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Graft choices for pediatric anterior cruciate ligament reconstruction: state of the art

Open AccessPublished:January 13, 2023DOI:https://doi.org/10.1016/j.jisako.2023.01.001

      Abstract

      The pediatric population is at particularly high risk for anterior cruciate ligament (ACL) injuries due to high rates of sports participation. Other risk factors for ACL injuries in children include but are not limited to being female, generalized ligamentous laxity, a high BMI, and poor neuromuscular control. ACL reconstruction (ACLR) is commonly done to treat ACL injuries and allow for return to sports and daily activities. ACL repair is another option with ongoing techniques being developed. The high rates of graft failure in children seen in recent publications on ACL repair are very concerning. Special consideration must be taken in ACLR in the skeletally immature patient due to the risk of growth-related complications, such as limb deformity or growth arrest, that can arise from drilling across or disrupting the physis. Graft choices for pediatric ACLR include iliotibial band over the top and over the front, hamstring autograft, bone patellar tendon bone autograft, quadriceps tendon autograft, and allograft. Factors for each graft choice to consider include graft size, graft failure rates, donor site morbidity, requirement for bony tunnels, the post-op rehabilitation process, and return to sport outcomes. Each graft has its benefits and disadvantages for the individual patient, depending on age, skeletal maturity, and goals for recovery. Lateral extra-articular tenodesis (LET) is another option to consider with pediatric ACLR because LET has been shown to decrease the re-rupture rate in adult ACLR. After surgery, patient follow-up until at least the growth plates are closed is important. This article aims to provide an overview and comparison of the various graft types to aid in the graft choice decision making process for pediatric ACLR.

      Keywords

      Funding

      None (see Table 1)
      Table 1Summary of graft types for ACLR and treatment options for pediatric ACL injuries.
      Graft Type or Treatment OptionsDescriptionProsCons
      Non-operative treatmentPhysical therapy across four phases, focusing on exercises aimed at improving neuromuscular control, quadriceps activation, knee extension, pivoting, and more.No surgery is involved. Return to sport at pre-injury levels may be possible.Persistent knee instability may result, leading to increased risk of meniscal tears and articular cartilage damage.
      Iliotibial Band over the top and over the frontThe iliotibial band (ITB) autograft is attached over the top of the lateral femoral condyle and over the front of the tibia, used for very skeletally immature patients.No bony tunnels required.
      Hamstring autograftGraft harvested from hamstring, with multiple techniques, including transphyseal, all-epiphyseal, and also without a tunnel on the femur, fixing the graft in the “over the top” of the lateral femoral condyle position.Less quadriceps inhibition post operatively and avoids the risk of patella fracture.Risk of physeal injury and growth disturbances.
      Bone patellar tendon bone autograftGraft harvested from patellar tendon, used for patients with almost closed physes and little growth remaining.Lowest graft re-tear rate and lowest revision rates.Risk of patella fracture and more difficult recovery, higher rate of contralateral knee injury and kneeling pain.
      Quadriceps tendon autograftGraft harvested from quadriceps.Size and strength of the graft, avoidance of bone plugs, improved kneeling pain.Little data on the use of quadriceps tendon autograft currently.
      Lateral Extra-articular SurgeryPart of the iliotibial band (ITB) is repositioned or anterolateral ligament (ALL) is reconstructed.Lower re-rupture rate, greater knee stability (improved pivot shift), decreases rotational laxityAdds to recovery and possible increased risk of arthritis.
      AllograftGraft is harvested from a cadaver and chemically processed before being used to reconstruct the ACL.No donor site morbidity.High graft re-tear rate.
      ACL RepairThe original torn ACL is reattached and repaired.Limited risk to physes, shorter recovery time, and no risk of donor site morbidity.Higher failure rates and re-injury rates compared to ACL reconstruction.

      Ethics Statement

      No study or ethics approval was required for this study.

      Introduction

      While a person is a minor until they are 18 years old, the FDA definition of a “pediatric patient” is a person aged 21 or younger at the time of their diagnosis or treatment. This higher upper age limit is set particularly for advisory panels and the regulation of medical devices used in the pediatric population. Children are between 2 years and 12 years old, and adolescents are between 12 years and 21 years old [

      US Department of Health and Human Services; Food and Drug Administration. Guidance for Industry and FDA Staff: Pediatric Expertise for Advisory Panels, https://www.fda.gov/media/72451/download; 2003 [accessed 1 November 2022].

