|Year : 2019 | Volume
| Issue : 2 | Page : 58-65
Systematic review of recovery protocols for athletes following ACL injuries: Surgical vs. conservative treatment
Manish Shukla1, Vishnu Dutt Bindal2, Vivek Pandey1
1 Department of Exercise Physiology, Lakshmibai National Institute of Physical Education, Gwalior, Madhya Pradesh, India
2 Department of Health Education, Lakshmibai National Institute of Physical Education, Gwalior, Madhya Pradesh, India
|Date of Submission||19-Feb-2019|
|Date of Decision||15-May-2019|
|Date of Acceptance||08-Jun-2019|
|Date of Web Publication||07-Oct-2019|
Mr. Manish Shukla
Department of Exercise Physiology, Lakshmibai National Institute of Physical Education, Gwalior, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
Injuries to anterior cruciate ligament (ACL) are common in sports. The treatments prescribed for torn ACL are surgical reconstruction (ACLr) and conservative management. While both treatments do not offer relief from long-term osteoarthritis (OA), the choice of the best treatment for athletes remains unclear. To assess the effectiveness of surgical versus conservative treatment for treating torn ACL in sports, a literature search in PubMed, MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and Cochrane Library Central Register of Controlled Trials was done for randomized controlled trials/quality randomized controlled trials (RCTs/QRCTs) that compared surgical reconstruction with conservative treatment of ACL rupture in active participants. Studies were assessed for quality using PEDro clinical appraisal tool. Since the studies were heterogeneous, meta-analysis was not performed, and a “best evidence synthesis” was reported. There were four studies (RCTs/QRCTs), which met the inclusion criteria. The mean age of participants in ACLr group ranged 25.3–45.8 years, while in CON group, it was 25.5–49.3 years. Tibiofemoral OA ranged from 23% to 80% in surgery group and 28%–68% in conservative group. Three studies reported no difference between surgical and conservative group in terms of long-term OA at 10–20 years' follow-up. When assessed in terms of functional knee outcomes (Lysholm score, IKDC score, and Tegner score) and knee laxity, ACLr group showed significantly better outcomes. Thus, it may be suggested, based on functional knee outcome scores, that ACLr may help athletes resume their sporting career postinjury. Further good quality RCTs involving a large number of participants are required to strengthen the claim.
Keywords: Anterior cruciate ligament, anterior cruciate ligament reconstruction, conservative, Lysholm score, Tegner score, tibiofemoral osteoarthritis
|How to cite this article:|
Shukla M, Bindal VD, Pandey V. Systematic review of recovery protocols for athletes following ACL injuries: Surgical vs. conservative treatment. Physiother - J Indian Assoc Physiother 2019;13:58-65
|How to cite this URL:|
Shukla M, Bindal VD, Pandey V. Systematic review of recovery protocols for athletes following ACL injuries: Surgical vs. conservative treatment. Physiother - J Indian Assoc Physiother [serial online] 2019 [cited 2022 Aug 19];13:58-65. Available from: https://www.pjiap.org/text.asp?2019/13/2/58/268644
| Introduction|| |
Injury to anterior cruciate ligament (ACL) is very common among athletic population. It is often accompanied by functional impairment, meniscal damage, chondral joint lesions, tibiofemoral instability, and eventually knee osteoarthritis (OA).
There are two kinds of treatments offered to patients with ACL injury: conservative treatment and surgical reconstruction. Both the treatments aim to restore functional stability of the knee and avoid the development of OA. Surgery for ACL rupture usually involves simple repair using suturing or suturing with some sort of augmentation to ACL reconstruction (ACLr) in which the torn ligament is reconstructed using a substitute graft of tendon or ligament fixed into position in preprepared drill holes. Nowadays, ACLr is increasingly performed as an arthroscopic procedure. In 94% of those patients, who undergo surgical reconstruction procedures, are performed within 1 year of the initial injury. Hamstring tendons graft or bone–patella tendon-bone (BPTB) graft is widely used for reconstruction whose properties have been studied before.
Conservative (nonoperative) treatment for ACL rupture includes rehabilitative protocols with modalities such as cryotherapy (ice), electrical stimulations, supporting brace, and exercises aimed at strengthening and balance.
