Aseptic Mechanical Failure Research Articles

Inadequate proximal screw fixation increases risk of failure following plate fixation of diaphyseal humerus fractures

BackgroundOperative treatment of humeral shaft fractures (AO/OTA 12) is being performed more frequently. Accordingly, it is important to understand the complications associated with plate fixation. This study analyzes risk factors associated with mechanical failure following plate fixation of humeral shaft fractures in order to further elucidate the mode and location of failure.MethodsA retrospective review of 351 humeral shaft fractures was completed at a single level I trauma center. Eleven of eighty-five humeral shaft fractures had aseptic mechanical failure requiring revision (12.9%), following initial plate fixation. Fracture characteristics (AO type, comminution, location) and fracture fixation (plate type, multiplanar, number of screws proximal and distal to the fracture) were compared between aseptic mechanical failure and those without failure. A forward stepwise logistic regression analysis was performed to determine any significant predictors of aseptic mechanical failure.ResultsThere was significant differences in fixation between the aseptic mechanical failure group and those without failure, specifically in the number of screws for proximal fixation (p = 0.008) and distal fixation (p = 0.040). In the aseptic mechanical failure group, patients tended to have less than < 8 cortices of proximal fixation (82%) and less than < 8 cortices of distal fixation (64%). Conversely, in patients without mechanical failure there was a tendency to have greater than > 8 cortices in both the proximal (62%) and distal fixation (70%). A forward stepwise logistic regression analysis found that less than < 8 cortices of proximal fixation was a significant predictor of aseptic failure, OR 7.96 (p = 0.011). We think this can be accounted for due to the variable bone quality, thinner cortices and multiple torsional forces in the proximal shaft that may warrant special consideration for fixation.ConclusionThe current dogma of humeral shaft fracture stabilization is to use a minimum of 3 screws proximal and distal to the fracture, however the current study demonstrates this is associated with higher rates of mechanical failure. In contrast, 4 bicortical screws or more of fixation on either side of the fracture had lower failure rates and may help to reduce the risk of mechanical failure.Level of Evidence Level III.

Long-term results and modern principles of prevention and treatment patients with endoprosthesis aseptic instability in oncology

Introduction.The results of using various reconstructive technologies in the 1980–1990’s to replace post-resection bone defects determined oncological endoprosthetics as the most promising onco-orthopedics trend, due to the quality-of-life and functional potential restoration in a short time. Despite the constant improvement of the design and technology of oncological endoprosthesis at the moment, complications such as aseptic instability, mechanical failure and infection of the endoprosthesis significantly affect the reduction of implant survival. It is impossible to reduce the frequency of endoprosthesis aseptic instability without developing a unified strategy for the prevention and treatment of this type of complication.The study objective – to examine the main causes of early and late aseptic loosening, analyze complication rate in various periods after endoprosthesis using literature data and results of treatment of a large patient group who underwent primary and repeat endoprosthesis for different post-resection bone defects.Materials and methods. The study included 1292 patients aged 10 to 81 years with primary bone and soft tissues sarcomas, metastatic, benign lesions of the bone, who since January 1992 to January 2020 were performed 1671 primary and revision endoprosthetics of various bone segments. The age of the patients ranged from 10 years to 81 years. The mean age of the patients was 34.7 years. In the study group of patients, most often endoprosthetics was performed at the age of 21 to 30 years and accounted for 29 % of cases. The mean follow-up period after primary arthroplasty of various segments was 82.8 months (from 0 to 335.7 months). The mean follow-up period after revision arthroplasty was 54.2 months (from 0 to 282.8 months). In 1594 (95.4 %) cases were used bone cement stem fixation.Results. The results of the study show that the optimal shape of the endoprosthesis stem for primary and revision endo-prosthesis replacement is conical and cylindrical figured (made in the shape of the bone marrow canal). The most stable endoprosthesis stems are 60–100 mm long for upper limb arthroplasty and 110–150 mm for lower limb arthroplasty. Endoprosthesis stems longer than 160 mm can only be used in revision endoprosthetics. The length of the bone resection does not affect the incidence of endoprosthesis instability. The quality of the formed cement mantle affects the frequency of endoprosthesis instability. The presence of at least one revision arthroplasty with replacement of the endoprosthesis stem increases the risk of developing subsequent early instability (type IIA) about 4 times and the risk of late instability (type IIB) about 6 times compared with primary arthroplasty. The occurrence of late aseptic instability of the endoprosthesis (type IIB) will lead to the development of breakage/destruction of the endoprosthesis (type IIIA) in a shorter period than the breakage/ destruction of the endoprosthesis will lead to the development of late instability of the endoprosthesis (type IIB).Conclusion. The choice of an endoprosthesis, taking into account the optimal biomechanics of the endoprosthesis design, the shape of the stem, methods of fixation, the introduction of innovative technological solutions, adherence to the principles of oncological endoprosthesis replacement, is a means of reducing the incidence of this type of complications.

