Femoral Head Penetration Rates and Oxidation of Highly Cross-Linked Polyethylene Hip Liners Implanted More Than 10 Years.

BACKGROUND: Highly cross-linked polyethylene (HXLPE) was introduced to improve wear in total hip arthroplasty, with manufacturers implementing different thermal treatments to reduce oxidation. It is important to understand how long-term time in vivo affects the wear of these materials. The purpose of this study was to investigate the wear and oxidative performance of first-generation HXLPE hip inserts implanted for greater than 10 years and compare annealed and remelted HXLPE formulations. METHODS: There were 49 total hip arthroplasty liners retrieved during routine revision surgery as part of an institutional review board-approved implant retrieval program. Penetration rates for the liners were calculated as the difference between the thickness of the unloaded and loaded regions divided by implantation time. Oxidation indices for the rim, locking mechanism, articulating surface, and backside regions were measured using Fourier-transform infrared spectroscopy according to American Society for Testing and Materials 2102. Mann-Whitney U tests were used to determine the statistical difference between annealed and remelted components. RESULTS: The cohort had an average implantation time of 13.1 ± 2.6 years for annealed and 12.1 ± 1.7 years for remelted components. The components were revised most often for polyethylene wear, instability, and loosening. The penetration rate averaged 0.0177 ± 0.014 mm/year for annealed components and 0.015 ± 0.022 mm/year for remelted components. Penetration rates did not differ between the remelted and annealed cohorts (P = .28). Oxidation indices were found to be significantly higher in the annealed cohort for all regions of interest (P < .001). CONCLUSIONS: Oxidation was found to be higher in the annealed HXLPE; however, this does not seem to be associated with greater wear as we found the average penetration rates for the cohorts were low, and the penetration rates were similar between the annealed and remelted cohorts.

Retrieval Analysis of Titanium Nitride Coatings for Orthopaedic Implants.

BACKGROUND: The first generation of titanium nitride (TiN) coatings for orthopaedic implants was clinically introduced in the 1990s because of their promising biocompatibility, wear resistance, and corrosion resistance. This study evaluated the in vivo performance of early TiN-coated knee and hip implants, focusing on the bearing surfaces and mechanisms of in vivo damage. METHODS: There were 13 TiN-coated implants (5 knee and 8 hip) retrieved from 8 patients as part of a multi-institutional implant retrieval program. The average implantation time was 4.25 years for knees and 17.5 years for hips. Implant revisions occurred for various reasons, including polyethylene wear, loosening, pain, infection, and instability. Components were examined using a semiquantitative scoring method, and surface roughness measurements were performed using white-light interferometry. Surface morphology, chemistry, and particle characterization were also assessed by scanning electron microscopy. RESULTS: For hips, mild corrosion was found on femoral head tapers, along with severe scratching on certain femoral heads. Knee implants exhibited low burnishing and scratching for both mechanisms. Roughness measurements (Sa) were 37.3 nm (interquartile range = 22.0 to 62.4) for hips and 85.3 nm (interquartile range = 66.3 to 110) for knees. The observed scratch depth in both hip and knee implants due to third-body particles ranged from 0.3 to 1.3 µm. The coating coverage remained intact in the majority of the implants, with 2 cases of small, localized cohesive chipping and substrate exposure. CONCLUSIONS: The results of this study confirm the potential in vivo durability of early TiN coatings and will be useful in benchmarking wear tests for modern TiN-coated orthopaedic implants.

Publication Rates of Poster and Podium Presentations at the American Association of Hip and Knee Surgeons Annual Meetings 2016 to 2019.

