Treatment of long bone non-unions with polytherapy: indications and clinical results

Efficacy and safety of recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with autologous bone for the treatment of long bone nonunion: A report of a prospective case series

INTRODUCTION

Recombinant human Bone morphogenetic proteins have been used for the treatment of nonunions with promising results. We have been investigating both experimentally and clinically the efficacy of the rhBMP-2 with the macro / micro-porous hydroxyapatite carrier granules on the potency on the reconstruction of long bone defect. The purpose of this study was to prospectively evaluate the efficacy and safety of this specific rhBMP-2 with HA carrier granules mixed with autologous cancellous bone in patients with nonunion and bone defect resulted from the fracture related infection.

MATERIALS AND METHODS

This was a retrospective review of a prospective cohort at a university hospital. Patients diagnosed with nonunion under the definition of the United States Food and Drug Administration with bone defect after long bone fractures were enrolled from January 2020 to February 2021. We included patients with atrophic and oligotrophic nonunion, and hypertrophic nonunion with malalignment that needed to be corrected. The other patient group was consisted of segmental bone defect resulted from FRI. The maximum amount of rhBMP-2 allowed in this clinical study was 6 mg and was added to autologous bone at a 1:1 ratio. Autologous bone was added to the mixture if the volume of mixed graft was insufficient to fill the bone defect. Patients were followed 3, 6, and 12 months post-operatively. Each visit, a radiograph was taken for assessment. Visual analog scale (VAS), questionnaire for quality of life (SF-12 physical component summary [PCS], mental component summary [MCS]), and weight-bearing status were collected for functional outcome assessment. Drug safety was assessed by examining BMP-2 antibodies.

RESULTS

Of the 24 enrolled patients (mean age: 57 years), 15 (62.5 %), 2 (8.33 %), and 7 (29.17 %) presented atrophic nonunion, hypertrophic nonunion with deformity, and bone defect after fracture related infection, respectively. Thirteen patients had nonunion in the femur, 9 in the tibia, and 1 in the humerus and radius. The average amount of harvested autologous bone was 9.25 g and 4.96 mg of rhBMP-2. All 24 patients achieved union after 1-year follow up. The union rate was 95.83 % and 100 % at 6 and 12 months postoperatively, respectively. Preoperative SF-12 PCS (mean: 34.71) improved at 6 and 12 months postoperatively, respectively. Preoperative SF-12 MCS (mean: 42.89) improved 12 months postoperatively (49.13, p = 0.0338). Change of VAS was statistically significant 3 months postoperatively (p = 0.0012). No adverse effects or development of BMP-2 antibodies were observed.

CONCLUSION

BMP-2 combined with autogenous bone resulted in excellent radiographical and functional outcomes in a relatively small prospective series of patients with nonunion and bone defect, without adverse effects. Further investigations are necessary to support our finding and optimize treatment strategies in nonunion patients.

[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.

Promoting bone callus formation by taking advantage of the time-dependent fracture gap strain modulation

Delayed union and non-union of fractures continue to be a major problem in trauma and orthopedic surgery. These cases are challenging for the surgeon. In addition, these patients suffer from multiple surgeries, pain and disability. Furthermore, these cases are a major burden on healthcare systems. The scientific community widely agrees that the stability of fixation plays a crucial role in determining the outcome of osteosynthesis. The extent of stabilization affects factors like fracture gap strain and fluid flow, which, in turn, influence the regenerative processes positively or negatively. Nonetheless, a growing body of literature suggests that during the fracture healing process, there exists a critical time frame where intervention can stimulate the bone's return to its original form and function. This article provides a summary of existing evidence in the literature regarding the impact of different levels of fixation stability on the strain experienced by newly forming tissues. We will also discuss the timing and nature of this "window of opportunity" and explore how current knowledge is driving the development of new technologies with design enhancements rooted in mechanobiological principles.

Polytherapy versus monotherapy in the treatment of tibial non-unions: a retrospective study

BACKGROUND

Treating tibial non-unions efficiently presents a challenge for orthopaedic trauma surgeons. The established gold standard involves implanting autologous bone graft with adequate fixation, but the addition of biologicals according to the so-called diamond concept has become increasingly popular in the treatment of non-unions. Previous studies have indicated that polytherapy, which involves implanting mesenchymal stem cells, bioactive factors and osteoconductive scaffolds, can improve bone healing. This study aims to evaluate the efficacy of polytherapy compared with monotherapy in treating tibial non-unions of varying severity.

MATERIALS AND METHODS

Data from consecutive tibial non-unions treated between November 2014 and July 2023 were retrospectively analysed. The Non Union Scoring System (NUSS) score before non-union surgery, and the Radiographic Union Score for Tibial fractures (RUST), scored at 1, 3, 6, 9, 12 and 18 months post-surgery, were recorded. Initially, a comparison was made between the polytherapy and monotherapy groups. Subsequently, patients receiving additional surgical non-union treatment were documented, and the frequency of these treatments was tallied for a subsequent per-treatment analysis.

RESULTS

A total of 34 patients were included and divided into a polytherapy group (n = 15) and a monotherapy group (n = 19). The polytherapy group demonstrated a higher NUSS score (44 (39, 52) versus 32 (29, 43), P = 0.019, z = -2.347) and a tendency towards a higher success rate (93% versus 68%, P = 0.104) compared with the monotherapy group. For the per-treatment analysis, 44 treatments were divided into the polytherapy per-treatment group (n = 20) and the monotherapy per-treatment group (n = 24). The polytherapy per-treatment group exhibited a higher NUSS score (48 (43, 60) versus 38 (30, 50), P = 0.030, z = -2.173) and a higher success rate (95% versus 58%, P = 0.006) than the monotherapy per-treatment group. Within the monotherapy per-treatment group, the NUSS score displayed excellent predictive performance (AUC = 0.9143). Setting the threshold value at 48, the sensitivity and specificity were 100.0% and 70.0%, respectively.

CONCLUSIONS

Polytherapy is more effective than monotherapy for severe tibial non-unions, offering a higher success ratio. The NUSS score supports decision-making in treating tibial non-unions.

LEVEL OF EVIDENCE

Level III.

Fracture healing on non-union fracture model promoted by non-thermal atmospheric-pressure plasma

Non-thermal atmospheric-pressure plasma (NTAPP) is attracting widespread interest for use in medical applications. The tissue repair capacity of NTAPP has been reported in various fields; however, little is known about its effect on fracture healing. Non-union or delayed union after a fracture is a clinical challenge. In this study, we aimed to investigate how NTAPP irradiation promotes fracture healing in a non-union fracture model and its underlying mechanism, in vitro and in vivo. For the in vivo study, we created normal and non-union fracture models in LEW/SsNSlc rats to investigate the effects of NTAPP. To create a fracture, a transverse osteotomy was performed in the middle of the femoral shaft. To induce the non-union fracture model, the periosteum surrounding the fracture site was cauterized after a normal fracture model was created. The normal fracture model showed no significant difference in bone healing between the control and NTAPP-treated groups. The non-union fracture model demonstrated that the NTAPP-treated group showed consistent improvement in fracture healing. Histological and biomechanical assessments confirmed the fracture healing. The in vitro study using pre-osteoblastic MC3T3-E1 cells demonstrated that NTAPP irradiation under specific conditions did not reduce cell proliferation but did enhance osteoblastic differentiation. Overall, these results suggest that NTAPP is a novel approach to the treatment of bone fractures.

Advances with Platelet-Rich Plasma for Bone Healing

Despite significant advances in the understanding and delivery of osteosynthesis, fracture non-union remains a challenging clinical problem in orthopaedic surgery. To bridge the gap, basic science characterization of fracture healing provides a platform to identify and target biological strategies to enhance fracture healing. Of immense interest, Platelet-rich plasma (PRP) is a point of care orthobiologic that has been extensively studied in bone and soft tissue healing given its relative ease of translation from the benchtop to the clinic. The aim of this narrative review is to describe and relate pre-clinical in-vitro and in-vivo findings to clinical observations investigating the efficacy of PRP to enhance bone healing for primary fracture management and non-union treatment. A particular emphasis is placed on the heterogeneity of PRP preparation techniques, composition, activation strategies, and delivery. In the context of existing data, the routine use of PRP to enhance primary fracture healing and non-union management cannot be supported. However, it is acknowledged that extensive heterogeneity of PRP treatments in clinical studies adds obscurity; ultimately, refinement (and consensus) of PRP treatments for specific clinical indications, including repetition studies are warranted.

Biomimetic Hematoma as a Novel Delivery Vehicle for rhBMP-2 to Potentiate the Healing of Nonunions and Bone Defects

SUMMARY

The management of bone defects and nonunions creates unique clinical challenges. Current treatment alternatives are often insufficient and frequently require multiple surgeries. One promising option is bone morphogenetic protein-2 (BMP-2), which is the most potent inducer of osteogenesis. However, its use is associated with many side effects, related to the delivery and high doses necessary. To address this need, we developed an ex vivo biomimetic hematoma (BH), replicating naturally healing fracture hematoma, using whole blood and the natural coagulants calcium and thrombin. It is an autologous carrier able to deliver reduced doses of rhBMP-2 to enhance bone healing for complex fractures. More than 50 challenging cases involving recalcitrant nonunions and bone defects have already been treated using the BH delivering reduced doses of rhBMP-2, to evaluate both the safety and efficacy. Preliminary data suggest the BH is currently the only clinically used carrier able to effectively deliver reduced doses (∼70% less) of rhBMP-2 with high efficiency, rapidly and robustly initiating the bone repair cascade to successfully reconstruct complex bone injuries without side effects. The presented case provides a clear demonstration of this technology's ability to significantly alter the clinical outcome in extremely challenging scenarios where other treatment options have failed or are considered unsuitable. A favorable safety profile would portend considerable promise for BH as an alternative to bone grafts and substitutes. Although further studies regarding its clinical efficacy are still warranted, this novel approach nevertheless has tremendous potential as a favorable treatment option for bone defects, open fractures, and recalcitrant nonunions.

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.

Multicenter consensus statements on the use of low-intensity pulsed ultrasound (LIPUS) in Hand Surgery

OBJECTIVE

The purpose of this agreement was to establish consensus statements on the use of low-intensity pulsed ultrasound (LIPUS) in hand surgery.

METHODS

Based on Delphi consensus methodology, a preliminary list of questions on the use of LIPUS in hand surgery was developed by an interdisciplinary team of hand and plastic surgeons as well as psychologists and experts from communications science. Based on these, questionnaires were invented and a total of three Delphi rounds have been conducted. Delphi panelists consisted of 11 German hand surgeons with a mean experience in hand surgery of 15 years (7-23 years). Questions and statements were revised during this process, resulting in a consensus at the end of round three.

RESULTS

After three Delphi rounds, the following recommendations could be derived. LIPUS can be applied for impaired fracture healing of the digits, metacarpals, carpal bones as well as a prophylactic procedure in order to avoid further revision surgery. LIPUS therapy can be useful in addition to revision surgery for delayed union and non-unions. In the case of certain risk factors (replantation, revascularization, osteoporosis, smoking), it can be applied directly postoperatively in order to prevent impaired fracture healing. It should be applied for 90-120 days.

CONCLUSION

There is a consensus among German hand surgeons, when and how LIPUS can be applied for improving fracture healing of the hand. Randomized controlled trials with direct comparison of fracture treatment with and without LIPUS are needed to support these statements with objective data.

Bridge Plate Fixation of Distal Femur Fractures: Defining Deficient Radiographic Callus Formation and Its Associations

OBJECTIVE

To determine whether deficient early callus formation can be defined objectively based on the association with an eventual nonunion and specific patient, injury, and treatment factors.

METHODS

Final healing outcomes were documented for 160 distal femur fractures treated with locked bridge plate fixation. Radiographic callus was measured on postoperative radiographs until union or nonunion had been declared by the treating surgeon. Deficient callus was defined at 6 and 12 weeks based on associations with eventual nonunion through receiver-operator characteristic analysis. A previously described computational model estimated fracture site motion based on the construct used. Univariable and multivariable analyses then examined the association of patient, injury, and treatment factors with deficient callus formation.

RESULTS

There were 26 nonunions. The medial callus area at 6 weeks <24.8 mm 2 was associated with nonunion (12 of 39, 30.8%) versus (12 of 109, 11.0%), P = 0.010. This association strengthened at 12 weeks with medial callus area <44.2 mm 2 more closely associated with nonunion (13 of 28, 46.4%) versus (11 of 120, 9.2%), P <0.001. Multivariable logistic regression analysis found limited initial longitudinal motion (OR 2.713 (1.12-6.60), P = 0.028)) and Charlson Comorbidity Index (1.362 (1.11-1.67), P = 0.003) were independently associated with deficient callus at 12 weeks. Open fracture, mechanism of injury, smoking, diabetes, plate material, bridge span, and shear were not significantly associated with deficient callus.

CONCLUSION

Deficient callus at 6 and 12 weeks is associated with eventual nonunion, and such assessments may aid future research into distal femur fracture healing. Deficient callus formation was independently associated with limited initial longitudinal fracture site motion derived through computational modeling of the surgical construct but not more routinely discussed parameters such as plate material and bridge span. Given this, improved methods of in vivo assessment of fracture site motion are necessary to further our ability to optimize the mechanical environment for healing.

LEVEL OF EVIDENCE

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

An engineered periosteum for efficient delivery of rhBMP-2 and mesenchymal progenitor cells during bone regeneration

During bone regeneration, the periosteum acts as a carrier for key regenerative cues, delivering osteochondroprogenitor cells and crucial growth factors to the injured bone. We developed a biocompatible, 3D polycaprolactone (PCL) melt electro-written membrane to act as a mimetic periosteum. Poly (ethyl acrylate) coating of the PCL membrane allowed functionalization, mediated by fibronectin and low dose recombinant human BMP-2 (rhBMP-2) (10-25 μg/ml), resulting in efficient, sustained osteoinduction in vitro. In vivo, rhBMP-2 functionalized mimetic periosteum demonstrated regenerative potential in the treatment of rat critical-size femoral defects with highly efficient healing and functional recovery (80%-93%). Mimetic periosteum has also proven to be efficient for cell delivery, as observed through the migration of transplanted periosteum-derived mesenchymal cells to the bone defect and their survival. Ultimately, mimetic periosteum demonstrated its ability to deliver key stem cells and morphogens to an injured site, exposing a therapeutic and translational potential in vivo when combined with unprecedentedly low rhBMP-2 doses.

3D printed hybrid scaffolds for bone regeneration using calcium methoxyethoxide as a calcium source

Introduction: Hybrids consist of inorganic and organic co-networks that are indistinguishable above the nanoscale, which can lead to unprecedented combinations of properties, such as high toughness and controlled degradation. Methods: We present 3D printed bioactive hybrid scaffolds for bone regeneration, produced by incorporating calcium into our "Bouncy Bioglass", using calcium methoxyethoxide (CME) as the calcium precursor. SiO2-CaOCME/PTHF/PCL-diCOOH hybrid "inks" for additive manufacturing (Direct Ink Writing) were optimised for synergy of mechanical properties and open interconnected pore channels. Results and Discussion: Adding calcium improved printability. Changing calcium content (5, 10, 20, 30, and 40 mol.%) of the SiO2-CaOCME/PTHF/PCL-diCOOH hybrids affected printability and mechanical properties of the lattice-like scaffolds. Hybrids containing 30 mol.% calcium in the inorganic network (70S30CCME-CL) printed with 500 µm channels and 100 µm strut size achieved the highest strength (0.90 ± 0.23 MPa) and modulus of toughness (0.22 ± 0.04 MPa). These values were higher than Ca-free SiO2/PTHF/PCL-diCOOH hybrids (0.36 ± 0.14 MPa strength and 0.06 ± 0.01 MPa toughness modulus). Over a period of 90 days of immersion in simulated body fluid (SBF), the 70S30CCME-CL hybrids also kept a stable strain to failure (~30 %) and formed hydroxycarbonate apatite within three days. The extracts released by the 70S30CCME-CL hybrids in growth medium did not cause cytotoxic effects on human bone marrow stromal cells over 24 h of culture.

Single-cell RNAseq provides insight into altered immune cell populations in human fracture nonunions

Nonunion describes bone fractures that fail to heal, resulting in the fracture callus failing to fully ossify or, in atrophic cases, not forming altogether. Fracture healing is regulated, in part, by the balance of proinflammatory and anti-inflammatory processes occurring within the bone marrow and surface cell populations. We sought to further understand the role of osteoimmunology (i.e., study of the close relationship between the immune system and bone) by examining immune cell gene expression via single-cell RNA sequencing of intramedullary canal tissue obtained from human patients with femoral nonunions. Intramedullary canal tissue samples obtained by reaming were collected at the time of surgical repair for femur fracture nonunion (n = 5) or from native bone controls when harvesting autologous bone graft (n = 4). Cells within the samples were isolated and analyzed using the Chromium Single-Cell System (10x Genomics Inc.) and Illumina sequencers. Twenty-three distinct cell clusters were identified, with higher cell proportions in the nonunion samples for monocytes and CD14 + dendritic cells (DCs), and lower proportions of T cells, myelocytes, and promyelocytes in nonunion samples. Gene expression differences were identified in each of the cell clusters from cell types associated with osteoimmunology, including CD14 + DC, monocytes, T cells, promyelocytes, and myelocytes. These results provide human-derived gene profiles that can further our understanding of pathways that may be a cause or a consequence of nonunion, providing the clinical rationale to focus on specific components of osteoimmunology. Clinical significance: The novel single-cell approach may lead to clinically relevant diagnostic biomarkers during earlier stages of nonunion development and/or investigation into therapeutic options.

Long-Term Assessment of Bone Regeneration in Nonunion Fractures Treated with Compression-Resistant Matrix and Recombinant Human Bone Morphogenetic Protein-2 in Dogs

OBJECTIVE

 The aim of this study was to assess bone density, bone architecture and clinical function of canine nonunion distal appendicular long bone fractures with a defect treated with fixation, compression-resistant matrix and recombinant human bone morphogenetic protein-2 (rhBMP-2).

STUDY DESIGN

 Prospective cohort study with dogs at least 1-year post treatment. Computed tomography was performed and quantitative measurements from previous fracture sites were compared with measurements from contralateral limbs. Subjective evaluation included gait assessment and palpation.

RESULTS

 Six patients met the inclusion criteria. The rhBMP-2 treated bone exhibited higher density at the periphery and lower density in the centre, similar to the contralateral limb. All patients were weight bearing on the treated limb and all fractures were healed.

CONCLUSION

 The rhBMP-2-treated bone underwent restoration of normal architecture and density. Acceptable limb function was present in all patients. The results of this study can serve as a basis for long-term response in treating nonunion fractures in veterinary patients.

A novel bone graft technique combined with plating for aseptic recalcitrant long bone nonunion

Background

To evaluate the outcomes and efficacy of a new technique of autogenous iliac crest bone grafting combined with locking compression plate (LCP) vertical fixation for aseptic recalcitrant long bone nonunion.

Methods

From July 2010 to September 2020, 36 aseptic recalcitrant long bone nonunions were treated with a bone-forming channel technique and internal LCP fixation. All the patients had received one or more failed treatments. The injury mechanism, nonunion type and duration, and prior treatments were recorded pre-operation. The routine treatment process included nonunion area exposure, previous implant removal, sclerotic bone debridement, LCP fixation, bone-forming channel creation, and iliac bone grafting, and a second LCP fixation when required. At follow-up, X-ray images were obtained to assess bone healing and implant failure. Visual analog scale (VAS), fracture site stability, limb function, activity, muscle strength, limb length, and complications were recorded.

Results

A total of 34 patients (24 males and 10 females) were finally enrolled, with a mean age of 49.8 ± 12.3 years. At a mean follow-up of 35.6 ± 22.0 months, 32 patients displayed bone union, with a healing rate of 94.1% and mean union time of 6.8 ± 2.4 months. The VAS score was 0.7 ± 1 at the final follow-up. The functional results showed that 19 patients were excellent, 11 patients were good, 2 patients were poor, and 2 patients did not heal.

Conclusion

Bone-forming channel technique combined with LCP vertical fixation is an excellent option to treat recalcitrant long bone nonunion.

Level of evidence

Therapeutic Level IV.

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.

The effect of TLR-4 on the proliferation and differentiation of bone mesenchymal stem cells and its relationship with the Wnt signal transduction pathway during bone nonunion

Background

Bone nonunion is a special fracture complication that occurs in about 5% to 10% of cases. This type of fracture is difficult to heal, and causes great pain to patients and affects their quality of life. The mechanism of bone nonunion is not clear. In our study, we investigated the influence of Toll-like receptor (TLR)-3, TLR-4, and Wnt signaling pathways on the occurrence of bone nonunion.

Methods

Firstly, we established a Sprague Dawley (SD) rat model of femoral nonunion, and detected the expression levels of TLR-3, TLR-4, β-catenin, nemo-like kinase (NLK), c-Jun N-terminal kinase (JNK), and other proteins during model construction. For in vitro experiments, primary cultured bone mesenchymal stem cells (BMSCs) were divided into 4 groups: lipopolysaccharide (LPS, agonist of TLR-4) group, LPS + CLI095 (inhibitor of TLR-4) group, control group, and LPS + substance P (SP) group. The expression of β-catenin, NLK, JNK, and ALP and the osteogenic differentiation ability of cells were detected during culture.

Results

X-ray and hematoxylin and eosin (HE) staining results confirmed the successful modeling of bone nonunion. During the formation of the bone nonunion model, the expression of TLR-4 showed an upward trend. In vitro experiment results showed that inhibition of TLR-4 expression could enhance the proliferation and differentiation ability of BMSCs. The expression of β-catenin, the core protein of the canonical Wnt signaling pathway, increased rapidly in the first 2 weeks of bone nonunion construction, and decreased after 2 weeks. Non-canonical Wnt signaling pathway proteins NLK and JNK had no change in the first 2 weeks, and showed an upward trend after 2 weeks. In vitro experiment results showed that the expression of β-catenin was dominant in BMSCs with strong proliferation and differentiation ability, while the expression of NLK and JNK was dominant in BMSCs with weak proliferation and differentiation ability. These results suggest that the Wnt signaling pathway may regulate the occurrence of bone nonunion.

Conclusions

TLR-4 inhibits the proliferation and differentiation of BMSCs, and the transformation of the canonical Wnt signaling pathway to the non-canonical Wnt signaling pathway may lead to bone nonunion. Our study may provide new insights into the treatment of bone nonunion.

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.

What Happens on the Back Table? Viability and Osteogenic Potential of Reamed Autogenous Bone Graft as a Function of Time and Temperature-A Pilot Study

OBJECTIVES

To provide guidelines for reamed autogenous bone graft (R-ABG) in nonunion surgery to best manage modifiable intraoperative factors, like storage temperature and time, for optimal graft viability. Our hypothesis was that R-ABG graft will show decreased cell viability as a function of increased time and storage temperature.

METHODS

R-ABG samples were obtained using an RIA system from 10 patients undergoing harvest for the treatment of a nonunion. A 10 cm3 sample of cancellous bone graft was divided into 10 samples. A control sample was processed immediately and analyzed using fluorescence activated cell sorting to determine its cell viability. The remaining samples were stored at 0, 15, and 37°C and processed similarly after 60 and 120 minutes. A paired t test was used to compare the mean change in percent viability.

RESULTS

The mean percent cell viability for the experimental conditions was not significantly different from the initial percent cell viability (P ≥ 0.08). There were no significant differences in the change in mean percentage of viable cells (P ≥ 0.07). After 60 and 120 minutes of storage, there were no significant differences in mean cell viability based on storage temperature (P ≥ 0.53 and P ≥ 0.68, respectively). A power analysis estimated that a sample size of 52 patients would be needed to detect a difference.

CONCLUSIONS

The results of our pilot study indicate that storage conditions may have less effect on cell viability than previously hypothesized. Further research with more patients is needed to confirm these preliminary results.

LEVEL OF EVIDENCE

Level II.

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.

Fracture, nonunion and postoperative infection risk in the smoking orthopaedic patient: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to analyse negative effects of smoking in orthopaedic and trauma patients.

A PubMed search was carried out for studies published until July 2020 regarding effects of smoking on fracture risk, nonunion, infection after orthopaedic surgery, and persisting nonunion after scaphoid nonunion surgery. Random effects models calculated for outcome parameters, and relative risks (RR) with 95% confidence intervals are provided. No adjustments for covariates were made. Heterogeneity was assessed with Higgins’ I2, publication bias with Harbord’s p (Hp), sensitivity analysis performed on funnel plots and quality of studies was analysed using the Newcastle-Ottawa Scale.

Of 3362 retrieved entries, 69 were included in the final analysis. Unadjusted RR for smokers to develop vertebral (six studies, seven entries; RR: 1.61; p = 0.008; I2 = 89.4%), hip (11 studies, 15 entries; RR: 1.28; p = 0.007; I2 = 84.1%), and other fractures (eight studies, 10 entries; RR: 1.75; p = 0.019; I2 = 89.3%) was significantly higher. Postoperative infection risk was generally higher for smokers (21 studies; RR: 2.20; p < 0.001; I2 = 58.9%), and remained upon subgroup analysis for elective spinal (two studies; RR: 4.38; p < 0.001; I2 = 0.0%) and fracture surgery (19 studies; RR: 2.10; p < 0.001; I2 = 58.5%). Nonunion risk after orthopaedic (eight studies; RR: 2.15; p < 0.001; I2 = 35.9%) and fracture surgery (11 studies; RR: 1.85; p < 0.001; I2 = 39.9%) was significantly higher for smokers, as was persisting nonunion risk after surgery for scaphoid nonunion (five studies; RR: 3.52; p < 0.001; I2 = 0.0%). Sensitivity analysis for each model reduced heterogeneity whilst maintaining significance (all I2 < 20.0%).

Smoking has a deleterious impact on fracture incidence, and (subsequent) development of nonunions and postoperative infections.

Cite this article: EFORT Open Rev 2021;6:1006-1019. DOI: 10.1302/2058-5241.6.210058

Image Guidance-Assisted Decompression and Removal of Heterotopic Ossification Following the Use of Recombinant Human Bone Morphogenetic Protein-2 in Transforaminal Lumbar Interbody Fusion

Heterotopic ossification (HO) following the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in the setting of transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF) is a troublesome and well-described postoperative complication. There is currently no consensus regarding the treatment of this offending pathology. In this report, we present a retrospective single-surgeon review of 14 patients who underwent image-guided decompression of HO. We describe a new technique where navigation demonstrates a safe and thorough decompression compared to that with fluoroscopy or anatomical landmarks alone. To evaluate successful decompression, we reviewed patient self-reported clinical outcomes. Seven patients demonstrated positive results, while three had mixed outcomes and four showed poor outcomes. While more studies are needed to determine the overall efficacy of intraoperative navigation-assisted decompression, findings from this small cohort of patients suggest that it is a useful technique in the setting of the removal of heterotopic bone.

Systemic Administration of PTH Supports Vascularization in Segmental Bone Defects Filled with Ceramic-Based Bone Graft Substitute

Non-unions continue to present a challenge to trauma surgeons, as current treatment options are limited, duration of treatment is long, and the outcome often unsatisfactory. Additionally, standard treatment with autologous bone grafts is associated with comorbidity at the donor site. Therefore, alternatives to autologous bone grafts and further therapeutic strategies to improve on the outcome and reduce cost for care providers are desirable. In this study in Sprague–Dawley rats we employed a recently established sequential defect model, which provides a platform to test new potential therapeutic strategies on non-unions while gaining mechanistic insight into their actions. The effects of a combinatorial treatment of a bone graft substitute (HACaS+G) implantation and systemic PTH administration was assessed by µ-CT, histological analysis, and bio-mechanical testing and compared to monotreatment and controls. Although neither PTH alone nor the combination of a bone graft substitute and PTH led to the formation of a stable union, our data demonstrate a clear osteoinductive and osteoconductive effect of the bone graft substitute. Additionally, PTH administration was shown to induce vascularization, both as a single adjuvant treatment and in combination with the bone graft substitute. Thus, systemic PTH administration is a potential synergistic co-treatment to bone graft substitutes.

Endochondral Bone Tissue Engineering Using Human Induced Pluripotent Stem Cells

There has been great interest in the use of induced pluripotent stem cells (iPSCs) in bone regenerative strategies for bone defects. In the present study, we investigated whether the implantation of chondrogenically differentiated iPSC-derived mesenchymal stem cells (iMSCs) could lead to the successful regeneration of bone defects in nude mice. Two clones of human iPSCs (201B7 and 454E2) were used. After the generation of iMSCs, chondrogenic differentiation was achieved using a three-dimensional pellet culture. Then, a 2-mm defect was created in the radius of nude mice and chondrogenically differentiated iMSC pellets were placed in the defect. Micro-computed tomography (μ-CT) imaging analysis was performed 8 weeks after transplantation to assess bone regeneration. Eleven out of 11 (100%) radii in the 201B7 cell-derived-pellet transplantation group and 7 out of 10 (70%) radii in the 454E2 cell-derived-pellet transplantation group showed bone union. On the other hand, only 2 out of 11 radii (18%) in the control group showed bone union. Therefore, the bone union rates in the experimental groups were significantly higher than that in the control group (p < 0.05). Histological analysis 2 weeks post-implantation in the experimental groups revealed hypertrophic chondrocytes within grafted iMSC pellets, and the formation of woven bone around them; this hypertrophic chondrocyte transitioning to the newly formed bone suggests that the cartilaginous template can trigger the process of endochondral bone ossification (ECO). Four weeks post-implantation, the cartilage template was reduced in size; newly formed woven bone predominated at the defect site. New vessels were surrounded by a matrix of woven bone and the hypertrophic chondrocytes transitioning to the newly formed bone indicated the progression of ECO. Eight weeks post-implantation, the pellets were completely resorbed and replaced by bone; complete bone union was overall observed. Dense mature bone developed with evidence of lamellar-like bone formation. Collectively, our results suggest that iMSC-based cartilage grafts recapitulating the morphogenetic process of ECO in the context of embryonic skeletogenesis are a novel and promising strategy for the repair of large bone defects.

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.

Low-intensity pulsed ultrasound (LIPUS) for stimulation of bone healing - A narrative review

The use of low intensity pulsed ultrasound (LIPUS) to accelerate the fracture repair process in humans was first reported by Xavier & Duarte in 1983 [1]. This success led to clinical trials and the 1994 approval of LIPUS in the United States for the accelerated healing of certain fresh fractures. LIPUS was approved in the US for the treatment of established non-unions in 2000, and is also approved around the world. In this article, we present relevant literature on the effect of LIPUS on bone healing in patients with acute fractures and non-unions and provide a molecular explanation for the effects of LIPUS on bone healing. Data on LIPUS accelerated fracture repair is controversial with many controlled studies showing a positive effect. However, the largest trial in acute tibial fractures stabilized with an intramedullary nail failed to show significant differences in accelerated healing and in functional outcomes. Uncontrolled data from prospective case series suggest a positive effect of LIPUS in non united fractures with healing rates of around 85%. Evaluation of results from studies, both positive and negative, has enabled an understanding that the patient population with potentially the greatest benefit from receiving LIPUS are those at-risk for fracture healing, e.g. diabetic & elderly patients. The elucidation of a pathway to activate the Rac-1 pathway by LIPUS might explain this beneficial effect. Overall, there is a strong need for further clinical trials, particularly for acute fractures at risk of progressing to non-union and in established non-unions including a comparison to the current standard of care.

Musculoskeletal tissue engineering: Regional gene therapy for bone repair

Bone loss associated with fracture nonunion, revision total joint arthroplasty (TJA), and pseudoarthrosis of the spine presents a challenging clinical scenario for the orthopaedic surgeon. Current treatment options including autograft, allograft, bone graft substitutes, and bone transport techniques are associated with significant morbidity, high costs, and prolonged treatment regimens. Unfortunately, these treatment strategies have proven insufficient to safely and consistently heal bone defects in the stringent biological environments often encountered in clinical cases of bone loss. The application of tissue engineering (TE) to musculoskeletal pathology has uncovered exciting potential treatment strategies for challenging bone loss scenarios in orthopaedic surgery. Regional gene therapy involves the local implantation of nucleic acids or genetically modified cells to direct specific protein expression, and has shown promise as a potential TE technique for the regeneration of bone. Preclinical studies in animal models have demonstrated the ability of regional gene therapy to safely and effectively heal critical sized bone defects which otherwise do not heal. The purpose of the present review is to provide a comprehensive overview of the current status of gene therapy applications for TE in challenging bone loss scenarios, with an emphasis on gene delivery methods and models, scaffold biomaterials, preclinical results, and future directions.

A clinical study on bone defect reconstruction and functional recovery in benign bone tumors of the lower extremity, treated by bone marrow mesenchymal stem cell rapid screening-enrichment-composite system

BACKGROUND

With the development of medical technology, credible options for defect reconstructions after the resection of benign bone tumors of the lower extremities have become a high priority. As the current reconstructive methods commonly used in clinical practice have some flaws, new methods of reconstruction need to be explored. We aimed to prepare a new kind of bioactive scaffold for the repair of bone defects through a stem cell rapid screening-enrichment-composite technology system developed by our team. Furthermore, we aimed to investigate the curative effects of these bioactive scaffolds.

METHODS

Firstly, cell count, trypan blue exclusion rate, and ALP staining were used to evaluate changes in enrichment efficiency, cell activity, and osteogenic ability before and after enrichment. Then, the scaffolds were placed under the skin of nude mice to verify their osteogenic effects in vivo. Finally, the scaffolds were used for the reconstruction of bone defects after operations for benign bone tumors in a patient's lower limb. The healing status of the defect site at 1 and 3 months was assessed by X-ray, and the Musculoskeletal Tumor Society (MSTS) score was applied to reflect the recovery of patient limb function.

RESULTS

The system effectively enriched stem cells without affecting the activity and osteogenic abilities of the bone marrow mesenchymal stem cells (BMSCs). Meanwhile, the bioactive scaffolds obtained better osteogenic effects. In patients, the active scaffolds showed better bone integration and healing status, and the patients also obtained higher MSTS scores at 1 and 3 months after surgery.

CONCLUSION

As a new technique, the rapid screening-enrichment-composite technology of stem cells demonstrates a better therapeutic effect in the reconstruction of bone defects after surgery for benign bone tumors of the lower extremities, which will further improve patient prognosis.

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

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

The importance of vitamin D in treatment of fracture non-union: A case report

The prevalence of hypovitaminosis D is currently increasing. A wide variety of diseases and complications are associated with low vitamin D serum concentrations, including poor fracture healing and fracture non-union. A healthy 44-y-old man presented himself with pain due to a non-union of a femoral shaft fracture at 4 y after the initial injury. The fracture had been operated upon three times and was adequately fixated in anatomic position. Hypovitaminosis D was diagnosed, and subsequent supplementation resulted in complete union of the fracture with full pain relief. This case illustrates the importance of adequate serum vitamin D levels in fracture healing, in addition to other fracture healing facilitating factors. With the increasing prevalence of hypovitaminosis D and possibly associated fracture-related complications, routine vitamin D determination should become part of clinical workup in cases of fracture non-union.

Infected Non-Union of the Distal Femur

The reported levels of non-union in the lateral locking plate differ widely, with some early studies showing rates of less than 6% and up to 17%-21% in more recent studies. We report a case where better results were shown by a non-union treated with distal femoral nailing with allogenic grafting.

Programable Active Fixator System for Systematic In Vivo Investigation of Bone Healing Processes

This manuscript introduces a programable active bone fixator system that enables systematic investigation of bone healing processes in a sheep animal model. In contrast to previous systems, this solution combines the ability to precisely control the mechanical conditions acting within a fracture with continuous monitoring of the healing progression and autonomous operation of the system throughout the experiment. The active fixator system was implemented on a double osteotomy model that shields the experimental fracture from the influence of the animal's functional loading. A force sensor was integrated into the fixator to continuously measure stiffness of the repair tissue as an indicator for healing progression. A dedicated control unit was developed that allows programing of different loading protocols which are later executed autonomously by the active fixator. To verify the feasibility of the system, it was implanted in two sheep with different loading protocols, mimicking immediate and delayed weight-bearing, respectively. The implanted devices operated according to the programmed protocols and delivered seamless data over the whole course of the experiment. The in vivo trial confirmed the feasibility of the system. Hence, it can be applied in further preclinical studies to better understand the influence of mechanical conditions on fracture healing.

Rat bone healing induced by natural nanocrystalline carbonated hydroxyapatite in combination with human amniotic fluid stem cells (AFSCs)

The present study was aimed at identifying a new scaffold/stem cell combination useful to treat large bone defects. Human amniotic fluid stem cells (AFSCs) were expanded in vitro, labeled with a fluorescent cell-permeable dye (PKH26) and transplanted in vivo in a femoral injured rat model. The femoral defect was left untreated (control rats) or filled with hydroxyapatite (HA; natural nanocrystalline carbonated hydroxyapatite-Orthoss®) scaffold alone or loaded with PKH26-labeled AFSCs. All animals were killed 3 weeks after implantation. Both gross anatomy and histological observations revealed a major bone regenerative response in rat specimens treated with HA scaffold, alone or supplemented with AFSCs. Samples injected with HA plus AFSCs displayed the presence of abundant fibrotic tissue, the formation of periosteal woven bone, and an increased presence of blood vessels in the bone marrow, with still fluorescent AFSCs in close proximity. These observations provide evidence that natural HA plus AFSCs represents a promising alternative therapeutic strategy to autologous bone grafting procedures.

Humeral head necrosis associated to shaft non-union with massive bone loss: a case report

Humeral non-union is a rare complication in shaft fractures, as well as humeral head necrosis is a possible complication in fracture involving the proximal third especially in four-part fractures. The presence of head osteonecrosis and diaphyseal non-union in the same arm represents a formidable challenge for an orthopaedic surgeon. We could not find any similar report in the literature dealing with this issue thus far. We present a case of a 65 years old woman referred to our hospital being affected by an atrophic humeral diaphyseal non-union with a massive bone loss (>10cm) associated to a humeral head osteonecrosis following a previous surgical procedures with a clear loosening of the hardware. At our institution,she was treated with hardware removal and insertion of a diaphyseal antibiotic spacer with Gentamycin for 2 months suspecting an active septic process at the union site despite negative cultural exams. Finally, she was treated with a cemented modular humeral megaprosthesis. At 20 months follow up, the patient, despite a reduced shoulder range of motion, referred to a pain-free recovery to an almost normal lifestyle, including car driving with no major disturbances. This case suggests that, in extreme selected cases following several failed treatments, megaprosthesis can represent a viable solution, especially in huge bone loss associated to joint degeneration, to ensure an acceptable return to a normal lifestyle.

The Life of a Fracture: Biologic Progression, Healing Gone Awry, and Evaluation of Union

New knowledge about the molecular biology of fracture-healing provides opportunities for intervention and reduction of risk for specific phases that are affected by disease and medications. Modifiable and nonmodifiable risk factors can prolong healing, and the informed clinician should optimize each patient to provide the best chance for union. Techniques to monitor progression of fracture-healing have not changed substantially over time; new objective modalities are needed.

The effect of platelet-rich plasma on fracture healing in long-bone pseudoarthrosis

PURPOSE

The aim of this study was to investigate the effects of platelet-rich plasma (PRP) on fracture union rate and fracture union time in pseudoarthrosis surgery and to evaluate the clinical and functional results of the patients.

METHODS

The patients who were undergone pseudoarthrosis surgery between 2011 and 2014 were evaluated retrospectively. Twenty-four patients were included in the study. Patients were divided into two groups with used PRP and not used PRP during surgery. There were 14 patients in the PRP group and 10 patients in the control group. The two groups were compared in terms of demographic characteristics, fracture union time, and functional scores of the Lower Extremity Functional Scale and Upper Extremity Functional Index.

RESULTS

Fractures were healed in both groups, and no complications were encountered. A statistically significant difference was found between the two groups in terms of fracture union time. The mean time of union was 5.3 months in the PRP group and 11.3 months in the control group (p: 0.000). There was no statistically significant difference between the two groups in terms of functional scores (p: 0.250).

CONCLUSION

As a result of our study, we concluded that PRP is an effective and safe method in pseudoarthrosis surgery that reduces fracture union time. Controlled studies with more patient numbers are needed.

Evaluation of BMP-2 Minicircle DNA for Enhanced Bone Engineering and Regeneration

BACKGROUND

To date, the significant osteoinductive potential of bone morphogenetic protein 2 (BMP-2) non-viral gene therapy cannot be fully exploited therapeutically. This is mainly due to weak gene delivery and brief expression peaks restricting the therapeutic effect.

OBJECTIVE

Our objective was to test the application of minicircle DNA, allowing prolonged expression potential. It offers notable advantages over conventional plasmid DNA. The lack of bacterial sequences and the resulting reduction in size, enables safe usage and improved performance for tissue regeneration.

METHODS

We inserted an optimized BMP-2 gene cassette with minicircle plasmid technology. BMP-2 minicircle plasmids were produced in E. coli yielding plasmids lacking bacterial backbone elements. Comparative studies of these BMP-2 minicircles and conventional BMP-2 plasmids were performed in vitro in cell systems, including bone marrow derived stem cells. Tests performed included gene expression profiles and cell differentiation assays.

RESULTS

A C2C12 cell line transfected with the BMP-2-Advanced minicircle showed significantly elevated expression of osteocalcin, alkaline phosphatase (ALP) activity, and BMP-2 protein amount when compared to cells transfected with conventional BMP-2-Advanced plasmid. Furthermore, the plasmids show suitability for stem cell approaches by showing significantly higher levels of ALP activity and mineralization when introduced into human bone marrow stem cells (BMSCs).

