Overview for NSW injured workers
Start with the dispute, not just the diagnosis
May be relevant when
Benefits to check
Legal help is useful when
How this affects your claim in practice
In a lower limb muscle atrophy claim, the diagnosis is only the starting point. The records should connect bilateral thigh measurements 10 cm above the patella with knees extended and muscles relaxed and bilateral maximum calf measurements taken at the same level with the worker's practical limits, including standing, walking, stairs, kneeling, squatting, driving and load carrying and safe duties that avoid unsafe mobility demands. If the insurer disputes whether swelling, varicose veins or opposite-limb disease invalidates comparison, the response should address that reason directly.
Assessment source
- NSW Guidelines for the Evaluation of Permanent Impairment, paras 1.8-1.12: NSW Guidelines control the assessment method and AMA5 is used only where adopted and not modified.
- NSW Guidelines para 1.12: AMA5 Chapter 18 pain is excluded; chronic pain is assessed through the underlying diagnosed condition, while CRPS is assessed under the relevant NSW method.
- NSW Guidelines para 1.15: assessment should usually wait until maximum medical improvement, meaning the condition is stable and unlikely to change substantially in the next year.
- NSW Guidelines Chapter 3 applies AMA5 Chapter 17 only as modified by NSW. Paragraphs 3.2-3.7 require the most specific valid method, selection of the highest valid evaluation where more than one method applies, common units before combination, and a 40% WPI lower-limb maximum.
- NSW Guidelines para 1.24: activities of daily living must not be used to increase or reduce a calculated lower-extremity impairment. Functional examples explain the measurement; they are not an extra percentage.
- NSW Guidelines paras 3.8-3.15 and corrected AMA5 Tables 17-4 and 17-6: true leg length, gait, unilateral atrophy and manual muscle testing each have their own measurement and non-combination requirements.
- NSW Guidelines paras 3.16-3.18: inconsistent range-of-motion findings are invalid; values from different movement planes within one joint are added; joint ankylosis uses the corrected NSW optimum-position table and positional additions.
- NSW Guidelines paras 3.19-3.24: arthritis means radiological cartilage loss for impairment purposes. It cannot be assumed from pain, and the arthritis method cannot be combined with gait, atrophy, strength or range of motion.
- NSW Guidelines paras 3.10-3.15 and 3.32-3.35: gait is a last resort; gait, atrophy, muscle testing and peripheral-nerve methods can duplicate lower-limb function and must follow Table 17-2 non-combination rules; CRPS uses the NSW Chapter 17 method rather than AMA5 Chapter 18 pain.
- NSW Guidelines paras 3.26-3.30 and Tables 3.2-3.4: NSW modifies diagnosis-based estimates, tibial plateau fracture, patello-femoral and ankle replacement, tibia-os calcis angle and persistent plantar fasciitis. Hip and total-knee replacements use AMA5 Tables 17-33 to 17-35 subject to the NSW corrections.
What injuries or conditions may be assessed?
Unilateral lower-limb muscle atrophy may follow an accepted muscle, joint, fracture or disuse condition and can affect the thigh, calf or both.
- Atrophy from a spinal nerve-root disorder is generally accounted for in the spine assessment rather than duplicated under Chapter 3.
- Swelling, varicose veins, opposite-limb injury or another abnormal comparison limb may make circumference comparison invalid.
Symptoms and findings that matter
Thigh circumference is compared 10 cm above the patella with the knee extended and muscles relaxed. Calves are compared at the same maximum level.
For lower limb muscle atrophy, range of motion is normally measured three times in each relevant plane and the greatest valid result is used. If repeated readings or findings between examinations are materially inconsistent, ROM is not a valid impairment parameter.
If true leg length is relevant to lower limb muscle atrophy, manual measurement is an exception to the greatest-reading rule: three readings are averaged. The opposite joint or limb is also compared where it provides a valid baseline.
Where lower limb muscle atrophy is assessed through manual muscle weakness, the examiner uses the six Medical Research Council grades from 0 to 5. Those grades are ordinal rather than evenly spaced, and the NSW method uses AMA5 Table 17-8; electrodiagnostic results do not replace the manual muscle test.
An impairment report for lower limb muscle atrophy may need a diagnosis-based estimate, radiological cartilage-loss method, replacement score, true limb-length difference, unilateral atrophy, muscle grade, named-nerve deficit or gait method instead of, or in a limited case alongside, ROM.
