what is the nonunion causes and its classification

When nine months have elapsed since the injury, and the fracture exhibits no radiologically visible progressive signs of healing continuously for three months, nonunion establishes.


nonunion of fracture is a very notorious complication to treat. infected nonunion challenges the clinical acumen of best of ortho surgeons.

there are various causes leading to nonunion and the following are some of those

Compound Fractures = there is extensive damage to the soft tissues in open fractures and there could be even loss of small pieces of bone.

the former results in impaired blood supply to the fracture fragments jeopardizing the chances of union.

Infection= commonly seen in compound fractures and in postsurgical infection.

hence, infections should be kept at a minimum in treatment of fractures

Segmental Fractures= in this type of fractures there is a maximum risk of damage to the intraosseous vessels resulting in poor union.

Distraction of fracture fragments =Excessive weight use during skin or skeletal traction causes this.

Soft-tissue interposition= Soft tissues, such as periosteum, muscle, tendon, nerves, vessels, etc., interpose between the fracture fragments.

it obstructs the growth of internal callus and thus jeopardizes union

ill advised open fractures = open reduction damages favorable factors for fractures union like fracture hematoma.

periosteal stripping and intramedullary reaming disturbs the vascular supply. all these are detrimental to fracture healing

Insecure and inadequate fixation


there are two classifications which are widely adopted:

PALEY’S CLASSIFICATION : this classification takes into account of bone loss and includes two varieties :

  1. type A less than 1cm bone loss
  2. type B greater than 1cm bone loss.

MULLER AND WEBER’S CLASSIFICATION : this classification takes into account the amount of callus at the fracture site

Clinical features

usually the individual gives history of trauma resulting in fractures, multiple injuries, multisystem or head injuries.

there could be history of open fractures, delay, or improper or inadequate treatment.

it should be noted that in nonunion the history is of a longer duration

Symptoms : the acute symptoms seen in fresh fractures are conspicuously absent in nonunion.

there is usually history of no pain or minimal pain. there could be presence of a deformity or loss of function.

Signs: the important clinical signs are painless abnormal mobility, no crepitus, shortening, scars, and sinuses, deformity, wasting of limb muscles, etc


Radiograph of the part in AP and lateral views shows:

  1. Gap between the fracture fragments.
  2. Sclerotic and rounded fragments seen
  3. The amount of callus formed could be less
  4. Decreased density of bone is due to osteoporosis.

Radiography helps classify nonunion depending upon the amount of callus

Principles of Management

nonunion is an absolute indication for surgery and it requires open reduction, rigid internal fixation and bone grafting

there is no role of conservative treatment

Other methods of treatment include electrical stimulation, interlocking nails, and Ilizarov’s technique.

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