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Background: Standard treatment for periprosthetic joint infection (PJI) involves 2-stage exchange with placement of an antibiotic-impregnated cement spacer (ACS). Conflicting evidence exists on the role of ACS in development of acute kidney injury (AKI) after first-stage surgery. In this randomized clinical trial, we aimed to compare the incidence of AKI between the first-stage of a planned 2-stage exchange vs 1-stage exchange. This study design isolates the effect of the ACS in otherwise identical treatment groups., Methods: The primary outcome variable was AKI, defined as a creatinine ≥1.5 times baseline or an increase of ≥0.3 mg/dL. Risk factors for AKI were evaluated using bivariate statistical tests and multivariable logistic regression., Results: Patients who underwent the first stage of a planned 2-stage exchange were significantly more likely to develop AKI compared with the 1-stage exchange group (15 [22.7%] vs 4 [6.6%], P = .011). On multivariable regression analysis, ACS placement (odds ratio 7.48, 95% confidence limit 1.77-31.56) and chronic kidney disease (odds ratio 3.84, 95% confidence limit 1.22-12.08) were independent risk factors for AKI., Conclusion: Our study provides evidence that high-dose antibiotic cement spacers for treatment of PJI are an independent risk factor for AKI. Therefore, efforts to minimize nephrotoxicity should be employed in revision for PJI when possible., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Posterior-stabilized total knee arthroplasty (TKA) with gradually variable radii (G-curve) femoral condylar geometry is now available. It is believed that a G-curve design would lead to more mid-flexion stability leading to reduced incidence of paradoxical anterior slide. The objective of this study was to assess the in vivo kinematics for subjects implanted with this type of TKA under various conditions of daily living., Methods: Tibiofemoral kinematics of 35 patients having posterior-stabilized TKA with G-curve design were analyzed using fluoroscopy while performing three activities: weight-bearing deep knee bend, gait, and walking down a ramp. The subjects were assessed for range of motion, condylar translation, axial rotation, cam-spine engagement, and condylar lift-off., Results: The average weight-bearing flexion during deep knee bend was 111.4°. On average, the subjects exhibited 5.4 mm of posterior rollback of the lateral condyle and 2.0 mm of the medial condyle from full extension to maximum knee flexion. The femur consistently rotated externally with flexion, and the average axial rotation was 5.2°. Overall movement of the condyles during gait and ramp-down activity was small. No incidence of condylar lift-off was observed., Conclusion: Subjects in this study experienced consistent magnitudes of posterior femoral rollback and external rotation of the femur with weight-bearing flexion. The variation is similar to that previously reported for normal knee where the lateral condyle moves consistently posterior compared to the medial condyle. Subjects experienced low overall mid-flexion paradoxical anterior sliding and no incidence of condylar lift-off leading to mid-flexion stability., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: We sought to evaluate the outcomes of cementless acetabular components used in patients with Crowe II and III dysplasia, and to compare outcomes between cups placed within vs outside of an "anatomic" zone. Our specific aims were to (1) plot hip centers in these patients at our institution to characterize "anatomic" vs "nonanatomic" positions, (2) evaluate the association between hip center and radiographic loosening, (3) determine whether hip center was associated with acetabular component revision, and (4) compare patient-reported outcome scores between groups., Methods: We retrospectively reviewed 88 primary cementless total hip arthroplasties at a mean follow-up of 10 years (range 2-26 years). Patients were 85% female, with a mean age of 44 years (range 28-61 years) and a body mass index of 27 kg/m 2 (range 19-42 kg/m 2 ). Medical records and radiographs were reviewed, and a survey was conducted for all patients. Anatomic hip center was defined using the 4-zone system, wherein centers are "anatomic" if they are <1 cm superior and <1 cm lateral to the approximate femoral head center. Cox proportional analyses were used to compare outcomes between groups., Results: Seventy hips (80%) had an anatomic hip center. Anatomic hips had a lower incidence of radiographic acetabular loosening (0% vs 17%, P = .007) and cup revision (0% vs 28%, P = .0002). There were no differences in Hip Disability and Osteoarthritis Outcome and Joint Replacement Scores (96.2 ± 5 vs 91.9 ± 12, P = .7)., Conclusion: The incidence of aseptic loosening and cup revision were lower when hip center was <1 cm superior and 1 cm lateral to the approximate femoral head center., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Data addressing risk factors predictive of mortality and reoperation after periprosthetic femur fractures (PPFxs) are lacking. This study examined survivorship and