The anterior cruciate ligament (ACL) is one. feature: Lisa Daitch, MPAS, PA-C, and Laura Stembridge

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1 feature: Lisa Daitch, MPAS, PA-C, and Laura Stembridge Getting back in the game after ACL rupture A safe return to competition is the goal of any injured athlete. Knee injuries deserve special attention, particulary those involving ligament damage. illustrations: fairman studios llc. The anterior cruciate ligament (white) provides rotational stability to the knee. The anterior cruciate ligament (ACL) is one of the most commonly injured structures of the knee. 1 An estimated 100,000 ACL ruptures are recorded each year in the United States, 60% of which require some type of surgical intervention. 1 Total costs associated with ACL diagnosis and management exceeds $1 billion in North America alone. 2 ACL rupture is an injury that affects more than professional athletes. It is frequent among active people in the general population as well. Physical activity is a normal part of everyday life for most individuals. Whether someone is a high-school football player, an avid runner, or a father playing catch with his son, physical activities fulfill competitive and social desires of people from all walks of life. Sports at any level are accompanied by numerous risk factors that can result in injury. Many injuries are minor and only require short-term rehabilitation, but others especially ACL ruptures can result in unfortunate seasonor career-ending devastation. This leads to a difficult dilemma for the athlete. Such positive effects of athletic activity as social interaction and health benefits can be destroyed if an injury of considerable magnitude occurs and an athlete cannot continue to participate. 2 A swift, successful return to activity is the initial priority. 3 Therefore, early surgical stabilization of the ACL is recommended for athletes wishing to return to a pre-injury level of ability. Today, the gold standard treatment for correcting an ACL rupture is surgical reconstruction 22 the clinical advisor september

2 Providers should encourage athletes to make soft landings with large amounts of knee-joint flexion to lower risks and prevent ACL injuries. using autograft or allograft tendons to effectively reproduce knee stability. 4 In short, an orthopedic surgeon removes the injured athlete s hamstring tendons or uses donated tendons to reconstruct a new ACL. After reconstruction and rehabilitation, the athlete should regain knee stability and be able to compete at a pre-injury level. Etiology The ACL is an important structure for forward stabilization of the knee. An ACL rupture causes impaired function and destroys the knee s normal mechanics. 5 Approximately 70% of ACL injuries arise in noncontact situations. 6 Noncontact ACL injuries are six to eight times more frequent in women than in men. 7 In the United States, the incidence is rising as a result of increasing ACL injuries among women aged years. 6 Anatomic, environmental, hormonal, and biomechanical factors increase an athlete s risk for noncontact injuries. 6 Anatomic risks factors primarily contribute to noncontact injuries in women. Because women have smaller intercondylar notches in the knee joint, there is an increased likelihood of ACL impingement or rupture. Typically, men have wider U-shaped intercondylar notches, reducing the likelihood of injury resulting from an anatomic or structural issue. 6 Women also tend to have larger pelvises, which lead to larger Q angles. To form the Q angle, draw a line from the anterior superior iliac spine (ASIS) of the pelvis to the center of the patella; then draw another line from the center of the patella to the tibial tuberosity. Larger Q angles are believed to result in greater amounts of stress and strain on the knees and a higher susceptibility of knee injury. 6 Faulty equipment and inadequate shoe-to-surface interactions equally increase the risk of injury in both male and female athletes. Special shoes and braces are used to provide better joint alignment and knee support to eliminate environmental factors of this nature. 7 Female sex hormones have recently been studied as contributors to ACL injuries. Estrogen and progesterone are thought to affect the composition and mechanics of the ACL, thus heightening a woman s chance of injury. Lastly, biomechanical factors are unique to each athlete. Degrees of muscle strength, control, and athletic ability affect each individual differently. 7 Usually, ACL tears occur when large loads or forces cannot be dissipated safely through the knee. Normally, the bones and soft tissues around the knee will safely disperse the applied forces through the knee and gradually decrease the forceful momentum. If loads or forces are too strong, the body s neuromuscular system becomes challenged, ultimately resulting in injury. 