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Background: The Medicare Access and CHIP Reauthorization Act of 2015 provides the framework to link reimbursement for providers based on outcome metrics. Concerns exist that the lack of risk adjustment for patients undergoing revision TKA for an infection may cause problems with access to care., Questions/purposes: (1) After controlling for confounding variables, do patients undergoing revision TKA for infection have higher 30-day readmission, reoperation, and mortality rates than those undergoing revision TKA for aseptic causes? (2) Compared with patients undergoing revision TKA who are believed not to have infections, are patients undergoing revision for infected TKAs at increased risk for complications?, Methods: We queried the American College of Surgeons National Surgical Quality Improvement Program database for patients undergoing revision TKA from 2012 to 2015 identified by Current Procedural Terminology (CPT) codes 27486, 27487, and 27488. Of the 10,848 patients identified, four were excluded with a diagnosis of malignancy (International Classification of Diseases, 9th Revision code 170.7, 170.9, 171.8, or 198.5). This validated, national database records short-term outcome data for inpatient procedures and does not rely on administrative coding data. Demographic variables, comorbidities, and outcomes were compared between patients believed to have infected TKAs and those undergoing revision for aseptic causes. A multivariate logistic regression analysis was performed to identify independent factors associated with complications, readmissions, reoperations, and mortality., Results: After controlling for demographic factors and medical comorbidities, TKA revision for infection was independently associated with complications (odds ratio [OR], 3.736; 95% confidence interval [CI], 3.198-4.365; p < 0.001), 30-day readmission (OR, 1.455; 95% CI, 1.207-1.755; p < 0.001), 30-day reoperation (OR, 1.614; 95% CI, 1.278-2.037; p < 0.001), and 30-day mortality (OR, 3.337; 95% CI, 1.213-9.180; p = 0.020). Patients with infected TKA had higher rates of postoperative infection (OR, 3.818; 95% CI, 3.082-4.728; p < 0.001), renal failure (OR, 36.709; 95% CI, 8.255-163.231; p < 0.001), sepsis (OR, 7.582; 95% CI, 5.529-10.397; p < 0.001), and septic shock (OR, 3.031; 95% CI, 1.376-6.675; p = 0.006)., Conclusions: Policymakers should be aware of the higher rate of mortality, readmissions, reoperations, and complications in patients with infected TKA. Without appropriate risk adjustment or excluding these patients all together from alternative payment and quality reporting models, fewer providers will be incentivized to care for patients with infected TKA., Level of Evidence: Level III, therapeutic study.

Background: Patients with geriatric hip fractures may be at increased risk for postoperative Clostridium difficile colitis, which can cause severe morbidity and can influence hospital quality metrics. However, to our knowledge, no large database study has calculated the incidence of, factors associated with, and effect of C. difficile colitis on geriatric patients undergoing hip fracture surgery., Questions/purposes: To use a large national database with in-hospital and postdischarge data (National Surgical Quality Improvement Program [NSQIP®]) to (1) determine the incidence and timing of C. difficile colitis in geriatric patients who underwent surgery for hip fracture, (2) identify preoperative and postoperative factors associated with the development of C. difficile colitis in these patients, and (3) test for an association between C. difficile colitis and postoperative length of stay, 30-day readmission, and 30-day mortality., Patients and Methods: This is a retrospective study. Patients who were 65 years or older who underwent hip fracture surgery were identified in the 2015 NSQIP database. The primary outcome was a diagnosis of C. difficile colitis during the 30-day postoperative period. Preoperative and procedural factors were tested for association with the development of C. difficile colitis through a backward stepwise multivariate model. Perioperative antibiotic type and duration were not included in the model, as this information was not recorded in the NSQIP. The association between C. difficile colitis and postoperative length of stay, 30-day readmission, and 30-day mortality were tested through multivariate regressions, which adjusted for preoperative and procedural characteristics such as age, comorbidities, and surgical procedure. A total of 6928 patients who were 65 years or older and underwent hip fracture surgery were identified., Results: The incidence of postoperative C. difficile colitis was 1.05% (95% CI, 0.81%-1.29%; 73 of 6928 patients). Of patients who had C. difficile colitis develop, 64% (47 of 73 patients) were diagnosed postdischarge and 79% (58 of 73 patients) did not have a preceding infectious diagnosis. Preoperative factors identifiable before surgery that were associated with the development of C. difficile colitis included admission from any type of chronic care facility (versus admitted from home; relative risk [RR] = 1.98; 95% CI, 1.11-3.55; p = 0.027), current smoker within 1 year (RR = 1.95; 95% CI, 1.03-3.69; p = 0.041), and preoperative anemia (RR = 1.76; 95% CI, 1.07-2.92; p = 0.027). Patients who had pneumonia (RR = 2.58; 95% CI, 1.20-5.53; p = 0.015), sepsis (RR = 4.20; 95% CI, 1.27-13.82; p = 0.018), or "any infection" (RR = 2.26; 95% CI, 1.26-4.03; p = 0.006) develop after hip fracture were more likely to have C. difficile colitis develop. Development of C. difficile colitis was associated with greater postoperative length of stay (22 versus 5 days; p < 0.001), 30-day readmission (RR = 3.41; 95% CI, 2.17-5.36; p < 0.001), and 30-day mortality (15% [11 of 73 patients] versus 6% [439 of 6855 patients]; RR = 2.16; 95% CI, 1.22-3.80; p = 0.008)., Conclusions: C. difficile colitis is a serious infection after hip fracture surgery in geriatric patients that is associated with 15% mortality. Patients at high risk, such as those admitted from any type of chronic care facility, those who had preoperative anemia, and current smokers within 1 year, should be targeted with preventative measures. From previous studies, these measures include enforcing strict hand hygiene with soap and water (not alcohol sanitizers) if a provider is caring for patients at high risk and those who are C. difficile-positive. Further, other studies have shown that certain antibiotics, such as fluoroquinolones and cephalosporins, can predispose patients to C. difficile colitis. These medications perhaps should be avoided when prescribing prophylactic antibiotics or managing infections in patients at high risk. Future prospective studies should aim to determine the best prophylactic antibiotic regimens, probiotic formula, and discharge timing that minimize postoperative C. difficile colitis in patients with hip fractures., Level of Evidence: Level III, therapeutic study.

Background: Many patients develop recurrent periprosthetic joint infection after two-stage exchange arthroplasty of the hip or knee. One potential but insufficiently tested strategy to decrease the risk of persistent or recurrent infection is to administer additional antibiotics after the second-stage reimplantation., Questions/purposes: (1) Does a 3-month course of oral antibiotics decrease the risk of failure secondary to infection after a two-stage exchange? (2) Are there any complications related to the administration of oral antibiotics after a two-stage exchange? (3) In those patients who develop a reinfection, is the infecting organism different from the initial infection?, Methods: Patients at seven centers randomized to receive 3 months of oral antibiotics or no further antibiotic treatment after operative cultures after the second-stage reimplantation were negative. Adult patients undergoing two-stage hip or knee revision arthroplasty for a periprosthetic infection who met Musculoskeletal Infection Society (MSIS) criteria for infection at the first stage were included. Oral antibiotic therapy was tailored to the original infecting organism(s) in consultation with an infectious disease specialist. MSIS criteria as used by the treating surgeon defined failure. Surveillance of patients for complications, including reinfection, occurred at 3 weeks, 6 weeks, 3 months, 12 months, and 24 months. If an organism demonstrated the same antibiotic sensitivities as the original organism, it was considered the same organism; no DNA subtyping was performed. Analysis was performed as intent to treat with all randomized patients included in the groups to which they were randomized. A log-rank survival curve was used to analyze the primary outcome of reinfection. At planned interim analysis (enrollment is ongoing), 59 patients were successfully randomized to the antibiotic group and 48 patients to the control group. Fifty-seven patients had an infection after TKA and 50 after a THA. There was no minimum followup for inclusion in this analysis. The mean followup was 14 months in the antibiotic group and 10 months in the control group., Results: Patients treated with oral antibiotics failed secondary to infection less frequently than those not treated with antibiotics (5% [three of 59] versus 19% [nine of 48]; hazard ratio, 4.37; 95% confidence interval, 1.297-19.748; p = 0.016). Three patients had an adverse reaction to the oral antibiotics severe enough to cause them to stop taking the antibiotics early, and four patients who were randomized to that group did not take the antibiotics as directed. With the numbers available, there were no differences between the study groups in terms of the likelihood that an infection after treatment would be with a new organism (eight of nine in the control group versus one of three in the treatment group, p = 0.087)., Conclusions: This multicenter randomized trial suggests that at short-term followup, the addition of 3 months of oral antibiotics appeared to improve infection-free survival. As a planned interim analysis, however, these results may change as the study reaches closure and the safety profile may yet prove risky. Further followup of this cohort of patients will be necessary to determine whether these preliminary results are durable over time., Level of Evidence: Level I, therapeutic study.

