Biomechanical evaluation of an intramedullary clavicle screw in simple oblique and butterfly wedge fractures

This biomechanical study evaluates the performance of a solid titanium-alloy intra-medullary ( IM) clavicular screw in torsion and cantilever bending in cadaveric clavicle specimens with simulated simple oblique and butterfly wedge midshaft fractures. Thirty-two fresh-frozen male clavicles were sorted into six experimental groups: Torsion Control, Torsion Simple Oblique Fracture, Torsion Butterfly Wedge Fracture, Bending Control, Bending Simple Oblique Fracture, and Bending Butterfly Wedge Fracture. The experimental groups were controlled for density, length, diameter, and laterality. All other samples were osteotomy-induced and implanted with a single 90 mm × 3 mm clavicle screw. All groups were tested to physiologically relevant cutoff points in torsion or bending. There were no statistically significant differences in the performance of the oblique and butterfly wedge fracture models for any torsion or bend testing measures, including maximum torsional resistance ( p = 0.66), torsional stiffness ( p = 0.51), maximum bending moment ( p = 0.43), or bending stiffness ( p = 0.73). Torsional testing of samples in the direction of thread tightening tended to be stronger than samples tested in loosening, with all groups either approaching or achieving statistical significance. There were no significant differences between the simple oblique or the butterfly-wedge fracture groups for any of the tested parameters, suggesting that there is no difference in the gross biomechanical properties of the bone-implant construct when the IM clavicle screw is used in either a simple midshaft fracture pattern or a more complex butterfly wedge fracture pattern.

Lower Leg Fractures in Children and Adolescents—Comparison of Conservative vs. ECMES Treatment

Background: Lower leg fractures are one of the most common fractures in pediatric age. In general, treatment of lower leg fractures is predominantly non-operative, requiring clinical and radiological controls. Nevertheless, it can be observed that in recent years tibial shaft fractures have increasingly been treated surgically. The aim of the present study is to investigate treatment strategies in the context of different fracture types of the lower leg.Methods: In this retrospective chart review, we analyzed 168 children with a diaphyseal fracture of the lower leg admitted to a trauma center between 2005 and 2017. The fractures were classified according to the AO Pediatric Comprehensive Classification of Long Bone Fractures (AO-PCCF).Results: The frequency of fractures based on the AO-PCCF classification was as follows: Simple oblique fracture of the tibia (43.5%, n = 73), hereof 32 toddler's fractures, multifragmentary oblique fracture of the tibia in 14.3% (n = 24) and simple oblique fracture of both, tibia and fibula in 18 patients (10.7%). Most pediatric fractures were treated conservatively by cast (n = 125). Thirty-seven patients received an ECMES, whereas 3 patients were treated with an external fixator and also 3 fractures were stabilized by plate osteosynthesis. Conservatively treated patients were significantly younger (mean age 6.0) compared to patients treated with ECMES (mean age 10.2) or plate osteosynthesis (PO)/external fixator (EF) (mean age 11.3), even if toddler's fractures (mean age 2.0) are excluded (mean age 7.4). There was no difference in time to full weight-bearing, hospitalization of patients treated with ECMES compared to conservative therapy although ECMES-treated fractures show more instability. The consolidation time was significantly higher in ECMES treated patients compared to conservative therapy.Conclusion: Pediatric patients (≤4 years) with lower leg fractures most often showed simple oblique fractures of the tibia, half of them toddler's fractures, which were treated predominantly by conservative therapy. All in all, the consolidation time was longer in intramedullary nailing (ECMES) than in conservative therapy. Nevertheless, time to full weight bearing and duration of cast was the same in both groups, even though ECMES treated fractures show more instability.

