Symmetric Contour Research Articles

Customized Cranioplasty Implants Using Three-Dimensional Printers and Polymethyl-Methacrylate Casting

ObjectiveThe prefabrication of customized cranioplastic implants has been introduced to overcome the difficulties of intra-operative implant molding. The authors present a new technique, which consists of the prefabrication of implant molds using three-dimensional (3D) printers and polymethyl-methacrylate (PMMA) casting.MethodsA total of 16 patients with large skull defects (>100 cm2) underwent cranioplasty between November 2009 and April 2011. For unilateral cranial defects, 3D images of the skull were obtained from preoperative axial 1-mm spiral computed tomography (CT) scans. The image of the implant was generated by a digital subtraction mirror-imaging process using the normal side of the cranium as a model. For bilateral cranial defects, precraniectomy routine spiral CT scan data were merged with postcraniectomy 3D CT images following a smoothing process. Prefabrication of the mold was performed by the 3D printer. Intraoperatively, the PMMA implant was created with the prefabricated mold, and fit into the cranial defect.ResultsThe median operation time was 184.36±26.07 minutes. Postoperative CT scans showed excellent restoration of the symmetrical contours and curvature of the cranium in all cases. The median follow-up period was 23 months (range, 14-28 months). Postoperative infection was developed in one case (6.2%) who had an open wound defect previously.ConclusionCustomized cranioplasty PMMA implants using 3D printer may be a useful technique for the reconstruction of various cranial defects.

Aesthetic Restoration of Fronto-orbital Deformity with Prefabricated Implant Utilizing Modeling Clay and Rapid-prototyping Technology

Skeletal deformity in the fronto-orbital region resulting from various problems can have significant aesthetic concerns. Restoring an aesthetically acceptable appearance relies most importantly on the restoration of a precise skeletal contour. Current surgical options for depression deformities or partial-thickness defects range from extensive corrective osteotomies to less complicated methods of onlay grafting with autogenous or alloplastic materials. Both methods have difficulties in providing a symmetric and smooth contour for predictable and reliable cosmetic results. Alloplastic implants provide another effective alternative and the success of the skeletal contouring correlates directly with the accuracy of the implant sculpture. Prefabricated methylmethacrylate implants, with the aid of modeling clay, computer imaging, and modern rapid-prototyping technologies, fits the depression deformity well and balances the skeletal contour. It provides plastic surgeons greater precision in customizing the implant, which ensures better predictability and reliability of cosmetic outcomes.

Management of morderate-to-severe Marcus-Gunn syndrome by anastomosis of levator and frontal muscles.

To study the effect of clinical management of moderate-to-severe Marcus-Gunn syndrome (MGS) by anastomosis of levator and frontal muscles. The medical records of 13 patients with moderate-to-severe MGS who underwent surgeries in our institute between 2000 and 2007 were reviewed retrospectively. They underwent unilateral anastomosis of levator and frontal muscles under local anesthesia. Postoperative follow-up periods ranged from 6 to 36 months, with an average of 12 months. All eyelids (100%) showed complete resolution of jaw-winking, ten eyelids (76.9%) had good correction of ptosis, with equal plapebral apertures and symmetrical contours, three (23.1%) showed residual mild ptosis (<2mm). For moderate-to-severe MGS, unilateral anastomosis of levator and frontal muscles provides satisfied correction of jaw-winking and ptosis.

Geometric morphometric analysis of the early Pleistocene hominin teeth from Jianshi, Hubei Province, China

Although the early Pleistocene hominin fossils found in East Asia continent are widely recognized as the earliest hominins migrated from Africa, debates remain on the morphology and taxonomy of these fossils. In this study, dental crown shape of the three early Pleistocene hominin teeth (P3, M1, and M1) found in Jianshi, Hubei Province of China was analyzed by means of geometric morphometrics. The comparative samples of fossil hominins from Africa, Asia, and Europe as well as those of modern humans (N=257) were used. The results indicate that the contour, asymmetry, and cusp patterns of these three types of teeth differ obviously between the fossil hominins and modern humans. The crown shape of P3 in most fossil hominins including Australopithecus, African early Homo, and Asian Pleistocene hominins are asymmetric with their crown occlusal contours long and curving elliptic-shaped. The occlusal contour of the fossil hominin M1 is symmetric and rectangle-shaped with no marked cusp protrusion. The crown shape of fossil M1 is characterized by asymmetric contour with slightly projected metaconid and hypoconid. On the contrary, in modern Chinese and some European late Pleistocene hominins, the crowns of P3s show symmetric contours with buccal side wider than lingual side; the crown shape of M1 is asymmetric with lingual cusp distal-placed, especially for hypoconid; the M1 has symmetric and round crown contour. Our study reveals that Australopithecus has wide variations in its crown shape, whereas these dental morphospaces of Asian hominins are closely placed. The crown contour, symmetry, and cusp patterns of these three teeth of Jianshi hominin resemble those of Asian early and middle Pleistocene hominins. No marked difference in dental crown shape is shown between the Jianshi hominin and other Chinese Homo erectus, and there is also no evidence in support of the Jianshi hominin’s closeness to Australopithecus and African early Homo members.

