Treatment of deep infection of the hip associated with massive bone loss: two-stage revision with an antibiotic-loaded interim cement prosthesis followed by reconstruction with allograft

High failure rate of 2-stage revision for the infected total elbow arthroplasty: a single institution's experience

BACKGROUND

Despite 2-stage revision being a common treatment for elbow prosthetic joint infection (PJI), failure rates are high. The purpose of this study was to report on a single institution's experience with 2-stage revisions for elbow PJI and determine risk factors for failed eradication of infection. The secondary purpose was to determine risk factors for needing allograft bone at the second stage of revision in the setting of compromised bone stock.

METHODS

We retrospectively analyzed all 2-stage revision total elbow arthroplasties (TEAs) performed for infection at a single institution between 2006 and 2020. Data collected included demographics and treatment course prior to, during, and after 2-stage revision. Radiographs obtained after explantation and operative reports were reviewed to evaluate for partial component retention and incomplete cement removal. The primary outcome was failed eradication of infection, defined as the need for repeat surgery to treat infection after the second-stage revision. The secondary outcome was the use of allograft for compromised bone stock during the second-stage revision. Risk factors for both outcomes were determined.

RESULTS

Nineteen patients were included. Seven patients (37%) had either the humeral or ulnar component retained during the first stage, and 10 (53%) had incomplete removal of cement in either the humerus or ulna. Nine patients (47%) had allograft strut used during reimplantation and reconstruction. Nine patients (47%) failed to eradicate the infection after 2-stage revision. Demographic data were similar between the repeat-infection and nonrepeat-infection groups. Six patients (60%) with retained cement failed compared with 3 patients (33%) with full cement removal (P = .370). Two patients (29%) with a retained component failed compared to 7 patients (58%) with full component removal (P = .350). Allograft was used less frequently when a well-fixed component or cement was retained, with no patients with a retained component needing allograft compared to 9 with complete component removal (P = .003). Three patients (30%) with retained cement needed allograft, compared with 6 patients (67%) who had complete cement removal (P = .179).

CONCLUSION

Nearly half of the patients failed to eradicate infection after 2-stage revision. The data did not demonstrate a clear association between retained cement or implants and risk of recurrent infection. Allograft was used less frequently when a component and cement were retained, possibly serving as a proxy for decreased bone loss during the first stage of revision. Therefore, the unclear benefit of removing well-fixed components and cement need to be carefully considered as it likely leads to compromised bone stock that complicates the second stage of revision.

Impaction bone grafting for contained acetabular defects in total hip arthroplasty

BACKGROUND

Acetabular bone loss is a technical challenge in total hip arthroplasty (THA). This study sought to report the functional and radiological results of acetabular reconstruction using impaction bone grafting (IBG) in patients with acetabular bone deficiency undergoing primary or revision THA.

METHODS

In this prospective study, full history taking, preoperative clinical and radiological evaluation, and preoperative planning and templating were performed. The Paprosky classification and the American Academy of Orthopaedic Surgeons classification were used to assess the acetabular deficiencies. Clinical outcomes were assessed utilizing the Harris hip score (HHS) and a 4-question satisfaction questionnaire. Graft incorporation was evaluated in the last follow-up X-rays.

RESULTS

This study included 50 patients with a mean age of 46.7 ± 15.3 years. The THA was primary in 14 (28%) patients and revision in 36 (72%) patients. The mean HHS improved significantly from 28.8 ± 24.1 preoperatively to 76.6 ± 6.1, with a mean follow-up period of 23 months. Overall, 88% of patients were very satisfied. Complete radiological graft incorporation to host bone was achieved in 35 (70%) patients, and the remaining patients had partial incorporation. Complete graft incorporation was associated more frequently with primary THA, autografts, cementless cups, decreased defect size, and decreased graft layer thickness.

CONCLUSIONS

IBG for acetabular reconstruction in THA can achieve excellent clinical and radiological outcomes with a low complication rate.

LEVEL OF EVIDENCE

Level IV.

Articulating Hip Spacers with a Constrained Acetabular Liner: Effect of Acetabular Bone Loss and Cementation Quality

Articulating hip spacers for periprosthetic joint infection (PJI) offer numerous advantages over static spacers such as improved patient mobilization, hip functionality, and soft tissue tension. Our study aimed to determine complication rates of a functional articulating spacer using a constrained liner to determine the role of acetabular cementation mantle and bone loss on the need for second-stage surgery. A retrospective review of 103 patients was performed and demographic information, spacer components and longevity, spacer-related complications, reinfection rates, and grade of bone loss and acetabular cement mantle quality were determined. There was no significant difference in spacer-related complications or reinfection rate between PJI and native hip infections. 33 of 103 patients (32.0%) elected to retain their spacers. Between patients who retained their initial spacer and those who underwent reimplantation surgery, there was not a significant difference in cement mantle grade (p = 0.52) or degree of bone loss (p = 0.78). Functional articulating antibiotic spacers with cemented constrained acetabular liners demonstrate promising early results in the treatment of periprosthetic and native hip infections. The rate of dislocation events was low. Further efforts to improve cement fixation may help decrease the need for second-stage reimplantation surgery.

A review of current practices in periprosthetic joint infection debridement and revision arthroplasty

BACKGROUND

Periprosthetic joint infection remains a significant challenge for arthroplasty surgeons globally. Over the last few decades, there has been much advancement in terms of treatment and diagnosis, however, the fight rages on. As management of periprosthetic joint infections continues to evolve, it is critical to reflect back on current debridement practices to establish common ground as well as identify areas for future research and improvement. BODY: In order to understand the debridement techniques of periprosthetic joint infections, one must also understand how to diagnose a periprosthetic joint infection. Multiple definitions have been elucidated over the years with no single consensus established but rather sets of criteria. Once a diagnosis has been established the decision of debridement method becomes whether to proceed with single vs two-stage revision based on the probability of infection as well as individual patient factors. After much study, two-stage revision has emerged as the gold standard in the management of periprosthetic infections but single-stage remains prominent with further and further research.

CONCLUSION

Despite decades of data, there is no single treatment algorithm for periprosthetic joint infections and subsequent debridement technique. Our review touches on the goals of debridement while providing a perspective as to diagnosis and the particulars of how intraoperative factors such as intraarticular irrigation can play pivotal roles in infection eradication. By providing a perspective on current debridement practices, we hope to encourage future study and debate on how to address periprosthetic joint infections best.

Application of structural allogenous bone graft in two-stage exchange arthroplasty for knee periprosthetic joint infection: a case control study

Background

Knee prosthetic joint infection (PJI) is a common but devastating complication after knee arthroplasty. The revision surgeries for knee PJI may become more challenging when it is associated with large bone defects. The application of structural bone allograft in knee revision surgeries with large bone defects is not a new technique. However, there is a lack of literature reporting its efficacy in PJI cases. This study aimed to investigate the outcome of structural fresh frozen allogenous bone grafts in treating patients in knee PJI with large bone defects.

Methods

We performed a retrospective cohort analysis of knee PJI cases treated with two-stage exchange arthroplasty at our institution from 2010 to 2016. 12 patients with structural allogenous bone graft reconstructions were identified as the study group. 24 patients without structural allograft reconstructions matched with the study group by age, gender, and Charlson comorbidity index were enrolled as the control group. The functional outcome of the study group was evaluated with the Knee Society Score (KSS). Treatment success was assessed according to the Delphi-based consensus definition. The infection relapse rate and implant survivorship were compared between groups.

