Front-of-knee injury
Patella and patellofemoral injury after a motor accident
A patella injury may involve fracture, dislocation, tendon or cartilage damage. Anterior knee pain alone is not a WPI method; the assessment must identify movement loss, objective instability, fracture residual or properly measured cartilage loss.
Motor accident injury
How can this injury happen?
Car or passenger collision
Direct dashboard impact can fracture the patella or damage patellofemoral cartilage.
Motorcycle accident
A fall onto the knee or twisting with the patella displaced can cause fracture or dislocation.
Pedestrian or cyclist impact
Bumper impact and ground contact can injure the patella, extensor mechanism and cartilage.
Injuries that can occur
- patella fracture or malunion
- patella dislocation or recurrent instability
- patellofemoral cartilage injury
- patellar or quadriceps tendon rupture
- post-traumatic arthritis or stiffness
Symptoms and functional problems
- anterior knee pain on stairs or rising
- instability or apprehension
- reduced flexion, extension or kneeling tolerance
- crepitus, swelling or extensor lag
Seek urgent medical assessment
Inability to straight-leg raise, deformity or suspected displaced fracture requires urgent assessment.
Clinical evidence
What findings matter?
The report should identify fracture, tracking, stability, extensor continuity and cartilage evidence. Crepitus and pain need a valid method rather than a standalone percentage.
| Record or examination | What it may establish | What it cannot prove alone |
|---|---|---|
| X-ray, skyline view or CT | Shows fracture, alignment, joint congruity and patellofemoral cartilage interval. | Ordinary imaging without defined position may not support Table 62. |
| Tracking and stability examination | Records apprehension, recurrent dislocation and extensor mechanism. | Apprehension alone is not a table row. |
| Active knee ROM | Measures permanent flexion and extension loss. | Do not duplicate a diagnosis-based consequence. |
Movement in daily life
How movement affects real activities
Patellofemoral problems often affect knee flexion under load for stairs, squatting and rising, while extension is essential for a stable step and straight-leg control.
Knee flexion
Stairs, squatting, kneeling and sitting.
Table 41 applies when active movement loss is the specific impairment.
Knee extension
Standing, walking and straight-leg control.
Extensor lag must be distinguished from pain-limited effort.
Patella tracking and stability
Controlled bending and direction change.
A Table 64 diagnosis row is used only if exact criteria and footnotes apply.
Threshold injury is a separate question: patella fracture or verified cartilage/tendon/ligament rupture may be non-threshold. Patellofemoral pain without rupture may be threshold.
Part 6 permanent impairment
How is CTP WPI assessed?
Potential methods include Table 41 ROM, Table 62 arthritis/cartilage interval and Table 64 diagnosis-based estimates. The most specific valid method is selected.
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; 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 showing cartilage thickness. | Pain, crepitus and osteophytes do not set the interval. |
| Diagnosis-based estimate | Clauses 6.94-6.97; Table 64 | A listed fracture or instability residual. | Exact row values require readable AMA4. |
- Distinguish fracture, instability and cartilage methods.
- Document residual signs at examination.
- Convert lower-extremity impairment through Table 6.4.
What cannot be combined?
- arthritis with ROM, gait, atrophy or strength
- gait with any other lower-limb evaluation
- ROM and diagnosis method for the same patellofemoral consequence
What does not establish WPI by itself?
- anterior knee pain
- crepitus
- apprehension alone
- arthroscopy or fixation
Motor accident examples
Dashboard patella fracture
The fracture history is important, but WPI depends on the applicable residual diagnosis, movement or arthritis method.
Recurrent patella instability
Current objective instability and exact Table 64 criteria are needed; subjective apprehension is insufficient.
Claim file preparation
Evidence checklist
Assessment source
Patella WPI source
Assessment source: Motor Accident Guidelines v10.1 clauses 6.68-6.75 and 6.84-6.97; AMA4 Tables 41, 62, 64 and Table 6.4.
Threshold injury: Fracture or verified cartilage/tendon/ligament rupture may be non-threshold; pain syndrome without rupture may remain threshold.
What the assessor checks
- ROM
- arthritis radiology
- diagnosis-based estimate
- combination rules
What does not establish the result by itself
- pain
- crepitus
- apprehension
- surgery
Official sources
Related NSW CTP guides
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Frequently asked questions
- Does patella fracture have fixed WPI?
- No. The permanent residual and most specific valid method determine WPI.
- Can crepitus be rated?
- Not by itself. A permitted diagnosis, movement or arthritis method is required.
- How is cartilage loss measured?
- Table 62 uses the articular cartilage interval on properly positioned radiographs.
- Can ROM and arthritis be combined?
- No when arthritis is the assessment basis, because clause 6.91 prohibits combining it with ROM.
- Does patella surgery set the percentage?
- No. Surgery is evidence; the stable residual impairment controls.