Clinical tests for ACL rupture, compared
A tear of the anterior cruciate ligament, which stops the shin sliding forwards and rotating on the thigh bone. Usually from a twisting or pivoting injury.
The 3 tests in the library for ACL rupture, side by side, each with the published accuracy figures that exist for it. Click a test for what each result means, any caution, and the source.
| Test | Sensitivity | Specificity | LR+ | LR− | Verdict |
|---|---|---|---|---|---|
| Anterior drawer test | 83% | 85% | 6.34 | 0.2 | Best used to rule in |
| Lachman test | 81% | 85% | 5.72 | 0.24 | Best used to rule in |
| Pivot shift test | 55% | 94% | 10.7 | 0.48 | Best used to rule in |
Reading the table
A high LR+ makes a positive result useful for ruling the condition in; a low LR− makes a negative result useful for ruling it out. A test can be good in one direction and weak in the other, and the figures come from different studies and patient groups, so compare them with care.
The Lachman and anterior drawer both measure forward translation of the tibia, so two positives are not two independent pieces of evidence.
Tests for the same problem are rarely independent, so a second positive adds much less than its own figure suggests. Do not multiply their figures together. Where a combination has been tested as a cluster or a decision rule, Rule It In, Rule It Out gives that published result.
To turn a figure into a probability for your patient, use the probability calculator.
Get the book for how to do and read each knee test with published figures, and which ones to trust for the ACL, meniscus and kneecap
This page gives the published figures. Rule It In, Rule It Out adds how to do each test, what counts as positive, how to read the result, and, where studied, whether combining tests helps.
Coming in late 2026 as a PDF and a paperback. Join the list to hear when it's out
One study, one test, once a month
Rule It In is a free evidence letter for musculoskeletal clinicians: one recent study explained, one examination test with its real numbers. From Trokos, publisher of Rule It In, Rule It Out.
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