- Open Access
Protocol for the systematic review of return-to-activity criteria in adolescent patients following an anterior cruciate ligament reconstruction
Systematic Reviews volume 11, Article number: 93 (2022)
Anterior cruciate ligament (ACL) rupture is a debilitating knee injury associated with sequela such as joint instability and progressive degeneration. Unfortunately, following surgical ACL reconstruction in adolescents, the rates of ACL graft failure range from 17 to 19%. A contributing factor to the high reinjury rate in this population may be the limited evidence regarding appropriate criteria for allowing unrestricted return-to-activities (RTA) postoperatively. Several systematic reviews have already sought to develop a consensus on what criteria should be utilized for releasing patients to unrestricted sports activities; however, these reviews have focused on adult populations, a group at much lower risk for reinjury. Our objective is to systematically examine the literature and identify the criteria used when determining unrestricted RTA following an ACL reconstruction in an adolescent population.
Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic search will be performed of the MEDLINE/PubMed, Cochrane, Embase, CINAHL, and SPORTDiscus electronic databases. Searches will be conducted from January 1, 2000, until submission of the final review. Studies will be identified that include adolescent patients (10–18 years old) undergoing a primary ACL reconstruction and which have specified the criteria used to determine RTA. Each article will be independently screened by two reviewers. To supplement the electronic database search, citations within all included studies will be manually reviewed. Reviewers will record the RTA assessment utilized and the rates of ACL reinjury through a standardized data extraction sheet. Reviewers will resolve full-text screening and data extraction disagreements through discussion. Synthesis of the collected data will focus on compiling and mapping the most commonly used types of RTA criteria.
This systematic review will determine the most commonly used RTA criteria in adolescent patients post-ACL reconstruction. This will help future interventions build more effective adolescent-specific RTA assessments through the validation of current RTA criteria as well as the implementation of new criteria according to the identified literature gaps.
Injuries to the anterior cruciate ligament (ACL) are increasing in prevalence in the adolescent population (10-18 years old) [1,2,3], with females aged 13-17 years possessing the highest injury incidence of any sex-age strata . Following an ACL injury, a surgical reconstruction is typically pursued to restore knee stability and enable resumption of pre-injury activities . However, only two-thirds of adolescent patients will return to their pre-injury levels of activity . Furthermore, once an athlete has returned-to-sports, the risk for a subsequent ACL injury is considerably higher compared to the initial injury [7,8,9]. Approximately 17-19% of adolescent athletes will re-tear their ACL within two years following an ACL reconstruction [8, 10, 11], with greater than 30% of second ACL injuries occurring within the first 20 sport exposures following return-to-sports . There is also a discrepancy between re-injury rates in adult and adolescent patients, with higher rates of second ACL injuries and revision surgeries in patients less than 18 years old, compared to older cohorts [9, 12].
A contributing factor to the high re-injury rates in the adolescent populations may be the lack of consensus regarding which criteria should be used when assessing readiness for unrestricted return-to-activity (RTA) . RTA criteria typically refers to a set of tests, or test batteries, designed to incorporate a number of risk factors, the results of which can be used to clear athletes for RTA at the final stage of rehabilitation . Despite the continuing development of milestone-based post-operative rehabilitation programs for young athletes , considerable debate remains regarding the optimal criteria for RTA clearance. Previous reviews have identified the most frequently used factors for determining RTA clearance following an ACL reconstruction , as well as the most commonly reported objective criteria . Although these reviews have provided clinically meaningful findings, the studies focused primarily on an adult population, with no such evidence existing in adolescent patients. Considering the higher rates of re-injury in this population [8, 10, 11] and the identification of age-specific risk factors for ACL injury [18, 19], the treatment of ACL injuries in adolescent patients must be considered separately from adults. Notably, a recent scoping review provided an overview of the current evidence for RTA tests following an ACL reconstruction in adolescent patients; however, they did not identify what RTA tests are being used in clinical practice . In addition, a recent survey of paediatric orthopaedic surgeons  and a review of children’s hospitals rehabilitation programs  found that the mode of testing and criteria thresholds for activity advancement varied considerably across hospitals and surgeons. Although these findings provide an estimate for the current landscape of surgeon practice , they may not accurately reflect RTA criteria used in scientific literature. By summarizing the scientific literature, future research can validate and adapt current RTA criteria, or target new areas for RTA development according to the identified literature gaps.
