Technical Note Modification of the Hybrid Anatomic Technique for Anterior Cruciate Ligament Reconstruction in Pediatric Patients Juan Ignacio Erquicia, M.D., Maximiliano Ibañez, M.D., Ricardo Espinoza-Von Bischhoffshausen, M.D., Gabriel Acuña, M.D., Xavier Pelfort Lopez, M.D., Ph.D., and Juan Carlos Monllau, M.D. Abstract: The incidence of anterior cruciate ligament (ACL) lesions with Tanner stage 4 has been increasing in children. To stabilize the knee, different surgical techniques have been developed for ACL reconstruction in the pediatric popu- lation. The use of a hybrid anatomic technique, intra-epiphyseal in the femur and transphysis in the tibia, has been recommended as the technique of choice to reconstruct the ACL in these patients. Despite the favorable results, this technique is not exempt from complications. The aim of this study was to present a simple and reproducible modification of the hybrid anatomic technique for ACL reconstruction in pediatric patients. T he incidence of anterior cruciate ligament (ACL) lesions with Tanner stage 4 has been increasing in children.1,2 To stabilize the knee, different surgical complications. Those include the failure or breakage of the different retrograde brocade systems and the resulting acute “killer angle” between the femoral techniques have been developed for ACL reconstruc- tunnel entrance into the joint and the ACL graft. tion in the pediatric population.3-6 According to The aim of this Technical Note is to present a simple published results,7 the use of a hybrid anatomic tech- and reproducible modification of the hybrid anatomic nique, intra-epiphyseal in the femur and transphysis in technique for ACL reconstruction (ACLR) in pediatric the tibia, has been recommended as the technique of patients. It was assumed that this modification would choice to reconstruct the ACL in these patients. Despite allow for a reconstruction that avoids any damage to the favorable results, this technique is not exempt from the femoral physis, calls for minimal or no x-rays, eliminates the need to use retrograde drill systems, and prevents the killer angle between the graft and the From Institut Català de Traumatologia i Medicina de l’Esport, Quiron femoral tunnel. Therefore, it can be used in patients Dexeus University Hospital, Universitat Autònoma de Barcelona, Barcelona, with Tanner stages 2, 3, and 4. To confirm the safety Spain (J.I.E., M.I., R.E.-V.B., G.A., J.C.M.); the Department of Orthopaedic Surgery, Consorci Sanitari de l’Anoia, Igualada, Spain (J.I.E., J.C.M.); the and reproducibility of this technique, a cadaveric Department of Orthopaedic Surgery, Hospital Parc Taulí, Universitat computed tomography scan study was performed. Autònoma de Barcelona, Sabadell, Spain (X.P.L., J.C.M.); and the Depart- ment of Orthopaedic Surgery, Hospital del Mar, Universitat Autònoma de Barcelona, Barcelona, Spain (J.C.M.). Surgical Technique The authors report the following potential conflicts of interest or sources of First, full standard arthroscopic diagnostic surgery is funding: J.C.M. reports board membership, Smith & Nephew. J.I.E. reports performed. If any meniscal or chondral lesions are grants, consultant, and other, Smith & Nephew. Full ICMJE author disclosure found, they are address before the ACLR. Once the forms are available for this article online, as supplementary material. ligament injury is confirmed, the semitendinosus and Received June 7, 2020; accepted September 10, 2020. Address correspondence to Maximiliano Ibañez, M.D., Department of Or- gracilis tendons of the patient are harvested, and the thopedic Surgery and Traumatology, ICATME, Hospital Universitari Dexeus, graft is made with the aim of obtaining a minimum Carrer de Sabino Arana, 5 - 19, 08028, Barcelona, Spain. E-mail: diameter of 8 mm. drmaximilianoibanez@gmail.com A minimal cutaneous incision is made on the lateral Ó 2020 by the Arthroscopy Association of North America. Published by aspect of the femur, and a longitudinal window is Elsevier. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). created on the fascia lata. The femoral insertion of the 2212-6287/201004 popliteal tendon and the lateral epicondyle are identi- https://doi.org/10.1016/j.eats.2020.09.007 fied. Under arthroscopic visualization from the Arthroscopy Techniques, Vol 10, No 1 (January), 2021: pp e37-e42 e37 e38 J. I. ERQUICIA ET AL. Fig 1. (A) Right knee, view from the high anteromedial portal. Femoral footprint landmark. (B) View from the high ante- romedial portal. Pinpoint femoral guide placed through the anterolateral portal to position it in the anatomic femoral footprint of the anterior cruciate ligament. accessory anteromedial portal, a Pinpoint femoral guide (Smith & Nephew) (Fig 2B). The flexibility of the pin (Smith & Nephew, Andover, MA) is placed through the prevents the drill from damaging the medial femoral anterolateral portal to position it in the anatomic condyle (Fig 3). A tunnel with a minimum diameter of femoral footprint of the ACL (Fig 1). 