Parotidotomy approach for a midcheek mass: A new surgical strategy

To report the feasibility and the results of a new surgical strategy for midcheek masses we called the parotidotomy approach. Retrospective consecutive case series. Characteristics, surgical outcome, and cosmetic result of cases managed using the parotidotomy approach were collected by retrospectively reviewing medical records. The standard superficial parotidectomy approach was modified to dissect facial nerve branches selectively to obtain a symmetric facial contour. The parotid gland was fully bisected along the course of the zygomatic and buccal branches of the facial nerve to provide access to the midcheek mass. The bisected parotid gland was repositioned after mass excision. Seven patients (3 males and 4 females) were included in this study. The parotidotomy approach was accomplished in two cases with a malignant tumor (one acinic cell carcinoma, one low-grade mucoepidermoid carcinoma), four with a benign tumor (two pleomorphic adenoma, one basal cell adenoma, one facial nerve schwannoma), and in one case with a chronic inflammatory lesion (chronic sialadenitis). In no case was facial nerve paralysis or Frey's syndrome noticed after this approach. For the two malignant tumors, there was no evidence of recurrence or metastasis at 2-year and 2.5-year follow-ups. Six of the seven patients were fully satisfied with the cosmetic results of surgery. The remaining patient had a mild sunken deformity of the midcheek where the mass had been located. To manage midcheek masses we modified the standard parotidectomy approach. This new surgical strategy, which we named the parotidotomy approach, provides surgically safe and cosmetically excellent results for midcheek masses.

Anterolateral thigh adipofascial flap for the restoration of facial contour deformities

From January 2000 to May 2008, 50 patients with facial contour deformities underwent soft tissue augmentation with 51 anterolateral thigh (ALT) adipofascial flaps. Fifty flaps survived with no complications; partial fat necrosis occurred in one flap. Mean follow-up was 16 months. Flaps ranged from 10 x 6 cm to 20 x 12 cm. Perforators were found in 50 flaps, 43 musculocutaneous perforators (84.3%) and 7 septocutaneous perforators (13.7%), with a mean of 2.5 perforators per flap. In one flap (2.0%), no perforator was found. In this case, we used an anteromedial thigh adipofascial flap using the medial branch of the descending branch of lateral circumflex femoral artery as the vascular pedicle. Relatively symmetric facial contour was achieved in 20 cases. In 30 cases, adjunctive procedures including flap debulking, fat injection, and resuspension were necessary, and 23 patients achieved satisfactory outcomes. We conclude that the ALT adipofascial flap can be successfully elevated and transplanted for the correction of soft tissue facial defects. This flap can provide tissue to fill large defects, and posses the qualities of pliability, an excellent blood supply, ease of suspension and fixation, and minimal morbidity at the donor site.

Polarization and spectral characteristics of anisotropic ring laser cavities with nonideal mirrors

A mathematical model for calculating the polarization and spectral characteristics of eigenmodes of nonplanar ring optical cavities with allowance for the phase anisotropy of oblique-incidence mirrors is described. The results of the numerical modeling and experimental measurements of the characteristics of laser mirrors and mode spectra of practically important four-mirror cavities with a nonplanar symmetric axial contour are compared. It is shown that the proposed mathematical model can be applied to optimal selection of lasers for laser cavities with allowance for their real parameters.

Correction of hemifacial microsomia with the help of mirror imaging and a rapid prototyping technique: case report

A 23-year-old man presented with an 8-year history of unilateral hemifacial microsomia. A three-dimensional model of the maxillofacial bones was generated after acquisition of helical computed tomographic data. A customised implant model was designed by projecting a mirror image of the healthy mandible on to the three-dimensional model. A resin model of the implant was then made using a rapid prototyping machine. A polymeric biomaterial was sculpted according to the model and implanted into the affected side of the mandible to restore his facial symmetry. The hemifacial microsomia was corrected and a symmetrical facial contour obtained. No complications developed during the 6-year follow-up.

The Use of Implants in Facial Augmentation for Hemifacial Atrophy

The Use of Implants in Facial Augmentation for Hemifacial Atrophy

Gland-preserving surgery for pleomorphic adenoma in the submandibular gland

Removal of tumours arising in the submandibular gland (SMG) usually involves excision of the entire gland. This prospective study evaluated the efficacy of gland-preserving surgery in patients with benign SMG tumours. Twenty consecutive patients with pleomorphic adenomas in the SMG underwent local excision of tumours with limited tumour-free margins and preservation of the remnant glandular tissues. All patients had salivary scintigraphy before and 6 months after surgery, with ultrasonography 2 years after operation. Complications, operating time, salivary function and rates of tumour recurrence were evaluated. The mean operating time was 28 min, and no patient had neurological complications. After surgery, the function of the affected gland was equal to that of the unaffected gland. All patients had symmetrical facial contours without defects in the operated submandibular triangle. None of the patients had evidence of tumour recurrence on ultrasonographic examination and regular clinical examination at a median of 36 months after surgery. Gland-preserving surgery in patients with benign SMG tumours preserves salivation, and reduces surgical morbidity and operating time, with good cosmesis but without compromising local control.

Function‐preserving parotid surgery for benign tumors involving the deep parotid lobe

Parotid deep lobe tumors have usually been removed by total parotidectomy, which has functional and aesthetic side effects. Limited partial parotidectomy may result in fewer side effects. We evaluated functional outcomes in 19 patients undergoing limited partial parotidectomy for benign tumors, 11 with deep lobe tumors and 8 with tumors involving both superficial and deep lobes, who underwent partial parotidectomy with preservation of normal glandular parenchyma and limited dissection of the facial nerve. Complications and salivary and cosmetic functions were evaluated at 6 and 12 months after surgery. Median operation time was 1.5 hr. Five patients experienced temporary facial weakness, and 1 developed Frey's syndrome. All patients experienced full recovery of facial nerve function within 6 months. Mean stimulated parotid salivary flow on the operated side was 74% of the preoperative level. All patients had symmetrical facial contours without sunken defects. No patient had tumor recurrence after a median follow-up of 40 months. Limited resection of benign tumors involving the parotid deep lobe may result in improved functional outcomes, including preserved salivary flow and beneficial cosmetic aspects, without compromising local tumor control.

Immediate breast reconstruction with latissimus dorsi musculocutaneous flap: A suitable option for chinese women after mastectomy

ObjectiveTo discuss the suitable immediate breast reconstruction modalities for Chinese patients by comparing the pedicled transverse rectus abdominis myocytaneous flap (TRAM) reconstruction with latissimus dorsi myocytaneous flap (LTD) reconstruction plus implants or not after mastectomy due to breast cancer.MethodsFrom Jan. 2000 to Jul. 2005, 74 staged 0-II patients (mean age 39) were performed immediate breast reconstruction with autologous tissue either using LTD flaps or pedicled TRAM flaps with supplemental implants when necessary after mastectomy due to breast cancer and the charts were reviewed.ResultsThe age, marriage and menses status did not affect the selection of modalities and the need of implants. In 74 patients, 62 cases (83.8%) were performed LTD reconstruction with 13 implants and 12 cases received TRAM with 1 implant. The difference in need of implants or not between the two modalities had no statistical significance (P=0.442, Fisher’ exact test). Aesthetic results judged as good or fair were in 88% patients and the cosmetic effects between LTD and TRAM groups or implant and non-implant groups had no differences. All reconstructions were successful, with 4.1% cumulative locoregional recurrence and 100% overall survival by following up to 66 months (median 9 months). The DFS and RFS between the two modalities had no significant differences by log rank test.ConclusionImmediate autologous tissue reconstruction makes it possible to regain the natural and symmetric contour of breast without increased local recurrence. The LTD flap reconstruction is a suitable option for most Chinese women as well as the pedicled TRAM flap.

THINNING CHARACTER USING MODULUS MINIMA OF WAVELET TRANSFORM

An essential step in character recognition is to extract the skeleton characteristics of the character. In this paper, an efficient algorithm is proposed to extract visually satisfactory skeleton from printed and handwritten characters, which overcomes fundamental shortcomings of our previous skeletonization technique based on the maximum modulus symmetry of wavelet transform (WT). The proposed method is motivated from some desirable properties of the WT with constructed wavelet functions: namely, the local modulus minima of the WT are scale-independent at different level scales and are located at the medial axis of the symmetrical contours of character stroke. Thus the modulus minima of the WT are computed as the intrinsic skeletons of character strokes. To achieve faster implementation, a multiscale processing technique is employed. Thus major structures of the skeleton are extracted using the coarse scale, while fine structures are extracted using the fine scale. We have tested the algorithm on handwritten and printed character images. Experimental results show that the proposed algorithm is applicable to not only binary image but also gray-level image where it can be impractical to use other skeletonization techniques, such as thinning and distance transforms. Further, it can effectively remove unwanted artifacts and branches from the extracted skeletons at the intersections and junctions of character strokes and is robust against noises while most existing methods perform poorly.

