Timothy L. Tan

The Fate of Spacers in the Treatment of Periprosthetic Joint Infection

BACKGROUND Two-stage exchange arthroplasty remains the preferred method to treat periprosthetic joint infection. The aim of this study was to investigate the clinical course of periprosthetic joint infection following resection arthroplasty and insertion of a spacer. METHODS Our institutional database was used to identify 504 cases of periprosthetic joint infection (326 knees and 178 hips) treated with resection arthroplasty and spacer insertion as part of a two-stage exchange arthroplasty. A review of the patient charts was performed to extract information relevant to the objectives of this study that included the details of the clinical course following resection arthroplasty. RESULTS The mean follow-up duration after initial spacer implantation was 56.2 months. Reimplantation occurred in the joints of 417 (82.7%) of 504 cases. Of these 417 cases, 329 (78.9%) had a minimum one-year follow-up, and 81.4% of these had successful treatment. The mean duration from resection arthroplasty to reimplantation was 4.2 months (range, 0.7 to 131.7 months). Sixty (11.9%) of the 504 joints required interim spacer exchange(s). Of the eighty-seven cases that did not undergo reimplantation, six (6.9%) required amputation, five (5.7%) underwent a Girdlestone procedure, four (4.6%) underwent arthrodesis, and seventy-two (82.8%) underwent spacer retention. Thirty-six patients died in the interstage period. CONCLUSIONS The commonly held belief that two-stage exchange arthroplasty carries a high success rate for the eradication of periprosthetic joint infection may need to be reexamined. A considerable number of patients undergoing the first stage of a two-stage procedure do not undergo a subsequent reimplantation for a variety of reasons or require an additional spacer exchange in the interim. Reports on the success of two-stage exchange should account for the mortality of these patients and for patients who never undergo reimplantation.

The absence of a metal-on-metal bearing does not preclude the formation of a destructive pseudotumor in the hip—a case report

