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April 1, 2013

Collateral Damage

Santana's Uphill Battle

by Corey Dawkins and Stephani Bee

It’s the final year of Johan Santana’s six-year, $137.5 million deal, but it looks like his Mets tenure has already concluded. Dr. David Altchek is scheduled to perform shoulder surgery on Santana tomorrow, after the lefty reportedly re-tore his anterior capsule during a spring bullpen session.

This will be the second time the former Cy Young winner has undergone the procedure. Santana first underwent the surgery back in 2010 and subsequently missed the entire 2011 season. When he returned, the southpaw was a shadow of his former self, posting a FRA+ of 102—better than average, but his worst numbers in over 10 years.

Santana has battled a bevvy of injuries during his time in New York, but this latest procedure appears to be uncharted territory.

Sports medicine has come a long way, lengthening the careers of players suffering from injuries that were once considered career-ending. Ulnar collateral ligament injuries and Tommy John surgery are practically commonplace now among pitchers; some have undergone two or three procedures while pitching at elite levels. Rotator cuff tears was death to a pitcher’s career in the 1980s, but pitchers are now returning the following year almost as if nothing happened. But despite these advances, capsular tears in the shoulder remain among the most troublesome.

Most pitchers have a hard time recovering from one capsular repair, and it appears that none have returned to pitch at the major-league level following a second procedure. There are several reasons it’s still difficult to recover from these procedures: the anatomy of the capsule, the demands of pitching, and the surgical procedures to repair the tear.

The shoulder capsule is a vital structure whose anatomy allows amazing functionality at elite levels but also makes it difficult to repair and return to the elite level. While it’s easier to imagine the capsule as a single, separate entity from the rest of the shoulder, it is not:

Shoulder Capsular Anatomy

  1. Superior Glenohumeral Ligament
  2. Middle Glenohumeral Ligament
  3. Anterior band of Inferior Glenohumeral Ligament
  4. Inferior Glenohumeral ligament complex / Axillary Pouch
  5. Posterior band of inferior glenohumeral ligament
  6. Posterior capsule
  7. Long head of Biceps tendon
  8. Supraspinatus, Infraspinatus, Teres minor tendons
  9. Subscapularis tendon
  10. Glenoid

Figure 1- Shoulder Capsule Anatomy

The capsule is actually made up of several ligaments and other structures that blend into the thickened tissue surrounding them. Not all the structures are always present. The superior glenohumeral ligament is present in over 90 percent of patients, while the middle glenohumeral ligament is not present in 15 to 25 percent of all shoulders. The inferior glenohumeral ligament (IGHL) is present in about 90 percent of shoulders, but it’s a discrete structure in only 75 percent of them.

The chief capsular restraint to shoulder instability in pitchers is the anterior band of the IGHL (#3), and it is the thickest of all the glenohumeral ligaments. The ligaments and structures appear to provide restriction throughout the range of motion, but that is not the case. Each structure provides some stability, but the IGHL provides stability chiefly at the extreme ranges of external rotation while at 90 degrees of abduction, such as the position while throwing a 90-plus mph baseball. This ligament and the nearby axillary pouch of the IGHL complex (#4) provide the majority of the static stability at the end of the cocking phase and start of the acceleration phase when the shoulder is at maximum external rotation in an abducted position.

This ligament is important to pitchers and is difficult to return from surgery due to the kinetics experienced during pitching. In non-overhead athletes, external rotation usually ends up maxing out near 90 degrees, but professional pitchers approach twice that amount. The greater the external rotation, the faster internal rotation can be produced, therefore increasing velocity. The ligament limits the external rotation enough to allow the shoulder to perform at the high level without becoming pathologic. Ligament failure allows greater translation of the humeral head, increasing instability and placing other structures at risk, such as the labrum and rotator cuff.

Surgical techniques vary depending on what is injured and where the capsule and ligaments are torn. There are essentially two methods of repair, arthroscopic and open. Arthroscopic surgery has been used much more extensively in recent year, but it has its limitations, including cases in which the tissue that requires repair is less than optimal. In these cases, an open repair is performed, where there is a much larger incision, similar to the one Santana already has.

In order to stabilize the shoulder anteriorly, a capsular shift or plication is often performed. Any associated labral tears and posterior capsule contracture are addressed. In non-overhead athletes, this works quite well, though a small loss of available range of motion is common. Overhead athletes though, need the extremes of motion in order to compete at a high level. Going from 180 degrees of external rotation to 160 degrees does not affect everyday activities that much, but it can lead to a significant loss of velocity relative to his peers.

Every shoulder is different, and even with the MRI scans, no one will know exactly what Santana’s shoulder is like until Dr. Altchek directly visualizes it under arthroscopy. The surgeon will first evaluate all the structures. Assuming there are no other major injuries, the surgeon will address the capsule tear itself. Traditionally, this has been performed with an open procedure in which the surgeon dissects down to the level of the subscapularis tendon, splitting the tendon to better visualize the relevant structures. The capsule is then split in a T-fashion before suture anchors are placed into the glenoid bone. The flaps are folded over each other to the proper tension before being sutured in place (Figures 2 and 3).

Figure 2: Open Anchor Insertion Right Shoulder Capsular Closure Right Shoulder

Figure 3: Completed Open Capsular Repair Right Shoulder

Arthroscopic capsular plication is similar, although the techniques are slightly different. Instruments are introduced through arthroscopic portals and suture anchors are placed. A specialized tool is used to pierce the capsule, and it is twisted to provide the appropriate amount of tension before suturing. An example can be seen in this animation.

For baseball players and other overhead athletes who wish to return to competition, arthroscopic surgery is usually indicated. Loss of motion is a more common complication with open procedures, but it greatly depends on the skill of the surgeon. Arthroscopic surgery is generally preferred unless there are significant concomitant injuries, such as large bony lesions because of instability. One confounding factor is that certain injuries are difficult to reach and stabilize arthroscopically. In these cases, open procedures are usually preferred. Whether Santana undergoes a second open procedure depends on the findings of the diagnostic arthroscopy.

Santana faces an uphill battle. Even first-timers recovering from the surgery have difficulty reaching previous levels. Hershiser managed to remain productive for several years following his surgery in 1990. Saberhagen, who had surgery in 1996, only approached his pre-surgical FRA+ once. Mark Prior had the surgery in 2008, and he has yet to return to the major leagues. Chien-Ming Wang made it back from his 2009 surgery, but he hasn’t been nearly as productive. Kelvim Escobar underwent the surgery in 2010 and has yet to return. Ex-teammate Chris Young underwent surgery in 2011, and although he did return, he was not as effective. If Santana manages to return, he will be a trailblazer. 

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

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