|dc.description.abstract||Background. Operative stabilisation of paediatric supracondylar elbow fractures is most
commonly achieved through the use of percutaneous Kirschner wires. These implants are
inert, cheap and simple to use. However, the requirement for removal and the possibility of
pin site infection provides opportunity for the development of new techniques that eliminate
these drawbacks. Bioabsorbable pins that remain in situ and allow definitive closure of skin
at the time of surgery could provide such advantages. However, their ability to maintain
fracture reduction and their effect on the growth plate has not been adequately evaluated.
Hypotheses. The Acumed® Biotrak Helical Nail (a bioabsorbable fixation implant) has
comparable strength to Kirschner wires and does not result in significant disruption of the
growth plate or subsequent growth.
Studies. Three complementary studies were performed. (1) A retrospective cohort analysis
was performed to establish the prevalence of complications related to Kirschner wire fixation
of paediatric supracondylar elbow fractures. (2) A saw-bone model was designed to compare
the mechanical performance of the Helical Nail and Kirschner wires. (3) An ovine model
was designed to assess the in vivo effects of the Helical Nail on limb growth and physeal
morphology. The surgical practicalities of the device and its potential for use in the
paediatric setting were evaluated. The primary outcome was femoral length six months after
Helical Nail insertion. Micro-CT evaluation of growth plate thickness, percentage disruption
and bony infiltration was undertaken – the first time this technique has been used in a large
animal study. Traditional histopathological techniques complimented the Micro-CT analysis
and offered comment on the microscopic appearance of the growth plate immediately
adjacent to the bioabsorbable nails.
Results. The infection rate within a large tertiary referral centre was 9.6%, which was
marginally higher than previous cohort studies. Mechanical testing demonstrated that the
Helical Nail had comparable strength in rotation, but inferior resistance to posterior
translation, when compared to Kirschner wires. In the ovine model, the Helical Nail
disrupted 3.4% of the physis. The nails had no effect on femoral growth during the six month
study period. Micro-CT analysis of both the helical nail and Kirschner wire groups
demonstrated multiple bony bridges, with two cases of physeal tethering in the Helical Nail
group. There was no difference in physeal thickness or bony infiltration of the physis.
Histopathology did not reveal any significant inflammatory or foreign body reaction adjacent
to the nails.
Conclusion. The Helical Nail demonstrated a number of encouraging attributes which
indicate its potential. However, in its current state the device is not suitable for use in the
stabilisation of paediatric supracondylar elbow fractures.||en