Anterior Cruciate Ligament (ACL) Injury

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Key words: anterior cruciate ligament + injury/treatment/characteristics/management

Definition/Description

Injuries to the ACL are relatively common knee injuries amongst athletes. They can range from mild such as small tears to severe when the ligament is completely torn. Both contact and non contact injuries occur allthough most common are non contact tears and ruptures.

Clinically Relevant Anatomy

The knee is being stabilized by 4 ligaments:

• Anterior cruciate ligament (ACL)
• Posterior cruciate ligament (PCL)
• Medial collateral ligament
• Lateral collateral ligament

The role of the ACL is to prevent forward movement of the tibia from underneath the femur. It is less thick than the PCL and thus more likely to be injured.

The ligament has a proximal attachment in the fossa on the postero-medial aspect of the lateral condyle of the femur and terminates distally on the tibial plateau in front of and lateral to the anterior tibial spine. The ACL has a multiple bundle structure which allows it to be functional at all knee angles. Two main aspects can be distinguished:

• Anteromedial part which is tight in knee flexion and lax in knee extension. It attaches on the proximal aspect of the femoral attachment and inserts on the anteromedial portion of the tibial insertion.
• Posterolateral band which is lax in flexion and tight in extension and partly prevents hyperextension. The fibers attach to the posterolateral aspect of the tibial attachment.
  

Mechanisms of injury / Pathological process

Three major types of ACL injuries are distinguished:

• Direct contact
• Indirect contact
• Non contact

Most common are the non contact injuries caused by forces generated within the athlete’s body while most other sport injuries involve a transfer of energy from a source external to the athlete’s body. A cut-and-plant movement is the typical mechanism that causes the ACL to tear: sudden change of direction or speed with the foot firmly planted. A direct impact to the front of the tibia or stiff-legged landing are other frequently reported causes. 

Women are three times more prone to have the ACL injured then men. A wider pelvis requieres the femur to angle toward the knee, lesser muscle strength gives less support to the knee and hormonal variations may alter the laxity of ligaments.

Characteristics/Clinical Presentation

• ­ 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 extension
• ­ Possible widespread mild tenderness
• ­ Tenderness at the medial side of the joint which may indicate cartilage injury
  

Differential Diagnosis

A torn ACL mostly does not occur isolated: over 50% of all ACL ruptures have associated meniscal injuries. If seen in combination with a medial meniscus tear and MCL injury, it is called O’Donohue’s triad. The same characteristics for an ACL injury can be found at knee dislocations and meniscal injuries. Other problems that have to be considered are patellar dislocation or fracture, and a femoral, tibial or fibular fracture. Differentiation can mostly be made based on a thorough anamnesis with particular attention for the mechanism at time of injury. An additional MRI scan can visualize the injury.

Diagnostic Procedures

• Lachman test
• Anterior drawer test
  

• Pivot shift 

Outcome Measures

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Examination

An organized, systematic physical examination is imperative when examining any joint. Immediately after the acute injury, the physical examination may be very limited due to apprehension and guarding by the patient. The basic examination should include the following:
The examiner should begin with inspection, looking for any gross effusion or bony abnormality. An immediate effusion indicates significant intra-articular trauma. According to Noyes et al, in the absence of bony trauma, an immediate effusion is believed to have a 72% correlation with an ACL injury of some degree. Assess the patient's range of motion (ROM), especially looking for lack of complete extension, secondary to a possible bucket-handle meniscus tear or associated loose fragment.Palpation of bony structures may suggest an associated tibial plateau fracture.Palpation of the joint lines to evaluate a possible associated meniscus tear. Palpation over the collateral ligaments to suggest any possible injury (sprain) of these structures. Up to 50% of ACL ruptures have associated meniscal injuries; acute injuries are likely to have associated injuries of the MCL and meniscus.
If the anterior drawer test is positive, it can be a sign that there is an ACL injury. The anterior drawer test is performed in 90° flexion of the knee. Swelling of the knee can make it impossible to make a flexion of the knee. Therefore we can also perform the Lachman test. This test is performed in 20-30° flexion of the knee. These tests are possibly positive if there is a hyper mobility of the joint. Sometimes it’s possible that there is another diagnosis, although the tests were positive. The doctors can also perform an MRI ( Magnetic Resonance Imaging ), that will make it easier to make the right diagnosis.