      ]. However, when dealing with surgical cases for anterior cruciate ligament (ACL) injuries in the pediatric population, it is more effective to distinguish between closed physis (growth plates) and open physis. The skeletal age of the patient allows an estimate of the growth remaining at the level of the knee and thus the risk of subsequent post-operative malalignment or leg length discrepancy [
      • Hubbard EW L.R.
      • Iobst C.A.
      Understanding Skeletal Growth and Predicting Limb-Length Inequality in Pediatric Patients.
      ]. It was also found that Tanner staging is unreliable when used as a method to guide decision-making for surgery in skeletally immature patients [
      • Slough JM H.W.
      • Chang Y.
      Reliability of Tanner staging performed by orthopedic sports medicine surgeons.
      ].
      Conservative treatments are an option for treating ACL injuries in the pediatric population [
      • Madelaine A.,F.G.
      • Sappey-Marinier E.
      • Madelaine T.
      • Seil R.
      • Lefevre N.
      • Chotel F.
      French Arthroscopic Society
      Conservative management of anterior cruciate ligament injury in paediatric population: About 53 patients.
      ]. Non-operative treatments include physical therapy with exercises that focus on improving neuromuscular control, knee stability, gait, knee extension, quadriceps activation, and pivoting. These exercises are performed at different phases of recovery [
      • Moksnes H.,G.H.
      Prevention and rehabilitation of paediatric anterior cruciate ligament injuries.
      ]. With adherence to quality rehabilitation, conservative treatments can be effective for some pediatric patients; however, they must be closely monitored for future instability and/or meniscal tears. However, if knee stability is not fully recovered through rehabilitation, non-operative treatments present risks of secondary damage, including meniscal tears and cartilage damage, due to persistent knee instability. Return to sport may also be delayed [
      • Madelaine A.,F.G.
      • Sappey-Marinier E.
      • Madelaine T.
      • Seil R.
      • Lefevre N.
      • Chotel F.
      French Arthroscopic Society
      Conservative management of anterior cruciate ligament injury in paediatric population: About 53 patients.
      ].
      Surgical management with ACL reconstruction (ACLR) is another option for treatment of ACL injuries. The procedure often involves drilling near or across the physis in order to create tunnels in the femur and tibia to hold the new graft in place. This presents with risks of growth and axis abnormalities in pediatric patients because these patients may have open physis [
      • Hubbard EW L.R.
      • Iobst C.A.
      Understanding Skeletal Growth and Predicting Limb-Length Inequality in Pediatric Patients.
      ]. These risks associated with ACLR should be considered against the risks of conservative treatments. Despite the risks with ACL reconstruction, ACLR offers higher rates of return to sports than operative treatments [
      • Fabricant PD L.N.
      • Cruz A.I.
      • Spitzer E.
      • Marx R.G.
      ACL reconstruction in youth athletes results in an improved rate of return to athletic activity when compared with non-operative treatment: a systematic review of the literature.
      ]. Early ACLR compared to delayed ACLR or non-operative treatment results in fewer meniscus tears and cartilage damage [
      • Kay J.,M.M.
      • Shah A.
      • Yen Y.M.
      • Samuelsson K.
      • Peterson D.
      • Simunovic N.
      • Flageole H.
      • Ayeni O.R.
      Earlier anterior cruciate ligament reconstruction is associated with a decreased risk of medial meniscal and articular cartilage damage in children and adolescents: a systematic review and meta-analysis.
      ]. Ultimately, the decision to pursue conservative treatment or ACLR depends on the individual patient with consideration of the injury and goals with regards to return to sport.
      There are multiple surgical techniques using a variety of grafts for pediatric ACL reconstruction. Techniques can be transphyseal, all epiphyseal or extraphyseal (over the top of the femur and over the front of the tibia without bone tunnels), or a combination thereof. Graft options include autograft and allograft. The latter is associated with a re-rupture rate of two to three times higher, so we generally recommend avoiding allograft tissue for isolated ACL reconstruction, especially in the pediatric population who are at the highest risk due to their age and activity level [
      • Kaeding C.C.,P.A.
      • Reinke E.K.
      • Huston L.J.
      • MOON Consortium
      • Spindler K.P.
      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.
      ,
      • Maletis GB P.H.
      • Funahashi T.T.
      • Tejwani S.G.
      Allograft Donor Characteristics Significantly Influence Graft Rupture After Anterior Cruciate Ligament Reconstruction in a Young Active Population: Letter to the Editor.
      ]. We also recommend avoiding ACL repair in view of the high failure rates, including very high rates in pediatric patients in a recently published study [
      • Gagliardi AG C.P.
      • Parikh H.B.
      • Traver J.L.
      • Howell D.R.
      • Albright J.C.
      ACL Repair With Suture Ligament Augmentation Is Associated With a High Failure Rate Among Adolescent Patients.
      ].
      When drilling across the physis, the concern is growth arrest in a skeletally immature patient. In a sheep model, it has been shown that growth plate lesions on the central tibial tunnel with soft tissue grafts in the tunnels show no growth disturbance. However, on the peripheral femur, posterolateral growth plate injuries with empty tunnels led to shortening, valgus deformity, and flexion deformity [
      • Seil R.,P.D.
      • Kohn D.
      The risk of growth changes during transphyseal drilling in sheep with open physes.
      ]. In animal studies, it has been shown that an injury to 7-9% of the growth plate can lead to major and permanent growth disturbances [
      • Mäkelä E.A.,V.S.
      • Vihtonen K.
      • Mero M.
      • Laiho J.
      • Törmälä P.
      • Rokkanen P.
      The effect of a penetrating biodegradable implant on the epiphyseal plate: an experimental study on growing rabbits with special regard to polyglactin 910.
      ]. However, with tunnels less than 9mm, studies in humans have shown no major risk of growth disturbance [
      • Pananwala H.,J.Y.
      • Mills L.
      • Symes M.
      • Nandapalan H.
      • Sefton A.
      • Delungahawatte L.
      • Dao Q.
      Tibial tunnel defect size as a risk factor in growth arrest following paediatric transphyseal anterior cruciate ligament reconstruction: an anatomical study.
      ]. An 8 mm drill hole in a 12-year-old female will injure 3-4% of the growth plate, and Janarv et al. found no effect on growth with drill hole area less than 4-5% of the growth plate [
      • Janarv P.M.,W.B.
      • Hirsch G.
      The influence of transphyseal drilling and tendon grafting on bone growth: an experimental study in the rabbit.
      ]. It is also important that surgeons do not use hardware, synthetics or bone crossing the physis in order to avoid growth-related complications in the pediatric patient [
      • Stadelmaier D.M.,A.S.
      • Dodds J.
      • Ross H.
      The effect of drilling and soft tissue grafting across open growth plates. A histologic study.
      ].
      Autograft options include iliotibial band as described by Micheli [
      • Micheli LJ R.B.
      • Gerberg L.
      Anterior cruciate ligament reconstruction in patients who are prepubescent.
      ,
      • Kocher M.S.,G.S.
      • Micheli L.J.
      Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents.
      ], hamstring tendons [
      • Lemaitre G.
      • Pineau V.
      • Rochcongar G.
      • Delforge S.
      • Bronfen C.
      • Haumont T.
      • Hulet C.
      SdCE
      ACL reconstruction in children: a transphyseal technique.
      ,
      • McCarthy M.M.,G.J.
      • Green D.W.
      • Cordasco F.A.
      All-epiphyseal, all-inside anterior cruciate ligament reconstruction technique for skeletally immature patients.
      ,
      • Lo IK K.A.
      • Fowler P.J.
      • Miniaci A.
      The outcome of operatively treated anterior cruciate ligament disruptions in the skeletally immature child.
      ], patellar tendon [
      • McCarroll J.R.,S.K.
      • Porter D.A.
      • Rettig A.C.
      • Murray S.
      Patellar tendon graft reconstruction for midsubstance anterior cruciate ligament rupture in junior high school athletes. An algorithm for management.
      ], and quadriceps tendon [
      • Mauch C A.M.
      • Wirries A.
      • Mayer R.R.
      • Friederich N.F.
      • Hirschmann M.T.
      Anterior cruciate ligament reconstruction using quadriceps tendon autograft for adolescents with open physes- a technical note.
      ]. There is no ideal graft for pediatric patients in general, and each has pros and cons. It is important to understand that there is no ideal graft for a given patient, but rather there are choices, and we attempt to illustrate the various options based on the latest data and science, as well as our collective experience.

