Management of Anterior Cruciate Ligament Injuries
Endorsed by: NASM, AOSSM, NATA, AAPM&R
History and Physical
Strong evidence supports that the practitioner should obtain a relevant history and perform a musculoskeletal exam of the lower extremities, because these are effective diagnostic tools for ACL injury.
Strong Evidence Strong Evidence
There were six high-strength and four moderate-strength studies evaluating history and physical examination as diagnostic tools for ACL injury. 8, 23, 32, 55, 58, 60, 87, 91, 104, 105 A relevant history is important for diagnosing ACL injuries and concomitant pathology and should include at a minimum the mechanism of injury, history of hearing/feeling a popping sensation, ability to bear weight, ability to return to play, history of mechanical symptoms of locking or catching, localization of pain if possible, and any history of prior knee injuries. 55, 60, 91 History of hearing/feeling a popping sensation and associated swelling is important in predicting an ACL injury.87

Appropriate physical exam is important in diagnosing ACL injuries and concomitant pathology and should also be performed including at a minimum: a neurovascular exam with documentation of both distal perfusion and tibial/peroneal nerve function, assessment for joint line tenderness or obvious step off/deformity, evaluation for an effusion, assessment of varus and valgus laxity at 0 and 30 degrees of extension, evaluation of anterior-posterior and rotational laxity. 8, 32, 58, 104, 105 Lachman’s test should be performed and has been shown to be sensitive for ACL injury.23

Benefits of Implementation
A thorough history and physical exam will assist the practitioner in prompt and accurate diagnosis of ACL injuries and concomitant pathology.

Possible Harms of Implementation
There are no known harms associated with appropriate implementation of this recommendation.

Future Research
Future research could help confirm the most useful history and physical exam findings for the diagnosis of ACL injury and concomitant pathology.
Radiographs
In the absence of reliable evidence, it is the opinion of the work group that in the initial evaluation of a person with a knee injury and associated symptoms [giving way, pain, locking, catching] and signs [effusion, inability to bear weight, bone tenderness, loss of motion, and/or pathological laxity] that the practitioner obtain AP and lateral knee xrays to identify fractures or dislocations requiring emergent care.
Consensus Consensus
While recognizing that various criteria for performing knee radiographs have been published, the consensus opinion recommends that practitioners initially evaluating a patient with an acute knee injury should obtain AP and lateral radiographs of the knee.  In the setting of acute knee injury, radiographs may lead to the diagnosis of fracture, dislocation, ligament disruption, neoplasm, foreign body, and/or soft tissue injury that could lead to loss of the limb or limb function. Early diagnosis of these disorders may decrease morbidity from the injury.

If a MRI or CT scan is already available additional radiographs may not be necessary. This recommendation is consistent with current practice.

Benefits of Implementation
Potential early recognition of clinically important knee injury enhances patient care.

Possible Harms of Implementation
X-ray exposure.

Future Research
Adequately powered study to evaluate the sensitivity and specificity of methods used in the initial evaluation of acute knee injury; symptoms and physical signs, plain radiographs, MRI scan, and CT scan.
 
Magnetic Resonance Imaging (MRI)
Strong evidence supports that the MRI can provide confirmation of ACL injury and assist in identifying concomitant knee pathology such as other ligament, meniscal, or articular cartilage injury.
Strong Evidence Strong Evidence
Fifteen high strength and two moderate strength studies demonstrated that MRI has a high sensitivity and specificity in diagnosing ACL tears, but somewhat lower sensitivity and specificity at identifying concomitant injuries and other problems.2, 30, 38, 40, 41, 42, 55, 59, 65, 89, 91, 92, 97, 101, 105, 107, 116 

A combination of history, clinical examination (Lachman test), and radiographs has similar diagnostic accuracy as MRI for identifying ACL tears. An MRI could be used in conjunction with the history and physical examination.

Possible Harms of Implementation
There are no known harms associated with implementing this recommendation.

Future Research
Evaluation of the severity and significance of cartilage and subchondral bone injury with regards to the risk of developing future arthritis
 
Pediatric
There is limited evidence in skeletally immature patients with torn ACLs, but it supports that the practitioner might perform surgical reconstruction because it reduces activity related disability and recurrent instability which may lead to additional injury.
Limited Evidence Limited Evidence
There was one low and two very low strength studies comparing surgical reconstruction to non-operative treatment. 72, 88, 110 Surgical reconstruction demonstrated a significant advantage over non-operative treatment in objective knee stability (KT1000, pivot shift, Lachman), subjective knee function scores (IKDC, Zarins and Rowe score, Lysholm), and Tegner activity score. None of three studies reported a clinically significant valgus deformity or limb length discrepancy.

