Clinical study on freehand of bicortical sacral screw fixation with the assistance of torque measurement device.

BACKGROUND: Sacral screw loosening is a typical complication after internal fixation surgery through the vertebral arch system. Bicortical fixation can successfully prevent screw loosening, and how improving the rate of bicortical fixation is a challenging clinical investigation. OBJECTIVE: To investigate the feasibility of improving the double corticality of sacral screws and the optimal fixation depth to achieve double cortical fixation by combining the torque measurement method with bare hands. METHODS: Ninety-seven cases of posterior lumbar internal fixation with pedicle root system were included in this study. Based on the tactile feedback of the surgeon indicating the expected penetration of the screw into the contralateral cortex of the sacrum, the screws were further rotated by 180°, 360°, or 720°, categorized into the bicortical 180° group, bicortical 360° group, and bicortical 720° group, respectively. Intraoperatively, the torque during screw insertion was recorded. Postoperatively, the rate of double-cortex engagement was evaluated at 7 days, and screw loosening was assessed at 1 year follow-up. RESULTS: The bicortical rates of the 180° group, 360° group, and 720° group were 66.13%, 91.18% and 93.75%, respectively. There were statistically significant differences between the 180° group and both the 360° and 720° groups (P < 0.05). However, there was no statistically significant difference between the 360° group and the 720° group (P > 0.05).The rates of loosening of sacral screws in the 180° group, 360° group, and 720° group were 20.97%, 7.35% and 7.81%, respectively. There were statistically significant differences between the 180° group and both the 360° and 720° groups (P < 0.05). However, there was no statistically significant difference between the 360° group and the 720° group (P > 0.05). The bicortical 360° group achieved a relatively satisfactory rate of dual cortical purchase while maintaining a lower rate of screw loosening. CONCLUSION: Manual insertion of sacral screws with the assistance of a torque measurement device can achieve a relatively satisfactory dual cortical purchase rate while reducing patient hospitalization costs.

Feasibility of transperineal minimal invasive surgery when performing sacrectomy for advanced primary and recurrent pelvic malignancies.

BACKGROUND: This study aimed to clarify the efficacy and safety of minimally invasive transabdominal surgery (MIS) with transperineal minimal invasive surgery (tpMIS) for sacrectomy in advanced primary and recurrent pelvic malignancies. METHODS: Using a prospectively collected database, we retrospectively analyzed the clinical, surgical, and pathological outcomes of MIS with tpMIS for sacrectomies. Surgery was performed between February 2019 and May 2023. The median follow-up period was 27 months (5-46 months). RESULTS: Fifteen consecutive patients were included in this analysis. The diagnoses were as follows: recurrent rectal cancer, n = 11 (73%); primary rectal cancer, n = 3 (20%); and recurrent ovarian cancer, n = 1 (7%). Seven patients (47%) underwent pelvic exenteration with sacrectomy, six patients (40%) underwent abdominoperineal resection (APR) with sacrectomy, and two patients (13%) underwent tumor resection with sacrectomy. The median intraoperative blood loss was 235 ml (range 45-1320 ml). The postoperative complications (Clavien-Dindo grade ≥ 3a) were graded as follows: 3a, n = 6 (40%); 3b, n = 1 (7%); and ≥ 4, n = 0 (0%). Pathological examinations demonstrated that R0 was achieved in 13 patients (87%). During the follow-up period, two patients (13%) developed local re-recurrence due to recurrent cancer. The remaining 13 patients (87%) had no local disease. Fourteen patients (93%) survived. CONCLUSIONS: Although the patient cohort in this study is heterogeneous, MIS with tpMIS was associated with a very small amount of blood loss, a low incidence of severe postoperative complications, and an acceptable R0 resection rate. Further studies are needed to clarify the long-term oncological feasibility.

Short-term outcomes of single port robotic hysterectomy with concomitant sacrocolpopexy.

