Posterior Fixation Research Articles

Isolated Dislocation of the Carpal Scaphoid: A Case Report

Isolated scaphoid dislocation is an exceedingly rare event with only a few cases described. It’s a rare and uncommon occurrence among carpal dislocations. In this case report, we present the case of a 50-year-old male diagnosed with an isolated radio-palmar dislocation of scaphoid in the emergency department based on clinical and radiological findings. Treatment involved posterior open reduction and fixation using two Kirschner wires under Fluoroscopy the one-year follow-up, the patient showed a favorable outcome, with complete restoration of wrist functioncopic guidance, followed by immobilization in a cast for 45 days.

Unilateral Vision Loss after Posterior Fixation for Traumatic Atlantoaxial Dislocation: A Case Report with Literature Review

Unilateral Vision Loss after Posterior Fixation for Traumatic Atlantoaxial Dislocation: A Case Report with Literature Review

Insertion sites of iliosacral screws on the posterior ilium: Implications for posterior pelvic fixation

ObjectivesLateral compression type II pelvic ring injuries can be treated with fixation through open or percutaneous approaches depending on the injury pattern and available osseous fixation pathways. The start site of iliosacral screws to stabilize these injuries should be on the unstable posterior iliac fragment; however, our understanding of start sites for iliosacral screws has not been developed. The purpose of this study is to provide an analysis of iliosacral screw start sites on the posterior ilium to help guide treatment of pelvic ring injuries. MethodsOne-hundred and seventeen consecutive patients at an academic level I trauma center with pelvic ring injuries who underwent surgical treatment with iliosacral screws were included in the final analysis. The start sites of iliosacral screws with confirmed intraosseous placement on a postoperative computed tomography were mapped on the posterior ilium and analyzed according to the sacral segment and type of iliosacral screw. ResultsOne-hundred and seventeen patients were included in the final analysis. Of the total of 272 iliosacral screw insertion sites analyzed, 145 (53%) were sacroiliac-style screws and 127 (47%) were transsacral screws. The insertion sites for sacroiliac-style screws and transsacral screws at different sacral segment levels can vary but have predictable regions on the posterior ilium relative to reliable osseous landmarks. ConclusionsIliosacral screws start sites on the posterior ilium have reliable regions that can be used to plan posterior fixation of pelvic ring injuries.

Comparison of Anterior versus Posterior Fixation in Traumatic Subaxial Cervical Spine Subluxation in Terms of Intraoperative Blood Loss, Surgical Time, and Length of Hospital Stay: A Prospective Observational Study

Abstract Objective The aim of this study was to compare the outcome of anterior versus posterior fixation for traumatic subaxial cervical spine subluxation in terms of mean intraoperative blood loss, surgical time, and length of hospital stay. Materials and Methods A prospective observational study was conducted from August 25, 2022 to August 24, 2023 at the Department of Neurosurgery, Punjab Institute of Neurosciences, Lahore, Pakistan, including 60 patients (30 in each group) fulfilling the inclusion criteria. Group A had anterior cervical fixation, while group B underwent posterior cervical fixation. Patients were monitored for intraoperative blood loss, surgical time, and length of hospital stay. All the results were collected and recorded on a proforma. Results The mean age of the patients in group A was 45.40 ± 3.75 years and that in group B was 45.50 ± 4.13 years. In all, 48.8% (n = 21) were males and 52.9% (n = 9) were females in group A, while 51.2% (n = 22) were males and 47.1% (n = 8) were females in group B. The mean intraoperative blood loss was 71.60 ± 0.77 mL in group A and 101.76 ± 0.85 mL in group B. The mean surgical time was 72.73 ± 0.98 minutes in group A and 94.73 ± 0.58 minutes in group B. The mean length of hospital stay was 7.63 ± 0.55 days in group A and 12.80 ± 0.71 days in group B. Conclusion It was concluded that the anterior approach is better than the posterior approach for traumatic subaxial cervical subluxation spine in terms of low blood loss, less surgical time, and reduced hospital stay.

Bilateral ultrasound-guided erector spinae plane block for postoperative pain relief in major traumatic spine surgery: A randomized controlled trial.

