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
Anterior instrumentation is an established method of correcting King I adolescent idiopathic scoliosis. Posterior segmental pedicle screw instrumentation, with its more powerful corrective force over hooks, could offer significant advantages. The purpose of our study is to compare the results of anterior instrumentation versus segmental pedicle screw instrumentation in adolescent idiopathic thoracolumbar scoliosis. A retrospective analysis was conducted on 36 consecutive female patients with adolescent idiopathic thoracolumbar scoliosis who had surgery from December 1997. All had a minimum of two year follow-up. Eleven patients had posterior surgery performed on them. Mean age at surgery was similar between both groups. Length of surgery was significantly shorter in the posterior group (189 minutes versus 272 minutes). Length of hospital stay was shorter in the posterior group (6.2 days versus eight days). Estimated blood loss, duration of analgesia, and ICU stay did not differ significantly between the two groups. No complications were encountered in both groups at latest follow-up. The magnitudes and flexibility of the thoracolumbar curves did not differ significantly between the two groups. The number of levels in the major curve was also similar between the groups. Fusion levels were shorter in the anterior group (mean 4.1 versus 5.0). The percentage correction of scoliosis was similar between the two groups at all stages of follow-up, being 74% at one week post-surgery, 70% at six months post-surgery, 68% at one year post-surgery and latest follow-up in the anterior group; and 71% at one week post-surgery, 67% at six months post-surgery, 68% at one year post-surgery, and 67% at latest follow-up in the posterior group. Thoracolumbar sagittal alignment at T11 to L2 was maintained for both groups throughout the follow-up period. The incidence of proximal junctional kyphosis was higher in the posterior group (p <
0.01). In conclusion, surgical correction of both the frontal and sagittal plane deformity are comparable to anterior
The results of the use of Harrington rods in the treatment of spinal fractures were reviewed. It was found that with burst fractures where the anterior pillar was deficient there was a significant incidence of loss of reduction. Anterior bone supplementation is recommended in these fractures when major loss of height or angulation occurs. Several technical faults were detected which, in most cases, also led to a loss of reduction. Almost all patients with an anatomical reduction were free of pain. There was no correlation between the loss of reduction and the lapse of time before operation, the levels of