Association of the presence of bone bars on radiographs and hip fracture in postmenopausal Caucasian women.

AIM: To determine whether the presence of bone bars (BB) identified on anteroposterior hip radiographs are more prevalent in patients that have had a hip fracture as compared to patients without a fracture. MATERIALS AND METHODS: Ninety-two Caucasian women with a unilateral proximal femur fracture were retrospectively evaluated and randomly selected using radiology database records to comprise the investigational group. Ninety-eight age-matched Caucasian women without hip fracture were selected as a control group. Anteroposterior hip radiographs were evaluated for the presence of BBs by two musculoskeletal radiologists. Chi-square tests were used to assess whether fractures were more prevalent in patients with BB than those without BB. RESULTS: The patient population was comprised Caucasian women with a mean age of 79.8 ± 6.4 years in the control group and 79.9 ± 6.6 years in the investigational group. Regardless of the reader, BB were identified in a significantly higher percentage of women with a fracture (75 versus 39%, p < 0.001 or 53 versus 38%, p = 0.041) as compared to those without a fracture. CONCLUSION: BB are associated with hip fracture. Their presence is a trigger for requesting a dual-energy x-ray absorptiometry (DXA) examination to confirm or refute a diagnosis of low bone mineral density (BMD) and a subsequent increased risk of fracture.

Arming a replicating adenovirus with osteoprotegerin reduces the tumor burden in a murine model of osteolytic bone metastases of breast cancer.

Most patients with advanced breast cancer develop osteolytic bone metastases, which have numerous complications. Because current therapies are not curative, new treatments are needed. Conditionally replicating adenoviruses (CRAds) are anticancer agents designed to infect and lyse tumor cells. However, in spite of their promise as selective cancer therapeutics, replicating adenoviruses have shown limited efficacy in the clinical setting. We hypothesized that a CRAd armed with osteoprotegerin (OPG) would eradicate bone metastases of breast cancer both directly, by oncolysis, and indirectly, by inhibiting osteoclastic bone resorption, and thus reducing the tumor burden. We constructed an armed CRAd (Ad5-Δ24-sOPG-Fc-RGD) by replacing viral E3B genes with a fusion of the ligand-binding domains of OPG and the Fc portion of human IgG1. Conditional replication was conferred by a 24-base pair deletion within E1A (Δ24), which prevents the binding of E1A to the retinoblastoma tumor suppressor/cell cycle regulator protein and limits replication in normal cells. Enhanced infection of cells expressing low levels of the primary Ad5 receptor was conferred by incorporating an arginine-glycine-aspartic acid (RGD) peptide sequence into the fiber knob to mediate binding to α(v) integrins. After characterization of the armed CRAd, we demonstrated that infection of breast cancer cells by Ad5-Δ24-sOPG-Fc-RGD both killed the infected cells by oncolysis and inhibited the formation of osteoclasts in an in vitro co-culture model. In a murine model of osteolytic bone metastases of breast cancer, the CRAd armed with shortened OPG (sOPG)-Fc reduced tumor burden in the bone and inhibited osteoclast formation more effectively than an unarmed CRAd.

The importance of incisor positioning in the esthetic smile: the smile arc.

The smile arc is defined as the relationship of the curvature of the incisal edges of the maxillary incisors and canines to the curvature of the lower lip in the posed smile. The ideal smile arc has the maxillary incisal edge curvature parallel to the curvature of the lower lip. Evaluation of anterior smile esthetics must include both static and dynamic evaluations of profile, frontal, and 45 degrees views to optimize both dental and facial appearance in orthodontic planning and treatment. This article presents the concept of the smile arc and how it relates to orthodontics-from the recognition of its importance, to its impact on orthodontic treatment planning, to how procedures and mechanics are adapted to optimize the appearance of the smile. Three cases are used to illustrate how treatment is directed, emphasizing how facial and smile goal setting go hand in hand.

Biomechanical testing of resorbable screws used for mandibular sagittal split osteotomies.

