What should be checked before relying on a WPI figure?
Check maximum medical improvement, the body area, objective findings, the NSW Guideline chapter and any NSW modification before relying on a percentage.
Can this page calculate your percentage?
No. WPI depends on an assessor, maximum medical improvement, objective findings and the NSW Guidelines. This page is general information only.
Permanent impairment assessment
How permanent impairment is assessed for Hip, knee, ankle, foot, limb length, lower limb nerves and gait
Lower limb WPI is method-driven. The assessor should identify the specific structure affected, then choose the most specific valid NSW/AMA5 method: ROM, arthritis/cartilage loss, diagnosis-based estimate, leg length, replacement scoring, nerve impairment, ankylosis or, only as a last resort, gait derangement.
What injuries can happen to this body part?
- Hip fracture, labral injury, hip arthritis, hip replacement and pelvic/acetabular involvement
- Knee meniscal tear, ACL/PCL/MCL/LCL laxity, patello-femoral injury, tibial plateau fracture, cartilage loss and knee replacement
- Ankle fracture, ankle instability, ankle replacement, foot fracture, plantar fasciitis, lower limb nerve injury, leg length discrepancy and gait issues
Symptoms and findings that matter
- The precise body part and diagnosis, not merely lower limb pain
- The most specific applicable method and whether another method is prohibited from combination
- ROM reliability, opposite-side comparison and whether pain/effort makes measurements inconsistent
- Radiological cartilage loss where arthritis is alleged
- Permanent walking-aid use only if gait derangement is truly the last-resort method
What investigations are usually relevant?
- Treating specialist report and final impairment assessment at maximum medical improvement
- Imaging, pathology, audiology, ophthalmology, respiratory, nerve or functional testing that fits the body system
- Operative reports, discharge summaries, rehabilitation records and objective clinical measurements where relevant
How WPI is assessed for this body part
- Lower limb WPI is method-driven. The assessor should identify the specific structure affected, then choose the most specific valid NSW/AMA5 method: ROM, arthritis/cartilage loss, diagnosis-based estimate, leg length, replacement scoring, nerve impairment, ankylosis or, only as a last resort, gait derangement.
- Assessment source: NSW Guidelines Chapter 3 lower extremity, including NSW corrections for leg length, gait, ankle ROM, ankylosis, tibial plateau fracture, ankle replacement, tibia-os calcis angle and lower limb nerve assessment.
- The assessor should explain maximum medical improvement, the body-system chapter, the method selected, any NSW modification, and why the objective findings fit that method.
How movement affects the assessment
- Hip ROM affects sitting, stairs, dressing, turning and getting in or out of vehicles.
- Knee ROM affects squatting, kneeling, stairs, chairs, gait and standing posture.
- Ankle and foot ROM affects push-off, uneven surfaces, ladders, driving pedals and balance, but gait derangement is not an add-on to another lower limb rating.
NSW lower limb global rules
Most specific method firstUse the method that most specifically addresses the lower limb impairment where possible, rather than a broad fallback label.
Highest valid assessmentWhere more than one valid lower limb method applies, the NSW Guidelines generally require the assessment that gives the highest valid rating, unless a specific rule prevents it.
Do not exceed amputation valueA lower limb part or region cannot exceed the applicable amputation value. The whole lower limb maximum is 40% WPI, except where a specific gait table gives WPI directly.
Gait derangement is last resortGait derangement should be used only as a last resort and cannot be combined with other lower extremity assessment methods.
Permanent walking aid onlyIf a walking aid is relied on, the evidence should show permanent use, not a temporary aid during treatment or recovery.
ROM reliabilityROM can be unreliable where effort, pain behaviour or inconsistency affects measurement. The opposite side should be compared where relevant.
Arthritis needs imagingArthritis/cartilage loss must be radiologically assessed. Pain, crepitus or a broad MRI comment is not enough by itself.
Lower limb ROM and consistency rules
Use ROM only where validROM should be used only where the measurements are consistent and clinically reliable.
Same joint planesMultiple valid planes within the same lower limb joint are added, not combined, under the NSW lower limb method.
Opposite side comparisonIf the opposite side has reduced average mobility, the assessor should explain whether baseline deduction or comparison is needed.
Knee varus/valgus with arthritisVarus or valgus deformity due to compartment arthritis is not combined with ROM; both are calculated and the greater valid value is used.
NSW gait derangement limits
Last resort onlyUse gait derangement only where no more specific lower limb method adequately assesses the impairment.
No combinationDo not combine gait derangement with another lower extremity method such as ROM, arthritis, muscle atrophy, nerve impairment or replacement scoring.
Pathological supportThe gait finding should be supported by objective pathology and examination findings, not only subjective walking difficulty.
Trendelenburg deletionNSW deletes the Trendelenburg item in AMA5 Table 17-5 because it is considered insufficiently reliable.
NSW arthritis and cartilage-loss rules
Cartilage loss definitionOsteoarthritis for lower limb WPI is assessed as cartilage loss, usually through radiologically determined joint-space intervals in AMA5 Table 17-31 as adopted by NSW.
Knee compartmentsThe knee has three compartments. The major impairment compartment is used; compartments are not added or combined.
Cannot combine with some methodsArthritis rating cannot be combined with gait disturbance, muscle atrophy, muscle strength or ROM.
Patello-femoral cautionPatello-femoral arthritis/crepitus is not added again when assessing arthritis of the knee joint itself.
Resurfacing proceduresNSW gives no additional impairment for resurfacing procedures for localised cartilage lesions or defects in major joints.