Results

Revision knees with structural allograft presented excellent improvement in the KSS (33.1 to 75.4). There was no significant difference between infection relapse-free survival rate and prosthesis survival rate in the two groups. The 8-year prosthesis survival rate was 90.9% in the study group and 91% in the control group (p = 0.913). The 8-year infection relapse-free survival rate was 80 and 83.3% in the study group and control group, respectively (p = 0.377).

Conclusion

The structural fresh frozen allogenous bone graft provided an effective way for bone defect reconstruction in knee PJI with an accountable survival rate. Meanwhile, using structural allografts did not increase the relapse rate of infection.

The Diagnosis and Treatment of Acetabular Bone Loss in Revision Hip Arthroplasty: An International Consensus Symposium

Despite growing evidence supporting the evaluation, classification, and treatment of acetabular bone loss in revision hip replacement, advancements have not been systematically incorporated into a single document, and therefore, a comprehensive review of the treatment of severe acetabular bone loss is needed. The Stavros Niarchos Foundation Complex Joint Reconstruction Center at Hospital for Special Surgery held an Acetabular Bone Loss Symposium on June 21, 2019, to answer the following questions: What are the trends, emerging technologies, and areas of future research related to the evaluation and management of acetabular bone loss in revision hip replacement? What constitutes the optimal workup and management strategies for acetabular bone loss? The 36 international experts convened were divided into groups, each assigned to discuss 1 of 4 topics: (1) preoperative planning and postoperative assessment; (2) implant selection, management of osteolysis, and management of massive bone loss; (3) the treatment challenges of pelvic discontinuity, periprosthetic joint infection, instability, and poor bone biology; and (4) the principles of reconstruction and classification of acetabular bone loss. Each group came to consensus, when possible, based on an extensive literature review. This document provides an overview of these 4 areas, the consensus each group arrived at, and directions for future research.

A Customized Knee Antibiotic-Loaded PMMA Spacer: A Preliminary Design Analysis

A preliminary design of customized antibiotic-loaded poly-methyl-methacrylate (ALPMMA) spacer characterized by an appropriate footprint according to the specific patient’s anatomy and a reliable mechanical response to severe functional loads (i.e., level walking and 45° bent knee) is reported. The targeted virtual prototyping process takes origin from a novel patented 3D geometrical conceptualization characterized by added customization features and it is validated by a preliminary FEM-based analysis. Mechanical and thermomechanical properties of the antibiotic-doped orthopedic PMMA cement, which will be used for the future prototype manufacturing, were measured experimentally by testing samples taken during a real day-running orthopedic surgery and manufactured according to the surgeon protocol. FEM analysis results indicate that small area is subjected to intensive stresses, validating the proposed geometry from the mechanical point of view, under the two loading scenarios, moreover the value of safety margins results positive, and this is representative of the lower stress magnitude compared to the critical material limits. The experimental data confirm that the presence of antibiotic will last during the surgeon period moreover, the temperature dependent modulus of the bone cement is slightly affected by the body range temperature whereas it will drastically drop for higher temperature out the range of interest. A complete customization, according to a patient anatomy, and the corresponding real prototype spacer will be manufactured by 3D printing techniques, and it will be validated by destructive testing during the second stage of this activity before commercialization.

On the Necessity of a Customized Knee Spacer in Peri-Prosthetic Joint Infection Treatment: 3D Numerical Simulation Results

Peri-prosthetic joint infections (PJIs) dramatically affect human health, as they are associated with high morbidity and mortality rates. Two-stage revision arthroplasty is currently the gold standard treatment for PJI and consists of infected implant removal, an accurate debridement, and placement of antimicrobial impregnated poly-methyl-metha-acrylate (PMMA) spacer. The use of antibiotic-loaded PMMA (ALPMMA) spacers have showed a success rate that ranges from 85% to 100%. ALPMMA spacers, currently available on the market, demonstrate a series of disadvantages, closely linked to a low propensity to customize, seen as the ability to adapt to the patients’ anatomical characteristics, with consequential increase of surgical complexity, surgery duration, and post-operative complications. Conventionally, ALPMMA spacers are available only in three or four standard sizes, with the impossibility of guaranteeing the perfect matching of ALPMMA spacers with residual bone (no further bone loss) and gap filling. In this paper, a 3D model of an ALPMMA spacer is introduced to evaluate the cause- effect link between the geometric characteristics and the correlated clinical improvements. The result is a multivariable-oriented design able to effectively manage the size, alignment, stability, and the patients’ anatomical matching. The preliminary numerical results, obtained by using an “ad hoc” 3D virtual planning simulator, clearly point out that to restore the joint line, the mechanical and rotational alignment and the surgeon’s control on the thicknesses (distal and posterior thicknesses) of the ALPMMA spacer is mandatory. The numerical simulations campaign involved nineteen patients grouped in three different scenarios (Case N° 1, Case N° 2 and Case N° 3) whose 3D bone models were obtained through an appropriate data management strategy. Each scenario is characterized by a different incidence rate. In particular, the observed rates of occurrence are, respectively, equal to 17% (Case N° 1), 74% (Case N° 2), and 10% (Case N° 3).

Total hip revision with custom-made spacer and prosthesis: A case report

BACKGROUND

Both periprosthetic joint infections (PJIs) and severe femoral segmental defects are catastrophic complications of total hip arthroplasty (THA), and both present a significant challenge in revisional surgery. There are limited data available to guide clinical decision making when both occur concurrently.

CASE SUMMARY

A 61-year-old woman presented with a 6-mo history of a sinus tract at the site of her original THA incision. Radiological imaging revealed a total hip joint implant with an ipsilateral segmental femoral defect. Based on histological, radiological, laboratory, and clinical features, a diagnosis of concurrent chronic PJI and segmental femoral defect (Type IIIB, Paprosky classification) was made. After multidisciplinary team discussion, three-dimensional (3D)-printed, custom-made antibiotic spacers were created that could be used to mold antibiotic-loaded cement spacer. These were placed following PJI debridement in the first stage of revision surgery. After the PJI was eliminated, a 3D-printed, custom-made, femoral prosthesis was created to repair the considerable femoral defect. After 20-mo follow-up, the patient had excellent functional outcomes with a near-normal range of hip movement. So far, neither evidence of recurrent infection nor loosening of the prosthesis has been observed.

CONCLUSION

We describe a case of “two-stage, custom-made” total hip revision to treat PJI with a concurrent segmental femoral defect. Use of a personalized, 3D-printed spacer and proximal femoral prosthesis led to satisfactory hip function and no early postoperative complications. Use of a customized implant provides surgeons with an alternative option for patients where no suitable spacer or implant is available. However, the long-term function, longevity, and cost-effectiveness of the use of custom-made prostheses have yet to be fully explored.

