MACHINE LEARNING AS AN ALTERNATIVE TO 3D PHOTOMODELING EMPLOYED IN ARCHITECTURAL SURVEY AND AUTOMATIC DESIGN MODELLING

This paper presents some experiments on the use of an alternative technique, Nerf, based on artificial intelligence, which can be used in the survey of architectural structures or parts of them. The Nvidia video cards supported by the new RTX architectures are now able to manage an enormous amount of data both in the calculation of lighting and the rendering of digital shaders, and in the management of the number of polygons that can be displayed in real time in the scene. The support of artificial intelligence has further improved the three-dimensional digitization process in order to support the hardware power of algorithms that use neural networks to optimize and reduce calculation times, improving various aspects of the graphics and also of the digital representation, also influencing the representation on “image based” 3D acquisition methods, currently the most used low-cost systems in the photomodeling of objects or three-dimensional scenes. At the current state of the art, many commercial companies and research organizations, first Nvidia with its Instant Nerf, are betting on algorithms based on the Neural Radiance Field. The paper highlights the criticalities of this new system and shows the discrete results and the expandable research scenarios that can involve the impossible survey with photomodeling methodology related to works of art or architecture, due to the intrinsic nature of the materials that they compose them or because it is impossible or very difficult to photograph them

Controversy: supporting patellar resurfacing in total knee arthroplasty – do it

Patellar resurfacing during total knee arthroplasty remains a controversial topic. Some surgeons routinely resurface the patella to avoid the increased rates of postoperative anterior knee pain and reoperation for secondary resurfacing, whilst others selectively resurface based on the presence of preoperative anterior knee pain, damaged articular cartilage, inflammatory arthritis, isolated patellofemoral arthritis, and patellar subluxation and/or maltracking. A third group of surgeons never resurface the patella. The anatomy and biomechanics of the patellofemoral joint as well as the advances in surgical techniques and prosthetic design must be taken into account when making a decision about whether to resurface the patella. Accurate component implantation if the patella is resurfaced becomes crucial to avoid complications. In our institution before 2008 we were performing a selective resurfacing of the patella, but in the last decade we have decided to always resurface it, with good outcomes and low complication rate. A reproducible surgical technique may be helpful in reducing the risk of postoperative anterior knee pain and complications related to implants. In this article we analyse the current trend and controversial topics in dealing with the patella in total knee arthroplasty, and discuss the available literature in order to sustain our choice

Modular tapered conical revision stem in hip revision surgery: mid- term results

Background: The aim of this paper is to evaluate the clinical and radiological outcomes of a fluted tapered modular distal-fixation stem at medium to long-term follow-up. The hypothesis of this investigation was to verify if the use of this implant design may have provided potential advantages in femoral revisions and post-traumatic instances where the restoration of the anatomy was the prime concern. Methods: We retrospectively reviewed 62 cases of femoral revision surgeries, performed in Paprosky type IIIA and IIIB bone defects between January 2001 and December 2011 with a mean follow-up of 8.5 ± 1.5 years (range 5.1–15.9 years) where a modular fluted stem was used. The clinical assessment was performed with the Harris Hip Score (HHS), and the radiographic evaluation was carried in order to assess the stability of the femoral component. Intra-operative and postoperative complications were recorded, and the rates of complications and revisions for any cause were determined. Results: Mean HHS improved 35.4 points from the preoperative assessment. Radiographic evaluation showed a stable stem anchorage in 90.3% of the cases at the last follow-up. Five (8%) implants required additional surgery. Neither breakage of the stem nor loosening of the taper junction were recorded. Kaplan-Meier survivorship was 89.4% (CI: 88.8–90%) for any complication and 92.3% (CI: 91.8–92.7%) according to revision for any causes at 81 months follow-up. Conclusions: Our findings suggest that this stem design is a reliable option in cases of complex femoral bone defects, as well as in cases with high functional deficiencies, with promising survivorship

THE 3D SURVEY OF THE ROMAN BRIDGE OF SAN LORENZO IN PADOVA (ITALY): A COMPARISON BETWEEN SFM AND TLS METHODOLOGIES APPLIED TO THE ARCH STRUCTURE

Abstract. 3D survey methodologies are widely applied to the Cultural Heritage, employing both TLS and close-range photogrammetry with SfM techniques. Laser scanning produces models with high metric reliability and accuracy, whereas the main quality of the 3D photogrammetry is the result in term of photorealistic representation. Many studies have been conducted about the comparison and the integration of these different approaches and the aim of this paper is to contribute with a peculiar case study: the underground Roman bridge of San Lorenzo in Padova (Italy). The investigation regards the resulting point clouds of the intrados (or inner curve) of the central arch, comparing them and providing graphical and analytical outputs. The proposed workflow has the purpose to be a simple but valid tool to detect and evaluate geometrical differences, their significativity and the reliability of the 3D models.</p

Double-tapered conical taper in primary and revision surgery: rationale and short-term follow-up