BACKGROUND: The objective of this study was to provide the poster and podium publication rates from the 2016 to 2019 American Association of Hip and Knee Surgeons (AAHKS) annual meetings and assess the quality of presentations ultimately published during this time. METHODS: Posters and podiums from 2016 to 2019 were located through the AAHKS e-poster and meeting archives. Titles were queried on Google, Google Scholar, and PubMed. Presentation title, topic type, number of authors, degrees held by first author, and award status were collected. For each identified full-text publication, journal name, study type, dates of online and print publication, and journal impact factor (JIF) were also obtained. RESULTS: A total of 1,274 abstracts were presented at the 2016 to 2019 AAHKS annual meetings with an overall publication rate of 67.8% (864 of 1,274). Podiums (4.0 months, 95% confidence interval [CI]: 3.0 to 4.0) were more likely to be published earlier than posters (7.0 months, 95% CI: 6.0 to 7.0) (P < .001). The median JIF of published abstracts was 3.3 (95% CI: 3.3 to 3.7) with no significant difference in mean JIF of published posters or podiums (3.3 ± 1.0 versus 3.3 ± 1.0, P = .554). The likelihood of publication was significantly higher for podiums (odds ratio [OR]: 3.41, 95% CI: 2.29 to 5.07, P < .001), award-winning presentations (OR: 4.78, 95% CI: 1.69 to 13.55, P = .003), and with more authors (OR: 1.09, 95% CI: 1.02 to 1.16, P = .014). DISCUSSION: This analysis demonstrates abstracts presented at the AAHKS annual meetings from 2016 to 2019 had an overall publication rate of 67.8%, with podiums (86.4%) 3 times as likely to be published as posters (63.6%). If selected to present at the AAHKS annual meeting, individuals can be confident that their work has a high chance of eventual publication.

Titanium-Titanium Junctions in the Knee Corrode, Generating Damage Similar to the Hip.

BACKGROUND: Previous studies identified corrosion between the modular tibial components of total knee arthroplasty devices. However, gaps persist. Compared to the hip, damage modes that occur within taper junctions in the knee remain poorly understood. In this study, we investigated corrosion on total knee arthroplasty components with titanium-titanium junctions. We asked the following question: under typical in vivo cyclic loading conditions, will the same alloy damage modes from total knee arthroplasty devices resemble those documented in the hip? METHODS: A total of 50 paired titanium alloy tibial baseplates and stems were collected and semiquantitatively analyzed using Goldberg corrosion scoring. To characterize damage, a subsection of moderately and severely corroded components was sectioned and imaged using scanning electron and digital optical microscopy. RESULTS: Of the 100 device components, 95% showed visual evidence of corrosion. The initial contact area between the stem and bore generally occurred 3 mm from the stem taper base. Scanning electron microscopy revealed 4 damage modes, including oxide film formation, crevice corrosion, selective dissolution, and pitting. CONCLUSIONS: Each of the damage modes identified in modular titanium-titanium tibial junctions was previously reported by total hip arthroplasty retrieval studies. Cumulatively, our results suggest that mechanically assisted crevice corrosion promoted this damage in vivo.

Comparison of Early Postoperative Step and Stair Counts With the Direct Anterior Approach Versus the Posterior Approach for Total Hip Arthroplasty.

BACKGROUND: The purpose of this study was to evaluate the impact of direct anterior approach (DAA) or posterior approach (PA) on step and stair counts after total hip arthroplasty using a remotely monitored mobile application with a smartwatch while controlling for baseline characteristics. METHODS: This is a secondary data analysis from a prospective cohort study of patients utilizing a smartphone-based care management platform. The primary outcomes were step and stair counts and changes from baseline through one year. Step and stair counts were available for 1,501 and 847 patients, respectively. Longitudinal regression models were created to control for baseline characteristics. RESULTS: Patients in the DAA group had significantly lower body mass index (P = .049) and comorbidities (P = .028), but there were no significant differences in age (P = .225) or sex (P = .315). The DAA patients had a higher average and improvement from baseline in step count at 2 and 3 weeks postoperatively after controlling for patient characteristics (P = .028 and P = .044, respectively). The average stair counts were higher for DAA patients at one month postoperatively (P = .035), but this difference was not significant after controlling for patient demographics. Average stair ascending speeds and changes from baseline were not different between DAA and PA patients. Descending stair speed was higher at 2 weeks postoperatively for DAA patients, but was no longer higher after controlling for baseline demographics. CONCLUSIONS: After controlling for baseline characteristics, DAA patients demonstrate earlier improvement in step count than PA patients after total hip arthroplasty. However, patient selection and surgeon training may continue to influence outcomes through a surgical approach.

Improved patient reported outcomes with the direct anterior approach versus the posterior approach for total hip arthroplasty in the early post-operative period.

BACKGROUND: Patients undergoing total hip arthroplasty (THA) with the direct anterior approach (DAA) may experience faster recovery but may also have better baseline health than those who undergo THA with the posterior approach (PA). This study aimed to compare patient-reported outcome measures (PROMs) between the DAA and PA while controlling for baseline factors. METHODS: This is a secondary data analysis from a prospective cohort study of patients utilizing a smartphone-based care management platform following THA. The primary outcomes were HOOS JR and EQ-5D-5L through 1 year and change from baseline. Longitudinal regression models were created to control for baseline characteristics and investigate the impact of surgical approach on PROMs. RESULTS: Of 1364 THAs evaluated, 731 (53.6%) were female, and 840 (61.6%) used the PA. Patients in the PA group were of similar age but had higher body mass index and comorbidity scores. Pre-operative HOOS JR and EQ-5D-5L were comparable, but higher post-operatively in the DAA group through 6 months (p = 0.03 and p = 0.005). At 1 year post-operatively, HOOS JR and EQ-5D-5L did not vary between groups (p = 0.48 and p = 0.56), nor did changes from baseline (p = 0.47 and p = 0.11). After controlling baseline characteristics, DAA was significantly associated with higher average HOOS JR through 6 months (p = 0.03) and EQ-5D-5L through 3 months (p = 0.005), but not at 12 months (p = 0.89 and p = 0.56). CONCLUSION: THA patients undergoing DAA demonstrate earlier improvements in HOOS JR and EQ-5D-5L. However, these differences may not be clinically significant and are not evident at 1-year post-operative. Patient selection and surgeon training may continue to affect outcomes by surgical approach.

Are Corrosion and Material Loss a Threat for Titanium-Titanium Tapers in Total Hip Arthroplasty Modular Acetabular Components?

BACKGROUND: Extensive research has reported on fretting corrosion and material loss for a variety of metal taper interfaces in orthopedic devices. For modular acetabular shell-liner constructs, the interfaces studied thus far have consisted of mixed-metal pairings, and the risk of fretting corrosion and material loss for the all-titanium (Ti) shell-liner taper junction in one ceramic-on-ceramic (COC) design remains poorly understood. We asked: do Ti shell-liner taper interfaces in COC total hip arthroplasty devices show in vivo evidence of (1) fretting and/or corrosion, and (2) quantifiable potential material loss? METHODS: We examined 22 shell-liner pairs and 22 single liners from retrieved COC components. The taper interface surfaces were assessed for fretting corrosion using a semiquantitative scoring method and imaged with scanning electron microscopy. A subcohort of components was measured with a coordinate measuring machine, and volumetric material loss and maximum wear depth were calculated. RESULTS: Fretting corrosion at the taper interfaces was minimal to mild for 95% of liners and 100% of shells. Imaging revealed fretting marks within a band of corrosion on some implants and evidence of corrosion not in the proximity of mechanical damage. Estimated material loss ranged from 0.2 to 1.3 mm3 for liners, and 0.5 to 1.1 mm3 for shells. Maximum wear depth for all components was 0.03 mm or less. CONCLUSIONS: Our results indicate that, compared to other taper junctions in total joint arthroplasty, the risk of corrosion and material loss may be minimal for Ti shell-liner interfaces.

Short-Term Surface Damage Mechanisms of Retrieved Highly Cross-Linked Polyethylene Patellar Components.

BACKGROUND: Previous retrieval studies of patellar components for total knee arthroplasty focused on historical designs and polyethylene materials that are no longer clinically relevant. Therefore, this study aimed to compare revision reasons and surface damage mechanisms of conventional, gamma inert sterilized polyethylene and highly cross-linked polyethylene (HXLPE) patellar components in contemporary designs from a single manufacturer. METHODS: A total of 114 gamma inert and 76 HXLPE patellar components were gathered in a multicenter orthopaedic implant retrieval program. Patient age and body mass index were similar between cohorts (P = .27 and P = .42, respectively); however, the gamma inert cohort was implanted longer (µdifference = 3.1 years; P = .005). A matched subset was created based on the total knee arthroplasty design, patellar shape, and implantation time. Revision reasons were gathered from revision operating notes, and surface damage was examined via the Hood scoring method. Differences between HXLPE and gamma inert cohorts were evaluated using Mann-Whitney U-tests. RESULTS: The most common revision reasons were infection, loosening, and instability, with the most common patellar complication resulting in revision being patellar loosening for both cohorts with similar incidences for both (chi-square; P = .60, P = .59). The most common surface damage modes were burnishing, scratching, and pitting in both cohorts. Total surface damage was significantly higher in the gamma inert components (P = .02), but not in the matched subset (P = .46). CONCLUSION: Overall, the clinical performance of HXLPE was similar to that of conventional polyethylene for patellar components with short implantation times. While this study provides much needed information on the performance of HXLPE patellae in short-term retrievals, long-term studies are still needed.