The primary goal of this systematic review is to determine the criteria used when assessing RTA readiness post-ACL reconstruction in adolescent patients, as well as how commonly each criteria is used. For each article we will determine:
How many RTA criteria were used? Considering the psychological [22,23,24], biomechanical [25,26,27,28,29], and biological  changes that occur following an ACL reconstruction, it is likely that multiple metrics are required when assessing RTA readiness.
Was the criteria time-based, subjective or objective? Previous systematic reviews have shown that 42% of articles used time from ACL reconstruction as the only criterion when evaluating RTA . This review will determine if these proportions are consistent in an adolescent population.
What functional test or benchmark was met prior to RTA? In order to validate current RTA criteria or target new areas for RTA development, the literature must be examined to determine the current standard-of-practice for RTA assessment.
We will also explore secondary outcomes, including determining the re-injury rate associated with each RTA assessment, as well as recording the most frequently used functional tasks and limb symmetry indexes (LSI).
The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed when preparing this systematic review protocol (see Additional file 1 ;). Any protocol modifications made during the conduct of the review will be described in the publication of the final report.
An experienced university librarian assisted with the creation and execution of the search strategy (see Additional file 2). The search strategy draws upon existing search strings previously used in systematic reviews of ACL reconstruction RTA criteria [16, 17, 33]. Search terms will be entered under three concepts: concept 1 included terms “child,” “pediatric,” and “adolescent”; concept 2 included terms “anterior cruciate ligament reconstruction,” “ACL repair,” and “ACL surgery”; and concept 3 included terms “return to sport,” “return to play,” and “return to athletics.” Terms within each concept will be combined with the OR Boolean operator, and the three concepts will be combined with the AND Boolean operator. Where possible, terms will be mapped to medical subject headings and searched using keywords. The electronic databases MEDLINE, Embase, CINAHL, SPORTDiscus, and Cochrane Central Register of Controlled Trials will be searched from January 1, 2000, until submission of the final manuscript. The combination of these databases produces an estimated 97% recall of all primary studies involving orthopedic surgical interventions . The search strategy will restrict citations to studies written in English and French. Although articles in other languages will be excluded, a list of the potentially relevant studies will be provided in a supplement of the final report for interested readers. To supplement the electronic database search, citations within all included studies will be manually reviewed to identify any additional studies omitted during the initial database searches.
Study eligibility criteria
We set the eligibility criteria for the review according to the PICOS (population, intervention, comparison, outcomes, study design) framework . We will include studies that meet the following criteria:
Population: All adolescent patients who have undergone a primary ACL reconstructive surgery will be considered (10–18 years old at the time of surgery), without exclusions relative to patient sex or activity level.
Intervention: A primary ACL reconstructive surgery. We will exclude articles where the patient is undergoing a revision ACL reconstruction. We will not restrict articles based on the graft type or surgical technique used.
Comparators: Contralateral limb of patients with ACL reconstruction or patients unaffected by ACL rupture (healthy controls).
Outcomes: We are interested in studies that specify the RTA criteria utilized following an ACL reconstruction. Studies will be excluded if they do not specify the criteria with enough detail to determine if the criteria were subjective or objective. From each articles, we will extract (i) how many criteria were used, (ii) the type of criteria (time-based, subjective, or objective), and (iii) the specific test or benchmark used.
Study design: Study designs of interest will include observational studies (including cross-sectional studies and cohort studies) or randomized control trials. We will exclude conference proceedings, surgical techniques, technical notes, letters to editors, case reports, clinical commentaries, and review articles.
