Enhancement of Bone-Healing by Low-Intensity Pulsed Ultrasound: A Systematic Review

Reconstructed bone fracture 28 years after hip rotationplasty for Ewing sarcoma: A case report

Hip rotationplasty is a surgical method used to treat malignant tumors of the proximal femur. A 52-year-old woman, who underwent hip rotationplasty for Ewing sarcoma of the proximal left femur at the age of 24, fell and hit the left buttock. The patient was then admitted to the Department of Orthopedic Surgery, Graduate School of Medicine, University of the Ryukyus. Radiography and computed tomography (CT) revealed a comminuted fracture of the reconstructed bone distally. The patient underwent open reduction and internal fixation (ORIF) and external fixator. External fixation was removed 1 month after the surgery. At two years after surgery, at the latest follow-up, bone union was confirmed by 3-dimensional CT. The combination of ORIF and temporal external fixation was effective for the reconstructed bone fractures after hip rotationplasty.

Low-intensity pulsed ultrasound promotes mesenchymal stem cell transplantation-based articular cartilage regeneration via inhibiting the TNF signaling pathway

BACKGROUND

Mesenchymal stem cell (MSC) transplantation therapy is highly investigated for the regenerative repair of cartilage defects. Low-intensity pulsed ultrasound (LIPUS) has the potential to promote chondrogenic differentiation of MSCs. However, its underlying mechanism remains unclear. Here, we investigated the promoting effects and mechanisms underlying LIPUS stimulation on the chondrogenic differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) and further evaluated its regenerative application value in articular cartilage defects in rats.

METHODS

LIPUS was applied to stimulate cultured hUC-MSCs and C28/I2 cells in vitro. Immunofluorescence staining, qPCR analysis, and transcriptome sequencing were used to detect mature cartilage-related markers of gene and protein expression for a comprehensive evaluation of differentiation. Injured articular cartilage rat models were established for further hUC-MSC transplantation and LIPUS stimulation in vivo. Histopathology and H&E staining were used to evaluate the repair effects of the injured articular cartilage with LIPUS stimulation.

RESULTS

The results showed that LIPUS stimulation with specific parameters effectively promoted the expression of mature cartilage-related genes and proteins, inhibited TNF-α gene expression in hUC-MSCs, and exhibited anti-inflammation in C28/I2 cells. In addition, the articular cartilage defects of rats were significantly repaired after hUC-MSC transplantation and LIPUS stimulation.

CONCLUSIONS

Taken together, LIPUS stimulation could realize articular cartilage regeneration based on hUC-MSC transplantation due to the inhibition of the TNF signaling pathway, which is of clinical value for the relief of osteoarthritis.

Effects of low-intensity pulsed ultrasound on the infrapatellar fat pad in knee osteoarthritis: a randomized, double blind, placebo-controlled trial

[Purpose] We investigated the effects of low-intensity pulsed ultrasound (LIPUS) irradiation of the infrapatellar fat pad (IFP) combined with therapeutic exercise for management of knee osteoarthritis (knee OA). [Participants and Methods] The study included 26 patients with knee OA, who were randomized into the LIPUS group (patients underwent LIPUS + therapeutic exercise) and the therapeutic exercise group (patients underwent sham LIPUS + therapeutic exercise). We measured changes in the patellar tendon-tibial angle (PTTA) and in IFP thickness, IFP gliding, and IFP echo intensity after 10 treatment sessions to determine the effects of the aforementioned interventions. We additionally recorded changes in the visual analog scale, Timed Up and Go Test, the Western Ontario and McMaster Universities Osteoarthritis Index, and Kujala scores, as well as range of motion in each group at the same end-point. [Results] Compared with patients in the therapeutic exercise group, those in the LIPUS group showed significant post-treatment improvements in PTTA, VAS, and Kujala scores, as well as in range of motion. [Conclusion] The combined use of LIPUS irradiation of the IFP and therapeutic exercise is a safe and effective modality to reduce IFP swelling, relieve pain, and improve function in patients with knee OA.

LIPUS accelerates bone regeneration via HDAC6-mediated ciliogenesis

Delayed fracture union and nonunion are common complications of fracture encountered, while Low-intensity pulsed ultrasound (LIPUS) can stimulate bone regeneration. Still, the underlying mechanism of LIPUS on bone regeneration has been poorly understood, which resulted in varied outcomes in the clinic. Therefore, figuring out the mechanism of LIPUS on bone regeneration can lay the foundation for better use of LIPUS in clinical bone regenerative therapies. In this study, we created transgenic mice to reveal the relationship between the periosteal cells' fate and the number of ciliated cells under the LIPUS stimulation. In vitro, we isolated the periosteal cell and aim to figure out the relationship between LIPUS and HDAC6-mediated ciliogenesis and find out a potential target for LIPUS-based bone regeneration strategies. The results showed that LIPUS promoted femoral bone defect regeneration and enhanced osteogenic differentiation of Prrx1⁺ cells. However, these pro-effects were significantly weakened when the Prrx1⁺ cell's primary cilia were knocked down. Besides, LIPUS stimulated the formation of Prrx1⁺ cells' primary cilia in the bone defect microenvironment. In vitro, the results supported that LIPUS enhanced the osteogenic differentiation of Prrx1⁺ cells through HDAC6-mediated ciliogenesis. In conclusion, λ LIPUS could promote the osteogenic differentiation of Prrx1⁺ cells to stimulate bone regeneration and inhibit the expression of HDAC6 to increase the prevalence of primary cilia in Prrx1⁺ cells. LIPUS could enhance the osteogenic differentiation of Prrx1⁺ cells mainly through HDAC6-mediated ciliogenesis.

Younger age is a significant factor for poorer adherence in fracture patients who received low-intensity pulsed ultrasound: A retrospective study

BACKGROUND

The factors for poor adherence to therapy in patients with postoperative fracture who are treated with low-intensity pulsed ultrasound remain unknown. Therefore, we designed a retrospective cohort study to determine the various factors for poorer adherence to therapy in patients with postoperative fracture who were treated with low-intensity pulsed ultrasound therapy.