The Da Vinci single port® (SP) robotic platform heralds a new era of minimally invasive surgery (MIS). The primary objective of this study was to assess short-term outcomes in patients undergoing SP robotic hysterectomy with concomitant sacrocolpopexy for pelvic organ prolapse (POP). We performed a retrospective case series at two tertiary care centers between January 2021 and August 2023. Patients with POP electing to undergo SP robotic hysterectomy with concomitant sacrocolpopexy were included. Chart abstraction was used to collect patient demographics and clinical outcomes. Recurrent POP was defined as new bothersome vaginal bulge symptoms and evidence of POP beyond the hymen on postoperative examination. 69 patients were included. Median operative time was 209 min (135-312) and estimated blood loss was 100 mL (20-2000). 1 (1.4%) patient sustained a major vascular injury resulting in laparotomy. Median pain score and morphine equivalents administered in PACU were low at 3 (0-7) and 3.2 (0-27) respectively. At 3 months, 60 (86.9%) patients were seen either in person or via telemedicine for their follow up appointment. 59/60 (98.3%) reported no vaginal bulge symptoms and 50/51 (98.0%) had stage 0 or 1 prolapse on exam. One (1.4%) patient had recurrent prolapse and underwent an additional repair. Postoperative complications included 2 (2.9%) cases of ileus/small bowel obstruction, 1 (1.4%) pelvic hematoma requiring a blood transfusion, and 1 (1.4%) umbilical hernia. The SP robotic platform is a safe and feasible platform for MIS hysterectomy and sacrocolpopexy with good short term anatomic and symptomatic outcomes.

Fluoroscopy guided teardrop technique for open trans-muscular iliac screw placement and open reduction maneuvers during modified triangular spinopelvic fixation for unstable U-shaped sacral and tile C pelvic traumas: technical note.

Unstable traumas of the spinopelvic junction, which include displaced U-shaped sacral fractures (Roy-Camille type 2 and type 3) and Tile C vertical shear pelvic ring disruptions, occur in severe traumas patients following high speed traffic accident or fall from a height. These unstable traumas of the spinopelvic junction jeopardize one's ability to stand and to walk by disrupting the biomechanical arches of the pelvis, and may also cause cauda equina syndrome. Historically, such patients were treated with bed rest and could suffer a life-long burden of orthopedic and neurological disability. Since Schildhauer pioneer work back in 2003, triangular spinopelvic fixation, whether it is performed in a percutaneous fashion or by open reduction and internal fixation, allows to realign bone fragments of the spinopelvic junction and to resume walking within three weeks. Nevertheless, such procedure remains highly technical and it not encountered very often, even for spine surgeons working in high-volume level 1 trauma centers. Hence, this visual technical note aims to provide a few tips to guide less experience surgeons to complete this procedure safely.

The optimal introversion angle and length of pedicle screw to avoid L1-S1 vascular damage.

BACKGROUND: posterior pedicle screw fixation is common method, one of the most severe complications is iatrogenic vascular damage, no report investigated association of different introversion angles (INTAs) and length of pedicle screw. The aims were to investigate the optimal introversion angle and length of pedicle screw for improving the safety of the operation, and to analyze the differences of vascular damage types at L1-S1. METHODS: Lumbar CT imaging data from110 patients were analyzed by DICOM software, and all parameters were measured by new Cartesian coordinate system, INTAs (L1-L5:5°,10°,15°,S1: 0°, 5°,10°,15°), DO-AVC (the distance between the origin (O) with anterior vertebral cortex (AVC)), DAVC-PGVs (the distance between AVC and the prevertebral great vessels (PGVs)), DO-PGVs (the distance between the O and PGVs). At different INTAs, DAVC-PGVs were divided into four grades: Grade III: DAVC-PGVs ≤ 3 mm, Grade II: 3 mm < DAVC-PGVs ≤ 5 mm, Grade I: DAVC-PGVs > 5 mm, and N: the not touching PGVs. RESULTS: The optimal INTA was 5° at L1-L3, the left was 5° and the right was 15° at L4, and screw length was less than 50 mm at L1-L4. At L5, the left optimal INTA was 5° and the right was 10°, and screw length was less than 45 mm. The optimal INTA was 15° at S1, and screw length was less than 50 mm. However, screw length was less than 40 mm when the INTA was 0° or 5° at S1. CONCLUSIONS: At L5-S1, the risk of vascular injury is the highest. INTA and length of the pedicle screw in lumbar operation are closely related. 3 mm interval of screw length may be more preferable to reduce vascular damage.

Effect of different lumbar-iliac fixation and sacral slope for Tile C1.3 pelvic fractures: a biomechanical study.