CONCLUSION

We have designed a highly bioactive BMP-2 minicircle plasmid with the potential to fulfil clinical requirements for non-viral gene therapy in the field of bone regeneration.

Synthesis and Characterization of a Biocomposite Bone Bandage for Controlled Delivery of Bone-Active Drugs in Fracture Nonunions

Fracture nonunions are common in orthopedics and their treatment often involves multiple surgical interventions. The aim of this study was to fabricate and characterize a gelatin-nano-hydroxyapatite membrane (GM)-based bone bandage for controlled delivery of bio-active molecules; recombinant human bone morphogenic protein-2 (rhBMP-2) and zoledronic acid (ZA) to promote osteoinduction and prevent callus resorption, respectively. In vitro cell-material interaction experiments using MC3T3 cells seeded on the GM indicated good biocompatibility. rhBMP-2-functionalized GM promoted osteogenic differentiation of MC3T3 cells and the rhBMP-2 bio-activity thus remained, as indicated by increased levels of alkaline phosphatase compared to only GM. The GM released a small amount (1.1%) of rhBMP-2 in vitro over a period of 5 weeks, demonstrating a strong interaction of rhBMP-2 with the GM. In the first animal study, the GM specimens loaded with rhBMP-2 or with the combination of rhBMP-2 + ZA were placed in the abdominal muscle pouch of rats. In the GM + rhBMP-2 + ZA group, significantly higher bone volume (21.5 ± 5.9 vs 2.7 ± 1.0 mm³) and area (3.3 ± 2.3 vs 1.0 ± 0.4 mm²) of bone were observed compared to GM + rhBMP-2 after 4 weeks, as indicated by micro-computed tomography and histomorphometry, respectively. Finally, a nonunion model in rats was used to evaluate the efficacy of the GM bandage and bio-active molecules in healing of fracture nonunions. The GM functionalized with rhBMP-2 + ZA led to higher bone formation around the fracture (63.9 ± 19.0 vs 31.8 ± 3.7 mm³) and stronger fracture callus (110.8 ± 46.8 vs 45.6 ± 17.8 N) compared to the empty controls. However, the overall union rate was only marginally improved. The GM alone or combined with ZA did not aid in bone healing in this model. Thus, this study shows that controlled delivery of rhBMP-2 + ZA via the developed GM is a promising approach that could aid in earlier full load bearing in patients with nonunion.

A RETROSPECTIVE CASE-SERIES ON THE USE OF S53P4 BIOACTIVE GLASS FOR THE ADJUNCTIVE TREATMENT OF SEPTIC DIAPHYSEAL NON-UNION

Objective:

Non-union and persistence of infection at a fracture site for long periods are always described as a challenge to orthopedists, especially in cases of severe compound fractures with comminution and segmental bone loss. This is a case series of septic non-unions, using S53P4 bioactive glass for adjunctive treatment, using internal syntheses or external fixators. The objective is to retrospectively evaluate the results of the use of S53P4 bioglass for the adjunctive treatment of septic non-unions.

Methods:

We reviewed 18 patients with septic non-unions. The patients were preoperatively classified using the Non-union Scoring System (NUSS) and union outcomes were assessed by the modified radiographic union scale in tibial (RUST) fractures. Of the 18 patients treated, six underwent internal osteosynthesis and 12 were treated with external fixators in combination with bioactive glass grafting.

Results:

The patients had a mean NUSS score of 56.6 (standard deviation of 7.6) and fracture union was achieved according to the RUST score in 17 of 18 cases (94.4%), with a mean value of 10.2 (standard deviation of 1.0). One patient was lost to follow-up. Reevaluation using the modified RUST score was 12.3 (SD = 1.0), maintaining union of 17/18.

Conclusion:

The fracture union rate was high, according to the literature, as was control of infection. Level of Evidence IV, Case series.

Humeral shaft non-union in the elderly: Results with cortical graft plus stem cells

INTRODUCTION

Humeral shaft is a common site of fracture non-union. Biology and bone quality represent some of the problems that the orthopaedic surgeon has to face up in the elderly. The goals of treatment of humeral shaft non-union are the achievement of mechanical stability and creation of a favourable biologic environment. Bone graft and stem cells are some of the augmentation techniques available to reach these goals.

PURPOSE

Evaluation of the outcomes of humeral shaft non-union in elderly population treated with cortical allograft and stem cells.

MATERIAL AND METHODS

A cohort of 21 patients with humeral shaft non-union was reviewed. Inclusion criteria were patients aged more than 65 years, with a diagnosis of humeral shaft non-union treated with cortical allograft and stem cells. Primary endpoints were 'bone healing' and 'time-to-union'. Secondary endpoints were shoulder and elbow function and patients' quality of life with Oxford Shoulder Score (OSS), Constant score and EuroQol-5D (EQ-5D).

RESULTS

6 patients met the inclusion criteria. In 5 of them, the cortical allograft was opposite to a plate, whereas in the other one a "Sandwich" technique was chosen because of large osteolysis. 'Bone healing' occurred in all patients after a mean of 3.3 months (range 2-5). In all but two patients, the elbow range of motion was in almost normal range (15-130). The mean OSS was 35.8 (+/- 6.4), whereas the mean Constant was 53.3 (+/- 2.2). The mean EQ-5D index was 0.451 (+/- 0.21).

DISCUSSION

Bone healing occurred in all patients, with a time-to-union comparable or even better compared with other series. The use of cortical bone graft provide both stability and biological benefit, whereas stem cells improve the non-union environmental biology. Functional outcomes were lower than other series and patients' quality of life was similar to Italian elderly women.

CONCLUSION

The use cortical allograft with stem cells is a viable strategy to treat humeral shaft non-union in the elderly.

Fracture Non-Union: A Review of Clinical Challenges and Future Research Needs

Non-union of bone following fracture is an orthopaedic condition with a high morbidity and clinical burden. Despite its estimated global prevalence of nine million annually, the limit of bone regeneration therapy still results in patients living with pain, a reduced quality of life and associated psychological, social and financial repercussions. This review provides an overview of the current epidemiological and aetiological data, and highlights where the clinical challenges in treating non-union lie. Current treatment strategies are discussed as well as promising future research foci. Development in biotechnologies to treat non-union provides exciting scope for more effective treatment for this debilitating condition.