New Technique for Custom-Made Spacers in Septic Two-Stage Revision of Total Hip Arthroplasties

The choice of spacer in the interim phase of two-stage revision hip arthroplasty is crucial. Conventional concepts like a Girdlestone situation, handformed or preformed bone cement spacers show complications like soft-tissue contractions, abrasion of bone cement particles, dislocation, breakage and a low level of mobility in the interim phase. To address these disadvantages, the senior author developed a new technique for custom-made spacers in septic two-stage revision of total hip arthroplasties using prosthetic implants with individualized antibiotic mixture in the cement applying a mechanical inferior cementation method. The aim of this study was to evaluate the results of these spacers with respect to their non-inferiority in terms of reinfection and survival-rate of the new implant and to describe the complications associated with this procedure. Our collective consisted of 130 patients with a median follow-up of nearly five years. With a reinfect-free rate of 92% and a spacer-related complication rate of 10% (8% articular dislocation, 1% periprosthetic joint fracture, 1% breakage), this procedure seems to be safe and superior regarding complications compared to conventional concepts. Further studies are necessary to show the clinical benefit of this procedure.

Management of peri-prosthetic joint infection and severe bone loss after total hip arthroplasty using a long-stemmed cemented custom-made articulating spacer (CUMARS)

Background

There is little evidence on techniques for management of peri-prosthetic infection (PJI) in the context of severe proximal femoral bone loss. Custom-made articulating spacers (CUMARS) utilising cemented femoral stems as spacers was described providing better bone support and longer survival compared to conventional articulating spacers. We retrospectively report our experience managing PJI by adaptation of this technique using long cemented femoral stems where bone loss precludes use of standard stems.

Methods

Patients undergoing 1st stage revision for infected primary and revision THA using a cemented long stem (> 205 mm) and standard all-polyethylene acetabulum between 2011 and 2018 were identified. After excluding other causes of revision (fractures or aseptic loosening), Twenty-one patients remained out of total 721 revisions. Medical records were assessed for demographics, initial microbiological and operative treatment, complications, eradication of infection and subsequent operations. 2nd stage revision was undertaken in the presence of pain or subsidence.

Results

Twenty-one patients underwent 1st stage revision with a cemented long femoral stem. Mean follow up was 3.9 years (range 1.7–7.2). Infection was eradicated in 15 (71.4%) patients. Two patients (9.5%) required repeat 1st stage and subsequently cleared their infection. Three patients (14.3%) had chronic infection and are on long term suppressive antibiotics. One patient (4.8%) was lost to follow up before 2 years. Complications occurred in seven patients (33%) during or after 1st stage revision. Where infection was cleared, 2nd stage revision was undertaken in 12 patients (76.5%) at average of 9 months post 1st stage. Five (23.8%) CUMARS constructs remained in-situ at an average of 3.8 years post-op (range 2.6–5.1).

Conclusions

Our technique can be used in the most taxing of reconstructive scenarios allowing mobility, local antibiotic delivery, maintenance of leg length and preserves bone and soft tissue, factors not afforded by alternative spacer options.

Conservative two-stage revision with primary components of infected total hip arthroplasty: An analysis of survival, clinical and radiographic outcomes

Few studies provide an analysis of conservative two-stage revision of hip periprosthetic joint infection (PJI) and its impact on final outcome. A conservative revision is defined when soft tissues and bone quality enable the use of primary prosthetic components. Data of patients treated for chronic hip PJI who underwent two-stage revision between 2009 and 2016 and had a minimum of 2 years of follow-up were collected. Oxford Hip Score (OHS), Harris Hip Score (HHS) and radiological and microbiological data were retrieved and analysed. Clinical and functional outcome, survival, mortality, eradication, reinfection and re-revision rates within subgroups of patients with primary components and revision components are reported herein. A total of 148 patients underwent two-stage hip exchange with a mean follow-up of 55.6 ± 23.1 months and a mean age at surgery of 64.3 ± 12.7 years. Forty-four percent of patients underwent conservative revision. The mean HHS significantly improved from 40.6 ± 9.4 points to the final value of 87.8 ± 10.5 points (p = .002), and the mean OHS went from 20.3 ± 3.8 points to 40.3 ± 5. points (p< .001). Patients who were treated with primary components or isolated revision stems in the second stage had a significant reduction in surgical times (p< .001). The mortality rate for all causes of death was 6.8%, the eradication rate was 89.9%, the reinfection rate was 4.7% and the reoperation rate was 7.4% without differences between conservative and non-conservative revisions. Two-stage exchange arthroplasty for total hip arthroplasty (THA) PJI is a good strategy that provides satisfactory results, high eradication rates and no further need for revision. The conservative two-stage revision in patients with adequate bone stock represents a feasible option with good results and survival rates.

Partial implant retention in two-stage exchange for chronic infected total hip arthroplasty

BACKGROUND

The efficacy of partial retention of well-fixed components during two-stage exchange for chronic total hip arthroplasty (THA) infection has remained unknown.

METHODS

A total of 14 patients with chronic infected THA were treated with damage control two-stage revision, including selective retention of the well-fixed femoral or acetabular component, aggressive debridement, antibiotic-laden cement spacer, antibiotic therapy, and delayed reimplantation. Indications for this treatment included chronic infected THAs with ingrown femoral or acetabular component and positive microbial growth with sensitive antibiotics. We excluded patients with acute infection; negative microbial growth; positive pathogen with high-virulence bacterial infections and multiple drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus, fungi, and Mycobacterium tuberculosis; sinus formation; a prior failure for periprosthetic joint infection (PJI) treatment; and obvious bone resorption in both femoral and acetabulum side. During the study period, this represented 3.3% (14/425) of the patients treated for infected THA. Minimum follow-up was three  years. None of the 14 patients in this series were lost to follow-up. Successful treatment was defined according to a modified Delphi-based international multidisciplinary consensus.

RESULTS

No repeated debridement and recurrence of infection occurred during the study period; no patient need chronic antibiotic suppression. Successful treatment of chronic PJI was achieved in all patients. Despite the high peri-operative complication rate, no severe consequences were observed. The mean Harris Hip Score was 86 (range, 82-92; SD, 3.3).

CONCLUSIONS

The selective partial implant retention two-stage revision for chronic PJI may be a treatment option in properly selected patients with low virulence bugs.

Mechanical failure of articulating polymethylmethacrylate (PMMA) spacers in two-stage revision hip arthroplasty: the risk factors and the impact on interim function

BACKGROUND

This study aimed to investigate the risk factors for mechanical failure of cement spacers and the impact on hip function after two-stage exchange arthroplasty for periprosthetic joint infection (PJI).

METHODS

Thirty-one patients (19 males and 12 females) with hip PJIs underwent resection arthroplasty and implantation of cement spacers from January 2014 to December 2015. Patients who encountered spacer-associated mechanical complications in the interim period (14 of 31) were compared with those without complications (17 of 31). Complications were defined as spacer dislocation, spacer fracture, spacer fracture with dislocation, and femoral fracture during or following spacer implantation. Hip functional outcome was assessed using the Harris hip score (HHS). Treatment success was defined according to the following criteria: (1) no symptoms or signs indicative of infection; (2) no PJI-related mortality; and (3) no subsequent surgical intervention for infection after reimplantation surgery. Multivariate logistic regression and Kaplan-Meier survival curves were used for analysis.

RESULTS

Fourteen patients (14/31 = 45%) suffered at least one spacer-related complication within the interim period. The development of spacer complications was associated with a younger age (odds ratio [OR] 0.91, 95% confidence interval [CI] 0.83-1.00, p = 0.045) and chronic PJI (OR 14.7, 95% CI 1.19-182, p = 0.036). Patients with spacer complications also had a lower median HHS (37 vs. 60, p < 0.001) before reimplantation in comparison to those without spacer complications. After reimplantation, the two groups had a similar median HHS (90 vs. 89, p = 0.945). Two patients did not undergo reimplantation due to extensive comorbidities, and subsequently retained the antibiotic spacer for definitive treatment. The 2-year treatment success rate was 84.6% in the spacer-complication group and 87.5% in the non-spacer-complication group (p = 0.81).