BACKGROUND: Lumbar-iliac fixation (LIF) is a common treatment for Tile C1.3 pelvic fractures, but different techniques, including L4-L5/L5 unilateral LIF (L4-L5/L5 ULIF), bilateral LIF (BLIF), and L4-L5/L5 triangular osteosynthesis (L4-L5/L5 TOS), still lack biomechanical evaluation. The sacral slope (SS) is key to the vertical shear of the sacrum but has not been investigated for its biomechanical role in lumbar-iliac fixation. The aim of this study is to evaluate the biomechanical effects of different LIF and SS on Tile C1.3 pelvic fracture under two-legged standing load in human cadavers. METHODS: Eight male fresh-frozen human lumbar-pelvic specimens were used in this study. Compressive force of 500 N was applied to the L4 vertebrae in the two-legged standing position of the pelvis. The Tile C1.3 pelvic fracture was prepared, and the posterior pelvic ring was fixed with L5 ULIF, L4-L5 ULIF, L5 TOS, L4-L5 TOS, and L4-L5 BLIF, respectively. Displacement and rotation of the anterior S1 foramen at 30° and 40° sacral slope (SS) were analyzed. RESULTS: The displacement of L4-L5/L5 TOS in the left-right and vertical direction, total displacement, and rotation in lateral bending decreased significantly, which is more pronounced at 40° SS. The difference in stability between L4-L5 and L5 ULIF was not significant. BLIF significantly limited left-right displacement. The ULIF vertical displacement at 40° SS was significantly higher than that at 30° SS. CONCLUSIONS: This study developed an in vitro two-legged standing pelvic model and demonstrated that TOS enhanced pelvic stability in the coronal plane and cephalad-caudal direction, and BLIF enhanced stability in the left-right direction. L4-L5 ULIF did not further improve the immediate stability, whereas TOS is required to increase the vertical stability at greater SS.

Multidisciplinary surgical considerations for en bloc resection of sacral chordoma: review of recent advances and a contemporary single-center series.

OBJECTIVE: Contemporary management of sacral chordomas requires maximizing the potential for recurrence-free and overall survival while minimizing treatment morbidity. En bloc resection can be performed at various levels of the sacrum, with tumor location and volume ultimately dictating the necessary extent of resection and subsequent tissue reconstruction. Because tumor resection involving the upper sacrum may be quite destabilizing, other pertinent considerations relate to instrumentation and subsequent tissue reconstruction. The primary aim of this study was to survey the surgical approaches used for managing primary sacral chordoma according to location of lumbosacral spine involvement, including a narrative review of the literature and examination of the authors' institutional case series. METHODS: The authors performed a narrative review of pertinent literature regarding reconstruction and complication avoidance techniques following en bloc resection of primary sacral tumors, supplemented by a contemporary series of 11 cases from their cohort. Relevant surgical anatomy, advances in instrumentation and reconstruction techniques, intraoperative imaging and navigation, soft-tissue reconstruction, and wound complication avoidance are also discussed. RESULTS: The review of the literature identified several surgical approaches used for management of primary sacral chordoma localized to low sacral levels (mid-S2 and below), high sacral levels (involving upper S2 and above), and high sacral levels with lumbar involvement. In the contemporary case series, the majority of cases (8/11) presented as low sacral tumors that did not require instrumentation. A minority required more extensive instrumentation and reconstruction, with 2 tumors involving upper S2 and/or S1 levels and 1 tumor extending into the lower lumbar spine. En bloc resection was successfully achieved in 10 of 11 cases, with a colostomy required in 2 cases due to rectal involvement. All 11 cases underwent musculocutaneous flap wound closure by plastic surgery, with none experiencing wound complications requiring revision. CONCLUSIONS: The modern management of sacral chordoma involves a multidisciplinary team of surgeons and intraoperative technologies to minimize surgical morbidity while optimizing oncological outcomes through en bloc resection. Most cases present with lower sacral tumors not requiring instrumentation, but stabilizing instrumentation and lumbosacral reconstruction are often required in upper sacral and lumbosacral cases. Among efforts to minimize wound-related complications, musculocutaneous flap closure stands out as an evidence-based measure that may mitigate risk.

3D CT modeling demonstrates the anatomic feasibility of S1AI screw trajectory for spinopelvic fixation in neuromuscular scoliosis.

