Management and outcome of diaphyseal aseptic non-unions of the lower limb: A systematic review

A systematic scoping review of the latest data on orthobiologics in the surgical treatment of non-union

INTRODUCTION

Recent studies have shown a growing concern regarding the cost-effectiveness and the lack of supporting data for the biologic agents that are being increasingly used in the orthopedic field. Our aim was to conduct a systematic scoping review of recent publications (last five years) on the use of orthobiologics to treat fracture non-union and summarize the latest available data.

PATIENTS AND METHODS

The inclusion criteria for this review were articles published in English, from 2016 to 2022, and focusing on the use of orthobiologics for the surgical treatment of non-union. Searches were conducted in March 2023 using Pubmed/MEDLINE and Embase. Studies on spinal fusion or gene therapy were excluded. Reviews, case reports with five cases or less, conference proceedings, preliminary reports, pediatric or non-human studies were excluded as well.

RESULTS

The search found 1807 articles, 15 were eligible after PRISMA checklist and exclusions. The evidence was heterogenous and there was only one level II RCT. Recent data suggests that bone morphogenic protein (BMP-2) products could be effective for septic and aseptic tibial non-unions. However, the evidence was not conclusive regarding BMP-7, plasma rich platelets (PRP), stem cells or demineralized bone matrix (DBM).

DISCUSSION

Every non-union case is different in terms of bone defect, biology, mechanical stability, surgical technique and host factors, which contributes to the conflicting reports on the efficacy of orthobiologics in the literature. We might never see a level 1, high powered and robust study defining the efficacy, safety profile and cost-effectiveness of such products.

LEVEL OF EVIDENCE

IV.

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

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

Femoral non-union above a fused knee: Successful treatment with exchange nailing and intramedullary delivery of bone morphogenetic protein

Bone healing is a complex and well-orchestrated physiological process, in which bone repairs and regenerates regaining its original biomechanical and biochemical properties. It is estimated that 5 to 10% of all fractures are complicated by delayed union or non-union. Progression to non-union is thought to be multifactorial, even though the exact biological sequence remains obscure. Treatment should aim to addressing deficiencies in both the mechanical and biological components, along with eliminating co-factors that could negatively affect the locally induced fracture healing response. We report a case of a 78-year-old patient who presented with a distal femoral non-union above a previously fused knee, which was successfully managed with exchange nailing and intramedullary delivery of recombinant human bone morphogenetic protein-7 (rhBMP-7).

Treatment of a femoral septic nonunion in a dog with interlocking nail stabilization associated to corticospongious bone autograft and greater omentum flap: case report

ABSTRACT Chronic septic bone nonunion requires a well-designed therapeutic planning, demanding a multimodal treatment to achieve bone consolidation and elimination of infection. A successful case of an association of the major omentum flap with surgical stabilization with an interlocking nail for treatment of a femoral septic nonunion in dog is reported. The patient had partial functional return of the limb 30 days after surgery, negative bacterial culture with radiographic signs of bone healing and total functional return of the limb at 90th days after the surgical procedure.

Treatment of atrophic nonunion via autogenous ilium grafting assisted by vertical fixation of double plates: A case series of patients

OBJECTIVE

To investigate the efficacy of the treatment of atrophic nonunion using structural autogenous ilium bone grafting in combination with vertical fixation of double plates.

METHODS

This retrospective study analysed the clinical data from consecutive patients with atrophic nonunion who underwent autogenous ilium grafting in combination with double-plate vertical fixation. The injury type and the bone affected by nonunion, the duration of nonunion and the outcomes following surgery were recorded for all patients.

RESULTS

The study enrolled 43 patients with atrophic nonunion of the upper and lower limbs: 17 patients with tibial nonunion, 21 with femoral nonunion, four with humeral nonunion and one with radial shaft nonunion. The mean duration of postoperative follow-up was 14.5 months (range, 8-28 months). A total of 43 of 43 patients (100%) achieved a healed nonunion fracture without the occurrence of complications such as infection, fracture of internal fixation or pain in the harvesting site. Comprehensive postoperative assessments of bone healing and function were observed to be good and/or excellent in all 43 patients.

CONCLUSION

Structural autogenous ilium grafting used in combination with double-plate vertical fixation can provide a stable structural environment for near optimal bone healing in patients with atrophic nonunion.

The Effect of Smoking on Posttraumatic Pseudoarthrosis Healing after Internal Stabilization, Treated with Platelet Rich Plasma (PRP)

Disturbed or delayed healing remains one of the most serious fracture-related complications, despite bone capacity for internal regeneration and reabsorption. Considerable progress in the understanding and treatment of fractures has been noted. The aim of our study was to evaluate treatment outcome in patients (smokers and non-smokers) with post-traumatic pseudoarthrosis.

Hypothesis

Determinate when administration of growth factors is most beneficial, and whether it accelerates bone union.

Material and methods

The study included patients treated for post-traumatic pseudoarthrosis resulting from multiple bone fractures. The study group and controls were further subdivided into: non-smokers, non-smokers >2 years after quitting, and smokers. Independent tests were performed for men and women. The study group, apart from other methods of treatment, received concentrated PRP (platelet-rich plasma) to aid the process of bone healing, or in cases of delayed healing confirmed by radiological assessment on follow-up visits.

Results

Mean time of fracture healing was 8 weeks for non-smokers and non-smokers >2 years after quitting, whereas in smokers the healing process was significantly prolonged (18 weeks in both, men and women).

