ACL Injury

What does ACL stand for?

ACL stands for Anterior Cruciate Ligament.

What is the ACL?

The anterior cruciate ligament is one of the four main ligaments that help stabilise the knee and prevent excessive movement of the thigh bone (femur) on the shin bone (tibia).

The ACL connects the femur to the tibia.

The simplest way to understand the function of the ACL is that it stops the shinbone moving forward from the thighbone and pivoting. This is known as preventing anterior draw and pivot shift.

There is no difference between ACL tear, rupture or injury. The terms are interchangeable.

How common are ACL injuries?

There are approximately 30 to 40,000 ACL injuries in the UK per year.

Injuries are more common in:

1. people who do pivoting sports,
2. in hyperlax, hypermobile or loose jointed people
3. in people have injured the ACL on one side with subsequent injury to the other knee.

What happens when the ACL doesn’t work or is torn?

When the injury happens, there may be a snap heard, the knee can swell up immediately and usually it is not possible to continue with the sport.

Gradually the swelling and pain can settle.

Over time, the knee can feel and unstable and give way particularly when twisting or pivoting or landing from a jumping movement.

Other symptoms include persistent swelling, pain around the knee or restriction of movement in the knee.

How is an ACL injury diagnosed?

Mr Gupté will assess your knee with a full history of the injury, which symptoms you are suffering and with a full clinical examination.

Examination of the knee will include:

• Areas of pain and tenderness.
• Whether the knee is swollen.
• Assessing the range of movement in the knee, in particular extension and bending.

There are specific tests done to assess whether the knee is loose because the ACL is injured:

• Lachman’s test.
• Anterior draw.
• Pivot shift: this is usually done only at surgery

Can you diagnose an ACL tear with a Xray?

You cannot diagnose an ACL tear on X ray because the ACL is a soft tissue and only bony injuries can be reliably diagnosed on X ray.

Will I need an MRI scan to diagnose my ACL injury?

Clinical examination usually provides a good idea of whether the ACL is injured. However any suspicion of ACL injury should be investigated further with an MRI scan.

The MRI will not only assess whether the ACL itself is injured, but whether other structures such as the meniscal cartilages or other ligaments are injured.

Mr Gupté’s team will endeavour to try to arrange the MRI for the same day or the day after consultation.

The fibres of a torn ACL do not pass smoothly between the femur (thigh bone) and tibia (shin bone).

On some scan sequences, there is swelling and fluid in the substance of the ACL

In very old (years old) ACL injuries, the ACL may be absent altogether.

Can other structures be damaged as well as the ACL?

The energy of any injury to the knee can pass through many structures in addition to the anterior cruciate ligament.

When the energy passes through the structures, they can get torn, bruised or damaged.

ACL injuries can be associated with:

• Injuries to the medial and lateral meniscal meniscus cartilages
• Injuries to other ligaments including the medial collateral ligament, lateral collateral ligament, posterior cruciate ligament and posterolateral corner.
• Bruising or fractures to the bone.
• A particular bruise that occurs on the shinbone and thighbone is known as the pivot shift lesion.
• Less commonly, the kneecap can also dislocate at the time of ACL injury.

There are many factors that determine whether patients will opt for surgery for their ACL tear.

These include:

• The level of instability in the knee and which other structures are injured.
• Whether physiotherapy has already been tried and not improve symptoms
• Desire to return to impact, twisting and contact Sports.
• Personal patient preference.

Other factors that affect surgical risk including body mass index, systemic disease or other joints being injured.

Mr Gupte will discuss all of these factors with you and come to a personalised assessment of risks and benefits of surgical versus Conservative management.

If you are considering on ACL reconstruction surgery, this will involve replacing the injured ACL with a piece of tendon (graft) from somewhere else, usually from the same knee. Regrettably, the majority of ACL tears cannot be effectively repaired, necessitating a reconstruction surgery with a graft to restore stability to the knee.

A lateral tenodesis is a modification of a very old ACL reconstruction technique know as the “Macintosh technique”. Mr Gupte was involved in the research team at Imperial College London that helped in the development of this technique from 2010. The technique involves taking a piece of tissue on that ins already present in the outside (lateral side) of the knee called the iliotibial band. A strip of this tissue is passed underneath the lateral collateral ligament and tethered to the thigh bone (femur) on the outside of the knee: proximal and posterior to the lateral epicondyle.

The biomechanics studies that took place at Imperial and other centres suggested that this technique reduces the stress on the ACL graft especially in the pivoting phase of movement such as during sharp turns and decelerating movements in sport.

Although not all surgeons employ the lateral tenodesis reinforcement technique, several studies have shown a lower re-rupture rate of ACL graft after return to sports in certain patient groups after lateral tenodesis.

Mr Gupte utilises the “modified Lemaire” technique of lateral tenodesis.

Lateral tenodesis operation to “reinforce” ACL graft: modified Lemaire technique.

You can download the full ACL rehab protocol here.

It is absolutely essential for a well supervised physiotherapy regime following ACL reconstruction surgery.

Physiotherapy for ACL rehab consists of:

• swelling management with ice and massage
• regaining range of movement with extension and flexion exercises
• strength and conditioning
• balance and conditioning
• rehearsing sporting movements specific for the sport

These techniques are used in different proportions at different times with good communication between physio, patient and surgeon.

What are the different phases of ACL rehab?

ACL rehab can be thought of as moving through five gears in overlapping stages:

First gear:
Recovery from the operation for two weeks: this involves a combination of pain management, swelling reduction with ice and elevation, assisted weight-bearing with crutches and can sometimes involve a brace.

Second gear:
Beginning physiotherapy in week 2 to 4: this stage can last 1 to 2 months and involves a combination of range of movement exercises quadriceps activation patella mobilisations and a gradual return to normal walking, aiming to discard crutches between week four and week eight.

Third gear:
Focus on muscle strength and conditioning together with cardiovascular fitness. This is often low impact range of movement exercises such as cycling swimming freestyle but not breaststroke, and crosstraining. During this time it’s important to engage with the physiotherapist to work out a program for muscle strength and conditioning with both resistance and non-resistance .

All strengthening should be balanced with a combination of stretches and massage.

Fourth gear (month 4-8):
This involves a return to impact activities such as gentle jogging or jumping.

It is best to have a assessment with Mr Gupté and the physiotherapist to ensure that your muscles are in good condition for impact activities to begin.

Start with straight straight line jogging on flat ground.

Patients can experience anterior knee pain at the front of their knee when they first start jogging as their kneecap and patella tendon have not been used to the impact for a number of months.

This can progress to pivoting and hopping activities from front to back and side to side as muscle strength allows.

Fifth gear (months 9 to 12):
A gradual return to sport in a graded manner. It’s best to return to sport after Mr Gupta and your physiotherapist have cleared your muscle strength and conditioning to be sufficient for pivot sporting activities to take place.

The return to sport is slightly longer in children than adults.

Typically, return to soccer or skiing is not recommended until at least nine months post operation and sometimes between 12 and 14 months post operation in children.