PURPOSE: The object of the study was to determine the suitability of specific resorbable screws for fixation of mandibular sagittal split osteotomies by in vitro biomechanical strength testing. MATERIALS AND METHODS: Resorbable screws (2.5 mm diameter) composed of a polylactic acidpolyglycolic acid copolymer were placed in an inverted L-pattern in overlapping urethane blocks representative of sagittal split mandibular surgery. In an in vitro model at room temperature, the test specimens were statically loaded until tensile failure occurred. On a different set of test specimens, dynamic testing was done in an in vitro water bath at body temperature through cyclic loads representative of mastication until failure. RESULTS: In static testing, three 2.5-mm resorbable screws sustained an average peak load of 131 Kiloponds (Kp) (standard deviation, 5.2 Kp) with 5.5% strain at yield. In dynamic testing, the resorbable screws tolerated a 45.3-Kp load for an average of 340,675 cycles (22,783 standard deviation). Several of these test specimens did not ultimately fail and were further evaluated by static testing with an average load of 77.4 Kp until fixation failure occurred. CONCLUSIONS: These laboratory results indicate a relatively high resistance to biomechanical loads representative of mastication and suggest that 2.5-mm resorbable screws of this particular polylactic acid-polyglycolic acid copolymer may be effective in fixation of the postoperative unrestrained sagittal split mandibular osteotomy.

The emerging soft tissue paradigm in orthodontic diagnosis and treatment planning.

Until now, orthodontic diagnosis and treatment planning has been based on hard tissue relationships and on the Angle paradigm that considers ideal dental occlusion 'nature's intended ideal form'. In this view, the clinician and nature are partners in seeking the ideal. In the modern biological model, variation is accepted as the natural form; ideal occlusion is the exception rather than the rule, and the orthodontist and nature are often adversaries. The orthodontist's task is to achieve the occlusal and facial outcomes that would most benefit that individual patient, whose esthetic concerns are often paramount. Because the soft tissues largely determine the limitations of orthodontic treatment, from the perspectives of function and stability, as well as esthetics, the orthodontist must plan treatment within the patient's limits of soft tissue adaptation and soft tissue contours. This emerging soft tissue paradigm in diagnosis and treatment planning places greater emphasis on clinical examination of soft tissue function and esthetics than has previously been the case, and new information in these areas is required.

How to avoid surgical failures.

Problems and failures in orthodontic-orthognathic surgical treatment are frequently discussed among colleagues, but not often written about. This lack of documentation may be attributed to a natural inclination for us to report our successes and hide our failures. More positively, we believe the lack of written material on complications probably relates more to the overwhelming success rate in these procedures than to an inclination to hide failures. In addition, some complications are clearly a result of the orthodontic care before and/or after the surgical procedure. This article concentrates on exploring the many complications in orthognathic surgery that are more a result of the orthodontic phase of care, and how the orthodontist can react to and manage surgical complications to achieve a successful result. The more the orthodontist understands the nature of surgical problems, the more able he/she is to manage them.

Effect of simulated intraoperative heating and shaping on mechanical properties of a bioabsorbable fracture plate material.

Heating bioabsorbable fracture fixation plates to above their glass transition temperature renders them temporarily malleable, thus facilitating their adaptation to the underlying bone geometry, although the consequence of heating is not well understood. Poly (L-lactide-co-glycolide) copolymer specimens were heated under various conditions, and the effects on specimen mechanics were assessed. Heating temporarily increased toughness while slight reducing flexural modulus. No lasting effects on in vitro material degradation were seen.

Bioabsorbable polymer science for the practicing surgeon.

The structure and function relationships of polymers have long been the purview of engineers and polymer chemists. As bioabsorbable polymer implants continue to make inroads in the medical implant armamentarium, surgeons, long familiar with the properties and handling characteristics of metal implants, may find it advantageous to become aware of some of the unique characteristics of these types of materials so that an informed decision can be made regarding their usage. In this article, we present, in relatively nontechnical terms, the salient features of polymers in general and absorbable polymers in particular.

