Effetti termici nella metrologia a coordinate

La norma UNI EN ISO 10360-2:2010 prescrive: “I limiti per le condizioni ambientali ammesse che possono avere influenza sulle misurazioni, quali condizioni di temperatura, umidità dell’aria e vibrazione nel luogo di installazione, devono essere specificati: - dal fabbricante, nel caso di prove di accettazione; - dall’utilizzatore, nel caso di prove di riverifica periodica. In entrambi i casi, l'utilizzatore è libero di scegliere le condizioni ambientali nelle quali saranno eseguite le prove secondo la ISO 10360-2, all'interno dei limiti specificati.” La presente Guida si prefigge l’obiettivo di rendere disponibile all’utilizzatore di Macchine di Misura a Coordinate (di seguito CMM) una serie di indicazioni e informazioni relative principalmente alla grandezza di influenza temperatura ed ai suoi effetti nelle misurazioni dimensionali. Affinché si possano ottenere le prestazioni dichiarate sui cataloghi, il costruttore di CMM dichiara, insieme alle specifiche tecniche della macchina, anche alcuni parametri ambientali che ritiene debbano essere mantenuti entro i limiti specificati.Ci si trova quindi subito di fronte al dilemma: • Si è in grado di rispettare le condizioni ambientali prescritte? • oppure si può soprassedere ed accontentarsi di prestazioni finali diverse? E quali saranno queste nuove prestazioni? Alle prime domande ne seguono altre: • serve ottenere dalla macchina il massimo delle prestazioni dichiarate dal Costruttore oppure ci si può accontentare di qualcosa in meno? • Tutte le volte che si effettuano misurazioni si è in grado di ricondurre i risultati delle misurazioni alla temperatura di riferimento? Nel prossimo paragrafo vengono proposte alcune problematiche che sono frequentemente oggetto di domande da parte degli utilizzatori di CMM e alle quali la presente guida propone delle risposte, frutto di analisi ed esperienze maturate da coloro che hanno redatto articoli nelle riviste di settore. Il capitolo 2 indica quali sono i riferimenti per terminologia e definizioni. I capitoli 3, 4, 5, 6, 7 e 8 sono il corpo centrale della guida e descrivono il fenomeno temperatura da un punto di vista fisico. Il capitolo 9 presenta invece un'ampia bibliografia comprendendo nel contempo termini di riferimenti normativi, nonché articoli scritti da esperti del settore in vari ambiti: tutto ciò allo scopo di fornire materiale utile sia per un approfondimento dei temi trattati nella stessa guida, sia per supportare (grazie soprattutto alle esperienze già maturate e descritte nei vari articoli) coloro i quali si trovassero ad affrontare per la prima volta simili tematiche

Fractional order hereditariness of knee human ligament and tendon

Anterior Cruciate Ligament (ACL) is one of the four major ligaments in the knee, playing a critical role in stabilizing the joint. ACL is highly susceptible to injury, overall during sport activities, often precipitating catastrophic long-term joint outcomes. The ideal replacement graft for a torn ACL would restore native anatomy and function to the knee. Most commonly used autograft and allograft, including patellar tendon (P) and hamstring tendon (H) graft, or bioengineered synthetic grafts, may substantially alter the biomechanics of the knee, permitting a return to only moderate physical activities [1]. Main issues are the sub-optimal graft properties [2] and a still incomplete biomechanics characterization [1]. The goal of the present work is to fully characterize and compare the viscoelastic behavior of the ACL and natural/artificial grafts in order to highlight the differences that should be overcome to achieve a successful biomechanical performance and an ideal graft design

Orthobiologic therapies delay the need for hip arthroplasty in patients with avascular necrosis of the femoral head: A systematic review and survival analysis

Purpose: The aim of this systematic review and survival analysis was to quantify the benefits of orthobiologic augmentation therapies for the treatment of avascular necrosis (AVN) of the femoral head and identify the most effective approach to delay the need for total hip arthroplasty (THA). Methods: A systematic review of the literature was performed on PubMed, Scopus, and Cochrane on clinical studies on orthobiologic therapies used alone or as an augmentation to core decompression or other procedures to address hip AVN. A qualitative analysis of the different biological therapies applied was performed. Afterward, the results of these procedures were quantitatively analysed to document their survivorship from THA compared to treatment groups without orthobiologics. Kaplan–Meier analysis was performed for all studies and then by categorising orthobiologics into treatment subgroups. Results: A total of 106 studies were included (4505 patients). Different orthobiologic approaches have been evaluated: cell-based therapies including bone marrow aspirate concentrate (BMAC) and bone marrow mesenchymal stromal cells (BM-MSCs), platelet-rich plasma (PRP), or other bioactive molecules applied in the osteonecrotic area or as intra-arterial injections. The survival analysis at 120 months documented a higher (p < 0.0005) cumulative survivorship with orthobiologics (69.4%) compared to controls (48.5%). The superiority was shown specifically for BMAC (p < 0.0005), BM-MSCs (p < 0.0005), intra-arterial (p < 0.0005) and PRP (p = 0.011) approaches, but the direct comparison of these approaches with their controls confirmed benefits only for BMAC (p < 0.0005). Conclusion: This systematic review and survival analysis demonstrated that orthobiologics have the potential to improve survivorship in patients affected by hip AVN. In particular, the specific analysis of different orthobiologic products supported relevant benefits for BMAC augmentation in terms of survival from the need for THA, while no clear benefits were confirmed for other orthobiologics. Level of Evidence: Level III

Tricalcium Phosphate as a Bone Substitute to Treat Massive Acetabular Bone Defects in Hip Revision Surgery: A Systematic Review and Initial Clinical Experience with 11 Cases

The use of tricalcium phosphate (TCP) as a bone substitute is gaining increasing interest to treat severe acetabular bone defects in revision total hip arthroplasty (rTHA). The aim of this study was to investigate the evidence regarding the efficacy of this material. A systematic review of the literature was performed according to the PRISMA and Cochrane guidelines. The study quality was assessed using the modified Coleman Methodology Score (mCMS) for all studies. A total of eight clinical studies (230 patients) were identified: six on TCP used as biphasic ceramics composed of TCP and hydroxyapatite (HA), and two as pure-phase ceramics consisting of TCP. The literature analysis showed eight retrospective case series, of which only two were comparative studies. The mCMS showed an overall poor methodology (mean score 39.5). While the number of studies and their methodology are still limited, the available evidence suggests safety and overall promising results. A total of 11 cases that underwent rTHA with a pure-phase ceramic presented satisfactory clinical and radiological outcomes at initial short-term follow-up. Further studies at long-term follow-up, involving a larger number of patients, are needed before drawing more definitive conclusions on the potential of TCP for the treatment of patients who undergo rTHA

The effect of autologous adipose derived mesenchymal stem cell therapy on juvenile osteochondritis dissecans of the patella: a case study

A prospective analysis of the effect of autologous adipose derived mesenchymal stem cell (AD-MSCs) therapy in the treatment of a juvenile osteochondritis dissecans (JOCD) of the patella. After failed conventional management of JOCD, a 13-year-old patient undergoes intra-articular MSC therapy. Repeated magnetic resonance imaging analyses showed regeneration of cartilage. In this report, the use of AD-MSCs, after unsuccessful conventional JOCD management, resulted in structural, functional and pain improvement. These results highlight the possibility to avoid surgery treatment in JOCD patella treatment

Anatomic and histological study of the anterolateral aspect of the knee: a SANTI Group investigation

Background: The structure and function of the anterolateral aspect of the knee have been significantly debated, with renewed interest in this topic since the description of the anterolateral ligament (ALL). Purpose: To define and describe the distinct structures of the lateral knee and to correlate the macroscopic and histologic anatomic features. Study Design: Descriptive laboratory study. Methods: Twelve fresh-frozen human cadavers were used for anatomic analysis. In the left knee, a layer-by-layer dissection and macroscopic analysis were performed. In the right knee, an en bloc specimen was obtained encompassing an area from the Gerdy tubercle to the posterior fibular head and extending proximally from the anterior aspect to the posterior aspect of the lateral femoral epicondyle. The en bloc resection was then frozen, sliced at the level of the joint line, and reviewed by a musculoskeletal pathologist. Results: Macroscopically, the lateral knee has 4 main layers overlying the capsule of the knee: the aponeurotic layer, the superficial layer including the iliotibial band (ITB), the deep fascial layer, and the ALL. Histologically, 8 of 12 specimens demonstrated 4 consistent, distinct structures: the ITB, the ALL, the lateral collateral ligament, and the meniscus. Conclusion: The lateral knee has a complex orientation of layers and fibers. The ALL is a distinct structure from the ITB and is synonymous to the previously described capsulo-osseous layer of the ITB. Clinical Relevance: Increasingly, lateral extra-articular procedures are performed at the time of anterior cruciate ligament reconstruction. Understanding the anatomic features of the anterolateral aspect of the knee is necessary to understand the biomechanics and function of the structures present and allows surgeons to attempt to replicate those anatomic characteristics when performing extra-articular reconstruction

Will the Kaplan Fiber Complex Be the ''New Anterolateral Ligament''? Insights from Direct Surgical Exploration in the Context of ACL Injury and Reconstruction

According to the most popular scientific literature database in 2022, nearly 20 papers mentioning the "Kaplan Fiber" complex have been published in the last 2 years, highlighting the role of this anatomical structure in the context of anterior cruciate ligament tear [...]

Assessment of rotatory laxity in anterior cruciate ligament-deficient knees using magnetic resonance imaging with Porto-knee testing device

Purpose Objective evaluation of both antero-posterior translation and rotatory laxity of the knee remains a target to be accomplished. This is true for both preoperative planning and postoperative assessment of different ACL reconstruction emerging techniques. The ideal measurement tool should be simple, accurate and reproducible, while enabling to assess both ‘‘anatomy’’ and ‘‘function’’ during the same examination. The purpose of this study is to evaluate the clinical effectiveness of a new in-housedeveloped testing device, the so-called Porto-knee testing device (PKTD). The PKTD is aimed to be used on the evaluation of both antero-posterior and rotatory laxity of the knee during MRI exams. Methods Between 2008 and 2010, 33 patients with ACLdeficient knees were enrolled for the purpose of this study. All patients were evaluated in the office and under anesthesia with Lachman test, lateral pivot-shift test and anterior drawer test. All cases were studied preoperatively with KT-1000 and MRI with PKTD, and examinations performed by independent observers blinded for clinical evaluation. During MRI, we have used a PKTD that applies antero-posterior translation and permits free tibial rotation through a standardized pressure (46.7 kPa) in the proximal posterior region of the leg. Measurements were taken for both knees and comparing side-to-side. Five patients with partial ruptures were excluded from the group of 33. Results For the 28 remaining patients, 3 women and 25 men, with mean age of 33.4 ± 9.4 years, 13 left and 15 right knees were tested. No significant correlation was noticed for Lachman test and PKTD results (n.s.). Pivot-shift had a strong positive correlation with the difference in anterior translation registered in lateral and medial tibia plateaus of injured knees (cor. coefficient = 0.80; p\0.05), and with the difference in this parameter as compared to side-to-side (cor. coefficient = 0.83; p\0.05). Considering the KT-1000 difference between injured and healthy knees, a very strong positive correlation was found for side-to-side difference in medial (cor. coeffi- cient = 0.73; p\0.05) and lateral (cor. coefficient = 0.5; p\0.05) tibial plateau displacement using PKTD. Conclusion The PKTD proved to be a reliable tool in assessment of antero-posterior translation (comparing with KT-1000) and rotatory laxity (compared with lateral pivotshift under anesthesia) of the ACL-deficient knee during MRI examinatio