dakndk

Mini-synqmdum: the sbuider
(iv) Shoulder Instability
R. J. Hawkins, S. R. Saddemi
-
Introduction
riorly, with anterior instability historically being the
most common. The shoulder may also be unstable in
more than one direction, termed multi-directional
instability. Inferior and anterior along with inferior
and posterior are the most common multi-directional
instabilities, but instability in all three directions may
occur. In order to be multi-directional, symptomatic
inferior instability should be present, in addition to
instability in at least one other direction.
The degree of instability is also an important
component of the classification. A dislocation is a
complete loss of the normal gleno-humeral articula-
Shoulder instability has been a problem for treating
physicians for hundreds of years. Hippocrates, the
father of medicine, wrote detailed descriptions of
shoulder anatomy, dislocations and their treatment.
The concepts regarding the diagnosis, classification,
and management of shoulder instability have evolved
greatly over the years. The evolution is not yet
complete as today’s shoulder experts are still debating
the best ways to diagnose and classify shoulder
instabilities and the optimal ways to treat them. The
latest controversial area in the management of
shoulder instabilities relates to arthroscopically assisted stabilization for anterior instability which may
play a larger role in the management of shoulder
instability in the future.
The purpose of this report is to review the concepts
of shoulder instability as they relate to classification,
diagnosis, and management.
Table
I
Multi-directional
Anterior-Inferior
Posterior-Inferior
Anterior-Posterior-Inferior
Classification
The classification of shoulder instability is based on
many factors such as direction, degree, chronology,
etiology, and volition (Table). All of these factors can
play a role in the classification of a particular patient’s
instability.
The direction in which a should is unstable is an
important aspect of the classification. Uni-directional
instabilities of the shoulder occur anteriorly or poste-
Current Orthopaedrcs (1990) 4,242-252
II
Degree
Dislocation
Subluxation
III
Chronolog>
Acute
Chronic
Recurrent
Locked
IV
Etiology
Traumatic
Atraumatic
Hyperlaxity
Overuse-Acquired
Hyperlaxity and Overuse
R. J. Hawkins MD, FRCS, The University
of Western Ontario,
University
Hospital,
339 Windermere
Road, London, Ontario,
Canada N6A 5A5.
S. R. Saddemi MD, Director of Sports Medicine, Medical College
of Ohio. Toledo, Ohio 43699, N5A.
0 1990 Langman Group UK Ltd
Direction
Uni-directional
Anterior
Posterior
Inferior
V
Volition
Voluntary
Involuntary
Positional
0268~890:90/ooO4
242
0242/$,0 00
SHOLJLDER INSTABILITY
tion. while a subluxation
is a partial loss of glenohumeral articulation.
Dislocations
and subluxations
may occur in any direction and both may occur at
different times in the same patient.
The chronology or the timing of the dislocation or
subluxation
is also LI part of the classification.
The
instability ma\ be acute or chronic; if chronic it may
be locked or recurrent.
The etiology of the instability
is important because
it implies different management.
A dislocation
or
subluxation
rn;ly be traumatic
or atraumatic.
Traumatic dislocations
occur as a result of 3 significant
injury. Atraumatic
dislocations
occur in two situations : in those with hypermobility
and hyperlaxity of
the shoulder, and in those who overuse their shoulders
repeatedly, especially in the overhead position. Both
factors. hypermobility
and overuse, may contribute to
an atr,iumatic
dislocation.
These individuals
are
particularly prone to multi-directional
instability.
The volition ot‘the dislocation is the final component
of the classification.
A dislocation is either voluntary
or involuntary.
A voluntary dislocation occurs when
the indrvidual intentionally.
willfully dislocates his or
her shoulder with muscular contraction.
An involuntary dislocation occurs without any overt attempt on
the part of the patient todo so. Involuntary dislocations
may be positional. meaning that the dislocation occurs
when the patient places his arm in a certain position.
Generally
positional
dislocations
are involuntary,
occurring when the patient positions his arm for ;I
particular functron or activity. Positional dislocations
may, however. become voluntary
over time, if the
patient places the arm in ;I certain position merely to
cause the dislocation.
Certainly voluntary and involuntary episodes may coexist in the hvme patient.
Voluntary dislocators occasionally require psychiatric
evaluation in addition to treatment of their shoulder.
Matsen has introduced acronyms to broadly classify
two groups of patients
with shoulder
instability.’
Patients with ‘Traumatic
shoulder instability
often
have a Unilateral
problem,
a Bankart lesion, and
usually require Surgery for optimal management’
terms ‘TUBS.’ (Traumatic,
Unilateral,
Bankart, Surgery).: On the (Ither hand. patients with an ‘Atraumatlc
initial
Injury
may have multi-directional
instability.
often have bilateral shoulder instability
and usually
respond
to a specific rehabilitation
program. Should surgery became necessary in this
patient, an infcrlor capsular shift is the appropriate
procedure.’ This is the ‘AMBRI’ group (Atraumatic,
Multi-directional.
Bilateral. Rehabilitation,
Inferior
Capsular Shift). .
In reviewing the classification
ue must remember
that it ih important
to know the direction,
degree.
chronology,
etiology, and volition of the instability,
For example, one who sustains an anterior dislocation
while making an arm tackle playing football has an
‘Acute Traumatic
Anterior Dislocation.‘
if that individual has several subsequent
episodes of instability,
he has ‘Chronic Recurrent Anterior Instability’.
The
243
instability
may be further classified bq the degree
depending
on whether dislocations
and,‘or subluxations occur. The classification
is important because it
implies which management
is most effective.
Anatomy and Biomechanics
The gleno-humeral
joint is dislocated more frequently
than any other joint in the body. This is not surprising
in view ot’ the great mobility present at this joint,
which lives in a milieu consisting
of ;I trade-off
between stability and mobility.
‘The stability ofthe gleno-humeral joint is dependent
on the intergrated
function of the bony architecture,
the labrum. capsule. gleno-humeral
ligaments.
dynamic muhclc function,
and an internal
pressure
gradient compared to atmospheric
pressure
The bony architecture
of‘ the shoulder does not
contribute
much to its stability.
