Diagnosing Infection in Patients Undergoing Conversion of Prior Internal Fixation to Total Hip Arthroplasty

Total Hip Arthroplasty in Challenging Settings: Acetabular Fractures, Adolescents, Conversions, and Developmental Dysplasia of the Hip

Total hip arthroplasty (THA) is one of the most common and successful procedures for the treatment of end-stage hip arthritis. However, in certain complex scenarios, THA can present important and unique challenges, specifically following acetabular fractures in adolescent patients, following failed fixation of proximal femoral fractures, and in developmental dysplasia of the hip (DDH). As these cases involve distorted anatomy, poor bone quality, retained hardware, and previous surgeries, detailed planning, specialized instrumentation and implants, and novel surgical techniques are required. This narrative review examines the challenges, surgical considerations, outcomes, and complications in complex THA management.

Identification of clinical risk factors and optimal inflammatory marker cutoffs for the diagnosis of septic nonunion at time of presentation

PURPOSE

The diagnosis of septic nonunion is difficult due to the risk of occult presentation. The purpose of this study is to identify risk factors for infection prior to nonunion surgery.

METHODS

This retrospective cohort study was completed at a single tertiary referral level one trauma center. Patients were included if they had surgery to repair a nonunion of the femur, tibia, or humerus after operative initial management. Predictors for septic nonunion were determined based on clinical, laboratory, and radiographic findings.

RESULTS

122 Patients met inclusion criteria. 28 Patients (23.0%) were diagnosed with septic nonunion. Clinical risk factors for septic nonunion diagnosis on multivariate regression included nonunion surgery performed at an outside hospital prior to referral (p = 0.003) and early infection requiring debridement within 60 days of initial injury (p = 0.01). Ideal inflammatory marker cutoffs based on ROC curves included WBC > 8.1 × 109/L (p = 0.001) and CRP > 14.1 mg/L (p = 0.001).

CONCLUSION

This study demonstrates additional clinical risk factors and re-defines cutoff values for laboratory biomarkers as predictors for diagnosis of septic nonunion. These data may help providers better identify cases of septic nonunion prior to nonunion surgery.

Unexpected positive cultures in conversion hip and knee arthroplasty

PURPOSE

Total hip and knee arthroplasty in patients with previous history of periarticular surgery, such as osteosynthesis, can be surprisingly complex. This type of procedure is known as conversion arthroplasty (cTHA or cTKA) and has a higher risk of complications. The rates of unexpected positive cultures (UPC) and the risk of periprosthetic joint infection (PJI) compared to primary arthroplasty is unclear. The main purpose of this study was to evaluate rates of Unexpected Positive Cultures (UPC) in a series of conversion arthroplasty patients. The main questions to answer are: 1. Are the patients with conversion arthroplasties more susceptible to UPC than other causes of revision arthroplasties? 2. Are the conversion patients with UPC more susceptible to developing PJI?

METHODS

This was a retrospective review of patients submitted to cTHA and cTKA from January 2012 to September 2018. Patients with history of previous infection or with missing intraoperative cultures were excluded. The UPC was defined as a single positive culture obtained during a procedure previously considered aseptic and PJI was defined according to the 2018 ICM criteria. After excluding 141 cases, 205 patients were analyzed, 160 hips and 45 knees.

RESULTS

Nine (4.4%) UPC were identified, five (3.1%) in the hip group and four (8,9%) in the knee group. Staphylococcal species were the most common isolated bacteria (n = 7, 77.7%). During the study period, four (1,9%) patients were diagnosed with PJI. Only one case had an UPC and a different germ was identified during revision arthroplasty workup.

CONCLUSIONS

While UPC are more prevalent in conversion knee arthroplasties compared to conversion hip arthroplasties, the rates are similar to those observed in revision arthroplasty for other indications. Importantly, the presence of a UPC in conversion arthroplasty does not appear to elevate the risk of subsequent periprosthetic joint infection, provided a thorough PJI workup has been conducted preoperatively. Therefore, in such cases, UPCs may be safely disregarded.

Latent infections in conversion total hip arthroplasty following internal fixation of femoral neck fractures: a systematic review and meta-analysis of diagnostic methods

BACKGROUND

Accurate diagnosis of latent infections prior to conversion total hip arthroplasty (THA) following internal fixation of femoral neck fractures is crucial for successful surgical outcomes. This systematic review aimed to provide a comprehensive evaluation of the current literature regarding the diagnosis of latent infections before conversion THA.

METHODS

Systematic search of PubMed, EMBASE, and Cochrane (CENTRAL) databases was conducted, and the diagnostic accuracy of various markers and techniques was assessed. The quality of the included studies was evaluated using the QUADAS-2 instrument.

