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Abstract

Background:

Although high rates of graft and contralateral anterior cruciate ligament (ACL) ruptures have been reported in younger patients after ACL reconstruction (ACLR), recent evidence suggests that previously reported crude event rates underestimate the actual event risk.

Purpose:

To report rates of graft and contralateral ACL rupture after ACLR in a large series of younger patients using survival analysis.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Patients aged <18 years at the time of primary ACLR were identified from a single-surgeon database over 12 years ending January 2018. Patients with a previous contralateral ACL rupture or bilateral ACL ruptures were excluded. Overall, 388 patients (204 males, 184 females) were included in the final dataset. Bespoke survey data and clinic follow-up data were used to record graft rupture and contralateral ACL rupture events. Rates of graft and contralateral ACL rupture were calculated using Kaplan-Meier survival analysis. Log-rank tests were used to compare survival functions between several subgroups.

Results:

According to Kaplan-Meier survival analysis, the cumulative rates at 2, 5, and 10 years for graft rupture were 11%, 17%, and 22%, and the cumulative rates for contralateral ACL injury were 7%, 19%, and 33%. Males had significantly greater rates of graft rupture than females throughout a 10-year follow-up period (P < .001). Contralateral ACL rupture survival functions were not significantly different between the sexes, although rates were higher in females until 5 years postoperatively, after which contralateral ACL ruptures increased in males, with a cumulative rate of 39% at 10 years compared with 29% for females. Survival rates did not vary between different age groups (<16 vs ≥16 years), but females with a graft diameter of <7 mm on the femoral side had significantly greater graft rupture rates than females with grafts ≥7 mm (P = .04).

Conclusion:

The present study is one of the largest consecutive series of younger patients, with one of the longest follow-up periods, reporting a high risk for a second ACL injury. Over time, the cumulative risk for contralateral ACL rupture was higher than for graft rupture. In males, the risk for contralateral ACL rupture continued to increase after 5 years.

Keywords

anterior cruciate ligament reconstruction athlete sports injury

Younger age is a recognized risk factor for sustaining multiple anterior cruciate ligament (ACL) injuries.^{10,14,18,24,29,32,38} This has been consistently determined via large-scale registry datasets^14,18 as well as institutional cohort studies^23,26,33 and may include rupture of an ACL graft or a subsequent contralateral ACL injury after a first-time ACL reconstruction (ACLR). The risk for either of these events occurring has been estimated to be between 2 to 5 times greater in younger patients compared with their older counterparts.¹⁴ While the definition of younger has varied, the proportion of ACL-injured patients who are <25 years old who sustain multiple ACL injuries has been documented^11,26,28,33 at between 20% to 50%. Such high rates of multiple ACL injuries in younger patients are of significant concern. Even more concerning is that many of these studies report crude event proportions at a mean or median follow-up time, which has been shown to underestimate the actual event risk.⁶

The significant and negative effect of age is also clearly apparent when patients are followed over a longer period after ACLR. In a longitudinal study by Salmon et al,²⁷ graft survival was 85% for adult patients compared with only 61% for adolescent athletes (aged ≤18 years) at a 20-year follow-up. This was despite both groups having similar rates of returning to sports and current levels of activity. Despite the limitation of small group numbers (39 adolescents in total; 13 males and 26 females), graft survival was reported at only 46% at 20 years for the adolescent males, compared with 69% for adolescent females. This sex-based disparity, which suggests that males are at higher risk for graft rupture than females, has also been shown in other cohort studies.⁵ Other research has indicated that females have significantly higher rates of subsequent contralateral ACL injuries.^24,31

A recent large study in pediatric patients by DeFrancesco et al⁷ showed significantly higher rates of multiple ACL injuries with the use of survival analysis than had previously been reported. In a sample of 504 patients <16 years, the cumulative rate of graft rupture was 21.6% by 4 years, which was notably higher than the rate of 8.7%, which had previously been reported in a meta-analysis of pediatric patients with a mean age of 13 years (range, 9-16 years).³⁹ Collectively, the results of both Salmon et al²⁷ and DeFrancesco et al⁷ highlight the importance of the type of analysis performed as well as the assessment of younger patients over a longer time frame. Unfortunately, there is a lack of other similar studies.

