Calculator: Do I Need ACL Reconstruction?

ACL Non-Operative Treatment Risk Estimator

Based on the BABY-Knee Algorithm (Grassi et al., J Exp Orthop 2025)

Important: This algorithm was developed and validated only in skeletally immature (growing) patients aged around 12–16 years, in a single-centre study of 75 patients. It is presented here for general educational purposes across a wider range of patients, but it has not been formally validated in skeletally mature adults. It does not replace clinical assessment and should not be used on its own to make a treatment decision. Please discuss your result with your orthopaedic surgeon.

Your details

Required so your result can be labelled and saved as a personal report.

Name *

Date of birth (Month & Year) *

1. Growth plate status up to 2 pts

This affects how much your knee's ligaments are expected to stretch or fail with instability.

I am skeletally mature (an adult, or my growth plates are closed) I am still growing (a child or adolescent with open growth plates)

Automatically set to skeletally mature based on your date of birth (18 years or older).

Please select your sex and, if your MRI report or surgeon has stated it, your skeletal (bone) age:

2. Meniscal tear pattern on MRI up to 3 pts

Taken from your radiologist's MRI report. Select the option that best matches — if more than one tear is mentioned, select the more severe.

No meniscal tear reported Ramp tear or longitudinal tear Bucket-handle tear or radial tear

3. Bone bruising pattern on MRI 1 pt

Look for mention of bone bruising / bone marrow oedema on the outer (lateral) side of the knee — this is very common with ACL injuries.

My report mentions lateral femoral and/or lateral tibial bone bruising

4. How the injury happened 1 pt

My injury happened without contact from another player/person, during my usual sport or activity (e.g. landing, pivoting, sudden change of direction)

5. Pivot-shift test result 1 pt

This is a hands-on knee exam done by a surgeon or physiotherapist — it cannot be assessed by yourself, and many patients won't yet know this result. If you're unsure, choose "Not assessed."

Enter your name and date of birth to continue

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out of 10 points

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If a pivot-shift test later comes back Grade 3 (gross):

Score breakdown

Interpretation

What this score has meant in the original study

These figures come from a single study of 75 growing patients (55 surgical, 20 initially non-surgical). They are a guide to typical outcomes in that specific group — not a personalised prediction, and not yet confirmed in adults or in larger studies.

For additional context: average scores by outcome in the original study

Treated surgically from the start	5.6
Non-op initially, later failed & needed surgery	4.7
Non-op initially, successful (no surgery needed)	2.1

This shows a general trend — higher scores were associated with surgical treatment and with non-operative treatment failing — but these are group averages, not a per-point risk calculation, and shouldn't be read as "each extra point adds X% risk."

Adapted from: Grassi A, Borque K, Dietvorst M, et al. Creation and validation of a treatment algorithm for skeletally immature patients with acute anterior cruciate ligament injury based on MRI and patient characteristics. J Exp Orthop. 2025;12:e70280.

Saves a copy of this full report as a PNG image

This tool is for education only and does not replace a clinical assessment. For a full review of your ACL injury, please get in touch with our clinic.