Analyzing risk factors for treatment failure in fracture-related infection

Surgical and microbiological characteristics that influence the probability of reoperation to promote bone healing after fracture-related infection diagnosis

PURPOSE

To compare the surgical and microbiological characteristics of fracture related infection (FRI) that had union and those requiring additional surgery to promote bone healing. We hypothesized that FRIs with MRSA will have higher risk for reoperation to promote bone healing.

METHODS

This is a retrospective study on 247 patients over 18 who underwent bone fixation for pelvis, upper, and lower extremities fractures between 2013 and 2021 at a level I trauma center. All cases had an FRI and at least 6 months of follow-up after diagnosis. Patients with pathologic fracture due to underlying malignancy and patients with spinal fractures were excluded. We compared surgical and microbiological characteristics of fractures between cases that required reoperation to promote bone healing and those who did not.

RESULTS

Of 247 patients, 55 (22.2%) required reoperations to promote bone healing after diagnosis of FRI. Patients that received topical antibiotics at closure during initial fixation had higher risk for reoperations to promote bone healing (30.8% vs. 15.2%, p = 0.049). Infection with Pseudomonas aeruginosa was associated with a lower risk for reoperations to promote bone healing (0%, p = 0.040). Rates of patients requiring reoperations to promote bone healing in infections with MRSA were similar to infections with MSSA (19.6% vs 20.9%, p = 1.000) and other pathogens (19.6% vs 23%; p = 0.539). Open fracture (OR 0.785, p = 0.534), tobacco use (OR 0.557, p = 0.126), upper extremity (OR 0.730, p = 0.534) or use of topical antibiotic at closure (OR 0.439, p = 0.067) did not increase risk for reoperation to promote bone healing.

CONCLUSION

Using topical antibiotics for skin closure during initial fixation for bone fractures may increase the risk of reoperation to promote bone healing, while infection with P. aeruginosa decreases the risk. Infection with MRSA or MSSA did not increase risk for requiring reoperation to promote bone healing after FRI diagnosis. Further studies should examine the impact of topical antibiotics during fracture surgery on development of FRI.

Development and validation of a preclinical canine model for early onset fracture-related infections

Fracture-related infections (FRIs) are a challenging complication in orthopaedics. Standard of care management for FRIs typically involves prolonged antibiotic therapies, irrigation and debridement (I&D) of the fracture site, and retention of fracture-fixation implants with or without exchange. Unfortunately, this treatment regimen is associated with treatment failure rates of up to 38 %, such that improved preventive and therapeutic interventions are needed. To test and develop these interventions, clinically relevant preclinical animal models are required. The purpose of this study was to develop and validate a canine model for early onset (<2 weeks) FRI that replicates its clinical, radiographic, bacteriologic, and histologic features. In this model, bilateral proximal fibular 1-cm ostectomies were created to mimic an open fracture, which was then stabilized using a plate and screws pre-incubated in methicillin-resistant Staphylococcus aureus (MRSA). After 7 days, I&D was performed and twice-daily systemic antibiotics were administered until the 17-day endpoint. This model consistently resulted in clinical signs of local infection, compromised wound healing, radiographic evidence for delayed bone healing and implant loosening, and implant-associated biofilm formation. Importantly, MRSA was isolated from deep tissue cultures in all dogs, and histological assessments detected bacteria and bacterial biofilms associated with all fracture-fixation implants at the study endpoint. These clinical, radiographic, bacteriologic, and histologic outcomes in conjunction with the capabilities for standard of care interventions, such as antibiotic treatment and I&D, verify that this preclinical canine model for early onset FRI effectively replicated the pathology associated with this commonly encountered complication of orthopaedic trauma.

Fracture-related infection blood-based biomarkers: Diagnostic strategies

Fracture-related infections are significant postoperative complications that carry substantial patient burden and additional healthcare costs. Despite their impact on outcome, early diagnosis of these infections remains challenging due to current available tests lacking acceptable diagnostic parameters. This review compiles existing information on blood-based biomarkers that have been evaluated as early diagnostic tools and highlights the challenges in their reliability. To begin to overcome these challenges new avenues of biomarker discovery utilizing "omics" technologies and novel analytical methods are being investigated in recent years. It appears that, despite their complexity, these newer approaches may be the future in biomarker discovery for fracture-related infection diagnosis.

Distally based sural flaps for soft tissue defects following traumatic osteomyelitis of lower leg and foot

This retrospective study aimed to determine the incidence and risk factors for osteomyelitis recurrence and present our experiences in treating traumatic osteomyelitis in the lower leg and foot. We retrospectively reviewed data from 174 patients with distally based sural flaps for treating traumatic osteomyelitis with soft tissue defects in the lower leg and foot from November 2003 to February 2021. Possible risk factors for osteomyelitis recurrence were compared between the osteomyelitis control and recurrence groups. A total of 162 (93.1%) flaps survived uneventfully, while 12 (6.9%) flaps developed partial necrosis. Five patients had a bone defect with an average length of 5 cm. The free vascularized bone grafts were performed in two patients, and bone transportations were performed in three patients. All patients were followed up with an average period of 72.8 months. There were 152 patients (87.4%) in control group and 22 patients (12.6%) in recurrence group. The recurrence rates of osteomyelitis were significantly higher when the patient's age was 40 years or more and the duration was 10 weeks or more (P < 0.05). Cierny-Mader (C-M) classification type IV osteomyelitis was also significantly associated with osteomyelitis recurrence (p = 0.049). This flap combined with appropriate osteomyelitis treatment was an effective method to treat traumatic osteomyelitis of lower leg and foot with a soft tissue defect. Both patient age ≥ 40 years old and C-M type IV osteomyelitis were nonnegligible risk factors for osteomyelitis recurrence.

Fracture related infection and sepsis in orthopedic trauma: A review

Trauma is a leading cause of death in the United States for people under 45. Amongst trauma-related injuries, orthopedic injuries represent a significant component of trauma-related morbidity. In addition to the potential morbidity and mortality secondary to the specific traumatic injury or injuries sustained, sepsis is a significant cause of morbidity and mortality in trauma patients as well, and infection related to orthopedic trauma can be especially devastating. Therefore, infection prevention and early recognition of infections is crucial to lowering morbidity and mortality in trauma. Risk factors for fracture-related infection include obesity, tobacco use, open fracture, and need for flap coverage, as well as fracture of the tibia and the degree of contamination. Timely administration of prophylactic antibiotics for patients presenting with open fractures has been shown to decrease the risk of fracture-related infection, and in patients that do experience sepsis from an orthopedic injury, prompt source control is critical, which may include the removal of implanted hardware in infections that occur more than 6 weeks from operative fixation. Given that orthopedic injury constitutes a significant proportion of traumatic injuries, and will likely continue to increase in number in the future, surgeons caring for patients with orthopedic trauma must be able to promptly recognize and manage sepsis secondary to orthopedic injury.

Multisite Study of the Management of Musculoskeletal Infection After Trauma: The MMUSKIT Study

Background

The optimal duration and choice of antibiotic for fracture-related infection (FRI) is not well defined. This study aimed to determine whether antibiotic duration (≤6 vs >6 weeks) is associated with infection- and surgery-free survival. The secondary aim was to ascertain risk factors associated with surgery- and infection-free survival.

Methods

We performed a multicenter retrospective study of patients diagnosed with FRI between 2013 and 2022. The association between antibiotic duration and surgery- and infection-free survival was assessed by Cox proportional hazard models. Models were weighted by the inverse of the propensity score, calculated with a priori variables of hardware removal; infection due to Staphylococcus aureus, Staphylococcus lugdunensis, Pseudomonas or Candida species; and flap coverage. Multivariable Cox proportional hazard models were run with additional covariates including initial pathogen, need for flap, and hardware removal.

