Anterior Cruciate Ligament (ACL) Injury

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Definition/Description[edit | edit source]

Injuries to the ACL are relatively common knee injuries amongst athletes.[1] 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[edit | edit source]

The knee is being stabilized by 4 ligaments:

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. [2][3]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[edit | edit source]

Three major types of ACL injuries are distinguished:[4]

  • 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.[5] 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.[6][7]

Characteristics/Clinical Presentation[1][edit | edit source]

  • ­ 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

Associated Injuries[edit | edit source]

Meniscal Lesions[edit | edit source]

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.[1]

Medial Collateral Ligament Injuries[edit | edit source]


Bone Contusions and Microfractures[edit | edit source]

Subcortical trabecular bone injury (bone bruise) may occur due to the pressures exerted on the knee in traumatic injury and are especially associated with ACL rupture.  Associated injuries of the menisci and the MCL tended to increaset he progression of bone contusion[8]. The focal signal abnormalities in subchondral bone marrow seen on MRI (undetectable on rdiographs) are thought to represent microtrabecular fractures, haemorrhage and oedema without disruption of adjacent cortices or articular cartilage.[9]  Bone contusions may occur in isolation to ligamentous or meniscal injury.[10]

Occult bony lesions have been reported in 84-98% of the patients with ACL rupture.[8][11][12] The majortiy of these have lesions of the lateral compartment[13], involving either the lateral femoral condyle, the lateral tibial plateau, or both.  The boney bruising itself is unlikely to cause pain or reduced function.[14]  Although the majority of bony lesions resolve, permanent alterations may remain. There is confusion in the literature as to how long these bony lesions remain hoever it has been reported that they can persist on MRI for years[15]. Rehabilitation and the long-term prognosis may be affected in those patients with extensive bony and associated articular cartilage injuries.  In the case of severe bone bruising it has been recommended to delay return to full weightbearing status to prevent further collapse of subchondral bone and further aggravation of articular cartilage injury.[15]

Chondral Injury[edit | edit source]

Hollis et al suggested that all patients following traumatic ACL disruption sustained a chondral injury at the time of initial impact with subsequent longitudinal chondral degradation in compartments unaffected by the initial bone contusion a process that is accelerated at 5 to 7 years’ follow-up[16].

Tibial Fractures[edit | edit source]

Posterolateral Corner Injury[edit | edit source]

Popliteal Cyst[edit | edit source]

Diagnostic Procedures[edit | edit source]

Differential Diagnosis[edit | edit source]

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 examination with particular attention for the mechanism at time of injury. An additional MRI scan can visualize the injury.

Can you spot the ACL and associated injuries in the MRI below?

Examination[edit | edit source]

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.

While inspecting, the examiner should look 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. Bony abnormality may suggest an associated fracture of the tibial plateau.

Assessing the patient’s range of motion (ROM) should be carried out to look for lack of complete extension, secondary to a possible bucket-handle meniscus tear or associated loose fragment. Palpation of joint lines and collateral ligaments can rule out a possible associated meniscus tear or sprained ligaments.

Medical Management
[edit | edit source]

Immediately after the trauma, the RICE principle should be applied.

Conservative treatment of isolated ACL tears (including physiotherapy and use of a knee brace) can have good outcome and may be indicated in patients:[17][18]

  • 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)

Surgical treatment is usually advised in dealing with combined injuries and for patients who frequently participate in high demand sports activities.

Physical Therapy Management
[edit | edit source]

Before surgery[edit | edit source]

RICE and electrotherapy can be applied during several weeks ahead of the surgery in order to reduce swelling and pain, to attempt full range of motion and to decrease joint effusion. This will help the patient to regain better motion and strentgh after the surgery.[19]

Therapy pre-ops can encourage strengthening of the quadriceps and hamstrings. Range of motion exercises should be included if there is no pain involved.[20][21]

NMES combined with exercise is more effective in improving quadriceps strength than exercise alone[22].

After Surgery[edit | edit source]

See Anterior Cruciate Ligament Rehabilitation

Prevention[edit | edit source]

Key Research[edit | edit source]

add links and reviews of high quality evidence here (case studies should be added on new pages using the case study template)

Resources
[edit | edit source]

add appropriate resources here

Clinical Bottom Line[edit | edit source]

In order to provide the injured athlete with the best care, physiotherapists should have elaborate knowledge of anatomy and functioning of the ACL.

Recent Related Research (from Pubmed)
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References[edit | edit source]

