Clinical implications of orbital volume change in the management of isolated and zygomaticomaxillary complex-associated orbital floor injuries.

BACKGROUND: Orbital floor injuries can occur in isolation or in association with zygomaticomaxillary complex fractures. Volumetric computed tomographic measurements of affected orbits are investigated for utility in guiding management in these two groups. METHODS: The medical records of all patients with craniomaxillofacial injuries (2003 to 2005) were reviewed. Of 522 total patients, 45 patients had isolated orbital floor fractures, 13 of whom underwent repair (29 percent), and 64 had zygomaticomaxillary complex fractures, 36 of whom underwent reconstruction (56 percent) and 10 of whom underwent orbital floor repair (16 percent). Radiographic criteria for floor exploration included 50 percent area fracture in isolated injuries and 10-mm estimated zygomaticomaxillary complex compression in zygomaticomaxillary complex-associated floor injuries. Volume measurements of the affected orbits were obtained and compared with the uninjured contralateral orbit. RESULTS: Before treatment in the operative zygomaticomaxillary complex group, there was an average decrease in orbital volume of 18.3 percent. In the isolated orbital floor group, there was an average increase in orbital volume of 28.3 percent. CONCLUSIONS: Zygomaticomaxillary complex-associated orbital floor injuries can be compressive injuries associated with loss of volume, whereas isolated injuries generally result in volume expansion. Radiographic criteria are often considered in the decision to proceed with orbital floor exploration to avoid late enophthalmos. The literature suggests that a 20 percent change in orbital volume results in perceptible deformity. Therefore, a radiographic criterion of 50 percent floor area (28 percent volume increase) in isolated injuries may be too stringent; an estimated 10 mm of compression (18.3 percent volume change) is a reasonable operative criterion for floor exploration in zygomaticomaxillary complex-associated injuries.

Triple chimeric flap based on anterior tibial vessels for reconstruction of severe traumatic injuries of the hand with thumb loss.

BACKGROUND: Reconstruction of severe traumatic injuries of the hand with digit loss may require multiple procedures over a prolonged period. The authors present a clinical series of patients in which these types of injuries were reconstructed in a single operation. METHODS: A chimeric flap based on the anterior tibial vessels is described. A total of three free tissue transfers included an anterior tibial flap, a dorsalis pedis flap, and a great toe wrap-around flap. These triple flaps were transferred to resurface the defects of the mutilated hand, which was involved in the thumb, first web space, volar palm, thenar eminence, or radial aspect of wrist. The cumulative size of the defects ranged from 9 x 11 cm to 12 x 18 cm. RESULTS: From 2002 to 2007, six patients with multiple defects of the hand and thumb underwent reconstruction using the described technique. The donor sites were covered by means of split-thickness skin grafting. All flaps survived and patients were satisfied with the functional and aesthetic outcome postoperatively at 6 to 12 months' follow-up. The average improvement of thumb opposition was 4.8 on the Kapandji scale. Sensory recovery of the thumb tip of S3 was achieved. There were no major donor-site complications. CONCLUSION: A chimeric flap based on the anterior tibial vessels is an excellent method of reconstruction of severe multilevel injuries of the hand, including thumb loss.

Favorable morphologic change of preosteoblasts in a three-dimensional matrix with in vitro microdistraction.

BACKGROUND: Distraction osteogenesis has been used to correct hypoplastic and asymmetric bony deformities in the growing patient, yet its underlying cellular mechanisms are poorly understood. Using a new in vitro model, the microdistractor, morphologic properties of preosteoblasts under mechanical strain were studied. METHODS: Mouse calvarial MC3T3 cells were suspended in a polymerized three-dimensional collagen gel and stressed for 14 days as one of three groups (n = 30): (1) distraction (0.5 mm/day); (2) oscillation (1 mm/day for 2 days alternated with 1 mm/day for 2 days); and (3) control (no force). A computer modeling system, KS-300, was used to record cell shape (aspect ratio) and orientation (deviance from axis of stress). RESULTS: In part I of the study, morphologic cellular changes were found to be even throughout different regions of the gel (central versus peripheral, versus different vertical layers), suggesting the force was evenly applied to all cells in the gel. In addition, when linear distraction forces were applied, morphologic change occurred over time, suggesting a morphologic response to the applied stress. In part II of the study, with different forces applied, morphologic changes occurred over time such that linear distraction forces caused cells to elongate and align in a parallel direction to the force, whereas oscillation caused cells to switch from parallel (with distraction) to perpendicular (with compression) orientation relative to the force applied. CONCLUSION: The authors' data suggest that the microdistractor device is an effective in vitro model for studying the cellular response to distraction stresses. It may be used in future studies to optimize clinical methods of distraction.