RESULTS

Five studies comprising 661 patients were included in the review. Pooled analysis using C-reactive protein (CRP) as a diagnostic marker resulted in a sensitivity and specificity of 72% and 76%, respectively, while using erythrocyte sedimentation rate (ESR) yielded a sensitivity and specificity of 75% and 78%, respectively. Fibrinogen and platelet count showed lower sensitivity and specificity compared to CRP and ESR. The best combined markers were CRP and serum platelet count, with a sensitivity of 76% and specificity of 86% based on one study.

CONCLUSION

Our review underscored the limitations and inconsistencies present in current diagnostic methods for latent infections in conversion surgery. Future research needs to focus on standardizing threshold values, exploring the potential of synovial fluid analysis, imaging techniques, and molecular methods, as well as developing tailored diagnostic algorithms.

PROSPERO

CRD42023394757.

Salvage Total Hip Replacement for Failed Proximal Femoral Fracture Fixation

INTRODUCTION

Salvage arthroplasty for failed proximal femoral fracture fixation is a complex procedure. This involves the removal of the primary failed or broken implant followed by a hip joint replacement procedure. The complications and technical difficulties associated with these surgeries are often difficult to anticipate.

METHODS

Initially, to further understand the position in the literature with regard to salvage arthroplasty, we completed an informative scoping review. Search terms were selected, and databases Embase and PubMed were utilised to form a literature search. Relevant articles were selected by two independent researchers, with a final list of nine studies reviewed and tabulated for themes to be identified and analysed. Subsequently, we retrospectively studied the notes of all the patients who underwent complex conversion arthroplasty in the same district hospitals in a span of 16 years (August 2002 to August 2018) and presented the results.

RESULTS

Seventy-one patients underwent complex salvage arthroplasty following a failed fixation of proximal femoral fracture under the care of three different surgeons. All surgeries were carried out by the posterior approach. The demographics, intraoperative events, and postoperative follow-up have been presented through clinical and radiological assessments. With a mean age being 73.6, female patients were almost twice the number of male patients. The left hip was the more common surgical site. Implant cutout was the most common cause of failure of the primary implant. Most of these surgeries were either uncemented (31 cases, 43.66%) or hybrid (29 cases, 40.84%). The most common acetabular size to be used was 50 mm, and the most common head size used was 32 mm. A majority of the surgeries were metal on poly bearings (64 cases, 90.14%). The mean surgical time, including anesthetic, was four hours and 13 minutes. A total of 31 (44%) patients needed blood transfusion postoperatively. The infection rate was 21.13% (15 cases), being the most common surgical complication. The mean follow-up of the patients was 27.2 months with the maximum follow-up being 125 months. The one-year mortality was found to be 14% (10 cases). The mean limb length discrepancy was shortening by an average of 3.84 mm. A total of 66.2% (47 cases) of patients were shortened postoperatively. The average cup abduction and anteversion angles were 35° and 24.25°, respectively. The average position of the femoral stem was 0.31° in the varus with 40.85% (29 cases) of patients having a slightly varus stem.

CONCLUSION

Upon drawing comparisons with primary hip arthroplasty for primary osteoarthritis through data available in the literature, it is obvious that salvage arthroplasty is a complex procedure with longer surgical times and onerous rehabilitation. Whilst it is not the same as revision arthroplasty, many of the characteristics in terms of surgical planning and outcomes are similar. Therefore, it is our recommendation that salvage hip arthroplasty procedures should be categorised, listed, and studied separately from primary arthroplasty in the National Joint Registry database.

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.

High Rate of Undetected Infections in Failed Osteosynthesis of Pertrochanteric Fractures

OBJECTIVE

The objective of this study was to assess the incidence of infection in patients with cutout after proximal femur fracture (PFF) osteosynthesis.

METHODS

DESIGN

Retrospective cohort study.

SETTING

Third-level trauma center.

PATIENT SELECTION CRITERIA

Patients presenting with a cutout following PFF (OTA/AO 31A) osteosynthesis, between January 2007 and December 2020.

OUTCOME MEASUREMENTS AND COMPARISONS

The primary outcome was infection according to the European Bone and Joint Infection Society criteria.

RESULTS

Sixty-seven patients presenting with a cutout were included, with mean age of 83.3 years (range 63-96), and 51 (76.1%) were women. Of all cases, 16 (24.7%) presented a concomitant infection. The presence of concomitant infection was suspected preoperatively in only 3 of the cases. A subgroup analysis was performed between the cases with infection and those without infection, the groups being comparable in terms of demographic data and postoperative radiological criteria. Patients with underlying infection had a higher rate of surgical wound complication (56.3% vs. 22%, P = 0.014) and higher rates of leukocytosis (11.560 vs. 7.890, P = 0.023).

