METACARPALS AND PHALANGES FRACTURES

METACARPALS AND PHALANGES FRACTURES

Introduction and anatomy

Metacarpals bones

there are five metacarpal bones in each hand the metacarpus has shaft distal and proximal end
The thumb metacarpal is shorter and thicker than the other. Its base has a saddle -shaped facet for the trapezium. The convex facet on its bead is not so prominently The remaining four metacarpals show expanded bases by which they articulate with the distal row of carpal bones and with each other. The middle metacarpal shows a prominent styloid process that projects
dorsally into the angle between capitate and trapezoid The heads any boldly rounded articular facets which extend further on the flexor than the extensor surface. The four metacarpal bones together form a gentle concavity for the palm. Their heads form the knuckles of the fist
• First metacarpal is important because of the mobility of its carpometacarpal joint, which is responsible for opposition of the thumb

• Second metacarpal articulates with three carpal bones trapezium, trapezoid, and capitate

• Capitate articulates with three metacarpals, ie. second,third and fourth phalanges

Joints of the hand

Carpometacarpal joint

Thumb

• Saddle joint
Flexion, extension, abduction, adduction, opposition • Flexion/extension in plane parallel to palm • Abduction/adduction in plane at right angle to palm • Opposition: thumb opposes to little finger

Other carpometacarpal joints

have limited gliding movement only Metacarpophalangeal joints
A 60 degree range of flexion/extension at metacarpo­phalangeal joint of thumb
A 90 degree at other metacarpophalangeal joints, together with abduction, adduction, and circumduction
Abduction and adduction is impossible with the metacarpophalangeal joints flexed
• Metacarpophalangeal joints of fingers (not thumb) are joined by deep transverse ligaments which prevents them spreading
during a firm grip

Interphalangeal joints

• Hinge joints
• Flexion extension onl
• Collateral ligaments lax in extension and taut in flexion

PHALANGES

There are 14 phalanx in each hand three phalanx in each finger except the thumb has two phalanx each phalanx has shaft distal and proximal end
Two phalanges form the thumb, three form each finger. Each of the five proximal phalanges has a concave facet on the base, for the head of its own metacarpal. Middle and distal phalanges carry a facet on each base: that is divided by a central ridge into two concavities. The heads of the proximal and middle phalanges are corre­spondingly trochlea-shaped, with their facets on the distal and flexor surfaces, not on the extensor surface
Each distal or terminal phalanx expands distally into a tuberosity, roughened on the flexor surface for attach­ment of the digital fibrofatty pad

Metacarpals and phalanges fractures

These fractures are not common and the treatment of these fractures depend on position and type of the fracture

Fracture of the fifth metacarpal neck

Causes

These are usually caused by a punch (hence the name -boxer,s fracture ). Up to 60 degree of flexion at the fracture site can be accepted because of the spare hyperextension in the fifth metacarpopha­langeal joint and because the most important function of the lit­tle finger is to flex , loss of extension is not so important

Investigations

  Radiographs X rays plain is simple and good for diagnosis of these fractures

Treatment

 

 It is treated with elevation and splintage for a few days and then gen­tle mobilisation. Surgery is rarely required. The (dropped knuckle) deformity is permanent
 
Metacarpal shaft fractures

Causes and investigations as above

Treatment

 Stable and undisplaced fractures which they are most  common  only need a resting splint for 1-2 weeks followed by careful mobilisation

Displaced fractures as

  When the frac­ture is spiral, rotation can occur at the fracture, and the finger no longer points to the scaphoid tubercle along with the other fingers when flexed into the palm. Union then results in fingers which tangle together when trying to make a fist , if the fracture is angu­lated, the prominent metacarpal head can be uncomfortable when gripping 

 Displaced metacarpal fractures therefore need manipulation and fixation with plates or percutaneous Kirschner wires

Phalangeal fractures

Whatever the fracture, the management must allow the fingers to be moved within a few days of injury to avoid stiffness. Most phalangeal fractures are undisplaced or can be manipulated under local anaesthetic into a stable anatomical position

The hand is splinted and elevated for a few days, when the

fractured finger is strapped to a neighbouring finger and mobilised called buddy strapping

If the fracture is displaced and unstable, or if the joint surface is disrupted, accurate reduction and fixation is needed. Rigid fixation with miniplates and screws allows early mobilization, which prevents stiffness. but unfortunately the soft­ tissue dissection required paradoxically can cause stiffness. Therefore, percutaneous wires are generally preferred unless open surgery is needed for reduction ligaments

 Summary of fractures of the metacarpals and phalanges

• Boxer,s fractures may be best left unreduced

• Spiral fractures of the metacarpals may lead to rotatory malunion

• Phalangeal fractures need early mobilisation to avoid stiffness

tags:phalanges,fractures,metacarpals