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Return to Sport After Anterior Cruciate Ligament Reconstruction in the Skeletally Immature Athlete

Chicorelli, Anne M. DO, MPH; Micheli, Lyle J. MD; Kelly, Michael BS; Zurakowski, David PhD; MacDougall, Robert BS

Clinical Journal of Sport Medicine: July 2016 - Volume 26 - Issue 4 - p 266–271
doi: 10.1097/JSM.0000000000000275
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Objective: Determine the percentage of skeletally immature athletes returning to sports after anterior cruciate ligament (ACL) injury and reconstruction.

Design: Retrospective case series.

Setting: Boston Children's Hospital Division of Sports Medicine.

Patients: Eligible participants were identified by chart review. Males and females aged ≤14 year old who were greater than 2 years after ACL reconstruction surgery seen between January 2001 and May 2009. A total of 250 patients completed the questionnaires.

Assessment of Risk Factors: Age, sex, mechanism, and sport played at time of ACL injury.

Main Outcome Measures: Response to the survey was 75% (250 of 333) which was analyzed using descriptive statistics to provide a summary of the study cohort. Kaplan–Meier survivorship analysis was applied to determine time to return to sports participation after ACL reconstruction with Greenwood formula used to calculate 95% confidence intervals around the estimated percentage returning at 6, 9, 12, 18, and 24-month follow-up.

Results: After undergoing ACL reconstruction, 96% of skeletally immature athletes are able to return to sports at the same skill level. Median time to return to sports was 9 months postoperative, with most athletes returning to sports (85%) by 12 months.

Conclusions: After undergoing ACL reconstruction, most child athletes are able to return to sports and 50% of these athletes return within 9 months after surgery.

Clinical Relevance: After undergoing ACL reconstruction, 96% of athletes ≤14 year old are able to return to sports at the same skill level. Median time to return to sports was 9 months postoperative, with most athletes returning to sports (85%) by 12 months. In our study, patients cited physical limitation, loss of interest in sport, and fear of reinjury as reasons for not returning to previous level of sport. Return to sport may be improved by additional research into sports-specific training and rehabilitation in this cohort.

*Orthopaedics and Sports Medicine, The Ohio State Medical Center, Wooster, Ohio;

Division of Sports Medicine, Boston Children's Hospital, Boston, Massachusetts; and

Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts.

Corresponding Author: Lyle J. Micheli, MD, Division of Sports Medicine, Boston Children's Hospital, 319 Longwood Ave, 6th Floor, Boston, MA 02115 (lyle.micheli@childrens.harvard.edu).

The authors report no conflicts of interest.

Received August 14, 2014

Accepted February 10, 2015

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INTRODUCTION

The knee is one of the most common sites of injury in the skeletally immature athletes.1 Treatment of anterior cruciate ligament (ACL) injuries within this subpopulation is controversial.2 Whereas operative treatment may risk injury to the physis, nonoperative management may lead to functional instability which predisposes the athlete to potential meniscal and/or chondral damage.3,4 As children have increased both their participation and demands in sporting activities, so have parents and physicians increased their awareness of potential injuries.1,5

The diagnosis of ACL injury in skeletally immature athletes is being made with increased frequency.6,22 In 1986, Lipscomb and Anderson6 reported 3.4% of their ACL reconstructions were in young children. McCarroll et al,7 in 1988, reported an incidence of 3.3%. More recently estimates of ACL injury in skeletally immature show an incidence of 6.7% of total ACL and 30.8% of all youth knee injuries.2

There is a concern about damage to the growth plate with ACL reconstruction in the growing child.8 However, studies have shown good functional outcome, low revision rate and minimal risk of growth disturbance when special surgical consideration is made for the immature physis.9

In the skeletally immature athlete, there are several different possible ACL surgical options. Reconstruction can be either physeal sparing, transphyseal, or partial physeal sparing (usually femur). Brief popularized the physeal sparing transepiphyseal fixation,10 whereas Micheli et al11 combined intraarticular and extraarticular physeal sparing reconstruction using the iliotibial band technique with good functional outcomes. Studies have shown that transphyseal reconstruction performed in the correct population provides athletes closer to skeletal maturation excellent results with minimal risk to the growth plate.12–14

Our goal was to evaluate skeletally immature athletes who underwent ACL reconstruction to determine what percentage of them returned to sports, the timing of return to full sports participation, and if they returned to the same preinjury level of sport activity.

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METHODS

Approval was obtained from our institutional review board and then a chart review was performed of all patients ≤14 year old treated with ACL reconstruction at Boston Children's Hospital Division of Sports Medicine between January 2001 and June 2009.

The study design is a retrospective case series. Inclusion criteria into our study were males and females aged ≤14 year old who were greater than 2 years after ACL reconstruction surgery. After providing informed consent, the patients completed a questionnaire about their initial ACL injury, participation in sports at the time of injury, and return to sports after ACL reconstruction (Figures 1A, B). Initial questionnaire was mailed (1A) and follow-up questionnaire was by phone interview (1B).

FIGURE 1

FIGURE 1

Surgeons performed the reconstructions based on the algorithm for management of ACL injuries in skeletally immature patients used at Boston Children's Hospital at that time (Figure 2). Those who were skeletally immature as determined by bone age and/or Tanner staging were treated with iliotibial band reconstruction, whereas the Tanner 3 and 4 or bone age >13 years were treated with transphyseal hamstring autograft with metaphyseal fixation, however Tanner 5 were treated with autologous hamstring or patella tendon autograft with interference screw fixation.

FIGURE 2

FIGURE 2

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Statistical Analysis

Response to the survey was 75% (250 of 333) which were analyzed using descriptive statistics to provide a summary of the study cohort (Table). Kaplan–Meier survivorship analysis was applied to determine time to return to sports participation after ACL reconstruction with Greenwood formula used to calculate 95% confidence intervals (CIs) around the estimated percentage returning at 6, 9, 12, 18, and 24-month follow-up15 (Figure 3). Multivariable Cox proportional-hazards regression was used to evaluate whether time to return to sports participation was influenced by age, sex, body mass index (BMI), trauma as cause of injury, or type of surgical graft used. A separate analysis was performed using logistic regression modeling to predict return to sports at selected time points after ACL reconstruction for the 5 most common sports that patients returned to (basketball, soccer, football or rugby, baseball or softball, and skiing or snowboarding).16 Statistical analysis was performed using the IBM SPSS software package (version 21.0; IBM, Armonk, New York). Two-tailed values of P < 0.05 were considered statistically significant.17

TABLE. De

TABLE. De

FIGURE 3

FIGURE 3

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RESULTS

The study cohort consisted of 250 patients with a mean chronological age of 12.7 years (range, 6-14). There were 136 females (54%) and 114 males (46%) (Table). Mean BMI was 21.7 kg/m2, with a range between 14.5 and 35.8. Non–sport-related trauma was the cause of ACL injury in 24% of patients, whereas 28% of patients sustained their injuries playing soccer, 16% in basketball, 13% in football or rugby, and 5% skiing or snowboarding. Autologous hamstring graft was used in 54%, iliotibial band in 29%, patellar tendon in 12% and tibialis anterior allograft in 5%. A total of 239 (96%) patients eventually returned to sports participation with a Kaplan–Meier estimated median time of 9 months (95% CI, 8-10 months) after ACL reconstruction (Figure 3). At 12-month follow-up, 85% of patients had returned to sports (95% CI, 80%-90%).

The Cox regression model did not identify any significant predictors of time to return to sports, including age (P = 0.41), sex (P = 0.15), BMI (P = 0.98), trauma (P = 0.63), and type of graft (P = 0.81). Thus, the data suggest that independent of these other variables; the median time to return was 9 months.

Logistic regression analysis indicated comparable rates among the 5 most common sports (Figure 3). No significant differences were detected between the specific sports except that a lower percentage of football and rugby players returned to sports participation at 6 and 9-month follow-up compared with those in basketball, soccer, and skiing (all P < 0.05). Thus, although participation in football or rugby had slightly lower rates of patients returning at 6 and 9-month follow-up, these athletes had essentially equivalent return rates at 12 months and later.

Of the 250 patients who had completed the initial survey, with institutional review board approval, we attempted to contact them by mail to obtain additional information on (1) whether they returned to the same perceived preinjury level of play and (2) whether this level was maintained (Figure 1B). A total of 142 patients were reached by mail and answered our 2 questions (57%). Of the 142 patients, 43 (30%) said that they returned to a higher level of play compared with their preinjury level, 64 (45%) indicated that they returned to the same level of play, 31 (22%) said that they returned to a lower level of play, and 4 patients (1%) said they never returned to sports participation. Therefore, 107 of the 142 (75%) patients stated that they returned to at least the same level of play. A total of 42 of the 43 (98%) of those who returned to a higher level and 54 of 64 (84%) of those who returned to the same level were able to maintain that same level of play. However, only 19 of the 31 (62%) who had returned to a lower level of play were able to maintain that level. The follow-up mailings revealed that 3 in 4 patients who underwent ACL reconstruction were able to return to the same level or a higher level of sports, and 90% of these athletes (96 of 107) maintained that level of participation. We performed a multivariate logistic regression analysis to assess factors that might be predictive of return to play at the same or higher level versus a lower level and found that those who returned to the same or higher level were younger in age (P = 0.04), whereas sex (P = 0.87), BMI (P = 0.09), and cause (trauma vs sports related) of ACL injury (P = 0.65) were not significant predictive factors.