METHODS

We retrospectively analyzed the data of postoperative patients who underwent low-intensity pulsed ultrasound after fracture surgery from January 2010 to May 2019. The patients were categorized into two groups as follows: group G, including those with a good adherence rate (>72%), and group P, including those with a poor adherence rate (<72%). Factors, such as age, sex, how the rental cost of low-intensity pulsed ultrasound was paid (by the patients themselves or by the insurance company), living (alone or with someone), insurance claim item (fractures within 3 weeks after osteosynthesis or delayed or non-union fractures), low-intensity pulsed ultrasound device-type (earlier- or next-generation), duration of low-intensity pulsed ultrasound use, fracture site (upper or lower limb), frequency of hospital visits (regular or irregular), and employment status (employed/unemployed) were compared between groups G and P.

RESULTS

In total, 96 patients (74 and 22 patients in groups G and P, respectively) who underwent low-intensity pulsed ultrasound were included in the study. Univariate analysis revealed that younger patients (P < 0.001) and patients who did not regularly visit the hospital (P = 0.024) were more likely to have poorer adherence to therapy. Multiple logistic regression analysis revealed that age was the only independent, pertinent factor for poorer adherence to therapy (odds ratio, 8.570; 95% confidence interval, 2.770-26.50; P < 0.001), with a cutoff value of 41 years.

CONCLUSIONS

Younger age is a significant factor for poorer adherence in patients undergoing low-intensity pulsed ultrasound therapy.

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.

Low-intensity pulsed ultrasound does not promote bone healing and functional recovery after open wedge high tibial osteotomy

Aims

To evaluate whether low-intensity pulsed ultrasound (LIPUS) accelerates bone healing at osteotomy sites and promotes functional recovery after open-wedge high tibial osteotomy (OWHTO).

Methods

Overall, 90 patients who underwent OWHTO without bone grafting were enrolled in this nonrandomized retrospective study, and 45 patients treated with LIPUS were compared with 45 patients without LIPUS treatment in terms of bone healing and functional recovery postoperatively. Clinical evaluations, including the pain visual analogue scale (VAS) and Japanese Orthopaedic Association (JOA) score, were performed preoperatively as well as six weeks and three, six, and 12 months postoperatively. The progression rate of gap filling was evaluated using anteroposterior radiographs at six weeks and three, six, and 12 months postoperatively.

Results

The pain VAS and JOA scores significantly improved after OWHTO in both groups. Although the LIPUS group had better pain scores at six weeks and three months postoperatively, there were no significant differences in JOA score between the groups. The lateral hinge united at six weeks postoperatively in 34 (75.6%) knees in the control group and in 33 (73.3%) knees in the LIPUS group. The progression rates of gap filling in the LIPUS group were 8.0%, 15.0%, 27.2%, and 46.0% at six weeks and three, six, and 12 months postoperatively, respectively, whereas in the control group at the same time points they were 7.7%, 15.2%, 26.3%, and 44.0%, respectively. There were no significant differences in the progression rate of gap filling between the groups.

Conclusion

The present study demonstrated that LIPUS did not promote bone healing and functional recovery after OWHTO with a locking plate. The routine use of LIPUS after OWHTO was not recommended from the results of our study. Cite this article: Bone Jt Open 2022;3(11):885–893.

A novel application of neural networks to identify potentially effective combinations of biologic factors for enhancement of bone fusion/repair

INTRODUCTION

The use of biologic adjuvants (orthobiologics) is becoming commonplace in orthopaedic surgery. Among other applications, biologics are often added to enhance fusion rates in spinal surgery and to promote bone healing in complex fracture patterns. Generally, orthopaedic surgeons use only one biomolecular agent (ie allograft with embedded bone morphogenic protein-2) rather than several agents acting in concert. Bone fusion, however, is a highly multifactorial process and it likely could be more effectively enhanced using biologic factors in combination, acting synergistically. We used artificial neural networks, trained via machine learning on experimental data on orthobiologic interventions and their outcomes, to identify combinations of orthobiologic factors that potentially would be more effective than single agents. This use of machine learning applied to orthobiologic interventions is unprecedented.

METHODS

Available data on the outcomes associated with various orthopaedic biologic agents, electrical stimulation, and pulsed ultrasound were curated from the literature and assembled into a form suitable for machine learning. The best among many different types of neural networks was chosen for its ability to generalize over this dataset, and that network was used to make predictions concerning the expected efficacy of 2400 medically feasible combinations of 9 different agents and treatments.

RESULTS

The most effective combinations were high in the bone-morphogenic proteins (BMP) 2 and 7 (BMP2, 15mg; BMP7, 5mg), and in osteogenin (150ug). In some of the most effective combinations, electrical stimulation could substitute for osteogenin. Some other effective combinations also included bone marrow aspirate concentrate. BMP2 and BMP7 appear to have the strongest pairwise linkage of the factors analyzed in this study.

CONCLUSIONS

Artificial neural networks are powerful forms of artificial intelligence that can be applied readily in the orthopaedic domain, but neural network predictions improve along with the amount of data available to train them. This study provides a starting point from which networks trained on future, expanded datasets can be developed. Yet even this initial model makes specific predictions concerning potentially effective combinatorial therapeutics that should be verified experimentally. Furthermore, our analysis provides an avenue for further research into the basic science of bone healing by demonstrating agents that appear to be linked in function.

Latest Advances in the Use of Therapeutic Focused Ultrasound in the Treatment of Pancreatic Cancer

Traditional oncological interventions have failed to improve survival for pancreatic cancer patients significantly. Novel treatment modalities able to release cancer-specific antigens, render immunologically "cold" pancreatic tumours "hot" and disrupt or reprogram the pancreatic tumour microenvironment are thus urgently needed. Therapeutic focused ultrasound exerts thermal and mechanical effects on tissue, killing cancer cells and inducing an anti-cancer immune response. The most important advances in therapeutic focused ultrasound use for initiation and augmentation of the cancer immunity cycle against pancreatic cancer are described. We provide a comprehensive review of the use of therapeutic focused ultrasound for the treatment of pancreatic cancer patients and describe recent studies that have shown an ultrasound-induced anti-cancer immune response in several tumour models. Published studies that have investigated the immunological effects of therapeutic focused ultrasound in pancreatic cancer are described. This article shows that therapeutic focused ultrasound has been deemed to be a safe technique for treating pancreatic cancer patients, providing pain relief and improving survival rates in pancreatic cancer patients. Promotion of an immune response in the clinic and sensitisation of tumours to the effects of immunotherapy in preclinical models of pancreatic cancer is shown, making it a promising candidate for use in the clinic.

