David C. Kieser

The course and distribution of the inferior alveolar nerve in the edentulous mandible.

The authors undertook the study to determine the pattern of intrabony distribution of the branches of the inferior alveolar nerve (IAN) in the edentulous mandible. One hundred seven human cadaveric mandibles were microdissected from their buccal aspect. In each case the height and distribution of the IAN was classified. The authors found that the IAN was located in the lower half of the mandible in 73% of males and 70% of females. The most common branching pattern observed was a single nerve trunk with a series of simple branches directed at the superior border of the mandible (59.6% males, 52% females). The second most common pattern was that of a small nerve plexus in the molar region (21.1% males, 26% females). The results showed that the pattern of distribution does not significantly differ between the sexes, between sides of the jaw, or with age.

Projectile penetration into ballistic gelatin.

Ballistic gelatin is frequently used as a model for soft biological tissues that experience projectile impact. In this paper we investigate the response of a number of gelatin materials to the penetration of spherical steel projectiles (7 to 11mm diameter) with a range of lower impacting velocities (<120m/s). The results of sphere penetration depth versus projectile velocity are found to be linear for all systems above a certain threshold velocity required for initiating penetration. The data for a specific material impacted with different diameter spheres were able to be condensed to a single curve when the penetration depth was normalised by the projectile diameter. When the results are compared with a number of predictive relationships available in the literature, it is found that over the range of projectiles and compositions used, the results fit a simple relationship that takes into account the projectile diameter, the threshold velocity for penetration into the gelatin and a value of the shear modulus of the gelatin estimated from the threshold velocity for penetration. The normalised depth is found to fit the elastic Froude number when this is modified to allow for a threshold impact velocity. The normalised penetration data are found to best fit this modified elastic Froude number with a slope of 1/2 instead of 1/3 as suggested by Akers and Belmonte (2006). Possible explanations for this difference are discussed.

Displaced tibial intercondylar eminence fractures

Purpose. To review outcomes of 19 patients with tibial eminence fractures. Methods. Records of 10 female and 9 male patients with type II (n=3) and type III (n=16) displaced tibial intercondylar eminence fractures were reviewed. Nine of whom were skeletally immature aged 6 to 15 (mean, 12) years; the remaining 10 patients were aged 19 to 55 (mean, 32) years. 14 involved the left knee. All patients presented with a painful haemarthrosis and reduced range of movement. Results. The most common activity causing this injury was skiing (n=7, primarily in adult females [n=5]), followed by cycling or motocrossing (n=6) and falling or other sporting activities (n=6). The injury mechanisms entailed forced flexion with rotation (n=7), hyperextension with rotation (n=7, primarily in skeletally immature males [n=4]), and direct trauma (n=5, primarily in adult males [n=4]). Eight patients (60% of adults and 22% of children) had associated injuries of the knee, which commonly occurred after direct trauma. Two patients were treated in a cast or brace after closed or open reduction without fixation. Two patients underwent arthroscopic reduction and internal fixation, and 15 underwent open reduction and internal fixation (2 after failed arthroscopic reduction and 11 proceeded directly). Postoperatively, 7 patients had a positive Lachman test, but none complained of subjective instability. Ten patients had knee stiffness; all except one had been immobilised for 4 to 6 weeks. Seven patients had extension impingement; 6 of them had been treated with open reduction and internal fixation. Two patients underwent further surgery for debridement and screw removal at years 1 and 3. One patient developed arthrofibrosis and underwent arthrolysis at month 6, but knee stiffness remained. No patient underwent subsequent anterior cruciate ligament reconstruction. Conclusion. Tibial eminence fractures are as common in adults as in children. Female skiers are at higher risk. Stiffness is a more common complication than laxity. Early range-of-motion exercise may reduce stiffness and extension impingement.

Leading wound care technology: The ARANZ medical silhouette.

Despite major advances in medical technology and wound care, wound assessment and documentation still rely mainly on rudimentary measures. Many practitioners continue to estimate wound size using maximal length, width, and depth measurements with rulers and probes.1 Others use acetate tracings or equivalent measures to outline the wound onto a grid to estimate surface area and document wound border changes. Even fewer practitioners seem to routinely photograph wounds with an included scale for more visual records. This article presents a recently developed device that is changing clinical documentation, assessment, auditing, and interservice communication-the ARANZ Medical Silhouette (ARANZ Medical Limited, Christchurch, New Zealand).