Benefits of Implementation
Potential benefits of implementing this recommendation include: improving knee stability and functional outcomes in skeletally immature patients with ACL injury.

Possible Harms of Implementation
Potential harms include: physeal injury, graft failure and surgical complications.

Future Research
Prospective studies on transphyseal versus all-epiphyseal reconstruction, intra-articular versus extra-articular techniques, and long-term outcomes of young patients following ACL reconstruction. Prospective comparative studies of non-operative treatment and ACL reconstruction in skeletally immature patients are necessary.

 
Young Active Adult
Moderate evidence supports surgical reconstruction in active young adult (18-35) patients with an ACL tear.
Moderate Evidence Moderate Evidence
The recommendation is based on one study of one prospective randomized cohort and two studies of moderate strength. 33, 34, 67, 90 The evidence indicates that ACL reconstruction decreases pathologic laxity, as measured by the Lachman, KT-1000, and pivot shift tests, and reduces episodes of instability and the incidence of subsequent injuries including meniscal tears.

Possible Harms of Implementation
As with all surgical procedures, there are patient risk including but not limited to infection, anesthetic complications, phlebitis, and neurovascular injury.

Future Research
Recommend increased attention to assessing factors important to potentially delay or prevent post-joint injury osteoarthritis such as outcomes of meniscus repair vs resection and outcomes assessing joint biology and homeostasis including restoration of normal joint biomechanics. Prospective comparative studies of nonoperative treatment and ACL reconstruction in skeletally immature patients are necessary.
 
 
Meniscal Repair
There is limited evidence in patients with combined ACL tears and reparable meniscus tears, but it supports that the practitioner might repair these meniscus tears when combined with ACL reconstruction because it improves patient outcomes.
Limited Evidence Limited Evidence
Nine low strength and two very low strength studies were included in this recommendation.6, 20, 45, 57, 68, 76, 102, 103, 106, 120, 121 One low strength study reported improved subjective knee function (Lysholm knee score and IKDC Score) and reduced activity related pain and swelling with repaired (51%)/stable (49%) menisci compared to meniscectomy at the time of ACL reconstruction.121 Objective functional outcomes as evidenced by single leg hops scores were also improved in the repaired/stable meniscus group.  One low strength study and one very low strength study reported reduced radiographic abnormalities in knees with repaired/stable menisci and a reduced incidence of osteophytes following repair compared to medial meniscectomy.6, 121Likewise, a very low strength study reported a reduction in pain following lateral meniscus repair compared to lateral meniscectomy combined with ACL reconstruction.103 Several studies reported improved outcomes with ACL reconstruction and menisci repair, but the groups were not directly comparable. 

Possible Harms of Implementation
As with all surgical procedures, there are patient risks including but not limited to infection, anesthetic complications, phlebitis, neurovascular injury, meniscal repair failure, and ACL reconstruction failure.

Future Research
Long-term, prospective studies comparing ACL reconstruction in patients with normal menisci to patients with torn menisci having either meniscectomy or meniscal repair. Further, we can investigate the pattern of meniscal tear, biology of meniscal healing, and repair techniques to increase the chance of successful repair. When meniscectomy is necessary additional research should be performed in the fields of meniscal transplantations and meniscal regeneration.
 
Recurrent Instability
There is limited evidence comparing non-operative treatment to ACL reconstruction in patients with recurrent instability, but it supports that the practitioner might perform ACL reconstruction because this procedure reduces pathologic laxity.
Limited Evidence Limited Evidence
One prospective comparative study was included.24 With respect to recurrent instability, this study compared two groups of interest – an ACL-unstable group that ultimately did not undergo ACL reconstruction despite persistent pathologic laxity (Group II in the article, considered "copers") as well as an ACL-unstable group that ultimately did undergo late ACL reconstruction following recurrent instability (Group IV in the article).  The late ACL reconstructions in Group IV occurred 9 to 84 months after injury.  Of the 147 patients in Group II, only 11 had meniscal surgery. Of the 46 patients in Group IV, 29 had meniscal surgery. The article also reports an ACL-stable group with hemarthrosis (Group I) and an ACL-unstable group that underwent early ACL reconstruction (Group III).

