Ergebnisse der Pseudarthrosenbehandlung mit „bone morphogenetic protein 7“ (BMP-7)

Therapeutic effect of autologous bone grafting with adjuvant bone morphogenetic protein on long bone nonunion: a systematic review and meta-analysis

BACKGROUND

The recombinant human bone morphogenetic protein (rhBMP) is a common graft substitute for treating cases of long bone nonunion. However, the feasibility of combining an autologous bone graft (ABG) with rhBMPs remains uncertain. Thus, this systematic review and meta-analysis aimed to evaluate the synergistic effect of ABG and rhBMPs on the healing of long bone nonunion.

METHODS

A systematic literature search was performed on PubMed, Web of Science, Cochrane Library, and China National Knowledge Infrastructure. Two authors independently screened the studies, extracted data, and assessed the quality of the trials. Statistical analyses were performed using Stata 12.0.

RESULTS

Of the 202 citations, five studies involving a total of 394 cases met the eligibility criteria; thus, they were included in this study. The pooled data revealed no significant differences among the groups in terms of postoperative healing rate (risk ratio [RR] = 1.01, 95% confidence interval [CI] = 0.96-1.06, P = 0.744), healing time (standardised mean difference =  - 0.20, 95% CI = - 0.95-0.56, P = 0.610), and pain (RR = 1.44, 95% CI = 0.25-8.29, P = 0.681). The combination of ABG and rhBMPs resulted in good limb function (RR = 1.31, 95% CI = 1.04-1.66, P = 0.023).

CONCLUSIONS

The combination of ABG and rhBMPs did not result in the healing of long bone nonunion and pain reduction. Nevertheless, it conferred good limb function. Thus, the findings in this study are insufficient to support the use of rhBMPs as an adjuvant to ABG.

The medial femoral condyle free corticoperiosteal flap versus traditional bone graft for treatment of nonunions of long bones: a retrospective comparative cohort study

Fracture healing is a complex process and many factors change the local biology of the fracture and reduce the physiologic repair process. Since 1991 the free vascularised corticoperiosteal graft has been proposed to treat nonunions. In this study we compare the healing rate and the healing time of the free vascularised corticoperiosteal graft harvested from medial femoral condyle versus the traditional cancellous bone graft from the iliac crest combined with other biologic or pharmacologic factors. We performed a retrospective cohort study. The main measures of outcomes were the rate of bone union and the mean healing time from surgery. The authors performed 10 free vascularised corticoperiosteal grafts in the cohort A and 10 patients received traditional cancellous bone graft plus other biologic or pharmacologic treatment in the same period in the cohort B. The mean follow up in cohort A was 18.6 months with a healing rate of 100% (10/10). In cohort B the mean follow up was 22.5 month with a healing rate of 90%. The mean time to obtain union (healing time) in the group that was treated with the free flap procedure was significantly shorter, 3.2 months versus a mean time of 8.8 months in the other group. Some studies describe a high healing rate of recalcitrant nonunions with treatments different from vascularized bone flaps: it is difficult to compare the results of vascularized bone transfers with the results of other case series. Our groups are very homogeneous even if it is difficult to define correct inclusion criteria because there is still no agreement about what is defined a recalcitrant or difficult nonunion, and the number of trials of previous surgery before to perform a vascularized free flap. Even if our study cohort is small, we have demonstrated that the MFCCF generally seems to give a better healing chance with a shorter healing time compared to other treatments.

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.

Evaluation of the clinical use of the ETN PROtect® in non-union therapy

INTRODUCTION

Non-union of a long bone fracture remains a challenge in orthopaedic and trauma surgery. In the current study, we sought to determine the clinical effectiveness of tibial non-union treatment utilizing an antibiotic-coated intramedullary nail (Expert Tibia Nail (ETN) PROtect®) regarding prevention and treatment of infection and the clinical outcome.

PATIENTS AND METHODS

36 patients suffering from tibial non-unions that were treated with the ETN PROtect® in the course of non-union treatment between February 2010 and March 2015 were included in this clinical observational study. Clinical and radiological examinations were performed preoperatively as well as 4, 6 and 12 weeks and 6 and 12 months postoperatively as part of a standardized follow-up program. Data regarding perioperative complications, weight-bearing capacity, radiological signs of consolidation and subjective health status were assessed at each time point. Laboratory parameters such as C-reactive protein (CRP) and leukocyte count were collected preoperatively in order to assess the patients' risk profile for infection.

RESULTS

Patients had an average of 6.2 previous surgeries and 22 patients (61.1%) had a positive bacterial culture from intraoperatively removed tissue during the first operative treatment. 29 patients (80.6%) achieved full weight-bearing after an average of 7.7 months, furthermore 80.6% of patients achieved osseous consolidation. 3 deep infections occurred, including one amputation. Subjective health status increase based on the SF-12 questionnaire during our follow-up program.

CONCLUSION

The results from the current study indicate that the use of the ETN PROtect® in the applied non-union therapy has a high clinical effectiveness regarding osseous consolidation and time to weight bearing. In addition, the use of gentamicin-coated nails in the treatment of tibial non-unions might contribute to both successful treatment of the underlying infection and prevention of perioperative infection. The gentamicin-coated nail may serve as a beneficial adjunct treatment in the applied non-union therapy in addition to all established techniques in the treatment of infected non-unions.

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.

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.

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.

Bone morphogenetic proteins - 7 and - 2 in the treatment of delayed osseous union secondary to bacterial osteitis in a rat model

Background

Bone infections due to trauma and subsequent delayed or impaired fracture healing represent a great challenge in orthopedics and trauma surgery. The prevalence of such bacterial infection-related types of delayed non-union is high in complex fractures, particularly in open fractures with additional extensive soft-tissue damage. The aim of this study was to establish a rat model of delayed osseous union secondary to bacterial osteitis and investigate the impact of rhBMP-7 and rhBMP-2 on fracture healing in the situation of an ongoing infection.

Methods

After randomization to four groups 72 Sprague-Dawley rats underwent a transverse fracture of the midshaft tibia stabilized by intramedullary titanium K-wires. Three groups received an intramedullary inoculation with Staphylococcus aureus (10³ colony-forming units) before stabilization and the group without bacteria inoculation served as healing control. After 5 weeks, a second surgery was performed with irrigation of the medullary canal and local rhBMP-7 and rhBMP-2 treatment whereas control group and infected control group received sterile saline. After further 5 weeks rats were sacrificed and underwent biomechanical testing to assess the mechanical stability of the fractured bone. Additional micro-CT analysis, histological, and histomorphometric analysis were done to evaluate bone consolidation or delayed union, respectively, and to quantify callus formation and the mineralized area of the callus.

Results

Biomechanical testing showed a significantly higher fracture torque in the non-infected control group and the infected rhBMP-7- and rhBMP-2 group compared with the infected control group (p < 0.001). RhBMP-7 and rhBMP-2 groups did not show statistically significant differences (p = 0.57). Histological findings supported improved bone-healing after rhBMP treatment but quantitative micro-CT and histomorphometric results still showed significantly more hypertrophic callus tissue in all three infected groups compared to the non-infected group. Results from a semiquantitative bone-healing-score revealed best bone-healing in the non-infected control group. The expected chronic infection was confirmed in all infected groups.

Conclusions

In delayed bone healing secondary to infection rhBMP treatment promotes bone healing with no significant differences in the healing efficacy of rhBMP-2 and rhBMP-7 being noted. Further new therapeutic bone substitutes should be analyzed with the present rat model for delayed osseous union secondary to bacterial osteitis.

Insulin-Like Growth Factor-1 as a Possible Alternative to Bone Morphogenetic Protein-7 to Induce Osteogenic Differentiation of Human Mesenchymal Stem Cells in Vitro

Growth factors and mesenchymal stem cells (MSC) support consolidation of bone defects. Bone Morphogenetic Protein-7 (BMP-7) has been used clinically and experimentally, but the outcomes remain controversial. Increased systemic expression of Insulin-like Growth Factor-1 (IGF-1) significantly correlates with successful regeneration of bone healing disorders, making IGF-1 a promising alternative to BMP-7. There is no experimental data comparing the osteoinductive potential of IGF-1 and BMP-7. Therefore, in this study, the influence of IGF-1 and BMP-7 in different concentrations on the osteogenic differentiation of two human MSC-subtypes, isolated from reaming debris (RMSC) and iliac crest bone marrow (BMSC) has been assessed. A more sensitive reaction of BMSC towards stimulation with IGF-1 in concentrations of 400–800 ng/mL was found, leading to a significantly higher degree of osteogenic differentiation compared to stimulation with BMP-7. RMSC react more sensitively to stimulation with BMP-7 compared to BMSC. Lower concentrations of IGF-1 were necessary to significantly increase osteogenic differentiation of RMSC and BMSC compared to BMP-7. Therefore, IGF-1 should be considered as a valuable option to improve osteogenic differentiation of MSC and merits further experimental consideration. The MSC subtype and method of differentiation factor application also have to be considered, as they affect the outcome of osteogenic differentiation.

