ACL Tear

ACL Tear Description
The anterior cruciate ligament is often referred to as the ACL.   70% of injuries to the ACL result from sports participation. 30% from direct contact and 70% from non-contact injuries. ACL tears are common in sports such as football, soccer, downhill skiing and rugby. Non-contact injuries occur while changing direction or landing from a jump. 

Female athletes are more likely to sustain ACL tears though the prepondurance of males involved in sports results in more males actually being injured.

95% of patients with ACL deficient knees who return to high-level activity will have further damage to their knees including meniscal and cartilage damage with resultant progressive arthritis. Arthritic changes in the knee generally progress despite successful ACL reconstruction

ACL Tear Anatomy
The ACL is one of the four major stabilizing ligaments in the knee. It functions primarily as a restraint to anterior tibial translation (90%); It is also a secondary restraint to tibial rotation and minor secondary restraint to varus-valgus angulation when the knee is in full extension. The tensile strength of the ACL is 2,150 N and its stiffness is 242 N/mm. Tension forces in the ACL are highest with the knee in full extension. The ACL is composed of Type I collagen (90%) and Type III collagen (10%)

The ACL originates from the lateral wall of the intercondylar notch of the distal femur at its posterior aspect and inserts in an oval shaped area, in the anterior aspect of the tibial plateau between the tibial eminences.

ACL Tear Symptoms
ACL Tears causes pain and swelling in the knee.  During the initial injury people often feel or hear a "pop" sensation in the knee. The knee generally swells within a few hours. Knee range of motion may be limited by pain, hamstring spasm, ACL impingement, or an associated meniscal tear.

ACL Tear Treatment 
ACL Tears are diagnosed based on a detailed history, physical exam and xrays performed by an orthopaedic surgeon, or sports medicine specialist.

Treatment for ACL injuries is dependent on the type of tear as well as the patients activity level. Partial thickness ACL tears that involve less than 50% of the thickness of the ACL often do well without surgery. People with complete ACL tears who are involved in cutting sports (football, soccer, basketball) or side-to-side sports (skiing, tennis) or are heavy manual labor generally need their ACL surgically reconstructed. People who are not involved in sports and do not do heavy labor often due well without surgery.

Risks of surgery include but are not limited to: Loss of stability / Graft failure, Anterior knee pain / kneeling pain, Stiffness, Painful hardware, Infection, Patellar fracture / patellar tendon rupture, Arthritis:, Arthrofibrosis, Cyclops lesion, NVI (saphenous neuralgia), Complex Regional Pain Syndrome, Hemarthrosis, Neurovascular Injury, Hardware failure, Pain unchanged or worse than before surgery, Stiffness, Incisional scar (cosmesis), Numbness surrounding the incision, Need for further surgery, blood clots (DVT), pulmonary embolus (PE), and the Risks of anesthesia including heart attack, stroke and death. Although complications can occur they are uncommon and most patients are satisfied with their surgical outcomes. You should always discuss any concerns that you have about surgery with your surgeon and ensure that you have a surgeon that you trust and are confident in.

After surgery people are generally placed in a hinged knee brace 7-21 days post-op. They may weight bear as tolerated with crutches and may discontinue crutches when comfortable, usually @ 2 weeks. Patients follow-up 7-14 days after surgery. The knee brace may be removed when non-weight bearing. Bracing is discontinued when people have excellent muscle control in the knee, generally at 6weeks.

Typically patients have physical therapy 2-3x per week for 12 weeks.   After 1wk they begin low-resistance stationary bike exercises, quad sets, straight leg raises, early hamstring resistance exercises, and closed-chain exercises with elastic cords. Therapy progress from there until patients are returned to full, unrestricted sports.

In general patients progress as follows:

12wks=cleared for all activities except: running on hard surfaces, terminal knee extensions with resistance, and jumping/pivoting sports.
6months=may do running and terminal knee extensions
8months=if 90% of hamstring and quadriceps strength have been regained and patient has full unrestricted ROM they may return to full, unrestricted sport with functional knee brace.
Driving: may drive after 6 weeks for right leg; 2 weeks for left leg.

Athletes returning to sports after ACL Tear should begin with a graduated exercise program. First they should be pain free with daily activities with full range of motion and at least 85% strength in the injured leg compared to the uninjured leg. Exercise begins with light jogging in a straight line, followed by sprinting in a straight line. When these have been done without pain the athlete can proceed to doing agility type drills such as 45º cuts, 90º cuts and jumping. Agility drills should begin at half-speed and proceed to full-speed provided the athlete remains pain free.  In most situations it takes 8-12 months to fully return to sports after ACL surgery.

ACL Tear Prevention
There are many important opportunities to decrease the risk of ACL injury.  As in all sports it is most important to maintain flexibility by stretching before and after practice or games.  Maintaining a proper diet and overall physical fitness is important. 

ACL injury prevention exercise programs have been shown to have a substantial beneficial effect.  ACL injury prevention programs have demonstrated  a risk reduction of 52% in the female athletes and 85% in the male athletes.  ACL injury prevention programs should include at least ten minutes of exercises three times per week, with a focus on neuromuscular training.  ACL injury prevention programs include lower extremity plyometrics, dynamic balance and strength, stretching, body awareness and decision-making, and targeted core and trunk control exercises. 
-Knee braces have been shown to decrease the risk of MCL injury, but does not affect ACL or LCL injuries

ACL Tear Risk Factors
ACL Tear is associated the following sports: Baseball; Basketball; Boxing; Cycling; Dance; Diving; Equestrian Sports; Figure Skating; Football; Golf; Gymnastics; Hockey;Rugby; Running; Skiing; Snowboarding; Soccer; Tennis; Volleyball; Wrestling.  Risk Factors for ACL tears include: a small femoral notch width, generalized ligamentous laxity, high body mass index, high landing forces, high varus/valgus moments, ineffective muscle activation and female gender.

ACL Tear Rehab and Exercise Program
ACL Tear

ACL Tear Outcomes
Approximately 90% of patients who undergo ACL reconstruction achieve restoration of knee stability, patient satisfaction, and return to full activity. ACL reconstruction decreases the risk of future meniscal tear, and improves stability, but its effects on delaying or preventing arthritis are unknown.

Similar injuries that can be confused with ACL Tear include:

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