Translate this page into:
The “Lelli Test” a modern and new clinical test for the diagnosis of anterior cruciate ligament lesions
*Corresponding author: Vishwajit Vijay Patil, Department of Arthroplasty and Sports Medicine, Villa Regina Multi-Speciality Hospital, Bologna, Italy. vishwajit.patil60@gmail.com
-
Received: ,
Accepted: ,
How to cite this article: Patil VV, Lelli A, Sangiorgi V. The “Lelli Test” a modern and new clinical test for the diagnosis of anterior cruciate ligament lesions. J Arthrosc Surg Sports Med. 2025;6:137-41. doi: 10.25259/JASSM_21_2025
Abstract
Objectives:
Over the past decade, Dr. Alessandro Lelli’s new functional clinical test, the Lelli Test or the Lever Sign Test, has supplemented traditional clinical tests and magnetic resonance imaging (MRI) investigations to diagnose partial and complete anterior cruciate ligament (ACL) lesions. The present study describes the test’s sensitivity in 3000 patients with complete or partial ACL injuries, even with negative MRI reports.
Materials and Methods:
A prospective study with its analysis of various test sensitivity to diagnose an ACL lesion in comparison to Lelli’s Test was done in the authors’ institute.
Results:
All tests were nearly 100% sensitive for patients with chronic complete ACL tears. However, with acute or partial ACL lesions, even with a negative MRI report, the sensitivity was much lower for the Lachman, Anterior Drawer, and Pivot Shift tests, but not the Lelli test. This level III evidence prospective clinical study of 3000 patients showed the mean sensitivity as 0.61 for the Lachman test, 0.67 for the Anterior Drawer test, 0.47 for the Pivot Shift test, and 0.97 for the Lelli test.
Conclusion:
The Lelli or Lever sign test is more sensitive to diagnosing acute and partial ACL tears correctly than standard manual tests, even in patients with negative MRI reports. This test’s key feature is distinguishing a healthy, intact, functionally valid ACL from a healthy, intact, but functionally invalid ACL.
Keywords
Anterior cruciate ligament
Lelli test
Lever sign test
INTRODUCTION
The anterior cruciate ligament (ACL) is the most commonly injured knee structure.[1,2] The three most commonly used physical tests to diagnose ACL rupture are the Lachman, anterior drawer, and Pivot Shift tests.[3,4] These tests are recommended diagnostic tools,[5] but they have a few drawbacks, such as the influence of patient guarding due to the pain associated with rapidly translating or twisting a potentially injured ACL[1,4,6] and difficulty diagnosing partial tears,[7] which are well documented. Despite its limitations, manual testing offers numerous advantages, including being non-invasive and inexpensive. Magnetic resonance imaging (MRI), which supports the diagnosis of ACL rupture, is also a valid and non-invasive diagnostic method. In some cases, the ACL may appear intact on a regular MRI, but the ACL tear can be visualized when a dynamic MRI is done [Figure 1].
- Patient magnetic resonance imaging (MRI) with anterior cruciate ligament (ACL) lesion but different orthopedic and clinical statistician results. The yellow box represents MRI taken in supine position. The yellow circle represents an intact ACL. The red box represents the same patients knee MRI taken in standing/dynamic position. The red circle represents a broken ACL ligament.
A new physical test called the “LELLI TEST” or “LEVER SIGN TEST” was conceived in 2005 and certified in 2016.[8] The Lelli test has proven superior to other manual tests, equally definitive for partial and complete ACL tears, and diagnostic even for acute injuries with a negative MRI report. This novel manual test takes advantage of the fact that the ACL provides most of the restraining force against anterior tibial fixation, especially around 30°,[9] and it is independent of the time from injury. The ACL is the only structure originating from the tibial plateau and attaching to the femur. In contrast, the remaining ligaments originate at the level of the tibial tuberosity or insert approximately 10–15 mm below the tibial plateau.
MATERIALS AND METHODS
Clinical tests
Anamnesis plays an essential role in the diagnosis. When examining a knee that has undergone trauma, the first step is to assess the injury accurately with specific semiological tests (laxity tests and stability tests) to distinguish a physiological laxity, for which no treatment is required, from a pathological laxity due to trauma, with or without instability. Accurate trauma analysis can direct the examiner toward a diagnosis, and a careful clinical examination helps confirm the diagnosis.
