Anineteen-year-old, left-hand-dominant man presented to our clinic with a
two-year history of intermittent clicking and pain in the left shoulder. The
symptoms started after he sustained a blow to the anterior aspect of the left
shoulder while trying to tackle another player during a high-school football
game. The patient reported that the left shoulder had slipped out of place and
then spontaneously returned to its normal position. Since then, he continued
to experience intermittent clicking, pain, and "looseness" of the
shoulder during sports and normal daily activities. The pain was localized to
the posterior aspect of the shoulder, and it was exacerbated by forward
elevation of the arm to shoulder height and by any throwing motion. The
patient recalled five additional occasions when the shoulder had slipped out
of place and spontaneously reduced. After each of these episodes, the patient
experienced pain and limited range of motion, which resolved over the course
of several days. The symptoms progressively worsened over a two-year period,
and eventually they prevented him from participating in sports. After the
initial clinical evaluation, he was managed for three months with a supervised
exercise program to strengthen the deltoid and rotator cuff muscles, and he
refrained from participating in any sports activity during this period. Rest
and physical therapy did not alleviate the symptoms.
On physical examination, the patient had equal passive and active range of
glenohumeral motion with normal scapulothoracic rhythm in both shoulders.
Forward elevation was 170°, and external rotation was 70° with the arm
by the side and 105° with the shoulder at 90° of abduction. Internal
rotation was to the T8 level. There were no motor or sensory deficits in the
upper extremity. Tenderness was produced by palpation along the posterior
glenohumeral joint line and by translating the humeral head posteriorly. No
increase in anterior or posterior humeral head translation was appreciated
compared with the contralateral shoulder. The apprehension sign was negative,
and the hyperlaxity signs in the hands and elbows were negative.
Radiographic evaluation of the left shoulder revealed no bone or joint
abnormalities. A magnetic resonance arthrogram revealed multiple abnormalities
in an unusual distribution, which were difficult to interpret under a unifying
diagnosis. These abnormalities included a posterior labral tear and an unusual
deformity of the posterolateral part of the humeral head extending inferiorly
to the neck (Figs. 1-A, 1-B,
and 1-C). Additionally, subtle
changes in the anterior labrum superiorly and the infraspinatus were
interpreted as a SLAP (superior labral anterior to posterior) lesion and a
sign of posterior impingement. Overall, the findings were thought to be
related to a combination of multidirectional instability and posterior
impingement.
Given the persistence of the symptoms, the lack of improvement with
nonoperative treatment, and the findings on the magnetic resonance arthrogram,
the patient underwent arthroscopy of the left shoulder. He was placed in the
beach-chair position, and the procedure was performed with the patient under a
combined scalene block and general anesthesia. A 30°, 4.5-mm arthroscope
was introduced to the glenohumeral joint through a posterior portal.
Arthroscopic examination demonstrated a minor cleavage crack in the
anteroinferior aspect of the glenoid labrum with a similar finding in the
posteroinferior part of the labrum, but there was no detachment of the labrum.
A complete detachment of the posterior glenohumeral ligament and capsule at
the humeral insertion site, which extended from the posterosuperior to the
posteroinferior portions of the humeral neck, was evident and appeared to be a
chronic injury. There was an increase in the bare area around the posterior
portion of the humeral neck but with no evidence of a Hill-Sachs lesion. The
biceps, subscapularis, supraspinatus, and infraspinatus tendons were found to
be intact. No other intra-articular abnormalities were found. The arthroscope
was then switched to an anterior portal, which allowed a better view of the
magnitude of the posterior ligament and capsule detachment from the humeral
neck (Fig. 2).
Arthroscopic repair of the posterior humeral avulsion of the glenohumeral
ligament and capsule was then performed (Figs.
3-A,
3-B, and 3-C). A 30°,
4.5-mm arthroscope was placed into an anterior portal, and instrumentation for
the repair was inserted through two posterior portals. The posterior part of
the humeral neck was cleaned of capsular remnants and burred to bleeding bone
at its articular margin. Reattachment was performed with use of four 3-mm
bioabsorbable suture anchors. Each suture was passed through the posterior
capsule and ligament with use of a suture punch and was tied with an
arthroscopic knot-tying technique. An anatomic repair was achieved.