8 For example, if an athlete lands with his or her lower body in a stiff position, higher ground reaction forces are transferred through the knee, placing unbearable strain on the joint and increasing chance of injury. Providers should encourage athletes to make soft landings with large amounts of knee-joint flexion to lower risks and prevent injuries. 9 Common athletic situations known to produce noncontact ACL injuries include events involving quick changes in direction, decelerating with cutting maneuvers, and pivoting movements or jump landings with full- or nearly full-knee extension. 6 Contact injuries are responsible for approximately 30% of ACL injuries and are caused by collisions with other players or objects on the field. 6 Clinical presentation Patients most often describe a popping or tearing sensation immediately followed by severe pain. Common complaints include, My knee buckled under, or My knee suddenly gave out. 10 Either of these scenarios should raise the question of possible ACL derangement. About 70% to 80% of patients with ACL ruptures complain of knee instability during daily activities or with specific high-level activities. 11 Symptoms FIGURE 1. The Lachman test assesses stability of the ACL. 24 the clinical advisor september

3 Earlier recognition of an ACL rupture leads to greater patient satisfaction and provides more optimal surgical treatment and rehabilitation. occur while walking, but patients usually report an onset of symptoms after pivoting movements or abrupt changes in direction. Immediate joint dysfunction with an inability to ambulate is the most common symptom associated with ACL rupture. 12 Patients describe immediate swelling of the knee after the initial mechanism of injury. Swelling is observed with ligament injury because of hemorrhaging that occurs when a ligament is torn or ruptured. Acute hemarthrosis, an extravasation of blood into a joint or synovial cavity, is a textbook sign of acute ACL injury. Pain, edema, and stiffness of the injured knee joint are consistent with hemarthosis. The sensitivity level of the patient and/or the experience level of the examiner may hinder an adequate physical examination. 12 Earlier recognition of an ACL rupture leads to greater patient satisfaction 11 and provides more optimal surgical treatment and rehabilitation. Primary-care workup A complete history and physical examination will diagnose approximately 90% of all ligament injuries. 13 Before examining the patient, document all past knee injuries to improve accuracy of the exam. Patients with previous ACL ruptures are more likely to incur subsequent tears. 14 Because joint position can determine which anatomical structures are most likely to be injured, discerning the mechanism FIGURE 2. The anterior drawer test is used to determine the degree of tibial displacement. of injury is extremely important during the interview. A detailed summary of the accident to include the position of the knee, direction of external forces, and description of the joint after trauma is essential. 13 Initial workup for a ruptured ACL requires a thorough physical exam. Focusing on the healthy knee aids in maneuvering the patient into a comfortable position and establishes patient-provider trust. The primary goal of the exam is to create a relaxing environment that allows easier movement of the patient. Properly examining the healthy knee first provides a necessary control for comparison during evaluation of the injured knee. 15 The physical exam consists of inspection, palpation, and assessment of knee-joint function. Inspecting the knees for asymmetry will determine the presence of effusion or hemarthrosis. Three functionality tests should be performed to determine the stability of the joint and ACL. These tests evaluate joint integrity and any degree of separation by applying stress in certain directions and assessing the endpoints. Intact ligaments produce an abrupt, firm end-feel, whereas sprained or torn ligaments have soft, indistinct endpoints. 15 The best functionality test for assessing the stability of the ACL is the Lachman test (Figure 1). With the patient lying in the supine position, flex the knee 20 to 30 while the heel rests on the end of the exam table. Grasp the femur with the non-dominant hand to prevent movement of the upper leg. Then, grasp the lower leg at the proximal tibia and apply a forward tug. This movement should produce a firm endpoint. If the endpoint is not firm or there is increased anterior translation of the tibia, the Lachman test is positive. 