At final evaluation of symptoms, 18% of the non-ACL-reconstructed, unstable patients (Group II) reported giving way with sports while only 3% of the late-ACL-reconstructed patients (Group IV) reported giving way with sports.  Similarly, 9% of the non-ACL-reconstructed, unstable patients (Group II) reported giving way with activities of daily life, while only 3% of the late-ACL-reconstructed patients (Group IV) reported giving way with activities of daily life. Objective instrumented and physical examination findings paralleled these subjective findings. This is without undergoing ACL reconstruction (Group II), 84% of patients demonstrated positive KT-1000 arthrometer measurements (>3 mm side-to-side difference with manual maximum testing) and 84% had positive pivot shift testing.  Following late ACL reconstruction (Group IV), 70% of patients demonstrated positive KT-1000 arthrometer measurements and 52% had positive pivot shift testing.

Possible Harms of Implementation
As with all surgery procedures, there are surgical risks and complications including but not limited to graft failure, arthrofibrosis, infection, neurovascular injury, and anesthetic complications.

Future Research
Further research is needed to assess the outcomes in patients with recurrent instability.  Specifically, we need to follow these patients after non-operative treatment as well as after ACL reconstruction.
 
Conservative Treatment
There is limited evidence to support non-surgical management for less active patients with less laxity.
Limited Evidence Limited Evidence
This recommendation is based on one moderate-strength, one low strength and three very low strength studies .24, 31, 71, 93, 29 Patients were classified based on activity level and knee laxity at initial injury. The following three groups were considered particularly low risk: (1) Patients participating in less than 50 hours of jumping or cutting sports and less than 5 mm of side to side difference based on KT-1000 or manual maximal testing, (2) Patients participating in 50-199 hours of jumping or cutting sports with less than 5 mm of side to side difference based on KT-1000 or manual maximal testing, and (3) Patients participating in less than 50 hours of jumping or cutting sports with 5-7 mm of side to side difference based on KT-1000 or manual maximal testing.31 Collectively, these low risk groups were found to have lower rates of late meniscal surgery and ACL reconstruction than patients in the high risk groups treated non-operatively.31 Thus, low risk patients may do well with non-operative treatment. However, 25% of the low risk patients ultimately required surgery, including ACL reconstruction or meniscal surgery.31

Benefits of Implementation
Lower risk patients, based on activity and/or index laxity criteria, may tolerate an ACL deficient knee, and therefore may be spared exposure to the risks of surgical intervention such as infection, risks of anesthesia, arthrofibrosis, etc.

Possible Harms of Implementation
Despite being categorized as low risk, these patients may still require late ACL reconstruction and/or meniscal surgery and could sustain further damage to the ACL deficient knee

Future Research
Future research should attempt to define which patients may be safely treated conservatively after ACL injury, and what specific risk factors contribute to this decision making process.

 
Surgery Timing
When ACL reconstruction is indicated, moderate evidence supports reconstruction within five months of injury to protect the articular cartilage and menisci.
Moderate Evidence Moderate Evidence
With respect to performing ACL reconstruction early following injury, three moderate strength studies evaluated the effect of timing on outcome following ACL reconstruction.17, 56, 76 Post-operative range of motion was not different if surgery was performed within 48 hours of injury, within 3-7 days of injury, or within 2 weeks of injury; or if surgery was delayed more than 3 weeks of injury, delayed for a minimum of 6 weeks of injury, or delayed for 8-12 weeks of injury. 17, 56, 76 Strength and stability by KT 1000 were also not different between early and delayed ACL reconstruction.56, 76 However, performing ACL reconstruction early, within three weeks of injury, increased the rate of re-operation form 0% to 8%. Complications included pain with extension (n=11), meniscus tear (n=1), and failed ACL reconstruction (n=2;).56
 
With respect to delaying ACL reconstruction to a time point past the injury, there were two high-strength studies of same cohort of patients and three moderate-strength studies that compared early (within 3-5 months from injury) versus late (after 3-5 months from injury) ACL reconstruction. 10, 24, 33, 35, 36 Early reconstruction improved objective knee stability as measured by the Lachman test and pivot shift test.83, 84 Three studies demonstrated a higher activity level in the patients that underwent early ACL reconstruction. 10, 33, 35, 36 One study reported higher function in patients that underwent early ACL reconstruction.24
 
Early reconstruction also decreased the incidence of meniscus tears from 62% to 37% and decreased the incidence of subsequent meniscectomy surgery from 44% to 8%.10, 35 One moderate-strength study stratified outcome by meniscus injury, which was not emphasized in the high-strength study but was supported by their data.10,35 Further, in the setting of meniscus treatment, the rate of meniscal repair was 29% with early ACL reconstruction and 12% when ACL reconstruction was delayed beyond 3 months.
 
The importance of this recommendation was based on improving patient function and protecting the knee with ACL injury from further meniscus injury, which could reduce the risk for premature osteoarthritis
 
Possible Harms of Implementation
The decision to perform early ACL reconstruction could lead to loss of motion, joint stiffness, and reoperation if sound history and physical examination is not performed.
 
Future Research
Randomized control trials should be performed to better understand the effect of timing of ACL reconstruction on range of motion, rate of reoperation, and clinical outcome of patients.
 
Combined MCL
There is limited evidence in patients with acute ACL tear and MCL tear to support that the practitioner might perform reconstruction of the ACL and non-operative treatment of the MCL tear.
Limited Evidence Limited Evidence
Two low strength studies evaluated isolated reconstruction of the ACL in acute ACL/MCL and chronic ACL/MCL injuries in which the MCL injury was high grade, but not complete (no or minimal valgus laxity when tested in full extension).43, 75 Both used hinged braces in the post-operative period.  Their results for ACL laxity and function are comparable to ACL reconstruction in isolated ACL tears. Valgus laxity was reduced from pre-operative status, but still present. This did not seem to alter functional status.
 
Potential Benefits of Implementation
Potential benefits include reduction of surgery with decreased OR time and less likelihood of motion limitations.

Potential Harms of Implementation
Potential harms may include the late loss of function or recurrent ACL injury from the residual valgus laxity.

Future Research
Long term follow-up studies of ACL reconstructed patients with partial MCL tears treated non-operatively at the time of ACL reconstruction, compared to isolated ACL injuries treated with ACL reconstruction would establish if there is potential harm associated with this strategy of treatment for complete ACL tears with associated partial MCL tears.
 
Locked Knee
In the absence of reliable evidence, it is the opinion of the work group that patients with an ACL tear and a locked knee secondary to a displaced meniscal tear have prompt treatment to unlock the knee in order to avoid a fixed flexion contracture.
Consensus Consensus
There were no published studies that met the criteria for this recommendation. The work group felt that, if left untreated for a sufficient period of time, a locked knee may lead to a fixed flexion contracture that may no longer be recoverable and could thus threaten the functional viability of the leg.

The torn meniscus is also more likely to be repairable if the meniscus is reduced early. Prolonged knee flexion may lead to articular cartilage damage as well.

Potential Harms of Implementation
As with all surgical procedures, there are patient risks including but not limited to infection, anesthetic complications, phlebitis, neurovascular injury, meniscal repair failure, and ACL reconstruction failure.

Future Research
Evaluation of the relative risk of arthrofibrosis if the ACL is reconstructed at the same time or as a staged procedure
 
 
Single or Double Bundle Reconstruction
Strong evidence supports that in patients undergoing intra-articular ACL reconstruction the practitioner should use either single bundle or double bundle technique, because the measured outcomes are similar.
Strong Evidence Strong Evidence
There are four high and eight moderate strength studies that compare single to double bundle ACL reconstruction.1, 3, 5, 51, 53, 56, 77, 79, 83, 99, 114, 123  The majority of the studies demonstrate no statistically significant difference in any outcome parameters. Meta-analysis demonstrated no statistically significant difference between single and double bundle reconstruction in post-operative pain, Lysholm or IKDC subjective knee scores.

Potential Harms of Implementation
As with all surgery procedures, there are surgical risks and complications including but not limited to, graft failure, arthrofibrosis, infection, neurovascular injury, and anesthetic complications.

Future Research
Long-term prospective, randomized studies comparing single and double bundle reconstruction should be performed to document clinical outcomes, degree of tunnel enlargement, traumatic arthritis, and incidence and results of subsequent revision surgeries. Double bundle surgery may include additional expense, and may increase the complexity of revision ACL surgery; future studies may analyze this surgical approach.
 
