Screws

PURPOSE: In patients with neuromuscular scoliosis undergoing posterior spinal fusion, the S2 alar iliac (S2AI) screw trajectory is a safe and effective method of lumbopelvic fixation but can lead to implant prominence. Here we use 3D CT modeling to demonstrate the anatomic feasibility of the S1 alar iliac screw (S1AI) compared to the S2AI trajectory in patients with neuromuscular scoliosis. METHODS: This retrospective study used CT scans of 14 patients with spinal deformity to create 3D spinal reconstructions and model the insertional anatomy, max length, screw diameter, and potential for implant prominence between 28 S2AI and 28 S1AI screw trajectories...

OBJECTIVES: The biomechanics in achieving molar distalization may differ between fixed appliances and clear aligners in the control of tooth movement. The objective of this study was to compare the treatment effects between clear aligners (CA) and fixed appliances (FA) in patients treated with miniscrew-assisted molar distalization. METHODS: The sample consisted of 46 subjects with mild-to-moderate crowding. A total of 22 patients treated with clear aligners (age, 25...

In this case report, a novel technique is described for an efficient, simple, and effective digital approach to immediate provisionalization of the implant-supported full-arch prosthesis. Today's patient population is increasingly educated about treatment options and expects efficient, esthetic, and comfortable results. This novel technique delivers on these aims while eliminating the many challenges posed by previously described digital and analog techniques to the immediate provisionalization of the implant- supported full-arch prosthesis...

This study presents a new approach to determining the preload force of bolted joints. The concept involves measuring the torsional angle without contact. For this purpose, we present a circular magnetic sensor array integrated into the torque wrench. The torsional angle in bolted joints depends on the dimensions of the screw and the materials used and is typically less than four degrees. For this reason, one requirement is a high angular resolution so that a continuous recording of the torsion angle is feasible during the assembly process...

Blends of polylactic acid (PLA) with amorphous polyhydroxyalkanoate (aPHA) are less brittle than neat PLA, thus enabling their use as biodegradable packaging. This work investigated the impact of recycling on the properties of neat PLA and PLA/aPHA blends with 90 and 75 wt. % PLA. After the materials were subjected to five heat histories in a single-screw extruder, the mechanical, rheological, and thermal properties were measured. All recycled compounds with 100% PLA and 75% PLA had similar decomposition behavior, whereas the decomposition temperatures for the blends with 90% PLA decreased with each additional heat cycle...

Simulation models are used to design extruders in the polymer processing industry. This eliminates the need for prototypes and reduces development time for extruders and, in particular, extrusion screws. These programs simulate, among other process parameters, the temperature and pressure curves in the extruder. At present, it is not possible to predict the resulting melt quality from these results. This paper presents a simulation model for predicting the melt quality in the extrusion process. Previous work has shown correlations between material and thermal homogeneity and the screw performance index...

Background : Although several biomechanical studies have been reported, few clinical studies have compared the efficacy of monoaxial and polyaxial pedicle screws in the surgical treatment of adolescent idiopathic scoliosis (AIS). This study aims to compare the radiological and clinical outcomes of mono- and polyaxial pedicle screws in the surgical treatment of AIS. Methods : A total of 46 AIS patients who underwent surgery to treat scoliosis using pedicle screw instrumentation (PSI) and rod derotation (RD) were divided into two groups according to the use of pedicle screws: the monoaxial group ( n = 23) and polyaxial group ( n = 23)...

Background: Aneurysmal bone cysts (ABCs) are osteolytic, non-malignant, vascular lesions of the bone. Pathological fractures can be a manifestation of the ABCs, which occur in about 8% of ABCs. Different treatments have been described in the literature, but, nowadays, an optimal management of the pathological fractures in patients with ABCs is still a matter of debate and there are no standard guidelines for treatment nor any shared indication about the best surgical intervention. The aim of our study is to review the current literature available on this matter exploring and confronting different surgical treatments for pathological fractures in ABC in order to clarify the surgical approach to these patients...

BACKGROUND: This Finite Element Analysis was conducted to analyze the biomechanical behaviors of titanium base abutments and several crown materials with respect to fatigue lifetime and stress distribution in implants and prosthetic components. METHODS: Five distinct designs of implant-supported single crowns were modeled, including a polyetheretherketone (PEEK), polymer-infiltrated ceramic network, monolithic lithium disilicate, and precrystallized and crystallized zirconia-reinforced lithium silicates supported by a titanium base abutment...

Femoral fractures are often considered lethal for adult horses because femur osteosynthesis is still a surgical challenge. For equine femur osteosynthesis, primary stability is essential, but the detailed physiological forces occurring in the hindlimb are largely unknown. The objective of this study was to create a numerical testing environment to evaluate equine femur osteosynthesis based on physiological conditions. The study was designed as a finite element analysis (FEA) of the femur using a musculoskeletal model of the loading situation in stance...

