Anterior cruciate ligament: Difference between revisions

|From = [[Lateral condyle of femur|lateralLateral condyle]] of the [[femur]]

|To = [[intercondyloidIntercondyloid eminence]] of the [[tibia]]

The '''anterior cruciate ligament''' ('''ACL''') is one of a pair of [[cruciate ligament]]s (the other being the [[posterior cruciate ligament]]) in the [[human]] [[knee]]. The two ligaments are also called "[[cruciform]]" ligaments, as they are arranged in a crossed formation. In the [[quadruped]] [[stifle joint]] (analogous to the knee), based on its [[Anatomical terms of location#Sources of confusion|anatomical position]], it is also referred to as the '''cranial cruciate ligament'''.<ref name="MVRC">{{cite web|url=http://www.melbvet.com.au/pdf/cruciate-disease.pdf |title=Canine Cranial Cruciate Ligament Disease |publisher=[[Melbourne]] Veterinary Referral Centre |pages=1–2 |access-date=September 8, 2009|archive-url=https://web.archive.org/web/20080719110705/http://www.melbvet.com.au/pdf/cruciate-disease.pdf|archive-date=19 July 2008}}</ref> The term cruciate translatesis to[[Latin]] for cross. This name is fitting because the ACL crosses the posterior cruciate ligament to form an “X”"X". It is composed of strong, fibrous material and assists in controlling excessive motion. This is done by limiting mobility of the joint. The anterior cruciate ligament is one of the four main [[ligament]]s of the knee, providing 85% of the restraining force to [[anterior]] tibial displacement at 30 and 90° of knee flexion.<ref>{{Cite journal |pmid = 3969275|year = 1985|last1 = Ellison|first1 = A. E.|title = Embryology, anatomy, and function of the anterior cruciate ligament|journal = The Orthopedic Clinics of North America|volume = 16|issue = 1|pages = 3–14|last2 = Berg|first2 = E. E.|doi = 10.1016/S0030-5898(20)30463-6}}</ref> The ACL is the most frequently injured ligament of the four located in the knee.

An ACL tear is one of the most common knee injuries, with over 100,000 tears occurring annually in the US.<ref>{{Cite journal|last1=Cimino|first1=Francesca|last2=Volk|first2=Bradford Scott|last3=Setter|first3=Don|date=2010-10-15|title=Anterior Cruciate Ligament Injury: Diagnosis, Management, and Prevention|url=https://www.aafp.org/afp/2010/1015/p917.html|journal=American Family Physician|language=en|volume=82|issue=8|pages=917–922|pmid=20949884|issn=0002-838X}}</ref> Most ACL tears are a result of a non-contact mechanism such as a sudden change in a direction causing the knee to rotate inward. As the knee rotates inward, additional strain is placed on the ACL, since the femur and tibia, which are the two bones that articulate together forming the knee joint, move in opposite directions, causing the ACL to tear. Most athletes require reconstructive surgery on the ACL, in which the torn or ruptured ACL is completely removed and replaced with a piece of tendon or ligament tissue from the patient ([[autograft]]) or from a donor ([[allograft]]).<ref name="ACL reconstruction - Mayo Clinic">{{Cite web|url=https://www.mayoclinic.org/tests-procedures/acl-reconstruction/about/pac-20384598|title=ACL reconstruction - Mayo Clinic|website=www.mayoclinic.org|language=en|access-date=2018-11-15}}</ref> Conservative treatment has poor outcomes in ACL injury, since the ACL is unable to form a fibrous clot, as it receives most of its nutrients from [[synovial fluid]]; this washes away the reparative cells, making the formation of fibrous tissue difficult. The two most common sources for tissue are the patellar ligament and the hamstrings tendon.<ref>{{Cite journal|last1=Samuelsen|first1=Brian T.|last2=Webster|first2=Kate E.|last3=Johnson|first3=Nick R.|last4=Hewett|first4=Timothy E.|last5=Krych|first5=Aaron J.|date=October 2017|title=Hamstring Autograft versus Patellar Tendon Autograft for ACL Reconstruction: Is There a Difference in Graft Failure Rate? A Meta-analysis of 47,613 Patients|journal=Clinical Orthopaedics and Related Research|volume=475|issue=10|pages=2459–2468|doi=10.1007/s11999-017-5278-9|issn=1528-1132|pmc=5599382|pmid=28205075}}</ref> The patellar ligament is often used, since bone plugs on each end of the graft are extracted, which helps integrate the graft into the bone tunnels during reconstruction.<ref>{{Cite web|url=https://www.healio.com/orthopedics/curbside-consultation/%7B0c145d9a-2b5e-4c9a-9f78-bc8dae001b66%7D/when-would-you-use-patel|title=When Would You Use Patellar Tendon Autograft as Your Main Graft Selection?|website=www.healio.com|language=en|access-date=2018-11-15}}</ref> The surgery is arthroscopic, meaning that a tiny camera is inserted through a small surgical cut.<ref name="ACL reconstruction - Mayo Clinic"/> The camera sends video to a large monitor so the surgeon can see any damage to the ligaments. In the event of an autograft, the surgeon makes a larger cut to get the needed tissue. In the event of an allograft, in which material is donated, this is not necessary, since no tissue is taken directly from the patient's own body.<ref name="orthoinfo.aaos.org">{{Cite news|url=https://orthoinfo.aaos.org/en/treatment/acl-injury-does-it-require-surgery/|title=ACL Injury: Does It Require Surgery? - OrthoInfo - AAOS|access-date=2018-11-15}}</ref> The surgeon drills a hole forming the tibial bone tunnel and femoral bone tunnel, allowing for the patient's new ACL graft to be guided through.<ref name="orthoinfo.aaos.org"/> Once the graft is pulled through the bone tunnels, two screws are placed into the tibial and femoral bone tunnel.<ref name="orthoinfo.aaos.org"/> Recovery time usually ranges between one and two years, but is sometimes longer, depending if the patient chose an autograft or allograft. A week or so after the occurrence of the injury, the athlete is usually deceived by the fact that he/she is walking normally and not feeling much pain.<ref name="orthoinfo.aaos.org"/> This is dangerous, as some athletes start resuming some of their activities such as jogging, which with a wrong move or twist, could damage the bones, as the graft has not completely become integrated into the bone tunnels. Injured athletes must understand the significance of each step of an ACL injury to avoid complications and ensure a proper recovery.