 
Autograft Source
Strong evidence supports that in patients undergoing intra-articular ACL reconstruction using autograft tissue the practitioner should use bone-patellar tendon-bone or hamstring-tendon grafts, because the measured outcomes are similar.
Strong Evidence Strong Evidence
There were four high-strength, and 19 moderate-strength studies included in this recommendation. 3, 7,10, 10, 13, 22, 27, , 28, 34, 49, 52, 63, 64, 86, 95, 96, 100, 115, 118, 119, 122 Graft choice did not matter with respect to stability testing in three high-strength studies  and ten moderate-strength studies.10, 16, 26, 48, 72, 111, 159, 165, 243, 287,294, 308   Patient satisfaction, normal IKDC score  , and graft failure were also not different between the two graft choices.10, 10, 13, 22, 27, 28, 34, 49, 52, 63, 64, 96, 115

However, significantly more post-operative kneeling pain was present in the patella tendon group as demonstrated by two high-strength studies and one moderate-strength study.28, 52, 96
 
Potential Harms of Implementation
Possible graft failure in either graft is possible and reported
 
Future Research
Recommend evaluation of radiographic and symptomatic osteoarthritis as mid to long term outcome measures in comparison studies between extensor mechanism grafts (patellar and quad tendons) and hamstring grafts. Additional research comparing ipsilateral grafts to contralateral grafts is also needed.

 
Autograft vs Allograft
Strong evidence supports that in patients undergoing ACL reconstructions, the practitioner should use either autograft or appropriately processed allograft tissue, because the measured outcomes are similar, although these results may not be generalizable to all allografts or all patients, such as young patients or highly active patients.
Strong Evidence Strong Evidence
This recommendation was built upon two high strength studies and seven moderate strength studies. 26, 39, 62, 63, 85, 111, 112, 113, 117 The preparation of allografts varies with respect to procurement, processing, storage, and implantation. Each of these steps can affect the mechanical properties and incorporation of the graft. Understanding these limitations, there were two high strength and six moderate strength studies available that compared ACL reconstruction with autograft and allograft tissues.
 
Combining the autograft and nonirradiated allograft data from two studies, there was a 6% failure rate with autograft and a 9% failure rate with nonirradiated allograft, which was not a statistically significant difference.111, 112 In contrast, there was a 34% failure rate with irradiated allograft (2.5 Mrad). The difference between failures in the autograft group and the irradiated allograft group was statistically significant.
 
Five moderate strength prospective comparative studies, similarly demonstrated that the clinical outcomes of ACL reconstruction with allograft were not significantly different from those with autograft.26, 62, 63, 84, 117
 
The allografts used in the study by Gorschewsky et al. were sterilized with osmotic treatment, oxidation, and solvent drying with acetone.39 In contrast, the other studies involved the use of fresh-frozen allografts or cryopreservation.  The patient-oriented outcomes, physical examination findings, instrumented laxity measurements, and complications in the allograft group in the study by Gorschewsky et al. were much worse than those in the other treatment arms of the other five prospective comparative studies. 26, 39, 62, 63, 84, 117

While outcomes following ACL reconstruction using autograft tissue and using non-irradiated allograft tissue are similar overall, these results may not be generalizable to specific subsets of patients with ACL rupture, such as athletes and young patients.  In fact, a longitudinal cohort study indicated a higher failure rate of allograft tissue in younger patients (Figure 3, Kaeding -- Sports Health 2011). 
 
Potential Harms of Implementation
As with all surgery procedures, there are surgical risks and complications including but not limited to graft failure, arthrofibrosis, infection, neurovascular injury, and anesthetic complications.  With ACL reconstruction using autograft tissue, there are specific additional risks of donor site morbidity, including risk of patellar fracture and long-term kneeling pain (with autograft bone-patellar tendon-bone) as well as risk of saphenous nerve trauma and long-term knee flexor strength deficit (with autograft hamstring tendon).  With ACL reconstruction using allograft tissue, there are specific additional risks of potential for disease transmission and limited availability.
 
Future Research
While outcomes following ACL reconstruction using autograft tissue and using non-irradiated allograft tissue are similar overall, these results may not be generalizable to specific subsets of patients with ACL rupture, such as elite athletes and very young patients.  Specifically, further research is needed to assess the outcomes following ACL reconstruction using autograft tissue and using non-irradiated allograft tissue in patients with specific activity levels (including elite athletes), ages (including the young and very young), and associated injuries.
 
Further research is needed to assess the outcomes following ACL reconstruction using autograft tissue and using non-irradiated allograft tissue in patients with specific activity levels (including elite athletes), ages (including the young and very young), and associated injuries.
 