The glenoid
is
relati\elq flat with a radius of curvature less than half
thar of the humcral head, and cover\ onl) about 15
33”,, of the humeral head. Sidles compared the glenohumeral articulation
to a ‘golf ball on a tee‘. referring
to 11s l,ick ctf inherent stability. The glenold labrum
increases the radius ot‘ cur\‘ature and deepens the
gtenoid. thus making it more concentric
with the
humeral head. The tabrum is also important
as it
series as the attachment
site for the glens-humeral
ligaments.
T-he gleno-humeral
ligaments control passive and
dyn,lmlc stability of the shoulder. The superior. middle
and inferior gleno-humeral
ligaments act in concert
pro\ iding stability. The ligaments function by tightening at the extremes of motion to limit further
translation
of the humerus preventing
a suhtuxation
or dislocation.
The inferior gteno-humeral
ligament
with its anterior and posterior bands is the prime
stabilizer of the shoulder, resisting anterior. posterior
and mfcrior translation.
The superior gleno-humeral
ligament is l’elt to have little function in pr-eventing
anterior
1nstabillty.
but does restraIn lnlcrior and
postcarior translation.
The middle gleno-hunlrral
ligamen! act5 as a secondary restraint to anterior- translation. and al40 functions to limit external rotation ‘it
45 of abduction. The most vulnerable positlon for the
shouider is elevation above the horirontal.
especially
as it is forced into excessive extern;tl rotation and
extelision. It is at this position that the inferior gtenohumcral ligament tightens. acting as :I check-rein
to
limit further external rotation and pre\‘ent anterio
instability.
Ligament cutting studies have shown that
cutting all of the posterior ligamentous
structures
alone did not allow a posterior dislocation. Dislocation
posteriorly did not occur until the anterior- superior
capsule and superior gleno-humeral
ligament *ere cllt
from the 12 to 3 o’clock position
;lntcriorly.
The
authclrs concluded that the shoulder acts as ;I ‘circle’.
in th,lt tight lor loose ligaments on one \ide ot. the joint
may %tffect translation
not only on that sl&. but alxo
on the opposite side of theJoint.
244
CURRENT
ORTHOPAEDICS-MINI-SYMPOSIUM:
Dynamic stability of the shoulder is provided in
large part by the muscles crossing the joint. Muscle
contraction increases joint compression,
thus increasing stiffness and decreasing translation.
The rotator
cuff muscles, because of their origins and insertions,
are well positioned
to resist subluxating
forces by
creating joint compression. They act concentrically
on
one side to provide movement
and eccentrically
on
the opposite side to maintain stability. The position of
the glenoid is also important in gleno-humeral
stability, making scapular function important. The trapezius
and serratus anterior are the primary movers of the
scapula and should be assessed when evaluating glenohumeral stability.
SHOULDER
m,
Normal attachment of
0.5 cm avulsion of
labrum and capsule
from glenoid rim (mild).
NPE I
Bankart
Lesion
1.0 cm avulsion of
labrum and capsule
(moderately severe)
NPE II
Bankan
Lesion
Pathophysiology
With knowledge of normal gleno-humeral
anatomy,
biomechanics,
and the factors which contribute
to
normal gleno-humeral
stability, we can better understand the pathophysiology
of shoulder instability.
Dysplasia or damage to the humeral head or glenoid,
loss of integrity of the capsular-labral-ligamentous
complex, or muscle dysfunction
may all contribute to
instability.
The ‘essential’
lesion is that pathologic
lesion
responsible for perpetuating
the recurrent instability.
There may commonly
be more than one ‘essential’
lesion. Rowe’ categorized
the various pathologic
lesions into three areas: (1) Capsular
lesions. (2)
Muscular lesions, and (3) Bony lesions. There are three
capsular lesions : (1) Rupture of the capsule and labrum
from the rim of the glenoid (the Bankart lesion), (2)
Rupture of the capsule from the humeral neck, and (3)
Excessive laxity of the capsule secondary to repeated
injury (Fig. 1).
Most investigators
agree that the most common
lesion accounting
for recurrent anterior dislocations
and subluxations
of the shoulder is an avulsion of the
labrum and capsule from the glenoid rim, better
ANATOMICAL
LESIONS
I \
“Reverse” Hill-Sach’s
(posterior dislocation)
Hill-Sachs lesion
Bankart lesion
Anatomic variatibns
of the glenoid
(
THE
\
Fig. l-Reprinted
from: Rowe, C. The Shoulder. New York:
Churchill Livingstone, 1988.
1.5 cm + avulsion of
capsule. The labrum
may be difficult to identify, as it is either worn
away or absorbed into
the capsule. Glenoid rim
is eburnated (severe).
TYPE Ill
Bankart
Lesion
.\
TYPE IV
Fracture of
Anterior
Glenoid rim
‘.
Different degrees of fracture of the glenoid rim
may occur. The avulsed
rim is usually enmeshed
in the capsule.
-81)
Fig. 2-Reprinted
from: Rowe, C. The Shoulder. New York:
Churchill Livingstone, 1988.
known as ‘the Bankart lesion’ (Fig. 2). Avulsion of the
capsule from the glenoid rim was noted by Caird in
1887, then by Broca and Hartman in 1890, and Perthes
in 1906. It was later popularized by Bankart in 1923.”
In Rowe’s follow-up series a Bankart lesion was found
in 85% with traumatic recurrent anterior dislocation,l
in 64% with recurrent anterior subluxationqs
and in
84”,/,of those operated upon for previous failed anterior
surgical procedures.h
Excessive capsular laxity may be present alone or
in conjunction
with a Bankart lesion, often contributing to the instability.
Rowe found abnormal capsular
redundancy
in 28% of those with traumatic recurrent
anterior dislocations,
in 26% of those with recurrent
anterior subluxations,
in 86”/0 of those with previous
failed anterior surgical procedures,
and in loo’?/, of
those with voluntary subluxation.7
A recent presentation
by Uribe at the American
Orthopaedic
Society for Sports Medicine
in 1989
documented the arthroscopic pathology in 45 patients
with an acute traumatic primary anterior dislocation.
These patients were placed into one of three groups
based on the intra-articular
pathology and the examination under anesthesia.