Publication details from all studies will be exported to Covidence systematic review software (Veritas Health Innovation, Melbourne, Australia; www.covidence.org), and duplicates will be removed. Study selection will be performed in two stages; screening at stage one will encompass reviewing titles and abstracts identified from the electronic searches. Two reviewers will independently review the title and abstract of each article identified through the literature search. All articles that meet the subject matter criteria described above will be included at this stage. Stage two screening will evaluate the full-text articles against the complete eligibility criteria, among those deemed potentially relevant during stage 1. Each article will be screened independently by two reviewers. Disagreements among reviewers will be decided through discussion, and a senior team member will be consulted if a disagreement can not be resolved. In addition, the authors of any studies with potential duplicate participants (e.g., same institution, overlapping patient enrollment dates) will be contacted to determine patient overlap. For articles with >50% patient overlap, the study with the larger patient population will be included . Before each screening stage, we will calibrate the reviewers to ensure consistent application of eligibility criteria. We will continue the calibration until we reach ~95% agreement between the screeners. Finally, a PRISMA flow diagram will be prepared to document the study selection process in the final publication .
Assessment of study quality
The quality of each study, including the risk of bias, will be assessed using the methodological index for non-randomized studies (MINORS) . MINORS is a validated instrument developed because of the problems faced by clinicians given the lack of randomized surgical trials and the large number of observational studies in surgery . The MINORS tool applies a scoring system across 12 items to assess the methodological and scientific value of studies, with the first 8 items relating to non-comparative studies and all 12 items relevant for comparative studies. The quality of each study will be independently assessed by two reviewers. Any disagreements will be resolved through discussion, with the involvement of a third reviewer if necessary. Articles will not be excluded on the basis of the assessment.
A data extraction form will be developed and pilot tested using a sample of 5 articles and revised as necessary. One reviewer will extract the data, and two reviewers will verify the completeness of the extraction. Table 1 lists the items for data extraction. These items will constitute the elements of the standardized data extraction form used by reviewers.
Continuous variables will be recorded as the mean ± standard deviation (SD). If the mean or SD is not reported, it will be estimated according to a previously validated formula: (higher range value — lower range value)/4 or interquartile range/1.35 [38, 39]. Categorical variables (e.g., reinjury rate) will be recorded as frequencies with percentages. If identical RTA criteria are used for multiple cohorts within the same paper (e.g., male and female), then demographic (e.g., age range) will be combined and recorded together . The primary outcome of interest was the RTA assessment used by each study when determining clinical clearance to full activities, recorded according to the following: (i) how many criteria were used; (ii) whether the criteria were time-based, subjective, or objective; and (iii) the specific test or benchmark used. As part of our secondary outcomes, we will record the reinjury rate associated with each RTA battery, as well as the most frequently used functional tasks.
The ACL is the most frequently damaged knee ligament , with rates continuing to rise among active adolescent athletes [1,2,3]. Despite surgical interventions aimed at restoring mechanical integrity , approximately 17–19% of adolescent athletes will sustain a second ACL injury within 2 years following an ACL reconstruction [8, 10, 11]. Given the high reinjury rate in this population [9, 12], and the potential for adverse long-term health consequences following an ACL injury [42,43,44,45,46,47,48], there is an urgent need to develop adolescent-specific RTA. This systematic review will identify the most commonly used criteria when determining unrestricted RTA following an adolescent ACL reconstruction. The results of this review will allow future interventions to build more effective adolescent-specific RTA assessments through the identification and validation of current RTA criteria and the implementation of new criteria according to the identified literature gaps.
A particular challenge for the present review will be the small number of studies conducted on adolescent ACL injuries. In anticipation of this, we made use of validated search strings developed in consultation with an experienced university librarian to maximize the coverage while retaining a feasible number of articles for screening. We have also included a secondary search of the included articles to identify any additional studies omitted during the initial database searches. Only studies which specify the adolescent-specific RTA criteria will be included in the final review. In addition, there may be variability in the descriptions of the utilized RTA criteria. Studies will only be included if they specified the RTA criteria with enough detail to determine if the criteria were subjective or objective. This will be independently assessed by two reviewers, with disagreement resolved through discussion. However, there is potential that some of the excluded investigations did in fact measure RTA criteria but did not include this information in the article. Finally, although the ACL reinjury rate will be extracted from each article, we may not be able to compare the ACL failure rates associated with specific RTA criteria. This type of analysis would require a separate investigation in which cohorts are carefully matched for graft type, sex ratio, chronicity of injury, concomitant injuries, articular cartilage deterioration, postoperative sports activity level, and time of follow-up. Therefore, future studies may be required to determine if the reported RTA criteria are effective in reducing ACL reinjury rates in an adolescent population.