What investigations are usually relevant
Investigations for lower limb muscle atrophy may include weight-bearing X-rays, CT, MRI, ultrasound or operation records identifying the actual joint, fracture, tendon, ligament, cartilage, prosthesis or nerve condition and repeat goniometer measurements, stability tests, alignment findings and comparison with the unaffected side where that comparison is valid. Each result should answer a defined clinical question and be read with the examination, diagnosis and history.
- Orthopaedic, rehabilitation and physiotherapy records showing whether the condition has reached maximum medical improvement.
- Certificates of capacity and duties evidence about walking, standing, stairs, kneeling, squatting, driving, lifting and uneven ground. These explain claim impact but do not alter the WPI calculation.
How WPI is assessed for this body part
For lower limb muscle atrophy, NSW Guidelines Chapter 3 applies AMA5 Chapter 17 subject to NSW corrections. The most specific valid method is used, and where more than one valid method applies the highest valid evaluation is generally selected unless Table 17-2 permits a combination.
If ROM is valid for lower limb muscle atrophy, values in different planes of the same joint are added. Regional values in the same limb are expressed in the same unit and combined before conversion to WPI.
Arthritis in an assessment of lower limb muscle atrophy requires radiologically measured cartilage loss. For a knee, only the most impaired compartment is used. Arthritis cannot be combined with gait, atrophy, strength or ROM for the same loss.
For lower limb muscle atrophy, gait remains a last-resort standalone method. Atrophy, manual muscle testing, peripheral nerve impairment and gait can duplicate strength loss and cannot be stacked. A diagnosis-based estimate is combined only where Table 17-2 permits it.
The calculation for lower limb muscle atrophy cannot be changed because of activities of daily living under NSW paragraph 1.24. Functional descriptions help explain the evidence but are not an uplift or deduction.
Table and value examples
Thigh or calf difference 0-0.9 cm
0% WPI (0% LEI)The other limb must provide a valid comparison.
Source: NSW-corrected AMA5 Table 17-6
Thigh or calf difference 1-1.9 cm
2% WPI (6% LEI)Thigh is measured 10 cm above the patella with the knee extended and muscles relaxed; calf is compared at the same maximum level.
Source: NSW-corrected AMA5 Table 17-6
Thigh or calf difference 2-2.9 cm
4% WPI (11% LEI)Swelling, varicose veins or another condition affecting the comparison limb can invalidate this method.
Source: NSW-corrected AMA5 Table 17-6
Thigh or calf difference 3 cm or more
5% WPI (12% LEI)Atrophy cannot be combined with another method that rates the same strength loss, such as gait, manual muscle testing or peripheral nerve impairment.
Source: NSW-corrected AMA5 Table 17-6
Worked assessment illustrations
These examples paraphrase the assessment reasoning in the source material. They explain method only and are not predicted outcomes.
Illustration 1
Measured unilateral thigh atrophy
Assumed facts: At maximum medical improvement, both thighs are measured 10 cm above the patella with the knees extended and muscles relaxed. The affected thigh is reproducibly 2.4 cm smaller and the comparison limb is normal.
Method: A 2.4 cm difference falls within the NSW-corrected 2-2.9 cm row. The assessor must first exclude swelling, varicose veins or another condition that makes the opposite limb an invalid comparator.
Illustrative outcome: The corrected row is 4% WPI (11% LEI). The same strength loss cannot also be rated by gait, manual muscle testing or peripheral nerve impairment. This is an illustration only.
Source: NSW Guidelines paras 3.13-3.15 and corrected AMA5 Table 17-6
What usually does not increase WPI
Atrophy is not added to gait, manual muscle testing or peripheral nerve impairment where those methods rate the same strength loss.
Pain, tenderness, swelling or difficulty walking does not create a percentage without a valid lower-limb method.
A scan label, surgery name or recommendation for surgery is not a fixed WPI result.
Work restrictions, weekly payments and inability to resume the pre-injury job are important claim issues but are not themselves impairment measurements.
Activities of daily living cannot be used to increase or reduce the calculated lower-extremity rating.
Evidence checklist
The records for lower limb muscle atrophy should include the accepted injury description, date and any insurer decision limiting the body part or diagnosis and imaging and operation reports, including the relevant side, level, compartment and procedure. They are most useful when the diagnosis, examination and practical restrictions are consistent.
- Repeat movement, stability, alignment, circumference, limb-length or neurological measurements required by the selected method.
- A calculation worksheet identifying the table, regional unit, permitted combinations, conversion and rounding.
How this injury commonly happens at work
Work-related lower limb muscle atrophy can arise through an accepted fracture, joint or muscle injury followed by permanent unilateral wasting and prolonged disuse after surgery or immobilisation where causally supported. The chronology should identify the actual task or event and when symptoms or function changed.
