The progress in quantitative evaluation of callus during distraction osteogenesis

Magnesium degradation-induced variable fixation plates promote bone healing in rabbits

BACKGROUND

Both initial mechanical stability and subsequent axial interfragmentary micromotion at fracture ends play crucial roles in fracture healing. However, the conversion timing of variable fixation and its effect on and mechanism of fracture healing remain inadequately explored.

METHODS

A magnesium degradation-induced variable fixation plate (MVFP) for femurs was designed, and its conversion timing was investigated both in vitro and in vivo. Then, locking plates and MVFPs with and without a magnesium shim were implanted in rabbit femur fracture models. X-ray photography and micro computed tomography (micro-CT) were performed to observe the healing of the fracture. Toluidine blue and Masson's trichrome staining were performed to observe new bone formation. The torsion test was used to determine the strength of the bone after healing. Finally, reverse transcription-polymerase chain reaction (RT-PCR) and western blotting were used to detect the expression of osteogenesis-related genes in the three groups.

RESULTS

The MVFP with sample 3 magnesium shim showed greater axial displacement within 15 days in vitro, and its variable capability was likewise confirmed in vivo. X-ray photography and micro-CT indicated increased callus formation in the variable fixation group. Toluidine blue and Masson's trichrome staining revealed less callus formation on the rigid fixation side of the locking plate, whereas the variable fixation group presented more callus formation, more symmetrical intraosseous calli, and greater maturity. The torsion test indicated greater torsional resistance of the healed bone in the variable fixation group. RT-PCR and western blotting revealed that the expression levels of BMP2 and OPG increased during early fracture stages but decreased in late fracture stages, whereas RANKL expression showed the opposite trend in the variable fixation group.

CONCLUSIONS

MVFP promoted faster and stronger bone healing in rabbits, potentially by accelerating the expression of BMP2 and modulating the OPG/RANKL/RANK signaling axis. This study offers valuable insights for the clinical application of variable fixation technology in bone plates and contributes to the advancement of both internal fixation technology and theory.

LEVEL OF EVIDENCE

level V.

Objective assessment of docking site consolidation in bone transport: the role of pixel value ratio in predicting healing outcomes

BACKGROUND

The management of docking site healing in bone transport remains a significant challenge in orthopedic surgery. Traditional assessment methods rely heavily on qualitative radiographic evaluations. This study investigates the utility of pixel value ratio (PVR), an objective quantitative measure, in assessing bone healing at the docking site during bone transport.

METHODS

This retrospective study included 47 patients who underwent bone transport for lower limb reconstruction between January 2015 and January 2020. Patients were categorized into bone union (n = 35) and nonunion (n = 12) groups based on docking site outcomes. PVR was calculated using two methods (PVR1 and PVR2) at six time points over 24 months post-docking. Subgroup analyses were performed based on gender, age, and surgical site.

RESULTS

Of 47 patients, 35 achieved bone union and 12 experienced nonunion. Both PVR1 and PVR2 were consistently lower in the union group compared to the nonunion group at all time points (p < 0.001). In the union group, PVR1 ranged from 1.064 ± 0.050 to 1.108 ± 0.062, while PVR2 ranged from 0.926 ± 0.079 to 0.946 ± 0.062. In the nonunion group, PVR1 ranged from 1.204 ± 0.057 to 1.273 ± 0.020, and PVR2 from 1.039 ± 0.060 to 1.148 ± 0.022. Subgroup analyses revealed that males had significantly lower PVR values compared to females, and tibial cases had lower PVR values compared to femoral cases in both union and nonunion groups (p < 0.05). All juvenile patients achieved union, compared to 71.4% of adults (p < 0.01).

CONCLUSION

PVR demonstrates significant potential as an objective tool for assessing docking site healing in bone transport procedures. The distinct patterns observed between union and nonunion cases provide a foundation for developing clinical guidelines to monitor and predict healing outcomes. Integration of PVR assessment into clinical practice could improve decision-making and optimize treatment protocols in bone transport procedures.

Bone Regenerate Evaluation Methods

Since its introduction by Ilizarov, the distraction osteogenesis technique has been used to treat trauma-related conditions, infections, bone tumors, and congenital diseases, either as methods of bone transport or elongation. One of the major dilemmas for the orthopedic surgeon who performs osteogenic distraction is establishing a reproducible method of assessing the progression of the osteogenesis, enabling the early detection of regenerate failures, in order to effectively interfere during treatment, and to determine the appropriate time to remove the external fixator. Several quantitative monitoring methods to evaluate the structural recovery and biomechanical properties of the bone regenerate at different stages, as well as the bone healing process, are under study. These methods can reveal data on bone metabolism, stiffness, bone mineral content, and bone mineral density. The present review comprehensively summarizes the most recent techniques to assess bone healing during osteogenic distraction, including conventional radiography and pixel values in digital radiology, ultrasonography, bone densitometry and scintigraphy, quantitative computed tomography, biomechanical evaluation, biochemical markers, and mathematical models. We believe it is crucial to know the different methods currently available, and we understand that using several monitoring methods simultaneously can be an ideal solution, pointing to a future direction in the follow-up of osteogenic distraction.

