ACL Reconstruction

Anterior Cruciate Ligament Reconstruction

Patient information and Rehabilitation Guidelines

This section provides a summary of information relating to injury to the Anterior Cruciate Ligament, covering what it is, how it is injured and how it is reconstructed. A summary is given of the rehabilitation plan with its stages right up to returning to sport.

Full detail is contained in the rehabilitation and information booklet obtainable from Mr Spalding.

Please select the arrow on the left menu for topics in this section.
Attachment – Consent Form Information Sheet: download

ACL reconstruction

ACL Introduction

The anterior cruciate ligament (ACL) is one of the main restraining ligaments in the knee. It runs through the centre of the knee, from the back of the femur (thigh bone) to the front of the tibia (shin bone), and it acts as a link mechanism between the thigh and lower leg.

The main function of the ACL is to stabilise the knee, especially during rotation, sidestepping, and pivoting movements.

This means that when the ACL is ruptured or torn, the tibia moves abnormally on the femur and comes out of joint, and the knee buckles. The main feeling is a sense of the knee giving way during twisting or pivoting movements, and a sense of not trusting the knee when turning.

It is usual to be able to return to walking and straight line running following a torn ACL but to not trust the knee on rough ground or twisting movements. All too often the diagnosis can be delayed because the knee may recover for straight line activities, giving a false sense of security, but there is no control when returning to pivoting sports.

And when the knee gives way, there is a risk of further damaging the other key structures in the knee – hence the importance of preventing re-injury by making an early diagnosis.

Mechanism of Injury

Typically, the ACL is injured in a non-contact, twisting movement involving rapid deceleration on the leg, or a sudden change of direction, such as during side stepping, pivoting or landing from a jump . Injuries are often associated with a popping sensation followed by swelling in the knee over the next few hours due to bleeding from the torn ligament.


Typical scenarios include a footballer or rugby player who catches his foot in the ground as he tries to change direction, a netball player who jumps and lands awkwardly twisting on their bent knee with their foot out to the side, and a skier who catches the ski at slow speed and twists their leg out to the side.

There are many other scenarios of course and depending on the exact mechanism it is also possible to damage the joint surfaces (articular cartilage), or the meniscus (footballer’s cartilage).

ACL Diagnosis

Injury to the ACL is diagnosed by detecting an increase in the forward movement of the tibia in relation to the femur. Normally such movement is prevented by the ACL. The examining doctor gently grasps the tibia and the femur and tries to detect the increased movement. acl-diagnosis

Another of the tests is the Pivot Shift test which gently reproduces the giving way sensation as the knee is slowly bent. Done carefully these are painless tests and can accurately diagnose a torn ligament.

ACL diagnosis

Often the diagnosis can be made from the story – a pivoting twisting movement associated with a pop sensation and the feeling of immediately not trusting the knee. Others nearby may have heard a pop and thought the leg was broken. Early swelling is common and it is not usually possible to carry on playing – and any attempt to do so often results in the knee giving way again.