Advanced Interventional Procedures for Knee Osteoarthritis: What Is the Current Evidence?

The prevalence of knee osteoarthritis (OA) is the highest among all joints and likely to increase over the coming decades. Advances in the repertoire of diagnostic capabilities of imaging and an expansion in the availability and range of image-guided interventions has led to development of more advanced interventional procedures targeting pain related to OA pain while improving the function of patients presenting with this debilitating condition. We review the spectrum of established advanced interventional procedures for knee OA, describe the techniques used to perform these procedures safely, and discuss the clinical evidence supporting each of them.

Bone Cements Used in Vertebral Augmentation: A State-of-the-art Narrative Review.

Vertebral compression fractures (VCFs) are common in osteoporotic patients, with a frequency projected to increase alongside a growing geriatric population. VCFs often result in debilitating back pain and decreased mobility. Cement augmentation, a minimally invasive surgical technique, is widely used to stabilize fractures and restore vertebral height. Acrylic-based cements and calcium phosphate cements are currently the two primary fill materials utilized for these procedures. Despite their effectiveness, acrylic bone cements and calcium phosphate cements have been associated with various intraoperative and postoperative incidents impacting VCF treatment. Over the past decade, discoveries in the field of biomedical engineering and material science have shown advancements toward addressing these limitations. This narrative review aims to assess the potential pitfalls and barriers of the various types of bone cements.

Characterizing focal muscle signal on MRI in flexor-pronator muscles' status post ulnar collateral ligament reconstruction.

OBJECTIVE: Focal high signal is commonly seen about the flexor pronator mass on MRI in some patients after ulnar collateral ligament (UCL) reconstruction of the elbow. The etiology of this high signal is unclear and not described in literature. The hypothesis is that the edema we see on post-operative MRI is related to palmaris longus graft harvest rather than secondary to other causes of muscle edema such as denervation or muscle strain. METHODS AND MATERIALS: An IRB waiver-approved, retrospective search of our radiology database was conducted using the keywords "ucl," "elbow," and "reconstruction" between 1/01/2012 and 1/01/2022, with search parameters set as MRI for exam type. The images were reviewed to evaluate for high signal at the flexor pronator mass by a junior and a senior musculoskeletal radiologist. The surgical notes were then reviewed in electronic medical record system to see which graft was used for the UCL reconstruction. RESULTS: The cohort comprised of 33 patients (1 female/32males, 14-51 years old) who had undergone UCL reconstructions. Four patients were excluded from the study secondary to the surgical note not specifying which graft was used. The surgical and imaging dates were also recorded with the largest time gap of 7 years between the surgery and imaging. Seventeen of the 29 patients had palmaris longus harvested from the ipsilateral arm, 1 patient had palmaris longus harvested from the contralateral arm, 2 patients had an internal brace, and 9 patients had a hamstring graft. Seventeen out of 17 (100%) patients with ipsilateral palmaris longus graft demonstrated focal edema at the flexor pronator mass while 0/12 of the patients without the palmaris longus graft showed the focal edema seen by its counterparts. CONCLUSION: High signal which is commonly seen at the flexor pronator mass in patient status most UCL reconstruction of the elbow is secondary to the palmaris longus harvest rather than other etiologies such as muscle strain, retear, or trauma.

Frequency of Coexistent Spinal Segment Variants: Retrospective Analysis in Asymptomatic Young Adults.

BACKGROUND AND PURPOSE: Spinal segment variants are highly prevalent and can potentially lead to incorrect spinal enumeration and, consequently, interventions or surgeries at the wrong vertebral levels. Our aim was to assess the prevalence of spinal segment variants and to study the potential association among these variants in a population without histories of spine symptoms. MATERIALS AND METHODS: Consecutive computed tomography exams of 450 young adults originally evaluated for non-spinal conditions and without a history of spinal diseases from a single institution. In addition to using descriptive statistics for reporting frequencies of spinal segment variants, the association between these variants was studied by calculating odds ratios and their 95% confidence interval. Consecutive CT exams were evaluated to determine the total number of presacral segments, presence of cervical rib, thoracolumbar transitional vertebra, iliolumbar ligament, and lumbosacral transitional vertebra. RESULTS: The spinal segment distribution variants (an atypical number of presacral segments or an atypical distribution of thoracolumbar vertebrae), cervical rib, thoracolumbar transitional vertebra, and lumbosacral transitional vertebra were reported in 23.8%, 4.2%, 15.3%, and 26.4% of cases in our study population. The presence of a cervical rib or a thoracolumbar transitional vertebra was associated with concurrent lumbosacral transitional vertebra (OR = 3.28; 95% CI, 1.29-8.47 and 1.87; 95% CI, 1.08-3.20, respectively). The inability to visualize the iliolumbar ligament was also associated with the presence of cervical ribs (OR = 3.06; 95% CI, 1.18-7.80). CONCLUSIONS: In a population of asymptomatic young adults, spinal segment variants are both highly prevalent with a high rate of coexistence. When a spinal segment variant (eg, transitional vertebra) is diagnosed, additional imaging might be considered for accurate spine enumeration before interventions or operations.

