Cortical Lag Screw To understand the concept of a lag screw it is necessary to understand the basic design of the cortical screw, which is the predominant type of screw used in the maxillofacial region Fig. Each cortical screw consists of a head and a shank; the entire length of the shank has threads and defines the screw length. Screw heads come in a variety of configurations; the popular ones have either a straight, cruciform, hexagonal, or square slot Fig. The shank has an internal diameter, also known as the core diameter, and an external diameter or thread diameter.
Span Plating or Bridge Plating Tension Band Plates come in different sizes and shapes depending on the size of the bone and its anatomical shape. Different sizes of plates require different sizes of screws. Depending upon the fracture location and type, a plate can be used in any one of the following modes Compression Mode The word compression in fracture fixation means bringing the two fragments closer to each other so that the fragments oppose well.
This mode is used on transverse and oblique fractures Neutralization Mode In this type of plating, a lag screw is used to neutralize bending, shear and rotational forces. The aim of this type of plating is not to achieve compression [This has already been achieved by the lag screw.
Addition of a plate provides further resistance to such forces. The fibular fracture commonly seen in ankle injuries is often fixed with lag screws protected by a neutralization plate. The plate is put on the tensile Lag screw osteosynthesis of the bone but it is not prebent. A buttress plate is used to prevent a collapse in fracture patterns which are unstable under compressive forces.
A buttress plate is very thin as compared to compression plate and is mostly applied on the compressive surface of the bone. This is the most common way that plates are used around joints.
Here there is a relatively soft cancellous bone core surrounded by a thin layer of together cortical bone. Accurate osteosynthesis may be achieved by lag screws alone but under load, there may be a risk of the screws cutting out of the bone or bending.
The addition of a plate will prevent such deformity under axial load. The plate should be situated where the maximum load is predicted to be.
Proximal tibia, for example, plates may be required on one side or another to protect a tibial plateau fracture fixation. There are specially shaped plates for the most common anatomical buttressing requirements, and these make application of the plate easier.
Antiglide Plate In antiglide plating, the plate is fixed to the bone in such a way that it prevents the distal fragment from overriding when force is applied along the long axis of the bone.
This principle is mostly applied in fracture of the distal fibula. It can be called a variation of compression plating. Span Plating or Bridge Plating It is a modification of neutralization mode which is applied when there is comminution and one does not want to dissect the fracture area to avoid devitalization of the fragments.
This kind of plating is done under x-ray control or C-arm image intensifier. The plate is contoured slightly to bypass the fracture zone and fixed only to major proximal and distal segments. This not only minimizes the devitalization of the fracture zone but also promotes the formation of periosteal callus.
In this method of plating, farthermost screws in the plate are applied on either side and then fixation moves towards the center on either side of a fracture zone with holes of plate spanning left unused for fixation.
Tension Band A plate can also be solely used as a tension band apparatus. The plate is attached to the tension side of a fracture and converts the tensile force into a compressive force at the cortex opposite the implant.
An example of such use is in olecranon fracture Prebending of Bone Plates What is the prebending of plates and why it is done?
Various types of plates are used in fracture fixation. One of the common mode of use is compression mode where apart from the fixation of fractures, the application of the plate aims for closer apposition of the fracture fragments.
To understand the concept of prebending, we first need to understand terms far cortex and near cortex.Fractured Neck of Femur Definition. The femoral neck fracture is a crack near the hip joint, located between the top (head) of the bone of the leg and the main part of the latter.
The femoral neck fracture often occurs in the elderly after a fall on the hip. Osteoporosis (bone degradation) contributes regularly to .
3 Contents Page 1. Introduction 4 pfmlures.comes 5 Design Features of the Gamma3 System 5 Lag Screw and Set Screw Function 6 Distal Locking Screws 7. Lag screw osteosynthesis is a form of compression osteosynthesis in which the bone segments are bound to one another as a result of traction from the screw.
2 . Mar 20, · In this case the patient initially had undergone a rigid plate osteosynthesis with a lag screw through the plate.
Fracture healing was achieved after revision surgery with removal of the lag screw, replacement of the plate, and additional osteosynthesis of the fibula (Figure 7). Evaluation of Titanium Lag Screw Osteosynthesis in the Management of Mandibular Fractures World Journal of Dentistry, July-August ;8(4) WJD.
DHS and Interfragmentary screw in subtrochanteric fracture. Subtrochanteric fractures are fractures below the intertrochanteric line of the femur.
These are high-velocity fractures and quite common in young active adults.