The Anterior Cruciate Ligament (ACL)

Introduction:

ACL stands for Anterior Cruciate ligament. It attaches to the area in front of the intercondylar eminence of the tibia it extends backwards and laterally, to attach to the posterior part of the inside of the lateral condyle of the femur.

Its primary role is to resist excessive anterior translation and medial rotation of the tibia, in relation to the femur.

The ligament is stretched or torn in 70% of all serious knee injuries (Tortora & Grabowski (2000).

It is more commonly torn in women than men. This is due to the fact that the ligament is smaller and less strong in females. There are muscular strength reasons, less strength means there isn’t as much muscular protection to the ligament and the increased elasticity in females means that there is more of a delay in hamstring firing, which will protect the ACL less. The other reason is that the skeletal alignment of women is different, with wider hips changing the angle at the knees.

How do you injure the ACL?

It is commonly done when rapidly decelerating, twisting/turning and landing from jumping.

The Anterior Cruciate ligament (ACL) can be compromised in isolated grade 3 Medial collateral ligament (MCL) injuries (Mazzocca et al 2003).

Commonly there is an audibly pop noise that is usually quite loud. The knee will swell up quickly due to the fact that the ACL bleeds.

How do you diagnose an ACL rupture?

Anterior draw & pivot shift tests are good at detecting an ACL rupture & Lachman test is best for ruling it out (Cleland & Koppenhaver 2011).

Or

An MRI scan is very good at detecting it.

Or

An arthroscopy (key hole)

What do I do in the first 48-72 hours?

Use: P.O.L.I.C.E.

This is the latest acronym that replaces the old R.I.C.E.

P: Protect the injury from further harm: This can be stopping the activity, using crutches, strapping it up, etc.

O.L: Optimal loading: This means load it but don’t overload it! This was put in place of rest because people were being too literal with rest and actually doing nothing, which is bad! So the key here is to move it, walk on it, etc. The key thing to remember is that as long as after doing the activity it is no worse for doing it, you are fine but if it is worse afterwards, then you have overloaded it.

I: Ice: This is to minimise the amount of swelling that gets to the injury site. You should wrap the ice in a damp tea towel and apply for 20 minutes.  The cooling effect should last for roughly 2 hours so you should re-apply it every 2 hours.

C: Compression: Now most people think that ice is the most important aspect but believe it or not it is actually compression. Compression helps control oedema formation & reduces swelling by promoting re-absorption (Knight 1995). Compression can take the form of tubi-grip or strapping and the aim is to create a back pressure that minimises the amount of swelling to the area. This is vital, as the more swelling you have, the more painful the injury will feel and the stiffer the area will become. It will inhibit muscle activity leading to muscle atrophy and it decreases proprioception. The other thing is that the more swelling there is, the longer it will take for your body to get rid of it.

E: Elevation: Basically keep the injury up as much as you can (in between your optimal loading etc.)

What about pain relief or anti-inflammatory's?

You should use pain relief as you require. For example if you are in so much pain that you aren’t moving the injury then you need to use pain relief.

On the anti-inflammatory front, take them for the first 48-72 hours or until the throbbing and heat reduce.

So I heard you can have surgery or just rehabilitate it. So what should I do?

Surgery:

ACL surgery has been around since the 1950s. Attempts to directly repair the ligament didn’t work because it is difficult to suture and the knee is difficult to adequately immobilise, which risks loosening the repair.

Due to this, surgeons started using tendons from other sites as grafts, to make a new ACL. These were structurally stronger than the damaged ACL and were the best option.

However using tendon comes with its own set of issues, new blood vessels and nerves have to grow into the graft, and structural changes occur within the fibres of the graft, before it works correctly as a ligament.

The graft is considered weakest at 6 to 12 weeks post-op but the whole process takes about a year, which is the reason that in the past, the rehabilitation process back to sport used to be 12 months.

In the mid-1980s they tried using grafts made of artificial materials such as Dacron or Gortex. This idea was to shorten the layoff time as the new graft was at maximum strength from day one.

Unfortunately the initial good results produced by artificial grafts were short-lived. The reason for this is longevity. The knee moves so much that within a year most of these grafts have disintegrated and leave debris in the joint that cause further issues.

Since this there have been many attempts to do this but all have failed so far.

