Is there a role for low intensity pulsed ultrasound (LIPUS) in delayed or nonunion following arthrodesis in foot and ankle surgery?

LIPUS as a potential strategy for periodontitis treatment: A review of the mechanisms

Periodontitis is a chronic inflammatory condition triggered by oral bacteria. A sustained inflammatory state in periodontitis could eventually destroy the alveolar bone. The key objective of periodontal therapy is to terminate the inflammatory process and reconstruct the periodontal tissues. The traditional Guided tissue regeneration (GTR) procedure has unstable results due to multiple factors such as the inflammatory environment, the immune response caused by the implant, and the operator's technique. Low-intensity pulsed ultrasound (LIPUS), as acoustic energy, transmits the mechanical signals to the target tissue to provide non-invasive physical stimulation. LIPUS has positive effects in promoting bone regeneration, soft-tissue regeneration, inflammation inhibition, and neuromodulation. LIPUS can maintain and regenerate alveolar bone during an inflammatory state by suppressing the expression of inflammatory factors. LIPUS also affects the cellular behavior of periodontal ligament cells (PDLCs), thereby protecting the regenerative potential of bone tissue in an inflammatory state. However, the underlying mechanisms of the LIPUS therapy are still yet to be summarized. The goal of this review is to outline the potential cellular and molecular mechanisms of periodontitis-related LIPUS therapy, as well as to explain how LIPUS manages to transmit mechanical stimulation into the signaling pathway to achieve inflammatory control and periodontal bone regeneration.

How to assess consolidation after foot and ankle arthrodesis with computed tomography. A systematic review

PURPOSES

Many studies have been performed that investigate consolidation after arthrodesis of foot and ankle joints. Consolidation in foot and ankle joints is best assessed by computed tomography (CT). However, no golden-standard methodology exists for radiological consolidation assessment from CT after ankle and foot arthrodesis. The aim of this review is to present an overview of the radiological methodologies for consolidation assessment, outcomes on reliability and validity and to advise which methodology should be used.

METHOD

Scientific databases were systematically searched. Eligible studies were studies that 1) performed foot or ankle arthrodesis, 2) mentioned radiological or CT follow-up in abstract, 3) performed postoperative CT in > 50% of patients. Two authors selected eligible studies and performed a risk of bias assessment with the COSMIN tool.

RESULTS

Risk of bias assessment showed that most studies (80%) were at high risk of bias due to poor methodology. The most popular method for consolidation assessment is by subjectively categorizing consolidation into consolidation groups, with a substantial reliability score. Another popular method is to calculate the fusion ratio and then apply a fusion threshold, to distinguish between fused and non-fused joints. This method had an excellent reliability score. In most studies a fusion threshold of 50% is used. However, four studies in this review showed that a 30% fusion threshold may by more valid.

CONCLUSION

Based on the results of this review we would advise to calculate fusion threshold and apply a 30% fusion threshold to distinguish fused from non-fused foot and ankle joints.

Can low-intensity pulsed ultrasound (LIPUS) accelerate bone healing after intramedullary screw fixation for proximal fifth metatarsal stress fractures? A retrospective study

Background

Intramedullary screw fixation is considered the standard treatment for proximal fifth metatarsal stress fractures. Low-intensity pulsed ultrasound (LIPUS) is a well-known bone-healing enhancement device. However, to the best of our knowledge, no clinical study has focused on the effect of LIPUS for postoperative bone union in proximal fifth metatarsal stress fractures. This study aimed to investigate the effect of LIPUS treatment after intramedullary screw fixation for proximal fifth metatarsal stress fractures.

Methods

Between January 2015 and March 2020, patients who underwent intramedullary screw fixation for proximal fifth metatarsal stress fractures were investigated retrospectively. All patients underwent intramedullary screw fixation using a headless compression screw with autologous bone grafts from the base of the fifth metatarsal. The time to restart running and return to sports, as well as that for radiographic bone union, were compared between groups with or without LIPUS treatment. LIPUS treatment was initiated within 3 weeks of surgery in all cases.

Results

Of the 101 ft analyzed, 57 ft were assigned to the LIPUS treatment group, and 44 ft were assigned to the non-LIPUS treatment group. The mean time to restart running and return to sports was 6.8 and 13.7 weeks in the LIPUS treatment group and was 6.2 and 13.2 weeks in the non-LIPUS treatment group, respectively. There were no significant differences in these parameters between groups. In addition, the mean time to radiographic bone union was not significantly different between the LIPUS treatment group (11.9 weeks) and the non-LIPUS treatment group (12.0 weeks). The rate of postoperative nonunion in the LIPUS treatment group was 0% (0/57), while that in the non-LIPUS treatment group was 4.5% (2/44). However, this difference was not statistically significant.

