Fracture pain-Traveling unknown pathways

Chemical neurolysis for the conservative treatment of hip fractures

Aim: Hip fracture management is challenging when surgical risks outweigh benefits. Inadequate analgesia from conservative treatments prompted new procedures targeting hip capsule denervation. This study evaluates the efficacy and safety of single injection chemical hip neurolysis in the pericapsular nerve group plane. Materials & methods: In eligible patients, an ultrasound-guided diagnostic block was performed using 5 ml of 2% lidocaine in the pericapsular nerve group plane. If positive, 6 ml of 99.9% alcohol was administered. Results: From May 2022 to May 2023, five patients underwent hip neurolysis. None reported pain at day 5 or during follow-up. There were no adverse effects. Conclusion: Chemical neurolysis seems to provide effective and safe conservative treatment for hip fractures, offering reliable analgesia for nonsurgical candidates.

Role of the Neurologic System in Fracture Healing: An Extensive Review

PURPOSE OF REVIEW

Despite advances in orthopedics, there remains a need for therapeutics to hasten fracture healing. However, little focus is given to the role the nervous system plays in regulating fracture healing. This paucity of information has led to an incomplete understanding of fracture healing and has limited the development of fracture therapies that integrate the importance of the nervous system. This review seeks to illuminate the integral roles that the nervous system plays in fracture healing.

RECENT FINDINGS

Preclinical studies explored several methodologies for ablating peripheral nerves to demonstrate ablation-induced deficits in fracture healing. Conversely, activation of peripheral nerves via the use of dorsal root ganglion electrical stimulation enhanced fracture healing via calcitonin gene related peptide (CGRP). Investigations into TLR-4, TrkB agonists, and nerve growth factor (NGF) expression provide valuable insights into molecular pathways influencing bone mesenchymal stem cells and fracture repair. Finally, there is continued research into the connections between pain and fracture healing with findings suggesting that anti-NGF may be able to block pain without affecting healing. This review underscores the critical roles of the central nervous system (CNS), peripheral nervous system (PNS), and autonomic nervous system (ANS) in fracture healing, emphasizing their influence on bone cells, neuropeptide release, and endochondral ossification. The use of TBI models contributes to understanding neural regulation, though the complex influence of TBI on fracture healing requires further exploration. The review concludes by addressing the neural connection to fracture pain. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

Do Not Lose Your Nerve, Be Callus: Insights Into Neural Regulation of Fracture Healing

PURPOSE OF REVIEW

Fractures are a prominent form of traumatic injury and shall continue to be for the foreseeable future. While the inflammatory response and the cells of the bone marrow microenvironment play significant roles in fracture healing, the nervous system is also an important player in regulating bone healing.

RECENT FINDINGS

Considerable evidence demonstrates a role for nervous system regulation of fracture healing in a setting of traumatic injury to the brain. Although many of the impacts of the nervous system on fracture healing are positive, pain mediated by the nervous system can have detrimental effects on mobilization and quality of life. Understanding the role the nervous system plays in fracture healing is vital to understanding fracture healing as a whole and improving quality of life post-injury. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

Optimization of Cobalt-Chromium (Co-Cr) Scaffolds for Bone Tissue Engineering in Endocrine, Metabolic and Immune Disorders

Approximately 50% of the adult global population is projected to suffer from some form of metabolic disease by 2050, including metabolic syndrome and diabetes mellitus. At the same time, this trend indicates a potential increase in the number of patients who will be in need of implant-supported reconstructions of specific bone regions subjected to inflammatory states. Moreover, physiological conditions associated with dysmetabolic subjects have been suggested to contribute to the severity of bone loss after bone implant insertion. However, there is a perspective evidence strengthening the hypothesis that custom-fabricated bioengineered scaffolds may produce favorable bone healing effects in case of altered endocrine or metabolic conditions. This perspective review aims to share a comprehensive knowledge of the mechanisms implicated in bone resorption and remodelling processes, which have driven researchers to develop metallic implants as the cobalt-chromium (Co-Cr) bioscaffolds, presenting optimized geometries that interact in an effective way with the osteogenetic precursor cells, especially in the cases of perturbed endocrine or metabolic conditions.