Hospital Charges Are Not Associated With Episode-of-Care Costs or Complications After Total Joint Arthroplasty.

BACKGROUND: The Centers for Medicare and Medicaid Services (CMS) now requires hospitals to publish charges for commonly performed procedures. This study aimed to evaluate compliance with the price transparency mandate and to determine if there is a correlation between hospital charges and episode-of-care claims costs and outcomes after total hip arthroplasty (THA) and total knee arthroplasty (TKA). METHODS: We identified a consecutive series of 2476 Medicare patients who underwent primary THA or TKA from 2018 to 2019 at one of 18 hospitals. Each hospital website was explored to assess compliance with the new price transparency requirements. Demographics, comorbidities, complications, and readmissions were recorded. Ninety-day episode-of-care claims costs were calculated using CMS claims data. Multivariate regression was performed to determine whether hospital charges had any association with complications, readmissions, or episode-of-care costs. RESULTS: There was no correlation between published hospital charges and inpatient costs (r = 0.087), postacute care costs (r = 0.126), or episode-of-care costs (r = 0.131). When controlling for demographics and comorbidities, there was no association between published charges and complications (P = .433) or readmissions (P = .141). All hospitals posted some shoppable services information online, but only 7 (39%) were fully compliant by publishing all price data. Of the 11 hospitals (61%) publishing hospital THA and TKA charges, the mean charge was $48,325 (range, $12,625-$79,531). CONCLUSION: Published charges for TKA and THA had no correlation with episode-of-care claims costs and were not associated with clinical outcomes. Despite efforts by CMS to increase price transparency, few hospitals were fully compliant, and a wide range in published charges was found.

Patient Satisfaction with Orthopedic Telemedicine Health Visits During the COVID-19 Pandemic.

Background:Telemedicine usage in orthopedic surgery has seen a dramatic increase as a result of the severe acute respiratory syndrome coronavirus 2 pandemic. The purpose of this study was to examine patient perceptions with telemedicine at a large orthopedic practice.Materials and Methods:An anonymous online survey was distributed to all patients who received a telemedicine health visit at our institution for musculoskeletal complaints from March 17 to June 1, 2020. Responses were scored on a 5-point Likert scale (strongly disagree, disagree, neutral, agree, and strongly agree, 1-5) and analyzed by average score and percent reaching top box.Results:A majority of patients (76.5%) were satisfied with their visit, and only 19.2% did not want telemedicine as a future option. Patients who presented for follow-up visits (4.11 vs. 3.94, p = 0.0053; 48% vs. 41%, p = 0.02) and utilized video (4.21 vs. 3.88, p < 0.001; 51% vs. 39%, p < 0.001) were more satisfied. Average satisfaction between older (>65 years) and younger patients was similar (4.06 vs. 4.06, p = 0.97), however, younger patients were more likely to reach top box (42% vs. 51%, p < 0.001). Confidence that the physician came to the correct diagnosis (r = 0.78, p < 0.001) and receiving the same information and care as an in-office visit (r = 0.60, p < 0.001) demonstrated the strongest correlation with satisfaction and desire for future telemedicine visits, respectively. Interestingly, 31.1% of patients would have sought treatment elsewhere had telemedicine not been an option.Conclusions:Overall, satisfaction rates are high for orthopedic patients undergoing telemedicine visits. Patients are more confident in telemedicine when presenting for a follow-up visit and with the use of video.

Distal Femoral Replacement and Periprosthetic Joint Infection After Non-Oncological Reconstruction: A Retrospective Analysis.

BACKGROUND: Distal femoral replacement (DFR) is commonly used to manage massive bone loss around the knee arising from aseptic loosening, periprosthetic joint infection (PJI), and distal femoral fractures. A number of studies report the outcome of DFR with considerable variation in long-term survivorship. This study investigated the outcome of DFR for patients with aseptic failures, fractures, and PJI. METHODS: A retrospective review of 182 patients who underwent DFR for non-oncological indications between 2002 and 2018 was conducted. Data collected included the following: indication, postoperative complications, reoperation, revision, and follow-up. Implant survivorship with Kaplan-Meier curves along with a log-rank test for different preoperative indications was performed. A Cox regression model was used to evaluate the risk of revision. RESULTS: The overall postoperative complication rate was very high at 36%. The most common complication was PJI (17%). The rate of reoperation for any cause was 29.7%, and the revision rate was 13.7%. The most common cause of re-revision was PJI (7.1%). Revision-free survivorship of the DFR implant was 91.6% at 1 year, 87.9% at 2 years, 82.5% at 5 years, and 73.4% at 10 years. Patients who had a prior-PJI had the lowest survivorship compared to patients undergoing DFR for management of periprosthetic fracture and mechanical loosening. Additionally, the prior-PJI group was at a fourfold increased risk of postoperative PJI compared to the aseptic group. CONCLUSION: DFR is a valuable reconstructive option for patients with massive bone loss around the knee. However, patients undergoing DFR are at high risk of complications, reoperations, and failure.

Fretting Corrosion, Third-Body Polyethylene Damage, and Cup Positioning in Primary vs Revision Dual Mobility Total Hip Arthroplasty.

BACKGROUND: Dual mobility (DM) articulations were introduced for total hip arthroplasty to reduce the risk of instability for patients who have a high risk of dislocation. The use of DM constructs in both primary and revision total hip arthroplasty has been steadily increasing, leading to concerns regarding potential risks of fretting corrosion, polyethylene wear, metal release, and failure due to component positioning. METHODS: A total of 56 retrieved DM constructs were collected. The inner and outer polyethylene liner surfaces were assessed for 7 damage mechanisms, and fretting corrosion was evaluated for the femoral stem, head, and modular liner. Three polyethylene liners with the greatest amounts of embedded debris were examined using scanning electron microscopy. Energy-dispersive X-ray spectroscopy was used to determine the elemental content of the debris. Acetabular cup orientation was analyzed radiographically using the EBRA (Einzel-Bild-Roentgen-Analyse) method. RESULTS: The devices were revised most frequently for infection (36%), loosening (21%), and instability/dislocation (18%). The most common polyethylene damage mechanisms were scratching, pitting, burnishing, and embedded debris, and no difference in total damage was found between primary and revision cases. Scanning electron microscopy/energy-dispersive X-ray spectroscopy revealed that debris morphology and composition were consistent with porous titanium coating, resulting from cup loosening or broken screws and augments. A total of 71% and 50% of the constructs were determined to be within the Lewinnek safe zone for inclination and anteversion, respectively. CONCLUSION: The most notable mechanisms of surface damage were due to third-body debris, especially for the polyethylene surfaces which articulate against cobalt-chromium femoral heads and acetabular liners. Scratching of the femoral head and the metal liner from this debris may support the clinical use of ceramic for DM bearing surfaces in the future.

Reasons for Revision, Oxidation, and Damage Mechanisms of Retrieved Vitamin E-Stabilized Highly Crosslinked Polyethylene in Total Knee Arthroplasty.

BACKGROUND: In order to improve oxidation resistance, antioxidants such as vitamin-E are added to polyethylene used in the bearing surfaces of orthopedic components. Currently, little is known about the efficacy of this treatment in vivo. This study therefore reports on the reasons for revision, surface damage mechanisms, and oxidation of retrieved vitamin E-stabilized highly crosslinked polyethylene (HXLPE) for total knee arthroplasty. METHODS: We examined 103 retrieved knee inserts fabricated from vitamin E (VE)-stabilized HXLPE and 67 fabricated from remelted HXLPE as a control. The implantation times were 1.2 ± 1.3 and 1.5 ± 1.3 years for the VE and control cohorts, respectively. The inserts were evaluated for 7 surface damage mechanisms using a semiquantitative scoring method and analyzed for oxidation using Fourier-transform infrared spectroscopy. Reasons for revision were also assessed using operative notes created at time of retrieval. RESULTS: Both groups were revised primarily for instability, infection, and loosening. Burnishing, pitting, and scratching were the most common damage mechanisms observed, with the VE cohort demonstrating less surface damage than the control. Measured oxidation for the cohort was low, with a median oxidation index of 0.09 ± .05 for the articulating surface, 0.05 ± 0.06 for the backside, 0.08 ± 0.06 for the anterior/posterior surfaces, and 0.08 ± 0.05 for the stabilizing post. As compared to the control cohort, oxidation tended to be less for the VE group at the articulating (P < .001) and backside (P = .003) surfaces, although the median differences were minimal and may not be clinically significant. CONCLUSION: The results indicate positive fatigue damage resistance and oxidation resistance for the retrieved VE-stabilized total knee arthroplasty inserts.

Is There Material Loss at the Conical Junctions of Modular Components for Total Knee Arthroplasty?

BACKGROUND: Clinical concern exists regarding fretting corrosion and material loss from taper junctions in orthopedic devices, with previous research focusing on the modular components from total hip arthroplasty. Comparatively little has been published regarding the fretting corrosion and material loss in modular knee devices. The purpose of this study is to evaluate fretting corrosion damage and quantify material loss for conical total knee arthroplasty taper interfaces. METHODS: Stem tapers of 166 retrieved modular knee devices were evaluated for fretting corrosion using a semiquantitative scoring method. High precision profilometry was then used to determine volumetric material loss and maximum wear depth for a subset of 37 components (implanted for 0.25-18.76 years). Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to characterize the observed damage. RESULTS: Mild to severe fretting corrosion was observed on the majority of tapers, with 23% receiving a maximum visually determined damage score of 4. The median rate of volumetric material loss was 0.11 mm3/y (range 0.00-0.76) for femoral components (both cone and bore taper surfaces combined) and 0.01 mm3 (range 0.00-8.10) for tibial components. Greater rates of material loss were associated with mixed metal pairings. There was a strong correlation between visual fretting corrosion score and calculated material loss (ρ = 0.68, P < .001). Scanning electron microscopy revealed varying degrees of scratching, wear, fretting corrosion, and instances of cracking with morphology not consistent with fretting corrosion, wear, or fatigue. CONCLUSION: Although visual evidence of fretting corrosion damage was prevalent and correlated with taper material loss, the measured volumetric material loss was low compared with prior reports from total hip arthroplasty.

What Is the Incidence of Cobalt-Chromium Damage Modes on the Bearing Surface of Contemporary Femoral Component Designs for Total Knee Arthroplasty?

BACKGROUND: The purpose of this study was to determine the incidence of metal release in contemporary total knee arthroplasty and the patient-related factors associated with this release. METHODS: In total, 256 retrieved cobalt-chromium femoral components were collected through a multi-institutional orthopedic implant retrieval program (implanted: 1-15 years). Implants were mainly revised for loosening (84/256), instability (62/256), and infection (46/256). Third-body damage was assessed using a semiquantitative scoring method. Microscale electro-corrosion damage (MECD) was evaluated using digital optical microscopy. Radii of curvature were measured from representative components to calculate anterior-posterior and medial-lateral ratios. Femoral component surface roughness was measured using a white light interferometer. Using a multivariable linear model, associations between damage score, implant, and patient factors were tested. Spearman's ρ correlation tests were performed to determine the association between roughness measurements and damage score. RESULTS: Mild to severe damage was observed in 52% (134/256) of the components. In the multivariable linear model, anterior-posterior ratio (ß = -8.07; P < .001), loosening (ß = -0.52; P = .006), and patient weight (ß = 0.01; P = .007) were associated with damage score. Suspected MECD damage was observed in 82% (209/256) of components. The Ra value (ρ = 0.196; P = .002) and Rq value (ρ = 0.157; P = .012) increased as the damage score increased. CONCLUSION: The findings of this retrieval study support that similar damage mechanisms exist in contemporary and long-term total knee arthroplasty devices. Additionally, we observed associations between loosening, anterior-posterior conformity, and patient weight with increased surface damage.

Same Day Total Hip Arthroplasty Performed at an Ambulatory Surgical Center: 90-Day Complication Rate on 549 Patients.

