Condition
Shoulder instability
Shoulder instability is the term used when the ball of the shoulder slips out of the socket, either fully (a dislocation) or partially (a subluxation). It is one of the most common sports injuries of the shoulder, particularly in contact sports.
Anatomy
How the shoulder is built to stay in joint
The shoulder is a ball-and-socket joint, but the socket is very shallow, which gives the shoulder a large range of motion. The trade-off is that the shoulder relies more on soft tissue for stability than other ball-and-socket joints.
The ball is called the humeral head, and the socket is called the glenoid. Surrounding the glenoid is a tough ring of fibrous tissue called the labrum. The labrum deepens the socket, helps stabilise the joint, and serves as the attachment point for the ligaments that hold the shoulder in place.
Pathology
What goes wrong in instability
Instability can be anterior, where the humeral head slips out the front of the socket (the most common pattern), posterior, where it slips out the back, or multidirectional.
When instability occurs, the labrum is often torn from its attachment to the glenoid. A tear at the front of the labrum is called a Bankart lesion and is the most common finding after an anterior dislocation.
Other structures that can be damaged include:
- The joint cartilage of the humeral head and glenoid.
- The humeral head bone. A Hill-Sachs lesion is an indentation in the back of the humeral head caused by the head impacting on the front rim of the socket during dislocation.
- The glenoid bone. Bone loss from the front rim of the socket is common in recurrent dislocations and is one of the main reasons a labral repair alone may not be enough.
- The ligaments and capsule surrounding the joint.
- The rotator cuff tendons, particularly in older patients.
- Nerves supplying the arm, in particular the axillary nerve, which can be stretched during dislocation.
Causes
What causes shoulder instability
Shoulder instability is usually associated with an injury to the shoulder, although some people who are ligamentously lax (extremely flexible, sometimes described as “double-jointed”) may have problems with instability without any history of injury.
Shoulder instability is a common sports injury, especially in contact sports such as rugby and football, and in skiing and surfing where falls onto the shoulder are common. It also occurs outside sport, particularly with high-energy mechanisms like a fall from height or a motor vehicle accident.
Recurrence
Can shoulder instability recur
Recurrent shoulder instability is very common after a first dislocation. The risk of recurrence is affected by several factors, including age, sex, functional demand (sports), the number of previous dislocations, and the previous treatment received. The greater the damage to the shoulder during the first dislocation, the higher the risk of recurrence.
Despite advances in physiotherapy and shoulder rehabilitation, recurrence rates in active young males can exceed 70 to 80 percent. Even in patients with lower functional demand, recurrence rates may be as high as 40 percent.
These numbers are why surgical stabilisation is often discussed early in young, active patients, particularly after the second dislocation, and why bone-loss assessment matters when planning the right operation.
Diagnosis
How shoulder instability is assessed
All cases of shoulder instability should be medically assessed to quantify the extent of the damage to the shoulder joint and surrounding structures. Assessment includes:
- Clinical examination. Specific tests for instability and apprehension, plus a check of rotator cuff strength and nerve function.
- X-rays. Standard views to confirm the head is back in place and look for obvious fractures.
- MRI scan. Almost always required to assess the labrum, ligaments, cartilage, and rotator cuff.
- CT scan. Required when there is suspected significant bone loss, either from the glenoid or the humeral head. Bone loss assessment is important for planning the right stabilisation procedure.
An ultrasound scan is not usually helpful in assessing the shoulder after a dislocation.
Treatment
Treatment options for shoulder instability
There are several treatment options available for shoulder instability. The right choice depends on the extent of the damage to the joint (particularly any bone abnormalities), other associated injuries, the patient's functional and sporting demand, and age. A thorough pre-operative assessment is critical.
- Non-operative treatment. A period of rest in a sling, anti-inflammatories, and physiotherapy focused on rotator-cuff and scapular control. Effective in some first-time dislocators with low functional demand.
- Arthroscopic labral repair (Bankart repair / shoulder reconstruction). Re-attachment of the torn labrum to the rim of the glenoid with suture anchors. Used when there is no significant bone loss and the soft tissue alone can hold the shoulder in.
- Latarjet procedure. A bone-block stabilisation that transfers the coracoid process to the front of the glenoid. Used for complex instability, significant bone loss, or recurrence after a previous repair.
- Combined approach. Some complex injuries require both arthroscopic and open techniques in the same operation.
The decision about which operation is right is made after a full assessment. Dr Piper will explain why one operation is being recommended over another, and what the realistic recurrence risk is after each.
Recovery
Recovery from shoulder stabilisation surgery
Recovery time depends on the type of instability, the extent of the damage, and the procedure performed. Most stabilisation surgeries require around four weeks in a sling, allowing time for the labrum or bone block to heal.
