The role of low-grade infection in the pathogenesis of apparently aseptic tibial shaft nonunion

The value of current diagnostic techniques in the diagnosis of fracture-related infections: Serum markers, histology, and cultures

Although fracture-related infection (FRI) is a serious complication following bone fractures, a comprehensive definition and diagnostic criteria have only emerged in recent years. According to this consensus definition, the diagnosis of FRI is based on preoperative and intraoperative suggestive or confirmatory criteria. Serum markers, histology, and microbiological cultures are considered to play a crucial role in the FRI diagnostic pathway. However, at the time of publication of the FRI consensus definition in 2018 and its update in 2020, limited data was available on the accuracy of these diagnostic methods. This review aims to provide an overview of recent publications and discuss whether new evidence has been obtained regarding the value of these current diagnostic techniques. Meanwhile, several studies have confirmed the limited prognostic value of C-reactive protein, erythrocyte sedimentation ratio, and white blood cell count. Other serologic markers for preoperative diagnosis of FRI with promising diagnostic performance are d-dimer, plasma fibrinogen, platelet count to mean platelet volume ratio, and a risk prediction model that includes soft tissue injury type and fracture complexity in addition to blood markers. However, their true diagnostic value in daily clinical practice needs to be investigated in further studies. Data on histology in FRI diagnosis is still limited, but its potential as a confirmatory criterion seems to lie in its high specificity. Recent studies indicate that tissue culture exhibits moderate sensitivity and high specificity, with sensitivity improvements achieved by sampling of five specimens and long-term culture. Implant sonication also appears to enhance the sensitivity of culture and the detection rate of polymicrobial infections. In conclusion, the true value of diagnostic techniques is difficult to assess, in part because it is measured against a gold standard that is itself imperfect and still evolving, but also because of methodological differences in sample processing or the use of different thresholds. Nevertheless, this review has identified that the value of current diagnostic techniques is high when used in combination. To draw more accurate conclusions about the value of serum markers, histology, and culture including sonication, future studies should be prospective and utilize a greater standardization in sampling and methodological protocols.

Clinical management and innovation in fracture non-union

INTRODUCTION

With the introduction and continuous improvement in operative fracture fixation, even the most severe bone fractures can be treated with a high rate of successful healing. However, healing complications can occur and when healing fails over prolonged time, the outcome is termed a fracture non-union. Non-union is generally believed to develop due to inadequate fixation, underlying host-related factors, or infection. Despite the advancements in fracture fixation and infection management, there is still a clear need for earlier diagnosis, improved prediction of healing outcomes and innovation in the treatment of non-union.

AREAS COVERED

This review provides a detailed description of non-union from a clinical perspective, including the state of the art in diagnosis, treatment, and currently available biomaterials and orthobiologics.Subsequently, recent translational development from the biological, mechanical, and infection research fields are presented, including the latest in smart implants, osteoinductive materials, and in silico modeling.

EXPERT OPINION

The first challenge for future innovations is to refine and to identify new clinical factors for the proper definition, diagnosis, and treatment of non-union. However, integration of in vitro, in vivo, and in silico research will enable a comprehensive understanding of non-union causes and correlations, leading to the development of more effective treatments.

[Non-unions of the upper extremities]

The diagnosis and treatment of non-unions still represents an interdisciplinary challenge. Therefore, prevention, early detection and specific treatment are of great importance. Non-unions of the upper extremities, although less common than that of the lower extremities, requires special attention for successful treatment due to the central role of the shoulder girdle and arm in day to day activities. Successful treatment of non-unions requires a comprehensive evaluation of the patient's medical history, a thorough clinical examination and in particular radiological imaging. In order to effectively treat the pseudarthrosis it is crucial to distinguish between pseudarthroses that are suspected to be due to infections and those that are not. This article presents a treatment algorithm for managing both pseudarthrosis due to infection and pseudarthrosis without infection in the upper extremities.

