The Forced Active Buckling Sign: A New Clinical Test for the Diagnosis of ACL Insufficiency

Abstract

Although insufficiency of the anterior cruciate ligament (ACL) is a frequent result of an injury, validated tests are associated with unsatisfying validity. Moreover, some of these tests are not easy to perform and patient's muscular resistance often limits their reliability. Therefore, with this study, we want to design an accurate test to diagnose an ACL insufficiency, which is independent of the assessor's skills and overcome any muscular resistance. Fifty patients with an isolated ACL rupture (group A; age 26.4 years ± 14.9 standard deviation [SD]; female, n = 15) and additional 50 patients with an intact ACL but meniscal lesions (group B; age 45.4 years ± 12.9 SD; female, n = 23) were consecutively included in this study. The integrity of the ACL and the menisci were evaluated by magnetic resonance imaging and verified arthroscopically. Two orthopaedic surgeons performed a pivot shift test, a Lachman's test, and our new “forced active buckling” (FAB)-sign test in all patients. The surgeons were blinded for the pathology of the knee and we randomized the tests for each patient and examiner. The sensitivity, specificity, positive predictive value, negative predictive value, and positive and negative likelihood ratios with confidence intervals were calculated and compared. With a prevalence of 0.5, the FAB-sign test revealed the best overall sensitivity of 0.78 compared with the Lachman's and pivot shift tests of 0.74 and 0.46, respectively. Also, the overall specificity of the FAB-sign test of 0.95 was higher than the Lachman's test of 0.83, however, comparable to the pivot shift test of 0.96. The FAB-sign test demonstrated the best positive and negative predictive values of 0.94 and 0.81. There was no significant difference between the two examiners concerning the accuracy of results in each test (p = 0.83). This study shows that the introduced FAB-sign test can detect an ACL insufficiency more sensitive and more specific compared to the pivot shift and Lachman's tests in the subacute phase. This is a randomized controlled diagnostic study, level 1b.

The diagnostic accuracy of clinical tests for anterior cruciate ligament tears are comparable but the Lachman test has been previously overestimated: a systematic review and meta-analysis

“…Comprehensive description of each study and patient cohorts is provided in Tables 1 and 2 . Only two studies [ 6 , 8 ] were not considered at risk of bias (Table 3 ). One study was an RCT [ 6 ], seven studies had a prospective design [ 8 , 42 , 43 , 49 , 54 , 72 , 75 ] and 14 assessed patients retrospectively [ 9 , 12 , 18 , 20 , 22 , 26 , 33 , 38 , 39 , 41 , 44 , 45 , 57 , 62 ].…”

“…The number of patients in cohorts extracted from studies ranged from six [22] to 217 [22]. The average age of patients ranged from 21 [8] to 45 [6,39] with seven studies including patients below 16 years of age [8,9,20,33,45,49,62]. Time from injury was not defined in three studies [38,45,72] while acute, subacute and/or chronic injuries were included in the same cohort in six studies [9,33,41,43,57,75]; three studies described patients as acute yet did not specify time from injury [8,49] or provided only the average time [62].Each study has been screened for risk of bias based on 4 criteria of patient selection, index test, reference standard and flow and timing.…”

American Academy of Orthopaedic Surgeons Clinical Practice Guideline Case Study: Management of Anterior Cruciate Ligament Injuries

“…Ultimately, obtaining a relevant history and examination is critical when assessing for an ACL injury. 5,7-16…”

“…Ultimately, obtaining a relevant history and examination is critical when assessing for an ACL injury. 5,[7][8][9][10][11][12][13][14][15][16] In all three cases, there was also shared decision making regarding treatment options. Each patient was young, was active, and wished to return to athletic activities.…”

Value of clinical tests in diagnosing anterior cruciate ligament injuries: A systematic review and meta-analysis

“…In conclusion, 18 articles were included in the quantitative synthesis (meta-analysis). [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Figure 1, Supplemental Method 1, http://links.lww.com/MD/G869 presents detailed information on the flowchart regarding the search and selection of the literature.…”