Current Modalities for Fracture Healing Enhancement

Previously, most fractures have been treated through bone reduction and immobilization. With an increase in the patients' need for an early return to their normal function, development in surgical techniques and materials have accelerated. However, delayed union or non-union of the fracture site sometimes inhibits immediate return to normal life. To enhance fracture healing, diverse materials and methods have been developed. This is a review on the current modalities of fracture healing enhancement, which aims to provide a comprehensive knowledge regarding fracture healing for researchers and health practitioners.

Multiscale modeling of bone tissue mechanobiology

Mechanical environment has a crucial role in our organism at the different levels, ranging from cells to tissues and our own organs. This regulatory role is especially relevant for bones, given their importance as load-transmitting elements that allow the movement of our body as well as the protection of vital organs from load impacts. Therefore bone, as living tissue, is continuously adapting its properties, shape and repairing itself, being the mechanical loads one of the main regulatory stimuli that modulate this adaptive behavior. Here we review some key results of bone mechanobiology from computational models, describing the effect that changes associated to the mechanical environment induce in bone response, implant design and scaffold-driven bone regeneration.

Fracture Nonunions and Delayed Unions Treated With Low-Intensity Pulsed Ultrasound Therapy: A Clinical Series

The incidence of nonunion of fractures has been steadily rising owing to improved life expectancy following severe injuries along with rising cases of polytrauma. Once a nonunion is established, the chances of spontaneous healing are deemed to be quite low. Fracture nonunion continues to be a challenge in clinical practice with nonunions having a considerable impact on patient’s quality of life causing both functional and psychosocial disability. Low-Intensity Pulsed Ultrasound (LIPUS) therapy is being projected as a viable and non-interventional alternative to surgical management of nonunions and delayed unions. LIPUS therapy is being widely recommended as a standalone treatment option for the treatment of established nonunions and delayed unions as it is believed to promote healing in all phases of fracture healing viz., inflammatory, intramembranous ossification, chondrogenesis, endochondral ossification and remodelling. In the current scenario of varying results and unclear clinical role of LIPUS therapy, we present a prospective case series of fracture nonunions and delayed unions treated with LIPUS therapy at a large District General Hospital. 

The Management of Acute Lumbar Stress Reactions of the Pedicle and Pars in Professional Athletes Playing Collision Sports

Acute stress reactions in the lumbar spine most commonly occur in athletes at the pars interarticularis followed by the pedicle. These reactions occur as a result of repetitive microtrauma from supraphysiological loads applied to the lumbar spine. Characteristic motions such as trunk extension and twisting are also thought to play a role and may be sport-specific. Other risk factors include increased lumbar lordosis, hamstring and thoracolumbar fascia tightness, and abdominal weakness. On physical examination, pain is typically reproduced with lumbar hyperextension. Currently, magnetic resonance imaging or nuclear imaging remain the most sensitive imaging modalities for identifying acute lesions. In the elite athlete, management of these conditions can be challenging, particularly in those playing collision sports such as American football, hockey, or rugby. Nonoperative treatment is the treatment of choice with rehabilitation programs focused on pain-free positioning and progressive strengthening. Operative treatment is rare, but may be warranted for patients symptomatic for >12 months. Specialized diagnosis protocols as well as treatment and return to play guidelines from 4 physicians treating elite athletes playing collision sports are presented and reviewed.

Bone Healing and Inflammation: Principles of Fracture and Repair

Bones comprise a significant percentage of human weight and have important physiologic and structural roles. Bone remodeling occurs when healthy bone is renewed to maintain bone strength and maintain calcium and phosphate homeostasis. It proceeds through four phases: (1) cell activation, (2) resorption, (3) reversal, and (4) bone formation. Bone healing, on the other hand, involves rebuilding bone following a fracture. There are two main types of bone healing, primary and secondary. Inflammation plays an integral role in both bone remodeling and healing. Therefore, a tightly regulated inflammatory response helps achieve these two processes, and levels of inflammation can have detrimental effects on bone healing. Other factors that significantly affect bone healing are inadequate blood supply, biomechanical instability, immunosuppression, and smoking. By understanding the different mechanisms of bone healing and the factors that affect them, we may have a better understanding of the underlying principles of bony fixation and thereby improve patient care.

Rehabilitation of the Canine Forelimb

The goal of rehabilitation is to restore function and mobility and reduce pain associated with chronic disease. In human medicine, physical therapy is standard of care for acute and chronic injuries and an integral component of postoperative recovery. Although there is a dearth of evidence-based veterinary medical studies in rehabilitation therapy and modalities for forelimb injuries in dogs, some extrapolation from human medicine can be made and applied. When developing a rehabilitation and therapeutic plan, the biomechanics of the affected limb and timeline of tissue healing of the target tissue and/or joint are important to consider.

Low-intensity pulsed ultrasound attenuates replacement root resorption of avulsed teeth stored in dry condition in dogs

This study aimed to investigate the effects of low-intensity pulsed ultrasound (LIPUS) on replacement root resorption after replantation of avulsed teeth stored in a dry condition in dogs. A total of 73 premolar roots from four male mongrel dogs were intentionally avulsed with forceps and divided into four groups—HN, HL, DN, and DL—according to storage conditions and whether or not they received LIPUS treatment. Thirty-eight roots were kept in Hanks’ Balanced Salt Solution for 30 min (HN and HL groups), whereas the remaining 35 roots were left to dry in the air for an hour (DN and DL groups) prior to replantation. Following replantation, the roots in the HL and DL groups (21 and 18 roots, respectively) received a 20-min daily LIPUS treatment for 2 weeks. The animals were euthanized 4 weeks after the operation. Micro-computed tomography images were acquired for each root and the amount of replacement root resorption was measured three-dimensionally. Histological assessments were also carried out. There was significantly less replacement root resorption for the roots in the DL group compared to the DN group (p < 0.01). Histological findings in the DN group demonstrated evident replacement root resorption, whereas the DL group revealed less severe resorption compared to the DN group. Within the limitations, these results suggest that LIPUS could attenuate the replacement resorption of avulsed teeth stored in a dry condition, thereby improving their prognosis.