Spine fixation surgery for traumatic vertebral fractures is associated with severe pain and is often difficult to control. Traditionally systemic opioids have been the mainstay of analgesia for these procedures, which can lead to hyperalgesia, nausea, ileus, sedation, cognitive impairment, dependence, etc., limiting usage of opioids. The Erector spinae plane block (ESPB) is a novel ultrasound-guided procedure with easily identifiable sonoanatomy. We hypothesized that a multimodal approach involving ESPB to a conventional analgesic regimen with local infiltration for patients undergoing major traumatic spine surgeries might provide better perioperative analgesia and reduce the need for postoperative opioid requirements. A randomized control prospective trial was conducted on 34 ASA grade I -II patients aged 18 to 65 years who were scheduled to undergo elective posterior spine fixation surgery with ASIA B to E after traumatic spine fracture under general anesthesia. Patients were randomized to Group A which included patients who received general anesthesia with ESPB, and Group B, or the control group, included patients who received general anesthesia with systemic analgesics and postoperative local infiltration without ESPB. Intraoperative total fentanyl consumption, VAS score at 0, 3, 6, 12, 18, and 24 hours, time to activate patient-controlled analgesia (PCA) pump, total morphine consumption, and opioid-related side effects were monitored and compared in both groups. Postoperative PCA morphine consumption was significantly lower in group A patients who received ESPB than those in the control group (17.06 ± 9.59 vs 37.82 ± 9.88 P value = <0.0001). VAS scores at rest and movement at 0, 3, 6, 9, 12, 18, and 24 hours were significantly lower (P value = 0.05) in the ESPB group compared with the control group at all time points. Bilateral ultrasound-guided Erector spinae plane block, when administered in traumatic spine patients undergoing spine fixation surgery, provides better analgesia with statistically decreased VAS scores and less postoperative opioid requirement.

Hirayama disease successfully treated by posterior fixation: a case report

Introduction and importance: Hirayama disease is a rare form of motor neuron amyotrophy that usually presents with weakness and atrophy of the distal upper extremities in young males. It is believed that it is caused by spinal cord compression during neck flexion because of the widening of the posterior extradural space. This case has been brought to attention due to its extraordinary rarity, serving as an educational tool for medical professionals and to advocate for surgical intervention when deemed necessary. Case presentation: The authors present a case of a young male in his 20s who was diagnosed with Hirayama disease, had weakness and atrophy in both of his upper limbs, and has been successfully treated by posterior fixation at C4, C5, and C6 with lateral mass screws. Clinical discussion: The majority of cases stabilize after 2–3 years of progression; therefore, cervical collars are generally sufficient for therapy. However, in certain serious cases with progression even after that time, surgical intervention is an option. Because this is such an uncommon incidence, surgical therapy has not been explored and is controversial. Conclusion: The use of posterior fixation at C4, C5, and C6 with lateral mass screws as a therapy for Hirayama disease may be regarded as a successful approach.

Promoting Regeneration in Degenerative Disc Disease.

The degenerative disc disease has a multifactorial etiology and mechanical stress is one of the most important etiological factor. The purpose of this study was to evaluate the intervertebral disc (IVD) after axial stress diminution from the point of view of its proteoglycan (PG) content, with preoteoglicans (PGs) being very important in the normal function but also in the degenerative or regenerative processes. This is a single-center, prospective, non-randomized study of 38 degenerated intervertebral discs treated with monosegmental or polisegmental posterior lumbar spinal fixation in 27 patients. During surgery, a posterior intervertebral distraction at operated levels was applied. Patients' mean age was 50.77 years and the mean follow-up 28.74 months. Both clinical (visual analog pain scale, Oswestry disability index) and radiological (lumbar spine lordosis, disc thickness) analyses were made before and after surgery. A new method of cartilage analysis, which was also validated for the IVD, delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) was used to determine the PG content before and after surgery for both the intervertebral degenerative disc and control level L1-L2 disc. The clinical features improved significantly. The thickness of the operated discs increased by an average of 1.71 mm postoperatively and remained unchanged in the control group. The lumbar lordosis did not change significantly. In dGEMRIC studies, the discs accumulated in average 410.08 units /cm2 of gadolinium before surgery and 272.45 units/cm2 after surgery, without significant changes in the control group. Our study shows an improvement of PG quantity in degenerated IVD due to a decrease in gadolinium binding seen in dGEMRIC study. Thus, we can ameliorate IVD homeostasis by eliminating mechanical stress, which could be a step towards the process of disc regeneration.