Safety study: is there a pathologic IGF-1, PDGF and TGF-β cytokine expression caused by adjunct BMP-7 in tibial and femoral non-union therapy?

Background

In this prospective safety study, we investigated if the characteristic cytokine expression during bone regeneration is manipulated by the local application of bone morphogenetic protein-7 (BMP-7) in non-union surgery. Therefore, the levels of insulin like growth factor 1 (IGF-1), platelet-derived growth factor AB (PDGF-AB) and transforming growth factor beta (TGF-β) were compared between patients with the gold standard use of autologous bone graft (ABG) and those with additional application of BMP-7 as part of the diamond concept.

Patients and methods

Between 2009 and 2014, of the 153 patients with tibial and femoral non-unions, a matched pair analysis was performed to compare the serological cytokine expressions. Blood samples were collected preoperatively, 1, 2 and 6 weeks as well as 3 and 6 months after non-union surgery. Matching criteria were smoking status, fracture location, gender, age and body mass index (BMI). Patients in G1 (n=10) were treated with ABG and local BMP-7 while their matching partners in G2 (n=10) received ABG only. The routine clinical and radiologic follow-up was 1 year.

Results

Although the IGF-1 quantification in G2 showed higher pre- and postoperative values compared to G1 (p<0.05), the courses of both groups were similar. Likewise, PDGF-AB and TGF-β expressions appeared similar in G1 and G2 with peaks in both groups at 2 weeks follow-up. Osseous consolidation was assessed in all operated non-unions. The adjunct application of BMP-7 did not cause any pathologic cytokine expression.

Conclusion

Similar expressions of the serum cytokines IGF-1, PDGF-AB and TGF-β were demonstrated in non-union patients treated with ABG and additional application of BMP-7 according to the diamond concept. Our findings indicate that the local application of BMP-7, which imitates the physiologic secretion of growth factors during bone regeneration, is safe and without the risk of abnormal systemic cytokine expression. Studies with higher patient numbers will have to validate these assumptions.

Mesenchymal stem cells from reaming material possess high osteogenic potential and react sensitively to bone morphogenetic protein 7

BACKGROUND

Femoral material harvested using the Reamer-Irrigator-Aspirator (RIA) system is an alternative source for autogenous bone material in the treatment of non-unions, especially in combination with bone morphogenetic proteins (BMP). So far, there is no in vivo evidence of BMP-7 interacting with mesenchymal stem cells (MSCs) from RIA material (RIA-MSCs) and iliac crest autogenous bone (BMSCs). The aim of this study was to compare their osteogenic potential when stimulated with BMP-7 in vivo.

METHODS

RIA-MSC and BMSC from 11 donors were isolated and the character of MSCs was investigated in vitro. Constructs consisting of MSC, β-tricalcium phosphate and 2 concentrations of BMP-7 (0.1 µg/mL and 1 µg/mL) were implanted in mice for 8 weeks. Bone formation in the constructs was analyzed quantitatively and qualitatively.

RESULTS

All cell populations used were determined to be MSCs. The qualitative in vivo analysis showed formation of bone tissue. With regard to quantity, bone formation was significantly higher in RIA constructs without or with stimulation with 0.1 µg/mL BMP-7, compared with BMSC constructs. We found no significant differences between constructs stimulated with 1 µg/mL BMP-7. In the RIA group, we observed a significant increase in bone formation after stimulation with 0.1 µg/mL BMP-7. No significant change could be found using a higher concentration. In the BMSC group, we detected a significant increase when using 0.1 µg/mL and 1 µg/mL BMP-7.