Cannabidiol and Cannabigerol, Nonpsychotropic Cannabinoids, as Analgesics that Effectively Manage Bone Fracture Pain and Promote Healing in Mice

Bone fractures are among the most prevalent musculoskeletal injuries, and pain management is an essential part of fracture treatment. Fractures heal through an early inflammatory phase, followed by repair and remodeling. Nonsteroidal anti-inflammatory drugs (NSAIDs) are not recommended for fracture pain control as they potently inhibit the inflammatory phase and, thus, impair the healing. Opioids do not provide a better alternative for several reasons, including abuse potential. Accordingly, there is an unmet clinical need for analgesics that effectively ameliorate postfracture pain without impeding the healing. Here, we investigated the analgesic efficacy of two nonpsychotropic cannabinoids, cannabidiol (CBD) and cannabigerol (CBG), in a mouse model for tibial fracture. Mice with fractured tibiae exhibited increased sensitivity to mechanical, cold, and hot stimuli. Both CBD and CBG normalized pain sensitivity to all tested stimuli, and their analgesic effects were comparable to those of the NSAIDs. Interestingly, CBD and CBG promoted bone healing via multiple mechanisms during the early and late phases. During the early inflammatory phase, both cannabinoids increased the abundance of periosteal bone progenitors in the healing hematoma and promoted the osteogenic commitment of these progenitors. During the later phases of healing, CBD and CBG accelerated the fibrocartilaginous callus mineralization and enhanced the viability and proliferation of bone and bone-marrow cells. These effects culminated in higher bone volume fraction, higher bone mineral density, and improved mechanical quality of the newly formed bone. Together, our data suggest CBD and CBG as therapeutic agents that can replace NSAIDs in managing postfracture pain as both cannabinoids exert potent analgesic effects and, at the same time, promote bone healing. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Pathophysiological mechanism of acute bone loss after fracture

BACKGROUND

Acute bone loss after fracture is associated with various effects on the complete recovery process and a risk of secondary fractures among patients. Studies have reported similarities in pathophysiological mechanisms involved in acute bone loss after fractures and osteoporosis. However, given the silence nature of bone loss and bone metabolism complexities, the actual underlying pathophysiological mechanisms have yet to be fully elucidated.

AIM OF REVIEW

To elaborate the latest findings in basic research with a focus on acute bone loss after fracture. To briefly highlight potential therapeutic targets and current representative drugs. To arouse researchers' attention and discussion on acute bone loss after fracture.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Bone loss after fracture is associated with immobilization, mechanical unloading, blood supply damage, sympathetic nerve regulation, and crosstalk between musculoskeletals among other factors. Current treatment strategies rely on regulation of osteoblasts and osteoclasts, therefore, there is a need to elucidate on the underlying mechanisms of acute bone loss after fractures to inform the development of efficacious and safe drugs. In addition, attention should be paid towards ensuring long-term skeletal health.

Genicular nerve and fracture site chemical neurolysis for distal femoral fracture: a case report

BACKGROUND

Distal femur fractures account for approximately 3%-6% of all femoral fractures. Non-operative management may be an attractive option for the elderly with significant perioperative mortality risk. Adequate pain control is a major barrier to non-operative fracture management. Chemical neurolysis has been described for analgesic management of proximal hip fractures, however no description of interventional management of distal femur fracture exists in literature. We describe a case of phenol chemical neurolysis of genicular nerves in addition to injection at the site of fracture to provide effective analgesia for distal femur fracture.

CASE PRESENTATION

A patient in their 90s with a witnessed mechanical fall sustained an intra-articular displaced fracture of the distal right femur shaft with extension into the distal femoral condyle. The patient elected to undergo non-surgical management given the high perioperative mortality risk. Acute pain service was involved and multimodal oral analgesics including opioids were insufficient in managing the patient's pain. The addition of femoral nerve catheter local anesthetic infusion did not sufficiently improve analgesia. Phenol chemical neurolysis of the superolateral, superomedial, inferomedial genicular nerves and of the fracture site was offered and performed. Resting pain decreased from Numerical Rating Scale 5/10 to 0/10 on postprocedure day 1. This was sustained at the 2-month timepoint.

CONCLUSIONS

We report the successful use of phenol neurolysis of genicular nerves and the fracture site in an elderly patient with a conservatively managed distal femur fracture. These interventions resulted in improved analgesia and achieved prolonged duration of effect.

Bulleyaconitine A reduces fracture-induced pain and promotes fracture healing in mice

A fracture is a severe trauma that causes dramatic pain. Appropriate fracture pain management not only improves the patient's subjective perception, but also increases compliance with rehabilitation training. However, current analgesics for fracture pain are unsatisfactory because of their negative effects on fracture healing or addiction problems. Bulleyaconitine A (BLA), a non-addictive analgesic medicine, is used for the treatment of chronic pain of musculoskeletal disorders in clinical practice, whereas the effects of BLA on fracture pain is undefined. To evaluate the analgesic effects of BLA on fracture, we generated tibial fracture mice here. It is found that oral administration of BLA to mice alleviates fracture-induced mechanical and thermal hyperalgesia. Interestingly, BLA significantly increases locomotor activity levels and reduces anxiety-like behaviors in fractured mice, as determined by open-field test. Notably, BLA treatment promotes bone mineralization and therefore fracture healing in mice, which may be attributed to the increase in mechanical stimulation caused by exercise. Our study suggests that BLA can be used as a promising analgesic agent for the treatment of fracture pain.