We will publish the results of this review in a sports medicine research journal with the intent of maximizing outreach to healthcare professional and researchers pursuing research on ACL management. In addition to a peer-reviewed publication, we will also draft lay summaries to post online and for distribution to key societies, patient groups, and policymakers.
Availability of data and materials
The datasets generated and/or analyzed during the current study will be available in the Open Science Foundation repository.
Anterior cruciate ligament
Methodological index for non-randomized studies
Population, intervention, comparison, outcomes, and study design
Preferred Reporting Items for Systematic Reviews and Meta-Analyses
Return to activity
Gornitzky AL, Lott A, Yellin JL, Fabricant PD, Lawrence JT, Ganley TJ. Sport-specific yearly risk and incidence of anterior cruciate ligament tears in high school athletes: a systematic review and meta-analysis. Am J Sports Med. 2016;44:2716–23.
Beck N, Lawrence J, Nordin J, DeFor T, Tompkins M. ACL tears in school-aged children and adolescents over 20 years. Pediatrics. 2017;139.
Shea KG, Pfeiffer R, Wang JH, Curtin M, Apel PJ. Anterior cruciate ligament injury in pediatric and adolescent soccer players: an analysis of insurance data. J Pediatr Orthop. 2004;24:623–8.
Herzog MM, Marshall SW, Lund JL, Pate V, Mack CD, Spang JT. Incidence of anterior cruciate ligament reconstruction among adolescent females in the United States, 2002 through 2014. JAMA Pediatr. 2017;171:808–10.
Feucht MJ, Cotic M, Saier T, Minzlaff P, Plath JE, Imhoff AB, et al. Patient expectations of primary and revision anterior cruciate ligament reconstruction. Knee Surgery, Sport Traumatol Arthrosc. 2016;24:201–7.
Morgan MD, Salmon LJ, Waller A, Roe JP, Pinczewski LA. Fifteen-year survival of endoscopic anterior cruciate ligament reconstruction in patients aged 18 years and younger. Am J Sports Med. 2016;44:384–92.
Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of contralateral and ipsilateral anterior cruciate ligament (ACL) injury after primary ACL reconstruction and return to sport. Clin J Sport Med. 2012;22:116–21.
Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of second ACL injuries 2 years after primary ACL reconstruction and return to sport. Am J Sports Med. 2014;42:1567–73.
Shelbourne KD, Gray T, Haro M. Incidence of subsequent injury to either knee within 5 years after anterior cruciate ligament reconstruction with patellar tendon autograft. Am J Sports Med. 2009;37:246–51.
Dekker TJ, Godin JA, Dale KM, Garrett WE, Taylor DC, Riboh JC. Return to sport after pediatric anterior cruciate ligament reconstruction and its effect on subsequent anterior cruciate ligament injury. J Bone Jt Surg - Am. 2017;99:897–904.
Law MA, Ko YA, Miller AL, Lauterbach KN, Hendley CL, Johnson JE, et al. Age, rehabilitation and surgery characteristics are re-injury risk factors for adolescents following anterior cruciate ligament reconstruction. Phys Ther Sport. 2021;49:196–203 Churchill Livingstone.
Astur DC, Cachoeira CM, da Silva VT, Debieux P, Kaleka CC, Cohen M. Increased incidence of anterior cruciate ligament revision surgery in paediatric verses adult population. Knee Surgery, Sport Traumatol Arthrosc. 2018;26:1362–6.
Greenberg EM, Greenberg ET, Albaugh J, Storey E, Ganley TJ. Anterior cruciate ligament reconstruction rehabilitation clinical practice patterns: a survey of the PRiSM society. Orthop J Sports Med. 2019;7.
Dingenen B, Gokeler A. Optimization of the return-to-sport paradigm after anterior cruciate ligament reconstruction: a critical step back to move forward. Sports Med. 2017;47:1487–500.