Background: Soft tissue defects after TKA are a potentially devastating complication. Medial gastrocnemius flaps occasionally are used to provide soft tissue coverage, most commonly with a periprosthetic joint infection., Questions/purposes: We asked: (1) What were the rates of persistent or recurrent infection, implant survivorship, flap-related complications, and reoperation for patients who underwent medial gastrocnemius flap reconstruction for soft tissue coverage after TKA? (2) What were the Knee Society clinical and functional scores for patients who underwent medial gastrocnemius flap reconstruction for soft tissue defects after TKA? (3) What were the risk factors for failure of medial gastrocnemius flap reconstruction after TKA, with failure defined as recurrent or new periprosthetic joint infection or inability to reimplant the TKA prosthesis?, Methods: Between 2003 and 2011, four surgeons at one institution performed 31 medial gastrocnemius flaps for soft tissue coverage over an infected TKA. Of those, 27 (87%) were available for followup at a minimum of 2 years (mean, 4 years; range, 2-6 years), although patients experiencing complications or treatment failures before two years were included. The study group consisted of 15 men and 12 women with a mean age of 61 years at the time of surgery (range, 36-86 years). The general indication for using a gastrocnemius flap in this setting was full-thickness soft tissue deficiency over the anterior knee during the course of treatment for concomitant deep infection. Six flaps were performed at prosthetic explantation and antibiotic spacer placement, eight at a spacer exchange, eight at second-stage TKA prosthesis reimplantation, and five at débridement with polyethylene exchange. The decision regarding when during staged treatment to place the flap was based solely on when the soft tissues were deemed insufficient, and not based on a belief that placement at one stage versus another was advantageous. Failure was defined as inability to undergo reimplantation of a TKA prosthesis or recurrence of periprosthetic joint infection. Patient and procedural characteristics were tested for association with failure. Survivorship was calculated by Cox proportional hazards modeling. Outcomes scores were drawn from a longitudinal institutional registry., Results: Fourteen of 27 (52%) patients had a persistent or recurrent infection; survivorship of the TKA prosthesis at 4 years was 48% (95% CI, 31%-66%). Although there were no flap-related complications, 12 patients had a total of 19 reoperations during the study period. Overall, the mean (± SD) Knee Society knee (38 ± 18 vs 65 ± 20; p < 0.001) and function (20 ± 22 vs 37 ± 25; p = 0.002) scores were improved at most recent followup. No factors were identified as associated with failure when a Bonferroni correction was applied., Conclusions: Gastrocnemius flaps were used to address difficult soft tissue defects in this series, in the presence of deep infections; the high proportion of patients experiencing persistent or recurrent infections reflects the case complexity and not necessarily a problem with the flaps. However, this series highlights the need to continue to explore alternative approaches to managing this difficult clinical problem. Future studies should aim to establish an evidence-based reconstructive algorithm, focusing on host, wound, and timing characteristics that may maximize outcomes., Level of Evidence: Level IV, therapeutic study.

Background: Reporting of complications after total hip arthroplasty (THA) is not standardized, and it is done inconsistently across various studies on the topic. Advantages of standardizing complications include improved patient safety and outcomes and better reporting in comparative studies., Questions/purposes: The purpose of this project was to develop a standardized list of complications and adverse events associated with THA, develop standardized definitions for each complication, and stratify the complications. A further purpose was to validate these standardized THA complications., Methods: The Hip Society THA Complications Workgroup proposed a list of THA complications, definitions for each complication, and a stratification scheme for the complications. The stratification system was developed from a previously validated grading system for complications of hip preservation surgery. The proposed complications, definitions, and stratification were validated with an expert opinion survey of members of The Hip Society, a case study evaluation, and analysis of a large administrative hospital system database with a focus on readmissions., Results: One hundred five clinical members (100%) of The Hip Society responded to the THA complications survey. Initially, 21 THA complications were proposed. The validation process reduced the 21 proposed complications to 19 THA complications with definitions and stratification that were endorsed by The Hip Society (bleeding, wound complication, thromboembolic disease, neural deficit, vascular injury, dislocation/instability, periprosthetic fracture, abductor muscle disruption, deep periprosthetic joint infection, heterotopic ossification, bearing surface wear, osteolysis, implant loosening, cup-liner dissociation, implant fracture, reoperation, revision, readmission, death)., Conclusions: Acceptance and use of these standardized, stratified, and validated THA complications and adverse events could advance reporting of outcomes of THA and improve assessment of THA by clinical investigators., Level of Evidence: Level V, therapeutic study.

Background: Modular revision femoral components allow the surgeon to make more precise intraoperative adjustments in anteversion and sizing, which may afford lower dislocation rates and improved osseointegration, but may not offer distinct advantages when compared with less expensive monoblock revision stems., Questions/purposes: We compared modular and monoblock femoral components for revision of Paprosky Type I to IIIA femoral defects to determine (1) survivorship of the stems; and (2) complications denoted as intraoperative fracture, dislocation, or failure of osseointegration., Methods: Between 2004 and 2010, participating surgeons at three centers revised 416 total hip arthroplasties (THAs) with Paprosky Type I to IIIA femoral defects. Of those with minimum 2-year followup (343 THAs, mean followup 51 ± 13 months), 150 (44%) were treated with modular stems and 193 (56%) were treated with monoblock, cylindrical, fully porous-coated stems. During this time, modular stems were generally chosen when there was remodeling of the proximal femur into retroversion and/or larger canal diameters (usually > 18 mm). A total of 27 patients died (6%) with stems intact before 2 years, 46 THAs (13%) were lost to followup before 2 years for reasons other than death, and there was no differential loss to followup between the study groups. The modular stems included 101 with a cylindrical distal geometry (67%) and 49 with a tapered geometry (33%). Mean age (64 versus 68 years), percentage of women (53% versus 47%), and body mass index (31 versus 30 kg/m(2)) were not different between the two cohorts, whereas there was trend toward a slightly greater case complexity in the modular group (55% versus 65% Type 3a femoral defects, p = 0.06). Kaplan-Meier survivorship was calculated for the endpoint of aseptic revision. Proportions of complications in each cohort (dislocation, intraoperative fracture, and failure of osseointegration) were compared., Results: Femoral component rerevision for any reason (including infection) was greater (OR, 2.01; 95% CI, 1.63-2.57; p = 0.03) in the monoblock group (27 of 193 [14%]) compared with the modular cohort (10 of 150 [7%]). Femoral component survival free from aseptic rerevision was greater in the modular group with 91% survival (95% CI, 89%-95%) at 9 years compared with 86% survival (95% CI, 83%-88%) for the monoblock group in the same timeframe. There was no difference in the proportion of mechanically relevant aseptic complications (30 of 193 [16%] in the monoblock group versus 34 of 150 [23%] in the modular group, p = 0.10; OR, 1.47; 95% CI, 0.86-2.53). There were more intraoperative fractures in the modular group (17 of 150 [11%] versus nine of 193 [5%]; OR, 2.2; 95% CI, 1.68-2.73; p = 0.02). There were no differences in the proportions of dislocation (13 of 193 [7%] monoblock versus 14 of 150 [9%] modular; OR, 0.96; 95% CI, 0.67-1.16; p = 0.48) or failure of osseointegration (eight of 193 [4%] monoblock versus three of 150 [2%] modular; OR, 1.92; 95% CI, 0.88-2.84; p = 0.19) between the two groups with the number of hips available for study., Conclusions: Although rerevisions were less common in patients treated with modular stems, aseptic complications such as intraoperative fractures were more common in that group, and the sample was too small to evaluate corrosion-related or fatigue concerns associated with modularity. We cannot therefore conclude from this that one design is superior to the other. Larger studies and pooled analyses will need to be performed to answer this question, but we believe modularity should be avoided in more straightforward cases if possible., Level of Evidence: Level III, therapeutic study.