Secondary repair of cleft lip nose deformity using subcutaneous pedicle flaps from the unaffected side

We used three types of subcutaneous pedicle flaps harvested from the unaffected side of the nostril to repair postoperative nose deformity caused by primary cleft lip surgery. By moving the subcutaneous pedicle flap from a nearby tissue-rich area, it was possible to achieve a favourable symmetrical nasal contour for the narrowing of the nostril cavity, depression of the nostril floor and the columella deviation of the affected side. The method, we used here is technically simple. We believe this procedure is a method of choice for repairing small deformities of the nose occurring after primary or secondary cleft lip surgery.

COMPLEX PENILE JOINING IN A CASE OF WIDE PENILE DUPLICATION

A 15-month-old boy with multiple congenital malformations was referred for surgical correction. Physical examination revealed 2 complete separated penises 10 cm apart. Both penises had severe penoscrotal hypospadias with marked chordee. Separated hemiscrotums with 1 testicle each and a huge ventral hernia were also noted (fig. 1, A). Both urethras were easily catheterized, and retrograde cystograms showed 2 separate bladders and wide pubic diastasis. Grade III vesicoureteral reflux was noted on the left side (fig. 1, B). Sonography confirmed 2 corpora cavernosa for each penis. Karyotype was normal. Our goal was to join both penises in a normal midline position. The neurovascular bundles were lifted and the urethral plates were removed. The urethras were extensively mobilized including the proximal bulb. Suspensory ligaments were divided to lengthen the penises. Further dissection disclosed paired corpora cavernosa on both sides. Chordees were repaired by tunica albuginea plication. Symphyseal diastasis was approximated with bilateral innominate osteotomies. A poorly developed left glans with neurovascular bundle was dissected from the corpora and removed. The right glans cap was undermined to enable coverage of the distal left corpora as well. All 4 corpora cavernosa converged in the midline. Both urethras were approximated side by side to be joined distally during the second stage. Hemiscrotums were joined to form a singular scrotal sac. Penile body skin was reconstructed using vascularized sliding skin flaps. The ventral hernia was repaired during the second stage. Followup 1 year later demonstrated good penile size with symmetrical contours (fig. 2). Parents confirmed continence and good erectile function.

Z-plasty and Augmentation Mammaplasty for Correction of Severe Breast Deformity Caused by Abscess: Report of A Case

Breast deformity imposes great cosmetic and psychological problems on the inflicted patients. The treatment goal is to achieve an aesthetic and symmetric breast contour, especially when the other side is unaffected. Breast abscess is not uncommon, but rarely causes severe deformity. We present a 33-year-old woman treated with zplasty and augmentation mammaplasty. The patient had undergone received surgical drainage twice for her left breast abscess two years before, which led to breast volume deficiency, contour deformity and malposition of the nipple-areola complex. A 200 cc saline-filled prosthesis was implanted in a subpectoral pocket to build up a symmetric breast mound and z-plasty was performed to correct the trapdoor deformity and the malposition of the nipple-areola complex. The surgical result was satisfactory. To the best of our knowledge, this is the first report of severe breast deformity secondary to previous breast abscess that required reconstructive surgery.

Characterization of hydrogen defects forming during chemical charging in the aluminum

The behavior of hydrogen and deuterium in high-purity aluminum introduced by high-fugacity chemical techniques has been studied. The aims were to establish: (a) the presence of the hydrogen–vacancies clusters and bubbles formations, (b) their size and size distributions, (c) the symmetry of the clusters and the dependence of these parameters on the hydrogen charging conditions and on subsequent annealing procedures and (d) the kinetics of hydrogen release from these clusters and the structure of the remaining defects produced when the hydrogen is removed. The study was combined with a parallel series of experiments, which utilized secondary ion mass spectrometry (SIMS), X-ray techniques (Laue, small-angle X-ray scattering (SAXS), diffractometer measurements), transmission electron microscopy (TEM) and scanning electron microscope (SEM). The experiments revealed the existence of a large size distribution of hydrogen voids and bubbles on the surface and under the surface obtained during electrochemical and chemical charging. The depth of these defects was controlled by electrochemical and chemical charging conditions and depended on the charging time. Hydrogen nearly entered the aluminum lattice interstitially. A TEM technique revealed the existence of surface bubble from the interactions between the aluminum hydroxide with hydrogen and formed a hydrogen–vacancy complex at the surface, which diffused into the volume and then clustered to form H 2 interior bubbles. A large size (some micrometers in the diameter) to very small sizes (nanometers in the diameter) in the distribution and variety in the density of the surface bubbles was obtained. Between the densely packed surface bubbles, formation of the dense dislocations could be seen. Internal bubble with symmetrical bend contours of the height and dense distributions of dislocations was observed.