Minimum five-year outcomes of reverse total shoulder arthroplasty using a trabecular metal glenoid base plate

Reverse total shoulder arthroplasty (RTSA) using trabecular metal (TM)-backed glenoid implants has been introduced with the aim to increase implant survival. Only short-term reports on the outcomes of TM-RTSA have been published to date. We aim to present the seven-year survival of TM-backed glenoid implants along with minimum five-year clinical and radiological outcomes. All consecutive elective RTSAs performed at a single centre between November 2008 and October 2014 were reviewed. Patients who had primary TM-RTSA for rotator cuff arthropathy and osteoarthritis with deficient cuff were included. A total of 190 shoulders in 168 patients (41 male, 127 female) were identified for inclusion at a mean of 7.27 years (SD 1.4) from surgery. The primary outcome was survival of the implant with all-cause revision and aseptic glenoid loosening as endpoints. Secondary outcomes were clinical, radiological, and patient-related outcomes with a five-year minimum follow-up. The implant was revised in ten shoulders (5.2%) with a median time to revision of 21.2 months (interquartile range (IQR) 9.9 to 41.8). The Kaplan-Meier survivorship estimate at seven years was 95.9% (95% confidence interval (CI) 91.7 to 98; 35 RTSAs at risk) for aseptic mechanical failure of the glenoid and 94.8% (95% CI 77.5 to 96.3; 35 RTSAs at risk) for all-cause revision. Minimum five-year clinical and radiological outcomes were available for 103 and 98 RTSAs respectively with a median follow-up time of six years (IQR 5.2 to 7.0). Median postoperative Oxford Shoulder Score was 38 (IQR 31 to 45); median Constant and Murley score was 60 (IQR 47.5 to 70); median forward flexion 115° (IQR 100° to 125°); median abduction 95° (IQR 80° to 120°); and external rotation 25° (IQR 15° to 40°) Scapular notching was seen in 62 RTSAs (63.2%). We present the largest and longest-term series of TM-backed glenoid implants demonstrating 94.8% all-cause survivorship at seven years. Specifically pertaining to glenoid loosening, survival of the implant increased to 95.9%. In addition, we report satisfactory minimum five-year clinical and radiological outcomes. Cite this article: Bone Joint J2021;103-B(8):1333-1338.

Compressive osseointegration for endoprosthetic reconstruction.

This review summarizes the biomechanical concepts, clinical outcomes and limitations of compressive osseointegration fixation for endoprosthetic reconstruction. Compressive osseointe - gration establishes stable fixation and integration through a novel mechanism; a Belleville washer system within the spindle applies 400-800 PSI force at the boneimplant interface. Compressive osseointegration can be used whenever standard endoprosthetic reconstruction is indicated. However, its mode of fixation allows for a shorter spindle that is less limited by the length of remaining cortical bone. Most often compressive osseointegration is used in the distal femur, proximal femur, proximal tibia, and humerus but these devices have been customized for use in less traditional locations. Aseptic mechanical failure occurs earlier than with standard endoprosthetic reconstruction, most often within the first two years. Compressive osseointegration has repeatedly been proven to be non-inferior to standard endoprosthetic reconstruction in terms of aseptic mechanical failure. No demographic, device specific, oncologic variables have been found to be associated with increased risk of aseptic mechanical failure. While multiple radiographic parameters are used to assess for aseptic mechanical failure, no suitable method of evaluation exists. The underlying pathology associated with aseptic mechanical failure demonstrates avascular bone necrosis. This is in comparison to the bone hypertrophy and ingrowth at the boneprosthetic interface that seals the endosteal canal, preventing aseptic loosening.

Radiographic parameter-driven decision tree reliably predicts aseptic mechanical failure of compressive osseointegration fixation

Background and purpose — Compressive osseointegration fixation is an alternative to intramedullary fixation for endoprosthetic reconstruction. Mechanical failure of compressive osseointegration presents differently on radiographs than stemmed implants, therefore we aimed to develop a reliable radiographic method to determine stable integration.Patients and methods — 8 reviewers evaluated 11 radiographic parameters from 29 patients twice, 2 months apart. Interclass correlation coefficients (ICCs) were used to assess test–retest and inter-rater reliability. We constructed a fast and frugal decision tree using radiographic parameters with substantial test–retest agreement, and then tested using radiographs from a new cohort of 49 patients. The model’s predictions were compared with clinical outcomes and a confusion matrix was generated.Results — 6 of 8 reviewers had non-significant intra-rater ICCs for ≥ one parameter; all inter-rater ICCs were highly reliable (p < 0.001). Change in length between the top of the spindle sleeve and bottom of the anchor plug (ICC 0.98), bone cortex hypertrophy (ICC 0.86), and bone pin hypertrophy (ICC 0.81) were used to create the decision tree. The sensitivity and specificity of the training cohort were 100% (95% CI 52–100) and 87% (CI 74–94) respectively. The decision tree demonstrated 100% (CI 40–100) sensitivity and 89% (CI 75–96) specificity with the test cohort.Interpretation — A stable spindle length and at least 3 cortices with bone hypertrophy at the implant interface predicts stable osseointegration; failure is predicted in the absence of bone hypertrophy at the implant interface if the pin sites show hypertrophy. Thus, our decision tree can guide clinicians as they follow patients with compressive osseo­integration implants.

Plasma Fibrin Degradation Product and D-Dimer Are of Limited Value for Diagnosing Periprosthetic Joint Infection

BackgroundAlthough the Musculoskeletal Infection Society introduced the use of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) as inflammatory markers for diagnosing periprosthetic joint infection (PJI), no single blood marker reliably detects infection before revision arthroplasty. We therefore posed 2 questions: (1) Are fibrin degradation product (FDP) and D-dimer of value for diagnosing PJI before revision arthroplasty? (2) What are their sensitivity and specificity for that purpose? MethodsTo answer these questions, we retrospectively enrolled 318 patients (129 with PJI [group A], 189 with aseptic mechanical failure [group B]) who underwent revision arthroplasty during 2013-2018. Receiver operating characteristic curves were used to determine maximum sensitivity and specificity of the 2 markers. Inflammatory and fibrinolytic markers were evaluated based on (1) the Tsukayama-type infection present and (2) the 3 most common PJI-related pathogens. ResultsFDP and D-dimer levels were higher in group A than in group B: 4.97 ± 2.83 vs 4.14 ± 2.67 mg/L and 2.14 ± 2.01 vs 1.51 ± 1.37 mg/L fibrinogen equivalent units (FEU), respectively (both P < .05). Based on the Youden index, 2.95 mg/L and 1.02 mg/L FEU are the optimal FDP and D-dimer predictive cutoffs, respectively, for diagnosing PJI. Sensitivity and specificity, respectively, were 65.12% and 60.33% (FDP) and 68.29% and 50.70% (D-dimer). ESR, CRP, and interleukin-6 values were diagnostically superior to those of FDP and D-dimer. ConclusionThe value of plasma FDP and D-dimer for diagnosing PJI is limited compared with traditional inflammatory markers (ESR, CRP, interleukin-6) before revision arthroplasty.

Uncemented, curved, short endoprosthesis stem for distal femoral reconstruction: early follow-up outcomes

BackgroundUncemented endoprosthetic knee replacement has become a mainstream treatment for malignant tumours of the distal femur. Most femoral stems, however, are straight and therefore poorly fit the anteriorly bowed curvature of the femur. To address this issue, we used a short, curved, uncemented press-fit femoral stem and evaluated its short-term outcomes after reconstruction of the distal femur.MethodsForty-two patients underwent distal femur replacement using curved press-fit stem. To assess the interface, we measured the axial length of the press-fit area and the perpendicular distance of the radiolucent area between the stem and bone on digital images obtained using tomosynthesis with Shimadzu Metal Artefact Reduction Technology (T-SMART). Postoperative complications and oncological outcomes were monitored at each follow-up visit.ResultsOf the 42 patients enrolled in the study, two had cancer-related deaths and one had local tumour recurrence. The minimum follow-up time of the surviving patients was 24 months, with no incidence of aseptic loosening or mechanical failure of the prosthesis. The average effective contact length between the press-fit stem and bone was 74.0 mm, with nearly undetectable radiolucent gaps between the implant and the bone on medial-lateral and anteroposterior views.ConclusionsOver the short term, uncemented, curved, short stem provides a stable bone-prosthesis interface without any aseptic loosening.

Is there a time delay to achieve stable compressive osseointegration fixation?

Compressive osseointegration fixation using the Compress® is an alternative to traditional intramedullary fixation for endoprosthetic reconstruction. This study aims to evaluate if there is a time delay to achieve stable compressive osseointegration fixation.What is your aim?Current manufacturer recommendations call for 6 weeks of limited weight bearing and limited published research suggests increased early aseptic failure. Between 2006 and 2014, surgeons at one center treated 116 patients with 137 Compress® implants for lower extremity oncologic reconstruction, revision arthroplasty, and fracture nonunion or malunion. Patients were prescribed limited weight bearing for 6 weeks as per manufacturer recommendations and we report on outcome after 116 implants were available for review with a minimum of 2-year follow up (mean 4 years; range 2-9 years). Kaplan-Meier survival plots with 95% Hall-Wellner bands were produced;, survivorship free from overall and aseptic failure at 2 months, 6 months, 1 year and 2 year time points was calculated along with 95% confidence intervals. The relationship with time was further examined via extended Cox pProportion hHazard models. Twenty-seven failures (including 6 aseptic failures) occurred among the 116 implants. Survivorship free from overall failure at 2 months was 92% (95% CI, 84%-100%) for proximal femur reconstructions, 98% (95% CI, 95%-100%) for distal femur reconstructions, and 100% for proximal tibia reconstructions. No aseptic failures were observed prior to 2 months in any group, with the first aseptic failure occurring at 81 days. Extended Cox pProportional hazards modeling demonstrated differences in hazard ratio (HR) by location (p=0.049) with an increased hazard for the proximal tibia group relative to the distal tibia group (HR=4.42, p=0.052) for overall failure but not aseptic mechanical failure. Only the overall failure showed a time dependent interaction (p value=0.008), reflecting that the increased hazard for the proximal tibia group occurred at 4-6 months, with no failures after this point. We were unable to identify a clear temporality for aseptic failure and compressive osseointegration fixation in our patient series and . The 6-week post-operative time point showed no relationship with increased risk of failure. More research is necessary to understand the early biomechanical stability of compressive osseointegration fixation and its ability to withstand physiologic loads, i.e. immediate weight-bearing, prior to biologic osseointegration.

Twelve-Year Outcomes of an Oxinium Total Knee Replacement Compared with the Same Cobalt-Chromium Design