Osteoid Osteomas of the Talus: A Case Report of Four Patients.

Osteoid osteomas are benign bone tumors that are commonly found in the cortical segments of long bone but can occasionally occur in the talus of the foot. They typically present in younger males and are characterized by lesions with a vascularized nidus surrounded by sclerotic bone. Plain radiographs can often miss the diagnosis, requiring further imaging with computed tomography (CT) or magnetic resonance imaging (MRI). Lesions often lead to a significant inflammatory response resulting in an impaired range of motion and nocturnal pain. Conservative management with non-steroidal anti-inflammatory medications and a walking boot is considered first-line therapy, with failure to respond being an indication for surgical intervention. Surgical treatment traditionally consisted of en bloc resection but has been replaced by CT-guided radio-frequency ablation (RFA) when conservative management has failed. Four cases of osteoid osteoma of the talus are presented which all went on to RFA after conservative management failed. The patients' non-specific symptomatology and unremarkable findings on plain radiographs led to further evaluation using MRI or CT, which aided in the diagnosis. Following imaging, RFA was performed which resulted in 100% relief of pain and symptoms in all four patients and a return to full activity without limitations. Osteoid osteomas of the talus present unique challenges due to the non-specific symptoms and complex surrounding anatomy that accompanies this condition. Management should include the use of CT for localization and RFA of the lesion, which we have shown leads to complete resolution of symptoms and return to normal daily activities.

An Interim Analysis of the First 102 Patients Treated in the Prospective Vertebral Augmentation Sacroplasty Fracture Registry.

PURPOSE: To evaluate the efficacy of sacroplasty for treating sacral insufficiency fractures, including the effect on pain relief, patient function and adverse event rates in an as-treated on-label prospective data registry. MATERIALS AND METHODS: Observational data including patient reported outcomes (PROs), patient characteristics, osteoporosis treatment, fracture duration, cause of sacral fractures and image guidance used for treatment were collected for patients undergoing sacroplasty. The PROs were collected at baseline then at one, three, and at six months following the procedure. The primary outcomes were pain as measured by the Numerical Rating Scale (NRS) and function as measured by the Roland Morris Disability Questionnaire (RMDQ). Secondary outcomes included adverse events, cement leakage, new neurologic events, readmissions and death. RESULTS: The interim results for the first 102 patients included significant pain reduction with mean pain improvement scores at six months decreasing from 7.8 to 0.9 (P < .001) and significant improvement in function with mean RMDQ scores improving from 17.7 to 5.2 (P < .001). Most procedures were performed under fluoroscopy (58%). There was cement leakage in 17.7% of the subjects but only one adverse event which was a new neurologic deficit related to cement extravasation. The readmission rate was 16% mostly due to additional back pain and fractures and there were no subject deaths. CONCLUSIONS: Sacroplasty with cement augmentation for acute, subacute and chronic painful sacral insufficiency fractures caused by osteoporosis or neoplastic disorders results in highly significant improvements in pain and function with very low rate of procedural related adverse events.

Computed Tomography and Magnetic Resonance Imaging Overlay in the Spine for Surgical Planning: A Technical Report.