Type I included II”, of the
patients who were felt to have stable shoulders under
SHOULDER
______.~
anesthesia, minimal hemarthrosis
and had a capsular
tear only, Type 1 included 34”, of the patients with
increased anterior translation
indicative
of anterior
instability,
a more obvious hemarthrosis
and separation of the glenoid labrum. Type 3 was by far the
largest group including 63”, of the patients. They had
gross anterior instability
with complete avulsion of
the anterior labrum.
Muscle lesions are a much less frequent and more
poorly understood
cause of shoulder instability.
In
Rowe’s series of I58 shoulders
operated
on fo1
recurrent anterior dislocation,
the subscapularis
was
considered normal in 83”,, ‘attenuated’or’inadequate‘
in IO”,,. and ruptured in 7°r,.J Although certainly more
difficult to document. a certain percentage of patients
with recurrent anterior instability also ha\-e pathology
of the rotator tuft: primarily the supraspinatus.
We
know that a strong rotator cuff is important
in
providing dynamic gleno-humeral
stability, and Jobe
has introduced the concept ofcoexistence
of instability
and impingement.
so we must be much more critical
in our analysis of the rotator cuff and its function when
evaluating gleno-humeral
instability. We also must be
aware ot‘the high incidence of acute rotator cuff tears
in those patients who are over 40 years of age at the
time of an acute traumatic anterior dislocation. Rowe
also noted another ‘muscle lesion’ in a series of 37
patients operated on for recurrent anterior subluxation.< An enlargement
of the normal seam between
the subscapularis
and supraspinatus
tendons (i.e. ‘the
rotator interval’) was seen in 20 of the 37 shoulders.
This may represent
loss of the normal suspensory
mechanism and may contribute to anterior instability.
Bon) lesions may also contribute
to shoulder
instability.
A bony defect of the humeral head to
glenoid may be one of the ‘essential’ lesions contributing to gleno-humeral
instability.
The Hill-Sachs
lesion. an osteochondral
compression
defect of the
posterior humeral head. is produced by impaction of
the humeral head against the glenoid rim at the time
of dislocation.
Hill-Sachs lesions of varying degrees
often exist. Rowe found Hill-Sachs lesions in 77”, of
143 traumatic
dislocations,’
in 40°, of those with
recurrent subluxation.’
and in 76”” of failed surgical
repairs.” Glenoid rim damage may also contribute
to
instability.
Rowe found glenoid rim damage in 73O, of
those with traumatic recurrent anterior dislocations,l
in 45”, of those with recurrent anterior subluxation.i
and in none of the \Toluntary dislocators or subluxatars. _
Diagnosis and Management
Instabilities
Anterior glmo-hunwml
of Specific
instahiiit.~~
Acute traumatic anterior dislocations. An acute anterior
dislocation
is by far the most common form of acute
shoulder instability. The overall incidence of shoulder
dislocations
is estimated to be between 1 and 3”0 ot
INST.ABII.ITY
____
‘45
the population” with anterior dislocations accounting
for about 98”” of these.” Dislocations
are approximately twice as common in males than females.” The
diagnosis is made by an appropriate
histor!. physical
examination
and radiographic
evaluation.
7he usual patient is a male who injures his shoulder
in an athletic event. The mechanism
of in.jury is an
extremely important part of the history, as It is often
the best clue as to which direction
the shoulder
dislocated. Indirect force to the shoulder, usually from
a direct force applied to the arm, which results in
excessive abduction,
extension and external rotation
is the usual mechanism
of injury. These forces cause
attenuation
and disruption of the static and dynamic
anterior stabilizers of the joint, and the humeral head
dislc)cates anteriorlv.
To summarize.
the important
part\ of the history are the position of the arm and the
degree and position of the applied force at the time of
the injury. The patient may also be able to relate in
which direction the shoulder dislocated.
whether or
not paresthesias
were present.
and the details of
reduction following the injury.
Atter obtaining
a thorough history, the physical
examination
typically reveals a patient with a very
painiul. tender shoulder. There is muscle spasm about
the shoulder and inspection
reveals ;I hollow posterior]! beneath the acromion. The arm is generally held
across the abdomen and the patient is unable to full>
rotate or abduct the arm. The physician should be sure
to document axillary nerve function since it may he
injured at the time of dislocation.
Radiographs
01‘the injured shoulder in t&o planes
90 to one another are essential. We recommend a true
anterior-posterior
(AP) view ofthe shoulder and a true
axillary X-ray. A true axillary X-ray often cannot be
obtained, and with an acute anterior dislocation
the
AP view alone combined with a history and physical
will document the dislocation. In this case the AP and
axillary view\ should be obtained after reduction. In
the e\ aluation of chronic anterior instability.
a Weht
Point view or an apical oblique view, both of which
are helpful in the evaluation
of anterior glenoid rim
defects. and ;I Stryker notch view or an AP \~ew with
the arm in internal rotation. to evaluate the posterior
humcr-al head for a possible Hill-Sachs det’ctt. mav
also provide helpful information.
Radiographs allow the sub-classification
of anterior
dislocLition. Sub-acromial
dislocations
are the most
common. with subglenoid.
sub-clavicular
and intrathoracic antcrlor dislocations being other variants.
MU~U/,YCVIVII~.
A closed reduction
01’ an anterior
shoulder dislocation
should be attempted
;I> \oon a\
the appropriate evaluation has been perform&.
After
the administration
of appropriate
analgesic5
anti
muscle relaxants, a closed reduction is attempted. Tht
least traumatic
m&hod of reduction
is imperative
The Stlmson technique with the patient prone and the
arm hanging cover the side of the bed with traction
applied. or traction-countertraction
maneu\ t‘rs are
generally successful and are reasonably
atraumatic.
246
CURRENT
ORTHOPAEDICS-MINI-SYMPOSIUM:
Occasionally, general anesthesia is required for closed
reduction, and rarely an open reduction is necessary.
Following a successful reduction, X-rays should be
obtained
to document
a satisfactory
reduction
and
rule out any associated
fractures.
The care after
reduction of an initial dislocation is controversial.
We
would like to know what role post-reduction
immobilization and rehabilitation
play in limiting the incidence of recurrent
instability,
which is the most
common complication
of an acute traumatic anterior
dislocation. Unfortunately
the literature offers varying
opinions regarding the value of immobilization
and
rehabilitation.
