SHOULDER INSTABILITY
Accurately Evaluating Shoulder Injuries
on the Field and on the Sideline
_____________________________________________________________
by Jon Heck, MS, ATC, and Jeana Sparano
Jon Heck is the coordinator of athletic training at Richard Stockton College in Pomona,
NJ. He received his bachelor's degree at William Paterson College and master's degree
at the University of Florida.
Jeana Sparano is currently a graduate student in the physical therapy program and a
student athletic trainer at Richard Stockton College in Pomona, NJ. She also received
her bachelor's degree in biology at Stockton.
Accurately evaluating shoulder instability is one of the more formidable tasks in
sports medicine. The signs and symptoms are often subtle, transient, confusing and
difficult to reproduce upon examination. Subluxation can also be easily mistaken for a
variety of other shoulder injuries.
Evaluating shoulder injuries during games presents the athletic trainer with many
obstacles. Emotions and intensity are high. Numerous players may experience injuries
simultaneously, and quite often athletes withhold information to stay in the game. Game
time also produces pressure to accurately evaluate the injury and make a timely and
appropriate return-to-play decision. The combination of these factors make on-the-field
assessment of shoulder instability a complex challenge for the athletic trainer.
Following are evaluation tactics in assessing instability on the field and on the
sideline. Also, criteria for referral and return-to-play decisions will be examined.
On-the-field Assessment
The purpose of on-the-field assessment is to determine the severity of the injury
via an abbreviated exam. This initial assessment is used to determine whether or not the
athlete should be moved to the sideline for a more complete injury evaluation or if the
injury requires immobilization and warrants referral to a medical facility.
The Dislocation
Dislocation of the shoulder is a serious instability. It is well-defined by the
complete removal of the humeral head from the glenoid fossa (1,2,4). The athlete with a
dislocated shoulder will usually identify the problem immediately to the athletic trainer
with comments such as "my shoulder's out" or "my shoulder popped out." The evaluation
then begins by the athletic trainer reaching under the shirt to palpate the shoulder while
taking a history throughout the assessment. A quick confirmation of the athlete's initial
description is attained by searching for deformities and noting the direction of the
dislocation.
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The anterior, inferior and posterior dislocation will have distinct signs upon
palpation. With an anterior dislocation, the head of the humerus can usually be palpated
in the front of the shoulder and the acromion will be abnormally prominent (2,9). A pure
inferior dislocation will be similar except the humeral head will be in the armpit. A
posterior dislocation will have a flattened anterior aspect, a prominent coracoid process
and a rounded posterior aspect of the shoulder (1).
Neurovascular Exam
The next concern for the sports medicine professional is the neurovascular status
of the injured shoulder. Circulation can be assessed by the radial pulse and capillary refill
at the nail beds (9). Any abnormal signs here warrant immobilization and immediate
transport to a medical facility. The presence and location of sensation problems, such as
numbness or tingling, should be questioned. The compromise of the axillary and
musculocutaneous nerves, and the brachial plexus in general, are prime concerns in any
dislocation (1,9). An isometric test of shoulder abduction and elbow flexion should be
included as well as a quick check of grip strength. While some weakness is anticipated, a
gross deficit, combined with numbness and tingling, signifies a need for immobilization
and immediate transport to a medical facility.
Mechanism of Injury
The history is then directed to the mechanism of injury to determine a match with
the direction of the dislocation. Generally, an anterior dislocation is related to forced
horizontal abduction or forced external rotation with the arm abducted above 90 degrees
(9). Inferior dislocations are usually related to a downward force on the superior proximal
humerus with the arm in 90 degrees of abduction. For example, a football player who is
bent at the waist and attempting to block or tackle an opponent is subject to an inferior
dislocation. Posterior dislocations are often the result of a posterior force applied to a
forward-flexed and internally rotated shoulder, such as falling on an outstretched arm.
This type of dislocation is rare in athletics (4,7,9).
Decision and Action
Obviously, an unreduced dislocation warrants immediate referral. The next step is
to prepare the athlete for transport to a medical facility. Reducing a shoulder dislocation
on the field or sideline in front of teammates, coaches, fans and parents is not
recommended. A medical facility, complete with imaging equipment, is a far superior
environment to reduce a dislocation (9,10). In the absence of a team physician this rule
should be followed absolutely. An elastic bandage may be used to immobilize the arm
and shoulder in whatever position is most comfortable for the athlete. This position may
vary from athlete to athlete and the direction of the dislocation. If a humeral neck fracture
and a clavicular fracture have been ruled out, removing the athlete from the field for
transport can be considered. This decision is based upon the athlete's reaction to the
injury and his or her willingness to walk to the sideline.
