Have you ever had an injury where the shoulder has ‘popped out’? Or do you feel like your shoulders are loose? Or are there certain positions like up above head where you feel unstable? These questions are just some examples that your clinician will ask to determine if you have something that is commonly referred to as shoulder instability. The shoulder joint being the most mobile joint in the human body is prone to dislocations (where the humerus pops out and stays out) and subluxations (where the humerus moves out then straight back in). These types of injuries are very common, but how do we rehab an injury like this and what are the best strengthening exercises? Firstly let’s delve a bit deeper into why this condition occurs and who is more at risk.
What is Anterior Shoulder Instability?
Shoulder instability or a shoulder dislocation as it is commonly known is classified into two groups traumatic and atraumatic. An anterior traumatic shoulder dislocation occurs when there is excessive translation of the humeral head within the glenoid fossa most commonly due to a traumatic event such as a sporting injury that moves the shoulder joint into a position of abduction, external rotation and extension. An anterior atraumatic shoulder is classified as an abnormal position that the shoulder joint is moved into that leads to pain, subluxations, functional impairments and dislocations which occur without any trauma to the shoulder joint itself.
Some of the signs and symptoms of an anterior traumatic shoulder dislocation include:
- Intense pain within the shoulder region
- Feelings of instability
- Humeral head may be visibly ‘out of place’ of the glenoid cavity and sometimes will have a squared off look to the shoulder compared to the unaffected side
- Swelling due to the acute inflammatory phase occurring
- Arm positioned into internal rotation and adduction due to being apprehensive in positions of external rotation and abduction
Some of the signs and symptoms of an anterior atraumatic shoulder dislocation include:
- Excessive amounts of range through the shoulder joint
- Several occasions of shoulder instability
- Apprehension in positions of external rotation and abduction
- May have pain within the shoulder joint
- Weakness of rotator cuff muscles and deltoids
Within the current literature there are some well-established acronyms to differentiate between traumatic and atraumatic as well as some suggested treatment options:
- T- Traumatic
- U- Unilateral
- B- Bankart Lesion
- S- Surgical Intervention Recommended
- A- Atraumatic
- M- Multidirectional
- B- Bilateral
- R- Rehabilitation Intervention Recommended
- I- Inferior Capsular Shift
The key differences with these acronyms is the treatment paths. As stated above traumatic shoulder dislocations will sometimes require surgical intervention due to damage to either bone, joint or muscular structures. However, atraumatic shoulder dislocations will rarely need surgical intervention if a structured rehabilitation program is followed with factors including dynamic stabilisation, strength, neuromuscular exercises as well as adequate education for the individual throughout the process.
A shoulder dislocation can be unidirectional including anterior, posterior and inferior dislocations. It is commonly seen that 96% of shoulder dislocations are caused from a traumatic event with anterior dislocations making up 97% of these shoulder dislocations (https://journals.sagepub.com/doi/10.1177/1758573215585656). The incidence of shoulder dislocation will rise significantly in a sporting or active population. Shoulder dislocations are the most commonly dislocated joint in human beings. As a result of this an anterior shoulder dislocation can significantly impact an individuals quality of life for many years even after the event has passed. This can lead to recurrent instability which can result in a barrier for individuals to return to activities and thus, lead to a fear of movement. Ultimately, impacting an individual’s physical and mental health especially if the recurrent instability is frequent.
What is the prevalence of shoulder dislocations?
- Shoulder dislocations are 2.5 times more likely to occur in men compared to females
- 72% of all shoulder dislocations occur in young males
- 50% of dislocations occur in those aged between 15-29 years of age
- The peak age group where dislocations are most likely to occur is 17-22 for males and 61-70 for females
Who is more at risk?
- Males in particular young males. Men are x3 more likely to suffer recurrent dislocations compared to women (https://pubmed.ncbi.nlm.nih.gov/25900943/#:~:text=Conclusions%3A%20Sex%2C%20age%20at%20initial,concluded%20in%20the%20GRADE%20criteria.)