Results

Of 96 patients, 54 (56.3%) received ≤6 weeks of antibiotics and 42 (43.7%) received >6 weeks. There was no association between longer antibiotic duration and surgery-free survival (hazard ratio [HR], 0.95; 95% CI, .65-1.38; P = .78) or infection-free survival (HR, 0.77; 95% CI, .30-1.96; P = .58). Negative culture was associated with increased hazard of reoperation or death (HR, 3.52; 95% CI, 1.99-6.20; P < .001) and reinfection or death (HR, 3.71; 95% CI, 1.24-11.09; P < .001). Need for flap coverage had an increased hazard of reoperation or death (HR, 3.24; 95% CI, 1.61-6.54; P = .001).

Conclusions

The ideal duration of antibiotics to treat FRI is unclear. In this multicenter study, there was no association between antibiotic treatment duration and surgery- or infection-free survival.

Time to Positivity in Blood Culture Bottles Inoculated with Sonication Fluid from Fracture-Related Infections

The timely and accurate identification of causative agents is crucial for effectively managing fracture-related infections (FRIs). Among various diagnostic methods, the "time to positivity" (TTP) of cultures has emerged as a valuable predictive factor in infectious diseases. While sonication of implants and inoculation of blood culture bottles with sonication fluid have enhanced sensitivity, data on the TTP of this microbiological technique remain limited. Therefore, patients with ICM criteria for confirmed FRI treated at our institution between March 2019 and March 2023 were retrospectively identified and their microbiological records were analyzed. The primary outcome parameter was TTP for different microorganism species cultured in a liquid culture collected from patients with confirmed FRI. A total of 155 sonication fluid samples from 126 patients (average age 57.0 ± 17.4 years, 68.3% males) was analyzed. Positive bacterial detection was observed in 78.7% (122/155) of the liquid culture pairs infused with sonication fluid. Staphylococcus aureus was the most prevalent organism (42.6%). Streptococcus species exhibited the fastest TTP (median 11.9 h), followed by Staphylococcus aureus (median 12.1 h) and Gram-negative bacteria (median 12.5 h), all of which had a 100% detection rate within 48 h after inoculation. Since all Gram-negative pathogens yielded positive culture results within 24 h, it could be discussed if empirical antibiotic therapy could be de-escalated early and limited towards the Gram-positive germ spectrum if no Gram-negative pathogens are detected up to this time point in the context of antibiotic stewardship.

Feasibility of using bacteriophage therapy to treat Staphylococcal aureus fracture-related infections

OBJECTIVE

Staphylococcus aureus fracture-related infections (FRIs) are associated with significant morbidity in part because conventional antibiotic therapies have limited ability to eradicate S. aureus in sessile states. Therefore, the objective of this study was to assess the feasibility of using Staphylococcal bacteriophages for FRI by testing the activity of a library of Staphylococcal bacteriophage therapeutics against historically preserved S. aureus FRI clinical isolates.

METHODS

Current Procedural Terminology codes were used to identify patients with FRI from January 1, 2021 to December 31, 2021. Preserved S. aureus FRI isolates from the cases were then tested against a library of 51 Staphylococcal bacteriophages from an American company. This was conducted by assessing the ability of bacteriophages to reduce bacterial growth over time. Growth inhibition greater than 16 h was considered adequate for this study.

RESULTS

All of the S. aureus preserved clinical isolates had at least one bacteriophage with robust lytic activity and six bacteriophages (11.8 %) had robust lytic activity to seven or more of the clinical isolates. However, 41 of the bacteriophages (80.4 %) had activity to less than three of the clinical isolates and no bacteriophage had activity to all the clinical isolates.

CONCLUSION

Our findings show that Staphylococcal bacteriophage therapeutics are readily available for S. aureus FRI clinical isolates. However, when correlated with the current barriers to using bacteriophages to treat FRI, designated Staphylococcal bacteriophage cocktails with broad spectrum activity should be created.

High Nonunion and Amputations Rates With Either Early Intramedullary Nail Removal or Retention for Tibial Shaft Fracture-Related Infections

OBJECTIVES

To compare debridement, antibiotics, and implant retention (DAIR) and intramedullary nail (IMN) removal with subsequent strategy for fracture stabilization in the treatment of tibia fracture-related infections (FRIs) occurring within 90 days of initial IMN placement.

DESIGN

Retrospective case-control.

