2008 Anterior Cruciate Ligament Tear

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  clinical practice The   new england journal of    medicine n engl j med 359;20 november 13, 2008 2135 This  Journal  feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the authors’ clinical recommendations. Anterior Cruciate Ligament Tear Kurt P. Spindler, M.D., and Rick W. Wright, M.D. From Vanderbilt Sports Medicine, Vander-bilt University Medical Center, Nashville (K.P.S.); and the Department of Orthope-dic Surgery, Washington University School of Medicine at Barnes–Jewish Hospital, St. Louis (R.W.W.). Address reprint re-quests to Dr. Spindler at Vanderbilt Sports Medicine, 4200 Medical Center E., South Tower, 1215 21st Ave. S., Nash-ville, TN 37232-8774, or at Engl J Med 2008;359:2135-42. Copyright © 2008 Massachusetts Medical Society.  A female high-school soccer athlete reacts to a defender, plants her leg, cuts to the left without contact, feels her leg give out, hears a pop, and has acute pain. She is unable to walk off the field or return to play. That evening her knee progressively swells. The next day she presents for evaluation. How should her case be managed? The Clinical Problem The passage in 1972 of Title IX legislation, which guarantees equal access to athletic programs for both sexes at any high school or college receiving federal funds, has led to an exponential rise in the number of female participants in sports. Although this has resulted in many benefits, including the promotion of physical fitness and the foster-ing of team-building behavior, it has also led to an increase in sports-related injuries among female athletes, particularly tears in the anterior cruciate ligament (ACL).The ACL is the most commonly injured ligament in the body, for which surgery is frequently performed. It is estimated that 175,000 ACL reconstructions were per-formed in the year 2000 in the United States at a cost of more than $2 billion. 1  This number continues to increase. Incidence rates for tears are difficult to assess because some injuries remain undiagnosed. A recent study at West Point, where injuries are consistently reported, showed an incidence of ACL tears of 3.2% for men and 3.5% for women during a 4-year period. 2  When considering sports or activities in which both sexes participate, women had a significantly higher rate of ACL tears than men (incidence ratio, 1.5; 95% confidence interval [CI], 1.3 to 2.2). 3  The majority of ACL tears (67% in men and almost 90% in women) occurred with-out physical contact. In other studies, the injury rate in female athletes has ranged from two to six times the rate in male athletes, depending on the sport studied. 4-7  The increased risk of an ACL tear in female athletes remains incompletely under-stood but has been attributed to several factors, including sex differences in leg alignment, with an increased rate of valgus deformity (knock-knee) among women; in notch width, with possibly less space for the ACL in women; in hormonal factors, including an increased risk during the preovulatory stage of the menstrual cycle 8 ; and in neuromuscular control. 6,9 Besides the immediate associated morbidity and costs, an ACL tear significantly increases the risk of premature knee osteoarthritis. 3,10  It is estimated that osteoar-thritis develops in 50% of patients with ACL tears 10 to 20 years after the injury,  while they are still young. 3,11,12 Strategies and Evidence Diagnosis Careful history taking and physical examination will frequently allow an accurate diagnosis of an ACL tear without the need for additional testing or evaluation. An The New England Journal of Medicine Downloaded from on December 17, 2012. For personal use only. No other uses without permission. Copyright © 2008 Massachusetts Medical Society. All rights reserved.  The   new england journal of    medicine n engl j med 359;20 november 13, 2008 2136 isolated ACL tear occurs less than 10% of the time, and assessment is needed for associated injuries; the prevalence of associated meniscus injuries is 60 to 75% 7,13,14 ; articular cartilage injuries, up to 46% 7,13-15 ; subchondral bone injuries (i.e., “bone bruises”), 80% 16-18 ; and complete collateral liga-ment tears (medial or lateral), 5 to 24%. 14,16,19  Table 1 and Figure 1 summarize the functions of the three major intraarticular knee structures (ACL, meniscus, and articular cartilage) and mani-festations of injury to these structures.Key points of the history suggesting ACL tear include a noncontact mechanism of injury, the identification of an audible popping sound, the early occurrence of swelling as a result of bleed-ing (hemarthrosis) from the rupture of the vascu-lar ACL, and an inability to continue to partici-pate in the game or practice after the injury. Collateral ligament tears usually do not result in swelling, and frequently patients with partial posterior ligament tears can continue to play. Meniscus tears are associated with a delayed on-set of swelling (commonly the next day).During the physical examination, two maneu- vers — the Lachman test and the pivot shift test — are useful in the assessment of an ACL tear. The Lachman test is shown in Figure 2; the pivot shift test assesses whether there is a sudden sub-luxation of the lateral tibial condyle on the distal femur when the knee is extended. In a recent meta-analysis of 28 studies, the pooled sensitivity and specificity of the Lachman test for an ACL tear were 85% and 94%, respectively. 