Titanium osteosynthesis hardware in maxillofacial trauma surgery: to remove or remain? A retrospective study

Balancing beauty and science: a review of facial implant materials in craniofacial surgery

Facial reconstruction and augmentation, integral in facial plastic surgery, address defects related to trauma, tumors infections, and congenital skeletal deficiencies. Aesthetic considerations, including age-related facial changes, involve volume loss and diminished projection, often associated with predictable changes in the facial skeleton. Autologous, allogeneic, and alloplastic implants are used to address these concerns. Autologous materials such as bone, cartilage, and fat, while longstanding options, have limitations, including unpredictability and resorption rates. Alloplastic materials, including metals, polymers, and ceramics, offer alternatives. Metals like titanium are biocompatible and used primarily in fracture fixation. Polymers, such as silicone and polyethylene, are widely used, with silicone presenting migration, bony resorption, and visibility issues. Polyethylene, particularly porous polyethylene (MedPor), was reported to have one of the lowest infection rates while it becomes incorporated into the host. Polyether-ether-ketone (PEEK) exhibits mechanical strength and compatibility with imaging modalities, with custom PEEK implants providing stable results. Acrylic materials, like poly-methylmethacrylate (PMMA), offer strength and is thus mostly used in the case of cranioplasty. Bioceramics, notably hydroxyapatite (HaP), offer osteoconductive and inductive properties, and HaP granules demonstrate stable volume retention in facial aesthetic augmentation. Combining HaP with other materials, such as PLA, may enhance mechanical stability. 3D bioprinting with HaP-based bioinks presents a promising avenue for customizable and biocompatible implants. In conclusion, various materials have been used for craniofacial augmentation, but none have definitively demonstrated superiority. Larger randomized controlled trials are essential to evaluate short- and long-term complications comprehensively, potentially revolutionizing facial balancing surgery.

A 3D dynamic finite element analysis of biomechanical behaviour of maxilla and fixative appliances following advancement Le Fort I surgery applied in different lengths

OBJECTIVES

Dynamic analysis of chewing impact on the stability of rigid fixation techniques following Le Fort I osteotomy has not been investigated in the previous literature. The aim of the present study was to evaluate segmental displacement and von Mises (VM) stress values on the fixation devices following different amounts of Le Fort I advancements under dynamic loading conditions.

MATERIALS AND METHODS

The 3D finite element models simulating 3, 5 and 8 mm advancement of maxilla at the Le Fort I level were generated using CBCT scan data. The models included two anterior L plates and two posterior I plates fixations bilaterally. Dynamic finite element analysis was performed to evaluate their biomechanical behavior against chewing cornflakes bio. Von Mises stresses and displacement values on three points were calculated.

RESULTS

Calculations were made in a time of 38, 40 and 40.5 ms for 3, 5 and 8 mm advancement models, respectively. As the advancement increased, stress values on the plates and displacement values in the D1 (intersection of the apex of the canine tooth with the osteotomy line), D2 (the most prominent point of zygomatic buttress on the osteotomy line), and D3 (intersection of the midline of the second molar tooth with the osteotomy line) points increased. The lowest stress and displacement values were found in the 3 mm advancement model. As advancement increased, the highest values were found in the I plates. The stress levels on the plates and screws remained within safe limits.

CONCLUSIONS

The von Mises stresses and displacement values tend to increase in according with the amount of advancement. More stress is transferred to posterior I plates and screws under dynamic forces.

Osteosynthesis-associated infection in maxillofacial surgery by bacterial biofilms: a retrospective cohort study of 11 years

OBJECTIVES

The aim of this retrospective cohort study was to determine risk factors for osteosynthesis-associated infections (OAI) with subsequent necessity of implant removal in oral and maxillofacial surgery.

MATERIALS AND METHODS

A total of 3937 records of patients who received either orthognathic, trauma, or reconstructive jaw surgery from 2009 to 2021 were screened for osteosynthetic material removal due to infection. Treatment-intervals, volume of applied osteosynthetic material, and respective surgical procedures were also assessed. Moreover, intraoperatively harvested microbial flora was cultured and subsequently identified by MALDI TOF. Bacteria were then screened for antibiotic resistance via VITEK system or, if necessary, via agar diffusion or epsilometer test. Data was analyzed utilizing SPSS statistical software. For statistical analysis of categorical variables, chi-square tests or Fisher exact tests were used. Continuous variables were compared via non-parametric tests. The level of significance for p-values was set at < 0.05. Descriptive analysis was also performed.