BACKGROUND: Computed tomography (CT) and magnetic resonance imaging (MRI) studies are used separately for surgical planning of spine surgery. Advanced techniques exist for creating CT-MR fusion images, but at this time these techniques are not easily accessible for large-scale use. TECHNIQUE: We propose a simple graphical technique for CT-MR image overlay, for use in the surgical planning of spinal decompression and guidance of intraoperative resection. The proposed technique involves overlaying a single cross-section from anatomically comparable MRI and CT studies on any software with basic image editing functions. RESULTS: We demonstrate CT-MR fusion images of 8 patients of the senior author in which the technique was used. We found that it can also be referenced intraoperatively for navigation. CONCLUSIONS: Compared to other techniques, our proposed method can be easily implemented by clinicians to create simple CT-MRI fusion images that can be useful for preoperative planning and intraoperative navigation.

Guiding therapeutic plasma exchange for antibody-mediated rejection treatment in lung transplant recipients - a retrospective study.

Antibody-Mediated Rejection (AMR) due to donor-specific antibodies (DSA) is associated with poor outcomes after lung transplantation. Currently, there are no guidelines regarding the selection of treatment protocols. We studied how DSA characteristics including titers, C1q, and mean fluorescence intensity (MFI) values in undiluted and diluted sera may predict a response to therapeutic plasma exchange (TPE) and inform patient prognosis after treatment. Among 357 patients consecutively transplanted without detectable pre-existing DSAs between 01/01/16 and 12/31/18, 10 patients were treated with a standardized protocol of five TPE sessions with IVIG. Based on DSA characteristics after treatment, all patients were divided into three groups as responders, partial responders, and nonresponders. Kaplan-Meier Survival analyses showed a statistically significant difference in patient survival between those groups (P = 0.0104). Statistical analyses showed that MFI in pre-TPE 1:16 diluted sera was predictive of a response to standardized protocol (R2  = 0.9182) and patient survival (P = 0.0098). Patients predicted to be nonresponders who underwent treatment with a more aggressive protocol of eight TPE sessions with IVIG and bortezomib showed improvements in treatment response (P = 0.0074) and patient survival (P = 0.0253). Dilutions may guide clinicians as to which patients would be expected to respond to a standards protocol or require more aggressive treatment.

Ultrasound of Musculoskeletal Hematomas: Relationship of Sonographic Appearance to Age and Ease of Aspiration.

OBJECTIVE: The purpose of this study was to evaluate the safety and efficacy of ultrasound-guided aspiration of musculoskeletal hematomas, evaluate the associations between the sonographic appearance of hematomas and their age with ease of aspiration, and determine if there is an optimal time frame for aspiration. MATERIALS AND METHODS: A retrospective search of our radiology database was conducted using the keywords "hematoma" and "aspiration" for procedures performed from January 1, 2008, through September 28, 2017, by three fellowship-trained musculoskeletal radiologists. Associations between the ease of aspiration and echotexture of the hematoma and between the ease of aspiration and age of the hematoma were assessed with a marginal ordinal logistic regression model to account for patient-level clusters. Pairwise comparisons of the ease of aspiration between the different echotextures were adjusted for multiple comparisons with the Tukey-Kramer method. This same method was also used to calculate the odds ratio (OR) for the age of the hematoma and ease of aspiration and decompression. Clinical follow-up was assessed for infection and symptomatic relief. RESULTS: The cohort was composed of 148 patients (77 male and 71 female patients) with a mean age of 48 years (age range, 16-80 years). One hundred patients underwent clinical follow-up: There were no instances of infection and all patients reported symptomatic relief. Marginal proportional odds model showed an OR of 3.77 when comparing the ease of aspiration between hypoechoic hematomas and hematomas showing the other echotextures combined (i.e., complex, heterogeneous, echo-genic), which was statistically significant (p = 0.010). The OR of the ease of aspiration in relation to the age of a hematoma for each additional week was 1.03 with a p value of 0.547, which shows that there is no correlation between the age of the hematoma and ease of aspiration. CONCLUSION: Ultrasound-guided aspiration of hematomas is a safe and effective procedure. The sonographic appearance of a hematoma is unrelated to its age. Although a hematoma with a hypoechoic appearance is easier to aspirate than hematomas with other echotextures, the appearance and age of a hematoma should not dissuade one from trying to aspirate it.

Appropriate Management of Vertebral Fragility Fractures: Development of a Pathway Based on a Vertebral Compression Fracture Registry.

