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Biomedical subjects

James J Xia

Publications and source records attributed to James J Xia.

18 recordsLinked to original sources
PubMed2007

Presurgical nasoalveolar molding therapy for the treatment of unilateral cleft lip and palate: a preliminary study.

OBJECTIVE: To evaluate the outcome of presurgical nasoalveolar molding (PNAM) therapy in the treatment of patients with nonsyndromic unilateral cleft and palate (UCLP). DESIGN: A prospective study with blinded measurements. PATIENTS: Twelve patients with UCLP treated from 1997 to 2003. INTERVENTIONS: The starting age for PNAM therapy was 26 days and the average length of the therapy was 110 days. MAIN OUTCOME MEASURES: Measurements of intraoral and extraoral casts were made, and statistical analyses were used to compare the differences between pre- and posttherapy measurements. RESULTS: After PNAM therapy, there was a statistically significant decrease in both intersegment alveolar cleft distance and columellar deviation (p < .05). There was also a statistically significant increase in cleft nostril height, maxillary width, and columellar width (p < .05). Moreover, although there was no statistically significant reduction of the affected nostril width, it demonstrated on average 1.7-mm reduction after PNAM therapy. The length of the time the patient utilized the appliance and postmolding nostril height were found to have a statistically significant positive correlation (p < .05). CONCLUSIONS: PNAM therapy decreases intersegment alveolar cleft distance while permitting an increase in posterior maxillary arch width. It also increases nasal symmetry by decreasing columellar deviation, increasing nostril height on the affected side, maintaining bialar width of nose, increasing columellar width, and creating more symmetrical nostril heights and widths. The improvement of the height of the cleft nostril was correlated with the time the appliance was applied.

Alveolar Process↗
PubMed2006

The accuracy of cephalometric tracing superimposition.

PURPOSE: The purpose of this study was to compare the accuracy of 4 methods for cephalometric tracing superimposition. They are the FH@Porion method, S-N@Sella method, least-squared averaged 5 landmarks (LS-5) method, and manual geometric method. MATERIALS AND METHODS: Eight lateral cephalometric radiographs were used. Cephalometric tracing was performed by 2 examiners. One had extensive experience in landmark digitization while the other had minimal experience. The radiographs were scanned and the reference landmarks ANS, Point A, Point B, and Pogonion were digitized, creating 8 master tracings. Then 6 digital copies of each master tracing were made, 3 for each examiner. Subsequently, the examiners were asked to digitize and trace predetermined cranial base landmarks and structures. Tracings occurred at 1-month intervals. As a result, 3 separate tracings of each set were obtained from each examiner. The tracings of each set were superimposed using 4 different methods in the CASSOS software (SoftEnable Technology Ltd, Hong Kong SAR, China). For each method of superimposition, the coordinates of ANS, Point A, Point B, and Pogonion were recorded. Their means and variances were calculated. The variance represents the variability of the superimposition method. A general linear model for repeated measures was computed to test whether there were statistically significant differences among the 4 superimposition methods, 2 examiners, 4 reference landmarks, and 2 directions. Because the distribution of the variances was skewed, they were transformed to log variances. Finally, the errors of the superimposition in millimeters for each given examiner, superimposition method, reference landmark, and direction (X, Y) were calculated. RESULTS: There was a statistically significant difference in measurement variability among the 4 superimposition methods (P < .001). For both examiners, the variability of the different superimposition methods from the highest to the lowest was: Frankfort Plane registered at Porion method, Sella-Nasion registered at Sella method, least-square averaged 5 landmarks method, and the manual geometric method. In addition, there was a statistically significant difference in the magnitude of superimposition errors between the 2 examiners (P < .001). The experienced examiner was consistently more precise than the inexperienced examiner across all methods. Moreover, there was a statistically significant difference among 4 reference landmarks (P < .001). For both examiners, the recorded variability of each given reference landmark from the lowest to the highest was: ANS, Point A, Point B, and Pogonion. Furthermore, the variability differences between horizontal and vertical directions did not reach a conventional level of significance (P = .123). Finally, the recorded errors in millimeters for each superimposition method were summarized. A smaller error in millimeters represented a higher accuracy in superimposition. The error of using manual geometric or LS-5 methods for both examiners was less than 0.50 mm, while the error of using the other 2 methods was up to 0.99 mm for the experienced examiner and 2.88 mm for the inexperienced examiner. CONCLUSION: The error of both manual and LS-5 methods was within 0.5 mm. The LS-5 method had its advantage because it could be automated by the computer.

