BackgroundAnatomic reduction of intra-articular fractures of the tibial plateau and distal radius can be difficult to achieve. Treatment goals are centered on restoring the native anatomy and articular congruency. Several surgeons in the USA have begun using an inflatable bone tamp to reduce these fracture patterns. The concept is built on the success of the tamp in kyphoplasty of the spine, but it has yet to be tested in the lab for use in the extremities. We performed an investigation into the safety and efficacy of using an inflatable bone tamp for intra-articular fracture reduction of the tibial plateau and distal radius.Materials and methodsPaired cadaveric specimens were obtained for a total of six proximal tibias and six distal radii. Intra-articular depression-type fractures were created in all specimens. The inflatable bone tamp was then used to reduce the depression. For comparison, the tibias were fractured on the medial and lateral side and a conventional metal tamp was used on the contralateral side of the balloon. Fine-cut micro-computed tomography (CT) scans were performed on all intact specimens, which were then fractured, and again after fracture reduction. CT data was used to measure the amount of restoration of the normal anatomy and to compare the effectiveness of the balloon to conventional methods.ResultsThe inflatable bone tamp was equivalent to conventional methods in large, minimally displaced fracture fragments and proved superior when comminution was present at the articular surface. No instances of overreduction or penetration into the joint were encountered with the balloon, whereas this was a common occurrence with conventional metal tamps. The inflatable tamp was successful in reducing all distal radius fractures without complication.ConclusionAnatomic reduction of impacted articular fractures should be the goal of any treating surgeon. In our cadaveric models, we have shown the inflatable bone tamp to be safe and effective in reducing depressed articular fractures around the tibial plateau and distal radius. The balloon offers the advantage of being minimally invasive and creating a symmetric, contained defect to hold bone filler for subchondral support.

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IntroductionPilon fractures represent a small percentage of all lower extremity fractures, but cause a disproportionate amount of disability and impairment. Modest clinical results of treatment of pilon fractures is the rule with only 25-71 % of patients having good or excellent results [1,4,5,7]. The popular understanding of the mechanism by which pilon fractures are created has been axial loading.The creation of a pilon fracture in the laboratory setting has been a challenge. Lauge-Hansen, using amputation specimens secured to boards which he manually twisted, was only able to create the pronation-dorsiflexion variety of pilon fractures [2]. To our knowledge, there are no reports of reliable methods of creating pilon fractures in the laboratory setting.The goal of our study was to create pilon fractures experimentally. The first objective was to determine the magnitude of axial loads required to create pilon fractures. The second objective was to evaluate the relationship between the extent of fracture comminution and the magnitude of axial loads which create pilon fractures. Materials and MethodsIn this IRB-exempt study, nine lower limb cadaveric specimens (distal two thirds of the tibia-fibula, ankle and foot) were obtained from the Body Bequeathal Program at a level-one trauma center. Four of the limbs were embalmed by standard procedures, while the remaining five were lightly embalmed. The specimens came from cadavers with no prior history of lower extremity injuries or surgery, and included the entire lower limb from six inches below the knee. Specimens were frozen at -20 degrees Celsius and thawed 24 hours prior to testing. Prior to testing, the specimens were radiographed to establish any pre-existing pathology including fractures or osteoporosis, as this would make comparison between mechanical testing results difficult. The limbs were transported to the University of Tennessee Engi- AbstractThe popular understanding of the mechanism which creates pilon fractures has been axial loading. The purpose of this project was to study the biomechanics of pilon fractures using contemporary mechanical testing in a cadaveric model. We attempted to reproduce pilon fractures in nine ankles using a drop-tower apparatus and measuring the force each foot met on impact. The position of the foot during impact and the height from which the foot was dropped was changed for each test. Limbs were radiographed both before and after injury and then grossly dissected. We were unable to reproduce a tibial pilon fracture using this methodology. Our results suggest that the mechanism of injury causing pilon fractures may be more complex than axial loading alone.

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