Modified pedicle screw-rod fixation versus open reduction plate fixation for the management of pubic symphysis diastasis: A retrospective study

ObjectiveSurgical intervention and fixation is the recognized measurement to treat pubic symphysis diastasis caused by high-energy trauma. The purpose of this retrospective study was to assess the clinical application of modified pedicle screw-rod fixation (modified PSRF) and open reduction plate fixation (ORPF) for treating pubic symphysis diastasis. MethodsThe data of this retrospective analysis were collected from 32 patients with pubic symphysis diastasis managed with modified PSRF or ORPF from January 2012 to December 2017, with or without posterior fixation. Indicators of clinical assessments including operating time, intraoperative blood loss, relevant surgical complications as well as follow-up were recorded. Majeed scores were performed for functional evaluation, as well as Matta criteria were applied to evaluate the quality of reduction. ResultsThe average time from injury to operation was 2.9 days in modified PSRF group and 3.2 days in ORPF group. Significant differences regarding average operation time (41.8 min versus 64.3 min) and average intraoperative blood loss (46.6 ml versus 304.6 ml) were presented between modified PSRF groups and ORPF group. Neither Majeed scores nor Matta evaluation showed a significant difference between two groups. In ORPF group, the incision infection occurred in one patient and two patients developed loosening of screws. In modified PSRF group, loosening of screws was found in one patient during the operative procedure and one patient experienced femoral nerve palsy. Irritation to the lateral femoral cutaneous nerve (LFCN) was detected in two patients in modified PSRF group. ConclusionsSatisfactory clinical outcomes were provided with applications of both fixation methods for treating pubic symphysis diastasis. Modified PSRF, as a minimal invasive technique, could serve as an effective and reasonable option for treating pubic symphysis diastasis.Level of evidence: III: retrospective cohort study.Trial registration: researchregistry3906.

Experience of mesenteric sector fixation in mesenteric torsion treatment

Objective: The preliminary results was reported regarding the treatment of mesenteric torsion by mesenteric fixation in the last decade, especially preventing recurrence of mesenteric torsion by mesenteric fan-shaped fixation. Methods: We selected 12 patients who received emergency operation in Chongqing Hospital of the First Affiliated Hospital of Guangzhou University of Chinese Medicine from December 2010 to March 2022. All of them were made a definite diagnose of mesenteric torsion by the preoperative CT scan or exploratory laparotomy. The recurrence of mesenteric torsion will be prevented by taking the operation of mesenteric fan-shaped fixation. This technique is suitable for the patient who is suffering total mesenteric torsion, but enteric necrosis is excluded affirmatively. The operation is consists of the following progress: (1) Exploratory laparotomy to check for necrosis of the bowel and for lesions other than torsion. (2) Mesenteric torsion derotation.(3) Mesenteric linear fixation; the right posterior lower border of the small mesentery (terminal ileal mesentery) is intermittently sutured to the posterior peritoneum of the right lower quadrant to increase the width of the base of the small mesentery. (4) Mesenteric fan-shaped fixation, which is fan-shaped to the lower left and fixed in the posterior peritoneum, shortening the length of the mesentery and further increasing the width of the mesentery and posterior peritoneal fixation. Results: A total of 12 patients with mesenteric torsion were treated by operation for 15 times in all. Among them, 3 cases received resection of most small bowel were performed without recurrence; 3 patients received only derotation for a total of 4 times, 2 cases recurred, 1 of them recurred twice; 4 cases underwent derotation and mesenteric linear fixation,and 1 case recurred. Four patients with derotation and mesenteric fan-shaped fixation recovered well without recurrence. Conclusion: Mesenteric fan-shaped fixation may be an effective operative type to reduce or avoid postoperative recurrence of mesenteric torsion.

Progress of anterior subcutaneous internal fixation in the treatment of anterior pelvic ring injury

Anterior subcutaneous internal fixation (INFIX) is one of the current representatives of minimally invasive fixation of injuries to the anterior pelvic ring. The nail insertion point of this technique is located at the anterior inferior iliac spinous screw, with an angle of 30° outward and 20° backward. Screw in at an angle, and note that the screw head should be above the deep fascia and maintain a safe distance of 20 to 25 mm from the bone surface. Its improved versions include 3 or 4 nails INFIX with added pubic tubercle screws, unilateral INFIX, short-rod INFIX, and double INFIX. These improvements further enhance stability. The lateral femoral cutaneous nerve (LFCN) is relatively easy to be damaged during anatomy, so special attention should be paid during the operation. Biomechanical stability has advantages over external fixation, and its application is flexible. It is not limited to pubic ramus fracture, symphyseal separation, etc. It also plays an important role in combined anterior and posterior ring fixation. It can be combined with posterior sacroiliac screws, iliac lumbar screws, etc. Fixed etc. Good clinical results have also been reported in children, pregnant women, and people with contraindications for subcutaneous connecting rods. In addition, the current application of robots, reduction frames and other technologies has greatly reduced the difficulty of reduction and improved the quality of closed reduction, making it possible to fix complex pelvic fracture. This technique has high reduction quality and is as effective as traditional steel plates. A common complication is LFCN injury. Careful exposure and adjustment of the position and depth of internal fixation during surgery can effectively avoid this complication.