The present study was undertaken to report rates of graft and contralateral ACL rupture after ACLR in a large series of younger patients (<18 years) using survival analysis up to 10 years after primary ACLR.

Methods

Patient Selection

A consecutive cohort of 400 patients who had undergone primary autograft ACLR between December 2004 and February 2018 by a single experienced knee surgeon (J.A.F.). The inclusion criteria were patients who were <18 years at the time of surgery. Patients with a previous contralateral ACL rupture (n = 8) or bilateral ACL ruptures (n = 2) were excluded, as were 2 patients who died within 6 months of surgery, leaving 388 eligible patients (203 males, 185 females) in the final study cohort.

After receiving ethics committee approval, we contacted all patients for inclusion in the present study. Some patients had been included in previous studies related to risk factors for second ACL injury³² or exploring ACL injuries in younger patients.³³ Others were also part of a longitudinal study investigating comprehensive outcomes after ACLR.^34,35

Surgical and Rehabilitation Details

All ACLRs were performed using a variety of graft types, but predominately hamstring tendon autografts. No allografts were used. Regardless of graft type, fixed-loop suspensory fixation was used on the femoral side and interference screw fixation on the tibial side, except in patients with clearly open growth plates. In the latter group, tibial fixation was performed using nonabsorbable sutures tied to a fixation post. During the surgical period, lateral extra-articular tenodesis was not routinely used (only 5 patients had anterolateral augmentation, and this was performed using a modified Ellison procedure^1,8).

Patients were discharged from the hospital on the first postoperative day, with weightbearing allowed as tolerated. Braces were not routinely used, the exceptions being when extensive meniscal tears were repaired. In this situation, a knee immobilizer was used for 3 weeks, during which time the patient remained partially weightbearing. Patients completed rehabilitation at a clinic of their choice, and standard rehabilitation protocols and guidelines were provided that encouraged immediate full active knee extension and the restoration of quadriceps function as soon as possible.³ Progression depended on recovery of range of motion, strength, and the absence of an effusion. In general, running did not commence until 3 to 4 months postoperatively with sports-specific activities commencing 1 to 2 months later. Clearance to return to competitive sports was typically between 9 and 12 months after surgery and was determined by the treating surgeon. The patient had to complete 1 month of completely unrestricted full-contact training before resuming competition.

Data Collection

Prospectively collected patient databases were searched for demographic, injury, and surgical information. Demographic characteristics included age at surgery, sex, and a previous history of contralateral ACL injury. The primary variables of interest for this study were the number of second ACL injuries, either ACL graft rupture or contralateral ACL injury after the primary procedure. Medical records of the entire cohort were initially checked beginning February 2023 to identify patients who had sustained a second ACL injury and the number and type (graft rupture, contralateral ACL) of injury were recorded. Patients who were identified from their medical record as having had both a graft rupture and contralateral ACL injury were not contacted further, as the purpose of this study was to document subsequent injuries rather than the outcome of the treatment of those injuries. The remaining patients were individually contacted via telephone or email/electronic survey to identify any further ACL injuries in the study cohort. Both forms of contact required the patient (or parent) to answer structured questions regarding any further injuries to the ACL-reconstructed knee or the contralateral knee.³² The questions included the date of further injury (separate questions for graft rupture and contralateral ACL injury), activity at the time of injury, and if sports-related, which sport and whether the sport was a contact or noncontact sport. Finally, the patient indicated the details of any medical treatment sought. Each patient’s last follow-up date was considered to be the day of their last clinic review/visit or the day they completed the survey/telephone interview, whichever was the latest. By the time of the follow-up, at least 5 years had elapsed since their index ACLR in all patients.

Statistical Analysis

Rates of ACL graft rupture and contralateral ACL injuries were calculated using Kaplan-Meier survival analysis, with patients censored after their last known follow-up. Log-rank tests were used to compare survival functions between several subgroups (sex, age, and graft diameter). Statistical significance was set at P ≤ .05, and all analyses were performed using SPSS software Version 28 (IBM Corp).

