Accuracy of 3 diagnostic tests for anterior cruciate ligament tears

In patients presenting with possible rupture of the anterior cruciate ligament (ACL), which diagnostic test can provide an accurate diagnosis during the physical examination?

Two reviewers searched MEDLINE (1966 to February 14, 2003) and EMBASE (1980 to February 14, 2003). Articles written in English, French, German, or Dutch were included. The key search terms were knee injuries, knee joint, and knee. These terms were combined with the headings joint instability and anterior cruciate ligament, as well as the text words laxity, instability, cruciate, and effusion. The results of these searches were combined with the subject headings sensitivity and specificity, physical examination, and not (animal not [human and animal]). Additional text words searched were sensitivit*, specificit*, false positive, false negative, accuracy, screening, physical examination, and clinical examination. The reference lists of included articles were examined.

Inclusion criteria consisted of (1) investigation of at least one physical diagnostic test for assessment of ACL ruptures in the knee and (2) the use of a reference standard of arthrotomy, arthroscopy, or magnetic resonance imaging.

Two independent reviewers extracted data from each included study. The methodologic quality of each test was assessed and recorded on a checklist for the screening of diagnostic tests (www.cochrane.de/cochrane/sadtdoc1.htm). The 3 diagnostic tests validated in this review were the pivot shift test, the anterior drawer test, and the Lachman test. A summary receiver operating characteristic curve was performed for each test, and the sensitivity, specificity, and predictive values were reported.

The search strategy produced 1090 potentially eligible studies, of which 17 studies were selected. One study was included via reference list examination and 2 reports referred to the same study. Thus, 17 studies met the inclusion criteria and were used for this review. For the included studies, the sample size ranged from 32 to 300 patients. As for the age of the subjects, the authors of 4 studies failed to report it. Thus, the average age of patients across 13 of the 17 studies was 28.6 years. Authors of all studies failed to measure the clinical test and reference standard separately and with blinding. In addition, all but two studies had a significant degree of verification bias. Arthrotomy was the lone reference standard in 4 studies whereas arthrotomy/arthroscopy was the reference standard in 5 studies. Arthroscopy alone was the reference standard in 6 studies where only 2 studies used MRI as the reference standard. Authors of 8 studies examined the anterior drawer test and reported sensitivity values ranging from 0.18-0.92 and specificity values ranging from 0.78-0.98. When pooled together using the bivariate random effects model (BREM), the sensitivity value of the 8 studies was 0.2 and the specificity value was 0.88. Authors of 9 studies examined the Lachman test and reported sensitivity values ranging from 0.63-0.93 and specificity values ranging from 0.55-0.99. Pooled together using the BREM, the sensitivity value was 0.86 and the specificity value was 0.91. Lastly, authors of 6 studies examined the pivot shift test and reported sensitivity values ranging from 0.18-0.48 and specificity values ranging from 0.97-0.99. Data for the pivot shift test could not be pooled using the BREM because of the low number of available studies. Predictive values were reported graphically, with the pivot shift test having the highest positive predictive value and the Lachman test having the best negative predictive value.

Based on predictive value statistics, it can be concluded that during the physical examination, a positive result for the pivot shift test is the best for ruling in an ACL rupture, whereas a negative result to the Lachman test is the best for ruling out an ACL rupture. It can also be concluded that, solely using sensitivity and specificity values, the Lachman test is a better overall test at both ruling in and ruling out ACL ruptures. The anterior drawer test appears to be inconclusive for drawing strong conclusions either way.