Treatment of atrophic femoral non-unions according to the diamond concept: Results of one- and two-step surgical procedure

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.

Long-term patient reported outcomes after revision surgery for lower extremity nonunion: A retrospective cohort study

INTRODUCTION

Ongoing lower extremity long-bone nonunion is a devastating condition and associated with substantial patient morbidity. There is limited evidence regarding physical and mental function after surgical management of lower extremity nonunions. The purpose of this study was to assess general physical and mental health and lower extremity specific physical function of patients that underwent surgery for a lower extremity long-bone nonunion.

METHODS

One-hundred and twenty-four adult patients who underwent successful surgical management for a lower extremity long-bone nonunion between June 2002 and December 2021 were evaluated at an average follow-up of 8.6 years (interquartile range [IQR]: 4 - 12). General physical and mental health was assessed with the Short-Form 12 (SF-12) physical (PCS) and mental (MCS) component summaries, and lower extremity specific physical function with the Lower Extremity Functional Scale (LEFS). Multivariable linear regression was performed to identify variables that were independently associated with outcomes.

RESULTS

The median LEFS was 50 (IQR: 37 - 63) and the median SF-12 PCS was 43 (IQR: 33 - 52), which are both lower than normative population scores (LEFS: 77 and PCS: 51, p < 0.0001). The median SF-12 MCS was 50, which was comparable to the normative population score of 51 (p < 0.0001). The number of previous surgeries before the index nonunion treatment (p = 0.018 and p = 0.041) and the number of revision surgeries after the index nonunion treatment (p = 0.022 and p = 0.041) were associated with lower LEFS and SF-12 PCS scores.

CONCLUSION

At an average of 8.6 years after lower extremity nonunion surgery that led to bone healing, patients continue to report lower general and lower extremity specific physical functioning compared to the normative population. The number of surgical attempts to obtain definitive healing was associated with compromised physical function scores. Mental health scores may return close to normative population scores. These results can be used to inform patients and guide treatment strategies and healthcare policies.

Infected humeral shaft nonunion treatment with the induced membrane technique and a novel fixation construct: a case report

Case

A 51-year-old woman with an infected left humeral shaft recalcitrant nonunion presented 3 years after initial injury. This case report focuses on the staged treatment of a 17-centimeter (cm) humeral shaft nonunion with the induced membrane technique (IMT) using a unique fixation construct of dual locked plating around a humeral nail to provide long-lasting fixation and allow for bone graft consolidation.

Conclusion

Large segmental bone loss of the humerus can be treated with the IMT using nail-plate fixation constructs that allow for early mobilization, increased time for bone graft consolidation before hardware failure, and less frequent follow-up.

Long-Term Outcomes Following Single-Stage Reamed Intramedullary Exchange Nailing in Apparently Aseptic Femoral Shaft Nonunion with Unsuspected Proof of Bacteria

Background: The aim of this study was to evaluate detection rates and risk factors for unsuspected proof of bacteria, as well as clinical and radiologic outcomes following femoral shaft nonunion without clinical signs of infection treated by a single-stage surgical revision procedure including reamed intramedullary exchange nailing. Methods: A retrospective cohort study was performed in a European level I trauma center between January 2015 and December 2022. Fifty-eight patients were included who underwent reamed intramedullary exchange nailing as a single-step procedure for surgical revision of posttraumatic diaphyseal femoral nonunion without any indications of infection in medical history and without clinical signs of local infection. Clinical details of the patients were analyzed and functional and radiologic long-term outcomes were determined. Results: In all patients, with and without proof of bacteria osseous, healing could be observed. The physical component summary of the SF-12 demonstrated significantly better results at least one year after the final surgical revision in case of a negative bacterial culture during exchange nailing. Conclusions: Clinical long-term outcomes demonstrated a trend towards better results following femoral shaft nonunion revision if there was no evidence for the presence of low-grade infected nonunion. In this case, a single-stage surgical procedure may be recommended.

Surprise positive culture rate in the treatment of presumed aseptic long-bone nonunion: a systematic review with meta-analysis of 2397 patients

INTRODUCTION

In pre-operatively presumed aseptic nonunions, the definitive diagnosis of infection relies on intraoperative cultures. Our primary objective was to determine (1) the rate of surprise positive intraoperative cultures in presumed aseptic long-bone nonunion (surprise positive culture nonunion), and (2) the rate of surprise positive cultures that represent infection vs. contamination. Secondary objectives were to determine the healing and secondary surgery rates and to identify cultured micro-organisms.

MATERIALS AND METHODS

We performed a systematic literature search of PubMed, Embase and Cochrane Libraries from 1980 until December 2021. We included studies reporting on ≥ 10 adult patients with a presumed aseptic long-bone nonunion, treated with a single-stage surgical protocol, of which intraoperative cultures were reported. We performed a meta-analysis for: (1) the rates of surprise positive culture nonunion, surprise infected nonunion, and contaminated culture nonunion, and (2) healing and (3) secondary surgery rates for each culture result. Risk of bias was assessed using the QUADAS-2 tool.

RESULTS

21 studies with 2,397 patients with a presumed aseptic nonunion were included. The rate of surprise positive culture nonunion was 16% (95%CI: 10-22%), of surprise infected nonunion 10% (95%CI: 5-16%), and of contaminated culture nonunion 3% (95%CI: 1-5%). The secondary surgery rate for surprise positive culture nonunion was 22% (95%CI: 9-38%), for surprise infected nonunion 14% (95%CI 6-22%), for contaminated culture nonunion 4% (95%CI: 0-19%), and for negative culture nonunion 6% (95CI: 1-13%). The final healing rate was 98% to 100% for all culture results. Coagulase-negative staphylococci accounted for 59% of cultured micro-organisms.

CONCLUSION

These results suggest that surprise positive cultures play a role in the clinical course of a nonunion and that culturing is important in determining the etiology of nonunion, even if the pre-operative suspicion for infection is low. High healing rates can be achieved in presumed aseptic nonunions, regardless of the definitive intraoperative culture result.

Surgical repair of large segmental bone loss with the induced membrane technique: patient reported outcomes are comparable to nonunions without bone loss

OBJECTIVE

To compare the outcomes of patients with segmental bone loss who underwent repair with the induced membrane technique (IMT) with a matched cohort of nonunion fractures without bone loss.

DESIGN

Retrospective analysis on prospectively collected data.

SETTING

Academic medical center.

PATIENTS

Two cohorts of patients, those with upper and lower extremity diaphyseal large segmental bone loss and those with ununited fractures, were enrolled prospectively between 2013 and 2020. Sixteen patients who underwent repair of 17 extremities with segmental diaphyseal or meta-diaphyseal bone defects treated with the induced membrane technique were identified, and matched with 17 patients who were treated for 17 fracture nonunions treated without an induced membrane. Sixteen of the bone defects treated with the induced membrane technique were due to acute bone loss, and the other was a chronic aseptic nonunion.

MAIN OUTCOME MEASUREMENTS

Healing rate, time to union, functional outcome scores using the Short Musculoskeletal Functional Assessment (SMFA) and pain assessed by the Visual Analog Scale (VAS).

