Absorbable plate strength loss during molding

Patient-specific implants made of 3D printed bioresorbable polymers at the point-of-care: material, technology, and scope of surgical application

BACKGROUND

Bioresorbable patient-specific additive-manufactured bone grafts, meshes, and plates are emerging as a promising alternative that can overcome the challenges associated with conventional off-the-shelf implants. The fabrication of patient-specific implants (PSIs) directly at the point-of-care (POC), such as hospitals, clinics, and surgical centers, allows for more flexible, faster, and more efficient processes, reducing the need for outsourcing to external manufacturers. We want to emphasize the potential advantages of producing bioresorbable polymer implants for cranio-maxillofacial surgery at the POC by highlighting its surgical applications, benefits, and limitations.

METHODS

This study describes the workflow of designing and fabricating degradable polymeric PSIs using three-dimensional (3D) printing technology. The cortical bone was segmented from the patient's computed tomography data using Materialise Mimics software, and the PSIs were designed created using Geomagic Freeform and nTopology software. The implants were finally printed via Arburg Plastic Freeforming (APF) of medical-grade poly (L-lactide-co-D, L-lactide) with 30% β-tricalcium phosphate and evaluated for fit.

RESULTS

3D printed implants using APF technology showed surfaces with highly uniform and well-connected droplets with minimal gap formation between the printed paths. For the plates and meshes, a wall thickness down to 0.8 mm could be achieved. In this study, we successfully printed plates for osteosynthesis, implants for orbital floor fractures, meshes for alveolar bone regeneration, and bone scaffolds with interconnected channels.

CONCLUSIONS

This study shows the feasibility of using 3D printing to create degradable polymeric PSIs seamlessly integrated into virtual surgical planning workflows. Implementing POC 3D printing of biodegradable PSI can potentially improve therapeutic outcomes, but regulatory compliance must be addressed.

Stable fixation using absorbable sutures in craniofacial surgery in patients over 24 months of age-a retrospective study

PURPOSE

In craniofacial surgery, the stable fixation of transposed bone segments is crucial in order to ensure good long-term results. The use of absorbable material in fixation avoids the need for a second surgery, which would otherwise be required to remove osteosynthesis material. The authors of the present manuscript have already demonstrated that absorbable sutures ensure the stable fixation of bone segments in patients up to 24 months of age. However, it has thus far remained unclear whether stable fixation is possible in older patients by using only absorbable sutures due to the slower bone remodelling and prolonged healing time in this cohort.

METHOD

For the present study, osteosynthesis was performed in 50 patients ranging from 25.7 to 192.1 months of age (mean, 61.4 ± 21.7 months) using solely absorbable sutures (PDS II®, Ethicon, Germany). Post-operative stability and possible restrictions-such as foreign body reactions-were evaluated within clinical and radiological routine follow-ups.

RESULTS

All children demonstrated clinically and radiologically stable osteosynthesis both directly post-operatively and in follow-ups. No significant foreign body reaction could be seen.

CONCLUSION

The present study demonstrates-for the first time-that absorbable sutures with a longer absorption period are also very well suited for the fixation of bone segments in patients over 24 months of age. The sole use of absorbable sutures in children over 24 months of age is a safe procedure with nearly no foreign body reactions. The procedure enables stable and highly cost-effective osteosynthesis without altering the osteotomy design.

Foreign-Body Reaction to Bioabsorbable Plate and Screw in Craniofacial Surgery

Hydroxyapatite and poly-L-lactide plates are often used for maxillofacial surgery. These plates take 3 to 4 years to resorb completely, leading to the possibility of a foreign-body reaction. A 20-year-old woman who developed a foreign-body reaction to the plates was reported. Based on review of the relevant literature, foreign-body reactions have often been reported with this plate. Long-term follow-up is warranted to evaluate patients using this plate in maxillofacial surgery.

Intracerebral foreign body granuloma caused by a resorbable plate with passive intraosseous translocation after cranioplasty

Numerous reports have demonstrated the usefulness of bioresorbable materials, but few have described severe complications caused by delayed degradation. The authors present the case of an intracranial foreign body granuloma caused by plates made of unsintered hydroxyapatite (uHA) particles and poly-l-lactide (PLLA; Super Fixsorb MX, Takiron) after cranioplasty. This 1-month-old boy presented to the authors' department with Pfeiffer syndrome. He had multiple-suture synostosis causing turribrachycephaly, Chiari malformation Type 1, and obstructive sleep apnea syndrome. At 6 months old, the child was treated with multidirectional cranial distraction osteogenesis. The uHA-PLLA plates were applied as base stones to reinforce the pins. After 16 days of distraction and 3 weeks of consolidation, the pins were removed. Seventeen months postoperatively, the plate on the right temporal bone showed passive intraosseous translocation (PIT), and by 2 years postoperatively, the plate was completely left behind in the cerebrum. At 3.5 years postoperatively, MRI disclosed a contrast-enhanced mass with surrounding brain edema at the site of the plate. The lesion was resected. The clinical history and histological specimens led to a diagnosis of foreign body granuloma surrounding the nonabsorbed resorbable plate in the dura mater. Resorbable plates are clearly useful resources in cases in which delayed absorption will not prove problematic, but careful application and follow-up is required when dealing with the growing skull given the possibility of intracranial displacement after PIT.