Background: The diagnosis of periprosthetic joint infection (PJI) in patients with failed metal-on-metal (MoM) bearings and corrosion reactions in hip arthroplasties can be particularly difficult, because the clinical presentation of adverse local tissue reactions may mimic that of PJI, because it can also occur concurrently with PJI, and because common laboratory tests used to diagnose PJI may be elevated in patients with MoM THAs., Questions/purposes: We sought to determine the test properties of the serum erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), synovial fluid white blood cell (WBC) count, and synovial fluid differential (percent polymorphonuclear cells [PMNs]) in diagnosing PJI in either MoM hips undergoing revision for a variety of indications or in non-MoM hips undergoing revision for either corrosion reaction or full-thickness wear. Additionally, we sought to describe how MoM bearings, metal debris, and corrosion reactions can confound the analysis of the synovial fluid WBC count and affect its diagnostic use for PJI., Methods: We reviewed 150 revision hips meeting specified inclusion criteria (92 MoM total hips, 19 MoM hip resurfacings, 30 non-MoM bearings with corrosion, and nine full-thickness bearing surface wear with metallosis). In our review, we diagnosed 19 patients as infected using Musculoskeletal Infection Society (MSIS) criteria. Mean laboratory values were compared between infected and not infected patients and receiver operator characteristic curves were generated with an area under the curve (AUC) to determine test performance and optimal cutoffs., Results: After excluding the inaccurate synovial fluid samples, the synovial fluid WBC count (performed accurately in 102 patients) was the best test for the diagnosis of PJI (AUC=98%, optimal cutoff 4350 WBC/μL) followed by the differential (performed accurately in 102 patients; AUC=90%, optimal cutoff 85% PMN). The ESR (performed in 131 patients) and CRP (performed in 129 patients) both had good sensitivity (83% and 94%, respectively). Patients meeting MSIS criteria for PJI had higher mean serum ESR, CRP, synovial fluid WBC count, and differential than those not meeting MSIS criteria (p<0.05 for all). An observer blinded to the MSIS diagnosis of the patient assessed the synovial fluid samples for inaccuracy secondary to metal or cellular debris. Synovial fluid sample "inaccuracy" was defined as the laboratory technician noting the presence of metal or amorpous material, fragmented cells, or clots, or the sample having some defect preventing an automated cell count from being performed. Of the 141 patients who had a synovial fluid sample initially available for review, 47 (33%) had a synovial fluid sample deemed to be inaccurate. A synovial fluid WBC count was still reported; however, 35 of these 47 hips (75%) and 11 of these 35 (31%) were falsely positive for infection., Conclusions: The diagnosis of PJI is extremely difficult in patients with MoM bearings or corrosion and the synovial fluid WBC count can frequently be falsely positive and should be relied on only if a manual count is done and if a differential can be performed. A more aggressive approach to preoperative evaluation for PJI is recommended in these patients to allow for careful evaluation of the synovial fluid specimen, the integration of synovial fluid culture results, and repeat aspiration if necessary., Level of Evidence: Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Modular tapered stems have been suggested as the optimal implants for patients with severe femoral bone loss (Paprosky Type IIIB and IV) undergoing revision total hip arthroplasty (THA); however, there are few data describing survivorship and hip scores associated with this treatment., Questions/purposes: At minimum 2 years, we sought to determine the (1) survivorship of these implants; (2) radiographic evidence of osseointegration; and (3) the Harris hip scores of patients revised with a modular tapered stem for severe femoral bone loss including the complications associated with their use., Methods: Between 1999 and 2010, we performed 1124 femoral revisions; of those, 135 (12%) were performed using a modular tapered stem. General indications for use of this device included bone loss, poor quality bone, leg length discrepancy, difficulty adjusting version, proximal femoral remodeling, and ectatic medullary canals in the setting of revision THA. This report reviewed 70 of those that were performed in Type IIIB and IV femurs. Of those 70 patients, 11 had died and one was lost before 2-year followup; the remaining 58 (83%, 33 with a Type IIIB femur and 25 with a Type IV femur) were followed for a minimum of 24 months (average, 67 months; range, 24-151 months). Survivorship free from revision, radiographic analysis for signs of subsidence or stem loosening, and Harris hip scores were tallied., Results: One patient underwent stem revision for early subsidence followed by failure of ingrowth for a survivorship free from repeat revision of 98% (57 of 58 patients). Five other stems (for a total of six [10%]) subsided early but nonetheless achieved radiographic signs of ingrowth and were not revised again. All other stems demonstrated osseointegration without subsidence and remained radiographically well fixed. In patients with surviving implants, the mean Harris hip score improved from 34 (range, 11-49) preoperatively to 74 (range, 14-100; p<0.001) postoperatively. Overall, 15 of 58 patients (26%) experienced a complication, of whom 10 (17%) underwent reoperation., Conclusions: We found that modular tapered stems resulted in 98% survivorship at a mean of 67 months in patients with Type IIIB and IV femurs undergoing femoral revision, although the overall complication rate in this complex subset of patients is high., Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Although the volume of total knee arthroplasties (TKAs) performed in the United States continues to increase, recent reports have shown the percentage of patients who remain "unsatisfied" is as high as 15% to 30%. Recently, several newer implant designs have been developed to potentially improve patient outcomes., Questions/purposes: The purpose of this study was to determine the impact of high-flex, gender-specific, and rotating-platform TKA designs on patient satisfaction and functional outcomes., Methods: A four-center study was designed to quantify the degree of residual symptoms and functional deficits in patients undergoing TKA with newer implant designs compared with a 10-year-old, cruciate-retaining (CR) TKA system introduced in 2003. Each contributing surgeon was fellowship-trained and specialized in joint replacement surgery. Only patients younger than 60 years old were included. Data were collected by an independent, third-party survey center blinded to the implant type, who administered questionnaires about patient satisfaction, residual symptoms, function, and pre- and postoperative activity levels using previously published survey instruments. Two hundred thirty-seven CR, 137 rotating-platform, 88 gender-specific, and 65 high-flex TKAs were included in the analysis. Differences in baseline demographic variables were accounted for using multiple logistic regression statistical analyses., Results: Patients who received certain newer designs reported more residual symptoms (grinding, popping, and clicking) in the 30 days before survey administration than the group receiving a 10-year-old CR design (CR, 24% [57 of 237 patients] versus gender-specific, 36% [32 of 88 patients]; odds ratio [OR], 2.1; 95% confidence interval [CI], 1.1-3.8; p=0.03; and rotating-platform, 43% [59 of 137 patients]; OR, 2.2; 95% CI, 1.3-3.7; p<0.001). They also reported more functional problems, including getting in and out of a chair (CR, 19% [46 of 237 patients] versus gender-specific, 37% [32 of 88 patients]; OR, 1.0; 95% CI, 1.1-3.5; p=0.001). Patients with newer TKA designs did not demonstrate any improvements in function or patient satisfaction versus those who received the 10-year-old CR design., Conclusions: When interviewed by an independent, blinded third party, the use of newer implant designs did not improve patient satisfaction and the presence of residual symptoms when compared with patients who received the 10-year-old CR design. Future studies should prospectively determine whether the purported benefits of newer implant designs improve patient-perceived outcomes., Level of Evidence: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Although malnutrition has been hypothesized to increase the risk of periprosthetic joint infection (PJI), strong evidence linking the two is lacking., Questions/purposes: The purposes of this study were to determine (1) if one or more laboratory values suggestive of malnutrition is independently associated with being revised for an infected joint arthroplasty as opposed to for an aseptic failure; (2) the relationship between laboratory parameters suggestive of malnutrition and obesity; and (3) if one or more laboratory parameters suggestive of malnutrition is independently associated with acute PJI complicating an aseptic revision procedure., Methods: Between 2002 and 2010, one surgeon performed 600 revision total joint arthroplasties in 547 patients; during that time, nutritional parameters (including serum albumin, total lymphocyte count, and transferrin) were routinely obtained preoperatively; complete data sets were available on 454 patients (501 procedures [84%]). We compared the frequency of having one or more laboratory parameters suggestive of malnutrition between patients undergoing a revision for septic reasons and aseptic reasons as well as between obese and nonobese patients. The 375 aseptic revisions were then assessed for the incidence of acute postoperative infection (within 90 days, diagnosed with Musculoskeletal Infection Society criteria). Multivariate logistic regression modeling was used to evaluate factors independently associated with (1) a septic as opposed to an aseptic mode of failure; and (2) acute postoperative infection after an aseptic revision., Results: Patients in 67 of 126 (53%) revisions for PJI had one or more laboratory parameters suggestive of malnutrition compared with 123 of 375 (33%) undergoing revision for a noninfectious etiology (odds ratio [OR], 2.3 [95% confidence interval, 1.5-3.5]; p<0.001). Patients who were of normal weight at the time of revision had the highest frequency of laboratory parameters suggestive of malnutrition (42 of 82 [51%]), although this was common in obese patients as well (76 of 238 [32%]) (p=0.002). Among the 375 aseptic revisions, 12 developed an acute postoperative infection (3%). The frequency of infection was nine of 123 in the group having one or more laboratory parameters suggestive of malnutrition and three of 252 in the group not having such laboratory parameters (7% versus 1%; p=0.003). Multivariate regression revealed that having laboratory parameters suggestive of malnutrition is independently associated with both chronic PJI (p=0.003; OR, 2.1) and an acute postoperative infection complicating an aseptic revision arthroplasty (p=0.02; OR, 5.9)., Conclusions: Having one or more laboratory parameters suggestive of malnutrition is common among patients undergoing revision arthroplasty and is independently associated with both chronic septic failure and acute postoperative infection complicating a revision performed for a noninfectious etiology. Future studies should assess the impact of a standardized screening protocol with subsequent correction of abnormal laboratory parameters suggestive of malnutrition on the risk of PJI to determine a potential causal relationship between the two., Level of Evidence: Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Serum C-reactive protein (CRP) is a general marker of inflammation, and recent studies suggest that measurement of CRP in synovial fluid may be a more accurate method for diagnosing periprosthetic joint infection (PJI)., Questions/purposes: We aimed to (1) determine if there is a correlation between serum and synovial CRP values, (2) establish cutoff values for diagnosing infection based on serum and synovial CRP, and (3) compare the utility of measuring CRP in synovial fluid versus serum for the diagnosis of PJI using standard assay equipment available at most hospitals., Methods: Between February 2011 and March 2012, we invited all 150 patients scheduled for revision TKA (84) or THA (66) to participate in this prospective study, of whom 100% agreed. Data ultimately were missing for 31 patients, leaving 60 patients undergoing revision TKA and 59 undergoing revision THA (71% and 89% of the original group, respectively) for whom CRP level was measured in serum and synovial fluid samples. Patients were deemed to have a PJI (32) or no infection (87) using Musculoskeletal Infection Society criteria. Serum and synovial CRP levels were assayed using the same immunospectrophotometer and the correlation coefficient was calculated. Receiver operating characteristic curve analyses were performed to compare utility in diagnosing PJI, which included area under the curve, diagnostic threshold, and test sensitivity, specificity, predictive values, and accuracy. In 22 of 150 patients (14.7%), synovial CRP could not be measured because the sample was too viscous or hemolyzed., Results: In the analyzed 119 samples, there was a strong correlation (r = 0.76; p < 0.001) between synovial and serum CRP. The area under the curve was 0.90 both for the synovial fluid (95% CI, 0.82-0.97) and serum (95% CI, 0.84-0.96) CRP assays. The diagnostic thresholds were 6.6 mg/L for synovial fluid and 11.2 mg/L for serum. Sensitivities, specificities, positive predictive value, negative predictive value, and accuracies were similar for synovial fluid and serum assays., Conclusions: Although recent studies have suggested a superiority of synovial fluid CRP over serum CRP for the diagnosis of PJI, we found that measurement of CRP in synovial fluid rather than serum using readily available assay equipment does not offer a diagnostic advantage in detection of PJIs., Level of Evidence: Level II, diagnostic study. See the Instructions to Authors for a complete description of levels of evidence.