Yellin JL, Fabricant PD, Gornitzky A, Greenberg EM, Conrad S, Dyke JA, et al. Rehabilitation following anterior cruciate ligament tears in children: a systematic review. JBJS Rev. 2016;4.
Barber-Westin SD, Noyes FR. Factors used to determine return to unrestricted sports activities after anterior cruciate ligament reconstruction. Arthrosc J Arthrosc Relat Surg. 2011;27:1697–705.
Barber-Westin SD, Noyes FR. Objective criteria for return to athletics after anterior cruciate ligament reconstruction and subsequent reinjury rates: a systematic review. Phys Sportsmed. 2011;39:100–10.
Myer GD, Sugimoto D, Thomas S, Hewett TE. The influence of age on the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: a meta-analysis. Am J Sports Med. 2013;41:203–15.
Paterno MV, Huang B, Thomas S, Hewett TE, Schmitt LC. Clinical factors that predict a second ACL injury after ACL reconstruction and return to sport: preliminary development of a clinical decision algorithm. Orthop J Sports Med. 2017;5.
Dietvorst M, Brzoskowski MH, Van Der Steen M, Delvaux E, Janssen RPA, Melick NV. Limited evidence for return to sport testing after ACL reconstruction in children and adolescents under 16 years: a scoping review. Journal of experimental orthopaedics. 2020;7:1–8.
Forrester LA, Schweppe EA, Popkin CA. Variability in rehabilitation protocols following pediatric anterior cruciate ligament (ACL) reconstruction. Phys Sportsmed. 2019;47:448–54.
Christino MA, Fantry AJ, Vopat BG. Psychological aspects of recovery following anterior cruciate ligament reconstruction. J Am Acad Orthop Surg. 2015;23:501–9.
Brewer BW, Cornelius AE, Stephan Y, Van Raalte J. Self-protective changes in athletic identity following anterior cruciate ligament reconstruction. Psychol Sport Exerc. 2010;11:1–5.
Langford JL, Webster KE, Feller JA. A prospective longitudinal study to assess psychological changes following anterior cruciate ligament reconstruction surgery. Br J Sports Med. 2009;43:377–81.
Shimizu T, Cheng Z, Samaan MA, Tanaka MS, Souza RB, Li X, et al. Increases in joint laxity after anterior cruciate ligament reconstruction are associated with sagittal biomechanical asymmetry. Arthrosc J Arthrosc Relat Surg. 2019;35:2072–9.
Messer DJ, Shield AJ, Williams MD, Timmins RG, Bourne MN. Hamstring muscle activation and morphology are significantly altered 1–6 years after anterior cruciate ligament reconstruction with semitendinosus graft. Knee Surgery, Sport Traumatol Arthrosc. 2020;28:733–41.
Kaur M, Cury Ribeire D, Theis J-C, Webster KE, Sole G. Movement patterns of the knee during gait following ACL reconstruction: a systematic review and meta-analysis. Sports Med. 2016;46:1869–95.
Bourne MN, Bruder AM, Mentiplay BF, Carey DL, Patterson BE, Crossley KM. Eccentric knee flexor weakness in elite female footballers 1–10 years following anterior cruciate ligament reconstruction. Phys Ther Sport. 2019;37:144–9.
Slater LV, Hart JM, Kelly AR, Kuenze CM. Progressive changes in walking kinematics and kinetics after anterior cruciate ligament injury and reconstruction: a review and meta-analysis. J Athl Train. 2017;52:847–60.
Harkey MS, Luc BA, Golightly YM, Thomas AC, Driban JB, Hackney AC, et al. Osteoarthritis-related biomarkers following anterior cruciate ligament injury and reconstruction: a systematic review. Osteoarthr Cartil. 2015;23:1–12.
Burgi CR, Peters S, Ardern CL, Magill JR, Gomez CD, Sylvain J, et al. Which criteria are used to clear patients to return to sport after primary ACL reconstruction? A scoping review. Br J Sports Med. 2019;53:1154–61.
Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred Reporting Items for Systematic Reviews and Meta-Analyses: the PRISMA statement. Annals of Internal Medicine. 2009;151:264–9.