Results

The mean follow-up period was 8 years (range, 0-18 years). One patient had not attended any postoperative appointments and did not respond to any follow-up attempt, and 17 patients did not have follow-up data beyond 12 months postoperatively. One patient had an early graft rupture at 6 months and underwent revision surgery but did not attend any follow-up appointments beyond 3 months after revision. For 50% of the cohort, the follow-up was between 6 and 10 years. A minimum 3-year follow-up was achieved for 91% of the cohort and a minimum 5-year follow-up was achieved for 83% of the cohort. Descriptive data for the cohort is shown in Table 1, and a histogram of patient age is shown in Figure 1.

Table 1

Patient Characteristics Overall and According to Sex^a

	Overall	Female	Male
	(N = 388)	(n = 184)	(n = 204)
Age, y	16.1 (9.9-17.9)	16.0 (9.9-17.9)	16.3 (11.7-17.9)^b
Graft type
Hamstring	352	174	178
Patellar tendon	16	3	13
Quadriceps	20	7	13
Graft size diameter, mm
Femoral side	7.8 (6-11)	7.4 (6-9.5)	8.1 (6-11)^c
Tibial side	8.4 (6.5-12)	8.1 (6.5-10)	8.8 (6.5-12)^c
Medial meniscal tear	86	51	35^b
No treatment	18	9	9
Repair	43	27	16
Resect	25	15	10
Lateral meniscal tear	133	59	74
No treatment	63	27	36
Repair	13	9	4
Resect	57	23	32^d

Values are presented as mean (range) or number of patients. Significant differences between male and female patients: ^bP < .05, ^cP < .001.

Two resections during a previous surgery.

Figure 1.

Histogram of patient age at surgery. Open growth plates were present in 54 patients (14%) and closed/closing growth plates in 334 patients (86%).

Based on Kaplan-Meier survival analysis, the cumulative rates of graft rupture via survival analysis were 11% at 2 years, 17% at 5 years, and 22% at 10 years (Table 2). This varied by sex, in which males had significantly greater rates of graft rupture than females (log-rank, P = .001) throughout a 10-year follow-up period (Figure 2A). For contralateral ACL injury, the cumulative rates were 7% at 2 years, 19% at 5 years, and 33% at 10 years. Contralateral ACL rupture survival functions were not significantly different between male and female patients (log-rank, P = .7), although rates were higher in females until 5 years, after which males continued to sustain contralateral ACL ruptures, with a cumulate rate of 39% at 10 years compared with 29% for females (Figure 2B). There were no differences in survival rates between patients who were <16 versus ≥16 years for graft rupture (log-rank, P = .92) (Figure 3) or contralateral ACL injury (log-rank, P = .94).

Table 2

Rates of ACL Graft Rupture and Contralateral ACL Rupture at 1-, 2-, 5-, and 10-Year Follow-up^a

Years After ACLR	Graft Rupture			Contralateral ACL Rupture
Years After ACLR	Overall	Female	Male	Overall	Female	Male
1	5.8 (3.8-8.6)	2.8 (1.2-6.5)	8.5 (5.4-13.3)	2.4 (1.2-4.5)	4 (1.9-8)	2 (0.8-5.3)
2	11.2 (8.4-14.8)	6.7 (3.9-11.5)	15.3 (11-21.2)	7.3 (5.5-10.4)	10.1 (6.5-15.5)	4.7 (2.5-8.8)
5	16.9 (13.4-21.2)	9.2 (5.7-14.6)	23.9 (18.4-30.8)	18.7 (15-23.3)	19.2 (14-25.9)	18.4 (13.4-25.1)
10	22.1 (17.7-27.5)	14.8 (9.8-22)	28.8 (22.1-37.1)	33.3 (27.6-39.9)	29.4 (22.2-38.3)	38.7 (29.9-49)

Values are presented as percentages (95% CI). ACL, anterior cruciate ligament; ACLR, anterior cruciate ligament reconstruction.

Figure 2.

