Human amniotic membrane (hAM) and collagen nerve wraps are biomaterials that have been investigated as therapies for improving outcomes of peripheral nerve regeneration; however, their efficacy has not been compared. The purpose of this study is to compare the efficacy of collagen and human amniotic membrane nerve wraps in a rodent sciatic nerve reverse autograft model. Lewis rats (n = 29) underwent sciatic nerve injury and repair in which a 10-mm gap was bridged with reverse autograft combined with either no nerve wrap (control), collagen nerve wrap or hAM nerve wrap. Behavioral analyses were performed at baseline and 4, 8 and 12 weeks. Electrophysiological studies were conducted at 8, 10 and 12 weeks. Additional outcomes assessed included gastrocnemius muscle weights, nerve adhesions, axonal regeneration and scarring at 12 weeks. Application of both collagen and hAM nerve wraps resulted in improvement of functional and histologic outcomes when compared with controls, with a greater magnitude of improvement for the experimental group treated with hAM nerve wraps. hAM-treated animals had significantly higher numbers of axons compared to control animals (p < 0.05) and significantly less perineural fibrosis than both control and collagen treated nerves (p < 0.05). The ratio of experimental to control gastrocnemius weights was significantly greater in hAM compared to control samples (p < 0.05). We conclude that hAM nerve wraps are a promising biomaterial that is effective for improving outcomes of peripheral nerve regeneration, resulting in superior nerve regeneration and functional recovery compared to collagen nerve wraps and controls.
Background: Advances in surgical planning and 3-dimensional (3D) printing have benefitted the field of craniomaxillofacial surgery by allowing visualization of patient anatomy in settings of otherwise restricted surgical fields. Long 3D print times limit the usability of surgical planning workflows in acute trauma reconstruction. We sought to identify variables affecting print time and produce rapid-printed models with sufficient quality for prebending osteosynthesis plates. Methods: Three-dimensional printing variables, including resolution, print orientation, and region of interest cropping, were optimized on a single mandibular and midface fracture model to maximize print time efficiency. Five mandibular and 5 midface fractures were printed both in the high-resolution and time-efficient protocol. Fixation plates were contoured to fit the optimized models and computed tomography scan. Distances and volumes between the fracture surface and plate were computed. Results: High-resolution mandible models were printed in 7.47 hours and maxillae in 7.53 hours. Optimized models were printed in 0.93 and 1.07 hours, respectively. Cropping to regions of interest, rotating the model, and decreasing print resolution significantly reduced print time. The difference (optimized versus high resolution) in distance between the plate and model averaged 0.22 and 0.34 mm for mandibles and maxillae; the air space volume differed by 1.39 and 0.90 mm 3 , respectively. Conclusions: Adjusting size, resolution, and position on the printing platform allows rapid fabrication of 3D models for surgical reconstruction without sacrificing surface quality. These edits reduce printing time, enabling the implementation of 3D-printing workflows for surgical planning in acute craniomaxillofacial trauma settings.
Virtual reality (VR) is emerging as an effective and intuitive surgical planning and 3D visualization tool. Digital surgical planning is the gold standard for planning the placement of implants in maxillofacial prosthetics, but the field lacks a platform exclusively designed to perform the task. Virtual reality planning (VRP) specific for maxillofacial prosthetics offers the clinician improved control of the presurgical planning and the potential to limit the need to adapt other advanced segmentation software. Furthermore, the virtual plan can be directly translated to the patient through custom 3D printed (3DP) surgical guides and visual aids. To the best of our knowledge, this article outlines the development of the world's first virtual reality planning platform and workflow for pre-operatory planning within a VR environment for clinical use specific to facial prosthetics and anaplastology.
