A new retroreflector named "quatriplan" based on the corner-cube principle, for advanced ultrasonic telemetry applications.

Telemetry consists in remotely detecting and locating an object. For applications in immersed structures as in nuclear primary vessel, ultrasonic waves are well adapted. Moreover, fixing a target on the structures of interest maximizes the signal-to-noise ratio and provides a reference point. Classical Corner-Cube Retroreflector (CCR) demonstrated high performance in this framework (1D and 2D measurements) but does not allow knowing the full (3D) positioning of the structure. This paper proposes an innovative compact target named "quatriplan", based on the CCR principle, and which must allow the ability to determine the orientation of the target in addition to its distance to the transducer. The simple design of the quatriplan is first explained, then its performances are investigated with modelling and experimentations. The results highlight its strong performance and benefit for advanced telemetry applications in industrial systems where complex design can impede easy and efficient access for inspection of specific parts.

Acoustical properties of an immersed corner-cube retroreflector alone and behind screen for ultrasonic telemetry applications.

Ultrasonic telemetry measurements consist in remotely detecting and locating an object. To maximize the signal-to-noise ratio, a target may be used, positioned at a reference point. In this framework, the ultrasonic reflective characteristics of a corner-cube retroreflector (CCR) are investigated. The most interesting property of a CCR is its ability to fully reverse an incoming wave in the same direction under certain conditions. Theoretical developments are performed in order to understand its acoustic behaviour, and experimentations are made in various configurations: CCR alone in water, and behind an immersed plate that acts as a screen, with normal and non-normal incidence. The results highlight its strong performance. Moreover, the study of two other couples of CCR material and surrounding fluid underlines the relevance of considering the acoustic properties of each medium, as they have a strong influence on the acoustic response of the CCR.

2D Ultrasonic Antenna System for Imaging in Liquid Sodium.

Ultrasonic techniques are developed at CEA (French Alternative Energies and Nuclear Energy Commission) for in-service inspection of sodium-cooled reactors (SFRs). Among them, an ultrasound imaging system made up of two orthogonal antennas and originally based on an underwater imaging system is studied for long-distance vision in the liquid sodium of the reactor's primary circuit. After a description of the imaging principle of this system, some results of a simulation study performed with the software CIVA in order to optimize the antenna parameters are presented. Then, experimental measurements carried out in a water tank illustrate the system capabilities. Finally, the limitations of the imaging performances and the ongoing search of solutions to address them are discussed.

Design of a Phased Array EMAT for Inspection Applications in Liquid Sodium.

This article describes the development of a French CEA in-house phased array Electro Magnetic Acoustic Transducer (EMAT) adapted to hot and opaque sodium environment for in-service inspection of Sodium Fast Reactors. The work presented herein aimed at improving in-service inspection techniques for the ASTRID reactor project. The design process of the phased array EMAT is explained and followed by a review of laboratory experimental test results.

Ultrasonic Transducer for Non-Destructive Testing of Structures Immersed in Liquid Sodium at 200 °C.

TUCSS transducer (French acronym standing for Transducteur Ultrasonore pour CND Sous Sodium) is designed for performing NDT (Non-Destructive Testing) under liquid sodium. Under sodium, the tests results obtained show that these transducers have sufficiently good acoustic properties to perform basic NDT of a structure immersed under liquid sodium at about 200 °C using conventional immersion ultrasonic technics. Artificial defects were made next to an X-shaped weld and could clearly be detected.

Multi-modal leaky Lamb waves in two parallel and immersed plates: Theoretical considerations, simulations, and measurements.

Leaky Lamb waves have the potential to be used to perform non-destructive testing on a set of several parallel and immersed plates. Short-time Fourier transform and two-dimensional Fourier transform have both been successfully used to measure the propagation properties: phase and group velocity, and leaky attenuation. Experimental measurements were validated by comparison between theory, experimentation and finite-element simulations (using comsol multiphysics® software) in the case of one immersed plate in water. These signal processing techniques proved to be efficient in the case of multi-modal propagation. They were applied to two immersed plates to identify the leaky Lamb mode generated in the second plate. Dispersion curves of the system composed by two immersed and parallel plates are computed. When plates have the same thickness, leaky Lamb modes propagate from the first to the second plate without any mode change, with the apparent attenuation being weaker in the second plate. Considering that the second plate is continuously supplied in energy by the first one, an energy-based model is proposed herein to estimate the apparent attenuation in the second plate. Despite our extremely simplifying assumption, this model proved to be in good agreement with both finite-element modelling and experimentation.

Weld inspection by focused adjoint method.

This paper reports a methodology for the non-destructive ultrasonic evaluation of welds, based on probing, residue back-focusing and topological energy calculation using an enhanced (focused) adjoint method. The proposed method combines the advantages of time reversal to compensate for the cumulative distorsions experienced by a wave propagating in a heterogeneous medium, and topological imaging to highlight the defect location. The synergistic effect of this combined approach makes it possible to detect anomalies in the most efficient way. The method paves the way towards a matched-insonification imaging of anomalies in anisotropic media.

Topological imaging in bounded elastic media.