Kaplan-Meier survival curves of (A) graft rupture and (B) contralateral ACL rupture according to sex in patients having undergone ACLR. ACL, anterior cruciate ligament; ACLR, anterior cruciate ligament reconstruction.

Figure 3.

Kaplan-Meier survival curves of graft rupture according to age grouping.

For the entire patient cohort and male patients, graft survival rates were not significantly different between patients who had smaller (<7 mm) compared with larger (≥7 mm) sized grafts (log-rank, P > .05). However, female patients with a smaller-sized graft on the femoral side had significantly greater rates of graft rupture than those with a larger-sized graft (log-rank, P = .04) (Figure 4).

Figure 4.

Kaplan-Meier survival curves of graft rupture in female patients according to graft diameter on the femoral side.

Discussion

The present study's findings confirm the high risk of a second ACL injury in younger patients. Over time, we found that the cumulative risk for contralateral ACL rupture was higher than that for graft rupture. This contradicts some previous work in adolescent cohorts. Salmon et al²⁷ and DeFrancesco et al⁷ showed greater graft rupture rates compared with contralateral ACL injury in their young patient cohorts. In the present study, females initially had higher rates of contralateral ACL rupture, but at around 5 years postoperatively the survival curves crossed over, and after 5 years, males had higher rates of contralateral ACL injuries. This was not seen in Salmon et al²⁷ despite their having a 20-year follow-up period, although it was most likely due to their small sample size of 13 adolescent male patients. An earlier 15-year follow-up study by the same research group did, however, show that male patients had increased rates of contralateral ACL injury after 5 years compared with females,¹⁹ consistent with the results of the present study. Morgan et al¹⁹ suggested that more young male patients may have returned to sports that have a higher risk for a knee injury and that this likely contributed to their finding of increased contralateral ACL injuries in this cohort. Interestingly, in their study, no contralateral ACL injuries occurred in the female participants after 6 years whereas in the present study, females continued to experience contralateral ACL injury between 5 and 10 years, just at a slower rate than their male counterparts. DeFrancesco et al⁷ had only a 4-year follow-up period and as such did not assess their young patients for a long enough period for this trend in contralateral ACL injuries to emerge.

The most incremental cumulative increase in graft ruptures was seen within the first 3 years, particularly for male athletes (shown in Figure 1). This is consistent with data from registry studies, which show that the incidence of ACL revision surgery peaks at 1 to 2 years¹⁴ and raises several issues, particularly in terms of when young athletes should return to sports. Return-to-sport criteria have been extensively discussed, but overall, there is little evidence that criteria can be directly applied to young athletes to prevent further injury.^15,37 While the recovery of quadriceps strength is important during ACL rehabilitation and may allow for an athlete to successfully return to sports, recent studies have either not found a relationship between the recovery of strength and risk for subsequent ACL injury in young athletes or have found that athletes with higher strength may have a higher injury risk.^4,30 It has also been suggested that it may be beneficial for young athletes to delay their return to strenuous sports.²¹ However, a recent study in which young athletes (<20 years at surgery) were advised to delay their return to competitive sports until 12 months after a first-time ACLR found that there was no beneficial effect of this delay. At 3 to 5 years after reconstruction, 33% of patients in the delayed group had suffered a subsequent ACL injury compared with 31% in a group who were not advised to delay their return to sports.³⁶