In vitro microdistraction of preosteoblasts: distraction promotes proliferation and oscillation promotes differentiation.

Osteoblast biology is influenced in vivo by a 3-dimensional (3D) extracellular matrix that mediates their adhesion and interaction and by a constant state of compressive and tensile forces. To study the role of mechanical stress on osteoblasts in vitro, these parameters must be addressed. Therefore, this study describes the use of a novel, in vitro system that subjects cells to distractive and compressive forces in a 3D environment. This system, termed a microdistractor system, was used to apply linear forces to 3D collagen type I gels containing preosteoblasts. Gels were induced for up to 16 days in osteogenic medium and subjected to either constant linear distraction (distraction gels) or to repeating cycles of distraction and compression (oscillation gels). The effect of these stresses was evaluated over time by measuring proliferation rates, protein synthesis (i.e., cellular activity), and osteogenic differentiation levels. While linear forces in general appeared to increase protein synthesis, force-specific effects on proliferation and differentiation were observed. Specifically, distraction forces appeared to enhance MC3T3 proliferation while distraction/compressive forces appeared to accelerate their osteogenic differentiation program. Therefore, these results suggest that the microdistraction system may be an appropriate in vitro system for the study of mechanobiology in osteoblast phenotype.

Suction-assisted lipoplasty: physics, optimization, and clinical verification.

BACKGROUND: Although suction-assisted lipoplasty (SAL) has been clinically practiced for more than 25 years, comparatively little investigation into fundamental physics of the instrumentation used in the procedure has been conducted. Moreover, relatively little is known about the clinical impact or merit of the wide variety of instrumentation currently available. OBJECTIVE: In this study, we examined the physics related to the various components of instrumentation used in lipoplasty, and developed means to optimize performance based on quantified bench and clinical data. METHODS: The components used to construct a lipoplasty system (vacuum pump, suction tubing, suction canister, and suction cannula) were first evaluated using methods of bench experimentation. A selected set of components/parameters were then evaluated in a clinical setting, and the results were correlated to the bench data. The following design parameters were analyzed: for cannulas-shaft length, shaft internal diameter, port size/pattern, and venting; for tubing-length, internal diameter, and collapsibility; for canisters-volume, pull-down speed, gradation precision, and splash-related issues; and for vacuum pumps-vacuum level and flow rate. RESULTS: Each of the system components can have a significant impact on the overall performance of the system. A simple calculation is presented that can be used to quantify the relative "resistance" and, therefore, speed of any selected cannula or tube. Port area is shown to be an important aspect of cannula design and clinical performance. Clinical data are shown to correlate reasonably with bench data, which imparts credibility to the bench data and provides a platform from which to extrapolate other bench data to the clinical setting. CONCLUSIONS: With clinical objectives in mind, guidelines and recommendations are presented, based on the data we collected, to optimize a lipoplasty system with regard to choices of the vacuum pump, suction tubing, and canister. With the ideal system in place, the cannula becomes the only remaining variable. Cannula properties and performance were also studied and are discussed in detail.

Cardiac morbidity and mortality after surgery for gastrointestinal carcinomas.

The number of Americans undergoing surgery for gastrointestinal (GI) cancer is increasing, as is the prevalence of cardiovascular disease. Clinical risk factors have been found to be useful in predicting cardiac events after vascular procedures. Their utility for predicting cardiac events after GI carcinoma surgery is unclear. We performed a retrospective review in order to determine whether clinical risk factors are useful in predicting cardiac events in patients undergoing GI carcinoma surgery and to ascertain the incidence of postoperative cardiac events. From 1998 to 2003, 333 patients were identified, with an average age of 56 years. One hundred one (30.3%) patients had one or more clinical risk factors. The overall cardiac event rate was 3.9 per cent. Age > 70 years was the only risk factor associated with a cardiac event. There was a trend toward increased cardiac risk with increasing number of risk factors. In the absence of clinical risk factors, cardiac events after surgery for GI carcinoma are low. There is an increased cardiac risk in patients > 70 years and a trend toward increased cardiac events as the number of clinical risk factors increases.