Sunday, April 10, 2011

Torn Anterior Cruciate Ligament / ACL Knee Injury

Torn Anterior Cruciate Ligament / ACL Knee Injury

 
What is an ACL injury?
A torn ACL is an injury or tear to the anterior cruciate ligament (ACL). The ACL is one of the four main stabilising ligaments of the knee, the others being the Posterior Cruciate Ligament (PCL), Medial Collateral Ligament (MCL) and Lateral Collateral Ligament (LCL). The ACL attaches to the knee end of the Femur (thigh bone), at the back of the joint and passes down through the knee joint to the front of the flat upper surface of the Tibia (shin bone).


It passes across the knee joint in a diagonal direction and with the PCL passing in the opposite direction, forms a cross shape, hence the name cruciate ligaments.
The role of the Anterior Cruciate Ligament is to prevent forward movement of the Tibia from underneath the femur. The Posterior Cruciate Ligament prevents movement of the Tibia in a backwards direction. Together these two ligaments are vitally important to the stability of the knee joint, especially in contact sports and those that involve fast changes in direction and twisting and pivoting movements. Therefore a torn ACL has serious implications for the stability and function of the knee joint.
How does a torn ACL occur?
A torn ACL or acl injury is a relatively common knee injury amongst sports people. A torn ACL usually occurs through a twisting force being applied to the knee whilst the foot is firmly planted on the ground or upon landing. A torn ACL can also result from a direct blow to the knee, usually the outside, as may occur during a football or rugby tackle. This injury is sometimes seen in combination with a medial meniscus tear and MCL injury, which is termed O’Donohue’s triad.
Anterior cruciate ligament injuries are more frequent in females with between 2 and 8 times more females suffering a rupture than males, depending on the sport involved and the literature reviewed. The reason for this is as yet unknown, however areas of current research include anatomical differences; the effect of oestrogen on the ACL and differences in muscle balance in males and females.

Symptoms of a torn ACL
There may be an audible pop or crack at the time of injury
A feeling of initial instability, may be masked later by extensive swelling.
A torn ACL is extremely painful, in particular immediately after sustaining the injury.
Swelling of the knee, usually immediate and extensive, but can be minimal or delayed.
Restricted movement, especially an inability to fully straighten the leg
Possible widespread mild tenderness
Positive signs in the anterior drawer test and Lachman's test (see assessment).
Tenderness at the medial side of the joint which may indicate cartilage injury.
Treatment for an Anterior Cruciate Rupture
What can the athlete do?
Immediately stop play or competition
Apply RICE (Rest, Ice, Compression, Elevation) to the knee immediately
Seek medical attention as soon as possible.
What can a Professional do?
A Doctor or Sports Injury Professional can assess the knee joint to confirm a torn ACL
Diagnose any additional injuries
If unsure you may be sent for an MRI scan or X-ray
Refer for ACL Surgery if required
Provide a pre-surgery rehabilitation program in order to strengthen the knee and reduce the swelling in preparation for surgery. This will help produce the best results following surgery.
What does surgery involve?
Surgery involves either repairing or reconstructing the torn ACL. With a repair, the exisiting damaged ligament is sutured (stitched) if the tear is in the middle. If the ligament has detached from the bone (avulsed) then the bony fragment is reattached.
Surgical reconstruction of the torn ACL is performed using either an extraarticular technique (taking a structure that lies outside the joint capsule such as a portion of the hamstring tendon) or an intraarticular technique (using a structure from within the knee such as part of the patellar tendon) which will replace the anterior cruciate ligament.
When is Surgery Required?
Surgery is performed more often than not following Anterior Cruciate ligament tears
The decision on whether to operate is based on a number of factors, including the athletes age; lifestyle; sporting involvement; occupation; degree of knee instability and any other associated injuries
Older people who are less active and perhaps injured their ACL following a fall as opposed to during sport would be unlikely to undergo surgery
A younger, fit person who regularly plays sport and would be more likely to adhere to a complex rehabilitation program is very likely to be offered surgery
How long will the athlete with a torn ACL be out of action?
This largely depends on your surgeon or physiotherapists approach to rehabilitation. Some therapists advocate an accelerated rehabilitation programme returning the athlete to full competition within 6 months, others prefer a 9 month rehabilitation period.
More information on rehabilitation of an acl knee injury can be see on our anterior cruciate ligament rehabilitation page.
Which types of knee brace are available?
A knee support or knee brace provides protection and support. They prevent injury to healthy joints and support unstable joints.
Hinged Knee Braces
A hinged knee brace is likely to provide the best support for the knee and contains metal reinforcements in the sides which are connected by a hinge in the middle. Some knee braces use a geared hinge system in the middle which means the pivot point of the support moves as the knee bends (because the pivot point of the knee changes as it bends) providing a more snug fit.
This provides excellent lateral support to protect the medial and lateral ligaments and knee joint in general. No support can guarantee protection to the anterior cruciate ligament as it only requires just a few degrees of twisting to damage it.
Stabilized Knee Supports
A stabilized knee support has reinforced side panels to provide extra support over the standard knee support - again helping to provent sideways stress on the knee ligaments. Stabilized knee supports may have flexible steel springs sewn into the material at the side or may have elastic straps which wrap around the side for additional support.
Stabilized knee supports will provide less lateral support for the knee joint but will often be less bulky than a full hinged knee support.
Basic Knee Supports
A simple neoprene heat retainer will not usually have any additional springs, stays or supports. Some are open patella and have a hole for the patella to fit through. This can decreases the pressure on the kneecap or patella. A padded knee support will be closed and have additional padding over the patella to protect from knocks or minor impact as well as pressure from the ground when kneeling for long periods or landing on the knees for example in volleyball.
These will provide only very moderate support and are not usually sufficient to provide protection to joints where ligament injury has occured or is a risk.
More information on rehabilitation, stretching and mobility, strengthening is available to subscribers.

There are two main tests which are used to assess the knee to determine if there has been damage to the anterior cruciate ligament. The following tests should only be conducted by a qualified professional.

Anterior draw test
With the patient laying on their back with the injured knee bent to 90 degrees and the foot flat on the table
The practitioner may stabilise the foot by sitting on it
The practitioner will grasp the upper Tibia (shin bone) with both hands
They will then attempt to pull the Tibia forwards, towards them
A positive result is if the Tibia moves excessively forwards
The injured knee should always be compared to the healthy knee for 'normal' movement
Lachmans test
The patient lies on their back with the knee flexed between 15 and 30 degrees
The practitioner grips the outside of the lower Femur (thigh) with the upper hand and the inside of the upper Tibia with the lower hand
The Femur is stabilised with the upper hand as the lower hand applies an anterior force on the Tibia
A positive results is found if the Tibia moves excessively forward compared to the healthy knee

As well as the tests described above, the practitioner may also:
Test the range of motion at the joint
Test the strength of the surrounding muscles
Test for associated injuries such as meniscus tears


http://www.sportsinjuryclinic.net/gallery/knee/anterior_cruciate_injury.jpg

No comments:

Post a Comment