Most patients in the present study received hamstring tendon grafts. Results from several large data sets have shown higher revision rates for hamstring tendons compared with patellar tendon grafts.^13,25 Data from the Norwegian ACL registry showed an increased risk of revision after the use of hamstring grafts compared with patellar tendon grafts, particularly for the youngest patients (15-19 years).²⁵ Data from the Kaiser Permanente Registry similarly showed a significantly higher risk of rupture (hazard ratio, 1.6) for hamstring grafts compared with patellar tendon grafts in patients <21 years at surgery.¹⁷ In the recent STABILITY trial, the addition of a lateral extra-articular tenodesis (LET) to a single-bundle hamstring graft in patients ≤25 years was shown to significantly reduce the rate of graft rupture from 11% in the group without a LET to 4% in the LET group.⁹ Unfortunately, this variable could not be evaluated because a LET procedure was not routinely used in the present cohort. In the present study, females with a smaller graft diameter on the femoral side had greater rates of graft rupture. Previous studies have similarly shown statistical associations between a small graft diameter at surgery and subsequent graft rupture.^12,16 However, collectively, the literature is mixed, and this association has not been consistently reported. A recent systematic review evaluated the risk of ACLR failure between various dichotomous graft size groupings and found that of 8 comparisons, graft diameters of <7 mm were associated with significantly higher failure rates.² This review included patients of all ages and activity levels. Data from the New Zealand ACL Registry found no relationship between graft diameter and graft failure in patients <20 years at the time of surgery.²⁰ In the present study it is unclear why an association between graft diameter and graft rupture was seen for only the female patients and not the young males. Overall, further data are required to understand the role of graft diameter in graft failure in young active patients.

Survival rates of graft or contralateral ACL rupture were no different between relatively younger (<16 years) and older (≥16 years) adolescent patients in the present study. Patel et al²² found that patients <15 years had 3.1 times higher odds of contralateral ACL rupture than those aged 15 to 20 years at the time of surgery. The mean follow-up time was, however, only 4 years, and as such it is unknown whether such a difference would persist over time. The present findings, in which the mean follow-up time was 8 years, indicate that the risk for multiple ACL injuries continues to remain present and meaningfully accumulates over a significant period for young athletes. This may have negative consequences for the ability of a young athlete to continue to participate in sports and physical activity over the lifespan as well as for the long-term health of the knee joint.

Strengths and Limitations

As with all research, the present study has both strengths and limitations. Strengths include a consecutive cohort of young athletes all operated on by a single experienced knee surgeon, as well as the long follow-up period. Limitations include the pragmatic nature of the study; as such, we did not routinely record the sports participation levels of patients over time. We therefore do not explicitly know the timing of return to play, how long patients continued to play after surgery, or if patients changed from a high-risk sport for knee injuries to a lower one. These are all factors that have an impact on exposure and thus the risk for reinjury. The high reinjury rates that we saw over time would nonetheless indicate that these young patients did remain highly active after their primary ACLR.

Conclusion

The present study is one of the largest consecutive series of younger patients, with one of the longest follow-up periods, reporting a high risk for a second ACL injury. Over time, the cumulative risk for contralateral ACL rupture was higher than for graft rupture. Understanding the postoperative time course for second ACL injury in young patients is important so that factors that contribute to this increased risk can be better understood and such injuries prevented.

Footnotes

Acknowledgements

The authors thank Haydn Klemm for his assistance in contacting the patients involved in this study.

Final revision submitted September 12, 2024; accepted September 19, 2024.

One or more of the authors has declared the following potential conflict of interest or source of funding: J.A.F. is a paid associate editor for The Orthopaedic Journal of Sports Medicine. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Ethical approval for this study was obtained from La Trobe Research (reference No. HEC22298).

References

Al’Khafaji

Devitt

Feller

. The modified Ellison technique: a distally fixed iliotibial band transfer for lateral extra-articular augmentation of the knee. Arthrosc Tech. 2022;11(2):e257-e262.

Alomar

Nasser

ASB

Kumar

Das

Mittal

. Hamstring graft diameter above 7 mm has a lower risk of failure following anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2022;30(1):288-297.

Batty

Feller

Damasena

, et al. Single-leg squat after anterior cruciate ligament reconstruction: an analysis of the knee valgus angle at 6 and 12 months. Orthop J Sports Med. 2020;8(8):2325967120946328.

Blucher

Feller

Devitt

, et al. Is there an association in young patients between quadriceps or hamstring strength after ACL reconstruction and graft rupture? Orthop J Sports Med. 2022;10(6):23259671221101003.

Cronström

Tengman

Häger

. Return to sports: a risky business? A systematic review with meta-analysis of risk factors for graft rupture following ACL reconstruction. Sports Med. 2023;53(1):91-110.