CONCLUSION

There was a high complication rate for articulating PMMA spacers during the interim period of two-stage revision total hip arthroplasty. A young age and chronic infection were the primary risk factors associated with mechanical complications. Patients at high risk of spacer-related mechanical complications should be advised accordingly by surgeons. Knowing the possible risk factors, surgeons should educate patients thoroughly to avoid spacer complications, thereby increasing patient satisfaction in the interim stage.

LEVEL OF EVIDENCE

Prognostic Level III.

Antibiotic-Loaded Polymethylmethacrylate Beads and Spacers in Treatment of Orthopedic Infections and the Role of Biofilm Formation

Polymethylmethacrylate (PMMA) also referred as (acrylic) bone cement is a non-degradable biomaterial that has been used in clinical orthopedic practice for several decades. PMMA can be used in a plain formulation, but is often used in an antibiotic-loaded formulation in (primary and revision) arthroplasty and in treatment of orthopedic infections as prosthetic joint infections (PJI) and chronic osteomyelitis. In treatment of PJIs antibiotic-loaded PMMA is often used as a carrier material for local antibiotic delivery in addition to treatment with systemic antibiotics. In this case, the antibiotic-loaded PMMA is often used as a spacer or as a bead chain. Since the introduction of PMMA as an antibiotic carrier there is a tremendous amount of scientific and clinical papers published, which studied numerous different aspects of antibiotic-loaded PMMA. This paper will review the research regarding basic principles of antibiotic-loaded PMMA as mechanism of action, antibiotic-release capacities, choice of antibiotics and influences on mechanical properties of PMMA. Subsequently, concerns regarding the application of antibiotic-loaded PMMA, biofilm formation, antibiotic resistance and local or systemic toxicity will be discussed. In addition to these subjects, the role of antibiotic loaded PMMA in clinical treatment of PJIs and chronic osteomyelitis is discussed in the final part of this paper.

What Determines the Type and Dose of Antibiotic That Is Needed to Be Added to the Cement Spacer in Patients With Infected Total Ankle Arthroplasty (TAA)?

RECOMMENDATION

We recommend tailoring the antibiotic in cement spacers to the infecting organism if it has been identified, as is typically done in total knee and hip arthroplasty. Otherwise, broad-spectrum antibiotics may be utilized. Medical comorbidities should always be considered, especially with regard to renal function and allergy profile. A thermostable antibiotic should be added to cement.

LEVEL OF EVIDENCE

Consensus.

DELEGATE VOTE

Agree: 100%, Disagree: 0%, Abstain: 0% (Unanimous, Strongest Consensus).

Utility of Serological Markers for Detecting Persistent Infection in Two-Stage Revision Arthroplasty in Patients With Inflammatory Arthritis

BACKGROUND

Serum erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are commonly used for the diagnosis of persistence of infection after the first stage of 2-stage revision arthroplasty for periprosthetic joint infection (PJI). As both ESR and CRP are markers of systemic inflammation, the utility of these tests to monitor infection clearance in patients with inflammatory arthritis is unclear.

METHODS

From 2001 to 2016, 44 two-stage revision total hip or knee arthroplasties in patients with an inflammatory arthritis diagnosed by a rheumatologist were identified. Persistence of infection at the time of planned second stage was defined as satisfying the Musculoskeletal Infection Society criteria for PJI (14 infected, 30 noninfected). ESR and CRP values were compared between the stages using nonparametric tests. Receiver operating characteristic analysis was performed to obtain the diagnostic parameters.

RESULTS

ESR and CRP decreased between the stages in the noninfected group (ESR: mean decrease = 31.6 mm/h [19.2-44.0], P < .001; CRP: mean decrease = 5.2 mg/dL [2.1-8.2], P < .001), but remained elevated in the infected group (ESR: mean decrease = 7.7 [-23.1 to 36.6], P = .572; CRP: mean decrease = 1.5 [-2.2 to 5.1], P = .258). Optimal thresholds for persistent infection were 29.5 mm/h and 2.8 mg/dL, respectively, for ESR and CRP. The sensitivity and specificity at the optimal thresholds were 64% and 77% for ESR, and 64% and 90% for CRP.

CONCLUSION

ESR and CRP responded to the treatment of PJI in patients with inflammatory arthritis and had reasonably high specificities with moderate sensitivities. ESR and CRP appear to be useful tools in diagnosing persistent infection even in patients with inflammatory arthritis.

Diagnostic Utility of Histological Analysis for Detecting Ongoing Infection During Two-Stage Revision Arthroplasty in Patients With Inflammatory Arthritis

BACKGROUND

Surgeons often rely on intra-operative histology (frozen sections [FS]) to determine the next step in surgical management during the second stage (re-implantation surgery) of 2-stage revision arthroplasty. The purpose of the study is to assess the accuracy of permanent sections (PS) and FS in the diagnosis of persistent infection during re-implantation in patients with an inflammatory arthritis.

METHODS

From 2001 to 2016, 47 planned second-stage revision total hip arthroplasty and total knee arthroplasty in patients with inflammatory arthritis were identified. Revisions were classified as having persistent infection if they were Musculoskeletal Infection Society positive at the time of second stage. PS or FS was considered to be positive for infection when at least one of the specimens demonstrated an acute inflammation. Receiver operating characteristic analysis was performed to obtain the diagnostic parameters.

RESULTS

There were 9 (19%) persistent infections. Both PS and FS had very high specificity (PS = FS = 94.7%). Sensitivity of PS was higher than FS, although not statistically significant (PS = 88.9%, FS = 55.6%, P = .083). Overall, PS had a better diagnostic utility than FS (area under the curve: PS vs FS = 0.92 vs 0.75, P = .045). Four specimens had discrepancies between PS and FS histology. In all 4 instances, the specimens were read as positive (infected) by PS, but negative by FS.

CONCLUSION

Histological analysis is recommended at the time of re-implantation surgery even in patients with inflammatory arthritis. PS had a better diagnostic utility than FS suggesting that areas of acute inflammation may be scattered and may not always be captured in the specimens taken for FS.

Changes in Antibiotic Susceptibility of Staphylococcus aureus Between the Stages of 2-Stage Revision Arthroplasty

BACKGROUND

Staphylococcus aureus is the predominant cause of periprosthetic joint infection (PJI) and can persist at the time of planned second stage of 2-stage revision arthroplasty, despite antibiotic cement spacer insertion and parenteral antibiotic therapy. Given the rapid emergence of antibiotic resistance, it is important to determine whether the antibiotic susceptibility of microorganisms changes between the stages of a 2-stage revision.

METHODS

A total of 1614 2-stage revision hip/knee arthroplasties performed for PJI at 2 academic institutions from 2000 to 2015 were identified. S aureus (methicillin susceptible and/or resistant) was isolated by culture in 402 (24.9%) cases during the first stage (resection arthroplasty). S aureus persisted and was cultured in 30 cases (knees = 18, hips = 12) during the second stage. Minimum inhibitory concentrations (MICs), demographics, antibiotic therapy, and surgical history were collected. The MICs at the time of the first-stage and second-stage surgeries were compared.