RESULTS

The initial average defect size for patients treated with the induced membrane technique was 8.85 cm. Mean follow-up times were similar with 17.06 ± 10.13 months for patients treated with the IMT, and 20.35 ± 16.68. months for patients treated without the technique. Complete union was achieved in 15/17 (88.2%) of segmental bone loss cases treated with the IMT and 17/17 (100%) of cases repaired without the technique at the latest follow up visit. The average time to union for patients treated with the induced membrane technique was 13.0 ± 8.4 months and 9.64 ± 4.7 months for the matched cohort. There were no significant differences in reported outcomes measured by the SMFA or VAS. Patients treated with the induced membrane technique required more revision surgeries than those not treated with an induced membrane.

CONCLUSION

Outcomes following treatment of acute bone loss from the diaphysis of long bones with the induced membrane technique produces clinical and radiographic outcomes similar to those of long bone fracture nonunions without bone loss that go on to heal.

LEVEL OF EVIDENCE

III.

Use of Autologous Bone Graft with Bioactive Glass as a Bone Substitute in the Treatment of Large-Sized Bone Defects of the Femur and Tibia

BACKGROUND

Managing bone defects in non-union surgery remains challenging, especially in cases of large defects exceeding 5 cm in size. Historically, amputation and compound osteosynthesis with a remaining PMMA spacer have been viable and commonly used options. The risk of non-union after fractures varies between 2% and 30% and is dependent on various factors. Autologous bone grafts from the iliac crest are still considered the gold standard but are limited in availability, prompting consideration of artificial grafts.

OBJECTIVES

The aims and objectives of the study are as follows: 1. To evaluate the radiological outcome of e.g., the consolidation and thus the stability of the bone (three out of four consolidated cortices/Lane-Sandhu-score of at least 3) by using S53P4-type bioactive glass (BaG) as a substitute material for large-sized bone defects in combination with autologous bone using the RIA technique. 2. To determine noticeable data-points as a base for future studies.

METHODS

In our clinic, 13 patients received bioactive glass (BaG) as a substitute in non-union therapy to promote osteoconductive aspects. BaG is a synthetic material composed of sodium, silicate, calcium, and phosphate. The primary endpoint of our study was to evaluate the radiological consolidation of bone after one and two years. To assess bone stabilization, we used a modified Lane-Sandhu score, considering only radiological criteria. A bone was considered stabilized if it achieved a minimum score of 3. For full consolidation (all four cortices consolidated), a minimum score of 4 was required. Each bone defect exceeded 5 cm in length, with an average size of 6.69 ± 1.92 cm.

RESULTS

The mean follow-up period for patients without final bone consolidation was 34.25 months, with a standard deviation of 14.57 months, a median of 32.00 months and a range of 33 months. In contrast, patients with a fully consolidated non-union had an average follow-up of 20.11 ± 15.69 months and a range of 45 months. Overall, the mean time from non-union surgery to consolidation for patients who achieved final union was 14.91 ± 6.70 months. After one year, six patients (46.2%) achieved complete bone consolidation according to the Lane-Sandhu score. Three patients (23.1%) displayed evident callus formation with expected stability, while three patients (23.1%) did not develop any callus, and one patient only formed a minimal callus with no expected stability. After two years, 9 out of 13 patients (69.2%) had a score of 4. The remaining four patients (30.8%) without expected stability either did not heal within two years or required a revision during that time.

CONCLUSIONS

Bioactive glass (BaG) in combination with autologous bone (RIA) appears to be a suitable filler material for treating extensive non-unions of the femur and tibia. This approach seems to show non-inferiority to treatment with Tricalcium Phosphate (TCP). To ensure the success of this treatment, it is crucial to validate the procedure through a randomized controlled trial (RCT) with a control group using TCP, which would provide higher statistical power and more reliable results.

Induced membrane technique versus one-stage autografting in management of atrophic nonunion of long bone in the lower limb: clinical and health burden outcomes

OBJECTIVE

In this study, we aimed to compare the outcomes of the two-stage induced membrane technique (IMT) and one-stage autografting in the treatment of aseptic atrophic nonunion in lower limb long bones.

METHODS

From January 2014 to January 2022, we reviewed all surgically treated long bone nonunion patients, including patients aged 18 years or older with atrophic nonunion, who were either treated with the two-stage induced membrane technique (IMT) or one-stage autografting. Outcome parameters interns of clinical, quality of life and healthcare burden were recorded and retrospectively analysed between the two treatment populations. The follow-up time was at least 1 year.

RESULTS

In total, 103 patients who met the criteria for aseptic atrophic nonunion were enrolled. Among them, 41 (39.8%) patients were treated with two-stage IMT, and 62 (60.2%) patients were treated with one-stage autologous bone grafting. The follow-up time was 12 to 68 months, with an average of 28.4 months. The bone healing rate was comparable in both groups (IMT: 92.7% vs. one-stage grafting: 91.9%, P = 0.089) at 12 months post-operation, and the bone healing Lane-Sandhu score was superior in the IMT group (mean: 8.68 vs. 7.81, P = 0.002). Meanwhile, the SF-12 scores of subjective physical component score (PCS) (mean: 21.36 vs. 49.64, P < 0.01) and mental health component score (MCS) (mean: 24.85 vs. 46.14, P < 0.01) significantly increased in the IMT group, as well as in the one-stage grafting group, and no statistically significant difference was found within groups. However, the total hospital stays (median: 8 days vs. 14 days, P < 0.01) and direct medical healthcare costs (median: ¥30,432 vs. ¥56,327, P < 0.05) were greater in the IMT group, while the complications (nonunion 8, infection 3, material failure 2, and donor site pain 6) were not significantly different between the two groups (17.1% vs. 19.4, P = 0.770).

CONCLUSION

The data indicate that two-stage method of IMT serves as an alternative method in treating atrophic nonunion; however, it may not be a preferred option, in comprehensive considering patient clinical outcomes and healthcare burden. More evidence-based research is needed to further guide clinical decision-making.

Accumulation of advanced glycation end products promotes atrophic nonunion incidence in mice through a CtBP1/2-dependent mechanism

Atrophic nonunion (AN) is a complex and poorly understood pathological condition resulting from impaired fracture healing. Advanced glycation end products (AGEs) have been implicated in the pathogenesis of several bone disorders, including osteoporosis and osteoarthritis. However, the role of AGEs in the development of AN remains unclear. This study found that mice fed a high-AGE diet had a higher incidence of atrophic nonunion (AN) compared to mice fed a normal diet following tibial fractures. AGEs induced two C-terminal binding proteins (CtBPs), CtBP1 and CtBP2, which were necessary for the development of AN in response to AGE accumulation. Feeding a high-AGE diet after fracture surgery in CtBP1/2-/- and RAGE-/- (receptor of AGE) mice did not result in a significant occurrence of AN. Molecular investigation revealed that CtBP1 and CtBP2 formed a heterodimer that was recruited by histone deacetylase 1 (HDAC1) and runt-related transcription factor 2 (Runx2) to assemble a complex. The CtBP1/2-HDAC1-Runx2 complex was responsible for the downregulation of two classes of bone development and differentiation genes, including bone morphogenic proteins (BMPs) and matrix metalloproteinases (MMPs). These findings demonstrate that AGE accumulation promotes the incidence of AN in a CtBP1/2-dependent manner, possibly by modulating genes related to bone development and fracture healing. These results provide new insights into the pathogenesis of AN and suggest new therapeutic targets for its prevention and treatment.