Bioabsorbable fixation devices: status for the craniomaxillofacial surgeon.

With time, more and more types of medical devices become available to assist the surgeon in managing patients. Bioabsorbable fixation devices, which have been directed toward the orthopedic surgeon over the past 10 years, are but one example. One aim of this article is to present the current status of bioabsorbable devices in medical practice to the craniomaxillofacial surgeon who may not be aware of the inroads this technology has made. A bioabsorbable fixation system has become available for use by the craniomaxillofacial surgeon, which is described. A further aim of this article is to present concisely the testing rigor required of such devices before their introduction to the U.S. market. This has the added benefit of explaining the important role of the surgeon in developing and helping reduce to standard clinical practice the use of new technologies.

Combined rapid maxillary expansion and protraction facemask in the treatment of Class III malocclusions in growing children: a prospective long-term study.

A prospective study of 28 growing children (mean age of 8 years 3 months) with Class III malocclusions was consecutively treated using rapid maxillary expansion and maxillary protraction. All patients were treated from a negative overjet to a positive overjet and from a Class III dental malocclusion to a Class I dental relationship. For each patient, a lateral cephalogram was taken before treatment (T1), immediately posttreatment (T2), and after an observation period (T3) averaging 2 years 5 months. Using analysis of variance, the cephalograms were analyzed to determine skeletal and dental changes resulting from treatment. Long-term changes (2 years 5 month observation period) were also evaluated. Results showed that immediately posttreatment, the maxilla moved anteriorly a mean of 1.54 mm and Sella-Nasion-A point increased 0.87 degree. The maxillary teeth moved anteriorly 2.73 mm and proclined 5.23 degrees, while the mandible rotated in a downward and backward direction. Long-term, the anterior position of the maxilla was maintained, but some of the Class III correction was lost because of mandibular growth. Comparison of this study's results to Riolo's longitudinal Class I data showed that, overall, rapid palatal expansion and maxillary protraction produced a small orthopedic effect with a moderate dentoalveolar effect which together contributed to the correction of the Class III malocclusion.

Evaluation of video imaging prediction in combined maxillary and mandibular orthognathic surgery.

The purpose of this study was to evaluate the accuracy of the soft tissue profile "line drawings" predicted by Quick Ceph Image in combined maxillary and mandibular orthognathic surgical procedures. Preoperative (mean = 27.7 days presurgical) and posttreatment (mean = 11.5 months postsurgical) lateral cephalograms of 40 white patients (10 males and 30 females) who had completed treatment that involved orthodontics, one-piece LeFort I osteotomy, and mandibular advancement by bilateral sagittal split osteotomy with or without genioplasty were used in the study. Forty-five lateral hard and soft tissue landmarks were digitized, using the "on-screen" digitizing option, for each cephalogram and for each computer predicted posttreatment tracing. A customized analysis consisting of 24 linear and 4 angular measurements was used to analyze the differences between the actual posttreatment cephalometric landmark measurements and computer predicted landmark measurements. Statistically significant differences between the posttreatment cephalometric soft tissue profiles and the computer predicted soft tissue profiles were analyzed for the total sample, patients grouped according to: magnitude and direction of maxillary movements, adjunctive genioplasty procedure, V-Y closure of the LeFort I incision, and gender and age differences. The results indicated that for some of the soft tissue landmarks, differences were found between the posttreatment and the computer predicted profiles. Differences between the predicted and actual posttreatment soft tissue profiles may be attributed to the inaccuracy of Quick Ceph Image's default soft to hard tissue ratios when predicting the soft tissue response to combined maxillary and mandibular orthognathic surgical procedures.

A comparative biomechanical analysis of resorbable rigid fixation versus titanium rigid fixation of metacarpal fractures.

