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
Previous classification systems of failure of
limb salvage focused primarily on endoprosthetic failures and lacked sufficient
depth for the effective study of the causes of failure. In order
to address these inadequacies, the International Society of Limb
Salvage (ISOLS) formed a committee to recommend revisions of the
previous systems. The purpose of this study was to report on their
recommendations. The modifications were prepared using an earlier,
evidence-based model with subclassification based on the existing
medical literature. Subclassification for all five primary types
of failure of limb salvage following endoprosthetic reconstruction
were formulated and a complementary system was derived for the failure
of biological reconstruction. An additional classification of failure
in paediatric patients was also described. Limb salvage surgery presents a complex array of potential mechanisms
of failure, and a complete and precise classification of types of
failure is required. Earlier classification systems lacked specificity,
and the evidence-based system outlined here is designed to correct
these weaknesses and to provide a means of reporting failures of
limb salvage in order to allow the interpretation of outcome following
reconstructive surgery. Cite this article:
The purpose of this study was to evaluate and
compare the effect of short segment pedicle screw instrumentation and
an intermediate screw (SSPI+IS) on the radiological outcome of type
A thoracolumbar fractures, as judged by the load-sharing classification,
percentage canal area reduction and remodelling. We retrospectively evaluated 39 patients who had undergone hyperlordotic
SSPI+IS for an AO-Magerl Type-A thoracolumbar fracture. Their mean
age was 35.1 (16 to 60) and the mean follow-up was 22.9 months (12
to 36). There were 26 men and 13 women in the study group. In total,
18 patients had a load-sharing classification score of seven and
21 a score of six. All radiographs and CT scans were evaluated for
sagittal index, anterior body height compression (%ABC), spinal
canal area and encroachment. There were no significant differences
between the low and high score groups with respect to age, duration
of follow-up, pre-operative sagittal index or pre-operative anterior
body height compression (p = 0.217, 0.104, 0.104, and 0.109 respectively).
The mean pre-operative sagittal index was 19.6° (12° to 28°) which
was corrected to -1.8° (-5° to 3°) post-operatively and 2.4° (0°
to 8°) at final follow-up (p = 0.835 for sagittal deformity). No
patient needed revision for loss of correction or failure of instrumentation. Hyperlordotic reduction and short segment pedicle screw instrumentation
and an intermediate screw is a safe and effective method of treating
burst fractures of the thoracolumbar spine. It gives excellent radiological
results with a very low rate of failure regardless of whether the
fractures have a high or low load-sharing classification score. Cite this article
