Lower-Limb Alignment (HKA / MAD / mLDFA / MPTA / JLCA) — free guideline decision tool
Standing long-leg film: HKA deviation, mechanical axis deviation, mLDFA, MPTA and JLCA to determine varus/valgus and the deformity source (femur / tibia / joint). Includes how to measure and what each value means. Instant, browser-side.
Open guideline tool →Guideline-based
Implements the decision logic from published clinical guidelines.
Runs in your browser
No installation. Enter the patient's values and get a guideline recommendation instantly.
Data stays local
Nothing is uploaded. Results are for licensed clinicians only.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Alignment direction | Valgus |
|---|---|
| HKA deviation from 180° | 6 ° |
| MAD (medial positive) | 20 mm |
| mLDFA | 88 ° |
| MPTA | 84 ° |
| JLCA | 3 ° |
→HKA deviation from 180°6°
- HKA deviation from 180°：6 ° → 3–10°: mild–moderate malalignment
- MAD (medial positive)：20 mm → > 15 mm medial: varus
- mLDFA：88 ° → 85–90°: normal (87 ± 3°)
Common questions
What is Lower-Limb Alignment (HKA / MAD / mLDFA / MPTA / JLCA)?
Standing long-leg film: HKA deviation, mechanical axis deviation, mLDFA, MPTA and JLCA to determine varus/valgus and the deformity source (femur / tibia / joint). Includes how to measure and what each value means. Instant, browser-side.
How is Lower-Limb Alignment (HKA / MAD / mLDFA / MPTA / JLCA) calculated? What is the core formula?
HKA deviation from 180° ≤ 3°: neutral alignment HKA deviation from 180° 3–10°: mild–moderate malalignment HKA deviation from 180° ≥ 10°: marked malalignment MAD (medial positive) < 1 mm (lateral): valgus MAD (medial positive) 1–15 mm medial: normal (8 ± 7 mm) MAD (medial positive) > 15 mm medial: varus mLDFA < 85°: distal femoral valgus mLDFA 85–90°: normal (87 ± 3°) mLDFA > 90°: distal femoral varus MPTA < 85°: proximal tibial varus (typical HTO indication) MPTA 85–90°: normal (87 ± 3°) MPTA > 90°: proximal tibial valgus JLCA 0–2°: normal JLCA > 2°: intra-articular contribution (cartilage loss / laxity)
When is Lower-Limb Alignment (HKA / MAD / mLDFA / MPTA / JLCA) used?
Knee & lower-limb alignment imaging: lateral knee, axial CT/MRI and standing long-leg films — patellar instability and osteotomy / arthroplasty planning.
What are the key clinical points for Lower-Limb Alignment (HKA / MAD / mLDFA / MPTA / JLCA)?
Standing bilateral long-leg AP (patellae forward). Each value is graded against published reference ranges. Measurement technique and positioning change the numbers — compare like with like on follow-up. Part of the YuanDoctor MSK measurement topic.
What are the limits and cautions when using Lower-Limb Alignment (HKA / MAD / mLDFA / MPTA / JLCA)?
For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
Does Lower-Limb Alignment (HKA / MAD / mLDFA / MPTA / JLCA) upload patient data? Where is it calculated?
Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
How is Lower-Limb Alignment (HKA / MAD / mLDFA / MPTA / JLCA) calculated in practice? Can you show a worked example?
Inputs: Alignment direction Valgus, HKA deviation from 180° 6 °, MAD (medial positive) 20 mm, mLDFA 88 °, MPTA 84 °, JLCA 3 ° → Result: HKA deviation from 180° 6 °（HKA deviation from 180°: 6 ° → 3–10°: mild–moderate malalignment, MAD (medial positive): 20 mm → > 15 mm medial: varus, mLDFA: 88 ° → 85–90°: normal (87 ± 3°)）
Run Lower-Limb Alignment (HKA / MAD / mLDFA / MPTA / JLCA) now
Standing long-leg film: HKA deviation, mechanical axis deviation, mLDFA, MPTA and JLCA to determine varus/valgus and the deformity source (femur / tibia / joint). Includes how to measure and what each value means. Instant, browser-side.
Open guideline tool →For licensed clinicians. Not a substitute for clinical judgement.
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