The effects of pain relief on proprioception and muscle strength for tibial plateau fractures: A randomized controlled trial

OBJECTIVES

To investigate the effect of transcutaneous electrical acupoint stimulation (TEAS) combined with proprioceptive neuromuscular facilitation (PNF) on postural stability, muscle strength and pain in patients with tibial plateau fracture.

METHOD

A 3-arm randomized controlled trial was conducted in 60 patients with tibial plateau fracture. Participants received one of the following interventions: standard treatment (ST group, n = 20), ST + PNF training (ST + PNF group, n = 20), ST + PNF training + TEAS intervention (ST + PNF + TEAS group, n = 20). All treatments lasted for six weeks. Participants' postural stability, muscle strength and pain were evaluated at baseline, after 3 and 6 weeks of intervention.

RESULTS

After 3 weeks of intervention, Between-group comparisons showed that both the ST + PNF group and ST + PNF + TEAS group showed significantly greater performance than the ST group in the postural stability measure (P < 0.02) and pain score(P < 0.05). The peak torque of quadriceps extensors and flexors at the velocity of 60°/s was significantly higher in the ST + PNF + TEAS group than in the ST group (P < 0.02). After 6 weeks of intervention, only the ST + PNF + TEAS group was superior to the ST group in postural stability measure(P < 0.04) and in pain score (P < 0.05). The ST + PNF + TEAS group was significantly higher than the ST + PNF group and the ST group in the peak torque of quadriceps extensors at the velocity of 60°/s and 180°/s (P < 0.01).

CONCLUSION

PNF training could improve dynamic postural stability and relieve pain at three weeks, while TEAS combined with PNF was more effective in relieving pain, strengthening muscle strength and improving dynamic postural stability at six weeks post-intervention.

Oral L-arginine supplementation for fracture healing: a systematic review of preclinical studies

Introduction

Approximately 5 to 10% of all patients with fractures experience deficient fracture healing that results in fracture nonunions. Previous studies have shown that nitric oxide production from arginine could improve fracture healing by improving local blood supply, supplementing growth factors, and improving collagen synthesis. Apart from its simple oral mode of administration, this amino acid provides a non-toxic and inexpensive option for fracture healing. To date, no systematic reviews regarding oral L-arginine supplementation for fracture healing are available. We present the first systematic review of oral L-arginine supplementation for fracture healing.

Methods

A systematic literature search was carried out using PubMed, Google Scholar, and ScienceDirect until February 1, 2021 using a combination of text words. No date limits were set. Studies investigating the use of oral L-arginine supplementation for fracture healing were included. Reference lists of relevant publications were assessed for additional references. In addition, bibliographies from other reviews were searched.

Results

Four studies were included. Of these, 3 were animal studies, and the other one was an in vitro study. Animals that were given oral L-arginine supplementation had significantly increased angiogenesis, reduced defect area, higher osteoblasts and osteoclasts, and higher rate of bone formation compared to controls.

Conclusions

The available preclinical studies suggest that oral L-arginine supplementation is a potential new therapy for fracture healing. This amino acid supplement is not only affordable and non-toxic; it is also simple. Further clinical studies are required to investigate the optimal dose of oral L-arginine supplementation for fracture healing in human subjects.

Modelling skeletal pain harnessing tissue engineering

Bone pain typically occurs immediately following skeletal damage with mechanical distortion or rupture of nociceptive fibres. The pain mechanism is also associated with chronic pain conditions where the healing process is impaired. Any load impacting on the area of the fractured bone will stimulate the nociceptive response, necessitating rapid clinical intervention to relieve pain associated with the bone damage and appropriate mitigation of any processes involved with the loss of bone mass, muscle, and mobility and to prevent death. The following review has examined the mechanisms of pain associated with trauma or cancer-related skeletal damage focusing on new approaches for the development of innovative therapeutic interventions. In particular, the review highlights tissue engineering approaches that offer considerable promise in the application of functional biomimetic fabrication of bone and nerve tissues. The strategic combination of bone and nerve tissue engineered models provides significant potential to develop a new class of in vitro platforms, capable of replacing in vivo models and testing the safety and efficacy of novel drug treatments aimed at the resolution of bone-associated pain. To date, the field of bone pain research has centred on animal models, with a paucity of data correlating to the human physiological response. This review explores the evident gap in pain drug development research and suggests a step change in approach to harness tissue engineering technologies to recapitulate the complex pathophysiological environment of the damaged bone tissue enabling evaluation of the associated pain-mimicking mechanism with significant therapeutic potential therein for improved patient quality of life.

