The relative incidence of fracture non-union in the Scottish population (5.17 million): a 5-year epidemiological study

Electrical impedance detects early stages of bone healing: An in vivo explanatory study of tibial fractures in rabbits

Purpose

Healing after bone fracture is assessed by clinical examination and frequent radiographs, which expose patients to radiation and lack standardisation. This study aimed to explore electrical impedance patterns during bone healing using electrical impedance spectroscopy in 18 rabbits subjected to tibial fracture stabilised with an external fixator.

Methods

Impedance was measured daily across the fracture site at a frequency range of 5 Hz to 1 MHz. Biweekly radiographs were analysed using modified anterior-posterior (AP) radiographic union score of the tibia (RUST). The animals were divided into three groups with different follow-up times: 1, 3 and 6 weeks for micro-computer tomography and mechanical testing.

Results

A decreasing trend in impedance was observed over time for all rabbits at lower frequencies. Impedance closest to 5 Hz showed a statistically significant decrease over time, with greatest decrease occurring during the first 7 postoperative days. At 5 Hz, a statistically significant correlation was found between impedance and the modified AP RUST score and between impedance and bone volume fraction.

Conclusions

This study showed that the electrical impedance can be measured in vivo at a distance from the fracture site with a consistent change in impedance over time and revealed significant correlation between increasing radiographic union score and decreasing impedance.

Level of Evidence

Not applicable.

[Non-unions of the upper extremities]

The diagnosis and treatment of non-unions still represents an interdisciplinary challenge. Therefore, prevention, early detection and specific treatment are of great importance. Non-unions of the upper extremities, although less common than that of the lower extremities, requires special attention for successful treatment due to the central role of the shoulder girdle and arm in day to day activities. Successful treatment of non-unions requires a comprehensive evaluation of the patient's medical history, a thorough clinical examination and in particular radiological imaging. In order to effectively treat the pseudarthrosis it is crucial to distinguish between pseudarthroses that are suspected to be due to infections and those that are not. This article presents a treatment algorithm for managing both pseudarthrosis due to infection and pseudarthrosis without infection in the upper extremities.

Long bone uninfected non-union: grafting techniques

Long bone non-unions represent a serious clinical and socioeconomical problem due to the prolonged episodes, frequent sequelae, and variable treatment effectiveness. Bone grafts, classically involving the autologous iliac crest graft as the 'gold standard' bone graft, enhance bone regeneration and fracture healing incorporating osteoconductive and/or osteoinductive/osteogenic capacity to the non-union under treatment. Structural alternatives to autologous bone grafts include allografts and bone substitutes, expanding the available stock but loosing biological properties associated with cells in the graft. Biological alternatives to autologous bone grafts include bone marrow concentration from iliac crest aspiration, bone marrow aspiration from reaming of the diaphyseal medullary canal in the long bones, and isolated, expanded mesenchymal stem cells under investigation. When the combination with natural and synthetic bone substitutes allows for larger volumes of structural grafts, the enhancement of the biological regenerative properties through the incorporation of cells and their secretoma permits to foresee new bone grafting solutions and techniques.

Trends in the Management of Fifth Metacarpal Neck Fractures

PURPOSE

To describe management trends of fifth metacarpal neck (5MCN) fractures within a large health care system. We aimed to define patient and surgeon factors associated with nonsurgical versus surgical treatment, as well as to identify factors associated with receiving care only in the emergency department (ED).

METHODS

We identified all 5MCN fractures within our system for the years 2012-2020 and recorded baseline demographics for cases. Injury, treatment, and fracture characteristics were all recorded. For fractures treated nonsurgically, we determined the type of immobilization used (if any) and recorded whether patients were seen only in the ED or received subsequent outpatient follow-up. Demographic comparisons were made between groups, and adjusted logistic regression models were generated to predict the odds of having a surgical 5MCN fracture or being seen in the ED only.

RESULTS

There were 611 5MCN fractures over an 8-year period, of which 10% were treated surgically. During the first half of the study period, 8% of isolated cases were treated surgically compared with 7% of cases in the second half. Soft dressings were increasingly used. There were no nonsurgically managed cases that underwent subsequent surgical procedures for symptomatic nonunion or malunion. Twenty-one percent of patients were seen only in the ED. Fracture angulation, associated injuries, insurance status, and treatment by a hand surgeon were all significantly associated with an increased likelihood of surgery.

CONCLUSIONS

Of the 611 5MCN fractures identified, 90% were treated nonsurgically. Patient and surgeon factors were associated with increased odds of surgery. Of patients who sought care for 5MCN injuries, >20% received no follow-up care outside of the ED. These data can be used to assess future changes in management trends and suggest that nonunion and symptomatic malunions are uncommon occurrences.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Non-Union Treatment in the Foot, Ankle, and Lower Leg: A Multicenter Retrospective Study Comparing Conventional Treatment with the Human Allogeneic Cortical Bone Screw (Shark Screw®)

Addressing non-unions involves stabilizing the affected area through osteosynthesis and improving bone biology using bone grafts. However, there is no consensus on the optimal treatment method. This study aims to compare outcomes of non-union surgery using conventional treatment methods (metal hardware ± graft) versus osteosynthesis with the human allogeneic cortical bone screw (Shark Screw®) alone or in combination with a metallic plate. Thirty-four patients underwent conventional treatment, while twenty-eight cases received one or more Shark Screws®. Patient demographics, bone healing, time to bone healing, and complications were assessed. Results revealed a healing rate of 96.4% for the Shark Screw® group, compared to 82.3% for the conventionally treated group. The Shark Screw® group exhibited a tendency for faster bone healing (9.4 ± 3.2 vs. 12.9 ± 8.5 weeks, p = 0.05061). Hardware irritations led to six metal removals in the conventional group versus two in the Shark Screw® group. The Shark Screw® emerges as a promising option for personalized non-union treatment in the foot, ankle, and select lower leg cases, facilitating effective osteosynthesis and grafting within a single construct and promoting high union rates, low complications, and a rapid healing process.

Principles and Evaluation of Bony Unions

Nonunion is a common and costly problem. Unfortunately, there is no widely agreed upon and standardized definition for nonunion. The evaluation of bony union should start with a thorough history and physical examination. The clinician should consider patient-dependent as well as patient-independent characteristics that may influence the rate of healing and evaluate the patient for physical examination findings suggestive of bony union and infection. Radiographs and clinical examination can help confirm a diagnosis of union. When the diagnosis is in doubt, however, advanced imaging modalities as well as laboratory studies can help a surgeon determine when further intervention is necessary.

Cracking the Code: The Role of Peripheral Nervous System Signaling in Fracture Repair

PURPOSE OF REVIEW

The traditionally understated role of neural regulation in fracture healing is gaining prominence, as recent findings underscore the peripheral nervous system's critical contribution to bone repair. Indeed, it is becoming more evident that the nervous system modulates every stage of fracture healing, from the onset of inflammation to repair and eventual remodeling.

RECENT FINDINGS

Essential to this process are neurotrophins and neuropeptides, such as substance P, calcitonin gene-related peptide, and neuropeptide Y. These molecules fulfill key roles in promoting osteogenesis, influencing inflammation, and mediating pain. The sympathetic nervous system also plays an important role in the healing process: while local sympathectomies may improve fracture healing, systemic sympathetic denervation impairs fracture healing. Furthermore, chronic activation of the sympathetic nervous system, often triggered by stress, is a potential impediment to effective fracture healing, marking an important area for further investigation. The potential to manipulate aspects of the nervous system offers promising therapeutic possibilities for improving outcomes in fracture healing. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

Circular external fixation for revision of failed tibia internal fixation

BACKGROUND

The management of failed tibial fracture fixation remains a challenge for orthopaedic surgeons. This study investigate the utility and outcomes of circular external fixation in the management of failed internal fixation of tibial fractures.

METHODS

Retrospective review of a prospectively collected database of a complex limb reconstruction unit at a major trauma centre was done during December 2022. Patients with failed internal fixation of tibial fracture who underwent revision surgery with circular external fixation frame were included.

RESULTS

20 patients with a mean age of 47.8 ± 16.5 years (range: 15-69) were included. Fourteen (70.0%) patients had failed plate and screws fixations, and the remaining six (30.0%) failed intramedullary nail fixation. The most common indication for revision surgery was development of early postoperative surgical site infection (5 patients; 25.0%). The mean duration of frame treatment was 199.5 ± 80.1 days (range = 49-364), while the mean follow-up duration following frame removal was 3.2 ± 1.8 years (range = 2-8). The overall union rate in this series was 100%; and all infected cases had complete resolution from infection. The total number of complications was 11, however, only two complications required surgical intervention. The most common complications reported were pin site infection (6; 30.0%) and limb length discrepancy of 2 cm (2; 10.0%).

CONCLUSIONS

Circular external fixation is a reliable surgical option in the treatment of failed internal fixation of tibia fractures. This technique can provide limb salvage in complex infected and noninfected cases with a high union rate and minimal major complications.

Current advances in anisotropic structures for enhanced osteogenesis

Bone defects are a challenge to healthcare systems, as the aging population experiences an increase in bone defects. Despite the development of biomaterials for bone fillers and scaffolds, there is still an unmet need for a bone-mimetic material. Cortical bone is highly anisotropic and displays a biological liquid crystalline (LC) arrangement, giving it exceptional mechanical properties and a distinctive microenvironment. However, the biofunctions, cell-tissue interactions, and molecular mechanisms of cortical bone anisotropic structure are not well understood. Incorporating anisotropic structures in bone-facilitated scaffolds has been recognised as essential for better outcomes. Various approaches have been used to create anisotropic micro/nanostructures, but biomimetic bone anisotropic structures are still in the early stages of development. Most scaffolds lack features at the nanoscale, and there is no comprehensive evaluation of molecular mechanisms or characterisation of calcium secretion. This manuscript provides a review of the latest development of anisotropic designs for osteogenesis and discusses current findings on cell-anisotropic structure interactions. It also emphasises the need for further research. Filling knowledge gaps will enable the fabrication of scaffolds for improved and more controllable bone regeneration.