RESULTS

The lower jaw was more prone to OAI than the mid face region. Larger volumes of osteosynthetic material led to significantly more OAI, resulting in reconstruction plates bearing the highest risk for OAI especially when compared to small-volume mini-plates frequently applied in trauma surgery. Among OAI associated with implant volumes smaller than 1500 mm3, the detection of Streptococcus spp., Prevotella spp., Staphylococcus spp., and Veillonella spp. was significantly elevated, whereas implant volumes larger than 1500 mm3 showed a significant increase of Enterococcus faecalis, Proteus mirabilis and Pseudomonas aeruginosa. High susceptibility rates (87.7-95.7%) were documented for 2nd- and 3rd-generation cephalosporines and piperacillin/tazobactam.

CONCLUSION

High material load and lower jaw reconstruction bear the greatest risks for OAI. When working with large volume osteosynthetic implants, gram-negative pathogens must be considered when choosing an appropriate antibiotic regime. Suitable antibiotics include, e.g., piperacillin/tazobactam and 3rd-generation cephalosporines.

CLINICAL RELEVANCE

Osteosynthetic material utilized in reconstructive procedures of the lower jaw may be colonized with drug-resistant biofilms.

Prophylactic removal of titanium osteosynthesis miniplates in patients after midface fractures - A retrospective cohort study

The aim of the study was to evaluate prophylactic removal of titanium osteosynthesis miniplates in patients after midface fractures. Complaints after fracture treatment and complications after plate removal were analyzed, retrospectively. A total of 205 patients were included. Plate removal was performed in 99 cases. Complaints related to the osteosynthesis material resulted in more frequent plate removal (p < 0.001). Complications were noted in 22 patients after plate removal. Duration of plate removal did not correlate with postoperative complications. In 69 patients, plates were removed without previous symptoms. Of these patients, postoperative complications were recorded in 15 cases. In patients with complaints after osteosynthesis, complications after plate removal occurred in seven (23.3%) patients. Ectropia developed significantly more often with increasing age (p < 0.05). CONCLUSION: Within the limitations of the study it seems that prophylactic plate removal is a treatment option that is not associated with an increased complication rate.

In vivo biocompatibility evaluation of 3D-printed nickel-titanium fabricated by selective laser melting

Nickel-titanium (NiTi) belongs to the group of shape-memory alloys (SMAs), which are characterized by flexibility and reversible deformability. Advanced techniques in 3D printing by selective laser-melting (SLM) process allow the manufacturing of complex patient-specific implants from SMAs. Osteosynthesis materials made of NiTi could be used for minimally invasive surgical approaches in oral- and maxillofacial surgery. However, the in vivo biocompatibility has not yet been fully investigated, especially in load-sharing and load-bearing implants. The aim of this study was to evaluate the in vivo biocompatibility of SLM-produced NiTi for intraosseous and subperiosteal applications. Test specimens were implanted into the frontonasal bone of ten miniature pigs. To assess peri-implant bone metabolism, fluorescent dye was administered after 2, 4, 6, 10, 12, and 14 weeks intraperitoneally. Specimens and the surrounding tissues were harvested after 8 and 16 weeks for histological analysis. While the NiTi implants presented a higher bone-to-implant contact ratio (BIC) after 8 than after 16 weeks (43.3 vs. 40.3%), the titanium implants had a significantly higher BIC after 16 weeks (33.6 vs. 67.7%). Histologically, no signs of peri-implant inflammation or foreign-body reaction were detectable. With respect to this preliminary study design, 3D-printed NiTi shows sufficient biocompatibility for intraosseous and subperiosteal implant placement.

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.

Room Traffic in Orthopedic Surgery: A Prospective Clinical Observational Study of Time of Day

OBJECTIVE

High rates of operating room (OR) traffic may contribute to surgical air contamination and surgical site infections (SSIs). The purpose of this study was to evaluate room traffic patterns in orthopedic implant procedures to determine the frequency of door openings and if time of day had an effect on room traffic.

