Recovering from a surgical procedure can be a daunting experience, especially if it’s your first time under the knife. Setting expectations and small steps to reach key milestones along your ACL journey will keep you motivated and focused for the 9-12+ months of rehabilitation, before returning to change of direction sport.

Your first phase of ACL rehabilitation is to create an environment for optimal graft and bone healing, whilst starting to load the knee safely. This rehab phase lasts around 12 weeks post op (longer for complex knee injuries).

Let’s take a look at what happens in these first 12 weeks:

Early Graft Healing 0-4 weeks

The body has recognised the original ligament has been replaced by a new tissue graft (usually a tendon graft from hamstrings, patella or quadricep). The healing cells get to work and bombard the area to start remodelling the new tissue and laying down new networks to increase blood supply (known as re-vascularisation).

Proliferation 4-12 weeks 

Re-vascularisation increases and the “healing cells” start to lay down an external matrix or scaffolding around the new graft and bone tunnels. This prepares the graft tissue to enter the next stage, where it starts to morph into the mechanical strength of an intact ACL to withstand increasing loads.

Ligamentisation 12weeks + 

With the support of the scaffolding around it, the body will start to lay down the foundations for the graft to turn into and do the job of a ligament. This phase has been seen to continue for up to 2 years.

Understanding these stages of healing is important as you find the right balance in your rehabilitation in the first few months post op. Here are the key measures and goals we use post ACL surgery in the first phase of rehab:

1. Walk without a limp

You will likely need the support of crutches in the first few days to weeks. You can stop using them as soon as you can walk without a noticeable limp.

2. Swelling management

Excessive swelling can slow down early graft healing and cell proliferation. Load management, elevation, ice, compression and gentle exercise can help reduce swelling in these early weeks.

3. Achieve full straightening of the knee 

Full knee extension (0 degrees) is important to allow sufficient quadriceps activation and contraction

4. Achieve knee bending >125 degrees

This should be progressed comfortably over the first 12 weeks of rehab. Bending the knee should feel easier as the weeks progress.

5. Quadriceps strength

Aim for a leg lift with a completely straight knee. This tells us that the knee is strong enough to withstand more load and progress to the next phase of rehab.

6. Balance

Retraining control and balance of the knee is vital in early ACL rehab.  Aim to balance on the operated leg for 45 seconds.

7. Strength & Load

Specific strengthening exercises for the quadriceps, hamstrings, calf, gluteals and core will feature in your rehab. Aim to be able to squat 1.5x your body weight before progressing on to the next phase of rehab (running, jumping, landing).

Click here for an ACL Checklist for a Safe Return to Running.

Need help with a structured rehabilitation program post ACL surgery? Book an appointment with our experienced physiotherapists.

References:

S. U. Scheffler Æ F. N. Unterhauser Æ A. Weiler (2008): Graft remodeling and ligamentization after cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc

Randall Cooper and Mick Hughes (2020). Melbourne ACL Rehabilitation Guide 2.0 [PDF]