PURPOSE: In patients with neuromuscular scoliosis undergoing posterior spinal fusion, the S2 alar iliac (S2AI) screw trajectory is a safe and effective method of lumbopelvic fixation but can lead to implant prominence. Here we use 3D CT modeling to demonstrate the anatomic feasibility of the S1 alar iliac screw (S1AI) compared to the S2AI trajectory in patients with neuromuscular scoliosis. METHODS: This retrospective study used CT scans of 14 patients with spinal deformity to create 3D spinal reconstructions and model the insertional anatomy, max length, screw diameter, and potential for implant prominence between 28 S2AI and 28 S1AI screw trajectories. RESULTS: Patients had a mean age of 14.42 (range 8-21), coronal cobb angle of 85° (range 54-141), and pelvic obliquity of 28° (range 4-51). The maximum length and diameter of both screw trajectories were similar. S1AI screws were, on average, 6.3 ± 5 mm less prominent than S2AI screws relative to the iliac crests. S2AI screws were feasible in all patients, while in two patients, posterior elements of the lumbar spine would interfere with S1AI screw insertion. CONCLUSION: In this cohort of patients with neuromuscular scoliosis, we demonstrate that the S1AI trajectory offers comparable screw length and diameter to an S2AI screw with less implant prominence. An S1AI screw, however, may not be feasible in some patients due to interference from the posterior elements of the lumbar spine.

Challenges of enbloc mid-sacrectomy as redo surgery for sacral chordoma: a case report.

Enbloc Sacrectomy is the procedure of choice for aggressive sacral lesions but not widely practiced in Pakistan, both by Neurosurgeons and Orthopaedic surgeons. Only one case has been mentioned in indexed local literature so far and that too not operated in Pakistan. The case of a 27 year old neurologically intact male is presented. He had a huge residual mass and midline non-healing wound after two attempts at intralesional debulking and one full course of local irradiation. He presented to the Mayo Hospital, Lahore on 29th December 2021 for a redo surgery of sacral chordoma. A marginal excision was achieved utilizing posterior only approach. This case will help to understand the key steps in enbloc mid-Sacrectomy and importance of involving multidisciplinary team for ensuring adequate wound closure.

Preoperative and follow-up variations of psoas major muscle are related to S1 screw loosening in patients with degenerative lumbar spinal stenosis.

BACKGROUND: It was reported the paraspinal muscle played an important role in spinal stability. The preoperative paraspinal muscle was related to S1 screw loosening. But the relationship between preoperative and postoperative change of psoas major muscle (PS) and S1 pedicle screw loosening in degenerative lumbar spinal stenosis (DLSS) patients has not been reported. This study investigated the effects of preoperative and follow-up variations in the psoas major muscle (PS) on the first sacral vertebra (S1) screw loosening in patients with DLSS. METHODS: 212 patients with DLSS who underwent lumbar surgery were included. The patients were divided into the S1 screw loosening group and the S1 screw non-loosening group. Muscle parameters were measured preoperatively and at last follow-up magnetic resonance imaging. A logistic regression analysis was performed to investigate the risk factors for S1 screw loosening. RESULTS: The S1 screw loosening rate was 36.32% (77/212). The relative total cross-sectional areas and relative functional cross-sectional areas (rfCSAs) of the PS at L2-S1 were significantly higher after surgery. The increased rfCSA values of the PS at L3-S1 in the S1 screw non-loosening group were significantly higher than those in the S1 screw loosening group. The regression analysis showed male, lower CT value of L1 and longer segment fusion were independent risk factors for S1 screw loosening, and postoperative hypertrophy of the PS was a protective factor for S1 screw loosening. CONCLUSIONS: Compared to the preoperative muscle, the PS size increased and fatty infiltration decreased after surgery from L2-3 to L5-S1 in patients with DLSS after short-segment lumbar fusion surgery. Postoperative hypertrophy of the PS might be considered as a protective factor for S1 screw loosening. MRI morphometric parameters and postoperative selected exercise of PS for DLSS patients after posterior lumbar fusion surgery might contribute to improvement of surgical outcome.

Soft Tissue Reconstruction After Sacral Neoplasm Resection: The University of California San Francisco Experience.