Conclusions

There were no statistically significant differences regarding the time to start running, return to sports, and radiographic bone union in patients with or without LIPUS treatment after intramedullary screw fixation for proximal fifth metatarsal stress fractures. Therefore, we cannot recommend the routine use of LIPUS to shorten the time to bone union after intramedullary screw fixation for proximal fifth metatarsal stress fractures.

Low intensity pulsed ultrasound (LIPUS) use for the management of instrumented, infected, and fragility non-unions: a systematic review and meta-analysis of healing proportions

Background

Non-union occurs in approximately 5 to 10% of fracture patients, with certain bones at greater risk of failing to heal. Non-unions have a significant impact on socioeconomic costs and the patients short and long-term quality of life. Low intensity pulsed ultrasound (LIPUS) is a non-invasive therapy for non-union treatment that can improve the long-term outcome. The purpose of this study is to summarize the available literature assessing LIPUS potential to improve the union rate in instrumented, infected, and fragility non-unions.

Methods

A literature search was conducted in the MEDLINE, EMBASE, and CINAHL databases for all relevant literature on the healing rates of LIPUS utilized in instrumented, infected, and fragility non-unions. Study characteristics were summarized for each of the included studies. The percentage of healed patients (healing rate), for instrumented, infected, and fragility fracture non-union patients were pooled from each included study.

Results

The literature search identified a total of 326 articles, while searching reference lists and grey literature identified an additional 3 articles. There was a total of 29 articles included in this review, with 20 articles included within the quantitative synthesis of healing rates. The most common design of included studies was case series (17 articles), followed by case reports (9 articles). Studies were primarily retrospective (18 studies), with an additional 10 prospective studies. Non-union healing rates were 82% (95% CI: 76 to 87%) in instrumented, 82% (95% CI: 70 to 95%) in infected, and 91% (95% CI: 87 to 95%) in fragility fracture patients with non-unions.

Conclusion

This study has provided a thorough overview of the current literature on LIPUS treatment for instrumented, infected, and fragility fracture non-unions. The healing rates for non-unions in these subgroups were comparable to healing rates observed with LIPUS use in general non-union literature. LIPUS treatment should be considered as a conservative non-surgical treatment option to potentially reduce the socioeconomic impact and improve the quality of life of these unfortunate patients.

Level of evidence

4 (systematic review of primarily case series data)

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04322-5.

The use of low intensity pulsed ultrasound in the foot and ankle

Low intensity pulsed ultrasound (LIPUS) therapy has demonstrated clinical effectiveness in achieving union in a variety of fracture situations.Few studies have investigated the effectiveness of LIPUS therapy in foot and ankle surgery.The overall rate of union in all published studies relating to the use of LIPUS in a variety of foot and ankle fracture and fusion situations is 95%.Some studies suggest lower healing rates (~ 67%) when LIPUS therapy is used to treat hindfoot fusion nonunion.A well-powered, high-quality, randomized controlled trial is needed to demonstrate the clinical and cost effectiveness of LIPUS therapy in foot and ankle surgery. Cite this article: EFORT Open Rev 2021;6:217-224. DOI: 10.1302/2058-5241.6.200045.

Fracture Nonunion Treated with Low-Intensity Pulsed Ultrasound and Monitored with Ultrasonography: A Feasibility Study

The positive effect of low-intensity pulsed ultrasound (LIPUS) on bone fracture healing has been proved. However, during the period of LIPUS therapy, it is undetermined whether LIPUS promotes the formation of heterotopic ossification (HO), which usually occurs in muscle tissues after trauma such as bone fracture and spinal cord injury. Here, we used 6-week LIPUS therapy in a 42-year-old Chinese male patient with a fracture nonunion in combination with ultrasonography for monitoring fracture healing and HO formation. After the LIPUS therapy, the mineralized bone formation in the area of defect of the distal tibia was presented in an ultrasound image, which was consistent with the outcome of plain radiography showing callus formation and the blurred fracture line in the area exposed to LIPUS. In addition, ultrasound images revealed no evidence of HO development within soft tissues during the period of LIPUS therapy. This study suggests that ultrasonography is a potential tool to guarantee the performance of LIPUS therapy with monitoring HO formation. Easy to use, the integration of the handheld ultrasound scanner and the ultrasonic therapeutic apparatus is entirely dedicated to help orthopedists make high-quality care and diagnosis.

