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Background: A 2-stage revision continues to be the standard treatment for periprosthetic joint infection (PJI) in hip arthroplasty. The use of "functional" spacers may allow patients to return to daily living while optimizing their health for revision surgery. We aimed to evaluate the clinical outcomes of different spacer types regarding infection eradication, mechanical complications, and functional outcomes., Methods: Patients who have complete Musculoskeletal Infection Society criteria for diagnosis of PJI that underwent one-stage or 2-stage revision were queried in an institutional surgical database between 2002 and 2022. Out of 286 patients, 210 met our inclusion criteria and were retrospectively reviewed for demographics, laboratory values, functional and patient-reported outcomes, and subsequent revisions. The study population had 54.3% women, a mean age of 61 years old, and a mean follow-up of 3.7 ± 3.2 years. There was no difference between age, body mass index, or Charlson Comorbidity Index scores between each cohort. Spacers were categorized as nonfunctional static, nonfunctional articulating, or functional articulating. Functional spacers were defined as those that allowed full weight bearing with no restrictions. Delphi criteria were used to define revision success, and failure was defined as a recurrent or persistent infection following definitive surgery., Results: There was a significantly lower reoperation rate after a definitive implant in the functional articulating cohort (P = .003), with a trending higher infection eradication rate and a lower rate of spacer failure compared to the nonfunctional spacer cohort. At 5 years, functional articulating spacers had a 94.1% survivorship rate, nonfunctional articulating spacers had an 81.2% survival rate, and nonfunctional static spacers had a 71.4% survival rate. In the functional articulating spacer cohort, 14.6% had yet to get reimplanted, with an average follow-up time of 1.4 years., Conclusions: Within this large cohort of similar demographics, functional articulating spacers may result in better clinical outcomes and infection eradication during 2-stage revision arthroplasty for PJI., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: There is no standard method for assembling the femoral head onto the femoral stem during total hip arthroplasty (THA). This study aimed to measure and record dynamic 3-dimensional (3D) THA head-neck assembly loads from residents, fellows, and attending surgeons, for metal and ceramic femoral heads., Methods: An instrumented apparatus measured dynamic 3D forces applied through the femoral stem taper in vitro for 31 surgeons (11 attendings, 14 residents, 6 fellows) using their preferred technique (ie, number of hits or mallet strikes). Outcome variables included peak axial force, peak resultant force, impulse of the resultant force, loading rate of the resultant force, and off-axis angle. They were compared between femoral head material, surgeon experience level, and the number of hits per trial., Results: Average peak axial force was 6.92 ± 2.11kN for all surgeons. No significant differences were found between femoral head material. Attendings applied forces more "on-axis" as compared to both residents and fellows. Nine surgeons assembled the head with 1 hit, 3 with 2 hits, 14 with 3 hits, 2 with 4 hits, and 3 with ≥5 hits. The first hit of multihit trials was significantly lower than single-hit trials for all outcome measures except the off-axis angle. The last hit of multihit trials had a significantly lower impulse of resultant force than single-hit trials., Conclusion: Differences in applied 3D force-time curve dynamic characteristics were found between surgeon experience level and single and multihit trials. No significant differences were found between femoral head material., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest form is provided with the online version of the article (http://links.lww.com/JBJS/H570).