      Geographic Differences in ACL Reconstruction

      Little has been documented in the literature regarding geographic differences in ACL reconstruction, especially in pediatric patients. In adults, a study with registries from six countries worldwide found that the mechanism in which an ACL injury occurs and patient demographics were very similar. However, the United States differed from European countries in that allografts were used significantly more. Furthermore, Luxembourg and the US used an interference screw for femoral fixation more, while European countries used suspensory fixation [
      • Prentice HA L.M.
      • Mouton C.
      • Persson A.
      • Magnusson H.
      • Gabr A.
      • Seil R.
      • Engebretsen L.
      • Samuelsson K.
      • Karlsson J.
      • Forssblad M.
      • Haddad F.S.
      • Spalding T.
      • Funahashi T.T.
      • Paxton L.W.
      • Maletis G.B.
      Patient demographic and surgical characteristics in anterior cruciate ligament reconstruction: a description of registries from six countries.
      ]. A survey with surgeons from 57 different countries worldwide further supports the higher rate of allograft use in the US compared to other countries. Additionally, hamstring autografts were used more often outside of North America as compared to the bone patellar tendon bone (BPTB) graft. Despite BPTB grafts having the lowest graft failure rate, hamstring autografts may be preferred because of the possible increased risk of complications associated with BPTB grafts. Furthermore, North American surgeons do not use the double bundle technique as much as surgeons from other countries [
      • Chechik O.,A.E.
      • Khashan M.
      • Lador R.
      • Eyal G.
      • Gold A.
      An international survey on anterior cruciate ligament reconstruction practices.
      ]. Outcomes are generally the same worldwide with similar revision rates [
      • Prentice HA L.M.
      • Mouton C.
      • Persson A.
      • Magnusson H.
      • Gabr A.
      • Seil R.
      • Engebretsen L.
      • Samuelsson K.
      • Karlsson J.
      • Forssblad M.
      • Haddad F.S.
      • Spalding T.
      • Funahashi T.T.
      • Paxton L.W.
      • Maletis G.B.
      Patient demographic and surgical characteristics in anterior cruciate ligament reconstruction: a description of registries from six countries.
      ]. One study found greater quadriceps weakness when comparing the surgical limb with the healthy limb in the US compared to Europe [
      • Tsai L.C.,J.C.
      • Hamblin K.A.
      • Popovich Jr., J.M.
      • Lyle M.A.
      • Cottmeyer D.F.
      • Warren G.L.
      Time, graft, sex, geographic location, and isokinetic speed influence the degree of quadriceps weakness after anterior cruciate ligament reconstruction: a systematic review and meta-analysis.
      ]. Many of these findings and differences do not have concrete explanations but rather is dependent on the relatively small population studied. Given the difference in rates of using various grafts, more studies should be done to ascertain the geographic differences, especially in pediatric patients, to better inform the process of graft choice in pediatric ACLR.
      • 1.
        Pananwala H, Jabbar Y, Mills L, Symes M, Nandapalan H, Sefton A, Delungahawatte L, Dao Q. Tibial tunnel defect size as a risk factor in growth arrest following paediatric transphyseal anterior cruciate ligament reconstruction: an anatomical study. ANZ J Surg. 2016 Sep;86(9):691-5. https://doi.org/10.1111/ans.13694.
      • 2.
        Stadelmaier DM, Arnoczky SP, Dodds J, Ross H. The effect of drilling and soft tissue grafting across open growth plates. A histologic study. Am J Sports Med. 1995 Jul-Aug;23(4):431-5. https://doi.org/10.1177/036354659502300410.
      • 3.
        Gagliardi AG, Carry PM, Parikh HB, Traver JL, Howell DR, Albright JC. ACL Repair With Suture Ligament Augmentation Is Associated With a High Failure Rate Among Adolescent Patients. Am J Sports Med. 2019 Mar;47(3):560-566. https://doi.org/10.1177/0363546518825255.
      • 4.
        Kaeding CC, Aros B, Pedroza A, Pifel E, Amendola A, Andrish JT, Dunn WR, Marx RG, McCarty EC, Parker RD, Wright RW, Spindler KP. Allograft Versus Autograft Anterior Cruciate Ligament Reconstruction: Predictors of Failure From a MOON Prospective Longitudinal Cohort. Sports Health. 2011 Jan;3(1):73-81. https://doi.org/10.1177/1941738110386185.
      • 5.
        Micheli LJ, Rask B, Gerberg L. Anterior cruciate ligament reconstruction in patients who are prepubescent. Clin Orthop Relat Res. 1999 Jul;(364):40-7. https://doi.org/10.1097/00003086-199907000-00006.
      • 6.
        Kocher MS, Garg S, Micheli LJ. Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents. J Bone Joint Surg Am. 2005 Nov;87(11):2371-9. https://doi.org/10.2106/JBJS.D.02802.
      • 7.
        Lemaitre G, Salle de Chou E, Pineau V, Rochcongar G, Delforge S, Bronfen C, Haumont T, Hulet C. ACL reconstruction in children: a transphyseal technique. Orthop Traumatol Surg Res. 2014 Jun;100(4 Suppl):S261-5. https://doi.org/10.1016/j.otsr.2014.03.001.
      • 8.
        Shelbourne KD, Gray T, Wiley BV. Results of transphyseal anterior cruciate ligament reconstruction using patellar tendon autograft in tanner stage 3 or 4 adolescents with clearly open growth plates. Am J Sports Med. 2004 Jul-Aug;32(5):1218-22.
      • 9.
        Cordasco FA, Mayer SW, Green DW. All-Inside, All-Epiphyseal Anterior Cruciate Ligament Reconstruction in Skeletally Immature Athletes: Return to Sport, Incidence of Second Surgery, and 2-Year Clinical Outcomes. Am J Sports Med. 2017 Mar;45(4):856-863. https://doi.org/10.1177/0363546516677723.
      • 10
        Shifflett GD, Green DW, Widmann RF, Marx RG. Growth Arrest Following ACL Reconstruction With Hamstring Autograft in Skeletally Immature Patients: A Review of 4 Cases. J Pediatr Orthop. 2016 Jun;36(4):355-61. https://doi.org/10.1097/BPO.0000000000000466.
      • Return to sport rate
      • Growth-related complications
      • Graft failure or surgery revision rate
      • Tegner Activity Scale
      • Marx Activity Rating Scale
      • Pedi-IKDC (International Knee Documentation Committee) Subjective Knee Form Score
      • Pediatric patients may be skeletally immature. This can result in growth-related complications, such as growth arrest or limb deformity, with pediatric ACLR due to disruption of the physis.
      • The patients’ level of skeletal maturity and desired activity level should be considered when choosing graft type.
      • Pediatric patients must be willing and able to undergo post-operative rehabilitation for best outcomes.