Familial Analysis of Nonunion in a Genealogic Population Database Demonstrates No Evidence of Heritable Risk

OBJECTIVE

To determine whether there is evidence of heritable risk for nonunion using a large, state-wide population database.

DESIGN

Database.

SETTING

Level 1 Trauma Center.

POPULATION

All Utah residents from 1996 to 2021 who sustained a long bone fracture and their family members were included.

OUTCOMES

The primary outcome was nonunion and the prevalence of nonunion among the patients' first-, second-, and third-degree relatives. The secondary objective was to identify demographic, injury, and socioeconomic risk factors associated with nonunion.

RESULTS

In total, 150,263 fractures and 6577 nonunions (4.4%) were identified. This was highly refined to a 1:3 matched cohort of 4667 nonunions of 13,981 fractures for familial clustering analysis. Cox proportional hazards did not demonstrate excessive risk of nonunion among first- ( P = 0.863), second- ( P = 0.509), and third-degree relatives ( P = 0.252). Further analysis of the entire cohort demonstrated that male sex (relative risk [RR] = 1.15; P < 0.001), Medicaid enrollment (RR = 2.64; P < 0.001), open fracture (RR = 2.53; P < 0.001), age group 41-60 years (RR = 1.43; P < 0.001), and a history of obesity (RR = 1.20; P < 0.001) were independent risk factors for nonunion.

CONCLUSIONS

Our results demonstrate no evidence of heritable risk for nonunion. Independent risk factors for nonunion were male sex, Medicaid enrollment, open fracture, middle age, and a history of obesity. Although it is important to identify modifiable and nonmodifiable risk factors, these results continue to support that the risk of nonunion is multifactorial, relating to injury characteristics, operative techniques, and patient-specific risk factors.

LEVEL OF EVIDENCE

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

Risk factors and healthcare costs associated with long bone fracture non-union: a retrospective US claims database analysis

BACKGROUND

Few contemporary US-based long bone non-union analyses have recently been published. Our study was designed to provide a current understanding of non-union risks and costs, from the payers' perspective.

METHODS

The Merative™ MarketScan® Commercial Claims and Encounters database was used. Patients with surgically treated long bone (femur, tibia, or humerus) fractures in the inpatient setting, from Q4 2015 to most recent, were identified. Exclusion criteria included polytrauma and amputation at index. The primary outcome was a diagnosis of non-union in the 12 and 24 months post-index. Additional outcomes included concurrent infection, reoperation, and total healthcare costs. Age, gender, comorbidities, fracture characteristics, and severity were identified for all patients. Descriptive analyses were performed. Crude and adjusted rates of non-union (using Poisson regressions with log link) were calculated. Marginal incremental cost of care associated with non-union and infected non-union and reoperation were estimated using a generalized linear model with log link and gamma distribution.

RESULTS

A total of 12,770, 13,504, and 4,805 patients with femoral, tibial, or humeral surgically treated fractures were identified, 74-89% were displaced, and 18-27% were comminuted. Two-year rates of non-union reached 8.5% (8.0%-9.1%), 9.1% (8.6%-9.7%), and 7.2% (6.4%-8.1%) in the femoral, tibial, and humeral fracture cohorts, respectively. Shaft fractures were at increased risk of non-union versus fractures in other sites (risk ratio (RR) in shaft fractures of the femur: 2.36 (1.81-3.04); tibia: 1.95 (1.47-2.57); humerus: 2.02 (1.42-2.87)). Fractures with severe soft tissue trauma (open vs. closed, Gustilo III vs. Gustilo I-II) were also at increased risk for non-union (RR for Gustilo III fracture (vs. closed) for femur: R = 1.96 (1.45-2.58), for tibia: 3.33 (2.85-3.87), RR for open (vs. closed) for humerus: 1.74 (1.30-2.32)). For all fractures, younger patients had a reduced risk of non-union compared to older patients. For tibial fractures, increasing comorbidity (Elixhauser Index 5 or greater) was associated with an increased risk of non-union. The two-year marginal cost of non-union ranged from $33K-$45K. Non-union reoperation added $16K-$34K in incremental costs. Concurrent infection further increased costs by $46K-$86K.

CONCLUSIONS

Non-union affects 7-10% of surgically treated long bone fracture cases. Shaft and complex fractures were at increased risk for non-union.

The Radiographic Union Score for ulnar fractures (RUSU) predicts ulnar shaft nonunion

AIMS

To develop a reliable and effective radiological score to assess the healing of isolated ulnar shaft fractures (IUSF), the Radiographic Union Score for Ulna fractures (RUSU).

METHODS

Initially, 20 patients with radiographs six weeks following a non-operatively managed ulnar shaft fracture were selected and scored by three blinded observers. After intraclass correlation (ICC) analysis, a second group of 54 patients with radiographs six weeks after injury (18 who developed a nonunion and 36 who united) were scored by the same observers.

RESULTS

In the initial study, interobserver and intraobserver ICC were 0.89 and 0.93, respectively. In the validation study, the interobserver ICC was 0.85. The median score for patients who united was significantly higher than those who developed a nonunion (11 vs. 7, p < 0.001). A ROC curve demonstrated that a RUSU ≤ 8 had a sensitivity of 88.9% and specificity of 86.1% in identifying patients at risk of nonunion. Patients with a RUSU ≤ 8 (n = 21) were more likely to develop a nonunion (n = 16/21) than those with a RUSU ≥ 9 (n = 2/33; OR 49.6, 95% CI 8.6-284.7). Based on a PPV of 76%, if all patients with a RUSU ≤ 8 underwent fixation at 6 weeks, the number of procedures needed to avoid one nonunion would be 1.3.

CONCLUSION

The RUSU shows good interobserver and intraobserver reliability and is effective in identifying patients at risk of nonunion six weeks after fracture. This tool requires external validation but may enhance the management of patients with isolated ulnar shaft fractures.

Segmental defect healing in the presence or absence of recombinant human BMP2: Novel insights from a rat model

This study defined and compared the course of native, impaired and growth factor-stimulated bone regeneration in a rat femoral defect model. A mid-diaphyseal defect with rigid internal fixation was surgically created in the right femur of male Fischer rats and serially analyzed over 36 weeks. Native bone regeneration was modeled using a sub-critical, 1 mm size defect, which healed uneventfully. Critical size defects of 5 mm were used to analyze impaired bone regeneration. In a third group, the 5 mm defects were filled with 11 µg of recombinant human bone morphogenetic protein 2 (rhBMP2) impregnated onto an absorbable collagen sponge, modeling its clinical use. Native bone regeneration was characterized by endochondral ossification with progressive remodeling to ultimately resemble intact femora. An endochondral response was also observed under conditions of impaired bone regeneration, but by week 8 medullary capping occurred with fibrofatty consolidation of the tissue within the defect, resembling an atrophic non-union. rhBMP2 treatment was associated with prolonged inflammatory cytokine expression and rapid intramembranous bone formation occurring with reduced expression of cartilage-associated collagens. Between weeks 4 and 36, rhBMP2-treated bones demonstrated decreased trabecular number and increased trabecular separation, which resulted in inferior mechanical properties compared with bones that healed naturally. Clinical Significance: Recombinant human bone morphogenetic protein 2 (rhBMP2) is used clinically to promote healing of long bones. Our data suggest that it drives intramembraneous ossification producing an inferior regenerate that deteriorates with time. Clinical outcomes would be improved by technologies favoring endochondral regenerative ossification.

Del1 Is a Growth Factor for Skeletal Progenitor Cells in the Fracture Callus

Failure to properly form bone or integrate surgical implants can lead to morbidity and additional surgical interventions in a significant proportion of orthopedic surgeries. While the role of skeletal stem cells (SSCs) in bone formation and repair is well-established, very little is known about the factors that regulate the downstream Bone, Cartilage, Stromal, Progenitors (BCSPs). BCSPs, as transit amplifying progenitor cells, undergo multiple mitotic divisions to expand the pool of lineage committed progenitors allowing stem cells to preserve their self-renewal and stemness. Del1 is a protein widely expressed in the skeletal system, but its deletion led to minimal phenotype changes in the uninjured mouse. In this paper, we demonstrate that Del1 is a key regulator of BCSP expansion following injury. In Del1 knockout mice, there is a significant reduction in the number of BCSPs which leads to a smaller callus and decreased bone formation compared with wildtype (WT) littermates. Del1 serves to promote BCSP proliferation and prevent apoptosis in vivo and in vitro. Moreover, exogenous Del1 promotes proliferation of aged human BCSPs. Our results highlight the potential of Del1 as a therapeutic target for improving bone formation and implant success. Del1 injections may improve the success of orthopedic surgeries and fracture healing by enhancing the proliferation and survival of BCSPs, which are crucial for generating new bone tissue during the process of bone formation and repair.

Shear's role in non-union. Measuring mean angle of long bone multi-fragmentary non-unions

INTRODUCTION

Both mechanical and biological theories have been proposed in the development of non-union. The mechanical theory suggests that a high strain environment in a fracture will predispose it to non-union. While in simple fractures and wedge fractures there are only one and two primary fracture planes respectively, in multi-fragmentary fractures there are many and a non-union may form along any of the original fracture lines, however the plane which experiences the highest strain is at 45O - the shear plane. We hypothesise that in multi-fragmentary fractures the initial fracture line that most often fails to unite will tend towards the plane with the highest strain.

OBJECTIVES

1) Define the mean non-union angle in a cohort of multi-fragmentary tibial and femoral fractures. 2) In wedge-like fractures within the cohort, define and compare the mean angle of initial fracture planes which go on to form a non-union to those that unite 3) In comminuted fractures within the cohort, define the mean non-union angle DESIGN: Retrospective cohort study SETTING: Level-1 trauma centre METHODOLOGY: Fractures were categorised into wedge-like and comminuted. A published technique was utilised to measure fracture and non-union angles. In wedge-like fractures, united and non-united initial planes were compared. In comminuted fractures only the mean non-union angle was defined. Demographic patient data was also collected.

RESULTS

183 non-unions were screened, 68 patients were included. The mean non-union angle was 56°(SD 18) across all fractures. In wedge-like fractures the mean non-union angle was 59°(SD 18). In comminuted fractures the mean non-union angle was 50°(SD 19). Non-united initial fracture planes in wedge-like fractures showed a peaked distribution about a mean of 58° while united fracture planes were distributed at the extremities of the range.

CONCLUSIONS

In patients with multi-fragmentary fractures resulting in non-union, the mean tibial non-union angle was 52° while the mean femoral non-union angle was 65°. In wedge-like fractures, non-unions occurred more commonly than appropriate union in fractures between 41°-80°. The non-union angle is closer to 45° in comminuted fractures than in wedge-like fractures. These results support the mechanical theory that strain from the shear plane is an important factor in the formation of non-unions.

LEVEL OF EVIDENCE

Prognostic level 3.

The Concept of Scaffold-Guided Bone Regeneration for the Treatment of Long Bone Defects: Current Clinical Application and Future Perspective

The treatment of bone defects remains a challenging clinical problem with high reintervention rates, morbidity, and resulting significant healthcare costs. Surgical techniques are constantly evolving, but outcomes can be influenced by several parameters, including the patient's age, comorbidities, systemic disorders, the anatomical location of the defect, and the surgeon's preference and experience. The most used therapeutic modalities for the regeneration of long bone defects include distraction osteogenesis (bone transport), free vascularized fibular grafts, the Masquelet technique, allograft, and (arthroplasty with) mega-prostheses. Over the past 25 years, three-dimensional (3D) printing, a breakthrough layer-by-layer manufacturing technology that produces final parts directly from 3D model data, has taken off and transformed the treatment of bone defects by enabling personalized therapies with highly porous 3D-printed implants tailored to the patient. Therefore, to reduce the morbidities and complications associated with current treatment regimens, efforts have been made in translational research toward 3D-printed scaffolds to facilitate bone regeneration. Three-dimensional printed scaffolds should not only provide osteoconductive surfaces for cell attachment and subsequent bone formation but also provide physical support and containment of bone graft material during the regeneration process, enhancing bone ingrowth, while simultaneously, orthopaedic implants supply mechanical strength with rigid, stable external and/or internal fixation. In this perspective review, we focus on elaborating on the history of bone defect treatment methods and assessing current treatment approaches as well as recent developments, including existing evidence on the advantages and disadvantages of 3D-printed scaffolds for bone defect regeneration. Furthermore, it is evident that the regulatory framework and organization and financing of evidence-based clinical trials remains very complex, and new challenges for non-biodegradable and biodegradable 3D-printed scaffolds for bone regeneration are emerging that have not yet been sufficiently addressed, such as guideline development for specific surgical indications, clinically feasible design concepts for needed multicentre international preclinical and clinical trials, the current medico-legal status, and reimbursement. These challenges underscore the need for intensive exchange and open and honest debate among leaders in the field. This goal can be addressed in a well-planned and focused stakeholder workshop on the topic of patient-specific 3D-printed scaffolds for long bone defect regeneration, as proposed in this perspective review.

Genetic Influence of Fracture Nonunion (FNU): A Systematic Review

Purpose

Nonunion of fractures occurs in about 15% of all fractures causing repeated surgical interference and prolonged morbidity. We performed this systematic review to assess genes and polymorphisms influencing fractures' nonunion (FNU).

Methods

We searched between 2000 and July 2022 in PubMed, EMBASE, the Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews, Genome Wide Association Studies (GWAS) Catalog, and the Science Citation Index, with the keywords nonunion of fractures, genetic influence, and GWAS. The exclusion criteria were review articles and correspondence. The data were retrieved to determine the number of studies, genes, and polymorphisms and the total number of subjects screened.

Results

A total of 79 studies were reported on nonunion of fractures and genetic influence. After the inclusion and exclusion criteria, ten studies with 4402 patients' data were analyzed. Nine studies were case-controlled, and 1 GWAS. It was identified that patients with polymorphisms in the genes ANXA3, BMP2, CALY, CYR61, FGFR1, IL1β, NOG, NOS2, PDGF gene, and TACR1 are prone to develop a nonunion of fractures.

Conclusion

We believe that for patients who develop an early nonunion of fractures, a genetic study should be conducted for single nucleotide polymorphism (SNP) and genes so that alternative and more aggressive treatment can be performed to heal fractures without prolonged morbidity.

Inhibition of CGRP signaling impairs fracture healing in mice

Calcitonin gene-related peptide (CGRP) is a neuropeptide produced by sensory nerves and functions as a pain sensor. It acts by binding to the calcitonin-like receptor (CLR, protein; Calcrl, gene). CGRP inhibition has been recently introduced as therapeutic treatment of migraine-associated pain. Previous studies have shown that CGRP stimulates bone formation. The aim of our study is to determine whether the inhibition of CGRP signaling negatively impacted fracture healing. Using α-smooth muscle actin (αSMA) Cre animals crossed with Ai9 reporter mice, we showed that CGRP-expressing nerves are near αSMA + cells in the periosteum. In vitro experiments revealed that periosteal cells express Calcrl and receptor activity modifying protein 1; and CGRP stimulation increased periosteal cell proliferation. Using a tamoxifen-inducible model αSMACre/CLRfl/fl , we targeted the deletion of CLR to periosteal progenitor cells and examined fracture healing. Microcomputed tomography of fractured femurs showed a reduction in bone mass in αSMACre+/CLRfl/fl female mice relative to controls and callus volume in males. Pharmacological CGRP-CLR inhibition was achieved by subcutaneous delivery of customized pellets with small molecule inhibitor olcegepant (BIBN-4096) at a dose of 10 μg/day. BIBN-4096-treated C57BL/6J mice had a higher latency toward thermal nociception than placebo-treated mice, indicating impaired sensory function through CGRP inhibition. CGRP inhibition also resulted in reduced callus volume, bone mass, and bone strength compared to placebo controls. These results indicate that inhibiting CGRP by deleting CLR or by using BIBN-4096, contributes to delayed bone healing.

Fractures in elderly mice demonstrate delayed ossification of the soft callus: a cellular and radiographic study

OBJECTIVES

The aim of this study was to assess the cellular age-related changes in fracture repair and relate these to the observed radiographic assessments at differing time points.

METHODS

Transverse traumatic tibial diaphyseal fractures were created in 12-14 weeks old (young n = 16) and 18 months old (elderly n = 20) in Balb/C wild mice. Fracture calluses were harvested at five time points from 1 to 35 days post fracture for histomorphometry (percent of cartilage and bone), radiographic analysis (total callus volume, callus index, and relative bone mineral content).

RESULTS

The elderly mice produced an equal amount of cartilage when compared to young mice (p > 0.08). However, by day 21 there was a significantly greater percentage of bone at the fracture site in the young group (mean percentage 50% versus 11%, p < 0.001). It was not until day 35 when the elderly group produced a similar amount of bone compared to the young group at 21 days (50% versus 53%, non-significant (ns)). The callus area and callus index on radiographic assessment was not significantly different between young and elderly groups at any time point. Relative bone mineral content was significantly greater in the young group at 14 days (545.7 versus -120.2, p < 0.001) and 21 days (888.7 versus 451.0, p < 0.001) when compared to the elderly group. It was not until day 35 when the elderly group produced a similar relative bone mineral content as the young group at 21 days (888.7 versus 921.8, ns).

CONCLUSIONS

Elderly mice demonstrated a delay in endochondral ossification which was associated with a decreased relative bone mineral content at the fracture site and may help assess these cellular changes in a clinical setting.

The Cambridge Experience with Lower Limb Long Bone Non-union Following Fixation and the Treatment Algorithm

Aim

Non-unions have been traditionally classified as atrophic, oligotrophic and hypertrophic and their management was primarily dictated by that. In our Unit, we have based our treatment rationale mainly on the stability of the metalwork and the presence of symptoms rather than the radiologic appearance of the non-union or the presence of infection. The aim was to present the treatment algorithm for lower limb long bone non-union following operative fixation.

Materials and methods

All patients treated for a femoral or tibial non-union following fixation between 2014 and 2020 in our unit and with a minimum follow-up of 2 years were included. Non-union was defined as having no evidence of fracture healing in any cortices six months after the index procedure. Union was defined as bridging callus in at least three cortices visualized on at least two orthogonal radiographs. Information retrieved included demographic and fracture characteristics, presence of infection, evidence of metalwork stability and treatment. Outcome measures included union rate, time to union and complications. Data were analysed with the Statistical Program for Social Sciences (SPSS) using contingency tables and linear regression. A p-value of less than 0.05 was considered statistically significant.

Results

Seventy-seven consecutive patients were included in the study. Union was achieved in 91% of the cases, while union was noted in all the patients treated non-operatively. The mean time to union was 14.49 months (9.98). Complications were encountered in 20 of the patients and the most common were docking site non-union and metalwork breakage. Infection was the only factor that affected time to union in a statistically significant manner (p = 0.006).

Conclusion

The results of our study suggest that in cases of long bone non-union following operative fixation using signs of metalwork instability and the presence of clinical symptoms as the main indication for surgical intervention provides a satisfactory outcome. This approach prevented operative management in a large proportion of patients.

Clinical significance

This article presents an algorithmic approach that could aid clinicians in their decision-making in long-bone non-union management.

Level of evidence

Therapeutic level III.

How to cite this article

Poutoglidou F, Krkovic M. The Cambridge Experience with Lower Limb Long Bone Non-union Following Fixation and the Treatment Algorithm. Strategies Trauma Limb Reconstr 2023;18(2):100-105.

Ultrasound and shockwave therapy for acute fractures in adults

BACKGROUND

The morbidity and socioeconomic costs of fractures are considerable. The length of time to healing is an important factor in determining a person's recovery after a fracture. Ultrasound may have a therapeutic role in reducing the time to union after fracture by stimulating osteoblasts and other bone-forming proteins. This is an update of a review previously published in February 2014.   OBJECTIVES: To assess the effects of low-intensity ultrasound (LIPUS), high-intensity focused ultrasound (HIFUS) and extracorporeal shockwave therapies (ECSW) as part of the treatment of acute fractures in adults.  SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase (1980 to March 2022), Orthopaedic Proceedings, trial registers and reference lists of articles.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs including participants over 18 years of age with acute fractures (complete or stress fractures) treated with either LIPUS, HIFUS or ECSW versus a control or placebo-control.

DATA COLLECTION AND ANALYSIS

We used standard methodology expected by Cochrane. We collected data for the following critical outcomes: participant-reported quality of life, quantitative functional improvement, time to return to normal activities, time to fracture union, pain, delayed or non-union of fracture. We also collected data for treatment-related adverse events. We collected data in the short term (up to three months after surgery) and in the medium term (later than three months after surgery).   MAIN RESULTS: We included 21 studies, involving 1543 fractures in 1517 participants; two studies were quasi-RCTs. Twenty studies tested LIPUS and one trial tested ECSW; no studies tested HIFUS. Four studies did not report any of the critical outcomes. All studies had unclear or high risk of bias in at least one domain. The certainty of the evidence was downgraded for imprecision, risk of bias and inconsistency. LIPUS versus control (20 studies, 1459 participants) We found very low-certainty evidence for the effect of LIPUS on Health-related quality of life (HRQoL) measured by SF-36 at up to one year after surgery for lower limb fractures (mean difference (MD) 0.06, 95% confidence interval (CI) -3.85 to 3.97, favours LIPUS; 3 studies, 393 participants). This result was compatible with a clinically important difference of 3 units with both LIPUS or control. There may be little to no difference in time to return to work after people had complete fractures of the upper or lower limbs (MD 1.96 days, 95% CI -2.13 to 6.04, favours control; 2 studies, 370 participants; low-certainty evidence).  There is probably little or no difference in delayed union or non-union up to 12 months after surgery (RR 1.25, 95% CI 0.50 to 3.09, favours control; 7 studies, 746 participants; moderate-certainty evidence). Although data for delayed and non-union included both upper and lower limbs, we noted that there were no incidences of delayed or non-union in upper limb fractures. We did not pool data for time to fracture union (11 studies, 887 participants; very low-certainty evidence) because of substantial statistical heterogeneity which we could not explain. In upper limb fractures, MDs ranged from 0.32 to 40 fewer days to fracture union with LIPUS. In lower limb fractures, MDs ranged from 88 fewer days to 30 more days to fracture union. We also did not pool data for pain experienced at one month after surgery in people with upper limb fractures (2 studies, 148 participants; very low-certainty evidence) because of substantial unexplained statistical heterogeneity. Using a 10-point visual analogue scale, one study reported less pain with LIPUS (MD -1.7, 95% CI -3.03 to -0.37; 47 participants), and the effect was less precise in the other study (MD -0.4, 95% CI -0.61 to 0.53; 101 participants). We found little or no difference in skin irritation (a possible treatment-related adverse event) between groups but judged the certainty of the evidence from this small study to be very low (RR 0.94, 95% CI 0.06 to 14.65; 1 study, 101 participants). No studies reported data for functional recovery. Data for treatment adherence were inconsistently reported across studies, but was generally described to be good. Data for costs were reported for one study, with higher direct costs, as well as combined direct and indirect costs, for LIPUS use. ECSW versus control (1 study, 56 participants) We are uncertain whether ECSW reduces pain at 12 months after surgery in fractures of the lower limb (MD -0.62, 95% CI -0.97 to -0.27, favours ECSW); the difference between pain scores was unlikely to be clinically important, and the certainty of the evidence was very low. We are also uncertain of the effect of ECSW on delayed or non-union at 12 months because the certainty of this evidence is very low (RR 0.56, 95% CI 0.15 to 2.01; 1 study, 57 participants). There were no treatment-related adverse events. This study reported no data for HRQoL, functional recovery, time to return to normal activities, or time to fracture union. In addition, no data were available for adherence or cost.

AUTHORS' CONCLUSIONS

We were uncertain of the effectiveness of ultrasound and shock wave therapy for acute fractures in terms of patient-reported outcome measures (PROMS), for which few studies reported data. It is probable that LIPUS makes little or no difference to delayed union or non-union. Future trials should be double-blind, randomised, placebo-controlled trials recording validated PROMs and following up all trial participants. Whilst time to union is difficult to measure, the proportion of participants achieving clinical and radiographic union at each follow-up point should be ascertained, alongside adherence with the study protocol and cost of treatment in order to better inform clinical practice.

Exosomes Derived from Adipose Stem Cells Enhance Bone Fracture Healing via the Activation of the Wnt3a/β-Catenin Signaling Pathway in Rats with Type 2 Diabetes Mellitus

Nonunion and delayed union are common complications of diabetes mellitus that pose a serious health threat to people. There are many approaches that have been used to improve bone fracture healing. Recently, exosomes have been regarded as promising medical biomaterials for improving fracture healing. However, whether exosomes derived from adipose stem cells can promote bone fracture healing in diabetes mellitus remains unclear. In this study, adipose stem cells (ASCs) and exosomes derived from adipose stem cells (ASCs-exos) are isolated and identified. Additionally, we evaluate the in vitro and in vivo effects of ASCs-exos on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and bone repair and the regeneration in a rat model of nonunion via Western blotting, immunofluorescence assay, ALP staining, alizarin red staining, radiographic examination and histological analysis. Compared with controls, ASCs-exos promoted BMSC osteogenic differentiation. Additionally, the results of Western blotting, radiographic examination and histological analysis show that ASCs-exos improve the ability for fracture repair in the rat model of nonunion bone fracture healing. Moreover, our results further proved that ASCs-exos play a role in activating the Wnt3a/β-catenin signaling pathway, which facilitates the osteogenic differentiation of BMSCs. All these results show that ASCs-exos enhance the osteogenic potential of BMSCs by activating the Wnt/β-catenin signaling pathway, and also facilitate the ability for bone repair and regeneration in vivo, which provides a novel direction for fracture nonunion in diabetes mellitus treatment.

Development and evaluation of local regenerative biomimetic bone-extracellular matrix scaffold loaded with nano-formulated quercetin for orthopedic fractures

The prevalence of bone injuries is greatly increasing each year and the proper healing of fractures without any complications is very challenging. Self-setting calcium phosphate cements (CPCs) have attracted great attention as bioactive synthetic bone substitutes. Quercetin (QT) is a multipurposed drug with reported bone-conserving properties. The loading of QT and QT-phospholipid complex within nanostructured lipid carriers (NLC) was proposed to overcome the poor physical properties of the drug and to introduce the use of bioactive excipients as phospholipids and olive oil. The aim of this work was to formulate a regenerative scaffold loaded with nano-formulated QT for local treatment of orthopedic fractures. For the first time, scaffolds composed of brushite CPC were prepared and loaded with quercetin lipid nano-systems. In vitro tests proved that the addition of lipid nano-systems did not deteriorate the properties of CPC where QT-NLC/CPC showed an adequate setting time, appropriate compressive strength, and porosity. The scanning electron microscope confirmed maintenance of nanoparticles integrity within the cement. Using a rat femur bone defect animal model, the histological results showed that the QT-NLC/CPC had a superior bone healing potential compared to crude unformulated QT/CPC. In conclusion, QT-NLC /CPC are promising lipid nano-composite materials that could enhance bone regeneration.

Recombinant human bone morphogenetic protein is a valid alternative to autologous bone graft for long bone non-unions: a systematic review and meta-analysis

OBJECTIVE

To compare the efficacy of recombinant human bone morphogenetic proteins (rhBMPs) and autologous bone graft (ABG) on the healing of long bone non-union.

METHODS

A systematic literature search was conducted on PubMed, Web of Science, Cochrane Library, and CNKI up to December 2021. Two authors independently screened the studies, extracted data, and assessed the quality of the trials. A Meta-analysis was performed using state software (version 12.0).

RESULTS

A total of 14 studies were included in this meta-analysis. Overall, there was no significant difference between the rhBMPs group and the ABG group in terms of healing rate (RR = 1.04, 95% CI = 0.96-1.12, p = 0.365) and healing time (SMD = -0.31, 95% CI = -0.76-0.14, p = 0.175). Subgroup analysis showed rhBMPs lead to higher healing rates (RR = 1.35, 95% CI = 1.17-1.56, p < 0.001), and shorter healing time (SMD = -0.65, 95% CI = -1.08 to -0.22, p = 0.003) in the subgroup of moderate-quality studies. Sensitivity analysis proved that our conclusions were relatively robust. No significant publication bias was recognized in all studies (Begg's test, p = 0.193; Egger's test, p = 0.307).

CONCLUSIONS

RhBMPs or combined with allografts bone, inorganic bone was a valid alternative to ABG for the treatment of long bone non-union.

Low-Intensity Pulsed Ultrasound Treatment for Non-unions of Long Bone Fractures in a Scottish District General Hospital

OBJECTIVE

Despite advances in treatment, the management of fracture non-union remains a challenging and complex problem in orthopaedics. Low-intensity pulsed ultrasound (LIPUS) treatment has been shown to be an effective, non-invasive, affordable treatment option. This treatment was evaluated in a Scottish district hospital over a nine-year period, which included the COVID-19 pandemic.

MATERIALS AND METHODS

This submission describes a case series at Dr Gray's Hospital in Scotland, 18 patients in whom fracture non-union was treated using LIPUS.