CONCLUSION

Faced with a cutout after osteosynthesis of a PFF, underlying infection should be considered as a possible etiological factor.

LEVEL OF EVIDENCE

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

Retrospective Analysis of Infection Factors in Secondary Internal Fixation after External Fixation for Open Fracture of a Long Bone: A Cohort of 117 Patients in a Two-Center Clinical Study

Purpose

To investigate infection risk factors after secondary internal fixation (IF) of open fracture of a long bone with removed fixation frame and explore the safe range of feasible operation for abnormal inflammatory indicators.

Methods

Clinical data of 117 cases of open fracture of a long bone that underwent temporary external fixation (EF) in one stage and IF in two stages were retrospectively analyzed. Collected data included age, sex, Gustilo type, multiple injuries, debridement time, duration of EF, needle infection, interval of conversion to IF after external fixator, preoperative white blood cell (WBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), albumin (ALB), blood glucose, and prognosis. We selected these factors for univariate analysis of postoperative surgical site infection (SSI) and multivariate logistic regression analysis of statistically significant risk factors and created receiver operating characteristic (ROC) curves to compare the diagnostic efficiency of each index and determine the optimal screening point.

Results

We followed up 117 patients, with 130 limbs affected. Univariate analysis showed that ESR, CRP, ALB, WBC, EF time, and Gustilo fracture type were significantly associated with SSI. Multivariate logistic regression analysis showed that CRP, duration of EF, and Gustilo fracture type were independently associated with postoperative infection. Area under ROC curves for WBC, ESR, and CRP were 69.7%, 73.2%, and 81.2%.

Conclusions

We demonstrated the role of Gustilo classification of open fractures in predicting postoperative infection, especially for open fractures above type III. If the inflammatory indexes return to normal or show a downward trend, and the second-stage IF operation is performed within the cutoff values, postoperative recurrent infection was reduced.

Conversion hip arthroplasty via the direct anterior approach: pearls, pitfalls and personal experience

OBJECTIVE

Conversion total hip arthroplasty (CTHA) through a direct anterior approach (DAA) in supine position.

INDICATIONS

Failed osteosynthesis of proximal femoral fractures or failed conservative hip surgery, with hardware in situ.

CONTRAINDICATIONS

Decayed general conditions, infection (peri-implant or systemic infection), need for greater trochanter reconstruction, severe proximal femur deformity.

SURGICAL TECHNIQUE

Supine position. Mark DAA and expected limited incisions for hardware removal (HR) with the help of a C-arm. Use guidewire and extraction devices for HR. Perform a DAA with particular attention to a wide release of the femur.

POSTOPERATIVE MANAGEMENT

Full progressive weight-bearing starting on day 1, depending on bone quality. Discharge with crutches following patient walking capability. Precautions for 6 weeks.

RESULTS

In all, 27 conversion THAs through a DAA. Mean age at the time of surgery 59.8 (range 18-81) years. Mean body mass index was 23.5 (range 17-31.6). Reasons of previous surgery failures were avascular necrosis of the femoral head, posttraumatic arthritis and nonunion with or without hardware migration. Mean surgical time was 125.8 min (range 58-190 min, standard deviation [SD] 38.2 min). Mean follow-up time was 6.9 years (range 2-15, SD 5.03 years). Mean pre-Harris Hip Score (mHHs) was 24.4 (range 19-36, SD 5.4), while the mean post-mHHS was 90.3 (range 89-91, SD 0.95). Two patients required postoperative osteosynthesis for periprosthetic fractures due to falls. Overall complication rate was 10%.

The Screening of Fixation-Related Infection in Patients Undergoing Conversion Total Hip Arthroplasty after Failed Internal Fixation of Hip Fractures: A Single-Central Retrospective Study

Objective

To evaluate the diagnostic values of preoperative plasma fibrinogen and platelet count for screening fixation‐related infection (FRI) in patients undergoing conversion total hip arthroplasty (cTHA) after failed internal fixation of hip fractures.

Method

This was a single‐center retrospective study. Data were retrospectively analyzed for 435 patients who underwent cTHA in our hospital from January 2008 to September 2020. They were divided into infected (n = 30) and non‐infected groups (n = 405) according to the 2013 International Consensus Meeting (ICM) criteria. The diagnostic sensitivity and specificity of plasma fibrinogen and platelet count were determined using receiver operating characteristic (ROC) curves. Optimal predictive cutoffs of these two markers were determined based on the Youden index. In addition, the diagnostic value of preoperative serum C‐reactive protein (CRP) and erythrocyte sedimentation rate (ESR) for screening FRI were also evaluated based on the cutoffs recommended by the 2013 ICM Criteria. Finally, the diagnostic ability of various combinations of the plasma fibrinogen and platelet count as well as serum CRP and ESR was re‐assessed.

Results

The numbers of patients with and without FRI were 30 (6.9%) and 405 (93.1%), respectively. Areas under the ROC curves were 0.770 for fibrinogen, 0.606 for platelet, 0.844 for CRP and 0.749 for ESR. The optimal predictive cutoff of fibrinogen was 3.73 g/L, which gave sensitivity of 60.0% and specificity of 90.5%. The optimal predictive cutoff for platelet was 241.5 × 10⁹/L, which gave sensitivity of 46.7% and specificity of 83.7%. The CRP gave sensitivity of 66.7% and specificity of 92.5% with the predetermined cutoff of 10 mg/L, while the ESR gave sensitivity of 67.5% and specificity of 72.4% % with the predetermined cutoff of 30 mm/h. The combination of CRP and ESR showed high specificity of 93.2% but low sensitivity of 66.7%, while the corresponding values for CRP with fibrinogen were satisfied both for sensitivity of 80.0% and specificity of 78.7%. The combination of these four biomarkers gave sensitivity of 73.3% and specificity of 85.7%.

Conclusion

Preoperative serum CRP, ESR, plasma fibrinogen and platelet count have low sensitivity on their own for screening FRI in patients, but the combination of CRP with fibrinogen shows promise for that.

Single-stage total hip arthroplasty after failed fixation of proximal femoral fractures: an increased risk for periprosthetic joint infections?

BACKGROUND

Higher complication rates have been reported for total hip arthroplasty (THA) after osteosynthesis of proximal femur fractures (PFF). This study evaluated the infection risk for conversion of internal fixation of PFF to THA by a single-staged procedure in the absence of clear infection signs.

METHODS

Patients undergoing a one-staged conversion to THA (2013-2018) after prior internal fixation of the proximal femur were included. Preoperative diagnostics with laboratory results, hip aspirations as well as intraoperative microbiology and sonication were assessed. Postoperative complications were recorded as well as patient demographics, duration between initial and conversion to THA, explanted osteosynthesis and implanted THA.

RESULTS

Fifty-eight patients (24 male/34 female, 62.8 ± 14.5 years) were included with a mean time of 3.8 ± 7.5 years between internal fixation and conversion to THA (45 cementless, 3 cemented, 3 hybrid and 7 hybrid inverse THAs). Preoperative mean blood level CRP was 8.36 ± 14 mg/l (reference value < 5 mg/l) and leukocyte count was 7.11 ± 1.84^3/µl (4.5-10.000^3/µl). Fifty patients had intraoperative microbiological diagnostics, with either swabs in 86.2% and/or sonication in 29.3%. Positive microbiological results were recorded in 10% (5 of 50 patients), with pathogens identified being mainly Staphylococcus. Complications after conversion occurred in 9.6% including a postoperative low-grade infection rate of 5.8% after a mean of 2.5 years.

CONCLUSION

This study found a positive microbiological test result in 10% of a one-stage conversion of PFF fixation to THA. Moreover, we found a high infection rate (5.8%) for early postoperative periprosthetic joint infection. Interestingly, CRP has not been proven to be an adequate parameter for low-grade infections or occult colonized implants. Therefore, we recommend a comprehensive pre- and intraoperative diagnostic including hip aspiration, swabs and sonication when considering one-staged revision.

The fate of positive intraoperative cultures following conversion total hip arthroplasty

INTRODUCTION

The objectives of this study are to report the rates of positive intraoperative cultures obtained during conversion total hip arthroplasty (THA) according to index surgery, and to describe the natural history of treatment for a consecutive series of patients with unexpected positive intraoperative cultures during conversion THA.

METHODS

We reviewed all patients at 2 institutions undergoing conversion THA from prior open reduction and internal fixation (ORIF) of acetabular and hip fractures or hemiarthroplasty for displaced femoral neck fractures from 2011 to 2018. Intraoperative cultures were taken in 105 patients. Positive intraoperative cultures during conversion were recorded and managed with an infectious diseases consult. The outcomes including PJI at 90 days and 1 year follow-up were documented.

RESULTS

Overall, 19 of 105 patients (18%) undergoing conversion THA had positive intraoperative cultures, with the highest rates in the hemiarthroplasty 7/16 (44%) and acetabular ORIF 9/48 (19%) groups. All 19 patients were initially treated conservatively: 8 received IV antibiotics, 10 received no additional therapy, and 1 received oral antibiotics. 4/9 acetabular fracture conversions developed PJI at 1 year, with 3 requiring multiple irrigation and debridement/polyethylene exchanges to control the infection while the 4th patient required 2-stage exchange. There were no 1-year PJI from any of the other index procedures after conversion. All 7 hemiarthroplasty patients with positive cultures were treated to resolution with 4-8 weeks IV antibiotics alone.

