Biomechanical effects of different instrumented segments and trunk shifts on distal adjacent segments after congenital scoliosis posterior hemivertebrectomy: Preliminary results of a single case.

Objective: The present study aims to discuss the biomechanical effects of the sagittal vertical axis and different instrumented segments on distal adjacent segments after congenital scoliosis posterior hemivertebrectomy. Method: A case of congenital scoliosis caused by hemivertebra was selected for the reconstruction of the preoperative and postoperative 3D computed tomography data of the full spine. A finite element model of different fusion lengths and postoperative trunk shift (TS) values was established using the finite element method to compare the biomechanical effects of different models on the distal adjacent segment. Result: In the L1-L3 and T12-L1-L3-L4 fusion modes, the horizontal shift of the 1st vertebra below the lowest instrumented vertebra (LIV) increased with the trunk shift (TS) expansion after operation, and the imbalance between the left and right vertical stress of the 1st intervertebral disc below the LIV increased. With the decrease in fused segments in cases of TS = 10 mm and TS = 5 mm, the 1st vertebra below the LIV was subjected to a greater unbalanced force in the horizontal direction, and the 1st intervertebral disc below the LIV was subjected to a smaller imbalance between the left and right vertical stress after operation. Conclusion: When treating congenital scoliosis with hemivertebrectomy and pedicle screw fixation, fused segments can be properly extended and the postoperative TS shortened with a view of reducing the imbalance between the left and right stress of the 1st intervertebral disc below the LIV as well as the horizontal shift of the 1st vertebra below the LIV.

[Treatment analysis of complex Schatzker type â £ tibial plateau fractures].

OBJECTIVE: To explore treatment strategy for complex Schatzker Ⅳ tibial plateau fracture. METHODS: Forty-one patients with complex Schatzker type Ⅳ tibial plateau fractures were treated from January 2016 to January 2021, including 28 males and 13 females, aged from 19 to 65 years old with an average of (35.3±19.8) years old. Individualized treatment plan was developed according to preoperative imaging characteristics, medial surgical approach was mainly combined with other auxiliary incisions. Posteromedial inverted L approach was used in 18 patients, posteromedial approach and anterolateral extended approach in 19 patients, and posteromedial approach with anterolateral and lateral condylar osteotomy in 4 patients. Articular surface and facture healing were observed, range of knee joint motion was measured at 12 months after opertaion, and function of knee joint was evaluated by Lysholm scoring system. RESULTS: Forty-one patients were followed up for 12 to 26 months with an average of (13.3±6.8) months. Twenty-nine patients and 10 patients were obtained complete fracture healing at 6 and 12 months after operation respectively, and fracture healing time was 4 to 13 months with an average of (5.0±3.7) months. Two patients occurred posterior medial internal fixation failure and varus deformity of knee joint, and the fracture healed and varus deformity was corrected after the second operation. Range of knee joint motion was (118±29) °, and Lysholm score was(83.0±16.0) points. CONCLUSION: Individualized treatment should be reasonably selected for complex Schatzker Ⅳ tibial plateau fractures, the characteristics of lateral plateau fractures are an important reference for selecting surgical approaches, the effective fixation of posteromedial bone blocks should be pay full attention, and the overall treatment results are satisfied.

An Analysis of the Risk Factors for Adding-on Phenomena After Posterior Hemivertebral Resection and Pedicle Screw Fixation for the Treatment of Congenital Scoliosis Caused by Hemivertebral Malformation.

Objective: To retrospectively analyze the risk factors for adding-on phenomena (AOP) after posterior hemivertebral resection (PHR) and pedicle screw fixation for the treatment of congenital scoliosis (CS) caused by hemivertebral (HV) malformation. Methods: Patients with CS who underwent surgery and were followed up for more than five years were included in this study. The d general data, such as gender, age, HV segment, Risser sign, and triangular cartilage, postoperative complications, and imaging data at different periods, including the standard anteroposterior and lateral x-rays of the total spine were collected. Results: In total, 58 patients were included in this study, of which 10 experienced AOP and 48 did not. The results of the single-factor analysis showed that there were statistically significant differences between the patients with AOP and those without in terms of the HV direction, lowest instrumented vertebra (LIV)-upper instrumented vertebra (UIV) (P < 0.05), and postoperative trunk shift (P < 0.05). The results of the logistic regression analysis showed that the HV direction and the postoperative trunk displacement distance were the main risk factors for postoperative AOP. The area under the receiver operating characteristic curve was 0.842 (P < 0.001). The best cut-off value of the adding-on index as an indicator of the occurrence of AOP after surgery was 0.67. When the adding-on index was >0.67, the incidence of postoperative AOP was 90.0%, and the non-occurrence rate was 22.9%. Conclusion: PHR and pedicle screw fixation is an effective way to treat HV malformation in CS. The HV direction, LIV-UIV, and postoperative TS are risk factors for AOP in patients with CS treated with PHR and pedicle screw fixation. The adding-on index has a high degree of accuracy for the prediction of the occurrence of AOP after PHR and pedicle screw fixation.