RESULTS

Nine (30%) revisions had an increase in vancomycin MIC. Six had an increase from ≤0.5 to 1 μg/mL, 2 had an increase from ≤0.5 to 2 μg/mL, and 1 had an increase from 1 to 2 μg/mL. All of the 9 revisions with an increase in vancomycin MIC had vancomycin in spacer.

CONCLUSION

Increases in the MICs were observed for vancomycin, the antibiotic widely used in cement spacers, in about one-third of the revisions. Despite the small sample size, the data from this preliminary study raise concern about the potential for emergence of resistant organisms between the stages of a 2-stage revision.

Removal of an Infected Total Hip Arthroplasty: Risk Factors for Repeat Debridement, Long-term Spacer Retention, and Mortality

BACKGROUND

Two-stage exchange arthroplasty remains the preferred approach to treatment of chronic periprosthetic joint infection (PJI) following total hip arthroplasty (THA). The objective of the present study is to investigate the fate of antibiotic spacers placed for periprosthetic joint infection after THA and evaluate risk factors for outcomes other than reimplantation.

METHODS

A national database was queried for Medicare patients who underwent removal of an infected hip prosthesis and placement of an antibiotic spacer. Patients with a study end point within 1 year postoperatively were included: (1) in-hospital mortality, (2) repeat debridement without reimplantation within 1 year, (3) resection arthroplasty, and (4) reimplantation of a hip arthroplasty. Independent patient-related risk factors for these end points were evaluated with a multivariate logistic regression analysis.

RESULTS

A total of 7146 patients met all inclusion and exclusion criteria. Within 1 year postoperatively, 464 patients (6.5%) died in a hospital setting, 775 patients (10.8%) had a repeat debridement procedure, 404 patients (5.7%) had a resection arthroplasty, 1202 patients (16.8%) retained their spacers, and the remaining 4301 patients (60.2%) were reimplanted at an average of 124.4 ± 39.3 days. Numerous independent patient-related risk factors for these were identified.

CONCLUSION

At 1 year only 60% of patients undergo reimplantation. One-sixth of patients retain their spacer and approximately 10% require repeat debridement. Death occurred in at least 6% of the population. Several independent patient-related risk factors exist for repeat debridement, no reimplantation or death within 1 year following index THA removal.

Results of single stage exchange arthroplasty with retention of well fixed cement-less femoral component in management of infected total hip arthroplasty

AIM

To investigate success of one stage exchange with retention of fixed acetabular cup.

METHODS

Fifteen patients treated by single stage acetabular component exchange with retention of well-fixed femoral component in infected total hip arthroplasty (THA) were retrospectively reviewed. Inclusion criteria were patients with painful chronic infected total hip. The patient had radiologically well fixed femoral components, absence of major soft tissue or bone defect compromising, and infecting organism was not poly or virulent micro-organism. The organisms were identified preoperatively in 14 patients (93.3%), coagulase negative Staphylococcus was the infecting organism in 8 patients (53.3%).

RESULTS

Mean age of the patients at surgery was 58.93 (± 10.67) years. Mean follow-up was 102.8 mo (36-217 mo, SD 56.4). Fourteen patients had no recurrence of the infection; one hip (6.7%) was revised for management of infection. Statistical analysis using Kaplan Meier curve showed 93.3% survival rate. One failure in our series; the infection recurred after 14 mo, the patient was treated successfully with surgical intervention by irrigation, and debridement and liner exchange. Two complications: The first patient had recurrent hip dislocation 12 years following the definitive procedure, which was managed by revision THA with abductor reconstruction and constrained acetabular liner; the second complication was aseptic loosening of the acetabular component 2 years following the definitive procedure.

CONCLUSION

Successful in management of infected THA when following criteria are met; well-fixed stem, no draining sinuses, non-immune compromised patients, and infection with sensitive organisms.

Development of advanced biantibiotic loaded bone cement spacers for arthroplasty associated infections

The incidence increase of infections in patients with hip or knee implants with resistant pathogens (mainly some S. coagulase-negative and gram positive bacteria) demands advanced antibiotic loaded formulations. In this paper, we report the design of new biantibiotic acrylic bone cements for in situ delivery. They include a last generation antibiotic (daptomycin or linezolid) in combination with vancomycin and are performed based on a novel modification of the Palacos R^® acrylic bone cement, which is based on two components, a liquid (methyl methacrylate) and a solid (polymeric phase). Hence, the solid component of the experimental formulations include 45wt% of microparticles of poly(D,L-lactic-co-glycolic) acid, 55wt% of poly(methyl methacrylate) beads and supplements (10wt-% each) of antibiotics. These formulations provide a selective and excellent control of the local release of antibiotics during a long time period (up to 2 months), avoiding systemic dissemination. The antimicrobial activity of the advanced spacers tested against S. aureus shows that single doses would be enough for the control of the infection. In vitro biocompatibility of cements on human osteoblasts is ensured. This paper is mainly focused on the preparation and characterization of cements and the studies of elution kinetics and bactericidal effects. Developed formulations are proposed as spacers for the treatment of infected arthroplasties, but also, they could be applied in other antibiotic devices to treat relevant bone-related infection diseases.

Vancomycin and Ceftazidime in Bone Cement as a Potentially Effective Treatment for Knee Periprosthetic Joint Infection

BACKGROUND

The aim of this study was to determine the optimal formulation of antibiotic-loaded bone cement for knee periprosthetic joint infection. We used both in vitro and in vivo models incorporating various broad-spectrum antibiotics and tested their efficacy against gram-positive and gram-negative bacteria.

METHODS

Bone cement specimens loaded with 4 g of either vancomycin or teicoplanin and 4 g of ceftazidime, imipenem, or aztreonam were studied to measure their in vitro antibiotic release characteristics and antibacterial capacities against methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. Bone cement spacers loaded with the antibiotics with the superior in vitro antibacterial capacity were then implanted into 8 patients (4 women and 4 men between 51 and 79 years of age) diagnosed with chronic knee periprosthetic joint infection. The antibiotic concentrations and antibacterial activities in the joint fluid at the site of the infection were measured following spacer implantation.

RESULTS

Cement samples loaded with vancomycin and ceftazidime exhibited in vitro antibacterial activity against the test microorganisms that lasted for as long as or longer than that of cement loaded with the other antibiotic combinations. Joint fluid samples exhibited activity against bacteria including American Type Culture Collection (ATCC) strains and clinically isolated strains.

CONCLUSIONS

Bone cement loaded with vancomycin and ceftazidime provided broad-spectrum antibacterial capacity both in vitro and in vivo and was shown to be a potentially effective therapeutic measure in the treatment of knee periprosthetic joint infections.

CLINICAL RELEVANCE

This study confirmed the potential effectiveness of drug delivery from bone cement spacers impregnated with vancomycin and ceftazidime.

Should well-fixed uncemented femoral components be revised in infected hip arthroplasty? Report of five trial cases

BACKGROUND

Well-fixed femoral component removal remains difficult and complicated.

METHODS

We report herein the outcomes of two-stage surgery involving retention of bone-ingrown uncemented stems, aggressive soft-tissue debridement, and delayed reimplantation of an acetabular component in 5 patients for infected hip arthroplasty.

RESULTS

By a mean follow-up point of 4.2 years after the second-stage operation, none of the 5 patients experienced recurrence of infection, and the mean Harris hip score had improved from 63 to 86 points by the latest follow-up evaluation.

