Do Patient-Specific Guides accurately correct lower limb deformities in children? Preliminary outcomes.

Introduction: Over the past decade, the use of patient-specific instrumentation (PSI) has increased exponentially as a means of improving surgical precision. In pediatric orthopedics, its adoption is more recent and differs from adult applications due to the unique characteristics of pediatric deformities and anatomical constraints, particularly the need to preserve the physis. This study aimed to assess the reliability and accuracy of PSI in performing lower limb long bone osteotomies in children.

Hypothesis: Planned corrections are comparable to the achieved corrections.

Patients and methods: This bicentric retrospective study included all PSI-assisted lower limb osteotomies performed since 2021. PSI guides were developed using bilateral CT scans. Demographic data, clinical outcomes at the final follow-up, and any complications were recorded. In all cases, postoperative three-dimensional (3D) reconstruction was performed using low-dose biplanar stereo radiography (EOS) and compared to the preoperative CT-based surgical plan. For each osteotomy, 3D measurements of the primary correction in all three planes were analyzed. Postoperative reliability was defined as the difference between the preoperative plan and the achieved correction (Δ angle). A threshold of ±3 ° was used to assess the accuracy of PSI.

Results: Eighteen patients (21 osteotomies, mean age 14.6 ± 3.4 years) were included: 52% femoral (n = 11) and 48% tibial (n = 10). At a mean follow-up of 10 ± 5 months, one intraoperative and three postoperative complications were observed. Two patients reported residual pain at the final follow-up. Planned corrections ranged from 9 ° to 85 °, with 62% exceeding 15 °. The mean Δ angle was 11 °, with no significant difference overall (p = 0.06), but a trend toward undercorrection was observed in cases with planned corrections >15 ° (p = 0.03).

Discussion: The use of PSI in pediatric lower limb osteotomies tends to result in undercorrection compared to the planification, particularly in case of severe deformity. This may be explained by the greater magnitude of corrections typically required in pediatric patients compared to adults. Although these findings require confirmation through larger cohorts and 3D postoperative analysis, they should be considered when using PSI in pediatric lower limb osteotomies.

Level of evidence: III; Retrospective case-control study.