Background: Many studies suggest long femoral components should be used in revision THA. However, longer stems are more difficult to insert and reduce femoral bone stock for future revisions., Questions/purposes: We investigated (1) how frequently a short (≤ 160-mm or primary-length) fully porous-coated stem could be utilized for Paprosky Type I to IIIA femoral defects, (2) how often the tip of the old stem or cement mantle was bypassed by the revision implant, (3) Harris hip scores, radiographic signs of osseointegration, and revision frequency, and (4) complications associated with these reconstructions., Methods: Two surgeons performed 277 femoral revisions graded as Paprosky Types I to IIIA between 2004 and 2009. When femoral canal diameter was less than 18 mm, these surgeons generally used the shortest stem capable of achieving a minimum of 4 cm of scratch fit in the femoral isthmus. Patients were evaluated clinically using the Harris hip score and radiographically for component loosening and to determine whether the revision component bypassed the prior stem tip or cement mantle., Results: A short stem was utilized in 144 of the 277 revisions (52%). In 113 (78%), the revision femoral component did not bypass the tip of the prior stem or cement mantle. The Harris hip score improved (p < 0.001) from 36 preoperatively to 76 at a mean of 4 years (range, 2-8 years). Twelve stems required repeat revision including six (4.9%) for failed ingrowth. Complications included four intraoperative fractures, three postoperative femoral fractures, one cortical perforation, and eight dislocations., Conclusions: Primary-length extensively coated stems provided reliable fixation for ½ of our Paprosky Type I to IIIA femoral revisions. When considering the use of such a component, the revision surgeon should take into account a small risk of failed osseointegration and technical challenges associated with this technique.

Background: Diagnosis of periprosthetic joint infection (PJI) can be difficult in the early postoperative period after total hip arthroplasty (THA) because normal cues from the physical examination often are unreliable, and serological markers commonly used for diagnosis are elevated from the recent surgery., Questions/purposes: The purposes of this study were to determine the optimal cutoff values for erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), synovial fluid white blood cell (WBC) count, and differential for diagnosing PJI in the early postoperative period after primary THA., Methods: We reviewed 6033 consecutive primary THAs and identified 73 patients (1.2%) who underwent reoperation for any reason within the first 6 weeks postoperatively. Thirty-six of these patients were infected according to modified Musculoskeletal Infection Society criteria. Mean values for the diagnostic tests were compared between groups and receiver operating characteristic curves generated along with an area under the curve (AUC) to determine test performance and optimal cutoff values to diagnose infection., Results: The best test for the diagnosis of PJI was the synovial fluid WBC count (AUC = 98%; optimal cutoff value 12,800 cells/μL) followed by the CRP (AUC = 93%; optimal cutoff value 93 mg/L), and synovial fluid differential (AUC = 91%; optimal cutoff value 89% PMN). The mean ESR (infected = 69 mm/hr, not infected = 46 mm/hr), CRP (infected = 192 mg/L, not infected = 30 mg/L), synovial fluid WBC count (infected = 84,954 cells/μL, not infected = 2391 cells/μL), and differential (infected = 91% polymorphonuclear cells [PMN], not infected = 63% PMN) all were significantly higher in the infected group., Conclusions: Optimal cutoff values for the diagnosis of PJI in the acute postoperative period were higher than those traditionally used for the diagnosis of chronic PJI. The serum CRP is an excellent screening test, whereas the synovial fluid WBC count is more specific.

Background: The Total Knee Arthroplasty (TKA) Complications Workgroup of the Knee Society developed a standardized list and definitions of complications associated with TKA. Twenty-two complications and adverse events believed important for reporting outcomes of TKA were identified. The Editorial Board of Clinical Orthopaedics and Related Research (®), the Executive Board of the Knee Society, and the members of the Knee Society TKA Complications Workgroup came to the conclusion that reporting of a list of TKA adverse events and complications would be more valuable if they were stratified using a validated classification system., Questions/purposes: The purpose of this article was to stratify the previously published standardized list of TKA adverse events and complications., Methods: A modified version of the Sink adaptation of the Clavien-Dindo Surgical Complication Classification was applied to the list of standardized TKA complications and adverse events., Results: The proposed stratified classifications of TKA complications were reviewed and endorsed by the Knee Society., Conclusions: Stratification of TKA complications will allow more in-depth and detailed outcome reporting for surgeons, hospitals, third-party payers, government agencies, joint replacement registries, and orthopaedic researchers. This improvement in reporting of TKA complications will also improve the quality of orthopaedic literature.

Background: TKA is among the fastest growing interventions in medicine, with procedure incidence increasing the most in younger patients. Global knee scores have a ceiling effect and do not capture the presence of difficulty or dissatisfaction with specific activities important to patients., Questions/purposes: We quantified the degree of residual symptoms and specific functional deficits in young patients who had undergone TKA., Methods: In a national multicenter study, we quantified the degree of residual symptoms and specific functional deficits in 661 young patients (mean age, 54 years; range, 19-60 years; 61% female) at 1 to 4 years after primary TKA. To eliminate observer bias, satisfaction and function data were collected by an independent, third-party survey center with expertise in administering medical outcomes questionnaires for federal agencies., Results: Overall, 89% of patients were satisfied with their ability to perform normal daily living activities, and 91% were satisfied with their pain relief. After TKA, 66% of patients indicated their knees felt normal, 33% reported some degree of pain, 41% reported stiffness, 33% reported grinding/other noises, 33% reported swelling/tightness, 38% reported difficulty getting in and out of a car, 31% reported difficulty getting in and out of a chair, and 54% reported difficulty with stairs. After recovery, 47% reported complete absence of a limp and 50% had participated in their most preferred sport or recreational activity in the past 30 days., Conclusions: When interviewed by an independent third party, about 1/3 of young patients reported residual symptoms and limitations after modern TKA. We recommend informing patients considering surgery about the high likelihood of residual symptoms and limitations after contemporary TKA, even when performed by experienced surgeons in high-volume centers, and taking specific steps to set patients' expectations to a level that is likely to be met by the procedure as it now is performed.

Background: Although there is extensive literature supporting a high success rate, there are limited data on return to work after total knee arthroplasty (TKA)., Questions/purposes: We sought to determine (1) the percentage of patients who returned to work after TKA; (2) what percentage returned to their original job; (3) whether this varied based on the physical job demand category; and (4) whether there were differences between men and women in terms of the likelihood of returning to work after TKA., Methods: A multicenter study was conducted of patients of working age (18-60 years) who underwent TKA 1 to 5 years previously. An independent third-party survey center with expertise in collecting healthcare data for state and federal agencies collected the data. Definitions from the US Department of Labor's Dictionary of Occupational Titles were used to determine physical job demand categories of sedentary, light, medium, heavy, and very heavy. Complete data were collected on 661 patients undergoing TKA (average age 54 years, 61% women)., Results: Seventy-five percent (494 of 661) were employed in the 3 months before their TKA and 98% (482 of 494) returned to work after surgery; 89% (440 of 494) returned to the same job. Before surgery, physical demand categories of the patients' jobs were sedentary 12%, light 10%, medium 24%, heavy 24%, and very heavy 30%. The return to work rate for those employed during the 3 months before surgery by physical demand category was sedentary 95%, light 91%, medium 100%, heavy 98%, and very heavy 97%. Men were more likely than women to have worked within the 3 months before TKA but there was no difference between sexes in return to work after TKA., Conclusions: In this group of young patients, most returned to work at their usual occupation after TKA.

