Diagnostic utility of open biopsy in patients with two culture-negative aspirations in the diagnostic work-up of periprosthetic joint infection

INTRODUCTION

Different approaches have been proposed for bacterial identification in patients with a suspected periprosthetic joint infection (PJI). If a one-stage procedure is considered, a higher rate of preoperative bacterial identification can be achieved if biopsy is included in the diagnostic work-up. The performance of open biopsy (OB) in the context of PJI has not been clearly determined yet. The purpose of this study was to determine the value of an OB added to two consecutive culture-negative joint aspirations during PJI workup.

MATERIALS AND METHODS

We retrospectively analyzed the OB data from a single institution. Patients under PJI work-up of the hip or knee with two culture-negative periprosthetic aspirations who underwent OB were included. Sensitivity and specificity were calculated using the musculoskeletal infection society (MSIS) criteria as gold standard. Patients undergoing urgent irrigation and debridement and patients with history of surgery to the affected joint in the prior 6 weeks were excluded.

RESULTS

126 patients were included in this study. 62 (49.2%) patients had prior revisions, 48 of them due to PJI. The sensitivity and specificity of OB was 69.4% and 89.1%, respectively. The OB procedure led to the identification of the causative germ in 50 out of 126 (40%) cases so they could undergo one-stage (septic) exchange.

CONCLUSION

The OB is a valuable resource if preoperative synovial fluid cultures are negative, a high suspicion of infection persists and a one-stage procedure is preferred. It intends bacteria identification and allows surgeons to evaluate prosthetic complications for further surgical procedures.

Results at 10-24 years after single-stage revision arthroplasty of infected total hip arthroplasty in patients under 45 years of age

INTRODUCTION

The management of periprosthetic joint infection (PJI) of the hip is a challenging procedure. One-stage exchange is carried out in specialist centres with comparable infection free survival rates. However, there is a paucity of long-term results of this approach in young patients.

METHODS

All patients undergoing one-stage exchange due to PJI with a known causative organism ⩽45 years of age with a minimum of 10-year follow-up (mean 15 years; range 10-24 years) were enrolled in this retrospective study. Patients older than 45 years of age or patients with a two-stage procedure were excluded from the study. The primary outcome measure was failure rate with special focus on reinfection at latest follow-up. Failure was defined as revision surgery for infection. Furthermore, functional outcome using the Harris Hip Score was determined initially and at latest follow-up. 26 patients fulfilled the inclusion criteria and were available for final follow-up.

RESULTS

The study cohort consists of 16 male and 10 female patients with a mean age of 36.8 years (range 20-45 years) and a mean BMI of 29.8 kg/m2 (range 20.7-40.6 kg/m2). Prior to the single-stage procedure, the patients underwent an average of 3.1 previous surgical interventions (range 1-9). The mean hospital stay after septic revision was 19.7 days (11-33 days). Most infections were caused by Staphylococcus epidermidis (n = 8, 30.8%), followed by Staph. aureus (n = 7, 26.9%) and Propionibacterium acnes (n = 6, 23.1%). At latest follow-up, the overall survival rate was 76.9 %, while infection control could be achieved in 96.2%. At final examination, the mean Harris Hip Score improved from 46.2 to 78.9 (range 18.0-99; SD, 22.6).

CONCLUSIONS

Single-stage revision surgery for the management of PJI in patients ⩽45 years is a successful treatment option with high infection control, even after long-term follow-up.

Diagnosis and management of the infected total knee replacement: a practical surgical guide

Purpose

Prosthetic joint infection (PJI) after total knee arthroplasty (TKA) is a significant burden in health care. Diagnosis and proper management are challenging. A standardised procedure for the diagnostic workup and surgical management provides clear benefits in outcome.

Methods

Several diagnostic protocols and definitions for PJI were established in recent years. Proper PJI diagnosis remains critical for success and for choosing the optimal treatment option. A distinct workup of diagnostic steps, the evaluation of the results in a multidisciplinary setup and the meticulous surgical management of the infection are the key factors of successful treatment.

Results

The management of PJI after TKA consists of early revision with debridement and implant retention (DAIR) in early cases or staged revision in late infections beyond 30 days postoperative or after onset of acute symptoms. The revision is performed as a two-stage procedure with the use of a fixed or mobile antibiotic spacer, or in selected cases as a single-stage operation with the use of local and systemic antibiotic treatment.

Conclusions

This paper reflects the opinion of two revision surgeons who follow the same protocol for diagnosis and treatment of PJI after TKA, highlighting the key steps in diagnosis and management.

Level of evidence

Expert’s opinion

What Is the Dislocation and Revision Rate of Dual-mobility Cups Used in Complex Revision THAs?

BACKGROUND

Dual-mobility cups have been shown to reduce the dislocation risk after THA. Although dual-mobility cups can be a useful strategy to mitigate against recurrent dislocation after revision surgery, few clinical studies have focused on the results of complex revision THAs with extensive bone and soft-tissue loss or in patients who have undergone more than one previous surgical procedure.

QUESTIONS/PURPOSES

(1) What is the survival free from revision for dislocation of dual-mobility cups used in complex revision THAs? (2) What is the survival free from any dislocation?