RESULTS

An overall healing rate of 94% was achieved. Exogen™ (Bioventus LLC, NC, USA) proved to be most successful in oligotrophic non-union. No observed patient demographic appeared predictive of outcome. LIPUS treatment failed in one case. No significant adverse effects of LIPUS were detected.

CONCLUSION

LIPUS represents a useful, cost-effective potential alternative to revision surgery. LIPUS may therefore be the preferred treatment when surgical intervention and face-to-face interactions are to be minimised, as during the COVID-19 pandemic.

Microgel-Assisted Delivery of Adenosine to Accelerate Fracture Healing

Extracellular adenosine plays a key role in promoting bone tissue formation. Local delivery of adenosine could be an effective therapeutic strategy to harness the beneficial effect of extracellular adenosine on bone tissue formation following injury. Herein, we describe the development of an injectable in situ curing scaffold containing microgel-based adenosine delivery units. The two-component scaffold includes adenosine-loaded microgels and functionalized hyaluronic acid (HA) molecules. The microgels were generated upon copolymerization of 3-acrylamidophenylboronic acid (3-APBA)- and 2-aminoethylmethacrylamide (2-AEMA)-conjugated HA (HA-AEMA) in an emulsion suspension. The PBA functional groups were used to load the adenosine molecules. Mixing of the microgels with the HA polymers containing clickable groups, dibenzocyclooctyne (DBCO) and azide (HA-DBCO and HA-Azide), resulted in a 3D scaffold embedded with adenosine delivery units. Application of the in situ curing scaffolds containing adenosine-loaded microgels following tibial fracture injury showed improved bone tissue healing in a mouse model as demonstrated by the reduced callus size, higher bone volume, and increased tissue mineral density compared to those treated with the scaffold without adenosine. Overall, our results suggest that local delivery of adenosine could potentially be an effective strategy to promote bone tissue repair.

Arginine Availability in Reamed Intramedullary Aspirate as Predictor of Outcome in Nonunion Healing

Fracture healing and nonunion development are influenced by a range of biological factors. Adequate amino acid concentrations, especially arginine, are known to be important during normal bone healing. We hypothesize that bone arginine availability in autologous bone marrow grafting, when using the reamer-irrigator-aspirator (RIA) procedure, is a marker of bone healing capacity in patients treated for nonunion. Seventeen patients treated for atrophic long bone nonunion by autologous bone grafting by the RIA procedure were included and divided into two groups, successful treatment of nonunion and unsuccessful, and were compared with control patients after normal fracture healing. Reamed bone marrow aspirate from a site distant to the nonunion was obtained and the amino acids and enzymes relevant to arginine metabolism were measured. Arginine and ornithine concentrations were higher in patients with successful bone healing after RIA in comparison with unsuccessful healing. Ornithine concentrations and arginase-1 expression were lower in all nonunion patients compared to control patients, while citrulline concentrations were increased. Nitric oxide synthase 2 (Nos2) expression was significantly increased in all RIA-treated patients, and higher in patients with a successful outcome when compared with an unsuccessful outcome. The results indicate an influence of the arginine-nitric oxide metabolism in collected bone marrow, on the outcome of nonunion treatment, with indications for a prolonged inflammatory response in patients with unsuccessful bone grafting therapy. The determination of arginine concentrations and Nos2 expression could be used as a predictor for the successful treatment of autologous bone grafting in nonunion treatment.

A Comparative Study of Treatment With External Fixator Versus Antibiotic Coated Intramedullary Nail in Infected Non-union Long Bones

Introduction: Infected non-union of bones shows problems in providing stability and controlling the infection. The treatment comprises debridement with or without the use of antibiotic cement and achieving stability by either external or internal fixation with or without bone grafting. The use of antibiotic-impregnated cement-coated intramedullary nailing gives stability and treats the infection, thereby permitting early mobilization. External fixation is a definitive mode of fracture stabilization indicated in cases of infected non-unions of the humerus, tibia, and juxta-articular bone. The present study was conducted to compare the results of management of infected non-union long bones treated with an external fixator (Ilizarov and Limb Reconstruction System (LRS)) and vancomycin-coated intramedullary nail.

Materials and method: The present prospective study was conducted on 40 study subjects aged >18 years, and were randomly divided using the alternative method into two groups. Group A: 20 Patients were treated with antibiotic-coated intramedullary interlocking nail (ACIIN). Group B: 20 patients were treated with the external fixator (LRS/Ilizarov). All patients were then evaluated post-operatively using laboratory investigations, and for any sign of inflammation or infection. Results were evaluated using association for the study and application of methods of Ilizarov (ASAMI) scoring system. Data were analyzed using the Statistical Package for Social Sciences (SPSS) version 20 (IBM Corp., Armonk, NY, USA).

Results: It was observed that 80.0% of patients in Group A, and 70% of subjects in Group B showed bony union, revealing a statistically significant (p-value<0.05) difference. Infection control, limb length discrepancy, and deformity were also assessed in both groups. Bone and functional outcomes were assessed using the ASAMI score in both groups. In LRS/Ilizarov, it was observed that 55% of subjects had no infection, 15% showed loosening, and 30% had an infection.

Conclusion: The ACIIN should not be used for bone defects more than 4 cm as it does not achieve stability and for these cases, procedures like external fixators (Ilizarov and LRS) should be used. Antibiotic-coated nail eliminated the complications of the external fixators like pin loosening, and pin infections and was technically less demanding. In our study, stiffness of adjacent joints was more in external fixators (LRS/Ilizarov) than ACIIN.

Contemporary management of aseptic diaphyseal tibia non-unions - A systematic review

INTRODUCTION

Tibia fractures are the most common long bone injuries encountered in the trauma population. The majority are treated successfully but non-union remains a common complication. A systematic review of current evidence regarding the management for aseptic diaphyseal tibial non-unions was undertaken.

METHODS

A systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA), was conducted.

RESULTS

A total of 632 publications were screened for inclusion. Full text review of 91 studies resulted in 26 publications being retained for final review. The majority of patients included in the studies either underwent exchange nailing (n=315) or primary intramedullary nailing (n=174) with respective union rates of 88% and 95% being achieved. The highest union rate (97%) was achieved with the use of fine wire external fixation. The major adjuvant treatment modalities were fibula osteotomies (n=372; 41%), fixation dynamization (n=208; 23%) and bone grafting (n=183; 20%).

CONCLUSION

The lack of standardization in reporting of outcomes and the diversity of management strategies employed precludes definitive conclusions or recommendations. Further research is required to ascertain the ideal treatment strategy in the management of aseptic tibial diaphyseal non-unions.

LEVEL OF EVIDENCE

IV.

Percutaneous Strain Reduction Screws Are a Reproducible Minimally Invasive Method to Treat Long Bone Nonunion

OBJECTIVES

(1) Evaluate whether initial results from percutaneous treatment of nonunion are reproducible (2) Estimate the relative cost of percutaneous treatment of nonunion versus traditional methods.

DESIGN

Retrospective multicentre case series.

SETTING

Four Level 1 trauma centers.

PATIENTS/PARTICIPANTS

Fifty-one patients (34 men and 17 women) with a median age of 51 years (range 14-81) were treated for nonunion at a median of 10 months (range 4-212) from injury.

INTERVENTION

Percutaneous strain reduction screws (PSRS).

MAIN OUTCOME MEASURED

Union rates and time to union were compared for patients treated in the developing institution versus independent units as well as with previously published results.

RESULTS

Forty-five (88%) patients achieved union at a median time of 5.2 months (range 1.0-24.7) confirming the previously published results for this technique. Comparable results were seen between the developing institution and independent units. No patients experienced adverse events beyond failure to achieve union. PSRS seems to offer savings of between £3177 ($4416) to £11,352 ($15,780) per case compared with traditional methods of nonunion surgery.

CONCLUSIONS

PSRS is a safe, efficacious treatment for long bone nonunion and may be more cost-effective than traditional nonunion treatment methods. The promising initial results of this technique have now been replicated outside of the developing institution.

LEVEL OF EVIDENCE

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

IC-Type Electric stimulation for delayed bone healing: monocentric evaluation over eight years of experience

Electrostimulation is suggested to positively influence bone healing for delayed unions of both fractures and osteotomies. This monocentric series aims to retrospectively assess the outcome of electrostimulation treatment for delayed union after traumatic fractures or knee osteotomy. Patients treated with electrostimulation for delayed union (no bony union on radiographic imaging at 90 days after osteotomy or fracture treatment) over an 8-year period were screened. The delay of treatment, success rate, revision rate and demographic data (age, sex, location of fracture, presence of osteosynthesis materials) were investigated. A questionnaire assessed objective (nicotine abuse, NRS pain assessment, activity levels) and subjective (comfort, usability, cost-effectiveness) aspects. Electrostimulation delivered radiographic healing in 75% of the fracture group and 66% of the osteotomy group. No statistical significant difference (N=136) in success rate was found for age, sex, presence of osteosynthesis material, delay or fracture location. Success rate did differ significantly with pain, activity level and smoking (p<0.05). Reflective questions to patients were answered mostly positively. The use of electrostimulation for the delayed union of fractures and knee osteotomies delivers high healing rates avoiding the burden of surgical reintervention. It is generally well received by the patient. No difference in success rate was found between sex, age or fracture location, nor did the delay of therapy onset or presence of osteosynthesis material seem to affect the success rate. Smoking had a negative influence on the efficacy of bone electrostimulation.

Comparison of outcomes and operative course between septic and aseptic nonunion in long bones

PURPOSE

The treatment of nonunion of long bones is difficult particularly in the presence of infection, which often involves staged surgical management. There is limited literature to compare the post operative course and outcomes of patients treated for septic versus aseptic nonunion. Thus, the purpose of this study was to determine if a difference exists between the number of surgical procedures, time to union, and rate of successful union for these two groups.

METHODS

A retrospective cohort study was performed at a single tertiary care center. Patients suffering nonunion of the humerus, tibia and femur were included. Patient demographic data and characteristics of the post operative course were collected to include number and reason for repeat operations, antibiotic course, time to union, and development of a successful union.

RESULTS

About 28 of 122 patients had septic nonunion. After diagnosis of nonunion, the septic group averaged 3.9 surgeries compared to 1.5 in the aseptic group (p < 0.001). There was no difference in the rate of successful union (79.8% versus 85.7%; p = 0.220), though the septic group took 129 days longer on average for successful union. (376 versus 247; p = 0.018).

CONCLUSION

Septic nonunion of long bones is associated with the need for significantly more operations as well as time to union, though union rates remain similar. The identification of infection is critical for both the appropriate treatment as well as counseling patients on the expected post operative course.

The epidemiology and direct healthcare costs of aseptic nonunions in Germany - a descriptive report

Aims

This observational cross-sectional study aimed to answer the following questions: 1) how has nonunion incidence developed from 2009 to 2019 in a nationwide cohort; 2) what is the age and sex distribution of nonunions for distinct anatomical nonunion localizations; and 3) how high were the costs for surgical nonunion treatment in a level 1 trauma centre in Germany?

Methods

Data consisting of annual International Classification of Diseases (ICD)-10 diagnosis codes from German medical institutions from 2009 to 2019, provided by the Federal Statistical Office of Germany (Destatis), were analyzed. Nonunion incidence was calculated for anatomical localization, sex, and age groups. Incidence rate ratios (IRRs) were determined and compared with a two-sample z-test. Diagnosis-related group (DRG)-reimbursement and length of hospital stay were retrospectively retrieved for each anatomical localization, considering 210 patients.

Results

In 2019, a total of 11,840 nonunion cases (17.4/100,000 inhabitants) were treated. In comparison to 2018, the incidence of nonunion increased by 3% (IRR 1.03, 95% confidence interval (CI) 0.53 to 1.99, p = 0.935). The incidence was higher for male cases (IRR female/male: 0.79, 95% CI 0.76 to 0.82, p = 0.484). Most nonunions occurred at the pelvic and hip region (3.6/100,000 inhabitants, 95% CI 3.5 to 3.8), followed by the ankle and foot as well as the hand (2.9/100,000 inhabitants each). Mean estimated DRG reimbursement for in-hospital treatment of nonunions was highest for nonunions at the pelvic and hip region (€8,319 (SD 2,410), p < 0.001).

Conclusion

Despite attempts to improve fracture treatment in recent years, nonunions remain a problem for orthopaedic and trauma surgery, with a stable incidence throughout the last decade.

Cite this article: Bone Joint Res 2022;11(8):541–547.

Public Insurance Payment Does Not Compensate Hospital Cost for Care of Long-Bone Fractures Requiring Additional Surgery to Promote Union

OBJECTIVES

To quantify the total hospital costs associated with the treatment of lower extremity long-bone fracture aseptic and septic unhealed fracture, to determine if insurance adequately covers these costs, and to examine whether insurance type correlates with barriers to accessing care.

DESIGN

Retrospective cohort study.

SETTING

Academic Level II trauma center.

PATIENTS

All patients undergoing operative treatment of OTA/AO classification 31, 32, 33, 41, 42, and 43 fractures between 2012 and 2020 at a single Level II trauma center with minimum of 1-year follow-up.

MAIN OUTCOME MEASURES

The primary outcome was the total cost of treatment for all hospital-based episodes of care. Distance traveled from primary residence was measured as a surrogate for barriers to care.

RESULTS

One hundred seventeen patients with uncomplicated fracture healing, 82 with aseptic unhealed fracture, and 44 with septic unhealed fracture were included in the final cohort. The median cost of treatment for treatment of septic unhealed fracture was $148,318 [interquartile range(IQR) 87,241-256,928], $45,230 (IQR 31,510-68,030) for treatment of aseptic unhealed fracture, and $33,991 (IQR 25,609-54,590) for uncomplicated fracture healing. The hospital made a profit on all patients with commercial insurance, but lost money on all patients with public insurance. Among patients with unhealed fracture, those with public insurance traveled 4 times further for their care compared with patients with commercial insurance (P = 0.004).

CONCLUSIONS

Septic unhealed fracture of lower extremity long-bone fractures is an outsized burden on the health care system. Public insurance for both septic and aseptic unhealed fracture does not cover hospital costs. The increased distances traveled by our Medi-Cal and Medicare population may reflect the economic disincentive for local hospitals to care for publicly insured patients with unhealed fractures.

LEVEL OF EVIDENCE

Economic Level V. See Instructions for Authors for a complete description of levels of evidence.

Is Atrophic Nonunion a Misnomer - A Hospital-based Prospective Cross-Sectional Study

Objective  The present study was conducted to estimate histologically the proportion of avascularity of fracture ends in case of nonunion of long bones. Methods  A total of 15 cases of established quiescent nonunion were operated according to the standard protocol and the fracture ends were evaluated histologically. The biopsied tissue was briefly fixed with formalin, embedded with paraffin (FFPE), and 5-micron sections were stained with hematoxylin and eosin according to standard protocols. Immunohistochemistry with anti-CD31 antibody (JC70A clone, DBS) was performed manually using standard protocols. Results  All cases of quiescent nonunion were included; radiologically, 2 cases were oligotrophic, and 13 cases were of atrophic nonunion. A total of 20% of the patients were females, 40% were in the age group between 31and 40 years old, and, radiologically, all cases were of atrophic nonunion. All cases showed positivity for CD-31 on immunohistochemistry. The blood vessel density was category I in 13.33% of the cases and category II in 86.67% of the cases. Four cases presented with mild inflammation and two presented with moderate inflammation. The average vessel count was 10 per high power field in the age groups between 20 and 30, 31 and 40, and 41and 50 years old. The age group between 61 and 70 years old showed an average vessel count of 4 per high power field. The difference in the vessel counts of oligotrophic and atrophic nonunion was not significant. No correlation was observed in the density of vessel count and duration of nonunion Conclusion  The nomenclature for the classification of nonunion into atrophic, oligotrophic, and hypertrophic needs revision. Our findings do not support that atrophic and oligotrophic nonunion are histologically different.

Therapeutic Efficacy and Safety of Osteoinductive Factors and Cellular Therapies for Long Bone Fractures and Non-Unions: A Meta-Analysis and Systematic Review

Background: Long bone fractures display significant non-union rates, but the exact biological mechanisms implicated in this devastating complication remain unclear. The combination of osteogenetic and angiogenetic factors at the fracture site is an essential prerequisite for successful bone regeneration. The aim of this study is to investigate the results of the clinical implantation of growth factors for intraoperative enhancement of osteogenesis for the treatment of long bone fractures and non-unions. Methods: A systematic literature review search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in the PubMed and Web of Science databases from the date of inception of each database through to 10 January 2022. Specific inclusion and exclusion criteria were applied in order to identify relevant studies reporting on the treatment of upper and lower limb long bone non-unions treated with osteoinductive or cellular factors. Results: Overall, 18 studies met the inclusion criteria and examined the effectiveness of the application of Bone Morphogenetic Proteins-2 and -7 (BMPs), platelet rich plasma (PRP) and mesenchymal stem cells (MSCs). Despite the existence of limitations in the studies analysed (containing mixed groups of open and close fractures, different types of fractures, variability of treatment protocols, different selection criteria and follow-up periods amongst others), their overall effectiveness was found significantly increased in patients who received them compared with the controls (I² = 60%, 95% CI = 1.59 [0.99–2.54], Z =1.93, p = 0.05). Conclusion: Administration of BMP-2 and -7, PRP and MSCs were considered effective and safe methods in fracture treatment, increasing bone consolidation, reducing time to repair and being linked to satisfactory postoperative functional scores.

Injectable Thermosensitive Chitosan-Collagen Hydrogel as A Delivery System for Marine Polysaccharide Fucoidan

Fucoidans, sulfated polysaccharides from brown algae, possess multiple bioactivities in regard to osteogenesis, angiogenesis, and inflammation, all representing key molecular processes for successful bone regeneration. To utilize fucoidans in regenerative medicine, a delivery system is needed which temporarily immobilizes the polysaccharide at the injured site. Hydrogels have become increasingly interesting biomaterials for the support of bone regeneration. Their structural resemblance with the extracellular matrix, their flexible shape, and capacity to deliver bioactive compounds or stem cells into the affected tissue make them promising materials for the support of healing processes. Especially injectable hydrogels stand out due to their minimal invasive application. In the current study, we developed an injectable thermosensitive hydrogel for the delivery of fucoidan based on chitosan, collagen, and β-glycerophosphate (β-GP). Physicochemical parameters such as gelation time, gelation temperature, swelling capacity, pH, and internal microstructure were studied. Further, human bone-derived mesenchymal stem cells (MSC) and human outgrowth endothelial cells (OEC) were cultured on top (2D) or inside the hydrogels (3D) to assess the biocompatibility. We found that the sol-gel transition occurred after approximately 1 min at 37 °C. Fucoidan integration into the hydrogel had no or only a minor impact on the mentioned physicochemical parameters compared to hydrogels which did not contain fucoidan. Release assays showed that 60% and 80% of the fucoidan was released from the hydrogel after two and six days, respectively. The hydrogel was biocompatible with MSC and OEC with a limitation for OEC encapsulation. This study demonstrates the potential of thermosensitive chitosan-collagen hydrogels as a delivery system for fucoidan and MSC for the use in regenerative medicine.

Outcomes of the Treatment of Fracture Non-union Using Combined Magnetic Field Bone Growth Stimulation: Experiences From a UK Trauma Unit

Introduction: Fracture non-union is a distressing diagnosis for both patients and clinicians. Several methods have been tried to help promote bone healing. Some of the non-operative strategies include the use of pulsed ultrasound and electrical or magnetic bone stimulators. This study aimed at assessing the outcomes of patients treated with combined magnetic field (CMF) bone stimulators.

Methods: All patients with confirmed fracture non-union treated using a CMF bone growth stimulator between May 2019 and December 2021 were included in the study. These were followed up at regular three-month intervals and monitored for signs of clinical and radiological union. The minimum patient follow-up was six months. Our primary outcome measure was union rates following CMF treatment. The secondary outcome measures were time to union and fracture type/configuration in relation to non-union.

Results: A total of 29 patients were included. Of the patients, 52% were female. The average age of the patients was 53.42 years (SD: 17.66 years). Four were excluded because their follow-up period was less than six months. Patients were started on CMF bone growth stimulant treatment between four and 27 months from the initial fracture (mean: 11.56 months). The majority of the patients had tibial shaft (21%), distal femur (17%), ankle (10%) and distal humerus (10%) fractures. The overall success rate was 84% (n=21), with a mean time to union of 6.62 months.

Conclusion: Bone growth stimulators using combined magnetic fields are a viable treatment option for established fracture non-union. They can result in improved outcomes and can avoid risks and costs associated with surgical options to treat non-union. However, more studies need to be conducted to establish the efficacy of these methods conclusively.

Nonunions and Their Operative Treatment

BACKGROUND

Nonunions, which arise as a complication of fractures, are an impor - tant medical and socio-economic problem. The goal of this study was to analyze nonunions in Germany with respect to the patients' age and sex, the anatomical site of the lesions, and their operative treatment.

METHODS

The study was performed on the basis of DRG (diagnosis-related group) data acquired for billing purposes and collected by the German Federal Statistical Office. The administrative frequencies of nonunions and fractures treated in the inpatient setting, broken down by sex and age group, were calculated from the documentation of ICD codes. An investigation was also made of surgical treatments for nonunion, as they were categorized by the German procedure classification (Operationen- und Prozedurenschlüssel, OPS).

RESULTS

The administrative frequency of nonunion was 14.84 per 100 000 persons per year, with a 2% decline in case numbers over the period 2007-2019. Nonunions develop in 2% of fractures. Nonunions affect men more often than women (58% vs. 42%). In men, their incidence as a function of age is highest under age 30; in women, it rises steadily with increasing age. The most common type of surgical treatment is a combination of resection, bone transplantation, and osteosynthesis.

CONCLUSION

This is the first detailed nationwide study of diagnoses of nonunions in Germany and their surgical treatment. Despite a slow decline in their incidence, nonunions remain an important problem in the inpatient setting. The risk profile for nonunions is sex-, age-, and site-specific.

Biological and molecular profile of fracture non-union tissue: A systematic review and an update on current insights

Fracture non‐union represents a common complication, seen in 5%–10% of all acute fractures. Despite the enhancement in scientific understanding and treatment methods, rates of fracture non‐union remain largely unchanged over the years. This systematic review investigates the biological, molecular and genetic profiles of both (i) non‐union tissue and (ii) non–union‐related tissues, and the genetic predisposition to fracture non‐union. This is crucially important as it could facilitate earlier identification and targeted treatment of high‐risk patients, along with improving our understanding on pathophysiology of fracture non‐union. Since this is an update on our previous systematic review, we searched the literature indexed in PubMed Medline; Ovid Medline; Embase; Scopus; Google Scholar; and the Cochrane Library using Medical Subject Heading (MeSH) or Title/Abstract words (non‐union(s), non‐union(s), human, tissue, bone morphogenic protein(s) (BMPs) and MSCs) from August 2014 (date of our previous publication) to 2 October 2021 for non‐union tissue studies, whereas no date restrictions imposed on non–union‐related tissue studies. Inclusion criteria of this systematic review are human studies investigating the characteristics and properties of non‐union tissue and non–union‐related tissues, available in full‐text English language. Limitations of this systematic review are exclusion of animal studies, the heterogeneity in the definition of non‐union and timing of tissue harvest seen in the included studies, and the search term MSC which may result in the exclusion of studies using historical terms such as ‘osteoprogenitors’ and ‘skeletal stem cells’. A total of 24 studies (non‐union tissue: n = 10; non–union‐related tissues: n = 14) met the inclusion criteria. Soft tissue interposition, bony sclerosis of fracture ends and complete obliteration of medullary canal are commonest macroscopic appearances of non‐unions. Non‐union tissue colour and surrounding fluid are two important characteristics that could be used clinically to distinguish between septic and aseptic non‐unions. Atrophic non‐unions had a predominance of endochondral bone formation and lower cellular density, when compared against hypertrophic non‐unions. Vascular tissues were present in both atrophic and hypertrophic non‐unions, with no difference in vessel density between the two. Studies have found non‐union tissue to contain biologically active MSCs with potential for osteoblastic, chondrogenic and adipogenic differentiation. Proliferative capacity of non‐union tissue MSCs was comparable to that of bone marrow MSCs. Rates of cell senescence of non‐union tissue remain inconclusive and require further investigation. There was a lower BMP expression in non‐union site and absent in the extracellular matrix, with no difference observed between atrophic and hypertrophic non‐unions. The reduced BMP‐7 gene expression and elevated levels of its inhibitors (Chordin, Noggin and Gremlin) could potentially explain impaired bone healing observed in non‐union MSCs. Expression of Dkk‐1 in osteogenic medium was higher in non‐union MSCs. Numerous genetic polymorphisms associated with fracture non‐union have been identified, with some involving the BMP and MMP pathways. Further research is required on determining the sensitivity and specificity of molecular and genetic profiling of relevant tissues as a potential screening biomarker for fracture non‐unions.

Analysis of Risk Factors for Non-union After Surgery for Limb Fractures: A Case-Control Study of 669 Subjects

Objective: The purpose of this study was to analyze the risk factors for limb fracture non-union in order to improve non-union prevention and early detection.

Methods: A total of 223 patients with non-union after surgery for limb fractures performed at our institution from January 2005 to June 2017 were included as the case group, while a computer-generated random list was created to select 446 patients with successful bone healing after surgery for limb fractures who were treated during the same period as the control group, thus achieving a ratio of 1:2. The medical records of these patients were reviewed retrospectively. Age, sex, body mass index, obesity, smoking, alcohol, diabetes, hypertension, osteoporosis, fracture type, multiple fractures, non-steroidal anti-inflammatory drugs (NSAIDs) use, delayed weight bearing, internal fixation failure, and infection data were analyzed and compared between the two groups. A multivariate logistic regression model was constructed to determine relevant factors associated with non-union.

Results: After comparison between two groups by univariate analysis and multivariate logistic regression, we found some risk factors associated that osteoporosis (odds ratio [OR] = 3.16, 95% confidence interval [CI]: 2.05–4.89, p < 0.001), open fracture (OR = 2.71, 95%CI: 1.72–4.27, p < 0.001), NSAIDs use (OR = 2.04, 95%CI: 1.24–3.37, p = 0.005), delayed weight bearing (OR = 1.72, 95%CI: 1.08–2.74, p = 0.023), failed internal fixation (OR = 5.93, 95%CI: 2.85–12.36, p < 0.001), and infection (OR = 6.77, 95%CI: 2.92–15.69, p < 0.001) were independent risk factors for non-union after surgery for limb fractures.

Conclusions: Osteoporosis, open fracture type, NSAIDs use, delayed weight bearing, failed internal fixation, and infection were found to be the main causes of bone non-union; clinicians should, therefore, take targeted measures to intervene in high-risk groups early.

Preclinical and Clinical Amelioration of Bone Fractures with Mesenchymal Stromal Cells: a Systematic Review and Meta-Analysis

Even though reunion of bone fracture confronts clinicians, mesenchymal stromal cells (MSCs) are investigated to be curative in bone fracture. This study aimed to explore the application potential of MSCs for healing bone fractures. By inputting search terms and retrieving studies published up to March 2021, multiple databases, including PubMed, EMBASE, Web of Science, and Cochrane Library, were searched to identify eligible studies. The mean difference (MD) and 95% confidence interval (95% CI) were calculated to analyze the main results in the meta-analysis. Data analysis was performed using Engauge Digitizer 10.8 and R Software. Of the 31 articles, 26 were preclinical studies (n = 913), and 5 were clinical trials (n = 335). Preclinically, MSCs therapy significantly augmented the progress of bone regeneration [(bone volume over tissue volume (MD7.35, p < 0.01)], despite some non-significant effects (on the callus index, bone strength, work to failure, and stiffness). Clinically, the MSC group had a significantly reduced incidence of poor recovery (odds ratio (OR) 0.30, p < 0.01); however, a significant decrease in healing time was not observed in the MSC group (MD 2.47, p = 0.26). In summary, our data suggest that patients with bone fractures benefited from MSC administration and that MSCs are a potentially useful agent for bone regeneration. Despite these satisfactory outcomes, larger randomised clinical trials (RCTs) are necessary to confirm these findings.

