# MRI identification of anatomical distribution of periosteal entrapment and its clinical outcomes in pediatric distal tibial Salter-Harris type II fractures

## TL;DR

This study uses MRI to identify where periosteal entrapment occurs in pediatric tibial fractures and finds it doesn't significantly affect long-term outcomes.

## Contribution

The study maps the anatomical distribution of periosteal entrapment in S-H type II fractures and evaluates its clinical impact using MRI.

## Key findings

- Periosteal entrapment was found in all patients, mainly in the anterolateral quadrant of the distal tibial physis.
- Conservative treatment, CR-PF, and ORIF showed similar functional outcomes with no significant increase in growth disturbances.
- Residual entrapped periosteum does not appear to negatively affect fracture healing or long-term prognosis.

## Abstract

This study aimed to characterize the spatial distribution and imaging features of periosteal entrapment in pediatric distal tibial Salter-Harris (S-H) type II fractures using magnetic resonance imaging (MRI) and to evaluate its clinical outcomes.

This retrospective study analyzed 20 cases of distal tibial S-H type II fractures between 2015 and 2024. All patients underwent post-injury MRI examinations (including T1-weighted, T2-weighted, and proton density-weighted imaging sequences). The precise location of periosteal entrapment was recorded and mapped to the four quadrants of the epiphysis. All patients were divided into three groups according to the treatment method: the conservative treatment group, the closed reduction and percutaneous fixation (CR-PF) group, and the open reduction and internal fixation (ORIF) group. Outcomes evaluated included fracture healing, growth disturbances (including bone bridge formation, angular deformity, and limb-length discrepancy), and the American Orthopaedic Foot and Ankle Society (AOFAS) score at the final follow-up (≥6 months).

A total of 20 patients (16 boys and 4 girls) with an average age of 10.65 ± 2.41 years (range: 2–13 years) were included in this study, and the mean follow-up period was 22.53 months. Post-injury MRI showed periosteal entrapment in all patients, with the anterolateral quadrant being the main entrapment site (15/20, 75%). During the follow-up period, 2 patients developed growth disturbances: one patient who underwent ORIF showed a bone bridge formation on imaging, while the other patient who received CR-PF presented with ankle varus deformity without evidence of bone bridge formation. At the final follow-up, the assessment of AOFAS scores revealed no significant difference in functional outcomes among the three groups (P = 0.951).

Distal tibial S-H type II physeal fractures are at high risk of concomitant periosteal entrapment, which is localized predominantly to the anterolateral corner of the distal tibial physis. Conservative management, CR-PF, and ORIF resulted in comparable functional outcomes without significantly increasing the risk of growth disturbances, indicating that residual entrapped periosteum may not adversely affect fracture healing or long-term prognosis.