Matched-Pair Analysis: Large-Sized Defects in Surgery of Lower Limb Nonunions

BACKGROUND

The treatment of large-sized bone defects remains a major challenge in trauma and orthopaedic surgery. Although there are many treatment options, there is still no clear guidance on surgical management, and the influence of defect size on radiological and clinical outcome remains unclear due to the small number of affected patients. The aim of the present study was to determine the influence of defect size on the outcome of atrophic and infected nonunions of the tibia or the femur based on the diamond concept in order to provide recommendations for treatment guidance.

PATIENTS AND METHODS

All medical records, surgical reports, laboratory data and radiological images of patients treated surgically for atrophic or infected nonunions of the lower limbs (femur or tibia) between 1 January 2010 and 31 December 2020 were examined. Patients with proximal, diaphyseal or distal nonunions of the femur or tibia who were surgically treated at our institution according to the "diamond concept" and attended our standardised follow-up program were included in a database. Surgical treatment was performed as a one- or two-step procedure, depending on the type of nonunion. Patients with a segmental bone defect ≥5 cm were matched with patients suffering a bone defect <5 cm based on five established criteria. According to our inclusion and exclusion criteria, 70 patients with a bone defect ≥5 cm were suitable for analysis. Two groups were formed by matching: the study group (bone defect ≥5 cm; n = 39) and control group (bone defect <5 cm; n = 39). The study was approved by the local ethics committee (S-262/2017).

RESULTS

The mean defect size was 7.13 cm in the study and 2.09 cm in the control group. The chi-square test showed equal consolidation rates between the groups (SG: 53.8%; CG: 66.7%). However, the Kaplan-Meier curve and log-rank test showed a significant difference regarding the mean duration until consolidation was achieved, with an average of 15.95 months in the study and 9.24 months in the control group (α = 0.05, p = 0.001). Linear regression showed a significant increase in consolidation duration with increasing defect size (R² = 0.121, p = 0.021). Logistic regression modelling showed a significant negative correlation between consolidation rate and revision performance, as well as an increasing number of revisions, prior surgeries and total number of surgeries performed on the limb. Clinical outcomes showed equal full weight bearing of the lower extremity after 5.54 months in the study vs. 4.86 months in the control group (p = 0.267).

CONCLUSION

Surprisingly, defect size does not seem to have a significant effect on the consolidation rate and should not be seen as a risk factor. However, for the treatment of large-sized nonunions, the follow-up period should be prolonged up to 24 months, due to the extended time until consolidation will be achieved. This period should also pass before a premature revision with new bone augmentation is performed. In addition, it should be kept in mind that as the number of previous surgeries and revisions increases, the prospects for consolidation decrease and a change in therapeutic approach may be required.

Effect of Tricalcium Phosphate on Healing of Non-Unions: An Observational Study of over 400 Non-Unions

Purpose

A central aspect of the treatment of non-unions is the filling of bone defects. The quantity of available autologous bone for this purpose is limited. Alternatively, or additionally, bone substitutes may be used. The aim of this retrospective, single-center study including 404 non-unions in 393 patients is to investigate the effect of tricalcium phosphate (TCP) on the healing of non-unions. Furthermore, the influence of gender, age, smoking status, comorbidities, type of surgical procedure, presence of infection, and length of treatment was investigated.

Methods

We evaluated three groups of patients. Group 1 received TCP + BG, group 2 received BG alone and group 3 received no augmentation. Bone stability was assessed 1 and 2 years after non-union revision surgery through analysis of radiographs using the Lane Sandhu Score. Scores ≥3 were rated as stable Other influencing factors were collected from the electronic medical record.

Results

In 224 non-unions, bone defects were filled with autologous bone and TCP (TCP+BG). In 137 non-unions, bone defects were filled with autologous bone (BG), and in 43 non-unions presenting non-relevant defects, neither autologous bone nor TCP were used (NBG). After 2 years, 72.7% of the TCP+BG patients, 90.1% of the BG patients and 84.4% of the NBG patients achieved a consolidation score ≥3. Advanced age, presence of comorbidities and longer treatment period had a significantly negative effect on consolidation 1 year after surgery. Longer treatment periods also showed a negative significant effect after 2 years. It is notable that larger defects, mainly treated with the combination of autologous bone and TCP, showed similar healing rates to that of smaller defects after 2 years.

Conclusion

The combination of TCP and autologous bone-grafts shows good results in the reconstruction of complicated bone-defects, but patience is required since the healing period exceeds 1 year in most patients.

Delayed Fracture Healing

Physiologic bone healing involves numerous parameters, such as microstability, fracture morphology, or tissue perfusion, to name just a few. Slight imbalances or a severe impairment of even one of these factors may, as the figurative weakest link in the chain, crucially or completely inhibit the regenerative potential of a fractured bone. This review revisits the physiology and pathophysiology of fracture healing and provides an insight into predispositions, subtypes, diagnostic tools, and therapeutic principles involved with delayed fracture healing and nonunions. Depending on the patients individual risk factors, nonunions may develop in a variety of subtypes, each of which may require a slightly or fundamentally different therapeutical approach. After a detailed analysis of these individual factors, additional diagnostic tools, such as magnetic resonance imaging (MRI), dynamic contrast-enhanced MRI, sonography, or contrast-enhanced ultrasonography, may be indicated to narrow down the most likely cause for the development of the nonunion and therefore help find and optimize the ideal treatment strategy.

Cryogel Scaffold-Mediated Delivery of Adipose-Derived Stem Cells Promotes Healing in Murine Model of Atrophic Non-Union

Non-union is defined as the permanent failure of a bone to heal and occurs clinically in 5% of fractures. Atrophic non-unions, characterized by absent/minimal callus formation, are poorly understood and difficult to treat. We recently demonstrated a novel murine model of atrophic non-union in the 3.6Col1A1-tk (Col1-tk) mouse, wherein dosing with the nucleoside analog ganciclovir (GCV) was used to deplete proliferating osteoprogenitor cells, leading to a radiographic and biomechanical non-union after the mid-shaft femur fracture. Using this Col1-tk atrophic non-union model, we hypothesized that the scaffold-mediated lentiviral delivery of doxycycline-inducible BMP-2 transgenes would induce osteogenesis at the fracture site. Cryogel scaffolds were used as a vehicle for GFP+ and BMP-2+ cell delivery to the site of non-union. Cryogel scaffolds were biofabricated through the cross-linking of a chitosan-gelatin polymer solution at subzero temperatures, which results in a macroporous, spongy structure that may be advantageous for a bone regeneration application. Murine adipose-derived stem cells were seeded onto the cryogel scaffolds, where they underwent lentiviral transduction. Following the establishment of atrophic non-unions in the femurs of Col1-tk mice (4 weeks post-fracture), transduced, seeded scaffolds were surgically placed around the site of non-union, and the animals were given doxycycline water to induce BMP-2 production. Controls included GFP+ cells on the cryogel scaffolds, acellular scaffolds, and sham (no scaffold). Weekly radiographs were taken, and endpoint analysis included micro-CT and histological staining. After 2 weeks of implantation, the BMP-2+ scaffolds were infiltrated with cartilage and woven bone at the non-union site, while GFP+ scaffolds had woven bone formation. Later, timepoints of 8 weeks had woven bone and vessel formation within the BMP-2+ and GFP + scaffolds with cortical bridging of the original fracture site in both groups. Overall, the cell-seeded cryogels promoted osseous healing. However, while the addition of BMP-2 promoted the endochondral ossification, it may provide a slower route to healing. This proof-of-concept study demonstrates the potential for cellularized cryogel scaffolds to enhance the healing of non-unions.

Silk-Based Bioengineered Diaphyseal Cortical Bone Unit Enclosing an Implantable Bone Marrow toward Atrophic Nonunion Grafting

Postnatal fracture healing of atrophic long bone diaphyseal nonunions remains a challenge for orthopedic surgeons. Paucity of autologous spongiosa has potentiated the use of tissue engineered bone grafts to improve success rates of bone marrow engraftment used in plate reosteosynthesis. Herein, the development and in vitro validation of a "sandwich-type" biofabricated diaphyseal cross-sectional unit, with an outer mechanically robust bioprinted cortical bone shell, encompassing an engineered bone marrow, are reported. Channelized silk fibroin blend sponges derived from Bombyx mori and Antheraea assama help in developing compartmentalized endosteum, exhibiting specialized osteoblasts (endosteal niche) and discontinuous endothelium (vascular niche). The cellular cross-talk between these two niches triggered via integrin-mediated cell adhesion, enables in preserving quiescence state of CD34⁺ /CD38^- hematopoietic stem cells and their recycling in the engineered marrow. The outer cortical bone strut is developed through multimaterial microextrusion bioprinting strategy. Osteogenically primed mesenchymal stem cells-laden silk fibroin-nano-hydroxyapatite bioink is bioprinted alongside paramagnetic Fe-doped bioactive glass-polycaprolactone blend thermoplastic ink, reinforcing it for mechanical stability. Pulsed magnetic field actuation positively influences the osteogenic commitment and maturation of the bioprinted constructs via mechanotransductory route. Therefore, the assembled engineered marrow and bioprinted cortical shell hold promise as potential orthobiologic substitutes toward atrophic nonunion repairs.

Contrast-Enhanced Ultrasound: A Viable Diagnostic Tool in Predicting Treatment Failure after Non-union Revision Surgery for Upper- and Lower-Limb Non-unions

Non-unions remain a major complication in the treatment of long-bone fractures and affect quality of life considerably. Both early detection and treatment of non-unions are essential to secure subsequent fracture union. Sufficient vascularization plays a key role in the healing process. The aim of this prospective study was to quantify the microperfusion within non-unions by means of contrast-enhanced ultrasound (CEUS) as early as 12 wk after non-union surgery and to examine the prognostic capability of CEUS in predicting treatment failure. Among 112 patients who had undergone non-union surgery, consolidation within 36 mo was achieved in 89 patients ("responders"), whereas 23 patients showed persistent non-unions ("non-responders") and required further surgery. CEUS quantification parameters such as peak enhancement, wash-in area under the curve and wash-in perfusion index revealed significantly higher perfusion levels in "responders" compared with "non-responders" (p < 0.05). Receiver operator characteristic curve analysis revealed that persistent fracture non-unions could be predicted with a sensitivity/specificity of 88.7%/72.2% in lower-limb non-unions and a sensitivity/specificity of 66.7%/100.0% in upper-limb non-unions. CEUS is a suitable diagnostic tool in predicting treatment failure as early as 12 wk after non-union surgery and should be integrated into the clinical routine when deciding on revision surgery at an early stage.

Long-term patient-related quality of life after successfully treated aseptic non-unions of the long bones

BACKGROUND

Non-union after fracture depicts a devastating complication in trauma surgery and studies assessing patient-reported outcome measures after stable bone consolidation are rare. Therefore, we aimed to evaluate the long-term impact of aseptic long bone non-union on the patients' physical health state and psychological wellbeing. For this purpose, quality of life after successful surgical treatment of long bone non-union was assessed.

METHODS

Sixty-one patients with aseptic long bone non-union surgically treated in our department between November 2009 and March 2019 with achieved bone consolidation were included. Quality of life was evaluated with the EQ-5D and SF-36 outcome instruments as well as with an ICD-10 based symptom rating (ISR) and compared to normative data.

RESULTS

With a minimum follow-up time of one year after the last surgery (mean 4.7 ± 2.7 years) the mean physical health component score of the SF-36 was 38.9 ± 13.7 and the mean mental health component score of the SF-36 was 49.0 ± 5.9, indicating lower quality of life compared to German normative values of 48.4 ± 9.4 (p < .001) and 50.9 ± 8.8 (p = 1.61), respectively. The mean EQ-5D index value reached 0.827 ± 0.18 with an EQ-5D VAS rating of 64.4 ± 21.5 compared to scores of 0.922 (p < .001) and 72.9 ± 1.1 (p < .001) obtained from an age-matched reference population. Mean scores of the ISR did not reveal significant psychological symptom burden in any scale, while an individual analysis showed moderate to severe impairments in 11.5% of the patients in total.

CONCLUSION

Even 4.7 years on average after surgically successful treatment of aseptic long bone non-union, patients still report significant lower quality of life in comparison to normative data. Future clinical studies on non-unions should focus on patient-related outcome measures. Newly emerging treatment strategies and interdisciplinary approaches should be implemented to improve the overall quality of life of non-union patients.

S53P4 bioactive glass scaffolds induce BMP expression and integrative bone formation in a critical-sized diaphysis defect treated with a single-staged induced membrane technique

Critical-sized diaphysis defects are complicated by inherent sub-optimal healing conditions. The two-staged induced membrane technique has been used to treat these challenging defects since the 1980's. It involves temporary implantation of a membrane-inducing spacer and subsequent bone graft defect filling. A single-staged, graft-independent technique would reduce both socio-economic costs and patient morbidity. Our aim was to enable such single-staged approach through development of a strong bioactive glass scaffold that could replace both the spacer and the graft filling. We constructed amorphous porous scaffolds of the clinically used bioactive glass S53P4 and evaluated them in vivo using a critical-sized defect model in the weight-bearing femur diaphysis of New Zealand White rabbits. S53P4 scaffolds and standard polymethylmethacrylate spacers were implanted for 2, 4, and 8 weeks. Induced membranes were confirmed histologically, and their osteostimulative activity was evaluated through RT-qPCR of bone morphogenic protein 2, 4, and 7 (BMPs). Bone formation and osseointegration were examined using histology, scanning electron microscopy, energy-dispersive X-ray analysis, and micro-computed tomography imaging. Scaffold integration, defect union and osteosynthesis were assessed manually and with X-ray projections. We demonstrated that S53P4 scaffolds induce osteostimulative membranes and produce osseointegrative new bone formation throughout the scaffolds. We also demonstrated successful stable scaffold integration with early defect union at 8 weeks postoperative in critical-sized segmental diaphyseal defects with implanted sintered amorphous S53P4 scaffolds. This study presents important considerations for future research and the potential of the S53P4 bioactive glass as a bone substitute in large diaphyseal defects. STATEMENT OF SIGNIFICANCE: Surgical management of critical-sized diaphyseal defects involves multiple challenges, and up to 10% result in delayed or non-union. The two-staged induced membrane technique is successfully used to treat these defects, but it is limited by the need of several procedures and bone graft. Repeated procedures increase costs and morbidity, while grafts are subject to donor-site complications and scarce availability. To transform this two-staged technique into one graft-independent procedure, we developed amorphous porous scaffolds sintered from the clinically used bioactive glass S53P4. This work constitutes the first evaluation of such scaffolds in vivo in a critical-sized diaphyseal defect in the weight-bearing rabbit femur. We provide important knowledge and prospects for future development of sintered S53P4 scaffolds as a bone substitute.

