Shoulder instability
Shoulder dislocation and instability after a motor accident
A dislocation may leave restricted motion, recurrent instability, labral damage, fracture or nerve injury. WPI is not set by the fact that a reduction or stabilisation operation occurred; the assessor must identify the permanent residual impairment and use a permitted method.
Motor accident injury
How can this injury happen?
Car or passenger collision
A side collision can drive the arm into abduction and rotation or force the shoulder against the door.
Motorcycle accident
A rider landing with an outstretched arm may sustain anterior or posterior dislocation, fracture or brachial plexus traction.
Pedestrian or cyclist impact
Direct impact or a fall can dislocate the joint and cause labral, bony or nerve injury.
Injuries that can occur
- anterior or posterior glenohumeral dislocation
- labral tear and recurrent instability
- Hill-Sachs or bony Bankart lesion
- greater tuberosity fracture or cuff injury
- axillary nerve or brachial plexus injury
Symptoms and functional problems
- apprehension in overhead or externally rotated positions
- recurrent slipping or subluxation
- restricted elevation and rotation
- numbness over the shoulder or weakness after dislocation
Seek urgent medical assessment
An unreduced deformity, absent pulse or new neurological deficit requires emergency assessment.
Clinical evidence
What findings matter?
Reduction records, post-reduction imaging, stability examination and neurological findings are central. Recurrent symptoms should be distinguished from general pain and fear of movement.
| Record or examination | What it may establish | What it cannot prove alone |
|---|---|---|
| Emergency and reduction record | Confirms direction, neurovascular status, reduction and associated fracture. | The acute event does not set permanent WPI. |
| X-ray, CT or MRI | Defines bony defects, labral pathology, fracture and cuff injury. | Imaging alone does not quantify instability or movement loss. |
| Stability, ROM and nerve examination | Records apprehension, recurrent instability, active movement and axillary or plexus deficit. | Subjective giving way without reproducible findings is insufficient. |
Movement in daily life
How movement affects real activities
External rotation and abduction often provoke apprehension, while flexion and internal rotation affect overhead reach, grooming and dressing.
Flexion
Lifting the arm forward and overhead, including reaching a shelf or putting on a shirt.
Active flexion and extension are rated through AMA4 shoulder Figures 36 to 38 when reliable.
Abduction
Lifting the arm sideways, including reaching away from the body or fastening a seat belt.
Active abduction and adduction are addressed by Figures 39 to 41.
External rotation
Washing hair, reaching behind the head and positioning the arm to put on a jacket.
Active external rotation is read with the shoulder rotation figures, not estimated from pain severity.
Internal rotation
Reaching behind the back for dressing, hygiene or fastening clothing.
Active internal rotation is addressed with Figures 42 to 44 and must be measured consistently.
Threshold injury is a separate question: a verified dislocation with structural or nerve injury may be outside a simple soft tissue classification. Apprehension or sprain without an excluded injury may still be threshold.
Part 6 permanent impairment
How is CTP WPI assessed?
Reliable active ROM is directly verifiable. AMA4 Table 23 is identified as the persistent joint subluxation/dislocation table, but no row value is published here because the supplied Chapter 3 source is unreadable; any use must be verified against the licensed table.
Measurement rules that apply
- Clause 6.50 requires active, not passive, range of motion for the impairment calculation. A goniometer should be used where clinically indicated, and unreliable movement should be repeated consistently before it is accepted.
- Clauses 6.51 and 6.52 permit a contralateral baseline only where the uninjured joint is a fair estimate of pre-accident mobility. The total upper-extremity impairment for each comparable joint is subtracted before conversion to WPI.
- Clause 6.67 prohibits upper-limb strength evaluation and AMA4 Table 34. A genuine peripheral nerve or muscle-bulk injury must use another permitted method without double counting.
| Method | CTP source | When it is relevant | Important limit |
|---|---|---|---|
| Active shoulder ROM | Clause 6.50; Figures 36-44 | Permanent loss after reduction, rehabilitation or stabilisation. | Do not infer angles from apprehension alone. |
| Persistent subluxation/dislocation | AMA4 Table 23, subject to clauses 6.24 and 6.65 | Potentially relevant to objectively persistent instability. | Exact row criteria and value require the readable AMA4 source before use. |
| Peripheral nerve method | Clauses 6.53 and 6.58-6.60 | A separate verified axillary or brachial plexus injury. | Cannot be combined unless it is a separate injury. |
- Check for a separate fracture, cuff or nerve injury.
- Rate the current permanent result after treatment.
- Do not treat stabilisation surgery as a fixed percentage.
What cannot be combined?
- ROM and instability methods for the same functional loss without an express basis
- nerve impairment that is merely the same manifestation of the shoulder injury
- strength Table 34
What does not establish WPI by itself?
- one dislocation episode
- fear of movement alone
- a Hill-Sachs label without residual findings
- surgery alone
Motor accident examples
First dislocation with full recovery
A documented dislocation may be non-threshold, yet produce little or no permanent WPI if movement and stability recover.
Recurrent instability with axillary sensory loss
The assessor must establish whether the nerve deficit is a separate injury before any permitted combination.
Claim file preparation
Evidence checklist
Assessment source
Shoulder dislocation WPI source
Assessment source: Motor Accident Guidelines v10.1 clauses 6.24, 6.47-6.60 and 6.65-6.67; AMA4 shoulder Figures 36-44, Table 23 and Table 3, subject to source verification.
Threshold injury: Dislocation, fracture, rupture and nerve injury must be identified separately from a soft tissue sprain; WPI remains a later and separate assessment.
What the assessor checks
- active ROM rules
- separate nerve injury rule
- Table 23 title
- strength prohibition
What does not establish the result by itself
- dislocation history
- imaging label
- apprehension alone
- operation
Official sources
Related NSW CTP guides
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Frequently asked questions
- Does one dislocation create WPI?
- Not automatically. Permanent residual movement, instability, fracture or nerve findings are required.
- Can recurrent subluxation be assessed?
- Potentially, but the exact AMA4 Table 23 criteria must be verified and the finding must be objective and permanent.
- Does stabilisation surgery set the percentage?
- No. The post-treatment impairment and valid method determine the result.
- Can axillary nerve injury be added?
- Only if it is a separate verified injury and the combination complies with clause 6.53.
- Is a dislocation a threshold injury?
- The classification depends on the actual structural injury. A verified dislocation, fracture or nerve injury is not analysed as pain alone.