In 2009, a 62-year-old woman with rheumatoid arthritis and a total hip arthroplasty (THA) on the right (uncemented Ti-6AL-7Nb stem combined with a Ti threaded cup, polyethylene inlay, and a 28-mm ceramic head; Zweymuller Alloclassic; Zimmer Orthopaedics, Warsaw, IN) implanted in 2006 presented with a left femoral neck fracture. A THA with a double-mobility acetabular system (Avantage Double-Mobility Acetabular System; Biomet, Warsaw, IN) was implanted. An uncemented titanium-niobium (Ti-6Al-7Nb) stem was used (Zweymuller Alloclassic; Zimmer) with a 12/14 mm trunnion combined with an XXL (+10.5 mm) 28-mm cobalt-chromium head with a 12/14 mm tapered bore (Biomet). The femoral head was introduced into the highly cross-linked, vitamin E-stabilized polyethylene bearing using a bearing press. An uncemented Ti HA-coated 52-mm acetabular shell was press-fitted in the socket and the large polyethylene femoral head was reduced into the metal articular surface. Postoperative recovery was uneventful, with normal wound healing. 2 years after implantation, the patient was referred to our center by her rheumatologist, since a soft tissue mass adjacent to the left THA had been diagnosed by ultrasound. A standard AP pelvic radiograph revealed adequate positioning of both hip implants without any signs of wear or osteolysis. Subsequent MARS-MRI scanning confirmed the presence of a 6 × 9 cm soft tissue mass at the posterolateral aspect of the left greater trochanter (Figure 1). There were no signs of any soft tissue reaction around the contralateral THA. Figure 1. Standard AP radiograph (panel A) and MARS-MRI scan (panel B) 2 years after implantation of the left THA with a double-mobility acetabular component. Note the adequate implant positioning and fixation (A) and a 6 × 9 cm soft tissue mass (B) at ... CRP was 68 mg/L and ESR was 53 mm/h; both were elevated, but this was possibly related to her rheumatoid arthritis. An inductively-coupled plasma mass spectrometer (ICP-MS) was used for evaluation of metal ion levels. Serum levels of chromium were below the detection level of 0.5µg/L, whereas cobalt serum levels were 5.7 µg/L. An aspirate of the hip joint was negative for bacterial or fungal growth. The patient was diagnosed as having a severe and early “adverse local tissue reaction” (ALTR) after a metal-on-polyethylene bearing THA with the taper as the potential source of the metal ion release. 2.5 years after implantation, a debulking procedure of the pseudotumor in combination with a 1-stage revision of the femoral component was performed. Perioperatively, extensive tissue necrosis and partial destruction of the abductor mechanism were found in the absence of any macroscopic signs of infection. The acetabular component was well fixed. Both the femoral trunnion and bore of the head showed signs of black debris (Figure 2). The femoral component was revised to a cemented polished straight stem (Exeter; Stryker, Allendale, NJ) with a ceramic 28-mm head (also Stryker) and a new double-mobility liner (Avantage Double-Mobility Acetabular System; Biomet). At the revision operation, 6 tissue samples were taken for bacterial culture according to our protocol. All 6 samples were negative for bacterial growth. Figure 2. A. Extensive necrosis at the greater trochanter area and destruction of the abductor mechanism. B. Debulking of large amounts of necrotic and fibrotic tissue from the periprosthetic region. C and D. Macroscopic signs of corrosion products at the bore ... The revision procedure was complicated by a deep infection that was unresponsive to lavage and prolonged antibiotic treatment. 2 months after revision, all components had to be removed, resulting in a (temporary) Girdlestone situation. The components were sent for retrieval analysis. Multiple samples of the periprosthetic tissues were processed in paraffin for routine histology. The histopathology of tissue samples revealed extensively necrotic material with only a focal cellular area of inflammatory cells containing macrophages, plasma cells, occasional foci of eosinophils, and several small perivascular lymphocytic aggregates (Figure 3). No polarizable materials or metallic debris were present in several tissue samples. The ALVAL score (Campbell et al. 2010) was 3 + 3 + 2 (= 8/10, moderate). Overall, the histological profile was consistent with an adverse immunological reaction in the absence of visible wear debris. Figure 3. A. Histological view of the soft tissue mass at the interface between the necrotic material (on the joint side) and inflammatory cells. Hematoxylin and eosin (HE), 40×. B. Enlargement of A with inflammatory cells consisting mainly of macrophages ... The profile of the ball taper was measured using a coordinate measuring machine (Legex 322; Mitotoyo, Aurora, IL). The dimensions of a perfect taper based on 6726 CMM points with a point spacing of 0.3 mm were determined using a least-squares method. The taper had an angle of 5 degrees, 47 min, and 34 s. A contour map was generated using the deviations of the CMM points from the fitting taper (Figure 4). The CMM results indicated uneven areas of contact, but the amount of material that had been removed through wear or corrosion could not be determined without knowing the initial form of the parts. However, in combination with the microanalysis described below, it appears that the small degree of texture and color changes was consistent with mild corrosion Figure 4. A. 2-dimensional graphical representation of the same profile. The outer diameter of the CMM map is the portion of the taper closest to the stem (labeled Rim) and the inner diameter of the CMM image corresponds to the inner surface (labeled Bottom). Areas ... The area of the stem trunnion that appeared discolored was examined by scanning electron microscopy (SEM) and energy-dispersive analysis of X-rays (EDAX) to identify the elements present. Organic material containing chromium and/or molybdenum consistent with corrosion products was identified within the machined grooves and in the deposited dark material outside the trunnion (Figure 5). Similar analysis performed on deparaffinized soft tissue sections failed to demonstrate any wear or corrosion products. Figure 5. Material present on the trunnion of the femoral component (panel A) was investigated by EDAX, revealing chromium (Cr), molybdenum (Mo), and oxygen (O) peaks consistent with corrosion products (panel B). The organic material within the grooves containing ...

Can Wear Explain the Histological Variation Around Metal-on-metal Total Hips?

