The aim of this study was to compare the peak pull-out force
(PPF) of pedicle-lengthening screws (PLS) and traditional pedicle
screws (TPS) using instant and cyclic fatigue testing. A total of 60 lumbar vertebrae were divided into six groups:
PLS submitted to instant pull-out and fatigue-resistance testing
(groups A1 and A2, respectively), TPS submitted to instant pull-out
and fatigue-resistance testing (groups B1 and B2, respectively)
and PLS augmented with 2 ml polymethylmethacrylate, submitted to
instant pull-out and fatigue-resistance testing (groups C1 and C2,
respectively). The PPF and normalized PPF (PPFn) for bone mineral density
(BMD) were compared within and between all groups.Aims
Materials and Methods
We evaluated the impact of lumbar instrumented
circumferential fusion on the development of adjacent level vertebral
compression fractures (VCFs). Instrumented posterior lumbar interbody
fusion (PLIF) has become a popular procedure for degenerative lumbar
spine disease. The immediate rigidity produced by PLIF may cause
more stress and lead to greater risk of adjacent VCFs. However,
few studies have investigated the relationship between PLIF and
the development of subsequent adjacent level VCFs. Between January 2005 and December 2009, a total of 1936 patients
were enrolled. Of these 224 patients had a new VCF and the incidence
was statistically analysed with other covariants. In total 150 (11.1%)
of 1348 patients developed new VCFs with PLIF, with 108 (72%) cases
at adjacent segment. Of 588 patients, 74 (12.5%) developed new subsequent
VCFs with conventional posterolateral fusion (PLF), with 37 (50%)
patients at an adjacent level. Short-segment fusion, female and
age older than 65 years also increased the development of new adjacent
VCFs in patients undergoing PLIF. In the osteoporotic patient, more
rigid fusion and a higher stress gradient after PLIF will cause
a higher adjacent VCF rate. Cite this article:
Loosening of pedicle screws is a major complication of posterior
spinal stabilisation, especially in the osteoporotic spine. Our
aim was to evaluate the effect of cement augmentation compared with
extended dorsal instrumentation on the stability of posterior spinal
fixation. A total of 12 osteoporotic human cadaveric spines (T11-L3) were
randomised by bone mineral density into two groups and instrumented
with pedicle screws: group I (SHORT) separated T12 or L2 and group
II (EXTENDED) specimen consisting of T11/12 to L2/3. Screws were
augmented with cement unilaterally in each vertebra. Fatigue testing
was performed using a cranial-caudal sinusoidal, cyclic (1.0 Hz)
load with stepwise increasing peak force.Aims
Materials and Methods
Ventral screw osteosynthesis is a common surgical
method for treating fractures of the odontoid peg, but there is still
no consensus about the number and diameter of the screws to be used.
The purpose of this study was to develop a more accurate measurement
technique for the morphometry of the odontoid peg (dens axis) and
to provide a recommendation for ventral screw osteosynthesis. Images of the cervical spine of 44 Caucasian patients, taken
with a 64-line CT scanner, were evaluated using the measuring software
MIMICS. All measurements were performed by two independent observers.
Intraclass correlation coefficients were used to measure inter-rater
variability. The mean length of the odontoid peg was 39.76 mm ( The cross-section of the odontoid peg is not circular but slightly
elliptical, with a 10% greater diameter in the sagittal plane. In
the majority of cases (70.5%) the odontoid peg offers enough room
for two 3.5 mm cannulated cortical screws. Cite this article:
