A Retrospective Analysis of 101 Zygomatico-Orbital Fractures

Orbital floor fractures in Taiwan: A 10-year nationwide population-based study

PURPOSE

To characterize the epidemiology, associated complications, and risk factors of orbital floor fractures in a nationwide longitudinal health insurance database.

MATERIALS AND METHODS

Claims data from a million randomly selected registered residents from the Taiwan National Health Insurance Research Database were analyzed between 2001 and 2011 as part of a retrospective cohort review. Patients were identified using the International Classification of Disease-9 diagnosis codes for orbital floor fracture (closed: 802.6; open: 802.7). The cases were categorized as surgical or nonsurgical based on the procedure codes and compared statistically.

RESULTS

From 2001 to 2011, 663 patients were diagnosed with orbital floor fractures out of a total population at risk of 9,836,431 person-years (average incidence: 6.78 persons/100,000/year) with overall increasing incidence. Surgical treatments were performed in 213 (32%) patients. Patients who received surgical treatment were younger than those who did not (mean age 25.3 ± 13.6 years vs. 34.2 ± 18.6 years, P < 0.001). The diagnosis with diplopia was a significantly associated factor for surgical treatment (2.2% in nonsurgery group vs. 6.6% in surgery group, P = 0.007). Male gender (adjusted hazard ratios [aHR] = 2.1, 95% confidence interval [CI]: 1.79-2.49) and low monthly income (aHR = 1.76, 95% CI: 1.16-2.67) were the risk factors for orbital floor fracture.

CONCLUSION

The incidence of orbital floor fractures increased in the Taiwanese population between 2001 and 2011. Men and low income patients were at increased risk of orbital floor fracture. More research is necessary to clarify what factors are driving the escalating incidence of orbital fractures in this national population.

Primary reconstruction of combined orbital and zygomatic complex fractures with patient-specific milled titanium implants - A retrospective study

The aim of this retrospective study was to compare mid-facial symmetry and clinical outcomes between patients treated with patient-specific and standard implants in primary fracture reconstructions of combined orbital and zygomaticomaxillary complex fractures. Patients who underwent primary reconstruction of orbital and zygomaticomaxillary complex fractures during the study period were identified and background and clinical variables and computed tomography images were collected from patient records. Zygomaticomaxillary complex dislocation and orbital volume were measured from pre- and postoperative images and compared between groups. Out of 165 primary orbital reconstructions, eight patients treated with patient-specific and 12 patients treated with standard implants were identified with mean follow-up time of was 110 days and 121 days, respectively. Postoperative orbital volume difference was similar between groups (0.2 ml for patient-specific vs 0.3 ml for standard implants, p = 0.942) despite larger preoperative difference in patient-specific implant group (2.1 ml vs 1,5 ml, p = 0.428), although no statistical differences were obtained in symmetricity or accuracy between the reconstruction groups. Within the limitations of the study it seems that patient-specific implants are a viable option for primary reconstructions of combined zygomaticomaxillary complex and orbital fractures, because with patient-specific implants at least as symmetrical results as with standard implants can be obtained in a single surgery.

Biomechanical Impact of a Zygoma Complex Fracture Using Human Cadaver

ABSTRACT

Zygomaticomaxillary complex fractures are common in midface trauma, with treatment often involving repair using titanium mini plates. However, the need for plate fixation along the zygomaticomaxillary suture on the infraorbital rim remains controversial. This study utilized a previously reported bite force simulator to investigate craniofacial strain patterns following zygomaticomaxillary complex fracture repairs with and without plating of the infraorbital rim. Osteotomies were made to 6 fresh-frozen cadaveric heads to simulate 2 types of zygomatic complex fractures: a dipod fracture with osteotomies at the zygomaticofrontal and zygomaticomaxillary sutures, and a tripod fracture with an additional osteotomies at the zygomaticotemporal suture. Repairs with and without the use of a titanium mini plate across the infraorbital rim were compared in both dipod and tripod fractures. Physiologically proportional masticatory loads were applied using the bite force simulator by actuating intrinsic muscle lines of action. The outcome metric was facial bone strains measured using uniaxial strain gauges. Mixed-effects linear models did not find a significant main effect on the overall strain pattern with the use of an infraorbital rim plate in both dipod (P = 0.198) and tripod (P = 0.117) fracture repairs. However, statistically significant differences were found locally at the zygomatic buttress (P = 0.019) and the zygomatic arch (P = 0.027) on the fractured side in dipod fractures. This is the first known study that successfully utilized a mechanical simulator to reproduce physiological intrinsic masticatory loads in a fracture fixation study. This new technology opens avenues for future biomechanical investigations on maxillofacial fracture repairs and other surgical treatments.

Efficacy of Altered Two-Point Fixation in Zygomaticomaxillary Complex Fracture

PURPOSE

To reconstruct a zygomaticomaxillary complex (ZMC) fracture, zygomaticofrontal (ZF) suture is the most reliable site to assess anatomical alignment and to secure rigidity. It has been chosen primary site to be fixed, but approach through the lateral eyebrow incision may leave a visible scar. This study suggests altered two-point fixation of ZMC fracture without accessing the ZF suture.

METHODS

In the retrospective study, a total of 40 patients with ZMC fracture were divided into two groups (group 1, two-point fixation and group 2, three-point fixation). Patient demographics and follow-up were evaluated, and degree of reduction including cortical gaps of ZF and inferior orbital (IO) area, protruding difference of zygoma, and malar difference using asymmetry index were measured through preoperative and postoperative CT.

RESULTS

Preoperatively, the means of ZF displacement, IO displacement, protruding difference of zygoma, and facial asymmetry index between the groups were not statistically different. The result was the same after the operation. However, all variables were significantly different before and after surgery within each group. Moreover, mean operation time was significantly different between groups (P value = 0.026).

CONCLUSION

Altered two-point fixation in ZMC fracture excluding incision approaching the ZF provides surgical efficacy and similar surgical outcomes to three-point fixation but offers reduced operation time and fewer complications.

Correlation of Clinical Findings With Computed Tomography in Orbital Traumas

BACKGROUND

Although the eye is a well-protected organ, it is frequently affected by trauma. The timely detection of ocular injuries is extremely important. In this study, the authors evaluated the consistency between findings in computed tomography (CT) examination for orbital fractures and globe integrity and clinical findings in patients presenting to the emergency department due to orbital trauma.

METHODS

The authors retrospectively reviewed the files of patients presenting with orbital trauma between January 2015 and January 2018 from emergency department records. Ophthalmology consultation and follow-up notes, radiology reports, and the emergency physician's notes were reviewed.

RESULTS

During the study period, 286 patients presented to the emergency department with orbital trauma. A total of 119 eyes of 83 patients who underwent orbital CT were included in the study. Orbital bone fracture was detected in 54.6% (n = 65) of the eyes. Of these, 73.8% (n = 48) involved multiple fractures. Among all eyes, the distribution of fractures in the orbital walls was lateral wall in 41.2% (n = 49), floor in 32.8% (n = 39), medial wall in 31.1% (n = 37), and roof in 10.9% (n = 13). Multiple wall fractures were detected in 36.9% (n = 44) of the eyes. At least 1 clinical finding such as diplopia, laceration, abnormal pupillary response, hypoesthesia, and exophthalmos was observed in 47.1% (n = 56) of the eyes. This rate was 56.8% among eyes with orbital fractures and 35.2% in those without fracture. There was a statistically significant relationship between floor fractures and diplopia (P = 0.002). No significant correlations were found between the other radiological and clinical findings.

CONCLUSION

Our study revealed a relationship between the presence of orbital fracture and eye damage. In particular, the authors found that the frequency of diplopia was significantly higher in eyes with maxillary bone fracture in the orbital floor. However, orbital CT findings other than bone fracture were not consistent with clinical findings.

Predictors of enophthalmos among adult patients with pure orbital blowout fractures

The aim of this study was to determine the predictors of post-traumatic enophthalmos (PE) in relation to the internal orbital changes following pure orbital blowout fractures. The design was a 10-year retrospective cross-sectional study analysing 629 medical records and computed tomography (CT) data of patients with orbital fractures from January 2008 to January 2017. Demographic, etiology, co-morbidity and clinical characteristics were obtained from the medical records. Assessment of the PE, fracture site and size, intraorbital structures and muscle change were performed using the Digital Imaging and Communications in Medicine (DICOM) viewer software, OsiriX v5.8.2. Of the 629 patients with orbital fractures, 87 were pure orbital blowout fractures. Demographic pattern showed that males outnumbered females in the series, with male: female ratio of 5.7:1. The mean age was 37.2 ± 14.7 and the main etiology was motor vehicle accident. Orbital floor fracture was the most common fracture location (67.8%). The involvement of the posterior ledge and inferior orbital fissure showed statistical significant difference with PE (Fisher's exact test, p = 0.03). Binary logistic regression showed that after controlling for age, patients with fracture size of more than 150 mm2 had three times the odds of sustaining a PE, (adjusted odds ratio (AOR) = 3.01 (95% CI 1.17-7.92). Fracture size larger than 150 mm2 was a radiological predictor of PE. Additional research investigating further on the role of concurrent fracture of the posterior ledge and inferior orbital fissure is advocated.

Etiology of orbital fractures at a level I trauma center in a large metropolitan city

Background/Purpose:

Orbital fractures are a common facial fracture managed by multiple surgical specialties. Methods: A retrospective review of the electronic medical records of patients (age, 18–85 years) presenting to Northwestern Memorial Hospital and Northwestern Medical Faculty Foundation in Chicago, IL, USA with International Classification of Diseases, Ninth Revision codes for facial fractures or CPT (Current Procedural Terminology) codes for orbital fracture repair.

Results:

A review of the electronic medical records identified 504 individual incidents of orbital fractures with available imaging for review. The most common location for an orbital fracture was a floor fracture (48.0%) followed by a medial wall fracture (25.2%). Left-sided orbital fractures were statistically significantly more common than right-sided orbital fractures (99% confidence interval). Orbital fractures were more prevalent in younger age groups. The mean patient age was 39.3 years. The most common cause of all orbital fractures was assault followed by falls. However, falls were the most common cause of orbital fractures in women and in patients aged 50 years and older. Evaluation by an ophthalmologist occurred in 62.8% of orbital fracture patients, and evaluation by a team comprising the facial trauma service (Otolaryngology, Plastic Surgery, and Oral and Maxillofacial Surgery) occurred in 81.9% of orbital fracture patients.

Conclusion:

Assault was the largest cause of all orbital fractures, and occurred most commonly in young males. Assaulted patients were more likely to have left-sided fractures compared to nonassaulted patients. In patients aged 50 years and older, falls were the most common cause of orbital fractures.

Clinical analysis of midfacial fractures

Purpose:

To analyze the features of midfacial fractures.

Methods:

Data of 320 patients treated for midfacial fractures during the past 10 years were retrospectively analyzed.

Results:

Patients were 192 male and 128 female. Their age ranged from 1 to 96 years old with the average of 42.1. Injury most frequently occurred by traffic accidents in 168 patients, followed by falls in 78, assaults in 31 and sports in 25. Pattern of the fractures was classified into zygoma in 159 patients, alveolus in 60, multiple sites in 54, maxilla in 45 and nasal bone in 2. Facial injury severity scale ranged from 1 to 12 with the average of 1.52. Injuries to other sites of the body were found in 90 patients. Fractures of multiple sites showed higher facial injury severity scale and were associated with injuries to other sites of the body at a higher rate. Observation was most frequently chosen in 153 patients, followed by open reduction and internal fixation in 72, intramaxillary fixation in 43 and transcutaneous reduction in 26.

Conclusions:

Midfacial fractures showed a variety of features in terms of the site and severity and associated injuries. Understanding these features is important to manage these patients properly.

Comparison of pre-bent titanium mesh versus polyethylene implants in patient specific orbital reconstructions

Introduction

Computerized tomography DICOM file can be relatively easily transformed to a virtual 3D model. With the help of additional software we are able to create the mirrored model of an undamaged orbit and on this basis produce an individual implant for the patient Authors decided to apply implants with any thickness, which are authors own invention to obtain volumetric support and more stable orbital wall reconstruction outcome. Material of choice was ultra-high molecular weight polyethylene (UHMWPE).

Objective

The aim of this study was to present and compare functional results of individual reconstructions of orbital wall using either titanium mesh or ultra-high molecular weight polyethylene.

Materials and methods

57 consecutive patients affected by orbital wall fracture (46 males, 11 females, mean age 34±14 year) were treated in Department of Maxillofacial Surgery from 2010 to 2012. In the first group we used patient specific treatment by titanium mesh shaped on a 3D printed model of a mirrored intact orbit (37 orbits) or by individually manufactured UHMW-PE implantby CAM milling in second group (20 orbits). All of these patients were subjected to preoperative helical computerized tomography and consultation of an ophthalmologist (including binocular single vision loss test - BSVL). Further on, patients were operated under general anaesthesia using transconjuctival approach. BSVL was again evaluated post-operationally in 1 month and 6 months later.

Results

Functional treatment results (BSVL) for both groups were similar in 1 month as well as 6 months post operational time. There was no statistically significant difference between these two groups.

Conclusions

This study of 6 months functional result assessment of pre-bent individual implants and CNC milled ultra-high molecular weight polyethylene of the orbital wall has shown it to be a predictable reconstruction method. Individually shaped UHMWPE seems to be as good as pre-bent titanium mesh.

Zygomaticomaxillary complex fractures and their association with naso-orbito-ethmoid fractures: a 5-year review

BACKGROUND

Zygomaticomaxillary complex fractures associated with ipsilateral naso-orbito-ethmoidal fractures are more complex injuries than isolated zygomaticomaxillary complex fractures. This injury pattern can have significant long-term morbidity if not recognized and treated appropriately during the initial operation. The purpose of this study is to compare mechanisms of injury, treatment, and outcome between patients with zygomaticomaxillary complex fractures and those with zygomaticomaxillary complex and ipsilateral naso-orbito-ethmoidal fractures.

METHODS

A 5-year retrospective review of all patients treated with zygomaticomaxillary complex fractures at a level I trauma center was performed. Computed tomographic scans were reviewed to divide patients into those with zygomaticomaxillary complex fractures alone and those with zygomaticomaxillary complex and ipsilateral naso-orbito-ethmoidal fractures. Demographics, treatment protocols, outcomes, complications, reoperations, and length of follow-up were identified for both groups and compared to determine differences between these populations.

RESULTS

A total of 245 patients were identified by the Current Procedural Terminology codes for zygomaticomaxillary complex fractures. One hundred eighty-five patients had zygomaticomaxillary complex fractures and 60 patients had zygomaticomaxillary complex/naso-orbito-ethmoidal injuries. The demographics for both populations were similar. There are differences between the groups with regard to mechanism of injury, operative findings, and techniques. The patients with zygomaticomaxillary complex/naso-orbito-ethmoidal fractures had higher rates of postoperative complications and deformities.