BackgroundThere is a general perception that adverse local tissue reactions in metal-on-metal hip arthroplasties are caused by wear, but the degree to which this is the case remains controversial.Questions/purposesTo what extent is the magnitude of wear associated with (1) the histological changes; (2) presence of metallosis; and (3) likelihood of pseudotumor formation in the periprosthetic tissues?MethodsOne hundred nineteen metal-on-metal total hip arthroplasties and hip resurfacings were selected from a retrieval collection of over 500 implants (collected between 2004 and 2012) based on the availability of periprosthetic tissues collected during revision, clinical data including presence or absence of pseudotumor or metallosis observed intraoperatively, and wear depth measured using a coordinate measurement machine. Histological features of tissues were scored for aseptic lymphocytic vasculitis-associated lesions (ALVAL). Correlation analysis was performed on the three endpoints of interest.ResultsWith the sample size available, no association was found between wear magnitude and ALVAL score (ρ = −0.092, p = 0.423). Median wear depth (ball and cup) was greater in hips with metallosis (137 μm; range, 8–873 μm) than in those without (18 μm; range, 8–174 μm; p < 0.0001). With the numbers available, no statistically significant association between wear depth and pseudotumor formation could be identified; median wear depth was 74 μm in hips with pseudotumors and 26 μm in those without (p = 0.741).ConclusionsWear alone did not explain the histopathological changes in the periprosthetic tissues. A larger sample size and more sensitive outcome variable assessments may have revealed a correlation. However, wear depth has been inconsistently associated with pseudotumor formation, perhaps because some patients with hypersensitivity may develop pseudotumors despite low wear.Clinical RelevanceMetal wear alone may not explain the histological reactions and pseudotumors around metal-on-metal hip implants.

In-Hospital Mortality in Patients With Periprosthetic Joint Infection

BACKGROUND While periprosthetic joint infection (PJI) has a huge impact on patient function and health, only a few studies have investigated its impact on mortality. The purpose of this large-scale study was to (1) determine the rate and trends of in-hospital mortality for PJI and (2) compare the in-hospital mortality rate of patients with PJI and those undergoing revision arthroplasty for aseptic failure and patients undergoing other nonorthopedic major surgical procedures. METHODS Data from the Nationwide Inpatient Sample from 2002 to 2010 were analyzed to determine the risk of in-hospital mortality for PJI patients compared with aseptic revision arthroplasty. The Elixhauser comorbidity index was used to obtain patient comorbidities. Multiple logistic regression analyses were used to examine whether PJI and other patient-related factors were associated with mortality. RESULTS PJI was associated with an increased risk (odds ratio, 2.05; P < .0001) of in-hospital mortality (0.77%) compared with aseptic revisions (0.38%). The in-hospital mortality rate of revision total hip arthroplasties with PJI was higher than those for interventional coronary procedures (1.22%; 95% confidence interval [CI], 1.20-1.24), cholecystectomy (1.13%; 95% CI, 1.11-1.15), kidney transplant (0.70%; 95% CI, 0.61-0.79), and carotid surgery (0.89%; 95% CI, 0.86-0.93). CONCLUSION Patients undergoing treatment for PJI have a 2-fold increase in in-hospital mortality for each surgical admission compared to aseptic revisions. Considering that PJI cases often have multiple admissions and that this analysis is by surgical admission, the risk of mortality will accumulate for every additional surgery. Surgeons should be cognizant of the potentially fatal outcome of PJI and the importance of infection control to reduce the risk of mortality.

Patients With Failed Prior Two-Stage Exchange Have Poor Outcomes After Further Surgical Intervention

BACKGROUND Failure of 2-stage exchange arthroplasty for the management of periprosthetic joint infection (PJI) poses a major clinical challenge. There is a paucity of information regarding the outcomes of further surgical intervention in these patients. Thus, we aim to report the clinical outcomes of subsequent surgery for a failed prior 2-stage exchange arthroplasty. METHODS Our institutional database was used to identify 60 patients (42 knees and 18 hips), with a failed prior 2-stage exchange, who underwent further surgical intervention between 1998 and 2012, and had a minimum 2-year follow-up. A retrospective review was performed to extract relevant clinical information, including mortality, microbiology, and subsequent surgeries. Musculoskeletal Infection Society criteria were used to define PJI, and treatment success was defined using Delphi criteria. RESULTS Irrigation and debridement (I&D) was performed after a failed 2-stage exchange in 61.7% of patients; 56.8% subsequently failed. Forty patients underwent an intended second 2-stage exchange; 6 cases required a spacer exchange. Reimplantation occurred only in 65% of cases, and 61.6% had infection controlled. The 14 cases that were not reimplanted resulted in 6 retained spacers, 5 amputations, 2 PJI-related mortalities, and 1 arthrodesis. CONCLUSION Further surgical intervention after a failed prior 2-stage exchange arthroplasty has poor outcomes. Although I&D has a high failure rate, many patients who are deemed candidates for a second 2-stage exchange either do not undergo reimplantation or fail after reimplantation. The management of PJI clearly remains imperfect, and there is a dire need for further innovations that may improve the care of these patients.

Positive Culture During Reimplantation Increases the Risk of Subsequent Failure in Two-Stage Exchange Arthroplasty

BACKGROUND It is strongly recommended that tissue and synovial fluid culture samples be obtained during reimplantation performed as part of a 2-stage exchange arthroplasty. The rate of positive cultures during reimplantation and the influence of positive cultures on subsequent outcomes, to our knowledge, are unknown. This study was designed to determine the rate of positive cultures during reimplantation and to investigate the association between positive cultures at reimplantation and subsequent outcomes. METHODS We retrospectively reviewed the data of 259 patients who met the Musculoskeletal Infection Society criteria for periprosthetic joint infection (PJI) and who underwent both stages of 2-stage exchange arthroplasty at our institution from 1999 to 2013. Among these patients were 267 PJIs (186 knees and 81 hips); 33 (12.4%) had ≥1 positive culture result at reimplantation. Treatment failure was assessed according to the Delphi-based consensus definition. Logistic regression analysis was performed to assess the predictors of positive culture and risk factors for failure of 2-stage exchange arthroplasty. RESULTS Of the 33 cases with PJI, 15 (45.5%) had a subsequent failure of the 2-stage exchange arthroplasty compared with 49 (20.9%) of the cases that were culture-negative at reimplantation. When controlling for other variables using multivariate analyses, the risk of treatment failure was higher (odds ratio = 2.53; 95% confidence interval [CI] = 1.13 to 5.64) and reinfection occurred earlier (hazard ratio = 2.00; 95% CI = 1.05 to 3.82) for the cases with a positive culture during reimplantation. The treatment failure rate did not differ (p = 0.73) between cases with ≥2 positive cultures (36.4%) and 1 positive culture (50%). CONCLUSIONS Positive intraoperative culture at the time of reimplantation, regardless of the number of positive samples, was independently associated with >2 times the risk of subsequent treatment failure and earlier reinfection. Surgeons should be aware that a positive culture at the time of reimplantation independently increases the risk of subsequent failure. LEVEL OF EVIDENCE Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Diagnosing Periprosthetic Joint Infection: And the Winner Is?

BACKGROUND Diagnosis of periprosthetic joint infection (PJI) remains a challenge despite a wide variety of available diagnostic tests. The question that arises is which of these tests has a better performance for diagnosing PJI. Diagnostic odds ratio (DOR) has been described as the best indicator for test performance. METHODS To compare the performance of the standard diagnostic tests, the DOR of serum erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), synovial fluid (SF) white blood cell (WBC) count, SF polymorphonuclear (PMN%), and leukocyte esterase (LE) were calculated. RESULTS We obtained 4662 ESRs, 4392 CRPs, 836 SF WBC, 804 SF PMN%, and 659 LE results. LE had the highest DOR for diagnosing PJI: 30.06 (95% confidence interval [CI]: 17.8-50.7). The rest of the DORs in the descending order were SF WBC: 29.4 (95% CI: 20.2-42.8), CRP: 25.6 (95% CI: 19.5-33.7), SF PMN%: 25.5 (95% CI: 17.5-37.0), and ESR: 14.6 (95% CI: 11.5-18.6). CONCLUSION Based on our findings, it appears that among the minor diagnostic criteria, LE has the best performance.

Polymicrobial Periprosthetic Joint Infections: Outcome of Treatment and Identification of Risk Factors.