However, it must be borne in mind that the evaluation of the patient becomes more complex in the case of acute or banal injuries, where the patient is apprehensive and has a swollen or painful knee.
Clinical tests evaluating pathological laxity are classified into active, passive, and dynamic tests. It is essential to understand which tests should be performed first. When faced with a patient who has suffered a trauma, we advise first performing the active and dynamic tests, which are designed to reproduce the instability, paying attention that they can result negative in case of partial injuries and require complete cooperation of the patient. In acute injuries, it is challenging to execute the tests themselves. Most orthopedic surgeons are very skilled in diagnosing a chronic ACL lesion. The classic passive tests that help us in diagnosing a complete ACL lesion are:
Anterior Drawer test
Lachman test
Pivot shift test.
The Anterior Drawer test is the most easily reproducible test. This test has a good sensitivity of 92% and a specificity of 91% in chronic conditions, but not as much in acute injury.[1] According to Sokal et al., the anterior drawer test’s overall sensitivity and specificity are 83% and 85%, respectively.[10] The test can be falsely negative when done with the tibia in internal or external rotation. This can be attributed to the internal rotation of the tibia, which “locks” the joint by tightening the posterior cruciate ligament (PCL) and posterolateral ligaments, like the iliotibial tract. Sometimes, with the knee at 90° flexion and the tibia at neutral rotation, if the medial and lateral structures are contracted, the drawer test may be negative even with a ruptured ACL.
A fundamental difficulty in performing this test is defining the starting point (neutral position) from which an anteriorly directed force will elicit a true anterior drawer sign. For example, suppose there is a lesion of the PCL with posterior yielding of the tibia, and the examiner applies an anterior stress. In that case, it may seem that a pure anterior drawer sign is elicited when, in reality, the tibia has been pulled forward from a posterior position to its neutral position. Nevertheless, performing an anterior drawer test is extremely difficult in acute injuries or in the presence of meniscal injuries. It is also challenging to perform on obese patients or if the doctor has small hands.
The Lachman test is considered the most sensitive test in diagnosing an ACL tear. In a meta-analysis study, the Lachman test was the most valid test to determine ACL tears, showing a pooled sensitivity of 85% and a pooled specificity of 94%.[1] One of the main advantages of the Lachman test is that it is performed in the functional position of the knee at 30° flexion. This is the position in which the ACL is an essential stabilizer for activities in which the individual has to change direction and stop. In these types of movement, the insufficiency of the ACL has the most significant impact, allowing the subluxation of the lateral tibial plateau. The advantages of the Lachman test are that it is highly sensitive for ACL rupture, not hampered by hemarthrosis, and less painful because the muscles are relaxed. The test is also not hampered by sprained or partially ruptured medial collateral ligament (MCL).
However, the test also has its own set of difficulties, like the inability to place the knee in 30° of flexion due to muscle guarding, which often accompanies an ACL injury. This test is often negative in acute, partial ACL, or concomitant meniscal injuries. It is also challenging to perform if the patient is obese or the doctor has small hands.
The Pivot Shift test is the most specific test in diagnosing an ACL tear. The pivot shift test’s overall sensitivity and specificity are 55% and 94%.[10] The pivot shift phenomenon is caused by the anterior subluxation of the lateral tibial plateau when the knee approaches extension. False-negative test results may arise due to protective muscle action against the subluxation phenomenon. In addition, ACL reattachment to the proximal portion of the PCL or concomitant MCL injuries can limit the amount of valgus force that can be applied to the knee. Furthermore, in the case of acute injury, the test can produce false negatives as muscle contraction and pain tend to protect the knee.
The Lelli test
The birth of the Lelli or Lever sign test was intuitive and spontaneous. During a routine walk that Dr. Lelli took with his kid, he noticed that the kid kept pulling up his pants even though the belt was on and intact. At that point, he correlated the belt of the trousers to the knee ACL. A thought crossed his mind that while the structures of the knee, such as the meniscus, cartilage, or bones, can either be intact or broken. The ligaments, being elastic structures, must have two characteristics to function well, that is, they must be intact and in tension [Figure 2].
