Anatomy Practical 2 Flashcards
what is the most common condition that requires hip replacement
osteoarthritis
In the majority of cases of (OA) there is no previous history of injury to the hip joint - the hip simply “wears out”.
what is osteoarthritis commonly referred to
wear and tear arhritis
Is there a genetic tendency in OA
There may be a genetic tendency in some people that increases their chances of developing OA
what happens in avascular necrosis
Another cause of degeneration of the hip joint is avascular necrosis of the femoral head , which loses a portion of its blood supply and actually dies
what is avascular necrosis linked to
Avascular necrosis (AVN) has been linked to alcoholism, fractures and dislocations of the hip, and long term cortisone treatment for other diseases.
Why are the hip and knee joint most commonly affected by OA?
bear the most weight
What features of OA can be recognised in an X-ray?
- narrowing of the space between the bones where the cartilage wears away
- cysts and fluid filled cavities caused by the bones rubbing against each other
what arteries supply the femoral head
medial femoral circumflex artery
lateral femoral circumflex artery
branch of the obturator artery
What is the main symptom of a degenerating hip joint
pain whilst weight bearing
what does degeneration lead to
The degeneration leads to a reduction in the range of motion of the affected hip
Bony spurs will usually develop which may limit how far the hip is able to move
How do you diagnose hip degeneration
- history
- physical
- x rays - determine the extent of the degenerative process and suggest a cause for the degeneration
- MRI - scanning may be necessary to determine whether avascular necrosis is causing the hip condition
what are the two major types of artificial hip replacements
- Cemented prosthesis
- Uncemented prosthesis
What is the choice of the type of artificial hip replacement based of of
The choice is usually made by the surgeon based on the age of the patient and their lifestyle, as well as the surgeon’s experience and personal preferences.
What is the prosthesis made up of
an acetabular component and a femoral component
The femoral component may come as a complete unit with the femoral stem and the femoral head joined together, or the femoral stem and the femoral head may come separately.
What is the femoral component of the prosthesis made out of
The femoral component is made of metal (some actually have a ceramic ball attached to the metal stem)
What is the acetabular compoenent made up of
The acetabular component is made of a metal shell with a plastic inner socket liner that acts like a bearing. The plastic used is very tough and very smooth and slick - (slick = slippery).
What are the advantages and disadvantages of a cemented
cemented
Advantages
- Bone cement allows a surgeon to affix prosthetic joint components to a bone that is slightly porous from osteoporosis.
- A small amount of antibiotic material can be added to the bone cement, helping to decrease the risk of post-surgical infection.
- The bone cement dries within 10 minutes of application, so the surgeon and patient can be confident the prosthetic is firmly in place
Disadvantages
- The drawback to using bone cement is that it may degrade over time and bits of cement can break off, potentially causing problems:
- A breakdown of the cement can cause the artificial joint to come loose, which may prompt the need for another joint replacement surgery (revision surgery).
- The cement debris can irritate the surrounding soft tissue and cause inflammation.
- While rare, the cement can enter the bloodstream and end up in the lungs, a condition that can be life-threatening. This risk is greatest for people who undergo spinal surgeries.
What are the advantages and disadvantages of an uncemented hip joint
A number of surgeons prefer cementless components because:
- They believe cementless components offer a better long-term bond between the prostheses and bones.
- Cementless components eliminate worry about the potential breakdown of cement.
The downsides to cementless prostheses are that:
- Press-fit prostheses require healthy bones. Patients with low bone density due to osteoporosis may not be eligible for these components.
- It can take up to three months for bone material to grow into a new joint component.1,2
What ligament is removed during a total hip arthroplasty?
x
what is the most common cause for patients to undergo knee replacement surgery
Osteoarthritis
What is the prosthesis for the knee joint made up of
1 The tibial component (bottom portion) replaces the top of the tibia (remember that the fibula plays no part in the knee joint.
2 The femoral component (top portion) replaces the two femoral condyles and the groove where the patella runs.
3 The patellar component (kneecap portion) replaces the joint surface on the bottom of the patella that rubs against the femur in the femoral groove
what is the femoral component of a knee joint made up of
- made of metal
what is the tibial component of a knee joint made up of
a metal tray that is attached directly to the bone and a plastic spacer that provides the bearing surface which replaces the menisci
What is hip joint made up of
As for the hip the plastic used is very tough and very slick.
what happens in a skeletal traction
In skeletal traction, a pin (eg, Steinmann pin) is placed through a bone distal to the fracture. Weights are applied to this pin, and the patient is placed in an apparatus to facilitate traction and nursing care.
When is traction most commonly used
Skeletal traction is most commonly used in femur fractures: A pin is placed in the distal femur (see image below) or proximal tibia 1-2 cm posterior to the tibial tuberosity. Once the
pin is placed, a Thomas splint is used to achieve balanced suspension.
What is external fixation
External fixation is a surgical treatment wherein rods are screwed into bone and exit the body to be attached to a stabilizing structure on the outside of the body
When is plaster of paris used
Plaster of Paris is used for the treatment of bone fracture, soft tissue injuries and for immobilisation where required
What is now replacing plaster of paris
Newer fibreglass based casts are now replacing plaster of Paris and are lighter and slightly more water resistant than the older casts.
What are the advantages and disadvantages of plaster casting
x
What are some of the complications of plaster casting
x
what is used for a more complex external fixation
a frame is used with pins that pass through the skin and sometimes muscles to connect the external fixator to the bone
two or more pins are placed on either side of the broken bone to hold the bond in place and to anchor the fixator securely
- sometimes wires are used with pins or instead of pins to secure the bone pieces
- the surgery uses the external fixator to place the broken bone in its correct position and alignment until bone healing occurs
How long can bone healing take
This may take approximately six weeks for a simple fracture, and up to one year or longer for a more complicated procedure.
What happens when the fixation is internal
When the fixation is internal, bone fragments may be fixed with Kirschner wires (K-wires) screws, transfixing pins or nails, a metal plate held by screws, a long intramedullary nail (with or without locking screws), circumferential bands, or a combination of these methods.
What do K wires do
K-wires (often inserted percutaneously without exposing the fracture) can hold fracture fragments together.
Some form of external splintage (usually a cast) is applied as supplementary support.
When are K wires used
They are used in situations where fracture healing is predictably quick.