- Age 40 or below are 13x more likely to sustain recurrent shoulder dislocations compared to those 41 and above (https://pubmed.ncbi.nlm.nih.gov/25900943/#:~:text=Conclusions%3A%20Sex%2C%20age%20at%20initial,concluded%20in%20the%20GRADE%20criteria.)
- Individuals who are involved in physically active sports
- A history of a shoulder dislocation on the contralateral side is associated with a future dislocation and may indicate potential intrinsic risk factors involved
- An anteverted glenoid may be an increased risk of shoulder dislocations especially anterior instability, an anteverted glenoid is one which faces anteriorly versus posteriorly
- Shoulder instability may be increased in those with joint hypermobility, this is then associated with being vulnerable to upper limb pain. Furthermore, it may reduce quality of life due to motor and muscular systems working overtime to stabilise the shoulder joint thus, impacting the sensitivity of the muscles around the shoulder joint
- Ehlers Danlos syndrome is a group of disorders which affect the connective tissues supporting the joints, skin, blood vessels and many other organs and tissues. This condition can also have a significant impact on an individual’s quality of life. This condition should be screened for especially in young females less than 14 years of age presenting with primary shoulder dislocations and generalised hypermobility
- Baseball throwers, gymnasts, swimmers generally will have an increase in the extensibility of the capsuloligamentous restraints of the shoulders which may lead to a higher risk of shoulder dislocation with these sports without trauma involved
- Strength is not a risk factor for developing shoulder dislocations however it can be a contributing factor for recurrent anterior shoulder dislocations due to people with anterior shoulder dislocations generally having deficits in their rotator cuff muscle strength (https://pubmed.ncbi.nlm.nih.gov/21508283/)
Should you use a sling after an anterior shoulder dislocation?
It has been shown that immobilisation in a sling for >1 week will not confer any additional reduction in recurrence of dislocation (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4935160/)
It has been further researched that not being immobilised with a sling may be a risk factor for anterior shoulder instability. So from both of these recommendations the sweet spot for shoulder dislocation sling immobilisation should be approximately 1 week. However, this should be individualised to the client as we may want to immobilise the shoulder for other reasons than to just reduce the recurrence of dislocations. Sling use is just one part of the shoulder instability treatment process.
What are the best rehabilitation exercises for shoulder instability?
Closed Kinetic Chain exercises (CKC) For Shoulder Dislocations:
CKC exercises within the upper limb can help to facilitate co-contraction of the rotator cuff muscles and deltoid muscles thus enhancing joint stability, controlling potential fear of movement, loading scapulothoracic muscles and enhancing proprioception. These type of exercises are crucial within the first stages of the shoulder instability rehabilitation program due to there being a fixed base of support to complete the exercise. With these exercises they will generally begin within gravity eliminated positions and slowly progressing to more physically and mentally demanding positions.
- 4 point kneel variations
4 point kneeling exercises are a great exercise for shoulder stability as well as trunk stability. This exercise can be progressed or regressed very easily which makes it perfect for the first stage of the rehabilitation process. To perform this movement you maintain equal weight bearing through knees and hands, pulling abdominals in slightly whilst maintaining a natural curve in your lower back. Adding in hand touches to increase the difficulty!
- Wall push up with shoulder taps
This is the regressed version of a push up from the floor and is the perfect start to allow some load to be placed through the shoulder and allow the individual to understand that movement through the shoulder is safe. Many individuals with anterior shoulder instability have overactive upper traps compared to the serratus anterior. This strengthening exercise is great to actively recruit the serratus anterior.
- Plank circles with Bosu ball
This strengthening exercise is a slightly later stage CKC exercise as it is on an uneven surface to focus more on the proprioception of the shoulder joint. Adding in a push up can make this exercise more difficult.
Open Kinetic Chain (OKC) Exercises For Shoulder Dislocations:
OKC exercises are an exercise where the feet or hands are not fixed to an object, one of the biggest benefits of OKC exercises compared to CKC exercises are that they can isolate a muscle more efficiently. With shoulder OKC exercises the load is increased and the effect of gravity becomes more evident. These strengthening exercises are crucial within the rehabilitation program to strengthen the shoulder girdle in a wide range of ways.