Work-related lower limb muscle atrophy can arise through direct muscle trauma leaving stable loss of bulk. The chronology should record the actual task or event and the point at which symptoms or function changed.
Common insurer disputes
For lower limb muscle atrophy, an insurer may dispute whether swelling, varicose veins or opposite-limb disease invalidates comparison and whether the difference is reproducible. The written decision should be answered with evidence directed to those reasons.
Further disputes about lower limb muscle atrophy may concern whether the wasting comes from a spinal nerve-root condition and whether atrophy duplicates gait, manual muscle testing or nerve impairment. The decision notice should identify which issue is relied on and the evidence said to support it.
Treatment and surgery issues
Depending on the diagnosis and treating opinion, management of lower limb muscle atrophy may involve rehabilitation and strength recovery before maximum medical improvement is considered. The request should explain the expected functional benefit and its connection to the accepted injury.
Weekly payments and work capacity
Capacity evidence for lower limb muscle atrophy should address standing, walking, stairs, kneeling, squatting, driving and load carrying and safe duties that avoid unsafe mobility demands. Proposed duties must be sustainable for the proposed hours, not merely possible once.
For lower limb muscle atrophy, capacity evidence should address travel to work and medication effects where relevant and weekly payment decisions where partial capacity is overstated. The question is whether those activities can be performed safely, reliably and for the proposed hours—not whether a task can be attempted once.
How NSW Work Injury Claim can help
For lower limb muscle atrophy, a claim review can help to clarify diagnosis and mechanism of injury and compare work duties with medical restrictions. The purpose is to identify the precise decision and the evidence needed for the next available step, not to promise an outcome.
For lower limb muscle atrophy, a claim review can help to respond to treatment or work capacity disputes and prepare WPI evidence when the condition becomes stable. The purpose is to identify the precise decision and the evidence needed for the next available step, not to promise an outcome.
Common questions about lower limb muscle atrophy claims
How can work cause or aggravate lower limb muscle atrophy?
For lower limb muscle atrophy, the relevant work history may include an accepted fracture, joint or muscle injury followed by permanent unilateral wasting, prolonged disuse after surgery or immobilisation where causally supported, and direct muscle trauma leaving stable loss of bulk. A claim still depends on the actual chronology and medical evidence. The records should identify what changed, when symptoms began or worsened, and how the diagnosed condition affects the worker's duties.
How is WPI assessed for lower limb muscle atrophy?
For lower limb muscle atrophy, NSW Guidelines Chapter 3 applies AMA5 Chapter 17 subject to NSW corrections. The most specific valid method is used, and where more than one valid method applies the highest valid evaluation is generally selected unless Table 17-2 permits a combination. Thigh circumference is compared 10 cm above the patella with the knee extended and muscles relaxed. Calves are compared at the same maximum level. The assessor must apply the NSW Guidelines to the accepted, stable condition; the diagnosis or an operation does not by itself determine a percentage.
Which records are most useful for a lower limb muscle atrophy assessment?
A lower limb muscle atrophy assessment commonly needs the accepted injury description, date and any insurer decision limiting the body part or diagnosis, imaging and operation reports, including the relevant side, level, compartment and procedure, repeat movement, stability, alignment, circumference, limb-length or neurological measurements required by the selected method, and a calculation worksheet identifying the table, regional unit, permitted combinations, conversion and rounding. Those records are most useful when they describe the same diagnosis, examination findings, treatment history and practical work restrictions.
What does an insurer commonly dispute about lower limb muscle atrophy?
For lower limb muscle atrophy, common issues include whether swelling, varicose veins or opposite-limb disease invalidates comparison, whether the difference is reproducible, and whether the wasting comes from a spinal nerve-root condition. The response should address the insurer's stated reason with the relevant chronology, clinical findings, investigations and duties evidence rather than relying on the diagnosis alone.
How can lower limb muscle atrophy affect weekly payments and suitable duties?
Capacity evidence for lower limb muscle atrophy may need to address standing, walking, stairs, kneeling, squatting, driving and load carrying, safe duties that avoid unsafe mobility demands, and travel to work and medication effects where relevant. A certificate should describe what the worker can do safely and sustainably. Proposed duties should then be checked against those restrictions and the real demands of the job.
Does lower limb muscle atrophy automatically receive a fixed WPI percentage?
No. For lower limb muscle atrophy, one verified example is thigh or calf difference 0-0.9 cm: 0% WPI (0% LEI), under NSW-corrected AMA5 Table 17-6. That value applies only when its stated criteria are met. Atrophy is not added to gait, manual muscle testing or peripheral nerve impairment where those methods rate the same strength loss.
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