Matthew J. Madsen

A Biomechanical Evaluation of Plating Techniques Used for Reconstructing Mandibular Symphysis/Parasymphysis Fractures

PURPOSE The purpose of this investigation was to evaluate and compare the biomechanical behavior of 5 different methods used to repair mandibular symphysis/parasymphysis fractures. MATERIALS AND METHODS Sixty synthetic polyurethane mandible replicas (Synbone, Laudquart, Switzerland) were used in this investigation. Ten controls and 10 each of the experimental groups were tested by subjecting 5 constructs in each group to vertical loading at the incisal edge and 5 constructs to torsional loading at the molar region by an Instron 1331 (Instron, Canton, MA) servohydraulic mechanical testing unit. The 5 methods of reconstruction include: arch bars using 18-gauge stainless steel wire with an acrylic lingual splint, 2 2.4-mm lag screw technique, 2 2.0-mm 4-hole locking miniplates, 2 2.0-mm 6-hole nonlocking miniplates, and 2 2.4-mm 6-hole limited-contact dynamic-compression plates. Mechanical deformation data within a 0 to 900 N range were recorded. Yield load, displacement at yield load, and stiffness were determined. Means and standard deviations were derived and compared for statistical significance using a Fishers protected least significant differences test with a confidence level of 95% (P < .05). Third-order polynomial best-fit curves also were created for each group to further evaluate and compare the mechanical behavior. RESULTS For incisal edge loading, statistically significant differences were noted between the lag screw technique and the arch bar, limited-contact dynamic-compression plate and locking miniplate; and between the nonlocking miniplate and the arch bar, limited-contact dynamic-compression plate and locking miniplate for stiffness. Additionally, statistically significant differences were noted between the lag screw technique and arch bar; and between the nonlocking miniplate and the arch bar, dynamic-compression plate and locking miniplate for yield load. For molar loading, statistically significant differences were noted between the lag screw technique and all other groups for both yield load and stiffness; as well as the arch bar and locking miniplate for stiffness. No statistically significant differences were noted between any groups for displacement at yield, for either incisal edge or molar loading. CONCLUSIONS Although statistically significant differences were noted between each of the fixation systems in their abilities to resist loads under the conditions tested, when placed in the context of functional parameters, all systems met the requirements for incisal edge loading. When molar loading was considered, the lag screw technique performed more favorably than the other systems.

Management of Atrophic Mandible Fractures

Traumatic facial fractures that were once rarely encountered now present with increasing frequency in the elderly population. Included in this group of fractures are those of the atrophic edentulous mandible. As patients age and become edentulous, atrophy of the mandibular alveolar ridges and adjacent basal bone reduces bony surface area, bone density, and blood supply, making the mandible more brittle and increasing the likelihood of mandibular fracture during a traumatic event. Surgical treatment of these fractures has become more predictable and less morbid. However, because these fractures present so infrequently, many surgeons lack the relevant experience in handling them, and thus find the reduction and fixation of such injuries difficult. A number of techniques have been employed to treat this injury. This article reviews the more common modalities and presents updates on accepted surgical treatments.

Bone graft harvest site options in orthopaedic trauma: A prospective in vivo quantification study

PURPOSE We compare autologous bone graft volume from three different harvest sites and the associated pain levels at one and four weeks post-harvest. METHODS We prospectively collected a total of 47 consecutive autologous bone grafts in our level I trauma centre between July 2010 and September 2010 - 12 from the anterior iliac crest (AIC), 19 from the olecranon and 16 from the lateral aspect of the proximal tibia. RESULTS The mean ages for each group were 44.8, 41.9 and 42.1, respectively, with no statistically significant differences for age or gender. The mean quantities harvested were, respectively, 6.2 cm(3) (cubic centimetres) from the AIC, 5.7 cm(3) from the olecranon and 7.3 cm(3) from the proximal tibia, with a statistically superior quantity from the proximal tibia when compared to the olecranon and no differences between the other sites. Analysis of the visual analogue scale (VAS) at one week and four weeks post-harvest confirmed statistically that pain was more severe at the AIC site when compared to both the olecranon and proximal tibia sites. There were no infections or neurovascular complications. CONCLUSIONS We conclude that the proximal tibia and olecranon are acceptable alternatives to the anterior iliac crest for autologous bone graft and may be preferred when the location of the primary injury permits.

Failed Fixation in Atrophic Mandibular Fractures: The Case against Miniplates

Despite advances in the treatment of the fractured atrophic edentulous mandible, treatment continues to be difficult. Patient management is more complicated due to patients often being elderly with more complex medical problems. Rigid internal fixation has greatly improved outcomes with shorter treatment times, yet a consensus has yet to be reached regarding which method yields the most predictable results. Options include using small miniplates to larger reconstruction plates. Although each method has advantages, we present our experience with retreatment of failed miniplate fixation using load-bearing reconstruction plates of fractured atrophic edentulous mandibles.

The Use of Risdon Cables in Pediatric Maxillofacial Trauma: A Technique Revisited

Although less common than adult fractures, fractures of the pediatric maxillofacial skeleton present unique challenges. Different considerations including variations of anatomy including tooth buds, dental variations, as well as considerations for future growth must be addressed. When traditional techniques to treat adult fractures are applied for securing intermaxillary fixation (IMF) such as arch bars, difficulty arises because the primary teeth are shorter and conventional arch bar techniques may slip off intra or postoperatively. We present a technique to achieve both IMF as well as interdental stability using a Risdon cable. Although this technique is not new, we present it as our preferred method for treating pediatric fractures of the facial skeleton where IMF must be accomplished.