Understanding Shoulder Instability for Athletes
In this comprehensive guide to shoulder instability we will cover common causes, symptoms and treatment options for athletes experiencing shoulder instability.
Shoulder instability is relatively common in athletes, accounting for between 4-8% of all athletic injuries. Unfortunately, shoulder instability is rarely just a one time injury, since once you have dislocated your shoulder initially, you are 87% more likely to have a second shoulder dislocation if you continue in your sports.
What is Shoulder Instability?
The shoulder is a ball and socket joint that requires a high amount of mobility to perform athletic movements like throwing, catching, hitting, and even running. The mobility requirements of the shoulder joint make it relatively unstable, with very little passive support and stability.
While the shoulder is called a “ball and socket” joint, it is really shaped more like a golf ball on a tee. There is a very shallow bony support of the glenoid that is buttressed slightly by a labrum that deepens the socket. There are several ligaments and joint capsules that support the shoulder, but these soft tissue structures are relatively loose to allow full range of motion of the shoulder.
With minimal passive support of the shoulder, it puts extra emphasis on dynamic stability using muscular support. Primarily, the rotator cuff muscles aid in stabilizing the shoulder and keeping the ball centered on the socket.
Essentially, shoulder instability occurs anytime the golf ball falls off the tee. This results in either a shoulder dislocation, where the ball slides off the socket and remains out of place, or with a subluxation, where the ball slides out of the socket but immediately relocates on its own.
Shoulder dislocation and subluxation can occur in several different ways. The most common form of shoulder instability is when the shoulder dislocates anteriorly, or slides out of the front of the joint. However, it can also slide out of the back of the joint resulting in posterior instability.
There is a third type of instability called multi-directional instability. This is much less common overall, and is a result of congenital anomalies. Essentially, the tissues around the shoulder are not strong enough to support the shoulder and the shoulder dislocates frequently in a variety of different directions.
Common Causes of Shoulder Instability in Athletes
Most commonly, shoulder instability results from a traumatic injury, like a fall on an outstretched arm, a tackle or other forms of direct contact. The shoulder is most vulnerable to dislocation in positions away from the body, like reaching overhead or out to the side.
Repetitive overuse in overhead motions like throwing a ball or striking a volleyball can gradually weaken the passive tissues around the shoulder and lead to a higher risk of developing shoulder instability overtime. It is less common to have a single traumatic episode of shoulder instability from non-contact mechanisms.
People suffering from multi-directional instability that have congenital lax tissues can dislocate in many different positions. There may not be a single episode or event that causes the instability, but it can occur from “normal” day to day movements.
Recognizing the Common Symptoms of Shoulder Instability
Symptoms During the Injury
Commonly with an initial dislocation, an athlete will feel a sensation that their shoulder “slipped out.” This will be accompanied with pain, loss of strength and loss of motion. Often they will walk off the field or court with their arm dangling at their side.
Shoulder instability can either occur as a dislocation where the shoulder stays out of the joint until it is manually relocated by a trained medical professional, or it might relocate on its own.
Symptoms After the Injury
After the initial injury, the pain will gradually resolve, but loss of range of motion and weakness will continue. Additionally, it is fairly common to feel a general “looseness” of the shoulder and have a sensation that the shoulder may slip out again with basic movements.
Unfortunately, after an initial dislocation or instability episode, you are much more likely to dislocate again in the future. As many as 87% of athletes between the ages of 15-20 years old experienced recurrent instability episodes, or that their shoulder “slipped out” a second time.
If you experience symptoms of shoulder dislocation and feel your shoulder “slip out”, it is important to follow up with a medical professional. Dislocation can result in injuries to the bone, arteries or nerves of the arm. It is important to have the shoulder checked out and to make sure that it was relocated correctly to ensure the best possible outcomes long term.
Diagnostic Tests for Shoulder Instability
Clinically, the best test for shoulder instability is the apprehension-relocation test. This test puts the shoulder out to the side, in the most vulnerable position for shoulder dislocation. Commonly, the patient will report "apprehension", or a sensation that the shoulder is going to slip out. We then provide a little extra stability by pressing down on the front of the shoulder, which relieves the apprehension that the shoulder might slip out.
Typically, a clinical exam is also followed up with at least an x-ray. The x-ray is important to ensure that the joint is properly relocated (the ball is sitting back in the socket), and it can also show any bony injuries to the joint, like a bony bankart injury or a hill-sachs lesion.
Many athletes will also undergo an MRI that will confirm how much injury occurred to the soft tissue during the dislocation. Most commonly, there will be injuries to the labrum (called a bankart tear), damage to the shoulder capsule, and sometimes rotator cuff damage or cartilage injuries. The MRI will give a full picture to the extent of the injury and allow for a clear plan moving forward.
Preventing Shoulder Instability in Athletes
With a recurrence rate of 87% following an initial shoulder dislocation. One of the best things you can do as an athlete is prevent shoulder instability from occurring in the first place.
The following exercises are proven strategies and exercises that help strengthen the shoulder joint and reduce risk of shoulder instability in athletes.
Shoulder Strengthening Exercises for Athletes
Rotator Cuff
The rotator cuff’s job is to help stabilize the shoulder joint and keep the ball on the socket. It is key for dynamic control and stability of the shoulder.
These two exercises are great ways to work on rotator cuff strength:
Straight Arm Band External Rotation
TRX External Rotation