CONCLUSIONS

RIA material is a source of MSCs with high osteogenic potential. Our results showed that stimulation by BMP-7 leads to an increased osteogenic potential of MSCs. In this respect, RIA-MSCs reacted more sensitively than BMSCs.

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

BACKGROUND

The treatment of non-unions in long bones poses a great challenge, particularly in cases of infection or large osseous defects. This article evaluates the use of the diamond concept in the treatment of femoral non-unions in a one-step or two-step procedure according to the Masquelet technique.

PATIENTS AND METHODS

Between February 2010 and March 2014, 88 patients with atrophic femoral non-unions were included in our study. The treatment was performed in one step (Group G1) on 41 patients and in two-step Masquelet technique (Group G2) on 47 patients, according to the diamond concept. In 72 cases it was decided to apply the growth factor BMP-7. The mean age of patients was 49.9 ± 15.3. The data were analysed after following up all patients for at least 12 months after surgery.

RESULTS

74% of patients achieved consolidation in an average of 9.3 months. Positive bacterial cultures were found in 16 cases (18%). The consolidation rate in G2 was dependent on the non-union localisation and the osteosynthesis method applied. 83% of patients treated by intramedullary reaming achieved consolidation, while this was the case for only 60% of patients with osteosynthesis plates. Smokers in G2 had a larger average osseous defect and a lower consolidation rate. The quality of life as assessed with the SF-12 questionnaire had improved in both groups, with no significant differences between G1 and G2 one year after surgery.

CONCLUSIONS

One-step therapy is a suitable method of treatment for aseptic femoral non-unions with small osseous defects, using BMP-7 and RIA in the case of primarily failed atrophic non-union treatment. The Masquelet technique is an efficient means of eradicating infections in non-unions. In combination with intramedullary nailing, this technique is the method of choice for the treatment of femoral shaft non-unions with large defects.

The treatment of nonunions with application of BMP-7 increases the expression pattern for angiogenic and inflammable cytokines: a matched pair analysis

The local application of bone morphogenetic protein-7 (BMP-7) in combination with the transplantation of autologous bone graft improves the outcome in nonunion treatment; however, the specific reasons remain unclear. In this study, we sought to determine if the local application of BMP-7 contributes to improved bone regeneration in nonunion therapy by modulation of the angiogenic and inflammable cytokine expression patterns of the early inflammation response. Therefore, we utilized the analysis of serological cytokine expression patterns. As a matched pair analysis, best-fitting patients who were treated with transplantation of autologous bone graft (G1, n=10) were compared with patients who were treated with additional application of BMP-7 (G2, n=10). The changes in the cytokine expression patterns were monitored and correlated to clinical data of bone healing. Significant differences in angiogenesis potential (vascular endothelial growth factor [VEGF] serum levels) could be found in the first days after surgery (P<0.05). Furthermore, the increase and absolute amount of VEGF levels in the BMP-7 group were considerably higher than in the control group during the first 2 weeks after surgery. The expression pattern of inflammable cytokines showed noticeable differences in the time point of significant elevated levels, in particular, inflammable cytokines showed an earlier peak in G2. Furthermore, interleukin-6 was significantly elevated within the first week only, comparing G2 to G1 (P<0.05). Our findings indicate that BMP-7 induces an early and more intense expression of VEGF via a direct and postulated indirect pathway, thereby providing a favorable environment for bone healing. Moreover, application of BMP-7 leads to an earlier expression of known proinflammatory cytokines. The results of this study show that application of BMP-7 leads to costimulatory effect on both angiogenic and inflammable cytokine expression patterns that may serve as a possible stimulus for bone regeneration.

Treatment with recombinant human bone morphogenetic protein 7 leads to a transient induction of neutralizing autoantibodies in a subset of patients

Background

Recombinant human bone morphogenetic protein 7 (rhBMP7) is applied for treatment of bone fractures, especially tibial non-unions. Its application may induce autoantibodies (aAB) affecting the targeted and endogenous signaling pathways and in turn negatively impact treatment efficacy.

Methods

Novel and sensitive assays for the quantification of BMP7-aAB and BMP2-aAB were established and used to analyze serum samples from healthy controls (n = 100 men, n = 100 women) and patients with long bone fracture (n = 265) treated or not with rhBMP7. Sera from three to nine time points per patient were available and enabled the evaluation of aAB over a time course of up to one year. Functional activity of the BMP-aAB was tested with a BMP-responsive cell-based reporter assay. Consolidation of the fracture was evaluated as clinical outcome potentially affected by BMP7-aAB.