Intramedullary nailing of extra-articular distal tibial fractures

Aims The aim of this study was to determine the immediate post-fixation stability of a distal tibial fracture fixed with an intramedullary nail using a biomechanical model. This was used as a surrogate for immediate weight-bearing postoperatively. The goal was to help inform postoperative protocols. Methods A biomechanical model of distal metaphyseal tibial fractures was created using a fourth-generation composite bone model. Three fracture patterns were tested: spiral, oblique, and multifragmented. Each fracture extended to within 4 cm to 5 cm of the plafond. The models were nearly-anatomically reduced and stabilized with an intramedullary nail and three distal locking screws. Cyclic loading was performed to simulate normal gait. Loading was completed in compression at 3,000 N at 1 Hz for a total of 70,000 cycles. Displacement (shortening, coronal and sagittal angulation) was measured at regular intervals. Results The spiral and oblique fracture patterns withstood simulated weight-bearing with minimal displacement. The multifragmented model had early implant failure with breaking of the distal locking screws. The spiral fracture model shortened by a mean of 0.3 mm (SD 0.2), and developed a mean coronal angulation of 2.0° (SD 1.9°) and a mean sagittal angulation of 1.2° (SD 1.1°). On average, 88% of the shortening, 74% of the change in coronal alignment, and 75% of the change in sagittal alignment occurred in the first 2,500 cycles. No late acceleration of displacement was noted. The oblique fracture model shortened by a mean of 0.2 mm (SD 0.1) and developed a mean coronal angulation of 2.4° (SD 1.6°) and a mean sagittal angulation of 2.6° (SD 1.4°). On average, 44% of the shortening, 39% of the change in coronal alignment, and 79% of the change in sagittal alignment occurred in the first 2,500 cycles. No late acceleration of displacement was noted. Conclusion For spiral and oblique fracture patterns, simulated weight-bearing resulted in a clinically acceptable degree of displacement. Most displacement occurred early in the test period, and the rate of displacement decreased over time. Based on this model, we offer evidence that early weight-bearing appears safe for well reduced oblique and spiral fractures, but not in multifragmented patterns that have poor bone contact. Cite this article: Bone Joint J 2021;103-B(2):294–298.

The “Chauffeur Fracture”: Historical Origins of an Often-Forgotten Eponym

This article describes the origin of the term “chauffeur fracture” used to indicate an oblique fracture of the radial styloid process with extension into the wrist joint. This kind of fracture was originally described by the British surgeon Jonathan Hutchinson in 1866. The invention of the automobile increased the incidence of this fracture among chauffeurs and cabdrivers. Indeed, at the beginning of the 20th century, motor vehicles were started by means of a crank-handle connected to the engine, which needed to be turned vigorously clockwise by hand. If the motor started unexpectedly, the crank-handle could jerk back violently and thereby cause a wrist injury due to sudden hyperextension. We retrospectively reviewed the literature and historical articles to better define the historical origins of an often-forgotten eponym. In 1904, the French surgeon Just Lucas-Championnière first evidenced the occupational origin of this fracture, so introducing the term “chauffeur fracture” to identify this injury.

Numerical Simulation of the Healing Process in the Tibia Diaphysis Fracture Fixed With External Fixation

The tibia diaphysis (shaft) fracture is one of the most common long bone fractures, and is usually treated with either the internal or the external fixations. How to choose a proper fixation type is still empirical and controversial. The objective of this study was to investigate whether the lateral external fixation (LEF) is suitable to treat the transverse and oblique tibia diaphysis fracture, from a mechanobiological perspective. The healing processes in the tibia fractures were simulated using the finite element method. The models of both the transverse and oblique (45°) tibia diaphysis fracture fixed with a LEF were built. A mechano-bioregulatory algorithm, which considered both the mechanobiological and biological environments, was developed to simulate the cell and tissue activities inside the callus. The results showed that both fractures healed in a typical secondary osteogenesis process. After 60 days, the regions of external callus and bone marrow were occupied with bone tissue. However, the mechanical stimulus in the inter-cortical region in the oblique fracture model with a less stiff LEF was greater than the stimulus in the transverse fracture model with the same LEF, indicating that the angled fracture was prone to generate greater instability. Moreover, increased osteogenic differentiation threshold only slightly affected the bone formation in the bridging areas, thus, had minor influences on the healing process. In conclusion, the lateral external fixation demonstrated satisfactory capacity in the treatment of the transverse and oblique tibia diaphysis fracture. The oblique fracture was more likely to be affected with a less stiff fixation.