Athirteen-year-old male was referred to our clinic for evaluation of
recurrent dislocation of the right shoulder. The first injury occurred at the
age of eleven when he sustained a hyperabduction injury to the right arm while
wrestling. He had immediate pain in the right shoulder but did not seek
medical attention. He sustained the first dislocation of the right shoulder
while diving into a pool approximately six months after the initial injury.
Three months later, he sustained a hyperabduction injury and dislocated the
same shoulder while playing football. Each time, the dislocated shoulder was
reduced in an emergency room and was treated with immobilization in a sling
for a brief period of time. Three weeks before presentation to our clinic, he
dislocated the right shoulder while throwing a Frisbee. The patient was
otherwise healthy and did not have a history of steroid use, sickle-cell
anemia, Ehlers-Danlos syndrome, instability of other joints, or other medical
conditions.
At the initial office visit, the patient had full, pain-free range of
motion. He was neurovascularly intact with a positive anterior apprehension
sign2. He had a
grade-I sulcus sign and a negative posterior apprehension
sign2. He had no
signs of generalized ligament laxity according to the criteria of
Wynne-Davies3.
The plain radiographs had normal findings with no evidence of a Hill-Sachs
lesion. Radiographs from previous emergency-room visits confirmed a recurrent
anterior dislocation. A magnetic resonance imaging scan performed two weeks
before the office visit showed a normal humeral head and anterior labrum.
Because of the high rate of recurrence of anterior instability in this
age-group4-6,
the patient and his family opted to have surgical correction of the shoulder
instability.
Diagnostic arthroscopy was performed, with the patient in the lateral
decubitus position with five pounds of traction, and it confirmed the absence
of a Hill-Sachs or Bankart lesion. However, he was found to have an avulsion
of the anterior and inferior shoulder capsule from the proximal aspect of the
humerus, a lesion known as a humeral avulsion of the glenohumeral
ligaments7. An open
repair of this lesion was performed.
The patient was placed in the supine position, and the shoulder was
prepared and draped. An anterior deltopectoral approach to the shoulder was
used. The subscapularis muscle was split between its upper two-thirds and
lower third as described by Jobe et
al.8. The capsule
was found to be avulsed from the proximal part of the humerus inferior to the
split. Care was taken to avoid injury to the anterior circumflex humeral
vessels. Two absorbable suture anchors were placed at the junction of the
humeral head and neck. The first anchor was placed in an inferiorly directed
position, and the second anchor was placed in a transversely directed
position. The capsule was then sutured back to the proximal part of the
humerus with the suture anchors. The limit of external rotation after the
capsule was secured was 30° with the arm at the side and 90° with the
arm abducted. The patient was managed with a shoulder immobilizer, and no
complications, including infection or neurovascular compromise, were noted
immediately postoperatively or at the follow-up visits at ten days and four
weeks after surgery. Physical therapy was started ten days after surgery and
was uneventful. However, six weeks after surgery, the patient was found to
have limited range of motion of the shoulder in elevation (100° of
elevation) and rotation with the arm elevated 90° (10° of external
rotation). Plain radiographs made at that time showed faint subchondral
sclerosis of the humeral head (Fig.
1). A T1-weighted magnetic resonance imaging scan showed focal
edema and a classic subchondral crescent sign, characteristic of osteonecrosis
(Fig. 2). A T2-weighted image
of the same magnetic resonance imaging scan showed diffuse edema of the
proximal humeral epiphysis (Fig.
3).
After the treatment options were considered, the decision was made to treat
the patient nonoperatively. The patient was allowed to move the shoulder
within the limits of pain three months after surgery, and stretching, but no
strengthening, exercises were performed under the supervision of a physical
therapist. The patient was evaluated every three months with repeat
radiographs and magnetic resonance imaging scans. At one year, the humeral
head was normal on both the radiographs
(Fig. 4) and the magnetic
resonance imaging scans (Figs.
5 and
6). The patient had a full
range of motion and no pain at that time. Eighteen months after surgery, he
returned to athletic activity with no symptoms.
This report illustrates several unique aspects of shoulder instability.
First, the age of the patient at the time of the initial dislocation was
unusual. Although there are several reports of traumatic dislocations in
children as young as three years
old9,10,
a review of the liyterature revealed that traumatic instability in children is
uncommon7,11-13.
Second, humeral avulsion of the glenohumeral ligaments is an uncommon cause of
instability but should be considered for patients in this
age-group11,12,14-16.
To our knowledge, there are no reports in the literature describing humeral
head osteonecrosis as a complication of suture anchor placement in shoulder
surgery or as a complication of shoulder surgery in adolescents. The main
arterial supply to the humeral head is from the anterior and posterior humeral
circumflex arteries. In cadaver studies, the posterior humeral circumflex
artery has been shown to supply the posterior portion of the greater
tuberosity and the posteroinferior part of the humeral
head17. Conversely,
the anterolateral ascending branch of the anterior circumflex humeral artery
supplies the entire head and is recognized as the most important source of
blood supply to the humeral
head17. It is most
likely that one of the intraosseous branches of the anterior circumflex
humeral artery was injured during suture anchor placement, leading to the
development of osteonecrosis in our patient.
Another consideration, although unlikely, given the focal intraosseous
nature of the lesion, is that the injury to the blood vessel occurred during
the surgical exposure, despite our precautions to protect the vessels.
Humeral head osteonecrosis secondary to proximal humeral fractures has been
reported in the literature but mostly in
adults18-20.
Although most patients with three or four-part humeral head fractures
eventually progress to unrecoverable osteonecrosis, previous studies have
documented revascularization of the humeral head by means of creeping
substitution after osteonecrosis. Wang et
al.20 reported a
case of revascularization of the humeral head after osteonecrosis secondary to
a fracture dislocation in a ten-year-old boy. That patient began showing signs
of revascularization several months after the osteonecrosis was diagnosed, and
the authors reported that the humeral head completely revascularized with no
evidence of long-term sequelae at the follow-up examination two years after
the injury. In our patient, the osteonecrosis pattern and time to recovery
were consistent with revascularization of a necrotic humeral head as suggested
by Wang et
al.20.
During shoulder surgery, particularly in adolescent patients, the anterior
humeral circumflex vessels and their branches should be protected to avoid
injury. Given this potentially dangerous problem, suture anchors in the
proximal part of the humerus should probably be avoided in adolescents unless
absolutely necessary. In adolescent patients with prolonged pain or stiffness
after shoulder surgery, we recommend radiographic analysis to rule out this
uncommon complication, which in our patient resolved completely with
conservative care over six months.