- Discussion:
- multidirectional instability implies three-way subluxations or
dislocations either anteriorly, posteriorly, or inferiorly;
- these patients usually have no true Bankart lesion and incontrast patients
have a capacious axillary pouch;
- ref:
The Effect of
Variation in Definition on the Diagnosis of Multidirectional Instability of the
Shoulder.
- affects overhead throwing atheletes, gymnasts, swimmers;
-
stabilizers of the shoulder:
- in multidirectional instability,
static stabilizers may be stretched and
dynamic stabilizers may be atrophied;
- arthroscopic "drive-through" sign is usually present;
- associated conditions:
collagen
disorders
- diff dx: (conditions which can be confused w/ multidirectional
instability):
-
impingement syndrome
-
rotator cuff tear
-
thoracic
outlet syndrome
-
biceps tendinitis;
-
cervical
disc herniation
-
syringomyelia
- Syringomyelia presenting as shoulder instability. RR
Richards. Journal of Shoulder and Elbow
Surgery. Vol 1. 1992. p 155-161.
-
natural history:
-
A longitudinal study of patients with multidirectional instability of the
shoulder with seven- to
ten-year follow-up.
-
Exam:
-
exam for anterior instability;
- look for generalized hyper-elasticity (thumbs can be hyperextended to the
distal radius);
- diagnosis is made by demonstrating instability in at least two planes;
- sulcus sign is often seen in pts with multidirectional instability;
- look for prominent depression below acromion when inferior traction
is applied to wrist;
- is an indication of deficient
rotator interval capsule:
- Treatment:
- multidirectional instability is not well suited to operative treatment;
- initial treatment should consist of intensive rehabilitation with rotator
cuff strengthening (
dynamic
stabilizers) for
at least one year;
-
surgical treatment options:
-
arthroscopic reconstruction:
- involves posterior & anterior plication of inferior capsule,
followed by possible
rotator interval plication;
- with intact labram (anterior / posterior), the suture
passer/shuttle device can be passed
underneath the labrum, allowing the imbricated capsule to be anchored against
the labrum;
-
anterior shoulder reconstruction:
- mutlidirectional instability can be successfullly managed w/
an anterior shoulder reconstruction
combined with a verticle (upward) shift of the inferior capsule;
- theoretically over-tightening of the anterior capsule might
result in posterior subluxation of the
humeral head;
-
combined anterior and posterior approach:
-
K
Hamada et al (JBJS 1999), 64% of shoulders w/ combined procedure developed a
posterolateral humeral head defect at one year postop, despite absence of
subluxation;
- the authors concluded that over tightening of the
anterior capsule resulted in subclinical
anterior subluxation;
-
inferior capsular shift using either an
anterior vs
posterior approaches:
in the report by
RG Pollock MD et al 2000, the authors treated 52 shoulders w/
multidirectional
instability
w/ an inferior capsular shift using either an ant / posterior - depending on
direction major
instability
(determined from intra-op exam);
- essential feature of this procedure is adequate separation
of the muscle from the capsule
inferiorly to prevent tethering and to allow effective shifting of the capsule
and reduction of
joint volume;
- careful separation of the capsule from the overlying
musculotendinous layer
(the subscapularis anteriorly or the infraspinatus and teres minor posteriorly)
in order to allow
effective shifting of the ligaments to reduce capsular redundancy;
- in this manner, the region of maximum capsular redundancy is
most directly approached
anteroinferiorly with the anterior approach and posteroinferiorly with the
posterior approach;
- 30 (61 %) had an excellent overall result, 16 (33 %) had a
good result, one (2 percent) had a fair
result, and two (4 percent);
- 47 (96 %) of the 49 shoulders remained stable at the time of
follow-up;
- 2 of the 34 shoulders that had been repaired through an
anterior approach began to
subluxate anteroinferiorly again;
- references:
- The inferior capsular-shift procedure for
multidirectional instability of the shoulder.
- Inferior capsular shift for involuntary inferior and
multidirectional instability of the shoulder.
A preliminary report.
- The inferior capsular shift for instability of
shoulder. Long term results in 34 shoulders.
JBJS. 81-B. No 2. Mar 1999. p 218.
-
Operative results of the inferior capsular shift procedure for multidirectional
instability of
the shoulder.
- posterior capsular imbrication:
-
Arthroscopic
posteroinferior capsular plication & RI closure after Bankart repair in ps
w/ traumatic anterior GH-A
minimum f/u of 5 years.
-
closure of rotator interval (see
rotator interval capsule)
- may be determined during intraop exam, w/ excessive inferior
translation (sulcus sign) w/ arm
positioned in adduction and external rotation;
- the decision to perform a rotator interval closure should be
performed only after the inferior
capsular reconstruction (since theoretically the sulcus sign may be eliminated
with the inferior shift);
- references:
-
Effects of Capsular Plication and Rotator Interval Closure in Simulated
Multidirectional
Shoulder Instability
-
Arthroscopic posteroinferior capsular plication & RI closure after Bankart
repair in ps w/
traumatic anterior
GH-A minimum f/u of 5 years.