Characteristics and Outcomes of Occult Infections in Presumed Aseptic Nonunions: A Retrospective Cohort Study

OBJECTIVES

To determine (1) the rate of positive cultures in presumed aseptic nonunions, (2) the rate and microbial spectrum of positive cultures that represented occult infection, and (3) rates of nonunion healing.

METHODS

DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS SELECTION CRITERIA

Adult patients with a presumed aseptic nonunion treated with single-stage revision between 2002 and 2022.

OUTCOME MEASURES AND COMPARISONS

The rate of positive cultures compared for 2 protocols: old: 1-2 samples cultured 7 days versus new: 5 samples cultured 14 days. The rate of positive cultures meeting occult infection criteria with the new protocol (≥2 samples with phenotypically indistinguishable microorganisms, or ≥1 sample with a high virulent microorganism). Nonunion healing rates between protocols and between groups based on culture results with the new protocol.

RESULTS

One hundred seventy-nine patients were included. The rate of positive cultures was 14% (n = 15/105) with the old protocol and 51% (n = 38/74) with the new protocol (P < 0.001). With the new protocol, the rate of positive cultures meeting occult infection criteria was 19% (n = 14/74), and coagulase-negative staphylococci (48%) and Cutibacterium acnes (38%) were the most common microorganisms. Nonunion healing rates after the primary revision did not differ between protocols (old: 82% vs. new: 86%, P = 0.41) and groups based on culture result (sterile: 86% vs. occultly infected: 93%, P = 0.66). The final overall nonunion healing rate was 97%.

CONCLUSIONS

Occult infections were identified in 1 in 5 presumed aseptic nonunions using a standardized protocol with 5 intraoperative samples cultured 14 days and were predominantly caused by slow growing, gram-positive microorganisms. The local spectrum and antimicrobial sensitivity of occult infections should be considered when developing empiric antimicrobial protocols. Patients with presumed aseptic nonunions can expect high healing rates, regardless of the culture result.

LEVEL OF EVIDENCE

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

Anti-Microbial Drug Metronidazole Promotes Fracture Healing: Enhancement in the Bone Regenerative Efficacy of the Drug by a Biodegradable Sustained-Release In Situ Gel Formulation

Nitroimidazoles comprise a class of broad-spectrum anti-microbial drugs with efficacy against parasites, mycobacteria, and anaerobic Gram-positive and Gram-negative bacteria. Among these drugs, metronidazole (MTZ) is commonly used with other antibiotics to prevent infection in open fractures. However, the effect of MTZ on bone remains understudied. In this paper, we evaluated six nitroimidazole drugs for their impact on osteoblast differentiation and identified MTZ as having the highest osteogenic effect. MTZ enhanced bone regeneration at the femur osteotomy site in osteopenic ovariectomized (OVX) rats at the human equivalent dose. Moreover, in OVX rats, MTZ significantly improved bone mass and strength and improved microarchitecture compared to the vehicle-treated rats, which was likely achieved by an osteogenic mechanism attributed to the stimulation of the Wnt pathway in osteoblasts. To mitigate the reported neurological and genotoxic effects of MTZ, we designed an injectable sustained-release in situ gel formulation of the drug that improved fracture healing efficacy by 3.5-fold compared to oral administration. This enhanced potency was achieved through a significant increase in the circulating half-life and bioavailability of MTZ. We conclude that MTZ exhibits osteogenic effects, further accentuated by our sustained-release delivery system, which holds promise for enhancing bone regeneration in open fractures.

Intraoperative calprotectin lateral flow immunoassay can assist decision-making between one- and two-stage revision total hip arthroplasty for patients with suspected periprosthetic joint infection

Aims

Accurate diagnosis of chronic periprosthetic joint infection (PJI) presents a significant challenge for hip surgeons. Preoperative diagnosis is not always easy to establish, making the intraoperative decision-making process crucial in deciding between one- and two-stage revision total hip arthroplasty (THA). Calprotectin is a promising point-of-care novel biomarker that has displayed high accuracy in detecting PJI. We aimed to evaluate the utility of intraoperative calprotectin lateral flow immunoassay (LFI) in THA patients with suspected chronic PJI.

Methods

The study included 48 THAs in 48 patients with a clinical suspicion of PJI, but who did not meet European Bone and Joint Infection Society (EBJIS) PJI criteria preoperatively, out of 105 patients undergoing revision THA at our institution for possible PJI between November 2020 and December 2022. Intraoperatively, synovial fluid calprotectin was measured with LFI. Cases with calprotectin levels ≥ 50 mg/l were considered infected and treated with two-stage revision THA; in negative cases, one-stage revision was performed. At least five tissue cultures were obtained; the implants removed were sent for sonication.

Results

Calprotectin was positive (≥ 50 mg/l) in 27 cases; out of these, 25 had positive tissue cultures and/or sonication. Calprotectin was negative in 21 cases. There was one false negative case, which had positive tissue cultures. Calprotectin showed an area under the curve of 0.917, sensitivity of 96.2%, specificity of 90.9%, positive predictive value of 92.6%, negative predictive value of 95.2%, positive likelihood ratio of 10.6, and negative likelihood ratio of 0.04. Overall, 45/48 patients were correctly diagnosed and treated by our algorithm, which included intraoperative calprotectin measurement. This yielded a 93.8% concordance with postoperatively assessed EBJIS criteria.

Conclusion

Calprotectin can be a valuable tool in facilitating the intraoperative decision-making process for cases in which chronic PJI is suspected and diagnosis cannot be established preoperatively.

What can they expect? Decreased quality of life and increased postoperative complication rate in patients with a fracture-related infection

BACKGROUND

By gaining insight into the Quality of Life (QoL) status and occurrence of complications, critical facets in the care for patients with Fracture-Related Infection (FRI) can be mitigated and measures can be taken to improve their outcome. Therefore, the aims of this study were to 1) determine the QoL in FRI patients in comparison to non-FRI patients and 2) describe the occurrence of other complications in both FRI and non-FRI patients.

METHODS

An ambidirectional cohort study was conducted in a level 1 trauma centre between January 1st 2016 and November 1st 2021. All patients who underwent surgical stabilisation of an isolated long bone fracture were eligible for inclusion. To avoid confounding, only patients with an Injury Severity Score (ISS) <16 were included. Data regarding patient demographics, fracture characteristics, treatment, follow-up and complications were collected of both non-FRI and FRI patients. QoL was assessed through the use of five-level EuroQol five-dimension (EQ-5D-5L) questionnaires twelve months post-injury.

RESULTS

A total of 134 patients were included in this study, of whom 38 (28%) FRI patients and 96 (72%) non-FRI patients. In comparison to non-FRI patients, FRI patients scored significantly worse on the QoL assessment regarding the index value (p = 0.012) and the domains mobility (p<0.001), usual activities (p = 0.010) and pain/discomfort (p = 0.009). Other postoperative complications were more often reported (p<0.001) in FRI patients (66%, n = 25/38) compared to non-FRI patients (27%, n = 26/96). During the median follow-up of 14.5 months (interquartile range (IQR) 9.5-26.5), 25 FRI patients developed a total of 49 distinctive complications besides FRI. The complications nonunion (18%, n = 9/49), infection other than FRI (e.g. line infection, urinary tract infection, pneumonia) (18%, n = 9/49) and implant failure (14%, n = 7/49) were the most frequently described in the FRI group.

CONCLUSION

Patients who suffered from an FRI have a decreased QoL in comparison to those without an FRI. Moreover, patients with an FRI have a higher rate of additional complications. These findings can help in patient counselling regarding the potential physical and mental consequences of having a complicated course of recovery due to an infection.

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.