Piezo1 channel activation in response to mechanobiological acoustic radiation force in osteoblastic cells

Mechanobiological stimuli, such as low-intensity pulsed ultrasound (LIPUS), have been shown to promote bone regeneration and fresh fracture repair, but the fundamental biophysical mechanisms involved remain elusive. Here, we propose that a mechanosensitive ion channel of Piezo1 plays a pivotal role in the noninvasive ultrasound-induced mechanical transduction pathway to trigger downstream cellular signal processes. This study aims to investigate the expression and role of Piezo1 in MC3T3-E1 cells after LIPUS treatment. Immunofluorescence analysis shows that Piezo1 was present on MC3T3-E1 cells and could be ablated by shRNA transfection. MC3T3-E1 cell migration and proliferation were significantly increased by LIPUS stimulation, and knockdown of Piezo1 restricted the increase in cell migration and proliferation. After labeling with Fluo-8, MC3T3-E1 cells exhibited fluorescence intensity traces with several high peaks compared with the baseline during LIPUS stimulation. No obvious change in the fluorescence intensity tendency was observed after LIPUS stimulation in shRNA-Piezo1 cells, which was similar to the results in the GsMTx4-treated group. The phosphorylation ratio of ERK1/2 in MC3T3-E1 cells was significantly increased (P < 0.01) after LIPUS stimulation. In addition, Phalloidin-iFluor-labeled F-actin filaments immediately accumulated in the perinuclear region after LIPUS stimulation, continued for 5 min, and then returned to their initial levels at 30 min. These results suggest that Piezo1 can transduce LIPUS-induced mechanical signals into intracellular calcium. The influx of Ca²⁺ serves as a second messenger to activate ERK1/2 phosphorylation and perinuclear F-actin filament polymerization, which regulate the proliferation of MC3T3-E1 cells.

Evaluation and management of atypical femoral fractures: an update of current knowledge

Atypical femoral fractures are often attributed to the use of anti-resorptive medications such as bisphosphonates (BP). Whilst they have proven effects on fragility fracture prevention, clinical and laboratory evidence is evolving linking BP-related suppression of bone remodelling to the development of atypical stress-related sub-trochanteric fractures (Shane et al. in JBMR 29:1-23, 2014; Odvina et al. in JCEM 90:1294-301, 2005; Durchschlag et al. in JBMR 21(10):1581-1590, 2006; Donnelly et al. in JBMR 27:672-678, 2012; Mashiba et al. in Bone 28(5):524-531, 2001; Dell et al. in JBMR 27(12):2544-2550, 2012; Black et al. in Lancet 348:1535-1541, 1996; Black et al. in NEJM 356:1809-1822, 2007; Black et al. in JAMA 296:2927-2938, 2006; Schwartz et al. in JBMR 25:976-82, 2010). Injuries may present asymptomatically or with prodromal thigh pain and most can be successfully managed with cephalomedullary nailing and discontinuation of BP therapy. Such injuries exhibit a prolonged time to fracture union with high rates of non-union and metal-work failure when compared to typical subtrochanteric osteoporotic femoral fractures. Despite emerging literature on AFFs, their management continues to pose a challenge to the orthopaedic and extended multi-disciplinary team. The purpose of this review includes evaluation of the current evidence supporting the management of AFFs, clinical and radiological features associated with their presentation and a review of reported surgical strategies to treat and prevent these devastating injures.

Evaluating the Effectiveness of Biophysical Methods of Osteogenesis Stimulation: Review

Background. Stimulation of osteogenesis (SO) by biophysical methods has been widely used in practice to accelerate healing or stimulate the healing of fractures with non-unions, since the middle of the XIX century. SO can be carried out by direct current electrostimulation, or indirectly by low-intensity pulsed ultrasound, capacitive electrical coupling stimulation, and pulsed electromagnetic field stimulation. SO simulates natural physiological processes: in the case of electrical stimulation, it changes the electromagnetic potential of damaged cell tissues in a manner similar to normal healing processes, or in the case of low-intensity pulsed ultrasound, it produces weak mechanical effects on the fracture area. SO increases the expression of factors and signaling pathways responsible for tissue regeneration and bone mineralization and ultimately accelerates bone union.The purpose of this review was to present the most up-to-date data from laboratory and clinical studies of the effectiveness of SO.Material and Methods. The results of laboratory studies and the final results of metaanalyses for each of the four SO methods published from 1959 to 2020 in the PubMed, EMBASE, and eLibrary databases are reviewed.Conclusion. The use of SO effectively stimulates the healing of fractures with the correct location of the sensors, compliance with the intensity and time of exposure, as well as the timing of use for certain types of fractures. In case of non-union or delayed union of fractures, spondylodesis, arthrodesis, preference should be given to non-invasive methods of SO. Invasive direct current stimulation can be useful for non-union of long bones, spondylodesis with the risk of developing pseudoarthrosis.

Evaluating the Effectiveness of Biophysical Methods of Osteogenesis Stimulation: Review

Background. Stimulation of osteogenesis (SO) by biophysical methods has been widely used in practice to accelerate healing or stimulate the healing of fractures with non-unions, since the middle of the XIX century. SO can be carried out by direct current electrostimulation, or indirectly by low-intensity pulsed ultrasound, capacitive electrical coupling stimulation, and pulsed electromagnetic field stimulation. SO simulates natural physiological processes: in the case of electrical stimulation, it changes the electromagnetic potential of damaged cell tissues in a manner similar to normal healing processes, or in the case of low-intensity pulsed ultrasound, it produces weak mechanical effects on the fracture area. SO increases the expression of factors and signaling pathways responsible for tissue regeneration and bone mineralization and ultimately accelerates bone union.The purpose of this review was to present the most up-to-date data from laboratory and clinical studies of the effectiveness of SO.Material and Methods. The results of laboratory studies and the final results of metaanalyses for each of the four SO methods published from 1959 to 2020 in the PubMed, EMBASE, and eLibrary databases are reviewed.Conclusion. The use of SO effectively stimulates the healing of fractures with the correct location of the sensors, compliance with the intensity and time of exposure, as well as the timing of use for certain types of fractures. In case of non-union or delayed union of fractures, spondylodesis, arthrodesis, preference should be given to non-invasive methods of SO. Invasive direct current stimulation can be useful for non-union of long bones, spondylodesis with the risk of developing pseudoarthrosis.

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.

Scapular Spine Stress Fracture Following Reverse Total Shoulder Arthroplasty: Successful Management with Low-Intensity Pulsed Ultrasound

Scapular spine stress fractures are a rare but well-recognised complication following reverse total shoulder arthroplasty (RTSA). They present a challenge with no consensus on management. Both operative fixation and conservative measures are associated with high rates of mal- or non-union and decreased functional outcomes. 

We present the case of a 60-year-old female, who presented with a scapular spine fracture one year following RTSA. Treatment consisted of initial immobilisation, physiotherapy and the application of a portable low-intensity pulsed ultrasound (LIPUS) system (EXOGENÒ Ultrasound Bone Healing System, Bioventus, Durham NC, Netherlands). Following a three-month treatment course, there was a significant improvement in patient-reported pain and functional scores (Oxford Shoulder Score from 5/48 to 38/48). Sequential radiographic imaging confirmed fracture union. Clinicians may consider the use of LIPUS therapy as a potential adjunctive treatment modality to promote the union of scapular spine stress fractures following RTSA.

Extracorporeal shock wave therapy accelerates endochondral ossification and fracture healing in a rat femur delayed-union model

Extracorporeal shock wave therapy (ESWT) has been demonstrated to accelerate bone healing; however, the mechanism underlying ESWT-induced bone regeneration has not been fully elucidated. This study aimed to examine the effects of ESWT and the process of fracture healing. A rat model of femur delayed-union was established by cauterizing the periosteum. ESWT treatment at the fracture site was performed 2 weeks after the operation and the site was radiographically and histologically evaluated at weeks 4, 6, and 8. The bone union rate and radiographic score of the ESWT group were significantly higher than those of the control group at 8 weeks. Histological evaluation revealed enhanced endochondral ossification at the fracture site. The effects of ESWT on ATDC5 cells were examined in vitro. ESWT promoted chondrogenic differentiation without inhibiting the proliferation of ATDC5 cells. ESWT may induce significant bone healing by promoting endochondral ossification at the fracture site.

Impact of COVID-19 on orthopaedic care: a call for nonoperative management

BACKGROUND

Surgical specialties face unique challenges caused by SARS-COV-2 (COVID-19). These disruptions will call on clinicians to have greater consideration for non-operative treatment options to help manage patient symptoms and provide therapeutic care in lieu of the traditional surgical management course of action. This study aimed to summarize the current guidance on elective surgery during the COVID-19 pandemic, assess how this guidance may impact orthopaedic care, and review any recommendations for non-operative management in light of elective surgery disruptions.

METHODS

A systematic search was conducted, and included guidance were categorized as either "Selective Postponement" or "Complete Postponement" of elective surgery. Selective postponement was considered as guidance that suggested elective cases should be evaluated on a case-by-case basis, whereas complete postponement suggested that all elective procedures be postponed until after the pandemic, with no case-by-case consideration. In addition, any statements regarding conservative/non-operative management were summarized when provided by included reports.

RESULTS

A total of 11 reports from nine different health organizations were included in this review. There were seven (63.6%) guidance reports that suggested a complete postponement of non-elective surgical procedures, whereas four (36.4%) reports suggested the use of selective postponement of these procedures. The guidance trends shifted from selective to complete elective surgery postponement occurred throughout the month of March. The general guidance provided by these reports was to have an increased consideration for non-operative treatment options whenever possible and safe. As elective surgery begins to re-open, non-operative management will play a key role in managing the surgical backlog caused by the elective surgery shutdown.

CONCLUSION

Global guidance from major medical associations are in agreement that elective surgical procedures require postponement in order to minimize the risk of COVID-19 spread, as well as increase available hospital resources for managing the influx of COVID-19 patients. It is imperative that clinicians and patients consider non-operative, conservative treatment options in order to manage conditions and symptoms until surgical management options become available again, and to manage the increased surgical waitlists caused by the elective surgery shutdowns.

Mechanotransduction in osteogenesis

Bone is one of the most highly adaptive tissues in the body, possessing the capability to alter its morphology and function in response to stimuli in its surrounding environment. The ability of bone to sense and convert external mechanical stimuli into a biochemical response, which ultimately alters the phenotype and function of the cell, is described as mechanotransduction. This review aims to describe the fundamental physiology and biomechanisms that occur to induce osteogenic adaptation of a cell following application of a physical stimulus. Considerable developments have been made in recent years in our understanding of how cells orchestrate this complex interplay of processes, and have become the focus of research in osteogenesis. We will discuss current areas of preclinical and clinical research exploring the harnessing of mechanotransductive properties of cells and applying them therapeutically, both in the context of fracture healing and de novo bone formation in situations such as nonunion.

Cite this article: Bone Joint Res 2019;9(1):1–14.

Experience of an isolated use of low-intensity pulsed ultrasound therapy on fracture healing in established non-unions: a prospective case series

Fracture non-unions are responsible for approximately 5% of cases, with low expectation of spontaneous healing thereafter. The fractures that heal without complications can take months to heal completely. An ultrasound, typically at low intensities (0.5-50 mW/cm²), serves a diagnostic purpose, whereas at higher intensities (0.2-100 W/cm²), its role becomes more therapeutic by generating heat energy. Low-intensity pulsed ultrasound (LIPUS) is frequently used to stimulate or to accelerate fracture healing. We present a prospective review of fracture non-unions treated with low-intensity pulsed ultrasound (LIPUS). We enrolled 66 patients during August 2016 and December 2018, 38 males and 28 females; age range 19-85 years (average 49.2 years). All these patients were followed up to minimum 6 months. The average time of referral post-treatment for fractures was 8.2 months (range 6-18 months). Four patients were excluded due to various reasons. 39 out of 62 fractures showed successful healing with symptom improvement and callus formation with 67% success rate. In this case series, we noted LIPUS therapy failure in the post-ORIF scaphoid fracture and post-ankle joint fusion non-union. We did not observe any influence of a medical condition such as diabetes mellitus, osteoporosis or personal habits like smoking. The LIPUS therapy appears to have influence on bone healing, depending on the onset of therapy, fracture type and the approach to fracture care. In this case series, the compliant group showed 67% successful outcome.