CONCLUSIONS

Patients undergoing conversion THA from prior hip or acetabular fracture have a high rate of positive intraoperative cultures. As such, all patients undergoing conversion THA from prior hip or acetabular fracture fixation should undergo thorough diagnostic workup prior to surgery, and have intraoperative cultures obtained during surgery if infection remains suspicious. Further work should be performed to develop MSIS criteria for preoperative management of patients undergoing conversion THA.

Is implant sonication useful when screening for infection in conversion of prior hip fracture fixation to total hip arthroplasty?

Objective

To examine sonication results in presumed aseptic conversion total hip arthroplasty (THA) after hip fracture fixation and to evaluate its implications on the treatment outcome.

Methods

This retrospective cohort study reviewed the data from presumed aseptic patients that underwent conversion of prior internal fixation of proximal femoral fractures to THA between 2012 and 2018. Microbiological analysis was performed using sonication of osteosynthesis material and tissue samples. Treatment outcome including the occurrence of periprosthetic joint infection (PJI) was recorded.

Results

A total of 32 patients were included in the study. Of these, five patients (15.6%) had positive intraoperative cultures. The mean follow-up following conversion THA was 43.0 months (range, 19.0–91.5 months). Sonication was positive in three patients (9.4%), all of whom were deemed contaminated and did not develop PJI. Tissue cultures were positive in two patients (6.3%). One patient with Enterococcus faecalis received antibiotic treatment and did not develop PJI. Another patient with growth of Cutibacterium acnes that was initially classified as a contaminant later developed acute PJI caused by the same pathogen. Overall, PJI occurred in two patients (6.3%) after conversion THA.

Conclusion

Sonication of internal fixation devices did not add diagnostic value in clinically aseptic conversion THA. Further studies are needed to better understand the relevance of unexpected positive cultures, and to develop diagnostic criteria for the management of these patients.

Patients' risk factors for periprosthetic joint infection in primary total hip arthroplasty: a meta-analysis of 40 studies

BACKGROUND

Periprosthetic joint infection (PJI) is a catastrophic complication after total hip arthroplasty (THA). Our meta-analysis aimed to identify the individual-related risk factors that predispose patients to PJI following primary THA.

METHODS

Comprehensive literature retrieval from Pubmed, Web of Science, and the Cochrane Library was performed from inception to Feb 20th, 2021. Patient-related risk factors were compared as per the modifiable factors (BMI, smoke and alcohol abuse), non-modifiable factors (gender, age), and medical history characteristics, such as diabetes mellitus (DM), avascular necrosis (AVN) of femoral head, femoral neck fracture, rheumatoid arthritis (RA), cardiovascular disease (CVD), and osteoarthritis (OA) etc. The meta-analysis was applied by using risk ratios with 95% corresponding intervals. Sensitivity analysis and publication bias were performed to further assess the credibility of the results.

RESULTS

Overall, 40 studies with 3,561,446 hips were enrolled in our study. By implementing cumulative meta-analysis, higher BMI was found associated with markedly increased PJI risk after primary THA [2.40 (2.01-2.85)]. Meanwhile, medical characteristics including DM [1.64 (1.25-2.21)], AVN [1.65 (1.07-2.56)], femoral neck fracture [1.75 (1.39-2.20)], RA [1.37 (1.23-1.54)], CVD [1.34 (1.03-1.74)], chronic pulmonary disease (CPD) [1.22 (1.08-1.37)], neurological disease [1.19 (1.05-1.35)], opioid use [1.53 (1.35-1.73)] and iron-deficiency anemia (IDA) [1.15 (1.13-1.17)] were also significantly correlated with higher rate of PJI. Conversely, dysplasia or dislocation [0.65 (0.45-0.93)], and OA [0.70 (0.62-0.79)] were protective factors. Of Note, female gender was protective for PJI only after longer follow-up. Besides, age, smoking, alcohol abuse, previous joint surgery, renal disease, hypertension, cancer, steroid use and liver disease were not closely related with PJI risk.

CONCLUSION

Our finding suggested that the individual-related risk factors for PJI after primary THA included high BMI, DM, AVN, femoral neck fracture, RA, CVD, CPD, neurological disease, opioid use and IDA, while protective factors were female gender, dysplasia/ dislocation and OA.

Combination of CRP with NLR is a sensitive tool for screening fixation-related infection in patients undergoing conversion total hip arthroplasty after failed internal fixation for femoral neck fracture

AIMS

Monocyte-lymphocyte ratio (MLR) or neutrophil-lymphocyte ratio (NLR) are useful for diagnosing periprosthetic joint infection (PJI), but their diagnostic values are unclear for screening fixation-related infection (FRI) in patients for whom conversion total hip arthroplasty (THA) is planned after failed internal fixation for femoral neck fracture.