Detecting, imaging and sizing defects in a bounded elastic medium is still a difficult task, especially when access is complex. Adjoint methods simplify the task as they take advantage of prior information such as the geometry and material properties. However, they still reveal a number of important limitations. Artifacts observed on the conventional topological energy image result from wave interactions with the boundaries of the inspected medium. The paper describes a method for addressing these artifacts, which involves forward and adjoint fields specified in terms of the boundary conditions. Modified topological energies are then defined according to the type of analyzed flaw (open slit or inclusion). Comparison of the numerical results with the experimental data confirms the relevance of the approach.

Total hip arthroplasty after periacetabular osteotomy.

Patients with hip dysplasia often endure multiple surgical interventions, first in attempts to preserve their biologic hips and later for total hip arthroplasty (THA). Each different surgical approach traumatizes the musculoligamentous complex of the hip. These cumulative insults can significantly affect THA success. We retrospectively reviewed 8 patients who underwent THA after previous periacetabular osteotomy via the same anterior approach. Acetabular bone stock required no augmentation for implant coverage. No complication occurred during surgery. All patients increased their functional score at last follow-up. No dislocation or implant loosening occurred. Leg-length restoration was excellent. Periacetabular osteotomy is a proven conservative procedure in dysplastic hips that can be realized through a Smith-Petersen incision. Restoration of the acetabular anatomy is achieved with limited muscle detachment. Good results have been achieved with periacetabular osteotomy; however, some patients develop increasing pain from progression of osteoarthritis and require a THA to allow relief of symptoms. The anterior-approach THA is a well-established procedure using the same Smith-Petersen interval as periacetabular osteotomy. Using this approach for both procedures optimizes the patient's immediate and ultimate functional recovery and hip stability. Instead of compromising subsequent THA, periacetabular osteotomy may improve THA results in dysplastic hips.

Minimum 10-year survival of Kerboull cemented stems according to surface finish.

UNLABELLED: The optimal surface finish for a cemented THA stem is still debated. We hypothesized surface finish would influence survival of Kerboull cemented hip arthroplasties and a matte finish would have lower survival. We reviewed survival of 433 total hip arthroplasties in 395 patients: 284 consecutive patients (310 hips) were enrolled in a prospective, randomized study of polished (165 hips) or matte finish stems (145 hips) and compared to a historical series of satin stems (123 hips) in 111 patients. The satin and matte finish implants had similar geometry but the polished was quadrangular rather than oval. Finish roughnesses were: polished (radius, 0.04 microm), satin (radius, 0.9 microm), and matte (radius, 1.7 microm). The mean age of the patients at the time of the index arthroplasty was 63.6 years. The survival rate at 13 years, using radiographic loosening as the end point, was 97.3%+/-2.6% for polished stems, 97.1%+/-2.1% for satin stems, and 78.9%+/-5.8% for matte stems. The data suggest survival of Kerboull stems was higher with a polished or satin surface finish than with a matte finish. LEVEL OF EVIDENCE: Level II, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Isolated arthroscopic biceps tenotomy or tenodesis improves symptoms in patients with massive irreparable rotator cuff tears.

BACKGROUND: Lesions of the long head of the biceps tendon are often associated with massive rotator cuff tears and may be responsible for shoulder pain and dysfunction. The purpose of this study was to evaluate the clinical and radiographic outcomes of isolated arthroscopic biceps tenotomy or tenodesis as treatment for persistent shoulder pain and dysfunction due to an irreparable rotator cuff tear associated with a biceps lesion. METHODS: We conducted a retrospective study of sixty-eight consecutive patients (mean age [and standard deviation], 68 +/- 6 years) in whom a total of seventy-two irreparable rotator cuff tears had been treated arthroscopically with biceps tenotomy or tenodesis. A simple tenotomy was performed in thirty-nine cases, and a tenodesis was performed in thirty-three. No associated acromioplasty was performed. All patients were evaluated clinically and radiographically by an independent observer at a mean of thirty-five months postoperatively. RESULTS: Fifty-three patients (78%) were satisfied with the result. The mean Constant score improved from 46.3 +/- 11.9 points preoperatively to 66.5 +/- 16.3 points postoperatively (p < 0.001). A healthy-appearing teres minor on preoperative imaging was associated with significantly increased postoperative external rotation (40.4 degrees +/- 19.8 degrees compared with 18.1 degrees +/- 18.4 degrees ) and a significantly higher Constant score (p < 0.05 for both) compared with the values for the patients with an absent or atrophic teres minor preoperatively. Three patients with pseudoparalysis of the shoulder did not benefit from the procedure and did not regain active elevation above the horizontal level. In contrast, the fifteen patients with painful loss of active elevation recovered active elevation. The acromiohumeral distance decreased 1.1 +/- 1.9 mm on the average, and glenohumeral osteoarthritis developed in only one patient. The results did not differ between the tenotomy and tenodesis groups (mean Constant score, 61.2 +/- 18 points and 72.8 +/- 12 points, respectively). The "Popeye" sign was clinically apparent in twenty-four (62%) of the shoulders that had been treated with a tenotomy; of the sixteen patients who noticed it, none were bothered by it. CONCLUSIONS: Both arthroscopic biceps tenotomy and arthroscopic biceps tenodesis can effectively treat severe pain or dysfunction caused by an irreparable rotator cuff tear associated with a biceps lesion. Shoulder function is significantly inferior if the teres minor is atrophic or absent. Pseudoparalysis of the shoulder and severe rotator cuff arthropathy are contraindications to this procedure. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.