Lateral unicompartmental knee arthroplasty (UKA) showed a lower risk of failure compared to medial unicompartmental knee arthroplasty in the Register of Prosthetic Orthopedic Implants (RIPO)

INTRODUCTION

The present study aimed to investigate differences in survivorship between medial and lateral unicompartmental knee arthroplasty (UKA) by analyzing the data of an Italian regional registry. The hypothesis was that, according to recent literature, lateral implants have comparable survivorship with regard to the medial implants.

MATERIALS AND METHODS

The Register of Orthopaedic Prosthetic Implants (RIPO) of Emilia-Romagna (Italy) database was searched for all UKAs between July 1, 2000, and December 31, 2019. For both cohorts, subject demographics and reasons for revision were presented as a percentage of the total cohort. Kaplan-Meier survivorship analysis was performed using revision of any component as the endpoint and survival times of unrevised UKAs taken as the last observation date (December 31, 2019, or date of death).

RESULTS

Patients living outside the region and symmetrical implants (which do not allow the compartment operated to be traced) were excluded. 5571 UKAs implanted on 5172 patients (5215 medial UKAs and 356 lateral UKAs) were included in the study. The survivorship analysis revealed 13 failures out of 356 lateral UKAs (3.7%) at a mean follow-up of 6.3 years and 495 failures out of 5215 medial UKAs (9.5%) at a mean follow-up of 6.7 years. The medial UKAs had a significantly higher risk of failure, with a Hazard Ratio of 2.6 (CI 95% 1.6-4.8; p < 0.001), adjusted for age, gender, weight, and mobility of the insert. Both the groups revealed a good survival rate, with 95.2% of lateral implants and 87.5% of medial implants still in situ at 10 years of follow-up.

CONCLUSIONS

Lateral UKA is a safe procedure showing longer survivorship than medial UKAs (95.2% and 87.5% at 10 years, respectively) in the present study.

LEVEL OF EVIDENCE

Level 3, therapeutic study.

Modes of failure with fractional flow reserve guidewires: Insights from the manufacturer and user facility device experience database

BACKGROUND

Fractional flow reserve (FFR) measurement is commonly used in the cardiac catheterization laboratory to assess the functional significance of coronary arterial plaques. Robust real-world data on complications and modes of failure of FFR guidewires are limited.

AIM

To characterize these outcomes by analyzing the post-marketing surveillance data from the United States Food and Drug Administration Manufacturer and User Facility Device Experience (MAUDE) database for commonly used FFR guidewires.

METHODS

The MAUDE database was queried from January 2010 through April 2020 for 3 FFR guidewires [PressureWire^TM X (Abbott), Comet^TM (Boston Scientific), and Verrata^TM (Philips)] by searching for the following events: “Injury”, “malfunction”, “death”, and “other”. This yielded 544 reports. After excluding incomplete reports, 486 reports were analyzed.

RESULTS

Guidewire tip fracture was the most commonly reported mode of failure, in 174 (35.8%) cases followed by guidewire kinking (n = 152, 31.3%), communication failure (n = 141, 29.0%), and shaft fracture (n = 67, 13.8%). In total, 133 (27.4%) device failures resulted in patient adverse events. The most common adverse event was retained guidewire tip, in 71 (53.4%) cases, followed by freshly deployed stent dislodgment (n = 26, 19.6%) and coronary artery dissection (n = 23, 17.3%). Seven deaths were reported.

CONCLUSION

FFR guidewire failures can occur because of various mechanisms and cause patient adverse events. The MAUDE database serves as an important platform for improved collaboration among clinicians, device manufacturers, and regulators to improve device performance and optimize patient outcomes. Our analysis provides mechanistic insights of FFR guidewire failure and associated adverse events but cannot verify causality or provide a comparison among different guidewires.

Unicompartmental knee arthroplasty has higher revisions than total knee arthroplasty at long term follow-up: a registry study on 6453 prostheses

PURPOSE

The purpose of this study is to analyse long-term unicompartmental knee arthroplasty (UKA) focusing on survivorship, causes of failure and revision strategy.

METHODS

This study is a retrospective analysis of data from a regional arthroplasty registry for cases performed between 2000 and 2017. A total of 6453 UKAs were identified and the following information was analysed: demographic data, diagnosis leading to primary implant, survivorship, complication rate, causes of failure, revision strategies. UKA registry data were compared with total knee arthroplasty (TKA) registry data of 54,012 prostheses, which were implanted in the same time period.

RESULTS

6453 UKAs were included in the study: the vast majority of them (84.4%) were implanted due to primary osteoarthritis followed by deformity (7.1%) and necrosis of the condyle (5.1%). When compared to TKA, UKA showed lower perioperative complication rate (0.3% compared to 0.6%) but higher revision rate (18.2% at 15 years, compared to 6.2% for TKA). No correlation was found between diagnosis leading to primary implant and prosthesis survival. The most frequent cause of failure was total aseptic loosening (37.4%), followed by pain without loosening (19.8%). Of the 620 UKAs requiring revision, 485 were revised with a TKA and 61 of them required a re-revision; on the other hand, of the 35 cases where another UKA was implanted, 16 required a re-revision.