 
Femoral Tunnel Technique
Moderate evidence supports that in patients undergoing intra-articular ACL reconstruction the practitioner could use either a tibial independent approach or transtibial approach for the femoral tunnel, because the measured outcomes are similar.
Moderate Evidence Moderate Evidence
There were seven moderate, one low, and one very low strength studies that compared intra-articular ACL reconstruction with use of a tibial independent to a transtibial approach to create the femoral drill hole.9, 18, 44, 73, 74, 78, 81, 82, 98

Research on this recommendation did not evaluate the techniques used for ACL reconstructions in skeletally immature patients. The tibial independent approach included both outside-in and medial portal drilling techniques. The studies demonstrate no consistent differences between the two techniques in objective metrics or patient reported outcomes. Meta-analysis of the study demonstrated no difference in IKDC knee exam or Lysholm scores.

Potential Harms of Implementation
As with all surgical techniques, there are potential complications such as malposition of the femoral tunnel or femoral tunnel blowout.

Future Research
Prospective randomized trials comparing the results of ACL reconstruction with femoral tunnels created using tibial independent and trans-tibial approaches should be performed to evaluate difference in objective metrics including limits of knee motion, and patient reported outcomes.
 
Post-Op Functional Bracing
Moderate evidence does not support the routine use of functional knee bracing after isolated ACL reconstruction, because there is no demonstrated efficacy.
Moderate Evidence Moderate Evidence
Three moderate strength studies compared the use of functional bracing following ACL reconstruction to either the use of no brace or a neoprene knee sleeve. 16, 69, 94 None of the studies showed statistically significant benefit of the functional brace in any of the functional or laxity measurements, including Tegner activity scale, Lysholm score, ACL Quality of Life, IKDC score, instrumented laxity testing, and limb hop distance symmetry. These results held up for one and two years in all of the studies. Based on this moderate evidence for lack of efficacy in the use of functional knee bracing following ACL reconstruction, its routine use cannot be supported.

Potential Benefits of Implementation
The benefit of implementing this recommendation may be a decrease in the overall cost of ACL reconstruction and rehabilitation.

Potential Harms of Implementation
There are no known harms associated with implementing this recommendation.

Future Research
No future research needed.
 
Prophylactic Braces
Limited evidence supports that the practitioner might not prescribe prophylactic knee braces to prevent ACL injury, because they do not reduce the risk for ACL injury.
Limited Evidence Limited Evidence
One moderate strength and one low strength study demonstrated no reduction in ACL injury rates with ACL prophylactic bracing in high school and collegiate American football players.25, 108

Future Research
Additional research could investigate the effect of prophylactic bracing in other populations (i.e. adolescent female soccer players) in which ACL injury rates are high. 
 
 
Neuromuscular Training Programs
Moderate strength evidence from pooled analyses with a small effect size (Number Needed to Treat=109) supports that neuromuscular training programs could reduce ACL injuries.
Moderate Evidence Moderate Evidence
One moderate strength study of female adolescent handball players and two low strength studies of adult male and adolescent female soccer players demonstrated significant reduction in ACL injuries after neuromuscular training.80, 19, 66  Five moderate strength studies showed a non-significant reduction and one moderate strength study showed a non-significant increase in ACL injuries (note: we were unable to confirm statistically significant reductions in injury reported by some of the aforementioned studies when reanalyzing the raw data).36, 46, 48, 61, 85, 109  No high strength double-blind randomized control trials implementing neuromuscular training interventions were identified, likely due to the difficulty in blinding of athletes and the need to cluster randomize athletes by team.  A two-step process of pooled analyses was employed. The initial pooled analysis contained all best available quality studies meeting the a priori inclusion criteria for this recommendation (Figure 11. Meta-Analysis of All Investigations Meeting Inclusion Criteria for ), showed no quantitative heterogeneity (0%), and indicated a relative risk reduction of 53 (20 to 72%). However, content and delivery methods among programs in these studies demonstrated qualitative heterogeneity; therefore a subset of the most homogeneous programs was identified. Programs were considered homogeneous if they contained similar exercise modalities and training implementation strategies (e.g., plyometrics, strengthening, instructor feedback to athletes).  The second pooled analysis of the homogeneous programs (Figure 12. Meta-Analysis of Investigations that Employed the Most Homogeneous Intervention) confirmed significant relative risk reduction of 62 (41 to 79%) favoring neuromuscular training programs for prevention of non-contact ACL injuries. The majority of the reported programs were coach-led and compliance was fair to poor, when reported. The current analyses indicate that the number needed to treat to prevent one ACL injury is approximately109 athletes (Figure 13. Number Needed to Treat (NNT) Analysis for Most Homogeneous Investigations (NNT =108.75)). An assessment of the studies included in this analysis demonstrated no publication bias (Figure 1D)
 
Potential Benefits of Implementation
The benefits of a neuromuscular training program implementation as part of a sports competition regime include a reduced risk of sustaining a sports related ACL injury.
 