Spongostan™ Leads to Increased Regeneration of a Rat Calvarial Critical Size Defect Compared to NanoBone® and Actifuse

Bone substitute materials are becoming increasingly important in oral and maxillofacial surgery. Reconstruction of critical size bone defects is still challenging for surgeons. Here, we compared the clinically applied organic bone substitute materials NanoBone^® (nanocrystalline hydroxyapatite and nanostructured silica gel; n = 5) and Actifuse (calcium phosphate with silicate substitution; n = 5) with natural collagen-based Spongostan™ (hardened pork gelatin containing formalin and lauryl alcohol; n = 5) in bilateral rat critical-size defects (5 mm diameter). On topological level, NanoBone is known to harbour nanopores of about 20 nm diameter, while Actifuse comprises micropores of 200–500 µm. Spongostan™, which is clinically applied as a haemostatic agent, combines in its wet form both nano- and microporous topological features by comprising 60.66 ± 24.48 μm micropores accompanied by nanopores of 32.97 ± 1.41 nm diameter. Micro-computed tomography (µCT) used for evaluation 30 days after surgery revealed a significant increase in bone volume by all three bone substitute materials in comparison to the untreated controls. Clearly visual was the closure of trepanation in all treated groups, but granular appearance of NanoBone^® and Actifuse with less closure at the margins of the burr holes. In contrast, transplantion of Spongostan™ lead to complete filling of the burr hole with the highest bone volume of 7.98 ccm and the highest bone mineral density compared to all other groups. In summary, transplantation of Spongostan™ resulted in increased regeneration of a rat calvarial critical size defect compared to NanoBone and Actifuse, suggesting the distinct nano- and microtopography of wet Spongostan™ to account for this superior regenerative capacity. Since Spongostan™ is a clinically approved product used primarily for haemostasis, it may represent an interesting alternative in the reconstruction of defects in the maxillary region.

The Influence of an Occult Infection on the Outcome of Autologous Bone Grafting During Surgical Bone Reconstruction: A Large Single-Center Case-Control Study

Background

Occult infections (OI) lack typical inflammatory signs, making them challenging to diagnose. Uncertainty remains regarding OI’s influence on the outcome of autologous bone grafting (ABG), and evidence-based recommendations regarding an appropriate course of action are missing. Thus, we sought to determine the incidence of an OI in patients receiving ABG, evaluate whether it influences the outcome of ABG and whether associated risk factors have a further negative influence.

Methods

This study was designed as a large size single-center case-control study investigating patients treated between 01/01/2010 and 31/12/2016 with a minimum follow-up of 12 months. Patients ≥18 years presenting with a recalcitrant non-union of the lower limb receiving surgical bone reconstruction, including bone grafting, were included. A total of 625 patients were recruited, and 509 patients included in the current study. All patients received surgical non-union therapy based on the “diamond concept” including bone reconstruction using ABG. Additionally, multiple tissue samples were harvested and microbiologically analyzed. Tissue samples were microbiologically evaluated regarding an OI. Bone healing was analyzed using clinical and radiological parameters, patient characteristics and comorbidities investigated and ultimately results correlated.

Results

Forty-six out of 509 cases with OI resulted in an incidence of 9.04%. Overall consolidation time was increased by 15.08 weeks and radiological outcome slightly impaired (79.38% vs 71.42%), differences were at a non-significant extent. Diabetes mellitus had a significant negative influence on consolidation time (p=0.0313), while age (p=0.0339), smoking status (p=0.0337), diabetes mellitus (p=0.0400) and increased BMI (p=0.0315) showed a significant negative influence on the outcome of bone grafting.

Conclusion

Surgeons treating recalcitrant non-unions should be aware that an OI is common. If an OI is diagnosed subsequent to ABG the majority of patients does not need immediate revision surgery. However, special attention needs to be paid to high-risk patients.

Investigating the Influence of Architecture and Material Composition of 3D Printed Anatomical Design Scaffolds for Large Bone Defects

There is a significant unmet clinical need to prevent amputations due to large bone loss injuries. We are addressing this problem by developing a novel, cost-effective osseointegrated prosthetic solution based on the use of modular pieces, bone bricks, made with biocompatible and biodegradable materials that fit together in a Lego-like way to form the prosthesis. This paper investigates the anatomical designed bone bricks with different architectures, pore size gradients, and material compositions. Polymer and polymer-composite 3D printed bone bricks are extensively morphological, mechanical, and biological characterized. Composite bone bricks were produced by mixing polycaprolactone (PCL) with different levels of hydroxyapatite (HA) and β-tri-calcium phosphate (TCP). Results allowed to establish a correlation between bone bricks architecture and material composition and bone bricks performance. Reinforced bone bricks showed improved mechanical and biological results. Best mechanical properties were obtained with PCL/TCP bone bricks with 38 double zig-zag filaments and 14 spiral-like pattern filaments, while the best biological results were obtained with PCL/HA bone bricks based on 25 double zig-zag filaments and 14 spiral-like pattern filaments.

The induced membrane technique for the management of long bone defects

AIMS

The purpose of this study was to: review the efficacy of the induced membrane technique (IMT), also known as the Masquelet technique; and investigate the relationship between patient factors and technique variations on the outcomes of the IMT.

METHODS

A systematic search was performed in CINAHL, The Cochrane Library, Embase, Ovid MEDLINE, and PubMed. We included articles from 1 January 1980 to 30 September 2019. Studies with a minimum sample size of five cases, where the IMT was performed primarily in adult patients (≥ 18 years old), in a long bone were included. Multivariate regression models were performed on patient-level data to determine variables associated with nonunion, postoperative infection, and the need for additional procedures.

RESULTS

A total of 48 studies were included, with 1,386 cases treated with the IMT. Patients had a mean age of 40.7 years (4 to 88), and the mean defect size was 5.9 cm (0.5 to 26). In total, 82.3% of cases achieved union after the index second stage procedure. The mean time to union was 6.6 months (1.4 to 58.7) after the second stage. Our multivariate analysis of 450 individual patients showed that the odds of developing a nonunion were significantly increased in those with preoperative infection. Patients with tibial defects, and those with larger defects, were at significantly higher odds of developing a postoperative infection. Our analysis also demonstrated a trend towards the inclusion of antibiotics in the cement spacer having a protective effect against the need for additional procedures.

CONCLUSION

The IMT is an effective management strategy for complex segmental bone defects. Standardized reporting of individual patient data or larger prospective trials is required to determine the optimal implementation of this technique. This is the most comprehensive review of the IMT, and the first to compile individual patient data and use regression models to determine predictors of outcomes. Cite this article: Bone Joint J 2020;102-B(12):1723-1734.