Oxidized zirconium (Oxinium) was introduced as an alternative bearing surface to cobalt-chromium (CoCr) in an attempt to reduce polyethylene wear and decrease aseptic mechanical failure of total knee replacements. While noncomparative reports have been described as promising, we were aware of no short or long-term clinical studies showing the superiority of Oxinium on polyethylene as a bearing surface. Using data from a comprehensive national joint replacement registry, we compared the long-term outcomes after cruciate-retaining total knee arthroplasty (TKA) with an Oxinium femoral component and those with the same prosthetic design but with a CoCr femoral component. The cohorts consisted of 17,577 cemented Genesis-II cruciate-retaining total knee replacements using non-cross-linked polyethylene, which included 11,608 with CoCr femoral components and 5,969 with Oxinium femoral components. The cumulative percent revision and hazard ratio (HR) for revision risk were estimated for the cemented Genesis-II Oxinium and CoCr cruciate-retaining TKAs performed in Australia from September 1, 1999, to December 31, 2013. In addition, the revision diagnoses and the effects of age and patellar resurfacing were examined. No difference in the HR for revision risk was found between the Oxinium and CoCr cohorts for any age category for all causes of revision (HR = 0.92 [95% confidence interval (CI), 0.92 to 1.29]; p = 0.329), loosening or lysis, or aseptic causes, except for loosening or lysis in the group of patients who were ≥75 years old (p = 0.033). In these patients, TKA with Oxinium femoral components had a higher rate of revision. Younger patients preferentially received Oxinium femoral components. The revision risk was not affected by patellar resurfacing or nonresurfacing. At 12 years, the cumulative percent revision was 4.8% (95% CI, 4.2% to 5.4%) for the CoCr Genesis-II prosthesis compared with 7.7% (95% CI, 6.2% to 9.5%) for the Oxinium Genesis-II prosthesis. In this cohort study involving the same prosthetic design, Oxinium femoral components did not reduce revision rates for all causes, loosening or lysis, or when infection as a cause of revision was removed compared with the same CoCr femoral component across all age groups including patients who were <55 years old. The cumulative percent revision was greater for the Oxinium components than for the CoCr components. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Total Knee Arthroplasty in the Younger Patient.

The rate of total knee arthroplasty (TKA) utilization in younger patients (< 65 years old) is increasing. Little is known regarding demographics and in-hospital outcomes in this population. The National Hospital Discharge Survey (NHDS) database was searched using International Classification of Diseases, Ninth Revision (ICD-9) procedure codes for patients admitted to U.S. hospitals for unilateral primary TKA between 2001 and 2010. Patients were separated into young (< 65 years of age) and senior cohorts (≥ 65 years of age). ICD-9 diagnosis and procedure codes were used to identify demographics, hospital length of stay, in-hospital adverse events, mortality, and discharge disposition. Trends were evaluated by linear regression with Pearson correlation coefficient (r) and statistical comparisons were made using Student t-test and chi-square analysis. The young cohort accounted for 38.4% of TKAs performed from 2001 to 2005, increasing to 42.7% of TKAs from 2006 to 2010. They had a higher percentage of males (36.4 vs. 34.2%, p < 0.001). Rates of obesity (11.1 vs. 6.0%, p < 0.001) and morbid obesity (5.8 vs. 1.9%, p < 0.001) were significantly higher, yet they had less comorbidities (4.7 vs. 5.2, p < 0.001), and lower rates of transfusion (12.2 vs. 19.8%, p < 0.001), pulmonary embolism (PE) (0.31 vs. 0.49%, p < 0.020), and mortality (0.03 vs. 0.18%, p < 0.001). Patients < 65 years old undergoing TKA have almost double the rate of obesity of patients ≥ 65 years old. This could explain the higher rates of periprosthetic infection and aseptic mechanical failure seen in younger patients. However, the young cohort had a more favorable discharge disposition and lower mortality and risk of PE than elderly patients.

Reverse total shoulder arthroplasty using a trabecular metal glenoid base plate: functional and radiological outcomes at two to five years.

We present the medium-term clinical results of a reverse total shoulder arthroplasty with a trabecular metal glenoid base plate. We reviewed 125 consecutive primary reverse total shoulder arthroplasties (RTSA) implanted in 124 patients for rotator cuff arthropathy. There were 100 women and 24 men in the study group with a mean age of 76 years (58 to 89). The mean follow-up was 32 months (24 to 60). No patient was lost to follow-up. There were statistically significant improvements in the mean range of movement and Oxford Shoulder Score (p < 0.001). Kaplan-Meier survivorship at five years was 96.7% (95% confidence interval 91.5 to 98.7) with aseptic glenoid failure as the end point. Radiologically, 63 shoulders (50.4%) showed no evidence of notching, 51 (40.8%) had grade 1 notching, ten (8.0%) had grade 2 notching and one (0.8%) had grade 4 notching. Radiolucency around the glenoid base plate was found in one patient (0.8%) and around the humeral stem in five (4.0%). In all, three RTSA (2.4%) underwent revision surgery for aseptic mechanical failure of the glenoid within 11 months of surgery due to malseating of the glenosphere. The clinical results of this large independent single unit series are comparable to those from previous series of RTSA reported in the literature. A trabecular metal base plate is safe and effective in the medium-term. Cite this article: Bone Joint J 2016;98-B:969-75.