Potential Harms of Implementation
No studies reported a significant increase in injury in those who participate in a neuromuscular training program for ACL injury prevention. 
 
Future Research
Future research from multi-site studies utilizing a standardized neuromuscular training program with large populations of high-risk athletes is recommended to further establish efficacy.  In addition, there is a need to investigate methods to optimize protocols (i.e., exercise modality), improve delivery and instruction (i.e., training feedback) and improve coach and athlete compliance. Lastly, a majority of the studies included adolescent and adult female soccer, basketball, volleyball and handball players. Future research that includes other high risk sports as well as male athletes is warranted to expand the generalizability of these results.
Post-Op Physical Therapy
For those undergoing post-operative rehabilitation after ACL reconstruction, moderate evidence supports early, accelerated, and non-accelerated protocols because they have similar outcomes.
Moderate Evidence Moderate Evidence
One high and one moderate strength study compared two year patient outcomes between a 19-week accelerated rehabilitation program versus a 32 week non-accelerated program.14, 15The rehabilitative programs were common relative to limits in knee ROM, the amount of weight bearing permitted, and type of rehab activity prescribed –however the accelerated programs had earlier initiation of activities known to strain the ACL, including unrestricted ROM (week 4 versus week 8), earlier weaning from brace (weeks 2-6 versus weeks 4-6), earlier OKC full knee extension (week 6 versus week 12), earlier CKC and functional tasks (week 5-6 versus week 12).  At 24-months post ACL reconstruction, the two groups had similar knee laxity, clinical assessments, patient satisfaction, activity levels and functional scores; and similar detection of passive motion and knee extensor strength. 14, 15

Other moderate strength studies examine early unrestricted motion and weight bearing (immediate versus 2-4 weeks; immediate versus 5-6 weeks) and early initiation open kinetic chain quadriceps exercise (limited range [90 – 40o] starting at 4 versus 12 weeks in isolation, and all reported similar patient outcomes with early versus late initiation of these activities.21,35, 47, 54 Early, accelerated protocols may include early weight bearing, range of motion, and strengthening including the addition of open kinetic chain exercises at six weeks.

Potential Benefits of Implementation
The benefit of early accelerated rehabilitation is that patients may be able to return to full, unrestricted activity sooner.

Potential Harms of Implementation
The impact on long term outcomes (e.g. progression of osteoarthritis) of the timing and intensity of rehabilitation programs is currently unknown.  For example, Beynnon (2005) noted that biomarkers of articular cartilage metabolism remained elevated well after the completion of both rehabilitation programs and the time interval that most individuals will return to full, unrestricted physical activity.  Cleavage of Type II collagen returned to normal after 12 months, while synthesis of Type II collagen and turnover of aggrecan approached normal but remained at 24 months.

Future Research
Current evidence is limited to two studies that have followed patients out 2 years post-surgery.  Additional research on long term outcomes of early, accelerated, and non-accelerated rehabilitation and return to activity on long term physical activity, biomechanical deficits and incidence of complications (e.g. onset of OA) are needed. Future Research should also address the influence of accelerated rehabilitation on graft integrity and the integrity of articular cartilage. This includes the use of imaging (MRI) to assess the effects of accelerated or delayed rehabilitation on graft healing and maturation and on the integrity of articular cartilage.
Return to Sports
Limited strength evidence does not support waiting a specific time from surgery/ injury, or achieving a specific functional goal prior to return to sports participation after ACL injury or reconstruction.
Limited Evidence Limited Evidence
The rationale for return to play and secondary injury risk was based on one low and one very low strength study.37, 104 Early return (mean five months) versus late return (mean nine months) to sport was not different for subsequent ipsilateral ACL injury, subjective and objective functional outcomes or knee laxity. 37 Similarly, early return to sports (<6 months versus >6months) was not associated with increased incidence of either contralateral or ipsilateral ACL injury. 104

The rationale for return to play based on achieving functional criteria was based on one low strength study.11 This study reported similar potential return to pre-injury sport levels in those who attempted to return before 12 months relative to those who returned after 12 months.

Potential Harms of Implementation
As individuals heal and recover at different rates and each injury has its own unique circumstances, it is difficult to assign a specific endpoint that would favor return to sport.  Each patient should be treated individually and functionally advanced to the level of their ability. Premature return to full activity may cause injury to a reconstructed ligament, surrounding structures, or the contralateral knee.  Early return in those individuals who elect non-operative management may lead to further injury of surrounding tissues and further decline. Current evidence is lacking as to the long-term consequences of premature return to sport on joint homeostasis, dynamic function, and risk of secondary injury.