Management of Marcus Gunn jaw winking synkinesis.

To report the outcomes of a management protocol for Marcus Gunn jaw winking synkinesis. The records of 31 patients (16 female, 15 male) presenting to a tertiary referral center with Marcus Gunn jaw winking synkinesis between 1993 and 2003 were retrospectively analyzed. Generally, patients with mild wink and a small degree of ptosis underwent unilateral upper eyelid retractor surgery. Patients with a moderate or marked wink and ptosis underwent bilateral levator weakening procedures and brow suspension. Patients were assessed and treated for amblyopia and vertical strabismus before ptosis surgery. Mean patient age was 11.23 years (median, 8 years; range, 10 weeks to 31 years). Ipsilateral hypotropia was noted in 8 patients (26%), with a median visual acuity in the ptotic eye of 20/30 (range, 20/20 to 20/40), compared with 20/20 in those without hypotropia. Patients who underwent unilateral surgery had good correction of ptosis, with equal palpebral apertures and symmetrical contour but had a detectable wink on formal testing. Patients who underwent bilateral surgery had equal palpebral apertures and symmetrical contour, with wink elimination. Mean follow-up was 31 months (all patients) and mean postoperative follow-up was 22 months. Patients with Marcus Gunn jaw winking synkinesis can present at a wide age range. There may be an associated vertical muscle imbalance, which should be managed before ptosis surgery to avoid ptosis undercorrection and allow amblyopia management. Nearly all patients use the synkinesis to reduce the underlying true ptosis to a less noticeable "habitual" ptosis or to maintain binocularity. Surgical approach will differ, depending on whether the synkinesis, ptosis, or both are the main concern. Satisfactory results with a low complication rate can be achieved with the use of this management protocol.

In situ transmission electron microscopy study of the crystallization of Ge2Sb2Te5

Crystallization of amorphous Ge2Sb2Te5 films (10, 40, and 70 nm thick) was studied by in situ heating in a transmission electron microscope (TEM). Electron irradiation-induced crystallization is possible at room temperature using a 400 kV electron beam where the reciprocal of the incubation time for crystallization scales linearly with the current density during electron irradiation. Without electron-beam exposure, crystallization starts at 130 °C. Using a 200 kV beam, crystallization also occurred in the temperature interval between 70 and 130 °C. In principle, electron irradiation always affects the crystallization kinetics, strongly promoting nucleation and probably not hampering growth. At 130 °C without electron-beam exposure, 400 nm diameter colonies of 10–20 nm grains develop in the 40 and 70 nm thick films showing clear symmetric bending contour contrast. These spherulites prefer to have in their center the 〈111〉 zone axis of the Fm3̄m structure perpendicular to the surface of the film and show a typical tilt variation of ±10°. At 340 °C, the transition from the metastable to the stable trigonal (P3̄m1) crystal structure takes place. Fast and excessive grain growth occurs with the [0001] axis perpendicular to the film surface of the film. Also shown is that oxidation of the Ge2Sb2Te5 film strongly influences its crystallization; its critical temperature decreases from 130 to 35 °C.

Unsteady Force on Slender Aircraft with Free Vortices in Inviscid Flow

Expressions are derived for the force on circular and wing-body contours induced by a vortex pair in a twodimensional uniform unsteady inviscid e ow, such as arise in the slender-body approximation of an aircraft. Zeroforce curves fortheclassical vortex pairbehind a circularcylinder in oncoming e ow arefound, and it isshown that the direction of the force can be upwind as well as downwind. A convenient expression for the force on a contour in a symmetric e owe eld is obtained by conformal mapping, involving only the e rst- and second-order derivatives of the required transformation-function. A result of practical interest for free vortices intended to enhance the lift force of an aircraft is that the force on the crosse ow contour induced by vortices with a certain strength generally decreases when enlarging the width of the contour perpendicular to the direction of that force. So span reduction increases the lift generated by vortices above the wings. The position of the vortices in relation to the contour is critical, however, as there are areas that are shown, where the lift caused by the vortices is negative. The force caused by the symmetric vortex pair on the symmetric contour is independent of the speed of the oncoming e ow; the pressure distribution on the contour, however, does vary with changing speed of the oncoming e ow.