BACKGROUND: There is an increasing interest in outpatient total hip arthroplasty (THA), as there are perceived benefits to the patient, insurer, and overall healthcare system. However, the safety of outpatient total joint arthroplasty has not been studied. METHODS: Five hundred forty-nine patients who underwent mini-posterior THA at a freestanding independent ambulatory surgical center (ASC) were reviewed. All patients were discharged to home on the day of surgery. RESULTS: The average age of the patients was 54.4 years (range 27-73). The average American Society of Anesthesiologists score was 1.6 (range 1-3). Of the 549 patients, 3 (0.5%) admitted from the surgery center to our local hospital. One patient was admitted for pain control after failing to disclose his long-term high-dose narcotic dependence, one patient was admitted for an acetabular component migration identified on postoperative x-ray, and one patient was admitted for hypotension, bradycardia, and an acute polyarthralgia exacerbation. An additional patient was seen 2 days after surgery in a local emergency department for oversedation secondary to narcotics and later discharged to home. CONCLUSION: Outpatient THA at an ASC is safe and effective when performed on the appropriately indicated patient. There were 4 visits to the hospital within 2 days of surgery. Only 1 was related to medical events, 2 were pain control and/or medication-related and the final was technique-related. Known orthopedic complications including infection, dislocation, and deep vein thrombosis appear consistent with the literature for a series of this size. Same day discharge THA in an ASC is safe and reproducible.

Fretting and Corrosion Damage in Taper Adapter Sleeves for Ceramic Heads: A Retrieval Study.

BACKGROUND: During revision surgery with a well-fixed stem, a titanium sleeve can be used in conjunction with a ceramic head to achieve better stress distribution across the taper surface. In vitro testing suggests that corrosion is not a concern in sleeved ceramic heads; however, little is known about the in vivo fretting corrosion of the sleeves. The purpose of this study was to investigate fretting corrosion in sleeved ceramic heads in retrieved total hip arthroplasties. METHODS: Thirty-seven sleeved ceramic heads were collected during revision. The femoral heads and sleeves were implanted 0.0-3.3 years. The implants were revised predominantly for instability, infection, and loosening. Fifty percent of the retrievals were implanted during a primary surgery. Fretting corrosion was assessed using the Goldberg-Higgs semiquantitative scoring system. RESULTS: Mild-to-moderate fretting corrosion scores (score = 2-3) were observed in 92% of internal tapers, 19% of external tapers, and 78% of the stems. Severe fretting corrosion was observed in 1 stem trunnion that was previously retained during revision surgery and none of the retrieved sleeves. There was no difference in corrosion damage of sleeves used in primary or revision surgery. CONCLUSION: The fretting corrosion scores in this study were predominantly mild and lower than reported fretting scores of cobalt-chrome heads in metal-on-polyethylene bearings. Although intended for use in revisions, we found that the short-term in vivo corrosion behavior of the sleeves was similar in both primary and revision surgery applications. From an in vivo corrosion perspective, sleeves are a reasonable solution for restoring the stem taper during revision surgery.

Do Stem Taper Microgrooves Influence Taper Corrosion in Total Hip Arthroplasty? A Matched Cohort Retrieval Study.

BACKGROUND: Previous studies identified imprinting of the stem morphology onto the interior head bore, leading researchers to hypothesize an influence of taper topography on mechanically assisted crevice corrosion. The purpose of this study was to analyze whether microgrooved stem tapers result in greater fretting corrosion damage than smooth stem tapers. METHODS: A matched cohort of 120 retrieved head-stem pairs from metal-on-polyethylene bearings was created controlling for implantation time, flexural rigidity, apparent length of engagement, and head size. There were 2 groups of 60 heads each, mated with either smooth or microgrooved stem tapers. A high-precision roundness machine was used to measure and categorize the surface morphology. Fretting corrosion damage at the head-neck junction was characterized using the Higgs-Goldberg scoring method. Fourteen of the most damaged heads were analyzed for the maximum depth of material loss and focused ion beam cross-sectioned to view oxide and base metal. RESULTS: Fretting corrosion damage was not different between the 2 cohorts at the femoral head (P = .14, Mann-Whitney) or stem tapers (P = .35). There was no difference in the maximum depths of material loss between the cohorts (P = .71). Cross-sectioning revealed contact damage, signs of micro-motion, and chromium-rich oxide layers in both cohorts. Microgroove imprinting did not appear to have a different effect on the fretting corrosion behavior. CONCLUSION: The results of this matched cohort retrieval study do not support the hypothesis that taper surfaces with microgrooved stems exhibit increased in vivo fretting corrosion damage or material release.

