We performed biomechanical comparison of a xenograft bone plate-screw (XBPS) system for achieving cadaveric lumbar transpedicular stabilization (TS) in dogs. Twenty dogs' cadaveric L2-4 lumbar specimens were harvested and their muscles were removed, but the discs and ligaments were left intact. These specimens were separated to four groups: the L2-4 intact group as control (group I, n = 5), the L3 laminectomy and bilateral facetectomy group (LBF) (group II, n = 5), the LBF plus TS with metal plate-screw group (group III, n = 5) and the LBF plus TS with XBPS group (group IV, n = 5). Five kinds of biomechanical tests were applied to the specimens: flexion, extension, left-right bending and rotation. The averages of the 16 stiffness values were calculated and then these were statistically analyzed. The statistical results show that the XBPS system contributes spinal stability and this system can be a good choice for achieving TS.
Animals ; Biomechanics ; Bone Plates/*veterinary ; Bone Screws/*veterinary ; Cadaver ; Dogs ; Lumbar Vertebrae/physiology/*surgery ; Range of Motion, Articular/physiology ; Spinal Fusion/instrumentation/*methods ; Transplantation, Heterologous/instrumentation/*methods

STUDY DESIGN: Retrospective analysis of adolescent idiopathic scoliosis. PURPOSE: This study aimed to investigate the influence of distinct distal fusion levels on spinopelvic parameters in patients with adolescent idiopathic scoliosis (AIS) who underwent posterior instrumentation and fusion surgery. OVERVIEW OF LITERATURE: The distal fusion level selection in treatment of AIS is the one of milestone to effect on surgical outcome. Most of the paper focused on the coronal deformity correction and balance. The literature have lack of knowledge about spinopelvic changing after surgical treatment and the relation with distal fusion level. We evaluate the spinopelvic and pelvic parameter alteration after fusion surgery in treatment of AIS. METHODS: A total of 100 patients with AIS (88 females and 12 males) were retrospectively reviewed. Patients were assigned into the following three groups according to the distal fusion level: lumbar 2 (L2), lumbar 3 (L3), and lumbar 4 (L4). Using a lateral plane radiograph of the whole spine, spinopelvic angular parameters such as thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) were radiologically assessed. RESULTS: The mean age was 15±2.4 years, and the mean follow-up period was 24.27±11.69 months. Regarding the lowest instrumented vertebra, patients were categorized as follows: 30 patients in L2 (group 1), 40 patients in L3 (group 2), and 30 patients in L4 (group 3). TK decreased from 36.60±13.30 degrees preoperatively to 26.00±7.3 degrees postoperatively in each group (p=0.001). LL decreased from 52.8±9.4 degrees preoperatively to 44.30±7.50 degrees postoperatively (p=0.001). Although PI showed no difference preoperatively among the groups, it was statistically higher postoperatively in group 3 than in the other groups (p < 0.05). In addition, in group 2, PI decreased from 50.60±8.74 degrees preoperatively to 48.00±6.84 degrees postoperatively (p=0.027). SS decreased from 35.20±6.40 degrees preoperatively to 33.40±5.80 degrees postoperatively (p=0.08, p>0.05). However, mean SS was significantly higher in group 3 (p=0.042, p < 0.05). PT decreased from 15.50±7.90 degrees preoperatively to 15.2±7.10 degrees postoperatively. The positive relationship (28.5%) between LL and PI measurements was statistically significant (r=0.285; p=0.004, p < 0.01). Furthermore, the positive relationship (36.5%) between LL and SS measurements was statistically significant (r=0.365; p=0.001, p < 0.01). CONCLUSIONS: When the distal instrumentation level in AIS surgery is below L3, a significant change in PT and SS (pelvic parameters) is anticipated.
Adolescent ; Animals ; Congenital Abnormalities ; Female ; Follow-Up Studies ; Humans ; Incidence ; Kyphosis ; Lordosis ; Retrospective Studies ; Scoliosis ; Spine