In the last few decades pedicle screw placement has brought in a genuine scientific revolution in the surgical care of spinal disorders. The technique has dramatically improved the outcomes of spinal reconstruction requiring spinal fusion. Short segment surgical treatments based on the use of pedicle screws for the treatment of neoplastic, developmental, congenital, traumatic and degenerative conditions have been proved to be practical, safe and effective. The reported incidence of nerve root damage after the use of pedicle screws ranges from 2% to 32%. The utilization of computerized image-guided technology in lumbosacral spinal fusion surgery offers increased accuracy of pedicle screw placement. We decided to review our x-rays of pedicle screw placement, and to assess the percentage misplacement of pedicle screws inserted without computer assistance. This is a retrospective study and our results are compared with those in the literature. 80 Post operative radiographs of patients operated on for trauma and degenerative conditions of the thoracolumbar spine were studied. Initially these were looked at independently by 2 orthopaedic spinal surgeons and a radiologist, and subsequently all x-rays were reviewed together to see where consensus could be reached where there was any disagreement. The percentage of misplaced screws inserted under fluoroscopy was obtained, and compared to the percentage of misplaced screws inserted under image guidance reported in the literature. Our study shows that there is no significant difference between the 2 techniques.
The lumbar spine consists of a mobile segment of 5 vertebrae, which are located between the relatively immobile segments of the thoracic and sacral segments. The bodies are wider and have shorter and heavier pedicles, and the transverse processes project somewhat more laterally and ventrally than other spinal segments. The laminae are shorter vertically than are the bodies and are bridged by strong ligaments. The spinous processes are broader and stronger than are those in the thoracic and cervical spine. Internal fixation as an adjunct to spinal fusion has become increasingly popular in recent years. Stainless steel or titanium plates or rods are longitudinally anchored to the spine by hooks or pedicle screws. Powerful forces can be applied to the spine through these implants to correct deformity. Implants provide immediate rigid spinal immobilization, which allows for early patient mobilization, and provides a more optimal environment for bone graft incorporation. Numerous clinical and experimental studies demonstrate higher fusion rates in patients with rigid internal fixation than in controls without instrumentation. Although various implants are available, pedicle fixation systems are the most commonly used implant type in the lumbosacral spine. The large size of the lumbar pedicles minimizes the number of instrumented motion segments required to achieve adequate stabilization. Many authors have reported loss of postoperative deformity correction after transpedicular screw fixation, ranging from 2.5 degrees to 7.1 degrees. The general preference is to stabilize the fractured vertebra by fusing one level above and one level below. With this technique, the rate of loss of correction is high. At our institution, we routinely stabilize the unstable thoracolumbar fractures by fusing one level above and one level below. In addition, we put screws into the pedicle(s) of fractured vertebrae. The reason for this is the following:
To correct the deformed body of the fractured vertebra for better load sharing. To make use of the pedicles of the fractured vertebra for superior rotatory stabilization. To avoid the need for the inclusion of additional levels, thereby preserving motion segments. To avoid the need for possible anterior spinal fusion and instrumentation. To obtain a better correction of a kyphotic deformity. Plain radiographs were analysed post operatively and compared for reduction of the fracture fragments and correction of kyphotic deformity to pre-operative films. 74 Patients were admitted with thoracolumbar spine fractures to our hospital. 48 Patients were surgically treated, and 34 patients were available for follow up. We found that inserting the pedicle screws into the fractured vertebra provided good stabilization for very unstable fractures. No loss of correction was seen in the follow up x-rays. We conclude that including the fractured vertebra into the fracture fixation device not only provides better fracture reduction, but also gives improved rotatory stability.