METHODS

Between January 1, 2009 and December 31, 2013, 327 patients underwent a complex revision THA that included an acetabular revision, defined as preexisting massive bone loss in the acetabulum (at least Paprosky Type 2B) and/or proximal femur (at least Paprosky Type 3), substantial gluteal soft-tissue involvement, at least two previous surgical procedures or a one-stage septic revision, or history of dislocation. All 327 complex revision patients received a dual-mobility cup. Of those, 34% (111) were lost to follow-up before 5 years and were not known to have reached a study endpoint (revision for dislocation, and any dislocation) before then, leaving 216 patients for analysis. For patients with bilateral hip surgeries only the first operated hip was included for analysis. The median (range) follow-up duration was 69 months (60 to 110). The primary endpoint was dislocation or re-revision for dislocation. Fifty-six percent (120 of 216) of the patients were women and 44% (96 of 216) were men. The mean age of the patients was 69 ± 9 years. The patients underwent a median of four surgical procedures (1 to 4) before the index procedure (the revision evaluated in this study). A survival analysis was performed using the Kaplan-Meier method; any dislocation or revision for dislocation was determined as the endpoint.

RESULTS

The dislocation-free survival rates were 96% (95% confidence interval 92 to 98) at 5 years and 82% (95% CI 72 to 89) at 9 years. The overall dislocation rate was 11% (24 of 216 patients) at the final follow-up interval. Survival free of revision for dislocation was 99% (95% CI 96 to 100) at 5 years and 85% (95% CI 75 to 92) at 9 years.

CONCLUSIONS

Dual-mobility cups used in complex revision THA in this series had a higher rate of dislocation and revision than expected, based on earlier studies of dislocations of these components. Although we believe dual-mobility cups are still the first choice of implant if the patient has instability, these cups should be used cautiously if severe bone loss or soft-tissue involvement is present.

LEVEL OF EVIDENCE

Level III, therapeutic study.

How reliable is the next generation of multiplex-PCR for diagnosing prosthetic joint infection compared to the MSIS criteria? Still missing the ideal test

INTRODUCTION

Identification of the pathogen in case of a periprosthetic joint infection (PJI) remains 1 of the greatest challenges in septic surgery. Rapid germ identification enables timely, specific, antimicrobial therapy. The first multiplex PCR (polymerase chain reaction) generation (Unyvero-i60) enables germ detection within 5 hours with a sensitivity of 78.8% and a specificity of 100%. The aim of this study is to investigate the performance of the new generation of cartridges (Unyvero-ITI) of multiplex PCR in the case of a PJI.

METHODS

In a prospective study, intraoperatively aspirated synovial fluid from 97 patients with aseptic or septic hip or knee revision surgery (49 aseptic, 48 septic) was examined with the multiplex PCR system (Unyvero-ITI) and the results were compared with the MSIS criteria. In addition, the time until the microbiological result was obtained in the event of a germ detection was documented.

RESULTS

The multiplex PCR showed a germ detection with a sensitivity of 85.1% and a specificity of 98.0%. In 7 cases a false negative result was found and in one patient a false positive result was found. The general accuracy of this test procedure was 91.8%. The detection of germs was carried out within 5 hours with the multiplex PCR compared to 4.9 days in conventional microbiological diagnostics.

CONCLUSIONS

The new generation of multiplex-PCR was able to improve germ detection. The possibility of prompt detection of germs offers the option of faster, targeted antimicrobial therapy. This diagnostic tool offers significant advantages, particularly in the context of an acute periprosthetic infection.

Revision Arthroplasty with Total Femur Replacement for the Management of Complex Post-traumatic Bone Defect in a Patient with Dwarfism

Dwarfism leads to an early onset of osteoarthritis of the joints of the lower limb. Due to bone deformities, arthroplasty is challenging. The incidence of implant-associated complications is higher compared to the normal population and often ends up with multiple revision arthroplasties. We report the first case in the literature of a 48-year-old patient with dwarfism who required implantation of a custom-made total femoral replacement due to aseptic stem loosening and a concomitant valgus gonarthrosis.

Are Metaphyseal Sleeves a Viable Option to Treat Bone Defect during Revision Total Knee Arthroplasty? A Systematic Review

Purpose  Bone loss is a challenging problem during revision total knee arthroplasty (TKA). Several studies have been published on the use of metaphyseal sleeves during revision TKA. Therefore, the aim of this systematic review was to summarize the clinical and radiographic outcomes of the use of metaphyseal sleeves in the setting of revision TKA.

Methods  A comprehensive search of PubMed, MEDLINE, CINAHL, Cochrane, EMBASE, and Google Scholar was performed, covering the period between January 1, 2000, and August 12, 2017. Various combinations of the following key words were used: “metaphyseal,” “sleeves,” “knee,” and “revision.” A total of 10 studies were included in the present systematic review.

Results  A total of 904 patients with 928 implants were recorded with a mean age of 69 years. They were evaluated at a mean follow-up of 45 months. Overall 1,413 sleeves, 888 in the tibia and 525 in the femur, were implanted. There were 36 septic re-revisions of the prosthetic components (4%). Five sleeves were found loose during septic re-revision; therefore, the rate of septic loosening of the sleeves was 0.35%. An aseptic re-revision of the prosthetic components was performed 27 times (3%). Ten sleeves were found loose during aseptic re-revision; therefore, the rate of aseptic loosening of the sleeves was 0.7%. Intraoperative fractures occurred 44 times (3.1%). Finally, clinical outcome was improved at final follow-up.