METHODS

We retrospectively included 340 patients who underwent conversion THA after internal fixation for femoral neck fracture from January 2008 to September 2020. Those patients constituted two groups: noninfected patients and patients diagnosed with FRI according to the 2013 International Consensus Meeting Criteria. Receiver operating characteristic (ROC) curves were used to determine maximum sensitivity and specificity of these two preoperative ratios. The diagnostic performance of the two ratios combined with preoperative CRP or ESR was also evaluated.

RESULTS

The numbers of patients with and without FRI were 19 (5.6%) and 321 (94.4%), respectively. Areas under the ROC curve for diagnosing FRI were 0.763 for MLR, 0.686 for NLR, 0.905 for CRP, and 0.769 for ESR. Based on the Youden index, the optimal predictive cutoffs were 0.25 for MLR and 2.38 for NLR. Sensitivity and specificity were 78.9% and 71.0% for MLR, and 78.9% and 56.4% for NLR, respectively. The combination of CRP with MLR showed a sensitivity of 84.2% and specificity of 94.6%, while the corresponding values for the combination of CRP with NLR were 89.5% and 91.5%, respectively.

CONCLUSION

The presence of preoperative FRI among patients undergoing conversion THA after internal fixation for femoral neck fracture should be determined. The combination of preoperative CRP with NLR is sensitive tool for screening FRI in those patients. Cite this article: Bone Joint J 2021;103-B(9):1534-1540.

Total Hip Arthroplasty After Prior Acetabular Fracture: Infection Is a Real Concern

BACKGROUND

Acetabular fractures often require surgical intervention for fracture fixation and can result in premature osteoarthritis of the hip joint. This study hypothesized that total hip arthroplasty (THA) in patients with a prior acetabular fracture who had undergone open reduction and internal fixation (ORIF) is associated with a higher rate of subsequent periprosthetic joint infection (PJI).

METHODS

About 72 patients with a history of acetabular fracture that required ORIF, undergoing conversion THA between 2000 and 2017 at our institution, were matched based on age, gender, body mass index, Charlson comorbidity index, and date of surgery in a 1:3 ratio with 215 patients receiving primary THA. The mean follow-up for the conversion THA cohort was 2.9 years (range, 1-12.15) and 3.06 years (range, 1-12.96) for the primary THA.

RESULTS

Patients with a previous acetabular fracture, compared with the primary THA patients, had longer operative times, greater operative blood loss, and an increased need for allogeneic blood transfusion (26.4% vs 4.7%). Most notably, PJI rate was significantly higher in acetabular fracture group at 6.9% compared with 0.5% in the control group. Complications, such as aseptic revision, venous thromboembolism, and mortality, were similar between both groups.

CONCLUSION

The present study demonstrates that conversion THA in patients with prior ORIF of acetabular fractures is associated with higher complication rate, in particular PJI, and less optimal outcome compared with patients undergoing primary THA. The latter findings compel us to seek and implement specific strategies that aim to reduce the risk of subsequent PJI in these patients.

Limited diagnostic value of serum inflammatory biomarkers in the diagnosis of fracture-related infections

AIMS

The aim of this study was to evaluate the diagnostic value of preoperative serum CRP, white blood cell count (WBC), percentage of neutrophils (%N), and neutrophil to lymphocyte ratio (NLR) when using the fracture-related infection (FRI) consensus definition.

METHODS

A cohort of 106 patients having surgery for suspected septic nonunion after failed fracture fixation were studied. Blood samples were collected preoperatively, and the concentration of serum CRP, WBC, and differential cell count were analyzed. The areas under the curve (AUCs) of diagnostic tests were compared using the z-test. Regression trees were constructed and internally cross-validated to derive a simple diagnostic decision tree.

RESULTS

Using the FRI consensus definition, 46 patients (43%) were identified as infected. Sensitivity, specificity, and AUC of CRP were 67% (95% confidence interval (CI) 52% to 80%), 61% (95% CI 47% to 74%), and 0.64 (95% CI 0.54 to 0.74); of WBC count were 17% (95% CI 9% to 31%), 95% (95% CI 86% to 99%), and 0.57 (95% CI 0.50 to 0.62); of %N 13% (95% CI 6% to 26%), 87% (95% CI 76% to 93%), and 0.50 (95% CI 0.43 to 0.56); and of NLR 28% (95% CI 17% to 43%), 80% (95% CI 68% to 88%), and 0.54 (95% CI 0.46 to 0.63), respectively. A better performance of serum CRP was shown in comparison to the leucocyte count (p = 0.006), %N (p < 0.001), and NLR (p = 0.001). A statistically lower serum CRP level was shown in patients with an infection caused by a low virulence microorganism in comparison to high virulence bacteria (p = 0.008). We found that a simple decision tree approach using only low serum neutrophils (< 3.615 × 10⁹/l) and low CRP (< 2.45 mg/l) may allow better identification of aseptic cases.

