Fracture non-union: Can biomarkers predict outcome?

The Masquelet technique of induced membrane for healing of bone defects. A review of 8 cases

BACKGROUND

Segmental defects of long bones are notoriously difficult to treat. This study evaluates eight cases in which the Masquelet technique of induced membranes was used. The primary purpose was to assess the results compared to other types of bone reconstruction and share our tips and tricks to improve the outcome.

METHOD

Retrospective study based on patient records and radiographs. Eight patients operated between 2011 and 2014 were included. Three had infected non-unions. Outcome measures were time-to full weight-bearing, time to radiographic consolidation, need for secondary bone grafting procedures and occurrence of complications.

RESULTS

Time to full weight bearing seemed shorter in patients treated with nails. In two cases only partial radiographic consolidation was noted at the latest follow up visit. One patient needed secondary bone grafting and two limbs were malaligned. There were no amputations, no persistent infections, and no implant failures.

DISCUSSION

The induced membrane technique is a useful tool to substitute bone loss yet consolidation time is somewhat unpredictable and prolonged non-weight bearing is required.

CONCLUSION

Nailing seems to improve outcome compared to plating. It shortens treatment time, reduces the amount of bone graft needed, aligns the bone and should be considered when feasible. Further larger scale studies are welcome to throw more light into the efficacy and effectiveness of this technique.

Unexpected tibial non-union after minimally invasive bridge plating: a case report

A fit 42-year-old woman presented to our department with a closed isolated distal tibial and fibular shaft fracture (AO 42-B1.3), which was addressed with a minimally invasive plate osteosynthesis (MIPO) with a bridging technique for both the tibia and the fibula. No risk factors for healing issues were known at the time of surgery. At the 6-month follow-up, the leg was still painful during walking and the fracture site was still evident on the radiographs. Bone and CT-scans confirmed the diagnosis of oligotrophic non-union. A revision surgery was then successfully performed with a reamed IM tibial nail and a fibular osteotomy taking into consideration both biological and mechanical factors. Surgeons must treat tibial shaft fractures avoiding unnecessary damage to soft tissue, restoring an appropriate reduction of the bony segment and providing an adequate fixation; however, other factors may play a role in the development of "unexpected non-union".

Long bone non-unions treated with the diamond concept: a case series of 64 patients

The aim of this retrospective study with prospectively documented data was to report the clinical results of treatment of long bone non-unions using the "diamond concept". Over a 4-year period, patients that presented with a long bone non-union and were managed with the diamond conceptual framework of bone repair were evaluated. Exclusion criteria were hypertrophic, pathological, and infected non-unions. Fixation was revised as it was indicated whilst biological enhancement included the implantation of RIA graft, BMP-7 and concentrated bone marrow aspirate. Data recorded included patient demographics, initial fracture pattern and type of stabilisation, number of previous interventions, time to reoperation, time to union and functional outcome. Painless full weight bearing defined clinical union. Radiological union was defined as the presence of mature callous bridging to at least 3 bone cortices. The minimum follow up was 12 months (range 12-32). In total 64 patients (34 males) with a mean age of 45 years (17-83) were evaluated. Anatomical distribution of non-unions included the femur (54.68%), tibia (34.38%), humerus (4.68%), radius (3.13%) and clavicle (3.13%). The median number of previous interventions was 1 (range 1-5). The majority of patients (82.62%) underwent revision of fixation whereas only bone grafting was performed 9.38% of patients. Three patients developed superficial wound infection (one was MRSA), 1 had deep vein thrombosis and 1 developed heterotopic bone formation. Union was successful in 63/64 (98.4%) non-unions at a mean time of 6 months (range 3-12). All patients were mobilising pain free and returned to their daily living activities at the final follow up. The application of the "diamond concept" in this cohort of patients was associated with a high union rate by providing an optimal mechanical and biological environment. Such an approach should be considered in the surgeon's armamentarium particularly in such cases where difficulty of bone repair is foreseen.

