From baseball pitchers, tennis, swimming, water polo to throwing sport athletes who participate in overhead sports and physical activities, a tremendous amounts of stress is exerted on their shoulders and its
surrounding structures when they perform strenuous activities in their specific athletics. For example, an elite baseball pitcher’s arm has been recorded at over 7000 degrees/second,
which makes it the fastest human body movement from any sport.
Shoulder pain is the most prevalent symptom among the overhead athlete where
throwing athletes will generally describe experiencing dead arm, defined as a condition
which restricts them from throwing at pre-injury speeds or control. SLAP, or
superior labrum anterior-posterior, lesions are frequent causes leading to this type of
dysfunction.
What is a SLAP Tear?
A SLAP tear occurs on the glenoid labrum from the anterior to posterior
angle of the long head of the biceps tendon. The glenoid labrum is a wedge-shaped
fibrous tissue structure that is attached to the edge of the glenoid,
functioning to deepen the glenoid cavity to improve stability as well as
implement muscular control and proprioception. The anatomy of the proximal long
head bicep tendon may actually vary but, in a majority of cases, it originates
from the posterior superior labrum and it is broader and innervated more
sensory fibres than the distal tendon.
There are
four main subgroups of SLAP lesions: type 1, where the connection between the
labrum and the glenoid remains intact while degeneration and some shredding has
occurred. It’s believed this may not be a cause of many symptoms; type 2, the
most common type of SLAP lesion which causes a majority of the symptoms and may
require surgery to heal, involves the detachment of the superior labrum and the
long head of the biceps tendon from the glenoid rim; type 3, where the
meniscoid superior labrum tears and is removed from the joint but the
connection between the tendon and the labral rim remains intact; and type 4,
where the tear of the superior labrum extends into the tendon, partially
removed from the joint along the superior labrum.
Mechanism of Injury
Three main controversial theories have been proposed to explain the exact
mechanism of injury for SLAP lesions. The deceleration theory suggests that in
a throwing athlete, a SLAP lesion occurs during the deceleration stage of
throwing as a result of the eccentric contractions of the biceps tendon. Moreover,
they advised that this overloaded the biceps anchor, tearing it from its
intra-articular attachment. A direct impact to the shoulder is also believed to
be a cause for a SLAP lesion. For instance, if an athlete lands on an outstretched
arm, the labrum may become compressed or pinched between the glenoid and the
humerus. Currently, the mechanism of acceleration, or peel back, has been
demonstrated to occur when the arm is in the cocked position of abduction and
external rotation. Researchers described at the time that during arthroscopy in
shoulder abduction and external rotation, the bicep tendon undertakes a more
vertical and posterior angle which causes the base of the biceps to twist,
resulting in a torsional force against the posterior superior labrum.
Furthermore, researchers compared these
deceleration and acceleration theories during an experiment in cadaver models. First,
they applied tension to the tendon of the biceps in which they were able to
generate a superior labral avulsion in approximately 20 percent of the
specimens using an increased force. To reproduce the mechanism of acceleration,
or peel back, researchers positioned the arm in an abducted and externally
rotated position. In about 90 percent of the shoulders tested, a type 2 SLAP
lesion was generated with approximately 20 percent less force than in the
deceleration model. The study concluded that the peel back mechanism is most
likely to cause a SLAP lesion than the deceleration model, furthermore
demonstrating that the bicep tendon is not pulled but rather peeled from the
bone.
Auto Accidents and SLAP Lesions
While sports and physical activities are the
most common cause for SLAP lesions, many individuals have reported experiencing
shoulder pain and other symptoms suggesting a SLAP tear after being involved in
an automobile accident. During an automobile accident, the rapid acceleration
of the vehicle after an impact pushes the body into a forward momentum. Besides
other common car wreck injuries, such as whiplash, the involved individual may
also suffer shoulder injuries as a result of tightly gripping the steering wheel
or even from reaching out at the exact time of the incident. For instance, when
a mother accompanied by a passenger is involved in an automobile accident,
their initial instinct is to reach over with a single arm and attempt to secure
the passenger in their seat. Unfortunately, due to the momentum of the
collision, the individual’s arm may be pushed away, causing damage on the
shoulder and possibly leading to a SLAP lesion. Regardless of the cause of
injury, SLAP lesions can be very painful, often being debilitating to the
affected individual.