Graphical abstract

Rationale underlying novel drug testing platform development. Pain detected by the central nervous system and following bone fracture cannot be treated or exclusively alleviated using standardised methods. The pain mechanism and specificity/efficacy of pain reduction drugs remain poorly understood. In vivo and ex vivo models are not yet able to recapitulate the various pain events associated with skeletal damage. In vitro models are currently limited by their inability to fully mimic the complex physiological mechanisms at play between nervous and skeletal tissue and any disruption in pathological states. Robust innovative tissue engineering models are needed to better understand pain events and to investigate therapeutic regimes.

Hip resection arthroplasty for acute femoral neck fractures in the non-ambulator

Objectives:

Hemiarthroplasty (HA) is the current standard of care for displaced femoral neck fractures (FNFs) in non-ambulators. Despite excellent outcomes, arthroplasty-specific risks remain, including dislocation, implant failure, periprosthetic fracture and infection, and fat embolization syndrome. To eliminate the possibility of these complications, should non-ambulatory patients with acute, native hip FNFs be treated with simple hip resection arthroplasty (HRA) instead of HA?

Design:

Retrospective case series.

Setting:

Large, urban level-1 trauma center.

Patients/Participants:

Five non-ambulatory patients (6 hips) with acute, native hip FNF underwent femoral head and neck resection. Also, the most recent 10 FNFs treated with HA were also identified for comparison purposes.

Intervention:

HRA was performed via a Smith-Peterson approach with an oscillating saw or osteotome to complete the fracture or perform a fresh neck cut.

Main Outcome Measurements:

Outcomes included postoperative vs preoperative VAS pain scores and narcotics usage, and return to baseline functional status (sit up in bed or a chair postoperatively). Procedure time for HRA was compared with the 10 most recent patients with FNF treated with HA.

Results:

HRA resulted in decreased postoperative vs preoperative VAS pain scores (7.7 vs 3.3, P = .002), and decreased operative times (59.2 minutes for HRA, 111.8 minutes for HA, P < .001). All HRA patients had immediate return of baseline function.

Conclusion:

HRA offers shorter operative times when compared with HA, decreased postoperative VAS pain scores, and immediate return to functional baseline status without possibility of arthroplasty-specific complications. HRA may be an acceptable treatment option for FNFs in the non-ambulator.

Level of evidence: IV

Multi-day delay to care identified in pediatric trauma cases during COVID-19

This study aims to establish how pediatric fracture patterns were altered at a level 1 trauma center in a state that implemented a shutdown during the initial height of COVID-19. After IRB approval, we identified 2017 patients treated at a pediatric institution for definitive management of a fracture between 26 March and 31 May 2018, 2019, or 2020. Dates were chosen based on statewide stay-at-home orders for Colorado. Patients were excluded for treatment at another institution (n = 148), no fracture noted in clinic (n = 18), or other (n = 13). Data were retrospectively collected from the remaining 1838 patients regarding demographics, fracture injury, mechanism, and treatment. Odds ratios (ORs) were calculated for each variable during COVID-19 relative to prior years. The number of fractures during 2020 decreased by 26% relative to 2019 and 23% to 2018. A larger proportion of patients experienced at least a 5-day delay to definitive treatment [OR: 1.55, confidence interval (CI): 1.23-1.96, P = 0.0002]. Rates of non-accidental trauma (NAT) increased non-significantly (OR: 2.67, CI: 0.86-8.32, P = 0.0900) during 2020 (1.2%) relative to 2018 (0.6%) and 2019 (0.3%). Fractures occurring at home increased to 79.9% (OR: 6.44, CI: 5.04-8.22, P < 0.0001). Despite less overall trauma during shelter-in-place orders, greater fracture numbers were seen among younger children and severe fractures were likely among older children. Patients may hesitate to seek care during 2020. Rates of NAT doubled during 2020. As communities prepare for future waves, treatment centers should warn against common fracture mechanisms and raise awareness of NAT.

What Did We Learn About Fracture Pain from Animal Models?

Progress in bone fracture repair research has been made possible due to the development of reproducible models of fracture in rodents with more clinically relevant fracture fixation, where there is considerably better assessment of the factors that affect fracture healing and/or novel therapeutics. However, chronic or persistent pain is one of the worst, longest-lasting and most difficult symptoms to manage after fracture repair, and an ongoing challenge remains for animal welfare as limited information exists regarding pain scoring and management in these rodent fracture models. This failure of adequate pre-clinical pain assessment following osteotomy in the rodent population may not only subject the animal to severe pain states but may also affect the outcome of the bone healing study. Animal models to study pain were also mainly developed in rodents, and there is increasing validation of fracture and pain models to quantitatively evaluate fracture pain and to study the factors that generate and maintain fracture pain and develop new therapies for treating fracture pain. This review aims to discuss the different animal models for fracture pain research and characterize what can be learned from using animal models of fracture regarding behavioral pain states and new molecular targets for future management of these behaviors.

