Concept: Fibrocartilage callus
OBJECTIVES: To report on a series of dogs and cats with long bone fractures that occurred as a direct consequence of linear external skeletal fixation (ESF) application. METHODS: Retrospective study. Data from the medical records and radiographs of canine (n = 4) and feline (n = 7) cases were collected from three referral and three first opinion practices in the UK (1999 to 2011). RESULTS: Long bone fractures occurred following the application of linear ESF either while the ESF was in situ or after removal. All fractures occurred through either a pin tract or an empty drill hole. Pins associated with ESF-related fracture tended to be in the higher end of the recommended size range. The majority of cases had additional complicating factors such as multiple injuries, revision surgery, poor owner compliance with postoperative exercise restriction and the presence of empty drill holes. CLINICAL SIGNIFICANCE: In cases with features that could complicate outcome, careful attention should be paid to recommendations for ESF application. Leaving empty drill holes is suboptimal. The retrospective nature of the study, low numbers of, and diversity amongst, cases should be taken into consideration when interpreting the results from this study.
BACKGROUND: The bone nonunion is an important complication of bone fracture repair. The existing models developed on small animal species prevent using osteosynthesis materials designed to be implanted in human bones. The goal of this study was to develop a nonunion process in a noncritical segmental tibial defect in sheep, a species analogous in size to humans. MATERIALS AND METHODS: The animals were divided into two groups of four animals each. In Group 1 (experimental), the defect was created by surgically stripping the periosteum from the edges of a distal tibial osteotomy, keeping the edges 5 mm apart, and placing an incomplete O-shaped silicone ring in the gap. Group 2 (control) was intervened with a simple fracture at the distal end of the tibia. In both groups an interlocking nail was used as a fixation system. Over 8 wk after surgery, radiographs and histologic and histomorphometric analyses were performed. RESULTS: The control group showed a typical bone repair process. In contrast, the experimental group showed a fracture line with rounded edges and a scarce callus formation. The bone callus showed reduced amount of bone formation and large content of fibrous tissue (P=0.001). CONCLUSIONS: These results indicate that our model developed an atrophic nonunion in sheep, a species having multiple similarities to humans, such as weight, size, bone structure, and bone remodeling process.
During the healing process after bone fracture, soft callus forms adjacent to the fracture site, is replaced by hard callus, and is finally remodeled to the original bone configuration. Although the cambium layer of the periosteum is reported to play an essential role in callus formation, we still lack direct in vivo evidence of this. To investigate the cell lineage of the soft callus, we analyzed the process of fracture healing in Prx1-Cre;ROSA26 reporter (R26R), Col1a1(3.6 kb)-Cre;R26R, Col1a1(2.3 kb)-Cre;R26R, Sox9-CreERT2;R26R, and Sox9-LacZ mice with X-gal staining. In the Prx1-Cre;R26R, in which the cells of the periosteum stained for X-gal before fracture, all cells in the soft callus were X-gal positive, whereas in the Col1a1(3.6 kb)-Cre;R26R mice, the cells in the periosteum before fracture stained for X-gal and the soft callus was partly composed of X-gal-positive cells. In contrast, in the Col1a1(2.3 kb)-Cre;R26R mice, in which the mature osteoblasts in the cambium layer of the periosteum were marked before fracture, no cells in the soft callus at the fracture site were X-gal positive. These results suggest that most of the cells in the soft callus are derived from the mesenchymal progenitors in the periosteum, and not from mature osteoblastic cells. Interestingly, in the Sox9-LacZ mice, Sox9-expressing X-gal-positive cells emerged in the periosteum adjacent to the fracture site 3 days after fracture. We demonstrated this by injecting tamoxifen into the Sox9-CreERT2;R26R mice for 3 days after fracture, so that these Sox9-expressing periosteal cells gave rise to cells in the soft and hard calli. Our findings show that the periosteal cells in which Sox9 expression is induced just after fracture are the major source of the chondrocytes and osteoblasts in the fracture callus.
It is proposed that the external asymmetric formation of callus tissues that forms naturally about an oblique bone fracture can be predicted computationally. We present an analysis of callus formation for two cases of bone fracture healing: idealised and subject-specific oblique bone fractures. Plane strain finite element (FE) models of the oblique fractures were generated to calculate the compressive strain field experienced by the immature callus tissues due to interfragmentary motion. The external formations of the calluses were phenomenologically simulated using an optimisation style algorithm that iteratively removes tissue that experiences low strains from a large domain. The resultant simulated spatial formation of the healing tissues for the two bone fracture cases showed that the calluses tended to form at an angle equivalent to the angle of the oblique fracture line. The computational results qualitatively correlated with the callus formations found in vivo. Consequently, the proposed methods show potential as a means of predicting callus formation in pre-clinical testing.