Algorithms↗
PubMed2006

Image-guided minimally invasive surgical access to the temporomandibular joint: A preliminary report.

PURPOSE: To establish a protocol for image-guided minimally invasive surgical access to the temporomandibular joint (TMJ). MATERIALS AND METHODS: This study involved 2 patients with TMJ pain and mandibular motion dysfunction. Axial magnetic resonance imaging (MRI) of the TMJ was obtained and loaded into an intra-operative navigation system to guide joint space injection. With a navigated syringe, 1 mL synvisc Hylan G-F 20 was directly injected into the superior and inferior joint spaces under navigation guidance. RESULTS: With the assistance of an intraoperative navigational system, the TMJ MRI images were visualized in 3 dimensions and enabled guiding a needle into the superior and inferior joint spaces for therapeutic injection. The treatment outcome for both patients was satisfactory with improvement in pain score and mandibular motion. CONCLUSIONS: A protocol for image-guided minimally invasive surgical access to the TMJ was established. This could provide the technical basis for evaluation of accurate joint space intervention as a form of treatment of appropriate TMJ disorders.

Adult↗
PubMed2006

Cost-effectiveness analysis for computer-aided surgical simulation in complex cranio-maxillofacial surgery.

PURPOSE: The purpose of this study is to assess the costs and benefits of computer-aided surgical simulation (CASS) and to compare it with the current surgical planning methods for complex cranio-maxillofacial (CMF) surgery. MATERIALS AND METHODS: The comparison of methods applies to all CMF surgeries where the patient's condition is severe enough to undergo a computed tomography scan and a stereolithographic model is necessary for the surgical planning process. The costs for each method can be divided into time and other costs. The time was estimated based on the authors' experience as well as on a survey of a small group of 6 experienced CMF surgeons in the United States. The other costs were estimated based on the authors' experience. RESULTS: CASS has lower costs in terms of surgeon time, patient time, and material costs. Specifically, total surgeon hours spent in planning are 5.25 hours compared with 9.75 for current standard methods. Material and scanning costs are Dollars 1,900 for CASS compared with about Dollars 3,510 for standard methods. Patient time for planning is reduced from 4.75 hours to 2.25 hours with CASS. The reduction in both time and other costs remains when the fixed fee costs of CASS are added to the variable costs. Amortized across the 600 patients per year (1,800 for the assumed 3-year life of the training and software), this adds only a few dollars and a fraction of an hour per surgery. Even in the case of a small clinic when the cost is amortized for 6 patients per year (18 patients for the assumed 3-year life of the training and software), the per surgery costs (9.65 hours and Dollars 2,456) will still favor CASS. CONCLUSION: Any great new design should consist of at least 2 of the 3 following features: faster, cheaper, and better outcome. This analysis demonstrates that CASS is faster and less costly than the current standard planning methods for complex CMF surgery. Previous studies have also shown that CASS results in better surgical outcomes. Thus, in all regards, CASS appears to be at least as good as the current methods of surgical planning.

Computer Simulation↗
PubMed2006

Presurgical nasoalveolar molding therapy for the treatment of bilateral cleft lip and palate: A preliminary study.

