The anterior cruciate ligament (ACL) is a knee-stabilizing ligament that prevents the tibia
from sliding out in front of the femur while simultaneously stabilizing the knee joint's rotation. ACL injuries occur most often in sports that involve sudden stopping or change in direction - such as soccer, basketball, and football. Due to the prevalence of this injury and the high percentage of individuals needing surgical repair, research on the most effective rehabilitation protocol after ACL reconstruction is extremely valuable.
One area of focus in literature is whether open kinetic chain(OKC) exercises are more effective than the combination of open and closed kinetic chain(CKC) exercises. In OKC exercises, the segment furthest away from the body, usually the hand or foot, is not fixed to an object, while in CKC exercises, it is fixed or immobile. A good example of an OKC exercise is a seated leg extension, while a common example of a CKC exercise is a squat. Research by Mikkelsen et al. indicates that adding OKC exercises six weeks post-surgery leads to no difference among rehabilitation protocols regarding knee joint stability.3 This suggests that the addition of OKC exercises does not cause or increase the risk of damage to the ligament during rehabilitation.
When looking at muscle strength, the combination of CKC and OKC exercises leads to
greater improvements in eccentric muscle torque of the quadriceps than just CKC exercises alone.3 Additionally, a recent study published in the Orthopaedic Journal of Sports Medicine shows that open-chain exercises effectively accelerate the strengthening of the hamstring muscle.2 A strong hamstring is important to rehabilitation, as restoring the hamstring/quadriceps strength ratio can reduce the risk factor for ACL graft rupture.2 This data indicates that including OKC exercises benefits post-surgery ACL rehabilitation.
Many individuals who experience an ACL sprain or tear are athletes. Therefore, the ability to return and the time it takes to return to their sport is essential to rehabilitation. With ACL reconstruction, there is the possibility the individual may not return to the same
level of physical activity before injury due to factors such as impaired knee function or fear of re-injury.3 The research by Mikkelsen et al. shows that combining CKC and OKC exercises increases the chance of returning to full activity levels by over 100% compared to CKC exercises alone.3 Additionally, individuals who combine the kinetic chain exercises in their rehabilitation protocol can return to their sport approximately two months earlier than those who performed only closed kinetic chain exercises.3 Another reason for including OKC exercises is its effect on the Limb Symmetry Index(LSI). Quadriceps and hamstring muscle function following an ACL rupture are crucial factors contributing to a patient's ability to cope with the injury process.4 Research by Florian Forelli et al. has shown OKC exercises decrease the LSI value in the hamstring at three and six months post-surgery.2 This effectively means the difference in strength and function between the unaffected limb and the affected limb is decreased. These findings suggest that a rehabilitation program for ACL reconstruction post-surgery should be comprised of open and closed kinetic chain exercises.
This is due to the direct benefit of increasing quadriceps strength and hamstring strength while facilitating a more consistent and effective return to sport.
In conclusion, individuals have better physical outcomes with an increased sense of
confidence in their ability as a result of incorporating closed and open kinetic chain exercises during ACL rehabilitation. Further research should focus on observing other aspects of ACL rehabilitation to develop the most efficient and effective protocol for individuals recovering from ACL reconstruction surgery.
If you have experienced an ACL injury or recently underwent knee surgery we encourage you to visit us at Shift Physiotherapy & Wellness located centrally in Edmonton. Our physiotherapist will take the time to complete a comprehensive assessment to evaluate and create an individualized treatment plan to help safely accelerate your return to sport or activities of daily living.
Written By: Evan Grant
1. American Academy of Orthopaedic Surgeons. (2014). Anterior Cruciate Ligament (ACL) Injuries . OrthoInfo. https://orthoinfo.aaos.org/en/diseases--conditions/anterior-cruciate-ligament-acl-injuries/
2. Florian Forelli, Barbar, W., Gwendal Kersante, Amaury Vandebrouck, Pascal Duffiet, Ratte, L., Hewett, T. E., & Rambaud, A. (2023). Evaluation of Muscle Strength and Graft Laxity With Early Open Kinetic Chain Exercise After ACL Reconstruction: A Cohort Study. Orthopaedic Journal of Sports Medicine, 11(6). https://doi.org/10.1177/23259671231177594
3. Mikkelsen, C., Werner, S., & Eriksson, E. (2000). Closed kinetic chain alone compared to combined open and closed kinetic chain exercises for quadriceps strengthening after anterior cruciate ligament reconstruction with respect to return to sports: a prospective matched follow-up study. Knee Surgery, Sports Traumatology, Arthroscopy, 8(6), 337–342. https://doi.org/10.1007/s001670000143
4. Williams, G. N., Snyder-Mackler, L., Barrance, P. J., & Buchanan, T. S. (2005). Quadriceps femoris muscle morphology and function after ACL injury: a differential response in copers versus non-copers. Journal of Biomechanics, 38(4), 685–693. https://doi.org/10.1016/j.jbiomech.2004.04.004
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