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December 16, 2011

Collateral Damage

Rounding Up the Usual Suspects: Rotator Cuff Tears

by Corey Dawkins and Ben Lindbergh

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Baseball pitchers and rotator cuff problems seem to go hand-in-hand despite the rotator cuff being much smaller than other muscles about the shoulder and upper back. The four small muscles that make up the rotator cuff are vital to the shoulder’s health and to a pitcher’s playing career. In fact, at one time, rotator cuff surgery was considered a career-ending sentence. That isn’t the case any longer, but it still hasn’t reached the level of relative certainty of ACL surgery or even Tommy John surgery. Without a healthy rotator cuff, a significant cascade effect culminating in shoulder instability and/or tears of the labrum is possible, if not inevitable. In today’s episode of Collateral Damage, we will be looking at the rotator cuff and ways of treating it in all of their complexity.

Anatomy
The rotator cuff is made up of four muscles that attach at different sites on the scapula, a.k.a. the shoulder blade. These four muscles are known as the supraspinatus, infraspinatus, teres minor, and subscapularis. The main function of the rotator cuff as a group is to ensure that the humeral head stays centralized in the glenoid fossa. This cannot be emphasized enough. Two of the muscles—infraspinatus and teres minor—assist in external rotation of the shoulder, while the subscapularis is the only rotator cuff muscle whose role is as an internal rotator. The supraspinatus also assists in abduction, especially early in the motion. Without that rotator cuff, the humeral head would slide all over the place and tear up the labrum, articular cartilage, and other tendons in the area.
 

Source Orthoassociates.com
 

Source Orthoassociates.com

The pictures above provide a good idea of the positioning of the rotator cuff and its insertions. We can see in both the overhead view and the lateral view that the tendons of the rotator cuff overlap to form a common tendon that encapsulates the front, back, and top of the humeral head. This structure allows the humeral head to be positioned more precisely and more efficiently than if there were four different insertions.

Mechanism of Injury
The rotator cuff is obviously a very important piece of anatomy, since we hear about it all the time when pitching injuries arise. Rotator cuff inflammation, partial rotator cuff tears, full-thickness rotator cuff tears—the list goes on and on. Entire books have been written on the biomechanics of the shoulder and the injuries associated with them in overhead athletes, but we’ll try to sum them up here.

Overhead athletes have unique mechanisms and unique disorders from which other athletes or patients do not suffer. MLB pitchers who suffered rotator cuff tears that required surgery had lower BMIs and were more likely to be All-Stars than a control group of pitchers who did not develop rotator cuff problems, an intriguing finding. (SurenaNamdari, MDetal. 2011) In our own database, this does tease itself out with rotator cuff surgeries to Bartolo Colon, Mark Mulder, and Pedro Martinez, to name a few.

As we mentioned above, the primary role of the rotator cuff in pitchers is to keep the head of the humerus centralized in the glenoid fossa. During the pitching motion, humeral angular velocities can reach 7000 degrees/second, easily the highest voluntary velocity measured. The rotator cuff is most at risk during the late-cocking and deceleration phases, and the two most common methods of rotator cuff injury in pitchers are internal impingement and tensile failure.

Tensile failure is the easiest to understand. During deceleration of the arm, the rotator cuff must contract eccentrically—contract while being stretched—to do its job of keeping the humeral head in the right place. At that point, the arm is moving at such a high velocity that the individual muscle fibers often reach the point of tensile failure. Even though these fibers can repair themselves, if pitching continues over a sufficiently long period after enough fibers have failed or become severely fatigued, partial- or full-thickness tears of the rotator cuff can occur.

Another common mechanism of injury is impingement, which in professional pitchers is more likely to be internal than subacromial. In our first article of this series, we discussed internal impingement in great detail. To summarize, during the late cocking position of abduction, external rotation, and extension, the postero-superior edge of the glenoid labrum can get pinched between the rotator cuff and the humeral head. This pinching of the labrum and posterior glenoid can lead to undersurface tears of the infraspinatus tendon and posterior fibers of the supraspinatus tendon. In fact, most tears in throwers are located in the region between the posterior mid supraspinatus to the mid infraspinatus.

Injury Findings
Clinicians must always ensure that the neck is not the cause of the symptoms. Herniated discs can cause inflammation surrounding the nerves that travel to the shoulder and down the arm. Once the neck is cleared of any injuries, the clinician turns to the shoulder.

Initially, the pitcher will often complain of difficulty getting loose or fatiguing earlier than usual. As his condition progresses, inflammation will set in, likely leading to pain in the late cocking and deceleration phases. Rotator cuff tears will also lead to pain associated with raising of the arm, even before reaching the late cocking phase. Depending on the location of the inflammation or tear, there can be tenderness in the front or back of the shoulder. Strength testing can reveal pain/weakness, and an MRI is a more revealing diagnostic than an x-ray. If the physician feels there is a good chance of a torn labrum as well, an MRI with dye injected into the shoulder may be ordered.