Increased Calcitonin Gene-Related Peptide Expression in DRG and Nerve Fibers Proliferation Caused by Nonunion Fracture in Rats

Purpose

Nonunion bone fracture can be a cause of persistent pain, but the pathophysiology remains largely unknown. The objective of this study was to identify how nonunion affect persistent pain after fracture. Specifically, we evaluated the association of neuropeptide change in dorsal root ganglia (DRG) and nerve proliferation at fracture sites with pain.

Methods

Rat union and nonunion fracture models were created. A piece of latex glove was placed at the fracture site to create a nonunion model. At 6 weeks after surgery, bone healing was assessed using radiography. In addition, the presence of calcitonin gene-related peptide-immunoreactive (CGRP-IR) DRG at the level of L3 and anti-growth associated protein 43-immunoreactive (GAP43-IR) nerve fibers in the scar tissue between the bone fragments were evaluated. Pain-related behavior was assessed using forced treadmill running.

Results

In radiological images at 6 weeks after surgery, callus formation was formed continuously between bone fragments in the union models. On the one hand, a clear gap was detected between fragments in nonunion models. The percentage of CGRP-IR DRG cells and the density of GAP43-IR nerve fibers in the scar tissue between the bone fragments in nonunion models was significantly higher than that in union models (p < 0.05). An increase in inflammatory cell infiltrate was observed in scar tissues in the nonunion models. During forced treadmill running, rats in the union model could run significantly longer than those in the nonunion models.

Conclusion

Increased CGRP expression in DRG cells and abnormal nerve proliferation secondary to prolonged inflammation could lead to persistent pain after bone fracture. In clinical practice, early achievement of bone union may minimize the development of persistent pain after fractures.

Fracture-induced pain-like behaviours in a femoral fracture mouse model

This study is the first comprehensive characterisation of the pain phenotype after fracture using both evoked and naturalistic behaviours in adult male and ovariectomised female mice. It also shows that an anti-nerve growth factor (NGF) therapy could be considered to reduce pain after fracture surgery.

INTRODUCTION

Bone fractures are common due to the ageing population and very painful even after healing. The phenotype of this pain is still poorly understood. We aimed to characterise it in a femoral fracture model in mice.

METHODS

We employed both adult male, and female ovariectomised (OVX) mice to mimic osteoporotic fractures. Mice underwent a unilateral femoral fracture maintained by an external fixator or a sham surgery. Pain behaviours, including mechanical and thermal sensitivity, weight bearing and LABORAS, were measured from baseline to 6 weeks after fracture. The effect on pain of an antibody against nerve growth factor (anti-NGF) was assessed. Changes in nerve density at the fracture callus were analysed by immunohistochemistry.

RESULTS

Following surgery, all groups exhibited high levels of invoked nociception. Mechanical and thermal hyperalgesia were observed from 1 week after surgery, with nociceptive sensitization in the fracture group maintained for the 6 weeks, whereas it resolved in the sham group after 3 weeks. OVX induced reduction in pain thresholds, which was maintained after fracture. The frequency of naturalistic behaviours did not change between groups. Anti-NGF administered before and weekly after surgery alleviated fracture-induced mechanical nociception. The density of nerve fibres in the fracture callus was similar in all groups 6 weeks after surgery.

CONCLUSIONS

Fractures in rodent models are highly painful in both sexes. This pain-like phenotype is prolonged and should be routinely considered in fracture healing studies as it can affect the study outcome. The anti-NGF alleviates fracture-induced mechanical pain.

Comparison of Postoperative Pain and Analgesia Requirement among Diabetic and Nondiabetic Patients undergoing Lower Limb Fracture Surgery - A Prospective Observational Study

Background:

Diabetic patients usually experience neuropathic pain and have a decreased response to opioids. Fractures are acute conditions and as such, they are very painful. No data is available related to fracture and postoperative pain in diabetics.

Aim:

This study was conducted to evaluate postoperative pain and analgesics requirement among diabetic and nondiabetic patients undergoing lower limb fracture surgery and the effect of glycosylated hemoglobin (HbA1c) on the postoperative pain.

Setting and Design:

This was a prospective observational study, conducted on 80 patients comprising of nondiabetic and diabetic, scheduled for elective lower limb fracture surgery under spinal anesthesia.