BACKGROUND The treatment outcomes of periprosthetic joint infection are frequently dependent on characteristics of the causative organism. The objective of this comparative study was to investigate the prevalence of and risk factors for development of polymicrobial periprosthetic joint infection, and the outcome of surgical treatment of these patients. METHODS All patients with polymicrobial, monomicrobial, or culture-negative periprosthetic joint infection treated from 2000 to 2014 were identified at a single institution. Ninety-five patients with a polymicrobial periprosthetic joint infection had a minimum follow-up of 12 months. We matched patients with a polymicrobial periprosthetic joint infection with the other cohorts using propensity score matching for several important parameters. Treatment success was defined according to the Delphi criteria; Kaplan-Meier survivorship curves were generated to demonstrate this. A multiple logistic regression analysis was performed to determine risk factors for a polymicrobial periprosthetic joint infection. RESULTS Overall, 10.3% (108 of 1,045) of the periprosthetic joint infections treated at our institution were polymicrobial in nature. Patients with a polymicrobial periprosthetic joint infection had a higher failure rate at 50.5% (48 of 95) compared with the monomicrobial periprosthetic joint infection cohort at 31.5% (63 of 200) and the culture-negative periprosthetic joint infection cohort at 30.2% (48 of 159) (p = 0.003). The survivorship of the polymicrobial periprosthetic joint infection group was 52.2% at the 2-year follow-up, 49.3% at the 5-year follow-up, and 46.8% at the 10-year follow-up. Patients with polymicrobial periprosthetic joint infection had a higher rate of amputation (odds ratio [OR], 3.80 [95% confidence interval (CI), 1.34 to 10.80]), arthrodesis (OR, 11.06 [95% CI, 1.27 to 96.00]), and periprosthetic joint infection-related mortality (OR, 7.88 [95% CI, 1.60 to 38.67]) compared with patients with monomicrobial periprosthetic joint infection. Isolation of gram-negative organisms (p < 0.01), enterococci (p < 0.01), Escherichia coli (p < 0.01), and atypical organisms (p < 0.01) was associated with polymicrobial periprosthetic joint infection. Only the presence of a sinus tract (OR, 2.20 [95% CI, 1.39 to 3.47]; p = 0.001) was a significant risk factor for polymicrobial periprosthetic joint infection on multivariate analysis. CONCLUSIONS This study reveals that polymicrobial periprosthetic joint infection, occurring at a relatively low rate, is associated with poor outcomes when compared with monomicrobial and culture-negative periprosthetic joint infection. Patients with polymicrobial infections were more likely to require a salvage procedure or to have periprosthetic joint infection-related mortality. Polymicrobial periprosthetic joint infection was associated with soft-tissue defects such as a sinus tract and certain types of organisms, which should be considered when administering antibiotics to these patients. LEVEL OF EVIDENCE Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Long-Term Outcomes of Liner Cementation into a Stable Retained Shell: A Concise Follow-up of a Previous Report.

UNLABELLED Liner cementation into a preexisting stable socket may reduce the morbidity of revision hip arthroplasty and preserve acetabular bone. However, the long-term outcomes of this technique remain unknown. The purpose of this report was to analyze the long-term results of a previously reported cohort of patients. Cementation of thirty-two liners (seventeen polyethylene and fifteen metal liners) into preexisting sockets was performed during revision hip arthroplasty, and the patients were followed for a minimum of two years. A retrospective chart review was performed to investigate the complications and survivorship. The mean duration of follow-up was 12.7 years (range, 2.1 to 19.1 years), with ten hips requiring rerevision at a mean of 6.4 years (range, 1.0 to 15.5 years). Nine patients experienced posterior dislocations, and two hips required rerevision for instability. Liner dissociation from the shell occurred in two patients. Survivorship analysis, with rerevision as the end point, demonstrated ten and fifteen-year survivorship of 77.3% and 68.8%, respectively. Dissociation of the cemented liner from the acetabular shell was an infrequent cause of failure despite long-term follow-up. Given the high rate of dislocations in this study, careful patient selection and surgical technique should be considered. LEVEL OF EVIDENCE Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Do clinical and quality of life scores change over time after hip resurfacing

Background Metal-on-metal hip resurfacing (MOMHR) is an alternative to total hip replacement in young and active patients but little is known about the evolution of clinical outcome scores of hip resurfacing over time. The purpose of this study was 1) to assess the long-term evolution of UCLA hip scores and SF-12 Quality of life evaluations in a group of patients treated with hip resurfacing arthroplasty, 2) to determine whether the age of the patient at surgery influenced these outcome measurements, and 3) whether the changes in SF-12 scores are comparable with those of the general US population. Patient and Methods A total of 100 patients with unilateral, unrevised, Charnley class A MOMHR were retrospectively selected for the study. UCLA and SF-12 scores were calculated preoperatively, short-term postoperatively, and beyond 10 years. Results There was a decrease in the UCLA function and activity scores, and in the SF-12 physical scores between the short-term and the last follow-up at a minimum of 10 years. However, pain, walking, and SF-12 mental scores were maintained through the last follow-up. Furthermore, the SF-12 physical scores at last follow-up were comparable with those of the general US population while the mental scores were greater. There were no significant differences between the two age groups at any of the follow-up intervals for any outcome measurement. Conclusions While there is a slight decline in physical function following hip resurfacing over time, pain relief, walking ability, and quality of life are maintained.