Background: Total hip arthroplasty (THA) failure due to tribocorrosion of modular junctions and resulting adverse local tissue reactions to corrosion debris have seemingly increased over the past few decades. Recent studies have found that chemically-induced column damage seen on the inner head taper is enabled by banding in the alloy microstructure of wrought cobalt-chromium-molybdenum alloy femoral heads, and is associated with more material loss than other tribocorrosion processes. It is unclear if alloy banding represents a recent phenomenon. The purpose of this study was to examine THAs implanted in the 1990s, 2000s, and 2010s to determine if alloy microstructure and implant susceptibility to severe damage has increased over time., Methods: Five hundred and forty-five modular heads were assessed for damage severity and grouped based on decade of implantation to serve as a proxy measure for manufacturing date. A subset of heads (n = 120) was then processed for metallographic analysis to visualize alloy banding., Results: We found that damage score distribution was consistent over the time periods, but the incidence of column damage significantly increased between the 1990s and 2000s. Banding also increased from the 1990s to 2000s, but both column damage and banding levels appear to recover slightly in the 2010s., Conclusion: Banding, which provides preferential corrosion sites enabling column damage, has increased over the last 3 decades. No difference between manufacturers was seen, which may be explained by shared suppliers of bar stock material. These findings are important as banding can be avoidable, reducing the risk of severe column damage to THA modular junctions and failure due to adverse local tissue reactions., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Implant failure due to fretting corrosion at the head-stem modular junction is an increasing problem in modular total hip arthroplasty. The effect of varying microgroove topography on modular junction contact mechanics has not been well characterized. The aim of this study was to employ a novel, microgrooved finite element (FEA) model of the hip taper interface and assess the role of microgroove geometry and taper mismatch angle on the modular junction mechanics during assembly. A two-dimensional, axisymmetric FEA model was created using a modern 12/14 taper design of a CoCrMo femoral head taper and Ti6Al4V stem taper. Microgrooves were modeled at the contacting interface of the tapers and varied based on height and spacing measurements obtained from a repository of measured retrievals. Additionally, taper angular mismatch between the head and stem was varied to simulate proximal- and distal-locked engagement. Forty simulations were conducted to parametrically evaluate the effects of microgroove surface topography and angular mismatch on predicted contact area, contact pressure, and equivalent plastic strain. Multiple linear regression analysis was highly significant (p < 0.001; R 2  > 0.74) for all outcome variables. The regression analysis identified microgroove geometry on the head taper to have the greatest influence on modular junction contact mechanics. Additionally, there was a significant second order relationship between both peak contact pressure (p < 0.001) and plastic strain (p < 0.001) with taper mismatch angle. These modeling techniques will be used to identify the implant parameters that maximize taper interference strength via large in-silico parametric studies., (© 2022 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Background: Revision total hip arthroplasties (THA) are time-consuming, expensive, and technically challenging. Today's Current Procedural Terminology (CPT) codes and relative value units (RVU) may in fact disincentivize surgeons to perform revision THAs. Our study reviewed labor and time investments for each component-specific revision THA and analyzed the gap between procedural value billed and final reimbursement., Methods: A retrospective review of 165 primary and revision THAs were validated using operative notes and billing records. We stratified revision THAs by standard CPT coding (with modifiers) as single acetabular component, single femoral component, femoral head plus polyethylene liner (head/liner) exchange, all-components, and spacer placement for infection. Operative time, RVUs, total charges, deductions, and final reimbursement data was collected. Mann-Whitney U tests studied final reimbursement per minute vs per RVU in revision and primary THAs., Results: Our cohort consisted of 27 primary THAs, 26 acetabular component revisions, 32 head/liner exchanges, 26 femoral component revisions, 27 all-component revisions, and 27 spacer placements. Compared to primary THAs, every revision subgroup except for head/liner exchanges were found to reimburse less per minute and all revision subgroups reimbursed less per RVU (P < .05)., Conclusion: Physicians face less reimbursement per minute and per RVU for revision THAs. With cuts in reimbursement set forth by Centers for Medicare and Medicaid Services (CMS) and insurers, revisions may be financially unfavorable. This ultimately will lead to an impending access to care problem in the future. Our study supports the need to re-examine the RVU allocation amongst revision THAs and evaluate changes to the Current Procedural Terminology (CPT) coding system., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Proximal femoral replacement (PFR) is reserved as a salvage procedure after failed total hip arthroplasty (THA) or after wide margin resection of tumors involving the proximal femur. Although failure of the PFR construct remains a significant problem, indication has not previously been investigated as a risk factor for failure., Methods: This study retrospectively evaluated patients who underwent PFR over a consecutive 15-year period for primary sarcoma or metastatic disease of the proximal femur, compared with conversion to PFR after failed THA. PFR failure was defined as recurrent prosthetic dislocations, periprosthetic fracture, aseptic loosening, or infection that ultimately resulted in revision surgery., Results: Overall, 99 patients were evaluated, including 58 in the neoplasm and 41 in the failed THA cohorts. Failed THA patients were older (P < .001), with a greater proportion having comorbid hypertension (P = .008), cardiac disease (P = .014), and history of prior ipsilateral and intracapsular surgeries (P < .001). The failure rate was significantly higher in failed THA patients (39.0% vs 10.3%; P < .001) with significantly shorter implant survivorship on Kaplan-Meier analysis (P = .003). A multivariate Cox proportional hazards