20  For the pivot shift, the specificity was high (98%), but the sensitivity was low (24%).Magnetic resonance imaging (MRI) is often used to confirm the diagnosis of an ACL tear, although it is not needed before proceeding to ACL reconstruction in an athlete when the diagnosis is clear from the history and physical examination. According to a systematic review, MRI had a sen-sitivity of 86%, a specificity of 95%, and an ac-curacy of 93% for an ACL tear, as confirmed by arthroscopy. 21 Treatment The majority of patients with a torn ACL can walk normally and can perform straight-plane activi-ties, including stair climbing, biking, and jog-ging. Surgical treatment is indicated if the patient has a sensation of instability in normal activities of daily living or wants to resume activities that involve cutting and pivoting, including football, soccer, basketball, lacrosse, singles tennis, and mogul skiing. Occupations such as firefighting, law enforcement, and some construction jobs also require an ACL-stabilized knee.Regardless of whether surgical intervention is pursued, the short-term management of an ACL tear should focus on the reduction of hemar-throsis with rest, ice, compression, and elevation (RICE); the administration of nonsteroidal anti-inflammatory agents; and the regaining of a normal range of motion, the reinitiation of quad-riceps control, and the restoration of a normal gait. A delay of 2 to 4 weeks between the acute injury and surgical correction is common. Surgical Approaches The surgical approach to ACL tears for the past two decades has involved the reconstruction of the ACL with the use of a graft (a piece of tendon) passed through tunnels drilled into the tibia and femur at insertion points of the ligament to ap-proximate normal anatomy, with the goal of elim-inating ACL instability. Reconstruction is indicat-ed rather than repair, since randomized trials have shown that ACL repair is no better than nonoperative treatment  22  and that ACL reconstruc-tion significantly improves knee stability and the likelihood of return to preinjury activity over re-pair alone or repair with augmentation (insertion of a tendon graft or synthetic graft). 23  In addition, randomized trials of ACL reconstruction have shown significantly fewer subsequent meniscus tears requiring surgery at 2 years than in nonop-erative management, 24  whereas the addition of augmentation to ACL reconstruction offered no benefit over reconstruction alone.A systematic review of four randomized trials has demonstrated similar outcomes using endo-scopic (single-incision) versus rear (two-incision) entry. 25  Either patellar tendon or hamstring ten-don may be used. A systematic review of nine randomized, controlled trials involving autografts found that these approaches yielded similar re-sults, including anterior–posterior laxity, isoki-netic quadriceps and hamstring strength, anterior knee pain, and clinical outcome or rating scores, 26  although the four trials that evaluated pain on kneeling found an increase in pain in procedures harvesting the patellar tendon, as compared with The New England Journal of Medicine Downloaded from on December 17, 2012. For personal use only. No other uses without permission. Copyright © 2008 Massachusetts Medical Society. All rights reserved.  clinical practice n engl j med 359;20 november 13, 2008 2137 the hamstring. Meta-analyses of trials comparing patellar tendon and hamstring autografts 27,28  showed no significant differences in the rates of restoring a “normal” knee, categorized as group A by the International Knee Documentation Com-mittee (41% and 33%, respectively), and of a re-turn to preinjury activity (76% and 67%, respec-tively). Patients with patellar tendon grafts had a significantly lower rate of positive results on the Lachman test (30% vs. 34%) but a significantly higher rate of anterior knee pain (22% vs. 13%) and extension deficit (9% vs. 6%). However, vali-dated scales were not used to assess anterior knee pain, activity level, or overall knee rating, and  validated patient-reported outcomes have not been compared between these grafts.There is a lack of randomized trials to inform the choice of allograft versus autograft for ACL reconstruction. The best available evidence is from seven observational studies 29-35  showing no significant differences in patient-reported out-comes, instrumented laxity, and donor-site symp-toms. However, the failure rate after 2 years was significantly higher for patients receiving allo-grafts (9 of 158) than for those receiving auto-grafts (2 of 167) (P = 0.03). Thus, the avoidance of allografting is prudent when possible in young athletes. The means of graft fixation (i.e., the technique or device used to secure the graft into the tibial and femoral tunnels) has not affected outcomes, including stability, range of motion, strength, and clinical assessments.Immediate complications of ACL reconstruc-tion are uncommon but include infection, deep  venous thrombosis, and nerve injury. 