Osteochondritis
This loosely defined term embraces three pathological processes
involving epiphyses of larger bones or even the whole of a small bone, e.g. in
the carpus or tarsus.
The
processes are avascular necrosis affecting epiphyses normally under
compression, chronic strain injuries to traction epiphyses and osteochondritis
dissecans, which is a stress fracture through articular cartilage with or
without involvement of subchondral bone. The individual conditions are usually
referred to anonymously (Table 28.1).
Avascular
necrosis (AVN)
The causes of osteochondritis presenting as AVN are obscure and theories
include interruption of arterial supply through
This is a mysterious and poorly understood condition. The capital
femoral epiphysis undergoes an early stage of infarction, progressing to
collapse and fragmentation, followed by healing (Figs
28.1 28.2, 28.3, and 28.4). The whole
process takes several years (Fig. 28.2) and involves part or all of the
epiphysis.
Various
classifications of the radiological changes have been used, e.g. Catterall,
Salter—Thompson, Herring. Unfortunately, they are prone to interobservor
error and it is difficult from a single set of X-rays to be sure of the stage or
extent of the disease. Moreover, radiological classifications do not reliably
relate to the age of the child or the clinical features. For example, a child,
especially if young, with whole head involvement may have good movements and
very little disability. The condition is relatively benign in the majority of
children and does not lead to severe disability or
Clinical
features. The condition can occur between the ages of 3 and 12. It is more
common in boys and more frequent in children of low birth weight or those who
had a constitutional delay in growth. There is a family history in 12 per cent
of cases and the condition may be bilateral in 20 per cent. Synchronous
involvement is rare and when seen the diagnosis of multiple epiphyseal dysplasia
should be considered.
The
usual presentation is pain and a limp. These can be mild and intermittent so the
onset may be difficult to define. The pain is usually in the hip region but,
like slipped upper femoral epiphysis (SUFE), can be referred to thigh or knee.
Therefore children with knee pain should always have their hips examined and
X-rayed if there is any suspicion of disease therein.
In
LCP disease, flexion is usually maintained but the hips lose abduction and
internal rotation. The thigh is usually thinner than the normal side and the Trendelenburg test frequently
positive. In spite of these clinical features the children usually remain active
and regularly have to be restrained.
The
diagnosis is confirmed by radiographs. Magnetic resonance imaging (MRI) or bone
scans may be helpful in the very early stages.
Treatment.
The goal is to achieve a congruous joint. The majority of cases will not regain
their previous normal shape (spherical congruity) but heal as an oval head (aspherical
congruity). However, providing the head matches the socket, the hip is likely to
do well in the long term. Where there is a mismatch (aspherical incongruity) the
hip does badly.
It
is generally agreed that hips should be exercised and kept as mobile as
possible, thereby aiming to prevent adduction or flexion deformity and encourage
remodelling to a congruous joint. If adduction deformity develops, a period in
abduction splintage should be considered.
The
role of open surgery, e.g. femoral or innominate osteotomy, is controversial,
especially in the younger child. It is difficult to prove that surgery will be
beneficial in the long term. In the short term, operations designed to achieve
containment of the femoral head may cause damage to the growth plate, usually
make a limp worse and may cause incongruity and stiffness. Therefore, if a
surgeon cannot feel sure of achieving a congruous joint (an arthrogram may help
in the assessment) a better alternative to osteotomy is a shelf-type procedure
to augment the acetabulum and thereby give better cover to the femoral head.
In
summary, LCP disease is generally benign with a good long-term prognosis. The
hip should be kept mobile to avoid deformity and encourage congruous healing.
Children who are younger and with partial head involvement do better and the role of operations remains controversial. We still do not know how
to select accurately those children who will benefit from surgery in the long
term.
Freiberg’s disease
This affects the distal epiphysis of the second metatarsal and is
generally very troublesome. If simple treatment, such as insoles, fails it may
be necessary to consider osteotomy or even excision of the metatarsal head.
Kohler's disease
This benign condition affects the tarsal navicular. This normally does
not ossify until the fourth year of life and thereby confusion may occur.
Kohler’s disease presents with pain which is usually not bad enough to warrant
more than symptomatic treatment. Radiographs show a flattened navicular (Fig.
28.5)
and a comparison view of the other foot is indicated to ensure that one is
not dealing with a normal ossification pattern. The children can be advised on
activity within the limits of their symptoms and the navicular usually remodels
to normality.
Keinbock
disease
This affects the carpal lunate and causes troublesome pain and
stiffness. It usually affects older teenagers and young
Panner’s
disease
The capitellum becomes flattened and the elbow stiffens. There is no
satisfactory operation for the condition but fortunately good elbow function is
usually maintained.
Traction
or strain injuries
These can occur wherever powerful muscles are attached to bone. In
children ligaments and tendons are generally stronger than bone and acute or
chronic traction injuries manifest by signs of avulsion. Examples of acute
traction injuries include rectus femoris at the anterior—inferior iliac spine
and hamstrings at the ischial tuberosity.
The
classical chronic traction injuries are recognised eponymously. They are:
• Osgood—Schlatter’s disease (tibial tubercle; Fig.
28.6);
• Sinding Larsen disease (distal pole of patella);
• Sever’s disease (posterior epiphysis of os calcis).
The
treatment of all these injuries is rest. Unfortunately many of the affected
children are keen athletes and the lesions are the effects of excessive demands
on an immature
Osteochondritis
dissecans
In this condition, a piece of articular cartilage, with or without the
underlying subchondral bone, becomes unstable and may detach into the joint,
thereby forming a loose body. The mechanism is acute or chronic trauma.
Common
sites include the medial femoral condyle, talus and capitellum. Loose bodies
cause pain and locking whereas an unstable fragment may cause discomfort when
the joint is stressed.
The
lesions may be present on plain X-rays but can also be well demonstrated by MRI.
In
general an expectant approach is adopted, unless a troublesome loose body needs
removal.