Anterior Cruciate Ligament Injury

ACL – Anterior Cruciate Ligament Injury

What does an injury look like? (

If you are reading this you are either concerned about injury, have had an injury or you are about to undergo reconstruction of the ACL.  At Core Body Clinic, Ltd we are experts in the treatment of ACL injuries. 

The ACL is a ligament inside the knee.  It is a very strong ligament and works to keep the knee stable by providing structural support and vital neurological information about the speed, position and posture of the knee in relation to the body and environment.  If you are involved in pivoting sports or activities where there is a sudden change in direction, then the ACL is a very important ligament.  Generally, you cannot feel the ACL in day to day living and we blissfully go about our daily activities without ever considering how important it is.   When we injure the ligament there is often an audible pop and the injured person often collapses in a heap on the floor thinking they have done something terrible to the knee.  In some cases the player or athlete will continue to run, noticing little but swelling and pain in their knee.

With the text book ACL injury the player will classically tell the story about running, turning or stepping to the inside and the giving way and buckling underneath them as they move.

The knee typically goes into a Varus of abducted movement, combined with external rotation of the tibia.  There is often an injury to the medial collateral ligament, though this is minor, and in some cases the cartilage of the medial meniscus.  In cases where all three are injured we call this an ‘unhappy triad’. 

Diagnosis is often done by carful history taking and asking the patient to tell a story about their injury.  A comprehensive manual assessment is then performed to understand how the knee has been injured.  This will look at ranges of movement, swelling and alignment of the knee.  We may also look at foot and pelvic biomechanics to understand if there are any markers for injury risk.  The best way to assess the integrity of the ACL is to apply the lachman’s test where the examiner grasps both the femur and tibia and pulls then apart.  In an ACL deficient or injured knee there will be laxity compared to an intact ACL where there will be a solid end feel, as if tugging on a piece of rope.

An MRI will provide 99.9% certainty and of course an examination under anaesthetic will be 100% conclusive.  However, history, examination and MRI are usually enough to determine the likely injury.  An X-ray is often useful to 1st establish whether there is a fracture, and this is essential if the patient cannot stand on the knee.  The ligament is so strong it may snap and in doing so pull incredibly hard on the tibial plateau causing a fracture.  In this case there would be a required period of immobilisation prior to fixing the ACL.


Do you need the ACL reconstructed?

Well, some authors say not and we can cope quite well without it.  Research shows that expert physiotherapy guided rehab and loading of the knee over a period of 3 months is enough to return a player to sport.  In many cases consensus dictates that young persons in their teens, 20’s and early 30’s who intend on playing sport again should have the ligament reconstructed and under go the 9-12 months of intense rehabilitation.  Over 35 years of age and not intending to play again then we should consider a 3-month intense plan.  Though this is the evidence, it is up to the patient to determine the best course of action for themselves and they should plan with the surgeon and physiotherapist, so they can make an informed choice.  12 months of rehabilitation is a significant length of time and the level of commitment is not a consideration that should be taken lightly.

The operation is called an autograft procedure where a new ligament is formed from a piece of tendon belonging to the patient.  Typically, in the UK we use a hamstring tendon.  In the USA there is a trend towards a patella tendon graft and there are some surgeons who also follow this technique in the UK.  At Core Body Clinic, we are familiar with all types.  Some newer techniques also use the Kevlar pillars to stabilise the knee claiming to return persons to sport quicker.  These are a pioneer of new and older tried and tested procedures.  Time will tell if they are superior to the most widely used isolated tendon graft.

The knee is battered and bruised after the operation.  Two portal holes are made in the front of the knee, a pilot hole above the knee and a 2inch incision is made just over the inside of the tibia.  Between the 4 cuts, drilling and grafting of the tendon, the knee will swell and likely be very achey.  This is normal and medication should be used for the 1st two weeks as and when required.

Rehabilitation is commenced in hospital and exercises are given to help the patient move the knee for the first 2 weeks.  You will see your physio at Core Body Clinic within the first 2 weeks.  The frequency of your visits will depend on your progress. 


If you have an ACL reconstruction the rehabilitation is broken down into 5 phases:


1 Acute Phase

2 Building Phase

3 Prep Phase

4 Pre-sport Phase

5 Return to Sport Phase  

Rehab is essential to the formation of a new ligament that will function to the same capacity as the old one.


The Acute Phase manages your pain, swelling and restores your ranges of movement immediately following surgery and can last for 6 weeks.  Patients are typically on crutches and rest for 2 weeks and mobilise with crutches (if needed).  Pain is variable and patient dependent.  Some have little where others have significant pain.  In this phase there will be slow and graduated exercises focused on the movements of flexion and extension.  It is essential to get the movement in the operated leg equal to the unoperated leg with regard to extension and up to 120 degrees of flexion within the first 6 weeks.  Resting and graduated activity will play a huge part in this. At Core Body Clinc we warn patients that it is the boredom phase.  We aim to make rehab as fun as possible.

