Pediatric physeal repair: from immune-angiogenic-osteogenic coupling to zonal biomimetic scaffolds

Physeal injury in children can trigger bone bridge formation that arrests growth and leads to limb-length discrepancy, angular deformity, or both. Clinical bar resection with interposition reduces recurrence yet often fails to restore zonal growth-plate function. This mini review synthesizes recent bioengineering strategies that aim to prevent re-bridging while re-establishing a cartilage-permissive niche capable of supporting longitudinal growth. We focus on three platform classes that provide strong leverage for spatiotemporal control. Injectable viscoelastic hydrogels can be tuned in degradation, transport, and stress relaxation and can serve as local depots for staged factor delivery. Deterministic printed architectures prescribe geometry and invasion routes and can be combined with bioactive compartments for hybrid control. Multiphasic composites introduce interfacial gating zones that target the defining failure mode of physeal repair, namely, mineralized continuity spanning epiphysis and metaphysis. To move beyond material taxonomies, we interpret the field through four coupled and engineerable knobs: immune response, vascular invasion, osteogenic takeover with bridge continuity, and time-dependent mechanics with viscoelasticity. Across platforms, durable success is most consistently associated with early control of vascular and osteogenic access to the defect core, preservation of a diffusion-limited cartilage niche, explicit interface gating, and longitudinal functional evaluation that captures growth rather than short-term histology alone.