OBJECTIVE: To evaluate the outcome of presurgical nasoalveolar molding therapy in the treatment of patients with bilateral cleft lip and palate. DESIGN: A prospective study with blinded measurements. SETTING: The Cleft and Craniofacial Clinic at the University of Texas at Houston Medical School, Houston, Texas. PATIENTS: Eight patients with bilateral cleft lip and palate, treated between 2002 and 2004. INTERVENTIONS: The starting age for presurgical nasoalveolar molding therapy was 34.9 days and the average length of the therapy was 212.5 days. MAIN OUTCOME MEASURES: Measurements of intraoral and extraoral casts were performed, and statistical analyses were used to compare the differences between measurements before and after therapy. RESULTS: Intraoral measurements demonstrated that there was a statistically significant reduction of the premaxillary protrusion and deviation. There was also a significant reduction in the width of the larger cleft. Extraoral measurements revealed that there was a significant increase in the bi-alar width and in the columellar length and width. Moreover, there was a significant improvement in columellar deviation. Finally, the nostril heights of both sides were increased. CONCLUSION: The authors have quantitatively shown that presurgical nasoalveolar molding therapy has significant advantages in the treatment of bilateral cleft lip and palate patients. It improves the nasal asymmetry and deficient nasal tip projection associated with bilateral cleft lip and palate. It also forces the protruded premaxillary segment into alignment with the dental alveolar segments, improving the shape of the maxillary arch. As a result, the changes associated with presurgical nasoalveolar molding therapy help decrease the complexity of subsequent surgeries.

Acrylic Resins↗
PubMed2005

A new Le Fort I internal distraction device in the treatment of severe maxillary hypoplasia.

PURPOSE: The purpose of this pilot study was to test a new Le Fort I internal distraction device. PATIENTS AND METHODS: A new internal Le Fort I distraction device designed by 1 of the authors was used in 3 patients with cleft lip and palate and severe maxillary hypoplasia who needed maxillary advancements in excess of 12 mm. Presurgical planning used CASSOS (SoftEnable Technology, Ltd, Hong Kong SAR, China) prediction tracing software and a stereolithographic model to calculate the distraction vector. The distractors were pre-bent and installed on the stereolithographic model and activated to advance the maxilla. Surgery was performed in a conventional manner, and distraction was started after a 7-day latency phase at the rate of 1 mm/day and continued until the presurgical plan was achieved. The distractor was removed after a 3-month consolidation phase. Cephalometric radiographs were taken at the completion of each phase. RESULTS: This new Le Fort I internal distraction device successfully distracted the maxillae as planned in all 3 patients. At the end of the distraction phase, the maxillary advancement was measured at 15.8 mm, 15.8 mm, and 13.5 mm, respectively. In each patient, a clockwise rotation of the maxilla was observed with a tendency to a posterior open bite. Postoperative radiographs also showed that the actual distraction vectors differed from the planned vectors. After the consolidation phase, radiographs showed a relapse of 2.6 mm, 0 mm, and 5.0 mm, respectively. There was no further relapse on 3-month follow-up radiographs. Each case showed radiographic evidence of excellent new bone formation at the osteotomy sites. CONCLUSION: The new Le Fort I internal distraction device produced the necessary advancement in all 3 patients. The study also showed that the actual distraction vector differed from the planned vector. This discrepancy was caused by a clockwise rotation of the maxilla during the distraction. Finally, the study showed a variable relapse rate not previously reported in maxillary distraction.

Adolescent↗
PubMed2005

Radiographic analysis for jaw motion normalization.

PURPOSE: This study incorporated 3 objectives: 1 ) to evaluate the physical location of the center of rotation as determined by a custom mathematical algorithm, 2 ) to identify and compare the geometric center of the condylar head in radiographs with the calculated center of rotation, and 3 ) to determine whether a correlation exists between jaw motion characteristics and the mandibular geometry of the subject. MATERIALS AND METHODS: Lateral cephalometric radiographs of 9 subjects who underwent motion path analysis were obtained. The determined center of rotation of each mandible was calculated through a custom algorithm and recorded on the radiograph. Circular templates were used to determine the geometric center of the condyle for comparisons. Finally, measurements of 4 geometric jaw parameters were made and compared with motion characteristics to investigate whether mandibular geometry can be correlated to motion parameters. RESULTS: All calculated centers of rotation were found to lie in the condylar head of the mandible. The average difference between the calculated center of rotation and geometric center of the condylar head was 2.87 mm (SD, 1.69 mm). In addition, correlations were found linking the length of the mandibular rotational arm to the rotational and translational motions. However, there was no correlation found with the other geometric mandibular parameters. CONCLUSIONS: Analysis of mandibular motion allows for an accurate determination of the center of rotation. Previously identified characteristic motion exists in terms of primary rotation, followed by translation of the mandible with rotation. The magnitude of each phase differs between subjects. This study points to a natural mechanism of mandibular opening as the amount of rotation increased for longer rotational arms and amount of translation increased for shorter ones, serving to lessen the disparity in the opening amounts among individuals.