Conclusion  Metaphyseal sleeves demonstrate high radiographic signs of osteointegration, low septic loosening rate, low intraoperative fractures rate, and a good-to-excellent clinical outcome. Hence, they are a valid option to treat large metaphyseal bone defect during revision TKA.

Level of Evidence  This is a systematic review of level IV studies.

Interprosthetic Femoral Sleeves in Revision Arthroplasty: A 20-Year Experience

BACKGROUND

Interprosthetic femoral fractures in patients with ipsilateral stemmed total hip arthroplasty (THA) and total knee arthroplasty (TKA) can be technically demanding to treat surgically. Nonunion and implant failure are among the main complications following fixation of interprosthetic femoral (IF) fractures. Total femoral arthroplasty (TFA) is associated with a high incidence of infection and instability. IF sleeves have been designed to avoid the disadvantages of these techniques and to provide a stable construct. The aim of this study was to present the results with this device from a single center.

METHODS

We reviewed 26 patients who underwent revision arthroplasty procedures, using custom-made cemented IF sleeves between 1997 and December 2017 in our institution. Two-part sleeves were used in 18 patients and one-part sleeves in 8 patients. The most common indication was an IF fracture (18 patients). Patients were monitored for postoperative complications, implant failure, and re-revision. The minimum follow-up of the survivors with nonrevised sleeves was 12 months.

RESULTS

Twenty-three patients were included for the final analysis. The mean survivorship of the IF sleeve was 4.6 years at latest follow-up (mean 48.5 months; range 12 to 156). The overall rate of complications was 47.8%. The rate of mechanical failure was 21.7%. Late infections occurred in 3 patients (13%). At the latest follow-up, the mean Harris Hip Score was 69.9 points (range 39 to 94), and the mean functional Knee Society Score was 42.5 points (range 0 to 90), with average knee flexion of 95° (range 90° to 100°).

CONCLUSION

The IF sleeve is a valid technique for the management of selected patients with IF fractures, particularly when a stable fracture fixation is not possible. Hip instability is not a concern, and functional improvement is achievable. Careful planning is required preoperatively to avoid mechanical failure.

Risk Factors for Failure After 1-Stage Exchange Total Knee Arthroplasty in the Management of Periprosthetic Joint Infection

BACKGROUND

One-stage exchange arthroplasty in the management of periprosthetic joint infection was introduced at our institution. The purpose of this study was to analyze the risk factors of failure after periprosthetic joint infection following total knee arthroplasty treated with 1-stage exchange.

METHODS

Ninety-one patients who underwent failed treatment following 1-stage exchange total knee arthroplasty due to periprosthetic joint infection from January 2008 to December 2017 were included. From the same period, we randomly selected a 1:1 matched control group without a subsequent revision surgical procedure. Bivariate analyses, including preoperative, intraoperative, and postoperative factors, as well as logistic regression, were performed to identify risk factors for failure.

RESULTS

Bivariate analysis yielded 10 predictors (variables with significance at p < 0.05) for failure involving re-revision for any reason and 11 predictors for failure involving re-revision for reinfection. The binary logistic regression model revealed the following risk factors for re-revision for any reason: history of a 1-stage exchange for infection (odds ratio [OR], 26.706 [95% confidence interval (CI), 5.770 to 123.606]; p < 0.001), history of a 2-stage exchange (OR, 3.948 [95% CI, 1.869 to 8.339]; p < 0.001), and isolation of enterococci (OR, 16.925 [95% CI, 2.033 to 140.872]; p = 0.009). The risk factors for reinfection in the binary logistic regression analysis were history of 1-stage or 2-stage exchange arthroplasty, isolation of enterococci, and isolation of streptococci (OR, 6.025 [95% CI, 1.470 to 24.701]; p = 0.013).

CONCLUSIONS

We identified several risk factors of failure after 1-stage exchange arthroplasty for periprosthetic joint infection, most of which were not related to the patient comorbidities. Among them, previous exchange due to periprosthetic joint infection and the isolation of Enterococcus or Streptococcus species were associated with a higher risk of failure. Besides a multidisciplinary approach, being aware of the identified risk factors when evaluating patients with periprosthetic joint infection could lead to better outcomes.

LEVEL OF EVIDENCE

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

Ten-Year Results Following One-Stage Septic Hip Exchange in the Management of Periprosthetic Joint Infection

BACKGROUND

Although 2-stage revision is still considered the gold standard for surgical management of periprosthetic joint infection (PJI), 1-stage revision has been reported to be as effective. Long-term reports for 1-stage revision in hip PJIs are lacking.

METHODS

We reviewed our 10-11 years of results of 85 patients who underwent 1-stage exchange of the hip with an antibiotic-loaded bone cemented prosthesis due to PJI to determine the following: (1) What is the infection-free survival? (2) What is the overall survival? and (3) What are the long-term clinical outcomes? All 1-stage revision total hip arthroplasties (THAs) for infection between January 2006 and December 2007, with a minimum 10-year follow-up (range 10-11), were included in this retrospective cohort. Patients from another country or patients who were unable to participate were excluded. Eighty-five patients with a hip PJI were available at the last follow-up. Thirty-seven patients died during the 10-year study. Harris Hip Scores were recorded before the surgery and at last follow-up. Failures are reported as infection-related or aseptic.

