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.
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| 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.
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| Lateral cutaway of the capsule. Courtesy of www.seattleclouds.com |
INJURY MECHANISMS
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.
SURGICAL TREATMENT
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.
SUMMARY