CONCLUSION

Two-stage revision with retention of well-fixed uncemented stems could be an alternative treatment option in hip periprosthetic infection.

Antibiotic mixing through impacted bone grafts does not seem indicated in two-stage cemented hip revisions for septic loosening

Impaction bone grafts (IBG) in two-stage revision for prosthetic hip infection (PHI) might be more susceptible for infection, therefore antibiotic mixing through these grafts has been suggested. However, outcomes have not been compared with IBG without antibiotics and no long-term results are available. Therefore, we evaluated long-term infection-free outcome after the use of IBG without antibiotic supplement in two-stage revision for PHI. Patients were divided into positive (group 1, n = 8) and negative (group 2, n = 28) cultures at re-implantation and followed up to 18 years after re-implantation. Five of 36 patients died from non-orthopaedic causes (median 37, range 24-149 months). Five patients had a re-operation not related to infection (median 39, range 7-140 months). These were censored in the Kaplan-Meier estimator at the last outpatient evaluation. We found an overall re-infection rate of 2.8% within two years, which matches comparative studies in which antibiotic impregnated bone grafts had been used. In group 1, there was one re-infection after 44 months. In group 2, all three infections occurred within 56 months with an estimated infection-free percentage at 10 years of 87% (95% CI 66-96). Follow-up should be extended beyond two years and randomised clinical trials are needed for further comparison with IBG impregnated with antibiotics.

The effect of temperature on the viability of human mesenchymal stem cells

Introduction

Impaction allograft with cement is a common technique used in revision hip surgeries for the last 20 years. However, its clinical results are inconsistent. Recent studies have shown that mesenchymal stem cells (MSCs) seeded onto allograft can enhance bone formation. This in vitro study investigates whether the increase in temperature related to the polymerisation of bone cement will affect the viability of human MSCs.

Methods

The viability of human MSCs was measured after incubating them at temperatures of 38°C, 48°C and 58°C; durations 45 seconds, 80 seconds and 150 seconds. A control group was kept at 37°C and 5% carbon dioxide for the duration of the investigation (7 days). During the course of the study the human MSCs were analysed for cell metabolic activity using the alamarBlue™ assay, cell viability using both Trypan Blue dye exclusion and calcein staining under fluorescent microscopy, and necrosis and apoptosis using Annexin V and propidium iodide for flow cytometric analysis. A one-way analysis of variance with a priori Dunnett’s test was used to indicate the differences between the treatment groups, when analysed against the control. This identified conditions with a significant difference in cell metabolic activity (alamarBlue™) and cell viability (Trypan Blue).

Results

Results showed that cell metabolism was not severely affected up to 48°C/150 seconds, while cells in the 58°C group died. Similar results were shown using Trypan Blue and calcein analysis for cell viability. No significant difference in apoptosis and necrosis of the cells was observed when human MSCs treated at 48°C/150 seconds were compared with the control group.

Conclusions

The study suggests that human MSCs seeded onto allograft can be exposed to temperatures up to 48°C for 150 seconds. Exposure to this temperature for this time period is unlikely to occur during impaction allograft surgery when cement is used. Therefore, in many situations, the addition of human MSCs to cemented impaction grafting may be carried out without detrimental effects to the cells. Furthermore, previous studies have shown that this can enhance new bone formation and repair the defects in revision situations.

A multidisciplinary team approach to two-stage revision for the infected hip replacement

We report the five year outcomes of a two-stage approach for infected total hip replacement. This is a single-surgeon experience at a tertiary centre where the more straightforward cases are treated using single-stage exchange. This study highlights the vital role of the multidisciplinary team in managing these cases.

A total of 125 patients (51 male, 74 female) with a mean age of 68 years (42 to 78) were reviewed prospectively. Functional status was assessed using the Harris hip score (HHS). The mean HHS improved from 38 (6 to 78.5) pre-operatively to 81.2 (33 to 98) post-operatively. Staphylococcus species were isolated in 85 patients (68%).

The rate of control of infection was 96% at five years. In all, 19 patients died during the period of the study. This represented a one year mortality of 0.8% and an overall mortality of 15.2% at five years. No patients were lost to follow-up.

We report excellent control of infection in a series of complex patients and infections using a two-stage revision protocol supported by a multidisciplinary approach. The reason for the high rate of mortality in these patients is not known.

Cite this article: Bone Joint J 2014;96-B:1312–18

Two-stage revision for prosthetic joint infection: outcome and role of reimplantation microbiology in 107 cases

Two-stage revision is widely used for the treatment of prosthetic joint infections. However, the duration of antibiotic treatment between stages and role of reimplantation microbiology are controversial. The purpose of this study was to evaluate the outcome and influence of the reimplantation microbiology of two-staged revisions with 6 weeks of antibiotic treatment. We retrospectively reviewed 107 patients treated with two-stage revision between 2001 and 2009. The overall treatment success rate was 94.4%. The reimplantation cultures were positive in 5/97 (5.2%) cases, and only one of them failed. Therefore, we achieved excellent results with a 6-week course of antibiotics between stages in two-stage revision. Positive reimplantation cultures do not seem to be associated with worse outcomes.

Partial two-stage exchange for infected total hip arthroplasty: a preliminary report

BACKGROUND

One common approach to the infected total hip arthroplasty (THA) calls for a staged revision, including removal of all components. However, removal of well-fixed femoral components can result in bone loss and compromised fixation; it is not known whether it is effective to leave a well-fixed femoral component in situ, remove only the acetabular component, débride thoroughly, place a spacer, and delay reimplantation.

QUESTIONS/PURPOSES

The purposes of this study were to determine (1) the frequency of infection recurrence; (2) the frequency of death; and (3) the Harris hip scores of patients treated with a "two-stage partial exchange" approach.

METHODS

A retrospective analysis from 2000 through January 2011 revealed 19 patients with infected THA treated with partial two-stage exchange including complete acetabular component removal, aggressive soft tissue débridement, retention of the well-fixed femoral stem, placement of an antibiotic-laden cement femoral head on the trunnion of the retained stem, postoperative course of antibiotics, and delayed reimplantation. Indications for this treatment included those patients whose femoral component was determined to be well fixed and its removal would result in significant femoral bone loss and compromise of future fixation. During the study period, this represented 7% (19 of 262) of the patients whom we treated for a chronically infected THA. Minimum followup was 2 years (mean, 4 years; range, 2-11 years). None of the 19 patients in this series were lost to followup. We defined failure as recurrence of infection in the same hip or the use of long-term suppressive antibiotics.

RESULTS

Two patients (11%), both with prior failure of two-staged treatment of infection, failed secondary to recurrence of infection at an average of 3.3 years. There were no patient deaths within 90 days. The mean Harris hip score was 68 (range, 31-100; best score is 100).

CONCLUSIONS

Insofar as 89% of patients in this series were clinically free of infection at a minimum of 2 years, we believe partial two-stage exchange may represent an acceptable option for patients with infected THA when femoral component removal would result in significant bone loss and compromise of reconstruction. Further study is required on this approach.