- Dr. Lelli’s son who kept pulling up his pants even though he had his belt fastened. When repeatedly told by Dr. Lelli to pull up his pants, he replied that his belt had been fastened!.
Three key reasons were added to this intuition:
The first is anatomical: The ACL is the only structure originating from the tibial plateau. The patellar tendon originates at the level of the tibial tuberosity and the PCL, and all the medial and lateral capsular ligament structures have their insertion approximately 10–15 mm below the tibial plateau.
The second is physical: The leg acts as a lever on a fulcrum, represented by the examiner’s fist. When a force is exerted at one end of the lever, it is transmitted to the other end.
The third is intuitive: The ACL can be compared to the belt of the trousers, which, despite being intact, would allow the trousers to fall if it was not well-tightened.
This test is performed with the patient supine, knees fully extended, on a hard surface, such as an examination table. The examiner stands at the patient’s side and places a closed fist under the proximal third of the calf so that the knee flexes slightly. With the other hand, moderate downward force is applied to the distal third of the quadriceps. With this configuration, the patient’s leg acts as a lever on a fulcrum, represented by the doctor’s fist. The two forces acting are the force of the doctor’s hand on the quadriceps and the force of gravity on the foot and lower leg.
In an intact ACL, the full leverage created by the ACL allows the downward force on the quadriceps to counter the downward force of gravity. The knee joint extends fully, and the heel lifts off the table [Figure 3a]. With a partial or complete tear of the ACL, this ability to compensate for the force of gravity on the lower leg is compromised. Thus, the tibial plateau slides anterior to the femoral condyles. In this case, gravity pulls the heel down, preventing the foot from rising [Figure 3b].
- (a) Force diagram of negative Lelli test. With the fist acting as a fulcrum (black arrowhead) under the left calf and a second hand pushing down on the left quadriceps (large black arrow), the ACL (red circle) can counteract the downward force on the foot due to gravity (small black arrow). The upward red arrow in figure 3a represents the leg being lift up from the table due to an intact ACL ligament showing its continuity. (b) Force diagram of positive Lever Sign or Lelli test. With the fist acting as a fulcrum (black arrowhead) under the right calf and a second hand pushing down on the right quadriceps (large black arrow), the ruptured ACL (red circle) is not able to counteract the downward force (small black arrow) on the foot, and the foot remains on the examination table.
For 1 year, the authors collected 3000 patients at a dedicated surgery center with a definitive MRI diagnosis of ACL rupture (partial or complete) or with a negative MRI report for ACL rupture [Figure 4].
- Lelli test during dynamic magnetic resonance imaging investigation.
The patients were divided into five equally sized groups based on their MRI findings (complete or partial ACL lesion) and clinical phase (acute or chronic): Group A (acute phase with MRI finding of complete ACL rupture), Group B (chronic phase with MRI finding of complete ACL rupture), Group C (acute phase with MRI finding of partial ACL rupture), Group D (chronic phase with MRI finding of partial ACL rupture), and Group E (MRI report negative but ACL loose). The acute phase was defined as <20 days from injury, whereas the chronic phase was defined as more than 20 days from injury (range 20 days-4 years). Exclusion criteria included comorbidities such as multi-ligamentous injuries and meniscal injuries, as well as prior reconstructions of the affected ACL. The demographic information on the groups was summarized, with no significant differences among the various patient groups. The study satisfied the institution’s requirements regarding the use of human subjects in scientific research. To ensure homogeneous data, a single clinician performed all physical examinations, blinded to the MRI findings. As part of the clinical evaluation, every patient underwent the same series of physical tests, including the Lachman, Anterior Drawer, Pivot Shift, and Lelli tests.