8 mm and 20 mm in depth is recommended (Fig 4A). The extra-articular end of the guide is positioned at an The result is a femoral tunnel with a slight curve. intermediate point between the lateral femoral struc- Consequently, there is a less acute angle between the tures previously described, and a 2.4-mm guide wire is future graft and the first millimeters of the tunnel placed in an outside-in technique. Then, a full-length (Fig 4B. femoral tunnel is performed from the outside with a To perform the tibial tunnel, the usual steps of 4-mm drill. Once the total length of the femoral tunnel anatomic reconstruction are followed, performing pro- is measured, a 2.4-mm flexible needle is placed outside- gressive drilling until a diameter of 8 mm is achieved in through it (Fig 2A). The flexible pin is recovered (Fig 5A). A dilator is placed in the tibial tunnel, and the from a low anteromedial portal, and the inside-out part lack of conflict between dilator and the intercondylar of the tunnel is performed with the Clancy flexible drill notch can be verified in complete extension. Finally, Fig 2. (A) Right knee, view from the high anteromedial portal. A 2.4-mm flexible guide was placed in an outside-in technique. Then, a full-length femoral tunnel was performed from the outside with a 4-mm drill. (B) Right knee, view from the antero- lateral portal. The flexible pin was recovered from a low anteromedial portal, and the inside-out part of the tunnel was performed with the Clancy 8-mm flexible drill. ACL RECONSTRUCTION IN PEDIATRIC PATIENTS e39 Fig 3. Cadaveric right knee spec- imen showing the setting of the surgical instruments. the graft is fixed in the femur with an adjustable cortical Discussion suspension device (Fig 5B). It allows for filling the 20- There is still controversy as to the appropriate surgical mm femoral tunnel with the plasty and preserving treatment of ACL injuries in skeletally immature pa- cancellous bone tissue in the most lateral part of the tients. Parker et al.8 described reconstruction by passing condyle. The graft is fixed at 30 flexion, using a post hamstring tendons through the anterior aspect of the distal to the tibial physis or an interference screw, tibia and over the top of the lateral femoral condyle. dependent on the size of the physis (Fig 6). Micheli et al.9 used the iliotibial band as the graft and A step-by-step description of the surgical technique is passed it outside the lateral femoral condyle and summarized in Table 1. Table 2 provides pearls and through the intercondylar notch. In that case, it was pitfalls in performing this procedure. Table 3 shows then sutured to the periosteum of the proximal tibia. advantages and limitations, and the Video 1 shows the Despite different ACL reconstruction techniques, there whole technique in detail. is still discussion about which provides the best results Fig 4. (A) Right knee, view from the high anteromedial portal. A tunnel with a minimum diameter of 8 mm and 20 mm in depth is recommended. (B) Right knee, view from the high anteromedial portal. The result is a femoral tunnel with a slight curve. Consequently, there is a less acute angle between the future graft and the first millimeters of the tunnel. e40 J. I. ERQUICIA ET AL. Fig 5. (A) Right knee, view from the anterolateral portal. Tibial tunnel footprint: progressive drilling until a diameter of 8 mm is achieved. (B) Final image of the graft fixed in the femur with an adjustable cortical suspension device. with the lowest risk of complications for the patient. the hybrid anatomy technique, we can observe that we Several studies have reported premature physeal obtain a softer angle in the femur that could prevent the closure, angular deformities, and leg-length discrep- shearing effect on the graft. ancies with transphyseal ACLR.10-12 However, a recent After analyzing the tomographic data of 8 cadaveric systematic review found no statistical difference in the knees in which the femoral tunnel had been performed incidence of leg-length discrepancies and angular de- with the technique that we present here, an average formities when comparing transphyseal and physeal- angle of 8 (range 3 to 9 ) was observed in the coronal sparing techniques.11 plane, without significant variations in the axial pro- Another concerning issue that still is not addressed in jection. With respect to the relationship between the the literature is the stress