Synergistic effects of autologous platelet-rich plasma combined with an extracorporeal shock wave in treatment of long diaphysis aseptic nonunion

INTRODUCTION

Union of long bone fractures is a complicated biological mechanism affected by numerous systemic and local variables. Disruption of any of these components may result in fracture nonunion. There are various types of clinically available treatment strategies for aseptic nonunion. Both activated platelet plasma and extracorporeal shock waves play important roles in fracture healing. This study aimed to investigate the interaction of platelet-rich plasma (PRP) and extracorporeal shock wave (ESW) in bone healing of nonunion.

HYPOTHESIS

PRP and ESW have synergistic effects in treating long bone nonunion.

METHODS

Between January 2016 and December 2021, a total of 60 patients with established nonunion of a long bone (18 tibias, 15 femurs, 9 humerus, 6 radii, and 12 ulnae) were included in this study, comprising 31 males and 29 females, ranging from 18 to 60 years old. Patients with bone nonunion were separated into two groups: PRP alone (Monotherapy group) and those treated with PRP combined with ESW (Combined treatment group). The two groups were compared to assess the therapeutic benefits, callus development, local problems, bone healing time, and Johner Wruhs functional classification of operated limbs.

RESULTS

Fifty-five patients were followed up, 5 patients were lost to follow-up, two in the PRP group and three in the PRP+ESW group, the follow-up time varied from 6 to 18 months, with an average of 12.7±5.2 months. At 8, 12, 16, 20, and 24 weeks following intervention, the callus score in the monotherapy group was significantly lower than in the combined treatment group (p<0.05). Both groups had no swelling and infection in the soft tissue of the nonunion operation site. In the PRP+ESW group, the fracture union rate was 92.59% and the healing time was 16.3±5.2 weeks. In the PRP group, the fracture union rate was 71.43% and the healing time was 21.5±3.7 weeks. The clinical healing time of the monotherapy group was significantly longer than the combined treatment group (p<0.05). All the nonunion patients with no signs of healing were treated with revision surgery. The excellent and good rate of Johner-Wruhs functional classification of affected limbs in the monotherapy group was significantly lower than in the combined treatment group (p<0.05).

CONCLUSION

PRP combined with ESW has a certain synergistic effect in treating aseptic nonunion after fracture surgery. It can significantly improve the formation of new bone, it is a minimally invasive and effective strategy to treat aseptic nonunion in a clinical setting.

LEVEL OF EVIDENCE

III, retrospective, single-centre, case-control study.

[Diagnostic and therapeutic work-up of infected tibial nonunion]

BACKGROUND

The failure of bone fracture healing is one of the major complications of fracture treatment, especially of the tibia due to its limited soft tissue coverage and high rate of open injuries. Although implant development is constantly progressing and modern surgical techniques are continuously improving, infected tibial nonunion plays a decisive role in terms of its variable clinical presentation.

OBJECTIVE

This article provides guidelines for the successful surgical treatment of infected tibial nonunion.

MATERIAL AND METHOD

Strategies are presented to identify infection as a cause of failure of fracture healing and to achieve infection and bone healing.

RESULTS

A significant amount of tibial nonunions primarily thought to be aseptic ultimately turn out to be infected nonunions.

CONCLUSION

The treatment of infected tibial nonunion requires extensive clinical, radiological and laboratory diagnostics as well as a profound biomechanical and biological understanding of the bone situation. This is the only way to achieve rapid osseous healing with as few revision interventions as possible.

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.

The value of sonication in the differential diagnosis of septic and aseptic femoral and tibial shaft nonunion in comparison to conventional tissue culture and histopathology: a prospective multicenter clinical study

BACKGROUND

Septic and aseptic nonunion require different therapeutic strategies. However, differential diagnosis is challenging, as low-grade infections and biofilm-bound bacteria often remain undetected. Therefore, the examination of biofilm on implants by sonication and the evaluation of its value for differentiating between femoral or tibial shaft septic and aseptic nonunion in comparison to tissue culture and histopathology was the focus of this study.