RESULTS
Group A, B, C, D, and E data are summarized [Tables 1 and 2]. For each group, the sample size remained constant (n = 600). Group B patients (complete tear and chronic injury) were most likely to be successfully diagnosed using the classic passive physical examination tests, while Group C patients (partial tear and acute injury) and E patients (negative MRI report but ACL lax) were least likely to be successfully diagnosed.
| Group | Number of patients | Mean age (years) | Sex (female) (%) |
|---|---|---|---|
| A | 600 | 22.2 | 24 |
| B | 600 | 23.6 | 31 |
| C | 600 | 20.9 | 18 |
| D | 600 | 23.8 | 32 |
| E | 600 | 25.3 | 21 |
| Group | Lachman test (%) | Anterior drawer test (%) | Pivot shift test (%) | Lelli test (%) |
|---|---|---|---|---|
| A | 64 | 75 | 26 | 97 |
| B | 100 | 100 | 76 | 100 |
| C | 42 | 28 | 12 | 92 |
| D | 37 | 79 | 58 | 98 |
| E | 60 | 54 | 65 | 98 |
In the two groups of patients with an MRI diagnosis of complete ACL rupture (Groups A and B), the mean sensitivity of the three clinical tests was superior to the two groups of patients with partial ACL lesions (Groups C and D). However, in group E, when we have a negative MRI report but clinically the ACL is lax, the classic passive tests for a probable ACL lesion are positive with an alarming percentage. Interestingly, mean sensitivity data for acute injuries were lower than the mean data for chronic injuries. This signified that the group E patients needed some sort of intervention. When data from all 3000 patients were pooled, the mean sensitivity was: 0.61 for the Lachman test, 0.67 for the Anterior Drawer test, 0.47 for the Pivot Shift test, and 0.97 for the Lelli test.
DISCUSSION
The ACL is the most commonly injured ligament[1,2] of all the knee ligaments. Various clinical tests and radiographic investigations aid in diagnosis. The diagnostic accuracy of these clinical tests varies in acute and chronic injuries. Most clinical tests are highly sensitive in diagnosing a chronic ACL tear. However, in the case of an acute ACL tear, the pivot shift test was found to be the most sensitive passive test, followed by the Lachman test and the Anterior Drawer test.[6] The accuracy further varies between partial and complete tears. In a systematic review, the sensitivity for the Lachman test was 96% for complete ACL ruptures and 68% for partial ACL ruptures. At the same time, the pivot shift test had an 86% sensitivity for complete ruptures and 67% for partial ruptures. [11] The MRI investigation proved to have a specificity and sensitivity of about 94–98% in detecting an ACL injury.[12-14]
The diagnostic ease of an ACL tear markedly improved with the introduction of the Lelli test or the Lever sign test in 2016.[8] A level II prospective comparative study showed that the Lelli test is highly sensitive and specific in its accuracy for detecting ACL tears.[15] A study by Gürpinar et al. showed that the Lelli test has a sensitivity and accuracy of 91.9% and 92.3% in the acute phase and 91.9% and 92.3% in the chronic phase of the injury.[16]
The study concluded with the mean sensitivity for each test as 0.61 for the Lachman test, 0.67 for the Anterior Drawer test, 0.47 for the Pivot Shift test, and 0.97 for the Lelli test. In the present study, mean sensitivity values were lower for the Pivot Shift test and higher for the Lachman test, possibly due to the large number of patients with acute injuries in this study. Furthermore, the differences in the sensitivity values may be attributed to the large number of patients with partial tears in the present study. The most significant finding of this study was the perfect correlation between the Lelli test and the patient’s MRI findings, regardless of whether the ACL rupture was partial or complete and irrespective of the time interval since injury.
Acute ACL injuries are generally regarded as being more challenging to diagnose. This statement was corroborated by our study findings of the increased sensitivity for diagnosing a chronic ACL lesion compared to an acute one. These findings confirmed the need for a robust test with higher sensitivity for detecting an ACL lesion irrespective of the elapsed time. The advantage of the Lelli test is its ease with which it can be performed on an obese individual and by a clinician with small hands. A systematic review and meta-analysis of various tests used for diagnosing ACL lesions concluded the Lelli and pivot shift test to be the best for ruling in or ruling out an ACL tear.[10] The Lelli test is more sensitive to diagnosing acute and partial ACL tears than classic passive physical tests. Therefore, the Lelli test has become one of the primary tests to diagnose an ACL lesion.
This level III evidence is clinically relevant because the Lelli test helps more accurately diagnose ACL lesions, even in patients with negative MRI reports.