Future Research
Future research is needed to identify the functional deficits that are associated with increased second injury risk and reduced long term outcomes. Future investigations may assess more directly individual graft healing times, alternative therapeutic exercises, changes in frequency or duration to individual programs, platelet rich plasma treatments, genetic markers/gene therapy.
 
Immediate Treatment of Acute Traumatic Knee Joint Injury
The following companion consensus statement was developed by panels nominated by the National Athletic Trainer's Association (NATA) and has been approved by the National Athletic Trainer's Association's Board of Directors. In the absence of reliable evidence, NATA recommends that people who sustain an acute traumatic knee joint injury with symptoms (e.g., feel or hear a pop, experience a giving way episode, pain, swelling or difficulty weight bearing) receive a physical examination by a qualified health care professional that assesses the structural integrity of the knee joint capsule, ligaments and menisci, and includes a neurovascular exam as soon as possible following injury. Immediate treatment with ice, compression, elevation, immobilization, and crutches is also indicated and patients should be referred for further musculoskeletal evaluation, unless signs and symptoms indicate that an emergent condition is present (e.g. neurovascular, gross deformity, uncontrollable pain).
Consensus Consensus
N/A
Aspiration of the Knee
The following companion consensus statement was developed by panels nominated by the American Orthopaedic Society for Sports Medicine (AOSSM) and has been approved by the American Orthopaedic Society for Sports Medicine's (AOSSM) Board of Directors. In the absence of reliable evidence, AOSSM recommends that physicians consider aspirating painful, tense effusions after knee injury.
Consensus Consensus
N/A
Physical Exam
The following companion consensus statement was developed by panels nominated by the National Athletic Trainer’s Association (NATA) and has been approved by the National Athletic Trainer's Association's (NATA) Board of Directors. In the absence of reliable evidence, NATA recommends that following an acute traumatic knee joint injury, patients with an abnormal neurovascular finding on physical exam, gross deformity, or severe and uncontrollable pain should receive emergent care to include immobilization and ongoing serial assessments of neurovascular function during transport to an emergency medical facility.
Consensus Consensus
N/A
Rehabilitation
The following companion consensus statements was developed by panels nominated by the American Physical Therapy Association (APTA) and has been approved by the American Physical Therapy Association (APTA) Board of Directors. In the absence of reliable evidence, it is the recommendation of APTA that a patient with an ACL tear who is not having ACL reconstruction undergo rehabilitation with goals of (1) full and pain free knee joint ROM is restored (equal to that of the contralateral limb), (2) thigh muscle strength and single hop test indexes are at least 90% (ratio of involved to uninvolved limb performance), and (3) self-reported knee function on reliable, valid, and responsive questionnaires is at least 90%.
Consensus Consensus
N/A

ACKNOWLEDGEMENTS

Guideline Work Group:
Kevin G. Shea, MD (Chair)
James L. Carey MD, MPH (Vice Chair)
John Richmond, MD
Robert H. Sandmeier, MD
Ryan T. Pitts, MD
John D. Polousky, MD
Constance Chu MD
Sandra J. Shultz PhD., ATC, FACSM, FNATA
Mark Ellen, MD
Angela Smith, MD
Cynthia R. LaBella, MD
Allen F. Anderson, MD
Volker Musahl, MD
Gregory D. Myer PhD

AAOS Guidelines Oversight Chair:
David Jevsevar, MD, MBA

AAOS Clinical Practice Guidelines Section Leader:
Kevin Shea, MD

AAOS Council on Research and Quality Chair:
Kevin J. Bozic, MD, MBA

 
Additional Contributing Members:
Jack Bert, MD
Warren R. Dunn, MD, MPH
Lynn Snyder- Mackler, PT, ScD, SCCS, FAPTA
 
AAOS Staff:
William Shaffer, MD, AAOS Medical Director
Deborah Cummins, PhD, Director of Research and Scientific Affairs
Jayson N. Murray, MA, Manager, Clinical Practice Guidelines
Peter Shores, MPH, Statistician
Nilay Patel, MA, Lead Research Analyst
Anne Woznica, MLS, Medical Librarian
Yasseline Martinez, Administrative Coordinator
Kaitlyn Sevarino, Evidence-Based Quality and Value Coordinator
 
Former Staff:
Leeaht Gross, MPH
 

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