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DISCUSSION

Our data provide the greatest number of return to sports in young athletes in an outcome-based study to date. Our primary goal is to safely restore athletes to their preinjury level of activity while minimizing growth plate damage by strict adherence to our protocol during ACL reconstruction. The challenge in reconstructing ACL tears in this age group is the risk that surgery poses to the tibia and femur physeal plates and resultant growth disturbance(s). Studies have shown that such risk does exist but failure to reconstruct portends poorer prognosis to the longevity and health of the injured knee.5,18,19 Many young athletes undergo ACL reconstruction surgery to protect the articular cartilage and meniscus and decrease the risk of developing premature knee osteoarthritis.20 A second goal of ACL surgery in the skeletally immature athlete is to allow an earlier return to sports than those patients who forego surgery until skeletally mature. Historically, the skeletally immature athlete with an ACL injury has been restricted from sports until skeletally mature and then be given the option to undergo ACL reconstruction surgery. Unfortunately, a high percentage of these sustain meniscal injury before attaining skeletal maturity. Wearing a brace to allow activity after an ACL tear does not prevent subsequent injury, as meniscal tears and instability have been documented after return to sports.18,20

Delaying or not reconstructing ACL tears may also have long-term consequences. Janarv reported that 68% of those who tried nonoperative intervention eventually opted for reconstruction, and those remaining who were not reconstructed had significantly decreased activity levels.24 Children who participate in physical activities at a young age are more likely to continue to be active as adults, which may reduce the risk of early morbidity and mortality. Consequently, delaying reconstruction may affect both a person's quality of life and limit their future participation in sports.25 Organized athletic participation as youth has been shown to promote athletic activity as adults. Tammelin et al26 followed almost 8000 young athletes and found that participation in sports was associated with high level of physical activity in later life. He also concluded that adolescent participation in the intensive endurance sports, and some sports that require and encourage diversified sports skills, seemed to be most beneficial with respect to the enhancement of adult physical activity. Telama et al27 reported that youth playing at a high level of physical activity was a significant prognostic indicator of adult activity. Studies have also shown that higher self-esteem may be associated with sports participation during the formative years of 9 to 14 years of age.28,29

Although more ACLs are being diagnosed and reconstructed in skeletally immature athletes, there are few data documenting return to organized sports and at what level. Studies in adults returning to sports after ACL reconstruction show that 53%-62% return to their previous level of play.19,21,25,30

Past studies have looked at return to sports for skeletally immature athletes after ACL reconstruction surgery. Shelbourne et al's review of ACL reconstruction in skeletally immature patients reported 55 of 60 (92%) returned to preinjury sports participation.20,23 Fuchs et al reported 9 of 10 patients treated with patellar tendon allograft in children aged 9 to 15 year old returned to their preinjury level of athletics.1 This study is the largest review to date in the medical literature which addresses this issue.

Based on this cohort, young athletes who participate in cutting and pivoting sports such as soccer, basketball, and football may be at increased risk for ACL injury. After undergoing ACL reconstruction, 239 of the 250 (96%) athletes who responded to the questionnaire were able to return to sports at the same or higher skill level. Median time to return to sports was 9 months postoperative, with most athletes returning to sports (85%) by 12 months. Rugby and football players had lower percentages of athletes returning to sports at 6 and 9 months but by 12 months had similar return to sports as compared with other cutting and pivoting athletes. This may be explained, in part, by the fact that at this age level, their sports are seasonal, as opposed to year-round sports.

In our study, patients cited physical limitations (n = 4), loss of interest in sport (n = 3), and fear of reinjury (n = 2) as reasons for not returning to previous level of sports. Psychological profiles of adult athletes have shown that those patients who did not return to their previous level of activity were more afraid of reinjury because of movement and had a worse knee-related quality of life than those who had returned to their previous level of activity.25 Children are often reliant on their families for access to physical therapy and often need very specific guidelines to remain focused and adherent to rehabilitation. A persisting problem in child and youth sports is inadequate treatment and rehabilitation for injuries.8,29

The relative injury rate in boys and girls was similar in this age group. Because this cohort was clinic based, no conclusions can be drawn as to the sex-specific risk of ACL injury in prepubescents. However, given the documented differential risk of male/female for ACL injury in older athletes, this merits further epidemiologic study.4,31

This study has some limitations. We did not have comprehensive data available from patients' initial visits to determine whether bone age or Tanner staging was used by the treating physicians to select extraphyseal or transphyseal technique. Recall bias is inherent in our retrospective study design as well. In addition, time of return to sport may be affected by seasonal sports participation because a relatively small percentage of this age group in this period was participating in year-round training in 1 sport. Finally, recall bias is inherent in any post activity questionnaire. However, both the parents and the young athletes themselves are usually quite precise about the timing and level of return to sport.

After undergoing ACL reconstruction, most athletes are able to return to sports and 50% of these athletes return within 9 months after surgery. However, the reason some athletes do not return may be resolved with sports-specific training and rehabilitation for this age group.

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ACKNOWLEDGMENTS

No outside funding was received for this work and to the best of our knowledge, no conflict of interest, financial, or other exists. The results of this study do not constitute endorsement by CJSM.

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Keywords:

pediatric; ACL; surgery; return to sports

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