EPIPHYSIOLYSIS OF THE CAPITELLUM HUMERI - rbrs

position to total separation of the
epiphysis if significant trauma
occurs. During maturation, separate
ossification centres develop for the
capitellum, the medial epicondyle,
the trochlea and the lateral epicondyle.
In early youth, the growth
plate gradually extends obliquely
downward and medially from a
point just above the lateral epicondyle
to below the medial epicondyle
(Fig. 4).
By age 4, the growth plate becomes
more irregular and metaphyseal
bone begins to project between
the medial epicondyle and the capitellum,
dividing the physis into two
separate physes. Both of these factors
aid stability and total separation
of the epiphyses becomes more difficult.
Anatomic peculiarities of the distal
humerus may therefore explain
the differences in age distribution of
these injuries (2).
Many classifications of physeal
injuries have been proposed. The
classification of Salter and Harris
(Fig. 5) is the most commonly used:
type 1: a fracture that involves epiphyseal
separation because of a
fracture through the physis only,
type 2: a fracture through the physis
and metaphysis, with a fragment of
the metaphysis remaining attached
to the epiphysis, type 3: a fracture
that begins intra-articularly and travels
through the epiphysis into the
physis, type 4: a fracture that begins
intra-articularly and travels through
the epiphysis, physis and the metaphysis,
and type 5: the physis is
crushed (3).
Anteroposterior and lateral radiographs
of the injured elbow are
EPIPHYSIOLYSIS OF THE CAPITELLUM HUMERI — LAUWERS et al 185
Fig. 3. — Image during open reduction and internal fixation:
note the displaced capitellum (arrow).
essential for evaluation. Views of the
opposite elbow in the same position
provide a valuable basis for comparison
in assessing injury, but should
not be taken on a routine base. Intraarticular
haematoma may displace
the posterior fat pad of the distal
humerus (the “fat pad sign”), which
may be the only demonstrable sign
in an undisplaced or spontaneously
reduced fracture. But in case of capsular
rupture, the intra-articular
blood or fluid can leak in the sur-
Fig. 4. — Schematic drawing of the normal age of ossification
of the elbow. Numbers indicate the approximate age in years at
which the centre begins to ossify.
Fig. 5. — Schematic drawing of the Salter-Harris classification
of physeal injuries.
rounding tissues, and the fat pad
sign can disappear. So, a normal fat
pad does not exclude a fracture of
the elbow.
Because the epiphysis is primarily
cartilaginous in young children,
epiphyseal separation may be difficult
to diagnose by routine radiographs.
Ultrasound has gained an
increasing role in the diagnosis of
musculo-skeletal pathology (3). It is
non-invasive, and does not require
sedation. High resolution real-time