CONCLUSIONS

Patients who sustain a zygomaticomaxillary complex fracture associated with an ipsilateral naso-orbito-ethmoidal fracture have a higher incidence of postoperative complications and deformities. It is important to recognize this fracture pattern early to help minimize postoperative morbidity.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Analysis of zygomatic fractures

The purpose of this study was to evaluate the natural history of zygomatic fractures in 469 cases over 14 years. The medical records of patients seeking treatment for zygomatic fractures were reviewed. The zygomatic fractures were classified as monopod, dipod, or tripod fractures for most patients. The monopod fractures included (1) zygomaticofrontal, (2) zygomaticomaxillary, and (3) zygomatic arch fractures. The dipod fractures were subclassified into 3 types according to combination of the previously mentioned 3 sites, which were 1 and 2, 1 and 3, and 2 and 3. Tripod fracture included all 1, 2, and 3. Among 469 cases of zygomatic fractures, tripod fractures (n = 238, 50.7%), zygomaticomaxillary fracture (n = 121, 25.8%), and isolated fracture of the zygomatic arch (n = 98 20.9%) formed most of the cases (n = 457, 97.4%). About one-half cases were tripod fractures (n = 238, 50.7%), and another half cases were monopod fractures (n = 220, 46.9%). Only 11 cases (2.4%) were dipod fractures. Most of the monopod fractures were zygomaticomaxillary (n = 121, 25.8%) and zygomatic arch fractures (n = 98, 20.9%). Among the dipod fractures, no cases of zygomaticofrontal and zygomatic arch fractures were reported. An open reduction was performed in 73.8% (346 cases), closed reduction in 24.5% (115 cases), and conservative treatment in only 1.7%. In tripod fracture (n = 238), an open reduction and internal fixation was performed for most of the cases (n = 225, 94.5%), and closed reduction was performed in only 11 cases (4.6%). In monopod zygomaticomaxillary fracture (n = 121), internal fixation was performed for most of the cases (n = 108, 89.3%), and closed reduction was performed in only 9 cases (7.7%). However, in monopod fracture of the zygomatic arch (n = 98), most of the cases (n = 95, 96.9%) were treated with closed reduction; open reduction was performed in only 1 case (1.0%). At zygomaticofrontal area (n = 241), internal fixation was performed in most of the cases (n = 198, 82.2%). At the infraorbital rim (n = 364), internal fixation was carried out in most cases (n = 257, 70.6%). At the zygomaticomaxillary buttress (n = 279), internal fixation was performed in about one third of the cases (n = 91, 32.6%). At the zygomatic arch (n = 339), only 1 case (0.3%) was fixed internally. The postoperative complication rate occurred in 88 cases (19.1%) among 461 cases operated. The most common complication was hypesthesia (50 cases, 56.8%), followed by diplopia (15 cases, 17.0%), limitation of mouth opening or closure (11 cases, 12.5%), infection (6.8%), and hematoma (4.5%). Most patients with hypesthesia improved at 2 months. About 90% of the patients with diplopia improved within 2 months. Limitation of mouth opening was improved immediately after operation in most of the cases. Our findings demonstrate significant differences in the demographics and clinical presentation that will enable a more accurate diagnosis and prediction of concomitant injuries and sequelae.

Three-dimensional analysis of zygomatic-maxillary complex fracture patterns

Zygomatic-maxillary (ZMC) complex fractures are a common consequence of facial trauma. In this retrospective study, we present a novel method of ZMC fracture pattern analysis, utilizing three-dimensional visualization of computed tomography (CT) images to record displacement of the malar eminence in a three-dimensional coordinate plane. The pattern of fracture was then correlated with treatment outcome. Facial CT scans were obtained from 29 patients with unilateral ZMC fractures and 30 subjects without fractures and analyzed. Briefly, displacement of the malar eminence (ME) on the fractured side was measured in medial-lateral (x), superior-inferior (y), and anterior-posterior (z) dimensions, as well as Euclidean distance, by comparison to ME location on the unfractured side. Baseline natural variance in asymmetry was accounted for by comparing ME location on the left and right sides in subjects without fractures. Patients who required open reduction and internal fixation (ORIF) to repair the ZMC fracture alone had significantly greater cumulative ME displacements than patients who did not require ORIF (p = 0.02). Additionally, patients with a high fracture score of 3, 4, or 5 (assigned based on severity displacement in each dimension) had significantly higher rates of ORIF than patients with a low fracture score of 0, 1, or 2 (p = 0.05). Severe displacement in one or more dimensions was associated with higher rates of ORIF than seen in patients with only neutral or mild displacements in all dimensions (p = 0.05). Severe x displacement was most strongly correlated with surgical intervention (p = 0.02). Overall, orbital floor repair was less strongly associated with most displacement measures than ZMC repair alone; however, patients requiring orbital floor repair had greater Euclidean ME displacements than patients who did not require orbital floor repair (p = 0.02). Fracture severity, as determined by multiple parameters in this novel evaluation system, is associated with higher rates of ORIF in patients with unilateral ZMC fractures. Determination of ZMC fracture pattern may thus be informative when considering treatment options.

