Massive Osteolysis and Pseudotumor Formation following Maestro Total Wrist Arthroplasty.

Metallosis is a known complication of arthroplasty and has been reported for the hip, knee, and shoulder joints. Metallosis pseudotumors have been linked to an increased risk of implant failure. We report a case of pseudotumor with massive bone loss following total wrist arthroplasty (TWA) using the Maestro implant. Revision to arthrodesis is possible, but issues with bone loss have to be addressed. We recommend caution in offering TWA to young patients with high functional demands.

Total Wrist Arthroplasty With a New Design, 20 Cases With 8-Year Follow-Up.

PURPOSE: Total wrist arthroplasty (TWA) is an established motion-preserving alternative to arthrodesis in the treatment of wrist arthritis, but post-TWA complications requiring additional surgery remain an issue. A new TWA design has been proposed. The purpose of this study was to report the outcome of a cohort study of 20 patients who underwent surgery using the new TWA design. METHODS: Patients were assessed before surgery and at 1, 2, and 8 years after surgery for visual analog scale (VAS) pain scores, wrist range of motion, hand grip strength, and patient-reported outcome measures (PROMs). Radiographic examination was conducted for evidence of prosthetic loosening. Reasons for revision were analyzed. RESULTS: In total, 24 reoperations were performed, including 12 revisions in 6 patients. Patient-reported outcome measures improved significantly at the 2-year follow-up compared with preoperative values. Hand grip strength, wrist extension, and VAS pain scores improved significantly at the 2-year follow-up. No radiographic loosening of the components was observed, but backing out of the carpal screws was noted in 16 of the 20 cases. CONCLUSIONS: The new TWA resulted in improved VAS pain scores, PROMs, wrist extension, and hand grip strength. The high frequency of reoperation is a concern, and modification of the implant is needed. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Clinical, Radiographic, and Patient-Perceived Outcome After Radial Hemi-Wrist Arthroplasty With a New Implant: 20 Cases With 5-Year Follow-up.

BACKGROUND: Distal component loosening is a common mode of failure in total wrist arthroplasty (TWA). A radial hemi-wrist arthroplasty (RHWA) has the potential to avoid problems related to the distal component in TWA. The aim of this study is to investigate clinical outcomes following surgical treatment with a new RHWA design. METHODS: In this pilot study of 20 consecutive RHWAs, patients were assessed preoperatively and postoperatively for range of motion, grip strength, Visual Analog Scale (VAS) pain scores, and functional scoring using Patient-Rated Wrist Evaluation (PRWE), Disabilities of the Arm, Shoulder, and Hand (DASH), and Canadian Occupational Performance Measure. Radiographs were analyzed at 12 months and 5 years (mean, 5.1 years) postoperatively. RESULTS: A total of 46 secondary surgeries were undertaken in 16 wrists, including 7 revisions. Another 6 patients are waiting for revision to radiocarpal arthrodesis. In non-revised patients, the DASH and PRWE scores improved, and wrist range of motion remained largely unchanged except for wrist flexion, which decreased. The VAS pain score during activity was reduced, and hand grip strength remained largely unchanged. CONCLUSIONS: The new implant resulted in improved functional scoring and improved VAS pain scores in non-revised patients, but many cases needed secondary surgery due to persistent pain. The high revision rate is a major concern, and further use of the implant in its current form cannot be recommended.

Dry Arthroscopy of the Wrist With a Single-use, 1.9 mm Chip-on-tip System in Wide-awake Local Anesthesia No Tourniquet.

We retrospectively reviewed our 34 first wrist dry arthroscopy cases using a single-use, 1.9 mm chip-on-tip system in wide-awake local anesthesia no tourniquet (WALANT). Thirteen patients were acute injuries; all acute patients underwent a magnetic resonance imaging (MRI) before arthroscopy. In total, 20 of 34 patients had a preoperative MRI. We use this method as a diagnostic tool in patients with wrist pain with suspected ligament tears and for the planning of treatment. We see 2 main advantages in the use of the needle chip-on-tip system: the simplicity of the procedure, and the minimal invasive character of the procedure due to the needle size that makes it possible to perform the procedure in WALANT. We find that the needle chip-on-tip arthroscopy system is a safe and cost-efficient alternative to wrist MRI with superior diagnostic ability. The procedure is minimally invasive and well suited for WALANT.

A Low-Power RRAM Memory Block for Embedded, Multi-Level Weight and Bias Storage in Artificial Neural Networks.

Pattern recognition as a computing task is very well suited for machine learning algorithms utilizing artificial neural networks (ANNs). Computing systems using ANNs usually require some sort of data storage to store the weights and bias values for the processing elements of the individual neurons. This paper introduces a memory block using resistive memory cells (RRAM) to realize this weight and bias storage in an embedded and distributed way while also offering programming and multi-level ability. By implementing power gating, overall power consumption is decreased significantly without data loss by taking advantage of the non-volatility of the RRAM technology. Due to the versatility of the peripheral circuitry, the presented memory concept can be adapted to different applications and RRAM technologies.