model showed that THA failure was the only independent predictor for PFR failure (hazard ratio: 4.26, 95% confidence interval: 1.66-10.94; P = .003)., Conclusion: This study revealed significantly worse PFR implant survivorship in patients undergoing PFR for the indication of failed THA compared with neoplasm. Although the underlying etiology of this relationship remains to be explicitly outlined, poor bone quality and soft tissue integrity, multiple prior surgeries, and comorbid conditions are likely contributing factors., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Femoral stem subsidence is a known cause of early implant failure, increasing the risk for aseptic loosening and periprosthetic fracture. Overall survivorship and subsidence in a novel porous tantalum-coated femoral prosthesis have not been well-studied., Methods: Consecutive patients undergoing primary total hip arthroplasty with a porous tantalum-coated femoral prosthesis between January 2008 and January 2015 with minimum 5-year follow-up were included. Clinical and radiographic data were obtained from hospital and office records. Multivariate logistic regression analyses were used to determine predictors of subsidence and clinical outcomes. Kaplan-Meier survivorship curves were performed to illustrate primary failure endpoints of (1) all-cause revision and (2) femoral prosthesis revision., Results: A total of 398 patients with a mean (±standard deviation) age of 61.0 ± 11.5 years, body mass index (BMI) 32.8 ± 8.0 kg/m 2 , and follow-up of 6.9 (range 5.0-11.2 years) were included. Survivorship at 5 years was 94.9% for all-cause revision and 98.0% for femoral component revision. Average subsidence was 1.8 ± 1.3 mm (range 0-15.5), with 8.1% patients experiencing subsidence >5 mm. Statistically significant mean improvements were observed at latest follow-up in the Hip Disability and Osteoarthritis Outcome Score Joint Replacement (40.6 ± 11.5 vs 85.2 ± 10.1, P < .001), Harris Hip Score (38.0 ± 12.0 vs 79.5 ± 12.8, P < .001), and hip flexion (92.8° ± 15.3° vs 103.3° ± 10.3°, P < .001). Multivariate logistic regression analyses revealed that greater BMI (odds ratio [OR] 1.17, P < .001), non-white/Caucasian race (OR 2.0, P = .036), and female gender (OR 2.4; P = .005) conferred a higher likelihood of subsidence >3 mm. BMI was a statistically significant and independent predictor of subsidence >5 mm (OR 1.25, P < .001) and subsidence >7 mm (OR 1.25, P < .001)., Conclusion: The trabecular metal taper femoral prosthesis conferred excellent clinical outcome improvement and survivorship. Increasing BMI was independently associated with an increased risk of subsidence in these patients and caution is recommended in utilizing this implant in obese, morbidly obese, and super morbidly obese populations., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Total hip arthroplasty (THA) in patients with abnormal proximal femoral anatomy requires an individualized treatment approach to prevent complications. Metaphyseal engaging stems in this population risk fracture, size/offset mismatch, and aseptic loosening. The Wagner conical femoral implant is a short diaphyseal engaging femoral stem that could improve treatment success in this difficult patient population., Methods: We identified 302 consecutive patients undergoing THA using the Wagner cone femoral prosthesis between January 2010 and January 2017. Clinical, radiographic, and patient-reported outcomes were obtained through chart review and radiographic measurements of postoperative X-rays. We used multivariate analysis to determine predictors of poor outcomes. Kaplan-Meier curves were created to demonstrate implant survivorship with reoperation and revision as endpoints. The average follow-up was 3.2 years, with a minimum of 2 years., Results: The implant retention survival rate during the 3.2-year study period was 98.7%. The overall reoperation rate was 4.2%, with infection followed by fracture being the most common reasons for reoperation. No patients were revised for aseptic loosening, and no patients were revised for subsidence. The average subsidence was 1.1 mm. The Harris Hip Score improved from 48.6 ± 7.3 (range, 28-64) preoperatively to 86.1 ± 8.5 (range, 66-100) at latest follow-up. The patient-reported satisfaction rate was 98.3%., Conclusion: The Wagner cone femoral prosthesis demonstrated excellent clinical, radiographic, and patient-reported functional outcomes at midterm follow-up. We recommend use of the Wagner cone in THA patients with challenging proximal femoral anatomy, small femoral diameter, or poor metaphyseal bone quality., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Aims: The aim of this study was to develop a novel computational model for estimating head/stem taper mechanics during different simulated assembly conditions., Methods: Finite element models of generic cobalt-chromium (CoCr) heads on a titanium stem taper were developed and driven using dynamic assembly loads collected from clinicians. To verify contact mechanics at the taper interface, comparisons of deformed microgroove characteristics (height and width of microgrooves) were made between model estimates with those measured from five retrieved implants. Additionally, these models were used to assess the role of assembly technique-one-hit versus three-hits-on the taper interlock mechanical behaviour., Results: The model compared well to deformed microgrooves from the retrieved implants, predicting changes in microgroove height (mean 1.1 μm (0.2 to 1.3)) and width (mean 7.5 μm (1.0 to 18.5)) within the range of measured changes in height (mean 1.4 μm (0.4 to 2.3); p = 0.109) and width (mean 12.0 μm (1.5 to 25.4); p = 0.470). Consistent with benchtop studies, our model found that increasing assembly load magnitude led to increased taper engagement, contact pressure, and permanent deformation of the stem taper microgrooves. Interestingly, our model found assemblies using three hits at low loads (4 kN) led to decreased taper engagement, contact pressures and microgroove deformations throughout the stem taper compared with tapers assembled with one hit at the same magnitude., Conclusion: These findings suggest additional assembly hits at low loads lead to inferior taper interlock strength compared with one firm hit, which may be influenced by loading rate or material strain hardening. These unique models can estimate microgroove deformations representative of real contact mechanics seen on retrievals, which will enable us to better understand how both surgeon assembly techniques and implant design affect taper interlock strength. Cite this article: Bone Joint J 2020;102-B(7 Supple B):33-40.

