2. TYPES:
1- Autografts (autogenous grafts)
In these, bone is transferred from one place to another in the same
individual. This is the most commonly used form of bone-grafting, but it
depends on there being sufficient donor bone of the sort required and a
recipient site with a clean vascular bed. Most of the transplanted bone
dies, but it continues to act as a scaffold, which is gradually replaced by a
process of creeping substitution. Cancellous Autografts can be obtained
from the thicker portions of the ilium, the greater trochanter, the
proximal metaphysis of the tibia, the lower radius, the olecranon, or from
an excised femoral head. Cortical grafts can harvested from any
convenient long bone or from the iliac crest; they usually need to be fixed
with screws, sometimes reinforced by a plate, and can be placed on the
host bone, or inlaid, or slid along the long axis of the bone.
The ideal vascularised autograft is one with an intact blood supply.
Bone is transferred complete with its blood vessels, which are
anastomosed to vessels at the recipient site. The technique is difficult and
time consuming, requiring microsurgical skill. Available donor sites
include the iliac crest (complete with one of the circumflex arteries), the
fibula (with the peroneal artery) and the radial shaft. Vascularized grafts
remain completely viable and become incorporated by a process
analogous to fracture healing.
5. Other types of graft
3- Xenografts
are obtained from another mammalian species, such as
pigs or cows. After treatment for antigenicity, they should,
theoretically, behave like allografts, but in practice they
are much less effective unless host marrow is added to the
graft.
4- 'Artificial bone‘
made of hydroxyapatite composites can be used in the
same way to fill a cavity or bridge a small gap. Bioactive
bone cements (injectable calcium phosphate preparations)
offer a simple alternative, e.g. for replacing bone loss in
metaphyseal fractures.
7. DISTRACTION HISTOGENESIS AND LIMB
RECONSTRUCTION
Present-day limb reconstruction is founded on the
principle that new-bone formation is stimulated in
response to gradual increases in tension. This was
originally discovered by Gavril Ilizarov in Russia and the
application of this principle to bone reconstruction is
widely referred to as the Ilizarov method.
13. Normally the medial border of the foot, even when
weight-bearing, forms a longitudinal arch. The
arrangement of the metatarsals also produces an
anterior or transverse arch in the forefoot. Flattening
of the longitudinal arch is referred to as a planus
deformity or flat-foot; and a dropped metatarsal arch
as anterior flat-foot. An excessively high arch
produces a cavus deformity.
Common deformities of the toes are lateral deviation
of the big toe (hallux valgus), proximal
interphalangeal flexion of one of the lesser toes
(hammer-toe) and flexion of both interphalangeal
joints of several toes (claw-toes).
14. CONGENITAL TALIPES EQUINOVARUS (IDIOPATHIC
CLUB-FOOT)
In this deformity the heel is in equinus (pointing
downwards), the entire hindfoot in varus (tilted towards
the midline) and the mid-foot and forefoot adducted and
supinated (twisted medially and the sole turned upwards).
It is relatively common; the incidence is 1 or 2 per 1000
birth and boys are affected twice as often as girls. The
condition is bilateral in one-third of cases. Similar
deformities are seen in neurological disorders e.g.,
myelomeningocele, and in arthrogryposis.
The skin and soft tissues of the calf and the medial side
of the foot are short and underdeveloped. If the condition
is not corrected early, secondary growth changes occur in
the bones and these are permanent. Even with treatment,
the foot is liable to be short and the calf may remain thin.
15.
16. Clinical features
The deformity is usually obvious at birth; the foot is both
turned and twisted inwards so that the sole faces
posteromedially. The heel is usually small and high, and
deep creases appear posteriorly and medially. In a normal
baby the foot can be dorsiflexed and everted until the toes
almost touch the front of the leg. In club-foot this
manoeuvre meets with varying degrees of resistance and
in severe cases the deformity is fixed.
The infant must always be examined for associated
disorders such as congenital hip dislocation and spina
bifida.
X-rays
The tarsal bones are incompletely ossified at this age and
the anatomy is therefore difficult to define. However, the
shape and position of the tarsal ossific centres are helpful
in assessing progress after treatment.