26  Graft failure has been reported in 3.6% of patients at 2 years, with no significant differences noted between grafting of a hamstring tendon and grafting of a patellar tendon. Additional arthro-scopic surgery was necessary in 14.7% of patients in one series, including the débridement of scar tissue and treatment of meniscus and articular cartilage. In a prospective cohort study, the risk of tearing an ACL reconstruction graft was the same as the risk of tearing the contralateral nor-mal ACL (3.0% for each). 36  Associated Injuries The presence of other knee injuries may adversely affect outcomes after ACL reconstruction. The risk of osteoarthritis appears to be increased in pa-tients who have had an associated meniscal tear or cartilage injury. Detailed discussion of the techniques to treat these associated injuries is beyond the scope of this article, but case series indicate high success rates for treating meniscal injuries. Longitudinal tears in the vascular zone (the peripheral third of the ligament) undergo repair, which has been reported to result in an 87% success rate (defined as the absence of a need for reoperation for clinical symptoms) with the use of current techniques. 37  Tears in the avas-cular zone (the central two thirds of the ligament) are treated with partial meniscectomy. There is currently no effective treatment for articular car-tilage injuries that do not penetrate subchondral Table 1. Function, Type of Injury, and Initial Evaluation of Commonly Injured Knee Structures.Knee Structure Biomechanical Function Clinical Function Injury Type Symptoms* Signs Anterior cruciate ligamentPrevents anterior and rotational motion of tibia relative to femurStabilizes knee for cut-ting and pivotingTear (primarily rupture)“Giving out” while cut-ting and pivotingPositive Lachman test and pivot shift testMeniscus (medial and lateral)Decreases force per unit area on articular car-tilage (distributes load)Protects articular carti-lage from prema-ture degeneration or osteoarthritisTear (both partial and complete)Mechanical symptoms (e.g., catching, locking) Joint-line pain, effusionArticular cartilageAllows for nearly fric-tionless gliding sur-face and impact dis-sipationAllows for painless and nearly effort-less active motion and impactFocal defect or osteoarthritis†Focal defect: no symp-toms or possible pain; osteoarthritis: pain, stiffness, swellingFocal defect: no symp-toms or loose piece of cartilage; osteo-arthritis: joint-line pain, effusion* Symptoms that are most specific for the diagnosis are listed.† Focal defects are those isolated to a small area, such as the femoral condyle. Focal defects are believed to be predictive of osteoarthritis, which is characterized by a regional loss of structure and function of the articular cartilage. The New England Journal of Medicine Downloaded from on December 17, 2012. For personal use only. No other uses without permission. Copyright © 2008 Massachusetts Medical Society. All rights reserved.  The   new england journal of    medicine n engl j med 359;20 november 13, 2008 2138 bone, other than débridement of unstable pieces. In patients in whom a lesion extends to bone, a  variety of restorative procedures are available. Rehabilitation A recent systematic review  38,39  of 54 randomized clinical trials evaluated a variety of rehabilitation techniques and “assistive devices.” Among its conclusions were that immediate postoperative  weight bearing does not adversely affect subse-quent knee function; that in a motivated patient, a self-directed home-therapy program with ini-tial education and monitoring is as effective as regular physical therapy visits; that the use of continuous passive-motion machines does not im-prove outcome, as compared with no use of such machines; that the use of postoperative function-al bracing versus no bracing does not improve B Meniscus C Articularcartilage A Anteriorcruciateligament l   Structure Biomechanical Function Injury Surgery The New England Journal of Medicine Downloaded from on December 17, 2012. For personal use only. No other uses without permission. Copyright © 2008 Massachusetts Medical Society. All rights reserved.
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