METHODS

In 2015, OR traffic was assessed in orthopedic implant cases. Room traffic was reported as the number of door openings per minute. Counts of how many people were present in the operating room were noted in 5-minute intervals from the time of sterile case opening to dressing placement. Operative cases were observed and categorized into 3 periods (6:00-9:59, 10:00-13:59, and 14:00-17:59) to assess if time of day affected room traffic.

RESULTS

Forty-six cases were observed for the present study. Among all cases, the mean room traffic rate was 35.2 openings per hour (SD, 10; range, 13.2-60.8). One-way analysis of variance revealed no statistically significant difference among groups (6:00-9:59 [n = 29], 10:00-13:59 [n = 10], and 14:00-17:59 [n = 7]) as it relates door openings per minute (room traffic rate) (P = 0.9237) or mean number of people in the OR (P = 0.3560). Pearson correlation revealed no correlation between case start time and room traffic rates (P = 0.6129, r2 = 0.0059) or between case start time and mean number of people in the OR (P = 0.3435, r2 = 0.0214).

CONCLUSIONS

Room traffic rates and mean number of people in the OR do not correlate with time of day of case in orthopedic implant procedures.

Is Mini-Plate Removal Necessary for Oral and Maxillofacial Surgery Patients? A Five-Year Case-Control Study

Objectives:

The purpose of this study was to determine the mini-plate and screw removal rate and reasons in maxillofacial surgery patients under previous semi-rigid fixation treatment in the past five years at the main trauma center of Mashhad.

Materials and Methods:

This was a census-based retrospective study. All the candidates who admitted to our department for maxillofacial plate removal due to symptomatic or infected mini-plates were included in this study. The patients’ age and gender, plate removal etiologies, and the time between plate insertion and removal were analyzed.

Results:

Mini-plates were inserted for 1026 patients. However, only 94 patients with a mean age of 29.4±11.1 years were candidates for plate removal. The plate removal rate was 9.16%. Infection and exposure were the most common causes of plate removal. The most prevalent removal site was the mandible (angle and body). The interval between mini-plate insertion and removal was an average of 12.9±5.6 months. It is noteworthy that the shortest lasting duration was when plate removal was secondary to pain (6.67 months) and infection (11.45 months).

Conclusion:

This research showed that the routine removal of plates does not appear to be generally indicated in healthy subjects unless there is an obvious and definitive clinical indication.

Radiographic evaluation of percutaneous transfacial wiring versus open internal fixation for surgical treatment of unstable zygomatic bone fractures

Introduction

The fixation of unstable zygomaticomaxillary complex (ZMC) fractures can be achieved by open reduction with rigid internal fixation (ORIF) and/or by closed reduction with percutaneous transfacial Kirschner wire fixation (CRWF). The aim of this study was to tomographically assess the symmetry and the protrusion of the cheekbone with unstable ZMC fractures that had been treated by ORIF vs. CRWF.

Materials and methods

Sixty patients exhibiting a surgically unstable tetrapodal ZMC fracture were included in this multicenter retrospective study. The coordinates of 5 landmarks representing the zygomatic protrusion were comparatively studied on the healthy and on the broken side using preoperative and postoperative tridimensional computed tomography (CT) scans or cone beam CT.

Results

No significant difference was found in the zygomatic protrusion irrespective of the surgical technique that was used. The zygomatico-maxillary ansa was found to be the most complicated area to reduce, particularly in the frontal plane with both the CRWF and the ORIF technique (p₁ = 0.001 and p₂ = 0.0009, respectively). There was no difference in terms of the level of complications, while the mean duration of the surgery was significantly less for the CRWF group.

Conclusion

With good postoperative radiographic outcomes, the CRWF can be proposed as an alternative or in association with the ORIF technique for fixation of tetrapodal fractures of the ZMC.

