# Personalized Bone Reconstruction and Regeneration in the Treatment of Craniosomiasis
## 2 Biomaterials and Tissue Engineering Approaches  
### Biodegradable Rigid Fixation Systems  
For the rigid fixation of the fragments during the craniosynostosis surgery, initially wire sutures were used, later titanium miniplates [46]. Then, biodegradable osteosynthesis materials were introduced [51], in order to avoid a second operation, needed to remove the metallic plates, commonly 3-6 months postsurgery, due to their migration in a centripetal direction [52] as a consequence of the appositional growth of cranial bone.  
Table 3 lists the most commonly used materials used in fixation devices that are commercially available, with their composition and post-operative infection rates [53].  
Among them, LactSorb(r) is a widely used synthetic resorbable biomaterial for pediatric tissue repair that fully resorbs within 6-12 months. Diverse groups reported the outcome of bone reconstruction surgeries in CS patients using LactSorb(r); the cumulative frequency of post-operative infections in the different studies ranges from 0 to 3% (Table 3), in over 2500 patients overall, followed up until 12 months or more [54; 55; 56; 57; 58; 59; 60; 61; 62].  
Other groups tested alternative PLLA-based biodegradable fixation systems for craniofacial implants, namely, the Biosorb(r) device (Table 3), tested in a single study on 161 patients [63], and the MacroPore(r), evaluated in two independent studies including overall 86 patients [55; 64].  
Further, Inion(r) CPS baby, which consists in a blend of trimethylene carbonate, polylactic acid, and L-Lactide, D,L-Lactide, Polyglycolide (PDLLA), was used by different groups proving very low disadvantages in terms of post-operative infection risk (Table 3) [65; 66; 67; 68].  
Despite the reported advantages of efficient resorption and low post-operative infection rates, these biodegradable osteosynthesis materials are less stable and more challenging in their usage [69]. Among the major drawbacks, these devices present a complicated handling and time-consuming thread cutting with respect to the titanium plates. Furthermore, screw fixation of resorbable plates leads to stable results only when the screws are accurately applied in an orthograde direction. Thus, cutting the threads is essential though it leads to significantly prolonged surgery duration. Self-cutting screw systems (e.g., TACKERt; Inion Ltd. Tampere, Finland) can be considered as an efficient alternative, though featuring a high fracturing risk due to torsional forces applied on the junction between the screw head and neck [70].  
For these reasons, for example, [PERSON] and coworkers [71] used the SonicWelds system developed by [PERSON] (Tuttlingen, Germany) in eight patients with craniosynostosis, after successful application in animal experiments [72]. In this system, the osteosynthesis Resorb-X(r) material is fixed by inserting resorbable pins through ultrasounds (bone welding), reducing the time required for applying the osteosynthesis materials by about 50% [72]. Thus, ultrasound aided fixation using resorbable osteosynthesis materials resulted more stable than screw fixation, due to fixation in both cortical and cancellous bone. The patients were followed up for 12 months and pin fixation was stable in all cases [72].  
On the basis of the clinical experiences with the biodegradable plates and screws, it is evident that they can be considered a promising alternative to metallic plating systems in paediatric CS patients, due to their very low complication rates (wound infection and palpability of implant of less than 1%). However, their successful implantation strongly depends on the operator's experience and his/her level of expertise in cranioplastic remodelling with rigid fixation systems [54].