Adult↗
PubMed2005

Microscopic approach to craniosynostosis.

The purpose of this study is to describe a minimally invasive approach using a microscope and the subsequent helmet therapy. The authors have treated 14 patients with the microscopic technique between May 2001 and November 2003. In this group of patients, there were 3 females and 11 males with an average age of 10.5 weeks and a range of 4 to 28 weeks. The study included 8 patients with sagittal synostosis and 6 patients with other synostoses. In the latter group, there were 3 patients with metopic, one with unicoronal, one with bicoronal, and one with lambdoidal. The approach used limited incisions over the affected sutures. The craniotomy/craniectomy was completed using a 5-mm burr. Postoperative helmet therapy was begun within 2 weeks after surgery. In patients with sagittal synostosis, a mean of 1.5 helmets for a duration of 11.4 weeks was used. In the other groups of patients with craniosynostosis, a mean of 2.3 helmets for a duration of 13.5 weeks was used. A microscopic variation to the "minimally invasive" approach to craniosynostosis is presented. It provides excellent visualization, illumination, and control of the surgical field. When compared with traditional surgery, it results in shorter hospitalization and operative time and decreased blood loss. The authors note that critical to this approach is the postoperative helmet therapy. Early results are encouraging.

Blood Loss, Surgical↗
PubMed2004

A comparative assessment of mandibular condylar position in patients with anterior disc displacement of the temporomandibular joint.

PURPOSE: The purpose of this study was to determine whether the position of the mandibular condyle in patients with anterior disc displacement (ADD) is different from that of a control group with normal joints using a novel method to quantify the irregular shape of the temporomandibular joint (TMJ). MATERIALS AND METHODS: Twenty-six magnetic resonance images of TMJs with ADD were evaluated and compared with 14 normal joints. The position of the condyle was determined by using 2 different methods: 1) measuring the horizontal and vertical normalized distances in millimeters between the geometric centers of the glenoid fossa and the condyle and 2) calculating the anteroposterior joint space ratio. RESULTS: Using the first method, the horizontal distance between the centers of the condyle and the glenoid fossa was 14.0 +/- 11.1 in the ADD group and 5.3 +/- 10.9 in the control group (P <.001). The vertical distance was 64.7 +/- 22.7 in the ADD group and 68.3 +/- 32.9 in the control group (P =.015). The ratio of the horizontal and the vertical condylar displacement in the ADD group was 2.4. Using the second method, the anteroposterior joint space ratios in the ADD group and in the control group were 1.7 +/- 0.5 and 1.2 +/- 0.4, respectively (P =.001). CONCLUSION: This study found that condyles of patients with ADD were situated more posterior and superior in the fossa than those in the control group. Moreover, in the ADD group, the posterior condylar displacement was noted to be 2.4 times greater than the superior condylar displacement.

Adolescent↗
PubMed2004

Biomechanical evaluation of the pins of a mandibular external distractor.

