Split-Type Fractures of the Spine: A New Minimally Invasive Percutaneous Technique

Abstract

Objective: This research presents a biomechanical analysis performed in the lumbar spine of a porcine animal model, considering a minimally invasive technique for the treatment of split fractures. Methods: Porcine spines were used to perform compression tests, considering three different approaches. Three groups were defined in order to verify and validate the proposed technique: a control group (1); spines with split fractures (2); and a treatment group (3). For the first group (control), spines were axially compressed until any kind of fracture occurred, in order to verify the strength of the structure. In the second group, split fractures were created to obtain the mechanical failure pattern of the model. In the third group, the split fractures were submitted to the proposed treatment, to verify the resistance achieved. The three groups were compared by means of axial compression tests. Statistical analysis was performed by ANOVA. Results: The control group (intact spine) and the treated split fracture group presented similar results (p>0.05), differing from the results for the untreated split fracture group (p<0.05). Conclusions: The tests performed in order to determine the behavior and strength of the lumbar spine when subjected to axial compression provided positive data for the development of a minimally invasive technique capable of restoring split fractures of the spine. Level of evidence III; Experimental research.

New Proposal for the Treatment of Coronal Split Fractures in Lumbar Vertebrae: The Fatigue Curve

“…Hubner et al, 24 published a study of the mechanical behavior of these fractures, considering that the first lumbar vertebra (L1) was fractured through different configurations of the fracture line. The authors discuss surgical and conservative treatment and show that coronal split fractures located in the anterior portion of the vertebral body are subject to fewer stresses and displacements, being more amenable to conservative treatment as compared to the fractures that occur in the middle of the vertebral body, corroborating with the model proposed by Denis et al, 5 In this sense, we developed the minimally invasive percutaneous surgical procedure for these fractures in particular, 25 previously presented in another article in this journal. The present study continues in that line of research and demonstrates, through an experimental test, the ability of the synthesis material being tested to support fractures, resisting a higher number of cyclic loads than fractured vertebrae in which no synthesis was used, under the same biomechanical conditions.…”

“…However, our group has researched these topics extensively over the last 10 years. We recently published other studies in this same journal that support the new technique, involving split type fractures and their biomechanical behavior, 24 in addition to having introduced this minimally invasive treatment more recently 25 in a study with other load conditions, demonstrating the viability of the proposed technique. We know that the in vivo environment is partially reproduced in the in vitro environment.…”

“…They concluded that the swine spine can be a good model for biomechanical studies of the human spine. This encouraged our group to use the model for trials of the new technique, 25 this time considering fatigue in this experimental study (in a set of swine lumbar vertebrae), for ethical reasons and due to the difficulty of obtaining vertebrae from human cadavers.…”

“…27 In this study we present an innovative way to perform fixation of coronal split fractures, supported by prior studies. 24,25 The method can improve the rigidity of the system through restoration of the anterior spine, avoiding the removal of the fragments, the migration of the disc to the focus of the fracture and pseudoarthrosis.…”

“…The maximum failure load found for these specimens in the static regime occurs between 7kN and 10kN (Hubner et al). 25 Loads at 40%, 60%, 70% and 80% of the maximum failure load were considered, following the test model executed by Parkinson et al, 18 Failure of the specimen was defined as the moment when the force versus displacement curve shows a sudden drop. 19 The S-N curve was established from the data obtained.…”