Assessment of neovascularization during bone healing using contrast-enhanced ultrasonography in a canine tibial osteotomy model: a preliminary study

Evaluation of recombinant human erythropoietin as a promoter of bone healing in cats with femoral fractures

Background

The bone regeneration potential of erythropoietin (EPO) is not yet fully investigated, but some previous experimental studies demonstrated that its application activated the differentiation of osteoblasts and promoted bone formation.

Aim

The aim of the present study was to evaluate the effects of recombinant human erythropoietin (rhEpo) on bone healing in cats with fragmented long bone fractures.

Methods

Twelve cats were divided into two groups-control (n = 6) in which physiological saline was applied at the fracture gap site and EPO (n = 6) with the application of 1,000 IU rhEpo. The effects of EPO on blood erythrocyte counts, hemoglobin content, and hematocrit were monitored by serial complete blood cell tests, whereas bone formation was evaluated by clinical and radiographic examinations on post-operative weeks 1, 2, 3, 4, 6, and 8.

Results

All tested blood parameters were within the reference range. A faster fracture healing and full limb weight-bearing were observed in the EPO group, with statistically significant differences with respect to the control group.

Conclusion

The obtained results confirmed that the local application of rhEpo promoted bone healing in cats with fragmented femoral fractures and increased bone callus strength without having significant systemic effects.

The Use of Stromal Vascular Fraction in Long Bone Defect Healing in Sheep

The objectives of the present study were to evaluate (a) the feasibility of using stromal vascular fraction (SVF) and nanocrystalline hydroxyapatite (nHA) paste in combination for the treatment of segmental bone defect, (b) the quality of the callus produced, (c) the potential improvement of the autograft technique, and (d) the direct comparison of the biomaterial to the use of autogenous cancellous bone. Unilateral, segmental mid-diaphyseal bone defect was created on the right metatarsus of skeletally mature sheep animals (n = 24) under anesthesia (D0). Residual segments were stabilized by stainless-steel plates and appropriate screws. Defects were managed as follows: group A: use of nHA paste to filling, group B: use of autogenous bone graft mixed with nHA bone paste, placed in defect, group C: use of SVF mixed with nHA bone paste injected into defect, group D: use of bone graft and SVF with nHA paste before apposition in bone defect. SVF had been previously isolated from adipose tissue of the animals intra-operatively after digestion with collagenase solution and neutralization. Animals were evaluated clinically and by X-raying and ultrasonographic examination of the defect, at regular intervals, until D90. Ultrasonographic assessment performed along the length of the defect included calculation of the length of the bone defect and assessment of vascularization. SVF was successfully isolated from group C and D animals, with the average yield being 1.77 × 106 cells. The comparison of clinical scores (based on the 'Kaler scale') on each post-operative day indicated significant differences between the four groups on D1 to D30 (p < 0.01); the median clinical score within group A was 2.5 for D1-D30 and 1 for the entire period; respective scores for other groups were 1.5 (p = 0.07) and 0 (p = 0.033). Differences in radiographic assessment scores were significant for scores obtained on D60 (p = 0.049) and D90 (p = 0.006). There was a significant difference between the four groups in the length of the bone defect, as assessed ultrasonographically, for the entire length of the study; median values were 8, 8.5, 6, and 8 mm for groups A, B, C, and D, respectively (p = 0.008). There was a significance in the differences between median scores obtained during the histopathological examination: 2, 11, 13.5, and 12 for group A, B, C, and D (p = 0.022). There was an inverse correlation between the overall scores of histopathological evaluations and the length of the bone defect (observed on D90) (p < 0.0001) and a correlation between the overall scores and the radiographic assessment scores (obtained on D90) (p < 0.0001). This is the first study in which the efficacy of fresh autologous Stromal Vascular Fraction (SVF) from adipose tissue in enhancing bone healing in a long, weight-bearing, diaphyseal bone was evaluated. It is concluded that the lumbosacral region was an attractive site for harvesting adipose tissue, the use of SVF contributed to faster rehabilitation post-operatively, and SVF significantly enhanced bone formation; in general, the results indicated an osteogenic potential of SVF comparable to the gold standard autologous bone graft.

Comparison of radiographic scoring systems for assessment of bone healing after tibial plateau leveling osteotomy in dogs

Introduction

Accurate radiographic assessment of bone healing is vital in determining both clinical treatment and for assessing interventions aimed at the promotion of bone healing. Several scoring systems have been used to evaluate osteotomy changes following tibial plateau leveling osteotomy (TPLO). The goal of this study was to compare the ability of five radiographic scoring systems to identify changes in bone healing following TPLO over time (Aim I), and to evaluate the influence of limb positioning on TPLO osteotomy scoring (Aim II).

Materials and methods

Phase I-A randomized, blinded, prospective study was conducted using similarly positioned postoperative TPLO radiographs from seven dogs taken immediately postoperatively, 6-weeks, and 8-weeks postoperatively. Ten reviewers assessed the radiographs, and five different scoring systems were tested for each set including three previously published ones, a Visual Analog Score (VAS), and a subjective 11-point scale. For each system, responses for 6-week postoperative were compared to 8-week postoperative. Scores were judged as correct (=showing an increase in score), incorrect (=decrease in score), or unchanged (=same score). Phase II-An international group of 39 reviewers was asked to score radiographs from three dogs, taken in different positions, using the VAS grading system. Scores were averaged and comparisons were made for each set.

Results

Phase I-The VAS system identified the greatest number of sets correctly (76%), with the least unchanged scores (15%), and 9% incorrect scores. Phase II-All three patients had an increase in the average difference between VAS-scores for differently positioned radiographs compared to similarly positioned radiographs. The magnitude of change between different positions far exceeded the magnitude of comparison of the similarly positioned radiographs from the 6- and 8-week time point.

Discussion/Conclusion

The VAS system appears to be the most appropriate of the tested systems to identify small changes in bone healing. In addition, the positioning of postoperative TPLO radiographs makes a substantial difference in the healing score that is assigned. Care must be undertaken when performing postoperative radiographs in both the clinical and research setting to ensure accurate assessment of bone healing.

Evaluation of Bone Healing Using Contrast-Enhanced Ultrasonography in Non-Operative Treatment of Tibial Fracture in a Puppy Dog

Simple Summary

This report describes the clinical presentation of a tibial fracture in a young dog. treated with a conservative approach and subjected to X-ray, B-mode, Color Doppler and contrast-enhanced ultrasound (CEUS) examinations during the bone healing, in order to assess hemodynamic changes during fracture healing. This report showed the application of CEUS in controlling the fracture healing process.

Abstract

A 10-month-old mixed-breed male dog was presented with an oblique tibial fracture. The dog was treated with a Robert Jones-like bandage as a conservative approach, and was subjected to X-ray, B-mode, Color Doppler and contrast-enhanced ultrasound (CEUS) examinations during the fracture healing, in order to assess bone hemodynamic changes. B-mode, Power Doppler and CEUS examinations of the fracture gap were performed at 7, 20, 35, and 50 days post-trauma. Quantitative analysis of CEUS and perfusion parameters were obtained. On CEUS, a steep incline in signal numbers was visible in fracture gap at 7 days with peaks at 35 days, after which the vascularization decreases gradually over the next days. In this study, CEUS provided important information on the early stages of the callus formation and on the healing of neighboring tissues, allowing recognition of a correct bone healing. Moreover, the number of vascular signals on CEUS was greater than that on Doppler images on the same day. This report showed the application of CEUS in controlling the fracture healing process. CEUS could be a method of monitoring the remedial processes, assessing the tibial fracture perfusion characterized by low-velocity, small-volume blood flows.