RESULTS

The 10-year infection-free survival was 94% and the surgery-free survival was 75.9%. The Harris Hip Scores improved from 43 (range 3-91) to 75 (range 10-91) (P < .001). The main indication for re-revision after 1-stage exchange was instability (10/20 patients).

CONCLUSION

One-stage exchange of the hip for PJI is a reliable treatment option with high rate of infection control and long-lasting favorable outcomes.

The role of alpha defensin in prosthetic joint infection (PJI) diagnosis: a literature review

Prosthetic joint infection (PJI) management is not standardized worldwide and the outcome is frequently unsatisfactory.

More and more arthroplasties are now being performed. An increasing number of highly virulent and antibiotic-resistant bacteria and an ageing population of patients presenting with many comorbidities make it necessary to focus on this important topic.

Diagnosis of PJI remains challenging because the clinical signs and symptoms and elevation of systemic biomarkers (C-reactive protein, erythrocyte sedimentation rate) may be unclear.

In the last few years, the clinical research has focused on synovial fluid biomarkers as a possible breakthrough in the complex scenario of PJI diagnosis.

Synovial biomarkers have shown encouraging results and they should be used as diagnostic adjuncts to synovial white cell count and culture bacteriology. Synovial leukocyte esterase (LE) and synovial C-reactive protein (CRP) have been evaluated as good screening measures; however, the most promising synovial fluid biomarker in terms of sensitivity and specificity for PJI seems to be alpha defensin (AD).

The laboratory-based alpha defensin enzyme-linked immunosorbent assay (ELISA) test demonstrated the highest ever reported accuracy for PJI diagnosis. However, an alpha defensin lateral flow test could have its place in ruling in a suspected PJI intraoperatively because of its high specificity and rapid results.

Cite this article: EFORT Open Rev 2019;4:10-13. DOI: 10.1302/2058-5241.4.180029

Patient-reported outcome measures (PROMs) in patients undergoing patellofemoral arthroplasty and total knee replacement: A comparative study

BACKGROUND

Incongruity in the evaluation of outcomes between patients and surgeons has led to an increasing utilization of patient-reported outcome measures (PROMs) as an evaluation method of outcome.

OBJECTIVE

The aim of this study was to compare Oxford Knee Score (OKS), KOOS-PS and Kujala Score results in patients who received either PFA or TKA with and without patella resurfacing in the tretament of knee osteoarthritis.

METHODS

A total of 50 patients (PFA = 19 patients; TKA with patelloplasty = 15 patients; TKA with patellar resurfacing = 16 patients) undergone surgery between 2011 and 2014 and were included for final analysis.

RESULTS

No statistical significance was found for OKS, KOOS-PS and Kujala scores between the three groups. However, although patients with PFA experienced higher levels of pain.

CONCLUSIONS

According to our results, it is essential to discuss the treatment options and quality of life expectations with the patient prior joint replacement surgery in order to reduce patient dissatisfaction.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

The Merete BioBall system in hip revision surgery: A systematic review

BACKGROUND

Modular hip arthroplasty is widely recognized in hip surgery; nevertheless, despite advances in prosthetic design, the incidence of hip revision surgery is increasing. In these procedures, a modular adapter that engages the femoral stem and the modular femoral head could be useful in order to protect the neck-head junction and restore preoperative biomechanics and soft tissue tension when the femoral or acetabular component should be retained. The Merete™ BioBall™ system (Merete Medical, Berlin, Germany) could fill this need. However the literature regarding this device is sparse, therefore we performed a systematic review to analyze: the indications for its use and clinical results and the causes of second revision and survival in hip revision surgery, mainly focus in complications of its use.

MATERIALS AND METHODS

Databases including PubMed and Google Scholar were searched for English-language articles published between 01/01/1999 and 01/04/2017, using search terms related to the system Merete™ BioBall™. Studies that reported the clinical use of the Merete™ BioBall™ system in hip revision surgery were selected. Data related to the indications, characteristics of the implant, clinical results, causes of second revision and survival were gathered.

RESULTS

A total of 14 studies with a level IV evidence were analyzed. Information related to the implant was provided in 194 cases. Isolated acetabular revision was the main indication of implant use (139/194 [71.6%]). The most common combination used was the standard implant (69/110 specified [59.4%]), 3XL length (28/107 specified [26.2%]) with 32mm metal head (58/187 specified [31%]). After a follow-up ranging from 2 to 97 months, there were 16 complications, thirteen (81,2%) were revised, including one neck fracture of the stem (6.25%), two ceramic head fractures (12,5%) and six recurrent dislocations (37,5%). Implant survival was 92.8% at 52.5 months of follow-up in the longest published series. Clinical and functional results were provided in a heterogeneous way.

CONCLUSIONS

There is insufficient evidence to recommend for or contraindicate the use of the Merete™ BioBall™ system. The Isolated acetabular revision was the main indication of implant use. When dislocation is the indication of its use the rate of second revision is high. Some important complications possibly related with the implant design have been reported but as isolated cases. The neck adapter failure or corrosion phenomena have not been reported. Further prospective and controlled trials are needed to assess the use of this type of implant and its survival.

LEVEL OF EVIDENCE

Level III systematic review of case series.

How Reliable Is the Cell Count Analysis in the Diagnosis of Prosthetic Joint Infection?

BACKGROUND

Synovial analysis of joint aspirates is a key diagnostic tool; all major diagnostic algorithms include cell count (CC) and polymorphonuclear percentage (PMN%) as important criteria to make the diagnosis. In this context, we conducted this study to analyze the overall accuracy of CC and PMN%.