Materials and Methods:

HbA1c was done in all the patients who were included in the study. Postoperative Visual Analog Scale (VAS) and analgesic consumption were assessed by an anesthesiologist blinded to the diabetic or nondiabetic status of the patients. VAS was assessed every 2^nd hourly, for 24 h and rescue analgesia was given if the VAS was ≥4 and record was maintained. Sedation scores and adverse effects were also recorded postoperatively.

Statistical Analysis:

The Chi-square test was used for the analysis of categorical variables and Student's t-test was used for continuous variables.

Results:

Diabetic group of patients had a significantly high VAS score with P ≤ 0.05. Rescue analgesics requirement was significantly different in two groups with diabetic patients requiring more supplementation of analgesia with a P = 0.025. The overall patient satisfaction was lesser in diabetic group (P = 0.004). There was statistically significant correlation between glycosylated hemoglobin and VAS at 2^nd, 16^th, 18^th, 20^th, 22^nd, and 24^th h.

Conclusion:

Postoperative pain and analgesic requirement was significantly higher in diabetic patients with lower limb fracture. Glycosylated hemoglobin had good correlation with higher VAS.

Ultrasound-Guided Hematoma Block for a Clavicular Fracture

BACKGROUND

Clavicular fractures are commonly encountered in the emergency department (ED). Fracture pain is usually treated with nonsteroidal anti-inflammatory drugs (NSAID) and opioids; however, both of these drug classes have potentially significant side effects that limit their use in certain patient populations. Hematoma blocks are safe and effective alternatives for pain control.

CASE REPORT

We present the case of a 39-year-old healthy man that presented to the ED with a clavicular fracture after a fall from a motorized scooter. He received minimal pain relief from hydrocodone-acetaminophen. A hematoma block was subsequently performed, with significant improvement in his pain. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Hematoma blocks are safe and effective treatments for clavicular fracture pain in the ED without the potentially significant side effects of NSAIDs and opioids.

Healthy Pain-Free Individuals with a History of Distal Radius Fracture Demonstrate an Expanded Distribution of Experimental Referred Pain Toward the Wrist

OBJECTIVE

Nociception caused by injuries may sensitize central mechanisms causing expanded pain areas. After recovery, the status of such pain distribution and sensitivity mechanisms is unknown. The present study investigated whether individuals who have fully recovered from a distal radius fracture demonstrate increased pain sensitivity and expanded distribution of pressure-induced pain.

DESIGN

Cross-sectional single-blinded study.

SETTING

Clinical setting.

SUBJECTS

Twenty-three pain-free individuals with a history of painful distal radius fracture and 22 nonfractured, age/gender-matched controls participated in two experimental sessions (day 0, day 1) 24 hours apart.

METHODS

Pressure pain thresholds (PPTs) were recorded bilaterally at the extensor carpi radialis longus (ECRL), infraspinatus, and gastrocnemius muscles. Spatial distribution of pain was assessed following 60-second painful pressure stimulation at the ECRL (bilateral) and the infraspinatus muscles on the fractured or dominant side. Participants drew pain areas on a body map. After day 0 assessments, prolonged pain was induced by eccentric exercise of wrist extensors on the fractured/dominant side.

RESULTS

Compared with controls, pressure-induced ECRL pain in the fracture group referred more frequently toward the distal forearm (P < 0.005) on day 0. Both groups showed larger pain areas on day 1 compared with day 0 (P < 0.005), although the fracture group showed a larger relative change between days (P < 0.005). The fracture group showed larger pain areas on the fracture side compared with the contralateral side on both days (P < 0.005).

CONCLUSIONS

Prolonged pain and recovered prior painful injuries like fractures may sensitize pain mechanisms manifested as expanded pain distribution. Pressure-induced referred pain can be a simple pain biomarker for clinical use.

Moderate to severe acute pain disturbs motor cortex intracortical inhibition and facilitation in orthopedic trauma patients: A TMS study

OBJECTIVE

Primary motor (M1) cortical excitability alterations are involved in the development and maintenance of chronic pain. Less is known about M1-cortical excitability implications in the acute phase of an orthopedic trauma. This study aims to assess acute M1-cortical excitability in patients with an isolated upper limb fracture (IULF) in relation to pain intensity.

METHODS

Eighty-four (56 IULF patients <14 days post-trauma and 28 healthy controls). IULF patients were divided into two subgroups according to pain intensity (mild versus moderate to severe pain). A single transcranial magnetic stimulation (TMS) session was performed over M1 to compare groups on resting motor threshold (rMT), short-intracortical inhibition (SICI), intracortical facilitation (ICF), and long-interval cortical inhibition (LICI).

RESULTS

Reduced SICI and ICF were found in IULF patients with moderate to severe pain, whereas mild pain was not associated with M1 alterations. Age, sex, and time since the accident had no influence on TMS measures.