Induced membrane technique: a critical literature analysis and proposal for a failure classification scheme

The reconstruction of long-bone segmental defects remains challenging, with the three common methods of treatment being bone transport, vascularized bone transfer, and the induced membrane technique (IMT). Because of its simplicity, replicability, and reliability, usage of IMT has spread all over the world in the last decade, with more than 300 papers published in the PubMed literature database on this subject so far. Most of the clinical studies have reported high rates of bone union, yet some also include more controversial results with frequent complications and revision surgeries. At the same time, various experimental research efforts have been designed to understand and improve the biological properties of the induced membrane. This literature review aims to provide an overview of IMT clinical results in terms of bone union and complications and to compare them with those of other reconstructive procedures. In light of our findings, we then propose an original classification scheme of IMT failures distinguishing between preventable and nonpreventable failures.

Non-Union Treatment Based on the "Diamond Concept" Is a Clinically Effective and Safe Treatment Option in Older Adults

Background

Patients >60 years suffering from non-unions are often unable to perform activities of daily living and often become dependent on nursing care. Evidence regarding treatment options and outcome is nonexistent. This study sought to determine the clinical effectiveness and safety of one- or two-step non-union therapy in elderly patients.

Methods

This study was a single-site retrospective database analysis of older adults with long bone non-unions treated via “diamond concept”. All medical records of patients receiving surgical treatment of non-unions between 01/01/2010 and 31/12/2016 were reviewed. Clinical and radiological outcome subsequent to non-union therapy were evaluated.

Results

A total of 76 patients (37 patients were treated with one-step and 39 patients with Masquelet therapy) suffering from a non-union older than 60 years treated between 01/01/2010 and 31/12/2016 in our institution were included into the current study. Bone consolidation was achieved in 91.9% after one-step and 76.9% after the Masquelet therapy. Analysis of age as a risk factor in the outcome of non-union therapy revealed no significant differences in patients treated with the one-step procedure according to the “diamond concept”. On the contrary, age had a significant negative influence on the outcome of the Masquelet therapy (p = 0.027).

Conclusion

Non-union therapy according to the “diamond concept” is an effective and reliable treatment option in elderly patients. According to findings of the current study, older adults suffering from an infected non-union benefit from a two-stage procedure, whereas in patients suffering from a non-infected non-union, a one-step surgical treatment is beneficial.

Nonunion - consensus from the 4th annual meeting of the Danish Orthopaedic Trauma Society

Nonunions are a relevant economic burden affecting about 1.9% of all fractures. Rather than specifying a certain time frame, a nonunion is better defined as a fracture that will not heal without further intervention.

Successful fracture healing depends on local biology, biomechanics and a variety of systemic factors. All components can principally be decisive and determine the classification of atrophic, oligotrophic or hypertrophic nonunions. Treatment prioritizes mechanics before biology.

The degree of motion between fracture parts is the key for healing and is described by strain theory. If the change of length at a given load is > 10%, fibrous tissue and not bone is formed. Therefore, simple fractures require absolute and complex fractures relative stability.

The main characteristics of a nonunion are pain while weight bearing, and persistent fracture lines on X-ray.

Treatment concepts such as ‘mechanobiology’ or the ‘diamond concept’ determine the applied osteosynthesis considering soft tissue, local biology and stability. Fine wire circular external fixation is considered the only form of true biologic fixation due to its ability to eliminate parasitic motions while maintaining load-dependent axial stiffness. Nailing provides intramedullary stability and biology via reaming. Plates are successful when complex fractures turn into simple nonunions demanding absolute stability. Despite available alternatives, autograft is the gold standard for providing osteoinductive and osteoconductive stimuli.

The infected nonunion remains a challenge. Bacteria, especially staphylococcus species, have developed mechanisms to survive such as biofilm formation, inactive forms and internalization. Therefore, radical debridement and specific antibiotics are necessary prior to reconstruction.

Cite this article: EFORT Open Rev 2020;5:46-57. DOI: 10.1302/2058-5241.5.190037

Physical Health and Psychological Outcomes in Adult Patients with Long-bone Fracture Non-unions: Evidence Today

Background: Research has suggested that bone fractures can hinder the health status of patients’ life. However, limited research has examined the impact that the healing process of a fracture has on the physical health and psychological state of individuals, particularly in considering the short- and long-term impact of having a fracture that fails to heal and drops into a non-union. The aim of this systematic review is to better understand the impact of fracture non-union to physical health and to respective psychological outcomes. Methods: Electronic databases ‘PubMed’, ‘Cochrane’, ‘PsycInfo’, ‘Medline’, ‘Embase’, ‘Web of Science’, and ‘CINAHL’ were used. Search terms used were nonunion OR non-union OR “non union” OR “long bone” OR “delayed union” AND “quality of life” OR qol OR depression OR anxiety OR psycholog* OR PTSD OR “post-traumatic stress disorder”. Studies published in the years 1995 to 2018 were included. Two independent reviewers carried out screening and data extraction. Studies were included if (1) participants were adult (human) patients with a traumatic non-union secondary to fracture/s; (2) outcomes measured included physical health and psychological wellbeing (e.g., PTSD, psychological trauma, depression, anxiety, etc.). Studies received emphasis if they compared those outcomes between: (1) The “non-union” group to a normative, matched population and (2) the “non-union group” to the same group after union was achieved. However, studies that did not use comparison groups were also included. Results: Out of the 1896 papers identified from our thorough literature search, 13 met the inclusion criteria. Quality assessment was done by the Methodological Index for Non-Randomized Studies (MINORS). Findings suggested that non-unions had a detrimental impact on physical health, and psychological difficulties often after recovery. Conclusions: Patients who experience a long bone non-union are at risk of greater psychological distress and lower physical health status. There is a need for early identification of psychological distress in patients with fracture non-unions and psychological provision should become part of the available treatment.

Does Age Influence the Outcome of Lower Limb Non-Union Treatment? A Matched Pair Analysis

Background: Fractures in elderly patients are common and have severe implications on a socioeconomic level, as musculoskeletal integrity and competence is crucial for independence. Changes in both composition and biology of bones during aging potentially affect fracture healing adversely. The current study sought to determine the influence of age on the outcome of non-union therapy of atrophic and hypertrophic non-unions based on the “diamond concept”, as well as to evaluate the well-known risk factors impairing bone healing. Patients and Methods: All medical records, operative notes, lab data, and radiological imaging of patients that received surgical treatment of both atrophic and hypertrophic non-unions of the femur or tibia between 1 January 2010 and 31 December 2016 were thoroughly reviewed and analyzed. Patients who participated in our standardized follow-up for at least 12 months were included into a database. Patients older than 60 years were matched with patients younger than 60 based on five established criteria. The study was approved by the local ethics committee (S-262/2017). According to our inclusion criteria, a total of 76 patients older than 60 years were eligible for analysis. Via matching, two groups were formed: study group (SG; >60 years; n = 45) and control group (CG; <60 years; n = 45). Results: Twelve months subsequent to treatment, the consolidation rate was equivalent in both groups (SG: 71% vs. CG: 67%). The consolidation for all patients before matching was 73%. The clinical results for the complete collective were no pain or pain with high or medium strain for 62.5%, whereas 29.6% had pain with low strain or constant pain. 7.87% had no pain levels given. Logistic regression modeling showed no influence of age >60 years on radiological or clinical outcome, whereas a significant negative correlation was revealed between patients aged 40–49 years and radiological non-union consolidation (b = −1.145 and p = 0.048). In addition, diabetes had a negative influence on non-union therapy (b = −1.145 and p = 0.048). As expected, the clinical outcome correlated significantly with the radiological outcome (p < 0.001). Conclusion: Surgeons should optimize both modifiable risk factors such as diabetes mellitus, as well as surgical treatment in order to achieve the best possible outcome in elderly patients. Elderly patients benefit from osseous consolidation by enabling and maintaining musculoskeletal competence due to the close correlation between clinical and radiological outcome. Advanced age alone does not negatively influence the outcome of non-union therapy and should, therefore, not be considered a risk factor. In contrast, patients in their fifth decade suffering from lower limb non-unions should be considered as high-risk patients and treatment should be modified accordingly.