Results

Prevalence of BMP7-aAB and BMP2-aAB was 1–2.5% in non-treated patients or healthy controls. The rhBMP7 treatment induced a transient increase in BMP7-aAB in a subset of patients, returning to non-detectable levels within six months. IgG from BMP7-aAB positive sera inhibited dose dependently the BMP7-reporter gene activity, whereas control sera were without effect. Successful consolidation of the fracture was observed in the majority of both aAB-positive and aAB-negative patients.

General significance

We conclude that BMP7-aAB can be detected as natural aAB in healthy subjects, and are transiently induced by rhBMP7 therapy in a subset of patients. The aAB are capable of antagonizing BMP7 signaling in vitro, but do not preclude treatment success in patients.

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There are patients with natural autoantibodies recognizing BMP7.

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In some patients, rhBMP7-therapy induces BMP7 autoantibodies.

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BMP7 autoantibodies elicit neutralizing effects on BMP signaling.

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Therapy-induced BMP7 autoantibodies disappear over time.

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BMP7 autoantibodies seem not to affect therapy success.

Low intensity pulsed ultrasound in the treatment of long bone nonunions: Evaluation of cytokine expression as a tool for objectifying nonunion therapy

BACKGROUND

Nonunion is one of the most common complications in bone healing. After several clinical studies, the effect of low intensity pulsed ultrasound (LIPUS) in the treatment of nonunions remains unclear because of the difficulty in evaluating its effect on bone healing. In former studies, the analysis of serum cytokine expression patterns over time has proven to be an objective method for showing the bone healing process and evaluating nonunion therapies. This study evaluates LIPUS as a treatment option for patients with nonunions based on the analysis of serum cytokine expression.

METHODS

In this prospective, single institution study, venous blood samples from 23 patients were taken from October 2012 to October 2013 before starting LIPUS therapy and at the end of week 1 and 2 and after 1, 2, and 3 months. Patients attended clinical and radiological follow-up examinations at the same intervals. After treating all patients according to the LIPUS therapy protocol, we divided them into two groups: Group 1 consisted of patients with healing at the nonunion site, and Group 2 consisted of patients with failed nonunion therapy. We measured transforming growth factor-β1 (TGF-β1), platelet-derived growth factor (PDGF), and basic fibroblastic growth factor (bFGF) at all time-points.

RESULTS

The TGF-β1 serum concentration increased from the pre-treatment value to 1 week within the unsuccessful group. Otherwise, no significant differences between groups in measured cytokines during LIPUS therapy could be detected.

CONCLUSION

Our findings suggest that LIPUS does not lead to a significant increase in cytokine levels in patients with nonunions. It is likely that "successful" treatment can be attributed to spontaneous healing. Our results suggest that LIPUS is not a proper treatment for long bone nonunions.

Modulation of Osteogenesis in MC3T3-E1 Cells by Different Frequency Electrical Stimulation

Electrical stimulation (ES) is therapeutic to many bone diseases, from promoting fracture regeneration to orthopedic intervention. The application of ES offers substantial therapeutic potential, while optimal ES parameters and the underlying mechanisms responsible for the positive clinical impact are poorly understood. In this study, we assembled an ES cell culture and monitoring device. Mc-3T3-E1 cells were subjected to different frequency to investigate the effect of osteogenesis. Cell proliferation, DNA synthesis, the mRNA levels of osteosis-related genes, the activity of alkaline phosphatase (ALP), and intracellular concentration of Ca²⁺ were thoroughly evaluated. We found that 100 Hz could up-regulate the mRNA levels of collagen I, collagen II and Runx2. On the contrary, ES could down-regulate the mRNA levels of osteopontin (OPN). ALP activity assay and Fast Blue RR salt stain showed that 100 Hz could accelerate cells differentiation. Compared to the control group, 100 Hz could promote cell proliferation. Furthermore, 1 Hz to 10 Hz could improve calcium deposition in the intracellular matrix. Overall, these results indicate that 100Hz ES exhibits superior potentialities in osteogenesis, which should be beneficial for the clinical applications of ES for the treatment of bone diseases.