DISCUSSION

These findings show altered M1 in the context of acute moderate to severe pain, suggesting early signs of altered GABAergic inhibitory and glutamatergic facilitatory activities.

Sustained Release of Levobupivacaine, Lidocaine, and Acemetacin from Electrosprayed Microparticles: In Vitro and In Vivo Studies

In this study, we explored the release characteristics of analgesics, namely levobupivacaine, lidocaine, and acemetacin, from electrosprayed poly(D,L-lactide-co-glycolide) (PLGA) microparticles. The drug-loaded particles were prepared using electrospraying techniques and evaluated for their morphology, drug release kinetics, and pain relief activity. The morphology of the produced microparticles elucidated by scanning electron microscopy revealed that the optimal parameters for electrospraying were 9 kV, 1 mL/h, and 10 cm for voltage, flow rate, and travel distance, respectively. Fourier-transform infrared spectrometry indicated that the analgesics had been successfully incorporated into the PLGA microparticles. The analgesic-loaded microparticles possessed low toxicity against human fibroblasts and were able to sustainably elute levobupivacaine, lidocaine, and acemetacin in vitro. Furthermore, electrosprayed microparticles were found to release high levels of lidocaine and acemetacin (well over the minimum therapeutic concentrations) and levobupivacaine at the fracture site of rats for more than 28 days and 12 days, respectively. Analgesic-loaded microparticles demonstrated their effectiveness and sustained performance for pain relief in fracture injuries.

Chronotherapy of Non-Steroidal Anti-Inflammatory Drugs May Enhance Postoperative Recovery

Postoperative pain relief is crucial for full recovery. With the ongoing opioid epidemic and the insufficient effect of acetaminophen on severe pain; non-steroidal anti-inflammatory drugs (NSAIDs) are heavily used to alleviate this pain. However, NSAIDs are known to inhibit postoperative healing of connective tissues by inhibiting prostaglandin signaling. Pain intensity, inflammatory mediators associated with wound healing and the pharmacological action of NSAIDs vary throughout the day due to the circadian rhythm regulated by the clock genes. According to this rhythm, most of wound healing mediators and connective tissue formation occurs during the resting phase, while pain, inflammation and tissue resorption occur during the active period of the day. Here we show, in a murine tibia fracture surgical model, that NSAIDs are most effective in managing postoperative pain, healing and recovery when drug administration is limited to the active phase of the circadian rhythm. Limiting NSAID treatment to the active phase of the circadian rhythm resulted in overexpression of circadian clock genes, such as Period 2 (Per2) at the healing callus, and increased serum levels of anti-inflammatory cytokines interleukin-13 (IL-13), interleukin-4 (IL-4) and vascular endothelial growth factor. By contrast, NSAID administration during the resting phase resulted in severe bone healing impairment.

Malnutrition and Fracture Healing: Are Specific Deficiencies in Amino Acids Important in Nonunion Development?

With the increasing incidence of fractures now, and in the future, the absolute number of bone-healing complications such as nonunion development will also increase. Next to fracture-dependent factors such as large bone loss volumes and inadequate stabilization, the nutritional state of these patients is a major influential factor for the fracture repair process. In this review, we will focus on the influence of protein/amino acid malnutrition and its influence on fracture healing. Mainly, the arginine-citrulline-nitric oxide metabolism is of importance since it can affect fracture healing via several precursors of collagen formation, and through nitric oxide synthases it has influences on the bio-molecular inflammatory responses and the local capillary growth and circulation.

Evaluation of the internal fixation effect of nano-calcium-deficient hydroxyapatite/poly-amino acid composite screws for intraarticular fractures in rabbits

Objective

To evaluate the internal fixation effect of nano-calcium-deficient hydroxyapatite/poly-amino acid (n-CDHA/PAA) composite screws in the intraarticular fracture model.

Materials and methods

A total of 35 New Zealand White rabbits were used in a bilateral femoral intercondylar fracture model and randomly divided into two groups. n-CDHA/PAA screws were used in the experimental group, and medical metal screws were used in the control group. The fracture condition, range of motion, and the screw push-out strength were assessed, and an arthroscopic examination of knee joint was performed at 4, 8, and 12 weeks after surgery. The biodegradation of the n-CDHA/PAA screws in vivo was tested through weighing, and changes in screw structure were assessed by X-ray diffraction at 12 weeks after surgery.