Clinical Presentation
Athletes with SLAP tears generally describe
pain within the shoulder. Throwing athletes also often report weakness when
throwing. While they may still be able to throw, their normal throwing velocity
may decrease. Many individuals affected with SLAP lesions experience tightness
on the back of their shoulder along with pain and weakness at the front,
specifically over the coracoid process area. They may also describe a clicking
or popping sensation when they throw. It’s essential to determine whether the
symptoms are recent and if they are painful or not. As mentioned before, an
athlete who experiences pain or weakness in the late cocking stage may have a
SLAP tear whereas an athlete who only describes pain on follow-through may be
more likely have impingement-related symptoms.
Standing Posture
Frequently, athletes with SLAP lesions experience an improper placement of the
scapula at rest. Researchers describe that an asymmetrical placement of the
scapula can be characterized by scapular malposition, inferior border
prominence, coracoid pain and dyskinesis of scapula movement. It’s essential to
point out the athlete’s thoracic posture as an increased kyphosis and a lack of
trunk rotation an additionally increase the weight being placed against the
shoulder during throwing motions.
Shoulder Range of Motion
The range of motion of the shoulder may be
evaluated to conclude the individual’s symptoms and restricted mobility. An
athlete’s glenohumeral range of rotation should be properly analyzed in all
overhead athletes. A thrower’s shoulder must have enough flexibility for
excessive external rotation with plenty of dynamic stability to avoid
subluxations, or misalignments. Glenohumeral range of rotation assessments are accomplished
in a supine position with the arm in a 90-degree abduction. These athletes
commonly experience an increase in the range of their external rotation due to
a constant stretching of their anterior capsule in the cocking stage and/or
humeral retroversion if they consistently practiced throws since a young age as
well as a decrease in their internal range of rotation. A lack of internal
rotation generally occurs as a result of a contracture on the postero-inferior
capsule contracture, commonly referred to as GIRD, or glenohumeral internal
rotation deficit. Sleeper stretches have been demonstrated to decrease GIRD as
well as decrease the risk of shoulder injuries by up to 40 percent in major
league baseball players.
Orthopedic Assessment for SLAP Lesions
Various
distinct shoulder evaluations to determine SLAP lesions have been previously
described above, however, it’s essential to understand that these tests may not
necessarily be sensitive or specific, therefore, several tests should be
utilized in each examination. A SLAP lesion should be suspected if most of the
following tests conclude as positive and prior history of a SLAP lesion is
suspected.
Individual tests for SLAP lesions include:
O’Brien’s Active Compression Test
During stage 1 of this test, the patient’s arm
must initially be in a 90-degree flexion as its horizontally flexed, or
adducted, 10 degrees with the thumb pointing down. The individual is required
to withstand the healthcare professional’s downward pressure, noting the
presence of any pain or symptoms.
During stage 2 of this test, an identical
procedure is followed with the individual’s palm facing up. If the individual
reports pain within the shoulder during the exercise but no pain after the
exercise, the test is considered positive.
Biceps Load 1
For this assessment, the athlete suspected of injury must sit with the
shoulder in a 90-degree abduction with an external rotation, or a position of
apprehension, while the forearm is in supination, taking note of any painful
symptoms. The individual will then be instructed to contract their biceps while
the healthcare professional withstands elbow flexion. It is suggested that the contraction
of the biceps may increase pain if there’s in the case of a SLAP tear while it
would decrease pain in the case of an anterior instability only as the bicep
contraction would stabilize the front of the shoulder.
Biceps Load 2
This assessment was particularly developed to recognize the presence of
SLAP lesions on the shoulder. The individual’s arm is placed in a 120-degree
abduction along with a full external rotation while the elbow is supinated and
flexed to 90-degrees. The individual is then indicated to flex their elbow while
the healthcare professional withstands the load. Researchers describe a
positive test is shown when the individual’s pain increases with the resisted
elbow flexion.
Resisted Supination Test
This test is utilized to recreate the peel back mechanism believed to be
responsible for SLAP lesions during throwing sports or physical activities. The
evaluated extremity is placed in a 90-degree abduction with neutral rotation
and the elbow is placed in a 60-70-degree flexion.
The healthcare professional withstands
supination while passively externally rotating the arm to end of range. A
positive test is demonstrated when the individual experiences clicking,
catching and anterior or deep shoulder pain only. Researchers added that with
this test, posterior shoulder pain or apprehension does not necessarily suggest
the presence of a SLAP lesion.
Crank Test
The individual is placed supine with the arm in a 160-degree abduction
in the scapula plane. The healthcare professional then applies an axial load to
the glenohumeral joint while internally and externally rotating the shoulder.
This test is considered positive if the individual’s pain is reproduced or a
painful mechanical click is reproduced.
Dynamic Labral Shear Test
The individual’s arm is placed in a 120-degree abduction and external
rotation. The healthcare professional places shear stress on the arm by
maintaining external rotation and horizontally abducting as well as lowering
the arm from a 120 to a 60-degree abduction. A positive test is indicated by
reproducing the individual’s pain or a painful click.
Treatment
Shoulder injuries in throwing athletes may be first managed utilizing
conservative treatments focused on improving GIRD and/or scapula control. In a
majority of cases, the entire kinetic chain must be evaluated and the proper
exercises should be carried out according to the specific demands of the sport.
For instance, a cricketer who bowls and throws with the right arm
reported experiencing symptoms of pain and weakness in the shoulder with
activity. The individual displayed symptoms of pain on the O’ Brien’s Active
Compression Test, Biceps Load 2 and Dynamic Labral Shear Test. The individual
also experienced pain through range on abduction, which improved when the
position of the scapula was corrected, or tilted posteriorly. Moreover, the
individual had no loss of glenohumeral range on the right side.
Due to the success of posteriorly tilting the scapula upon experiencing
pain during the assessment, treatment must be focused on lengthening techniques
of the muscles which anteriorly tilt the scapula, helping to strengthen the
lower and middle trapezius and further improving the condition of the scapula.
The individual was assigned a range of exercises to improve scapula placement. The
individual involved in the assessment experienced improved symptoms over a four-week
period and was able to throw from the boundary without experiencing any
symptoms.
Conservative treatment may not always be successful, specifically if a
type 2 SLAP lesion is present. In these instances, surgical procedures may be required
and the athlete will take 9 to 12 months to return to their specific sport or
physical activity and they will report that it takes up to two years to return
to their pre-injury level of fitness.
Rehab or Surgery for SLAP Lesions
Chiropractic for SLAP Tears
According to the severity of an athlete’s injuries, each individual
may respond differently to treatment. Several studies have demonstrated that
conservative treatment can help some athletes return to their specific sport of
physical activity. A 2010 study displayed a 71 percent success rate, allowing
athletes to return to participation levels after rehabilitation, although about
66 percent of these individuals were able to perform at the level prior to
injury. Chiropractic care is an effective, alternative treatment option for a
wide variety of musculoskeletal injuries and conditions, primarily focusing on
the spine and nervous system dysfunction. After performing several evaluations
to determine the source of an individual’s pain and symptoms, a chiropractor
may commonly utilize spinal adjustments and manual manipulations to first
correct any misalignments of the spine. Following these initial procedures, a
chiropractor may use mobilization stretches and exercises to carefully restore
strength, flexibility and mobility to the structures surrounding the shoulder. As
with any type of injury or condition, time and patience is often required to
fully restore the body back to its original condition of health.
By Dr. Alex Jimenez