With news of Johan Santana re-injuring the previously repaired anterior capsule of his pitching shoulder and yesterday's successful second surgery, comes an upswell in the curiosity of the injury, what it entails, and what makes it different than some of the more common shoulder injuries befalling players, such as rotator cuff tears and impingements. More commonly seen in traumatic events such as skiing accidents, anterior tears of the shoulder capsule are becoming increasingly diagnosed in baseball as a result of the subacute, microscopic tears of the shoulder capsule that can be sustained with the repetitive, over the head motions native to the game. In spite of the recent advances in orthopedic medicine and imaging technologies, an anterior capsule tear remains indirect and inexact in its diagnosis as a baseball specific injury.
ANATOMY OF THE SHOULDER CAPSULE
Before we begin, for those who would like a primer on the anatomy of the shoulder as it applies to baseball, this article from Baseball Prospectus is a great resource and will provide a firm knowledge base of the relevant shoulder anatomy that will be discussed here.
Briefly, the capsule of the shoulder is a fibrous lining that encompasses the glenohumeral joint and provides additional restraint and stabilization of the joint, keeping the head of the humerus in contact with the glenoid fossa, while also allowing for the wide range of motion allowed by the shoulder joint. It also lends additional support of the glenohumeral joint from the negative pressure environment within the capsule. It attaches laterally to the anatomical neck of the humerus, medially to the glenoid fossa, and superiorly with the attachment of the long head of the biceps, near the root of the coracoid process. The capsule is thickest superiorly and inferiorly and at its thinnest anteriorly; with adduction of the arm, the capsule is loose and lax anteriorly and inferiorly and taut superiorly.
|Illustration courtesy of www.bartleby.com|
The capsule is reinforced by a handful of intrinsic ligaments, which themselves are thickenings of the capsule. The anterior portion of the capsule are reinforced by 3 glenohumeral ligaments – the superior, middle, and inferior – which run from supraglenoid tubercle of the scapula to the lesser tubercle and the anatomical neck of the humerus, creating a Z pattern along the capsule. Additionally, the transverse humeral ligament passes from the greater and lesser tubercles of the humerus and provides additional support in keeping the tendon of the long head of the biceps in the bicipital groove, while the coracohumeral ligament strengthens the superior portion of the capsule, and assists in supporting the weight of the arm against gravity at rest and limits inferior and posterior translation of the head of the humerus. The muscles of the rotator cuff reinforce the capsule superiorly, anteriorly, and posteriorly.
Many of the findings on the mechanism of injury leading to anterior capsule tears are similar to those seen with rotator cuff tears. Most commonly, the shoulder capsule is stretched or torn by violent injury such as dislocation or a sudden powerful subluxation. In baseball, the injury more commonly arises from repetitive micro injuries produced from the abduction and external rotation of the shoulder required to perform over the head movements. With abduction, the thinner and weaker anterior capsule is subjected to multiple iterations of being pulled taut, creating an environment for microscopic tears and stretching of the fibrous capsule to be suffered. With the tear, the normally negative pressure environment within the capsule is lost, thereby reducing stability of the joint, allowing for anterior displacement of the humeral head, and endangering the health of nearby anatomy, in particular, the rotator cuff muscles, as well as the intrinsic ligaments of the capsule.
SYMPTOMS AND DIAGNOSIS OF A CAPSULE TEAR
Differential diagnoses that can cause symptoms similar to a capsule tear are plentiful, and include more typically seen injuries such as SLAP tears, rotator cuff tears, bursitis, and impingement. Specific to the capsule, a clinician must also rule out adhesive capsulitis, commonly known as 'frozen shoulder', as a cause of the pain.
Much like a rotator cuff tear, the player will complain of pain during throwing, in particular the load and deceleration phases of throwing. This in turn can develop into palpatory tenderness of the shoulder around the insertions of the rotator cuff tendons, as well as the bony landmarks of the glenohumeral joint upon physical examination. Musculoskeletal examinations, including the load and shift test and the apprehension and relocation test can be performed to confirm anterior instability. Magnetic resonance imaging is useful in demonstrating the presence, location, and severity of the capsule tear, usually with the administration of gadolinium contrast necessary.
NON OPERATIVE TREATMENT
Non-surgical approaches to treating capsule tears are predominantly not successful, and demonstrate a high rate of occurrence of re-injury. After a period of rest and the initial management of pain and inflammation has been successful, non-operative methods of treatment focus on the restoration normal range of motion, strength, and mechanics, accomplished through standard physical therapy and baseball specific throwing programs once the player is pain free.
No matter what surgical technique is used eventually used for a given player, the goal of surgery is to regain stability of the glenohumeral joint through re-establishing the proper amount of tension to the capsule and the restoration of the labrum to its attachment site, should it be torn. While arthroscopic approaches are typically recommended in athletes due to the reduced amount of recovery time and post operative compromises of shoulder range of motion, open arthrotomies are commonly performed with capsule tears, especially when the tear is adjacent to the glenoid cavity versus the humeral head.
POST OPERATIVE REHABILITATION
Rehabilitation approaches differ slightly depending on the surgical approach used, but are very similar to those seen with rotator cuff repairs. A thorough and detailed description of the rehabilitation process can be found here. Briefly, range of motion is severely limited for first four weeks following surgery, with only basic daily activities and waist level routines allowed. No over the head movements are permitted for six weeks, and the shoulder is protected through shoulder immobilization and slinging at this time to promote uninterrupted recovery and repair. Hand and elbow exercises to promote full range of motion of these wrist and elbow joints are performed at this stage in the rehabilitation, with some shoulder exercise performed after week 2 of this stage, with everything performed as pain allows, against gravity, and with shoulder rotation kept under 90 degrees. After six weeks, strengthening exercises are started, with slinging and immobilization of the shoulder discontinued. As rehabilitation progresses, strengthening exercises are gradually increased, range of motion exercises are continued, and isokinetic and tubing exercises are introduced around three months post-operation. Assessment of baseball specific function will begin around 3-6 months postoperatively, with throwing programs discussed after about nine months of rehabilitation. With open surgical approaches, this may not happen until later, closer to a year postoperatively. Given the rarity of the anterior capsule repair within baseball circles, these guidelines are still being revised to optimize recovery specific to the procedure.