The Adenosine A2A Receptor Agonist Accelerates Bone Healing and Adjusts Treg/Th17 Cell Balance through Interleukin 6

The aim of this study was to explore the effect of adenosine A2A receptor agonists on fracture healing and the regulation of the immunity system after bone fracture. We implanted fibrin gel containing adenosine A2A receptor agonist CGS 21680/inhibitor ZM 241385/saline locally in rat tibial fracture models, finding that the adenosine A2A receptor agonist could promote fracture healing. At the same time, the adenosine A2A receptor agonist decreased the level of IL-6 in blood and the fracture area, increased Treg cells, and decreased Th17 cells in blood of bone fracture rats. Further, tibial fracture rats implanted with the adenosine A2A receptor agonist gel were injected with IL-6. We found that IL-6 could reverse the effect of adenosine A2A receptor agonists on fracture healing and Treg/Th17 cells in blood. Through the above results, we believe that the adenosine A2A receptor agonist can promote fracture healing and regulate Treg/Th17 cells in blood of rats with fractures. These effects are related to IL-6.

Dysfunctional stem and progenitor cells impair fracture healing with age

Successful fracture healing requires the simultaneous regeneration of both the bone and vasculature; mesenchymal stem cells (MSCs) are directed to replace the bone tissue, while endothelial progenitor cells (EPCs) form the new vasculature that supplies blood to the fracture site. In the elderly, the healing process is slowed, partly due to decreased regenerative function of these stem and progenitor cells. MSCs from older individuals are impaired with regard to cell number, proliferative capacity, ability to migrate, and osteochondrogenic differentiation potential. The proliferation, migration and function of EPCs are also compromised with advanced age. Although the reasons for cellular dysfunction with age are complex and multidimensional, reduced expression of growth factors, accumulation of oxidative damage from reactive oxygen species, and altered signaling of the Sirtuin-1 pathway are contributing factors to aging at the cellular level of both MSCs and EPCs. Because of these geriatric-specific issues, effective treatment for fracture repair may require new therapeutic techniques to restore cellular function. Some suggested directions for potential treatments include cellular therapies, pharmacological agents, treatments targeting age-related molecular mechanisms, and physical therapeutics. Advanced age is the primary risk factor for a fracture, due to the low bone mass and inferior bone quality associated with aging; a better understanding of the dysfunctional behavior of the aging cell will provide a foundation for new treatments to decrease healing time and reduce the development of complications during the extended recovery from fracture healing in the elderly.

[Physical treatment options with impact on bone healing]

The impact of physical stimulation of a fracture remains unsolved because of the complexity of this process. Differences in the localization and the morphology of the fracture, soft tissue injury, pretreatment and risk factors have an influence on study results, leading to problems in evaluation of physical modulation concerning fractures and nonunions. Extracorporeal shock wave therapy (ESWT) is technically demanding and often associated with local complications including bone and soft tissue stress; however, it is still applied in some centers for the treatment of nonunions. The study situation assessing the effectiveness of this treatment consists of a single randomized controlled trial (RCT) with a medium risk of bias. A positive effect for bony healing could be seen in 70-71% of ESWT patients but also in 73% of the surgically treated group. A systematic review and meta-analysis demonstrated an insufficient and inconsistent study quality but acknowledged that ESWT can be an effective treatment for delayed union and nonunion. For low-intensity pulsed ultrasound (LIPUS) studies with a reduced bias are available, representing a better level of evidence. Concerning advantages in the consolidation of acute fractures, only one RCT showed a reduction of healing time in fractures with an expected prolonged bony bridging. For the treatment of delayed unions, a highly rated RCT showed a significantly improved consolidation of midshaft tibial fractures using LIPUS. A systematic review and meta-analysis of nonunions showed positive effects in biologically active lesions, e.g. in hypertrophic pseudarthrosis, leading to a fusion rate of 80%. The consolidation process was better in patients without surgical revision 3-6 months prior to LIPUS.

Low Intensity Pulsed Ultrasound Influences the Myogenic Differentiation of Muscle Satellite Cells in a Stress Urinary Incontinence Rat Model

OBJECTIVE

To investigate the therapeutic effect of low intensity pulsed ultrasound (LIPUS) in a stress urinary incontinence (SUI) rat model and its influence on myogenic satellite cells.

METHODS

Fifty Sprague-Dawley rats underwent vaginal distension and bilateral ovariectomy mimicking partum injury and menopause to construct SUI models, which were further randomized into 100 mW/cm² LIPUS, 200 mW/cm² LIPUS, 300 mW/cm² LIPUS, and none-treatment control subgroups with 10 rats per subgroup. Ten rats served as mock operation control. Leak point pressure and bladder capacity were recorded 1 week after LIPUS treatment. Immunofluorescence staining and Western blot were performed to examine histological changes, myodifferentiation, and signaling pathway.

RESULTS

Here,we found the leak point pressure and bladder capacity were restored in 200 mW/cm² LIPUS and 300 mW/cm² LIPUS groups, but not in 100 mW/cm² LIPUS group. More robust striated muscle regeneration was observed in 200 mW/cm² LIPUS group comparing with the SUI none-treatment group. Moreover, we found LIPUS activated the myodifferentiation of muscle satellite cells, which is correlated to p38 phosphorylation level.

CONCLUSION

LIPUS restored the leak point pressure and bladder capacity, and activated satellite cell myodifferentiation in SUI rat model.

Effect of low-intensity pulsed ultrasound on distraction osteogenesis: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Low-intensity pulsed ultrasound (LIPUS) is a common adjunct used to promote bone healing for fresh fractures and non-unions, but its efficacy for bone distraction osteogenesis remains uncertain. This study aims to determine whether LIPUS can effectively and safely reduce the associated treatment time for patients undergoing distraction osteogenesis.

METHODS

MEDLINE, EMBASE, and the Cochrane Library were searched until May 1, 2018, without language restriction. Studies should be randomized controlled trials (RCTs) or quasi-RCTs of LIPUS compared with sham devices or no devices in patients who undergo distraction osteogenesis. The primary outcome was the treatment time. The secondary outcome was the risk of complications. Treatment effects were assessed using mean differences, standardized mean differences, or risk ratios using a random-effects model. The Cochrane risk-of-bias tool was used to assess the risk of bias. The I² statistic was used to assess the heterogeneity. The GRADE system was used to evaluate the evidence quality.

