To devise a method to quantify and optimize tightness when inserting cortical screws, based on bone characterization and screw geometry. Cortical human cadaveric diaphyseal tibiae screw holes (n = 20) underwent destructive testing to firstly establish the relationship between cortical thickness and experimental stripping torque (Tstr), and secondly to calibrate an equation to predict Tstr. Using the equation’s predictions, 3.5 mm screws were inserted (n = 66) to targeted torques representing 40% to 100% of Tstr, with recording of compression generated during tightening. Once the target torque had been achieved, immediate pullout testing was performed.Aims
Methods
Plating displaced proximal humeral fractures is associated with a high rate of screw perforation. Dynamization of the proximal screws might prevent these complications. The aim of this study was to develop and evaluate a new gliding screw concept for plating proximal humeral fractures biomechanically. Eight pairs of three-part humeral fractures were randomly assigned for pairwise instrumentation using either a prototype gliding plate or a standard PHILOS plate, and four pairs were fixed using the gliding plate with bone cement augmentation of its proximal screws. The specimens were cyclically tested under progressively increasing loading until perforation of a screw. Telescoping of a screw, varus tilting and screw migration were recorded using optical motion tracking.Aims
Methods
The aim of this study was to investigate the effect of a posterior
malleolar fragment (PMF), with <
25% ankle joint surface, on
pressure distribution and joint-stability. There is still little
scientific evidence available to advise on the size of PMF, which
is essential to provide treatment. To date, studies show inconsistent
results and recommendations for surgical treatment date from 1940. A total of 12 cadaveric ankles were assigned to two study groups.
A trimalleolar fracture was created, followed by open reduction
and internal fixation. PMF was fixed in Group I, but not in Group
II. Intra-articular pressure was measured and cyclic loading was
performed.Aims
Materials and Methods
To assess the effect of high tibial and distal femoral osteotomies
(HTO and DFO) on the pressure characteristics of the ankle joint. Varus and valgus malalignment of the knee was simulated in human
cadaver full-length legs. Testing included four measurements: baseline
malalignment, 5° and 10° re-aligning osteotomy, and control baseline
malalignment. For HTO, testing was rerun with the subtalar joint
fixed. In order to represent half body weight, a 300 N force was applied
onto the femoral head. Intra-articular sensors captured ankle pressure.Aims
Materials and Methods
Osteosynthesis of anterior pubic ramus fractures using one large-diameter screw can be challenging in terms of both surgical procedure and fixation stability. Small-fragment screws have the advantage of following the pelvic cortex and being more flexible. The aim of the present study was to biomechanically compare retrograde intramedullary fixation of the superior pubic ramus using either one large- or two small-diameter screws. A total of 12 human cadaveric hemipelvises were analysed in a matched pair study design. Bone mineral density of the specimens was 68 mgHA/cm3 (standard deviation (Objectives
Materials and Methods
End caps are intended to prevent nail migration
(push-out) in elastic stable intramedullary nailing. The aim of
this study was to investigate the force at failure with and without
end caps, and whether different insertion angles of nails and end caps
would alter that force at failure. Simulated oblique fractures of the diaphysis were created in
15 artificial paediatric femurs. Titanium Elastic Nails with end
caps were inserted at angles of 45°, 55° and 65° in five specimens
for each angle to create three study groups. Biomechanical testing
was performed with axial compression until failure. An identical
fracture was created in four small adult cadaveric femurs harvested
from two donors (both female, aged 81 and 85 years, height 149 cm and
156 cm, respectively). All femurs were tested without and subsequently
with end caps inserted at 45°. In the artificial femurs, maximum force was not significantly
different between the three groups (p = 0.613). Push-out force was
significantly higher in the cadaveric specimens with the use of
end caps by an up to sixfold load increase (830 N, standard deviation
(SD) 280 These results indicate that the nail and end cap insertion angle
can be varied within 20° without altering construct stability and
that the risk of elastic stable intramedullary nailing push–out
can be effectively reduced by the use of end caps. Cite this article:
