Medial Wall Orbital Reconstruction using Unsintered Hydroxyapatite Particles/Poly L-Lactide Composite Implants

Degradation of Unsintered Hydroxyapatite and Poly-L-Lactide Composite Sheets In Vivo and In Vitro

Bioabsorbable sheet-shaped implants made of forged composites of unsintered hydroxyapatite and poly-L-lactide (F-u-HA/PLLA) have been used for orbital fracture repair with good results. This is the first report using multiple specimens implanted in the human orbit to demonstrate the biodegradation and loss of strength of F-u-HA/PLLA sheets. Among the patients who underwent various facial fracture repairs with F-u-HA/PLLA sheets implanted in their orbits, those whose sheets were subsequently extracted were included in the study. Viscosity-average molecular weight, crystallinity, and bending strength of the extracted implants were measured. An in vitro degradation test was also performed for comparison. Among the 111 patients who underwent F-u-HA/PLLA sheet implantation, 13 subsequently underwent surgical extraction of implants; the majority were due to secondary correction of complex fractures. One patient developed an infection; none developed foreign body reactions. Overall, 11 specimens from 10 patients with consent were examined. The time from implantation to extraction ranged from 43 to 632 days (median: 210 d). Compared with the results of the in vitro degradation test, the viscosity-average molecular weight and bending strength had a slower decrease. The F-u-HA/PLLA sheets retained more than 50% of their initial bending strength after 12 months. Crystallinity varied widely. F-u-HA/PLLA sheets implanted in human orbits did not degrade faster than those of in vitro testing. Sheet-shaped implants made of forged composites of unsintered hydroxyapatite and poly-L-lactide can be considered appropriate reconstructive materials for orbital fractures as they retained sufficient strength to support the orbital contents at 12 months postoperatively, and no case of delayed foreign body reactions was observed.

A Narrative Review of u-HA/PLLA, a Bioactive Resorbable Reconstruction Material: Applications in Oral and Maxillofacial Surgery

The advent of bioresorbable materials to overcome limitations and replace traditional bone-reconstruction titanium-plate systems for bone fixation, thus achieving greater efficiency and safety in medical and dental applications, has ushered in a new era in biomaterial development. Because of its bioactive osteoconductive ability and biocompatibility, the forged composite of uncalcined/unsintered hydroxyapatite and poly L-lactic acid (u-HA/PLLA) has attracted considerable interest from researchers in bone tissue engineering, as well as from clinicians, particularly for applications in maxillofacial reconstructive surgery. Thus, various in vitro studies, in vivo studies, and clinical trials have been conducted to investigate the feasibility and weaknesses of this biomaterial in oral and maxillofacial surgery. Various technical improvements have been proposed to optimize its advantages and limit its disadvantages. This narrative review presents an up-to-date, comprehensive review of u-HA/PLLA, a bioactive osteoconductive and bioresorbable bone-reconstruction and -fixation material, in the context of oral and maxillofacial surgery, notably maxillofacial trauma, orthognathic surgery, and maxillofacial reconstruction. It simultaneously introduces new trends in the development of bioresorbable materials that could used in this field. Various studies have shown the superiority of u-HA/PLLA, a third-generation bioresorbable biomaterial with high mechanical strength, biocompatibility, and bioactive osteoconductivity, compared to other bioresorbable materials. Future developments may focus on controlling its bioactivity and biodegradation rate and enhancing its mechanical strength.

A comparative study of porous polyethylene versus absorbable polydextro- and polylevolactic-lactide plate in reconstruction of isolated medial orbital wall fracture

BACKGROUND

Several materials for medial orbital wall reconstruction have been mentioned in the literature. Our main purpose was to investigate postoperative enophthalmos and diplopia after medial orbital wall reconstruction with polydextro- and polylevolactic (poly-_L/_DL) acid (P[_L/_DL]LA) mesh plates and porous polyethylene plates.

METHODS

Using a retrospective study design, we enrolled a cohort of isolated medial blowout fracture patients treated during a 58-month interval. The predictor variable was medial orbital wall reconstruction materials (P(_L/_DL)LA mesh plate and porous polyethylene plate. The main outcome variables included the occurrence of postoperative enophthalmos and diplopia at 1 week, 1, 3, 6, and 12 months post-surgery. Appropriate descriptive, uni- and bivariate statistics were computed, and P < 0.05 was considered significant.