RESULTS

A total of 7 trials with 172 patients were included. The pooled results suggested that during the process of distraction osteogenesis, LIPUS therapy did not show a statistically significant reduction in the treatment time (mean difference, - 8.75 days/cm; 95% CI, - 20.68 to 3.18 days/cm; P = 0.15; I² = 72%) or in the risk of complications (risk ratio, 0.90 in favor of LIPUS; 95% CI, 0.65 to 1.24; I² = 0%). Also, LIPUS therapy did not show a significant effect on the radiological gap fill area (standardized mean difference, 0.48 in favor of control; 95%CI, - 1.49 to 0.52; I² = 0%), the histological gap fill length (standardized mean difference, 0.76 in favor of control; 95%CI, - 1.78 to 0.27; I² = 0%), or the bone density increase (standardized mean difference, 0.43 in favor of LIPUS; 95%CI, - 0.02 to 0.88; I² = 0%).

CONCLUSIONS

Among patients undergoing distraction osteogenesis, neither the treatment time nor the risk of complications could be reduced by LIPUS therapy. The currently available evidence is insufficient to support the routine use of this intervention in clinical practice.

TRIAL REGISTRATION

CRD 42017073596.

Local administration of WP9QY (W9) peptide promotes bone formation in a rat femur delayed-union model

The WP9QY peptide (W9) consists of nine amino acids. It binds to RANKL and blocks RANKL-induced increases in bone resorption and osteoclastogenesis. W9 has a unique effect on the coupling mechanism between osteoclasts and osteoblasts, which promotes bone formation while working to suppress bone resorption. In this study, with the aim of clinical application of W9 for fracture treatment, we aimed to clarify the bone repair-promoting effect of W9 when administered locally to a rat femur model of delayed union. Using Sprague-Dawley rats, a model of delayed union was created in the right femur by cauterizing the periosteum. Injection of W9 (1 mg in 100 μl) or phosphate-buffered saline (PBS) (100 μl) at the fracture site was performed at the operation and every week thereafter until death (sacrifice). The bone union rate was 14% in the PBS group and 57% in the W9 group at 8 weeks postoperatively. The X-ray score of the W9 group was significantly higher than that of the PBS group at 8 weeks postoperatively. When bone morphometry was analyzed by micro-computed tomography (CT), total callus volume (TV) and mineralized callus bone volume (BV) were measured. TV showed no significant difference between the two groups, but BV/TV was significantly higher in the W9 group. This finding suggests that local administration of W9 can promote bone maturation from callus and can be considered to contribute to fracture healing. These results reveal that W9 has an effect on fractures of promoting healing and could be applied as a fracture treatment.

Low-intensity pulsed ultrasound promotes spinal fusion and enhances migration and proliferation of MG63s through sonic hedgehog signaling pathway

Low-intensity pulsed ultrasound (LIPUS) has been found to accelerate the healing process of spinal fusion via a process closely related to osteoblast differentiation and migration. Sonic hedgehog (Shh) signaling plays an important role in development and homeostasis, including a critical function in bone formation. However, its role in spinal fusion during LIPUS treatment is still unknown. This study showed that LIPUS treatment after spinal fusion surgery increased bone formation. The increased bone mass under LIPUS treatment appeared to result from the increased migration and proliferation of osteoblasts, resulting from upregulation of the Shh signaling pathway. In contrast, inhibition of Shh reduced the migratory and proliferative ability of osteoblast-like MG63 cells and blocked the efficacy of LIPUS treatment.

Therapy Concepts for the Proximal Interphalangeal Joint

The principles of hand therapy for proximal interphalangeal joint disorders include protecting injured structures, minimizing patient discomfort, and optimizing patient recovery. Comprehension of hand anatomy, the nature of the injury being treated, and the phases of healing are critical when designing a safe and effective hand therapy program. Hand therapists use a combination of orthoses, guided exercises, and modalities to improve edema, sensitivity, range of motion, and function.

When Is a Fracture Not "Fresh"? Aligning Reimbursement With Patient Outcome After Treatment With Low-Intensity Pulsed Ultrasound

OBJECTIVE

The clinical value of low-intensity pulsed ultrasound (LIPUS) for fresh fracture is known. Yet, in the absence of a definition of what "fresh" is, payers have adopted study inclusion criteria drawn from randomized clinical trials as de facto definitions of which patients should be treated, with "fresh" defined as <1 week old. Patients with fracture may thus be ineligible for LIPUS treatment after week 1, which potentially denies access to patients who could benefit from LIPUS. We seek to characterize the inflection point at which heal rate declines.

DESIGN

Prospective cohort.

SETTING

Food and Drug Administration-mandated nationwide postmarketing surveillance registry.

PATIENTS

Observational cohort of 5983 registry enrollees.

INTERVENTION

LIPUS, 20 min/d.

MAIN OUTCOME MEASURE

Fracture heal rate. Logistic regression was used to model the odds ratio of nonunion from week 1 to week 12. Covariates in the model included age, gender, body mass index, open fracture, and smoking.

RESULTS

We estimated the time point at which a fracture responds to LIPUS as well as during the first week after fracture. There was significant bone-to-bone variation; metatarsal was "fresh" until week 7, ankle until week 9, humerus until week 10, and femur and radius until week 12. Healing was significantly impacted by patient age, body mass index, and open fracture (all, P ≤ 0.02).

CONCLUSIONS

Our results suggest that fractures of the metatarsal, femur, humerus, ankle, and radius respond to LIPUS treatment, as if they were still fresh at least 6 weeks longer than the eligibility allowed under current coverage policies.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Low-intensity pulsed ultrasound is effective for progressive-stage lumbar spondylolysis with MRI high-signal change

PURPOSE

This study aimed to investigate the treatment effects of low-intensity pulsed ultrasound (LIPUS) on progressive-stage spondylolysis. Spondylolysis is a stress fracture of the pars interarticularis. Based on the results of computed tomography, spondylolysis was classified into three categories: early, progressive, and terminal. Bone healing was prolonged or not obtained in progressive-stage spondylolysis. The progression of spondylolysis to nonunion has been associated with an increased incidence of spondylolisthesis. To prevent these clinical conditions, achieving bony healing of the spondylolysis site should be the goal of treatment.