risk ratios for mortality and reoperation after surgical treatment for PPFx and associated clinical risk factors., Methods: A retrospective review was performed for 291 patients treated surgically for PPFx between 2004 and 2013. Primary outcomes were death and reoperation., Results: Mortality at 1 year was 13%, whereas the rate of reoperation was 12%. Greater span of fixation and revision arthroplasty (vs open reduction internal fixation) trended toward a lower likelihood of reoperation., Conclusion: After PPFx, patients have a 24% risk of either death or reoperation at 1 year. Factors contributing to increased mortality are nonmodifiable. Risk of reoperation is minimized with greater span of fixation and performance of revision arthroplasty., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The diagnosis of adverse local tissue reaction (ALTR) after metal-on-metal total hip arthroplasty (MoMTHA) presents a significant challenge. No single biomarker is specific for ALTR. The purpose of this study was to determine if the ratio of cobalt to chromium ions is useful for diagnosing ALTR in MoMTHA. In 89 bearing-related revision THAs, preoperative cobalt and chromium ion levels were compared to an intraoperative soft tissue damage grading scale. The average cobalt to chromium ratio was 2.96 (0-20). There was no correlation between the tissue scale and the cobalt to chromium ratio (R=0.095; P=0.41). Many variables affecting ion production/excretion mitigate the use of the ion ratio. The cobalt to chromium ratio is not a predictive biomarker for ALTR in MoMTHA., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Ion levels have been shown to reliably predict abnormal function of the bearing surface with increased wear, but ion levels should not be used alone as a trigger for when to proceed with revision surgery with metal-metal articulations. Risk stratification strategies help determine which patients should be monitored more closely with serial ion levels, cross-sectional imaging with a MARS MRI, or proceed on to revision. Based on the current data available, an ion level greater than 4.5 ppb (Cr or Co) may serve as a threshold for when abnormal wear is occurring, and is suggested as a trigger for a MARS MRI scan., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The purpose of this study was to determine if cobalt and chromium ion levels can predict soft tissue damage at total hip revision. This study included 90 metal-on-metal total hip patients with preoperative cobalt and chromium ion levels. Tissue damage noted at revision surgery was graded on a 4-point scale. Sensitivity, specificity, and predictive values were calculated for various threshold values. Receiver operating characteristic analysis was conducted. Using 7 ppb as a threshold, cobalt and chromium ion levels had poor sensitivity and specificity (Co, 65% and 56%; Cr, 29% and 75%). Positive predictive values for cobalt and chromium were only 48% and 26% respectively. The area under the curve was 0.37 for cobalt and 0.44 for chromium. The length of time to revision significantly correlated with tissue damage (P = .001). Ion levels are unreliable predictors of periarticular soft tissue damage and should not be used in isolation as surgical intervention triggers., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The success of metal bearings is dependent on several parameters. The effects of in vivo forces on the deformation of monoblock acetabular components have yet to be determined. The purpose of our study was to assess the amount of deformation with press-fit fixation of 1-piece metal acetabular components. Four manufacturers provided 1-piece metal acetabular components in each size (30 cups). Testing was conducted using a custom vise to simulate press-fit fixation, and measurements were performed with a Mitutoyo Test device (Aurora, Ill). Previously determined in vivo forces were used in the press-fit simulation. All components deformed under simulated in vivo applied loads. Component deformation ranged from 15 to 300 µm. Larger cups with thinner walls to accommodate larger heads had the greatest deformation and often exceeded the range of reported clearances from the manufacturers (76-227 µm)., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The study purpose was to analyze current results of modern cementless femoral components in young patients having total hip arthroplasty (THA) or hip resurfacing. Twenty-two studies (n = 5907; hips = 6408) evaluating modern cementless THA in young patients and 15 studies evaluating hip resurfacing (n = 3002; hips = 3269) were included. Meta-analysis techniques were used to pool failure rates. The pooled failure rate for THA using femoral revision for mechanical failure as an end point was 1.3% (95% confidence interval [CI], 1.0%-1.7%) at a mean 8.4 years of follow-up. At a mean of 3.9 years of follow-up, the pooled mechanical failure rate of the femoral component for hip resurfacing was 2.6% (95% CI, 2.0-3.4). In conclusion, the enthusiasm for hip resurfacing should be tempered by these data. Longer follow-up and direct comparison trials are required to confirm these findings.

