Anterior cruciate ligament (ACL) injuries are common knee injuries. Approximately 200,000 anterior cruciate ligament (ACL) injuries occur each year in the United States. Of these injuries, surgical reconstructions are involved in the rehabilitation process of approximately 100,000. It is important that healthcare providers have the ability to safely and accurately assess these injuries when they occur to allow people to begin appropriate treatment as soon as possible. Knowledge of the mechanism of injury, signs and symptoms, and diagnostic tests for anterior cruciate ligament (ACL) injuries are all important assessment tools for a healthcare provider in diagnosing anterior cruciate ligament (ACL) injuries. It is important to consider current research in these areas to ensure that the best examination process is used for an accurate diagnosis of ACL injuries. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay The ACL, along with the posterior collateral ligament, is one of the two intracapsular cruciate ligaments of the knee. The ACL is composed of collagen, mainly type I, and is organized into multiple fiber bundles. The ACL is innervated by the posterior tibial nerve and receives its blood supply from the middle and inferior genicular arteries. Jarbo et al. (2017) state that the ACL has two separate portions, “the anteromedial bundle and the posterolateral bundle, named for their respective insertion sites from the tibia to the femur.” One group of researchers argues that these bundles exhibit less of an anatomical separation, but more of a functional differentiation. Markatos et al. (2013) explain, “An anteromedial bundle tightens at 90 degrees of flexion and a posterolateral bundle tightens as full extension is approached.” This allows the knee to maintain stability at various joint angles that may occur during daily movements. The function of the ACL involves maintaining the stability of the knee joint. Jarbo et al. (2017) describe the role of the ACL as follows: “The ACL is responsible for preventing anterior translation of the tibia relative to the femur and also acts as a secondary brake on tibial rotation and varus/valgus rotation.” This means that the ACL has more of a responsibility in helping to maintain knee stability, the primary function being resistance to anterior movement of the tibia. The important role of the ACL in preventing this movement is described by Markatos et al. (2013) who argue that “the ACL… accounts for up to 86% of the total force resisting front-wheel drive.” Total knee stability, including resistance to rotational motion, is further aided by the surrounding musculature. However, the body is not always able to maintain this stability, especially during athletics. When the ACL is exposed to more load than it can handle, it causes injuries that range from small tears to a complete tear. Athletes of all levels are at increased risk for an anterior cruciate ligament (ACL) tear. The risk for those who practice basketball, handball, football and skiing is even higher than for other sports. Anterior cruciate ligament injuries can occur due to both contact and non-contact mechanisms of injury, however, non-contact mechanisms make up the majority of anterior cruciate ligament tears. Kiapour et al. (2015) state that over 70% of all anterior cruciate ligament (ACL) injuries occur with a non-contact mechanism. The most common forms of non-contact mechanisms forACL injuries are related to a change in velocity or “multidirectional force generation across the knee joint during loading.” According to Wetters et al., the individual's knee is typically in the range from “early flexion to hyperextension at the time of injury.” They go on to explain that when the knee is in this range, the tensile properties of the ACL are higher. One athletic movement where the knee is often in this range is during deceleration. Therefore, deceleration is described as a frequent mechanism for anterior cruciate ligament (ACL) injuries. This can be explained by the fact that during deceleration “the quadriceps forces needed to stop the athlete increase and therefore contractions can place significant stress on the ACL”. Other mechanics include landing from a jump or performing a sideways cutting motion. Wetters et al. (2015) add that twisting and rotating movements can also lead to non-contact anterior cruciate ligament (ACL) injuries. Overall, these injuries tend to be caused by a combination of motion and forces at the knee. One group of researchers describes that “sagittal and coronal loading, in combination with unbalanced muscle contraction forces of the quadriceps and hamstring muscle groups, can lead to significant stresses on the ACL.” When the stresses of these forces are too high within the knee, the ACL tears. Diagnosing ACL injuries starts with recognizing the mechanism of injury. Knowing the mechanism of injury can provide clues as to whether an ACL injury should be considered or less as an indication of suspicion when performing an evaluation. Additionally, it is important to recognize the most common signs and symptoms of anterior cruciate ligament (ACL) injuries to facilitate a correct diagnosis to the affected person if he or she heard any auditory signal, such as a click or pop. Complete ACL tears often create a sound loud enough to be heard by the individual or those around them. This can be a good indicator of a potential anterior cruciate ligament (ACL) tear. The patient will often describe feeling unstable or that the knee will give out. They may be worried about getting up or walking initially after the injury. Upon inspection, ACL tears commonly “produce rapid swelling at the joint line.” While it is important to recognize these signs and symptoms of ACL injuries, the most important diagnostic tool is the use of special tests for ACL injuries. There are a number of special tests that can be used to diagnose anterior cruciate ligament injuries. According to Jarbo et al. (2017), “The 3 most widely accepted clinical tests for diagnosing an anterior cruciate ligament (ACL) injury include the anterior drawer test, Lachman, and pivot-shift, all initially described in the 1970s.” A new test has recently been proposed, called the “Lever Sign”. It is important to study the literature when new tests are released to ensure that the clinical examination tools used in practice are the most appropriate for the condition. Furthermore, it is important to consider that in a clinical setting “the accuracy of these tests may be influenced by patient factors such as swelling, pain, protective muscle action and examiner experience”. Therefore, the selection of a special test for diagnosis must be evidence-based andon the patient's current presentation. The anterior drawer test is a simple test for anterior cruciate ligament (ACL) injury. This simplicity makes it one of the most commonly used ACL tests. To perform this test, the professional