Leg Length Discrepancy
Classify measured structural and functional leg-length components separately.
Description
Leg-length discrepancy screening compares structural and functional components separately with the same tolerance.
Leg-length discrepancy screening compares structural and functional components separately with the same tolerance. The returned total adds their supplied magnitudes.1
Classify measured structural and functional leg-length components separately.
When to use Leg Length Discrepancy
Use this tool to classify measured structural and functional leg-length components separately.
Prepare the measured movement, timing, load or preassigned score requested. Keep protocols, units, paired measurements and caller-selected thresholds consistent.
How to use Leg Length Discrepancy and understand its results
- Prepare the measured movement, timing, load or preassigned score requested. Keep protocols, units, paired measurements and caller-selected thresholds consistent.
- Enter structuralDifferenceCm, functionalDifferenceCm, toleranceCm using the field table and calculation rules, then run the tool.
- Read totalDifferenceCm, discrepancyType. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| structuralDifferenceCm | Structural difference cm | number | Required |
| functionalDifferenceCm | Functional difference cm | number | Required |
| toleranceCm | Tolerance cm | number | Required |
Enter nonnegative differences/tolerance cm. Return total and mixed, structural, functional or none according to strict component flags.
total=structural+functional; componentFlag=component>tolerance Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| totalDifferenceCm | Total difference cm | number |
| discrepancyType | Discrepancy type | string |
{
"input": {
"structuralDifferenceCm": 1,
"functionalDifferenceCm": 1,
"toleranceCm": 0.2
},
"output": {
"totalDifferenceCm": 2,
"discrepancyType": "mixed"
}
}Limitations and assumptions
No examination, directional cancellation or causal diagnosis is performed.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Step Width Screen: Compare step width with caller-provided base-of-support limits. For a complementary task, use Knee Over Pedal Offset: Measure knee-over-pedal-spindle horizontal offset at a specified crank position.
References
-
Leg Length Discrepancy — tool.io
Similar or alternative tools
- Step Width Screen
Compare step width with caller-provided base-of-support limits.
- Knee Over Pedal Offset
Measure knee-over-pedal-spindle horizontal offset at a specified crank position.