Shoulder Instability
Shoulder instability refers to a broad spectrum of disorders of the
shoulder that can include subtle abnormal amounts of motion that can
generate pain, to complete dislocations of the shoulder. The motion
and stability of the shoulder joint is controlled by a number of
factors including the strength and integrity of several muscles around
the shoulder and shoulder blade (scapula), the ball and socket
configuration itself, the cartilage rim around the socket (the labrum)
and the capsule and ligaments surrounding the shoulder joint itself.
Any one of these items can be damaged or function incorrectly and
instability can occur.
Subtle instability patterns typically will present with pain in the
shoulder area that may be confused for shoulder impingement
syndromes or rotator cuff injury. This is a
common mis-diagnosis for younger patients, where the pain complaints
and even some of the physical exam findings may suggest one of these
problems, however the underlying cause is actually instability. More
significant levels of instability may feel as though the shoulder
joint is slipping out of place with certain motions or activities or
even present with complete dislocations. Shoulder instability can be
described as unidirectional (only excessive motion in 1 direction) or
multidirectional instability (too much motion in 2 or more
directions). This is an important distinction to make as they are
commonly treated differently and have a different prognosis.
The diagnosis is made based on a complete history of pain and motion
complaints as well as a very careful physical exam that will be
performed by an orthopaedic surgeon. This is typically accompanied by
a series of X-rays and an MRI. These imaging studies help to determine
if the instability has lead to any changes in the bone structure,
small fractures that may associated with it, and any damage to
ligaments, capsule, labrum, or muscles.
The treatment for instability of the shoulder is typically started
with a focused course of physical therapy to stabilize the muscular
support for the shoulder. If this does not provide enough stability to
perform activities that are required for employment or sporting
activities of interest, then surgery is indicated. This traditionally
had been performed with an "open" surgical approach to the
shoulder. However, currently this is often performed via arthroscopy
which is a minimally invasive surgery and has demonstrated similar
results with less risk involved (see shoulder
arthroscopy). This may include repairs of damaged tissue such as
the labrum and moving areas of tissue to tighten the capsule and
ligament structures to provide the necessary support.