Nowadays the methods typically used are:

Hamstring autografts:

They use the semitendinosus tendon either alone, or with the gracilis tendon for a stronger graft. The two tendons are commonly combined and referred to as a four strand hamstring graft, made by a 25 cm piece, which is removed from each tendon. They are folded and braided together to form a quadruple thickness strand for the replacement graft. The braided segment is threaded through the heads of tibia and femur and its ends fixated with screws on the opposite sides of the two bones.
84% of ACL reconstructions use hamstring grafts in Denmark & Sweden (Rahr-Wagner et al 2014). However, there is a 2 x greater risk of ACL reconstruction revision with the hamstring graft, which is 5.1% at 5 years (Persson et al 2014).  

Patellar tendon:

The graft is taken from the injured knee. The middle third of the tendon is used, with bone fragments removed on each end. The graft is then threaded through holes drilled in the tibia and femur, and finally screwed into place.

This method is becoming less common due to the following issues:

Increased wound pain.

Increased scar formation as compared to a hamstring tendon operation.

Risk of fracturing the patella during harvesting of the graft.

Increased risk of tendinopathy.

However, Patella tendon reconstructions are statically more stable (Mohtadi et al 2011). The revision rate is 2.1% for patellar tendon grafts, which is better than hamstring grafts (Persson et al 2014).

Synthetic Grafts:

There are some synthetic reconstructions but as yet it is early days, but watch this space.

The non-surgical option:

There is limited return to sporting activity after ACL Anterior Cruciate Ligament rupture with or without surgery (Ardern et al 2011). Sorry but it’s true, don’t think it’s a 100% with or without surgery.

The key is, that once the knee is settled down with swelling and has full movement you should try rehabilitating it first and if it’s not progressing then that is the time to have the surgery. The reality is the evidence finds that an early ACL reconstruction didn't provide better results at five years than rehab with the option of having it later (Frobell et al 2013). So you might as well try the non-surgery route first. Plus it has been found that Anterior Cruciate Ligament (ACL) rehabilitation may prevent 61% of surgeries after ACL rupture (Khan 2010). So it works!

If you’re worried about wasting your time rehabilitating it for months and only to have the surgery in the end, then don’t worry as this study supports prehabilitation as a consideration for patients awaiting ACL reconstruction (Shaarani et al 2013). Basically the strength and stability that you will have developed before surgery will help you post operatively.

So what is the ACL rehab if you don’t have the surgery?

Basically it is similar to the ACL reconstruction protocols but without some of the restrictions on range of movement that you typically get with the protocols, especially in the early stages.

So if I have surgery what do I do?

Basically this currently depends on the surgeon and there are protocols to follow as a guide. This said a lot of these protocols haven’t changed too much over the years but the evidence has.

Here is a typical patella tendon graft protocol:

Post-Operative Positioning:

Compression dressing, ice to knee.

Immobiliser with knee in straight (0 degrees) extension (the struts for the immobiliser should be bent out into a position of relative knee hyperextension, which generally keeps a knee with a postop dressing in full extension).

Knee elevation.

Immediate quad sets; ankle pumps encouraged.

(if in doubt contact surgeon)

Postoperative Day One:

No pillow under knee at any time for first six weeks. Pillows should always support foot/ankle while in bed.

Out of bed.

Quad sets - 30 reps, 3-5 times daily. Five quads hard for 6 seconds. Relax for 3 seconds. Repeat.

Ankle pumps every hour.

Protected weight bearing with crutches to tolerance.

Dressing changes prior to hospital discharge.

Obtain full passive extension (0 degrees) out of immobiliser (essential).

Achieve 90 degrees of flexion.

Protected weight bearing as tolerated (WBAT) with crutches.

Exercises (out of immobiliser):

Quad sets.

Active assisted knee flexion (sitting).

Hamstring stretches.

Passive extension to 0 degrees.

Standing hamstring curls.

Discharge Protocol:

Gait-weight bear as tolerated with crutches.

Exercises (out-of-brace):

Flexion Exercises (4 times daily):

Active assisted knee flexion (sitting) to > 90 degrees (as tolerated).

Sitting/standing hip flexion.

Standing hamstring curls.

Extension exercises:

Quadriceps stretch to achieve full passive extension (frequently).

Quad sets (10 sets of 30 daily).

Straight leg raises (obtain full extension): 10 sets of 30 daily. No sag of the knee should be present.

Hamstring stretches (hourly).

Crutch Ambulation Protocol (verify with surgeon for each case):

Weight bear as tolerated (protected) with crutches for 2 weeks.

After two weeks, may progress to one crutch (on opposite side) once quadriceps function and gait mechanics are normal.

Discontinue one crutch once gait mechanics are normal (no limping).

Postoperative Two to Six Weeks:

Goals:

Top priority - obtain full (0 degrees) knee extension.

Increase knee range of motion.

Increase quadriceps strength in preparation for progression to ambulation without use of crutches.

.

Exercise Program:

Continue knee immobilizer at full extension. Decrease use as comfortable (important - verify with surgeon). May ambulate without knee brace (with crutches) once quadriceps able to fire well to support operative knee.

Flexion Exercises:

Active assisted knee flexion (with overpressure - goal is 130 degrees).

Biking as tolerated to 30 minutes (low resistance).

First two weeks of exercise bike backwards (no resistance).

Progressive Resistance Exercises: (30-50 repetitions light resistance only, 3 times/day).

Straight leg raises (maintain full extension).

Hamstring curls.

Hip flexion, extension, abduction.

* If any of these exercises seem to aggravate the knee (swelling, pain, or tenderness), then that specific exercise which causes the difficulty should be postponed until you have discussed the effects of the exercise with the physio.

Postoperative Seven to Twelve Weeks:

Goals:

Achieve full extension to near full flexion.

Improve quadriceps tone (return of VMO definition).

Exercise Program:

Quadriceps - straight leg raises (10 sets of 30 repetitions each), and quads setting (10 sets of 30 repetitions each).

Hip muscle groups. May progress by adding weights above the knee.

Hip abductors, flexors, abductors, extensors (10 repetitions, 4 sets daily).

An isometric variation can be performed by pushing down on the hip being worked on and sustaining a contraction for 10 seconds.

Hamstrings curls - may add weights around the ankle (10 repetitions, 4 times daily). Calf raises. 3 sets, 10 repetitions - fast and slow sets (each).

Swimming. Flutter kick only - gentle. No whip kick.

May begin outdoor biking program - avoid hills. A good rule of thumb for those interested in returning to athletics is that you need three minutes of biking to substitute for one minute of running.

Accelerated program - start with sand bags on tibial tubercle. Perform straight leg raises (10 sets, 10 repetitions each) and progress fulcrum distally one inch per week).

Walking (level ground). Build up pace gradually. Feel big toe of affected foot push off as you walk to ensure normal gait pattern. Start off at one mile at brisk pace, increase to three miles. No limping allowed.

Mini squats: Stand facing the edge of a door and place hands on the door knobs on each side of the door. Feet should be shoulder width apart. Perform a half-squat (never past 90 degrees) and slowly raise to a starting position. Build up to 100 repetitions per day.

Postoperative 12-16 Weeks:

Goals:

Full knee range of motion. Refer back to surgeon for extension restriction of 5 degrees or if less than 110 degrees flexion.

Normal gait pattern.

Progressively increasing functional strengthening program.

Exercises:

Continue with exercise program from week 7-12.

Weight room activities:

Leg press - press body weight as many times as possible on nonsurgical side (to fatigue). Follow same sequence on surgical side.

Squat rack - half squats (not past 70 degrees) at one-half body weight, 10 repetitions; progress to full body weight as tolerated.

Continue biking and/or swimming on a daily basis. No whip kicks.

Agility workouts:

Balancing on a wobble board.

Figure of 8’s (20 to 30 yard diameter circles).

Backward jog.

Half speed jog (level surfaces only). Initially alternate 100 yards, walking/jogging over one mile.

Build up to one mile by 16 weeks postoperative.

Postoperative Four Months - Six Months:

Goals:

Improve quadriceps strength/function.

Improve endurance.

Improve coordination/proprioception.

Exercises:

Jogging - (level surfaces) - 15 minutes at 8-10 minutes/mile pace. Add 5 minutes per week.

Perform daily.

Biking - by now the amount of set resistance should be increasing. Perform daily at 20 minutes/day. Legs should feel drained once off the bike.

Step-ups - face the step. Put foot of operative knee on step and step up on the step. Repeat with gradual build up in repetitions until doing 100 step-ups/day. Try to lower from the step twice as long as it takes to raise up on the step.

Agility Drills:

Figure 8’s - daily - 5 minutes half-speed - tighten circle size down.

Shuttle runs daily - 5 minutes - half-speed - repeat 10-12 repetitions.

Zig-zag running - angle across a distance of 10-15 yards, then angle back across field to another boundary 10-15 yards apart. Continue for 100 yards. Tighten up as strength/endurance permits.

Sports on Own:

Football: Light kicking, heading, drills (no fast sharp pivoting).

Basketball - shooting baskets only.

Recreational tennis (no sharp pivoting).