BACKGROUND: The BenchMarket Medical (BMM) Vertebral Compression Fracture (VCF) Registry, now known as Talosix, is a collaborative effort between Talosix (the authorized registry vendor), Noridian Healthcare Solutions, and clinicians to gather outcomes evidence for cement augmentation treatments in patients with acute painful osteoporotic VCFs. The VCF Registry was designed to provide outcomes evidence to inform the Medicare payer's "coverage with evidence development" decision to authorize reimbursement for cement augmentation treatments. OBJECTIVES: The purpose of this article was to present a pathway for appropriate use of vertebral augmentation based on the findings of the VCF Registry. STUDY DESIGN: Prospective observational data, including patient characteristics, diagnosis, process of care, and patient-reported outcomes (PROs) for pain and function, were collected from patients undergoing cement augmentation treatment. The PROs were collected at baseline, 1, 3, and 6 months following the procedure. SETTING: The VCF Registry is a national ongoing registry with no specified end time or designated sample size. METHODS: Primary outcomes were pain improvement measured using the Numeric Rating Scale and function improvement, measured using the Roland Morris Disability Questionnaire (RMDQ). Secondary outcomes included cement leakage, new neurologic deficits, adverse events, readmissions, and death. RESULTS: The VCF Registry delivered outcomes data to support Noridian's "coverage with evidence development" decision. A total of 732 patients were included in this study. Registry outcomes confirmed postmarket evidence of highly significant pain relief with mean pain score improvement of 6.5/10 points at 6 months. Function also improved significantly with mean RMDQ score change of 11.4/24 points 6 months after surgery. Results also showed the safety and reliability of cement augmentation. LIMITATIONS: The nature of the registry data is that it contains nonrandomized, nonplacebo controlled data and should not be perceived as such. The real-world setting and the large number of patients within the dataset should increase the external validity of the findings. CONCLUSIONS: Cement augmentation treatments of patients with acute painful VCFs reliably results in highly significant benefits of pain decrease and functional improvement for this Medicare population. KEY WORDS: Vertebral compression fractures, osteoporosis, kyphoplasty, back pain, registry.

Serum dilutions as a predictive biomarker for peri-operative desensitization: An exploratory approach to transplanting sensitized heart candidates.

Antibody-mediated rejection (AMR) of cardiac allografts mediated by anti-HLA Donor Specific Antibodies (DSA) is one of the major barriers to successful transplantation for the treatment of end-stage heart failure. Therapeutic plasma exchange (TPE) is a first-line treatment for pre-transplant desensitization. However, indications for treatment regimens and treatment end-points have not been well established. In this study, we investigated how sera dilutions could guide TPE regimens for effective peri-operative desensitization and early AMR treatment. Our data show that 1:16 dilutions of EDTA-treated sera and 1.5 volume TPE reduce anti-HLA class I and class II antibody levels in the same manner and, therefore, allows to predict which antibodies would respond to peri-operative TPE. We successfully applied this approach to transplanting three highly sensitized cardiac recipients (CPRA 85-93%) with peri-operative desensitization based on a virtual crossmatch performed on 1:16 diluted serum. Furthermore, we have used sera dilutions to guide DSA treatment post-transplant. Although these findings have to be confirmed in a larger prospective study, our data suggest that serum dilutions can serve as a predictive biomarker to guide peri-operative desensitization and post-transplant immunologic management.

Validation of simple prediction algorithms to consistently achieve CD3+ and postselection CD34+ targets with leukapheresis.

BACKGROUND: Cellular therapies using engineered T cells, haploidentical transplants, and autologous gene therapy are increasing. Specified CD3+ or high CD34+ doses are typically required for subsequent manufacturing, manipulation, or CD34+ selection. Simple, practical, and reliable lymphocyte and hematopoietic progenitor cell (HPC) collection algorithms accounting for subsequent CD34+ selection have not been published. STUDY DESIGN AND METHODS: In this analysis of 15 haploidentical donors undergoing tandem lymphocyte and HPC collections, we validated one-step, practical prediction algorithms (Appendix S1, available as supporting information in the online version of this paper) that use conservative facility-specific collection efficiencies, CD34+ selection efficiency, and donor-specific peripheral counts to reliably achieve the target CD3+ and CD34+ product doses. These algorithms expand on our previously published work regarding predictive HPC collection algorithms. RESULTS: Ninety-three percent of lymphocyte and 93% of CD34+ collections achieved the final target CD3+ and CD34+ product dose when our algorithm-calculated process volumes were used. Linear regression analysis of our algorithms for CD3+, preselection CD34+, and postselection CD34+ showed statistically significant models with R2 of 0.80 (root mean square error [RMSE], 31.3), 0.72 (RMSE, 385.7), and 0.56 (RMSE, 326.0), respectively, all with p values less than 0.001. CONCLUSION: Because achievement of CD3+ or CD34+ dose targets may be critical for safety and efficacy of cell therapies, these simple, practical, and reliable prediction algorithms for lymphocyte and HPC collections should be very useful for collection facilities.