The Sideline Assessment
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If the athlete does not demonstrate a dislocation on the field, further evaluation on
the sideline should be performed. The purpose of the sideline assessment is to complete a
more thorough exam and to get a solid impression of the injury. The sideline assessment
is also used to determine whether or not the athlete can safely return to play. If not, the
athletic trainer must decide when and if the athlete should be referred. In most cases a
subluxation does not warrant immediate referral.
The Subluxation
It is much more difficult to accurately assess a subluxation than a dislocation.
Once the humeral head returns to the glenoid, the remaining signs and symptoms may
mimic other injuries. In fact, the more subtle the subluxation, the more challenging the
assessment (5,8). Subluxation is defined as excessive and symptomatic translation of the
humeral head along the glenoid (1,4,6,8). It may be anterior, inferior, posterior or
multidirectional (4,6). The degree of translation, the portion of the humeral head that
crosses the glenoid rim and the length of time the head is removed from the fossa
determine the severity of the subluxation.
The assessment of a subluxation begins with a neurovascular exam, similar to the
one performed on the playing field. This exam is performed to rule out the most serious
problems first. On the sideline, the brachial plexus dermatomes are checked for
sensitivity to light touch. Special attention should be given to the lateral deltoid and the
radial forearm, since these areas represent the axillary and musculocutaneous nerves (9).
After a subluxation episode the athlete may experience dead-arm syndrome. These
symptoms include altered sensation, (1,5,6) a "heavy" feeling and a general weakness of
the arm.
History
The importance of the athlete's history cannot be overstated when assessing
subluxations. The athlete who experiences a moderate subluxation will give important
clues if questioned properly. The most important question to ask is, "Did it feel like your
shoulder came out?" Other key concepts to include when questioning the athlete are
"unstable," "slipping" or "sliding" sensations (5). An athlete may be kept out of
competition based on positive replies to these questions even if the rest of the exam is
unremarkable. The direction of the instability and the frequency of the episodes should
also be questioned. Chronic subluxators will easily communicate their episodes of
instability.
If the athlete confirms a subluxation, clinicians should inquire about the length of
time the shoulder was "out". In contrast, the athlete may describe the subluxation episode
as immediate (6). Establishing when a subluxation becomes a dislocation is a difficult and
subjective task. When a subluxation is described as being "out" for any period of time it
is considered to be a self-reduced dislocation. A self-reduced dislocation indicates
removal from competition and follow-up with an orthopaedist.
The next task for the healthcare professional is to determine the mechanism of
injury. Normally, the athlete who is injured on the field will have a traumatic mechanism.
The traumatic causes for subluxation are similar to those of a dislocation. In particular,
the position of the arm when the injury occurred is very important. The mechanism of
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injury is usually a strong indicator of the direction of the subluxation. Because the
mechanism of subtle subluxation is normally chronic overuse, clinicians should not
expect to see this problem on the field (7,8). This athlete will normally present with rotator
cuff problems in the athletic training room.
Observation and Palpation
Observing the athlete's post-injury carrying position of the arm and shoulder is
very useful. After a subluxation episode the athlete will usually keep the arm very close
to the body, or in a "slinged" position, and support it with the other hand (1,6). This is a
stable and secure position and can be easily observed as the athlete walks off the field.
The athlete is also usually reluctant to actively move the arm away from the body,
especially in forward flexion and abduction.
The location of point tenderness used in conjunction with other signs and
symptoms is helpful when evaluating shoulder instability. Athletes with multi-directional
instability may have point tenderness along the medial border of the scapula (6). This is
probably due to excessive stress placed upon the scapular rotators. Point tenderness along
the posterior joint line is indicative of posterior instability (1,7,8). Anterior subluxators are
point tender over the greater tuberosity, but this is also true for impingement and bicipital
tendinitis.