NSW corrected Table 17-4 leg length discrepancy rows
0 to 1.9 cm0% WPI.
2 to 2.9 cm3% WPI (8% lower extremity impairment).
3 to 3.9 cm5% WPI (13% lower extremity impairment).
4 to 4.9 cm7% WPI (18% lower extremity impairment).
5 cm or more8% WPI (19% lower extremity impairment).
Measurement methodThe clinical method must be identified. CT is preferred if available, but is not ordered solely for the impairment assessment.
Practical WPI examples
- A worker with a knee injury may need a meniscus, ligament, arthritis, tibial plateau, ROM or replacement-joint pathway depending on the residual findings.
- A worker with ankle restriction should be checked against the corrected NSW ankle ROM rows before falling back to gait derangement.
- A worker with leg-length difference needs the corrected NSW table and a proper measurement method, not a broad description of limping.
Evidence checklist
- A clear diagnosis and the body area being assessed
- Records showing the condition has reached maximum medical improvement, if that is the issue
- Specialist reports, imaging reports and treating notes relied on by the assessor
- Objective findings on examination, not only symptoms described by the injured person
- A work and treatment chronology explaining the injury, treatment, surgery and recovery path
- Any previous injury, degeneration, congenital issue or non-work cause that needs apportionment considered
- X-rays or CT/MRI where relevant
- Operative reports
- Final orthopaedic or rehabilitation reports
- ROM measurements
- Gait and aid records
- Work-duty evidence about standing, walking, kneeling, stairs and lifting
What usually does not increase WPI
- Assuming a scan result automatically gives a WPI percentage
- Confusing pain, disability or inability to work with permanent impairment
- Ignoring maximum medical improvement before arranging an assessment
- Using an AMA5 table without checking whether the NSW Guidelines modify or replace it
- Double counting the same impairment through two methods when the Guidelines require one method
- Using gait derangement when a specific lower limb method applies
- Combining arthritis with ROM or gait when NSW prohibits it
- Assuming pain or surgery automatically creates a fixed WPI percentage
Assessment source
Assessment source: Assessment source: NSW Guidelines Chapter 3 lower extremity, including NSW corrections for leg length, gait, ankle ROM, ankylosis, tibial plateau fracture, ankle replacement, tibia-os calcis angle and lower limb nerve assessment.
This section is source-backed general information. It is not a WPI assessment and is not legal advice.
- SIRA NSW Workers Compensation Guidelines for the Evaluation of Permanent Impairment: Source for the NSW assessment framework, MMI, AMA5 adoption, NSW modifications and exclusions.
- SIRA lower extremity chapter: Source for NSW lower extremity assessment rules, gait derangement limits and NSW-modified lower limb tables.
Related injury and claim pages
Need a practical claim check?
If an impairment percentage, medical assessment or insurer decision is affecting your NSW injury claim, send the decision or report for a practical review. This is general information only and does not guarantee any result.
Request a free claim checkAssessment scope for Lower Limb WPI Assessment
The assessment scope for Lower Limb WPI Assessment should be stated precisely before any percentage is considered. The file should identify whether that label describes the primary diagnosed condition, a symptom of another injury, a regional overview or one component of a broader impairment. Findings from another body area or diagnosis should not be transferred without explanation. The report should connect the stated condition to the correct NSW Guideline chapter, objective findings, treatment history and any permitted combination or apportionment method. This distinction is particularly important where similar page labels cover different clinical questions.
- Confirm the diagnosis and body area being assessed as Lower Limb
- Separate condition-specific findings from overlapping symptoms or injuries in another body area
- Check that the selected NSW Guideline chapter and method match the condition actually assessed
- Explain any combination, apportionment or exclusion rather than relying on the page label alone
Start with maximum medical improvement
Permanent impairment should generally be assessed when the condition is stable and unlikely to change substantially in the next year. Treatment, surgery and rehabilitation history may affect whether the timing is appropriate.
Use the NSW Guidelines first
The NSW Guidelines adopt AMA5 in many areas, but NSW modifications prevail. Do not assume an AMA5 table applies without checking the NSW chapter and any public SIRA clarification.
Keep the assessment practical
A useful assessment file separates diagnosis, objective findings, surgery history, work capacity issues, apportionment questions and the body-area method used by the assessor.
Ask about an impairment issueDocuments and records
Injury evidence to organise early
The useful records depend on how the injury happened, when symptoms were recorded and how treatment or work capacity changed.
- Date, location and short description of the injury event
- Medical certificates, reports, scans, treatment records or hospital documents
- Employer, insurer, police, incident or venue records where relevant
- Photos, witness details, dashcam or other supporting material if available
- Income, superannuation, work capacity or leave records where relevant
- Letters, emails, claim numbers and decisions already received
Common questions
Injury evidence questions
Short general answers only. The right next step depends on the facts, dates and documents.
Is WPI the same as being unable to work?
No. WPI is a medical impairment measure. Work capacity, weekly payments, damages, treatment disputes and TPD issues are separate questions, although the evidence may overlap.
Does pain alone create a WPI percentage?
Not by itself. NSW workers compensation excludes AMA5 Chapter 18 on pain. Chronic pain is assessed through the underlying diagnosed condition where the Guidelines permit it.
Can secondary psychological symptoms be added to physical WPI?
In NSW workers compensation, secondary psychiatric or psychological impairment is not assessed as permanent impairment. Primary psychological impairment is assessed separately and is not combined with physical WPI.
Injury pathway enquiry
Not sure which claim type matches the injury?
Start with how the injury happened, what medical records exist and how work or daily activity has changed. The same injury can sit in different pathways.