Lower limb injury
Knee injury after a motor accident
A knee claim should separate fracture, meniscus, ligament, patella, cartilage and nerve pathology. The most specific valid lower-limb method is used, and a limp or surgery name does not replace objective knee findings.
Motor accident injury
How can this injury happen?
Car or passenger collision
Dashboard loading, footwell intrusion or twisting during impact can injure ligaments, meniscus, patella or tibial plateau.
Motorcycle accident
A rider may twist the planted leg or strike the knee on the road, causing ligament, meniscus, fracture or patella injury.
Pedestrian or cyclist impact
Bumper impact and a fall can fracture the plateau or patella and injure ligaments or meniscus.
Injuries that can occur
- meniscus or articular cartilage injury
- ACL, PCL, MCL or LCL injury
- tibial plateau, patella or femoral condyle fracture
- patellofemoral injury or dislocation
- post-traumatic arthritis, stiffness or nerve injury
Symptoms and functional problems
- locking, catching or giving way
- loss of flexion or extension
- difficulty stairs, kneeling, squatting or prolonged standing
- swelling, instability or reduced walking tolerance
Seek urgent medical assessment
A locked knee, deformity, inability to weight-bear, threatened circulation or acute compartment symptoms requires urgent assessment.
Clinical evidence
What findings matter?
The examination should record active movement, measured laxity, effusion, alignment, meniscal signs, patella tracking and neurological status. MRI supports anatomy but does not set WPI.
| Record or examination | What it may establish | What it cannot prove alone |
|---|---|---|
| MRI, X-ray or CT | Shows meniscus, ligament, cartilage, fracture, arthritis and alignment. | A tear or fracture label does not select the final method alone. |
| Active knee ROM | Measures flexion and extension under Table 41. | Passive movement and pain estimates do not set the rating. |
| Stability and functional examination | Records cruciate/collateral laxity, patella stability, locking, gait and muscle bulk. | Giving-way complaints without measured instability are insufficient. |
Movement in daily life
How movement affects real activities
Knee flexion is needed for sitting, stairs, kneeling and squatting. Extension is needed for stable standing and the swing-through phase of walking.
Flexion
Sitting, stairs, squatting, kneeling and entering a car.
AMA4 Table 41 addresses active knee movement.
Extension
Standing stability, walking and placing the heel for a step.
A fixed extension deficit must be measured reliably.
Stability
Changing direction, uneven ground and controlled loading.
Objective ligament laxity may use a diagnosis-based method rather than being inferred from a limp.
Threshold injury is a separate question: knee sprain or soft tissue pain may be threshold. Fracture, nerve injury or partial/complete meniscus, ligament or cartilage rupture may be non-threshold if verified.
Part 6 permanent impairment
How is CTP WPI assessed?
Potential methods include Table 41 ROM, Table 62 arthritis and Table 64 diagnosis-based estimates. Clause 6.70 requires the most specific valid method and Table 6.5 controls combinations.
Measurement rules that apply
- Clauses 6.69 and 6.70 require the method that most specifically addresses the lower-limb impairment. Gait should not replace a joint, nerve, fracture or replacement method that can be applied reliably.
- Clause 6.84 requires active range of motion, a goniometer where clinically indicated and consistent repetitions when reliability is uncertain. Passive movement may inform the examination but does not set the impairment value.
- Clause 6.85 says only the most severe deficit in one direction or axis from the same lower-limb ROM table is rated. Deficits from separate tables may be combined only as the Guidelines permit.
| Method | CTP source | When it is relevant | Important limit |
|---|---|---|---|
| Knee ROM | Clauses 6.84-6.85; AMA4 Table 41 | Permanent active flexion or extension loss. | Do not add multiple deficits from the same table. |
| Arthritis/cartilage interval | Clauses 6.88-6.92; Table 62 | Properly positioned radiographs with measurable joint space. | Osteophytes, cysts and pain are ignored for this measurement. |
| Diagnosis-based estimate | Clauses 6.94-6.98; Table 64 | Listed fracture, meniscus, patella or ligament residuals with required signs. | Read footnotes and do not invent unverified rows. |
- A tibial plateau fracture and separate MCL laxity are assessed separately under clause 6.71.
- Lower-extremity impairment is converted through Table 6.4.
- Gait is a last resort and cannot be combined.
What cannot be combined?
- gait derangement with any other lower-limb evaluation
- arthritis with gait, atrophy, strength or ROM
- two methods rating the same knee instability or movement loss
What does not establish WPI by itself?
- knee pain
- MRI tear without residual signs
- subjective giving way
- arthroscopy alone
Motor accident examples
Dashboard knee with PCL injury
Measured residual PCL laxity may support a diagnosis-based method; pain and MRI alone do not.
Tibial plateau fracture with MCL laxity
Clause 6.71 expressly treats the fracture and separate ligament laxity as separate injuries before WPI combination.
Claim file preparation
Evidence checklist
Assessment source
Knee WPI assessment source
Assessment source: Motor Accident Guidelines v10.1 clauses 6.68-6.75 and 6.84-6.102; AMA4 Tables 41, 51-54, 62, 64 and Table 6.4.
Threshold injury: Fracture, nerve injury and verified meniscus/ligament/cartilage rupture may be non-threshold; knee sprain may remain threshold.
What the assessor checks
- most specific method
- knee ROM
- arthritis measurement
- diagnosis-based estimate
- combination rules
What does not establish the result by itself
- pain
- MRI alone
- giving way
- arthroscopy
Official sources
Related NSW CTP guides
Free claim check
Review the medical evidence and insurer decision together
Send the accident date, insurer letter, scans or reports and any deadline shown. NSW CTP Claim is a specialised service of Stephen Young Lawyers. Legal services are provided by Stephen Young Lawyers.
Frequently asked questions
- Does an MRI tear set knee WPI?
- No. The assessor needs the permanent residual findings and correct method.
- Can knee ROM and arthritis be combined?
- Not where arthritis is the basis of assessment; clause 6.91 prohibits combining it with ROM.
- Can gait be added?
- No. Gait is a last resort and cannot be combined with another lower-limb evaluation.
- How is cartilage loss assessed?
- Table 62 uses the articular cartilage interval on properly positioned radiographs.
- Does surgery create WPI?
- No. The stable post-treatment impairment and valid method determine the result.