The purpose of this study was to asses the fate of incomplete seating of press-fit acetabular components. From 1990 to 2002, 587 hip arthroplasties were performed using a single-design acetabular component inserted with a press-fit technique with no additional fixation. Complete radiographic follow-up at a mean 9.2 years was available for 343 cases. One hundred thirty-three acetabular components had incomplete seating on the initial postoperative radiograph and 210 cases had complete seating. Of 133 components, 125 (94%) had evidence of complete zone 2 filling. Zone 2 focal osteolysis was present in 22 patients. There were no intraoperative fractures. No acetabular components were revised for loosening. Incomplete seating of press-fit acetabular components is safe and effective in achieving initial and long-term fixation. Zone 2 lucencies when present initially are not associated with increased failure risks. Vigorous attempts to completely seat the acetabular component appear to be unwarranted.

Infection is an unfortunate complication of total knee arthroplasty. Current literature supports 2-stage reimplantation as the gold standard. Controversy exists whether static or articulating spacers are the best interim treatment method. Seventy-six 2-stage reimplantation procedures met the study inclusion criteria. There were 28 static spacers and 48 articulating spacers. The eradication rate was 94.7% in the articulating group compared with 92.1% in the static group (P = 0.7). There were no significant differences in postoperative Knee Society Scores pain scores. There were 28 (58%) good to excellent function scores in the articulating group and 10 (36%) in the static group (P = .05). Interim use of an articulating spacer maintains excellent infection eradication rates and may improve function over the use of static spacers.

Hip instability is a common postoperative complication after revision surgery. This study sought to define the prevalence of hip instability after 2-stage reimplantation without an articulating spacer. A joint registry review identified 110 patients undergoing 2-stage reimplantation. Fifty-five patients (56 hips) were alive at the time of data collection. Instability was documented and risk factors were analyzed. Of the 56 hips, 14 (25%) dislocated. Five of these 14 patients had chronic abduction insufficiency. Six patients required rerevision to attain stability. There were no significant differences between dislocators and nondislocators in abduction angle, head size, cup size, liner type, or leg length. The 25% (14/56) dislocation rate reported here is unacceptable. Interim articulating spacers, postoperative bracing, large head technology, and constrained liners are treatment methods that should be considered in this group of patients.

The goal of knee arthroplasty is to relieve pain and normalize range of motion while providing stability through the gait cycle. Postoperative, significant (>15 degrees ) flexion contractures can cause persistent pain and altered gait mechanics. This study evaluated the efficacy of revision surgery for painful flexion contractures. Of the 14 patients included in the study, 10 had complete resolution of their flexion contracture. There was significant improvement in extension (P < .0001), flexion (P = .002), and total arc of motion (P < .0001). Knee Society (KSS) pain scores improved significantly (P < .001), whereas KSS function scores did not significantly improve (P = .66). Revision surgery for symptomatic flexion contractures can improve range of motion and diminish pain. The best form of treatment is avoidance through careful flexion and extension gap balancing during primary surgery.

A retrospective review of patients with joint arthroplasty was performed to determine if body mass index has increased with time and if the body mass index of patients with arthroplasty was significantly different than that of the general population. We also sought to determine if reimbursement kept pace with this growing cohort. The number of obese patients increased from 30.4% in 1990 to 52.1% in 2005 (P < .0001). In 2005, 24% of the general population was obese, whereas 52.1% of arthroplasty patients were obese. Physician reimbursement decreased 38% for knee arthroplasty and 46% for hip arthroplasty and the need for total joint arthroplasty because of these confounding variables will increase exponentially beyond scheduled expectations. Patients and health policy forecasters must understand the interrelationship between obesity and the need for arthroplasty.

Acetabular component deformation secondary to forces encountered during insertion is a potential consequence of the press-fit technique. This study characterized the stiffness of Pinnacle 100 cups (DePuy, Warsaw, Ind) via mechanical testing and used this information with intraoperative measurements of cup deformation to calculate the in vivo forces acting on cups inserted during hip arthroplasty in 21 patients. We found that 90.5% of cups had measurable compression deformity, averaging 0.16 +/- 0.16 mm. The corresponding forces acting on these cups averaged 414 +/- 421 N. For hard-on-hard bearing surfaces, such in vivo deformation of acetabular shells may result in negative clinical consequences such as equatorial loading with increased wear and potential seizing of components, chipping of ceramic inserts, or locking mechanism damage.