Conclusions

The risk for infection is smaller in non-smokers as compared to smokers, with the latter being at an elevated risk for bone inflammation and delayed union.

Diaphyseal long bone nonunions - types, aetiology, economics, and treatment recommendations

The intention of the current article is to review the epidemiology with related socioeconomic costs, pathophysiology, and treatment options for diaphyseal long bone delayed unions and nonunions. Diaphyseal nonunions in the tibia and in the femur are estimated to occur 4.6-8% after modern intramedullary nailing of closed fractures with an even much higher risk in open fractures. There is a high socioeconomic burden for long bone nonunions mainly driven by indirect costs, such as productivity losses due to long treatment duration. The classic classification of Weber and Cech of the 1970s is based on the underlying biological aspect of the nonunion differentiating between "vital" (hypertrophic) and "avital" (hypo-/atrophic) nonunions, and can still be considered to represent the basis for basic evaluation of nonunions. The "diamond concept" units biomechanical and biological aspects and provides the pre-requisites for successful bone healing in nonunions. For humeral diaphyseal shaft nonunions, excellent results for augmentation plating were reported. In atrophic humeral shaft nonunions, compression plating with stimulation of bone healing by bone grafting or BMPs seem to be the best option. For femoral and tibial diaphyseal shaft fractures, dynamization of the nail is an atraumatic, effective, and cheap surgical possibility to achieve bony consolidation, particularly in delayed nonunions before 24 weeks after initial surgery. In established hypertrophic nonunions in the tibia and femur, biomechanical stability should be addressed by augmentation plating or exchange nailing. Hypotrophic or atrophic nonunions require additional biological stimulation of bone healing for augmentation plating.

[The relevant axial deviation: Diagnostics and therapy for correction osteotomies of the femur]

Intraoperative assessment of the femoral axis, length and torsion can be difficult. A postoperative torsional discrepancy is a common but rarely diagnosed condition. A clinical evaluation of femoral torsion is limited, especially in the early postoperative period. Conventional radiographs are a reliable diagnostic tool for evaluation of discrepancies of leg length and axis. Computed tomography remains the gold standard for assessment of torsional discrepancies. Because of the wide variability of the physiological femoral torsion, the clinical impact of a torsional discrepancy in individual cases remains unclear. There is a general recommendation for revision in cases of intraindividual deviations of more than 15°; however, most patients with deviations even greater than 15° are asymptomatic. Therefore, the indications for correction should be carefully considered in each individual case. The patient level of activity is a crucial point in decision-making for correction osteotomy. Before correction osteotomy, the surgeon has to make a detailed biomechanical analysis of the leg. Early correction is recommended in most cases. Detailed knowledge of the patient medical history is needed for preoperative planning. Prior surgeries can have a significant impact on the choice of the surgical approach and stabilization technique.

Biological methods to enhance bone healing and fracture repair

This article looks into normal physiological fracture healing with special emphasis on the diamond concept. A precise definition of nonunion of long bones is described. Most often inadequate fixation (too rigid or too loose) is the reason for nonunion in long bone fractures. Because a critical bone defect cannot be bridged, it may lead directly or indirectly (lack of fixation) to nonunion. Individual inadequate local biological characteristics are also often found to be the cause; poor soft tissue coverage as well as a lack of periosteum and muscle or fascia or skin defects can lead to compromised vascularity in situ. Systemic factors are now much more recognized, e.g., smoking, diabetes, and cachexia, as well as the limited impact of some medications, e.g., nonsteroidal anti-inflammatory drugs and steroids. Today's mode of treatment for nonunion is approached in this article, and suggestions for appropriate treatment of long bone nonunion is presented.

Biological and molecular profile of fracture non-union tissue: current insights

Delayed bone healing and non-union occur in approximately 10% of long bone fractures. Despite intense investigations and progress in understanding the processes governing bone healing, the specific pathophysiological characteristics of the local microenvironment leading to non-union remain obscure. The clinical findings and radiographic features remain the two important landmarks of diagnosing non-unions and even when the diagnosis is established there is debate on the ideal timing and mode of intervention. In an attempt to understand better the pathophysiological processes involved in the development of fracture non-union, a number of studies have endeavoured to investigate the biological profile of tissue obtained from the non-union site and analyse any differences or similarities of tissue obtained from different types of non-unions. In the herein study, we present the existing evidence of the biological and molecular profile of fracture non-union tissue.

Long-term functional outcome and quality of life after successful surgical treatment of tibial nonunions

PURPOSE

Our aim was to evaluate quality of life (QoL) and functional outcome of patients with tibial nonunions after completion of surgical treatment with an average follow-up of five years.

METHODS

The following data of 64 patients were retrospectively evaluated: fracture type, type and duration of surgical therapy, range of motion of the knee and ankle and American Orthopaedic Foot and Ankle Society (AOFAS) score. QoL was evaluated with the Short-Form Health Survey (SF-36) questionnaire; pain intensity, patient satisfaction and impairments of daily, professional and sport activities with a ten point visual analogue scale.

RESULTS

QoL, even in cases with successfully completed treatment, was significantly reduced compared with the normal general population. Pain intensity and limited ankle dorsal extension, despite the absence of intra-articular fractures, were significantly correlated with inferior QoL.

CONCLUSIONS

This study emphasises the long-term negative impact of tibial nonunions on patient QoL, even after successful surgical treatment.