PURPOSE: Resection of sacral neoplasms such as chordoma and chondrosarcoma with subsequent reconstruction of large soft tissue defects is a complex multidisciplinary process. Radiotherapy and prior abdominal surgery play a role in reconstructive planning; however, there is no consensus on how to maximize outcomes. In this study, we present our institution's experience with the reconstructive surgical management of this unique patient population. METHODS: We conducted a retrospective review of patients who underwent reconstruction after resection of primary or recurrent pelvic chordoma or chondrosarcoma between 2002 and 2019. Surgical details, hospital stay, and postoperative outcomes were assessed. Patients were divided into 3 groups for comparison based on reconstruction technique: gluteal-based flaps, vertical rectus abdominus myocutaneous (VRAM) flaps, and locoregional fasciocutaneous flaps. RESULTS: Twenty-eight patients (17 males, 11 females), with mean age of 62 years (range, 34-86 years), were reviewed. Twenty-two patients (78.6%) received gluteal-based flaps, 3 patients (10.7%) received VRAM flaps, and 3 patients (10.7%) were reconstructed with locoregional fasciocutaneous flaps. Patients in the VRAM group were significantly more likely to have undergone total sacrectomy (P < 0.01) in a 2-stage operation (P < 0.01) compared with patients in the other 2 groups. Patients in the VRAM group also had a significantly greater average number of reoperations (2 ± 3.5, P = 0.04) and length of stay (29.7 ± 20.4 days, P = 0.01) compared with the 2 other groups. The overall minor and major wound complication rates were 17.9% and 42.9%, respectively, with 17.9% of patients experiencing at least 1 infection or seroma. There was no association between prior abdominal surgery, surgical stages, or radiation therapy and an increased risk of wound complications. CONCLUSIONS: Vertical rectus abdominus myocutaneous flaps are a more suitable option for patients with larger defects after total sacrectomy via 2-staged anteroposterior resections, whereas gluteal myocutaneous flaps are effective options for posterior-only resections. For patients with small- to moderate-sized defects, local fasciocutaneous flaps are a less invasive and effective option. Paraspinous flaps may be used in combination with other techniques to provide additional bulk and coverage for especially long postresection wounds. Furthermore, mesh is a useful adjunct for any reconstruction aimed at protecting against intra-abdominal complications.

En-bloc excision of sacral squamous cell carcinoma with immediate reconstruction.

Sacral squamous cell carcinoma is an uncommon condition that may arise in scars following burns or in chronic wounds, such as an untreated pilonidal cyst. The aim of the present technical note is to describe a surgical technique aimed at minimizing local recurrence rates by en-bloc resection as well as providing immediate plastic reconstruction: 1. right-sided extended vertical rectus abdominis myo-cutaneous (VRAM) flap; 2. abdomino-perineal excision of the rectum with end colostomy; 3. en-bloc excision of the mass inclusive of gluteus maximus muscles and distal sacrectomy; 4. sacrectomy defect covered with VRAM flap; 5. bilateral gluteal defects covered with single-layer dermal substitute of bovine collagen and elastin hydrolysate followed by immediate split-thickness skin grafting from bilateral thigh donor sites, and negative pressure wound therapy dressings. This approach resulted in a favorable outcome at 2-year follow-up in a male patient presenting with a large locally advanced sacral squamous cell carcinoma involving the external anal sphincter muscle.

Surgical Intervention is Associated with Improvement in Health-Related Quality of Life Outcomes in Patients with Symptomatic Sacral Tarlov Cysts: Results from a Prospective Longitudinal Cohort Study.