      Graft Choices

      Iliotibial Band over the top and over the front

      With traditional adult ACL reconstruction (ACLR), creation of tunnels and fixation across the physis introduces the possibility of growth disturbance for pediatric patients who have growth remaining. Micheli developed the technique of using the iliotibial band (ITB) autograft over the top of the lateral femoral condyle and over the front of the tibia, which does not require bony tunnels [
      • Micheli LJ R.B.
      • Gerberg L.
      Anterior cruciate ligament reconstruction in patients who are prepubescent.
      ,
      • Kocher M.S.,G.S.
      • Micheli L.J.
      Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents.
      ]. This combined intra-articular/extra-articular physeal-sparing technique with ITB autograft is recommended for very skeletally immature patients (Tanner Stages 1 and 2), where non-operative treatments have failed. These patients often have problems with pivoting and are at higher risk of meniscal or chondral injury. The surgery is recommended for prepubescent patients, with skeletal age confirmed with a hand and wrist radiograph. Tanner Stage 1 or 2, as confirmed by a physician, corresponds to less than or equal to 12 years old for males and less than or equal to 11 years old for females. Once the patient has entered the pubescent stage with growth, an anatomic technique with tunnels can be performed, rather than the ITB autograft. This stage corresponds with Tanner Stage ≥ 3, with males between 13 and 16 years old and females between 12 and 14 years old. For these very young patients, they must also be found to be willing and able to complete post-operative rehabilitation [
      • Kocher M.S.,G.S.
      • Micheli L.J.
      Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents. Surgical technique.
      ].
      In a recent paper, Sugimoto et al. examined the outcomes of 38 pediatric patients following ACL reconstruction with ITB using 3-dimentional (3D) motion analysis. All of the patients had at least 2 years of growth left after surgery, and the mean time between the surgery to kinematic and kinetic tests done was 5.98 years. The participants completed the drop vertical jump maneuver and vertical simple-limb hop tests. The drop vertical jump demonstrated that the mean peak normalized ground-reaction force (GRF) at landing was not significantly different between the surgical and non-surgical limb. Similarly, the vertical single-limb hop test revealed that there was no significant difference between the surgical and non-surgical knee for the mean normalized GRF at landing and mean peak vertical jump height. These results demonstrate that for most pediatric patients after ITB ACLR, the function of the surgical knee is restored to a level almost equivalent to the contralateral knee after a year [
      • Sugimoto D.,W.A.
      • Brodeur J.J.
      • Liotta E.S.
      • Williams K.A.
      • Kocher M.S.
      • Micheli L.J.
      • Heyworth B.E.
      Long-Term Follow-up of Skeletally Immature Patients With Physeal-Sparing Combined Extra-/Intra-articular Iliotibial Band Anterior Cruciate Ligament Reconstruction: A 3-Dimensional Motion Analysis.
      ].
      The surgical technique is described subsequently. A lateral incision is made over the distal iliotibial band. A one-centimeter strip of the iliotibial band is dissected free and detached approximately 15-18 centimeters from the distal end of the lateral femoral condyle. The iliotibial band is left attached distally and dissection is performed distally to separate the iliotibial band from the joint capsule and from the lateral patellar retinaculum. The free proximal end of the iliotibial band is sutured for later graft passage. Arthroscopy of the knee is performed and the torn anterior cruciate ligament fibers are excised. A notchplasty not performed to avoid iatrogenic injury to the perichondrial ring of the distal femoral physis, which is in close proximity to the over-the-top position. The free end of the iliotibial band graft is brought from the over-the-top position and through the knee arthroscopically with use of a clamp. A second incision of approximately 4-5 cm is made over the proximal medial aspect of the tibia. A curved clamp is placed from this incision into the joint under the intermeniscal ligament. A small groove is made in the anterior proximal tibial epiphysis under the intermeniscal ligament with use of a shaver to bring the tibial graft placement more posterior. The free end of the graft is then brought through the joint, under the intermeniscal ligament and out the medial tibial incision. The graft is fixed on the femoral side through the lateral incision with the knee at 90° of flexion with use of mattress sutures to the lateral femoral condyle periosteum at the insertion of the lateral intermuscular septum to affect an extraarticular reconstruction. The tibial side is then fixed through the medial incision with the knee flexed 20° and tension applied to the graft and the graft is sutured to the periosteum with multiple figure of eight non-absorbable mattress sutures [
      • Kocher M.S.,G.S.
      • Micheli L.J.
      Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents.
      ].

