Page 220 - Advances in Biomechanics and Tissue Regeneration

216 11. ANALYSIS OF THE BIOMECHANICAL BEHAVIOR OF INTRAMEDULLARY NAILING

FIG. 11.2 Location of femoral fractures according to Wiss’ classification.

(Fig. 11.2). In addition, diaphyseal fractures, by their degree of comminution, have been classified by Winquist and
Hansen [5] (Fig. 11.3), type IV being the most difficult to treat and with increased complications and sequelae because
of their instability.
The treatment of these fractures, always surgical, since the 1980s has been done by using intramedullary nails [6],
which have many designs. These nails have revolutionized the treatment of diaphyseal femoral fractures, increasing
their indications to the totality of fractures between zones 2 and 5 of Wiss et al. [4], regardless of the type of fracture,
and presenting high values of consolidation with complications and sequelae [7, 8]. Since then in a bid to improve
results, changes in nail design, morphology, material manufacture, screw configuration, and surgical approach have
been introduced. Currently, there are stainless steel or titanium nails; slotted instead of grooved nails; hollow or solid
nails to give greater rigidity; and oblique, transverse, spiral blade screws, etc. These developments have increased the
stability and degree of fixation of the screws in the osteoporotic bone, and with anterograde or retrograde surgical
approaches have increased their indications to more distal fractures. There are also reamed or unreamed nails to min-
imize vascular injury. Reamed nails decrease the risk of pulmonary embolism caused by the increase in intramedullary
pressure produced during reaming [9], although this point continues to be controversial because some authors do not
find a significant difference in pulmonary embolism between reamed and unreamed nails [10]. That is to say, there are
multiple therapeutic possibilities but there is no consensus on the indication of each type of nail or surgical approach to
the different types of fractures.
Regarding the use of clinical findings as an aid in decision making, most are satisfactory, but a definitive conclusion
has not been reached as to therapeutic indication.
Theuseofreamedorunreamednailsisapersistentdiscussion[7].Inameta-analysisperformedin[11],thereisscientific
evidence of the best results of reamed nails against unreamed nails in terms of resurgeries, consolidation delays, and
pseudarthrosis. Similar results with both types of nails and techniques as to breakage of the implant and the production
of distress and respiratory failure [11] have been found. However, complications have been found in the use of reamed
nails, especially in polytraumatized patients with lung injury [7], and because of this unreamed nails have been designed
in an attempt to decrease the respiratory impact of reamed nails. However, this theoretical beneficial effect of unreamed
nails in polytraumatized patients with respiratory involvement is not clinically proven [11]. There is some controversy
because a number of authors have achieved excellent results with few complications using unreamed nails [12].
With respect to retrograde nails, Papadokostakis et al. [13], in a meta-analysis that studied the results of treatment
with a retrograde nail in distal and diaphyseal fractures, found that this type of nail is a treatment option for distal
fractures, but not for diaphyseal fractures because it produces high rates of pain in knees and a greater number of
pseudarthroses and resurgeries than when using anterograde nails. These higher rates of failure in retrograde nails
are due to the use of unreamed nails of small diameter, smaller than the diameter of the femoral medullary canal.
At present, comparative results with anterograde nails are being discussed. Thus retrograde nails are preferable in
patients with difficult access to the greater trochanter, such as obese and pregnant patients, and in patients with ipsi-
lateral fracture of the tibia, which is tactically advisable when treating both fractures with a unique approach [7].

I. BIOMECHANICS