Influence of surface modifications on the degradation of standard-sized magnesium plates and healing of mandibular osteotomies in miniature pigs

Biodegradable magnesium alloys are suitable osteosynthesis materials. Despite the alloy composition, surface modifications appear to have an influence on the degradation process and biocompatibility. The aim of this study was to investigate the impact of hydrogenation and fluoridation of the surface in a mandibular osteotomy model. Standard-sized plates and screws were implanted in an osteotomy at the mandibular angle in nine miniature pigs. The plates and screws were harvested together with the adjacent tissues at 8 weeks after surgery and were investigated by micro-computed tomography and histological analysis. The bone healing of the osteotomy was undisturbed, independent of the surface properties. The adjacent bone tissue showed new bone formation at the implant surface; however, formation of some lacunae could be observed. The corrosion was between 9.8% and 11.6% (fluoridated<hydrogenated<non-modified) in histological specimens, while radiologically neither the volume nor the density of the osteosynthesis material was reduced in any treatment group. The soft tissues exhibited full biocompatibility with every surface property. In summary, surface modification by hydrogenation and fluoridation did not significantly influence bone healing, biocompatibility, or corrosion kinetics of the magnesium osteosynthesis at the mandibular angle.

No Need to Routinely Remove Titanium Implants for Maxillofacial Fractures

PURPOSE

Titanium implants are typically used to fix maxillofacial fractures and their routine removal is a controversial topic in maxillofacial surgery. This study aimed to estimate the removal rate and risk factors associated with removal.

MATERIALS AND METHODS

The authors designed and implemented a retrospective study. Adult patients who underwent open reduction and internal fixation with titanium implants for maxillofacial fractures were included and those who returned for implant removal were identified from January 2007 to December 2016. The predictor variables were gender, age, preoperative infection, injury time, trauma cause, and fracture site. The primary outcome variable was removal of titanium implants. Descriptive and bivariate statistics were computed. Kaplan-Meier survival methods were used to estimate rate of removal. Univariate and multivariate Cox proportional hazards models were used to identify risk factors associated with removal.

RESULTS

Of 2,325 patients (1,890 men and 435 women; average age, ∼35.49 yr) registered in this study, 163 (7.01%) had their titanium implants removed and 1-, 2-, and 10-year removal rates were 3, 7, and 8%, respectively. The risk factors most closely associated with removal were preoperative infection, injury by a blow from an object, obsolete fracture, and female gender.

CONCLUSIONS

Routinely removing titanium implants in patients with maxillofacial fracture is not necessary. When the risk factors listed earlier are present in these patients, follow-up should be scheduled more frequently.

Bioabsorbable plates versus metal miniplate systems for use in endoscope-assisted open reduction and internal fixation of mandibular subcondylar fractures

PURPOSE

To compare bioabsorbable plates with metal miniplate systems for use in endoscope-assisted open reduction and internal fixation (EAORIF) of mandibular subcondylar fractures.

MATERIALS AND METHODS

This retrospective cohort study included patients with mandibular subcondylar fractures treated with EAORIF using bioabsorbable unsintered hydroxyapatite/poly l-lactide composite plates or titanium miniplate systems. The outcome variables included preoperative fracture conditions, postoperative stability during fracture healing, and complications during the follow-up period. Other variables included clinical characteristics (age, sex, fracture site, and total follow-up duration) and intra- and postoperative data (surgical duration, duration of intermaxillary fixation/elastic band guidance). Variables were evaluated using descriptive statistics and compared between groups using the Mann-Whitney test and the chi-square test or Fisher's exact test, as appropriate.

RESULTS

In total, 28 patients were analyzed, including 13 who underwent EAORIF using bioabsorbable plates and 15 who underwent EAORIF using titanium miniplates. With the exception of second surgery for plate removal, none of the assessed variables showed significant differences between the two groups (p < 0.05).

CONCLUSIONS

Our results suggest that EAORIF using biodegradable plates is a stable and reliable method for the management of mandibular subcondylar fractures and eliminates the need for secondary surgery for plate removal.

Osteosynthesis of a cranio-osteoplasty with a biodegradable magnesium plate system in miniature pigs

Biodegradable magnesium alloys are a new class of implant material suitable for bone surgery. The aim of this study was to investigate plates and screws made of magnesium for osteosynthesis in comparison to titanium in a cranial fracture model. Implants were used for internal fixation of a cranio-osteoplasty in nine minipigs. Computed tomography was conducted repeatedly after surgery. The implants and the adjacent tissues were harvested 10, 20 and 30weeks after surgery and investigated by micro-computed tomography and histological analysis. The surgical procedure and the inserted osteosynthesis material were well tolerated by the animals, and the bone healing of the osteoplasty was undisturbed at all times. The adjacent bone showed formation of lacunas in the magnesium group, resulting in a lower bone-to-implant contact ratio than that of titanium (72 vs. 94% at week 30), but this did not lead to clinical side effects. Radiological measurements showed no reduction in osteosynthesis material volume, but indicated signs of degradation: distinct volumes within the magnesium osteosynthesis group had lower density in micro-computed tomography, and these volumes increased up to 9% at week 30. The histological preparations showed areas of translucency and porosity inside the magnesium, but the outer shape of the osteosynthesis material remained unchanged. No fracture or loosening of the osteosynthesis devices appeared. Soft tissue probes confirmed sufficient biocompatibility. Given their biodegradable capacity, biocompatibility, mechanical strength and visibility on radiographs, osteosynthesis plates made of magnesium alloys are suitable for internal fixation procedures.