      Hamstring autograft

      Hamstring grafts do have advantages that account for its popularity in young athletes. ACL reconstruction with a hamstring graft has less quadriceps inhibition post operatively and avoids the risk of patella fracture that comes with bone tendon bone (BTB) grafts [
      • Tay G.H.,W.S.
      • Marquis G.
      Indirect patella fractures following ACL reconstruction: a review.
      ]. With BTB, there is also a higher prevalence of anterior knee pain and kneeling pain [
      • DeFazio M.W.,C.E.
      • Gustin M.J.
      • Sing D.C.
      • Abdul-Rassoul H.
      • Ma R.
      • Fu F.
      • Li X.
      Return to Sport After ACL Reconstruction With a BTB Versus Hamstring Tendon Autograft: A Systematic Review and Meta-analysis.
      ]. Hamstring autograft has been used extensively for skeletally immature patients with a variety of techniques including transphyseal, all-epiphyseal and also without a tunnel on the femur, fixing the graft in the “over the top” of the lateral femoral condyle position. All of these techniques have published data to support their use [
      • Lemaitre G.
      • Pineau V.
      • Rochcongar G.
      • Delforge S.
      • Bronfen C.
      • Haumont T.
      • Hulet C.
      SdCE
      ACL reconstruction in children: a transphyseal technique.
      ,
      • McCarthy M.M.,G.J.
      • Green D.W.
      • Cordasco F.A.
      All-epiphyseal, all-inside anterior cruciate ligament reconstruction technique for skeletally immature patients.
      ,
      • Lo IK K.A.
      • Fowler P.J.
      • Miniaci A.
      The outcome of operatively treated anterior cruciate ligament disruptions in the skeletally immature child.
      ], and in general we prefer a transphyseal technique to ensure that the graft is placed in the optimal position most reliably. The preferred graft for the young ACL patient is the 4 stranded semitendinosus graft or a 6-8 stranded semitendinosus/gracilis if a longer graft is needed. If possible, consider using a single tendon because it leads to increased deep flexion strength, increased internal rotation strength, and acts as a medial dynamic stabilizer [
      • Eriksson K.,H.P.
      • Jansson E.
      • Larsson H.
      • Shalabi A.
      • Wredmark T.
      Semitendinosus muscle in anterior cruciate ligament surgery: Morphology and function.
      ,
      • von Essen C.,H.A.
      • Barenius B.
      • Eriksson K.
      Utilizing a contralateral hamstring autograft facilitates earlier isokinetic and isometric strength recovery after anterior cruciate ligament reconstruction: a randomised controlled trial.
      ,
      • Lee DW S.J.
      • Yang S.J.
      • Cho S.I.
      • Kim J.G.
      Functional Effects of Single Semitendinosus Tendon Harvesting in Anatomic Anterior Cruciate Ligament Reconstruction: Comparison of Single versus Dual Hamstring Harvesting.
      ].
      One of us has published a series of four cases of growth abnormalities after trans-physeal ACL reconstruction with hamstring autograft [
      • Shifflett G.D.,G.D.
      • Widmann R.F.
      • Marx R.G.
      Growth Arrest Following ACL Reconstruction With Hamstring Autograft in Skeletally Immature Patients: A Review of 4 Cases.
      ]. Four patients that underwent surgery presented with growth retardation or premature growth plate closure on average 11 months after the surgery. Two patients developed asymptomatic tibial recurvatum due to closure of the tibial apophysis as confirmed by a bilateral CT scan. One possible explanation for the tibial apophyseal growth arrest is that the patients experienced rapid growth spurts. This could result in tenoepiphysiodesis, where the graft tension across the physis leads to the growth arrest. The other two patients developed asymptomatic valgus deformity as demonstrated with 3D growth plate mapping MRI. The authors speculated that growth was impacted in these cases because the femoral sockets created through an anteromedial portal with an oblique trajectory resulted in injury to a greater cross-sectional area of the physis [
      • Shifflett G.D.,G.D.
      • Widmann R.F.
      • Marx R.G.
      Growth Arrest Following ACL Reconstruction With Hamstring Autograft in Skeletally Immature Patients: A Review of 4 Cases.
      ]. Still, the prevalence of these growth disturbances are unusual in ALCR. In a meta-analysis by Wong et al., only 58 out of 1329 pediatric ACL reconstructions (4.4%) resulted in growth disturbances, and 16 of these 58 cases (27.6%) required corrective surgeries. Of these growth disturbances cases, abnormal valgus consisted of 14 patients (1.1% of total cases) and recurvatum was seen in 3 patients (0.2% of total cases) [
      • Wong S.E.,F.B.
      • Pandya N.K.
      Complications After Pediatric ACL Reconstruction: A Meta-analysis.
      ].
      To prevent growth arrests following transphyseal ACL reconstruction with hamstring autograft, the authors recommend the following considerations. To avoid tibial recurvatum, a vertical tunnel not too anterior to the ACL footprint can be used to reduce the tension on the graft. Patients should be followed for hyperextension in the operative leg 6- and 12-months post-op as early signs of tibial recurvatum related to tibial tubercle apophyseal growth arrest. To prevent genu valgum, it is important to consider both the trajectory and size of the reamer used in order to reduce the amount of cross-sectional area of the physis resected by tunnel creation. Other considerations to prevent growth arrest include hardware or bone plug placement near the physis, drilling too close to the physis, and extensive periosteal stripping during graft harvest. The authors also recommend thorough pre-op evaluation, including long leg AP and lateral hip-to-ankle films. These radiographs should also be continued 6- and 12-months post-op or every 6 months until growth plates fused to monitor proper lower limb alignment [
      • Shifflett G.D.,G.D.
      • Widmann R.F.
      • Marx R.G.
      Growth Arrest Following ACL Reconstruction With Hamstring Autograft in Skeletally Immature Patients: A Review of 4 Cases.
      ].
      Lo et al. has described hamstring autograft with a combined transtibial and extra-physeal (or “over the top” technique) on the femur [
      • Lo IK K.A.
      • Fowler P.J.
      • Miniaci A.
      The outcome of operatively treated anterior cruciate ligament disruptions in the skeletally immature child.
      ]. For this technique, grafts are released proximally and all are kept in continuity at their distal insertions. The Kennedy ligament augmentation device (Kennedy-LAD) was incorporated for some cases into a composite graft and secured proximally but not distally. However, Kennedy-LAD is no longer used, especially in skeletally immature patients, ever since its discontinuation in 2009.
      Despite claims of newer techniques and procedures for the hamstring graft ACL reconstruction potentially leading to lower revision rates, Murgier et al. found that traditional 4-stranded semitendinosus hamstring grafts and multiple strand hamstring grafts have a very similar failure rate indicating that a thicker hamstring graft does not result in a lower failure rate. They also found that BTB grafts have a significantly lower failure rate of 0% in females than hamstring grafts which had a 5.1% failure rate. This was a study of 991 patients less than or 20 year of age and were followed for 2-5 years after surgery [
      • Murgier J.,P.A.
      • Young S.
      • Clatworthy M.
      Effectiveness of thicker hamstring or patella tendon grafts to reduce graft failure rate in anterior cruciate ligament reconstruction in young patients.
      ]. A study also examined return to pre-injury activity levels using the New Zealand registry. Using a pre-operative Marx score of 13 as the high activity threshold, it was found that at one year, 17.2% of BTB graft operations and 9.3% hamstring graft operations had a Marx score of 13 or greater. At two-year post-op these rates were 23.3% and 13.3% for BTB and hamstring respectively [
      • Rahardja R.,L.H.
      • Clatworthy M.G.
      • Monk A.P.
      • Young S.W.
      Higher Rate of Return to Preinjury Activity Levels After Anterior Cruciate Ligament Reconstruction With a Bone-Patellar Tendon-Bone Versus Hamstring Tendon Autograft in High-Activity Patients: Results From the New Zealand ACL Registry.
      ]. Males and patients of a younger age had a higher return to activity. This may contribute to the higher rates of contralateral ACL injury in BTB graft ACL reconstructions.
      An all-epiphyseal technique has been reported by several authors and has the theoretical advantage of avoiding the growth plates altogether [
      • McCarthy M.M.,G.J.
      • Green D.W.
      • Cordasco F.A.
      All-epiphyseal, all-inside anterior cruciate ligament reconstruction technique for skeletally immature patients.
      ,
      • Anderson CN A.A.
      Management of the Anterior Cruciate Ligament-Injured Knee in the Skeletally Immature Athlete.
      ,
      • Cordasco F.A.,M.S.
      • Green D.W.
      All-Inside, All-Epiphyseal Anterior Cruciate Ligament Reconstruction in Skeletally Immature Athletes: Return to Sport, Incidence of Second Surgery, and 2-Year Clinical Outcomes.
      ]. However, in practice, the tunnels are created in very close proximity to the physis and the risk of physeal injury is not insignificant with this technique, with complications and re-operation rates that limit the theoretical advantages of the technique in our opinion [
      • Lawrence JT W.R.
      • Garrett W.E.
      Growth disturbance following ACL reconstruction with use of an epiphyseal femoral tunnel: a case report.
      ,
      • Koch P.P.,F.S.
      • Blatter S.C.
      Complications after epiphyseal reconstruction of the anterior cruciate ligament in prepubescent children.
      ,
      • Wall EJ G.P.
      • Eismann E.A.
      • Myer G.D.
      • Carr P.
      Outcomes and Complications After All-Epiphyseal Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients.
      ,
      • Saad L.,G.G.
      • Nault M.L.
      Complication rates following all-epiphyseal ACL reconstructions in skeletally immature patients: A retrospective case series study.
      ].
      Additionally, living donor hamstring allograft has been studied in children as well [
      • Lawrence JT W.R.
      • Garrett W.E.
      Growth disturbance following ACL reconstruction with use of an epiphyseal femoral tunnel: a case report.
      ]. In 100 children with a median age of 14 years old, 79 hamstring grafts were donated by the father and 21 by the mother. The median hamstring graft diameter was 7.5 mm and a 4-strand graft was used in 86 cases and a 2-strand raft was used in 14 cases. Thirty-nine of the pediatric patients had open growth plates, 22 had closing growth plates, and 39 had closed growth plates. Clinical outcomes with this cohort were associated with excellent subjective outcomes, including good ligament stability, a high rate of return to sports, as well as no significant difference in radiographic leg length over two years. However, the graft rupture rate was 24% in males and 16% in females. In addition, positive family history of ACL rupture increased the risk of subsequent injury [
      • Ghosh K.,S.L.
      • Heath E.
      • Pinczewski L.A.
      • Roe J.P.
      Transphyseal anterior cruciate ligament reconstruction using living parental donor hamstring graft: excellent clinical results at 2 years in a cohort of 100 patients.
      ].

