmer’s shoulder

Swimmer’s shoulder

Weisnthal, Larry M

Most swim coaches and orthopedic physicians do not really understand swimmer’s shoulder. It is important to understand the anatomy of the shoulder as well as the techniques and methods for avoiding injury.

This is the first of a taco-part series on swimmer’s shoulder:

Shoulder injuries in swimming are most often caused by impingement. Impingement is worst at 90 degrees (mid-recovery and mid-pull through) and 180 degrees of elevation (position of the long forward reach). It is made worse by internal rotation of the arm.

The keys to shoulder-friendly swimming technique are to avoid internal rotation during recovery and pullthrough, to reduce the extent and duration of forward reach, and to delay the application of pull forces until the leading hand has descended well below the position of long forward reach.

Injuries to the shoulder are the cause of considerable lost training time and many shortened swimming careers. Numerous studies have documented that between 25 to 35 percent of high level competitive swimmers experience interfering shoulder pain. Also, 60 to 75 percent of these swimmers will have a serious shoulder problem at some time during their careers. In addition to lost training time, these injuries are the cause of considerable medical expense, emotional distress and abandoned careers.

Given the magnitude of this problem, it is obvious that one of the major goals of both coach and swimmer would be to avoid or minimize these injuries. Coaches and swimmers alike should have the same level of knowledge of techniques and training methods for injury avoidance as they have for techniques and methods for swimming fast. Sadly, it is obvious that even the greatest coaches often have little understanding of mechanisms of injury as well as techniques and methods for avoiding injury.

Conversely, orthopedic surgeons and other medical professionals have a clear understanding of mechanisms of injury, but too often have an incomplete understanding of the nuances of swimming technique which contribute to this injury.

The situation could be greatly improved if swim coaches had a better understanding of anatomy and if orthopedic surgeons had a better understanding of swimming technique.

Try raising your arms over your head. Now, move them around. Better yet, mimic crawl and butterfly, straight overhead and reaching for the ceiling. Strive for maximum forward (upward) “extension” (actually forward flexion/abduction, in proper anatomic terms) as you rotate your hips. Can you feel the stress and strain?

The human upper extremity was not designed nor did it evolve to do movements like this. In contrast to running (or even throwing), competitive swimming is a completely unnatural activity for which humans did not evolve and to which it is often impossible to adapt.

Simplified Anatomy

The head of the humerus is joined to the shoulder blade (scapula) at a very small indentation in the scapula called the glenoid.

There is a thin rim of cartilage around the glenoid called the labrum. This sometimes tears, which can contribute to pain and cause a clicking sound. Tom cartilage doesn’t heal.

The humerus is joined to the scapula by a sheath of dense ligaments known as the joint capsule.

Over the joint capsule inserts a sheath of tendons collectively called the rotator cuff. This is a coalescence of the tendons of four different muscles which originate from various positions on the scapula and insert on the proximal humerus to rotate it. These muscles are called the teres major and minor, subscapularis and supraspinatus. It is the last of these muscles and its tendon which causes most of the trouble.

The supraspinatus originates in a groove on the top surface of the scapula. It is a skinny muscle which runs along the top of the scapula, then ends in a tendon which eventually interdigitates with the other tendons of the other three muscles which collectively form the rotator cuff.

The function of the supraspinatus is to move the arm away from the body. (In anatomic parlance, the “arm” is what lay people call the “upper arm,” as opposed to the forearm, which is below the elbow.) The supraspinatus is responsible for the first 15 degrees of this “away” motion (properly called abduction), until the much larger/stronger deltoid muscle is in place to take over and abduct it the rest of the way.

The problem with the suprapinatus (besides being a small muscle doing a big job) is that the tendon has to travel underneath an outcropping of scapular bone called the acromion before it can attach to the humerus. If the arm had been designed to work overhead, the acromion would have been entirely redesigned with respect to position and shape.

But the problem is that the acromion forms a roof (I call it a “carport”) over the supraspinatus tendon, which does a dandy job of protecting it from injury (e.g., a blow from a club or when some oaf claps you on the shoulder, saying “How ’bout them Dawgs!”). It is also a rigid structure which grinds into the supraspinatus tendon when the latter is elevated during overhead arm activities (like swimming).

Another structure which can pinch the supraspinatus tendon during overhead motion is the coracoacromial ligament, which runs from the coracoid process to the tip of the acromion. There is controversy over what part of the swimmers’ problem is caused by the coracoacromial ligament and what part is caused by the acromion. In most cases, probably both contribute to the problem.

Sometimes there is a little fluidfilled cushion (similar to an air bag) which comes into play. This is called a bursa, and it serves to cushion the top of the rotator cuff tendon sheath when it bangs into the acromial “carport.” With chronic rubbing and banging, the bursa itself can become inflamed and painful. This condition is called bursitis.

The shoulder joint (actually the joint between the humerus and the scapula) is designed for motion and not stability, in contrast with the hip. The hip is a true ball-and-socket joint, where the ball of the femur is securely cradled in a deep socket of pelvic bone called the acetabulum. It is plenty strong and plenty stable, but it is obvious that the shoulder has a much greater range of motion than the hip.

Rather than resembling a ball and socket, the shoulder is much more analogous to a golf ball on a golf tee. The bony structures themselves provide absolutely no stability. The stability comes only from two places:

The ligamentous joint capsule, which connects the head of the humerus to the scapula; and

The rotator cuff itself, which is, as described, a sheath of tendons inserting all around the head of the humerus to elevate and rotate it.

Another anatomic factoid: all bones have growth plates, or epiphyses. This is not relevant to us older guys and gals, but it is crucially relevant to teenage swimmers. There is a common condition in land athletes (soccer players, basketball players, runners) called Osgood-Schlatter’s syndrome.

This occurs when the inferior patellar tendon inserts in the top/front of the tibia right on top of a growth plate (epiphysis). The traction and motion of the tendon against the epiphysis causes inflammation and pain which can be very severe. The treatment is rest and letting the bone mature so that the epiphysis closes and the problem cures itself.

What is not always (or even often) appreciated (even by expert sports orthopedists who tend to take care of college football players more than swimmers) is that there is a very important growth plate right at the top edge of the acromion (the “carport” of the scapula).

This growth plate is the last growth plate in the body to close. Teenage girls stop growing usually by age 15 to 16. Most of their growth plates close about this time. A big exception is the acromial growth plate, which does not close often until the college years and even into the 20s. Therefore, teenage swimmers can get a condition analogous to Osgood-Schlatter’s disease. Traction of the deltoid tendons and repetitive up-and-down motion of the shoulder blade can lead to inflammation of the acromial growth plate.

Lastly, the supraspinatus (superior rotator cuff) tendon has a very poor blood supply just a thin arteriole, which is easily kinked off/wrung out, interrupting the blood supply. This wring-out effect is prominent during the “back end” of freestyle and fly, which is why the Australian/Carew technique of an early exit is preferable to an exaggerated push back to “finish” the stroke. The fact that both Kieren Perkins and Franziska Van Almsick (among many others) swim this way proves that it is not a fatal detriment to performance.

A wring-out effect can also occur during very innocent times, such as sleeping (i.e., either sleeping on the affected side, by direct pressure of the bed scrunching the top of the shoulder, or sleeping on the non-affected side and letting the arm of the affected side drop down onto the bed, which again wrings out the supraspinatus tendon). The swimmer should either sleep on the back (preferably without a pillow) or on the non-affected side, keeping the affected arm elevated during the night on a pillow.

Principal Causes of

Shoulder Pain

The main cause of shoulder pain is the impingement of the superior rotator cuff (supraspinatus) tendon against the “carport” of the acromion. This is exacerbated by the following conditions:

An elongated, misshapen or slightly downsloping acromion. These anomalies greatly increase the pressure against the tendon as the arm is elevated and are present in 30 to 35 percent of the population. These kids and grown-ups are guaranteed to have trouble with swimming unless major stroke and training modifications are made.

Hyperlaxity of the joint capsule. In principle, if the joint capsule is very “flexible,” “lax,” or “mobile,” this can make impingement much worse and can cause impingement even in the case of a “normal” or Type 1 acromion which doesn’t slope downward.

The reason for this is that there will then be a much greater upward and downward “travel” of the head of the humerus during repetitive arm motion. If the head of the humerus is free to migrate upward, it will then squeeze the supraspinatus tendon against the acromial “carport.”

I believe this problem, however, is greatly overdiagnosed by sports orthopedists, who are used to treating inflexible football players rather than flexible swimmers. They look at a swimmer and say, “You are hypermobile and need to do a lot of exercises, and if that doesn’t work, you need a surgical procedure to tighten up your joint capsule.”

This is an operation which has been commonly used on elite swimmers in recent years.