RESULTS

Three hundred-two isolated medial blowout fracture patients were included (24.5% females, 67% treated with P(_L/_DL)LA mesh plate). Exophthalmos measured highest in both groups 1 week after surgery and decreased steadily for 6 months postoperatively. Statistically significant differences were observed between both groups at 1 week, 1 month, and 3 months after surgery, with a higher incidence of exophthalmos observed in the P(_L/_DL)LA mesh plate group (P < 0.001). No significant differences were observed at 6 and 12 months after surgery.

CONCLUSION

The occurrence of enophthalmos after medial blowout fracture reconstruction with P(_L/_DL)LA mesh plate is comparable with the use of porous polyethylene plate. Both P(_L/_DL)LA mesh and porous polyethylene plates are, therefore, reliable implants for medial orbital wall reconstruction.

Use of Unsintered Hydroxyapatite and Poly-L-lactic Acid Composite Sheets for Management of Orbital Wall Fracture

Although unsintered hydroxyapatite and poly-L-lactic acid (u-HA/PLLA) composite sheets have various applications, such as in craniomaxillofacial fractures, orthognathic surgery, and orthopedic surgery, and have been proven to be safe and effective, no studies have reported the use of u-HA/PLLA composite sheets for orbital wall reconstruction with long-term follow-up. This study reports our preliminary results using the u-HA/PLLA composite sheet for orbital wall fractures. The SuperFIXSORB MX sheet (u-HA/PLLA composite sheet; Takiron, Tokyo, Japan), with size of 30 × 50 mm and thickness of 0.5 mm, was used in all cases of hard reconstruction of the orbital bone defect. Seventy-two patients with acute orbital wall fractures (within 2 weeks after sustaining the injury) treated at the Jikei University between January 2014 and August 2016 were included. The authors evaluated the postoperative complications and the operability of the material. The authors did not observe any postoperative complications, such as infection, postoperative diplopia, or enophthalmos, due to the use of the u-HA/PLLA composite sheet. In pure orbital fractures (orbital fractures only), the mean (±standard deviation) operation time was significantly longer with combined inferior and medial wall fractures (201.1 ± 36.6 minutes; n = 11) than with inferior wall or medial wall fractures only (135.0 ± 54.4 minutes; n = 51) (Mann-Whitney U test, P < 0.001). The U-HA/PLLA composite sheet is safe and can be used for orbital wall fracture reconstruction. Further long-term functional and aesthetic assessments for infection, ocular movement disorder, enophthalmos, and any other complication are necessary.

Application of the three-dimensionally printed biodegradable polycaprolactone (PCL) mesh in repair of orbital wall fractures

PURPOSE

The present study aims to investigate the surface characteristics and biomechanical properties of 3D-printed polycaprolactone (PCL) mesh and present the clinical outcomes of this implant in the treatment of orbital wall fractures.

PATIENTS AND METHOD

A retrospective review of patients who underwent surgery for medial, inferior and inferomedial orbital wall fractures using PCL mesh was performed between April 2017 and June 2018. Two clinical outcomes were investigated: functional recovery and anatomical accuracy of reduction detected in image. Furthermore, scanning electron microscopy was used to evaluate the microscopic morphology, surface characteristics, and porosity of the PCL mesh.

RESULTS

Among a total of 22 patients with a mean age of 41.3 years, the most common cause of injury was assault (54.5%). Fourteen patients (63.6%) had isolated orbital floor fractures. At postoperative 1-week follow-up, three patients (13.6%) exhibited diplopia and a further three patients (13.6%) showed restriction in ocular motility, but these patients had completely recovered by their 6-month postoperative follow-up. Ideal repair of orbital fracture was almost achieved in 21 patients (95.4%) and there were no cases of implant infection, inflammatory response, migration of implant, or hemorrhage. Microscopic imaging of PCL mesh surface revealed fully interconnected micropores with 50% porosity.

CONCLUSIONS

The repair of orbital wall fracture using PCL mesh offers reliable stabilization of orbital wall defects with a low complication rate, leading to outstanding functional and aesthetic outcomes. Therefore, PCL mesh is a good alternative for bioresorbable implants in the treatment of orbital wall fractures.