In Rowe’s classic study of over 300
anterior dislocations, the redislocation
rate in patients
under 20 years of age was 945:. This followed
immobilization
of 3 weeks or less. Hovelius recently
compared a group immobilized
for 3-4 weeks in a
sling and swathe to an early motion group which used
a sling only as needed for comfort. He found that
immobilization
for 3-4 weeks did not reduce the
recurrence
rate and that age at the time of initial
dislocation was the most important factor with regard
to prognosis. ‘(’ During his 5-year follow-up, there were
two or more redislocations
in 55% of patients 12-22
years old, in 37:/i of those 23329, and only 12% of those
30-40 years of age.” Simonet and Cofield,”
found
that 56% of patients restricted from resuming sports
activity for 6 weeks or greater had satisfactory results,
compared with only 157; of patients restricted less
than 6 weeks. The recurrence rate was 820/, in athletes,
compared to 3076 m non-athletes.
Yoneda reported
that in those treated with 5 weeks of immobilization
and subsequent
internal
rotator strengthening,
the
redislocation
rate was only 17%. I3 In a study at the
US Naval Academy, Aronen et alI5 reported only a
257; redislocation
rate with a 3-year follow-up in a
group treated with muscle strengthening
and activity
restriction until the rehabilitation
goals were met.
We presently immobilize
the young athlete in a
sling for comfort only and then begin early motion
and shoulder strengthening,
emphasizing
rotational
strengthening.
We also limit the athlete from placing
the arm in the provocative
position of abduction
extension and external rotation for 6-8 weeks following the dislocation.
Return to athletics is permitted
when the patient achieves a full painless range of
motion,
normal
strength,
and has a negative
or
minimal
apprehension
sign. There are patients
in
whom the apprehension
sign remains positive.
Recurrent anterior instability. Recurrent anterior instability is a very common reason for presentation.
As
we discussed earlier, recurrent
anterior
instability
needs to be sub-classified in order to adequately discuss
its diagnosis and treatment.
Recurrent anterior instability may be traumatic or
atraumatic.
It may be voluntary or involuntary,
and it
may present as recurrent dislocations,
subluxations.
or both.
History. The patient
usually volunteers
that ‘my
shoulder comes out’. The patient can usually tell if the
THE SHOULDER
shoulder dislocates, subluxes or does both. The patient
is often confused as to the direction of instability
so
certain questions are important.
The position of the
arm at the time of the symptomatic
instability
is
extremely important.
A patient with instability
when
the shoulder
is abducted,
externally
rotated
and
extended,
almost certainly
has anterior
instability.
While one with instability with the shoulder in forward
flexion, adduction and internal rotation in all likelihood has posterior instability.
Complaints
of instability while carrying heavy loads, with downward traction
applied, are generally related to inferior instability.
A
history of apprehension
is also a very important clue.
The apprehensive
patient is fearful of putting the arm
in a certain position because it ‘may go out’.
Patients
with recurrent
anterior
instability
are
therefore placed into different groups based on their
presentation.
Recurrent traumatic imoluntary
instabilit>l
1. Recurrent dislocations. This group represents those
patients with a normally functioning
shoulder, until
with an inciting
event, a dislocation
occurs. The
dislocation
usually requires
reduction
by another
individual, and is generally quite painful. These events
may be frequent or infrequent,
and may gradually
occur with less and less trauma as the shoulder’s
stabilizing mechanisms
become more incompetent.
2. Recurrent subluxations. The patient with recurrent
subluxation
who has never had a documented
dislocation can present a diagnostic
challenge.
These
patients generally present in one of two ways.
Some present with a classical ‘dead arm syndrome’.
They may give a history of pain, clicking, and grinding
in the shoulder. The ‘dead arm’ feeling has been
described in different ways. It can be a ‘sudden sharp
paralyzing
pain’ (Rowe) or a feeling of heaviness,
numbness or weakness associated with the shoulder
positioned in abduction, external rotation and extension. The patient may volunteer
a history of the
shoulder slipping out of place.
The second type of presentation
in those with
recurrent subluxation
presents more of a diagnostic
challenge. These patients present with a chief complaint of pain in the shoulder. They usually have pain
when performing overhead activities suchas throwing.
These patients are usually young and have primary
anterior instability
with secondary tendonitis
due to
impingement
or eccentric overload. Physical examination findings are important in the proper diagnosis
of patients in this category.
3. Recurrent dislocation with subluxation. This group
represents patients with both recurrent dislocations
and subluxations.
Due to the frequent episodes of
subluxation they are often quite disabled.
4. The ‘apprehension shoulder’ plus 1. 2, or 3. Finally
there is a group of patients who although having an
underlying
instability
problem, present with what is
best described as an ‘apprehension
shoulder’. They
_
live a f’earful existence that their shoulder will ‘go out’
if their arm goes into the position of abduction
and
external rotation. They avoid this position and may
become significantly
disabled. They often refuse to
participate
in certain
sporting
and work related
activities.
They inevitably
develop a limitation
ot
external rotation.
sometimes
even with the arm at
their side.
The physical examination
should include a general
appreciation
of the musculo-skeletal
system and then
more specifically. the involved and uninvolved
shoulders. Features such as an ability to touch the volar
forearm with the thumb, hyperextension
of the elbows
and knees, hyperextension
of the fingers to bring them
parallel to the dorsal forearm. and an ability to place
the palms flat on the floor with the knees extended are
important indicators of generalized laxity. These signs
are more common in patients with multi-directional
and atraumatic
instabilit).
Instability
ways.
of the shoulder
may be manifest
in several
I. Apprehension
signs or provocative testing suggestive of an underlying instability pattern.
3 Excessive translation
of the humeral head within
_,
the glenoid socket.
3. The obvious presentation
of a dislocation
or the
demonstration
on behalf of the patient
of an
instability pattern.
The positive ‘apprehension
sign’ is most commonly
applied to anterior uni-directional
instability
of the
shoulder. In the sitting position this is performed with
the examiner behind the patient stressing the arm in
external rotation and abduction.