places the patient in a supine position with the foot resting on the evaluation table, the hip flexed at 45 degrees and the knee flexed at 90 degrees. The foot is stabilized while the professional applies anterior translation to the tibia. Two different scenarios can be a positive test result; if there is no final sensation or if there is greater tibial translation compared to the uninjured side, it is considered positive for an anterior cruciate ligament (ACL) injury. In order for this test to be completed correctly, the practitioner must ensure that the tibia is aligned with the medial condyle of the femur before starting the test. Rossi et al. (2011) explain that not doing so could cause a false positive if there is a damaged PCL, because it can cause a more posterior initial tibial position, making it appear as if there is more anterior translation compared to the other side. Another point to consider is that pain and inflammation may make it uncomfortable or impossible for the patient to achieve 90 degrees of knee flexion to perform this test correctly. The Lachman test is considered the most valid test for examining the anterior cruciate ligament (ACL) because it typically has high sensitivity and specificity. This test is also performed with the patient in the supine position, but requires only 20-30 degrees of knee flexion to perform. For this test, “the examiner stabilizes the patient's femur with one hand while translating the tibia anteriorly with the other hand. As with the anterior drawer test, it is important to consider the final sensation when this test is performed. Rossi et al. (2011) explain that a soft sensation in the extremity is indicative of a complete tear of the anterior cruciate ligament (ACL), while a firm sensation in the extremity would be a negative test. The pin displacement test is one that does not require the examiner to consider a final sensation. This test is performed with the patient in the supine position with 40 degrees of hip flexion and slight hip adduction. The examiner holds the patient's knee slightly flexed and applies light valgus and internal rotation forces. The knee is then passively flexed by the practitioner while maintaining these forces. Lichtenberg et al. (2018) describe a positive test as follows: “there is an anterior subluxation of the lateral tibial plateau that spontaneously reduces beyond 30 degrees of knee flexion.” The most recent ACL diagnostic test is the Lever Sign Test. This test is also performed with the patient in the supine position, but with the knee fully extended. The examiner then “places a closed fist under the proximal third of the calf [which] causes the knee to flex slightly.” This will act as the fulcrum of the leverage in this test. Next, the examiner exerts an anterior-to-posterior force on the patient's quadriceps, approximately one-third proximal to the knee. This test looks for “ACL discontinuity”. A negative test would be if the knee joint went into full extension and the heel of the affected leg lifted off the table. This would mean that an uninjured ACL is creating intact leverage at the knee, which allows the heel to lift off the table from the force applied to the quadriceps. Conversely, a positive test would have a missing part of the lever system; this means that a damaged ACL will not be able to help lift your heel off the table. Therefore, a positive Lever Sign test is one in which the knee does not move into flexion and the heel remains oncot. Various studies have been completed to compare the effectiveness of this new Lever Sign test compared to three other, more traditional, diagnostic tests of the anterior cruciate ligament (ACL). Measures of the effectiveness of special tests include sensitivity and specificity. Sensitivity is defined by Fritz & Wainner (2001) as “the ability of the test to recognize the condition when present. A highly sensitive test has relatively few false negative results.” In contrast, “specificity is the ability of the test to identify the absence of disease.” This means that “a highly specific test has relatively few false positive results.” Ideally, a test will have both high sensitivity and high specificity, however, Fritz & Wainner (2001) argue that few tests fall into this category. Ideally, a test will have both high sensitivity and high specificity, however, Fritz & Wainner (2001) argue that few tests fall into this category. In their study, Lelli et al. (2016) performed a prospective study over a period of 8 months. They evaluated a total of 400 patients in 4 different categories. These categories were based on the stage of post-injury healing – acute or chronic – and MRI findings – complete or partial anterior cruciate ligament (ACL) tear. In this study, the term acute was defined as “less than 20 days after injury.” Patients in this study were 29.8% female and 70.2% male with an average age of 26.4 years. All patients were tested by the same examiner who was blinded to the MRI findings. Each participant was assessed using “the Lachman test, the Anterior Drawer test, the Pivot Shift test and the Lever Sign test”. Each participant's uninjured leg was used as a control for this study, but only for the lever sign test. This test showed that the sensitivity and specificity of the lever sign test were both 1.0, meaning that the test was always correct compared to the MRI results. The mean sensitivity of the other three tests was 62% for the Lachman test, 72% for the anterior drawer test, and 47% for the Pivot Shift test. Because these tests were not compared to the uninjured side, specificity was not calculated. A study conducted by Jarbo et al. (2017) also examined the new Lever Sign test and its effectiveness as a diagnostic test. Their study looked at 102 patients with acute knee injuries. Acute lesions were defined as having been less than 4 weeks old. There were 44 females included in the study, 28 in the surgical group and 16 in the non-surgical group, and 58 males in the study, 26 in the surgical group and 32 in the non-surgical group. Those included in the study had an average age of 23 years. All patients were clinically evaluated for ACL integrity using all 4 diagnostic tests: Lachman test, anterior drawer test, Pict Shift test, and lever test. Patients in the surgical group were also tested with all 4 tests under anesthesia. The surgical group had ACL integrity, or lack thereof, confirmed by MRI and arthroscopic surgery, whereas the nonsurgical group's ACL injury status was confirmed by MRI only; however, the results were only compared with MRI findings to calculate sensitivity and specificity. Having the test results in clinical and surgical settings allowed the researchers to compare the accuracy of the tests in awake patients and those under anesthesia. During anesthesia, the Anterior Drawer, Lachman, and Pivot Shift tests were all more accurate, but the difference in Lever Sign test results was not.