  1. ↑ 1.0 1.1 1.2 Yasuharu Nagano, Hirofumi Ida, Masami Akai, Toru Fukubayashi. Biomechanical characteristics of the knee joint in female athletes during tasks associated with anterior cruciate ligament injury. Knee 2009; 16(2): 153-158
  2. ↑ 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
  3. ↑ R. Putz, R. Pabst. Sobotta atlas van de menselijke anatomie. Bon Stafleu Van Loghum. Houten/Diegem. 2002
  4. ↑ T.E. Hewett,S.J. Shultz,L.Y. Griffin, Understanding and Preventing Noncontact ACL Injuries. American Orthopaedic Society for Sports Medicine. 2007
  5. ↑ M. Darrow. The knee Sourcebook. The McGraw-Hill Companies. USA. 2007
  6. ↑ McLean SG, Huang X, van den Bogert AJ (2005). "Association between lower extremity posture at contact and peak knee valgus moment during sidestepping: implications for ACL injury". Clin Biomech (Bristol, Avon) 20 (8): 863–70
  7. ↑ Mountcastle, Sally; et al. "Gender Differences in Anterior Cruciate Ligament Injury Vary With Activity. The American Journal of Sports Medicine. 35.10 (2007)
  8. ↑ 8.0 8.1 Yoon KH, Yoo JH, Kim KI.J. fckLRBone contusion and associated meniscal and medial collateral ligament injury in patients with anterior cruciate ligament rupture. Bone Joint Surg Am. 2011 Aug 17;93(16):1510-8.
  9. ↑ Dorothy M. Niall and Vladimir Bobic. Bone Bruising and Bone Marrow Edema Syndromes: Incidental Radiological Findings or Harbingers of Future Joint Degeneration? International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine [Accessed online 20th January 2012 at http://www.isakos.com/innovations/niall.aspx]
  10. ↑ Rick W. Wright, Mary Ann Phaneuf, Thomas J. Limbird and Kurt P. Spindler. Clinical Outcome of Isolated Subcortical Trabecular Fractures (Bone Bruise) Detected on Magnetic Resonance Imaging in Knees. Am J Sports Med September 2000 vol. 28 no. 5 663-667
  11. ↑ Mark A. Rosen, Douglas W. Jackson, Paul E. Berger. Occult osseous lesions documented by magnetic resonance imaging associated with anterior cruciate ligament ruptures. Arthroscopy: The Journal of Arthroscopic and Related SurgeryfckLRVolume 7, Issue 1 , Pages 45-51, March 1991
  12. ↑ R.B. Frobell, H.P. Roos, E.M. Roos, M.-P. Hellio Le Graverand, R. Buck, J. Tamez-Pena, S. Totterman, T. Boegard, L.S. Lohmande. The acutely ACL injured knee assessed by MRI: are large volume traumatic bone marrow lesions a sign of severe compression injury? Osteoarthritis and Cartilage, Volume 16, Issue 7, July 2008, Pages 829-836
  13. ↑ Viskontas DG, Giuffre BM, Duggal N, Graham D, Parker D, Coolican M. Bone bruises associated with ACL rupture: correlation with injury mechanism. Am J Sports Med. 2008 May;36(5):927-33. Epub 2008 Mar 19.
  14. ↑ Szkopek K, Warming T, Neergaard K, Jørgensen HL, Christensen HE, Krogsgaard M. Pain and knee function in relation to degree of bone bruise after acute anterior cruciate ligament rupture. Scand J Med Sci Sports. 2011 Apr 8. doi: 10.1111/j.1600-0838.2011.01297.x. [Epub ahead of print]
  15. ↑ 15.0 15.1 Atsuo Nakamae, Lars Engebretsen, Roald Bahr, Tron Krosshaug and Mitsuo Ochi. Natural history of bone bruises after acute knee injury: clinical outcome and histopathological findings. Knee Surgery, Sports Traumatology, Arthroscopy, Volume 14, Number 12, 1252-1258
  16. ↑ Hollis G. Potter, Sapna K. Jain,Yan Ma, Brandon R. Black, Sebastian Fung and Stephen Lyman. Cartilage Injury After Acute, Isolated Anterior Cruciate Ligament TearfckLRImmediate and Longitudinal Effect With Clinical/MRI Follow-up. Am J Sports Med February 2012 vol. 40 no. 2 276-285
  17. ↑ D E Meuffels, M M Favejee, M M Vissers, MP Heijboer, M Reijman, J Verhaar. Ten year follow-up study comparing conservative versus operative treatment of anterior cruciate ligament ruptures. A matched-pair analysis of high level athletes. British Journal of Sports Medicine 2009; 43(5):347-351
  18. ↑ J. Craig Garrison, Douglas Wyland. Rehabilitation Following a Minimally Invasive Procedure for the Repair of a Combined Anterior Cruciate and Posterior Cruciate Ligament Partial Rupture in a 15-Year-Old Athlete. J Orthop Sports Phys Ther 2010;40(5):297-309
  19. ↑ I Eitzen, H Moksnes, L Snyder-Mackler, MA Risberg. Progressive 5-Week Exercise Therapy Program Leads to Significant Improvement in Knee Function Early After Anterior Cruciate Ligament Injury. Journal of Orthopaedic and Sports Physical Therapy 2010;40(11):705-722
  20. ↑ S. van Grinsven, R. E. H. van Cingel, C. J. M. Holla, C. J. M. van Loon. Evidence-based rehabilitation following anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2010; 18:1128–1144
  21. ↑ Savio L-Y. Woo, Richard E. Debski, PhD, John D. Withrow, Marsie A. Janaushek. Biomechanics of Knee Ligaments. The American Journal of Sports medicine 1999;27:533
  22. ↑ Kyung-Min KiM, Ted Croy, Jay HerTel, SuSan Saliba. Effects of Neuromuscular Electrical Stimulation After Anterior Cruciate Ligament Reconstruction on Quadriceps Strength, Function, and Patient-Oriented Outcomes: A Systematic Review. J Orthop Sports Phys Ther 2010;40(7):383-391.


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