OBJECTIVE: The treatment of symptomatic Tarlov cysts remains a controversial topic within neurosurgery. We describe our experience with patients who underwent surgical intervention for sacral Tarlov cysts at a single institution. General and disease-specific outcome measures were used to assess health-related quality of life. METHODS: Patients who underwent surgical treatment for one or more sacral Tarlov cysts between 2018 and 2021 were included. The Tarlov Cyst Quality of Life (TCQoL), a validated disease-specific measure, was the primary outcome of the study. Secondary outcomes included general outcome measures: 36-Item Short Form Survey, the Oswestry Disability Index, and Visual Analog Scale. Patients were followed at 3, 6, and 12 months postoperatively. Repeated measures analyses were used to assess change from preoperative to 12 months postoperative. RESULTS: Data were obtained from 144 patients who underwent surgery for sacral Tarlov cysts, average age 52.3 ± 11.3 years, 90.3% female. Patients reported significant mean improvement on the TCQoL over time (preoperative 3.2 ± 0.1; 3-month postoperative 2.1 ± 0.1; 6-month 1.9 ± 0.1; 12-month 1.9 ± 0.1; P < 0.001). Patient age and duration of symptoms were not associated with outcome. A total of 82.3% of patients reported improvement on TCQoL. There was not a significant difference in the proportion of patients reporting improvement on TCQoL by cyst size (small 90.9% vs. large 77.9%; P = 0.066). CONCLUSIONS: Our longitudinal series demonstrated patient-reported improvement following surgery for symptomatic sacral Tarlov cysts using a validated disease-specific health-related quality of life scale through 12 months after surgery. Patient age and preoperative duration of symptoms were not correlated with outcome.

A Retrospective Cohort Study of vNOTES Extraperitoneal Versus Laparoscopic Sacral Hysteropexy With Uterine Preserving Regarding Surgical Outcomes and Two-Year Follow-Up Results.

STUDY OBJECTIVE: To explore the effectiveness of transvaginal natural orifice transluminal endoscopic surgery extraperitoneal sacral hysteropexy (vNOTES-ESH) in women with symptomatic uterine prolapse over a 2 year follow-up. DESIGN: Retrospective cohort study. SETTING: Gynecological minimally invasive center. PATIENTS: Women undergoing sacral hysteropexy either by vNOTES (n = 25) or laparoscopic (n = 74) between November 2016 and December 2020. INTERVENTIONS: Both vNOTES-ESH and laparoscopic sacral hysteropexy (LAP-SH) were used for uterine prolapse. Demographic data, operative characteristics, perioperative outcomes, and follow-up information 2 years postsurgery in the 2 groups were retrospectively evaluated. RESULTS: Both procedures showed similar operation time, estimated blood loss, hospital stays, and pain scores (p >0.05). During a median follow-up of 59 (24-72) months, the surgical success rate was 96% for vNOTES-ESH and 97.3% for LAP-SH (p >0.05), with no differences in anatomical position or pelvic organ function after the operation. Women in the LAP-SH group experienced more bothersome symptoms of constipation compared to those in the vNOTES-ESH group (5.41% vs 0, p <0.05). Lastly, 1 case in the vNOTES-ESH group had a mesh exposed area of less than 1 cm2, and 1 patient in the LAP-SH group experienced stress incontinence. CONCLUSIONS: In this retrospective study, vNOTES-ESH met our patients' preference for uterine preservation and was a successful and effective treatment for uterine prolapse, providing good functional improvement in our follow-up. This procedure should be considered as an option for patients with pelvic organ prolapse.

Presacral Neuroendocrine Neoplasms: A Multi-site Review of Surgical Outcomes.

INTRODUCTION: Presacral neuroendocrine neoplasms (PNENs) are rare tumors, with limited data on management and outcomes. METHODS: A retrospective review of institutional medical records was conducted to identify all patients with PNENs between 2008 and 2022. Data collection included demographics, symptoms, imaging, surgical approaches, pathology, complications, and long-term outcomes. RESULTS: Twelve patients were identified; two-thirds were female, averaging 44.8 years of age, and, for the most part, presenting with back pain, constipation, and abdominal discomfort. Preoperative imaging included computed tomography scans and magnetic resonance images, with somatostatin receptor imaging and biopsies being common. Half of the patients had metastatic disease on presentation. Surgical approach varied, with anterior, posterior, and combined techniques used, often involving muscle transection and coccygectomy. Short-term complications affected one-quarter of patients. Pathologically, PNENs were mainly well-differentiated grade 2 tumors with positive synaptophysin and chromogranin A. Associated anomalies were common, with tail-gut cysts prevalent. Mean tumor diameter was 6.3 cm. Four patients received long-term adjuvant therapy. Disease progression necessitated additional interventions, including surgery and various chemotherapy regimens. Skeletal, liver, thyroid, lung, and pancreatic metastases occurred during follow-up, with no mortality reported. Kaplan-Meier analysis showed a 5-year local recurrence rate of 23.8%, disease progression rate of 14.3%, and de novo metastases rate of 30%. CONCLUSION: The study underscores the complex management of PNENs and emphasizes the need for multicenter research to better understand and manage these tumors. It provides valuable insights into surgical outcomes, recurrence rates, and overall survival, guiding future treatment strategies for PNEN patients.