MATERIALS AND METHODS

Osteosynthesis material for sonication and tissue samples for long-term culture and histopathologic examination from 53 patients with aseptic nonunion, 42 with septic nonunion and 32 with regular healed fractures were obtained during surgery. Sonication fluid was concentrated by membrane filtration and colony-forming units (CFU) were quantified after aerobic and anaerobic incubation. CFU cut-off values for differentiating between septic and aseptic nonunion or regular healers were determined by receiver operating characteristic analysis. The performances of the different diagnostic methods were calculated using cross-tabulation.

RESULTS

The cut-off value for differentiating between septic and aseptic nonunion was ≥ 13.6 CFU/10 ml sonication fluid. With a sensitivity of 52% and a specificity of 93%, the diagnostic performance of membrane filtration was lower than that of tissue culture (69%, 96%) but higher than that of histopathology (14%, 87%). Considering two criteria for infection diagnosis, the sensitivity was similar for one tissue culture with the same pathogen in broth-cultured sonication fluid and two positive tissue cultures (55%). The combination of tissue culture and membrane-filtrated sonication fluid had a sensitivity of 50%, which increased up to 62% when using a lower CFU cut-off determined from regular healers. Furthermore, membrane filtration demonstrated a significantly higher polymicrobial detection rate compared to tissue culture and sonication fluid broth culture.

CONCLUSIONS

Our findings support a multimodal approach for the differential diagnosis of nonunion, with sonication demonstrating substantial usefulness.

LEVEL OF EVIDENCE

Level 2 Trial registration DRKS00014657 (date of registration: 2018/04/26).

[Plate-assisted bone segment transport for bone defects of the lower extremities : Possibilities and limitations of treatment]

Large bone defects of the lower extremities are challenging for both patients and the treating orthopedic surgeons. The treatment is determined by the size and location of the defect; however, patient-specific factors, such as the soft tissue situation and the presence of systemic comorbidities must be taken into consideration in the treatment strategy. Osteodistraction is an excellent technique especially for large bone defects exceeding 3 cm; however, it is time-consuming and required external fixation prior to the development of motorized distraction nails. This article describes the procedure for the treatment of large bone defects of the lower extremities, with its possibilities and limitations, using the novel plate-assisted bone segment transport (PABST) procedure.

Biomechanical analysis of recently released cephalomedullary nails for trochanteric femoral fracture fixation in a human cadaveric model

BACKGROUND

Recently, two novel concepts for intramedullary nailing of trochanteric fractures using a helical blade or interlocking dual screws have demonstrated advantages as compared to standard single-screw systems. However, these two concepts have not been subjected to a direct biomechanical comparison so far. The aims of this study were to investigate in a human cadaveric model with low bone quality (1) the biomechanical competence of nailing with the use of a helical blade versus interlocking screws, and (2) the effect of cement augmentation on the fixation strength of the helical blade.

METHODS

Twelve osteoporotic and osteopenic human cadaveric femoral pairs were assigned for pairwise implantation using either a short TFN-ADVANCED Proximal Femoral Nailing System (TFNA) with a helical blade head element or a short TRIGEN INTERTAN Intertrochanteric Antegrade Nail (InterTAN) with interlocking screws. Six osteoporotic femora, implanted with TFNA, were augmented with bone cement. Four groups were created: group 1 (TFNA) paired with group 2 (InterTAN), both consisting of osteopenic specimens, and group 3 (TFNA augmented) paired with group 4 (InterTAN), both consisting of osteoporotic specimens. An unstable trochanteric AO/OTA 31-A2.2 fracture was simulated and all specimens were tested until failure under progressively increasing cyclic loading.