15 The second functionality test to be performed is the anterior drawer test (Figure 2). Lay the patient in the supine position, and place the knee in 90 of flexion without rotation. Place both hands on the proximal tibia, and pull the upper part of the calf forward. An anterior drawer test is positive when the tibia moves anteriorly without an abrupt, hard endpoint. 15 Finally, the pivot shift test (Figure 3) assesses anterior subluxation of the lateral tibial plateau when the lower leg is stabilized in near full extension. While increasing flexion, a palpable springlike reduction should be observed. A positive pivot shift test usually produces a thud or jerk around 10 to 20 of flexion. During a positive exam, the force created by the examiner will cause the knee joint to slip, giving a positive visual for identifying rotational knee instability. 15 Continues on page 26 the clinical advisor september

4 Diagnostic criteria Four criteria can definitively diagnose an ACL rupture. Determination is made after retrieving a history of (1) popping during injury, (2) knee instability, (3) effusion or hemarthosis, and (4) a positive Lachman test. 10 The physical examination functionality tests for assessing ACL derangement are specific and moderately sensitive. Therefore, the physical examination is remarkably accurate in the hands of a trained practitioner. If the physical exam is negative, the likelihood the patient has a ligament injury is exceptionally low. Patients that do not meet criteria for an ACL rupture should be managed with conservative and supportive treatment. In light of the fact that 1% to 2% of ligament pathologies are missed during physical examination, careful follow-up and re-evaluation is necessary if symptoms do not improve. 12 After obtaining a positive physical exam indicating possible ACL injury, referral to an orthopedic surgeon is essential. An MRI is not required when deciding whether to refer. MRI adds only marginal value when determining whether a patient needs an orthopedic referral or conservative outpatient therapy. 16 The main purpose of a MRI is prompt identification of any surgically treatable traumatic knee injury. MRI is not invasive; making it faster and more economical for patients and clinicians. 17 A negative MRI of the knee reliably excludes any internal abnormality requiring surgical FIGURE 3. The pivot shift test assesses the degree of incapacitating Click Here What do you think? Add your comments to this article or any article by going to You will also see what your colleagues are saying. intervention, which prevents the need for invasive diagnostic arthroscopy. If symptoms are ongoing, arthroscopy may be an orthopedic surgeon s final diagnostic attempt. 18 A thorough clinical examination, along with MRI, provides the most accurate noninvasive source of information for pathological findings of the ACL. 16 Treatment and prognosis A treatment plan should be developed after obtaining initial symptoms, performing a detailed physical examination, and assessing other associated injuries the patient may have. Other key factors affecting the appropriate treatment include the time interval from the initial injury, the individual s activity level, and the desired goals for returning to competition. 16 Both conservative and operative interventions are considered for treating ACL injuries. Operative treatment is usually performed in athletes, while conservative treatment is likely to have a sufficient outcome for the general population. Clinicians must determine which patients can attempt a return to strenuous activities without surgical intervention. Early surgical stabilization is recommended in active patients presenting with instability. 4 If surgical stabilization is deferred, be aware that an increased risk of knee damage results from the unpredictable functional ability after injury. Compared with conservative treatment, surgical reconstruction provides greater knee stability during daily as well as strenuous activities. The goal of ACL reconstructive surgery is to allow the athlete to return to competition in a timely manner without any further damage. After ACL reconstruction, postoperative rehabilitation is critical for a successful outcome. 11 The setting and frequency of physical therapy affects the rehabilitative process. Techniques that contribute to successful postoperative outcomes include weight-bearing activities, continuous passive motion exercises, and adjunctive modalities. 19 As part of the rehabilitative process, braces should be worn during postoperative recovery and when an athlete returns to competition. 11 Functional knee braces provide mechanical and proprioceptive improvements. By improving extension, decreasing pain and graft strain, and providing protection from excessive forces, the outcome of ACL reconstruction enhanced. Functional knee braces 26 the clinical advisor september