Non-unions treated with bone morphogenic protein 7: introducing the quantitative measurement of human serum cytokine levels as promising tool in evaluation of adjunct non-union therapy

BACKGROUND

In this study we sought to determine if application of bone morphogenic protein 7 (BMP-7) promotes physiological bone healing of non-unions and to investigate if serum cytokine analysis may serve as a promising tool in the analysis of adjunct non-union therapy. Therefore we analyzed the influence of BMP-7 application on the serum cytokine expression patterns on patients with impaired bone healing compared to patients that showed proper bone healing.

METHODS

Our study involved analyzing blood samples from 208 patients with long bone fractures together with patients that subsequently developed non-unions. From this large pool, 15 patients with atrophic non-union were matched to 15 patients with atrophic non-union treated with local application of BMP-7 as well as normal bone healing. Changes in the cytokine expression patterns were monitored during the 1st, 2nd, 4th, 8th, 12th and 52nd week. The patients were followed both clinically and radiologically for the entire duration of the study. Serum cytokine expression levels of transforming growth factor beta (TGF-β), platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) were analyzed and compared.

RESULTS

Serum expression of TGF-β were nearly parallel in all three groups, however serum concentrations were significantly higher in patients with proper bone healing and those treated with BMP-7 than in patients with non-unions (p < 0.05). bFGF serum concentrations increased initially in patients with proper bone healing and in those treated with BMP-7. Afterwards, values decreased; bFGF serum concentrations in the BMP-7 group were significantly higher than in the other groups (p < 0.05). PDGF serum concentration levels were nearly parallel in all groups, serum concentrations were significantly higher in patients with proper bone healing and those treated with BMP-7 than in patients with non-unions (p < 0.05).

CONCLUSION

Treatment with BMP-7 in patients with former non-unions led to similar cytokine expression patterns after treatment as those found in patients with proper bone healing. Our results suggest that treatment with BMP-7 promote healing of non-unions. Furthermore, quantitative measurement of serum cytokine expression is a promising tool for evaluating the effectiveness of additional non-union therapies such as adjunct application of growth factors.

Treatment of nonunions in fractures of the humeral shaft according to the Diamond Concept

Methods

Between 2005 and 2012, 50 patients (23 female, 27 male) with nonunion of the humeral shaft were included in this retrospective study. The mean age was 51.3 years (14 to 88). The patients had a mean of 1.5 prior operations (sd 1.2;1 to 8). All patients were assessed according to a specific risk score in order to devise an optimal and individual therapy plan consistent with the Diamond Concept. In 32 cases (64%), a change in the osteosynthesis to an angular stable locking compression plate was performed. According to the individual risk an additional bone graft and/or bone morphogenetic protein-7 (BMP-7) were applied.

Results

A successful consolidation of the nonunion was observed in 37 cases (80.4%) with a median healing time of six months (IQR 6). Younger patients showed significantly better consolidation. Four patients were lost to follow-up. Revision was necessary in a total of eight (16%) cases. In the initial treatment, intramedullary nailing was most common.

Discussion

The use of locking compression plates in combination with autologous cancellous bone graft has been shown to be a safe and effective treatment. In more complex cases, the use of the Masquelet technique and BMP-7 may be indicated at the first revision operation. Take home message: Our results suggest the Diamond Concept is a successful treatment strategy for nonunions of the humeral shaft. Cite this article: Bone Joint J 2016;98-B:81–7.

Failed treatment of long bone nonunions with low intensity pulsed ultrasound

INTRODUCTION

The use of low intensity pulsed ultrasound (LIPUS) in the treatment of nonunions is still controversial. The present study is concerned with whether this procedure has a clinical use and which cofactors influence its therapeutic results.

METHODS

In this prospective, single institution, observational study, data from October 2010 to October 2013 from 61 nonunions in 60 patients treated with EXOGEN(®) LIPUS therapy were analysed. The average age was 45.4 ± 9.81 (18-63) years. Treatment was primarily done on long bones of the lower extremity (75.4 %). All 61 nonunions were examined after treatment, and the rate of healing as well as functional and subjective results were evaluated. Based on clinical and radiological findings, patients were divided into two groups: G1-successful treatment; and G2-unsuccessful treatment. Groups were compared to one another to identify possible factors influencing treatment.