During the sling period, passive exercises (movement of the shoulder without using the shoulder muscles) are performed under physiotherapy guidance to prevent excessive stiffness. Once the tissue or bone has healed, the sling is removed and active exercises commence. Strengthening is introduced over the following weeks. Exercises should never cause excessive pain.
Return to sport typically takes around four and a half months for a Latarjet procedure and six months for a labral repair.
Complications and risks
Risks of stabilisation surgery
As with any surgery, there are risks. The specific risks depend on the procedure performed and the extent of the original damage. The general risks include (but are not limited to):
- Post-operative shoulder pain and swelling. Bruising can extend down the arm. Usually settles in the first few weeks.
- Shoulder stiffness. A period of stiffness after surgery is normal and improves with physiotherapy. Some patients notice a small loss of external rotation after a Latarjet procedure, but it does not usually cause functional limitation. With any shoulder surgery, there is a risk of frozen shoulder, which may prolong recovery.
- Recurrence of dislocation. Stabilisation reduces the risk of recurrent dislocation but does not eliminate it. Recurrence after Bankart repair may be as high as 15 percent in young active males. Recurrence after a Latarjet is significantly lower.
- Shoulder arthritis. Damage to the joint cartilage at the time of dislocation can lead to arthritis later. Surgery cannot reverse cartilage damage, but stabilising the shoulder may prevent further damage during recurrent dislocations.
- Nerve injuries. Stretching of nerves during the original dislocation (most common) or during surgery may cause numbness or muscle weakness. Most nerve palsies are temporary.
- Complex regional pain syndrome (CRPS). A rare condition that causes pain and stiffness in the hand.
- Loss of throwing strength or delayed return to sport. Six months is the typical timeline; full sport-specific strength takes longer.
- General surgical risks. Infection (very rare with arthroscopic surgery, slightly higher with open Latarjet), DVT (very rare with upper-limb surgery), allergic reactions to medication, and anaesthetic complications.
FAQ
Frequently asked questions
- What is the difference between a dislocation and a subluxation?
- A dislocation is when the ball of the shoulder fully comes out of the socket. A subluxation is a partial dislocation, where the ball slips out of the socket but spontaneously goes back in. Both are forms of shoulder instability and can be caused by the same underlying tissue damage; the difference is how far the head moves before reducing.
- Should I have surgery after my first shoulder dislocation?
- It depends. Recurrence rates after a first dislocation in young, active males can exceed 70 to 80 percent, so surgery is often discussed early in this group. In older patients, lower-demand patients, or patients with no significant labral or bone-loss damage, non-operative treatment with physiotherapy may be reasonable. The decision is based on age, activity profile, and the imaging findings.
- How is the choice between labral repair and Latarjet made?
- The decision depends on bone loss, the number of previous dislocations, and the activity profile. Arthroscopic labral repair works well when the bony socket is intact and the soft tissue is the main problem. The open Latarjet is used when there is significant glenoid bone loss, an engaging Hill-Sachs lesion, or a previous labral repair has failed. CT imaging for bone-loss assessment guides the choice. Patients will also often choose a Latarjet procedure for the lower risk of recurrent dislocation, particularly if they are planning on continuing to play contact sports. Dr Piper will discuss surgical options with you during your consultation.
- How long is recovery from shoulder stabilisation surgery?
- A sling is worn for around four weeks. Passive exercises start in the sling period under physiotherapy guidance, then active and strengthening exercises commence after the sling is removed. Return to sport typically takes around four and a half months for a Latarjet procedure and six months for a labral repair.
- Can shoulder instability lead to arthritis?
- Yes. Damage to the joint cartilage at the time of dislocation can lead to arthritis later in life. Recurrent dislocations cause repeated cartilage injury. Surgery to stabilise the shoulder cannot reverse cartilage damage but may prevent further injury during recurrent dislocations.
References
- Olds M, et al. Risk factors which predispose first-time traumatic anterior shoulder dislocations to recurrent instability in adults: a systematic review and meta-analysis. Br J Sports Med. 2015;49(14):913-922.
- Robinson CM, et al. Functional outcome and risk of recurrent instability after primary traumatic anterior shoulder dislocation in young patients. J Bone Joint Surg Am. 2006;88(11):2326-2336.
- Hurley ET, et al. Risk factors for recurrence after Bankart repair: a systematic review and meta-analysis. JSES Int. 2022;6(3):420-426.
- Hurley ET, et al. Long-term outcomes of the Latarjet procedure for anterior shoulder instability: a systematic review of studies at 10-year follow-up. J Shoulder Elbow Surg. 2019;28(2):e33-e39.
Concerned about a recurring dislocation?
Book an appointment with Dr Piper
Consultations at Lakeview Private Hospital, Norwest. Bring a referral and any imaging you have.