Page 180 - ASOP ROT Study Guide

Early mobilization will discourage the development of:
♦ osteoporosis - the "thinning" of bone caused by disease
♦ renal stone formation - caused by calcium from the thinning bone
♦ stiffness - caused by disease of joints
♦ muscle wasting - caused by muscle disuse
♦ skin sores - caused by pressure of the plaster cast

10.7 Delayed and Non-union

About two percent of all fractures go on to non-union and a few more will be delayed as shown in
Figure 33. If left to heal naturally, upper limb fractures heal in six weeks or so and lower limb
fractures in twelve. This rule of thumb is useful but must not be too strictly adhered to and will be
modified depending on the degree of violence involved and how the fracture was treated. It is
worth noting that although growing children do heal faster than adults, once growth ceases the rate
of union is not age dependent.

Non-union is commonest in the tibia but may occur at any site. The tibia is of course commonly
injured, but other factors contribute to non-union, including its rather exposed site under the skin
with little surrounding muscle and soft tissue. Why fractures go on to nonunion is not fully
understood but some factors which are known to cause it may be listed:
♦ Excess movement
♦ Too little movement - a result of rigid internal fixation
♦ Soft tissue interposition - soft tissue between the bone ends
♦ Poor blood supply
♦ Infection
♦ Excessive traction, or splintage of bones too far apart
♦ Intact adjacent bone - e.g. tibia and fibula

Non-union may be said to occur when the injured person and/or the surgeon feels that healing has
taken too long. Bearing in mind our rules of thumb for fracture union time, we may say that non-
union is established at twenty weeks in the lower limb and ten in the upper. These are arbitrary
but practical figures.

Delayed union is even less specific and it is really a period between expected union and accepted
non union when the decision to do something is contemplated. The causes are the same as for
non-union.

http://jortho.org/2005/2/1/e2/index.htm

Treatment for non union relies on removing any underlying cause, and then stimulating
union. Stabilizing the fracture sufficiently and then adding a bone graft seems to stimulate union
but how this works remains an enigma. The bone used for a graft is usually autologous
(taken from the bone, usually the pelvis, of the same individual) and is placed next to the fracture.
It appears to be able to "switch on" the hitherto deficient healing mechanism.