STATEMENT OF SIGNIFICANCE

To the best of our knowledge this is the first study that used biodegradable magnesium implants for osteosynthesis in a cranial fracture model. The cranio-osteoplasty in miniature pigs allowed in vivo application of plate and screw osteosynthesis of standard-sized implants and the implementation of surgical procedures similar to those conducted on human beings. The osteosynthesis configuration, size, and mechanical properties of the magnesium implants within this study were comparable to those of titanium-based osteosynthesis materials. The results clearly show that bone healing was undisturbed in all cases and that the biocompatibility to hard- and soft tissue was sufficient. Magnesium implants might help to avoid long-term complications and secondary removal procedures due to their biodegradable properties.

Effects of degradable osteosynthesis plates of MgYREZr alloy on cell function of human osteoblasts, fibroblasts and osteosarcoma cells

The aim was to evaluate the biocompatibility of osteosynthesis plates of the MgYREZr/WE43 alloy by using human cells in vitro. Eluates of degradable magnesium osteosynthesis plates as well as halved plates were used for incubation with human osteoblasts, fibroblasts and osteosarcoma cells. The cell viability was evaluated by using FDA/PI-Staining and LDH analysis. Cell proliferation was assessed by MTT, WST-Test and BrdU-ELISA. Scanning electron microscope was used for investigation of the cell adhesion. The number of devitalized cells in all treatment groups did not significantly deviate from the control group. According to MTT results, the number of metabolically active cells was not significantly affected by the addition of the eluates. The number of metabolically active cells was reduced by 24 to 38% compared to the control on incubation in direct contact with the osteosynthesis plates. The proliferation of the cells was inhibited by the addition of the eluates. While the eluate of the half-hour elution has only a very small effect, the 24 h eluate significantly inhibits proliferation by 23-25% compared to the control. The roughened surface of the magnesium osteosynthesis plate after incubation showed adherent cells. However, some areas of the plates were also free of adherent cells. WE43 based magnesium alloys showed favorable biocompatibility considering the viability of the cells evaluated; however, proliferation rates were reduced in a time dependent manner, especially in fibroblast group. This might be a potential clinical benefit of magnesium osteosynthesis plates and their superiority to titanium, thus the fibroblastic ingrowth might negatively influence the bone-plate contact.

Can Resorbable Fixation Screws Replace Titanium Fixation Screws? A Nano-Indentation Study

PURPOSE

The aim of this study was to compare the nano-hardness and elastic modulus of titanium and resorbable screws and determine whether resorbable screws could completely replace titanium screws.

MATERIALS AND METHODS

The mechanical properties (nano-hardness and decreased elastic modulus) of TriMed titanium, resorbable Inion CPS, and Synthes RapidSorb samples were measured using a nano-indentation technique. In this study, a Hysitron TriboIndenter TI 950 with a resolution less than 1 nN and a displacement resolution of 0.04 nm was used for the nano-indentation tests. The unloading segments of the nano-indentation curves were analyzed using the method of Oliver and Pharr (J Mater Res 7:1564, 1992).

RESULTS

Statistical analysis showed that the values of the elastic modulus and nano-hardness of the TriMed titanium screws were significantly higher than those of the resorbable Inion CPS and Synthes RapidSorb screws (P < .05). A statistical difference was not observed between the values of the elastic modulus and the nano-hardness of the Inion CPS and Synthes RapidSorb screws (P > .05).

CONCLUSIONS

In this study, the resorbable screws were found to be soft and flexible compared with the titanium screw. According to the results of this nano-indentation study, resorbable and titanium screws cannot be used interchangeably.