Navigation-Assisted Orbital Trauma Reconstruction Using a Bioactive Osteoconductive/Bioresorbable u-HA/PLLA System

Orbital fractures with orbital wall defects are common facial fractures encountered by oral-maxillofacial surgeons, because of the exposed position and thin bony walls of the midface. The primary goal of surgery is to restore the pre-injury anatomy and volume of hard tissue, and to free incarcerated or prolapsed orbital tissue from the fracture by bridging the bony defects with reconstructive implant material and restoring the maxillofacial-orbital skeleton. Numerous studies have reported orbital fracture repair with a wide variety of implant materials that offer various advantages and disadvantages. The ideal orbital implant material will allow conformation to individual patients' anatomical characteristics, remain stable over time, and are radiopaque, especially for the reconstruction of relatively large and/or complex bony walls. Based on these requirements, novel uncalcined and unsintered hydroxyapatite (u-HA) particles and poly-L-lactide (PLLA; u-HA/PLLA) composite sheets could be used as innovative, bioactive, and osteoconductive/bioresorbable implant materials for orbital reconstruction. In addition, intraoperative navigation is a powerful tool. Navigation- and computer-assisted surgeries have improved execution and predictability, allowing for greater precision, accuracy, and minimal invasiveness during orbital trauma reconstructive surgery of relatively complex and large orbital wall defects with ophthalmological malfunctions and deformities. This review presents an overview of navigation-assisted orbital trauma reconstruction using a bioactive, osteoconductive/bioresorbable u-HA/PLLA system.

Navigation-Assisted Isolated Medial Orbital Wall Fracture Reconstruction Using an U-HA/PLLA Sheet via a Transcaruncular Approach

Purpose: We investigated the feasibility of isolated medial orbital wall fracture reconstruction using an unsintered hydroxyapatite particles/poly L-lactide (u-HA/PLLA) sheet implant with the assistance of intraoperative navigation via the transcaruncular approach. Patients and methods: Ten consecutive patients (5 males and 5 females; mean age, 57.5 years) were included based on the clinical and imaging criteria. All patients underwent surgical treatment of the isolated medial orbital wall fracture using transcaruncular incision and the u-HA/PLLA implant under navigation. The follow-up time was greater than 6 months. Preoperative and postoperative clinical data regarding the presence of diplopia, eye motility restriction, and enophthalmos were assessed. The orbital volumes of the injured and uninjured orbit were also evaluated using computed tomography images. Results: All patients had improved ophthalmologic functional and esthetic outcomes and were successfully treated without any long-term complications arising during follow-up. There was a significant difference between the preoperative and postoperative injured orbits due to herniation of the orbital contents. Moreover, the orbital volume of the postoperative injured side following surgery was the same as that of the unaffected side, indicating that anatomically good reconstruction had been obtained. Conclusions: Surgical treatment using the transcaruncular approach and u-HA/PLLA materials with intraoperative navigation is a safe, promising, and effective technique for isolated medial orbital wall fracture reconstruction.

Analysis of Orbital Volume Measurements Following Reduction and Internal Fixation Using Absorbable Mesh Plates and Screws for Patients With Orbital Floor Blowout Fractures

INTRODUCTION

Hinge-shaped fractures are common type of orbital floor blowout fractures, for which reduction and internal fixation is ideal. Nonetheless, orbital floor reconstruction using alloplastic materials without reducing the number of bone fragments is the most frequently used procedure. Therefore, this study analyzed and compared the outcomes between open reduction and internal fixation using absorbable mesh plates and screws, and orbital floor reconstruction, by measuring the orbital volume before and after surgery.

METHOD

Among patients with orbital floor blowout fractures, this study was conducted on 28 patients who underwent open reduction and internal fixation, and 27 patients who underwent orbital floor reconstruction from December 2008 to September 2015. The mechanism of injury, ophthalmic symptoms before and after surgery, and the degree of enophthalmos were examined; subsequently, the volumes of the affected and unaffected sides were measured before and after surgery based on computed tomography images. This study compared the degree of recovery in the correction rate of the orbital volume, ophthalmic symptoms, and enophthalmos between the 2 groups.

RESULT

The patients who underwent open reduction and internal fixation, and the patients who underwent orbital floor reconstruction showed average correction rates of 100.36% and 105.24%, respectively. Open reduction and internal fixation showed statistically, significantly superior treatment outcomes compared with orbital floor reconstruction. The ophthalmic symptoms and incidence of enophthalmos completely resolved in both groups.

CONCLUSION

For orbital floor blowout fractures, open reduction and internal fixation using absorbable mesh plates and screws was a feasible alternative to orbital floor reconstruction.