Lecture for undergraduate students

1. Fractures of Forearm
Dr. Sundar Karki
MBBS, MS (Ortho), Lecturer
Department of Orthopedics and Trauma
Devdaha Medical College

2. Introduction
 The radius and ulna are common sites for fracture
in all age groups. These may result from direct or
indirect injury. Common combinations of injury in
this region are:
 Fracture of both bones of the forearm
 Monteggia fracture-dislocation and
 Galeazzi fracture-dislocation.

3. Relevant Anatomy
 Muscles controlling supination and pronation
 The muscles producing these movements are
attached to the forearm bones, and are responsible
for the rotational displacement of these fractures.
 The supinators of the forearm (biceps and the
supinator) are attached to the radius in its
proximal third .
 The pronators (pronator teres and pronator
quadratus) are attached to the middle and distal-
thirds of the radius respectively.

4. Relevant Anatomy
 This means that the supinators control the
proximal half of the forearm whereas the
pronators control the distal-half.
 Therefore, in fractures of the proximal-third of
the forearm bones, the proximal half of the
forearm has only supinators attached to it, and
is supinated.
 The distal half on the other hand is pronated. In
fractures of the middle-third, both the proximal
and the distal halves of the forearm are in mid
pronation.

5. Relevant Anatomy
 Radio-ulnar articulation: The radius and ulna
articulate with each other by the proximal and
distal radio-ulnar joints, and interosseous
membrane.
 Hence, an injury to the forearm usually results in
fractures of both the bones. In a case where there is
a fracture of only one bone, and the fracture
is displaced, there should be dislocation of the
proximal or the distal radio-ulnar joint.

7. FRACTURES OF THE
FOREARM BONES
 The radius and ulna are commonly fractured
together – termed fracture of ‘both bones of the
forearm’.
 Sometimes, there may be a fracture of either of the
bones without much displacement.
 The cause of fracture may be either an indirect
force such as a fall on the hand, or a direct force
such as stick blow to the forearm.

8. Displacements
 In children, these fractures are often undisplaced, or
minimally displaced (greenstick fractures), but in
adults they are notoriously prone to severe
displacement. A combination of any of the following
displacements may occur:
• Angulation – commonly medial and anterior
• Shift – in any direction
• Rotation – the proximal and distal fragments lie in
different positions of rotations (e.g., the proximal
fragment may be supinated and the distal pronated).

9. Treatment
 Conservative treatment is sufficient in most cases.
For adults with displaced fractures, operative
treatment is often required.
 Conservative treatment: This consists of closed
reduction by manipulation under general anesthesia,
and immobilization in an above-elbow plaster cast.
 Open reduction and internal fixation: In a large
proportion of cases, especially in adults, it is
impossible to obtain satisfactory reduction by
closed manipulation, or to maintain it in plaster. So
open reduction and internal fixation is done.

11. Complications
 Infection: An open fracture of both bones of the forearm
may become secondarily infected, leading to osteomyelitis.
 Volkmann's ischemia: This occurs within 8 hours of
injury, as a result of ischemic damage to the muscles of
the flexor compartment of the forearm.
 Delayed union and non-union: Fractures of shafts of both
bones of the forearm are prone to delayed union,
particularly that of ulnar shaft at the junction of the
middle and lower-thirds. The cause of non-union is
usually inadequate immobilization.
 Treatment of non-union of these bones is open reduction
and internal fixation using plates, and bone grafting.

12. Complications
 Malunion: This results from failure to achieve and
maintain a good reduction so that the bones unite
in an unacceptable position, leading to deformity
and limitation of movement – especially that of
rotation of the forearm.
 Treatment is open reduction and internal fixation
using plates, and bone grafting.

13. Complications
 Cross union: When radius and ulna fractures are
joined to each other by a bridge of callus, it is
called a cross union. It is likely to develop in a
case where the two fractures are at the same
level. It result in a complete limitation of forearm
rotations.
 If the cross union is in mid-pronation, the
position most suitable for function, it is left as it
is. If it occurs in excessive pronation or
supination, operative treatment may be required.

14. MONTEGGIA FRACTURE
DISLOCATION
 Fracture of proximal third of the ulna with
dislocation of the proximal radial head.
 It is caused by a fall on an out-stretched hand. It
may also result from a direct blow on the back of
the upper forearm.

16. Bado classification
 Type 1 (60%)—anterior radial head dislocation and
apex anterior proximal-third ulna fracture. Also called
extension type.
 Type 2 (15%)—posterior radial head dislocation and
apex posterior proximal-third ulna fracture. Annular
ligament is disrupted in posterior Monteggia fracture
dislocations.

17. Bado classification
 Type 3—lateral radial head dislocation and proximal
ulnar metaphyseal fracture.
 Type 4—anterior radial head dislocation and
proximal-third radius and ulna fractures below
bicipital groove.
 “Monteggia-equivalent or variant”—radial head
fracture instead of dislocation.

18. Bado classification

19. Treatment
 All Monteggia fractures in adults should be treated
with ORIF.
 The radial head will normally reduce and be stable.
If not, the most common cause is a nonanatomic
reduction of the ulna.
 If the ulna is anatomic and the radial head does not
reduce, an open reduction with a separate approach
is required to address the annular ligament.

20. Complications
 The complication rate is higher for Monteggia equivalent
and Bado type II injuries.
 PIN injury: This causes paralysis of thumb and finger
extensors. Usually resolves spontaneously and should be
observed for 3 months.
 Redislocation/subluxation, synostosis, and loss of motion.

21. GALEAZZI FRACTURE-
DISLOCATION
 This injury is the counterpart of the Monteggia
fracture-dislocation.
 Here, there is a fracture of the lower third of the
radius with dislocation or subluxation of the distal
radio-ulnar joint.
 It commonly results from a fall on an out stretched
hand.

23. Displacement and Diagnosis
 Displacement: The radius fracture is angulated
medially and anteriorly. The distal radio-ulnar
joint is disrupted, resulting in dorsal dislocation of
the distal end of the ulna.
 Diagnosis: In an isolated fracture of the distal-half
of the radius, the distal radio-ulnar joint must be
carefully evaluated for subluxation or dislocation.

24. Treatment & Complications
 TREATMENT
 Perfect reduction is essential for complete restoration of
functions, particularly rotation of the forearm.
 It is difficult to achieve and maintain perfect reduction by
conservative methods (except in children).
 Most adults require open reduction and internal fixation
of the radius with a plate.
 COMPLICATIONS
Malunion occurs because of displacement of the
fragment. It results in deformity and limitation of
supination and pronation