Weightbearing and non-weightbearing exercises Weightbearing (WB) and non-weightbearing (NWB) exercises, also known a s closed kinetic chain and open kinetic chain exercises, respectively, are used in rehabilitation programs for patients following ACL injury and ACL reconstruction surgery to improve quadriceps strength and dynamic knee stability (Escamilla et al., 2009; Escamilla, MacLeod, Wilk, Paulos, & Andrews, 2012a; Fleming, Oksendahl, & Beynnon, 2005). During the first few weeks after ACL reconstruction surgery, patients begin loading their operated knee as tolerated to manage pain and to protect the healing tissue. Biological incorporation of soft tissue grafts such as STG requires more time (typically 8 to 12 weeks) when compared to grafts incorporating bone plugs (Buckwalter, Grodzinsky, Hunter, & Thomas, 1999). Therefore, rehabilitation following ACL reconstruction may be modified according to the time frame of biological healing and graft remodeling (Kvist, 2006). Exposing the new graft tissues – which are undergoing remodeling and maturation processes – too early
to an excessive and uncontrolled load may cause graft rupture or graft failure (Mikkelsen, Werner, & Eriksson, 2000). Although overloading the reconstructed graft may cause graft rupture or failure, unloading the graft may delay recovery and weaken the graft strength (Buckwalter et al., 1999). Thus, early resumption of activities that place controlled load onto the healing tissue enhances graft tissue strength and function (Buckwalter et al., 1999). Clinicians should therefore implement gradual, progressive loading of the lower extremity musculature and the ACL graft during the rehabilitation process while respecting the healing times of concomitant injuries and surgical considerations (see above). Open kinetic chain (NWB) exercises are both safe and essential to restoring quadriceps strength (Noehren & Snyder- Mackler, 2020). Closed chain (WB) are also safe and generally more functional. Both WB and NWB exercises should be incorporated throughout the recovery process in controlled, progressive manners.
Figure 7: Examples of Weightbearing Exercises (Closed Kinetic Chain Exercises)
Note . From Western Schools, © 2018.
The 2017 updated clinical practice guidelines for knee ligament sprains suggests implementing both WB and NWB exercises within 4 to 6 weeks of injury (Logerstedt et al., 2017). Progressive rehabilitation programs typically recommend incorporating these exercises earlier after surgery in controlled manners (Adams et al., 2012; Capin, Behrns, et al., 2017). Executing strengthening exercises throughout the entire knee flexion ROM early after ACL reconstruction may place tension on the new graft, although
some tension is needed for graft maturation. Therefore, clinicians may consider having patients begin performing WB training in a limited ROM of knee flexion (0° to 40°). Early after ACL reconstruction, patients may perform NWB eccentric training on a limited knee flexion ROM (90° to 45°). At 6 weeks following surgery, patients may perform both WB and NWB eccentric exercises at larger knee flexion ROM (0° to 90°) to maximize quadriceps strength (Lorenz & Reiman, 2011).
Figure 8: Non-weightbearing (Open kinetic chain) Exercise Example
Note . From Western Schools, © 2018.
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