A recent approach comes up with the idea of injectable polymers as 4D materials combining the minimally invasive delivery with advanced healing capabilities. These materials can respond to physiological stimuli, leading to controlled and time-dependent transformations that enhance bone healing. Mainly, acrylate-based compounds have been used as bone grafts due to their high mechanical strength and good biocompatibility as mentioned previously. These compounds are light-sensitive and crosslink on exposure to specific wavelength for a specific range of time. However, polymerization method using chemical or thermal initiators is usually slow and also, non-degradable diluents make it inefficient for clinical usage. That's why, photocrosslinking has been evolved as a solution which is a single paste formulation and have control over setting reaction by exposing it to specific wavelength of light in a short range of time faster and easier to handle . However, these polymers responding to physiological stimulus like temperature and pH, including light, have been used in bone regeneration. Table provides some examples of injectable polymers used as 4D materials for bone repair. Matsui et al. founds that PEG-ALN responds to acidic pH and selectively accumulates at fracture site promoting bone healing. It has the potential to be a versatile treatment for intractable fractures as, it induces bone formation and inhibits bone resorption at inflammatory phase.