The appropriate treatment for the young patient with post-collapse avascular necrosis (AVN) of the femoral head continues to be controversial. Femoral surface replacement (FSR) has emerged as a potential strategy to delay total hip arthroplasty in these patients. Between 1997 and 2003, 37 FSR procedures were performed. Success was defined as patients not requiring revision surgery or having a Harris hip pain score of 30 or greater. Failure was defined as patients having revision surgery or a Harris hip pain score of 20 or less. The overall failure rate based on Harris hip pain scores and revision surgery was 64.8% (24/37 procedures). Fifteen (40.5%) procedures required revision surgery, whereas 9 (24.3%) patients were considered failures based on their pain scores. The purpose of this study was to determine if FSR is a viable option for post-collapse AVN. We conclude that hemiresurfacing for AVN is an unpredictable procedure. This procedure is no longer offered as a treatment option for post-collapse AVN at our institution.

This study evaluates the difficult reconstructive challenge of severe proximal femoral bone loss. We present intermediate-term results of 46 hips with extensive proximal femoral bone loss that underwent revision total hip arthroplasty using cementless distal fixation without supplemental allograft. All were evaluated with the Harris hip score at a minimum of 2 years. Radiographs were assessed using the Engh fixation scale. At a mean of 6.4 (range 2-12) years, 43 of the 46 prostheses were functioning well. Two patients required revision for symptomatic loosening, and 1 prosthesis remains radiographically loose with a fair clinical score. Mean Harris hip score was 77 at last follow-up. There were 6 intraoperative femur fractures, 9 dislocations, 10 cases of severe stress shielding, and no infections.

This study assessed the early morbidity associated with modular component exchange surgery for the treatment of accelerated polyethylene wear and osteolysis in 55 patients. Review of the surgical records revealed no significant intraoperative complications, little intraoperative blood loss (mean 333 mL), no allogenic blood transfusions, and no recorded postoperative deep vein thromboses. Eighteen percent of patients, however, experienced postoperative dislocation. Five patients dislocated multiple times, 3 of which required rerevision surgery. Two patients required rerevision for femoral implant fractures related to osteolysis and 1 additional patient required rerevision due to catastrophic failure of the acetabular component 5 years postoperatively. With an average follow-up of 30 months, 6 of the 55 patients treated with modular exchange required rerevision. The results of this study suggest that instability is the most prevalent early complication associated with modular component exchange. As such, we believe that more stable constructs should be emphasized, possibly at the expense of polyethylene thickness.

A white blood cell count (WBC) of >50000 cell/mm(3) from a knee aspirate with >or=80% polymorphonuclear cells (PMNCs) is suggestive of infection. This study sought to determine if these same criteria were applicable when interpreting aspirates from a total knee. Of 440 revision total knee arthroplasties, 86 patients had preoperative aspirations of the knee before revision. Fifty-five aspirates were from aseptic failures; 31 aspirates were from patients determined to have septic failure. The mean white blood cell (WBC) count in aspirates from the aseptic group was 645 cells/mm(3) (SD = 878). The mean WBC count in the septic group was 25951 cells/mm(3) (SD = 34994; P=<.001). The mean percentage of PMNCs was statistically higher in the septic group compared with the aseptic group (72.8% vs 27.3%; P=<.001). The synovial fluid WBC count differential analysis is a statistically relevant indicator of the presence or absence of infection in revision knee arthroplasty. Aspirates with a WBC count of 2500 per milliliter and 60% PMNCs are highly suggestive of infection.

Hip instability is the leading cause of morbidity after total hip arthroplasty. Surgical strategies that have been used to eliminate recurrent instability include component revision, trochanteric advancement, or the use of constrained components. Between 1986 and 1997, 731 revision total hip arthroplasties were performed at our institution. A total of 29 patients underwent modular component exchange to treat hip instability. After revision surgery, 16 of 29 (55%) patients experienced redislocation. Nine (31% overall) patients dislocated repeatedly after modular component exchange. Five of the 9 patients who dislocated repeatedly (17% overall) ultimately required rerevision to obtain stability. Modular component exchange is an unpredictable procedure in definitively solving hip stability problems. The limitations of this procedure in treating this complex multifactorial problem must be understood by patient and surgeon alike., (Copyright 2002, Elsevier Science (USA))

Satisfactory performance of revision total knee arthroplasty (TKA) requires adequate exposure. This article shows the patella inversion method of exposure in a large consecutive series of revision TKAs.Between 1987 and 1999, 420 revision TKAs were performed. Exposure was facilitated by the patella inversion method. No attempt was made to evert the patella. This technique of exposure was used in 95% (397 of 420) of patients. There were no episodes of patellar tendon avulsion in this series. Multiple exposure options are available in revision TKA. Extensile techniques violate the extensor mechanism. For most patients, these methods were unnecessary. The patella inversion method afforded adequate exposure in most patients without violating the extensor mechanism.