Non-operative Treatment
No one wants to have surgery on their rotator cuff, so everyone tries conservative management first, except in rare cases, i.e. full-thickness tears or when there are other more significant injuries present as well. Treatment involves a multi-faceted approach to decrease pain and restore normal motion, strength, and mechanics. An initial period of rest follows, in which there is no throwing and treatment is focused on physical therapy and modalities to decrease pain. A corticosteroid injection may be considered to decrease the inflammation (not to “pump you up,” as Arnold would say). Prescription strength oral anti-inflammatory medication may also be used. The Thrower’s Ten program is often initiated after the patient is pain-free, focusing on specific exercises to strengthen the shoulder. A throwing program can be resumed once the pitcher reattains the appropriate strength and range of motion.

Surgical Treatment
Isolated rotator cuff tears in a pitcher are rare and are almost always associated with at least a mild form of labrum fraying or degenerative changes in the shoulder. There are two main methods of repair: open and arthroscopic. Open repair is suggested for massive rotator cuff tears but is generally avoided for overhead athletes because of the length of rehabilitation and typical outcomes.

One of the main reasons why arthroscopic repairs are preferred is that pain levels following arthroscopic repairs are generally much lower than in open repairs. In order to get the greatest amount of posterior exposure, the patient is placed in what is called the “beach chair position,” leaning back about 20 degrees from vertical, with a folded sheet on his back on the edge of the scapula closest to the spine. Prior to any incisions, the shoulder is examined under anesthesia to identify any other coexisting conditions. After the examination under anesthesia is complete, three or four arthroscopic portals are then introduced for the surgical equipment.

The surgeon visualizes as much of the joint as possible in order to ensure the repair is performed in the proper sequence. After visualizing the glenohumeral joint, the surgeon evaluates the subacromial space and, if necessary, performs a decompression wherein a portion of the acromion is shaved away. This decreases the risk of any future subacromial impingement and other possible impediments to a successful return to pitching.

The bone is roughened at the point where the rotator cuff inserts to promote some bleeding. Sutures are passed through the torn portion of the rotator cuff tendons with precise care, since the majority of failed rotator cuff repairs are due to the sutures being pulled through the tendon. Anchors into the humeral head are inserted before the sutures are pulled taught. The sutures are then passed to the anchors and locked in place. Additional sutures may be placed to supplement the primary repair.

The single row technique, wherein a row of anchors is placed on the greater tuberosity of the humerus lateral to the anatomic insertion of the rotator cuff, has traditionally been used. More recently, a double row technique has been used more often in order to ensure an improved functional outcome for pitchers. In the double row technique, one row of anchors is placed at the edge of the joint, and the other is placed lateral to the rotator cuff insertion. For an example of an arthroscopic repair on both a model and a real patient, see the video below:

This video from YouTube shows the double row technique, which provides a more anatomic repair and is the preferred arthroscopic technique for pitchers.

Open rotator cuff repairs have been performed for some time but are falling out of favor for overhead athletes unless the rotator cuff tears are large or complex. They require the surgeon to make the incision and detach the deltoid muscle from the acromioclavicular joint to improve the access and better visualize the torn rotator cuff tendons. Once the surgeon reaches the level of the rotator cuff, repair is similar to other methods and will attempt to get as close to an anatomic alignment and insertion as possible.

For an example of an open repair, see this video on YouTube. (Warning—some footage may be considered graphic).

Surgical Rehabilitation
Rehabilitation differs depending on the procedure used. For the first six weeks, active range of motion is not allowed, which permits the tendons to heal properly. The patient wears an abduction sling, essentially a sling with a bumper that keeps the arm away from the body. Passive range of motion is very gradually progressed in order to prevent contractures. Motions that would stress the repair, such as putting the arm behind the back, are not allowed at all, even in passive motion. General conditioning activities like walking and possibly stationary bike riding are allowed if tolerated well. Working in a pool is not allowed until at least two to three weeks after surgery.

Starting around week six, use of the sling can be discontinued. Gentle active motion is allowed; around weeks five to six, full passive motion is also permitted. In the next several weeks leading up to around the three-month mark, active range of motion is increased until the player regains full motion. More aggressive shoulder strengthening begins at this time. Sports-related rehabilitation is still avoided until five months out from surgery, with throwing not beginning until six months have passed. The throwing program is progressed very slowly, and pitching off a mound does not occur until about nine months after surgery. Maximal improvement before returning to play generally takes at least one year.

Rehabilitation from the rare open rotator cuff repair takes significantly longer, but many of the benchmarks, such as strengthening and returning to throwing, are approximately the same. It is not unheard of for this approach to take two years to attain maximal improvement levels.

Summary
Rotator cuff injuries worry all baseball players but can be particularly devastating to pitchers. At this point, the success rate for returning to an equivalent or improved level of production does not compare to that of Tommy John surgery. With the emphasis being placed on recognizing the signs and symptoms of internal impingement, one of the factors in partial (greater than 50 percent) thickness or full thickness rotator cuff tears may be managed. The attention placed on pitch counts may also help avoid major rotator cuff injury. Yet, regardless of any preventative measure taken, there will always be rotator cuff injuries. In the future, improved surgical techniques will decrease recovery time significantly, allowing us to milk a few more years out of the next Pedro’s arm.

Corey Dawkins is an author of Baseball Prospectus. 
Click here to see Corey's other articles. You can contact Corey by clicking here
Ben Lindbergh is an author of Baseball Prospectus. 
Click here to see Ben's other articles. You can contact Ben by clicking here

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