PURPOSE: Our goal was to establish whether the pins of an external distractor were capable of overcoming tissue resistance to distraction. MATERIALS AND METHODS: The study was carried out in 2 parts. The first part of the study determined the bending rigidity of the distractors pins. To accomplish this, the distractor was installed on the mandible of a stereolithographic model using 4 regular 2.0-mm steel pins. An osteotomy was not performed. The distractor was activated using a torque gauge, and the bending rigidity of the pins was recorded. The second part of the study determined the tissue resistance to mandibular distraction using fresh cadavers. Six cadavers were divided into 2 groups to determine tissue resistance to angular and linear distraction, respectively. The devices used to measure tissue resistance were a modified external multiplanar distractor and a torque gauge. RESULTS: In the anteroposterior direction, the tissue resistance to linear distraction clearly exceeded the bending rigidity of the pins for the first 7.5 mm of activation. After this, the opposite was true. In the vertical direction, the tissue resistance clearly exceeded the bending rigidity of the pins for the first 8.0 mm of activation. After this, the opposite was true. For the first 15.0 degrees of angular distraction in the sagittal plane, the tissue resistance was almost identical to the bending rigidity of the pins. After this, the tissue resistance significantly exceeded the bending rigidity of the pins. For the first 7.0 degrees of angular distraction in the transverse plane, the tissue resistance was marginally greater than the bending rigidity of the pins. After this, the bending rigidity of the pins increased significantly. CONCLUSION: The 2.0-mm steel pins used in most external multiplanar distractors are not capable of overcoming the tissue resistance to linear or angular distraction.

Biomechanical Phenomena↗
PubMed2004

Prototype testing for a new bioabsorbable Le Fort III distraction device: a pilot study.

PURPOSE: The goal of the study was to design and test prototypes for a new, internal resorbable Le Fort III distractor in the minipig model. MATERIALS AND METHODS: Le Fort III osteotomies were performed on 3 juvenile minipigs, followed by implantation of the bioabsorbable distractors. After a 5-day latency period, the distraction progressed at a rate of 1 mm/day in 2 equal increments for 12 days. This was followed by a 6-week consolidation phase. Cephalometric radiographs were taken postoperatively, on completion of distraction and after the consolidation phase, to evaluate the amount of distraction that was obtained. Necropsy was performed at the completion of each experiment. RESULTS: The first minipig was sacrificed at the end of the distraction period because of device failure. On necropsy, it was noted that the anterior footplate on either side had failed. The second minipig was sacrificed during the latency period because of severe pneumonia. On necropsy, it was noted that none of the footplates had failed but that the distraction barrels on either side had become dislodged from the anterior bioabsorbable footplates. The third minipig was sacrificed at the end of the distraction period because of device failure. On necropsy, it was noted that the posterior bioabsorbable footplates on either side were fractured across the posterior screw lines. CONCLUSIONS: The bioabsorbable devices evaluated in this study could not withstand the forces generated during distraction osteogenesis in the minipig model. Experience with the prototypes may help in designing internal bioresorbable Le Fort III distraction devices.

Absorbable Implants↗
PubMed2004

Molding helmet therapy in the treatment of brachycephaly and plagiocephaly.

The purpose of this study was to compare the use of molding helmet therapy in the treatment of positional brachycephaly and posterior positional plagiocephaly. Four hundred twenty-eight children with positional brachycephaly or plagiocephaly were included in this study. In this group of patients, 132 (32%) were treated with positioning alone. Of the 292 (68%) patients who were treated with molding therapy, 64 (21.9%) were treated for positional brachycephaly and 248 (78.1%) were treated for posterior positional plagiocephaly. All children were evaluated by a craniofacial surgeon and a pediatric neurosurgeon. Anthropomorphic measurements were used to assess the efficacy of treatment. Measurements were made before initiation of therapy and at 2-month intervals until the completion of therapy. Results showed that statistically significant improvements (P < 0.01) were seen in all patients treated with molding helmet therapy. Overall, the children with posterior plagiocephaly normalized their head shapes; however, the head shapes of the children with positional brachycephaly did not normalize despite statistically significant improvements in their Cephalic Index. It is concluded that molding helmet therapy is an effective treatment of position-induced head shape abnormalities. Helmet therapy is more effective in children with posterior positional plagiocephaly than in children with positional brachycephaly.

Cephalometry↗
PubMed2004

New internal Le Fort I distractor for the treatment of midface hypoplasia.