Rehabilitation protocols are followed after both types of treatments: conservative and surgery. It is three-stage program: acute, recovery, and functional phases. The acute stage of rehabilitation following injury, or immediately after surgery, aims at restoring range of motion and reducing inflammation. The recovery phase (3–6 weeks) aims at improving lower limb muscle strength and functional stability. The functional stage of rehabilitation (from 6 weeks onward) ensures safer return to previous levels of activity with low re-injury risks.
The goal of every treatment is to reduce knee pain and instability and restore function. In acute severe instability or “giving away” cases as well as in long-term or chronic ACL injury cases, surgical treatment has been strongly recommended to resume active lifestyle. Conservative treatment has demonstrated satisfactory results with patients returning to preinjury activity level,, but in the long-term, complications of degenerative changes (the development of early onset of OA) are still debatable.
Knee OA is linked to degenerative changes in the integrity of cartilage that acts as a cushion between the joining bones. Knee OA occurrence rate after an isolated ACL rupture is about 0%–13% after a follow-up of 10 years. However, when combined with meniscus damage, this rate increases to 21%–48%. Radiographically diagnosed OA has been reported in 20%–50% of ACL-deficient knees at 10 years' postinjury compared with 5% in uninjured knees. While surgery has not shown to offer protection against long-term degenerative change, recent studies have suggested structured neuromuscular rehabilitation might provide effective recovery following ACL rupture without increasing the risks of long-term degenerative change.
Functional instability characterizes ACL injury whether in reconstruction or conservative treatment. Knee laxity assessment using the KT-1000 arthrometer, pivot-shift test, and Lachman test failed to differentiate between reconstruction and conservative treatment groups.
ACL injury is a multifactorial outcome. Since the nature and intensity of causative factors of ACL injury significantly differ between athletic and nonathletic population, as well as between different sports, the treatment protocols should be recommended taking these into consideration. However, there has been great controversy among orthopedic community regarding the best treatment for knee injury and particularly ACL tears in terms of the development of OA and functional instability after conservative versus surgical reconstruction.,
Purpose of the review
Both the methods of ACL injury treatment, i.e., reconstructive surgery and conservative protocols aim to restore knee stabilization and function. Since previous reviews,,,,, considered only general population and keeping this fact in mind that a greater proportion of ACL injuries occur in sporting arena, the deficiency of concrete understanding about the best treatment method for treating torn ACL among general and athletic population warrants further systematic review of the currently available good randomized controlled trials/quality randomized controlled trials (RCTs/QRCTs) for comparing surgical versus conservative treatment among injured athletes.
The objective of the study is to review the current literature and establish the optimal treatment (surgical vs. conservative interventions) for ACL injuries for athletes.
| Methods and Materials|| |
Inclusion and exclusion criteria
The studies were included if they met the following criteria:
(A) randomized or Quasi-RCTs with head-on comparison between ACLr and ACL conservative treatment among athletes only, (B) no other ligament was injured greater than Grade II, (C) BPTB or hamstring tendon graft was used in surgical reconstruction, (D) the tibiofemoral OA prevalence was reported, (E) return to sports activity was reported, (F) follow-up was equal to or more than 10 years, and (G) they were written in English.
Surgical reconstruction means arthroscopic reconstruction of the torn ACL with BPTB or Hamstring tendon graft. Conservative (nonsurgical) management means any intervention which was noninvasive and therefore included physiotherapy and rehabilitation programs consisting of exercise, bracing, electrotherapy, and muscle stimulation interventions and graded return to exercise and activities.
Studies were excluded if (A) patients were placed in casts after surgery, or (B) patients underwent ACL revision surgery or (C) studies where ACL and posterior cruciate ligaments were ruptured together or (D) studies with a meniscal injury were also included, but meniscal repair or other collateral ligament repair caused the studies to be excluded. Also excluded were those studies performed on human or animal cadaver, basic science articles, editorial articles, and surveys.
Comprehensive online literature search was conducted for articles published from the year 2000 to June 2018. A rigorous database search was done in PubMed, MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and Cochrane Library Central Register of Controlled Trials.
Database search was done using the following keywords - ACL OR ACL AND OA OR osteoarthrosis OR degenerative joint disease OR arthritis OR gonarthrosis ACLr OR repair OR surgery OR replacement AND meniscus OR menisci OR tear OR torn OR injury OR injuries OR injured, ACL injury AND return to sports. Although we focused on tibiofemoral OA, we did not specify the type of OA for the literature search to avoid eliminating studies of both tibiofemoral and patellofemoral OA.
