Radial Head Fractures - Alistair Jepson 30/1/2001

BACKGROUND

Mechanism of injury:

(i) F.O.S.H. - force transmitted along line of forearm producing valgus stress at elbow (may also cause a capitellar #)

- greater carrying angle in women postulated as reason for higher incidence in women

(ii) direct blow to elbow

Mechanism likely to be a good predictor for the type of # too

Classification:

Mason (Br J Surg 1954)

Type I : 'fissure or marginal #'s without displacement' (lateral quadrant)

Type II : 'marginal sector fractures with displacement' (displaced, impacted or tilted)

Type III : 'comminuted #'s involving the whole head of the radius'.

Often quoted as:

I : undisplaced radial head #

II : displaced # with either >2 or 3mm step in articular surface, >30 ° angulation or >30% of head involvement

III : comminuted #

Then either simple or complex depending on whether assoc with another # or ligamentous injury such as dislocation

This classification has since been modified by:

a) Johnston (Ulster Med J 1962) adding IV : radial head # assoc with dislocation of the elbow (~5-10% of all radial head #'s and conversely same % of dislocations associated with radial head #'s),

b) Hotchkiss (J Am Acad Orthop Surg 1997) to include completely displaced #'s of the radial head assoc with radial neck #

Fracture mechanics:

o Other #'s assoc with radial head # are proximal part of ulna, occasionally distal humerus, particularly capitellum

o Associated ligamentous injuries are very important

- Medial collateral ligament of elbow (1 ° stabiliser of the elbow)

- Lateral collateral ligament

- Distal radio-ulnar joint - Essex Lopresti injury = Acute Distal Radio-Ulnar disruption

o occurs in ~5% of all radial head #'s

o should be examined for clinically (tenderness at DRUJ)

o best XR to show is a lateral wrist with hand in full pronation (distal ulna will sublux dorsally)