1. Static external rotation and internal rotations isometrics
Isometrics are such a perfect way to start OKC exercise. External rotation and internal rotation isometrics are great to allow the rotator cuff muscles to begin to fire. This type of exercise should be pain free with submaximal efforts. Due to the subscapularis having a role in glenohumeral stability the internal rotation strengthening exercise is crucial.
2. Scaptions or ‘Y’s
This exercise is a great exercise to work on the rotator cuff muscles as well as the scapular stabilisers. This exercise can be done in lying on the ground or a bench. To complete start by slowly raising hands up in the shape of a ‘Y’ making sure to keep thumbs up to bias the lower and middle trapezius muscles. A tip here is to not engage your upper trapezius so not shrugging to lift your shoulders up.
3. Bottoms up kettle bell variations
Kettlebells are a great tool to build dynamic shoulder instability as there is so many progressions that can be implemented into the rehabilitation program. By placing the kettlebell upside down it becomes very difficult to stabilise. This strengthening exercise is great for the core stabilisers, scapular depressors and retractors.
Plyometric Exercises For Shoulder Dislocations:
These exercises focus on the stretch-shortening cycles of eccentric followed by concentric contractions. It has three phases the eccentric where the musculotendinous unit deforms under load created by a rapid stretch. Then the amortization stage which is the transition between eccentric and concentric where kinetic energy is transferred and stored as potential energy. Finally the concentric stage which is the end result of explosively propelling the systems centre of mass in the applied direction. (https://www.physio-network.com/blog/physio-guide-to-plyometrics/). Plyometric are one of the last phases of the rehabilitation program. There are four phases of the plyometric prescription:
Absorption phase in this phase we want approximately 75% strength of the affected side. This can be replicated as altitude landing from weight plates. Begin by placing your hands on weight plates just wider then shoulder width apart then coming down onto the floor and absorbing the force.
Force creation, with these type of exercises we do not want to do high reps as this places a lot of load through the shoulder. One great exercise in this stage of plyometric prescription is an incline explosive push up where you begin on the bench pushing yourself up explosively then coming back down absorbing the force.
Stretch shortening cycle in this phase we want to ensure that the individual has at least 90% limb symmetry. A fantastic exercise for this phase is a push press where you are transferring your force from lower body into a shoulder press.
Maximal demands where we want the individual to have minimum 95% limb symmetry and this phase is the final phase to return to sport exercises. As it’s the final phase we want to be individual specific. A great exercise is drop catches with weight where you are dropping and then catching a weight in a long lever position this is a very difficult exercise but crucial to build the final bit of confidence for a player to return to sport.
Complications with traumatic anterior shoulder instability:
- Bony Bankart lesions which are a fracture on the inferior glenoid cavity can be present in 21% of people with anterior shoulder instability (https://pubmed.ncbi.nlm.nih.gov/18430839/)
- Hills Sach lesions which is a compression fracture of the humeral head and occurs on the humeral head as it is softer compared to the glenoid cavity. These are present in up to 83% of shoulder dislocations the larger the lesion is associated with recurrent dislocations (https://link.springer.com/article/10.1007/s00167-021-06847-7).
- Approximately 33% of shoulder dislocations showed a rotator cuff muscle tear or a greater tuberosity fracture (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6132400/). Furthermore, 40% of individuals over the age of 40 suffering an anterior shoulder dislocation will have a rotator cuff muscle tear. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4935160/)
- 13.5% of people with a traumatic dislocation will have a neurological deficit which commonly affects the axillary nerve (https://pubmed.ncbi.nlm.nih.gov/18381306/)
Ultimately, the aim of the rehabilitation program for anterior shoulder dislocations is to build absolute stability and confidence through the shoulder to allow the individual to return to their valued activities. These exercises are just examples and the activity that the individual wants to return to will ultimately determine the exercise prescription. If you or someone you know is looking for further advice in shoulder instability get into contact with Physio Fit to book an appointment!