An ACL tear can happen in a second. Rehabilitation takes much longer.
For many people, the real goal is not simply to walk normally again. They want to run, ski, play football, cycle, jump or return to demanding training. That is why ACL rehabilitation has to keep evolving over several months.
What matters in the first few weeks is not enough later on.
Does every ACL tear need surgery?
No. The decision depends on instability, associated injuries, the sport you want to return to and your personal goals.
A 2025 systematic review and meta analysis found no clear difference in return to sport rates or activity level between people managed with ACL reconstruction and those managed with rehabilitation without surgery. That does not mean surgery is unnecessary. It means the decision should be individual rather than based on the words ACL tear alone.
Early rehabilitation: calm the knee and restore function
After surgery or a recent injury, the priorities are fairly simple. Reduce the knee reaction. Restore full extension. Recover flexion progressively. Walk normally again. And get the quadriceps working properly.
Strength work therefore starts well before the sport specific phase. Load is increased according to healing, swelling, pain and medical restrictions.
The 2023 Aspetar clinical practice guideline places exercise at the centre of rehabilitation after ACL reconstruction. Passive treatment can be useful at the beginning, but it does not replace active rehabilitation.
Strength soon becomes the main issue
As the knee improves, rehabilitation starts to look more like training. Leg press, squats, lunges, single leg exercises, hamstring work and calf strength can all be useful depending on the stage.
The question is not simply whether a movement is possible. It is how much load the person can handle, how well the movement is controlled and how confident it feels.
Sport requires reserve. Accelerating, braking, landing and changing direction place much greater demands on the knee than normal walking.
When can running start again?
The usual question is often: which month can I start running? It is understandable. But another question is often more useful: what can the knee already do?
Return to running should not be based on the calendar alone. Range of motion, swelling, strength and load tolerance also matter. The Aspetar guideline therefore recommends combining time with functional criteria.
A date can help with orientation. It cannot replace an assessment.
Return to Sport is more than a hop test
Later come jumping, landing, acceleration, braking and changes of direction. Looking only at jump distance is not enough.
How does the person land? What happens at the hip and knee? Can they absorb force quickly? Does movement quality remain good when fatigue increases?
A large 2025 meta analysis included 136 studies and 23,360 participants. It showed that different hop tests reveal different deficits. Vertical jumps in particular can continue to show differences between the two legs for longer.
Why 90 percent symmetry does not automatically mean ready
Comparing the injured leg with the other side is useful. But there is a limitation. If both legs have lost strength during rehabilitation, they may look similar while both are still below the level needed for sport.
When possible, I therefore also look at absolute strength, movement quality and the actual demands of the sport.
A 2025 network meta analysis with 1889 participants supports this broader approach. Psychological readiness, self reported knee function and physical tests each provided useful information about return to sport. No single number described the whole picture.
From the first run back to full performance
Return to Sport is not one date. It is a progression.
It often starts with simple running and controlled jumping. Then speed increases. Movements become more complex. Depending on the sport, the next steps may include changes of direction, sprinting, contact or longer periods of repeated effort.
A runner has different needs from a football player. Skiing is not the same as BMX. The final phase should therefore resemble the real sporting demands as closely as possible.
What can be tested during ACL rehabilitation?
Depending on the stage, useful measures can include range of motion, swelling, quadriceps strength, posterior chain strength, single leg capacity, jumping, landing, running mechanics, braking and changes of direction.
Confidence matters too. Someone can be physically strong and still hesitate with every fast movement. That is relevant when planning a return to training or competition.
ACL rehabilitation in Basel
In my sports physiotherapy practice in Basel, I work with people after ACL injury or ACL reconstruction from the early strength phase through return to running and sport.
The final question is not only: how many months have passed?
It is: is the knee actually ready for the demands of the sport?
Read more about sports physiotherapy and Return to Sport in Basel
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Common questions
How long does physiotherapy take after ACL surgery?
Rehabilitation usually lasts many months. How long regular physiotherapy remains useful depends on strength progress, the sport you want to return to, associated injuries and how the knee responds.
Can an ACL tear be treated without surgery?
For some people, rehabilitation without surgery is a reasonable option. The decision should be made with the medical team and should reflect the person’s real goals and knee function.
Does nine months automatically mean I am ready for sport?
No. Time matters, but it is not enough on its own. Strength, function, load tolerance, movement quality and the demands of the sport also need to be considered.
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