With the arm in this
position.
controlled
levering of the humeral
head
anteriorly.
while palpating
directly
anteriorly
to
prevent .I dislocation, will eiicit a feeling of apprehension from the p:ltient (i.e. ‘Crank Test’). This apprehension is manifest by muscle contraction
to resist
movement, or by an obvious look of apprehension
on
the patient’s face. or by the patient stating that the
maneuver
reproduces
his functional
instability
and
that they fear the shoulder will ‘come out’ if the stress
is continued.
Paln may be present, but alone it does
not constitute a positive apprehension
sign.
The ‘apprehension’
maneuver
may also be performed with the patient supine (i.e. ‘Fulcrum Test’).
The shoulder joint is positioned
on the edge of the
table. which acts as a fulcrum, with the body providing
the counterweight.
In this position progressive external rotation, abduction
and extension may elicit an
‘apprehensive’
response.
_.__-.
Trmslution
__-__
SHOULDER
INSTABILITY
-_
..___
247
__
of'the gleno-humeral,joint
Assessment and grading of the amount of anterior and
posterior translation of the humeral head in the glenoid
socket is an evolving science. It is often difficult, even
with the patient anesthetized,
to accurately determine
anterior and posterior translation.
We use a ‘load and
shift’ test which is performed with the patient both
sitting and supine.
With the examiner sitting to the side and behind
the seated patient, the patient’s scapula is fixed with
one of the examiner’s
hands. The examiner
then
grazps the humeral head from the lateral side, loading
it medially Into the glenoid fossa to insure appropriate
reduction and a ‘neutral’ position. The examiner then
translates the humeral head posteriorly and then back
to the glenoid, this is performed several times until the
examiner is sure of the degree of posterior translation.
After loading the humeral head into the glenoid, the
humeral head is translated anteriorly to determine the
anterior translation.
The patient’s arm is at his side
during this test in the neutral position. The ‘load and
shift’ test is then performed with the patient supine.
With the patient supine the arm can be placed in
different poGtions to assess the integrity of the various
component\
of the capsule-labral
complex.
Inferior translation
is determined
with the patient
seated with his arm at his side. The examiner applies
traction to the arm. pulling the humeral head inferiorly.
With his other hand the examiner places his thumb
and Index finger anterior and posterior to the acromion. pushing the humeral head inferiorly
;I visible
‘sulcus sign’ may he present if there i\ significant
inferior translation.
It i\ Important to grade the amount of’ translation
compare it to the non-involved
shoulder.
Cir-ade 1
Grade 7
and
Translation
of the humeral head up the
glenoid face to the glenoid rim.
Translation
of the humeral head over the
glenoid rim, with spontaneous
reduction
upon release of the applied ctress may
occur but is still Grade 2.
In addition to using the above grading system for
anterior. posterior and inferior translation.
we also
document the centimeters of inferior translation
with
applied stres\.
In addition to grading the translation
the examiner
should attempt
to determine
if the translation
is
symptomatic.
If the patient complains of instability.
pain or a click with translation
in a certain direction.
and appreciates that as part of his symptom complex,
then the diagnosis is clearer.
Relowtion
test
The ‘relocation test’ described by Jobe and Fowler IS
a helpful adjunct in thediagnosisofanterior
instability.
It is particularly
helpful in cases where there is only
248
CURRENT
ORTHOPAEDICS-MINI-SYMPOSIUM:
anterior subluxation
present or when the patient has
impingement
and rotator cuff tendonitis
with underlying anterior instability.
In these cases the apprehension sign may be negative, or cause only pain but not
apprehension,
and translation may be normal.
The ‘relocation test’ is performed with the patient,
positioned supine as described for the ‘apprehension’
maneuver. The ‘apprehension’maneuver
with the arm
in abduction and external rotation is performed. The
examiner
should document
any apprehension
and
pain elicited, and the amount of external rotation
achievable. Next the same maneuver is performed but
with his other hand the examiner applies a posteriorly
directed force to the proximal humerus. This force
may ‘relocate’ the humeral head preventing
anterior
subluxation.
This may eliminate apprehension
and/or
pain and may increase the degree of external rotation
achievable.
These findings may be consistent
with
anterior subluxation.
We have modified this test by suddenly releasing
the posteriorly direct force-the
‘release test’-to
see
if there is the immediate onset of apprehension
and/
or pain.
Jobe has also described
a modification
of his
maneuver
which we call an ‘augmentation
test’. In
this case an apprehension
maneuver is performed. but
an anteriorly directed force is applied to the posterior
aspect of the proximal humerus, thus increasing any
existing anterior subluxation. This test may be positive
for an increase in apprehension
and/or pain.
Management ofchronic recurrent traumatic involuntary
anterior instahilit~
The treatment options of any shoulder instability are
acceptance of the disability, rehabilitation,
or surgical
stabilization.
The indications for surgery are based on the patient’s
symptoms and disability. The disability is dependent
on the frequency
of the dislocations,
the ease or
difficulty of reduction, the age and activity requirement
of the patient, and the presence of subluxations
and/
or apprehension.
The patient with frequent subluxations and apprehension
with his arm in abduction/
external rotation is often quite disabled, whereas one
who dislocates every 5 years or so, without intervening
subluxation
and/or apprehension
may function quite
well without significant disability.
If one is not very disabled then we would recommend
a non-operative
approach. Rotator cuff, trapezius, and
serratus anterior strengthening,
along with avoidance
of the provocative
position may be successful. Like
many others, however, we have not found rehabilitation to be very successful in young athletic patients
with recurrent anterior instability.
Surgical options. The main goals of surgery are to
stabilize the shoulder and maintain
a full, pain-free
range of motion. We feel that these goals are best
achieved by correction
of any pathology-i.e.
‘the
essential lesion or lesions’-found
at surgery.
THE SHOULDER
Many different procedures have been described, but
many are extra-articular
procedures which ignore the
existing pathology and distort the normal anatomy.
Many times a procedure is successful in preventing
recurrent instability at the expense of a significant loss
of external rotation, which may rarely lead to the
development
of osteoarthritis.
The different procedures can be divided into:
1. Bony procedures
(osteotomies
of the glenoid
humerus, bone block procedures)
2. Musculo-tendinous
operations
3. Capsulo-labral
operations
4. Combinations
and modifications
of the above.
or
While we do not wish to describe
all of the
procedures in detail, we feel that in a review article
such as this we should comment on some of the more
commonly
performed
procedures.