The parameters of interest were functional outcome as measured with reliable and valid patient-reported outcome measures such as the Lysholm Knee Score, International Knee Documentation Committee Score (IKDC), Tegner Activity Score, and KT-1000 arthrometer knee laxity score.
Quality assessment of included studies
The studies included in the review were appraised for quality using PEDro Critical Appraisal Tool. PEDro Critical Appraisal tool consists of 11 questions to assess the recruitment, allocation, power, blinding, and data analysis aspects of clinical trials. [Table 1] includes PEDro appraisal criteria for selected studies. The quality assessment pointed toward methodological weaknesses and indicated a high risk of bias. Only one study had compared the results of ACLr versus conservative management through an RCT design. The remaining three studies adopted the method of retrospective matched pair comparison. All the studies showed that ACLr and conservative groups were similar at baseline. Major source of bias included participants' allocation to ACLr or conservative group since randomization was reported only in one study. However, since the allotment of the treatment was left to patients' choice, randomization was impossible to achieve. All the included studies measured at least one outcome for 85% or more of their cohort. All the studies presented between-group comparisons for their dataset. Point and variability measures were reported for at least one key outcome in all studies.
|Table 1: Quality assessment of selected studies using PEDro critical appraisal tool|
Click here to view
| Results|| |
Data synthesis and analysis
Since the studies differed with regard to the parameters and outcome measures included (and hence, heterogeneous), the data could not be pooled for statistical analysis. Thus, “a best-evidence synthesis” was performed., With the use of the system developed by van Tulder et al., the following ranking of levels of evidence was formulated: (1) strong evidence is provided by two or more studies with low risk of bias and by generally consistent findings in all studies (≥75% of the studies reported consistent findings), (2) moderate evidence is provided by one low risk of bias study and two or more high risk of bias studies and by generally consistent findings in all studies (≥75%), (3) limited evidence is provided by one or more high risk of bias studies or one low risk of bias study and by generally consistent findings (≥75%), (4) conflicting evidence is provided by conflicting findings (<75% of the studies reported consistent findings), and (5) no evidence is provided when no studies could be found.
Initially, 254 studies were selected and were independently reviewed by authors for their titles, keywords, publication year, and abstracts [Figure 1]. After screening for duplicates and retrievals, remaining 184 studies were reviewed for full-text availability (73 abstracts removed), language (non-English articles removed), and nature of articles (editorials, surveys, and basic medical articles) and 137 records were additionally removed. Thus, full texts of the 47 remaining articles were reviewed again for meeting inclusion/exclusion criteria. This step yielded 12 studies which were brought for final screening of quality assessment and a total of 4 articles were provisionally identified as meeting the inclusion criteria and thus included in the review. The selected studies were reported in [Table 2] along with their characteristics.
Characteristics of participants in the studies
A total of 186 participants at final follow-up period were included in the review, with sample sizes ranging from 32 to 54 patients. The mean age of participants in ACLr group ranged 25.3–45.8 years, while in conservative group, it was 25.5–49.3 years. All studies included radiologic assessment of surgically versus conservatively treated participants. Three studies reported median Lysholm scores for ACLr versus conservative group. Median IKDC scores for functional knee outcomes, Tegner activity scores for activity rating were reported for all the groups and KT-1000 arthrometer knee laxity scores were presented for two studies as percentage of patients >3 mm, while for one study, it was measured in millimeters (mm), and for one study, it was not reported. The follow-up time in the included studies ranged from 10 to 20 years [Table 2].
Prevalence of knee osteoarthritis
The overall tibiofemoral joint OA percentage varied between 23% and 80% in ACLr group while the corresponding prevalence of OA in the nonoperative conservatively treated patients' knees ranged from 28% to 68% [Table 2]. One study with long follow-up period (17–20 years) demonstrated significant tibiofemoral OA prevalence (67%) in conservatively treated group than ACLr group (28%, P < 0.05). No other studies reported significant differences for the prevalence of knee OA between surgically treated (23%–80%) and nonsurgically treated individuals (28%–67%, P < 0.05).,,
Knee functional outcomes
The overall median Lysholm scores for ACLr group ranged 84–88, while for conservative treatment group, it was 53–89 [Table 2]. For one study, the median Lysholm scores were not reported while it was assessed as written in full article. Only one study demonstrated significantly higher Lysholm score (84.3) for ACLr group than conservatively treated group (53.3, P < 0.05). All remaining studies,, failed to show a significant difference between ACLr group and conservative group in median Lysholm score at 0.05 level of significance.
