- Discussion:
- subluxation of the head of radius from its encirclement by annular
ligament is a common elbow injury among
young children; (nurse maid)
- most common prior to age 6 yrs because prior to this age, the radial head
is spherical and is composed
mainly of cartilage;
-
mechanism:
- subluxation of the radial head generally results from a sudden pull
on the upper limb, such as that
exerted by an adult to
prevent the child from falling;
- radial head is traumatically subluxated w/ forceful traction on the
hand w/ the elbow extended and the
forearm pronated;
- annular ligament either tears or slips over the radial head, allowing
subluxation of radial head;
- w/ release of traction, the ligament remains interposed between the
radial head and capitellum;
-
diff dx:
- need distinguish nurse maid from
congenital dislocation of radial head:
-
Monteggia frx:
- occurance of radial head dislocation along w/ a subtle plastic
deformation of the ulnar shaft;
- note that posterior border of ulnar shaft should appear
perfectly straight on the lateral radiograph,
and any bowing indicates an associated
green
stick frx;
- Clinical Presentation:
- child presents w/ injured elbow pronated, partially flexed and held by
side;
- forearm is pronated and the elbow is partially flexed;
- there is anterolateral tenderness over the radial head;
- usually occurs in children under age 4 and rare after age > 5;
- the child presents with a flexed and pronated forearm supported closely to
the trunk of the body;
- the patient complains of pain around the radial head;
- Radiographs:
- radiographs to r/o associated fractures;
- lateral radiograph of a nurse maid's elbow does not show dirsuption of
colinear relationship between
capitulum & central axis of the radius;
- relationship of radius & ulna that indicates pronated posture of the
forearm;
- Reduction of nurse maid elbow:
- interposed annular ligament can be repositioned in its normal site by
simple supination of forearrm w/ the
elbow in slight flexion;
- elbow is gently flexed to 90 deg by gripping childs forearm above wrist w/
one hand while, w/ other hand,
lower end of humerus and elbow are held to prevent
rotation at shoulder;
- thumb is placed in region of of the radial head for palpation &
application of posteriorly directed pressure
on the head of the radius, while firmly, supinating
and extending the forearm;
- childs forearm is firmly rotated into full supination;
- immediately following reduction, a click may be heard, & child should note
the sudden relief of pain;
- these manipulations screw the radial head into the annular lig;
- Post Reduction Treatment:
- immobilization is not necessary for the first episode of subluxation;
- if treatment of subluxation is delayed for > 12 hrs following reduction,
upper limb is immobilized for 10 days
in long arm posterior splint w/ elbow in 90 deg of flexion
& forearm in full supination;
- if pt has 3 recurrent episodes of subluxation, then apply cast for 3
weeks;