Two-stage revision total hip arthroplasty for periprosthetic infections using antibiotic-impregnated cement spacers of various types and materials

Antibiotic-impregnated hip cement spacers of various types and materials have been used in the treatment of periprosthetic hip infections. We developed a handmade spacer by using polymethylmethacrylate (PMMA) and/or α-tricalcium phosphate (α-TCP). In this study, we retrospectively reviewed the surgical outcomes in 36 consecutive patients treated with 2-stage revision total hip arthroplasty by using our antibiotic-impregnated hip cement spacers. We aimed to analyze the infection control and reinfection rates after revision surgery. Moreover, we analyzed the possible predictors of postoperative reinfection. After exclusion of 1 patient who died immediately after the first-stage surgery, infection was controlled in 33 of the 36 hips (success rate, 91.7%). Two of these 33 hips underwent resection arthroplasty. Of the 36 hips that had been treated with the antibiotic-cement spacer, 31 hips (86.1%) were eligible for the second-stage prosthesis re-implantation. The 31 protocol hip joints of patients followed up for >6 months (mean, 48.6 months). Ten of these 31 hips (32.3%) became reinfected. No possible predictor examined differed significantly between the reinfection-positive and reinfection-negative groups. However, spacers consisting of PMMA cement alone were associated with the highest risk of reinfection. Therefore, α-TCP-containing antibiotic-impregnated hip cement spacers might decrease the reinfection rate in patients undergoing re-implantation.

One-stage revision arthroplasty for infected hip replacements

Infection remains a serious complication after total hip arthroplasty (THA) and is a leading cause of hip revision surgery. It is currently accepted that removal of the prosthesis is essential to curing an infection when facing chronic PJIs with prosthesis loosening. In order to avoid the disadvantages of a two-stage approach, some authors have proposed a one-stage hip revision for the treatment of hip prosthesis infection in selected patients using not only antibiotic-loaded cemented components but also cementless implant. In the case of a one-stage procedure, the patient is exposed to a single major procedure and therefore lower cumulative perioperative risk. A functional prosthesis replacement is completed without exposure to the complications associated with spacers. In addition, there are also benefits both financially and in terms of resource allocation.

Retaining well-fixed cementless stem in the treatment of infected hip arthroplasty

BACKGROUND AND PURPOSE

Two-stage reconstruction, reimplantation after removal of an infected prosthesis, has been considered to be the gold standard for treatment of infected hip arthroplasty. However, during the removal of a well-fixed femoral stem, the proximal femur can be damaged and a sequestrum can be formed, which might lead to chronic osteomyelitis and difficulty in reimplantation. We wanted to determine whether infection after hip arthroplasty can be treated without removal of a well-fixed stem.

METHODS

We treated 19 patients who had an infection after hip replacement, but a well-fixed cementless stem, with 2-stage reconstruction. At the first stage, we removed the acetabular cup, the liner and the head, but not the stem. We then implanted a cup of cement spacer. After control of infection, we reimplanted the acetabular component and head.

RESULTS

2 patients did not undergo second-stage reconstruction because they were satisfied with the pain relief and the activity that they had with the cement-spacer implantation. The remaining 17 patients underwent the second-stage of the reconstruction using cementless arthroplasty. At a mean follow-up time of 4 (2-8) years, 15 of the patients had no recurrence of infection, with satisfactory clinical and radiographic outcome.

INTERPRETATION

This second-stage reconstruction after retention of the stem could be an alternative treatment option for periprosthetic infection with a well-fixed stem.

A two stage re-implantation protocol for the treatment of deep periprosthetic hip infection. Mid to long-term results

Deep periprosthetic hip infection is a devastating complication. Goal of treatment is infection eradication and durable functional reconstruction. Two-stage re-implantation is the standard of treatment. From January 1998 to December 2004 we treated 38 patients with an infected THA. There were 24 females and 14 males, with a mean age of 67 years (61-75). The infection occurred 13 months to 15 years (mean: 7.2 years) after the index operation. The mean follow-up was 11.6 years (7 to 14). 35 patients were available for review. Almost one third of the patients had been treated before with antibiotics. In 5 cases more than one pathogen were present. In 3 cases, it was not possible to isolate a causative organism. In 15 cases (43%), a resistant pathogen was isolated. We used a two stage re- implantation protocol. Spacer was not used in any of the cases. Femoral revision was performed with uncemented implants, 21 of distal (wagner type) fixation and 14 of modular type with proximal fixation. 24 press fit shells (17 oTMT cups) and 11 Muller rings were used. In 33 cases (94%) eradication of infection was achieved. The mean HHS improved from a mean of 38.2 preoperatively to a mean of 88.6 at final follow-up (p<0.001). There was no case of implant loosening or migration. Chronic late infection can be managed successfully with a two stage re-implantation protocol, without interim spacer, including neglected cases, previous long term antibiotics and cases with resistant pathogens.

Bone grafting and one-stage revision of THR - biological reconstruction and effective antimicrobial treatment using antibiotic impregnated allograft bone

Infection of a total hip replacement (THR) is considered one of the most serious complications in orthopaedic surgery. Problems derive from the presence of biofilms with inherent resistance to usual antibiotic treatment and bone defects resulting from infection induced osteolysis. Discussions on the choice of treatment mainly focus on the chance of eradicating the infection in either one or more stages. The advantages of only one operation with regard to patients' satisfaction, functional results and economical burden are evident. However, the fear of re-infection usually leads surgeons to multiple stage procedures, mostly using antibiotic loaded spacers in the interval. Spacers have no effect on biofilms and are associated with a high rate of complications such as breakage or dislocation. Cemented revisions show several disadvantages like reduction of biomechanical properties through added antibiotics, inferior long term results, difficulties of removal in case of recurrence etc. Uncemented implants appear more advantageous but are at risk of becoming colonised by remaining biofilm fragments. To overcome this risk higher local concentrations of antibiotics are needed. Allograft bone may be impregnated with high loads of antibiotics using special incubation techniques, resulting in an antibiotic bone compound (ABC). ABC provides local concentrations exceeding those of cement by more than a 100-fold and efficient release is prolonged for several weeks. At the same time it is likely to restore bone stock, which is usually compromised after removal of an infected endoprosthesis. Based on these considerations new protocols for one-stage exchange of infected THR have been established. Bone voids may be filled with ABC, uncemented implants may be fixed in original healthy bone. Recent studies indicate an overall success rate of more than 90% with one operation, without any adverse side effects. Incorporation of allografts appears as after grafting with unimpregnated bone grafts. One stage revision using ABC together with uncemented implants, should be at least comparable to multiple stage procedures, but with the advantage of the obvious benefits for patients and cost.

Microhardness of bi-antibiotic-eluting bone cement scaffolds

Bi-antibiotic-impregnated bone cements (BIBCs) are widely used in orthopaedics as a prophylactic agent (depot) to address post-surgical infections. Although hardness is widely considered a viable index to measure the integrity of the cement structure, there are few specific studies involving changes in hardness characteristics of BIBCs post elution of high doses of two widely used antibiotics: tobramycin and gentamicin. Increased doses of antibiotics and increased duration of elution may also decrease the hardness of polymethyl methacrylate (PMMA) bone cement, thus increasing the chances of shattering, scratching, and deformation.

In this project, we have investigated the changes in surface hardness of five different antibiotic-loaded specimens: 0.5 g tobramycin and 0.5 g gentamicin together, 1 g tobramycin, 1 g gentamicin, 5 g tobramycin and 5 g gentamicin together, and 10 g tobramycin (each added to 40 g of PMMA), post elution for various time periods (1, 3, and 21 days). The effect of hydration on the hardness of bone cement was studied to replicate in vivo conditions. The micro-indentation tester (Buehler m5103) was utilized to determine if the increased antibiotic loads would compromise the integrity of the bone cement matrix.