Postoperatively, the shoulder was immobilized in a gun-slinger brace with
25° of abduction and 0° of arm rotation for five weeks. Thereafter,
the patient started physical therapy consisting of passive range-of-motion
exercises, including forward flexion and external rotation only. At eight
weeks after surgery, the physical examination demonstrated that internal
rotation and cross-body adduction were limited to 50% of that of the
contralateral shoulder. Posterior capsular stretching exercises, including
internal rotation and cross-body adduction, were introduced to the therapy
program along with active exercises to strengthen the rotator cuff, deltoid,
and scapulothoracic muscles. At sixteen weeks, the patient had no pain,
clicking, or subjective symptoms of instability. On examination, he had no
tenderness and had equal passive and active range of motion. Forward elevation
was 170°, and external rotation was 70° with the arm by the side and
105° with the shoulder at 90° of abduction. Internal rotation was to
the T8 level. Glenohumeral translation with the load and shift tests and the
jerk test was equal bilaterally. There was a negative apprehension sign and
full muscle strength measured by manual muscle testing. At the most recent
follow-up evaluation, twelve months after surgery, he was able to complete all
activities of daily living and to participate in recreational sports,
including football and basketball, without any symptoms or limitations.
Posterior instability is an infrequent cause of shoulder disability in
younger patients. Several factors, such as capsular laxity, disruption of the
posterior capsulolabral complex (a posterior Bankart lesion), and injury to
the coracohumeral and superior glenohumeral ligaments (a rotator interval
lesion), are associated with posterior
instability1,2.
Failure of the glenohumeral capsule at its humeral insertion has not been well
recognized as a cause of recurrent posterior
instability1,2.
The patient in the present report sustained a posterior humeral avulsion of
the posterior portion of the inferior glenohumeral ligament. The most likely
mechanism of injury for this lesion is the posteriorly directed force applied
to the front of the shoulder. Bigliani et al. defined the tensile properties
of the posterior elements of the inferior glenohumeral ligament using a
cadaver model7.
Tensile failure occurred at the humeral insertion site in five of the sixteen
specimens, at the glenoid insertion site in four specimens, and at the
midsubstance in seven specimens. On the basis of that study, one could assume
that the humeral capsular insertion site should be a more frequent site for
ligament failure than has been reported in the clinical literature.
A preoperative diagnosis of a posterior humeral avulsion of the inferior
glenohumeral ligament requires a good quality magnetic resonance arthrogram
and a high index of suspicion. Understanding the appearance of this lesion on
a magnetic resonance arthrogram is difficult, but it contributes substantially
to making an accurate diagnosis. The appearance of this lesion on magnetic
resonance imaging has been reported
infrequently5,6,8.
Laurencin et al. reported on a twenty-one-year-old patient who experienced
posterior instability after a posteriorly directed blow to the
shoulder5. Magnetic
resonance imaging failed to reveal the reason for his symptoms. Diagnostic
arthroscopy performed six months after the injury demonstrated a
superior-lateral tear of the posterior glenohumeral capsule. No other lesions
were found. The tear was repaired through an open posterior approach, but the
results were not reported.
Hottya et al. reported on four patients with a posterolateral capsular tear
near or at the humeral
insertion8. These
soft-tissue disruptions were diagnosed with magnetic resonance imaging or
magnetic resonance arthrograms. All of these patients had a clinical diagnosis
of traumatic posterior instability. Additional findings included posterior
labral tears in three patients, damage to the teres minor tendon and/or muscle
in four patients, and a reverse Hill-Sachs lesion in two patients. Three of
the patients underwent shoulder arthroscopy, which confirmed the capsular and
labral damage found on the magnetic resonance imaging scan. Repair of the
capsular damage was performed in two patients. The postoperative results were
not reported.
Barr et al. recently reported on the magnetic resonance arthrogram findings
of humeral avulsion of the posterior portion of the inferior glenohumeral
ligament in a small series of
patients6. These
findings included capsular disruption along the posterior humeral neck as well
as outpouching of contrast with distortion of the normal posterior axillary
pouch. Only upon retrospective analysis were we able to identify avulsions of
the posterior portion of the inferior glenohumeral ligament on the magnetic
resonance arthrogram of the patient in the present report. The key findings
included frank capsular disruption along the posterior aspect of the humeral
neck, thickening of the retracted posterior band of the inferior glenohumeral
ligament, and distortion of the posterior axillary recess. The adjacent
osseous abnormality, originally interpreted as a Hill-Sachs lesion,
corresponded to the increased humeral bare area seen arthroscopically and was
consistent with the chronically retracted ligament and capsular deformity.
Posterior avulsion of the humeral attachment of the glenohumeral ligament
can occur alone or in combination with other derangements of the shoulder such
as a posterior Bankart lesion or a reverse Hill-Sachs defect. During
diagnostic arthroscopy, the posterior capsule and the junction between the
posterior capsule and the neck of the humerus should be performed through an
anterior portal. It is our opinion that, when found in a symptomatic patient,
the posterior humeral capsular and ligamentous detachment should be addressed
surgically, similar to its anterior
counterpart3,4.
In summary, posterior humeral avulsion of the glenohumeral ligament is an
important and possibly under-diagnosed cause of traumatic posterior
instability of the shoulder.