CONCLUSION
The Lelli or the Lever Sign test is now a commonly used test for the diagnosis of partial and complete ruptures of the ACL, even in patients with a negative MRI report. In this prospective clinical study of 3000 patients, the Lelli test was found to have higher sensitivity than the other commonly performed physical tests. The other advantage of the test was its ease in performing the test on an obese individual, even with a clinician having small hands. All physical tests have no significance if they are not compared with those performed on the healthy contralateral knee to distinguish between a physiological and a pathological condition.
Author contributions:
VVP: Design, definition of intellectual content, literature search, clinical studies, data acquisition, data analysis, statistical analysis, manuscript preparation, manuscript editing and review; AL: Concepts, design, definition of intellectual content, experimental studies, data acquisition, manuscript editing and review; VS: Clinical studies, data acquisition, statistical analysis, and data analysis.
Ethical approval:
Ethical committee approval was not required as the patients were not subjected to any medical or surgical intervention and this study focused only on the clinical tests done on the patients.
Declaration of patient consent:
Patient’s consent is not required as patients identity is not disclosed or compromised.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
References
- Clinical diagnosis of an anterior cruciate ligament rupture: A meta-analysis. J Orthop Sports Phys Ther. 2006;36:267-88.
- [CrossRef] [Google Scholar]
- Anterior cruciate ligament reconstruction recovery and rehabilitation: A systematic review. J Bone Joint Surg Am. 2022;104:739-54.
- [CrossRef] [Google Scholar]
- Physical examination of the knee: A review of the original test description and scientific validity of common orthopedic tests. Arch Phys Med Rehabil. 2003;84:592-603.
- [CrossRef] [Google Scholar]
- Methods to diagnose acute anterior cruciate ligament rupture: A meta-analysis of physical examinations with and without anaesthesia. Knee Surg Sports Traumatol Arthrosc. 2013;21:1895-903.
- [CrossRef] [Google Scholar]
- Guideline on anterior cruciate ligament injury. Acta Orthop. 2012;83:379-86.
- [CrossRef] [Google Scholar]
- The diagnostic accuracy of ruptures of the anterior cruciate ligament comparing the Lachman test, the anterior drawer sign, and the, pivot shift test in acute and chronic knee injuries. Am J Sports Med. 1986;14:88-91.
- [CrossRef] [Google Scholar]
- A comprehensive review of partial anterior cruciate ligament tears. J Bone Joint Surg Am. 2009;91:198-208.
- [CrossRef] [Google Scholar]
- The “lever sign”: A new clinical test for the diagnosis of anterior cruciate ligament rupture. Knee Surg Sports Traumatol Arthrosc. 2016;24:2794-7.
- [CrossRef] [Google Scholar]
- Three-dimensional dynamic motion analysis of the anterior cruciate ligament deficient knee joint. Am J Sports Med. 1989;17:463-71.
- [CrossRef] [Google Scholar]
- 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. Knee Surg Sports Traumatol Arthrosc. 2022;30:3287-303.
- [CrossRef] [Google Scholar]
- Diagnostic accuracy of physical examination for anterior knee instability: A systematic review. Knee Surg Sports Traumatol Arthrosc. 2015;23:2805-13.
- [CrossRef] [Google Scholar]
- Sensitivity and specificity of bell-hammer tear as an indirect sign of partial anterior cruciate ligament rupture on magnetic resonance imaging. Knee Surg Sports Traumatol Arthrosc. 2014;22:1112-8.
- [CrossRef] [Google Scholar]
- 2D and 3D 3-tesla magnetic resonance imaging of the double bundle structure in anterior cruciate ligament anatomy. Knee Surg Sports Traumatol Arthrosc. 2006;14:1151-8.
- [CrossRef] [Google Scholar]
- Magnetic resonance imaging versus arthroscopy in the diagnosis of knee pathology, concentrating on meniscal lesions and ACL tears: A systematic review. Br Med Bull. 2007;84:5-23.
- [CrossRef] [Google Scholar]
- Critical analysis of the lever test for diagnosis of anterior cruciate ligament insufficiency. Arthroscopy. 2017;33:1560-6.
- [CrossRef] [Google Scholar]
- Diagnostic accuracy of lever sign test in acute, chronic, and postreconstructive ACL injuries. Biomed Res Int. 2019;2019:3639693.
- [CrossRef] [Google Scholar]
