Bone is a living tissue and it needs blood supply to survive. If
there is damage to one of the blood supply, bone may depend on the accessory
blood supply for the survival. But certain bones in our body have precarious
unidirectional blood supply like Head of femur, scaphoid, and talus.
When there is damage to blood supply to the head of femur it
results in the death of cells in the femoral head. Gradually there is collapse
of femoral head with loss of sphericity. This condition is referred to as
Avascular necrosis of femoral head or Osteonecrosis (bone death) of femoral
head.
How AVN develops in femoral head?
Hip joint is a ball and socket type of synovial joint. The socket
is formed by cup shaped acetabulum which surrounds the ball (femoral head -
upper end of thigh bone). The surface of femoral head and socket is lined by
thick articular cartilage and then lined by synovial membrane. All together
with the surrounding joint capsule and muscles form a hip joint.
The ball of hip joint receives most of its blood supply through
the neck of thigh bone. If there is damage to this blood supply there is no
accessory blood supply to the femoral head.
There is gradual death of cells in femoral head due to loss of
blood supply. Due to death of bone cells, there is no reparative process of
bone formation and resorption. Gradually the bony structure in the femoral head
weakens and starts to collapse. When AVN develops in the head femur, the weight
bearing area of the head is the first place to collapse. The rounded contour of
the femoral head is lost and it becomes flattened causing abnormal movement in
the hip joint.
Secondary osteoarthritis develops, as there is gradual wear in
ball and socket of the hip joint.
Causes:
Many causes have been identified
Trauma:
Fractures
Damage to the blood supply of femoral head usually occurs
following a trauma or fractures to the bones in and around the hip joint.
Ø Fracture of Femoral neck, Femoral head
Ø Hip Dislocations
Ø Bad fractures of acetabulum
AVN can develop months or some times after initial injury.
Drugs:
Steroids:
Some steroids like cortisone,
prednislone or methyprednisolone are known to cause AVN. In certain conditions like bronchial asthma,
skin diseases, some auto immune disorders, inflammatory arthritis and in cases
of organ transplant to prevent rejection, use of steroids is must to control or
treat these conditions. Orally prescribed steroid are notorious in producing
AVN of femoral head. There have been studies to show that steroid given in the
form of injections into the joints or bursa does not cause any AVN of femoral
head.
Blood
disorders:
Some blood diseases like sickle cell disease, Leukemia’s, Gauchers
disease and diseases related to blood coagulation can cause AVN of femoral
head.
Lifestyle:
Studies have shown that alcohol and smoking can cause AVN in
femoral head. Chronic alcohol intake can damage blood vessels leading to AVN.
Smoking cause narrowing of small blood vessels and thereby reducing blood
supply to the femoral head.
Others:
Deep see divers and miners are more prone develop AVN. Due to high
atomospheric pressure tiny air bubbles are formed inside the blood stream which
can block the tiny blood vessels in the femoral head there by resulting in AVN.
Symptoms
What
does AVN feel like?
1. Pain:
Initially
patient complains of pain in the affected hip which gradually increases on
weight bearing. As the disease progresses patient complains of pain at rest and
at night.
2. Limping
3 3.Stiffness
4. Difficulty in sitting cross legged and squatting
5. Shortening of affected limb
Diagnosis
How do doctors identify the condition?
History: doctor inquires
about
- Occupation
-
Medical problems and any medications like steroids
-
Alcohol and smoking
2 Examination: doctor examines
hip for
- Range
of movements
-
Stiffness
X-rays:
X - rays do not show any changes of
AVN in the early stages of disease even though patient is having pain in the
hip. It may take few months to observe changes of AVN and make diagnosis on X -
ray.
MRI:
MRI can detect early
changes of AVN in the femoral head that cannot be seen on X- ray. It helps to
detect damaged areas of blood supply to the hip. AVN of femoral head can be
graded as mild, moderate and severe depending on the size location of these
damaged areas and if any collapse has occurred in the MRI images. MRI can also
help to detect AVN changes in the opposite hip even though there are no
symptoms.
Bone scan:
Bone scan involves
injecting a radioactive chemical into the blood. Hours after injection a
special camera is used to take pictures of your skeleton. The picture shows
blank spot in the areas of femoral head which is devoid of blood supply. MRI
has replaced Bone scan in diagnosing the cases of AVN of femoral head.
Treatment
What
are the treatment options for AVN of femoral head?
AVN of femoral head is irreversible resulting in arthritic hip.
Some drugs and salvage procedures can help in delaying the progress of
disease. The choice of treatment depends
upon the stage of the disease. Some factors like age of the patient, general
health of patient and activity level also determines the treatment methods.
Nonoperative
treatment:
If avascular necrosis of femoral head is diagnosed in early
stages, some of following treatment methods can help in delaying the progress
1.
Protected weight bearing on
the affected limb with the help of crutches or walker can help reduce pain. The
idea behind it is, it permits healing and prevents further damage.
2. Exercises and stretches prevent stiffness in the hip and helps to
maintain range of motion.
3. Medications:
A. Bisphosphnates : This group of drugs help to reduce the risk of
femoral head collapse in patients with Avascular necrosis.
B. Blood thinners: They are given in view of improving blood
circulation to the femoral head.
C. Anti-inflammatory medications / simple analgesics to reduce pain.
The above mentioned treatment modalities may delay the progression
of disease, but not completely reverse the Avascular necrosis.
Surgical management:
Salvage procedures: Some surgical procedures can try to decrease
the pressure in femoral head and increase the blood supply. The main
prerequisite for such surgeries is that there should not be any collapse in the
femoral head. Many procedures have been designed to improve the blood supply of
femoral head. Your surgeon can choose
and suggest appropriate procedure.