RESULTS

Stiffness in group 3 was significantly higher versus group 4, p = 0.03. Varus (°) and femoral head rotation around the femoral neck axis (°) after 10,000 cycles were 1.9 ± 1.0/0.3 ± 0.2 in group 1, 2.2 ± 0.7/0.7 ± 0.4 in group 2, 1.5 ± 1.3/0.3 ± 0.2 in group 3 and 3.5 ± 2.8/0.9 ± 0.6 in group 4, being significantly different between groups 3 and 4, p = 0.04. Cycles to failure and failure load (N) at 5° varus or 10° femoral head rotation around the neck axis in groups 1-4 were 21,428 ± 6020/1571.4 ± 301.0, 20,611 ± 7453/1530.6 ± 372.7, 21,739 ± 4248/1587.0 ± 212.4 and 18,622 ± 6733/1431.1 ± 336.7, being significantly different between groups 3 and 4, p = 0.04.

CONCLUSIONS

Nailing of trochanteric femoral fractures with use of helical blades is comparable to interlocking dual screws fixation in femoral head fragments with low bone quality. Bone cement augmentation of helical blades provides significantly greater fixation strength compared to interlocking screws constructs.

Outcome and risk factors for recurrence of early onset fracture-related infections treated with debridement, antibiotics and implant retention: Results of a large retrospective multicentre cohort study

INTRODUCTION

Early Fracture-Related Infections (FRIs) are a common entity in hospitals treating trauma patients and are often treated with a Debridement, Antibiotics and Implant Retention (DAIR) procedure. Aims of this study were to 1) evaluate the recurrence rate after DAIR procedures for early onset FRI, 2) establish the number of surgical procedures to gain control of the initial infection and 3) identify independent predictors for recurrence in this cohort.

METHODS

A retrospective multicentre cohort study was conducted in two level 1 trauma centres. Consecutive patients who underwent a DAIR procedure between January 1st 2015 and July 1st 2020 for confirmed FRI with an onset of <6 weeks after the latest osseous operation were included. Recorded data included patient demographics, treatment characteristics and follow-up. Univariate and multivariate logistic regression analyses were performed to assess predictors for recurrent FRI.

RESULTS

A total of 141 patients with early FRI were included in this study with a median age of 54.0 years (interquartile range (IQR) 34.5-64.0). The recurrence rate of FRI was 13% (n = 19) at one year follow-up and 18% (n = 25) at 23.1 months (IQR 15.3-36.4) follow-up. Infection control was achieved in 94% (n = 127/135) of cases. In total, 73 patients (52%) underwent at least two surgical procedures to treat the ongoing initial episode of FRI, of whom 54 patients (74%) required two to three procedures and 17 patients (23%) four to five procedures. Predictors for recurrent FRI were use of an intramedullary nail during index operation (odds ratio (OR) 4.0 (95% confidence interval (CI) 1.1-13.8)), need for additional surgical procedures to treat ongoing infection during the treatment period following the first presentation of early FRI (OR 1.9 (95% CI 1.1-3.5)) and a decreased Injury Severity Score (ISS) (inverted OR 1.1 (95% CI 1.0-1.1)).

CONCLUSION

The recurrence rate after treatment of early onset FRI in patients treated with a DAIR procedure was 18% at 23.1 months follow-up. At least two surgical procedures to gain control of the initial infection were needed in 52% of patients. Independent predictors for recurrent FRI were the use of an intramedullary nail during index operation, need for additional surgical procedures and a decreased ISS.

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

Background

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

Methods

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

Results

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

Conclusion

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

Level of evidence

Therapeutic Level IV.

Comparison of outcomes and operative course between septic and aseptic nonunion in long bones

PURPOSE

The treatment of nonunion of long bones is difficult particularly in the presence of infection, which often involves staged surgical management. There is limited literature to compare the post operative course and outcomes of patients treated for septic versus aseptic nonunion. Thus, the purpose of this study was to determine if a difference exists between the number of surgical procedures, time to union, and rate of successful union for these two groups.