Experimental study on determining the degree of bone healing by wall thickness ratio analysis

To verify the reliability and accuracy of wall thickness ratio analysis to determine the degree of bone healing, fracture models were established with 6 beagles. X-ray, micro-CT, and CT scans were performed at 24 weeks. The healthy side and the affected side were used to simulate the three-dimensional geometric model after internal fixation, and the mesh was divided. The mean and median CT wall thickness values were obtained through the wall thickness analysis. X-ray, CT, micro-CT, and gross appearance were used to determine the degree of bone healing, which was compared with wall thickness analysis. There was a positive correlation between the average CT value and the median wall thickness. The correlation coefficient analysis of the median wall thickness ratio (R2) and healing index ratio (R3) showed a positive correlation. The results of the wall thickness ratio (R2) and the healing index ratio (R3) were used to determine bone healing, and the results were consistent with the results of the actual mechanical test and image analysis. The results of wall thickness ratio analysis were significantly correlated with the degree of bone healing. This method is simple, rapid, and practical to analyze and judge the degree of bone healing.

A comparative study of bone union and nonunion during distraction osteogenesis

BACKGROUND

The clinical characteristics of bone nonunion during distraction osteogenesis (DO) were rarely discussed. This study was employed to specify the difference between bone union and nonunion during DO.

METHODS

The patients with bone lengthening were recruited in our study. The bone union cases indicated the ones that remove the external fixator successfully, whereas the bone nonunion represented the bridging callus did not appear even after 9 months (an absence of bridging callus for at least three out of four cortices on plain radiographs) that needs autogenous bone transplantation. The differences in the pixel value ratio (PVR) growth of regenerated callus, lengthening index (LI), healing index (HI), external fixation index (EFI) and blood biochemical indexes between bone union and nonunion were analyzed.

RESULTS

A total of 8 bone nonunion and 27 bone union subjects were included in this study. The PVR growth in bone nonunion was significantly lower than that in bone union (0.19 ± 0.06 vs. 0.32 ± 0.16, P = 0.048). Interestingly, the HI and EFI in bone nonunion was significantly higher than that in bone union (62.0 ± 31.4 vs. 37.0 ± 27.4, P = 0.036; 75.0 ± 30.9 vs. 49.9 ± 16.1, P = 0.006). However, no significant difference with regard to LI was identified (0.76 ± 0.52 vs. 0.77 ± 0.32, P = 0.976). Moreover, the circulating level of urea and lymphocyte count in bone union was significantly lower than that in bone nonunion (4.31 ± 1.05 vs. 5.17 ± 1.06, P = 0.049; 2.08 ± 0.67 vs. 2.73 ± 0.54, P = 0.018). On the contrary, the circulating level of magnesium in bone union was significantly higher than that in bone nonunion (0.87 ± 0.07 vs. 0.80 ± 0.07, P = 0.014).

CONCLUSION

Compared to the bone union, the PVR growth was significantly lower, whereas the HI and EFI was significantly higher in the bone nonunion. Moreover, the circulating level of urea, magnesium and lymphocyte count was also different between these two. Therefore, the PVR, HI and EFI seems to be reliable and sensitive indicators to reflect the bone nonunion during DO, which might be considered in bone lengthening. Further prospective studies are still needed to elaborate the concerned issues.

Global trends and current status of distraction osteogenesis: Bibliometric analysis of publications from 1980 to 2021

Introduction: Distraction osteogenesis (DO) has become an important technology for the correction of various congenital and acquired skeletal ridge deformities. It is widely used in oral and maxillofacial surgery, orthopedics, and other disciplines. From 1980 to 2021, the cutting-edge research of DO has been continuously promoted, and the interaction between disciplines has also been deepening. However, the analysis on the global trend and status of DO is relatively rare. Therefore, the aim of our study was to summarize the global trends and current status of DO through bibliometrics. Materials and methods: Web of Science (WOS) core collection database and Medline were used to search DO-related literatures published during 1980-2021. The collected data are imported into Microsoft Excel, Microsoft Word, VOSviewer software for analysis and drawing figure/table. Results: A total of 7,721 publications were included in this study. The United States is the main contributing country to DO (ranking first in terms of total publications, sum of times cited and H-index). Harvard University was the main contributing institution to DO. Journal of Craniofacial Surgery is the main contributing journal of DO related articles. Buchman, SR is the main contributing author to DO related articles. DO related publications can be summarized into 7 clusters: 1) "mechanism study", 2) "limb bone distraction study", 3) "alveolar bone distraction study", 4) "temporomandibular joint ankylosis study", 5) "maxillofacial surgery study", 6) "skull distraction study" and 7) "mandible distraction study". Mandible distraction study has been a hot topic in recent years. In addition, the "management", "osteogenesis" and "reconstruction" of DO have been the research hotspots from 1980 to 2021. Conclusion: From 1980 to 2021, the total number of DO articles has increased rapidly and maintained a steady trend. The United States is the predominant country in the field. Surgery, dental, and oral surgery and orthopaedics are hot fields of DO research. The study of mandible distraction has been paid more and more attention and will become a hotspot in the future. Our study is beneficial for scientists to specify the research hotspot and development direction of DO.