Abrams GD, Harris JD, Gupta AK, McCormick FM, Bush-Joseph CA, Verma NN, et al. Functional performance testing after anterior cruciate ligament reconstruction. Orthop J Sports Med. 2014;2.
Slobogean GP, Verma A, Giustini D, Slobogean BL, Mulpuri K. MEDLINE, Embase, and Cochrane index most primary studies but not abstracts included in orthopedic meta-analyses. J Clin Epidemiol. 2009;62:1261–7.
O’Connor D, Green S, Higgins JD. Defining the review question and developng criteria for including studies. In: Cochrane handbook for systematic reviews of interventions: Cochrane book series; 2008. p. 81–94.
Harris JD, Quatman CE, Manring MM, Siston RA, Flanigan DC. How to write a systematic review. Am J Sports Med. 2014;42:2761–8.
Arem Lim KS, Mile Ini EN, Amien Orestier DF, Abrice Wiatkowski FK, Ves Anis YP, Acques Hipponi JC, et al. Methodological index for non-randomized studies (INORS): development and validation of a new instrument. ANZ J Surg. 2003;73:712–6.
Higgins JP, Deeks JJ, Altman DG. Special Topics in Statistics. Cochrane Handb Syst Rev Interv Cochrane B Ser. London: Wiley; 2008. p. 481–529.
Higgins JP, Deeks JJ. Selecting studies and collecting data. In: Cochrane handbook for systematic reviews of interventions. London: Wiley; 2008. p. 151–85.
Higgins JP, Li T, Deeks JJ. Choosing effect measures and computing estimates of effect. In: Cochrane handbook for systematic reviews of interventions: Wiley; 2019. p. 143–76.
Majewski M, Susanne H, Klaus S. Epidemiology of athletic knee injuries: a 10-year study. Knee. 2006;13:184–8.
Acevedo RJ, Rivera-Vega A, Miranda G, Micheo W. Anterior cruciate ligament injury: identification of risk factors and prevention strategies. Curr Sports Med Rep. 2014;13:186–91.
Hame SL, Alexander RA. Knee osteoarthritis in women. Curr Rev Musculoskelet Med. 2013;6:182–7.
Oberländer KD, Brüggemann G-P, Höher J, Karamanidis K. Knee mechanics during landing in anterior cruciate ligament patients: a longitudinal study from pre- to 12 months post-reconstruction. Clin Biomech. 2014;29:512–7.
Hewett T, Myer G, Kiefer A, Ford K. Longitudinal increases in knee abduction moments in females during adolescent growth. Med Sci Sports Exerc. 2015;47:2579–85.
Simon D, Mascarenhas R, Saltzman BM, Rollins M, Bach BR, MacDonald P. The relationship between anterior cruciate ligament injury and osteoarthritis of the knee. Adv Orthop. 2015;2015.
Sugimoto D, Alentorn-Geli E, Mendiguchía J, Samuelsson K, Karlsson J, Myer G. Biomechanical and neuromuscular characteristics of male athletes: implications for the development of anterior cruciate ligament injury prevention programs. Sports Med. 2015;45:809–22.
Whittaker JL, Woodhouse LJ, Nettel-Aguirre A, Emery CA. Outcomes associated with early post-traumatic osteoarthritis and other negative health consequences 3–10 years following knee joint injury in youth sport. Osteoarthr Cartil. 2015;23:1122–9.
The authors would like to thank Nigèle Langois for her help in creating the literature search strategy.
The authors would like to thank the Ontario Graduate Scholarship, Natural Sciences and Engineering Research Council of Canada, the Arthroscopy Association of North America, CHEO Research Institute, and the University of Ottawa Department of Surgery for their support.
Ethics approval and consent to participate
Not applicable, because the manuscript does not involve human participants.
Consent for publication
Not applicable, because the manuscript does not report an individual participant’s data.
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Romanchuk, N.J., Livock, H., Lukas, K.J. et al. Protocol for the systematic review of return-to-activity criteria in adolescent patients following an anterior cruciate ligament reconstruction. Syst Rev 11, 93 (2022). https://doi.org/10.1186/s13643-022-01965-w
- Anterior cruciate ligament
- Anterior cruciate ligament reconstruction
- Return to activity
- Functional tests