Current concepts for injury prevention in athletes after anterior cruciate ligament reconstruction

Abstract

Ligament reconstruction is the current standard of care for active patients with an anterior cruciate ligament (ACL) rupture. Although the majority of ACL reconstruction (ACLR) surgeries successfully restore the mechanical stability of the injured knee, postsurgical outcomes remain widely varied. Less than half of athletes who undergo ACLR return to sport within the first year after surgery, and it is estimated that approximately 1 in 4 to 1 in 5 young, active athletes who undergo ACLR will go on to a second knee injury. The outcomes after a second knee injury and surgery are significantly less favorable than outcomes after primary injuries. As advances in graft reconstruction and fixation techniques have improved to consistently restore passive joint stability to the preinjury level, successful return to sport after ACLR appears to be predicated on numerous postsurgical factors. Importantly, a secondary ACL injury is most strongly related to modifiable postsurgical risk factors. Biomechanical abnormalities and movement asymmetries, which are more prevalent in this cohort than previously hypothesized, can persist despite high levels of functional performance, and also represent biomechanical and neuromuscular control deficits and imbalances that are strongly associated with secondary injury incidence. Decreased neuromuscular control and high-risk movement biomechanics, which appear to be heavily influenced by abnormal trunk and lower extremity movement patterns, not only predict first knee injury risk but also reinjury risk. These seminal findings indicate that abnormal movement biomechanics and neuromuscular control profiles are likely both residual to, and exacerbated by, the initial injury. Evidence-based medicine (EBM) strategies should be used to develop effective, efficacious interventions targeted to these impairments to optimize the safe return to high-risk activity. In this Current Concepts article, the authors present the latest evidence related to risk factors associated with ligament failure or a secondary (contralateral) injury in athletes who return to sport after ACLR. From these data, they propose an EBM paradigm shift in postoperative rehabilitation and return-to-sport training after ACLR that is focused on the resolution of neuromuscular deficits that commonly persist after surgical reconstruction and standard rehabilitation of athletes.

Figure 1

Schematic representation of the 4 measures of neuromuscular asymmetry highly predictive of second injury risk in athletes who underwent anterior cruciate ligament reconstruction.

Figure 2

Examples of singleleg anterior (A) and lateral (B) progression activities. These tasks can aid the sports medicine clinician both in identifying and treating clinically important, bilateral neuromuscular dysfunction after anterior cruciate ligament reconstruction.

Figure 3

Proper tuck jump technique. The athlete begins in deep hip and knee flexion and swings the arms backward in preparation for the jump. The goal is to minimize frontal-plane motion of the trunk and lower extremities while achieving a thigh position that is parallel to the floor at the height of the jump. The sports medicine clinician should view the athlete during repeated jumps in both the sagittal and frontal planes to identify takeoff and landing asymmetries.

Figure 4

Schematic representation of how anterior cruciate ligament reconstruction can drive postsurgical symmetries and neuromuscular deficits. These impairments are, in turn, minimized with sports symmetry training and preventative multiplane dynamic movement tasks.