DeFrancesco

Striano

Baldwin

. Statistics in brief: evaluating measures of the postoperative event burden. Clin Orthop Relat Res. 2019;477(11):2601-2606.

DeFrancesco

Striano

Bram

Baldwin

Ganley

. An in-depth analysis of graft rupture and contralateral anterior cruciate ligament rupture rates after pediatric anterior cruciate ligament reconstruction. Am J Sports Med. 2020;48(10):2395-2400.

Feller

Devitt

Webster

Klemm

. Augmentation of primary ACL reconstruction with a modified Ellison lateral extra-articular tenodesis in high-risk patients: a pilot study. Orthop J Sports Med. 2021;9(8):23259671211021351.

Getgood

AMJ

Bryant

Litchfield

, et al. Lateral extra-articular tenodesis reduces failure of hamstring tendon autograft anterior cruciate ligament reconstruction: 2-year outcomes from the STABILITY Study randomized clinical trial. Am J Sports Med. 2020;48(2):285-297.

10.

Kaeding

Pedroza

Reinke

Huston

Spindler

. Risk factors and predictors of subsequent ACL injury in either knee after ACL reconstruction: prospective analysis of 2488 primary ACL reconstructions from the MOON cohort. Am J Sports Med. 2015;43(7):1583-1590.

11.

Kamath

Murphy

Creighton

, et al. Anterior cruciate ligament injury, return to play, and reinjury in the elite collegiate athlete: analysis of an NCAA Division I cohort. Am J Sports Med. 2014;42(7):1638-1643.

12.

Kang

Dong

Wang

. Small hamstring autograft is defined by a cut-off diameter of 7 mm and not recommended with allograft augmentation in single-bundle ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2019;27(11):3650-3659.

13.

Laboute

James-Belin

Puig

Trouve

Verhaeghe

. Graft failure is more frequent after hamstring than patellar tendon autograft. Knee Surg Sports Traumatol Arthrosc. 2018;26(12):3537-3546.

14.

Lind

Menhert

Pedersen

. Incidence and outcome after revision anterior cruciate ligament reconstruction. Results from the Danish registry for knee ligament reconstructions. Am J Sports Med. 2012;40(7):1551-1557.

15.

Losciale

Zdeb

Ledbetter

Reiman

Sell

. The association between passing return-to-sport criteria and second anterior cruciate ligament injury risk: a systematic review with meta-analysis. J Orthop Sports Phys Ther. 2019;49(2):43-54.

16.

Magnussen

Lawrence

West

Toth

Taylor

Garrett

. Graft size and patient age are predictors of early revision after anterior cruciate ligament reconstruction with hamstring autograft. Arthroscopy. 2012;28(4):526-531.

17.

Maletis

Chen

Inacio

Funahashi

. Age-related risk factors for revision anterior cruciate ligament reconstruction: a cohort study of 21,304 patients from the Kaiser Permanente anterior cruciate ligament registry. Am J Sports Med. 2016;44(2):331-336.

18.

Maletis

Inacio

Funahashi

. Risk factors associated with revision and contralateral anterior cruciate ligament reconstructions in the Kaiser Permanente ACLR registry. Am J Sports Med. 2015;43(3):641-647.

19.

Morgan

Salmon

Waller

Roe

Pinczewski

. Fifteen-year survival of endoscopic anterior cruciate ligament reconstruction in patients aged 18 years and younger. Am J Sports Med. 2016;44(2):384-392.

20.

Murgier

Powell

Young

Clatworthy

. Effectiveness of thicker hamstring or patella tendon grafts to reduce graft failure rate in anterior cruciate ligament reconstruction in young patients. Knee Surg Sports Traumatol Arthrosc. 2021;29(3):725-731.

21.

Nagelli

Hewett

. Should return to sport be delayed until 2 years after anterior cruciate ligament reconstruction? Biological and functional considerations. Sports Med. 2017;47(2):221-232.

22.

Patel

Bram

Talathi

, et al. Which children are at risk for contralateral anterior cruciate ligament injury after ipsilateral reconstruction? J Pediatr Orthop. 2020;40(4):162-167.

23.