A new Le Fort I internal distraction device was developed by one of the authors (J. G.) and successfully used on a patient with cleft lip and palate and severe maxillary hypoplasia. The device consisted of an upper plate and a lower plate, which were installed above and below the Le Fort I osteotomy. The upper plate was shaped like a "U," and the lower plate was shaped like an inverted "U." The design of the device was unique in that the distraction screws were placed in the maxillary sinus and orientated parallel to the sagittal plane. Presurgical planning used a stereolithographic (STL) model and the CASSOS software to calculate the distraction vector. The distractors were prebent and installed on the STL model and activated to advance the maxilla 15.5 mm. Surgery was performed in a conventional manner, and distraction was started on the seventh day after surgery. At the completion of distraction, a total of 15.5 mm of distraction was achieved. The distractors were removed 3 months after surgery. Results showed that the patient's severe maxillary hypoplasia was corrected as predicted and there was excellent new bone formation between the edges of the osteotomy.

Adolescent↗
PubMed2004

Nonsynostotic scaphocephaly: the so-called sticky sagittal suture.

OBJECT: Scaphocephaly is a common craniofacial abnormality that results from craniosynostosis of the sagittal suture. The authors have treated a group of infants who presented with nonsynostotic scaphocephaly, or a so-called sticky sagittal suture. The purpose of this study was to describe these patients with nonsynostotic scaphocephaly, the natural history of the disease, and its treatment. METHODS: At the University of Texas-Houston Medical School between 1996 and 2002, nine patients presented with nonsynostotic scaphocephaly. When the abnormality in patients was diagnosed prior to 12 months of age, the majority (seven of eight) were successfully managed by molding helmet therapy. The only child in this group in whom this therapy failed to correct the deformity was noted on repeated computerized tomography scanning to have true sagittal synostosis, which required surgical correction. One child with nonsynostotic scaphocephaly, who presented after 1 year of age, required surgical correction followed by postoperative molding helmet therapy. CONCLUSIONS: Patients with nonsynostotic scaphocephaly appear to have sagittal synostosis. If treated early (at < 12 months of age), head shape in these patients can be normalized by molding helmet therapy. Surgery is reserved for older patients (> 12 months of age) or those with sagittal synostosis.

Cranial Sutures↗
PubMed2003

Three-dimensional surgical planning for maxillary and midface distraction osteogenesis.

Computerized surgical planning protocols for distraction osteogenesis are still in their rudimentary phase. The authors have developed a system to plan distraction osteogenesis in craniofacial and maxillofacial surgery that uses three-dimensional computed tomography scans and computer simulation in a virtual reality environment. This involves the creation of a three-dimensional bone model of the craniofacial skeleton, which incorporates virtual globes. Virtual osteotomies are performed on the bone model and the movements of the bone segments are simulated. The program generates a recipe for the linear and the angular changes necessary to achieve the desired outcome. The purpose of this article is to present this surgical planning process and discuss its use in maxillary and midface distraction.

Child↗
PubMed2002

Molding helmet therapy in the management of sagittal synostosis.

The current surgical treatment of sagittal craniosynostosis often fails to produce a normal cephalic index; however, recent reports of early endoscopic suture release and postoperative helmet therapy promise improved cranial symmetry. The role of helmet therapy is critical in this approach, but there are few reports on the use of helmet therapy after craniosynostosis surgery. The authors present a retrospective review comparing the results of surgery alone versus surgery and postoperative banding in treating children diagnosed with sagittal synostosis. Cephalic index (CI) measurements and the divergence of the CI from the norm (DFN) were used to compare the banded and the non-banded groups. Included in the study were 21 children with sagittal craniosynostosis of whom 6 were treated with surgery alone and 15 were treated with surgery and postoperative banding. Preoperatively, both groups were significantly different from the norm (non-banded, P < 0.05; banded, P < 0.01), while postoperatively they were not significantly different from the norm. Statistically significant changes were present in the CIs of the banded group in the preoperative-follow-up interval (P < 0.01), while no significant changes occurred in the non-banded group during this same interval. Statistically significant changes in the DFN occurred in the preoperative-postoperative and preoperative-follow-up intervals of the banded group; however, these changes were not significant in the non-banded group during the same intervals. Correction toward a normal CI was seen in the banded group throughout the course of treatment, while this trend was not present in the non-banded group. Therefore, molding helmet therapy maintains the operative correction obtained and promotes more normal cranial growth patterns.

Cephalometry↗