Ablation of Proliferating Osteoblast Lineage Cells After Fracture Leads to Atrophic Nonunion in a Mouse Model

Nonunion is defined as the permanent failure of a fractured bone to heal, often necessitating surgical intervention. Atrophic nonunions are a subtype that are particularly difficult to treat. Animal models of atrophic nonunion are available; however, these require surgical or radiation-induced trauma to disrupt periosteal healing. These methods are invasive and not representative of many clinical nonunions where osseous regeneration has been arrested by a "failure of biology". We hypothesized that arresting osteoblast cell proliferation after fracture would lead to atrophic nonunion in mice. Using mice that express a thymidine kinase (tk) "suicide gene" driven by the 3.6Col1a1 promoter (Col1-tk), proliferating osteoblast lineage cells can be ablated upon exposure to the nucleoside analog ganciclovir (GCV). Wild-type (WT; control) and Col1-tk littermates were subjected to a full femur fracture and intramedullary fixation at 12 weeks age. We confirmed abundant tk+ cells in fracture callus of Col-tk mice dosed with water or GCV, specifically many osteoblasts, osteocytes, and chondrocytes at the cartilage-bone interface. Histologically, we observed altered callus composition in Col1-tk mice at 2 and 3 weeks postfracture, with significantly less bone and more fibrous tissue. Col1-tk mice, monitored for 12 weeks with in vivo radiographs and micro-computed tomography (μCT) scans, had delayed bone bridging and reduced callus size. After euthanasia, ex vivo μCT and histology showed failed union with residual bone fragments and fibrous tissue in Col1-tk mice. Biomechanical testing showed a failure to recover torsional strength in Col1-tk mice, in contrast to WT. Our data indicates that suppression of proliferating osteoblast-lineage cells for at least 2 weeks after fracture blunts the formation and remodeling of a mineralized callus leading to a functional nonunion. We propose this as a new murine model of atrophic nonunion. © 2021 American Society for Bone and Mineral Research (ASBMR).

Non-union bone fractures

The human skeleton has remarkable regenerative properties, being one of the few structures in the body that can heal by recreating its normal cellular composition, orientation and mechanical strength. When the healing process of a fractured bone fails owing to inadequate immobilization, failed surgical intervention, insufficient biological response or infection, the outcome after a prolonged period of no healing is defined as non-union. Non-union represents a chronic medical condition not only affecting function but also potentially impacting the individual's psychosocial and economic well-being. This Primer provides the reader with an in-depth understanding of our contemporary knowledge regarding the important features to be considered when faced with non-union. The normal mechanisms involved in bone healing and the factors that disrupt the normal signalling mechanisms are addressed. Epidemiological considerations and advances in the diagnosis and surgical therapy of non-union are highlighted and the need for greater efforts in basic, translational and clinical research are identified.

Surgical Site Infection Following Intramedullary Nailing of Subtrochanteric Femoral Fractures

Aim: To investigate the incidence, risk factors and pathogenic micro-organisms causing superficial and deep infection in subtrochanteric femoral fractures managed with an intramedullary nail. Materials and Methods: Following institutional board approval, all consecutive patients presenting with a subtrochanteric fracture were retrospectively identified, over an 8-year period. Basic demographics, fracture characteristics, fracture union, revision operation, mortality and other complications were reported and analysed. Variables deemed statistically significant (p-value < 0.05) were then included into a revised adjusted model of logistic regression analysis, where we reported on the odds ratio (OR). Results: The overall incidence of infection was 6.4% (n = 36/561; superficial: 3.7%; deep: 2.7%). Associations with deep infection included: non-union (OR 9.29 (2.56–3.38)), the presence of an open fracture (OR 4.23 (3.18–5.61)), the need for massive transfusion (OR 1.42 (2.39–8.39)), post-operative transfusion (OR 1.40 (1.10–1.79)) and prolonged length of stay (OR 1.04 (1.02–1.06)). The Commonest causes of superficial infection were Staphylococcus aureus (28.5%), enteric flora (23.8%) and mixed flora (23.8%); whereas coliforms (60%) and Staphylococcus aureus (26.7%) were the commonest micro-organisms isolated in deep infection. Polymicrobial infection was identified in 38.5% and 80% of superficial and deep infections, respectively. Conclusion: Causative micro-organisms identified in both superficial and deep infection were similar to those reported in post-traumatic osteomyelitis. In an attempt to minimise infection, the treating clinician should focus on modifiable risk factors with adequate patient optimisation, prompt surgical treatment, adequate antibiotic coverage and wound care when treating patients with subtrochanteric femur fracture.

Epidemiology of long bone non-unions in Spain

Epidemiological and ecological studies on long bone non-unions (NU) are scarce, based on different populations and methodologies. The aim of this study was to produce a descriptive analysis of the femur, tibia, and humerus non-union epidemiology in Spain. Methods Data were obtained from the Minimum Basic Data (Conjunto Mínimo Básico de Datos, CMBD) Hospital Discharge Database of the Spanish Ministry of Health, according to the ICD9-CM coding for diagnoses and procedures, and from the National Institute of Statistics for population, generating secondary databases with the reported cases that included the code 733.82 in a disaggregated manner, by age (categorized in 5 intervals), gender, Spanish region, and calendar year (1997-2015). Percentage of non-unions related to fractures in the previous year, annual prevalence (expressed per 100,000 person-years) and period prevalence (expressed per 100,000 person-period) were calculated by age, gender, and Spanish regions. The Odds ratio (OR) was estimated with a confidence of 95% using a logistic regression model per anatomical site. Results A mean of 235,446 fractures in all locations were annually reported in Spain from 1997 to 2015. Regarding non-union of long bones (femur, tibia and humerus), a total of 37,053 cases were found, representing a yearly mean of 1,950 cases. The proportion of long bone fractures that evolved into a non-union was 4% (1.4% femur, 1.5% tibia, and 1% humerus). The mean annual prevalence rate of NU in Spain was estimated in 4.5 (3.7-4.9) cases per 100,000 persons-year. The overall NU prevalence in Spain was estimated in 86 cases per 100,000 persons. By the type of bone, the period prevalence (per 100,000 persons-period) of the femur NU was 31, of the tibia 33, and of the humerus 22. Conclusions This description of the epidemiology of long bone non-unions in Spain confirms that the overall non-union rate has been stable from 2000 to 2015, higher in the tibia and in the femur compared to the humerus. NU occurred more frequently in aged females than in males in the femur and the humerus, while the tibia non-unions were more frequent in males and younger age.

Bone marrow aspirate concentrate/platelet-rich fibrin augmentation accelerates healing of aseptic upper limb nonunions

Introduction

Nonunions remain a significant burden in orthopedics, often afflicting young males of working age. Positive findings have been published using bone marrow aspirate concentrate (BMAC) and platelet-rich fibrin (PRF) for the treatment augmentation of lower limb nonunions. The aim of this study was to investigate if the treatment augmentation with BMAC and PRF can also accelerate the healing of nonunions of the upper limb.

Materials and methods

Sixty-eight patients (45 men, 23 women) affected by 75 nonunions of long bones of the upper limb were treated and divided into two groups. The first series was treated with standard surgery alone (group A); afterwards, the second series benefited from standard surgery with the addition of BMAC and PRF applied on lyophilized bone chips. Nonunions were classified radiographically according to the Weber–Cech method and prognostically using the Calori and Moghaddam scores. All patients were radiographically assessed at 1.5, 3, 6, 12, and 24 months of follow-up.

Results

Baseline demographic characteristics did not present differences between groups. No differences were documented in terms of complications (two in group A and three in group B). Significant differences were instead documented in terms of healing time. The first healing signs were observed 1.5 months after surgery in 90.7% of patients in group B and 34.4% of group A (p < 0.0005). At 1.5, 3, 6, and 12 months, a higher radiographic score was found for group B (all p < 0.0005), while no difference was found at final follow-up of 24 months (90.6% of group A and 97.7% of group B achieved radiological healing). Faster healing with BMAC/PRF augmentation was confirmed for all bones, as well as for the subgroup of patients affected by atrophic nonunions (p = 0.001).

Conclusion

This study showed the benefits of restoring both mechanical and biological aspects when addressing nonunions of the long bones of the upper limb. In particular, the association of BMAC and PRF to lyophilized bone chips was safe and able to accelerate healing time. These good results were confirmed for humerus, radius, and ulna sites, as well as for challenging atrophic nonunions of the upper limb.

In silico re-foundation of strain-based healing assessment of fractures treated with an external fixator

In the last decades, the literature has demonstrated a renewed interest in finding quantitative and non-invasive techniques for the assessment of bone fractures, by replacing X-ray images. Many different approaches have been proposed from ultrasounds to vibrations. This study aims to numerically assess the foundation of a method firstly proposed in 70' years, based on strain gauges measurements on external fixators for fracture healing monitoring. The theoretical basis consists in the load transfer from the fixator to the bone caused by the callus stiffening during healing. The feasibility is questioned since the level of fixator strain and its variation in invivo conditions should be high enough to be detectable by the sensors. A finite element model of a fractured tibia phantom treated with a monolateral external fixator was developed and validated experimentally. Then, this reference model was used to simulate bone healing and to investigate the sensitivity of virtual strain measurements to callus geometry and loading conditions. The analysis of load distribution among fixator components and their strain maps allowed to identify optimum strain gauges locations which resulted on the pins more distant from the callus, regardless of the simulated conditions. Even in the worst case of a very thin (3 mm) transverse callus in constrained compression conditions, the strain level (≈100 με/100 N) and its variation per week (-50 με/100 N/wk) resulted measurable in the first healing phase, before plateau conditions occurring after about 6 weeks from fixation. A thicker callus causes higher strain levels and can significantly improve measurements, whilst the callus orientation and the loading conditions have a minor effect. However, in case of a free compression loading, also the rods could provide useful indications if sensorized. The results support the method applicability in invivo conditions for the considered test case. Further investigations will be addressed to evaluate the effect of the fixator structure and configuration as well as of patient specific healing timing on the method sensitivity.

Monitoring of fracture healing. Update on current and future imaging modalities to predict union

Fracture nonunion causes considerable patient morbidity and an associated burden to society. Traditional reliance on radiographs to monitor union has limitations as bridging callus of long bone fractures can take three or more months to occur. Computed Tomographic (CT) scanning is becoming increasingly popular and can evaluate bridging callus in the late stages of healing to confirm union. The use of dynamic contrast enhanced Magnetic Resonance Imaging (MRI) and advances in nuclear imaging may yield benefits in the assessment of the infected nonunion. Emerging evidence supports the use of ultrasound to detect bridging callus prior to radiographic confirmation and it may be of use to predict patients at high risk of nonunion. This paper is part of a Supplement supported by The Osteosynthesis and Trauma Care Foundation (OTCF).