A retrospective study of zygomatico-orbital complex and/or zygomatic arch fractures over a 71-month period

BACKGROUND/AIM

The aim of this retrospective study was to evaluate the epidemiology, treatment, and complications of zygomatico-orbital complex (ZOC) and/or zygomatic arch (ZA) fractures either associated with other facial fractures or not over a 71-month period.

MATERIAL AND METHODS

This survey was performed in three hospitals of Ribeirao Preto in Sao Paulo, Brazil, from August 2002 to July 2008. The records of 1575 patients with facial trauma were reviewed. There were 140 cases of ZOC and ZA fractures either associated with other facial fractures or not. Data regarding gender, age, race, addictions, day of trauma, etiology, signs and symptoms, oral hygiene condition, day of initial evaluation, hospital admission, day of surgery, surgery approach, pattern of fractures, treatment performed, post-operative antibiotic therapy, day of hospital discharge, and post-operative complications were collected. The data were subjected to descriptive statistical analyses.

RESULTS

The most frequent fractures affected Caucasian men and occurred during the fourth decade of life. The most frequent etiology was traffic accident, and symptoms and signs included pain and edema. Type I fractures were the main injury observed, and the treatment of choice was always rigid internal fixation. Post-operative antibiotic therapy was solely employed when there was an indication. Complications were observed in 13.1% of the cases.

CONCLUSIONS

The treatment protocol yielded suitable post-operative results and also showed success rates comparable to published data around the world.

Macroporous hydrogels upregulate osteogenic signal expression and promote bone regeneration

The objective of this work was to investigate the effects of macroporous hydrogel architecture on the osteogenic signal expression and differentiation of human mesenchymal stem cells (hMSCs). In particular, we have proposed a tissue engineering approach for orbital bone repair based on a cyclic acetal biomaterial formed from 5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD) and poly(ethylene glycol) diacrylate (PEGDA). The EHD monomer and PEGDA polymer may be fabricated into macroporous EH-PEG hydrogels by radical polymerization and subsequent porogen leaching, a novel technique for hydrophilic gels. We hypothesized that EH-PEG hydrogel macroporosity facilitates intercellular signaling among hMSCs. To investigate this phenomenon, hMSCs were loaded into EH-PEG hydrogels with varying pore size and porosity. The viability of hMSCs, the expression of bone morphogenetic protein-2 (BMP-2), BMP receptor type 1A, and BMP receptor type 2 by hMSCs, and the differentiation of hMSCs were then assessed. Results demonstrate that macroporous EH-PEG hydrogels support hMSCs and that this macroporous environment promotes a dramatic increase in BMP-2 expression by hMSCs. This upregulation of BMP-2 expression is associated by a more rapid hMSC differentiation, as measured by alkaline phosphatase expression. Altering hMSC interactions with the EH-PEG hydrogel surface, by the addition of fibronectin, did not appear to augment BMP-2 expression. We therefore speculate that EH-PEG hydrogel macroporosity facilitates autocrine and paracrine signaling by localizing endogenously expressed factors within the hydrogel's pores and thus promotes hMSC osteoblastic differentiation and bone regeneration.