What Factors Are Associated With Failure of Compressive Osseointegration Fixation?

Compressive osseointegration is as an alternative to traditional intramedullary fixation. Two- to 10-year survivorship and modes of failure have been reported; however, as a result of relatively small numbers, these studies are limited in their ability to identify risk factors for failure. (1) What is survivorship free from aseptic mechanical and survivorship free from overall failure of compressive osseointegration fixation? (2) What patient factors (age, sex, body mass index [BMI], anatomic location of reconstruction, indication for reconstruction, radiation, chemotherapy) are associated with increased risk of failure? Between 2006 and 2014, surgeons at one center treated 116 patients with 137 Compress® implants for lower extremity oncologic reconstructions, revision arthroplasty, and fracture nonunion or malunion. One hundred sixteen implants were available for review with a minimum of 2-year followup (mean, 4 years; range, 2-9 years). Kaplan-Meier survival plots were produced to examine survivorship and Cox regression modeling was used to generate hazard ratios (HRs) for potential risk factors for failure. Patient factors (age, sex, BMI, anatomic location of reconstruction, indication for reconstruction, radiation, chemotherapy) were obtained from chart review and an institutional database. Survivorship free from aseptic mechanical failure was 95% (95% confidence interval [CI], 91%-99%) at 18 months and 93% (95% CI, 86%-99%) at 4 years. Survivorship free from overall failure was 82% (95% CI, 75%-89%) at 18 months and 75% (95% CI, 66%-84%) at 4 years. Risk of overall failure was increased with reconstruction of the proximal tibia (HR, 4.42; 95% CI 0.98-19.9) and distal femur (HR, 1.74; 95% CI, 0.50-6.09) compared to the proximal femur (HR, 1; referent; p = 0.049). Risk of aseptic mechanical failure was increased with reconstruction of the proximal tibia (HR, 1; referent) and distal femur (HR, 0.37; 95% CI, 0.08-1.77) compared with the proximal femur (HR, 0, p = 0.048). Radiation was associated with increased risk of overall failure (HR, 3.85; 95% CI, 1.84-8.02; p < 0.003), but not aseptic mechanical failure. Age, sex, BMI, chemotherapy, and surgical indication were not associated with increased risk of aseptic or overall failure. This study questions the use of age as a contraindication for the use of this technology and suggests this technology may be considered in proximal femoral reconstruction and for patients with indications other than primary oncologic reconstructions. Future research should establish long-term survivorship data to compare this approach with conventional intramedullary stems and to evaluate the potential benefits of preventing stress shielding and preserving bone stock in revision situations. Level III, therapeutic study.

Younger Age Is Associated with a Higher Risk of Early Periprosthetic Joint Infection and Aseptic Mechanical Failure After Total Knee Arthroplasty

