In this study, arthroscopy was used to perform suture anchor fixation outside the tunnel to treat children with ACL tibial fractures. The follow-up period was 25–36 months. No deformities or fracture nonunion were found in the affected limb; thus, the clinical outcome was satisfactory. The key points of this technique are as follows: (1) synovial tissue and hematoma surrounding the fracture were debrided, and the bone bed was freshened to avoid affecting fracture reduction; (2)fixation was performed using ACL tibial fixators, with the anterior and medial edges of the fracture as the chosen fixation sites. Fine Kirschner wires were used to establish the tunnels, and sutures were guided through the tunnels. Following the direction of the ACL, traction was first applied to the medial pull suture to correct the lateral displacement, then to the anterior pull suture to apply downward pressure on the fractured bone;(3) during reduction, the anterior meniscus and transverse ligament are retracted using probe hooks to avoid affecting fracture reduction; and (4) under arthroscopic monitoring, the double pulley technique was used to adjust the tension of the high-strength suture.
An ACL tibial avulsion fracture is a type of ACL injury. The flexion and rotational force of the knee joint can result in an ACL tibial avulsion fracture and displacement, ligament contracture, limited flexion and extension of the knee joint, and impaired movement. Currently, such displaced fractures are often treated using arthroscopic surgery, and a wide variety of fixation methods are available, including steel wires, high-strength sutures, cannulated screws, anchors, Kirschner wires, and so on. Steel wires offer poor toughness and non-elastic fixation; hence, breakage can occur easily during knee flexion and extension.9,10 Kirschner wire fixation causes minimal damage, but it does not offer sufficient holding power, which can easily lead to the loosening or detachment of internal fixation, thereby resulting in fracture re-displacement and affecting the function of the affected limb.11 Currently, the most commonly used method in clinical settings is the technique of using cannulated screws, which generally involves utilizing two screws to fix the fractured bone. This method is especially effective in the fixation of larger bone fractures.12 However, for pediatric patients, the relatively large diameter of cannulated screws means that the cutting action of the thread when inserting the screw can cause a more significant damage to the epiphysis. Moreover, ACL tibial fractures are smaller in children than in adult patients, which implies that screwing in and removing the fixators will cause a greater damage to the ACL tibial spine. Therefore, this method should be used with caution in pediatric patients.13 Fracture fixation with high-strength sutures are also widely used in clinical practice. It is advantageous for the fixation of comminuted ACL tibial fractures and does not require a second surgery to retrieve the fixator. However, slippage of the sutures may occur to different degrees during knee flexion and extension, which may cause cutting to the tunnel, thereby preventing early functional recovery.14,15 Internal fixation with suture anchors is one of the surgical approaches for treating ACL tibial avulsion fracture. In et al. used intra-articular suture anchors to fix the fractured bone and obtained a satisfactory clinical efficacy.16 However, they encountered difficulty in adjusting the tension of the intra-articular suture, and excessively large knots may irritate the synovium or affect joint extension. Yao et al. used intra-articular fixation with double row anchors to treat ACL tibial fractures and achieved satisfactory clinical efficacy.17 However, for pediatric patients, the relatively large diameter of the lateral row anchors implies that pre-drilling and screwing in the anchor may lead to epiphyseal damage.
Unlike in adults, the proximal tibial epiphyseal plate in children plays a crucial role in the growth and development of the lower limbs. This is of particular importance when selecting the surgical method and fixation for intra-articular fractures in this group. Jang et al. found that the 8-mm bone tunnel only damages 2.5% of the growth area of the tibial epiphyseal plate, and the damage area will decrease with age.18 Thus, avoiding epiphyseal damage as much as possible is our top priority. Not only should we consider the healing of the fracture during the post-operative follow-up, but we should also pay attention to whether there is an epiphyseal damage and an abnormal development in the affected limb. The follow-up period should, therefore, be extended accordingly. Sinha et al. adopted an epiphyseal plate evasion method for the suture fixation of ACL tibial avulsion fractures in children, and the early clinical outcomes were satisfactory.19 Using arthroscopic techniques, Liu et al. drilled across the epiphyseal plate and performed figure-8 suture fixation to treat ACL tibial avulsion fractures in children.20 No deformities were found in the lower limbs of the patients during the 2-year follow-up.
The surgical method adopted in the present study has the following advantages: (1) drilling with smooth, fine Kirschner wires can avoid epiphyseal damage caused by the drilling of coarse screw threads; (2) the same suture remains in the same tunnel, which prevents cutting of the tunnel during knee flexion and extension; (3) the surgical procedures are simple and do not require complicated winding of sutures. The two high-strength sutures are passed around posteriorly to the ACL tibial spine and pulled anteriorly. Then, the same high-strength suture is passed through the same tunnel to apply downward pressure on the upturned bone, which was subsequently followed by reduction and fixation; (4) suture anchor fixation outside the tunnel avoids the epiphysis, which only causes minimal damage to the epiphysis, and allows the tightening of the high-strength sutures for the effective fixation of the fractured bone; and (5) it involves an extra-articular knot that will not irritate the synovium or affect the flexion and extension of the joint.