METHODS

A retrospective cohort study was performed at a single tertiary care center. Patients suffering nonunion of the humerus, tibia and femur were included. Patient demographic data and characteristics of the post operative course were collected to include number and reason for repeat operations, antibiotic course, time to union, and development of a successful union.

RESULTS

About 28 of 122 patients had septic nonunion. After diagnosis of nonunion, the septic group averaged 3.9 surgeries compared to 1.5 in the aseptic group (p < 0.001). There was no difference in the rate of successful union (79.8% versus 85.7%; p = 0.220), though the septic group took 129 days longer on average for successful union. (376 versus 247; p = 0.018).

CONCLUSION

Septic nonunion of long bones is associated with the need for significantly more operations as well as time to union, though union rates remain similar. The identification of infection is critical for both the appropriate treatment as well as counseling patients on the expected post operative course.

[Infected nonunion: diagnostic and therapeutic work-up]

BACKGROUND

Septic nonunion is one of the major complications in fracture healing. The challenge is to identify the infection as the cause of nonunion first and then to achieve healing of the infection and the bone.

OBJECTIVE

Because of the more heterogeneous appearance of an infected nonunion, the prevalence of germ detection in surgical nonunion revision is often underestimated.

MATERIAL AND METHODS

In a retrospective study between 2010 and 2017, 86 patients with radiologically confirmed femoral shaft nonunion without clinical evidence and unremarkable medical history of a florid infection as the cause of nonunion, who had undergone primary single-stage surgical nonunion revision were analyzed. At least four intraoperatively obtained samples were evaluated for microbiological diagnosis. A distinction was made between tissue samples with subsequent 48‑h short-term incubation and tissue samples with 14-day long-term cultivation. The finding "germ detection" was made if at least two of the samples demonstrated bacterial growth.

RESULTS

In 18 of 86 patients with a nonunion preoperatively judged to be aseptic, positive bacterial evidence was obtained after short-term incubation. After long-term cultivation, positive bacterial detection was possible in 38 of 86 patients with a femoral shaft nonunion initially classified as aseptic. Regarding potential risk factors, the two groups demonstrated no relevant differences. In 29 patients, 1 pathogen was isolated from the obtained samples, whereas in the remaining 9 patients, a mixed culture with an average of 2.9 ± 0.5 different bacteria was detected. Identification revealed mainly low-virulence bacteria, most commonly Staphylococcus epidermidis.

CONCLUSION

If the preoperative diagnostics including clinical, laboratory and radiological examination as well as a careful anamnesis reveal indications of a possible infectious event, the surgical nonunion revision should be performed in two stages with specimen collection before definitive nonunion revision. For microbiological diagnosis, several representative tissue samples should independently be obtained from the nonunion site and incubated for 14 days. Only in the absence of evidence of septic nonunion is a single-stage procedure suggested.

Concepts and clinical aspects of active implants for the treatment of bone fractures

Nonunion is a complication of long bone fractures that leads to disability, morbidity and high costs. Early detection is difficult and treatment through external stimulation and revision surgery is often a lengthy process. Therefore, alternative diagnostic and therapeutic options are currently being explored, including the use of external and internal sensors. Apart from monitoring fracture stiffness and displacement directly at the fracture site, it would be desirable if an implant could also vary its stiffness and apply an intervention to promote healing, if needed. This could be achieved either by a predetermined protocol, by remote control, or even by processing data and triggering the intervention itself (self-regulated 'intelligent' or 'smart' implant). So-called active or smart materials like shape memory alloys (SMA) have opened up opportunities to build active implants. For example, implants could stimulate fracture healing by active shortening and lengthening via SMA actuator wires; by emitting pulses, waves, or electromagnetic fields. However, it remains undefined which modes of application, forces, frequencies, force directions, time durations and periods, or other stimuli such implants should ideally deliver for the best result. The present paper reviews the literature on active implants and interventions for nonunion, discusses possible mechanisms of active implants and points out where further research and development are needed to build an active implant that applies the most ideal intervention. STATEMENT OF SIGNIFICANCE: Early detection of delays during fracture healing and timely intervention are difficult due to limitations of the current diagnostic strategies. New diagnostic options are under evaluation, including the use of external and internal sensors. In addition, it would be desirable if an implant could actively facilitate healing ('Intelligent' or 'smart' implant). Implants could stimulate fracture healing via active shortening and lengthening; by emitting pulses, waves, or electromagnetic fields. No such implants exist to date, but new composite materials and alloys have opened up opportunities to build such active implants, and several groups across the globe are currently working on their development. The present paper is the first review on this topic to date.

