Home › Clinical Tools › Hip FAI / dysplasia

🦵 Hip Dysplasia & FAI Measurements (LCEA / Tönnis / Alpha / Neck-Shaft)

UseHip (adult) imaging: AP pelvis, Dunn view, CT/MRI — dysplasia, FAI and hip-preservation assessment.

Loading calculator…

SourceWiberg G. Studies on dysplastic acetabula and congenital subluxation of the hip joint. Acta Chir Sc…

Runs locally in your browser (no PHI uploaded). For licensed clinicians — not a substitute for clinical judgement.
Stored on this device for revisit reminders

This-shift next steps

After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.

Paste the link in Slack, Teams, X, or LinkedIn — the preview image comes from this page’s Open Graph card.

Methodology · worked example, guidelines & full notes
Clinical takeaway

Standard AP pelvis (coccyx tip over the symphysis, 1–3 cm).

When to use

Hip (adult) imaging: AP pelvis, Dunn view, CT/MRI — dysplasia, FAI and hip-preservation assessment.

How it works

Lateral center-edge angle < 20°: acetabular dysplasia Lateral center-edge angle 20–25°: borderline dysplasia Lateral center-edge angle 25–39°: normal Lateral center-edge angle ≥ 40°: overcoverage (pincer FAI) Tönnis angle < 0°: overcoverage (pincer) Tönnis angle 0–10°: normal Tönnis angle > 10°: dysplasia (steep sourcil) Alpha angle ≤ 55°: normal Alpha angle > 55°: cam morphology (> 60° more specific) Neck-shaft angle < 120°: coxa vara Neck-shaft angle 120–140°: normal (mean ~125–135°) Neck-shaft angle > 140°: coxa valga Femoral version < 5°: decreased version / retroversion (worsens impingement) Femoral version 5–25°: normal range (mostly 10–20°) Femoral version > 25°: excessive anteversion (worsens instability) Minimum joint space width < 2 mm: marked narrowing — poor hip-preservation outcome Minimum joint space width 2–3 mm: mild narrowing Minimum joint space width ≥ 3 mm: normal

Key points

  • Standard AP pelvis (coccyx tip over the symphysis, 1–3 cm).
  • 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.

References

  • Wiberg G. Studies on dysplastic acetabula and congenital subluxation of the hip joint. Acta Chir Scand 1939;83(Suppl 58)
  • Tannast M, et al. What are the radiographic reference values for acetabular under- and overcoverage? Clin Orthop Relat Res 2015;473:1234-1246
  • Nötzli HP, et al. The contour of the femoral head-neck junction as a predictor for the risk of anterior impingement. J Bone Joint Surg Br 2002;84:556-560
  • Griffin DR, et al. The Warwick Agreement on femoroacetabular impingement syndrome. Br J Sports Med 2016;50:1169-1176

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.

Lateral center-edge angle28 °
Tönnis angle8 °
Alpha angle62 °
Neck-shaft angle130 °
Femoral version15 °
Minimum joint space width3.5 mm

→Alpha angle62°

  • Lateral center-edge angle：28 ° → 25–39°: normal
  • Tönnis angle：8 ° → 0–10°: normal
  • Alpha angle：62 ° → > 55°: cam morphology (> 60° more specific)
Verification & sources · governance
FAQ

Frequently asked questions

What are the limits and cautions when using Hip Dysplasia & FAI Measurements (LCEA / Tönnis / Alpha / Neck-Shaft)?
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 Hip Dysplasia & FAI Measurements (LCEA / Tönnis / Alpha / Neck-Shaft) 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 Hip Dysplasia & FAI Measurements (LCEA / Tönnis / Alpha / Neck-Shaft) calculated in practice? Can you show a worked example?
Inputs: Lateral center-edge angle 28 °, Tönnis angle 8 °, Alpha angle 62 °, Neck-shaft angle 130 °, Femoral version 15 °, Minimum joint space width 3.5 mm → Result: Alpha angle 62 °（Lateral center-edge angle: 28 ° → 25–39°: normal, Tönnis angle: 8 ° → 0–10°: normal, Alpha angle: 62 ° → > 55°: cam morphology (> 60° more specific)）
Related tools

Other tools