Optimising proliferation and migration of mesenchymal stem cells using platelet products: A rational approach to bone regeneration

This study investigates how mesenchymal stem cell's (MSCs) proliferation and migration abilities are influenced by various platelet products (PP). Donor-matched, clinical-, and control laboratory-standard PPs were generated and assessed based on their platelet and leukocyte concentrations. Bone marrow derived MSCs were exposed to these PP to quantify their effect on in vitro MSC proliferation and migration. An adapted colony forming unit fibroblast (CFU-F) assay was carried out on bone marrow aspirate using clinical-standard PP-loaded electrospun poly(ϵ-caprolactone) (PCL) membrane to mimic future clinical applications to contain bone defects. Clinical-standard PP had lower platelet (2.5 fold, p < 0.0001) and higher leukocyte (14.1 fold, p < 0.0001) concentrations compared to laboratory-standard PP. It induced suboptimal MSC proliferation compared to laboratory-standard PP and fetal calf serum (FCS). All PP induced significantly more MSC migration than FCS up to 24 h. The removal of leukocytes from PP had no effect on MSC proliferation or migration. The PP-loaded membranes successfully supported MSC colony formation. This study indicates that platelet concentrations in PP impact MSC proliferation more than the presence of leukocytes, whilst MSC migration in response to PP is not influenced by platelet or leukocyte numbers. Clinical-standard PP could be applied alongside manufactured membranes in the future treatment of bone reconstruction. © 2019 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:1329-1338, 2019.

The 'diamond concept' for long bone non-union management

Long bone non-union continues to be a significant worldwide problem. Since its inception over a decade ago, the ‘diamond concept’, a conceptual framework of what is essential for a successful bone healing response, has gained great acceptance for assessing and planning the management of fracture non-unions. Herein, we discuss the epidemiology of non-unions, the basic science of bone healing in the context of the diamond concept, the currently available results and areas for future research.

Genomewide Association Study of Fracture Nonunion Using Electronic Health Records

Nonunion is a clinically significant complication of fracture associated with worse outcomes, including increased pain, disability, and higher healthcare costs. The risk for nonunion is likely to be complex and multifactorial, and as such, the biology underlying such risk remains poorly understood. Genetic studies represent one approach to identify implicated biology for further investigation, but to date the lack of large cohorts for study has limited such efforts. We utilized the electronic health records of two large academic medical centers in Boston to identify individuals with fracture nonunion and control individuals with fracture but no evidence of nonunion. We conducted a genomewide association study among 1760 individuals of Northern European ancestry with upper or lower extremity fracture, including 131 with nonunion, to examine whether common variants were associated with nonunion in this cohort. In all, one locus in the Calcyon (CALY) gene exceeded a genomewide threshold for statistical significance (p = 1.95e-8), with eight additional loci associated with p < 5e-7. Previously reported candidate genes were not supported by this analysis. Electronic health records should facilitate identification of common genetic variations associated with adverse orthopedic outcomes. The loci we identified in this small cohort require replication and further study to characterize mechanism of action, but represent a starting point for the investigation of genetic liability for this costly outcome.

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

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

Bone marrow-derived stem/stromal cells (BMSC) 3D microtissues cultured in BMP-2 supplemented osteogenic induction medium are prone to adipogenesis

Bone marrow-derived mesenchymal stem/stromal cells (BMSC) may facilitate bone repair through secretion of factors that stimulate endogenous repair processes or through direct contribution to new bone through differentiation into osteoblast-like cells. BMSC microtissue culture and differentiation has been widely explored recently, with high-throughput platforms making large-scale manufacture of microtissues increasingly feasible. Bone-like BMSC microtissues could offer an elegant method to enhance bone repair, especially in small-volume non-union defects, where small diameter microtissues could be delivered orthoscopically. Using a high-throughput microwell platform, our data demonstrate that (1) BMSC in 3D microtissue culture result in tissue compaction, rather than growth, (2) not all mineralised bone-like matrix is incorporated in the bulk microtissue mass and (3) a significant amount of lipid vacuole formation is observed in BMSC microtissues exposed to BMP-2. These factors should be considered when optimising BMSC osteogenesis in microtissues or developing BMSC microtissue-based therapeutic delivery processes.

Preclinical therapies to prevent or treat fracture non-union: A systematic review

Background

Non-union affects up to 10% of fractures and is associated with substantial morbidity. There is currently no single effective therapy for the treatment or prevention of non-union. Potential treatments are currently selected for clinical trials based on results from limited animal studies, with no attempt to compare results between therapies to determine which have the greatest potential to treat non-union.

Aim

The aim of this systematic review was to define the range of therapies under investigation at the preclinical stage for the prevention or treatment of fracture non-union. Additionally, through meta-analysis, it aimed to identify the most promising therapies for progression to clinical investigation.

Methods

MEDLINE and Embase were searched from 1^St January 2004 to 10^th April 2017 for controlled trials evaluating an intervention to prevent or treat fracture non-union. Data regarding the model used, study intervention and outcome measures were extracted, and risk of bias assessed.

Results

Of 5,171 records identified, 197 papers describing 204 therapies were included. Of these, the majority were only evaluated once (179/204, 88%), with chitosan tested most commonly (6/204, 3%). Substantial variation existed in model design, length of survival and duration of treatment, with results poorly reported. These factors, as well as a lack of consistently used objective outcome measures, precluded meta-analysis.

Conclusion

This review highlights the variability and poor methodological reporting of current non-union research. The authors call for a consensus on the standardisation of animal models investigating non-union, and suggest journals apply stringent criteria when considering animal work for publication.

Diagnosis and management of long-bone nonunions: a nationwide survey

Purpose

There is variability among surgeons on definitions regarding the degree of bone healing of long-bone fractures. A lack of consensus may negatively affect communication between surgeons, and lead to unintended and unwanted variability in treatment of patients suffering from abnormal healing of long-bone fractures. We aimed to identify differences between surgeons regarding their views on the degree of union of long-bone fractures.

Methods

We performed a survey among 114 surgeons who worked at 11 level I trauma centers and 68 level II/III hospitals in the Netherlands. We asked them to represent their institutional colleagues and answer questions regarding their views on the definition, factors influencing bone healing, clinical practice, views on scientific evidence, and the use or need of guidelines for non-union of long-bone fractures. A total of 26 trauma surgeons and 37 orthopedic surgeons responded (59%).

Results

Compared to trauma surgeons, more orthopedic surgeons maintain 6 months as the timeframe for classifying a fracture without healing tendencies as a non-union fracture (50 vs 70%; P = 0.019). Compared to orthopedic surgeons, trauma surgeons use the bone scan (46 vs 19%; P = 0.027) and the PET scan (50 vs 5.4%; P < 0.001) more often, and consider medication use to be a factor influencing bone healing more often (92 vs 69%; P = 0.040). Furthermore, they utilize bone marrow aspiration (35 vs 11%; P = 0.029), reaming of long bones (96 vs 70%; P = 0.010), synthetic bone substitutes (31 vs 5.4%; P = 0.012), bone morphogenetic proteins (58 vs 16%; P = 0.001), and the Diamond concept (92 vs 8.1%) more often as treatment modalities for non-union of long-bone fractures. Surgeons agreed on that intramedullary nail osteosynthesis was the treatment option supported by the highest level of evidence. 80% of the respondents feel a need for a clinical guideline on the management of long-bone non-union.

Conclusion

There is no consensus among surgeons on the definition, factors influencing healing, clinical practice, and scientific evidence regarding non-union of long-bone fractures. The vast majority of surgeons believe that their practice would benefit from (inter)national guidelines on this topic, and efforts should be made to reduce surgeon-to-surgeon variability in treatment recommendations and facilitate more homogenous scientific research on non-union of long-bone fractures.

Level of evidence

Level V.