Enhancing the Efficiency of Distraction Osteogenesis through Rate-Varying Distraction: A Computational Study

Finite element analysis safety of tibial cortex transverse transport

Aims

Tibial cortex transverse transport (TTT) represents an innovative surgical technique used in managing lower limb ischaemic conditions, focusing specifically on diabetic foot ulcers. This study aimed to assess the safety of TTT by evaluating the stress magnitude and distribution on the tibia and tibial osteotomy blocks.

Methods

A 3D finite element model was developed to simulate the TTT system, including the tibia, osteotomy blocks, skin, and TTT device. The models were reconstructed using Mimics, Geomagic, and SolidWorks, and analyzed with Ansys finite element processing software. To estimate the fracture risk under specific conditions, we calculated the stress limits and distribution the tibia could withstand without fracturing under various loading scenarios, such as torsion and axial compression.

Results

The results indicate that stress on the tibial cortex increased progressively with the advancement of bone transport fixation adjustment, and was primarily concentrated around the pinholes used to lift the osteotomy block. No significant differences were observed between the control and TTT groups.

Conclusion

Through finite element analysis, it was determined that TTT does not compromise the overall stability of the tibia, and the TTT device provides protection against bone fracture caused by window-cutting in diabetic patients. Therefore, to preserve the TTT system's stability, its components must be protected from high-impact forces.

A 4D time-lapse morphometry method to quantify bone formation and resorption during distraction osteogenesis

Distraction osteogenesis (DO) is widely utilized for treating limb length discrepancy, nonunion, bone deformities and defects. This study sought to develop a 4D time-lapse morphometry method to quantify bone formation and resorption in mouse femur during DO based on image registration of longitudinal in vivo micro-CT scans. Female C57BL/6 mice (n = 7) underwent osteotomy, followed by 5 days of latency, 10 days of distraction and 35 days of consolidation. The mice were scanned with micro-CT at Days 5, 15, 25, 35, 45, and 50. Histological sectioning and Movat Pentachrome straining were performed at Day 50. After registration of two consecutive micro-CT images of the same bone (day x and day y), the spatially- and temporally-linked sequences of formation, resorption and quiescent bones at the distraction gap were identified and bone formation and resorption rates (BFRdayx-y and BRRdayx-y) were calculated. The overall percentage error of the registration method was 2.98% ± 0.89% and there was a strong correlation between histologically-measured bone area fraction and micro-CT-determined bone volume fraction at Day 50 (r = 0.89, p < 0.05). The 4D time-lapse morphometry indicated a rapid bone formation during the first 10 days of the consolidation phase (BFRday15-25 = 0.14 ± 0.05 mm3/day), followed by callus reshaping via equivalent bone formation and resorption rates. The 4D time-lapse morphometry method developed in this study allows for a continuous quantitative monitoring of the dynamic process of bone formation and resorption following distraction, which may offer a better understanding of the mechanism for mechano-regulated bone regeneration and aid for development of new treatment strategies of DO.

Masquelet's induced membrane technique in the upper limb: a systematic review of the current outcomes

BACKGROUND

The Masquelet induced membrane technique is a surgical procedure that allows the reconstruction of segmental bone defects using a relatively simple approach that requires minimal resources from both the healthcare facility and the patient. Historically applied to the lower limb, this technique is gaining increasing attention in the literature for its use in the upper limb.

METHODS

A systematic review of the literature was conducted using the PubMed and Google Scholar databases to identify all studies reporting the outcomes of the Masquelet induced membrane technique in the long bones of the upper limb (humerus, radius, and ulna) with a sample size of at least 3 patients. The papers had to include the length of the bone defect, a description of the protocol used for treatment, the complications of each case, and the anatomical location of the defect. The studies that did not meet the above inclusion criteria were excluded.

RESULTS

The search identified 1044 studies, of which 15 met the inclusion criteria. These studies described a total of 156 patients with a mean age of 42 years. The affected bone segments included the humerus in 22 cases and the forearm in 134 cases. In 108 cases, the bone defect was septic. The average defect length was 4.5 cm. PMMA was used as a spacer in all cases, with antibiotics added in 77% of them. The average time interval between the first and second phases of the procedure was 9.5 weeks, and bone union took an average of 5.5 months. The mean follow-up duration was 48 months, and the complication rate was 21%, ranging from 0% to 75%.