RESULTS

Twenty (32.8 %) patients showed bone consolidation with an average time of healing of 5.3 (2-7) months. In patients without successful treatment, who underwent revision surgery instead, full weight bearing took on average 3.7 months longer, and they were able to return to work 6.8 months later. Most of the treated patients (70.5 %) reported no improvement in pain. In G2, 12 (29.3 %) patients suffered in their previous history from osteitis; in G1 there were only two patients (10 %) (p = 0.012). There were further significant differences in the age of the fracture, the type of osteosynthesis, the gap size, as well as the NUSS score.

CONCLUSION

Despite patients being chosen strictly according to EXOGEN(®) indications, only a small number of patients with nonunions who underwent LIPUS therapy experienced successful treatment (32.8 %). Overall, its use resulted in a clear delay in the time of treatment, so that according to our results, the use of LIPUS should be seen critically in long bone nonunions and use should be made on a case-by-case basis.

Treatment of atrophic tibia non-unions according to 'diamond concept': Results of one- and two-step treatment

BACKGROUND

The successful treatment of atrophic tibia non-unions and tibia non-unions with large bone defects or infections is a major challenge in orthopedic and trauma surgery. This article evaluates the use of the 'diamond concept' using a one-step or two-step procedure according to 'Masquelet technique' in the treatment of atrophic tibia non-unions.

METHODS

Between February 2010 and March 2014, 102 patients with atrophic non-unions were treated according to the 'diamond concept' in our center. Ninety-nine were available for follow-up. Forty-nine received a one-step treatment (Group 1, G1) and 50 patients received a two-step treatment according to the 'Masquelet technique' (Group 2, G2). Clinical and radiological parameters were measured preoperatively as well as 4, 6, and 12 weeks and 6 and 12 months postoperatively. In order to evaluate the subjective health of patients, we used the SF-12 questionnaire. Data analysis was performed one year after treatment.

RESULTS

The rate of consolidation in G1 was 84% and 80% in G2. The time to heal in G2 was 8.6 ± 2.9 months, which is significantly longer than in G1 being 6.9 ± 3.1 months. In comparison patients in G1/G2 had an average of 3.2/6.7 previous major surgeries. In G1, 4 of 8 patients who did not heal successfully showed positive intraoperative cultures. In G2, 26 patients (52%) initially presented with positive cultures. The results of the SF-12 questionnaire improved in both groups during the postoperative follow-up, but showed no significant differences between groups. In 29 patients a gentamycin-coated nail was used for reosteosynthesis. These patients showed by trend a lower rate of complications at a higher rate of consolidation.

CONCLUSIONS

Our study showed that the 'diamond concept' is a suitable method for safely and effectively treating non-unions with large defects or infections. The use of an antibiotic-coated nail provides a therapeutic benefit. For large bone defects of infected non-unions the two-step procedure after Masquelet is an efficient way to eradicate the infection and treat the bone defect successfully.

Reaming in treatment of non-unions in long bones: cytokine expression course as a tool for evaluation of non-union therapy

The analysis of peripheral serum cytokine expression patterns has been shown to be a possible method for demonstrating changes in bone metabolism. The aim of this study is to evaluate the effectiveness of this method within the treatment of long bone non-union with intramedullary reaming, a well-established non-union treatment concept.

MATERIALS AND METHODS

Three groups were added to this study: group one (G1) suffered from long bone non-unions, treated successfully with intramedullary reaming; group two (G2) consisted of long bone fractures with proper fracture healing; and group three (G3) included long bone fractures resulting in non-unions. We took blood samples on day 2, and after week 1, 4, 6, month 3 and 6 after initial treatment. Clinical and radiological follow-up were provided for 6 months. We measured transforming growth factor ß-1 (TGFß-1), platelet-derived growth factor (PDGF-AB), and insulin like growth factor-1 (IGF-1) at all-time points.

RESULTS

TGF-ß1 levels in G1 and G2 increased from day 2 to 6 weeks after surgery. In general, G1 and G2 showed parallel TGF-ß1 expression patterns, and G3 had a significant peak during first week compared to G1 (p = 0.023). PDGF peaked in G3 during first week after treatment, whereas G1 had its maximum after 4 weeks and G2 after 6 weeks. We were able to detect a significantly lower PDGF concentration at 3 months in G1 compared to G3 (p = 0.029). IGF-1 showed a peak concentration in G1 during the first 4 weeks. Afterwards, concentration levels in both G1 and G2 were higher.