CONCLUSION

The evaluated serum inflammatory markers showed limited diagnostic value in the preoperative diagnosis of FRI when using the uniform FRI Consensus Definition. Therefore, they should remain as suggestive criteria in diagnosing FRI. Although CRP showed a higher performance in comparison to the other serum markers, it is insufficiently accurate to diagnose a septic nonunion, especially when caused by low virulence microorganisms. Cite this article: Bone Joint J 2020;102-B(7):904-911.

The Value of Serological Screening Prior to Conversion Total Hip Arthroplasty

BACKGROUND

This study sought (1) to assess the value of serological testing prior to conversion total hip arthroplasty (THA) in predicting infection and (2) to identify optimal serological values for routine diagnostic workup prior to conversion THA.

METHODS

All patients at our tertiary referral center undergoing conversion THA after hip/acetabular fracture procedure from 2013 to 2018 were retrospectively reviewed. Inclusion criteria were patients previously undergoing hemiarthroplasty or open reduction and internal fixation of acetabular, intertrochanteric, and subtrochanteric fractures that progressed to conversion THA due to post-traumatic arthritis having erythrocyte sedimentation rate/C-reactive protein (CRP) prior to conversion. Infection was defined as positive intraoperative cultures not deemed contaminant in collaboration with infectious disease consult and/or development of PJI within 1 year postoperatively.

RESULTS

Twelve of 87 (14%) patients undergoing conversion THA developed infection. The mean erythrocyte sedimentation rate (37.2 vs 24.4 mm/h, P = .2062) and CRP (22.4 vs 9.0 mg/L, P = .0026) in the infected cohort were elevated compared to the noninfected group. An optimal cutoff value for CRP of 12 mg/L (area under the curve = 0.77, 95% confidence interval 0.58-0.97) revealed 75% sensitivity, 84% specificity, 43% positive predictive value, and 95% negative predictive value (P < .0001) in the entire cohort.

CONCLUSIONS

Even without clinical signs and symptoms, patients undergoing conversion THA from internal fixation of hip/acetabular fractures are still at high risk for developing periprosthetic joint infection. All patients undergoing conversion THA should have CRP measured preoperatively as a part of the diagnostic workup for underlying infection. Further research should be devoted to creating a preoperative diagnostic algorithm incorporating CRP, similar to Musculoskeletal Infection Society criteria, dedicated to patients undergoing conversion THA.

LEVEL OF EVIDENCE

Level III, Diagnostic retrospective cohort study.

One-Stage Arthroplasty or Revision for Seronegative Infections in Hip and Knee

Objective

To assess the safety and effectiveness of one‐stage total joint arthroplasty (TJA) or revision for seronegative infections after total hip arthroplasty (THA) and total knee arthroplasty (TKA).

Methods

This retrospective study included a total of 495 patients who had undergone one‐stage total joint (hip or knee) arthroplasty or revision with a diagnosis of osteoarthritis secondary to sepsis, osteoarthritis or osteonecrosis of the femoral head (ONFH) secondary to internal fixation surgery of the hip joint, and one‐stage revision for prosthesis loosening after THA or TKA from January 2012 to December 2016. Bacterial cultures were taken from all patients (from joint fluid or articular cavity fluid and four to six different parts of soft tissues) during the operation. If the cultures were positive, patients received antibiotic treatment. Microbiology results from surgical samples, clinical evaluations, SF‐12 score (physical component summary [PCS] and mental component summary [MCS]), Harris hip score (HHS) or Hospital for Special Surgery (HSS) score, and patients' satisfaction was recorded at every follow‐up session.

Results

A total of 24 patients had a positive result for bacterial culture (4.85%). The bacterial culture results showed that there were 19 cases (79.16%) of gram‐positive cocci (Staphylococcus aureus), 4 cases (16.67%) of gram‐negative bacilli, and 1 case (4.17%) of fungi. For at least 24 months (mean 35 months) follow‐up, no reinfection was discovered. The mean HHS or HSS score improved significantly from 36.29 points preoperatively to 84.21 points postoperatively (P < 0.001). The mean PCS score improved from 10.15 preoperatively to 20.34 postoperatively, and the mean MCS from 13.22 preoperatively to 21.76 postoperatively, with significant differences. Most of the patients were satisfied.

