When this patient first walked into our sports injury clinic in Tunbridge Wells, his knee strength looked almost normal. On a quad strength test, his injured leg was within 3% of his good one. A lot of people would have taken that as a green light to get back to training.
We didn’t. When we measured how quickly that same muscle could produce force, the injured leg was 56% behind.
This post walks through his first four weeks of ACL rehab with us: what we tested, what we found, what we changed, and where he is now. If you’ve hurt your knee and you’re trying to work out what proper rehab should lo
What is a partial ACL tear?
The anterior cruciate ligament (ACL) sits in the middle of the knee. Its job is to stop your shin bone sliding forward on your thigh bone, and to help control twisting.
Most ACL injuries happen without anyone touching you. You land awkwardly, plant your foot to change direction, or decelerate hard, and the knee twists or collapses inwards. We see them most in footballers, rugby players, netballers, hockey players and skiers, but they happen in the gym and on the school field too.
A partial tear means some of the ligament’s fibres are damaged but it hasn’t fully ruptured. Typical signs include:
- a pop or tearing feeling at the time of injury
- swelling within the first few hours
- the knee feeling loose, wobbly or like it might “give way”
- pain or apprehension when twisting or pivoting
Plenty of people with a partial ACL tear recover well without surgery, as long as the rehab is thorough. If the knee keeps giving way despite good rehab, that’s when we’d refer you on for a scan and a consultant opinion. Either way, the rehab principles in this post apply.
Why we test instead of guess
At our Tunbridge Wells clinic we use VALD DynaMo, a handheld dynamometer that measures how much force a muscle produces and how fast it gets there. It’s the same type of testing used in professional sport, and a full lower-limb screen takes around 15 minutes.
Why bother? Because how a knee feels is a poor guide to how strong it is. After a knee injury, swelling and pain switch the thigh muscles off, and that inhibition can hang around long after the pain has gone. People also compensate without realising, shifting load onto the good leg or into the hip and back.
Testing both legs gives us a clear side-to-side comparison. The common benchmark for returning to sport is a difference of less than 10% between legs. For this patient, we tested three muscle groups:
- Quadriceps (seated knee extension): the main muscles that protect the knee
- Hamstrings (prone knee flexion): they work with the ACL to stop the shin sliding forward
- Hip abductors (side-lying hip abduction): they control where the knee points when you land
Week 0: strong on paper, slow in practice
Here’s what the first assessment showed on 2 September 2026. The injured knee was his right.
Test | Left (uninjured) | Right (injured) | Difference |
|---|---|---|---|
Quad max strength | 85.9 kg | 83.1 kg | 3% |
Quad rate of force development | 218 kg/s | 96 kg/s | 56% |
Hamstring max strength | 18.2 kg | 17.7 kg | 3% |
Hip abductor max strength | 20.0 kg | 14.5 kg | 28% |
Hip abductor rate of force development | 38 kg/s | 19 kg/s | 50% |
Look at the first two rows. If we’d only measured maximum strength, his quads would have passed comfortably. But the injured side was producing that force at less than half the speed.
The hip was behind on both counts: 28% weaker and 50% slower. For an ACL knee, that’s a big deal, and we’ll come back to why.
What is rate of force development, and why does it matter for your knee?
Rate of force development (RFD) is how quickly a muscle can go from relaxed to pushing hard. Strength is how much force you can make. RFD is how fast you can make it.
Think about pushing a heavy car. You could lean into it slowly, building up until you’re pushing as hard as you can. Or you could hit it with everything straight away. Both might end at the same peak, but one gets there far quicker.
Sport doesn’t give you time to build up slowly. When you land from a jump, plant to change direction or stop suddenly, your foot is on the ground for a fraction of a second. ACL injuries tend to happen right at the start of that contact. Reaching full strength takes longer than that window, so what protects the knee is how much force you can produce quickly.
That’s why a knee can test as strong and still be vulnerable. Slow strength arrives too late to help.
Why ACL rehab has to include the hip
Your hip abductors, mainly the glute medius, sit on the outside of your hip. They control how your thigh bone lines up when you land on one leg.
When they’re weak or slow, the knee tends to drift inwards on landing. Clinicians call this dynamic knee valgus. It’s one of the classic positions linked to ACL injury, because it twists and strains the ligament at exactly the wrong moment.
It’s also common for the hip to weaken after a knee injury, simply because you’ve been limping and offloading that side for weeks. So a hip that’s 28% weaker isn’t a surprise. Leaving it that way would be a mistake. Good knee rehab in Tunbridge Wells, or anywhere, should test and train the hip as well as the knee.