CONCLUSIONS

Our study was able to show that the cytokine expression pattern in physiological bone healing is similar to that in successful non-union treatment with intramedullary reaming. Our results show that the effect of non-union therapy could be observed objectively by measuring cytokine expression patterns in peripheral blood even in a small group of patients.

[Use of osteoanabolics in fracture nonunion]

BACKGROUND

The treatment of fracture nonunion (pseudarthrosis) is often lengthy and debilitating for the patient. There are operative and conservative therapies available.

RESEARCH QUESTION

Does the systemic use of osteoanabolic acting substances (osteoanabolics) lead to an acceleration of the delayed fracture healing and/or strengthening of the fracture? Which types of pseudarthrosis are suitable for this treatment option?

MATERIALS AND METHODS

A literature review was carried out focusing on the systemic anabolic therapy options for the treatment of delayed healing of fractures or pseudarthrosis. Additionally, our own case studies are presented.

RESULTS

Teriparatide and strontium ranelate have a positive effect on the healing of fractures in animal studies and in humans. There are also case studies on the use of both substances in delayed fracture healing or pseudarthrosis. The scientific knowledge regarding teriparatide is significantly more comprehensive. However, prospective randomized trials are lacking so far.

CONCLUSION

The systemic use of anabolics can be a therapeutic option, especially for biological reactive pseudarthrosis. However, these are off-label treatments and contraindications should be especially well heeded. Because of the numerous positive results, from the point of view of teriparatide treatment, a multicentric, prospective randomized study on the treatment of aseptic pseudarthrosis should be initiated.

Bone Regeneration Using Bone Morphogenetic Proteins and Various Biomaterial Carriers

Trauma and disease frequently result in fractures or critical sized bone defects and their management at times necessitates bone grafting. The process of bone healing or regeneration involves intricate network of molecules including bone morphogenetic proteins (BMPs). BMPs belong to a larger superfamily of proteins and are very promising and intensively studied for in the enhancement of bone healing. More than 20 types of BMPs have been identified but only a subset of BMPs can induce de novo bone formation. Many research groups have shown that BMPs can induce differentiation of mesenchymal stem cells and stem cells into osteogenic cells which are capable of producing bone. This review introduces BMPs and discusses current advances in preclinical and clinical application of utilizing various biomaterial carriers for local delivery of BMPs to enhance bone regeneration.

Enhanced osteoinductivity of recombinant human bone morphogenetic protein-2 in combination with epidermal growth factor in a rabbit tibial defect model

This study aims to explore the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on bone formation when treated with epidermal growth factor (EGF) using human mesenchymal stem cells (hMSCs) and a rabbit tibial defect model. The rhBMP-2 (250 ng/ml)+EGF (10 ng/ml) group showed higher alkaline phosphatase (ALP) activity, ALP expression, increased calcium amount than rhBMP-2 group. In micro-CT and histology results of animal experiments, the rhBMP-2+EGF group showed more amount of bone bridging compared to the rhBMP-2 group. Among the 8-week groups, the rhBMP-2+EGF group showed significantly higher percent bone volume and trabecular number compared to the rhBMP-2 group. The combined treatment with EGF and rhBMP-2 induced significantly higher bone formation compared to that of rhBMP-2 only in both hMSCs and a rabbit tibial defect model. Therefore, EGF is expected to facilitate bone formation effect of rhBMP-2 when both factors are treated in combination.

Autograft versus BMPs for the treatment of non-unions: what is the evidence?

Autograft is considered the gold standard in non-union treatment. However, it is associated with significant morbidity and limited biological activity. The introduction of bone morphogenetic proteins (BMPs) has added a valuable tool to the surgeon's possibilities. The initial expectations of the effectiveness of BMPs were high, but over the years the union rate of BMPs was shown to be comparable with autograft. In this overview, both treatment modalities are compared. The off-label use of BMPs, the combination of BMPs and autograft, and the economic perspective of BMP use are summarized. In their current formulation, BMPs are an effective alternative for autograft in selected cases. The beneficial effect outweighs the economic costs. Widening of the indication to other long bone non-unions and new formulations are expected in the nearby future.