Use of Masquelet technique in treatment of septic and atrophic fracture nonunion

BACKGROUND

Treatment of atrophic non-unions and large bone defects or infections remains a challenging task for the treating surgeon. In the herein study, we present our experience of the 'Masquelet technique' according to the 'diamond concept' for the treatment of complex long bone reconstruction procedures.

METHODS

Between February 2010 and March 2015, 150 patients (mean age 51.4) with atrophic and- /or infected non-unions were included in this prospective study. All patients received autologous bone graft, a graft expander (TCP (tricalcium phosphate)) and BMP (bone morphogenic protein). Clinical and radiological parameters were assessed at 6 weeks, and at 3, 6 and 12 months. The SF-12 questionnaire was used to evaluate the subjective health of patients.

RESULTS

A successful bony consolidation of the non-unions was observed in 120 (80%) cases with a median healing time of 12.1 months. The mean defect gap was 4.4cm. Initial infection was documented in 54 cases. The most frequently identified pathogen was staphylococcus epidermidis and staphylococcus aureus. A successful removal of microorganisms with subsequent healing was achieved in 39 cases (72%). The SF-12 scores of subjective physical and mental health increased from PCS 31.5 preoperatively to 36.7 one year postoperatively, while MCS increased from 45.5 to 48.7.

CONCLUSIONS

Our study showed that the Masquelet technique according to the 'diamond concept' is a valid method to treat complex atrophic non-unions with large bone defects and associated infection. Following the principles of the 'diamond concept' (targeted optimization of tissue engineering and bone regeneration) a high rate of success can be expected in these difficult reconstruction cases.

[Stimulation of fracture healing by growth factors and cell-based technologies]

Bone has the special capability to completely regenerate after trauma and to re-establish its original geometry and biomechanical stability corresponding to the pretrauma conditions. Nevertheless, in daily clinical practice impaired fracture healing and nonunions are regular complications as a result of inadequate mechanical stability and/or insufficient biological processes around the fracture region. Since the beginning of the millennium, intensive research on the physiological processes in bone healing as well as the production and clinical administration of growth factors have enabled the possibility to improve the local biological processes during fracture healing by osteoinduction. Although the initial clinical results, particularly of bone morphogenetic proteins, in fracture healing were promising, growth factors did not become established for unrestricted use in the clinical application. Currently, additional growth factors are being investigated with respect to the potential supportive and osteoinductive characteristics for enhancement of fracture healing and possible clinical applications. Furthermore, the development of cell-based technologies is another promising approach to positively stimulate fracture healing. In addition to the gold standard of autologous bone grafting, harvesting of mesenchymal stroma cells by aspiration has gained in importance in recent years. Allogeneic bone cell transplantation procedures and in particular gene therapy are promising new strategies for the treatment of disorders of fracture healing. This review gives an overview of present and future possibilities for modulation of fracture healing by growth factors and cell-based technologies.

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.

Comparison of the clinical effectiveness of Bone Morphogenic Protein (BMP) -2 and -7 in the adjunct treatment of lower limb nonunions

BACKGROUND

Substantial evidence exists demonstrating the individual effectiveness of both rhBMP-2 and -7 in the treatment of nonunions, data comparing the clinical effectiveness of adjunct rhBMP-2 and -7 remains scarce. Therefore, we examined our large single-center case series to compare the clinical effectiveness of both rhBMP-2 and -7 in non-union therapy aiming to answer: - Does a certain type of BMP have an advantageous effect on radiological outcome of applied lower limb non-union therapy? - Does application of a certain type of BMP have an advantageous effect on radiological outcome of infected lower limb nonunions? - Are there any additional risk factors associated with inferior outcome in context with an adjunct BMP treatment?

HYPOTHESIS

Both BMPs have the same effect on the radiological outcome of surgically treated lower limb nonunions.

PATIENTS AND METHODS

Single-center retrospective database analysis of a case series of patients with lower limb long bone nonunions receiving either a one- or two-stage (Masquelet-) procedure based on the "diamond concept" with application of rhBMP-2 or -7. The "diamond concept" summarizes core factors that need to be present to achieve bone healing. In particular, these factors relate to the optimization of the mechanical (stability) and biological environment (sufficient osteogenic and angiogenic cells, osteoconductive scaffolds and growth factors). All medical data from patients that received surgical treatment between 01/01/2010 and 31/12/2016 were assessed. In total, 356 patients were treated with BMPs and 156 patients 18 years or older with non-union of their tibia or femur having a follow-up of at least 1 year were included. Consolidation in context with type of rhBMP was compared and the influence of relevant risk factors assessed.

RESULTS

Consolidation rate was significantly higher in patients treated with rhBMP-2 (rhBMP-2: 42/46 (91%) vs. rhBMP-7: 64/110 (58%); p<0.001). In particular, application of rhBMP-2 increased the likelihood of consolidation for tibial nonunions (OR 32.744; 95%CI: 2.909-368.544; p=0.005) and when used in two-stage therapy (OR 12.095; 95% CI: 2.744-53.314; p=0.001). Furthermore, regression modeling revealed a higher correlation between application of rhBMP-2 and osseous consolidation in infected nonunions (OR 61.062; 95% CI: 2.208-1688.475; p=0.015) than in aseptic nonunions (OR 4.787; 95% CI: 1.321-17.351; p=0.017). Risk factors negatively influencing the outcome of non-union treatment in context with rhBMPs were identified as active smoking (OR 0.357; 95% CI: 0.138-0.927; p=0.024), atrophic nonunion (OR 0.23; 95% CI: 0.061-0.869; p=0.030), higher BMI (OR 0.919; 95% CI: 0.846-0.998; p=0.046) and a larger defect size (OR 0.877; 95% CI: 0.784-0.98; p=0.021).

DISCUSSION

Patients who received rhBMP-2 for the treatment of tibial nonunions and as part of the two-stage treatment had a significantly higher rate of healing compared to patients treated with rhBMP-7 regardless of infection.

LEVEL OF EVIDENCE

III, retrospective case-control study.

Chemokine analysis as a novel diagnostic modality in the early prediction of the outcome of non-union therapy: a matched pair analysis

BACKGROUND

Despite the regenerative capability of skeletal tissue fracture, non-union is common. Treatment of non-unions remains challenging, and early determination of the outcome is impossible. Chemokines play an important role in promoting the formation of new bone and remodeling existing bone. Despite their importance regarding the regulation of bone biology, the potential of chemokines as biological markers reflecting osseous regeneration is unknown. The purpose of this study was to determine (1) if serum chemokine expression levels correlate with the outcome of non-union surgery and (2) if chemokine expression analysis can be used to identify patients at risk for treatment failure.