Clinical effectiveness of Osigraft in long-bones non-unions

Current evidence, based primarily on case series, suggest that the eptotermin alfa (recombinant bone morphogenetic protein-7 (rhBM-7)), which is commercialized as Osigraft with an indication for tibial non-union, used in monotherapy or polytherapy, is a safe and effective therapy for long bones non-unions of lower and upper limbs. No previous study has compared the safety and the efficacy of Osigraft and the "gold standard" treatment for recalcitrant long-bones non-union, autologous bone graft (ABG). This study aims to compare the effectiveness of Osigraft and ABG in the treatment of post-traumatic, persistent long bone non-unions. In particular, the present study will focus exclusively on complex persistent non-unions, excluding simpler cases, in which it is likely that a simple revision of the osteosynthesis will be sufficient to promote union, and extremely severe cases in which there is an indication for amputation and prosthesis. The study addresses the following research question: 1. Is the effectiveness of eptotermin alfa comparable to that of ABG in the treatment of complex long bone non-unions? 2. Are there significant differences in the prevalence of adverse events between patients treated with eptotermin alfa and those treated with ABG? The study is an observational, retrospective study, located in one Experimental Recruiting Center (Ospedale Universitario G. PINI - Milano). The study was conducted with ethics approval and according with the existing Italian law. Demographic and clinical data were collected from patients Clinical Medical Records and other existing documentation, through a web based eCRF. The treatment (surgery with Osigraft or ABG) effectiveness was evaluated comparing the number of success cases (primary endpoint) and the length for clinical and radiological healing (secondary end-points). The treatment safety was evaluating comparing the prevalence of Adverse Events. Osigraft was demonstrated to be statistically equivalent to ABG with respect to the primary and secondary end point of surgical success. The treatment success was statistically comparable across all the anatomical regions considered, both in patients treated with Osigraft and in patients treated with ABG. The use of Osigraft when compared to autograft was associated with statistically lower intraoperative blood loss and shorter operative times. In addition patients treated with Osigraft developed statistically less peri-operative and late onset adverse events, compared to ABG. The difference was substantially due to the occurrence of pain at donor site in patients treated with ABG.

Fracture healing redefined

It is well established that local mechanical conditions and interfragmentary movement are important factors for successful bone healing and may vary dramatically with patient fracture-load and activity. Up until now however it was technically impossible to use these key influence parameters in the aftercare treatment process of human lower extremity fractures. We propose a theory that with state of the art sensor technology these biomechanical influences can not only be monitored in vivo, but also used for individualized therapy protocols. Local measurement systems for fracture healing are available but remain research tools, due to various technical issues. To investigate the biomechanical influences on healing right away surrogate sensor tools are needed. Various gait characteristics have been proposed as surrogate measures. Currently available sensor tools could be modified with the appropriate support structure to allow such measurements continuously over the course of a fracture healing. Interdisciplinary work between clinicians, software engineers with computer and biomechanical simulations is needed. Through such a sensor system human boundary conditions for fracture healing could not only be defined for the first time, but also used for a unique, extendible aftercare system. With this tool critical healing situations would be detected much earlier and could be prevented with easy activity modifications, reducing patient and socioeconomic burden of disease. The hypothesis, necessary tools and support structures are presented.

Longitudinal analysis of osteogenic and angiogenic signaling factors in healing models mimicking atrophic and hypertrophic non-unions in rats

Impaired bone healing can have devastating consequences for the patient. Clinically relevant animal models are necessary to understand the pathology of impaired bone healing. In this study, two impaired healing models, a hypertrophic and an atrophic non-union, were compared to physiological bone healing in rats. The aim was to provide detailed information about differences in gene expression, vascularization and histology during the healing process. The change from a closed fracture (healing control group) to an open osteotomy (hypertrophy group) led to prolonged healing with reduced mineralized bridging after 42 days. RT-PCR data revealed higher gene expression of most tested osteogenic and angiogenic factors in the hypertrophy group at day 14. After 42 days a significant reduction of gene expression was seen for Bmp4 and Bambi in this group. The inhibition of angiogenesis by Fumagillin (atrophy group) decreased the formation of new blood vessels and led to a non-healing situation with diminished chondrogenesis. RT-PCR results showed an attempt towards overcoming the early perturbance by significant up regulation of the angiogenic regulators Vegfa, Angiopoietin 2 and Fgf1 at day 7 and a further continuous increase of Fgf1, -2 and Angiopoietin 2 over time. However µCT angiograms showed incomplete recovery after 42 days. Furthermore, lower expression values were detected for the Bmps at day 14 and 21. The Bmp antagonists Dan and Twsg1 tended to be higher expressed in the atrophy group at day 42. In conclusion, the investigated animal models are suitable models to mimic human fracture healing complications and can be used for longitudinal studies. Analyzing osteogenic and angiogenic signaling patterns, clear changes in expression were identified between these three healing models, revealing the importance of a coordinated interplay of different factors to allow successful bone healing.

The role of pleiotrophin in bone repair

Bone has an enormous capacity for growth, regeneration, and remodelling, largely due to induction of osteoblasts that are recruited to the site of bone formation. Although the pathways involved have not been fully elucidated, it is well accepted that the immediate environment of the cells is likely to play a role via cell–matrix interactions, mediated by several growth factors. Formation of new blood vessels is also significant and interdependent to bone formation, suggesting that enhancement of angiogenesis could be beneficial during the process of bone repair. Pleiotrophin (PTN), also called osteoblast-specific factor 1, is a heparin-binding angiogenic growth factor, with a well-defined and significant role in both physiological and pathological angiogenesis. In this review we summarise the existing evidence on the role of PTN in bone repair.