Modified S1 Pedicle Subtraction Osteotomy.

STUDY DESIGN: Surgical technique video. OBJECTIVE: To report a surgical technique to revise patients with previous fusions at L4-S1 leading to an iatrogenic flat back and sagittal imbalance using L5-S1 transforaminal interbody fusion combined with a small S1 corner osteotomy. BACKGROUND: This is a case of a woman (51 y old) with a history of multiple lumbar surgeries, severe back pain, sagittal imbalance, and loss of lordosis. METHODS: We describe a feasible revision technique in a complex patient with the goal of attaining optimal distribution of lumbar lordosis and sagittal balance through a modified S1 pedicle subtraction osteotomy, and the use of an interbody cage to enhance the fusion rate and facilitate closure of the 3-column osteotomy. RESULTS: The preoperative patient lordosis angle of 31 degrees at L1-L4 and 16 degrees at L4-S1 became 12 degrees at L1-L4 and 44 degrees at L4-S1 postoperatively. CONCLUSION: The combination of L5-S1 transforaminal interbody fusion and S1 corner osteotomy is a feasible technique for the restoration of lumbar lordosis in patients with previous fusion and consequent loss of lordosis.

The Influence of Radiographic Parameter on the S2 Alar-Iliac Screw Virtual Trajectory in Degenerative Lumbar Scoliosis Patients: A Computed Tomography Study.

OBJECTIVE: S2 alar-iliac (S2AI) screw had been widely used in the pelvic fusion for degenerative lumbar scoliosis (DLS) patients. However, whether S2AI screw trajectory was influenced by sagittal profile in DLS patients had not been comprehensively investigated. The objective of this study was to evaluate the associations between the optimal S2 alar-iliac (S2AI) screw trajectory and sagittal spinopelvic parameters in DLS patients. METHODS: Computed tomography (CT) scans of pelvis were performed in 47 DLS patients for three-dimensional reconstruction of S2AI screw trajectory from September 2019 to November 2021. Five S2AI screw trajectory parameters were measured in CT reconstruction images, including: 1) angle in the transverse plane (Tsv angle); 2) angle in the sagittal plane (Sag angle); 3) maximal screw length; 4) screw width; and 5) skin distance. The lumbar Cobb angle, lumbar apical vertebral translation (AVT); global kyphosis (GK); thoracic kyphosis (TK); lumbar lordosis (LL); sagittal vertical axis (SVA); sacral slope (SS); pelvic tilt (PT); and pelvic incidence (PI) were measured in standing X-ray films of the whole spine and pelvis. RESULTS: Both Tsv angle and Sag angle had significant positive associations with SS (p < 0.05) but negative associations with both PT (p < 0.05) and LL (p < 0.05) in all cases. Patients with SS less than 15° had both smaller Tsv angle and Sag angle than those with SS equal to or more than 15° (p < 0.05). The decreased LL would lead to the backward rotation of the pelvis, resulting in a more cephalic and less divergent trajectory of S2AI screw in DLS patients. CONCLUSIONS: For DLS patients with lumbar kyphosis, spine surgeons should avoid both excessive Tsv and Sag angles for S2AI screw insertion, especially when using free-hand technique.

The minimally invasive sacrospinous fixation under visual guidance: An anatomical study.

OBJECTIVE: Sacrospinous fixation is the gold standard procedure for management of apical pelvic organ prolapse by the vaginal route. However, there may be a relevant risk of neurovascular injury due to the proximity of neurovascular structures. We propose an anatomical study concerning the sacrospinous ligament with a new innovative minimally invasive technology using both a suture capturing device and a chip-on-the-tip endoscope to perform sacropinous fixation. STUDY DESIGN: Bilateral sacrospinous fixation was performed in three female cadavers, in the course of the anatomical study conducted with a specific device (the Suture Capturing I Stitch™ Device) under real time visual guidance with a chip-on -the-tip endoscope, the NanoScope™ system. RESULTS: Identification of ischial spine and sacrospinous ligament as well as feasibility of sacrospinous fixation under NanoScope™ control were always possible on both sides. CONCLUSIONS: This new innovative minimally invasive technology using both a suture capturing device and a chip-on-the-tip endoscope is relevant and could be an advantage in terms of safety and better placement of the suture on the sacrospinous ligament.