CONCLUSION

UKA is associated with fewer perioperative complications but higher revision rates when compared to TKA. Its survivorship is not affected by the diagnosis leading to primary implant. Revision surgery of a failed UKA should be performed implanting a TKA, which is associated with a lower re-revision rate when compared to another UKA.

LEVEL OF EVIDENCE

Level 3, therapeutic study.

Lithium di silicate ceramic surface treated with Er,Cr:YSGG and other conditioning regimes bonded to orthodontic bracket

Aim

To assess bond integrity and modes of failure of metallic brackets to lithium disilicate ceramics (LDC) conditioned with Er,Cr:YSGG laser (ECL).

Material and methods

Sixty LDC were arbitrarily allocated into six groups (n = 15) according to the type of ceramic surface conditioning treatment. Group 1 surface treated with silane (S) only, group 2 surface etched with hydrofluoric acid (HF)+ S, group 3 surface conditioned with HF+ ultrasonic bath (UB)+ S, group 4 sand blasting (SB) of glass ceramic surface with 50 µm Al₂O₃, group 5 surface conditioned with self-etch ceramic primer (SECP) and in group 6 surface treated with ECL + S. After conditioning, the specimens were positioned in a universal testing device for shear bond strength (SBS) testing. Adhesive Remnant Index (ARI) was used to determine sites of bond failure. Among experimental groups analysis of variance (ANOVA) and Tukey multiple comparison test was used at a significance level of (p < 0.05).

Results

The highest SBS values were observed in group 3 HF+ UB + S (18.21 ± 1.241) and the lowest SBS values were displayed group 1 surface treated with S only (5.21 ± 0.23). Specimens surface conditioned in group 2 with HF+ S (17.85 ± 1.25), group 3 HF+ UB + S (18.21 ± 1.241) and group 6 ECL + S (17.09 ± 1.114) unveiled comparable SBS values (p > 0.05).

Conclusion

LDC conditioned with ECL at (4.5 W and 30 Hz) has a potential to be used in clinical settings alternate to HF acid.

Multimodal method for landslide risk analysis

Quantitative landslide risk analysis is a key step in creating appropriate land use policies. However, regional scale landslide hazard and risk studies are traditionally based on a single, infinite-slope style of failure, belying the differing consequences of a diverse range of failure modes. In this paper we expand an existing multimodal coseismic landslide hazard model to create a method for multimodal, multi-trigger quantitative landslide risk analysis and apply it to the country of Lebanon.

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Physics-based, mode-specific models for coseismic and precipitation-induced landslides capture the effects of multiple failure types and triggering scenarios.

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A new model for analyzing slope stability against rotational failures allows for efficient, regional scale assessments.

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Open-source mapping of built-up area is used to identify elements at risk.

Effects of misalignment on static torsional strength of anterior cervical plate systems

BACKGROUND CONTEXT

There is little understanding of cervical plate misalignment as a risk factor for plate failure at the plate-screw-bone interface.

PURPOSE

To assess the torsional strength and mode of failure of cervical plates misaligned relative to the midsagittal vertical axis.

STUDY DESIGN

Plastic and foam model spine segments were tested using static compression and torsion to assess effects of misaligned and various lengths anterior cervical plate (ACPs).

METHODS

Different length ACPs and cancellous fixed angle screws underwent axial torsional testing on a servo-hydraulic test frame at a rate of 0.5°/s. A construct consisted of one ACP, four screws, one ultrahigh-molecular weight polyethylene inferior block, and one polyurethane foam superior block. Group 1 had ACPs aligned in the midsagittal vertical axis, group 2 plates were positioned 20° offset from the midline, and group 3 had the ACP shifted 5 mm away and 20° offset from midline. Torques versus angle data were recorded. The failure criterion was the first sign of pullout determined visually and graphically.

RESULTS

Group 1 had a more direct screw pullout during failure. For the misaligned plates, failure was a combination of the screws elongating the holes and shear forces acting between the plate and block. The misaligned plates needed more torque to failure. The failure torque was 50% reduced for the longer versus the shorter plates in the neutral position. Graphically shown initial screw slippage inside the block preceded visual identification of slippage in some cases.

CONCLUSIONS

We observed different failure mechanisms for neutral versus misaligned plates. Clinically, misalignment may have the benefit of needing more torque to fail. Misalignment was a risk factor for failure of the screw-bone interface, especially in longer plate constructs. These comparisons of angulations may be a solid platform for expansion toward a more applicable in vivo model.