Abstract Background Facial aesthetic surgery encompasses a variety of procedures with complication rates that are difficult to estimate due to a lack of published data. Objectives We sought to estimate major complication rates in patients undergoing facial aesthetic procedures and develop a risk assessment tool to stratify patients. Methods We utilized the Tracking Operation and Outcomes for Plastic Surgeons (TOPS) database from 2003-2018. The analytic database included major facial aesthetic procedures. Univariate analysis and a backward stepwise multivariate regression model identified risk factors for major complications. Regression coefficients were utilized to create the score. Performance robustness was measured with area under receiver operating characteristic curves and sensitivity analyses. Results A total of 38,569 patients were identified. The major complication rate was 1.2% (460). The regression model identified risk factors including over 3 concomitant surgeries, BMI ≥25, ASA class ≥2, current or former smoker status, and age ≥45 as the variables fit for risk prediction (n = 13,004; area under curve: 0.68, standard error: 0.013, [0.62-0.67]). Each of the 5 variables counted for 1 point, except over 3 concomitant surgeries counting for 2, giving a score range from 0 to 6. Sensitivity analysis showed the cutoff point of ≥3 to best balance sensitivity and specificity, 58% and 66%, respectively. At this cutoff, 65% of cases were correctly classified as having a major complication. Conclusions We developed an acceptable risk prediction score with a cutoff value of ≥3 associated with correctly classifying approximately 65% of those at risk for major morbidity when undergoing face and neck aesthetic surgery. Level of Evidence: 3
Introduction: Paul Tessier once famously quipped that orbital hypertelorism correction was no more than an extended rhinoplasty, i.e., a normal nose could not be obtained unless the orbital cavities were in normal position. Operative options for surgical correction of orbital hypertelorism include box osteotomy and facial bipartition. Correction of nasal deformities must also be undertaken in order to create an acceptable aesthetic result; however, this is a difficult procedure. This study evaluates patient characteristics and post-operative outcomes in patients undergoing surgical correction of orbital hypertelorism and provides conclusions on the surgical management of hypertelorism on the basis of the senior author’s 44-year experience with orbital hypertelorism. Methods: All patients (n = 83) who underwent surgical correction of orbital hypertelorism between January 1, 1975 and January 1, 2019 were identified. A retrospective chart review was conducted by three independent reviewers to determine eligibility. Demographic information collected included age at time of surgery, gender, time to last follow up visit and procedure performed. Outcome measures included postoperative complications and follow-up operations. Results: 83 patients were identified to have undergone surgical correction of orbital hypertelorism. 36% of patients underwent follow-up procedures with the senior author. No complications such as CSF leaks or wound infections occurred. In addition to quantitative results of retrospective data analysis, examination of Dr. Tessier’s cases and the senior author’s experience shows that in cases where nasal reconstruction is done concomitantly with hypertelorism correction, a Gillies/Converse type scalping flap is required. Conclusion: The underlying cause of hypertelorism is heterogenous. It is a symptom, not a diagnosis. On the basis of a 44-year experience with orbital hypertelorism, the following conclusions can be drawn: 1. Do not operate too early. 5 or 6 should be the minimum age because good results earlier than that have not been shown; 2. Parents should be told that repeat operations on the nose should be expected; 3. The paramedian forehead flap can be used for secondary rhinopoeses, but is not to be used if there is a fresh craniotomy beneath; 4. If a coronal incision is to be made by the neurosurgeons (as for example for closure of an encephalocoele), the plastic surgeon should be present to ensure that the incision will not burn the bridges for subsequent nasal reconstruction; 5. Moving the orbits is not difficult; getting a normal nose is; 6. One common characteristic in hypertelorism patients is a short nose which needs to be lengthened.