All the studies revealed subjective median IKDC scores [Table 2]. Two studies, showed significantly higher IKDC scores for ACL surgery group than conservatively treated group (P < 0.05) while other two, failed to show such differences.
Median Tegner activity scores for before surgery activity level and at follow-up activity level were reported for all the selected studies [Table 2]. Two studies, showed significant improvement in activity level following surgery for ACL surgery group (P < 0.05) while remaining two, did not (P < 0.05). For conservatively treated groups, three studies,, showed a significant decrement in median Tegner scores following conservative treatment while one study showed no difference (P < 0.05) in median Tegner score following conservative treatment.
KT-1000 arthrometer knee laxity scores [Table 2] were reported for three studies,, while one study did not report KT-1000 knee laxity score for the study. Two studies, provided percentage of patients whose KT-1000 score was >3 mm. In these two studies, there were significantly less percentages of patients with laxity >3 mm in ACLr group as compared to conservative group. One study reported knee laxity at follow-up in millimeters (mm) and showed significantly less knee laxity as measured by KT-1000 arthrometer in ACLr group (1.5 mm) as compared to nonsurgically treated group (4.5 mm; P < 0.05).
| Discussion|| |
The parameters included in the synthesis of the review were the prevalence of tibiofemoral OA, functional outcomes of knee, activity level before and after treatment, and knee laxity/instability. As per the inclusion and exclusion criteria, four randomized/quasi-randomized trials were selected that addressed the basic purpose of comparing ACL surgery versus conservative treatment among active athletes.
Injury to the ACL is very common phenomena in sports. Sandberg et al. suggested that “a possible candidate for ACL surgery could be a patient with high physical demands and with a positive pivot shift.” A severe ACL injury may shorten athlete's career or force him to retire from sports.
Tibiofemoral osteoarthritis following anterior cruciate ligament tear: Surgical versus conservative treatment
OA is a major degenerative joint disease in elderly population. Previous studies have demonstrated that the risk factors for OA development include age at onset of injury, sex, obesity, injury severity, meniscus status, and knee arthroscopy. Female and elderly population are at high risk of OA development following knee injury. Evidence shows that overweight individuals have a high prevalence of knee OA. In younger population, the incidences of knee OA are mainly due to sprains to the knee.
While reconstruction after ACL injury might not completely prevent OA, this strategy may reduce the OA prevalence. This can be attributed to better joint stability, re-alignment of disrupted joint kinematics, less laxity and thus less degeneration following ACLr. Furthermore, there are lesser incidents of total knee replacement in ACL reconstructed patients (0.6%) than nonreconstructed patients (4.6%, P < 0.001). Patients undergoing ACLr within 1 month following injury are at lower risk of OA as compared to those undergoing late reconstruction or treated conservatively. Furthermore, early reconstruction of ACL injury may prevent OA in athletes with symptomatic instability.
However, Kessler et al. reported in their retrospective cohort study with 11 years of follow-up that ACLr resulted in higher incidence of OA. Harris et al. reported in a systematic review based on 4 retrospective follow-up (overall follow-up = 11.8 years) studies that OA incidence following ACLr was greater (overall = 41.4%, 95% confidence interval = 35.0%–48.1%) than following nonsurgical treatments (overall = 30.9%, 95% confidence interval = 24.4%–38.3%). After ACLr surgery, the short-term functional results appear favorable, however, over long term, at least 28%–87% of these patients develop posttraumatic tibiofemoral OA.
However, the decision regarding the choice of treatment has always been left to the patient. Some patients opt for nonsurgical treatment of their ACL injuries., Patients recommended for this type of treatment typically have sufficient dynamic knee stability for their desired level of function and no secondary joint injury (e.g., meniscal tear and collateral ligament sprain). For these patients, the rates of OA range from 11% to 73%. Furthermore, there is a general opinion for younger individuals to opt for ACLr and older participants to undergo conservative treatment.
Many of the patients had anteroposterior laxity of more than 3 mm (as measured by KT-1000 arthrometer), which is defined as pathologic knee instability, and for the reconstructed group, these results are considered failures according to universal failure definitions. However, strikingly conservative group had more percentage of patients above 3 mm, and thus, it can be concluded that knee laxity in conservatively treated group was greater than ACLr group and it might force a patient to undergo delayed reconstruction.