Genetic ablation of cyclooxygenase-2 (COX-2) in mice is known to impair fracture healing. To determine if teriparatide (human PTH1-34) can promote healing of Cox-2-deficient fractures, we performed detailed in vivo analyses using a murine stabilized tibia fracture model. Periosteal progenitor cell proliferation as well as bony callus formation was markedly reduced in Cox-2-/- mice at day 10 post-fracture. Remarkably, intermittent PTH1-34 administration increased proliferation of periosteal progenitor cells, restored callus formation on day 7, and enhanced bone formation on days 10, 14 and 21 in Cox-2-deficient mice. PTH1-34 also increased biomechanical torsional properties at days 10 or 14 in all genotypes, consistent with enhanced bony callus formation by radiologic examinations. To determine the effects of intermittent PTH1-34 for callus remodeling, TRAP staining was performed. Intermittent PTH1-34 treatment increased the number of TRAP positive cells per total callus area on day 21 in Cox-2-/- fractures. Taken together, the present findings indicate that intermittent PTH1-34 treatment could compensate for COX-2 deficiency and improve impaired fracture healing in Cox-2-deficient mice.
- The Veterinary clinics of North America. Equine practice
- Published 8 months ago
Many long bone fractures that are not considered repairable in the adult horse are repairable in the foal. This is largely because of reduced patient size and more rapid healing in the foal. When there is no articular communication, the long-term prognosis for athletic function can be very good. Emergency care and transport of the foal with a long bone fracture is different than the adult.
Trabecular bone fractures constitute a major health issue for the modern societies, with the currently established prediction methods of fracture risk, such as Bone Mineral Density (BMD), resulting in errors up to 40%. Fracture-zone prediction based on bone’s micro-structure has been recently proposed as an alternative prediction method of fracture risk. In this paper, a Classification System (CS) for the automatic fracture-zone prediction based on an Ensemble of Imbalanced Learning methods is proposed, following the observation that the percentage of the actual fractured bone area is significantly smaller than the intact bone in the case of a fracture event. The sample is divided into Volumes of Interest (VOIs) of specific size and twenty-nine morphometrical parameters are calculated from each VOI, which serve as input features for the CS in order for it to separate the input patterns in to two classes: Fractured and non-Fractured. To this end, two well-established Imbalanced Learning methods, namely Random Undersampling and Synthetic Minority Oversampling, and two popular classification algorithms, namely Multilayer Perceptrons and Support Vector Machines, are tested and combined accordingly, to provide the best possible performance on a dataset that contains forty-five specimens' pre- and post-failure scans. The best combination is then compared with three well-established Ensembles of Imbalanced Learning methods, namely RUSBoost, UnderBagging and SMOTEBagging. The experimental results clearly show that the proposed CS outperforms the competition, scoring in some occasions more than 90% in G-Mean and Area under Curve metrics. Finally, an investigation on the significance of the various trabecular bone’s biomechanical parameters is made using the Sequential Forward Floating Selection technique, in order to identify possible biomarkers for fracture-zone prediction.
Closed reduction is generally recommended for acute nasal bone fractures, and rhinoplasty is considered in cases with an unsatisfactory outcome. However, concomitant rhinoplasty with fracture reduction might achieve better surgical outcomes. This study investigated the surgical techniques and outcomes in patients who underwent rhinoplasty and fracture reduction concomitantly, during the acute stage of nasal bone fracture.
Nasal bone fractures comprise almost 40% of all facial injuries. Most are initially reduced using closed reduction. This study introduces a newly developed method, the clip operation via endonasal approach.
In this study, our objective was to evaluate effects of leptin on fracture healing in rats. Seventy two male Sprague-Dawley (SD) rats were randomized into 3 groups. Standardized femoral fractures were created in all the rats. Group A was treated with 1 mL normal saline (NS), group B with 0.3 μg/kg leptin in 1 mL NS, and group C with 0.5 μg/kg leptin in 1 mL NS for 2 weeks intraperitoneally. Each group was divided into three subgroups including 8 rats for evaluation at 2, 4 and 8 weeks. Radiological evaluation showed that callus formation of group B and C was all significantly higher than group A at 8 weeks (P=0.04 and P=0.013, respectively). There was no statistically significant difference in fracture healing between group B and group C at 8 weeks (P=0.197). Histological evaluation revealed fracture healing of group B and C was better than group A at 4 weeks (P=0.01 and P=0.002, respectively) and 8 weeks (P=0.008 and P=0.003, respectively). Micro-computed tomography (Micro-CT) analysis demonstrated that greater amounts of bony callus and evidence of bone fusion were observed in group B and C at 4 weeks (P=0.02 and P=0.04, respectively) and 8 weeks (P=0.005 and P=0.001, respectively) compared to group A. Group C also had better fracture healing than group B at 8 weeks (P=0.01). In conclusion, leptin has a positive effect on rat femoral fracture healing.