METHODS

15 consecutive pediatric patients with progressive-stage spondylolysis (defects) with MRI high-signal change were analyzed. Nine patients were treated conservative treatment including avoidance of any sport activity and the use of a brace during treatment (conventional). Six patients were treated using LIPUS everyday during treatment in addition to conservative treatment. Approximately every 1.5 months, bone healing was evaluated via CT. Cases that retained defects after 4.5 months were defined as nonunion.

RESULTS

Two patients dropped out during the study period. A total of 13 patients (mean 14.6 ± 2.5 years) from the database met with 19 interarticularis defects. The bone union rate in LIPUS group was significantly higher than that in conventional group (66.7 vs. 10.0%, p = 0.020). The treatment period to bone union was 3.8 months and 2.7 ± 0.3 months in conventional and LIPUS groups.

CONCLUSIONS

This study revealed that LIPUS treatment might be effective for bone union in patients with progressive-stage spondylolysis with MRI high-signal change.

LEVEL OF EVIDENCE

4.

Low intensity pulsed ultrasound for bone healing: systematic review of randomized controlled trials

Objective To determine the efficacy of low intensity pulsed ultrasound (LIPUS) for healing of fracture or osteotomy.Design Systematic review and meta-analysis.Data sources Medline, Embase, CINAHL, Cochrane Central Register of Controlled Trials, and trial registries up to November 2016.Study selection Randomized controlled trials of LIPUS compared with sham device or no device in patients with any kind of fracture or osteotomy.Review methods Two independent reviewers identified studies, extracted data, and assessed risk of bias. A parallel guideline committee (BMJ Rapid Recommendation) provided input on the design and interpretation of the systematic review, including selection of outcomes important to patients. The GRADE system was used to assess the quality of evidence.Results 26 randomized controlled trials with a median sample size of 30 (range 8-501) were included. The most trustworthy evidence came from four trials at low risk of bias that included patients with tibia or clavicle fractures. Compared with control, LIPUS did not reduce time to return to work (percentage difference: 2.7% later with LIPUS, 95% confidence interval 7.7% earlier to 14.3% later; moderate certainty) or the number of subsequent operations (risk ratio 0.80, 95% confidence interval 0.55 to 1.16; moderate certainty). For pain, days to weight bearing, and radiographic healing, effects varied substantially among studies. For all three outcomes, trials at low risk of bias failed to show a benefit with LIPUS, while trials at high risk of bias suggested a benefit (interaction P<0.001). When only trials at low risk of bias trials were considered, LIPUS did not reduce days to weight bearing (4.8% later, 4.0% earlier to 14.4% later; high certainty), pain at four to six weeks (mean difference on 0-100 visual analogue scale: 0.93 lower, 2.51 lower to 0.64 higher; high certainty), and days to radiographic healing (1.7% earlier, 11.2% earlier to 8.8% later; moderate certainty).Conclusions Based on moderate to high quality evidence from studies in patients with fresh fracture, LIPUS does not improve outcomes important to patients and probably has no effect on radiographic bone healing. The applicability to other types of fracture or osteotomy is open to debate.Systematic review registration PROSPERO CRD42016050965.

Mechanobiology of bone remodeling and fracture healing in the aged organism

Bone can adapt to changing load demands by mechanically regulated bone remodeling. Osteocytes, osteoblasts, and mesenchymal stem cells are mechanosensitive and respond to mechanical signals through the activation of specific molecular signaling pathways. The process of bone regeneration after fracture is similarly and highly regulated by the biomechanical environment at the fracture site. Depending on the tissue strains, mesenchymal cells differentiate into fibroblasts, chondrocytes, or osteoblasts, determining the course and the success of healing. In the aged organism, mechanotransduction in both intact and fractured bones may be altered due to changed hormone levels and expression of growth factors and other signaling molecules. It is proposed that altered mechanotransduction may contribute to disturbed healing in aged patients. This review explains the basic principles of mechanotransduction in the bone and the fracture callus and summarizes the current knowledge on aging-induced changes in mechanobiology. Furthermore, the methods for external biomechanical stimulation of intact and fractured bones are discussed with respect to a possible application in the elderly patient.

Regenerate bone stimulation following limb lengthening: a meta-analysis

Background

Limb lengthening with external fixation is performed to treat patients with leg length discrepancy or short stature. Although the procedure has a high rate of success, one potential drawback from limb lengthening is the amount of time spent in the fixation device while regenerate bone consolidates. Although some studies have assessed different treatment modalities, there has not been a study that has systematically evaluated whether low intensity pulsed ultrasound (LIPUS) or pulsed electromagnetic fields (PEMF) have significant effects on regenerate bone growth. The purpose of this study was to evaluate these two non-pharmacological treatment options to stimulate regenerate bone, and to assess whether they affect the treatment time in limb lengthening.

Methods

Utilizing the electronic databases Medline, Embase and Ovid, we performed a literature search for studies describing the application of LIPUS or PEMF following limb lengthening. With the aid of a statistical software package, Forest-Plots were generated to compare the differences in bone healing index with and without the use of regenerate bone stimulation.

Results

A total of 7 studies assessed these two bone stimulation modalities in a cohort of 153 patients. Overall, the mean healing index was 11.7 days/cm faster when using bone stimulation that in the comparison cohorts (33.7 vs 45.4 day, standardized mean difference of 1.16; p = 0.003).

Conclusion

Amongst the drawbacks from limb lengthening is the relatively high rate of non- and delayed-union. Several methods, both pharmacological and non-pharmacological, have been investigated for their potential to stimulate the growth of regenerate bone. After systematically evaluating the limited and heterogeneous current literature, we found that LIPUS and PEMF both decreased the time for bone healing (healing index in days/cm) of the newly formed regenerate bone in an adequately selected cohort of patients that underwent limb lengthening. However, a high number of complications should be noted, which could be attributed to the lengthening procedure or to the additional bone stimulation.

PROSPERO registration number

CRD42016039024

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1259-5) contains supplementary material, which is available to authorized users.