Knee function and return to sports
Ardern et al. reported that following ACLr about 80% of athletes returned to some kind of sport, 63% athletes achieved their preinjury level of participation, and 44% resumed their competitive sports whereas the rate of return to competitive sports following conservative treatment ranged 10%–14%.
About 90% ACL reconstructed athletes score well on laxity test and strength test, and 85% score well on IKDC subjective scale as compared to nonsurgically treated group. However, despite the good outcomes in clinical examination relatively low rate of return to competitive sport have been observed, thus speculating the role of psychological factors and fear of reinjury affecting return to sport.
Bjordal et al. concluded that reconstructive surgery was necessary for an athlete to be able to play football again, but findings by Myklebust et al. challenged this report; 82% of the nonoperatively treated patients returned to competitive team handball at their preinjury level of performance. Roos et al. in a study of ACL-injured soccer players' reported that only 30% of 219 players were still active soccer players after 7 years, and the ability to return to soccer was the same regardless of treatment choice. Furthermore, the rates of delayed surgery for knee instability in ACL-deficient patients range from 12% to 39%.,, High motivation and a strong wish to play again may help in early return to sports despite having problems with pain, instability, or reduced range of motion.
| Conclusion|| |
The previous reviews,,,,, do not provide evidence for ACLr reducing the rate of OA development or improving the long-term symptomatic outcomes. However, the conservative treatment group also has been found to be symptomatic at follow-up and later opt for ACLr., Although the precise effect of ACLr on knee functional outcomes is unclear till date, ACLr has been associated with greater knee joint stability, restored knee anatomy, and biomechanics leading to an increased ability to counter sheer and torsional stress on cartilage structures and reduction in the cumulative incidence of OA in patients undergoing ACLr.
In a stricter sense, the results from this systematic review thus agree with Monk et al. who concluded that due to lack of good quality randomized trials, it is impossible to determine whether surgery or conservative treatment is best for ACL injury. In addition, low methodological quality of the included studies in the review resists a strong opinion in favor of any treatment. However, based on the results of functional outcomes of knee following both treatments from this study, the opinion gravitates toward surgical treatment as a suitable option to resume athletic career satisfactorily.
Limitations of the study
The studies included in this review had no clear randomization of participants as the patients opted for the type of treatment to undergo. In addition, it is unclear whether the functional outcomes and knee stability of patients in both groups were similar at the time of the choice of treatment as more knee instability may force an individual to opt for reconstructive treatment. The status of meniscus in patients at the time of injury was not under control. Patients sustaining meniscal repair or meniscectomy have a higher rate of OA development. This may be attributed to the fact that torn meniscus fails to absorb the stress on the articulating surfaces in the joint and progressive loading makes it worse over time.
It should be noted that the selected studies had different grafts used for reconstruction. This could make a difference when long-term outcomes of surgical treatment are to be evaluated. OA was assessed by radiological method, which is less precise than magnetic resonance imaging in diagnosing the degenerative changes in the joint. In addition, baseline OA was not reported in the studies, and thus outcomes may not be true representative of actual differences. These limitations suggest cautious interpretation of results and conclusions of the present review.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Moses B, Orchard J, Orchard J. Systematic review: Annual incidence of ACL injury and surgery in various populations. Res Sports Med 2012;20:157-79.
van Yperen DT, Meuffels DE, Reijman M. Twenty-year follow-up study comparing operative versus nonoperative treatment of anterior cruciate ligament ruptures in high-level athletes: Response. Am J Sports Med 2018;46:NP57-8.
Monk AP, Davies LJ, Hopewell S, Harris K, Beard DJ, Price AJ. Surgical versus conservative interventions for treating anterior cruciate ligament injuries. Cochrane Database Syst Rev 2014;4:CD011166.
Mohtadi NG, Chan DS, Dainty KN, Whelan DB. Patellar tendon versus hamstring tendon autograft for anterior cruciate ligament rupture in adults. Cochrane Database Syst Rev 2011;9:CD005960.
Monk AP, Davies LJ, Hopewell S, Harris K, Beard DJ, Price AJ. Surgical versus conservative interventions for treating anterior cruciate ligament injuries. Cochrane Database Syst Rev 2016;4:CD011166.
Lu HZ, Liu ZN, Zhang DJ, Ye YL. Treatment of unstable chronic anterior cruciate ligament-deficient knee with osteoarthritis. Zhonghua Yi Xue Za Zhi 2012;92:472-5.
