Early ACL Reconstruction in Children With Congenital ACL Deficiency: A Prospective Case Series

BACKGROUND: Congenital absence or hypoplasia of the anterior cruciate ligament (ACL) is an uncommon condition. Children with this anomaly frequently present with knee instability, altered gait patterns, and may develop progressive deformities or early degenerative changes if untreated. Management remains debated, as some patients compensate well functionally, while some ACL reconstructions in young, skeletally immature children pose a potential risk to open physes. Conversely, early surgical stabilization may help protect the developing knee and support future reconstructive procedures, including limb-lengthening interventions. The purpose of this study was to evaluate the clinical outcomes of physeal-sparing ACL reconstruction in children with congenital ACL deficiency. METHODS: A prospective case series of 22 children (24 knees), aged 3 to 13 years, with congenital ACL deficiency and no prior ligament injury was analyzed. Skeletally immature patients with congenital ACL deficiency were prospectively recruited between 2022 and 2024. Inclusion criteria were symptomatic instability with positive anterior drawer, Lachman, and pivot-shift tests and MRI-confirmed ACL absence. Patients with traumatic ACL rupture or neuromuscular disorders were excluded. Arthroscopic-assisted ACL reconstruction was performed using a modified MacIntosh technique with an iliotibial band autograft, providing combined intra-articular and extra-articular stabilization. Pre- and postoperative assessments included clinical examination, radiographs, and magnetic resonance imaging. Follow-up ranged from 6 to 15 months for short-term outcomes. Outcomes assessed were knee stability, range of motion, graft appearance on MRI, and postoperative complications. RESULTS: Twenty-two skeletally immature patients (24 knees), aged 3 to 13 years, were included in this prospective study. Preoperatively, all knees exhibited severe anterior laxity, while most retained full motion. Frequently associated conditions included fibular hemimelia (54%), skeletal dysplasia (38%), and proximal focal femoral deficiency (8%). At final follow-up, 91.7% of knees were stable with negative Lachman and pivot-shift tests. Two knees in one patient showed persistent instability. MRI demonstrated intact grafts in 92% of knees. Full range of motion was preserved in most cases, with mild extension loss in 2 knees. No growth disturbances or angular deformities were observed during the follow-up period. Complications were limited to superficial infections in 2 cases, successfully treated. CONCLUSIONS: This large case series suggests that early physeal-sparing ACL reconstruction using an iliotibial band technique at short-term follow-up is safe and effective in restoring stability in children with congenital ACL deficiency at short-term follow-up, supporting early surgical intervention in symptomatic patients. LEVEL OF EVIDENCE: Level IV-prospective case series.