Intensive care unit providers more quickly and accurately assess risk of multiple harms using an engineered safety display.

Project Emerge took a systems engineering approach to reduce avoidable harm in the intensive care unit. We developed a socio-technology solution to aggregate and display information relevant to preventable patient harm. We compared providers' efficiency and ability to assess and assimilate data associated with patient-safety practice compliance using the existing electronic health record to Emerge, and evaluated for speed, accuracy, and the number of mouse clicks required. When compared to the standard electronic health record, clinicians were faster (529 ± 210 s vs 1132 ± 344 s), required fewer mouse clicks (42.3 ± 15.3 vs 101.3 ± 33.9), and were more accurate (24.8 ± 2.7 of 28 correct vs 21.2 ± 2.9 of 28 correct) when using Emerge. All results were statistically significant at a p-value < 0.05 using Wilcoxon signed-rank test (n = 18). Emerge has the potential to make clinicians more productive and patients safer by reducing the time and errors when obtaining information to reduce preventable harm.

Price of High-Throughput 25-Hydroxyvitamin D Immunoassays: Frequency of Inaccurate Results.

BACKGROUND: With a 10-year sustained increase in 25-hydroxyvitamin D [25(OH)D] testing, laboratories have swapped their LC-MS/MS methods for high-throughput automated immunoassays. Although it is generally well-known that immunoassays have poor recoveries for 25-hydroxyvitamin D2 [25(OH)D2], the frequency and extent to which this impacts total 25(OH)D have not been previously demonstrated. We evaluated 3 automated immunoassays against the first FDA-cleared CDC/NIST-traceable LC-MS/MS method. METHODS: Method comparison was performed for the Siemens ADVIA Centaur, Roche Elecsys Cobas, and Abbott Architect 25(OH)D immunoassay methods in real patient samples (n = 105). We calculated the mean bias in samples containing >20 ng/mL 25(OH)D2 and estimated the percent 25(OH)D2 cross-reactivities. We determined the prevalence of appreciable concentrations of 25(OH)D2 in our patient population through random sampling (n = 120) and projected the frequency of inaccurate 25(OH)D immunoassay results. RESULTS: Linear regression for 25(OH)D was y = 1.09x - 4.44 (Centaur), y = 0.84 + 0.43 (Cobas), and y = 0.83x - 0.48 (Architect). The mean biases of 25(OH)D concentrations were 5.6 (11.0) ng/mL (Centaur), -17.5 (7.2) ng/mL (Cobas), and -20.3 (9.8) ng/mL (Architect) in samples containing >20 ng/mL 25(OH)D2. The observed percent cross-reactivities for 25(OH)D2 were 115% (Centaur), 52% (Cobas), and 44% (Architect). We estimate that 8% of our population has >20 ng/mL 25(OH)D2, thereby compromising the accuracy of 25(OH)D results in >3000 samples annually. CONCLUSIONS: We demonstrate that immunoassay manufacturer package inserts indicate much better recoveries of 25(OH)D2 than what is observed in unadulterated real patient samples. We estimate the frequency of inaccurate total 25(OH)D determination by these immunoassay methods to be largely dependent on the concentration of 25(OH)D2 in each sample.

Arthroconidia in lung tissue: an unusual histopathological finding in pulmonary coccidioidomycosis.