ACL reconstruction is the most common treatment for an ACL tear, but it is not the only treatment available for individuals. Some may find it more beneficial to complete a nonoperative rehabilitation program. Individuals who are going to continue with physical activity that involves cutting and pivoting, and individuals who are no longer participating in those specific activities both are candidates for the nonoperative route.<ref name="Paterno 322–327">{{Cite journal|last=Paterno|first=Mark V.|date=2017-07-29|title=Non-operative Care of the Patient with an ACL-Deficient Knee|journal=Current Reviews in Musculoskeletal Medicine|volume=10|issue=3|pages=322–327|doi=10.1007/s12178-017-9431-6|issn=1935-973X|pmc=5577432|pmid=28756525}}</ref> In comparing operative and nonoperative approaches to ACL tears, few differences were noted between surgical and nonsurgical groups, with no significant differences in regard to knee function or muscle strength reported by the patients.{{cn|date=September 2023}}

The main goals to achieve during rehabilitation (rehab) of an ACL tear is to regain sufficient functional stability, maximize full muscle strength, and decrease risk of reinjury.{{cn|date=September 2023}} Typically, three phases are involved in nonoperative treatment - the acute phase, the neuromuscular training phase, and the return to sport phase. During the acute phase, the rehab is focusing on the acute symptoms that occur right after the injury and are causing an impairment. The use of [[Movement assessment|therapeutic]] exercises and appropriate therapeutic modalities is crucial during this phase to assist in repairing the impairments from the injury. The neuromuscular training phase is used to focus on the patient regaining full strength in both the lower extremity and the core muscles. This phase begins when the patient regains full range of motion, no effusion, and adequate lower extremity strength. During this phase, the patient completes advanced balance, [[proprioception]], cardiovascular conditioning, and neuromuscular interventions.<ref name="Paterno 322–327"/> In the final, return to sport phase, the patient focuses on sport-specific activities and agility. A functional performance brace is suggested to be used during the phase to assist with stability during pivoting and cutting activities.<ref name="Paterno 322–327"/>

[[Prehabilitation]] has become an integral part of the ACL reconstruction process. This means that the patient exercises before getting surgery to maintain factors such as range of motion and strength. Based on a [[Movement assessment|single leg hop test]] and self-reported assessment, prehab improved function; these effects were sustained 12 weeks postoperatively.<ref>{{Cite journal|last1=Shaarani|first1=Shahril R.|last2=O'Hare|first2=Christopher|last3=Quinn|first3=Alison|last4=Moyna|first4=Niall|last5=Moran|first5=Raymond|last6=O'Byrne|first6=John M.|date=September 2013|title=Effect of prehabilitation on the outcome of anterior cruciate ligament reconstruction|journal=The American Journal of Sports Medicine|volume=41|issue=9|pages=2117–2127|doi=10.1177/0363546513493594|issn=1552-3365|pmid=23845398|s2cid=38240767}}</ref>

Image:Gray347.png|Right knee joint, from the front, showing interior ligaments