Summary by Jan Egil Brattgjerd:
A definite
biomechanical impact was detected with increased multi-directional stability
without adverse effects in comparison with other relevant conventional fixation
methods in a comprehensive ex vivo evaluation. As intended during implant
design development, the physical effect justified introducing the novel implant
into the clinics.
The
profound impact on torsional stability, but also the enhanced bending and
compressive stability can be explained by moment of inertia considerations of
single beam prisms, where a larger footprint of the bone-implant construct
describes the higher resistance to loading. This corresponds with the mechanism
of action by interlocked pins to improve load distribution by equal
transmission amongst pins from fragile cancellous bone medially in the femoral
head to solid cortical bone laterally in the trochanteric area.
The
modestly improved compressive stability from dynamic testing may be indicative
of the role of the interlocking plate to allow for a stabilising controlled
intermediate compression by impaction of the fragments during loading with such
an implant.
However,
whether the improved gross stability is sufficient to enhance healing
conditions or affect failure patterns in vivo, will be the topic of forthcoming
clinical trials. So far, the results are promising and the interlocked pins
must be considered a favourable development of the pin concept.
Digital public defence: Jan Egil
Brattgjerd - Institute of Clinical Medicine (uio.no)
OUH - Orthopaedic Surgery
(ous-research.no)