Gunshot induced indirect femoral fracture: Mechanism of injury and fracture morphology

Introduction Indirect ballistic fractures occur when a projectile passes close to, but not contacting, the bone. The mechanism of how these fractures occur is not yet proven, but recently the acoustic shockwave has been excluded as a cause. The objective of this study is to determine whether the expanding temporary cavity, the collapse of this cavity or its oscillation causes these fractures. In addition, we describe the fracture morphology and biomechanical causes of this injury. Method 40 fresh deer femora were strain gauged and embedded in ballistic gelatin before being shot with four different projectiles with varying distances off the bone. Pressure recordings, chronographs and radar allowed assessment of local pressures and energy transfer. High-speed video allowed the temporal relationship between the temporary cavity and fracture formation to be analysed, while sample dissection allowed the fracture morphology to be described. Results The fractures produced were consistently wedge-shaped and caused by the expansion of the temporary cavity, flexing the bone beyond its yield point, causing tension failure on the cortex opposite the expanding temporary cavity and a compression wedge on the side of the cavity. Local pressure was not predictive of fracture formation but the energy transfer to the gelatin block was predictive. Conclusions Indirect fractures are caused by the expansion of the temporary cavity and relate to the proximity of this cavity to the bone. Fractures occur from flexion of the bone and classically display wedge-shaped fracture patterns with the apex of the wedge pointing away from the expanding cavity.

Identifying the source of bullet wipe: a randomised blind trial

ObjectiveTo assess the usefulness of scanning electron microscopy and energy dispersive x-ray spectroscopy in matching bullet wipe to the bullet.HypothesisBullet wipe can be used to match a bullet type to a crime scene.

Remote ballistic fractures in a gelatine model--aetiology and surgical implications.

BackgroundRemote ballistic femoral fractures are rare fractures reported in the literature but still debated as to their existence and, indeed, their treatment. This study aimed to prove their existence, understand how they occur and determine which ammunition provides the greatest threat. In addition, fracture patterns, soft tissue disruption and contamination were assessed to aid in treatment planning.MethodWe filmed 42 deer femora embedded in ballistic gelatine and shot with four different military (5.56 × 45 mm, 7.62 × 39 mm) and civilian (9 × 19 mm, .44 in.) bullets, at varying distances off the bone (0–10 cm).ResultsTwo remote ballistic fractures occurred, both with .44 in. hollow-point bullets shot 3 cm off the bone. These fractures occurred when the leading edge of the expanding temporary cavity impacted the femurs supracondylar region, producing a wedge-shaped fracture with an undisplaced limb, deceivingly giving the appearance of a spiral fracture. No communication was seen between the fracture and permanent cavity, despite the temporary cavity encasing the fracture and stripping periosteum from its base.ConclusionThese fractures occur with civilian ammunition, but cannot prove their existence with military rounds. They result from the expanding temporary cavity affecting the weakest part of the bone, creating a potentially contaminated wedge-shaped fracture, important for surgeons considering operative intervention.

Noninvasive management of an odontoid process fracture in a toddler: case report.

Study Design Case report. Objective Odontoid process fractures represent an uncommon injury in small children, with their optimal management remaining unclear. We present a case of conservatively managed displaced type 2 odontoid process fracture in a small child. Methods We analyzed clinical and radiographic outcomes of a restrained 2-year-old girl involved in a motor vehicle accident who sustained a displaced type 2 odontoid process fracture and was treated conservatively in a semirigid Aspen collar. Results The fracture progressively healed with callus formation evident at 6 weeks. By 12 weeks, the patient was asymptomatic and had regained head control and a full range of movement. Radiographic remodeling of the fracture was seen to improve over the 6-month follow-up. Conclusion This case illustrates that displaced type 2 odontoid process fractures can be successfully managed conservatively in small children.

The allograft sleeve: a case report of the surgical management of an interprosthetic fracture between a shoulder and elbow joint replacement

Periprosthetic fractures after shoulder and elbow joint replacement are recognized complications and their treatment is well reported in the literature. Fractures that occur between ipsilateral shoulder and elbow joint replacements, the so-called interprosthetic fractures, are infrequent and as a result their management is less well defined. We present a patient with an interprosthetic humeral fracture that required a novel approach to surgical management that has not been previously described and propose a simple treatment algorithm for the management of these in injuries.

Effect of ageing on the calibration of ballistic gelatin

Purpose Ballistic gelatin is commonly used as a validated surrogate for soft tissue during terminal ballistic testing. However, the effect of a delay between production and testing of a gelatin mould remains unknown. The aim of this study was to determine any potential effects of ageing on ballistic gelatin. Methods Depth of penetration (DoP) of 4.5 mm spherical fragment simulating projectiles was ascertained using mixtures of 10%, 11.25% and 20% Type A 250 Bloom ballistic gelatin. Testing was performed daily for 5 days using velocities between 75 and 210 m/s. DoP at day 5 was statistically compared with day 1, and net mass change was recorded daily. Results No significant difference was found for DoP observed with time in any of the samples (P>0.05). Spearman correlation was excellent in all moulds. The moulds with known standard calibrations remained in calibration throughout the study period. Mass loss of less than 1% was noted in all samples. Conclusion Mass loss was the only quantifiable measure of changes in the blocks with time, but did not correlate with any changes in DoP. This may provide reassurance when undertaking such testing that an inadvertent delay will not significantly alter the penetration properties of the mould. Future research is recommended to determine any potential effect on the mechanical properties of gelatin at higher velocity impacts and whether the calibration corresponds to an adequate simulation under such conditions.