Background: Few data exist regarding the impact of socioeconomic factors on results of current TKA in young patients. Predictors of TKA outcomes have focused primarily on surgical technique, implant details, and individual patient clinical factors. The relative importance of these factors compared to patient socioeconomic status is not known., Questions/purposes: We determined whether (1) socioeconomic factors, (2) demographic factors, or (3) implant factors were associated with satisfaction and functional outcomes after TKA in young patients., Methods: We surveyed 661 patients (average age, 54 years; range, 18-60 years; 61% female) 1 to 4 years after undergoing modern primary TKA for noninflammatory arthritis at five orthopaedic centers. Data were collected by an independent third party with expertise in collecting healthcare data for state and federal agencies. We examined specific questions regarding satisfaction, pain, and function after TKA and socioeconomic (household income, education, employment) and demographic (sex, minority status) factors. Multivariable analysis was conducted to examine the relative importance of these factors for each outcome of interest., Results: Patients reporting incomes of less than USD 25,000 were less likely to be satisfied with TKA outcomes and more likely to have functional limitations after TKA than patients with higher incomes; no other socioeconomic factors were associated with satisfaction. Women were less likely to be satisfied and more likely to have functional limitations than men, and minority patients were more likely to have functional limitations than nonminority patients. Implants were not associated with outcomes after surgery., Conclusions: Socioeconomic factors, in particular low income, are more strongly associated with satisfaction and functional outcomes in young patients after TKA than demographic or implant factors. Future studies should be directed to determining the causes of this association, and studies of clinical results after TKA should consider stratifying patients by socioeconomic status.

Background: Preoperative antibiotics are known to be critical for decreasing the risk of periprosthetic joint infection (PJI) in primary THA and TKA. However, antibiotics often are withheld before revision surgery, as there is concern that even a single dose of prophylactic antibiotics may affect intraoperative cultures., Questions/purposes: In this prospective randomized controlled trial, we determined the effect of a single dose of prophylactic antibiotics on cultures obtained at the time of revision arthroplasty., Methods: We randomized 65 patients with known PJI after 37 TKAs and 28 THAs at three centers. Patients were included in the trial if they had a culture-positive aspiration and had not taken antibiotics within 2 weeks of the procedure. Patients were randomized to receive prophylactic antibiotics either before the skin incision or after a minimum of three sets of intraoperative cultures were obtained. Preoperative and intraoperative cultures were then compared. Results between patients who did and did not receive antibiotics were compared using an equivalence test for proportion differences (two one-sided t-tests [TOST]) with a 0.2 margin., Results: Intraoperative cultures yielded the same organisms as preoperative cultures in 28 of 34 patients (82%) randomized to receive antibiotics before the skin incision compared to 25 of 31 patients (81%) randomized to receive antibiotics after obtaining operative cultures (statistically equivalent by TOST estimate: p = 0.0290)., Conclusions: In this randomized controlled trial, there was no effect on the results of cultures obtained intraoperatively when prophylactic antibiotics were administered before skin incision. Given the known benefits of prophylactic antibiotics in preventing PJI, preoperative prophylaxis should not be withheld in revision surgery for fear of affecting cultures.

Background: Potential advantages suggested but not confirmed for surface replacement arthroplasty (SRA) over THA include lower frequency of limp, less thigh pain, less limb length discrepancy, and higher activity., Questions/purposes: We therefore determined whether patients having SRA had a limp, thigh pain, or limb length discrepancy less frequently or had activity levels higher than patients having THA., Methods: In a multicenter study, we surveyed 806 patients aged 18 to 60 years with a premorbid UCLA activity score of 6 or more who underwent hip arthroplasty for noninflammatory arthritis at one of five orthopaedic centers. Patients had either a cementless THA with an advanced bearing surface (n = 682) or an SRA (n = 124). The patients were demographically comparable. Specific telephone survey instruments were designed to assess limp, thigh pain, perception of limb length, and activity levels. Minimum followup was 1 year (mean, 2.3 years; range, 1.1-3.9 years)., Results: When controlled for age, sex, and premorbid activity level, patients with SRA had a higher incidence of complete absence of any limp, lower incidence of thigh pain, lower incidence of perception of limb length discrepancy, greater ability to walk continuously for more than 60 minutes, higher percentage of patients who ran after surgery, greater distance run, and higher percentage of patients who returned to their most favored recreational activity., Conclusions: When interviewed by an independent third party, patients with SRA reported higher levels of function with fewer symptoms and less perception of limb length discrepancy compared to a similar cohort of young, active patients with THA.

Background: Acute postoperative infection after total hip arthroplasty (THA) is typically treated with irrigation and débridement and exchange of the modular femoral head and acetabular liner. Given a rate of failure exceeding 50% in some series, a one-stage exchange has been suggested as a potential alternative because it allows more thorough débridement and removal of colonized implants. To date, most studies published on the one-stage exchange have used microbe-specific antibiotic-laden bone cement with only one small single-institution series that reported outcomes after a cementless one-stage exchange., Questions/purposes: We determined whether a one-stage cementless exchange for treating acute postoperative infection after THA would result in infection control with component retention and normalization of infection markers., Methods: We retrospectively identified 27 patients who underwent a one-stage exchange performed for an acute (≤6 weeks) postoperative infection after THA from April 2004 to December 2009. Primary cementless components were used both at the time of the index arthroplasty and the revision in all patients. Surgery was followed by a 6-week course of culture-specific antibiotics in all patients and a variable course of oral antibiotics. Our primary outcome was retention of the implants at most recent followup and our secondary outcome was normalization of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) at most recent followup. Patients were followed until failure or a minimum of 2 years., Results: At a minimum followup of 27 months (mean, 50 months; range, 27-89 months), 19 of the 27 patients (70%) retained their implants but four required further operative débridement with component retention at a mean of 3 weeks (range, 2-6 weeks) to obtain control of infection. Thus, an isolated single-stage exchange was successful in 15 of the 27 patients (56%). Eight patients (30%) ultimately had a two-stage exchange for persistent infection; seven of these patients required no further surgery, whereas one patient required a second two-stage exchange. Of those patients retaining their prosthesis after one-stage exchange and tracked with ESR and CRP, four (33% [four of 12]) had elevated values without other signs or symptoms of recurrent infection., Conclusions: For acute postoperative infection after primary THA, a one-stage cementless exchange allowed 70% of patients to retain their implants at most recent followup. Of those patients who ultimately went on to a two-stage exchange, only one required a second two-stage exchange., Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Although modern-generation rotating-hinge knee implants have been modified to mitigate earlier complications related to aseptic loosening with these devices in revision TKAs, there are few, if any, reports of failure related to the hinge mechanism in these prostheses., Case Description: We present a case of disengagement of the hinge-post extension in a contemporary rotating-hinge knee prosthesis originally implanted during revision surgery for instability and extensor mechanism insufficiency. We hypothesize the screw home kinematics of the knee resulted in a counterclockwise torque, contributing to the hinge post locking screw disengagement in this case., Literature Review: Although some authors have reported complications and failures related to aseptic loosening with rotating-hinge knee prostheses, there have been no reports regarding complications related to the hinge mechanism, which simultaneously links and permits rotation between the femoral and tibial components., Clinical Relevance: Arthroplasty surgeons who use rotating-hinge knee prostheses need to be aware of this potential mode of failure. Design modifications, including more secure locking mechanisms and side-specific implants, may avoid this complication.

Background: Despite dislocation being the most frequent complication after revision THA, risk factors for its occurrence are not completely understood., Questions/purposes: We therefore (1) determined the overall risk of dislocation after revision THA in a large series of revision THAs using contemporary revision techniques, (2) identified patient-related risk factors predicting dislocation, and (3) identified surgical variables predicting dislocation., Methods: We performed 1211 revision THAs between June 2004 and October 2010 in 576 women and 415 men who had a mean age of 64.7 years (range, 25-95 years) at time of surgery. Forty-six (4%) were lost to followup and 13 died (1%), leaving 1152 hips followed for a minimum of 90 days (mean, 2 years; range, 90 days to 7.1 years). Multivariate logistic regression was performed to identify risk factors for dislocation. The model was also tested on patients followed for a minimum 1 year to assess any difference in longer followup., Results: One hundred thirteen patients dislocated over the followup period (9.8%). Factors that were different between patients who dislocated and those who remained stable included a history of at least one previous dislocation (odds ratio [OR] = 2.673), abductor deficiency (OR = 2.672), and Paprosky acetabulum class (OR = 1.522). Use of a constrained liner (OR = 0.503) and increased femoral head size (OR = 0.942) were protective against dislocation, while with longer followup a constrained liner was no longer significant., Conclusions: Dislocation remains a common problem after revision THA. Identifying these risk factors can assist in patient education and surgical planning. Recognition of these risk factors in both patient type and surgical strategy is important for the surgeon performing revision THA and for minimizing these risks., Level of Evidence: Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Background: In a previously reported series of 51 patients with 62 cemented, fixed-bearing unicompartmental knee arthroplasties, we reported a 10-year, 98% survival rate with an average knee score of 92 points. The survivorship and modes of failure past 10 years are incompletely understood., Questions/purposes: At 15-year followup we sought to determine (1) the overall durability and survivorship of this design; (2) modes of failure; and (3) the progression of arthritis in the nonresurfaced compartments., Methods: Nineteen knees in 16 patients were available for study with 34 patients lost to death and one lost to followup. At 15 years, we analyzed the Kaplan-Meier survivorship as well as durability with regard to radiographic loosening and knee scores, determined modes of failure, and assessed radiographs for degeneration in the nonresurfaced compartments., Results: Fifteen-year survivorship was 93% and 20-year survivorship was 90%. Four of 62 knees were revised to total knee arthroplasty at a mean of 144 months. One knee was revised for patellofemoral and lateral compartment degeneration, one for lateral compartment degeneration, one for polyethylene disengagement and metallosis, and one for pain of unclear etiology. No patients had aseptic loosening or osteolysis. The mean knee score was 78 at latest followup. Arthritic progression in the nonresurfaced compartments was common although symptomatic in only two patients., Conclusions: With this cemented, fixed-bearing design, the failure rates were low, there were no cases of failure secondary to wear or loosening, and the survivorship was similar to that reported for total knee arthroplasty.