      Bone patellar tendon bone autograft

      For patients with open physis that are near closure and therefore have minimal growth remaining, bone-tendon-bone autograft is an excellent option, particularly in view of the lower re-rupture rate associated with this graft [
      • Rahardja R.,L.H.
      • Clatworthy M.G.
      • Monk A.P.
      • Young S.W.
      Higher Rate of Return to Preinjury Activity Levels After Anterior Cruciate Ligament Reconstruction With a Bone-Patellar Tendon-Bone Versus Hamstring Tendon Autograft in High-Activity Patients: Results From the New Zealand ACL Registry.
      ,
      • MOON Knee Group S.K.
      • Huston L.J.
      • Zajichek A.
      • Reinke E.K.
      • Amendola A.
      • Andrish J.T.
      • Brophy R.H.
      • Dunn W.R.
      • Flanigan D.C.
      • Jones M.H.
      • Kaeding C.C.
      • Marx R.G.
      • Matava M.J.
      • McCarty E.C.
      • Parker R.D.
      • Vidal A.F.
      • Wolcott M.L.
      • Wolf B.R.
      • Wright R.W.
      Anterior Cruciate Ligament Reconstruction in High School and College-Aged Athletes: Does Autograft Choice Influence Anterior Cruciate Ligament Revision Rates?.
      ]. Most females thirteen and over (especially if post-menarchal) as well as males fifteen and older have relatively minimal growth remaining and will not develop a clinically meaningful deformity following BTB ACL reconstruction [
      • Shelbourne K.D.
      • GT, Wiley B.V.
      Results of transphyseal anterior cruciate ligament reconstruction using patellar tendon autograft in tanner stage 3 or 4 adolescents with clearly open growth plates.
      ]. However, for patients with significant growth remaining that could lead to a centimeter or more in the distal femur or proximal tibia, BTB should be avoided since the bone plugs and fixation crossing the physis will definitely cause a growth arrest and subsequent deformity.
      For BTB, it is important to exclude skeletally immature patients with more than a year of growth remaining. In New Zealand, 54% of the ACL injuries occur in rugby, football, and net ball. Thus, a majority of the athletes injured participate in pivoting sports. There is a slow increase in BTB use in New Zealand, but hamstring tendon is still used for 60% of ACL reconstructions. In terms of graft survival, patellar tendon has a higher cumulative survival rate with respect to re-tear, even at year 1. Based on the New Zealand ACL registry, there is a 2.7% failure rate when using BTB tendon versus 12.4% failure rate in hamstring grafts in patients less than 20 years old. This difference persists for patients 20-24 years old, and in patients greater than 25 years. Across many studies, hamstring tendons have been shown to have revision rates that are significantly higher than for BTB [
      • Persson A.,F.K.
      • Gjertsen J.E.
      • Kjellsen A.B.
      • Engebretsen L.
      • Hole R.M.
      • Fevang J.M.
      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.
      ,
      • Gifstad T F.O.
      • Engebretsen L.
      • Lind M.
      • Forssblad M.
      • Albrektsen G.
      • Drogset J.O.
      Lower risk of revision with patellar tendon autografts compared with hamstring autografts: a registry study based on 45,998 primary ACL reconstructions in Scandinavia.
      ,
      • Mohtadi NG C.D.
      A Randomized Clinical Trial Comparing Patellar Tendon, Hamstring Tendon, and Double-Bundle ACL Reconstructions: Patient-Reported and Clinical Outcomes at 5-Year Follow-up.
      ].

      Quadriceps tendon autograft

      Quadriceps autograft has received increased attention over the past decade as an option for ACL reconstruction in the skeletally immature patient population [
      • Mauch C A.M.
      • Wirries A.
      • Mayer R.R.
      • Friederich N.F.
      • Hirschmann M.T.
      Anterior cruciate ligament reconstruction using quadriceps tendon autograft for adolescents with open physes- a technical note.
      ,
      • Cordasco F.A.,M.S.
      • Green D.W.
      All-Inside, All-Epiphyseal Anterior Cruciate Ligament Reconstruction in Skeletally Immature Athletes: Return to Sport, Incidence of Second Surgery, and 2-Year Clinical Outcomes.
      ,
      • Kohl S.,S.C.
      • Decker S.
      • Ziebarth K.
      • Slongo T.
      • Ahmad S.S.
      • Kohlhof H.
      • Eggli S.
      • Zumstein M.
      • Evangelopoulos D.S.
      Mid-term results of transphyseal anterior cruciate ligament reconstruction in children and adolescents.
      ,
      • Buescu CT O.A.
      • Lucaciu D.O.
      • Todor A.
      Pain level after ACL reconstruction: A comparative study between free quadriceps tendon and hamstring tendons autografts.
      ]. Potential advantages include the size and strength of the graft as well as the avoidance of bone plugs that can affect growth as well as improved kneeling pain. When using the quadriceps, it is important for surgeons to avoid inadvertent release of the rectus tendon from the rest of the quadriceps tendon complex. As well, careful closure of the defect is of the utmost importance when using a quadriceps tendon graft [
      • Shea K.G.,B.J.
      • Richmond C.G.
      • Ellis H.B.
      • Wilson P.L.
      • Fabricant P.D.
      • Mayer S.
      • Stavinoha T.
      • Troyer S.
      • Dingel A.B.
      • Ganley T.J.
      Quadriceps Tendon Graft Anatomy in the Skeletally Immature Patient.
      ]. The data on this graft for skeletally immature patients remains relatively short-term compared to the other options.