Golf (9-holes, avoid fatigue).

Postoperative Full Rehabilitation:

No competitive or pivot sports until cleared by surgeon.

Quadriceps/thigh circumference should be within 1 cm of nonoperative (if normal) side.

Weekly strengthening program - independently (2-3 times/week):

Full speed jog/run - 20-30 minutes - 6-7 minutes/mile or best pace.

Exercise stationary bike - increasing resistance, set bike so low leg is flexed no more than 10-15 degrees, 20 minutes.

Agility drills (figure 8’s, shuttle runs, turns), wobble board balancing.

Continue quad sets, SLR’s (300 repetitions/day).

Hills/stairs - running up hills and up stairs can be utilised to help build muscle mass and strength. Care should be taken running downhill and down steps. This can irritate the knee and should be one of the last exercises added to the workout program.

So as you can see it is very specific, with lots of restrictions and timing etc.

Do we need all of these restrictions?

What is different from current evidence compared to the protocols?

Weight bearing:

Immediate weight bearing post anterior cruciate ligament reconstruction is safe & helps to increase quadriceps muscle activity, to build muscle strength (Tyler et al 1998) & (Kruse et al 2012).

Safe range of movement allowed:

0°-90° flexion of the knee is safe & performing closed-chain strengthening exercises has been found safe also (Kruse et al 2012). This flexion is usually limited in open chain activites but the evidence suggests that it is safe.

Eccentric quads strengthening & isokinetic hamstring muscle strengthening are safe 3 weeks post-op  (Kruse et al 2012). Typically there is no mention of eccentric exercises in ACL protocols but you can do it. Obviously the isokinetic exercise won’t be possible for most people as the machine is not available.

Neuromuscular electrical stimulation:

Intensive neuromuscular electrical stimulation combined with standard rehab is effective at accelerating recovery after knee surgery (Feil et al 2011). So if available using muscle stimulation helps to enhance the rehabilitation effects so is worth using.

Bracing?

There is no long term benefit to using a knee brace post-op Anterior Cruciate Ligament (ACL) reconstruction (Smith & Davies 2008).

Bracing does not provide any benefit & is not necessary in ACL rehabilitation (Kruse et al 2012).

This is different to some protocols as some still include bracing in the early stages.

Overall my advice is to follow the protocol for now but maybe in the future this evidence will alter what you can do and will accelerate the rehabilitation time.

What is the chance of future problems following an ACL rupture?

An Anterior cruciate ligament (ACL) reconstruction has a 5 to 15% chance of re-rupture and is at most risk between week 6 and 12.

Anterior Cruciate Ligament (ACL) injuries are associated with arthritis, whether you have a reconstruction or not (Myklebust & Bahr 2005).

If I have never injured my ACL can I prevent the chance of rupturing it?

Evidence suggests that 50% of primary Anterior Cruciate Ligament (ACL) injuries can be prevented (Kahn 2010).

Neuromuscular and educational interventions appear to reduce the incidence rate of ACL injuries by approximately 50% (Gagnier et al 2013).

Moderate evidence found stretching, proprioception, strength, plyometric & agility drills decrease ACL injury chance (Stojanovic & Ostojic 2012).

FIFA have even devised something to help to prevent ACL injury:

The “FIFA 11+ ” is a complete warm-up programme to reduce injuries among male & female football players aged 14 years & over.

Now you must take this with a pinch of salt as FIFA did their own research so it may be a bit biased on the claims they make but generally it makes sense and should help to prevent. They say that the FIFA 11+ done at least twice a week resulted in 30-50% fewer injured football players!

So what is it?

The “11+” has three parts with a total of 15 exercises, which should be performed in the specified sequence at the start of each training session. A key point in the programme is to use the proper technique during all of the exercises. Pay full attention to correct posture and good body control, including straight leg alignment, knee-over-toe position and soft landings.

Part 1: running exercises at a slow speed combined with active stretching and controlled partner contacts;

Part 2: six sets of exercises, focusing on core and leg strength, balance, and plyometrics/agility, each with three levels of increasing difficulty;

Part 3: running exercises at moderate/high speed combined with planting/cutting movements.

If you would like to see the real thing then it can be found here:

Here is the FIFA 11+ manual of warm-up exercises: http://f-marc.com/11plus/manual/

Obviously everybody is different and ideally should be assessed and screened to highlight their individual issues that increase their risk of injury. From this you can work out what to work on to lower your risk.

If you need any further information or would like to book an appointment then call Hawkes Physiotherapy on 01782 771861 or 07866195914

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