Can low intensity pulsed ultrasound (LIPUS) be used as an alternative to revision surgery for patients with non-unions following fracture fixation?

BACKGROUND

Non-union is a significant complication of fracture fixation surgery, and can negatively impact a patient's quality of life. Low intensity pulsed ultrasound (LIPUS) has been used to treat delayed or non-unions previously in the literature. The aim of this study was to determine the success rate of LIPUS treatment in patients with chronic fracture non-unions, and to establish the effect of systemic or local factors on its success.

METHODS

This was a retrospective, observational study which included all patients undergoing LIPUS treatment in a single institution. Patients deemed suitable for LIPUS underwent treatment for a period of 6 months from initiation. They were followed up with sequential radiographs to assess union at intervals of 6 weeks, 3 months, 6 months and 1 year. LIPUS treatment was considered to be successful when patients achieved clinical and radiological union, without the need for revision surgery.

RESULTS

A total of 46 patients were included in the study; 8 were lost to follow - up, leaving 38 patients for the final analysis. The mean age of patients was 47.03 ± 19.7 with a male to female ratio of 1.2:1. Union was achieved in 57.89%; the rest underwent revision surgery. There was no significant association between outcomes after LIPUS treatment and patients' age, gender, smoking status or type of non-union. Patients with a small inter-fragment bone gap were more likely to have a successful outcome after LIPUS (p = 0.041). Time to treatment did not have a statistically significant impact on outcomes after LIPUS. Interestingly, all 6 patients with diabetes in the study managed to achieve union after LIPUS.

CONCLUSIONS

This study demonstrates that LIPUS is not successful in a large proportion of patients with established fracture non-unions. However, it does represent a low risk treatment modality as an alternative to revision surgery, especially for patients with diabetes who have a small inter - fragment bone gap. More research in the form of large randomised controlled trials needs to be carried out to further assess the role of LIPUS in the treatment of non-unions.

Low-intensity Pulsed Ultrasound regulates alveolar bone homeostasis in experimental Periodontitis by diminishing Oxidative Stress

Periodontitis is a widespread oral disease that results in the loss of alveolar bone. Low-intensity pulsed ultrasound (LIPUS), which is a new therapeutic option, promotes alveolar bone regeneration in periodontal bone injury models. This study investigated the protective effect of LIPUS on oxidative stress in periodontitis and the mechanism underlying this process.

Methods: An experimental periodontitis model was induced by administering a ligature. Immunohistochemistry was performed to detect the expression levels of oxidative stress, osteogenic, and osteoclastogenic markers in vivo. Cell viability and osteogenic differentiation were analyzed using the Cell Counting Kit-8, alkaline phosphatase, and Alizarin Red staining assays. A reactive oxygen species assay kit, lipid peroxidation MDA assay kit, and western blotting were used to determine oxidative stress status in vitro. To verify the role of nuclear factor erythroid 2-related factor 2 (Nrf2), an oxidative regulator, during LIPUS treatment, the siRNA technique and Nrf2^-/- mice were used. The PI3K/Akt inhibitor LY294002 was utilized to identify the effects of the PI3K-Akt/Nrf2 signaling pathway.

Results: Alveolar bone resorption, which was experimentally induced by periodontitis in vivo, was alleviated by LIPUS via activation of Nrf2. Oxidative stress, induced via H₂O₂ treatment in vitro, inhibited cell viability and suppressed osteogenic differentiation. These effects were also alleviated by LIPUS treatment via Nrf2 activation. Nrf2 silencing blocked the antioxidant effect of LIPUS by diminishing heme oxygenase-1 expression. Nrf2^-/- mice were susceptible to ligature-induced periodontitis, and the protective effect of LIPUS on alveolar bone dysfunction was weaker in these mice. Activation of Nrf2 by LIPUS was accompanied by activation of the PI3K/Akt pathway. The oxidative defense function of LIPUS was inhibited by exposure to LY294002 in vitro.

Conclusions: These results demonstrated that LIPUS regulates alveolar bone homeostasis in periodontitis by attenuating oxidative stress via the regulation of PI3K-Akt/Nrf2 signaling. Thus, Nrf2 plays a pivotal role in the protective effect exerted by LIPUS against ligature-induced experimental periodontitis.