produced in the graft by the tunnel and the femoral physis, the average distance was acute angle of the femoral tunnel inside the joint. As we 4 mm (range 3 to 6) and 5 mm (range 2 to 6) in the have previously stated, when using this modification of coronal and sagittal view, respectively. Fig 6. Right knee. Anteroposterior and lateral x-ray showing no damage to the femoral physis. ACL RECONSTRUCTION IN PEDIATRIC PATIENTS e41 Table 1. Step-by-step Modification of the Hybrid Anatomic Technique for Anterior Cruciate Ligament (ACL) Reconstruction in Pediatric Patients Step Description 1 The patient is positioned supine at the operative table, with 90 knee flexion, using a distal foot support and a lateral support for the thigh. 2 The semitendinosus and gracilis tendons of the patient are harvested, and the graft is made with the aim of obtaining a minimum diameter of 8 mm. 3 A minimal cutaneous incision is made on the lateral aspect of the femur, and a longitudinal window is created on the fascia lata. The femoral insertion of the popliteal tendon and the lateral epicondyle are identified. 4 From the accessory anteromedial portal, a Pinpoint femoral guide is placed through the anterolateral portal to position it in the anatomic femoral footprint of the ACL. 5 The extra-articular end of the guide is positioned at an intermediate point between the lateral femoral structures, and a 2.4-mm guide wire is placed in an outside-in technique. 6 A full-length femoral tunnel is performed from the outside with a 4-mm drill. Once the total length of the femoral tunnel is measured, a 2.4-mm flexible needle is placed outside-in through it. 7 The flexible pin is recovered from a low anteromedial portal, and the inside-out part of the tunnel is performed with the Clancy flexible drill. 8 To perform the tibial tunnel, the usual steps of anatomic reconstruction are followed, performing progressive drilling until a diameter of 8 mm is achieved. 9 Finally, the graft is fixed in the femur with an adjustable cortical suspension device. 10 The graft is fixed at 30 flexion, using a post distal to the tibial physis or an interference screw, depending on the size of the physis. The described technique allows for an anatomic tunnel and the graft. In addition, it eliminates the need reconstruction of the ACL in pediatric patients, avoiding to use retrograde drills and thus the possibility of them the femoral physis. By making a small lateral incision, failing. Finally, we recommend this technique in pa- and identifying the lateral anatomic structures, it is tients with Tanner stages 2, 3, and 4, with tibial fixation possible to avoid the use of the image intensifier during with a post or interferential screw, depending on the surgery. With this modified procedure, it is possible to size of the tibial physis. prevent the acute killer angle between the femoral Table 2. Pearls, Pitfalls, and risks Table 3. Advantages and Limitations Pearls Advantages - The correct preoperative planning is essential to formalize the Avoids any damage to the femoral physis indication of this surgical technique Minimal or no x-rays needed - If any meniscal or chondral lesions are found, they should be Eliminates the need to use retrograde drill systems addressed before the anterior cruciate ligament reconstruction Prevents the “killer angle” between the graft and the femoral tunnel - The flexibility of the pin prevents the drill from damaging the Can be used in patients with Tanner stages 2, 3, and 4 medial femoral condyle Risks and Limitations - We recommend having previous experience in knee arthroscopy, Moderate learning curve as this is a particularly demanding technique Technically demanding procedure - A tunnel with a minimum diameter of 8 mm and 20 mm in depth Experience needed in knee arthroscopy and anterior cruciate is recommended ligament reconstruction - A dilator is placed in the tibial tunnel, and the lack of conflict Need to use specific material such as flexible guides and drills between dilator and the intercondylar notch can be verified in Risk of medial femoral condyle cartilage injury when introducing the complete extension drill through the low anteromedial portal, which is prevented using Pitfalls and Risks the flexible guide and drills - This technique should not be used extensively, as it is indicated in Risk of injury to the posterior cruciate ligament when introducing the patients with Tanner stages 2, 3, and 4 and tibial fixation with a flexible pin guide into the femur; easily avoidable when pulling the post or interferential screw, depending on the size of the tibial shuttle suture at the end of the flexible guide physis. e42 J. 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