Background: Proposed benefits of modularity for femoral revisions in total hip arthroplasty (THA) include more precise biomechanical restoration and improved stability, but this has not been proven with use of a splined, tapered design. This study's purpose is to compare (1) complication rates, (2) functional outcomes, and (3) radiographic measures of subsidence, offset, and leg length discrepancy with the use of modular vs monoblock splined, tapered titanium stems in revision THA., Methods: We retrospectively reviewed 145 femoral revisions with minimum 2-year follow-up (mean, 5.12 years; range, 2-17.3 years). Patients receiving a modular (67) or monoblock (78) splined, tapered titanium stem for femoral revision were included., Results: There were no statistically significant differences in rates of reoperation (22.3% vs 17.9%; P = .66), intraoperative fracture (9.0% vs 3.8%; P = .30), postoperative fracture (3.0% vs 1.3%; P = .47), dislocation (11.9% vs 5.1%; P = .23), or aseptic loosening (4.5% vs 6.4%; P = .73) between the modular and monoblock cohorts, respectively. There were similar results regarding subsidence >5 mm (10.4% vs 12.8%; P = .22), LLD >1 cm (35.8% vs 38.5%; P = .74), restoration of hip offset (-5.88 ± 10.1 mm vs -5.07 ± 12.1 mm; P = .67), and Harris Hip Score (70.7 ± 17.9 vs 73.9 ± 19.7; P = .36) between groups. Multivariate regression showed no differences in complications (P = .44) or reoperations (P = .20) between groups., Conclusion: Modular and monoblock splined, tapered titanium stems demonstrated comparable complication rates, functional outcomes, and radiographic parameters for femoral revisions. However, a limited number of patients with grade IIIB or IV femoral bone loss received a monoblock stem. Future investigations are required to determine whether modularity is beneficial for more complex femoral defects., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Implant failure due to fretting-corrosion of head-neck modular junctions is a rising problem in total hip arthroplasty. Fretting-corrosion initiates when micromotion leads to metal release; however, factors leading to micromotion, such as microgrooves on the stem taper, are not fully understood. The purpose of this study is to describe a finite element analysis technique to determine head-neck contact mechanics and investigate the effect of stem taper microgroove height during head-neck assembly. Two-dimensional axisymmetric finite element models were created. Models were created for a ceramic femoral head and a CoCrMo femoral head against Ti6Al4V stem tapers and compared to available data from prior experiments. Stem taper microgroove height was investigated with a generic 12/14 model. Head-neck assembly was performed to four maximum loads (500 N, 2000 N, 4000 N, 8000 N). For the stem taper coupled with the ceramic head, the number of microgrooves in contact and plastically deformed differed by 2.5 microgrooves (4%) and 6.5 microgrooves (11%), respectively, between the finite element models and experiment. For the stem taper coupled with the CoCrMo head, all microgrooves were in contact after all assembly loads in the finite element model due to an almost identical conical angle between the taper surfaces. In the experiments, all grooves were only in contact for the 8000 N assembly load. Contact area, plastic (permanent) deformation, and contact pressure increased with increasing assembly loads and deeper microgrooves. The described modeling technique can be used to investigate the relationship between implant design factors, allowing for optimal microgroove design within material couples., Competing Interests: Conflict of Interest Statement The authors have no conflicts to disclose., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Femoral stem fracture is a rare and morbid complication after total hip arthroplasty (THA). There currently exists a paucity of reports regarding cementless non-modular, titanium, femoral stem fractures., Methods: A case report and review of the literature for modular and non-modular stem fractures was conducted., Results: We report the first documented fatigue fracture in the Wagner Self-Locking (SL) Revision (Zimmer-Biomet, Warsaw, Indiana) System., Discussion: Proximal stress shielding can lead to poor bone support and contribute to excessive cantilever bending forces, even on non-modular, titanium, tapered stems. Body mass index, prosthetic diameter, and stem length are factors that need to be vetted in order to prevent this complication.