METHODS

A single-center retrospective analysis was performed with clinical data of included patients, with a total of 524 preoperative joint aspirations (255 hips, 269 knees). From the aspirated synovial fluid, we tested the leukocyte esterase activity, leukocyte CC, and PMN%, and sent specimens for aerobic and anaerobic bacterial culture. Depending on the clinical results in accordance with the Musculoskeletal Infection Society criteria for prosthetic joint infection (PJI), 203 patients were then admitted for aseptic revision and 134 patients for septic exchange.

RESULTS

In 337 cases (64.3% of the study patients), it was possible to measure the CC. The best cutoff level for PJI of all study patients was 2582 leukocytes/μL (sensitivity [SE] 80.6%, specificity [SP] 85.2%) and a PMN% of 66.1% (SE 80.6%, SP 83.3%). The chosen cutoff levels for PJI of total knee and total hip arthroplasty were 1630 leukocytes/μL (SE 83.6%, SP 82.2%) and a PMN% of 60.5% (SE 80.3%, SP 77.1%) and 3063 leukocytes/μL (SE 78.1%, SP 80.0%) and a PMN% of 66.1% (SE 82.2%, SP 82.4%), respectively.

CONCLUSIONS

CC and PMN% are sensitive methods for diagnosing PJI of total hip and total knee arthroplasty. However, there are differences in cutoff levels between knees and hips. International guidelines and diagnostic criteria need revisions in terms of these parameters.

Posterolateral overhang affects patient quality of life after total knee arthroplasty

PURPOSE

To investigate the appropriate mediolateral placement of symmetrical tibial components and the amount of overhang expected from the posterolateral of tibial components implanted to give ideal coverage and the subsequent incidence of residual knee pain and reduction in functional capacity.

METHOD

A retrospective evaluation was made of 146 consecutive total knee arthroplasties. The posterolateral overhang, rotational alignment and coverage of the tibial component were measured on a post-operative CT scan and the effect of posterolateral overhang on clinical outcomes was analysed 3 years after surgery.

RESULTS

Complaints of local pain in the posterolateral corner were determined in 76 (52.1%) patients. At the Posterolateral corner, overhang was determined in 111 (76%) patients, in the cortical border in 11 (7.6%) patients and underhang in 24 (16.4%) patients. In 71 (48.6%) patients, pain was determined together with oversize and in the evaluation of the overhang of the tibial component in the posterolateral region and the rotation status, there was determined to be overhang in 75 (96.2%) patients where the tibial component was placed in ideal rotation, in 25 (100%) where placement was in external rotation and in 11 (25.6%) where placement was in internal rotation. The mean KSS, KSS-F and WOMAC-P scores were 83.9 ± 6.3, 83.3 ± 7.8 and 4.6 ± 2.9, respectively, in those with posterolateral overhang of the tibial component .The mean KSS, KSS-F and WOMAC-P scores were 86.6 ± 8.4, 89.5 ± 7.8 and 2.8 ± 2.1, respectively, in those with no overhang and the difference was determined to be statistically significant. The amount of overhang was determined as mean 3.6 ± 2.0 mm in those with posterolateral pain and 0.02 ± 3.4 mm in those without pain and the difference was statistically significant.

CONCLUSIONS

This study demonstrated that overhang in the posterolateral region is surprisingly high and negatively affects the clinical results following TKA, thereby presenting a danger to the success of TKA. The risk of posterolateral oversizing can increase with placement of the tibial component in external rotation.

The Accuracy of the Alpha Defensin Lateral Flow Device for Diagnosis of Periprosthetic Joint Infection: Comparison with a Gold Standard

BACKGROUND

Alpha defensin is a new biomarker that has been shown to have a very high accuracy to rule out periprosthetic joint infection. Recently, a new rapid lateral flow version of the alpha defensin test was developed and introduced to detect high levels of alpha defensin in synovial fluid quickly and with ease. We conducted a single-center prospective clinical study to compare the results of the Synovasure Alpha Defensin Test with those of the Musculoskeletal Infection Society (MSIS) criteria, which are considered to be the gold standard for diagnosing periprosthetic joint infection.

METHODS

A total of 223 consecutive patients with pain after total hip arthroplasty or total knee arthroplasty were enrolled into the study. In all patients, blood C-reactive protein was measured and joint aspirations were performed. From the synovial fluid, a leukocyte cell count with granulocyte percentage, microbiology cultures, and leukocyte esterase tests were carried out according to the recommendation of the MSIS for diagnosing periprosthetic joint infection. Concurrently, the Synovasure Alpha Defensin Test with a lateral flow device was performed from the aspirate. In the final clinical and statistical evaluation, 191 subjects with 195 joint aspirations (96 hips and 99 knees) were included. According to the MSIS criteria, there were 119 joints with an aseptic revision and 76 joints with periprosthetic joint infection.

RESULTS

After statistical analysis, the overall sensitivity of the Synovasure Alpha Defensin Test was 92.1% (95% confidence interval [CI], 83.6% to 97.1%), the specificity was 100% (95% CI, 97.0% to 100%), the positive predictive value was 100% (95% CI, 94.9% to 100%), and the negative predictive value was 95.2% (95% CI, 89.9% to 98.2%). The overall accuracy of the Synovasure test was 96.9% (95% CI, 93.4% to 98.9%), 189 of 195 cases.