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.

Validation of the diagnostic criteria of the consensus definition of fracture-related infection

BACKGROUND

The recently developed fracture-related infection (FRI) consensus definition, which is based on specific diagnostic criteria, has not been fully validated in clinical studies. We aimed to determine the diagnostic performance of the criteria of the FRI consensus definition and evaluated the effect of the combination of certain suggestive and confirmatory criteria on the diagnostic performance.

METHODS

A multicenter, multi-national, retrospective cohort study was performed. Patients were subdivided into an FRI or a control group, according to the treatment they received and the recommendations from a multidisciplinary team ('intention to treat'). Exclusion criteria were patients with an FRI diagnosed outside the study period, patients younger than 18 years of age, patients with pathological fractures or patients with fractures of the skull, cervical, thoracic and lumbar spine. Minimum follow up for all patients was 18 months.

RESULTS

Overall, 637 patients underwent revision surgery for suspicion of FRI. Of these, 480 patients were diagnosed with FRI, treated accordingly, and included in the FRI group. The other 157 patients were included in the control group. The presence of at least one confirmatory sign was associated with a sensitivity of 97.5%, a specificity of 100% and a high discriminatory value (AUROC 0.99, p < 0.001). The presence of a clinical confirmatory criterion or, if not present, at least one positive culture was associated with the highest diagnostic performance (sensitivity: 98.6%, specificity: 100%, AUROC: 0.99 (p < 0.001)). In the subgroup of patients without clinical confirmatory signs at presentation, specificities of at least 95% were found for the clinical suggestive signs of fever, wound drainage, local warmth and redness.

CONCLUSIONS

The presence of at least one confirmatory criterion identifies the vast majority of patients with an FRI and was associated with an excellent diagnostic discriminatory value. Therefore, our study validates the confirmatory criteria of the FRI consensus definition. Infection is highly likely in case of the presence of a single positive culture with a virulent pathogen. When certain clinical suggestive signs (e.g., wound drainage) are observed (individually or in combination and even without a confirmatory criterion), it is more likely than not, that an infection is present.

[Fracture-related infections after intramedullary nailing : Diagnostics and treatment]

Intramedullary nailing is the treatment of choice for a large number of fractures requiring surgery. In cases of fracture-related infections (FRI) the treatment of nail infections requires special attention due to the closed situation of the osteosynthesis material in the intramedullary canal. This article gives an overview of the general principles and diagnostic criteria for FRI after nail fixation and discusses the treatment recommendations based on three case examples. In cases of acute implant infections, an implant-retaining procedure is principally possible for both periprosthetic joint infections and FRI; however, after intramedullary nailing the nail should also be exchanged in cases of acute nail infections as a sufficient debridement of the nail is impossible due to its intramedullary location. In chronic FRI after intramedullary nailing a one-stage or two-stage procedure can be followed. In cases of adequate soft tissue coverage, good fracture reduction and an expected bone healing without critical bony substance defects, a one-stage procedure with nail exchange should be preferred. If a chronic infection with soft tissue and bone defects develops after intramedullary nailing, a two-stage procedure analogous to the treatment of osteomyelitis should be considered. In this case a multidisciplinary team approach with specialists in plastic surgery, microbiology and infectious diseases is necessary. The use of local antibiotics and antimicrobial-coated implants is deemed to be advantageous.