Background: The new double-conical tapered stem is a novel cementless modular system, which is indicated for both primary and revision surgeries. It has been designed with different angles at the proximal (5°) and distal sections (1° 36’) in order to obtain optimal fixation by proximal and distal fit and fill of the femoral canal. Aim: The aim of this prospective study was to evaluate the short-term clinical and radiographic outcomes of primary and revision hip surgery with the new double-conical stem. Methods: 61 stems were implanted (December 2013 to September 2016) in 42 cases of primary and in 19 cases of revision surgery. The mean age of patients was 64.7 (17–94; standard deviation [SD] 21.9) years. Results: The mean body mass index of the patients was 24.6 (17–34.6). In 3 cases of developmental dysplasia of the hip we performed femoral shortening osteotomy. The mean follow-up was 26 (8–40) months. 3 patients died due to causes unrelated to surgery. Postoperative complications included 3 hip dislocations, 2 infections and 1 case of stem explant for metastatic tumour. For all other cases, at the last follow-up radiographs showed no loosening, no radiolucent lines nor subsidence. The mean Harris Hip Score significantly improved from 45 (range 35–58) preoperatively to 87 (range 75–94). Leg length discrepancy was found in 10% of cases but never >1 cm. Conclusions: Radiographic analysis showed the bone-stem contact full at 2 levels of taper. The double-tapered prosthetic stem can therefore be usefully employed both in primary and in revision surgeries

Ten-year outcomes of a nitrided Ti-6Al-4V titanium alloy fixed-bearing total knee replacement with a highly crosslinked polyethylene-bearing in patients with metal allergy

Background: Metal hypersensitivity in patients with a total knee arthroplasty (TKA) is a rare condition and a very controversial topic. Despite the lack of data concerning the real effective impact of allergy on TKA failures, most of the manufactures offer the choice of ‘non-allergenic’ implants both for primary and revision TKA, some of which provide the same designs and surgical techniques as the conventional ones. Only a few studies are available on outcomes on these ‘hypersensitivity-friendly’ implants and even fewer specifically on allergic patients with a mid- to long-term follow-up. Methods: Between 2007 and 2015, we enrolled 72 patients (57 females, 15 males), who underwent TKA treated with a non-allergenic posterior-stabilized (PS) total knee implant for a declared and proven metal allergy. Patients were followed clinically and radiographically for a mean 10 years of follow-up. Results: With revision as an endpoint the Kaplan–Meier survival estimate showed a survival rate of 97.2% at five years and 95.1% at 10 years. Significant improvements in range of motion (ROM), Knee Society Scoring (KSS) and Hospital for Special Surgery (HSS) knee scores were registered at final follow-up (P < 0.0001). At final follow-up validated Patient-Reported Outcome Measures (PROMs) showed the following scores: Oxford Knee Score (OKS) 42.1, EQ5D 0.80, EQ VAS 80.1, Forgotten Joint Score 71.2. Conclusions: This nitrided Ti-6Al-4V titanium alloy fixed-bearing total knee replacement with a highly crosslinked polyethylene-bearing showed interesting results and survival rates in patients with metal allergy at mid- to long-term follow-up

Clinical and radiographic outcomes of a trabecular titanium™ acetabular component in hip arthroplasty: results at minimum 5 years follow-up

BACKGROUND: Aim of this prospective study was to evaluate mid-term clinical and radiographic outcomes in total hip arthroplasty using an acetabular cup made of an innovative biomaterial, Trabecular Titanium™, whose highly porous structure and mechanical properties have been designed to mimic those of the natural bone, thus promoting a more physiological load transfer and a more durable fixation. METHODS: Between September 2007 and November 2009, 134 total hip replacements and eight revisions were carried out using DELTA-TT primary cups (Lima Corporate, Villanova di San Daniele del Friuli, Italy) in 133 consecutive patients. Mean age was 57.5 ± 14.7 SD (18–92) years. Diagnosis was primarily hip osteoarthritis in 85 (63 %) cases, developmental dysplasia of the hip (DDH) in 24 (18 %) and hip avascular necrosis (AVN) in 10 (7 %). All the revision procedures were due to aseptic loosening of the original implant. Approval of the Institutional Review Board of the IRCCS Policlinico San Matteo in Pavia was obtained for this study. RESULTS: Mean follow-up was 72.7 ± 7.9 SD (60–86) months. Average Harris Hip Score (HHS) significantly increased from 44.2 ± 5.4 SD (35–52) preoperatively to 95.9 ± 3.5 SD (88–100) at the last follow-up. No major post-operative complications were observed. 99.3 % of the acetabular components were radiographically stable at the last follow-up, without any radiolucent lines, sclerotic areas or periprosthetic osteolysis. Kaplan-Meier survival rate was 99.3 % at 5 years (95 % confidence interval). CONCLUSIONS: This first account on the mid-term clinical performance of the DELTA-TT cup shows primary and secondary stability, thus representing an optimal solution for patients with high demands or affected by severe hip conditions