CONCLUSIONS

Our results suggest that the Synovasure periprosthetic joint infection test has a very high accuracy in diagnosing periprosthetic infections after total hip arthroplasty or total knee arthroplasty. Although the Synovasure Alpha Defensin Test does not provide information on the identity of the infectious pathogen, the test does have an important role in recognizing periprosthetic joint infection early and enables surgeons to start proper therapy without delay.

LEVEL OF EVIDENCE

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

Are Trabecular Metal Cones a Valid Option to Treat Metaphyseal Bone Defects in Complex Primary and Revision Knee Arthroplasty?

Purpose  Metaphyseal bone defects are a challenge in complex primary and revision total knee arthroplasty (TKA). Recently, several studies have been published with promising results about the use of Trabecular Metal (TM) cones to address bone defects. The aim of this study is to review the literature to assess the efficacy of TM cones to address metaphyseal bone loss.

Methods  A comprehensive search was performed on PubMed, Medline, CINAHL, Cochrane, Embase, and Google Scholar databases using various combinations of the following keywords: “metaphyseal,” “cones,” “tantalum,” “knee,” and “revision.” Only papers reporting clinical data about the use of trabecular metal cones were included in the analysis. In vitro studies, case reports, surgical technique, or other studies where it was not possible to collect clinical data were excluded. Patients characteristics, details of the surgical procedures, outcome, and complications were collected from each included study.

Results  No controlled studies were available in the literature and all the papers were case series. In 16 studies included, the records of 442 patients with 447 implants and 523 TM cones were reported. The mean follow-up was 42 months (range: 5–105) for 360 procedures. Among 437 procedures, 30.4% were septic revisions. The Anderson Orthopaedic Research Institute (AORI) classification was available for 352 defects: 13 type 1, 69 type 2A, 115 type 2B, and 155 type 3. To manage these 352 defects, 360 TM cones were implanted. Intraoperative fractures occurred 13 times (10 femoral/3 tibial), 6 required surgical fixation. The overall infection rate was 7.38%, and the infection rate for the aseptic procedures was 0.99%. An aseptic exchange was performed 13 times, among these procedures two TM cones were loose. Signs of loosening were found just in 1.3% of the 523 TM cones implanted (5 femoral/2 tibial) during 447 procedures.

Conclusion  The TM cones are an effective solution to manage bone defects in complex primary and revision TKA at intermediate follow-up. The incidence of complications was low; however, the femoral metaphysis proved to be more susceptible to complications.

Level of Evidence  Level IV, systematic review of level IV studies.

Severe metallosis and elevated chromium in serum following implantation of the joint unloading implant system

In recent years, the minimally invasive joint-preserving implant system has been developed. The main goal of this device is to unload the medial knee compartment without affecting the lateral compartment. The current authors describe a severe metallosis and elevated chromium in serum following implantation of the joint unloading implant system of a 50-year-old male patient, presented to our hospital 3 years after implantation of a KineSpring System into his left knee due to unicompartmental medial osteoarthritis (OA) in an external hospital. Radiographs showed radiological signs for loosening of the screws in the tibia and a progressive OA on the medial and patellofemoral compartments. Revision surgery with removing of the unloading device was performed at our hospital. The intraoperative situs presented a severe metallosis around the device. Five days after revision surgery, the laboratory parameters revealed an elevated value for chromium in serum, while nickel and cobalt values in serum were normal. Reliable clinical data about the long-term results of the KineSpring System is desperately needed. Further studies are warranted to work out the effects of cobalt and chromium levels and further side effects following the implantation of the extra-articular absorber system.

Are There Benefits In Early Diagnosis Of Prosthetic Joint Infection With Multiplex Polymerase Chain Reaction?

Purpose Identification of bacteria and susceptibility are fundamental in periprosthetic joint infection (PJI). Especially in the case of systemic inflammatory response syndrome (SIRS) rapid detection of pathogens is essential for proper therapy. Bacterial cultures are time consuming. The polymerase chain reaction (PCR) is a non-culture molecular method and is able to rapidly identify pathogens and their resistance genes. Multiplex PCR (mPCR) can amplify several different DNA sequences simultaneously. The aim of this study was to show the value of mPCR for early diagnosis of PJI.

Methods 60 patients undergoing total hip or knee revisions were recruited in this prospective single-centre-study. Three groups were created: 26 patients with aseptic loosening (negative control), 26 patients with chronic PJI, and 8 patients with acute PJI/SIRS. We compared the results of joint aspirates obtained intraoperatively investigated by mPCR with the microbiology results of tissue specimens.

Results The overall sensitivity of mPCR was 78.8% (95% CI, 61.1 - 91.0%), the specificity was 100% (95% CI, 87.2 - 100%), the negative predictive value was 79.4% (95% CI, 62.1 - 91.3%), the positive predictive value was 100% (95% CI, 86.8 - 100%), and the overall accuracy was 88.3% (95% CI, 77.4 - 95.2%). The overall accuracy in acute infections/SIRS (87.5%) was greater than in late chronic PJI (76.9%). In PJI the mPCR was able to provide the results within 5 hours whereas the mean time for cultures was 6.4 days.