Paterno

Rauh

Schmitt

Ford

Hewett

. Incidence of contralateral and ipsilateral anterior cruciate ligament (ACL) injury after primary ACL reconstruction and return to sport. Clin J Sport Med. 2012;22(2):116-121.

24.

Paterno

Rauh

Schmitt

Ford

Hewett

. Incidence of second ACL injuries 2 years after primary ACL reconstruction and return to sport. Am J Sports Med. 2014;42(7):1567-1573.

25.

Persson

Fjeldsgaard

Gjertsen

, et al. Increased risk of revision with hamstring tendon grafts compared with patellar tendon grafts after anterior cruciate ligament reconstruction: a study of 12,643 patients from the Norwegian Cruciate Ligament Registry, 2004-2012. Am J Sports Med. 2014;42(2):285-291.

26.

Pinczewski

Morgan

Salmon

Waller

Thompson

Roe

. 15 year survival of endoscopic anterior cruciate ligament reconstruction in patients aged 18 years and under. Orthop J Sports Med. 2015;3(3):2325967115S00007.

27.

Salmon

Heath

Akrawi

Roe

Linklater

Pinczewski

. 20-Year outcomes of anterior cruciate ligament reconstruction with hamstring tendon autograft: the catastrophic effect of age and posterior tibial slope. Am J Sports Med. 2018;46(3):531-543.

28.

Shelbourne

Benner

Gray

. Return to sports and subsequent injury rates after revision anterior cruciate ligament reconstruction with patellar tendon autograft. Am J Sports Med 2014;42(6):1395-1400.

29.

Shelbourne

Gray

Haro

. 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(2):246-251.

30.

Simonson

Piussi

Högberg

, et al. Effect of quadriceps and hamstring strength relative to body weight on risk of a second ACL injury: a cohort study of 835 patients who returned to sport after ACL reconstruction. Orthop J Sports Med. 2023;11(4):23259671231157386.

31.

Sutherland

Clatworthy

Chang

Rahardja

Young

. Risk factors for revision anterior cruciate ligament reconstruction and frequency with which patients change surgeons. Orthop J Sports Med. 2019;7(11):2325967119880487.

32.

Webster

Feller

Leigh

Richmond

. Younger patients are at increased risk for graft rupture and contralateral injury after anterior cruciate ligament reconstruction. Am J Sports Med. 2014;42(3):641-647.

33.

Webster

Feller

. Exploring the high reinjury rate in younger patients undergoing anterior cruciate ligament reconstruction. Am J Sports Med. 2016;44(11):2827-2832.

34.

Webster

Feller

. Psychological readiness to return to sport after anterior cruciate ligament reconstruction in the adolescent athlete. J Athl Train. 2022;57(9-10):955-960.

35.

Webster

Feller

. Who passes return-to-sport tests, and which tests are most strongly associated with return to play after anterior cruciate ligament reconstruction? Orthop J Sports Med. 2020;8(12):2325967120969425.

36.

Webster

Feller

Klemm

. Second ACL injury rates in younger athletes who were advised to delay return to sport until 12 months after ACL reconstruction. Orthop J Sports Med. 2021;9(2):2325967120985636.

37.

Webster

Hewett

. Is there value and validity for the use of return to sport test batteries after anterior cruciate ligament injury and reconstruction? Arthroscopy. 2020;36(6):1500-1501.

38.

Wiggins

Grandhi

Schneider

, et al. Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction: a systematic review and meta-analysis. Am J Sports Med. 2016;44(7):1861-1876.

39.

Wong

Feeley

Pandya

. Complications after pediatric ACL reconstruction: a meta-analysis. J Pediatr Orthop. 2019;39(8):e566-e571.

Survival Analysis of ACL Graft and Contralateral ACL Ruptures in Patients Younger Than 18 Years

Abstract

Background:

Purpose:

Study Design:

Methods:

Results:

Conclusion:

Keywords

Methods

Patient Selection

Surgical and Rehabilitation Details

Data Collection

Statistical Analysis

Results

Discussion

Strengths and Limitations

Conclusion

Footnotes

Acknowledgements

References