The results demonstrated that the amount of drug initially incorporated determined the hardness of the cement post elution. As compared to the control (no antibiotic), specimens containing 1 and 10 g of antibiotic exhibited over 50% and 73% decrease in hardness, respectively. The different treatment durations (post 1 day) as well as the hydration conditions had insignificant effect on the hardness of the cement.

Temporary cement tectoplasty: a technique to improve prefabricated hip spacer stability in two-stage surgery for infected hip arthroplasty

This technical note describes an intraoperatively custom-made, antibiotic-loaded bone cement roof, used in conjunction with a prefabricated hip spacer to improve component stability, as part of the first stage of a two-stage procedure for an infected hip implant. This technique was successfully used in seven cases who presented with extensive superior and/or posterio-superior acetabular defect, which created a risk of spacer dislocation. With this technique we were able to avoid any further dislocation in these seven cases. We believe that the technique may reduce postoperative spacer dislocation in cases with extensive acetabular defects, while improving clinical outcomes.

Sufficient release of antibiotic by a spacer 6 weeks after implantation in two-stage revision of infected hip prostheses

BACKGROUND

Although antibiotic-loaded spacers are commonly used to treat periprosthetic infections, it is unclear whether spacers continue to release bactericidal levels of antibiotic 6 weeks after implantation.

QUESTIONS/PURPOSES

We asked whether an antibiotic can be detected in the tissue surrounding the spacer 6 weeks after implantation and whether the concentration is higher than the minimal inhibition concentration (MIC) previously determined for pathogens that are responsible for most periprosthetic infections.

METHODS

We removed 14 spacers used in two-stage septic revisions of infected hip prostheses 6 weeks after the primary implantations and determined the concentration of the antibiotics in the membrane formed between the spacer and the neighboring bone on the acetabular and the femoral sides. In seven cases Copal cement with gentamicin and clindamycin were used, and in seven other cases vancomycin was added to the Copal cement. Concentrations of the spacer antibiotics in the neighboring tissue were determined by tandem mass spectroscopy.

RESULTS

All three antibiotics were detected in concentrations higher than their MIC. There were no differences between the groups regardless whether vancomycin was added to the cement, or whether the cement was applied with the acetabular cup spacer or with the stem spacer.

CONCLUSIONS

We concluded that, using the spacer technique described in this study, 6 weeks after spacer implantation, the concentrations of antibiotic are sufficient to treat a periprosthetic infection.

Staged custom, intramedullary antibiotic spacers for severe segmental bone loss in infected total hip arthroplasty

Introduction. Total hip arthroplasty (THA) infections with severe bone loss pose significant reconstructive challenges. We present our experience with two-stage hip reimplantation using an intramedullary, antibiotic-impregnated nail. Methods. Three patients with infected THA with severe proximal femoral bone loss (Mallory type IIIB or greater) were treated using a custom antibiotic spacer. Clinical outcomes and any complications were recorded. Average followup was 49 months from final reimplantation. Results. Mean age at spacer placement (stage 1) was 53 years. The mean Harris Hip Score at final followup was 80. Two patients had asymptomatic heterotopic ossification, and one patient had a 2 cm leg-length discrepancy. Conclusions. A custom intramedullary nail antibiotic spacer is a reliable option in the staged management of the infected THA with severe proximal femoral bone loss. Benefits of this technique include limb salvage with maintenance of leg length, soft tissue tension, and functional status.

Structural allograft as an option for treating infected hip arthroplasty with massive bone loss

BACKGROUND

Revision of the infected hip arthroplasty with major bone loss is difficult. Attempts to restore bone stock with structural allograft are controversial.

QUESTIONS/PURPOSES

We assessed the (1) reinfection rate; (2) rerevision rate; (3) radiographic graft union, resorption, and implant migration; (4) Harris hip scores at 1 year and at last followup compared with before surgery; and (5) other major complications associated with the use of bulk structural allograft to treat massive bone loss in infected hip arthroplasty.

METHODS

We retrospectively reviewed 27 patients who underwent two-stage revision arthroplasty using structural allograft to treat massive bone defects in infected hip arthroplasty. There were 17 proximal femoral grafts, three acetabular major column grafts, two acetabular minor column grafts, and 10 cortical strut grafts used. Five patients had combinations of two allografts. The minimum followup was 1.1 years (mean, 8.2 years; range, 1.1-16.8 years).

RESULTS

One of 27 patients had reinfection. The Kaplan-Meier survivorship was 93% at 10 years with rerevision for aseptic loosening as the end point. Radiographically, three patients had nonunion at the graft-host junction. All patients except two had graft resorption, of which all were mild except two, which were severe. Three patients had implant migration. The mean modified Harris hip scores were 39.2 points (range, 25-60) preoperatively, 67.3 points (range, 40-91) at 1-year followup, and 70.3 points (range, 46-81) at last followup. Other major complications included one patient with dislocation and one patient with transient sciatic nerve injury.

CONCLUSIONS

Based on our data, we believe the use of structural allografts is a reasonable option for treating massive bone loss in infected hip arthroplasties.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

The effect of endoskeleton on antibiotic impregnated cement spacer for treating deep hip infection

Backgrounds

A two-stage revision arthroplasty was suggested optimal treatment for deep infections in hip joint. The effect of endoskeleton of cement spacers on the interim function and infection control remains unclear.

Methods

From Jan. 2004 to Dec. 2007, we collected a prospective cohort of consecutive 34 patients who treated with two-stage revision total hip arthroplasty for deep infection of hip joint. In group 1, fifteen patients were treated by a novel design augmented with hip compression screw while nineteen patients were treated by traditional design in group 2.

Results

No fracture of cement spacer occurred in group 1 while 6 cases developed spacer failure in group 2. (p < 0.05) There were significant differences in bodily pain and general health perception between groups (p < 0.05).

Conclusions

Patients being treated for deep infection of hip joint using cement spacer augmented with stronger endoskeleton have lower pain levels and better joint function between stages.

Vastus lateralis muscle flap for infected hips after resection arthroplasty

We evaluated the potential of a vastus lateralis muscle flap in controlling infection after resection arthroplasty of the hip. We retrospectively reviewed 119 patients with 120 chronic infections after resection arthroplasty treated with this procedure. The flap was fixed with Mitek anchors in the acetabular cavity. The mean duration of infection after resection before the muscle flap procedure was 6.5 months (2 to 13). The patients had previously undergone a mean of 4.9 operations (2 to 25). In all patients the infected cavity was the origin of the persistent infection. The mean follow-up was for 2.6 years (1.0 to 4.7). No patient had recurrent infection post-operatively and all had an improvement in the pain and better quality of life.

Improved antibiotic impregnated cement prosthesis for treating deep hip infection: a novel design using hip compression screw

A 2-stage revision arthroplasty has been suggested as the optimal treatment for deep infections in the hip joint. Improvement of the surgical technique to increase the interim function is subject to investigation. From 2004 to 2007, we collected a cohort of 15 consecutive patients who were treated by a novel design augmented with a modified hip compression screw. No fracture of the cement spacer occurred. We believe the modified hip compression screw is a good alternative for the functional endoskeleton of an antibiotic loaded cement prosthesis in the treatment of deep hip infection.