Evaluation of a single miniplate use in treatment of zygomatic bone fracture

Different methods of internal fixation of simple displaced zygomatic fracture, such as wiring, miniplate, and screw fixation, were compared for postreduction rotational stability caused by muscular forces. This study was performed to evaluate the minimally invasive therapy in cases of zygomatic bone fracture. Seventeen patients were treated by percutaneous hook reduction and miniplate fixation along the frontozygomatic suture. Postoperatively, repositioning of aesthetic and stability and also bone ends approximation were assessed clinically and radiologically. The patients were followed up for 6 to 49 months. Preoperative symptoms were subsided except the infraorbital sensitivity disturbances in one of the patients. Postoperative complications such as diplopia and hematoma were minimal and subsided by time. In this study, orbitozygomatic, commuted, and zygomatic bone fractures simultaneously with diplopia were excluded. We showed that treatment of an isolated zygomatic bone fracture according to aesthetic and functional requirements may be achieved by insertion of a single miniplate at the lateral rim of the orbit.

Tissue response and orbital floor regeneration using cyclic acetal hydrogels

Orbital floor injuries are a common form of traumatic craniofacial injury that may not heal properly through the body's endogenous response. Reconstruction is often necessary, and an optimal method does not exist. We propose a tissue engineering approach for orbital bone repair based upon a cyclic acetal biomaterial formed from 5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD) and poly(ethylene glycol) diacrylate (PEGDA). The EHD monomer and PEGDA polymer may be fabricated into an EH-PEG hydrogel by radical polymerization. The objectives of this work were to study (1) the tissue response to EH-PEG hydrogels in an orbital bone defect and (2) the induction of bone formation by delivery of bone morphogenetic protein-2 (BMP-2) from EH-PEG hydrogels. EH-PEG hydrogels were fabricated and implanted into an 8-mm rabbit orbital floor defect. Experimental groups included unloaded EH-PEG hydrogels, and EH-PEG hydrogels containing 0.25 microg and 2.5 microg BMP-2/implant. Results demonstrated that the unloaded hydrogel was initially bordered by a fibrin clot and then by fibrous encapsulation. BMP-2 loaded EH-PEG hydrogels, independent of concentration, were surrounded by fibroblasts at both time points. Histological analysis also demonstrated that significant bone growth was present at the 2.5 microg BMP-2/implant group at 28 days. This work demonstrates that the EH-PEG construct is a viable option for use and delivery of BMP-2 in vivo.

Reconstruction of the zygomatic arch using a mandibular adaption plate

Zygomatic complex fractures are one of the most common facial fractures treated by maxillofacial surgeons. Because of the importance of the zygomatic complex in midfacial skeletal orientation, comminuted zygomatic arch fractures can lead to significant morbidity and deformity. Common repair modalities include closed reduction via a Gilles approach, open reduction and internal fixation with screws and/or plating systems, primary bone grafting, and/or biosynthetics. In patients with significant comminution and arch defects, who are poor candidates for bone grafting, reconstruction can be difficult. In this clinical report, we present 2 patients with comminuted zygomatic arch fractures and significant bony defects, who were reconstructed with mandibular adaption plates alone without primary bone grafting. Over a mean follow-up period of 12.5 months, both patients healed well without any complications and had acceptable cosmetic outcomes.

Combined fixation with plates and transmalar Kirschner wires for zygomatic fractures

After repair of a fractured zygoma, the fixed zygoma occasionally becomes displaced. This phenomenon--generally called "relapse"--is a complication that can be prevented by fixing plural sites with plates. However, this impairs blood supply to the bone, which causes atrophy. To solve this dilemma, we developed a new concept for fixing the zygoma. Fractured zygomas are fixed by combining plate fixation at a single site with transmalar fixation with Kirschner wires. This secures stability of the fixed zygoma without impairing its blood supply. We evaluated the stability of fractured zygomas fixed by our method by doing dynamic experiments using simulation models. The stresses at the screw-bone interfaces were significantly reduced by the additional transmalar fixation with wire, indicating that zygomas fixed by our method are less likely to relapse than zygomas fixed with a single plate. We also reviewed the outcomes of patients treated by our method, which indicates its clinical usefulness.