Conclusions Multiplex PCR is a reliable diagnostic tool in PJI management, especially in acute cases complicated with SIRS. Early diagnosis within several hours is possible, targeted antibiotic treatment can be started promptly.

One-stage Exchange Arthroplasty for Periprosthetic Hip and Knee Joint Infections

Background:

Periprosthetic joint infection (PJI) is a devastating complication of joint replacement surgery. In an aging population of the developed world, the increasing numbers of hip and knee replacements will inevitably lead to increasing incidence of PJI, carrying with (it) significant patient morbidity and cost to the health care system. Two-stage exchange arthroplasty is currently the gold standard but it is associated with multiple operations, prolonged hospitalization and impaired functionality. One-stage exchange arthroplasty is similar to the two-stage procedure but the interval between removal of the prosthesis and reimplantation of a new one is only a few minutes. It has the theoretical benefits of a single anesthetic, shorter hospitalization, less cost and improved function.

Methods:

We reviewed the current literature regarding the outcomes of one-stage exchange arthroplasties focusing on re-infection rates and functional outcomes.

Results:

Current themes around the one-stage exchange procedure include the indications for the procedure, definition of re-infection, surgical techniques used to provide fixation and differences in approach for hip and knee replacements.

Conclusion:

The current literature on one-stage exchange procedure is promising, with comparable results to two-stage revisions for hips and knees in selected patients. However, there is a great need for a large multi-centred randomized control trial, focusing on re-infection rates and functional scores postoperatively, to provide concrete guidelines in managing this complex condition.

Can Good Infection Control Be Obtained in One-stage Exchange of the Infected TKA to a Rotating Hinge Design? 10-year Results

BACKGROUND

Prosthetic joint infection (PJI) occurs in 1% to 2% of total knee arthroplasties (TKAs). Although two-stage exchange is the preferred management method of patients with chronic PJI in TKA in North America, one-stage exchange is an alternative treatment method, but long-term studies of this approach have not been conducted.

QUESTIONS/PURPOSES

We reviewed our minimum 9-year results of 70 patients who underwent one-stage exchange arthroplasty with a rotating hinge design to determine: (1) What was the proportion of patients free of infection? (2) What was the patient rate of survival free of any reoperation? (3) What were the clinical outcomes as measured by Hospital for Special Surgery scores? (4) What proportion of patients developed radiographic evidence of loosening?

METHODS

All one-stage revision TKAs for infection between January 1 and December 31, 2002, with a minimum 9-year followup (mean, 10 years; range, 9-11 years), in which patients had been seen within the last 1 year, were included in this retrospective review. During that period, 11 patients with infected TKAs were treated with other approaches (including two-stage approaches in eight); the general indication for one-stage revision was the diagnosis of PJI with a known causative organism. Exclusion criteria were culture-negative preoperative aspiration, known allergy to local antibiotics or bone cement, or cases in which radical débridement was impossible as a result of the involvement of important anatomical structures. Eighty-one patients with PJI were seen during this period; 70 underwent one-stage exchange using our strict protocol and were reimplanted with a rotating hinge TKA. Eleven patients (15.7%) were lost to followup. Hospital for Special Surgery scores were recorded and all radiographs were evaluated for prosthetic loosening. Failure was defined as revision surgery for infection or any other cause.

RESULTS

Our 10-year infection-free survival was 93% (mean, 4.1; 95% confidence interval [CI], 89%-96%; p < 0.007); and the patient 10-year survival rate free of revision for other causes was 91% (mean, 5.2; 95% CI, 86%-95%; p < 0.002). Mean Hospital for Special Surgery knee score at last followup was 69.6 (± 22.5 SD; range, 22-100) and the mean improvement in Hospital for Special Surgery knee score from preoperative to most recent followup was 35 (± 24.2 SD; range, 13-99). Evidence of radiographic loosening was seen in 11 patients at last followup, whereby in six patients, there was need for revision surgery.

CONCLUSIONS

Our study results showed an overall infection control rate of 93% and good clinical results using our one-stage approach, which combines aggressive débridement of the collateral ligaments and posterior capsule with a rotating hinge implant. These results are comparable with two-stage techniques at a followup of 10 years; further research into one-stage exchange techniques for PJI in TKA appears warranted.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

One-stage exchange: it all began here

Based on the first implementation of mixing antibiotics into bone cement in the 1970s, the Endo-Klinik has used one stage exchange for prosthetic joint infection (PJI) in over 85% of cases. Looking carefully at current literature and guidelines for PJI treatment, there is no clear evidence that a two stage procedure has a higher success rate than a one-stage approach. A cemented one-stage exchange potentially offers certain advantages, mainly based on the need for only one operative procedure, reduced antibiotics and hospitalisation time. In order to fulfill a one-stage approach, there are obligatory pre-, peri- and post-operative details that need to be meticulously respected, and are described in detail. Essential pre-operative diagnostic testing is based on the joint aspiration with an exact identification of any bacteria. The presence of a positive bacterial culture and respective antibiogram are essential, to specify the antibiotics to be loaded to the bone cement, which allows a high local antibiotic elution directly at the surgical side. A specific antibiotic treatment plan is generated by a microbiologist. The surgical success relies on the complete removal of all pre-existing hardware, including cement and restrictors and an aggressive and complete debridement of any infected soft tissues and bone material. Post-operative systemic antibiotic administration is usually completed after only ten to 14 days.