Core decompression of femoral head:
The most common surgical procedure is to drill one or several
holes into the femoral neck and head trying to enter into areas of poor blood
supply. The idea behind this procedure is one that it creates a new path for
new blood vessels to grow into areas of poor blood supply and it relieves
pressure inside the femoral head. The other advantage of this procedure is that
there is pain relief secondary to relieving pressure in the femoral head.
Core decompression of femoral head can be supplemented with bone
grafting with or without stem cells injection
Core
Decompression and Bone grafting of femoral head:
Following core decompression procedure bone graft is packed into
the dead part of femoral head and channel created in the femoral head and neck.
The bone graft can be taken from the patient or from the bone bank. The bone
graft is made into tiny pieces and packed into the channel created in the
femoral head and neck.
Stem
cells treatment:
Stem cells obtained from the patient body can be injected into the
channel created for core decompression of femoral head. Stem cells injection
can be done along with bone grafting also. There are studies showing that stem
cells help to stimulate new bone formation in the diseased areas of the femoral
head.
Postoperative
rehabilitation after core decompression surgery:
This surgical procedure is done through a very small incision from
the side of thigh. Surgeon guides the drill into the femoral head with help of
intraoperative X - ray machine
(C-Arm). This procedure is usually done as outpatient procedure and patient can
go back to the house on the same day with help of crutches or walker.
Following core decompression surgery the drill holes in the
femoral neck and head may weaken the bone, making it susceptible to fracture.
So patients are advised to use crutches or walker to move around for six weeks.
After six weeks, patient patients are advised to put full weight on operated
leg and take advice of physiotherapist to regain hip range of motion and
strength.
Advantages
of core decompression surgery:
Core decompression of femoral head is NOT A DEFINITIVE procedure.
It is a salvage procedure to delay the process of Avascular necrosis probably
by increasing blood supply and also preventing further collapse.
After the core decompression procedure it is necessary to
continue, the medications explained above as they also help in delaying the
progress of disease.
Core decompression and Vascularized fibular grafting:
In the first step surgeons drills a hole
into the femoral neck and head. In the next step surgeon removes small part of
fibula (Thin bone by the side of shin bone in leg) along with its blood
vessels. This is referred as vascularized fibular graft because it has its own
blood supply. Fibular graft is inserted into the channel created in the neck
and head of the femur. Vascular surgeon attaches the blood vessels from the
fibula to one of the blood vessels in the hip. This procedure does two things
1. Fibular graft acts as structural support
preventing collapse of femoral head.
2. The newly connected blood vessels try to
increase blood supply to the femoral head.
This is a very complicated procedure and
needs special expertise. The success of the surgery depends on the viability of
newly created blood supply. It is rarely practiced nowadays.
TOTAL HIP REPLACEMENT:
The process of Avascular necrosis of
femoral head invariably ends in arthritic hip. In arthritic hip, joint surfaces
of femoral head and acetabulum becomes irregular with loss of motion in the
joint. The treatment choice is total hip replacement.
Total hip replacement is procedure in
which the surgeon replaces the damaged femoral head and damaged joint surface
of acetabulum (socket) with prosthetic components. Damaged femoral head is
removed and replaced with metallic stem and ball. Damaged cartilage of the
socket of hip joint is replaced with metal socket.
Prosthetic components:
Total Hip replacement can be either
cemented or uncemented.
Cemented Total hip replacement: In this procedure, cement is used for fixation of
the prosthetic components into the bone.
Uncemented Total Hip replacement: In this technique, the fixation of components is by
“pressfit” into the bone which allows bone to grow onto the components.
Prosthetic materials:
Total hip replacement has wide range of
designs and materials.
The stem component and socket components
in the total hip arthroplasty are invariably medical grade steel or titanium
alloys. There is choice of material selection for the prosthetic head and liner
of socket. Prosthetic heads can be metallic or ceramic. Socket liners are available
in plastic, metallic and ceramic materials.
Different combinations of metal heads
and liners can be made depending on needs of the patient.
Metal on plastic (Metal head / Plastic
liner)
Ceramic on plastic (Ceramic head /
Plastic liner)
Metal on metal (Metal head / Metal
liner)
Metal on ceramic (Metal head / ceramic
liner)
Ceramic on ceramic (Ceramic head /
Ceramic liner)
The decision to use cemented or
uncemented components and various combination of head and socket liners are
based on various factors such as age, bone quality and sometimes surgeons
choice.
RESURFACING ARTHROPLASTY:
In certain patients with limited damage to the
part of femoral head surgeon may consider resurfacing arthroplasty. In this
procedure surgeon replaces only damaged femoral head with metallic implant.
Dr.A.Mohan Krishna
M.S.Ortho.,MCh orth (U.K)
Consultant Orthopedic surgeon,
Apollo Hospital
Appointments
Cell: 9247258989
9441184590
email: bonesandjointsclinic@gmail.com
online appointments:
www.drmohankrishna.com
www.bonesandjointsclinic.com
Plantar Fasciitis: It is the most common condition that causes heel pain.
Plantar fasciitis is due to irritation and inflammation of the tight tissue
that forms the arch of the foot. The most common symptom is pain under the heel
after a period of rest, i.e. severe pain and inability to walk in the morning
after getting up from sleep. The same might happen after sitting for a long
time and then trying to walk. Interestingly the pain gets better after a few
steps though it may not go away completely.
Again, the pain may get worse with prolonged walking and standing. X ray
may show a bony spur which may develop in long standing cases of heel pain due
to plantar fasciitis, but it may not cause the symptoms.