Medical Management

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Physical Therapy Management ( without / before surgery ) 

The first thing a person with an ACL-injury has to do is apply RICE. This stands for Rest, Ice, Compression and Elevation. In the therapy before an operation it is important to encourage strengthening of the quadriceps and hamstrings, as well as range of motion exercises. Performance of ROM will help the patient regain motion and strength.
Surgical treatment is usually advised in dealing with combined injuries (ACL tears in combination with other injuries in the knee). However, deciding against surgery is reasonable for select patients. Nonsurgical management of isolated ACL tears is likely to be successful or may be indicated in patients:
- With partial tears and no instability symptoms
- With complete tears and no symptoms of knee instability during low-demand sports who are willing to give up high-demand sports
- Who do light manual work or live sedentary lifestyles
- Whose growth plates are still open (children)

The surgery www.physio-pedia.com/index.php5

(after surgery)

The first phase is pre-operative. The intention is to reduce swelling,  pain and attempting full range of motion and to decrease joint effusion.^(9,11) It is done through compression, elevation, cryotherapy and electrical stimulation. It is suggested to build good quadriceps and hamstrings strength before surgery  if there’s no pain involved. ⁽⁹⁾   

The second phase is postoperative. First week after surgery, rehabilitation is mostly passive. Regular icing and elevation are used to reduce swelling. The goal is full extension and  70 degrees of flexion by the end of the first week.  After the operation the patient  must  wear a knee brace and use two crutches. In the 3-4 week after the operation the patient tries to genuinely increase the stance phase in an attempt to walk with one crutch. With good hamstring/quadriceps control. The use of crutches can be reduced earlier. After 4 weeks, we progressively decrease the using  of the knee brace. ^(9,11)

Multidirectional mobilizations of the patella should be included for at least 8 weeks. Other mobilization exercises are the passive extension of the knee (no hyperextension) and the passive and active mobilization in flexion direction. In the 0-4 week we can go from 0 to 110 degrees  of flexion and after 4 weeks we try to normalize the motility (no thorough flexion).⁽⁹⁾  

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From 0 to 4 weeks exercise for the calf muscle, hamstring and quadriceps (vastus medialis) can be performed. After 4 weeks hamstringstonifications, quadricepstonifications( vastus medialis)  in close chain exercises. In the immediate postoperative phase, there is no strength. The exercises should be started on light intensity (50% of maximum force) and progressively increased to 60-70%. The closed chain exercises should be built from less responsible positions (bike, leg presses, step) to more congested starting positions (ex.squad). The progress of the exercise depends on pain, swelling and quadriceps control. from 10 weeks: isokinetic exercise. ^(9,11)

Proprioception and coordination exercises start from  4-5 week if the general power is good. exercises on boards, toll, balance exercises. From the 10th week we can start with forward ,backward and lateral movements, dynamic exercises. ⁽⁹⁾

After 3 months we can move on to functional exercises. As going back running and jumping exercises. Also proprioceptive and coordination exercises become heavier, quicker changes in direction are possible. To stimulate coordination and control through afferent and efferent information processing, exercises should be enhanced by variation in visible input, surface stability (trampoline), speed of exercise performance, complexity of the task, resistance, one or two-legged performance, etc. ⁽⁹⁾

Finally in the 4-5 month  we maximize endurance and strength of the knee stabilizers, optimize neuromuscular control with plyometric exercises and  add the sport-specific exercises. We work on acceleration and deceleration, variations in running and turning and cutting maneuvers. This improves arthrokinetic reflexes to prevent new trauma during competition. ⁽¹¹⁾

Key Research

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Resources

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Clinical Bottom Line

To understand what an ACL-injury is you need to have knowledge of the anatomy. You have to kwnow where the ACL is located, why it’s important to the knee and what it does with the knee.

Recent Related Research (from Pubmed)

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References

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Evidence-based rehabilitation following anterior cruciate ligament reconstruction-S. van Grinsven, R. E. H. van Cingel, C. J. M. Holla, C. J. M. van Loon- Knee Surg Sports Traumatol Arthrosc 2010; 18:1128–1144 ⁽⁹⁾

Biomechanics of Knee Ligaments- Savio L-Y. Woo,* PhD, Richard E. Debski, PhD, John D. Withrow, Marsie A. Janaushek- The American Journal of Sports medicine 1999;27:533 ⁽¹⁰⁾

The Long-term Effect of 2 Postoperative Rehabilitation Programs After Anterior Cruciate Ligament Reconstruction A Randomized Controlled Clinical Trial With 2 Years of Follow-Up-May Arna Risberg,*† PT, PhD, Inger Holm- The American Journal of Sports medicine 2009; 37: 1958 ⁽¹¹⁾

Evaluation of the clinical signs of anterior cruciate ligament and meniscal injuries-Dhavalakumar K Jain, Rajkumar Amaravati, Gaurav Sharma- Indian J Orthop  2009; 43 : 375-378 ⁽¹²⁾

T.E. Hewett,S.J. Shultz,L.Y. Griffin, Understanding and Preventing Noncontact ACL Injuries (American Orthopaedic Society for Sports Medicine, United States of America,2007) ⁽¹³⁾

M. Kjaer, M.Krogsgaard, P.Magnusson, L.Engebretsen, H.Roos, T.Takala, S.L-Y Woo, Textbook of Sports Medicine (Blackwell Science, Hong Kong, 2003) ⁽¹⁴⁾

M. Darrow  , The knee Sourcebook (A Division of The McGraw-hill companies,United States of America,2007) ⁽¹⁵⁾

R. Putz, R. Pabst  , Sobotta atlas van de menselijke anatomie (Bon Stafleu Van Loghum,Houten/ Diegem,2002) ⁽¹⁶⁾