Intrapelvic dislocation of a femoral trial head during primary total hip arthroplasty requiring laparotomy for retrieval

Background and Purpose:

Total hip arthroplasty (THA) is a safe and reliable surgical procedure. However, THA also has intra- and postoperative complications. A dreaded and frustrating intraoperative complication during total hip arthroplasty is dislocation of the femoral trial head from the neck into the pelvis.

Methods:

Here, we report on the case of a 71-year old female patient with osteoarthritis of the left hip. Total hip arthroplasty was performed in a lateral position through a standard posterior approach. During intraoperative trial reduction, the femoral trial head dissociated from the taper and dislocated into the psoas compartment. Several unsuccessful attempts, including an additional ventral approach, were made to immediately retrieve the femoral trial head.

Results and interpretation:

Postoperative a Computerized Tomography (CT) was performed to locate the trial head, a secondary explorative laparotomy was undertaken to retrieve it. The retrieval of the femoral trial head should be performed in a planned second surgical procedure to avoid possible complications during the manipulation necessary for retrieval.

One stage conversion of an infected fused knee to total knee replacement - a surgical challenge

Background and Purpose:

Two-stage revision arthroplasty is a common technique for the treatment of infected total knee replacement. Few reports have addressed the conversion of a fused knee into a total knee replacement. However, there is no case reported of converting an infected fused knee into a hinge knee using a one-stage procedure.

Methods:

We report on a 51-year old male patient with an infected fused knee after multiple surgeries.

Results and Interpretation:

A one-stage conversion of septic fused knee into total knee arthroplasty by a rotational hinge prosthesis was performed. The case highlights that with profound preoperative assessment, meticulous surgical technique, combined antibiotic treatment and the right implant, one-stage revision in a surgical challenge may have a role as a treatment option with good functional outcome.

Traumatic Stem Fractures in Short Stem THA-A Rare Case Series

Adequate trauma of a well-fixed total hip prosthesis might cause relevant osseous injuries. Concomitant occult fractures of the implant itself are very rare. We report on two patients admitted to our institution and who were previously treated with similar types of short-stem total hip arthroplasty (THA). Both were unable to walk after an adequate trauma, although the initial admitting hospital misdiagnosed the exact diagnosis. Detailed reexamination later revealed a prosthetic neck fracture of the cement-free stem. Both patients were treated with a stem revision. In THA patient, special attention should be drawn to the implants after relevant trauma. A single examination shortly after trauma seems to be insufficient to diagnose implant-related injuries. A secondary follow-up several weeks after trauma, including at least X-rays, has to be recommended.

[Results of primary median nerve repair at the wrist: report of 24 cases]

INTRODUCTION

Nerve injuries of the upper limb can cause serious damage: primary repair has improved the results but the prognosis for recovery remains uncertain. We present the results of primary repair of 24 median nerve injuries at the level of the wrist.

MATERIALS AND METHODS

Between 1990-1998, we repaired 57 median nerve injuries at the wrist. Only 24 patients were included in this retrospective study. The average age of the patients was 25 years (range: 18-60 years). Seventeen patients were men and seven were women. All the patients were operated within 12 h after the accident. In all the cases, epiperineural suture was performed followed by immobilisation in a cast for 3 weeks. No specific rehabilitation programme was employed.

RESULTS

At review with a mean follow-up of 3 years, 46% of the patients obtained good or very good results according to Chanson's scoring system. The sensory recovery was between S4-S2 with the Weber test in 75% of patients. Fifty-eight percent of patients recovered a motor function between M3-M2.

DISCUSSION

In most papers, very good and good results averaged 60%. The results in our series did not achieve this level. We believe that this is due to two factors: firstly, the age distribution of our patients and secondly the lack of a specific program of sensory rehabilitation.

[Lesions of the distal radio-ulnar joint associated with isolated fractures of the radial shaft]

The authors have performed a retrospective study of 49 Galeazzi fractures treated between 1990 and 1998. This lesion is considered rare because it is often misdiagnosed as an isolated fracture of the radius. The mean age of the patients was 31 years. There was a male predominance with a sex ratio of 4/1. Road traffic accidents were the main etiology (45%). Galeazzi fracture type III in Mansat's classification represented 53%, followed by type II (33%), type I (8%) and equivalents of Galeazzi fracture (6%). The treatment was surgical in all cases. The radial fracture was internally fixed with a plate. Reduction of the distal radio-ulnar instability, achieved by manipulation, was maintained with radio-ulnar pin fixation in 53% and with plaster cast immobilization 45%. The results, evaluated according to Mikic's criteria were excellent in 87%. The prognosis of Galeazzi's fracture depends mainly on the initial treatment of the lesions of the distal radio-ulnar joint, which require for their diagnosis a meticulous clinical evaluation and a good radiological analysis.

[Femoral neck fracture in osteopoikilosis]

Osteopoikilosis was discovered in a 53-year-old patient who suffered a fracture of the right femoral neck. Plain X-rays demonstrated symmetrical bilateral stippling of variable size. No images were seen in the skull and spine. The fracture of the femoral neck was treated by total hip replacement. At surgery, the joint cartilage of the femoral head and the acetabulum had a normal aspect. Pathology examination of the femoral head demonstrated regular thick dense lamellae. Functional outcome at ten months was good (Postel-Merle-d'Aubigné score). Osteopoikilosis is an uncommon clinically latent condensing bone disease which can be revealed by bone fracture.