Rockwood
in a
review of 53 studies. with 3332 cases, found an average
recurrence
rate of only 37$’ 5 He found that the
problem was not the rate of recurrence but often poor
function. The recurrence rates were 3.1 “/n for a PuttiPlatt, 4.1:; for a Magnuson Stack, 1.79; for a Bristow
and 3.57; for a Bankart respectively.?
Putti-Platt. The Putti-Platt
has been used for many
years, initially independently
by Putti and Platt, for
recurrent anterior instability.
It has undergone many
modifications,
but in essence, it involves shortening
and overlapping
of the subscapularis
and anterior
capsule. While this procedure
has generally
been
reasonably successful in preventing
recurrent dislocations, it is almost always accompanied
by a significant
loss of external rotation.
In a long-term review of 132 Putti-Platt procedures,
Morrey and Janes, ih found 18 recurrent dislocations
for a recurrence rate of 13.6?;. While this recurrence
rate is higher than that reported by other series, their’s
represented reasonably long-term follow-up.
In a functional
analysis of Putti-Platt
procedures,
Regan et al i’ found a 21.8” deficit of external rotation
with the shoulder at neutral and a 28.8’ deficit with
the shoulder at 90“ of abduction.
None of the eight
patients
who were overhand
or throwing
athletes
returned to their pre-operative
level following surgery.
Leach et ali” reported a 12-19” loss of external rotation
but not functional compromise.
While the Putti-Platt
procedure
may effectively
limit anterior instability,
we feel that it should not be
used as a routine procedure. In addition to limiting
external rotation and compromising
overhand function, the author has seen several patients who have
developed osteoarthritis
following an excessively tight
Putti-Platt repair.”
Magnuson-Stack.
In the operation devised by Magnuson and Stack, the anterior capsule and subscapularis
tendon are tightened by advancing
them laterally on
the humerus. As with the Putti-Platt
this procedure
although reasonably effective in eliminating
anterior
instability.
is often accompanied
by an undesirable
loss of external rotation.
__
Miller et al’” in a review of 29 patients found five
post-operative
dislocations,
a redislocation
rate
of 17”“. They also found a 25” lack of external rotation and found that only 52”/, returned to their preinjury level of competitive
athletics.
Karadimos,
in the largest single series of Magnuson-Stack
procedures ( I54 patients) reported only a ?“,I recurrent
rate.:”
Regan et al“ found a deficit of 4.7. of external
rotation with the shoulder at neutral and a 6.4” deficit
with the shoulder at 90” of abduction. They found that
three of eight athletes returned to their pre-operative
level of throwing and overhand activity.
Despite the f-act that the senior author (RJH) had
had excellent results with a modified Magnuson-Stack
procedure, we rarely perform it anymore. preferring
instead to address and repair the pathology.
Bristmc,. In 1954 Latarjet described
transfer of the
coracoid process through the subscapularis
tendon as
a method of treating anterior instability.
Helfet in
1958 described a transplant
of the coracoid with the
attached conjoined tendon to the anterior surface of
the glenoid, through a tranverse rent in the subscapularis muscle. He termed this the Bristow procedure.
Mead in 1964 described fixing the bone block with a
screw.
It has been proposed that the Bristow operation is
effective because the coracoid acts as a bone block
impeding
anterior
redislocation,
because the cnnjoined tendon acts as a dynamic
sling holding the
humeral head posteriorly when the arm is abducted
and externally rotatecl, and thirdly because it prevents
the lower portion of the subscapularis
from riding
superiorly with abduction, thus reinforcing the anteroinferior capsule.”
Many authors have reported excellent result with
the Bristow procedure.
Hill et al” found only two
post-operative
dislocations
following 83 procedures
performed for anterior dislocation,
but found that five
of 24 patients operated on for anterior subluxations
continued to have subluxationspost-operatively.
Their
redislocation
rate was similar to that reported by
Allman who found no redislocations
in 50 cases,
Collins and Wilde who also had no redislocations
in
50 cases, and Sweeney et al who had a 3”” redislocation
rate in 97 cases. Hovelius et al in a review of I I3 cases,
found a redislocation
rate of 6”, and a resubluxation
rate of 7”,,. Torg et al reported
a post-operative
instability
rate of X.5”,, in a series of 207 modified
Bristow procedures.”
Unfortunately,
most authors
have reported significant
losses of external rotation
and diminished
athletic function following the procedure. Hill et al” found a mean loss of external rotation
of 12.6 and found that only six of 41 patients could
throw in the same manner as before injury. Regan et
al” found a 12.2” deficit of external rotation with the
shoulder at neutral and an 11.6” deficit with the
shoulder at 90 of abduction.
In their series only three
of nine throwers returned to their prior performance
level. Torg et a1 in a large series found that only 16””
._~ ---
SHOULDER
INSTABILITY
-_--
‘49
of athletes whose dominant arm had been operated on
returned to their pre-injury level of throwing.”
We do not recommend
routine use of the Bristow
procedure
due to the potential
problems
with the
screw,’ ’ potential
injury to the musculocutaneous
nerve, marked distortion of the normal anatomy. and
loss of external rotation. However, it may have a role
Mhen used in a situation in which there has been a
significant bony loss of the anterior gelnoid rim.
Budart
prowdurr.
The Bankart
procedure
is a
capsular repair first performed by Perthes in 1906. It
was popularized by Bankart’s article in 1939 describing
the repair of the anterior capsule to the hone of the
anterior glenoid through drill holes with the use of a
suture. A Bankart repair or a modification
of it is
currently the ‘gold standard’to which other procedures
should be compared.
The main advantage
of the
Bankart is that it directly addresses the pathology
perpetuating
the instability, as a Bankart lesion is the
most common pathology associated
with traumatic
anterior instability.
The procedure
:~lso allows the
surgeon to modify the case intra-operatIvei?
and
pert’orm an anterior capsulorrhapy
or a capsular shift
if only capsular redundancy
is found. The Bsnkart
procedure cim also be performed without causing a
significant loss of external rotation. Rowe has been a
major proponent of the Bankart or modified Bankart
repair. Rowe and Zarinsi
reported ;I series of 50
shoulders with anterior subluxation.
