Chapter 2: ACL Injury, Surgery, and Rehabilitation: A Science-Based and Evidence-Informed Approach 2 CCHs
By: Jacob J. Capin, PT, DPT, PhD, MS; Zakariya H. Nawasreh, BS, MSc, PhD; and David S. Logerstedt, PT, PhD, MPT, MA, SCS Learning objectives
After completing this course, the learner will be able to: Identify and describe the anatomy of the anterior cruciate ligament (ACL) and key surrounding structures including how they contribute to knee arthrokinematics; Discuss the typical mechanism of injury, clinical course, and risk factors associated with ACL injury; Apply a comprehensive clinical examination to develop a specific diagnosis for patients with a suspected ACL injury; Course overview Injury to the anterior cruciate ligament (ACL) can be devastating. Approximately 250,000 ACL injuries occur annually in the United States and ACL injury rates are rising, particularly among young individuals involved in jumping, cutting, and pivoting sports (Frank & Jackson, 1997; Griffin et al., 2000; Majewski, Susanne, & Klaus, 2006). ACL injuries typically result in substantial short-term physical impairments and long-term joint morbidity including a high risk for subsequent injury and early, post-traumatic osteoarthritis. The purpose of this intermediate-level course is to provide physical therapists and physical therapist assistants with an overview of the etiology and risk factors of isolated ACL injury; to discuss pertinent clinical examination, classification, and prognosis after ACL injury and reconstruction; and to review interventions relevant to successful outcomes after injury or surgery. Injury to the anterior cruciate ligament (ACL) is the most prevalent of internal knee lesions, with upwards of 250,000 ACL injuries occurring each year in the United States (Frank & Jackson, 1997; Griffin et al., 2000; Majewski, Susanne, & Klaus, 2006). The annual national incidence rate of ACL injury in different populations ranges from 8 to 52 per 100,000 persons, with a median of 32 per 100,000 persons (Moses, Orchard, & Orchard, 2012). Men aged 19 to 25 years have the highest incidence rate, at 241.0 per 100,000 person-years (Sanders et al., 2016). The peak incidence rate for women is in the 14- to 18-year-old range (227.6 per 100,000 person-years; Sanders et al., 2016). Compared with boys, girls have a higher overall rate of ACL injury (relative risk [RR], 1.40, [95% CI 1.25-1.57]) with the largest disparity occurring in basketball (RR, 4.14 [95% CI, 2.98-5.76]; Bram et al., 2020), despite a greater number of ACL injuries in boys (Gornitzky et al., 2016). A tear is most likely to occur in the mid-substance (middle portion of the tissue) of the ACL during noncontact injuries, as seen in sporting activities (Kennedy, Hawkins, Willis, & Danylchuck, 1976; Noyes, Torvik, Hyde, & DeLucas, 1974). Approximately 30% of all ACL injuries involve physical contact while the majority are noncontact in nature (Hewett, Stroupe, Nance, & Noyes, 1996). The incidence of noncontact ACL injuries is greater in sports that require multidirectional activities, such as rapid deceleration, pivoting, cutting, and landing from jumps (Griffin et al., 2006). Sports activities account for 88% of
Describe the diagnostic strategies, management plans, and classification of patients with ACL injury; Formulate a rehabilitation program using clinical strategies and evidence-based interventions after ACL injury and ACL reconstruction Explain the functional and clinical outcomes after ACL injury and reconstruction. Given the modifications and advancements in ACL surgical procedures and the proliferation of research on interventions and outcomes, many clinicians find it difficult to keep apprised of the latest evidence and integrate this new information into their clinical practice. Decisions regarding which patients are appropriate for non-operative management of an ACL-deficient knee, how to safely progress patients through a criterion- based guideline, and when to provide recommendations for a safe return back to sports after ACL injury or reconstruction are challenging. Physical therapists and physical therapist assistants will be able to use the knowledge and skills outlined in this course with their patients after ACL injury or surgery to maximize patients’ responses to exercise at their current functional level while minimizing risk of injury to the healing tissue(s).
INCIDENCE
injuries to the ACL, although ACL injuries from motor vehicle accidents and work injuries have also been reported (Magnussen et al., 2010). In the United States, most ACL injuries occur in young athletes (Wojtys & Brower, 2010) and people of various ages who participate in basketball, soccer, football (Magnussen et al., 2010) and downhill skiing (Pujol, Blanchi, & Chambat, 2007). In comparable sports, girls are 3.4 times more likely to sustain an ACL injury than boys (Joseph et al., 2013). In girls, the highest per-season injury risk levels are in gymnastics, soccer, basketball, and lacrosse (Agel, Rockwood, & Klossner, 2016; Gornitzky et al., 2016). In boys, the highest injury risk levels per season are in American football, lacrosse, and soccer (Gornitzky et al., 2016). More than 127,000 ACL reconstructions are performed annually, making it the sixth most common orthopedic procedure in the United States (Hughes & Watkins, 2006; Kim, Bosque, Meehan, Jamali, & Marder, 2011), although rates are rising. From 2002 to 2014, the overall rate of ACL reconstruction increased 22% in the United States; adolescents (age 13 to 17 years) incurred the highest absolute rates, which increased 37%, 107% and 63% during the study period for isolated ACL reconstruction, ACL reconstruction with meniscal repair, and ACL reconstruction with meniscectomy, respectively (Herzog et al., 2018). In Australia from July 2000 to June 2015, the annual incidence of ACL reconstruction increased 43% including an astonishing 74% among those under 25 years of age (Zbrojkiewicz et al., 2018).
FUNCTIONAL ANATOMY
The ACL originates on the medial side of the lateral femoral condyle and runs through the intercondylar fossa to insert onto the medial tibial eminence (Figure 1). It can be divided into two functional bands, the anteromedial and posterolateral bundles
(Petersen & Zantop, 2007). These two bands play different roles, depending on the degree of knee flexion. The anteromedial bundle remains taut throughout the full degree of knee range of motion (ROM), with increased tightening near full flexion (Amis
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