      Lateral Extra-articular Surgery

      Lastly, in adults, multiple studies have shown that lateral extra-articular tenodesis (LET) combined with ACLR can reduce re-rupture rate in high-risk patients [
      • Getgood A.M.J.,B.D.
      • Litchfield R.
      • Heard M.
      • McCormack R.G.
      • Rezansoff A.
      • Peterson D.
      • Bardana D.
      • MacDonald P.B.
      • Verdonk P.C.M.
      • Spalding T.
      • Willits K.
      • Birmingham T.
      • Hewison C.
      • Wanlin S.
      • Firth A.
      • Pinto R.
      • Martindale A.
      • O'Neill L.
      • Jennings M.
      • Daniluk M.
      • Boyer D.
      • Zomar M.
      • Moon K.
      • Pritchett R.
      • Payne K.
      • Fan B.
      • Mohan B.
      • Buchko G.M.
      • Hiemstra L.A.
      • Kerslake S.
      • Tynedal J.
      • Stranges G.
      • Mcrae S.
      • Gullett L.
      • Brown H.
      • Legary A.
      • Longo A.
      • Christian M.
      • Ferguson C.
      • Mohtadi N.
      • Barber R.
      • Chan D.
      • Campbell C.
      • Garven A.
      • Pulsifer K.
      • Mayer M.
      • Simunovic N.
      • Duong A.
      • Robinson D.
      • Levy D.
      • Skelly M.
      • Shanmugaraj A.
      • Howells F.
      • Tough M.
      • Spalding T.
      • Thompson P.
      • Metcalfe A.
      • Asplin L.
      • Dube A.
      • Clarkson L.
      • Brown J.
      • Bolsover A.
      • Bradshaw C.
      • Belgrove L.
      • Millan F.
      • Turner S.
      • Verdugo S.
      • Lowe J.
      • Dunne D.
      • McGowan K.
      • Suddens C.M.
      • Declercq G.
      • Vuylsteke K.
      • Van Haver M.
      STABILITY Study Group
      Lateral Extra-articular Tenodesis Reduces Failure of Hamstring Tendon Autograft Anterior Cruciate Ligament Reconstruction: 2-Year Outcomes From the STABILITY Study Randomized Clinical Trial.
      ,
      • Ferretti A.,M.E.
      • Ponzo A.
      • Basiglini L.
      • Iorio R.
      • Caperna L.
      • Conteduca F.
      Combined Intra-articular and Extra-articular Reconstruction in Anterior Cruciate Ligament-Deficient Knee: 25 Years Later.
      ,
      • Sonnery-Cottet B.,B.N.
      • Vieira T.D.
      • Saithna A.
      Clinical outcomes of extra-articular tenodesis/anterolateral reconstruction in the ACL injured knee.
      ]. Patients with ACLR and LET were also found to have an improved pivot shift as compared to patients with ACLR alone. More large-scale studies are needed to determine if LET significantly increases return to sport and patient reported outcome measures (PROMs) [
      • Sonnery-Cottet B.,B.N.
      • Vieira T.D.
      • Saithna A.
      Clinical outcomes of extra-articular tenodesis/anterolateral reconstruction in the ACL injured knee.
      ]. Depending on graft choice and the specific patient factors, lateral extra-articular surgery with either ITB or anterolateral ligament reconstruction can be considered. The European registry (PAMI) showed graft selection for acute ACL reconstructions with open growth plates to be majority semitendinosus and/or gracilis (72%) and a minority quadriceps tendon (28%). Extraarticular tenodesis was performed in 40% of those patients. For delayed ACL reconstructions 44% used quadriceps tendon, 39% semitendinosus and/or gracilis, and 17% patellar tendon. Extraarticular tenodesis were performed in 33% of those patients [
      • Mouton C.,M.H.
      • Janssen R.
      • Fink C.
      • Zaffagnini S.
      • Monllau J.C.
      • Ekås G.
      • Engebretsen L.
      • Seil R.
      Preliminary experience of an international orthopaedic registry: the ESSKA Paediatric Anterior Cruciate Ligament Initiative (PAMI) registry.
      ].
      Recent studies have demonstrated that the lower graft failure rate associated with ACLR and LET combined is also seen in skeletally immature patients [
      • Carrozzo A.,M.E.
      • Saithna A.
      • Annibaldi A.
      • Guy S.
      • Ferreira A.
      • Vieira T.D.
      • Ferretti A.
      • Sonnery-Cottet B.
      Clinical Outcomes of Combined Anterior Cruciate Ligament Reconstruction and Lateral Extra-articular Tenodesis Procedures in Skeletally Immature Patients: A Systematic Review From the SANTI Study Group.
      ,
      • Monaco E.,C.A.
      • Saithna A.
      • Conteduca F.
      • Annibaldi A.
      • Marzilli F.
      • Minucci M.
      • Sonnery-Cottet B.
      • Ferretti A.
      Isolated ACL Reconstruction Versus ACL Reconstruction Combined With Lateral Extra-articular Tenodesis: A Comparative Study of Clinical Outcomes in Adolescent Patients.
      ]. Additionally, Monaco et al. demonstrated that ACLR and LET combined resulted in better laxity and knee stability as compared to ACLR alone. PROMs or other complications did not differ between patients with ACLR and LET and patients with ACLR alone [
      • Monaco E.,C.A.
      • Saithna A.
      • Conteduca F.
      • Annibaldi A.
      • Marzilli F.
      • Minucci M.
      • Sonnery-Cottet B.
      • Ferretti A.
      Isolated ACL Reconstruction Versus ACL Reconstruction Combined With Lateral Extra-articular Tenodesis: A Comparative Study of Clinical Outcomes in Adolescent Patients.
      ]. When performing lateral extra-articular surgery, it is important to respect the growth plates as well. One technique for LET is with iliotibial band autograft and fixed by suture without hardware [
      • Patel N.M.,T.N.
      Combined Anterolateral Ligament Reconstruction and Capsular Reinforcement in the Skeletally Immature Knee.
      ]. Another strategy is a modified Ellison technique, which has been popularized in Australia, where a strip of the iliotibial band is detached distally and is passed under the proximal lateral collateral ligament. It is then reattached distally [
      • Devitt B.M.,L.B.
      • Williams A.
      • Amis A.A.
      • Feller J.A.
      Biomechanical Assessment of a Distally Fixed Lateral Extra-articular Augmentation Procedure in the Treatment of Anterolateral Rotational Laxity of the Knee.
      ].

      Allograft

      ACL reconstructions with allografts have a much high failure rate in pediatric patients and should not be used. The MOON (Multicenter Orthopedic Outcomes Network) consortium found that the odds of tear after allograft ACLR are 4 times as high as the odds of autograft ACLR when adjusted for age [
      • Kaeding C.C.,A.B.
      • Pedroza A.
      • Pifel E.
      • Amendola A.
      • Andrish J.T.
      • Dunn W.R.
      • Marx R.G.
      • McCarty E.C.
      • Parker R.D.
      • Wright R.W.
      • Spindler K.P.
      Allograft Versus Autograft Anterior Cruciate Ligament Reconstruction: Predictors of Failure From a MOON Prospective Longitudinal Cohort.
      ]. Furthermore, patients 10 to 19 years old that underwent allograft ACLR had a graft tear rate of 37.5%, which is the highest rate of all age groups [
      • Kaeding C.C.,A.B.
      • Pedroza A.
      • Pifel E.
      • Amendola A.
      • Andrish J.T.
      • Dunn W.R.
      • Marx R.G.
      • McCarty E.C.
      • Parker R.D.
      • Wright R.W.
      • Spindler K.P.
      Allograft Versus Autograft Anterior Cruciate Ligament Reconstruction: Predictors of Failure From a MOON Prospective Longitudinal Cohort.
      ]. Moreover, Maletis et al. demonstrate that depending on the type of chemical processing of the allografts, soft tissue allografts are at least 4.67 times higher risk of ACL revision compared to BPTB autografts [
      • Maletis GB C.J.
      • Inacio M.C.S.
      • Love R.M.
      • Funahashi T.T.
      Increased Risk of Revision After Anterior Cruciate Ligament Reconstruction With Soft Tissue Allografts Compared With Autografts: Graft Processing and Time Make a Difference.
      ].

      ACL repair in pediatric patients

      ACLR is still the gold standard for ACL injuries, but ACL repair remains a controversial topic. In theory, ACL repair in pediatric patients is an attractive option because there is limited risk to the physes, no donor site morbidity and potentially a more rapid recovery from surgery. Ferretti et al. demonstrated that ACL repair in adults can aid the healing of an acutely injured ACL based on MRI review [
      • Ferretti A.,M.E.
      • Annibaldi A.
      • Carrozzo A.
      • Bruschi M.
      • Argento G.
      • DiFelice G.S.
      The healing potential of an acutely repaired ACL: a sequential MRI study.
      ]. A cohort study found advantages of ACL repair compared to ACLR, including increased hamstring strength 6 months after surgery and better Forgotten Joint Score-12 (FJS-12) scores. No differences were found in return to sport or complications, but there was a significantly higher failure rate with ACL repair among younger participants [
      • Ferreira A.,S.A.
      • Carrozzo A.
      • Guy S.
      • Vieira T.D.
      • Barth J.
      • Sonnery-Cottet B.
      The Minimal Clinically Important Difference, Patient Acceptable Symptom State, and Clinical Outcomes of Anterior Cruciate Ligament Repair Versus Reconstruction: A Matched-Pair Analysis From the SANTI Study Group.
      ]. Other ACL repair techniques are being developed, including arthroscopic ACL repair with an absorbable or an all-suture anchor, which does not require bony tunnels. This technique presented by Turati et al. showed almost all subjects (18/19) return to sport at the same pre-injury level. At two years following surgery, patients felt their knee was normal and did not complain of instability, and patients that underwent ACL repair had comparable PROMs to patients that underwent ACLR. Unfortunately, 21.1% (4/19) patients re-injured their knee on average 4 years after the ACL repair [
      • Turati M.,R.L.
      • Zanchi N.
      • Piatti M.
      • Gaddi D.
      • Gorla M.
      • Omeljaniuk R.J.
      • Courvoisier A.
      • Bigoni M.
      An arthroscopic repair technique for proximal anterior cruciate tears in children to restore active function and avoid growth disturbances.
      ].
      Despite the possible benefits of ACL repair, higher failure rates following ACL repair compared to ACLR are also reported in other studies. A recent study with modern arthroscopic techniques showed high failure rates specifically in adolescent patients [
      • Gagliardi AG C.P.
      • Parikh H.B.
      • Traver J.L.
      • Howell D.R.
      • Albright J.C.
      ACL Repair With Suture Ligament Augmentation Is Associated With a High Failure Rate Among Adolescent Patients.
      ]. Another recent study comparing ACL repair and ACLR found patients 21 years and younger had a 37% failure rate following ACL repair compared to 3.5% in patients older than 21 [
      • Vermeijden H.D.,Y.X.
      • van der List J.P.
      • DiFelice G.S.
      Role of Age on Success of Arthroscopic Primary Repair of Proximal Anterior Cruciate Ligament Tears.
      ]. Overall, we do not recommend ACL repair particularly in pediatric patients given the high failure rates.

