Intramedullary nailing is considered the gold standard in the treatment of long bone non-unions of the lower limb [
3]. To the best of our knowledge, only one study reported results of Fixion nail in the treatment of long bone non-unions [
13]. In the present paper combined treatment of long bone non-unions by expandable self locking nails and PRP gel is evaluated. The rate of healed non-unions and the mean time to union were similar to those reported in previous studies carried out with different nails and without PRP gel [
14‐
16]. Kempf et al., using their nail, noted 92.6% and 94.8% of consolidation in femoral and tibial non-unions, respectively [
17]. The average time to consolidation was shorter than that obtained in our series but a 7.5% infection rate and significant shortening of femur and tibia were reported [
17]. The absence of interlocking screws with the related skin incisions and the short operative time could explain the lack of infection observed with expandable self locking nails. Moreover, the maintenance of limb length found in the present study could lie on the biomechanical characteristics of nail. Indeed, once the Fixion nail has expanded, it completely obliterates the medullary canal adapting to the canal’s shape [
18]. The nail fits into the isthmus of the shaft and therefore any axial and sideways displacement is prevented [
19]. The large frictional contact surface between nail and bone results in a self-locking effect without the cortex weakening effect of drill holes. Forces acting on the outside of the bone are distributed over a large area and are not concentrated on small, localized areas, as when locking screws are used [
20]. Mechanical testing of humeral Fixion nail showed an average strength in the 4-point-bending test of 43.15 ± 3.0 Nm and an average torsional stiffness of 2.78 ± 0.27 Nm
2 [
20], thus overcoming the results recorded for several conventional locking nails [
20]. The lack of interlocking screws allowed short operative and fluoroscopy times; fluoroscopy was mainly used throughout the expansion phase, because of the concern to over expand the medullary canal. Daccarett et al., using the Fixion nail, obtained a 96% rate of healing with short time to consolidation (13, 15, and 16 weeks treating pseudoarthrosis of femur, tibia, and humerus, respectively). However, a more heterogeneous group of patients was enrolled in this study consisting of both hypertrophic and atrophic non-unions [
13].
In the present study the medullary canal was reamed up to two millimeters less than maximum diameter the nail reaches once its expansion is completed. In spite of several studies dealing with reaming procedure during intramedullary nailing of open or closed fracture [
21‐
25], few data concerns reaming of medullary canal for pseudoarthrosis of bone. The choice of reaming the canal allowed the insertion of a nail with larger diameter, thus providing better stability. Moreover, the reaming produces an internal bone graft locally which appears to promote the healing of non-unions [
26]. The cortical circulation and related periosteal callus formation have shown to be increased after reaming procedure [
27]. The lack of a control group prevented us from comparing reaming and unreaming techniques. The absence of homogeneous group of patients treated with expandable intramedullary nailing alone did not allow to demonstrate the usefulness of PRP supplementation in the treatment of non-unions.
In the treatment of long bone non-unions, we obtained results similar to previous studies but with less complications using expandable intramedullary nails and PRP supplementation. Future controlled studies with larger sample size and more homogeneous study groups are warranted to investigate the single contribution of PRP gel and Fixion nail in the non-union treatment.