Biomechanical comparative study on external fixators of new configurations in the treatment of Tile C pelvic injury.

To compare the biomechanical properties of several anterior pelvic ring external fixators with two new configurations in the treatment of Tile C pelvic fractures, in order to evaluate the effectiveness of the new configurations and provide a reference for their clinical application. A finite element model of a Tile C pelvic ring injury (unilateral longitudinal sacral fracture and ipsilateral pubic fracture) was constructed. The pelvis was fixed with iliac crest external fixator (IC), anterior inferior iliac spine external fixator (AIIS), combination of IC and AIIS, combination of anterior superior iliac spine external fixator (ASIS) and AIIS, and S1 sacroiliac screw in 5 types of models. The stability indices of the anterior and posterior pelvic rings under vertical longitudinal load, left-right compression load and anterior-posterior shear load were quantified and compared. In the simulated bipedal standing position, the results of the vertical displacement of the midpoint on the upper surface of the sacrum are consistent with the displacement of the posterior rotation angle, and the order from largest to smallest is IC, AIIS, ASIS + AIIS, IC + AIIS and S1 screw. The longitudinal displacement of IC is greater than that of the other models. The displacements of ASIS + AIIS and IC + AIIS are similar and the latter is smaller. In the simulated semi-recumbent position, the vertical displacement and posterior rotation angle displacement of the midpoint on the upper surface of the sacrum are also consistent, ranking from large to small: IC, AIIS, ASIS + AIIS, IC + AIIS and S1 screw. Under the simulated left-right compression load state, the lateral displacements of the highest point of the lateral sacral fracture end are consistent with the highest point of the lateral pubic fracture end, and the order from large to small is S1 screw, IC, AIIS, ASIS + AIIS and IC + AIIS, among which the displacements of S1 screw and IC are larger, and the displacements of ASIS + AIIS and IC + AIIS are similar and smaller than those of other models. The displacements of IC + AIIS are smaller than those of ASIS + AIIS. Under the simulated anterior-posterior shear load condition, the posterior displacements of the highest point of the lateral sacral fracture end and the highest point of the lateral pubic fracture end are also consistent, ranking from large to small: IC, AIIS, ASIS + AIIS, IC + AIIS and S1 screw. Among them, the displacements of IC and AIIS are larger. The displacements of ASIS + AIIS and IC + AIIS are similar and the latter are smaller. For the unstable pelvic injury represented by Tile C pelvic fracture, the biomechanical various stabilities of the combination of IC and AIIS are superior to those of the external fixators of conventional configurations. The biomechanical stabilities of the combination of ASIS and AIIS are also better than those of the external fixators of conventional configurations, and slightly worse than those of the combination of IC and AIIS. Compared with sacroiliac screw and conventional external fixators, the lateral stabilities of IC + AIIS and ASIS + AIIS are particularly prominent.

Impact of shear stress on sacral pressure injury from table rotation during laparoscopic colorectal surgery performed in the lithotomy position.

This study aimed to evaluate the impact of shear stress on surgery-related sacral pressure injury (PI) after laparoscopic colorectal surgery performed in the lithotomy position. We included 37 patients who underwent this procedure between November 2021 and October 2022. The primary outcome was average horizontal shear stress caused by the rotation of the operating table during the operation, and the secondary outcome was interface pressure over time. Sensors were used to measure shear stress and interface pressure in the sacral region. Patients were divided into two groups according to the presence or absence of PI. PI had an incidence of 32.4%, and the primary outcome, average horizontal shear stress, was significantly higher in the PI group than in the no-PI group. The interface pressure increased over time in both groups. At 120 min, the interface pressure was two times higher in the PI group than in the no-PI group (PI group, 221.5 mmHg; no-PI group, 86.0 mmHg; p < 0.01). This study suggested that shear stress resulting from rotation of the operating table in the sacral region by laparoscopic colorectal surgery performed in the lithotomy position is the cause of PI. These results should contribute to the prevention of PI.