Background: Despite the importance of complications in evaluating patient outcomes after TKA, definitions of TKA complications are not standardized. Different investigators report different complications with different definitions when reporting outcomes of TKA., Questions/purposes: We developed a standardized list and definitions of complications and adverse events associated with TKA., Methods: In 2009, The Knee Society appointed a TKA Complications Workgroup that surveyed the orthopaedic literature and proposed a list of TKA complications and adverse events with definitions. An expert opinion survey of members of The Knee Society was used to test the applicability and reasonableness of the proposed TKA complications. For each complication, members of The Knee Society were asked "Do you agree with the inclusion of this complication as among the minimum necessary for reporting outcomes of knee arthroplasty?" and "Do you agree with this definition?", Results: One hundred two clinical members (100%) of The Knee Society responded to the survey. All proposed complications and definitions were endorsed by the members, and 678 suggestions were incorporated into the final work product. The 22 TKA complications and adverse events include bleeding, wound complication, thromboembolic disease, neural deficit, vascular injury, medial collateral ligament injury, instability, malalignment, stiffness, deep joint infection, fracture, extensor mechanism disruption, patellofemoral dislocation, tibiofemoral dislocation, bearing surface wear, osteolysis, implant loosening, implant fracture/tibial insert dissociation, reoperation, revision, readmission, and death., Conclusions: We identified 22 complications and adverse events that we believe are important for reporting outcomes of TKA. Acceptance and utilization of these standardized TKA complications may improve evaluation and reporting of TKA outcomes.

Background: Irrigation and débridement (I&D) of periprosthetic infection (PPI) is associated with infection control ranging from 16% to 47%. Mitigating factors include organism type, host factors, and timing of intervention. While the influence of organism type and host factors has been clarified, the timing of intervention remains unclear., Questions/purposes: We addressed the following questions: What is the failure rate of I&Ds performed within 90 days of primary surgery? And what factors are associated with failure?, Methods: We performed a multicenter retrospective analysis of I&D for PPI within 90 days of primary surgery. We included 86 patients (44 males, 42 females) with an average age of 61 years. Failure was defined as return to the operating room for an infection-related problem. We determined the failure rate of I&D within 90 days of primary surgery and whether the odds of rerevision for infection were associated with Charlson Comorbidity Index, age, sex, joint, organism type, and timing. The minimum followup was 24 months (average, 46 months; range, 24-106 months)., Results: 54 of 86 patients (63%) failed. Eight of 10 (80%) failed within the first 10 days, 32 of 57 (56%) within 4 weeks, and 22 of 29 (76%) within 31 to 90 days postoperatively. No covariates were associated with subsequent revision surgery for infection., Conclusions: I&D for PPI is frequently used in the early postoperative period to control infection. While it is assumed early intervention will lead to control of infection in most cases, our data contradict this assumption.

Background: Enterococcal periprosthetic joint infections (PJIs) are rare after joint arthroplasty. These cases are usually reported in series of PJIs caused by other pathogens. Because few studies have focused only on enterococcal PJIs, management and control of infection of these cases have not yet been well defined., Questions/purposes: We asked (1) what is the proportion of enterococcal PJI in our institutes; and (2) what is the rate of infection control in these cases?, Methods: We respectively identified 22 and 14 joints with monomicrobial and polymicrobial PJI, respectively, caused by enterococcus. The diagnosis of PJI was made based on the presence of sinus tract or two positive intraoperative cultures. PJI was also considered in the presence of one positive intraoperative culture and abnormal serology. We determined the proportion of enterococcal PJI and management and control of infection in these cases. Minimum followup was 1.5 years (mean, 3.2 years)., Results: The proportion of monomicrobial enterococcal PJI was 2.3% (22 of 955 cases of PJI). Mean number of surgeries was two (range, 1-4). Initial irrigation and débridement was performed in 10 joints and eight patients needed reoperation. Seven of the 16 joints were initially managed using two-stage exchange arthroplasty and did not need further operation. Six patients had a definitive resection arthroplasty. Salvage surgeries (fusion and above-knee amputation) were performed in three cases (8%). The infection was ultimately controlled in 32 of the 36 patients., Conclusions: Management of enterococcal PJI is challenging and multiple operations may need to be performed to control the infection., Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Dislocation after revision THA is a common complication. Large heads have the potential to decrease dislocation rate, but it is unclear whether they do so in revision THA., Questions/purposes: We therefore determined whether a large femoral head (36 and 40 mm) resulted in a decreased dislocation rate compared to a standard head (32 mm)., Methods: We randomized 184 patients undergoing revision THA to receive either a 32-mm head (92 patients) or 36- and 40-mm head (92 patients) and stratified patients by surgeon. The two groups had similar baseline demographics. The primary end point was dislocation. Quality-of-life (QOL) measures were WOMAC and SF-36. The mean followup for dislocation was 5 years (range, 2-7 years); the mean followup for QOL was 2.2 years (range, 1.6-4 years)., Results: In the 36- and 40-mm head group, the dislocation rate was 1.1% (one of 92) versus 8.7% (eight of 92) for the 32-mm head. There was no difference in QOL outcomes between the two groups., Conclusions: Our observations confirm a large femoral head (36 or 40 mm) reduces dislocation rates in patients undergoing revision THA at short-term followup. We now routinely use large heads with a highly crosslinked polyethylene acetabular liner in all revision THAs., Level of Evidence: Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: The treatment for an early postoperative periprosthetic infection after cementless THA that results in the highest quality of life after the control of infection is unknown. Although common treatments include irrigation and débridement with component retention, a one-stage exchange, or a two-stage exchange, it is unclear whether any of these provides a higher quality of life after the control of infection., Questions/purposes: We projected, through decision-analysis modeling, the possible estimated final health states defined as health-related quality of life based on quality-of-life studies of an early postoperative periprosthetic infection after cementless THA treated by irrigation and débridement, one-stage exchange, or two-stage exchange., Methods: Publications addressing early postoperative infections after THA were analyzed for the estimated rate of infection control and quality-of-life measures after a specific treatment. Decision analysis was used to model the different treatments and describe which, if any, treatment results in the greatest quality of life after early THA infection., Results: In the model, a one-stage exchange was the treatment for early THA infection that maximized quality-of-life outcomes if the probability of controlling the infection exceeded 66% with this procedure. If the probability of infection control of a one-stage exchange was less than 66% or that of irrigation and débridement was greater than 60%, then irrigation and débridement appeared to result in the greatest quality-of-life outcome., Conclusions: A decision analysis using estimates of infection control rate and quality-of-life outcomes after different treatments for an early postoperative infection after THA showed possible outcomes for each treatment., Level of Evidence: Level II, economic and decision analyses. See Guidelines for Authors for a complete description of levels of evidence.