Coccidioides immitis/posadasii presents in mycelial form with branching hyphae and arthroconidia when cultured in the laboratory. On histopathology, the presence of endospore-containing spherules is considered diagnostic of coccidioidomycosis. Here we report an unusual case of coccidioidomycosis with hyphae and arthroconidia in pulmonary tissue sections. A 49-year-old male patient with intermittently treated pulmonary coccidioidomycosis sought treatment for residual pulmonary complaints. A cavity in the left upper lobe was seen on computed tomographic scan. Due to minimal improvement of symptoms despite treatment with fluconazole, a left upper lobectomy was ultimately performed. Coccidioides mimmitis/posadasii was identified by culture and DNA probe from the lobectomy specimen. The histopathology showed a fibro-cavitary lesion, with arthroconidia and hyphal structures, but no typical endospore-forming spherules. While uncommon, C. immitis/posadasii may present with hyphae and arthroconidia on histopathology. Pathologists should be aware of this unusual presentation; culture remains the most reliable method for definitive diagnosis.

Achieving High Reliability in Histology: An Improvement Series to Reduce Errors.

OBJECTIVES: Despite sweeping medical advances in other fields, histology processes have by and large remained constant over the past 175 years. Patient label identification errors are a known liability in the laboratory and can be devastating, resulting in incorrect diagnoses and inappropriate treatment. The objective of this study was to identify vulnerable steps in the histology workflow and reduce the frequency of labeling errors (LEs). METHODS: In this 36-month study period, a numerical step key (SK) was developed to capture LEs. The two most prevalent root causes were targeted for Lean workflow redesign: manual slide printing and microtome cutting. The numbers and rates of LEs before and after interventions were compared to evaluate the effectiveness of interventions. RESULTS: Following the adoption of a barcode-enabled laboratory information system, the error rate decreased from a baseline of 1.03% (794 errors in 76,958 cases) to 0.28% (107 errors in 37,880 cases). After the implementation of an innovative ice tool box, allowing single-piece workflow for histology microtome cutting, the rate came down to 0.22% (119 errors in 54,342 cases). CONCLUSIONS: The study pointed out the importance of tracking and understanding LEs by using a simple numerical SK and quantified the effectiveness of two customized Lean interventions. Overall, a 78.64% reduction in LEs and a 35.28% reduction in time spent on rework have been observed since the study began.

Cysteine reversal of the novel neuromuscular blocking drug CW002 in dogs: pharmacodynamics, acute cardiovascular effects, and preliminary toxicology.

BACKGROUND: CW002 is a neuromuscular blocking drug that is inactivated by endogenous L-cysteine. This study determined the exogenous L-cysteine dose-response relationship for CW002 reversal along with acute cardiovascular effects and organ toxicity in dogs. METHODS: Six dogs were each studied four times during isoflurane-nitrous oxide anesthesia and recording of muscle twitch, arterial pressure, and heart rate. CW002 (0.08 mg/kg or 9 x ED95) was injected, and the time to spontaneous muscle recovery was determined. CW002 was then administered again followed 1 min later by 10, 20, 50, or 100 mg/kg L-cysteine (1 dose/experiment). After twitch recovery, CW002 was given a third time to determine whether residual L-cysteine influenced duration. Preliminary toxicology was performed in an additional group of dogs that received CW002 followed by vehicle (n = 8) or 200 mg/kg L-cysteine (n = 8). Animals were awakened and observed for 2 or 14 days before sacrificing and anatomic, biochemical, and histopathologic analyses. RESULTS: L-cysteine at all doses accelerated recovery from CW002, with both 50 and 100 mg/kg decreasing median duration from more than 70 min to less than 5 min. After reversal, duration of a subsequent CW002 dose was also decreased in a dose-dependent manner. Over the studied dose range, L-cysteine had less than 10% effect on blood pressure and heart rate. Animals receiving a single 200-mg/kg dose of L-cysteine showed no clinical, anatomic, biochemical, or histologic evidence of organ toxicity. CONCLUSION: The optimal L-cysteine dose for rapidly reversing the neuromuscular blockade produced by a large dose of CW002 in dogs is approximately 50 mg/kg, which has no concomitant hemodynamic effect. A dose of 200 mg/kg had no evident organ toxicity.

Long-term follow up after coronary sirolimus drug-eluting stent implantation for cardiac transplant arteriopathy.

There has been limited published experience with the use of sirolimus drug-eluting stents in the setting of cardiac transplant vasculopathy. Systemic sirolimus has been shown to protect against progressive transplant vasculopathy, and sirolimus-eluting stents have shown to reduce the risk of in-stent restenosis in native coronary arteries. We report a case of acute myocardial infarction in the setting of advanced transplant vasculopathy, and describe the long-term results of sirolimus drug-eluting stent implantation.