Results

The general situation of all animals was good and showed no incision infection and dehiscence after surgery. X-ray scanning showed that significant callus growth was present in both groups at 4 weeks after surgery, and there was no significant difference (P>0.05) in the Lane-Sandhu score between the experimental and control groups at all time points after surgery. There were no statistically significant differences (P>0.05) in the range of motion and Oswestry Arthroscopy Score of arthroscopic examination of the knee joints between the two groups. The screw push-out strength of the control group was stronger than that of the experimental group at 4 weeks after surgery (P<0.05), but after that, there was no significant difference between the groups (P>0.05). The degradation tests showed that the n-CDHA/PAA screws degraded gradually after implantation, and the weight loss rate was approximately 16% at 12 weeks after surgery. The X-ray diffraction results showed that the crystal structure of the outer surface of the n-CDHA/PAA screw has changed at 12 weeks after surgery.

Conclusion

The n-CDHA/PAA screw is an effective and safe implant as a potential internal fixation device for an intercondylar fracture of the femur, and its internal fixation effect was similar to that of medical metal screw.

New Insights in Understanding and Treating Bone Fracture Pain

PURPOSE OF REVIEW

This paper describes recent advances in understanding the mechanisms that drive fracture pain and how these findings are helping develop new therapies to treat fracture pain.

RECENT FINDINGS

Immediately following fracture, mechanosensitive nerve fibers that innervate bone are mechanically distorted. This results in these nerve fibers rapidly discharging and signaling the initial sharp fracture pain to the brain. Within minutes to hours, a host of neurotransmitters, cytokines, and nerve growth factor are released by cells at the fracture site. These factors stimulate, sensitize, and induce ectopic nerve sprouting of the sensory and sympathetic nerve fibers which drive the sharp pain upon movement and the dull aching pain at rest. If rapid and effective healing of the fracture occurs, these factors return to baseline and the pain subsides, but if not, these factors can drive chronic bone pain. New mechanism-based therapies have the potential to fundamentally change the way acute and chronic fracture pain is managed.

Ethanolic extract of Dalbergia sissoo promotes rapid regeneration of cortical bone in drill-hole defect model of rat

Leaves of Dalbergia sissoo is known to have protective actions against postmenopausal bone loss in rat. In this study, we have evaluated the fracture healing properties of ethanolic extract (EE) of Dalbergia sissoo leaves. To observe the fracture healing property in the drill-hole injury model, we randomly divided total 32 adult female Sprague Dawley rats (180±200g) into 4 groups: (i) Control operated group; (ii) EE (250mg/kg/day); (iii) EE (500mg/kg/day) and (iv) EE (1000mg/kg/day). The right femora were fractured at the mid-diaphysis region and each group of rats received their respective treatment for 15days. Ethanol extract dose dependently induced bone regeneration at the fracture site assessed by fluorochrome labeling. All of three doses, 250mg/kg/day dose significantly increased bone volume fraction, trabecular thickness, trabecular number, and connectivity density and decreased trabecular separation in bone. Furthermore, the extract induced the expression of osteogenic genes including BMP-2, BMP-4, RunX-2 and COL-1 compared to the control group. The EE improved fracture healing much earlier (day 15) than the normal healing process, as assessed by the increased callus volumes and mineralized nodule formation. This extract is found beneficial in fracture healing of rat.

Preventing painful age-related bone fractures: Anti-sclerostin therapy builds cortical bone and increases the proliferation of osteogenic cells in the periosteum of the geriatric mouse femur

Age-related bone fractures are usually painful and have highly negative effects on a geriatric patient’s functional status, quality of life, and survival. Currently, there are few analgesic therapies that fully control bone fracture pain in the elderly without significant unwanted side effects. However, another way of controlling age-related fracture pain would be to preemptively administer an osteo-anabolic agent to geriatric patients with high risk of fracture, so as to build new cortical bone and prevent the fracture from occurring. A major question, however, is whether an osteo-anabolic agent can stimulate the proliferation of osteogenic cells and build significant amounts of new cortical bone in light of the decreased number and responsiveness of osteogenic cells in aging bone. To explore this question, geriatric and young mice, 20 and 4 months old, respectively, received either vehicle or a monoclonal antibody that sequesters sclerostin (anti-sclerostin) for 28 days. From days 21 to 28, animals also received sustained administration of the thymidine analog, bromodeoxyuridine (BrdU), which labels the DNA of dividing cells. Animals were then euthanized at day 28 and the femurs were examined for cortical bone formation, bone mineral density, and newly borne BrdU+ cells in the periosteum which is a tissue that is pivotally involved in the formation of new cortical bone. In both the geriatric and young mice, anti-sclerostin induced a significant increase in the thickness of the cortical bone, bone mineral density, and the proliferation of newly borne BrdU+ cells in the periosteum. These results suggest that even in geriatric animals, anti-sclerostin therapy can build new cortical bone and increase the proliferation of osteogenic cells and thus reduce the likelihood of painful age-related bone fractures.