Background: The purpose of this study was to examine the outcomes of repeat revision after failure of a constrained liner., Methods: We reviewed 1212 consecutive revisions and identified 74 (6%) revisions of a failed constrained liner in 46 patients with a mean age of 65 years. The most common reasons for revision of a constrained liner were recurrent instability (64.9%) and infection (25.7%)., Results: At a mean of 35 months, 42 of the 74 hips (57%) required repeat revision. Kaplan-Meier revision-free survival was 24% at 10 years. Thirty-two of the 74 revisions (43%) had a dislocation event after the index revision. Kaplan-Meier dislocation-free survival was 43% at 10 years. There was a higher failure rate among the 34 patients with abductor deficiency (hazard ratio 1.90, 95% confidence interval, 1.06-3.43; P = .032)., Conclusion: Patients undergoing revision of a failed constrained liner have a high likelihood of recurrent dislocation and repeat revision surgery., Level of Evidence: Level IV., (Copyright © 2018. Published by Elsevier Inc.)

Trunnionosis of total hip arthroplasty (THA) components has been an increasingly reported complication. Consensus is lacking regarding preventive practices and the overall incidence of trunnionosis. In this study, fellowship-trained adult reconstruction orthopedic surgeons were surveyed to identify expert opinions. A 25-question, web-based survey regarding trunnionosis incidence, prevention, and biomaterials was sent to 345 fellowship-trained adult reconstruction orthopedic surgeons in North America. The survey yielded 151 (43.8%) responses from surgeons with a mean of 11.97±9.49 years of experience. These surgeons believe that the material composite of the head-neck junction is the most important contributor to trunnionosis. They often choose a ceramic head with a metal alloy stem to reduce trunnionosis. They more commonly impact the femoral head 3 times than once. Fifty-one percent believe that trunnionosis leads to THA failure for between 0% and 2% of all THA revisions, whereas 48.3% believe that the failure rate is greater than 2%. More than half (53.6%) of these surgeons recommend a revision THA if a patient's serum cobalt level is greater than 10 µg/L, regardless of symptom presence. The incidence of trunnionosis appears to be increasing due to changes in implants and/or an increased awareness of the problem, with 48.3% of these surgeons believing that trunnionosis is the primary cause of THA failure for more than 1 in 50 patients. Some suggested preventive measures include cleaning and drying the trunnion, using ceramic femoral heads, matching THA components, and adding titanium sleeves on well-fixed stems that are retained during revision surgery. [Orthopedics. 2018; 41(4):e557-e562.]., (Copyright 2018, SLACK Incorporated.)

Background: In revision total hip arthroplasty (THA), proximal femoral bone loss creates a challenge of achieving adequate stem fixation. The purpose of this study was to examine the outcomes of a monoblock, splined, tapered femoral stem in revision THA., Methods: Outcomes of revision THA using a nonmodular, splined, tapered femoral stem from a single surgeon were reviewed. With a minimum of 2-year follow-up, there were 68 cases (67 patients). Paprosky classification was 3A or greater in 85% of the cases. Preoperative and postoperative Harris Hip Scores (HHS), radiographic subsidence and osseointegration, limb length discrepancy, complications, and reoperations were analyzed., Results: The Harris Hip Score improved from 37.4 ± SD 19.4 preoperatively to 64.6 ± SD 21.8 at final follow-up (P < .001). There were 16 revision procedures-8 for septic indications and 8 for aseptic indications. Subsidence occurred at a rate of 3.0% and dislocation at 7.4%. Limb length discrepancy of more than 1 cm after revision was noted in 13.6% of patients. Bone ingrowth was observed in all but 4 patients (94.1%). At 4-year follow-up, Kaplan-Meier estimated survival was 72.9% (95% confidence interval [CI] 57.0-83.8) for all causes of revision, 86.6% (95% CI 72.0-93.9) for all aseptic revision, and 95.5% (95% CI 86.8-98.5) for aseptic femoral revision., Conclusion: Although complications were significant, revision for femoral aseptic loosening occurred in only 3 patients. Given the ability of this monoblock splined tapered stem to adequately provide fixation during complex revision THA, it remains a viable option in the setting of substantial femoral bone defects., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: There are increasing reports of total hip arthroplasty failure subsequent to modular taper junction corrosion. The surfaces of tapers are machined to have circumferential machining marks, resulting in a surface topography of alternating peaks and valleys on the scale of micrometers. It is unclear if the geometry of this machined surface topography influences the degree of fretting and corrosion damage present on modular taper junctions or if there are differences between modular taper junction material couples., Questions/purposes: (1) What are the differences in damage score and surface topography between CoCr/CoCr and CoCr/Ti modular junctions? (2) How are initial surface topography, flexural rigidity, taper angle mismatch, and time in situ related to visual taper damage scores for CoCr/CoCr couples? (3) How are initial surface topography, flexural rigidity, taper angle mismatch, and time in situ related to visual taper damage scores for CoCr/Ti couples?, Methods: Damage on stem and head tapers was evaluated with a modified Goldberg score. Differences in damage scores were determined between a group of 140 CoCr/CoCr couples and 129 CoCr/Ti couples using a chi-square test. For a subgroup of 70 retrievals, selected at random, we measured five variables, including initial stem taper machining mark height and spacing, initial head taper roughness, flexural rigidity, and taper angle mismatch. All retrievals were obtained at revision surgeries. None were retrieved as a result of metal-on-metal failures or were recalled implants. Components were chosen so there was a comparable number of each material couple and damage score. Machining marks around the circumference of the tapers were measured using white light interferometry to characterize the initial stem taper surface topography in terms of the height of and spacing between machining mark peaks as well as initial head taper roughness. The taper angle mismatch was assessed with a coordinate measuring machine. Flexural rigidity was determined based on measurements of gross taper dimensions and material properties. Differences of median or mean values of all variables between material couples were determined (Wilcoxon rank-sum tests and t-tests). The effect of all five variables along with time in situ on stem and head taper damage scores was tested with a multiple regression model. With 70 retrievals, a statistical power of 0.8 could be achieved for the model., Results: Damage scores were different between CoCr/CoCr and CoCr/Ti modular taper junction material couples. CoCr/CoCr stem tapers were less likely to be mildly damaged (11%, p = 0.006) but more likely to be severely damaged (4%, p = 0.02) than CoCr/Ti stem tapers (28% and 1%, respectively). CoCr/CoCr couples were less likely to have moderately worn head tapers (7% versus 17%, p = 0.003). Stem taper machining mark height and spacing and head taper roughness were 11 (SD 3), 185 (SD 46), and 0.57 (SD 0.5) for CoCr/CoCr couples and 10 (SD 3), 170 (SD 56), and 0.64 (SD 0.4) for CoCr/Ti couples, respectively. There was no difference (p = 0.09, p = 0.1, p = 0.16, respectively) for either factor between material couples. Larger stem taper machining mark heights (p = 0.001) were associated with lower stem taper damage scores, and time in situ (p = 0.006) was associated with higher stem taper damage scores for CoCr/CoCr material couples. Stem taper machining marks that had higher peaks resulted in slower damage progression over time. For CoCr/Ti material couples, head taper roughness was associated with higher stem (p = 0.001) and head taper (p = 0.003) damage scores, and stem taper machining mark height, but not time in situ, was associated with lower stem taper damage scores (p = 0.007)., Conclusions: Stem taper surface topography was related to damage scores on retrieved head-neck modular junctions; however, it affected CoCr/CoCr and CoCr/Ti couples differently., Clinical Relevance: A taper topography of circumferential machining marks with higher peaks appears to enable slower damage progression and, subsequently, a reduction of the reported release of corrosion products. This may be of interest to implant designers and manufacturers in an effort to reduce the effects of metal release from modular femoral components.

