RETHINKING RETURN TO SPORT REHAB
Evidence suggests that more than 50% of athletes are unable to return to their preinjury level of function after ACL reconstruction. Second ACL injury rates, accounting for ipsilateral and contralateral tears, have been reported between 12% and 31%.1
Younger age and return to sport involving pivoting and cutting has been identified as a risk factor for ACL reinjury. A study by Paterno found that 29.5% of young, active athletes who returned to cutting and pivoting sports after an ACL reconstruction suffered a second ACL injury 24 months after return to sport.2
Paterno et al also assessed biomechanical and neuromuscular variables in a group of young athletes who returned to pivoting and cutting sports. He found three predictive biomechanical variables during a drop-vertical-jump maneuver including increased hip internal rotation, increased peak knee valgus, and side-to-side asymmetries in sagittal-plane knee moment.3
Roughly 70 percent of ACL tears occur from a noncontact mechanism of injury due to a loss of neuromuscular control. The noncontact mechanism of injury has been associated with a failure to maintain knee neuromuscular control while attending to external factors involving complex dynamic visual stimuli, movement planning, rapid decision-making, environmental interactions, and unanticipated perturbations.4
Recent research shows that neurocognitive coordination is impaired in patients with injured or repaired ACLs. Recent studies demonstrate structural changes in the nervous system and the brain following injury and reconstruction that may be limiting function and return to sport. In addition to being mechanical stabilizers, ligaments naturally have cells called mechanoreceptors that relay sensory information from the joint to the brain. Injury to the ligament or replacement with a graft causes a loss of these mechanoreceptors disrupting the communication between the joint and the brain.5
Early data on existing neuromuscular training programs suggest that enhancing body control may decrease ACL injuries in women. Current rehab models focus on quad strength, power, and neuromuscular control as a measure of return to sport readiness. Common return to sport tests includes isometric quad strength, single leg squat, single leg hop, triple hop, and cross over triple hop.
Perhaps advancing ACL rehab programs beyond neuromuscular control to incorporate neurocognitive training and reactive agility would lead to better return to sport outcomes.
Dingenen et al looked at twenty-eight ACL-reconstructed athletes 6 months postoperative and found faster reactive agility was significantly correlated with better functional performance and patient-reported outcome measures.6
Agility training involving decision making and response to external stimuli may better prepare our athletes for game time scenarios and reduce risk of second ACL injury.
Written by Hannah Sweitzer, DPT, OCS, CSCS
- Boden BP, Sheehan FT, Torg JS, Hewett TE. Noncontact anterior cruciate ligament injuries: mechanisms and risk factors. J Am Acad Orthop Surg. 2010;18(9):520-527. doi:10.5435/00124635-201009000-00003
- Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of Second ACL Injuries 2 Years After Primary ACL Reconstruction and Return to Sport. Am J Sports Med. 2014 Jul;42(7):1567-73. doi: 10.1177/0363546514530088. Epub 2014 Apr 21. PMID: 24753238; PMCID: PMC4205204.
- Paterno MV, Schmitt LC, Ford KR, et al. Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and return to sport. Am J Sports Med. 2010;38(10):1968-1978. doi:10.1177/0363546510376053
- Griffin LY, Agel J, Albohm MJ, Arendt EA, Dick RW, Garrett WE, Garrick JG, Hewett TE, Huston L, Ireland ML, Johnson RJ, Kibler WB, Lephart S, Lewis JL, Lindenfeld TN, Mandelbaum BR, Marchak P, Teitz CC, Wojtys EM. Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg. 2000 May-Jun;8(3):141-50. doi: 10.5435/00124635-200005000-00001. PMID: 10874221.
- Boden BP, Dean GS, Feagin JA Jr, Garrett WE Jr. Mechanisms of anterior cruciate ligament injury. Orthopedics 2000; 23:573.
- Dingenen B, Truijen J, Bellemans J, et al 16 Relationships between a multidirectional reactive agility test, functional performance and patient-reported outcome measures 6 months after anterior cruciate ligament reconstruction. British Journal of Sports Medicine 2019;53:A6