Intramedullary versus crossed pinning for paediatric distal radius fractures: clinical decision patterns and biomechanical validation integrating real-world practice with growth plate stress finite element analysis

This observational study characterized clinical outcomes and decision patterns for intramedullary (IM) versus crossed pinning (CP) in paediatric distal radius fractures, integrating real-world practice with growth plate-inclusive finite element analysis (FEA) to elucidate biomechanical profiles, particularly physeal safety. Retrospective analysis of 102 children (43 IM, 59 CP) undergoing closed reduction and percutaneous fixation (2018–2023). Baseline differences included younger age (IM 8.3 ± 2.7 vs. CP 12.3 ± 3.3 years, p < 0.001) and more proximal fractures (IM 25.0 ± 6.1 vs. CP 15.9 ± 2.7 mm from physis, p < 0.001). Outcomes included Gartland–Werley score, complications, and radiographic parameters. FEA simulated axial (100 N) and torsional (1 N·m) loads at 15 mm and extended 25 mm fracture locations, with sensitivity analysis on growth plate modulus. Functional outcomes were excellent and equivalent (Gartland–Werley: IM 0.26 ± 0.54 vs. CP 0.49 ± 0.78, p = 0.22). No growth arrest occurred. A nonsignificant infection trend favored IM (1/43 vs. 5/59, p = 0.22). Both groups achieved equivalent immediate postoperative alignment. FEA showed comparable axial stability at both locations. Under torsion, CP demonstrated superior stability (15 mm: 25–26% less displacement/physeal stress; amplified to 41–42% less at 25 mm), with trends robust to modulus variation. Both techniques yielded excellent outcomes when applied per observed patterns (IM for younger/proximal; CP for older/distal fractures). Position-dependent FEA insights, showing enhanced CP torsional advantages proximally, support an observed clinical practice pattern suggesting an approximate 20–25 mm threshold that warrants prospective validation. Limitations include retrospective design, unmodeled cast effects, and FEA simplifications.