The use of metal-on-metal bearing surfaces for total hip arthroplasty increased dramatically in the past decade for a variety of reasons, including the advantage of using larger-diameter femoral heads to reduce instability. However, recent research suggesting negative outcomes and high failure rates associated with some of these implants has decreased their use. Further, the use of larger-diameter femoral heads on relatively small femoral neck tapers has caused concern about localized corrosion at this junction, particularly with varus femoral alignment and longer femoral neck and head lengths. Although the advent of modular components offers the surgeon greater intraoperative flexibility, this modularity may prove to be a weak link when coupled with large-diameter femoral heads. This report describes a patient with a history of bilateral metal-on-metal total hip arthroplasty complicated by failure of the right hip as a result of fretting and mechanically assisted crevice corrosion. Notching of the femoral neck and head dissociation occurred 10 years after the primary procedure. The authors describe the patient's presenting symptoms, the possible etiology of the catastrophic failure, and the method of treatment and provide a brief review of metal-on-metal implants that may shed some light on the complications in this case. [Orthopedics.2016; 39(5):e984-e987.]., (Copyright 2016, SLACK Incorporated.)

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.

Innovations in the design of dual-modular femoral components have afforded surgeons several intraoperative advantages during both primary and revision total hip arthroplasty (THA). Although use of these implants has become more popular, the long-term outcomes and potential complications of introducing a second modular junction are still to be determined. In addition, concerns about corrosion potentiation at modular junctions in metal-on-metal (MOM) THA have arisen in recent studies. In this article, we present a unique case of fracture at the modular junction of the stem and modular sleeve of a dual-modular femoral component implanted with a MOM articulation. The proposed mechanisms of failure, including crevice and fretting corrosion as well as the potential effect of metal debris generated by MOM articulations, are reviewed. This case report is the first to describe component fracture at the stem-sleeve junction of this modern-generation dual-modular femoral component. Surgeons who encounter a painful dual-modular femoral stem must entertain this mode of failure and consider junctional failure as a potential diagnosis for such a patient, particularly in the setting of a MOM articulation.

A retrospective chart review was performed of all patients who had undergone revision total hip arthroplasty with a synovial aspiration with greater than 100 WBC since the institution of our electronic medical record. Infection was defined using a combination of criteria. A diagnosis of periprosthetic sepsis was established in 52 of the 253 included hips. No significant differences existed with respect to gender, age, BMI, Deyo-Charlson Comorbidity Index, or the cause of initial hip degeneration. Using receiver-operating characteristic curves accuracy was maximized for WBC of 745 or segmented cell count of 73.5% with a sensitivity of 98%, specificity of 37%, negative predictive value of 99% and accuracy of 50%. Application of the current American Academy of Orthopaedic Surgery Clinical Practice Guidelines (AAOS CPG) thresholds revealed a similar accuracy of 49%., (© 2013.)

