Methods: This retrospective study enrolled patients with severe lumbar canal stenosis who underwent biportal endoscopic “Z” technique decompression between 2021 and 2023. Patients with any clinical or radiological signs of spondylolisthesis were excluded. The resection of the ligamentum flavum was classified into piecemeal resection, one-piece “butterfly” resection, and the novel variant “two-wings” or two-piece resection. Several demographic and clinical statistical variables were collected, with a specific focus on surgical time, postoperative complications, and clinical outcomes. Results: Ninety lumbar decompression surgeries were performed on 70 patients. The patients were divided into the butterfly group (en bloc) with 27 levels, “two-wings” group with 35 levels, and “piecemeal” group with 28 levels. No significant differences in demographics or clinical variables were found among the three groups. However, piecemeal resection was associated with a higher incidence of dural tears and a longer surgical time (p<0.05). In contrast, en bloc resection, particularly in the two-wing group, demonstrated the best surgical times without an increase in complication rates. Conclusions The results revealed that removing the ligamentum flavum en bloc (either in two pieces or one) may reduce the surgical time and incidence of dural tears. Randomized and prospective studies are warranted to establish definitive conclusions.

Methods: This retrospective study enrolled patients with severe lumbar canal stenosis who underwent biportal endoscopic “Z” technique decompression between 2021 and 2023. Patients with any clinical or radiological signs of spondylolisthesis were excluded. The resection of the ligamentum flavum was classified into piecemeal resection, one-piece “butterfly” resection, and the novel variant “two-wings” or two-piece resection. Several demographic and clinical statistical variables were collected, with a specific focus on surgical time, postoperative complications, and clinical outcomes. Results: Ninety lumbar decompression surgeries were performed on 70 patients. The patients were divided into the butterfly group (en bloc) with 27 levels, “two-wings” group with 35 levels, and “piecemeal” group with 28 levels. No significant differences in demographics or clinical variables were found among the three groups. However, piecemeal resection was associated with a higher incidence of dural tears and a longer surgical time (p<0.05). In contrast, en bloc resection, particularly in the two-wing group, demonstrated the best surgical times without an increase in complication rates. Conclusions The results revealed that removing the ligamentum flavum en bloc (either in two pieces or one) may reduce the surgical time and incidence of dural tears. Randomized and prospective studies are warranted to establish definitive conclusions.

Methods: This retrospective study enrolled patients with severe lumbar canal stenosis who underwent biportal endoscopic “Z” technique decompression between 2021 and 2023. Patients with any clinical or radiological signs of spondylolisthesis were excluded. The resection of the ligamentum flavum was classified into piecemeal resection, one-piece “butterfly” resection, and the novel variant “two-wings” or two-piece resection. Several demographic and clinical statistical variables were collected, with a specific focus on surgical time, postoperative complications, and clinical outcomes. Results: Ninety lumbar decompression surgeries were performed on 70 patients. The patients were divided into the butterfly group (en bloc) with 27 levels, “two-wings” group with 35 levels, and “piecemeal” group with 28 levels. No significant differences in demographics or clinical variables were found among the three groups. However, piecemeal resection was associated with a higher incidence of dural tears and a longer surgical time (p<0.05). In contrast, en bloc resection, particularly in the two-wing group, demonstrated the best surgical times without an increase in complication rates. Conclusions The results revealed that removing the ligamentum flavum en bloc (either in two pieces or one) may reduce the surgical time and incidence of dural tears. Randomized and prospective studies are warranted to establish definitive conclusions.

PURPOSE: The aim of this study is to evaluate and compare the stress distribution in Locator attachments in mandibular two-implant overdentures according to implant locations and different loading conditions. MATERIALS AND METHODS: Four three-dimensional finite element models were created, simulating two osseointegrated implants in the mandible to support two Locator attachments and an overdenture. The models simulated an overdenture with implants located in the position of the level of lateral incisors, canines, second premolars, and crossed implant. A 150 N vertical unilateral and bilateral load was applied at different locations and 40 N was also applied when combined with anterior load at the midline. Data for von Mises stresses in the abutment (matrix) of the attachment and the plastic insert (patrix) of the attachment were produced numerically, color-coded, and compared between the models for attachments and loading conditions. RESULTS: Regardless of the load, the greatest stress values were recorded in the overdenture attachments with implants at lateral incisor locations. In all models and load conditions, the attachment abutment (matrix) withstood a much greater stress than the insert plastic (patrix). Regardless of the model, when a unilateral load was applied, the load side Locator attachments recorded a much higher stress compared to the contralateral side. However, with load bilateral posterior alone or combined at midline load, the stress distribution was more symmetrical. The stress is distributed primarily in the occlusal and lateral surface of the insert plastic patrix and threadless area of the abutment (matrix). CONCLUSION: The overdenture model with lateral incisor level implants is the worst design in terms of biomechanical environment for the attachment components. The bilateral load in general favors a more uniform stress distribution in both attachments compared to a much greater stress registered with unilateral load in the load side attachments. Regardless of the implant positions and the occlusal load application site, the stress transferred to the insert plastic is much lower than that registered in the abutment.
Bicuspid ; Clothing ; Denture, Overlay* ; Finite Element Analysis ; Incisor ; Mandible ; Plastics

Aged ; Cognition ; Cognitive Dysfunction/therapy* ; Female ; Humans ; Male ; Mental Status and Dementia Tests ; Middle Aged ; Pilot Projects