      Summary

      The graft selection for pediatric cases consists of the quadriceps tendon, hamstring tendon, tractus iliotibialis, allografts, living donor allograft, and patellar tendon, the latter of which should only be used if the growth plates are closed or nearly closed. In a systematic review of mainly U.S. studies, it was found that of all pediatric ACL reconstructions, 79% used hamstring autograft, 8.3% used fresh-frozen allograft, 6.4% used BTB, 5.1% used quadriceps tendon, and 1.1% used live donor allografts. When BTB autograft was used, pediatric patients tended to be older. It was also found that ipsilateral graft failure was significantly greater for patients treated with fresh-frozen allografts (16.2%) than hamstring autografts (7.8%) or BTB autografts (6.2%) [
      • Zacharias A.J.,W.J.
      • Collofello B.S.
      • Wilson B.R.
      • Unger R.Z.
      • Ireland M.L.
      • Johnson D.L.
      • Jacobs C.A.
      Secondary Injuries After Pediatric Anterior Cruciate Ligament Reconstruction: A Systematic Review With Quantitative Analysis.
      ]. This is further supported by Cruz et al., JBJS 2020, which reveals a significantly higher failure rate of 25.5% vs. 16.6% and 8.5% for allograft vs. hamstring and BTB, respectively, in patients 19 years of age and younger [
      • Cruz AI.Jr, BJ.
      • Ellington M.D.
      • Mayer S.W.
      • Pennock A.T.
      • Stinson Z.S.
      • VandenBerg C.D.
      • Barrow B.
      • Gao B.
      • Ellis Jr., H.B.
      Failure Rates of Autograft and Allograft ACL Reconstruction in Patients 19 Years of Age and Younger: A Systematic Review and Meta-Analysis.
      ]. In a comparative 2019 study by Salem et al., it was found that in female athletes aged 15 to 20, BTB autograft led to fewer graft ruptures than hamstring autograft. Interestingly, this difference was not observed in this study for female athletes aged 21 to 25 years of age. It was also found that BTB autograft led to significantly increased risk of kneeling pain when compared to hamstring regardless of age [
      • Salem H.S.,V.V.
      • Patel N.
      • Dodson C.C.
      • Tjoumakaris F.P.
      • Freedman K.B.
      Anterior Cruciate Ligament Reconstruction in Young Female Athletes: Patellar Versus Hamstring Tendon Autografts.
      ].
      • Patient skeletal maturity and desired return to play activity level should be considered when choosing graft type.
      • The iliotibial band over the top and over the front technique is for very skeletally immature patients and does not require bony tunnels.
      • Hamstring autografts offer an easier recovery with less quadriceps inhibition and decreased risk of patellar fracture as compared to bone patellar tendon bone autografts.
      • Bone patellar tendon bone (BPTB) autografts should only be used in patients with near or complete growth plate closure. BPTB autografts offer a lower re-rupture rate.
      • Quadriceps tendon autografts provide advantages due to its size and strength, and it does not require bony plugs. More data is needed on quadriceps autografts.
      • Lateral extra-articular tenodesis reduces the re-rupture rate in high-risk patients.
      • Allografts have high re-rupture rates compared to autografts and should not be used in children.
      • ACL reconstruction is preferred over ACL repair due to high failure rates associated with ACL repair.
      • Trans-physeal technique for hamstring autograft is preferred to ensure proper graft placement.
      • Follow-up after pediatric ACLR with radiographs is key to prevent limb deformity. Modern limb deformity correction techniques can correct growth complications.
      • Incomplete pre-operative evaluations of skeletal maturity with radiographs
      • Performing ACL repair rather than ACL reconstruction
      • Inadequate follow-up with the patient post-op with radiographs at least every 6 months until growth plates closed to check for limb alignment abnormalities
      • Using allografts
      • Drilling more than 7-9% of the growth plate (>9 mm)
      • Using hardware, placing bone plugs, or drilling near the physis
      • Extensive periosteal stripping during graft harvest

      Conclusion

      In conclusion, ACL reconstruction in a pediatric or adolescent patient with open physes has relatively low risk for growth disturbance but the risk for subsequent knee injury remains high. There are many options for graft choice, as described above. Common to all grafts and techniques is that no bone or hardware should cross the physis to avoid risking major growth disturbances. Fortunately, even in cases of severe limb deformity following ACL reconstruction, an excellent result can be obtained with modern limb deformity correction techniques [
      • Rozbruch S.R.,F.C.
      • Schachter L.F.
      • Bigman D.
      • Marx R.G.
      Growth arrest of the tibia after anterior cruciate ligament reconstruction: lengthening and deformity correction with the Taylor Spatial Frame.
      ]. Live donor allografts offer an interesting alternative with excellent recovery but pose ethical and legal issues in many countries. LET may prove to be a useful adjunct in the pediatric population to reduce the historically high re-rupture rates. In general, pediatric ACL reconstruction should be done at specialized centers and patients should be followed until the growth plates are closed, at the very least. Additionally, this descriptive review is limited by the scientific value and methodology presented in the included studies. More high-quality studies on pediatric ACL reconstruction are needed in the future to make sound decisions about treatment for pediatric ACL injuries and continually improve outcomes after pediatric ACLR.

      Conflicts of Interest

      R.G.M. serves as a Deputy Editor of the Journal of Bone and Joint Surgery and an Associate Editor of Evidence-Based Orthopaedics for the Journal of Bone and Joint Surgery, receives royalties from books published by Springer and Demos Health, and receives equity compensation for seat on science advisory board for MEND Nutrition Inc., outside of the submitted work.
      C.F. is a consultant and receives product royalties from Karl Storz and Medacta, and receives fellowship and research support from Arthrex, Zimmer Biomet, and Stryker, outside of the submitted work.
      K.E. serves as a consultant for Arthrex, consultant and medical advisory board for Episurf, and editorial board for KSSTA, outside of the submitted work.
      A.V. is a shareholder and Director of Forte Health Hospital, outside of the submitted work.
      All other authors declare no conflicts of interest.

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