Conclusion

One‐stage arthroplasty or revision with exhaustive debridement, adequate dosage, and duration of sensitive antibiotics is safe and effective for patients who have seronegative infection of hip or knee joints.

Total Hip Arthroplasty for Posttraumatic Conditions

Posttraumatic arthritis accounts for a notable share of secondary osteoarthritis about the hip joint. Compared with total hip arthroplasty for primary osteoarthritis or inflammatory arthritis, total hip arthroplasty for posttraumatic arthritis offers greater technical challenges because of bone deformities and retained implants. Careful preoperative evaluation is necessary to prepare the approach, hardware removal strategy, and implants necessary to address bone deficiencies. Although arthroplasty is a highly successful procedure for posttraumatic arthritis, the results are less favorable than surgery for primary osteoarthritis. It is associated with a higher incidence of intraoperative and postoperative complications, including periprosthetic fractures, infection, instability, and decreased survivorship.

Diagnostic accuracy of serum inflammatory markers in late fracture-related infection: a systematic review and meta-analysis

AIMS

To assess the diagnostic value of C-reactive protein (CRP), leucocyte count (LC), and erythrocyte sedimentation rate (ESR) in late fracture-related infection (FRI).

MATERIALS AND METHODS

PubMed, Embase, and Cochrane databases were searched focusing on the diagnostic value of CRP, LC, and ESR in late FRI. Sensitivity and specificity combinations were extracted for each marker. Average estimates were obtained using bivariate mixed effects models.

RESULTS

A total of 8284 articles were identified but only six were suitable for inclusion. Sensitivity of CRP ranged from 60.0% to 100.0% and specificity from 34.3% to 85.7% in all publications considered. Five articles were pooled for meta-analysis, showing a sensitivity and specificity of 77.0% and 67.9%, respectively. For LC, this was 22.9% to 72.6%, and 73.5% to 85.7%, respectively, in five articles. Four articles were pooled for meta-analysis, resulting in a 51.7% sensitivity and 67.1% specificity. For ESR, sensitivity and specificity ranged from 37.1% to 100.0% and 59.0% to 85.0%, respectively, in five articles. Three articles were pooled in meta-analysis, showing a 45.1% sensitivity and 79.3% specificity. Four articles analyzed the value of combined inflammatory markers, reporting an increased diagnostic accuracy. These results could not be pooled due to heterogeneity.

CONCLUSION

The serum inflammatory markers CRP, LC, and ESR are insufficiently accurate to diagnose late FRI, but they may be used as a suggestive sign in its diagnosis.

Limited Predictive Value of Serum Inflammatory Markers for Diagnosing Fracture-Related Infections: results of a large retrospective multicenter cohort study

Introduction: Diagnosing Fracture-Related Infections (FRI) based on clinical symptoms alone can be challenging and additional diagnostic tools such as serum inflammatory markers are often utilized. The aims of this study were 1) to determine the individual diagnostic performance of three commonly used serum inflammatory markers: C-Reactive Protein (CRP), Leukocyte Count (LC) and Erythrocyte Sedimentation Rate (ESR), and 2) to determine the diagnostic performance of a combination of these markers, and the additional value of including clinical parameters predictive of FRI.

Methods: This cohort study included patients who presented with a suspected FRI at two participating level I academic trauma centers between February 1^st 2009 and December 31^st 2017. The parameters CRP, LC and ESR, determined at diagnostic work-up of the suspected FRI, were retrieved from hospital records. The gold standard for diagnosing or ruling out FRI was defined as: positive microbiology results of surgically obtained tissue samples, or absence of FRI at a clinical follow-up of at least six months. The diagnostic accuracy of the individual serum inflammatory markers was assessed. Analyses were done with both dichotomized values using hospital thresholds as well as with continuous values. Multivariable logistic regression analyses were performed to obtain the discriminative performance (Area Under the Receiver Operating Characteristic, AUROC) of (1) the combined inflammatory markers, and (2) the added value of these markers to clinical parameters.

Results: A total of 168 patients met the inclusion criteria and were included for analysis. CRP had a 38% sensitivity, 34% specificity, 42% positive predictive value (PPV) and 78% negative predictive value (NPV). For LC this was 39%, 74%, 46% and 67% and for ESR 62%, 64%, 45% and 76% respectively. The diagnostic accuracy was 52%, 61% and 80% respectively. The AUROC was 0.64 for CRP, 0.60 for LC and 0.58 for ESR. The AUROC of the combined inflammatory markers was 0.63. Serum inflammatory markers combined with clinical parameters resulted in AUROC of 0.66 as opposed to 0.62 for clinical parameters alone.

Conclusion: The added value of CRP, LC and ESR for diagnosing FRI is limited. Clinicians should be cautious when interpreting the results of these tests in patients with suspected FRI.