After obtaining a positive physical exam indicating a possible ACL injury, referral to an orthopedic surgeon is essential. An MRI is not required when deciding whether to refer to a specialist. MRI adds only marginal value when determining whether a patient needs an orthopedic referral or conservative outpatient therapy.16 The main purpose of an MRI is prompt identification of any surgically treatable traumatic knee injury. The primary advantage of MRI is that it is not invasive, which makes it faster and more economical for patients and clinicians.17 A negative MRI of the knee reliably excludes any internal abnormality requiring surgical 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 recording the patient’s initial symptoms, performing a detailed physical examination, and assessing any associated injuries that may be present. Other key factors used to determine appropriate treatment include the time interval since the initial injury, the person’s activity level, and the desired goals for returning to competition.16 Both operative and conservative 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, inform the patient that risk of knee damage increases due to 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 incurring 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
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, these devices enhance the outcome of ACL reconstruction. Functional knee braces reduce 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 in ACL-deficient subjects.21
Maintaining dynamic stability around the knee through neuromuscular control while reducing 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 and 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 lower the risk 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 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 reduce such biomechanical risk factors as decreased proprioception and prevent 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.24
Ms. Daitch is an associate professor in the Physician Assistant Department at Georgia Health Sciences University in Augusta, where Ms. Stembridge is a second-year student.
- 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;91:2242-2250.
- Silvers HJ, Mandelbaum BR. Prevention of anterior cruciate ligament injury in the female athlete. Br J Sports Med. 2007;41 Suppl 1:i52-i59.
- Maffulli N, Longo UG, Gougoulias N, et al. Long-term health outcomes of youth sports injuries. Br J Sports Med. 2010;44:21-25.
- 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;43:325-327.
- 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;24:14-16.
- Griffin LY, Agel J, Albohm MJ, et al. Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg. 2000;8:141-150.
- Hughes G, Watkins J. A risk-factor model for anterior cruciate ligament injury. Sports Med. 2006;36:411-428.
- 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;18:703-707.
- 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;17:859-879.
- Guillodo Y, Rannou N, Dubrana F, et al. Diagnosis of anterior cruciate ligament rupture in an emergency department. J Trauma. 2008;65:1078-1082.
- Linko E, Harilainen A, Malmivaara A, Seitsalo S. Surgical versus conservative interventions for anterior cruciate ligament ruptures in adults. Cochrane Database Syst Rev. 2005;2:CD001356. A
- Jackson JL, O’Malley PG, Kroenke K. Evaluation of acute knee pain in primary care. Ann Intern Med. 2003;139:575-588.
- Dutton M. Orthopaedic Examination, Evaluation, & Intervention. 2nd edition. Pittsburgh, Pa.: McGraw-Hill Medical; 2008:932-933.
- Swärd P, Kostogiannis I, Roos H. Risk factors for a contralateral anterior cruciate ligament injury. Knee Surg Sports Traumatol Arthrosc. 2010;18:277-291.
- Solomon DH, Simel DL, Bates DW, et al. The rational clinical examination. Does this patient have a torn meniscus or ligament of the knee? Value of the physical examination. JAMA. 2001;286:1610-1620.
- Munshi M, Davidson M, MacDonald PB, et al. The efficacy of magnetic resonance imaging in acute knee injuries. Clin J Sport Med. 2000;10:34-39.
- Crawford R, Walley G, Bridgman S, Maffulli N. 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.
- Biau DJ, Tournoux C, Katsahian S, et al. Bone-patellar tendon-bone autografts versus hamstring autografts for reconstruction of anterior cruciate ligament: meta-analysis. BMJ. 2006;332:995-1001.
- Wright RW, Fetzer GB. Bracing after ACL reconstruction: a systematic review. Clin Orthop Relat Res. 2007;455:162-168.
- Birmingham TB, Bryant DM, Giffin JR, et al. A randomized controlled trial comparing the effectiveness of functional knee brace and neoprene sleeve use after anterior cruciate ligament reconstruction. Am J Sports Med. 2008;36:648-655.
- Anderson AF, Dome DC, Gautam S, et al. Correlation of anthropometric measurements, strength, anterior cruciate ligament size, and intercondylar notch characteristics to sex differences in anterior cruciate ligament tear rates. Am J Sports Med. 2001;29:58-566.
- Brophy RH, Silvers HJ, Mandelbaum BR. Anterior cruciate ligament injuries: etiology and prevention. Sports Med Arthrosc. 2010;18:2-11.
- Hewett TE, Myer GD, Ford KR. Reducing knee and anterior cruciate ligament injuries among female athletes: a systematic review of neuromuscular training interventions. J Knee Surg. 2005;18:82-88.
- Peeler J, Leiter J, MacDonald P. Accuracy and reliability of anterior cruciate ligament clinical examination in a multidisciplinary sports medicine setting. Clin J Sport Med. 2010;20:80-85.
All electronic documents accessed August 15, 2011.