The Impact of the Placement of the L5 Vertebra in Relation to the Intercrest Line on the Level of Disc Herniation.

AIM: To determine whether there is a correlation between a deeply seated L5 vertebra in relation to the intercrest line (ICL) and the level of degeneration of lumbar discs. MATERIAL AND METHODS: The study included 152 patients who underwent surgery for lumbar disc herniation. After analyzing the radiographs, the patients were separated into two groups. Group 1 patients had an ICL that passed through the L4 corpus, and Group 2 patients had an ICL that passed through the L4-5 disc distance or the L5 vertebra. Group 1 patients were classified as having a deeply seated L5 vertebra, while Group 2 patients were classified as not having a deeply seated L5 vertebra. RESULTS: The study found that male patients had a significantly higher incidence of a deeply seated L5 vertebra compared to female patients (p=0.003). Patients who underwent surgery at the L4?5 level exhibited disc heights that were notably higher than those who underwent surgery at the L5-S1 level. In Group 1, 68% of the patients had surgery at the L4-5 level, compared to only 41.7% in Group 2 (p=0.009). CONCLUSION: When investigating the effects of the position of the L5 vertebra in relation to the ICL at the L4-5 and L5-S1 disc levels, the study found that having a deeply seated L5 vertebra protected against L5-S1 disc herniation and that L4-5 disc herniation was more common in these patients. This is believed to be due to the L5?S1 segment being less mobile when the L5 vertebra is deeply seated.

Dynamic Lateral Semisitting Position for Supracerebellar Approaches: Technical Note and Case Series.

BACKGROUND: It has always been a matter of debate which position is ideal for the supracerebellar approach. The risk of venous air embolism (VAE) is the major deterrent for surgeons and anesthesiologists, despite the fact that sitting and semisitting positions are commonly used in these operations. OBJECTIVE: To demonstrate a reduction on the risk of VAE and tension pneumocephalus throughout the operation period while taking advantages of the semisitting position. METHODS: In this study, 11 patients with various diagnoses were operated in our department using the supracerebellar approach in the dynamic lateral semisitting position. We used end-tidal carbon dioxide and arterial blood pressure monitoring to detect venous air embolism. RESULTS: None of the patients had clinically significant VAE in this study. No tension pneumocephalus or major complications were observed. All the patients were extubated safely after surgery. CONCLUSION: The ideal position, with which to apply the supracerebellar approach, is still a challenge. In our study, we presented an alternative position that has advantages of the sitting and semisitting positions with a lower risk of venous air embolism.

The Trans-Spinous Crosslink Increases the Pull-Out Strength of the Pedicle Screw Instrumentation.

AIM: To evaluate whether adding an extra anchoring point to the construct by passing the crosslink through a hole in the spinous process (trans-spinous crosslink technique), may prevent screw loosening by increasing the pull-out strength. MATERIAL AND METHODS: Twenty-four fresh-frozen single lumbar sheep vertebrae were instrumented with pedicle screws bilaterally, and they are connected to each other with a crosslink. All vertebrae were assigned randomly to either the experiment (trans-spinous crosslink) group or the control group. In the experiment group, the crosslink was passed through a hole within the spinous process. In the control group, the posterior part of the hole was removed. The pull-out force of the construct was determined using a mechanical testing machine. RESULTS: The mean pull-out forces of the experiment group and the control group were 1949 ± 361.55 N and 1338.57 ± 220.26 N, respectively. The pull-out force of the experiment group was significantly higher than those of the control group with 99.9% confidence (p < 0.001). CONCLUSION: The pedicle screws rigidly anchor the internal fixation devices to the vertebral colon. In classical construct design, pedicle screws share the load. Adding extra anchoring points decreases screw share and may prevent construct pull-out. This study shows that the trans-spinous crosslink can serve as an anchoring point and increases the construct pull-out strength.