Preliminary results of stabilization of far distal tibia fractures with the distal tibial nail: A prospective, multicenter case series study.

INTRODUCTION: The distal tibial nail (DTN) is a novel retrograde intramedullary nail used for distal tibial fracture stabilization. We investigated the clinical results of DTN use for distal tibial fractures and compared them with those reported in the literature on locking plates and antegrade intramedullary nails. MATERIALS AND METHODS: This multicenter, prospective, observational cohort study examined distal tibial fractures with AO/OTA classification 43 types: A1, A2, A3 or C1. The primary outcomes included bone union rate, soft tissue problems, and surgical complications. Secondary outcomes were EuroQol-5 Dimension-5 Level (EQ-5D-5L), Self-Administered Foot Evaluation Questionnaire (SAFE-Q), and American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot clinical scores 1 year postoperatively. Incidence of varus or valgus/anterior-posterior flexion deformity with a difference of ≥5° and postoperative reduction loss rate were evaluated. RESULTS: Five men and five women were enrolled (mean age, 69 years [range, 30-77 years]), including one open-fracture-type Gustilo type IIIB case. Bone union was observed in all patients at 6 months postoperatively. Delayed union, leg edema, and guide pin breakage were observed in three, one, and one cases, respectively. No soft tissue or surgical complications were observed. During the final follow-up, the EQ-5D-5L, SAFE-Q, and AOFAS hindfoot scores were 0.876 (0.665-1.0), 83-92, and AOFAS 92.6 (76-100), respectively. Varus and retroflexion deformities were observed in one case each. DISCUSSION: DTN has been reported to have biomechanically equivalent or stronger fixation strength than locking plates or antegrade intramedullary nails. In addition, while DTN was thought to be less invasive for soft tissue and can avoid injury to the knee, it was thought that care should be taken to avoid medial malleolus fractures and posterior tibialis tendon injuries. Comparisons with literature treatment results for locking plates and antegrade intramedullary nails showed comparable to advantageous results. CONCLUSIONS: DTN treatment results for distal tibial fractures were as good as those for locking plates and antegrade intramedullary nails. DTN is useful for stabilization and does not compromise the surrounding soft tissues.

Pre-and postoperative factors associated with functional outcomes in patients with posterior malleolar fractures.

INTRODUCTION: Recent studies on posterior malleolar fractures mainly focus on the reduction quality and fixation of the posterior fragment since it contributes to ankle stability and articular congruency. However, the association of pre-and postoperative factors considering the whole ankle joint in postoperative functional outcomes remains unclear. Therefore, this study aimed to examine the association between pre-and postoperative variables for postoperative functional outcomes in patients with posterior malleolar fragments (classified as Haraguchi type I or II) and considered the association between reduction and fixation for small posterior malleolar fragments of less than 25% of the intra-articular surface. METHODS: This multicenter retrospective cohort study included 110 adult patients who underwent internal fixation for ankle fractures with posterior malleolar fragments. The primary outcome was the American Orthopaedic Foot and Ankle Society (AOFAS) score 12-months postoperatively. As pre-and postoperative variables, the preoperative demographic data, radiographic findings, operative method, postoperative radiographic findings, and complications were evaluated. In addition, univariable and multivariable logistic regression analyses were conducted to examine the association between pre-and postoperative variables and AOFAS scores. RESULTS: Twenty-four (21.8%) cases had postoperative complications. Univariate analysis showed that age was significantly according to AOFAS score-stratified groups in patients with Haraguchi type II fractures. Multivariable logistic regression analysis using bootstrapping in the Haraguchi type II group showed that postoperative complications were significantly associated with low AOFAS scores, indicating poor functionality. In both fracture types, postoperative complications had the highest odds ratio among the explanatory variables. In patients with small posterior malleolar fragments, fragment reduction, fixation, and ankle stability were not associated with AOFAS scores. CONCLUSIONS: Our results suggest that postoperative complications were associated with AOFAS scores at postoperative 12 months in patients with ankle fractures with posterior malleolar fragments. In patients with small posterior malleolar fragments, reduction and fixation were not associated with AOFAS scores. Therefore, clinical decisions for posterior fragment fixation should be made based on the possible risk of complications related to the surgical procedures in addition to the posterior malleolar fragment size.

Bone engineering by phosphorylated-pullulan and ß-TCP composite.

A multifunctional biomaterial with the capacity bond to hard tissues, such as bones and teeth, is a real need for medical and dental applications in tissue engineering and regenerative medicine. Recently, we created phosphorylated-pullulan (PPL), capable of binding to hydroxyapatite in bones and teeth. In the present study, we employed PPL as a novel biocompatible material for bone engineering. First, an in vitro evaluation of the mechanical properties of PPL demonstrated both PPL and PPL/ß-TCP composites have higher shear bond strength than materials in current clinical use, including polymethylmethacrylate (PMMA) cement and α-tricalcium phosphate (TCP) cement, Biopex-R. Further, the compressive strength of PPL/ß-TCP composite was significantly higher than Biopex-R. Next, in vivo osteoconductivity of PPL/ß-TCP composite was investigated in a murine intramedular injection model. Bone formation was observed 5 weeks after injection of PPL/ß-TCP composite, which was even more evident at 8 weeks; whereas, no bone formation was detected after injection of PPL alone. We then applied PPL/ß-TCP composite to a rabbit ulnar bone defect model and observed bone formation comparable to that induced by Biopex-R. Implantation of PPL/ß-TCP composite induced new bone formation at 4 weeks, which was remarkably evident at 8 weeks. In contrast, Biopex-R remained isolated from the surrounding bone at 8 weeks. In a pig vertebral bone defect model, defects treated with PPL/ß-TCP composite were almost completely replaced by new bone; whereas, PPL alone failed to induce bone formation. Collectively, our results suggest PPL/ß-TCP composite may be useful for bone engineering.

Diameter-selective alignment of carbon nanotubes on Si(001) stepped surfaces.

We report total-energy electronic-structure calculations based on the density-functional theory that provide stable adsorption sites, structural characteristics, and energy bands of carbon nanotubes (CNTs) adsorbed on the Si(001) stepped surfaces. We choose (5,5), (9,9), and (13,13) armchair CNTs with the diameters of 6.8 Å, 12.2 Å, and 17.6 Å, respectively, as representatives of CNTs and explore all the possible adsorption sites either on the terrace or at step edges. We find that the (9,9) CNT is most favorably adsorbed at the edge of the double-layer step DB along the ⟨110⟩ direction, whereas the (5,5) and (13,13) CNTs favor the terrace site where the CNTs are perpendicular to the Si dimer rows. This finding is indicative of the diameter-selective self-organized alignment of CNTs by exploiting the Si surface steps along the particular direction. We also find that the electronic structure of each CNT is modified upon adsorption depending on the adsorption site and the diameter of the CNTs. In particular, the (9,9) CNT at the most stable step edge site becomes semiconducting and the resultant valence and conduction bands exhibit nearly linear dispersion with the effective mass of 0.085 m0 (m0: bare electron mass), preserving the characteristics of the Dirac electrons. We also find that the flat bands appear near the Fermi level (EF) when the (13,13) CNT is adsorbed at the metastable DB step edge, inferring that spin polarization is possible for the CNT on the Si(001) stepped surface.