Cylindrical specimens of bone measuring 15 mm in diameter were obtained from the lateral cortical layer of 10 pairs of femurs and tibias. A central hole 3.2 mm in diameter was drilled in each specimen. The hole was tapped, and a 4.5 mm cortical bone screw was inserted from the outer surface. The montage was submitted to push-out testing up to a complete strip of the bone threads. The cortical t...

PURPOSE To compare the treatment outcome of Acutrak versus Herbert screw fixation for scaphoid non-union and delayed union. METHODS Records of 132 patients who underwent Herbert screw fixation (n=61) or Acutrak screw fixation (n=71) with or without bone grafting for scaphoid non-union and delayed union by a single surgeon were reviewed. The most common fracture site was the waist of the scaph...

BACKGROUND We aimed to use the animal model of dynamic fixation to examine the interaction of the pedicle screw surface with surrounding bone, and determine whether pedicle screws achieve good mechanical stability in the vertebrae. METHODS Twenty-four goats aged 2-3 years had Cosmic ® pedicle screws implanted into both sides of the L2-L5 pedicles. Twelve goats in the bilateral dynamic fixatio...

OBJECTIVES To report the application and clinical outcome of the treatment of radial carpal bone fracture in five dogs using a variably-pitched, headless cannulated compression screw (Acutrak). METHODS Arthroscopy was performed prior to surgical repair in three cases. In two cases, a fissure within the radial carpal bone was more clearly apparent when oblique indirect illumination was employe...

INTRODUCTION: In a pedicle screw fixation, the degree of osseointegration between a screw and the bone is an essential factor for the stability and fusion. In patients with osteoporosis, however, there is a high possibility for a pedicle screw loosening. Owing to this, there is a difficulty in determining the surgical indications. Previous biomechanical studies have reported that a pedicle scre...

In lower cancellous apparent bone density, it can be difficult to achieve adequate screw fixation and hence stable fracture fixation. Different strategies have been proposed, one of them is through augmentation using calcium phosphate cement in the region at or close to the screw thread itself. To support the hypothesis of an improved screw fixation technique by augmentation of the bone surroun...

Aim. The aim of this study was histomorphologic and histomorphometric evaluation of peri-screw bone after immediate orthodontic and orthopedic forces and comparing them with a control group. Materials and Methods. 18 dual-top miniscrews were inserted in the premolar region of three Iranian dogs. Screws were divided into three groups: (1) the first group undergoing immediate orthodontic force of...

Objective The purpose of this study was to determine the feasibility of screw fixation in previously augmented vertebrae with bone cement. We also investigated the influence of cement distribution pattern on the surgical technique. Methods Fourteen patients who required screw fixation at the level of the previous percutaneous vertebroplasty or balloon kyphoplasty were enrolled in this study. ...

INTRODUCTION Although pedicle or lateral mass screws are usually chosen to fix atlantoaxial (C1-C2) instability, there is an increased risk for vertebral artery (VA) injury when used in patients with bone or arterial anomalies or osteoporotic bone. Here we report the C1 posterior arch screw as a new technique for upper cervical fixation. CASE DESCRIPTION A 90-year-old man complained of upper ...

RATIONALE: The purpose of the current study is to establish the biomechanical rationale for the increased risk of periprosthetic fracture associated with locking screw constructs over conventional screw constructs. This is important because the promise of locking plates to increase fixation in osteoporotic bone must be balanced with the potential complication of a periprosthetic fracture. An un...