A review of the mechanisms behind shoulder dislocations in skiing, why it's so common for skiers to suffer the same injury, and exercises to rehab the shoulder and lower the risk of another episode.
The highlights:
*The shoulder joint is inherently unstable and is vulnerable to dislocations because of its anatomy: picture a golf ball sitting on a tee
*Shoulder dislocations happen to skiers these three common ways 1) bracing yourself with an extended arm as you fall, 2) direct trauma to the shoulder, and 3) an eccentric load as you resist forced abduction
*Two types of shoulder dislocation: anterior (i.e pops out the front) and posterior (pops out the back) with anterior dislocations significantly being the most common
*More than 50% of athletes will experience another episode within 13 months after the initial injury with male athletes under the age of 20 participating in contact or overhead sports to have the highest risk of recurrence at 72-86%
*Research shows little evidence to make strong recommendations for length and position of immobilization: no difference in outcomes when immobilized for 1-6 weeks with the arm placed in external or internal rotation.
*Scroll to the bottom of the article with recommendations on rehabbing from shoulder dislocations
The shoulder joint is famous for being inherently unstable. I want you to think of this joint like a golf ball on a tee. The head of the humerus being the golf ball and the shoulder socket (i.e. glenoid fossa) being the tee. It’s easy for a golf ball to fall off a tee because the surface area of the tee is much smaller than the surface area of the golf ball. Just like it can be easy for the head of the humerus to dislocate or sublux (e.g. partial dislocation or malalignment) from the socket of the shoulder. The socket is much smaller than the contact area of the head of the humerus. There are two main types of shoulder dislocations: anterior and posterior.
Anterior shoulder dislocations refer to the shoulder popping out the front. The opposite is a posterior shoulder dislocation where the shoulder pops out the back. The three most common mechanisms of injury for skiers is 1) bracing yourself with an extended arm as you fall, 2) direct trauma to the shoulder, and 3) an eccentric load as you resist forced abduction (1). The first mechanism produces an anterior dislocation when falling backwards, and a posterior dislocation when falling forwards. The second mechanism can be the result of colliding with another skier or fixed objects such as trees, rocks, gates, or ropes. And the third mechanism occurs when a ski pole gets stuck behind the skier with the strap still over the wrist to produce a strong external rotation and abduction force on the shoulder to cause a dislocation. While both types share a common outcome-dislocation-the clinical picture between the two look very different.
Anterior shoulder dislocations are much more frequent than posterior shoulder dislocations. In a study examining 393 shoulder injuries sustained during skiing, anterior shoulder dislocations were the second most frequent at 22% and posterior shoulder dislocations rounding out the bottom of the list at 1% (2). The rate of recurrent episodes or instability following first time anterior shoulder dislocations are scary. On average, more than 50% of athletes will experience another episode within 13 months after the initial injury with male athletes under the age of 20 participating in contact or overhead sports to have the highest risk of recurrence at 72-86% (3).
This has sparked the debate of whether or not young athletes should undergo stabilization surgery after first time dislocation to reduce the risk of recurrent instability in the shoulder. That is a whole another discussion that deserves its own article. If you would like to learn more about that hot topic then please let me know in the comments section. Let’s not forget about skiers over the age of 20. While the risk of first time and re-injury goes down with age, possibly explained by less overall risk consumed, people over 40 years of age also experience injuries to other structures following shoulder dislocation including the rotator cuff, nerves, and bony damage (4). How do you manage these injuries when they occur?
There is nonoperative and surgical management of anterior and posterior shoulder dislocations. The focus will be on the former and the latter can be discussed in greater length at another time. In the acute stage of the injury a shoulder dislocation needs to be reduced (i.e. put back into its anatomical alignment). This can be performed with premedication by injecting lidocaine into the joint or intravenous sedation before a traction-counter traction technique is performed. Following a reduction the arm is immobilized for pain relief and patient satisfaction.
It is important to consider the length and position of immobilization after reduction. Currently there are no high level studies that show different periods of immobilization, ranging from 1-6 weeks, lower the risk of recurrent instability episodes (5,6). One finding worth noting is that longer immobilization, greater than 1 week may improve pain and patient satisfaction in the acute stage of the injury. With respect to positioning, there is no strong evidence to support positioning the arm into more external or internal rotation to reduce the risk of recurrent instability with most physicians opting to position into internal rotation for ease and patient satisfaction (4).
During this period of immobilization, typically 1-6 weeks, passive and active assisted range of motion exercises can be performed safely without re-injuring the shoulder. Examples include:
3. wall slides
After 3-6 weeks shoulder strengthening can begin with a focus on open and closed chained exercises. Open chain exercises can include:
1. shoulder flexion with resisted abduction
2. rotational reactive isometrics
I think arguably the most important field of strengthening to reduce the risk of re-injury involves closed chain exercises and can be divided into beginner, intermediate, and advanced strengthening exercises.
Beginner (holding all positions for 30-60 seconds with equal distribution of weight and no discomfort before progressing to the next phase)
1. prone planks
2. side planks
3. tall planks
Intermediate (Performing 15-25 repetitions, 2-3 sets each with proper form and no discomfort before progressing to the next phase)
2. prone plank alternating leg lifts
Advanced (Performing 15-25 repetitions, 2-3 sets each with proper form and no discomfort before progressing to the next phase)
1. side plank threading the needle
4. scap pull up
5. single arm scapular push up
Until next time,
Dr. Ben Costa, PT, DPT
Telephysio PT, Owner
References
1. McCall D & Safran MR. Injuries about the shoulder in skiing and snowboarding. Br J Sports Med. 2009; 43:987-992.
2. Kochler MS, Dpre MM, Feagin JA. Shoulder injuries from alpine skiing and snowboarding: aetiology, treatment, and prevention. Sports Med. 1998;25:201-11.
3. Grumt RC, Bach BR, Provencher MT. Arthroscopic stabilization for first time versus recurrent shoulder instability. Arthroscopy: The Journal of Arthroscopic and Related Surgery. 2010;26(2):239-248.
4. Gurney-Dunlop T, Eid AS, Old J, Dubberley J, MacDonald P. First time anterior shoulder dislocation natural history and epidemiology: immobilization versus early surgical repair. Ann Joint. 2017; 71(2):1-7.
5. Simonet WT, Melton LJ, Cofield RH, et al. Incidence of anterior shoulder dislocation in Olmsted County, Minnesota. Clin Orthop Relat Res. 1984;186:186-91.
6. Kuhn JE. Treating the initial anterior shoulder dislocation-an evidence based medicine approach. Sports Med Arthrosc. 2006;14:192-8.
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