METHODS

Non-union patients receiving surgical therapy in our institution between March 2012 and March 2014 were prospectively enrolled in a clinical observer study. Regular clinical and radiological follow-up was conducted for 12 months including collection of blood during the first 12 weeks. Based on the outcome, patients were declared as responders or non-responders to the therapy. To minimize biases, patients were matched (age, sex, body mass index (BMI)) and two groups of patients could be formed: responders (R, n = 10) and non-responders (NR, n = 10). Serum chemokine expression (CCL-2, CCL-3, CCL-4, CXCL-10, CCL-11, and interferon gamma (IFN-γ)) was analyzed using Luminex assays. Data was compared and correlated to the outcome.

RESULTS

CCL-3 expression in NR was significantly higher during the course of the study compared to R (p = 0.002), and the expression pattern of CCL-4 correlated with CCL-3 in both groups (NR: p < 0.001 and r = 0.63). IFN-γ expression in NR was continuously higher than in R (p < 0.001), and utilization of CCL-3 and IFN-γ serum expression levels 2 weeks after the treatment resulted in a predictive model that had an AUC of 0.92 (CI 0.74-1.00).

CONCLUSION

Serum chemokine expression analysis over time is a valid and promising diagnostic tool. The chemokine expression pattern correlates with the outcome of the Masquelet therapy of lower limb non-unions. Utilization of the serum analysis of CCL-3 and IFN-γ 2 weeks after the treatment resulted in an early predictive value regarding the differentiation between patients that are likely to heal and those that are prone to high risk of treatment failure.

Evaluation of matrix metalloproteases as early biomarkers for bone regeneration during the applied Masquelet therapy for non-unions

INTRODUCTION

In the current study, we sought to determine if serum concentrations of MMPs correlate with bone regeneration occurring during the course of the Masquelet-therapy and to identify if MMPs may serve as early biomarkers reflecting successful bone regeneration and tissue remodeling.

MATERIAL AND METHODS

This study was designed as a prospective clinical observer study. We compared serum samples over the time of treatment, as a matched-pair analysis, from 10 patients who were treated successfully with the Masquelet-therapy (Responder) with 10 patients who did not respond to the Masquelet-therapy (Non-Responder). The quantitative measurement was performed with Luminex Performance Human High Sensitivity Assays according to manufacturer's instructions. The lab technician performing the Luminex assays was blinded to both patient data and clinical outcome.

RESULTS

Analysis of the expression pattern of MMP-2, -8 and -9 showed significant differences between groups. Two days after the first step of the Masquelet therapy Responder showed peak values of MMP-8 and MMP-9 that where significantly higher (p = 0.003 and p = 0.042, respectively) than in Non-Responder. In contrast serum levels of MMP-2 were lower after the first step of the Masquelet therapy in the Non-Responder group. The ratio of MMP-9 and MMP-2 was significantly higher in the Responder group two days after step I (p = 0.031) as well as 4 weeks after step II (p = 0.030).

CONCLUSION

The findings of the current study emphasize the potential role of MMPs as biomarkers in bone remodeling. In particular, a distinct expression of MMP-2 correlates with successful bone regeneration, whereas initial overexpression of MMP-2 serum levels might identify patients that have a higher risk for a poor outcome of the Masquelet-therapy. Furthermore, we were able to introduce the serum analysis of the ratio of MMP-9 and MMP-2 as promising novel modality for early prediction of the outcome of the Masquelet therapy. Further analysis of this ratio over time subsequent to the second step might serve as an early indicator of a favorable response to the induced membrane technique.

Management of septic non-union of the tibia by the induced membrane technique. What factors could improve results?

INTRODUCTION

Management of septic non-union of the tibia requires debridement and excision of all infected bone and soft tissues. Various surgical techniques have been described to fill the bone defect. The "Induced Membrane" technique, described by A. C. Masquelet in 1986, is a two-step procedure using a PMMA cement spacer around which an induced membrane develops, to be used in the second step as a bone graft holder for the bone graft. The purpose of this study was to assess our clinical and radiological results with this technique in a series managed in our department.

MATERIAL AND METHOD

Nineteen traumatic septic non-unions of the tibia were included in a retrospective single-center study between November 2007 and November 2014. All patients were followed up clinically and radiologically to assess bone union time. Multivariate analysis was used to identify factors influencing union.

RESULTS

The series comprised 4 women and 14 men (19 legs); mean age was 53.9 years. Vascularized flap transfer was required in 26% of cases before the first stage of treatment. All patients underwent a two-step procedure, with a mean interval of 7.9 weeks. Mean bone defect after the first step was 52.4mm. The bone graft was harvested from the iliac crest in the majority of cases (18/19). The bone was stabilized with an external fixator, locking plate or plaster cast after the second step. Mean follow-up was 34 months. Bony union rate was 89% (17/19), at a mean 16 months after step 2. Eleven patients underwent one or more (mean 2.1) complementary procedures. Severity of index fracture skin opening was significantly correlated with union time (Gustilo III vs. Gustilo I or II, p=0.028). A trend was found for negative impact of smoking on union (p=0.06). Bone defect size did not correlate with union rate or time.

DISCUSSION

The union rate was acceptable, at 89%, but with longer union time than reported in the literature. Many factors could explain this: lack of rigid fixation after step 2 (in case of plaster cast or external fixator), or failure to cease smoking. The results showed that the induced membrane technique is effective in treating tibial septic non-union, but could be improved by stable fixation after the second step and by cessation of smoking.

LEVEL OF EVIDENCE

IV, Retrospective study.

Evaluation of the clinical effectiveness of bioactive glass (S53P4) in the treatment of non-unions of the tibia and femur: study protocol of a randomized controlled non-inferiority trial

BACKGROUND

Treatment of non-union remains challenging and often necessitates augmentation of the resulting defect with an autologous bone graft (ABG). ABG is limited in quantity and its harvesting incurs an additional surgical intervention leaving the risk for associated complications and morbidities. Therefore, artificial bone graft substitutes that might replace autologous bone are needed. S53P4-type bioactive glass (BaG) is a promising material which might be used as bone graft substitute due to its osteostimulative, conductive and antimicrobial properties. In this study, we plan to examine the clinical effectiveness of BaG as a bone graft substitute in Masquelet therapy in comparison with present standard Masquelet therapy using an ABG with tricalciumphosphate to fill the bone defect.

METHODS/DESIGN

This randomized controlled, clinical non-inferiority trial will be carried out at the Department of Orthopedics and Traumatology at Heidelberg University. Patients who suffer from tibial or femoral non-unions with a segmental bone defect of 2-5 cm and who are receiving Masquelet treatment will be included in the study. The resulting bone defect will either be filled with autologous bone and tricalciumphosphate (control group, N = 25) or BaG (S53P4) (study group, N = 25). Subsequent to operative therapy, all patients will receive the same standardized follow-up procedures. The primary endpoint of the study is union achieved 1year after surgery.

DISCUSSION

The results from the current study will help evaluate the clinical effectiveness of this promising biomaterial in non-union therapy. In addition, this randomized trial will help to identify potential benefits and limitations regarding the use of BaG in Masquelet therapy. Data from the study will increase the knowledge about BaG as a bone graft substitute as well as identify patients possibly benefiting from Masquelet therapy using BaG and those who are more likely to fail, thereby improving the quality of non-union treatment.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS), ID: DRKS00013882 . Registered on 22 January 2018.