High-moisture extrusion (HME) is widely used to produce meat analogues. During HME the plant-based materials experience thermal and mechanical stresses. It is complicated to separate their effects on the final products because these effects are interrelated. In this study we hypothesize that the intensity of the thermal treatment can explain a large part of the physicochemical changes that occur during extrusion. For this reason, near-infrared (NIR) spectroscopy was used as a novel method to quantify the thermal process intensity during HME...

CASE: Two patients with osteopetrosis underwent conversion total hip arthroplasty (THA) after failure of internal fixation due to hip fractures. We experienced challenges, including difficulty of hardware removal, remaining of previous broken screws in the canal, difficulty in finding the femoral canal, and an intraoperative acetabulum fracture. Despite complications, both patients achieved satisfactory functional outcome after surgery at the latest follow-up. CONCLUSION: Our cases showed that previous hip fracture and failed internal fixation make conversion THA more complex and unpredictable in patients with osteopetrosis...

OBJECTIVE: To investigate the prosthetic parameters, clinical indices, crestal bone levels, and inflammatory biomarkers in peri-implant crevicular fluid as influenced by two different implant restorative materials i.e., metal ceramic and monolithic zirconia at baseline, 1 Year and 2 Years. MATERIALS AND METHODS: Twenty patients with bilateral implants placed in the same arch were selected. Monolithic zirconia (4Y-PSZ) crown was placed on one side whereas a metal ceramic (M C) crown was inserted on the contralateral side after randomization...

While the usual etiology of slipped capital femoral epiphysis (SCFE) is idiopathic, there are many other factors that increase the predisposition to slippage. Chemotherapy can be one of them. In this article, we report a rare case of acute SCFE after tumor prosthesis implantation in a patient who received chemotherapy. A 10-year-old girl with osteosarcoma of the right distal femur underwent (neo-) adjuvant chemotherapy, wide tumor resection, and reconstruction using a growing tumor prosthesis and a short non-cemented femoral stem...

OBJECTIVES: This study aimed to compare the accuracy of implant-level conventional and digital impressions for atrophied maxillary ridges. MATERIALS AND METHODS: Twelve participants with atrophied edentulous maxillary ridges received six implants. Six months later and after soft tissue maturation around healing abutments, a control cast was constructed using the final passive restoration for each patient. Two types of implant-level impression techniques were carried out for each patient: (1) conventional (splinted open-tray) impression technique and (2) digital impression technique...

The diagnosis of a traumatic unstable pelvis in a stable patient is a temporary concept depending on when we see the patient, as all patients presenting with hemorrhagic shock have hemodynamic stability until they become unstable. As a rule, the more unstable the pelvic fracture is, the higher the risk of bleeding and hemodynamic instability it has. Therefore, in unstable pelvic fractures, hemodynamic stability should be a diagnosis by exclusion. For bleeding detection in stable patients, an immediate one-stage contrast-enhanced CT scan is the appropriate diagnosis test; however, since CT scan radiation is always an issue, X-rays should be considered in those cases of hemodynamically stable patients in whom there is a reasonable suspicion that no unsafe bleeding is going on...

AIM: The aim of the present retrospective case series was to longitudinally assess soft tissue volume changes on the vestibular aspect of implants in relation to keratinized mucosa thickness (KMT) and width (KMW) after the application of the microsurgical envelope technique combined with a connective tissue graft (CTG). MATERIALS AND METHODS: A total of 12 healthy patients received 12 dental implants placed either in the posterior maxilla or mandible. The study involved the harvesting of 12 CTGs with a minimally invasive single-incision technique, grafted to the vestibular peri-implant soft tissue utilizing the envelope technique, followed by the insertion of 12 screw-retained IPS e...

The accurate fenestration, screw implantation and assisting stabilizing-plate placement in surgery of benign tumors in the proximal femur needs be defined easily. The aim of this study was to investigate the value of 3D printed multifunctional guides plate (3D-MGP) based on computer aided design. Between January 2020 and June 2022, 17 patients (nine females and eight males) with benign proximal femoral tumor had lesion curettage and allograft combined with internal plate fixation using 3D-MGP. In this study, the patients had CT scans and a technician reconstructed the 3D images of tumor and the femur, a doctor designed the location and margin of the fenestration and screws, and integrated different functions into MGP for benign proximal femoral lesions, which assisted in precise localization, fenestration and screw drilling...

Background: Bennett fractures are traditionally fixed with percutaneous K-wires from dorsal to volar, or with a volar to dorsal screw via a volar open approach. While volar to dorsal screw fixation is biomechanically advantageous, an open approach requires extensive soft tissue dissection, thus increasing morbidity. This study aims to investigate the practicality and safety of Bennett fracture fixation using a percutaneous, volar to dorsal screw, particularly with regard to the median nerve and its motor branch during wire and screw insertion...

Background: Intramedullary screws (IMS) have become a viable option for metacarpal fracture fixation. To further appraise their utility, this study assessed clinical and patient-reported short- and medium-term outcomes of IMS fixation for extra-articular metacarpal fractures. Methods: A retrospective cohort study was performed in a series of 32 patients (with a total of 37 fractures) who underwent metacarpal fracture fixation over a 42-month period between January 2020 and July 2023. Results: Mean time for return to work was 39...