Background: Irrigation and débridement with retention of prosthesis is commonly performed for periprosthetic joint infection. Infection control is reportedly dependent on timing of irrigation and débridement relative to the index procedure., Questions/purposes: We therefore (1) compared the ability of irrigation and débridement to control acute postoperative, acute delayed, and chronic infections and (2) determined whether any patient-related factors influenced infection control., Patients and Methods: We retrospectively reviewed the records of 136 patients (138 joints) from two institutional databases treated with irrigation and débridement between 1996 and 2007. Mean age at time of treatment was 64 years (range, 18-89 years); 77 (56%) joints were in women. Three subgroups were extracted: acute postoperative infections, occurring within 4 weeks (52 joints), acute delayed infections occurring after 4 weeks with acute onset of symptoms (50 joints), and chronic infections (36 joints). Minimum followup was 12 months (average, 54 months; range, 12-115 months). Failure to control infection was reported as the need for any subsequent surgical intervention and/or use of long-term suppressive antibiotics., Results: Infection control was not achieved in 90 joints (65%; 82 requiring return to surgery and eight remaining on long-term suppressive antibiotics). Failure rates were 69% (36 of 52), 56% (28 of 50), and 72% (26 of 36) for acute postoperative, acute delayed, and chronic infections, respectively. Of the 10 variables considered as potential risk factors, only Staphylococcal organisms predicted failure., Conclusions: Irrigation and débridement is unlikely to control periprosthetic joint infection, including acute infections. Our data suggest surgeons should be cautious using this procedure as a routine means to address periprosthetic joint infection. For most patients, we recommend irrigation and débridement be reserved for an immunologically optimized host infected acutely with a non-Staphylococcal organism., Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Background: Two-stage exchange arthroplasty is the gold standard for treatment of infected TKA. The erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and synovial fluid white blood cell (WBC) count with differential are often used to determine treatment response; however, it is unclear whether these tests can answer the critical question of whether joint sepsis has been controlled between stages and if reimplantation is indicated., Questions/purposes: We therefore asked if (1) these serologies respond between stage one explantation and stage two reimplantation during two-stage knee reconstruction for infection; and (2) changes in the values of these serologies are predictive of resolution of joint infection., Methods: We retrospectively reviewed the serologies of 76 infected patients treated with a two-stage exchange protocol. The ESR, CRP, and aspiration were repeated a minimum of 2 weeks following antibiotic cessation and prior to second stage reoperation. Comparisons were made to identify trends in these serologies between the first and second stage procedures., Results: Eight knees (12%) were persistently infected at the time of second stage reoperation. The ESR remained persistently elevated in 37 knees (54%), and the CRP remained elevated in 14 knees (21%) where infection had been controlled. We were unable to identify an optimum cutoff value for the ESR, CRP, or the two combined. The best test for confirmation of infection control was the synovial fluid WBC count., Conclusions: Although the ESR, CRP, and synovial fluid WBC counts decreased in cases of infection control, these values frequently remained elevated. We were unable to identify any patterns in these tests indicative of persistent infection., Level of Evidence: Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Chronic infections in TKA have been traditionally treated with a two-stage protocol incorporating a temporary antibiotic-loaded cement spacer. The use of a static as opposed to an articulating spacer is controversial. Some surgeons believe a static spacer results in a higher rate of infection eradication, whereas others believe an articulating spacer provides equivalent rates of infection control with improved function between stages and the potential for better eventual range of motion., Questions/purposes: We determined the rates of infection control and postoperative function for an articulating all-cement antibiotic spacer fashioned intraoperatively from prefabricated silicone molds., Methods: We retrospectively reviewed 60 patients with an infected TKA using the same cement-on-cement articulating spacer. A minimum of 4 g antibiotic per package of cement was used when making the spacer. Complications and pre- and postoperative knee flexion, extension, and Knee Society scores were recorded. Bone loss associated with the spacer was determined radiographically and by intraoperative inspection of the bony surfaces at the second stage. Minimum followup was 24 months (mean, 35 months; range, 24-51 months)., Results: Seven patients (12%) became reinfected, four with an organism different from that identified at the index resection arthroplasty. One spacer femoral component broke between stages but did not require any specific treatment. We identified no bone loss between stages and no complications related to the cement-on-cement articulation. The mean pretreatment Knee Society scores of 53 improved to 79. The mean preoperative flexion of 90.6º improved to 101.3º at final followup., Conclusions: An articulating antibiotic spacer was associated with control of a deep periprosthetic infection in 88% of patients while allowing range of motion between stages., Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Hybrid revision knee component fixation, in which cement is placed in the metaphysis combined with a cementless diaphyseal engaging stem, provides ease of insertion, possibly improved component alignment, and easier removal if required, compared with fully cemented prostheses. The literature suggests the technique has a 2 to 5 year survivorship ranging from 81% to 94%., Questions/purposes: To confirm the literature we asked whether (1) a modified hybrid fixation technique is durable and reliable at an average 5-year followup, (2) this method of fixation provides clinical improvements as assessed by knee scores, (3) there are radiographic findings unique to this fixation technique, (4) the degree of knee constraint influences clinical performance or radiographic findings, and (5) end-of-stem pain is associated with this fixation method?, Patients and Methods: We retrospectively reviewed all 83 patients who had 88 both-component revision TKAs using our modified hybrid fixation technique. We assessed the Knee Society scores and evaluated radiographs for radiolucent and radiosclerotic lines. The minimum followup was 24 months (average, 65 months; range, 24-126 months)., Results: Kaplan-Meier survivorship free of aseptic loosening was 100% at 5 years and 90% at 10 years. Postoperatively, the mean Knee Society pain and function scores both improved. Partial radiolucent lines were rare; two components were loose. We commonly observed radiosclerotic lines adjacent to stem extensions but these did not affect clinical scores or implant stability at last followup. Neither knee scores nor radiographic findings differed based on knee constraint. End-of-stem pain occurred rarely and was transient., Conclusions: Modified hybrid fixation of revision knee arthroplasty using a diaphyseal engaging stem and cementation only in the metaphysis is durable at a mean 5 years followup., Level of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Patients with a personal or familial history of thromboembolism are considered at higher risk for thromboembolic disease after knee arthroplasty. While it remains unclear why some patients develop deep vein thrombosis (DVT) or pulmonary embolism (PE) despite similar operative procedures and the same prophylactic regimen, we presume one explanation would be genetic predisposition., Questions/purposes: We determined the frequency of 12 factors including antithrombin III activity, prothrombin gene mutations, and the presence of phospholipid antibodies in a high-risk patient cohort and compared those findings with the known prevalence in the population at large., Patients and Methods: Patients identified preoperatively as having a personal or familial history of DVT and/or PE were referred for hemostatic serum and genetic tests, including % antithrombin III activity (ATIII), protein C and protein S activities, APC resistance, Factor V gene (Leiden) mutations, prothrombin gene mutations, lupus anticoagulant antibody presence, cardiolipin antibody presence, phosphatidyl antibody presence, β2-glycoprotein antibody presence, and serum homocysteine and lipoprotein(a) levels The frequencies of varying abnormalities were identified and compared to the prevalence reported in the literature., Results: Forty-three of 1944 patients undergoing knee arthroplasty had a history of DVT or PE. Sixteen of 43 (37%) patients had an abnormality and eight of these (19%) had two or more abnormalities. The frequency of nine of the 12 tests appeared to be greater in this cohort than in the population at large., Conclusions: Patients with a personal or familial history of DVT or PE appear to have a high frequency of hereditary prothrombotic abnormalities. Preoperative evaluation by a hematologist may be warranted in patients with a personal or familial history of DVT or PE as the postoperative anticoagulation protocols may be altered and identification of these abnormalities may affect a patient's risk for other disease states., Level of Evidence: Level IV, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: Synovial fluid white blood cell count is useful for diagnosing periprosthetic infections but the utility of this test in the early postoperative period remains unknown as hemarthrosis and postoperative inflammation may render standard cutoff values inaccurate., Questions/purposes: We evaluated the diagnostic performance of four common laboratory tests, the synovial white blood cell count, differential, C-reactive protein, and erythrocyte sedimentation rate to detect infection in the first 6 weeks after primary TKA., Methods: We reviewed 11,964 primary TKAs and identified 146 that had a knee aspiration within 6 weeks of surgery. Infection was diagnosed in 19 of the 146 knees by positive cultures or gross purulence. We compared demographic information, time from surgery, and the laboratory test values between infected and noninfected knees to determine if any could identify infection early postoperatively. Receiver operating characteristic curves were constructed to determine optimal cutoff values for each of the test parameters., Results: Synovial white blood cell count (92,600 versus 4200 cells/μL), percentage of polymorphonuclear cells (89.6% versus 76.9%), and C-reactive protein (171 versus 88 mg/L) were higher in the infected group. The optimal synovial white blood cell cutoff was 27,800 cells/μL (sensitivity, 84%; specificity, 99%; positive predictive value, 94%; negative predictive value, 98%) for diagnosing infection. The optimal cutoff for the differential was 89% polymorphonuclear cells and for C-reactive protein 95 mg/L., Conclusions: With a cutoff of 27,800 cells/μL, synovial white blood cell count predicted infection within 6 weeks after primary TKA with a positive predicted value of 94% and a negative predictive value of 98%. The use of standard cutoff values for this parameter (~ 3000 cells/μL) would have led to unnecessary reoperations., Level of Evidence: Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: The two-incision approach to THA has been controversial, with some authors reporting its use is associated with a rapid recovery whereas others report no differences in outcomes and a higher risk of perioperative complications secondary to increased surgical complexity., Questions/purposes: We therefore compared early postoperative variables including pain, length of stay, functional recovery, complications, and complexity of the mini-posterior and two-incision approaches to THA., Patients and Methods: We prospectively enrolled 72 patients scheduled for THA and randomized them into two groups: mini-incision posterior approach and the two-incision approach. Preoperative teaching, anesthetic protocols, implants used, and rehabilitation pathways were identical for both groups. All variables were assessed at a maximum of 1 year postoperatively., Results: All key outcomes were similar in the two groups: mean visual analog scale (VAS) scores for pain during the first 3 postoperative days and the first 6 weeks, total narcotic requirements in the hospital and during the first 6 weeks, mean length of stay (51 hours versus 48 hours), and mean Harris hip scores and SF-12 scores. Achievement of functional milestones was similar between the two groups. There was one reoperation in each group. Mean operative time was longer for patients in the two-incision group (98 minutes versus 77 minutes), however the accuracy of component positioning was similar., Conclusions: We found no differences in perioperative outcomes between these two approaches for THA. Variables other than the surgical approach including perioperative protocols, patient expectations, and the patient's general health may have a greater effect on outcomes such as pain during the early postoperative period, functional recovery, and length of hospital stay. The use of small incisions for THA was safe as was a shortened hospital stay in selected patients.

