The Physio Hub

ACL rehab: “Who’s afraid of the big bad wolf”

The rehabilitation process post ACL reconstruction has developed over the years and benefitted from advancements in research. Below is a collated summary of the research review ‘Who’s afraid of the big bad wolf’ Noehren B, Snyder-Mackler L (2020)- which addresses the use of Open Kinetic Chain exercises (the big bad wolf) during the early rehab phase.

What are the goals of post ACL reconstruction rehab?

ACL rehabilitation is multifaceted and extensive. Due to the prevalence of re-rupture of ACL repairs it is important not to rush each stage and meet the relevant goals before progressing.

The main goals of rehab are; full range of motion at the knee, regain muscle strength and proprioception, good functional stability, return to previous functional level, decrease risk for re-injury, and return to sport.

What is the fear behind OKC exercises?

Previously, with early ACL rehabilitation, open kinetic chain (OKC) exercises were discouraged. It was believed OKC exercises placed a large strain on the ACL. However, it was found that walking places 2-3 times the load of OKC leg extension exercises, so why are we avoiding this?

What are the benefits of OKC exercises?

One benefit of OKC exercises are that they only allow movement of one joint, targeting a specific muscle group. This reduces and stops any compensations that the body can make.

For example: Seated knee extension- working the quadriceps in isolation. Squat- works the quads, glutes, hamstrings etc… although more functional, if one area is weaker the others can compensate to achieve the movement.

One of the main muscles inhibited post ACL reconstruction are the quadriceps. The quadriceps are vital in regaining knee stability, strength and function and therefore require a lot of focus to achieve the desired strength post-surgery. Completing exercises such as OKC exercises can facilitate quad muscle regeneration and recruitment.

That being said, in the acute phase, only low loading of OKC exercises are necessary. Resistance is increased to 60-70% of a patients 1 rep max as they progress through their programme.

Research from a paper by Fitzgerald GK, Piva R and Irrgang JJ, showed a positive correlation of combing neuromuscular electrical stimulation with leg extension with quadricep strength and self-reported knee function at both the 12 and 16 week post-op mark.

There are benefits to gain from both open kinetic chain exercises and closed chain exercises, however, it is important not to disregard the OKC exercises in the early phases as it is significant in overcoming quadriceps inhibition.

So, don’t be afraid of the big bad wolf!