In this phase you will do:

Heel slides, inner quad contractions, prone flexion, ab and ad – duction, gluteal exercises and core, graduating to bike, aqua walking (when wounds heeled) and as much seated upper body as you want (we recommend machines and after week 2 depending on how you feel).   Again, this is for movement and swelling control and the plan will be individual after the 2 weeks phase as swelling and movement improve.  Knee exercises will be progressed to low load closed chain.


The building phase is where the knee feels a lot better and is typically 4-6 weeks and beyond.  Here we want to get your quads bigger and start building the hamstrings again.  Exercises will be varied and much harder.  Initially we monitor swelling and graduate your activity.  It is very important to listen to the program so you don’t wind up with too much swelling, if any.  Tougher bike, steps, weighted squats and hamstrings, heavier gluteal and core exercises will come into place. Early balance work will start with basic stability challenge exercises.  The easier you find them, the harder it becomes!

We will also get you swimming and using the legs in a freestyle action, avoiding breast stroke as we feel the knee can do without too much aggravation.  Breast stroke will be re-introduced as you grow confident and we pass the 3 month mark.  Of course, on occasions we find patients who cannot swim and therefore alter the activity.  Expect to work your hips very hard in this phase and to begin closed chain balance work like the wobble board and bose ball


The prep phase is about adding load and with it impact.  Running may commence from around week 12 though some surgeons prefer 16 weeks, and everyone is different therefore if it is looking like 4 months – do not panic! you still have another 5 months to go.  It is not a race.  Getting the knee ready to run will require testing on the leg press to ensure the knee is strong enough to cope.  Once you are ready to run we start on the treadmill and build from here.  Expect everything to get more difficult at this phase.  Heavier weights, more challenging core and balance work will come into play.  There will be some quad aching and also the knee may ache over the patella/knee cap and patella tendon.


The pre-sport phase will require a discussion of the activity you want to return to.  If you are not playing in a team or multi directional sport, we will still aim to place you into the most challenging situations and stress your balance systems.  This generally starts in the prep phase and builds on the exercises.  We look towards 5 months to commence side stepping, turning and cutting.  Building speed, depth of angles and frequency of change as you gain confidence and strength.  The phase places ever increasing stress on the knee to ensure the quads and hamstrings are up to scratch.  Its important to consider that even though you have been doing months of exercise, the operated knee will still be weaker.  Sets and reps get tougher as we want to ensure the knee can tolerate the same pressures as the unoperated knee.


Pre-sport phase takes you from Month 7 to 12 and places you into the same phases and positions as you would experience in your chosen sport or activity.  We need to ensure you are up to the loading, cutting and change of direction as would be experienced in the match or chosen activity.

This phase is designed to expose any insecurities and vulnerabilities in a controlled environment.  We test you at each stage to ensure the knee is working optimally and refer you for cybex testing if we are at all concerned to ensure a smooth free transition.


Each phase is evidence based from peer review journals.  There is no fast way of getting the ACL to remodel any quicker and time is your best friend. 

We are highly skilled in the treatment of ACL reconstruction and work closely with the Reading Hip and Knee unit, plus surgeons from Basingstoke, Windsor and London.


Further Reading:

Anderson etal (2009) Treatment of ACL injury.. Arthroscopy 25 653-85

Arden (2014) 55% return to competitive sport following ACLr surgery…48 1543-1552

Dye (2005) The pathophysi of patellofemoral pain: .. Clin ortho related Res 436 100-110

Escamila (2012) ACL Strain and tensile force…… JOSPT 42 (3) 208-220

Filbay etal (2015) QoL in ACL-deficient individuals: a systematic review … BJSM 49 1033-1041

Glass (2010) The effects of open change Vs closed kinetic chain exercise… N Am JSPT 5 74-84

Grindem etal (2015) How does a combined preoperative.... BJSM 49 385-389

Hartigan (2013) Kinesiophobia…noncopers vs Potential Copers. JOSPT 43(11) 821-832.

Herrington etal (2013) Task based rehab protocol… PT in Sport 14 188-198

Imoto etal (2011) effectivness of electrical muscle stimulation…Sao Paulo MJ.129 414-23

Kim etal (2010) Effects of NMES after ACL.. JOSPT 40 383-391

Kyristis (2016) Likelihood of ACL rupture… BJSM 50: 946-951

Lobb (2012) A review of SRs on ACL reconstruction. Phys Th in Spt 13 270-8

Melik (2016) EB clinical practice update:…..BJSM 50 1506-1515

Willy & Meira (2016) Current concepts in biomechanical... IJSPT 11(6) 877-890