How we approached the rehab: Reduce, Restore, Resilience
Every rehab plan at AG Osteopathy & Sports Injury Clinic follows three phases. They overlap, and we move through them based on test results and how the knee responds, not the calendar.
- Reduce. Settle swelling and pain, get the knee moving fully again, and get the quads switching on properly. Hands-on treatment and load management sit here.
- Restore. Rebuild strength and speed, on both the knee and the hip. Because his biggest deficits were in speed, we didn’t just lift heavier. Exercises were done with the intent to push as hard and as fast as possible from the first moment of each rep.
- Resilience. Prepare the knee for the demands of sport: landing, hopping, sprinting, cutting and reacting. This is where we’re heading next.
Week 4: the results
We retested on 1 October 2026. These are the changes on his injured (right) side.
Test | Week 0 | Week 4 | Change |
|---|---|---|---|
Quad max strength | 83.1 kg | 102.2 kg | +23% |
Quad rate of force development | 96 kg/s | 323 kg/s | more than 3x faster |
Hip abductor max strength | 14.5 kg | 22.4 kg | +55% |
Hip abductor strength gap between legs | 28% | 2% | almost level |
Hip abductor rate of force development | 19 kg/s | 70 kg/s | more than 3x faster |
Hip abductor time to peak force (fastest rep) | 3.7 s | 1.6 s | under half the time |
His injured quad is now stronger and faster than his uninjured quad was four weeks ago. His hip strength is almost identical side to side, and its speed now matches the other leg.
To be straight about the limits of this data: at the first test, a couple of the injured-side measures came from a single attempt, which can understate what someone is capable of. We also didn’t retest his left knee this time, so we can’t yet call the quads symmetrical. Both will be checked at his next assessment. Even allowing for that, the direction is clear.
What’s next: getting back to sport
Four weeks in, the foundations are in place. Now the work shifts to the Resilience phase:
- plyometrics and hopping, building up from two legs to one
- landing and deceleration practice, with the knee tracking well
- change of direction and cutting drills
- reactive work, where he doesn’t know which way he’s going until the last moment
- sport-specific training, gradually reintroduced
We don’t clear anyone for return to sport on time alone. Before he’s back to full contact, we’ll want strength and rate of force development within 10% on both legs, good hop test results, and for him to feel confident in the knee. Confidence matters more than people think: hesitation changes how you move.
Frequently asked questions about ACL rehab in Tunbridge Wells
Do I need surgery for a partial ACL tear?
Not always. Many people with a partial tear do well with a structured rehab programme. If your knee keeps giving way even after good rehab, or you have other damage in the knee, we’ll refer you for a scan and a specialist opinion.
How long does ACL rehab take?
It varies a lot with the size of the tear, your sport and how you respond. That’s why we use testing rather than a fixed timeline. You move on when the numbers and the knee say you’re ready.
Can an osteopath help with an ACL injury?
Yes. At our clinic, ACL rehab combines hands-on treatment with exercise-based rehab and objective strength testing. Our clinic director, Angus Gould, has postgraduate training in strength and conditioning and musculoskeletal ultrasound. If you’ve been searching for an ACL physio in Tunbridge Wells, we offer the same type of rehab.
Do I need a GP referral?
No. You can book directly with us. If you’re claiming through private health insurance, check your policy, as some insurers ask for a GP referral.
What does strength testing involve?
You push against a small handheld device in a few set positions. It’s quick, painless and gives us exact figures for each leg, so we can compare sides and track progress over time.
Where are you based?
We’re on Upper Grosvenor Road in Tunbridge Wells. We see patients from across Kent and East Sussex, including Tonbridge, Southborough, Pembury, Rusthall, Crowborough, Paddock Wood, Sevenoaks and Frant.
Book an ACL assessment in Tunbridge Wells
If you’ve injured your knee, or you’ve been told you’re ready to return to sport but don’t feel it, come and get tested. We’ll measure both legs, show you exactly where you stand, and build a rehab plan around what the numbers find.
AG Osteopathy & Sports Injury Clinic is on Upper Grosvenor Road, Tunbridge Wells, and easy to reach from Tonbridge, Southborough, Pembury, Crowborough and the surrounding areas.
Book your assessment online (link to booking page)
Written by Angus Gould, osteopath and clinic director. First Class Masters in Osteopathy (Swansea University), with postgraduate training in strength and conditioning, dry needling, shockwave therapy and musculoskeletal ultrasound.