SETTING

Four academic, Level 1 trauma centers.

PATIENTS

Sixty-six patients who subsequently received unplanned operative treatment for FRI diagnosed within 90 days of initial tibia IMN.

INTERVENTION

DAIR versus IMN removal pathways.

MAIN OUTCOME MEASUREMENTS

Fracture union.

RESULTS

Twenty-eight patients (42.4%) were treated with DAIR and 38 (57.6%) via IMN removal with subsequent strategy for fracture stabilization. Mean follow-up was 16.3 months. At final follow-up, ultimate bone healing was achieved in 75.8% (47/62), whereas 24.2% (15/62) had persistent nonunion or amputation. No significant difference was observed in ultimate bone healing ( P = 0.216) comparing DAIR and IMN removal. Factors associated with persistent nonunion or amputation were time from injury to initial IMN ( P < 0.001), McPherson systemic host grade B ( P = 0.046), and increasing open-fracture grade, with Gustilo-Anderson IIIB/IIIC fractures being the worst ( P = 0.009). Fewer surgeries after initial FRI treatment were positively associated with ultimate bone healing ( P = 0.029).

CONCLUSIONS

Treatment of FRI within 90 days of tibial IMN with DAIR or IMN removal with subsequent strategy for fracture stabilization results in a high rate, nearly 1 in 4, of persistent nonunion or amputation, with neither appearing superior for improving bone healing outcomes.

LEVEL OF EVIDENCE

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

Devascularized Bone Surface Culture: A Novel Strategy for Identifying Osteomyelitis-Related Pathogens

The gold standard for identifying pathogens causing osteomyelitis (OM) is intraoperative tissue sampling culture (TSC). However, its positive rate remains inadequate. Here, we evaluated the efficiency of a novel strategy, known as devitalized bone surface culture (BSC), for detecting OM-related microorganisms and compared it to TSC. Between December 2021 and July 2022, patients diagnosed with OM and received both methods for bacterial identification were screened for analysis. In total, 51 cases were finally recruited for analysis. The mean age was 43.6 years, with the tibia as the top infection site. The positive rate of BSC was relatively higher than that of TSC (74.5% vs. 58.8%, p = 0.093), though no statistical difference was achieved. Both BSC and TSC detected definite pathogens in 29 patients, and their results were in accordance with each other. The most frequent microorganism identified by the BSC method was Staphylococcus aureus. Moreover, BSC took a significantly shorter median culture time than TSC (1.0 days vs. 3.0 days, p < 0.001). In summary, BSC may be superior to TSC for identifying OM-associated pathogens, with a higher detectable rate and a shorter culture time.

Fracture Related Infections and Their Risk Factors for Treatment Failure—A Major Trauma Centre Perspective

Fracture related infections (FRI) are debilitating and costly complications of musculoskeletal trauma surgery that can result in permanent functional loss or amputation. Surgical treatment can be unsuccessful, and it is necessary to determine the predictive variables associated with FRI treatment failure, allowing one to optimise them prior to treatment and identify patients at higher risk. The clinical database at a major trauma centre was retrospectively reviewed between January 2015 and January 2021. FRI treatment failure was defined by infection recurrence or amputation. A univariable logistic regression analysis was performed, followed by a multivariable regression analysis for significant outcomes between groups on univariable analysis, to determine risk factors for treatment failure. In total, 102 patients were identified with a FRI (35 open, 67 closed fractures). FRI treatment failure occurred in 24 patients (23.5%). Risk factors determined by our multivariate logistic regression model were obesity (OR 2.522; 95% CI, 0.259–4.816; p = 0.006), Gustilo Anderson type 3c (OR 4.683; 95% CI, 2.037–9.784; p = 0.004), and implant retention (OR 2.818; 95% CI, 1.588–7.928; p = 0.041). Given that FRI treatment in 24 patients (23.5%) ended up in failure, future management need to take into account the predictive variables analysed in this study, redirect efforts to improve management and incorporate adjuvant technologies for patients at higher risk of failure, and implement a multidisciplinary team approach to optimise risk factors such as diabetes and obesity.