Beyond the surgeon's feedback on bone behavior in the operating room, there is a paucity of data present in the literature on the mechanical properties of pediatric calvarial bone. The present study tested the calvarial bone of four species (Adult Humans, Dog, Pig, and Monkey) to find the mechanical properties. Three types of tests were performed; flexural, compression, and torsion to mimic how bone is handled during the surgery and the results were further compared with the existing published data for human pediatric calvarium. Test results indicated a significant difference between the modulus (p = 0.006 for flexural, 0.0002 for compression, and 0.0075 for shear) and strength (p = 0.0005 for flexural, 0.0051 for compression, and p < 0.0001 for shear) amongst the tested groups. Compared with published data, the flexural properties of the 12-day-old pig were found to be closest to that of an 11-month-old human infant (E = 0.783 GPa). In contrast, the adult human was found to have a flexural modulus 3.9 times that of the pig, and specimen thickness of adult humans had a strong positive correlation (r = 0.77, p = 0.0237) with its flexural modulus, strengthening the disparity between infant and adult human skull bone material properties. Based on these results, neonatal piglet calvarium was selected as a model for 1-year-old human infants commonly presented for total cranial vault reconstruction. These results will help to inform the development and use of new technologies and techniques for bone graft manipulation in the laboratory and the operating room.
Beyond the surgeon's feedback on bone behavior in the operating room, there is a paucity of data present in the literature on the mechanical properties of pediatric calvarial bone. The present study tested the calvarial bone of four species (Adult Humans, Canine, Porcine, and Macaque) using ASTM standards to find the mechanical properties. Three types of tests were performed; flexural, compression, and torsion to mimic how bone is handled during the surgery and the results were further compared with the existing published data for human pediatric calvarium. Test results indicated a significant difference between the modulus (p=0.006 for flexural, 0.0002 for compression, and 0.0075 for shear) and strength (p= 0.0005 for flexural, 0.0051 for compression, and p<0.0001 for shear) amongst the tested groups. Compared with published data, the flexural properties of the 12-day-old pig were found to be closest to that of an 11-month-old human infant (E=783.8 MPa). In contrast, the adult human was found to have a flexural modulus 3.9 times that of the porcine, and specimen thickness of adult humans had a strong positive correlation (r=0.77, p=0.0237) with its flexural modulus, strengthening the disparity between infant and adult human skull bone material properties. Based on the results, piglet calvarium was selected as a model for 1-year-old human infants commonly presented for total cranial vault reconstruction. These results will help to inform the development and use of new technologies and techniques for bone graft manipulation in the laboratory and the operating room.
Abstract Background Collagen and human amniotic membrane (hAM) are Food and Drug Administration (FDA)-approved biomaterials that can be used as nerve wraps or conduits for repair of peripheral nerve injuries. Both biomaterials have been shown to reduce scarring and fibrosis of injured peripheral nerves. However, comparative advantages and disadvantages have not been definitively shown in the literature. The purpose of this systematic review is to comprehensively evaluate the literature regarding the roles of hAM and collagen nerve wraps and conduits on peripheral nerve regeneration in preclinical models. Methods The MEDLINE database was queried using the PubMed search engine on July 7, 2019, with the following search strategy: (“amniotic membrane” OR “amnion”) OR (“collagen conduit” OR “nerve wrap”)] AND “nerve.” All resulting articles were screened by two independent reviewers. Nerve type, lesion type/injury model, repair type, treatment, and outcomes were assessed. Results Two hundred and fifty-eight articles were identified, and 44 studies remained after application of inclusion and exclusion criteria. Seventeen studies utilized hAM, whereas 27 studies utilized collagen wraps or conduits. Twenty-three (85%) of the collagen studies utilized conduits, and four (15%) utilized wraps. Six (35%) of the hAM studies utilized conduits and 11 (65%) utilized wraps. Two (9%) collagen studies involving a conduit and one (25%) involving a wrap demonstrated at least one significant improvement in outcomes compared with a control. While none of the hAM conduit studies showed significant improvements, eight (73%) of the studies investigating hAM wraps showed at least one significant improvement in outcomes. Conclusion The majority of studies reported positive outcomes, indicating that collagen and hAM nerve wraps and conduits both have the potential to enhance peripheral nerve regeneration. However, relatively few studies reported significant findings, except for studies evaluating hAM wraps. Preclinical models may help guide clinical practice regarding applications of these biomaterials in peripheral nerve repair.
