Dr. Peter J. Millett is an orthopedic shoulder surgeon who specializes in disorders of the shoulder. He is an expert in shoulder instability, dislocated shoulders and in traumatic injuries that result in these conditions. This article discusses causes and treatments of shoulder instability and in shoulder dislocations.

1. This article was originally posted on http://drmillett.com/ask/ on Thursday, September 15, 2011.
“The Unstable Shoulder: Vail, Colorado Shoulder Surgeon Discusses Common
Causes of Chronic Shoulder Instability, Shoulder Dislocations and Offers
Insight on New Treatments”
Dr. Peter J. Millett (http://drmillett.com), an orthopedic shoulder surgeon and Director of Shoulder
Surgery for the Steadman Clinic in Vail, Colorado was interviewed for this article.
The shoulder is the most mobile joint in the human body. While it offers the largest range of motion of all
joints, it also has extraordinary strength that allows one to position the hand in space so that we can
accomplish great tasks and movements. According to Dr. Peter J. Millett, a top orthopedic shoulder surgeon
in Vail, Colorado, it is this great strength and range of motion, that often leaves the shoulder joint
susceptible to injury.
“Shoulder instability is one of the more common shoulder problems that I see in my patients,” says Dr.
Millett. “It is a condition that occurs when the ligaments, muscles and tendons within the shoulder no longer
work together in a unified fashion to hold the ball into the socket. When this occurs, the ball (humeral head)
literally comes out of the socket (glenoid) and the feeling of shoulder instability is the result.”
Types of Shoulder Instability
When shoulder instability occurs, the bones of the shoulder
move beyond what Mother Nature intended such that the
ball slips or ‘pops’ out of place.”
There are two, sometimes overlapping, degrees of
shoulder instability - one is a shoulder dislocation where
the ball comes completely out of the socket and the
other is a shoulder subluxation, where the ball comes
out partially and then pops back in place.
When the shoulder is locked out with a complete dislocation, the shoulder is usually painful and difficult to
move. When the joint completely slides out of place (dislocation), it may reduce (go back in) spontaneously
or it may require a trip to the local ER so that the joint can be properly put back into place by a medical
professional.
With a shoulder subluxation, there is usually a transient sense that the joint is out or that it has slipped, but
with a subluxation it invariably reduces spontaneously. Most individuals who subluxate their shoulder are
able to move their shoulder joint back into a reduced position and are able to treat the pain with mild pain
relievers.
Patients can have shoulder instability in different directions – anterior (front of the shoulder) is most
common. Posterior (back of the shoulder) and multi-directional shoulder instability are other variants.
C auses o f S ho ulder Instability
Collision sports athletes are at highest risk to suffer shoulder instability. Athletes who engage in contact and
collision sports, such as football, hockey and lacrosse, are at the higher risk for complete shoulder
dislocations, and furthermore they are also at greatest risk for recurrence of the instability once the first
dislocation has occurred.
When an athlete suffers a traumatic blow or hit directly to the shoulder area, damage can occur within the
shoulder joint. If the trauma is severe enough, ligaments and a cartilage known as the labrum may be
disrupted. Without proper treatment, an individual may continue to experience recurrent symptoms of
shoulder instability, pain, and weakness for months or years following the injury. Additional episodes of