A Bankart procedure was performed in the 32 shoulders In which a
Bankart lesion c\as found, and a modified Bankart
repalr (capsulorrhapy)
was performed in the remaining
IX p;itients who had capsular redundancy
Good or
excellent result were obtained
in 94O, oi‘ the caseh.
HoLelius et al found a 200 redislocation
rate Clfter the
Bankart procedure compared with ;i 19”,, redi&~cation
rate after the Putti-Platt.
Several authors have reported good function and
only small deficits of external rotation following a
Bankart procedure.
in Rowe’s series there were ??
dominant
shoulders, with 21 of these (64”“) able to
return to forceful throwing and participate
In sports
and work.
Author’.~ prrfewti
approach.
Our philosophy has now
evolved such that we utilize an approach that allows
dealing with any pathology present at the time of
surgery. This is our current method despite consistent
result\ in the past with a modified Magnuson-Stack
procedure.
We utilize two varieties of soft tissue repair based
upon ;tccess to the shoulder joint.
I. Our first approach
is almost identical
to that
recently described by Thomas and Matsen. ‘1 Through
a standard
delto-pectoral
approach
we make an
incision through the subscapularis
tendon and capsule
I cm medial to the biceps tendon in a vertical fashion.
The joint is then explored both visually and by direct
palpation to assess the pathology. If there is a detached
labrum it 1s re-attached through drill holes to the bony
glenoiti
rim. If the capsule
is stripped
with a
250
CURRENT
ORTHOPAEDICS-MINI-SYMPOSIUM:
degenerative
labrum the capsule is sutured down to
the glenoid
rim making
sure that tethering
the
overlying subscapularis
with sutures is avoided. If
anterior capsular redundancy
is present, the capsule,
and sometimes subscapularis
are shortened and tensioned, ensuring 20” of external rotation is obtained at
the completion of the procedure.
2. The second technique
is more technically
demanding but allows for more direct capsular plication.
This approach involves incising through the subscapularis tendon in a vertical fashion separating it from
the underlying
capsule. A ‘T’ shaped incision based
laterally
is made through
the capsule
with the
horizontal arm of the ‘T’ extending medially to the
glenoid. The pathology is then addressed accordingly,
either repair of the labrum and/or capsule to the bony
glenoid as above, or plicating the two flaps of capsule
in a cruciate fashion (i.e. an anterior capsular repair)
is performed. The advantage of this approach is that
the subscapularis
is not shortened.
We have uncommonly
used a subscapularis
splitting
approach,
as popularized
by Jobe, in throwing
athletes. This may allow earlier rehabilitation
and less
restriction of external rotation, as yet unproven.
Controversies related to anterior instability
and impingement
As mentioned
above, young athletes with anterior
subluxation
often present with pain and symptoms
related to impingement
and rotator cuff tendonitis.
The patient
with impingement
and instability
is
generally a young overhand or throwing athlete.
The primary pathology is either congenital capsular
laxity or acquired capsular laxity from the frequent
stresses incurred during the throwing motion. The
capsular laxity allows increased humeral translation,
resulting in fatigue and eccentric injury to the rotator
cuff and parascapular
muscles. Muscle dysfunction
and fatigue lead to loss of the normal depressor effect
of the rotator cuff, allowing the humeral head to
migrate proximally
and anteriorly,
where impingement on the overlying coraco-acromial
arch is possible.
Physical findings
include positive
impingement
signs, but signs of subluxation
are often subtle. The
apprehension
sign may be positive, but often elicits
only pain. The relocation test is often helpful in this
case, usually relieving the pain brought on by the
apprehension
maneuver.
Often an exam under anesthesia along with arthroscopy
of the shoulder are
helpful in making the diagnosis.
The initial treatment
is a conservative
program
emphasizing
rotator cuff and parascapular
muscle
strengthening.
In most, this program is successful, but
if surgery becomes necessary it may be prudent to
address the instability.
An anterior cruciate capsulorrhaphy or a Bankart
repair in the presence of a
Bankart lesion is usually our recommended
approach.
Subacromial
decompression
may be unsuccessful
if
performed
without
addressing
the instability,
yet
THE SHOULDER
sometimes
it is a first step to try, as it is a lesser
procedure and may eliminate symptoms.
Arthoscopy. Diagnostic arthroscopy particularly as an
aid in the diagnosis of subtle instability,
has a role in
the management
of anterior instability.
Arthroscopy
allows inspection of the anterior glenoid rim, capsularlabral complex, the rotator cuff, and the posterior
humeral head. A Bankart lesion, labral damage, or a
Hill-Sachs lesion suggest anterior instability.
In those
with associated rotator cuff tendonitis
and impingement one may find a partial thickness, joint surface
cuff tear suggestive of eccentric injury, or subacromial
changes suggesting impingement.
The role of arthroscopy in anterior reconstruction
is
still undefined. Johnson, Caspari, Morgan and Matthews have reported variable results from arthroscopic
capsular-labral
repair. Morgan reported on 25 patients
with recurrent
anterior
dislocations
treated
with
arthroscopic
suturing
of a Bankart
lesion. At 17
months follow-up, there were no instances of recurrent
instability.”
Matthews et alZb reported on 25 patients
with recurrent anterior instability treated with arthrostopic staple capsulorrhaphy.
Five patients
were
reoperated on for pain/or recurrent instability.
Johnson has also reported about a 20% failure rate following
arthroscopic
staple capsulorrhaphy.
Caspari has reported improved results using an arthroscopic
technique utilizing sutures to repair the capsular-labral
complex.
Presently we feel that open procedures remain the
treatment of choice. However, with better instrumentation, such as biodegradable
screws and staples
presently being evaluated, further experience, longer
follow-up and careful comparison
with traditional
open techniques,
arthroscopic
stabilization
may ultimately become the treatment of choice in some cases.
Recurrent atraumatic anterior inooluntary instabilit)
The basic assessment and management
of atraumatic
instability differs little from traumatic instability. This
group obviously presents with a different history. The
initial dislocation
or subluxation
occurs without a
significant traumatic event, often occurring during the
acts of throwing or swimming.