CONCLUSIONS

The Masquelet induced membrane technique is a viable surgical option for managing segmental bone defects of the upper limb. However, the complication rate remains significant. Further research is needed to identify strategies to improve the outcomes of this technique.

LEVEL OF EVIDENCE

Level 2.

The accordion technique did not improve bone healing in a mouse model of distraction osteogenesis

Distraction osteogenesis (DO) is a valuable surgical method for limb lengthening and bone defect correction, but its lengthy consolidation phase presents challenges. The accordion technique (AT), involving compression and distraction of bone segments, has shown potential for enhancing healing. This study aimed to investigate the effectiveness of the AT conducted at three different time points (distraction phase, early consolidation phase, or late consolidation phase) compared to conventional DO in a mouse osteotomy model. Healing was evaluated using in vivo microCT, histology, and computational modeling. Results showed that bridging frequency, BV, and callus tissue composition were similar between conventional DO and late consolidation AT. In contrast, distraction phase AT led to delayed healing at day 15 with a 72% reduction in BV compared to DO, but no significant differences by the endpoint. Early consolidation AT showed significantly impaired healing compared to DO, with only 29% of mice achieving bony bridging, and significantly reduced bone marrow area of the endpoint callus. In silico modeling was generally predictive of in vivo findings and suggested that application of the AT during early consolidation results in destruction of newly-formed vascular tissue. Overall, no benefit was observed for the AT compared to conventional DO with the parameters employed in this study.

Effect of the accordion technique on bone regeneration during distraction osteogenesis: A computational study

BACKGROUND AND OBJECTIVE

Distraction osteogenesis (DO), a bone lengthening technique, is widely employed to treat congenital and acquired limb length discrepancies and large segmental bone defects. However, a major issue of DO is the prolonged consolidation phase (10-36 months) during which patients must wear a cumbersome external fixator. Attempts have been made to accelerate the healing process of DO by an alternating distraction and compression mode (so-called "accordion" technique or AT). However, it remains unclear how varied AT parameters affect DO outcomes and what the most effective AT mode is.

METHODS

Based on an experimentally-verified mechanobiological model, we performed a parametric analysis via in silico simulation of the bone regeneration process of DO under different AT modes, including combinations of varied application times (AT began at week 1-8 of the consolidation phase), durations (AT was used continuously for 1 week, 2 weeks or 4 weeks) and rates (distraction or compression at 0.25, 0.5, 0.75, and 1 mm/12 h). The control group had no AT applied during the consolidation phase.

RESULTS

Compared with the control group (no AT), AT applied at an early consolidation stage (e.g. week 1 of the consolidation phase) significantly enhanced bone formation and reduced the overall healing time. However, the effect of AT on bone healing was dependent on its duration and rate. Specifically, a moderate rate of AT (e.g. 0.5 mm/12 h) lasting for two weeks promoted blood perfusion recovery and bone regeneration, ultimately shortening the healing time. Conversely, over-high rates (e.g. 1 mm/12 h) and longer durations (e.g. 4 weeks) of AT adversely affected bone regeneration and blood perfusion recovery, thereby delaying bone bridging.

CONCLUSIONS

These results suggest that the therapeutic effects of AT on DO are highly dependent of the AT parameters of choice. Under appropriate durations and rates, the AT applied at an early consolidation phase is beneficial for blood recovery and bone regeneration. These results may provide a basis for selecting effective AT modes to accelerate consolidation and reduce the overall treatment period of DO.

Paediatric mandibular distraction: optimizing outcomes

PURPOSE OF REVIEW

The purpose of this review is to summarize current evidence surrounding the use of mandibular distraction osteogenesis in children and to highlight recent advances in our knowledge of this subject.

RECENT FINDINGS

Distraction osteogenesis of the mandible has gained in popularity since its initial description about 30 years ago. Its efficacy and safety have been well described. More recently, proper patient selection, technique modifications and long-term outcomes have been the subject of much discussion around this revolutionary technique.

SUMMARY

Distraction osteogenesis of the mandible is a powerful tool for surgeons. Technological advances and high-quality research have allowed for optimization of this technique within the field of craniomaxillofacial surgery.

Zinc-Based Biodegradable Materials for Orthopaedic Internal Fixation

Traditional inert materials used in internal fixation have caused many complications and generally require removal with secondary surgeries. Biodegradable materials, such as magnesium (Mg)-, iron (Fe)- and zinc (Zn)-based alloys, open up a new pathway to address those issues. During the last decades, Mg-based alloys have attracted much attention by researchers. However, the issues with an over-fast degradation rate and release of hydrogen still need to be overcome. Zn alloys have comparable mechanical properties with traditional metal materials, e.g., titanium (Ti), and have a moderate degradation rate, potentially serving as a good candidate for internal fixation materials, especially at load-bearing sites of the skeleton. Emerging Zn-based alloys and composites have been developed in recent years and in vitro and in vivo studies have been performed to explore their biodegradability, mechanical property, and biocompatibility in order to move towards the ultimate goal of clinical application in fracture fixation. This article seeks to offer a review of related research progress on Zn-based biodegradable materials, which may provide a useful reference for future studies on Zn-based biodegradable materials targeting applications in orthopedic internal fixation.

In vivo and in silico monitoring bone regeneration during distraction osteogenesis of the mouse femur

BACKGROUND AND OBJECTIVE

Distraction osteogenesis (DO) is a mechanobiological process of producing new bone by gradual and controlled distraction of the surgically separated bone segments. Mice have been increasingly used to study the role of relevant biological factors in regulating bone regeneration during DO. However, there remains a lack of in silico DO models and related mechano-regulatory tissue differentiation algorithms for mouse bone. This study sought to establish an in silico model based on in vivo experimental data to simulate the bone regeneration process during DO of the mouse femur.

METHODS

In vivo micro-CT, including time-lapse morphometry was performed to monitor the bone regeneration in the distraction gap. A 2D axisymmetric finite element model, with a geometry originating from the experimental data, was created. Bone regeneration was simulated with a fuzzy logic-based two-stage (distraction and consolidation) mechano-regulatory tissue differentiation algorithm, which was adjusted from that used for fracture healing based on our in vivo experimental data. The predictive potential of the model was further tested with varied distraction frequencies and distraction rates.

RESULTS

The computational simulations showed similar bone regeneration patterns to those observed in the micro-CT data from the experiment throughout the DO process. This consisted of rapid bone formation during the first 10 days of the consolidation phase, followed by callus reshaping via bone remodeling. In addition, the computational model predicted a faster and more robust bone healing response as the model's distraction frequency was increased, whereas higher or lower distraction rates were not conducive to healing.

CONCLUSIONS

This in silico model could be used to investigate basic mechanobiological mechanisms involved in bone regeneration or to optimize DO strategies for potential clinical applications.

Orthophosphate and alkaline phosphatase induced the formation of apatite with different multilayered structures and mineralization balance

Mineralized collagen is a natural organic-inorganic composite. The combination of organic collagen and inorganic apatite to form different nanostructures is the key to producing bone substitutes with biomechanical properties that are as identical to normal bone as possible. However, the formation of apatite with different nanostructures during collagen mineralization is unexplored. Here, pyrophosphate (Pyro-P), as an important hydrolysate of adenosine triphosphate in the body, was introduced to prepare mineralized collagen under the regulation of alkaline phosphatase (ALP) and orthophosphate (Ortho-P). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results showed that mineralized collagen, which combined with different crystallinities and multilayered structured apatite, was successfully prepared. A combination of ion chromatography (IC), Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD), and thermogravimetry (TG) analyses revealed the crucial role of Ortho-P in the formation of multilayered flower-shaped apatite with different crystallinities and in the maintenance of mineralization balance. Mineralization balance is of great significance for maintaining normal bone morphology during bone regeneration. Overall, our results provide a promising method to produce new bone substitute materials for the repair of large bone defects and a deeper insight into the mechanisms of biomineralization.