Current Options for Determining Fracture Union

Determining whether a bone fracture is healed is one of the most important and fundamental clinical determinations made in orthopaedics. However, there are currently no standardized methods of assessing fracture union, which in turn has created significant disagreement among orthopaedic surgeons in both clinical and research settings. An extensive amount of research has been dedicated to finding novel and reliable ways of determining healing with some promising results. Recent advancements in imaging techniques and introduction of new radiographic scores have helped decrease the amount of disagreement on this topic among physicians. The knowledge gained from biomechanical studies of bone healing has helped us refine our tools and create more efficient and practical research instruments. Additionally, a deeper understanding of the molecular pathways involved in the bone healing process has led to emergence of serologic markers as possible candidates in assessment of fracture union. In addition to our current physician centered methods, patient-centered approaches assessing quality of life and function are gaining popularity in assessment of fracture union. Despite these advances, assessment of union remains an imperfect practice in the clinical setting. Therefore, clinicians need to draw on multiple modalities that directly and indirectly measure or correlate with bone healing when counseling patients.

Can we enhance fracture vascularity: What is the evidence?

Angiogenesis is a vital component of bone healing. The formation of the new blood vessels at the fracture site restores the hypoxia and nutrient deprivation found at the early stages after fracture whilst at a later stage facilitates osteogenesis by the activity of the osteoprogenitor cells. Emerging evidence suggests that there are certain molecules and gene therapies that could promote new blood vessel formation and as a consequence enhance the local bone healing response. This article summarizes the current in vivo evidence on therapeutic approaches aiming at the augmentation of the angiogenic signalling during bone repair.

Patient-important outcome for the assessment of fracture repair

Current evidence indicates that fracture healing assessment is limited to the use of one or two domains (such as pain, range of motion or mobility) in any single study. Functional outcome measures, which include physician-rated or observer-based impairment ratings and patient self-reported or observer-based activity limitation measures, better position the effectiveness of a given intervention towards patient-important outcomes. Health status measures, for example, cover a wide-range of physical, emotional, and social health dimensions. In this paper, we will examine the utility of metrics to assess fracture healing that are important to both the patient and provider, with selected examples from the recent literature. We recommend outcome measures with established and verified reliability and validity. Policy-makers and other stakeholders need to have an accurate assessment of treatment outcome that includes changes in function over time-adequate measures, should be re-applied at periodic intervals.

Biological perspectives of delayed fracture healing

Fracture healing is a complex biological process that requires interaction among a series of different cell types. Maintaining the appropriate temporal progression and spatial pattern is essential to achieve robust healing. We can temporally assess the biological phases via gene expression, protein analysis, histologically, or non-invasively using biomarkers as well as imaging techniques. However, determining what leads to normal versus abnormal healing is more challenging. Since the ultimate outcome of fracture healing is to restore the original functions of bone, assessment of fracture healing should include not only monitoring the restoration of structure and mechanical function, but also an evaluation of the restoration of normal bone biology. Currently few non-invasive measures of biological factors of healing exist; however, recent studies that have correlated non-invasive measures with fracture healing outcome in humans have shown that serum TGFbeta1 levels appear to be an indicator of healing versus non-healing. In the future, developing additional measures to assess biological healing will improve the reliability and permit us to assess stages of fracture healing. Additionally, new functional imaging technologies could prove useful for better understanding both normal fracture healing and predicting dysfunctional healing in human patients.

Delayed union and nonunions: epidemiology, clinical issues, and financial aspects

Fracture healing is a critically important clinical event for fracture patients and for clinicians who take care of them. The clinical evaluation of fracture healing is based on both radiographic findings and clinical findings. Risk factors for delayed union and nonunion include patient dependent factors such as advanced age, medical comorbidities, smoking, non-steroidal anti-inflammatory use, various genetic disorders, metabolic disease and nutritional deficiency. Patient independent factors include fracture pattern, location, and displacement, severity of soft tissue injury, degree of bone loss, quality of surgical treatment and presence of infection. Established nonunions can be characterised in terms of biologic capacity, deformity, presence or absence of infection, and host status. Hypertrophic, oligotrophic and atrophic radiographic appearances allow the clinician to make inferences about the degree of fracture stability and the biologic viability of the fracture fragments while developing a treatment plan. Non-unions are difficult to treat and have a high financial impact. Indirect costs, such as productivity losses, are the key driver for the overall costs in fracture and non-union patients. Therefore, all strategies that help to reduce healing time with faster resumption of work and activities not only improve medical outcome for the patient, they also help reduce the financial burden in fracture and non-union patients.