Linko E, Harilainen A, Malmivaara A, Seitsalo S. Surgical versus conservative interventions for anterior cruciate ligament ruptures in adults. Cochrane Database Syst Rev 2005;2:CD001356.
Frobell RB, Roos HP, Roos EM, Roemer FW, Ranstam J, Lohmander LS. Treatment for acute anterior cruciate ligament tear: Five year outcome of randomised trial. BMJ 2013;346:f232.
Frobell RB, Roos EM, Roos HP, Ranstam J, Lohmander LS. A randomized trial of treatment for acute anterior cruciate ligament tears. N Engl J Med 2010;363:331-42.
Myer GD, Ford KR, Hewett TE. The effects of gender on quadriceps muscle activation strategies during a maneuver that mimics a high ACL injury risk position. J Electromyogr Kinesiol 2005;15:181-9.
Orchard JW. Why does Australia have a higher rate of knee reconstruction surgery than New Zealand (and Scandinavia) and what can we do about it? J Sci Med Sport 2011;14:276-7.
Delincé P, Ghafil D. Anterior cruciate ligament tears: Conservative or surgical treatment? A critical review of the literature. Knee Surg Sports Traumatol Arthrosc 2012;20:48-61.
Smith TO, Postle K, Penny F, McNamara I, Mann CJ. Is reconstruction the best management strategy for anterior cruciate ligament rupture? A systematic review and meta-analysis comparing anterior cruciate ligament reconstruction versus non-operative treatment. Knee 2014;21:462-70.
Lysholm J, Gillquist J. Evaluation of knee ligament surgery results with special emphasis on use of a scoring scale. Am J Sports Med 1982;10:150-4.
Anderson AF, Irrgang JJ, Kocher MS, Mann BJ, Harrast JJ; International Knee Documentation Committee. The international knee documentation committee subjective knee evaluation form: Normative data. Am J Sports Med 2006;34:128-35.
Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligament injuries. Clin Orthop Relat Res 1985;198:43-9.
Arneja S, Leith J. Review article: Validity of the KT-1000 knee ligament arthrometer. J Orthop Surg (Hong Kong) 2009;17:77-9.
Maher CG, Sherrington C, Herbert RD, Moseley AM, Elkins M. Reliability of the PEDro scale for rating quality of randomized controlled trials. Phys Ther 2003;83:713-21.
Tsoukas D, Fotopoulos V, Basdekis G, Makridis KG. No difference in osteoarthritis after surgical and non-surgical treatment of ACL-injured knees after 10 years. Knee Surg Sports Traumatol Arthrosc 2016;24:2953-9.
van Meer BL, Meuffels DE, van Eijsden WA, Verhaar JA, Bierma-Zeinstra SM, Reijman M. Which determinants predict tibiofemoral and patellofemoral osteoarthritis after anterior cruciate ligament injury? A systematic review. Br J Sports Med 2015;49:975-83.
Guyatt GH, Sackett DL, Sinclair JC, Hayward R, Cook DJ, Cook RJ. Users' guides to the medical literature. IX. A method for grading health care recommendations. Evidence-based medicine working group. JAMA 1995;274:1800-4.
Slavin RE. Best evidence synthesis: An intelligent alternative to meta-analysis. J Clin Epidemiol 1995;48:9-18.
van Tulder M, Furlan A, Bombardier C, Bouter L; Editorial Board of the Cochrane Collaboration Back Review Group. Updated method guidelines for systematic reviews in the Cochrane collaboration back review group. Spine (Phila Pa 1976) 2003;28:1290-9.
Mihelic R, Jurdana H, Jotanovic Z, Madjarevic T, Tudor A. Long-term results of anterior cruciate ligament reconstruction: A comparison with non-operative treatment with a follow-up of 17-20 years. Int Orthop 2011;35:1093-7.
Meuffels DE, Favejee MM, Vissers MM, Heijboer MP, Reijman M, Verhaar JA. Ten year follow-up study comparing conservative versus operative treatment of anterior cruciate ligament ruptures. A matched-pair analysis of high level athletes. Br J Sports Med 2009;43:347-51.
Sandberg R, Balkfors B, Nilsson B, Westlin N. Operative versus non-operative treatment of recent injuries to the ligaments of the knee. A prospective randomized study. J Bone Joint Surg Am 1987;69:1120-6.
Gelber AC, Hochberg MC, Mead LA, Wang NY, Wigley FM, Klag MJ. Joint injury in young adults and risk for subsequent knee and hip osteoarthritis. Ann Intern Med 2000;133:321-8.
Felson DT, Lawrence RC, Dieppe PA, Hirsch R, Helmick CG, Jordan JM, et al.
Osteoarthritis: New insights. Part 1: The disease and its risk factors. Ann Intern Med 2000;133:635-46.
Tashman S, Collon D, Anderson K, Kolowich P, Anderst W. Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:975-83.
Lin SH, Wang TC, Lai CF, Tsai RY, Yang CP, Wong CS. Association of anterior cruciate ligament injury with knee osteoarthritis and total knee replacement: A retrospective cohort study from the Taiwan National Health Insurance Database. PLoS One 2017;12:e0178292.
Petersen W. Does ACL reconstruction lead to degenerative joint disease or does it prevent osteoarthritis? How to read science. Arthroscopy 2012;28:448-50.
Kessler MA, Behrend H, Henz S, Stutz G, Rukavina A, Kuster MS. Function, osteoarthritis and activity after ACL-rupture: 11 years follow-up results of conservative versus reconstructive treatment. Knee Surg Sports Traumatol Arthrosc 2008;16:442-8.
Harris KP, Driban JB, Sitler MR, Cattano NM, Balasubramanian E, Hootman JM, et al.
Tibiofemoral osteoarthritis after surgical or nonsurgical treatment of anterior cruciate ligament rupture: A systematic review. J Athl Train 2017;52:507-17.
McDaniel WJ Jr., Dameron TB Jr. Untreated ruptures of the anterior cruciate ligament. A follow-up study. J Bone Joint Surg Am 1980;62:696-705.
Hawkins RJ, Misamore GW, Merritt TR. Followup of the acute nonoperated isolated anterior cruciate ligament tear. Am J Sports Med 1986;14:205-10.
Grindem H, Eitzen I, Engebretsen L, Snyder-Mackler L, Risberg MA. Nonsurgical or surgical treatment of ACL injuries: Knee function, sports participation, and knee reinjury: The delaware-oslo ACL cohort study. J Bone Joint Surg Am 2014;96:1233-41.
Bak K, Jørgensen U, Ekstrand J, Scavenius M. Reconstruction of anterior cruciate ligament deficient knees in soccer players with an iliotibial band autograft. A prospective study of 132 reconstructed knees followed for 4 (2-7) years. Scand J Med Sci Sports 2001;11:16-22.
Ardern CL, Webster KE, Taylor NF, Feller JA. Return to sport following anterior cruciate ligament reconstruction surgery: A systematic review and meta-analysis of the state of play. Br J Sports Med 2011;45:596-606.
Bjordal JM, Arnły F, Hannestad B, Strand T. Epidemiology of anterior cruciate ligament injuries in soccer. Am J Sports Med 1997;25:341-5.
Myklebust G, Holm I, Maehlum S, Engebretsen L, Bahr R. Clinical, functional, and radiologic outcome in team handball players 6 to 11 years after anterior cruciate ligament injury: A follow-up study. Am J Sports Med 2003;31:981-9.
Roos H, Ornell M, Gärdsell P, Lohmander LS, Lindstrand A. Soccer after anterior cruciate ligament injury – An incompatible combination? A national survey of incidence and risk factors and a 7-year follow-up of 310 players. Acta Orthop Scand 1995;66:107-12.
Noyes FR, Matthews DS, Mooar PA, Grood ES. The symptomatic anterior cruciate-deficient knee. Part II: The results of rehabilitation, activity modification, and counseling on functional disability. J Bone Joint Surg Am 1983;65:163-74.
Lohmander LS, Atley LM, Pietka TA, Eyre DR. The release of crosslinked peptides from type II collagen into human synovial fluid is increased soon after joint injury and in osteoarthritis. Arthritis Rheum 2003;48:3130-9.
Lohmander LS, Englund PM, Dahl LL, Roos EM. The long-term consequence of anterior cruciate ligament and meniscus injuries: Osteoarthritis. Am J Sports Med 2007;35:1756-69.
Leys T, Salmon L, Waller A, Linklater J, Pinczewski L. Clinical results and risk factors for reinjury 15 years after anterior cruciate ligament reconstruction: A prospective study of hamstring and patellar tendon grafts. Am J Sports Med 2012;40:595-605.
[Table 1], [Table 2]