2. instability can cause additional damage to the cartilage, ligaments, and bone. Thus, it is important to get this
evaluated and treated early so as not to create additional damage to the shoulder joint. There can be
secondary consequences of the damage such as arthritis if it is not treated properly and the shoulder
continues to come out.
Some people who have shoulder instability, may in fact, never have a complete dislocation but only
recurrent subluxation events. Often these individuals simply have looser ligaments (hyperlaxity). Overuse
and activities that involve repetitive motion can stretch the capsule and ligaments that stabilize the shoulder,
resulting in symptoms of shoulder instability. Athletes who participate in repetitive overhead movements,
such as throwing a baseball, swimming, or serving a tennis ball are at particular risk for developing this type
of shoulder instability pattern.
Finally, some patients are simply more genetically inclined to develop shoulder instability and shoulder
dislocations because they are born with loose ligaments, colloquially known as double-jointed, due to
stretchy collagen or other types of connective tissue disorders.
Treatm ent fo r S ho ulder Instability, S houlder D islocations
Dr. Millett explains that some individuals can sustain an injury and live with the instability, while others may
need surgery after only a single dislocation. It depends on the age of the patient, the sports in which they
participate, and the pattern of injury “It is common for some patients to suffer a traumatic injury that causes
recurrent shoulder subluxations, and yet they live with the annoying symptoms for years, because it is either
not that severe or the diagnosis is not made. These individuals often rely on over the counter pain
medication to relieve the soreness in their shoulder. In some instances, a secondary injury can lead to a
shoulder that is highly unstable and needs surgery to stabilize it.”
Ty Lenard, a patient of Dr. Millett’s, knows this story too well. A basketball player for years, he injured his
shoulder during the 8th grade while playing in a basketball tournament. The injury left his shoulder weak
and vulnerable for months. By high school, he was playing football for his high school team and began to
experience dislocations on a regular basis. One final, hard hit, sent him straight to the ER and eventually
into the hands of Dr. Millett.
“Ty had some serious damage to his right shoulder from years of traumatic injuries and subsequent
dislocations. His CT scan showed an anteroinferior glenoid fracture, which essentially is a bone defect in
the socket that made the shoulder highly unstable. The fracture made the ball unable to stay in the socket,
similar to a golf ball sitting on a broken tee. The only way he would be able to resume playing football, was
with surgery to rebuild the deficient socket.”
There are new surgical options available
today for patients with mild and/or severe
shoulder instability. Arthroscopic surgery is
one of the most current and effective
treatment options. Small holes are made
through the skin and tiny instruments are
used to repair the shoulder joint. The most
common procedure is called an arthroscopic
Bankart repair, where the torn labrum is
repaired and the ligaments are re-tensioned.
Sometimes there is more damage and an
arthroscopic capsular shift is performed.
This is used for injuries exhibiting a more intricate and complicated instability. It is also performed
arthroscopically and involves a reattachment of loose or torn ligaments to the joint with the use of special
implants called suture anchors. These anchors are used to relocate, hold in place and tighten injured joints.
In some cases this is done posteriorly (in the back); this is called a posterior capsular shift. In other cases

3. where the shoulder dislocates in multiple directions (multi-directional instability) the capsule is tightened in
the front, back, and bottom, a procedure sometimes known as a pancapsular shift.
For some cases, like Ty’s where there is bone loss on the glenoid, the socket will need to be rebuilt. A
technique that has been used in France for years, known as the Latarjet procedure, can be used in cases
such as this. Dr. Millett has used this technique for many years now and performed a Latarjet procedure on
Ty to rebuild the bone that had been damaged from years of instability. At the same time he also performed
an arthroscopic procedure to remove some loose debris from the shoulder joint and to smooth out his Hill-
Sachs defect (a common injury to upper end of the humerus). After a strict rehab protocol, Ty has gotten
back on the football field and is playing in college on a scholarship with 100% return of normal function of
his arm and shoulder.
There are a number of different types of shoulder instability and procedures to treat them. Dr. Millett has
ongoing laboratory and clinical research projects on these surgical techniques for shoulder instability to
allow for faster and better recoveries.
Shoulder instability is a very common condition that can be treated reliably with predictably in the vast
majority of patients and athletes. Proper diagnosis and appropriate surgery are however essential for an
optimal result. Once surgery has been performed and the shoulder rehabilitated, most individuals can
return to their normal activities without the fear or anxiety of instability or a dislocation. Recovery typically
takes between 4 and 6 months.
Talk to your orthopedic doctor if you are experiencing shoulder instability so that a proper course of
treatment can be prescribed and you can resume a normal, active lifestyle.