The important difference from traumatic instability
is that the pathology or ‘essential’ lesion is usually not
a Bankart lesion. These patients usually have capsular
laxity. either congenital
or acquired, and only occasionally have a Bankart
lesion. There is often a
component
of multi-directional
instability
in this
group.
The treatment
differs in that we recommend
a
longer trial of conservative management,
emphasizing
rotator cuff and parascapular
muscle strengthening.
If
conservative
treatment fails then a specific capsulorrhaphy, addressing the laxity is indicated. In general
we prefer an anterior cruciate type capsulorrhaphy,
sometimes in conjunction
with an inferior capsular
shift. The failure rate of extra-articular
procedures
SHOULDER
such as a Bristow, Putti-Platt.
of concern in this group.
or Magnuson-Stack
is
Postrrior dislocation.
Traumatic
dislocations
are rare,
accounting
for only about 2”” of all traumatic
dislocations. The diagnosis is often missed initially.
In a review of 41 locked posterior dislocations
by
the senior author,‘the correct diagnosis was made
between
I and 6 weeks after injury in 13 cases,
between 6 weeks and 6 months in 12 cases, and after 6
months in I6 cases. The mechanisms of injury included
motor cehicle accidents (16 cases), seizures (11 cases).
electro-shock
treatments
(eight cases), and alcoholrelated injuries
(six cases). Physical
examination
revealed a loss of external rotation, with an average
internal rotation deformity of 40”. There was also a
loss of supination.
The axillary X-ray was diagnostic
in all cases. but had not been obtained initially in any
case. A fracture of the lesser tuberosity seen on an AP
radiograph is also an indication
that there may be a
posterior dislocation.
If a traumatic posterior dislocation in the absence
of an impression defect is diagnosed acutely. management consists of a closed reduction and immobilization
in a spica cast with the shoulder externally rotated and
extended.
The treatment
of a locked posterior dislocation
depends on the duration of the dislocation and the size
of the humeral head defect. The guidelines
are as
follows :
I. Closed reduction
~-Duration less than 6 weeks and
Defect less than 20”,
A.
7 Lesser Tuberosity Transfer-(Modified
McLaughlin
Procedure)
~~Duration less than 1 year and
-Defect 20 50”. of humeral head
3. Hemlarthroplasty
Duration greater than 1 year and/or
Defect greater than 50”,,
If a hemiarthroplasty
is performed it should be placed
in neutral version rather than retroversion
to decrease
the incidence of postoperative posterior instability.
Rtwrrmt
po.stcvYrw .suh/u.wtion. Posterior instability
is
usually subluxation rather than dislocation and seldom
requires reduction. Ocassionally there is the history of
a traum..itic injury. but more commonly
posterior
subluxation
results from overuse. The patient often
complains
01‘ pain and instability
with his arm in
forward
f&ion.
adduction
and internal
rotation,
Classitication
Includes habitual, voluntary and involuntary variants.
Physical findings include increased posterior translation. and rarelv a positive posterior apprehension
sign performed
with the arm in forward flexion,
adduction, and internal rotation. The patient is often
able to demonstrilte
the subluxation
with provocative
INSTABILITY
251
positioning
and/or muscle contraction.
A small percentage of these patients are psychiatrically
disturbed.
Treatment
consists
of prolonged
non-operative
management.
Rotator cuff strengthening.
stressing the
external rotators and parascapular
muscles is emphasized.
Posterior surgical reconstructions
are far less successful than anterior procedures.
In a review by the
senior author,‘X the recurrence
rate was 50”” in 26
patients operated on for recurrent posterior subluxation. Our preferred posterior reconstruction
is a softtissue procedure
including
posterior
capsular
and
infraspinatus
shortening.
We use a spica cast postoperatively and proceed cautiously with rehabilitation.
With our recent surgical changes. results are much
improved.
Mlriti-tlirc~c,tional instabilit?,
Multi-directional
instability (MDI) was introduced as
a concept by Neer in 1980.” Since that time it has
been recognized as a much more common problem
then previously
realized.
The hallmark
of multidirectional instability if symptomatic
inferior instability In association
with anterior
and’or posterior
instability.
Neer has taught us that the etiological
factors
contributing
to MD1 include various combinations
of:
1. Repetitive overuse
._.
3 Inherent ligamentous/capsular
3. Major traumatic injuries
laxity
MD1 is seen in athletes as well as sedentary individuals.
Proper detection depends on suspecting the possibility of MDI. The patient often complains
of the
shoulder ‘slipping down’ while carrying heavy loads.
In addition, the patient may complain of anterior and/
or posterior instability with the arm in the respective
pro\ ocative position. Many patients with MD1 present
with a chief complaint of pain. Often the patient has
problems with the opposite shoulder or instability of
other joints.
The hallmark of MD1 is a positive sulcus sign as
described above. In addition there is increased anterior
and posterior translation.
Signs of generalized
ligamentous laxity as described
above are frequently
present.
The treatment again consists of prolonged internal
and external rotator strengthening.
These patients
often have scapular dysfunction
and winging. and
require parascapular
muscle strengthening.
If non-operative
treatment fails then surgery should
be considered. Standard operations for uni-directional
anterior or posterior dislocations
may fail to correct
MD1 because the pathology is not corrected. The main
pathology is increased joint volume due to an enlarged
inferior axillary capsular pouch. The standard procedure may not correct inferior instability
and may
displace the head to the opposite side leading to
arthritis. Neer”’ introduced the inferior capsular shift
252
CURRENT
ORTHOPAEDICS-MINI-SYMPOSIUM:
for MD1 and this is the procedure that we perform.
This is generally performed from an anterior approach,
but in some cases of posterior-inferior
instability,
it is
performed through a posterior approach in conjunction with an infraspinatus
shortening.
Summary
The proper diagnosis and classification
of shoulder
instability
allows the physician
to recommend
the
appropriate treatment. Rehabilitation
is the preferred
treatment for posterior subluxation
and MDI. Recurrent anterior instability generally requires surgery for
optimal function. Surgery can be very successful in
preventing instability and allowing a normal range of
motion if the pathology
causing the instability
is
corrected.
References
1990; W
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THE
SHOULDER
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