In the evaluation of patients with a persistently painful total hip arthroplasty establishing an accurate diagnosis is paramount in the selection of a successful treatment regimen. It is unknown whether synovial analysis might differentiate aseptic loosening from other causes of failure. A physiological basis exists to suggest that aseptic loosening might be a process of non-segmented leukocytes. The objective of this study was to determine if the synovial fluid differential cell count might aid in the diagnosis of aseptic loosening. A retrospective chart review of all patients who had undergone revision hip arthroplasty with pre-operative or intra-operative aspiration results was performed. Aseptic loosening was defined as gross intraoperative movement in the absence of infection. From these results Relative-Operating Characteristic (ROC) curves were created, and sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. A diagnosis of aseptic loosening was established in 76 of the 253 hips. The ROC curves indicated that lymphocyte count does have utility in the diagnosis of aseptic loosening. If an aspirate has a combination of fewer than 2500 WBCs (sensitivity 93%, specificity 42%, NPV 94%, accuracy 57%) or more than 10% lymphocytes (sensitivity 86%, specificity 42%, NPV 87%, accuracy 55%) then the sensitivity for aseptic loosening is 96%, the specificity is 33%, the NPV is 95% and the accuracy is 52%. In patients with painful total hip arthroplasties in whom infection has been excluded, aspiration data can be a useful adjunct in the diagnosis of aseptic loosening. In aspirates with neither a WBC cell count of less than 2500 nor a lymphocyte cell count of greater than 10% aseptic loosening can be effectively "ruled out" as fewer than 5% of these patients will have aseptic loosening. While non-specific, aspirate differential can be useful to "rule-out" aseptic loosening with a sensitivity and negative predictive value well exceeding that of standard radiographs., (Copyright © 2013 Elsevier Inc. All rights reserved.)

We previously reported on the metal ion concentrations of cobalt, chromium, and titanium that were found in the serum of patients three years after they had undergone primary total hip arthroplasty as compared with the concentrations found in the serum of control patients who did not have an implant. This study is a concise update on the serum metal levels found in a cohort of these patients ten years after the time of hip implantation. Of the original seventy-five subjects, metal ion levels were available for forty patients (53%). Ten patients (hybrid group) had received a hybrid total hip replacement that consisted of a modular cobalt-alloy femoral stem with a cobalt-alloy femoral head that had been inserted with cement and a titanium acetabular socket that had been inserted without cement. Nine patients (cobalt-chromium [CoCr] group) had received an implant with an extensively porous-coated modular cobalt-alloy femoral stem and femoral head along with a titanium acetabular socket; the femoral and acetabular components had each been inserted without cement. Eight patients (titanium group) had undergone insertion of a proximally porous-coated modular titanium-alloy femoral stem with a cobalt-alloy femoral head and a titanium acetabular socket; the femoral and acetabular components had each been inserted without cement. Thirteen patients (control group) from the original control group of patients who had not received an implant served as control subjects. Serum metal levels were measured with use of high-resolution sector field inductively coupled plasma mass spectrometry. The hybrid total hip arthroplasty group had mean cobalt levels that were 3.2 times higher at 120 months than they were at baseline, and the cobalt levels in that group were significantly higher than those in the titanium total hip arthroplasty group at thirty-six, sixty, eighty-four, ninety-six, and 120 months (p < 0.01). The hybrid group had mean chromium levels that were 3.9 times higher at 120 months than they were at baseline, and the CoCr total hip arthroplasty group had chromium levels that were 3.6 times higher at 120 months than they were at baseline. The serum titanium levels were higher in the titanium group at all follow-up time intervals as compared with the levels in all other groups, and the level in the titanium group at 120 months was eighteen times higher than it was at baseline (p < 0.01). Patients with well-functioning primary metal-on-polyethylene total hip replacements had elevated serum metal levels for as many as ten years postoperatively. Furthermore, metal release at the modular femoral head-neck junctions, rather than passive dissolution from porous ingrowth surfaces, was likely the dominant source of serum cobalt and chromium.

The use of modularity, specifically dual modular femoral stems, in total hip arthroplasty has increased in popularity over the past 2 decades. While offering several distinct advantages intraoperatively, the long-term success of adding a second modular junction has yet to be established. One potential complication of increasing modularity is component fracture. We present a case of modular femoral neck prosthesis fracture necessitating revision surgery to treat this complication. Careful preoperative planning during revision of these failures is essential to avoid morbidity and unnecessary subsequent revision surgeries, as demonstrated in this case. The combined effects of crevice and fretting corrosion, large-diameter femoral head, long modular neck, metal-on-metal articulation, patient size, and activity level may have all played integral roles in creating an environment susceptible to this classic pattern of fatigue fracture., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Pseudotumor formation after hip arthroplasty is a rare complication that can occur with various head-liner articulation couples. Adverse local tissue reactions and pseudotumors have been shown to present as prosthetic infections or implant failures with a broad array of laboratory and imaging findings. We report a case of pseudotumor formation resulting from modular neckstem corrosion in a well-fixed ceramic-on-polyethylene total hip arthroplasty. The patient underwent successful revision surgery using an extended trochanteric osteotomy, long-stem revision femoral component, and headliner exchange. It is critical that surgeons are aware of the potential complications with increased component modularity and the possibility of adverse local tissue reactions resulting from fretting and crevice corrosion at modular junctions.

