ACL: ANTERIOR CRUCIATE LIGAMENT

 The Injury

The Anterior Cruciate Ligament lies deep within the knee joint.

• Origin: Femur (thigh bone) 

• Insertion: Tibia (shin bone). 

• Function: prevents excessive forward movement of the shin in relation to the thigh and also to prevent excessive rotation at the knee joint. 

Because of the force that is required to damage the ACL it is not uncommon for other structures such as the meniscus or MCL to also be damaged. Above a moderate impact causes the LCL to rupture. A more violent impact causes the ACL to also rupture.

 Occurrence

The ACL can be injured in several different ways:

• Landing from a jump onto a bent knee then twisting or landing on a knee that is over-extended.

• In collision sports, direct contact of the knee from opponents can cause damage to the ACL. 

• At the moment of injury the person may experience a snapping sensation deep within the knee.

• Pain is proportional to the force and degree of damage to other structures within the knee joint.

• The athlete may feel able to continue playing, but the knee joint is unstable.

• After a few hours the knee joint will become painfully swollen due to what is called a hemarthrosis or bleeding within the joint.

• This swelling provides a protective function by not allowing the person to use their knee.

• Stress tests on the knee ligaments to measure the degree of laxity allows an estimate of the damage.

• Also, an MRI scan can be used to ascertain the level of knee injury.

• In some cases it may be necessary to survey the joint with an arthroscope.

• A partial tear with minimal instability, a conservative approach is to see a PT. This option is more likely for adolescents + sedentary people. 

• Surgical reconstruction is the surest way to restore normal function. An arthroscopic procedure is performed where a strip of the patella tendon or hamstring is removed and used as a graft to replace the ACL.

 Rehabilitation

A return to full activity in most cases occurs in less than 6 months. Early full range of motion is important. The following rehab program is only appropriate if the surgeon uses a bone patella tendon bone graft.
 

Stage 1: Pre-Operative

For patients having surgery or those who undergo a ‘conservative’ rehab program. In the long term, an unstable knee joint may lead to osteoarthritis. The aims during this stage are to: 

• Restore a normal gait pattern: Progressing from crutches to heel to toe walking.

• Reduce knee joint swelling principally through applying a cold compress to the knee joint.

• Improve range of flexion through heel sliding exercises and regain full range of extension

Stage 2: Week 1 following surgery

Reduce swelling with ice and restore range of motion through exercise.

• Early restoration of knee extension is most important.

• Static quad contractions are done every hour, to help decrease swelling and to start regaining strength.

• Use a continuous passive movement (CPM) machine that bends and straightens the knee, reducing swelling + restoration of ROM.

• Use crutches and a normal walking pattern is encouraged; when 70 degrees of knee flexion is possible, static cycling is initiated.

Stage 3: Concentrated Rehab - Weeks 1-12

Gains made during the 1st week after surgery is maintained.

• Range of motion exercises are continued until the patient has full knee extension and flexion.

• Crutches are discarded when the patient is walking normally and using stairs, both up and down.

• Continue stationary cycling and progress to the step machine.

• Quads and hamstring strengthening is progressed mainly through squatting exercises

• Enhance Proprioception - the sensation of joint movement and position, so crucial to sporting activity. 

Stage 4: Late Rehab - Weeks 13-20

Range of movement should now be normal during everyday activities. 

• Strengthening and proprioception exercises should be progressed and, once the operated knee has achieved 90% of the normal leg in these aspects, functional activities can be undertaken.

• Activities consist of sport-specific drills and movements, the intensity, frequency and duration of which should be gradually increased until normal function is achieved. 

Stage 5: Functional Rehab - Weeks 21+

When surgeon is satisfied knee has sufficient muscle strength, functional exercises begin:

• Jog 100 walk 50 (x 6); Jog 150 walk 50 (x 6); Jog 200 meters, walk 50 meters (x 8); Jog 200 walk 50 (x 12); Jog 2000m.

• When the player can jog without pain and can do plyometric drills the following exercises are performed with a 1 day rest:

• 25 mins: Run a 20m diameter figure-8 course placing a very gentle stress on the knee. The pace is walk, jog or half pace run.

• 20 repeats: Variable pace running with gradual turns. Run a straight 30m up to the 20m diameter semi-circle, around which he gently turns before completing another straight 30m run back to the finish. The pace is either a jog or ½ speed.

• 25 min: Variable pace running with slightly tighter turns. Run a 10m diameter figure-8. Walking, jogging, ½ or ¾ speed.

• 20 repeats: Variable pace running with gradual turns. The pace of the run is either three quarter or full pace.

• 20 repeats: Two 5m diameter circles 30m apart. Run at full pace

• 20 repeats: As Exercise 5, but single cones are used.

• 10 repeats: Six cones 5m apart in a straight line. Complete a shuttle run, at full pace, turning alternately to the left and right.