5 Muscle activation is necessary for adequate protection of the ACL. Without it, mobility and stabilization of the knee joint would be impossible. decrease the strain on the reconstructed ligament and boost aspects of neuromuscular control. 20 For patients wishing to defer surgical reconstruction of the ACL, conservative nonoperative treatments include, short periods of immobilization, bracing, progressive rehabilitation programs, and regular follow-up evaluations. Prevention and education Muscle activation is necessary for adequate protection of the ACL. Without it, mobility and stabilization of the knee joint would be impossible. The quadriceps, hamstrings, and gastrocnemius muscles are important knee stabilizers. Careful activation patterns of muscles should be determined to increase stabilization in uninjured individuals as well as ACL-deficient subjects. 21 Maintaining dynamic stability around the knee through neuromuscular control while decreasing magnitude and rate of impact forces generated during landings will help in the prevention of knee injury. Proper deceleration techniques should be addressed to prevent injury to the ACL. 22 Athletes should become adept at such skills as landing softly on the ball of the foot then rolling back to the heel. To decrease stress on the ACL, athletes should be advised to engage in knee and hip flexion while landing or during lateral maneuvers. Training to increase hamstring, gluteus medius, and hip abductor strength, will promote stability and decrease the chance of injury. 23 Using neuromuscular control to provide functional knee joint stability is an important rehabilitative measure after ACL reconstruction. 23 An ACL rupture decreases proprioception, which often remains even after reconstructive surgery. Proprioception is the sensory mechanism of the body that provides necessary information to mediate neuromuscular control and enhance functional joint stability. 6 The sources at a glance l Noncontact ACL injuries are six to eight times more frequent in women than in men. l Acute hemarthrosis, an extravasation of blood into a joint or synovial cavity, is a textbook sign of acute ACL injury. l The physical exam consists of inspection, palpation, and assessment of knee-joint function. l Clinicians must determine which patients can attempt a return to strenuous activities without surgical intervention. of proprioception are mechanoreceptors found in muscular, articular, and cutaneous tissues. They translate mechanical events into neural signals the body understands to create balance and stability. 6 Neuromuscular training is used to decrease such biomechanical risk factors as decreased proprioception to decrease knee injuries, specifically ACL injuries in athletes. The training programs focused on neuromuscular control of the lower extremities help modify landing mechanics and subsequently decrease the prevalence of noncontact ACL injuries. 8 The introduction of balance, strength, and core stability training exercises induces neuromuscular changes and potential injury prevention effects in athletes. 23 n Ms. Daitch is an assistant professor in the physician assistant department at the Medical College of in Augusta, where Ms. Stembridge is a second-year student. References 1. Carey JL, Dunn WR, Dahm DL, et al. A systematic review of anterior cruciate ligament reconstruction with autograft compared with allograft. J Bone Joint Surg Am. 2009;91: Available at pmc/articles/pmc /. 2. Silvers HJ, Mandelbaum BR. Prevention of anterior cruciate ligament injury in the female athlete. Br J Sports Med. 2007;41 Suppl 1:i52-i59. Available at 3. Maffulli N, Longo UG, Gougoulias N, et al. Long-term health outcomes of youth sports injuries. Br J Sports Med. 2010;44: Pinczewski L, Roe J, Salmon L. Why autologous hamstring tendon reconstruction should now be considered the gold standard for anterior cruciate ligament reconstruction in athletes. Br J Sports Med. 2009;43: Li G, Zhang S, Wang X. Biomechanical effect of anterior cruciate ligament rupture on posterior horn of lateral meniscus. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2010;24: Griffin LY, Agel J, Albohm MJ, et al. Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg. 2000;8: Hughes G, Watkins J. A risk-factor model for anterior cruciate ligament injury. Sports Med. 2006;36: Irmischer BS, Harris C, Pfeiffer RP, et al. Effects of a knee ligament injury prevention exercise program on impact forces in women. J Strength Cond Res. 2004;18: Alentorn-Geli E, Myer GD, Silvers HJ, et al. Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 2: a review of prevention programs aimed to modify risk factors and to reduce injury rates. Knee Surg Sports Traumatol Arthrosc. 2009;17: the clinical advisor september

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