Early failures of metal-on-metal total hip arthroplasty (THA) occur due to aseptic loosening, metal hypersensitivity reactions, pseudotumor formation, and component seizing. The purpose of this study was to investigate the timing, common modes of failure, clinical outcomes, and incidence of metal-on-metal THA revisions. A review was performed of 80 patients who underwent revision of a failed metal-on-metal THA for any reason. The most common reason for metal-on-metal failure was aseptic acetabular loosening, with a rate of 56.25% (45/80 patients). Early failure of metal-on-metal THAs was noted, with 78% of these revisions being performed within 2 years of the index operation and 92.5% within 3 years. Furthermore, 13% of patients experienced significant localized soft tissue reactions. Mean preoperative Harris Hip Score was 42.35 ± 14.24 and mean postoperative Harris Hip Score was 66.5 ± 23.2 (range, 9.55-95.4), with an average follow-up of 438 ± 492 days (range, 40-2141), or 1.2 years.It is imperative that clinicians be cognizant of the fact that the proposed advantages of metal-on-metal THA are not without potential detrimental sequelae. This article proposes an algorithm to aid in diagnosing the etiology of a painful metal-on-metal THA, as well as 2 classification schemes regarding metal-on-metal THA complications to help direct treatment., (Copyright 2012, SLACK Incorporated.)

Modular femoral components have been developed to aid in recreating native femoral version, limb length, and offset in total hip arthroplasty. Use of modular implants results in cost savings, as well. Inventory can be reduced while allowing intraoperative flexibility and options. With modular implants, the femoral prosthesis can be built in situ, which is helpful in minimizing incision length and surgical dissection. However, additional modular junctions are associated with increased concern for component failure through taper fretting, fatigue fracture, and local corrosion, which may contribute to elevated serum metal ion levels. The recent trend toward using larger diameter femoral heads may impart higher loads and stress than were seen previously. Although modular components offer a plethora of intraoperative options in primary and revision total hip arthroplasty, the long-term effects of these additional junctions remains unknown.

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.

The goal of this study is to evaluate the efficacy of using an extended trochanteric osteotomy (ETO) as part of a 2-stage exchange procedure for prosthetic hip infections. Twenty-three consecutive infected total hip arthroplasties in which an ETO was used as part of a 2-stage exchange procedure were retrospectively reviewed. An ETO was used when the femoral component could not be extracted using standard techniques. Clinical and radiographic parameters were evaluated at an average of 49 months of follow-up. Postoperatively, 20 of 23 (87%) patients had resolution of their infection, with healing of the ETO in 22 of 23 patients at a mean of 11.5 weeks. Preoperative modified D'Aubigne and Postel score means of 2.4 for pain and 2.6 for walking ability significantly improved (P < .001) to 5.3 and 4.9. Use of an ETO as part of a 2-stage exchange arthroplasty can be performed safely and effectively in appropriately selected cases.

Periprosthetic femur fractures after total hip arthroplasty are a growing concern as their prevalence is expected to rise. A retrospective review was performed of all patients undergoing revision total hip arthroplasty with an extended trochanteric osteotomy (ETO) for treatment of a Vancouver B2/B3 fracture at our institution. Fourteen patients were identified having a minimum of 2-year follow-up. Clinical and radiographic evaluation was performed for all patients. At a mean 44.5 months of follow-up, mean modified D'Aubigne and Postel scores were 8.6. In all cases the ETO and fracture healed with radiographic evidence of osseointegration of the femoral component. Use of an ETO for the treatment of periprosthetic femur fractures provides excellent exposure, facilitates component implantation, and is compatible with fracture healing and good short-term clinical results.

Porous tantalum is an alternative metal for total joint arthroplasty components that offers several unique properties. Its high volumetric porosity (70% to 80%), low modulus of elasticity (3 MPa), and high frictional characteristics make it conducive to biologic fixation. Tantalum has excellent biocompatibility and is safe to use in vivo. The low modulus of elasticity allows for more physiologic load transfer and relative preservation of bone stock. Because of its bioactive nature and ingrowth properties, tantalum is used in primary as well as revision total hip arthroplasty components, with good to excellent early clinical results. In revision arthroplasty, standard and custom augments may serve as a structural bone graft substitute. Formation of a bone-like apatite coating in vivo affords strong fibrous ingrowth properties and allows for substantial soft-tissue attachment, indicating potential for use in cases requiring reattachment of muscles and tendons to a prosthesis. Development of modular components and femoral stems also is being evaluated. The initial clinical data and basic science studies support further investigation of porous tantalum as an alternative to traditional implant materials.

A retrospective radiographic evaluation of 39 acetabulae reconstructed with Trilock press-fit components (Depuy, Warsaw, IN) without use of supplementary fixation was performed. The following radiographic criteria were evaluated: change in component inclination angle, migration, osteolytic areas, and radiolucent lines. Acetabular components were considered loose when there was migration greater than four millimeters, change in abduction angle greater than four degrees, or a concentric radiolucent line greater than two millimeters. The average length of follow-up was 12.6 years. Six of the 39 (15.4%) total hip arthroplasties were considered loose. Two (5.1%) of these were revised and four (10.4%) were asymptomatic at the time of latest follow-up. Significant areas of osteolysis were found in 15 hips (38.5%). We conclude that the Trilock acetabular component provides adequate fixation and satisfactory long-term results.