Background: Metallic wires and cables are commonly used in primary and revision THA for fixation of periprosthetic fractures and osteotomies of the greater trochanter. These systems provide secure fixation and high healing rates but fraying, third-body generation, accelerated wear of the bearing surface, and injury to the surgical team remain concerning., Questions/purposes: We determined the rate of cable failure, union, and complications associated with a novel, nonmetallic cerclage cable in periprosthetic fracture and osteotomy fixation during THA., Methods: We retrospectively reviewed 29 patients who had primary and revision THAs using nonmetallic cables. Indications for use included fixation of an extended trochanteric osteotomy, intraoperative fracture of the proximal femur, strut allograft fixation, and a Vancouver B1 periprosthetic fracture of the femur. All patients were evaluated clinically and radiographically immediately postoperatively, at 3 weeks, 6 weeks, 3 months, and then annually thereafter. The minimum followup was 13 months (mean, 21 months; range, 13-30 months)., Results: Two of the 29 patients (7%) developed a nonunion; all remaining osteotomies, fractures and allografts had healed at the time of most recent evaluation. Four patients (14%) dislocated postoperatively; two were treated successfully with closed reduction, while the other two required reoperation. We identified no evidence of breakage or other complications directly attributable to the cables., Conclusions: The nonmetallic periprosthetic cables used in this series provided adequate fixation to allow for both osteotomy and fracture healing. We did not observe any complications directly related to the cables. Level of Evidence Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background: A third-generation TKA system was designed to address problems encountered with earlier designs including a high rate of patellofemoral complications. At a minimum of 5 years, we previously reported survivorship of 98.7% using revision for any reason as the endpoint for a cohort that includes the patients described in this report. That cohort was unique in that a tibial component that uses four short pegs for fixation was used in a subset of patients undergoing cruciate-retaining TKA and the tibial and femoral components were precoated with polymethylmethacrylate., Questions/purposes: We now report the survival rate, postoperative function, complications, radiographic loosening, and osteolysis at a minimum of 10 years postoperatively., Patients and Methods: We retrospectively reviewed 161 patients who underwent 179 TKAs. The patella was resurfaced in all cases and all components were cemented. Patients were evaluated clinically and radiographically for evidence of component loosening and osteolysis. Forty of the 161 patients (with 44 TKAs) had died and eight patients (nine knees) were lost to followup. For the remaining 113 patients (126 knees), the minimum followup was 10 years (mean, 11.7 years; range, 10.0-13.9 years)., Results: Survivorship at a minimum of 10 years postoperatively using revision for any reason and revision for aseptic loosening were 97.7% and 100%, respectively. Three knees were revised: one for infection, one for periprosthetic fracture, and one for postoperative arthrofibrosis. There were no reoperations for patellar component maltracking, wear or loosening, tibiofemoral polyethylene wear, osteolysis, or aseptic loosening. Hospital for Special Surgery scores improved from a mean of 47.7 (range, 23-78) preoperatively to 85.4 (range, 33-100)., Conclusions: This cruciate-retaining design had a low risk of implant failure or revision and the design changes eliminated the patellar failures seen with earlier iterations at up to 10 years., Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Unlabelled: In May 2006, the US Food and Drug Administration approved the first metal-on-metal total hip resurfacing. Surgeons wanting to implant this device were required to undergo formal industry-sponsored training before performing their first case and a technical specialist attended their initial 10 cases. Safety surveys were completed on the first 537 cases performed and included patient age, gender, diagnosis, and occurrence of any unexpected events perioperatively or postoperatively. Intraoperative data were available for all 537 cases (100%), hospital discharge and six-week data were available for 524 cases (97.6%), three-month data were available for 523 cases (97.4%), six-month data were available for 509 cases (94.3%) and one-year data were available for 449 cases (83.6%); the mean followup was 10.4 months. We documented adverse events in 40 (32 major, 8 minor) of the 537 cases including nine nerve injuries and eight dislocations. There were 14 component revisions (3.1%) [corrected] within the first year, including 10 for femoral neck fracture, two for dislocations, and two for acetabular component loosening. Complications were frequently seen among patients older than 55 years of age and in women, emphasizing the importance of appropriate patient selection for the procedure., Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Unlabelled: The optimal implant option for hip arthroplasty in the young, active patient remains controversial. There has been renewed interest for metal-on-metal hip resurfacing due to improved design and manufacturing of implants, better materials, enhanced implant fixation, theoretical advantages over conventional total hip arthroplasty, and recent Food and Drug Administration approval of two devices. Recent studies indicate satisfactory short- and midterm clinical results (1- to 10-year followup) with low complication rates, but there is a learning curve associated with this procedure, a more extensive surgical approach is necessary, and long-term results have yet to be determined. Proper patient selection may help avoid complications and improve patient outcomes. Patient selection criteria in the literature appear based predominantly on theoretical considerations without any consensus on stratifying patient risk. The most commonly reported complications encountered with hip resurfacing include femoral neck fracture, acetabular component loosening, metal hypersensitivity, dislocation, and nerve injury. At the time of clinical evaluation, patient age; gender; diagnosis; bone density, quality, and morphology; activity level; leg lengths; renal function; and metal hypersensitivity are important factors when considering a patient for hip resurfacing. Based on our review, we believe the best candidates for hip resurfacing are men under age 65 with osteoarthritis and relatively normal bony morphology., Level of Evidence: Level V, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Unlabelled: Safely obtaining adequate exposure at the time of revision total knee arthroplasty is an integral step in successfully performing the procedure. A medial capsular approach combined with an extensive intraarticular synovectomy provides adequate exposure for most patients. If further exposure is required, a quadriceps snip can be used to free the proximal extensor mechanism. The benefits of this approach include its technically simple nature and an unaltered postoperative rehabilitation regimen. We report a series of 126 consecutive revision knee procedures in which a medial capsular approach was adequate in 111 cases, representing 92% of the patients with an intact extensor mechanism. A quadriceps snip was required in nine cases. If more extensive exposure is required for an excessively stiff or difficult to expose knee, a tibial tubercle osteotomy or V-Y quadricepsplasty provides wider exposure., Level of Evidence: Therapeutic study, level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

This study reports the 11-year to 15-year results of unicompartmental knee arthroplasty with an emphasis on failure mechanisms and progression of patellofemoral arthrosis. In a prospective study of 513 consecutive potential knee replacement candidates, 59 patients (12%) had medial unicompartmental arthroplasty of the knee. All 59 patients had isolated unicompartmental disease without clinical symptoms or radiographic evidence of patellofemoral arthritis. No patient was lost to followup. The average followup was 13 years (range, 11-15 years). The mean preoperative Hospital for Special Surgery knee score of 55 points (range, 30-79 points) improved to a mean of 90 points (range, 60-100 points) at final followup. Patellofemoral symptoms were present in 1.6% of patients at 10 years; this increased markedly to 10% of patients at 15 years (p < 0.01). Four patients (10%) had moderate or severe patellofemoral symptoms at final followup; two were revised to a primary total knee replacement at 7 and 11 years for progressive patellofemoral degeneration. No component was radiographically loose and no osteolysis was seen. The Kaplan-Meier survival with loosening or revision for any reason was 98.0% +/- 2.0% at 10 years and 95.7% +/- 4.3% at 15 years. At up to 15 years, unicompartmental knee arthroplasty yielded good clinical results; however, progressive patellofemoral arthritis was the primary mode of failure.

Femoral revision total hip arthroplasty is a technically demanding procedure. In addition to these technical issues, preoperative planning can be challenging and with multiple reconstructive options available, the decision-making process can be complex. The ability to preoperatively determine the most appropriate option for reconstruction greatly assists with ensuring that the appropriate implants and instruments are available at the time of surgery. A classification of femoral bone loss is presented that guides the surgeon in selecting an appropriate method of reconstruction.

The diagnosis of septic implant failure can be difficult to make, yet is imperative for optimal patient outcomes in revision total hip arthroplasty. In most cases, a thorough history and physical examination combined with preoperative laboratory tests and an intraoperative frozen section are sufficient to differentiate septic from aseptic failure. If preoperative laboratory test values are elevated, preoperative aspiration of the hip can be used in selected patients to confirm or exclude the diagnosis of infection. Nuclear medicine studies comprise a second-line investigation to evaluate patients with a painful total hip arthroplasty in whom revision surgery otherwise is not indicated. Intraoperative tissue appearance in combination with intraoperative Gram stains are unreliable for detecting periprosthetic sepsis, and neither is adequate when considered alone for ruling out infection at the time of revision total hip arthroplasty. It is imperative that the surgeon doing revision total hip arthroplasty thoroughly understands the relative utility of preoperative and intraoperative tests used to diagnose periprosthetic sepsis.

Reconstruction of the failed acetabular component in total hip arthroplasty (THA) can be challenging. Although there are multiple reconstructive options available, a cementless acetabular component inserted with screws has been shown to have good intermediate-term results and is the reconstructive method of choice for the majority of acetabular revisions. We reviewed the results of 138 consecutive acetabular revisions done with a hemispheric, cementless acetabular component that is sintered with Ti fiber metal mesh and was inserted with line-to-line reaming and multiple screws for fixation. At a mean of 15 years, 19 acetabular components had been revised (13.8%); seven were revised for recurrent instability, six were revised for deep periprosthetic infection, five well-fixed cups were removed at the time of femoral revision, and one cup was fixed by fibrous tissue only at the time of femoral revision and was removed. One acetabular component was radiographically loose. Survivorship of the component was 81% at 15 years when revision for any reason was considered as an end point and 96% when revision for loosening or radiographic evidence of loosening was considered as a second end point. Cementless acetabular revision provides durable results at 15 years with a low rate of failure for loosening.