Linear (two-dimensional) and three-dimensional (3D) plating systems (Poly-Medics) composed of the resorbable copolymer of polyglycolic acid (PGA) and poly-l-lactic acid (PLLA) (Lactosorb) were studied in vitro. The plates were applied to osteotomized fresh frozen human cadaveric metacarpal bones that were then tested for torsional rigidity and three-point bending strength and rigidity. The results were compared to those from another study of two low-profile titanium plating systems (Leibinger and Synthes). Analysis of variance revealed that the linear-flat Lactosorb plate and screws had apex dorsal rigidity and force-to-displacement measurements equal to all but two of the titanium plates (3D). The 3D-flat Lactosorb plate had the highest torsional rigidity of the resorbable system, but it was only moderately rigid compared to the titanium plating systems. This in vitro biomechanical study of the copolymer PGA-PLLA plating system indicates that, in clinical applications, it may be better suited for metacarpal fractures rather than proximal phalangeal fractures due to the lower demands of torsional loading compared to apex bending.

Bioresorbable implants--practical considerations.

Traditional metal implants, primarily used for internal fixation, have been used by the orthopedic surgeon for years. Decades of development have produced such devices for almost every conceivable need. Despite their widespread use, a relatively consistent set of problems or issues have been identified. These include the potential for long term migration, breakage, stress shielding, reaction to the material, interference with standard imaging techniques, and growth restriction in young patients. A number of bioresorbable polymer devices have recently become available to create a viable alternative for some indications. As expected with an evolving technology, solving one set of problems has engendered another. One of the most limiting aspects of bioresorbable polymers is their inherently lower strength compared to metals. Although more of an issue with some materials and applications than others, significant tissue reactions have been observed in some cases as well. This paper discusses the field of synthetic bioresorbable polymers in general, but with specific reference to those materials and devices that can be used in place of metal implants for internal fixation.

Resorbable bone fixation: its potential role in cranio-maxillofacial trauma.

The concept of biodegradable bone fixation devices, which provide sufficient rigidity to allow fracture healing and resorption thereafter, has significant appeal in cranio-maxillofacial trauma treatment; however, biodegradable bone fixation devices have not yet become available for clinical use in the craniofacial skeleton. This article reviews the obstacles in developing a resorbable polymer bone fixation system and describes the initial use of such a system in the treatment of cranio-maxillofacial trauma patients. It also discusses the potential role of a resorbable polymer bone fixation system in conjunction with the use of metal fixation in the management of facial fracture.

Nonsurgical treatment of open bite in nongrowing patients.

Successful treatment of the adult patient with an open bite dental or skeletal pattern often presents a difficult challenge. While the causes of open bite may be multifactorial in nature, there are specific diagnostic criteria that may allow for an orthodontic treatment modality incorporating extraction therapy with retraction of incisors. Two case presentations illustrate treatment of adult patients with open bites due to proclined incisors. The diagnostic criteria and mechanics for appropriate and successful treatment are discussed. Although the selection of extraction therapy for correction of anterior open bite has a narrow range of application in the overall scheme of open bite treatment, this treatment method has certain areas of application in which success may be anticipated.

The accuracy of video imaging in orthognathic surgery.

Video imaging is an important emerging technology in planning orthognathic surgery and educating patients about the esthetic effects of treatment. The presurgical cephalograms of 56 patients, 41 with mandibular advancement alone and 15 with mandibular advancement plus genioplasty, were digitized, and the computer-generated soft tissue "line drawing" predictions were compared with the actual posttreatment cephalograms. Video images of the patients' presurgical lateral view were obtained, and two experienced clinicians compared the computer generated video image predictions with the actual posttreatment profile. Video images judged very good or excellent were considered acceptable for treatment planning; 60% to 83% met this criterion, depending on the profile area viewed. The percentage of acceptable images in the lower lip, labiomental fold, and chin area decreased with the addition of a genioplasty. The predicted and actual posttreatment soft tissue line drawings were quite similar for all areas except for the lower lip region, where statistically significant differences were noted, with the predicted lower lip more retrusive and thinner than the actual contours. For the lower lip and chin, a 2 mm or more discrepancy was observed in 20% of the patients. In all cases, the actual image was judged more esthetic than the predicted image, allaying fears of unrealistically optimistic computer generated predictions.