Although early aseptic mechanical failure after total knee arthroplasty has been reported in younger patients, it is unknown whether early revision due to periprosthetic joint infection is more or less frequent in this patient subgroup. The purpose of this study was to determine whether the incidence of early periprosthetic joint infection requiring revision knee surgery is significantly different in patients younger than fifty years of age compared with older patients following primary unilateral total knee arthroplasty. A large population-based study was conducted with use of the California Patient Discharge Database, which allows serial linkage of all discharge data from nonfederal hospitals in the state over time. Patients undergoing primary unilateral total knee arthroplasty during 2005 to 2009 were identified. Principal outcomes were partial or complete revision arthroplasty due to periprosthetic joint infection or due to aseptic mechanical failure within one year. Multivariate analysis included risk adjustment for important demographic and clinical variables. The effect of hospital total knee arthroplasty volume on the outcomes of infection and mechanical failure was analyzed with use of hierarchical modeling. At one year, 983 (0.82%) of 120,538 primary total knee arthroplasties had undergone revision due to periprosthetic joint infection and 1385 (1.15%) had undergone revision due to aseptic mechanical failure. The cumulative incidence in patients younger than fifty years of age was 1.36% for revision due to periprosthetic joint infection and 3.49% for revision due to aseptic mechanical failure. In risk-adjusted models, the risk of periprosthetic joint infection was 1.8 times higher in patients younger than fifty years of age (odds ratio = 1.81, 95% confidence interval = 1.33 to 2.47) compared with patients sixty-five years of age or older, and the risk of aseptic mechanical failure was 4.7 times higher (odds ratio = 4.66, 95% confidence interval = 3.77 to 5.76). The rate of revision due to infection at hospitals in which a mean of more than 200 total knee arthroplasties were performed per year was lower than the expected (mean) value (p = 0.04). Patients younger than fifty years of age had a significantly higher risk of undergoing revision due to periprosthetic joint infection or to aseptic mechanical failure at one year after primary total knee arthroplasty.

The use of receiver operating characteristics analysis in determining erythrocyte sedimentation rate and C-reactive protein levels in diagnosing periprosthetic infection prior to revision total hip arthroplasty

Periprosthetic infection (PPI) is a difficult complication in total joint arthroplasty, and while erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are acute phase reactants thought to be of high predictive value for diagnosing infection, no clear cut-off values have been defined. The current study aimed to determine the cut-off values for ESR and CRP that improve clinical differentiation between aseptic failure and PPI in total hip arthroplasty (THA). Four hundred and seventy-nine patients who underwent revision THA for either aseptic mechanical failure or PPI during the period of 2000 to 2005 were included in the study. Specific exclusion criteria were applied to eliminate inflammatory or other confounding conditions. All patients underwent preoperative testing of ESR and CRP. Receiver operating characteristic (ROC) curves were constructed to determine maximum sensitivity and specificity. Patients with PPI had significantly higher ESR and CRP values compared to patients undergoing revision for aseptic etiologies. An ESR threshold of 30 mm/h gave a sensitivity of 94.3% and a CRP threshold of 10 mg/l gave a sensitivity of 91.1%. Combining both ESR and CRP cut-offs for a positive diagnosis increased the sensitivity to 97.6%. However, when calculated by ROC analysis, the predictive cut-offs equated to 31 mm/h for ESR and 20.5 mg/l for CRP. The gold standard for diagnosing PPI remains bacterial culture, but sensitivity is negatively affected by prior antibiotic exposure, strongly adherent bacteria, slow growing persisters, and biofilms. ESR and CRP are reflective of systemic changes in infection and pose an attractive, less invasive alternative with reasonable sensitivity and specificity. The current study is the first to identify ideal cut-off values for ESR and CRP in THA patients, providing an optimum balance between sensitivity and specificity based on ROC curves.

Inflammatory response in 85 patients with loosened hip prostheses: A prospective study comparing inflammatory markers in patients with aseptic and septic prosthetic loosening

Background The most common complications of prosthetic hip joints are aseptic mechanical failure and infection. Delayed low-grade infections are seen most often, and they are also most difficult to distinguish from aseptic mechanical failures.Methods We conducted a prospective study to compare inflammatory markers in patients diagnosed with aseptic or septic prosthetic loosening. The diagnostic criteria were based on the decisions of experienced orthopedic surgeons and microbiological analysis of periprosthetic tissue samples taken perioperatively.Results Coagulase-negative staphylococci were the commonest pathogens in the infected patients. Pre- or perioperative elevation of C-reactive protein and erythrocyte sedimentation rate were significantly greater in the infection group, as were white blood cell count and levels of cytokines in synovial fluid. The patterns of infiltration of inflammatory cells in periprosthetic tissue were also significantly different between the groups.Interpretation A combination of clinical judgment and multiple tissue samples constitutes a good platform for distinguishing between septic and aseptic loosening of prostheses. Moreover, the combined use of several laboratory and histopathological markers of inflammation, especially infiltration of polymorphonuclear cells, further helps the diagnosis.