Corrosion Damage and Wear Mechanisms in Long-Term Retrieved CoCr Femoral Components for Total Knee Arthroplasty.

BACKGROUND: Metal debris and ion release has raised concerns in joint arthroplasty. The purpose of this study was to characterize the sources of metallic ions and particulate debris released from long-term (in vivo >15 years) total knee arthroplasty femoral components. METHODS: A total of 52 CoCr femoral condyles were identified as having been implanted for more than 15 years. The femoral components were examined for incidence of 5 types of damage (metal-on-metal wear due to historical polyethylene insert failure, mechanically assisted crevice corrosion at taper interfaces, cement interface corrosion, third-body abrasive wear, and inflammatory cell-induced corrosion [ICIC]). Third-body abrasive wear was evaluated using the Hood method for polyethylene components and a similar method quantifying surface damage of the femoral condyle was used. The total area damaged by ICIC was quantified using digital photogrammetry. RESULTS: Surface damage associated with corrosion and/or CoCr debris release was identified in 51 (98%) CoCr femoral components. Five types of damage were identified: 98% of femoral components exhibited third-body abrasive wear (mostly observed as scratching, n = 51/52), 29% of femoral components exhibited ICIC damage (n = 15/52), 41% exhibited cement interface damage (n = 11/27), 17% exhibited metal-on-metal wear after wear-through of the polyethylene insert (n = 9/52), and 50% of the modular femoral components exhibited mechanically assisted crevice corrosion taper damage (n = 2/4). The total ICIC-damaged area was an average of 0.11 ± 0.12 mm2 (range: 0.01-0.46 mm2). CONCLUSION: Although implant damage in total knee arthroplasty is typically reported with regard to the polyethylene insert, the results of this study demonstrate that abrasive and corrosive damage occurs on the CoCr femoral condyle in vivo.

Is there material loss at the backside taper in modular CoCr acetabular liners?

BACKGROUND: Metal wear and corrosion products generated by hip replacements have been linked to adverse local tissue reactions. Recent investigations of the stem/head taper junction have identified this modular interface as another possible source of metal debris; however, little is known regarding other modular metallic interfaces, their ability to produce metal debris, and possibly to provide insight in the mechanisms that produce metal debris. QUESTIONS/PURPOSES: We asked three questions: (1) can we develop a reliable method to estimate volumetric material loss from the backside taper of modular metal-on-metal liners, (2) do backside tapers of modular metal-on-metal liners show a quantifiable volumetric material loss, and, if so, (3) how do regions of quantitatively identified material loss correspond to visual and microscopic investigations of surface damage? METHODS: Twenty-one cobalt-chromium (CoCr) liners of one design and manufacturer were collected through an institutional review board-approved retrieval program. All liners were collected during revision surgeries, where the primary revision reason was loosening (n=11). A roundness machine measured 144 axial profiles equally spaced about the circumference of the taper region near the rim to estimate volume and depth of material loss. Sensitivity and repeatability analyses were performed. Additionally, visual and scanning electron microscopy investigations were done for three liners. RESULTS: Our measurement method was found to be reproducible. The sensitivity (how dependent measurement results are on experimental parameters) and repeatability (how consistent results are between measurements) analyses confirmed that component alignment had no apparent effect (weak correlation, R2=0.04) on estimated volumetric material loss calculations. Liners were shown to have a quantifiable material loss (maximum=1.7 mm3). Visual investigations of the liner surface could identify pristine surfaces as as-manufactured regions, but could misidentify discoloration as a possible region of material loss. Scanning electron microscopy more accurately distinguished between as-manufactured and damaged regions of the taper. CONCLUSIONS: The roundness machine has been used to develop a repeatable method for characterizing material loss; future work comparing a gravimetric standard with estimations of material loss determined from the roundness machine may show the accuracy and effectiveness of this method. Liners show rates of material loss that compare with those reported for other taper junctions. Visual inspection alone may misidentify as-manufactured regions as regions of material loss. CLINICAL RELEVANCE: This study identifies the acetabular liner/shell interface in modular metal-on-metal devices as a potential source of metal wear or corrosion products. The relation between metal debris and clinical performance, regardless of the type of bearing couple, is a concern for clinicians. Therefore, it is important to characterize every type of modular junction to understand the quantity, location, and mechanism(s) of material loss.