Radiographic Changes of Adjacent Upper Segment Performed Short Segmental Lumbosacral Fusion: Does Total Laminectomy Influence Adjacent Upper Segmental Instability? / 대한척추외과학회지

STUDY DESIGN: Retrospective study. OBJECTIVES: The purpose of this study was to compare factors that influence degenerative changes in patients undergoing total laminectomy and patients undergoing partial laminectomy. SUMMARY OF LITERATURE REVIEW: Lumbar or lumbosacral fusion with total or partial laminectomy may result in adjacent segment problems of the upper segment. However, the differences between the two procedures that may influence adjacent segment instability are still controversial. MATERIALS AND METHODS: We evaluated 95 patients, followed up for at least 2 years, who had been treated with short level (at most 2 levels) posterior lumbar interbody fusion with pedicle fixation, secondary to spinal stenosis. Treatment procedures included total laminectomy (42 cases) and partial laminectomy (53 cases). We analyzed the preoperative status of the intervertebral discs (Thompson grade), difference of disc height, and difference between preoperative segmental sagittal angle and last follow-up sagittal angle. We excluded cases that required revision secondary to infection, nonunion, or hematoma formation. However, we included cases that required revision due to adjacent segmental problems during the follow-up period. RESULTS: The mean age of the patients treated with total laminectomy was 59.0+/-10.9 years, and of the patients treated with partial laminectomy was 58.8+/-10.2 years. The preoperative Thompson grade showed no statistical difference. The difference in disc height and segmental sagittal angle between the preoperative and last follow-up examinations showed no statistical difference between the two groups. CONCLUSIONS: There was no significant difference in the radiographic or clinical outcomes based on removal or preservation of posterior structures. Nevertheless, we need further follow-up to evaluate adjacent segment degeneration.

Evaluation of Rotational Displacement of the Posterior Facet on the Sagittal Plane in Computed Tomographic Images of Calcaneal Fractures

PURPOSE: To find out whether or not the computed tomographic (CT) classification systems of the calcaneal fracture are efficient in illuminating displaced posterior facet fragment and the degree of displacement can be evaluated by analyzing serial CT images. MATERIALS AND METHODS: Seventy-seven hundred calcaneal fractures were classified by CT classification systems including Sanders classification, and the sagittal rotation angle of the posteior facet fragment was measured on the plain lateral radiograph. Among the serial axial CT images, a number of images with the cortical bone embedded in the cancellous portion were recorded and any significant relationship between each data were evaluated. RESULTS: The conventional CT classification systems are rather insufficient in illuminating the extent of sagittal rotatory displacement. However, the number of CT images in which the cortical radiodensity was observed showed a significantly related with the degree of displacement. CONCLUSION: The conventional CT classification of the calcaneal fractures is unsatisfactory in expressing the degree of sagittal rotatory displacement of the posterior facet fragment; this problem may be alleviated by observing the number of axial CT images in which cortical radiodensity was revealed within the calcaneal body.

The Posterior Fixation of Thoracolumbar Burst Fracture using Pedicle Screws and Caudal Offset Sublaminar Hooks / 대한척추외과학회지

STUDY DESIGN: A retrospective study. OBJECTIVES: We analyzed the clinical results of thoracolumbar burst fractures, managed by posterior fixation of 2 segments above and 1 segment below, using an offset sublaminar hook. SUMMARY OF LITERATURE REVIEW: Mono-segment fixation above and below the injured vertebra, using posterior pedicle screw fixation, has the benefit of saving the uninjured mobile lumbar segment in thoracolumbar junction burst fracture patients. However, in a severely comminuted vertebral body, mono-segment fixation may not prevent loss of correction and metal failure. Options for such cases are additional anterior column support or long segment fixation, including 2 segments above and 1 below the injured vertebra. Instead of fixing 2 segments below the fracture level, fixation of one segment below, using the offset sublaminar hook, can save the uninjured segment, especially in the upper lumbar segment, with greater fixation strength than mono-segmental screws only. MATERIAL AND METHOD: The study included eleven patients with a thoracolumbar junction burst fracture, which underwent posterior fixation using pedicle screws in 2 segments above and 1 segment below, aided by an offset sublaminar hook. The mean follow-up period was 30.7 months (range, 24 to 58 months). Radiographs taken at follow-up were evaluated for implant loosening, correction loss, change in pedicle screw angle, and loss of vertebral height, adjacent segment instability and junctional degenerative change. The clinical results were collected in out-patient department. RESULTS: No implant loosening was noted. No case showed adjacent instability, acceleration of junctional degenerative change at the lower end of lumbar segment or hook dislodgement. Also, there were no junctional area related symptoms. CONCLUSION: For posterior surgery of thoracolumbar burst fractures, this construct, fixing 2 segments above and 1 segment below injured vertebra, aided by an offset sublaminar hook, was satisfactory in maintaining fracture reduction, and showed no instability or acceleration of degeneration on adjacent segnents.