Stress Tests
Passive translation tests of the humeral head on the sideline, other than the
inferior sulcus sign, may be of limited use. These tests are very subtle, and the sideline
environment is not conductive to their accurate use. Clinicians should focus their sideline
assessment on four tests that stress the shoulder in compromising positions. Although
these tests may cause pain, they are considered a true positive when they reproduce the
athlete's symptoms of instability.
For anterior instability the apprehension and relocation tests are used (3,5,6). These
tests are performed simultaneously with the athlete in a supine position. If a positive
apprehension sign is obtained, the relocation test is then performed by applying a
posterior force to the humeral head. A positive relocation test will reduce the
apprehension and allow additional external rotation. To confirm this result, the posterior
force is then released and observation begins for an incremental return of the symptoms.
A positive sulcus sign is more indicative of multi-directional instability than
isolated inferior instability (1,4,5,6,8). For posterior instability the posterior stress test is
used (1,4,5). The arm is forward flexed to 90 degrees, the elbow is flexed to 90 degrees and
the shoulder is internally rotated. A posterior force is then applied to the elbow while
stabilizing the medial border of the scapula. The athlete must be relaxed for this test to be
effective.
Posterior Instability
Posterior subluxation caused by chronic overuse is much more common than
posterior dislocation (4,7,8). The subluxation is usually subtle, and these athletes rarely
describe a feeling of posterior instability (8). This makes assessment very difficult.
Therefore, posterior subluxation is suspected when pain occurs during the follow-through
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phase of any overhead sports and the pull-through phase of swimming, rowing (4,7,8) or
swinging a bat.
Isolated posterior instability is rare, and it is usually accompanied by an inferior
and/or anterior instability (4,6). Therefore, posterior instability is suspected when any
other type of instability is found along with posterior shoulder pain. Posterior subluxation
in athletes who have had surgery for anterior instability has also been encountered.
Return to Play
The rule of automatic removal from play for any athlete who experiences a firsttime subluxation should be followed. This athlete should be put in a sling and referred to
an orthopaedist for follow-up.
The athlete with chronic instability presents a unique challenge. An athletic
trainer should discuss the athlete's case with the treating orthopaedist before the season
begins. In particular, healthcare professionals need to determine the athlete's return-toplay options if another episode occurs during a game. With the guidelines set by the
orthopaedist, it may be warranted for certain athletes to continue to play after a
subluxation.
Sports medicine professionals should not expect to catch the cause of rotator cuff
pain, secondary to subtle instability, on the sideline. For this athlete, a return-to-play
decision based upon an evaluation of their rotator cuff symptoms is made. This athlete
would be re-examined in the training room where a much more detailed and focused
evaluation can take place.
References
1. Allen, A.A. and Warner, J.P. (1995). Shoulder instability in the athlete. Orthopedic
Clinics of North America, 26, 487-504.
2. Aromen, J.G. and Chronister R.D. (1995). Anterior shoulder dislocations. The
Physical and Sports medicine, 23(10), 65-69.
3. Kvitne, R.S. and Jobe, F.W. 91993). The diagnosis and treatment of anterior
instability in the throwing athlete. Clinical Orthopaedics and Related Research,291,
107-122.
4. Pollock, R.G. and Bigliani, L.U. (1993). Recurrent posterior shoulder instability.
Clinical Orthopaedics and Related Research, 291, 85-96.
5. Sigman, S.A. and Richmond, J.C. (1995). Office diagnosis of shoulder disorders. The
Physician and Sports medicine, 23(7), 25-31.
6. Silliman, J.F. and Hawkins, R.J. (1993). Classification and physical diagnosis of
instability of the shoulder. Clinical Orthopaedics and Related Research, 291, 7-19.
7. Tibone, J.E. and Bradley, J.P. (1993). The treatment of posterior subluxation in
athletes. Clinical Orthopaedics and Related Research, 291, 124-137.
8. Torchia, M.E. and Bradley, J.P. (1995). Managing posterior shoulder instability. The
Physician and Sports medicine, 23(1), 41-51.
9. Valceschini, G. and Macintyre, J. (1995). Immediate reduction of shoulder
dislocation. The Physician and Sports medicine, 23(3), 61-65.
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10. Wichmann, S. and Martin, D.R. (1992). Reducing dislocations on the field. The
Physician and Sports medicine, 20 (9), 180-186.
Address correspondence to:
Jon Heck, MS, ATC
Richard Stockton College
Jim Leeds Road
Pomona, NJ 08240
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