Improper technique. The definition of “improper”-in the context of rotator cuff impingement, which is the most common and serious cause of swimmer’s shoulder-includes many of the beloved “long forward” techniques currently being taught today. I think that this intense emphasis on the “long forward” is a time bomb which is already beginning to produce otherwise avoidable problems in the swimming community.

Overtraining. This condition as a cause of shoulder pain is overrated. For example, neither Janet Evans nor many other notable distance swimmers ever had problems with shoulder injury. This is because of their favorable anatomy and very shoulderfriendly technique.

Other causes of shoulder pain include:

Growth plate inflammation (epiphysitis);

Bursitis and other changes associated with chronic impingement, such as formation of adhesions (scar tissue) and calcium deposits;

Glenoid labrum tears; and

Thoracic outlet syndrome (a fortunately rare condition, requiring expert diagnosis, which will not be discussed here).

Diagnosis and Principles

It is obvious that the first thing you need is a diagnosis. Which of the preceding causes is contributing to your problem? I think that every top level swimmer with shoulder pain should immediately get an evaluation by an experienced orthopedist and should seriously consider getting an MRI.

The MRI doesn’t subject the swimmer to any radiation. However, he or she should probably also get a baseline set of at least three X-ray views as well. They show the shape and structure of the acromion (which can be difficult to visualize in teenage girls on plain X-rays, as the structure can be thin and even cartilaginous, rather than bone). They also show the relationship of the acromion to the head of the humerus, presence or absence of epiphysitis, and presence or absence of tendinitis.

It is also helpful to know the swimmer’s history and to view an above-water and underwater video of the swimmer’s stroke. Once you understand the enemy, you can devise a battle plan.

Here are the principles:

If there is an elongated, overly convex or downsloping acromion, and the swimmer aspires to compete at an elite level, he or she should probably undergo arthroscopic surgery. Once the problem is evident by the emergence of pain and has been documented by an MRI or radiographs, I think this type of acromion (remember, we are talking potentially up to 30 to 35 percent of all swimmers) is incompatible in most cases with pain-free training at elite performance levels.

The surgery to “fix” this is performed arthroscopically. Basically, the orthopedist shaves the underside of the coracoacromial ligament to increase the space for the rotator cuff tendons and to make the undersurface smooth. The orthopedist then transects (“releases”) the coracoacromial ligament at its attachment to the acromion. This is necessary to expose the end of the acromial bone. Then the end of the acromion is shaved off, and the undersurface is smoothed with a little buzz saw.

If there are any adhesions/scar tissue, or calcifications, or fragments of tom glenoid labrum (the rim of cartilage around the “golf tee” socket, or glenoid), these are removed as well.

The transected ligment reattaches by itself and heals very rapidly, and virtually all of the surgical healing takes place within a month. So, the surgery (in cases where the problem is “caught early”) is almost trivial when done by ari expert.

A further advantage of the surgery is that the orthopedist can do a detailed “examination under anesthesia” to document conclusively whether or not true instability is present. By that, I mean, “Is it actually possible to dislocate the shoulder joint by applying extreme forces?” If the joint is actually dislocatable, then a joint capsule tightening procedure may be helpful. Otherwise, I would leave the joint capsule alone.

The capsule tightening procedure has become very popular for football players who chronically dislocate their shoulders (e.g., Jerry Rice of the San Francisco 49ers). This operation has been performed on many elite college swimmers. I would not recommend this operation for a high school (or younger) swimmer except in a very extreme case, where the shoulder was actually dislocatable under anesthesia and there was otherwise a clinical picture compatible with impingement resulting from instability which did not respond to a rigorous exercise/strengthening program.

There are several problems with the capsular tightening procedure (called the “Oratec” or radiowave heating/ protein denaturing procedure):

Post-op recovery and rehabilitation are a bigger deal.

There may be limitation of motion, which is bad for swimming performance.

The joint capsule will almost certainly stretch out again over time.

Whether or not the lifelong integrity of the joint capsule will be preserved is entirely unknown.

Also, studies on cadaver shoulders (quite gruesome research, actually) show that impingement forces are eliminated by bone reshaping (acromioplasty), while they are only reduced and usually not eliminated by strengthening the tendon forces.

Next issue: short of surgery; ar irt addition to sagely, wa can a surd coach do?

About the Author

Larry M. Weisenthal, M.D., Ph.D., is a physician, researcher, Masters swimmer and swim parent from Huntington Beach, Calif.

Copyright Sports Publications, Inc. Apr-Jun 2000

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