A Novel Leverage Technique Using Monoaxial Pedicle Screw for Reduction of Thoracolumbar Compression Fractures: Surgical Technique and Analysis of Radiological Parameters.

Thoracolumbar compression fractures resulting from high-energy injuries are a common type of spinal fracture. Satisfying reduction of compressive vertebra body is essential for the clinical outcome. However, traditional distraction technique may lead to complications including pedicle screw loosening, pedicle screw breakage, and postoperative back pain because of excessive distraction. In this study, we reported a novel technique for reduction. Additionally, the effect and postoperative radiological parameters of this technique were compared with those of traditional distraction technique. The clinical data of 80 patients who had been treated with posterior pedicle screw fixation from January 2019 to December 2020 was retrospectively analyzed. Thirty-six patients were performed with the leverage technique, while 22 patients were treated with the traditional distraction technique. When pedicle screw fixation was performed with either the leverage technique or the traditional distraction technique, fracture reduction was completed with monoaxial pedicle screws using either the leverage maneuver or distraction of adjacent vertebrae. Clinical evaluation, including operation time, hospital stay, blood loss volume, and postoperative complications were collected. The American Spinal Injury Association (ASIA) score for neurological condition and the visual analog scale (VAS) score for pain were used to evaluate the patients' functional outcome. The radiographic analysis included local kyphotic angle (LKA), regional kyphotic angle (RKA), anterior vertebral height (AVH), posterior vertebral height (PVH), and sagittal compression (SC). The student t-test and the χ2-test (or the Fisher exact test) were used to compare the outcome measures between the two groups. The leverage group comprised 36 patients, while 44 patients were included in the distraction group. No statistically significant differences were found in the demographic data. The VAS score in the leverage group (3.0 ± 0.8) was significantly lower than that in the distraction group (4.2 ± 0.6) on postoperative day 1. Total correction of the LKA in the leverage group (11.5 ± 2.5°) was significantly higher than that in the distraction group (7.1 ± 1.3°) (p = 0.0004). Total correction of the RKA was higher in the leverage group (12.1 ± 4.3°) than in the distraction group (6.1 ± 0.9°) (p = 0.005). The ratio of rear pillar /front pillar correction was 0.35 ± 0.13 and 0.89 ± 0.18 in the leverage and distraction groups, respectively (p = 0.014). Total correction of the upper and lower foraminal height in the leverage group was significantly less than that in the distraction group. The leverage group had significantly higher correction of the upper and lower intervertebral space height than the distraction group. Our novel leverage technique provided better kyphotic reduction and restoration than compared to conventional distraction technique in the surgical treatment of thoracolumbar compression fractures.

The clinical relevance of fixation failure after pubic symphysis plating for anterior pelvic ring injuries: an observational cohort study with long-term follow-up

BackgroundOpen reduction and plate fixation is a standard procedure for treating traumatic symphyseal disruptions, but has a high incidence of implant failure. Several studies have attempted to identify predictors for implant failure and discussed its impact on functional outcome presenting conflicting results. Therefore, this study aimed to identify predictors of implant failure and to investigate the impact of implant failure on pain and functional outcome.MethodsIn a single-center, retrospective, observational non-controlled cohort study in a level-1 trauma center from January 1, 2006, to December 31, 2017, 42 patients with a plate fixation of a traumatic symphyseal disruption aged ≥ 18 years with a minimum follow-up of 12 months were included. The following parameters were examined in terms of effect on occurrence of implant failure: age, body mass index (BMI), injury severity score (ISS), polytrauma, time to definitive treatment, postoperative weight-bearing, the occurrence of a surgical site infection, fracture severity, type of posterior injury, anterior and posterior fixation. A total of 25/42 patients consented to attend the follow- up examination, where pain was assessed using the Numerical Rating Scale and functional outcome using the Majeed Pelvic Score.ResultsSixteen patients had an anterior implant failure (16/42; 37%). None of the parameters studied were predictive for implant failure. The median follow-up time was six years and 8/25 patients had implant failure. There was no difference in the Numerical Rating Scale, but the work-adjusted Majeed Pelvic Score showed a better outcome for patients with implant failure.Conclusionimplant failure after symphyseal disruptions is not predictable, but appears to be clinically irrelevant. Therefore, an additional sacroiliac screw to prevent implant failure should be critically discussed and plate removal should be avoided in asymptomatic patients.

Long-term outcomes after surgery for subaxial cervical spine injuries in octogenarians, a matched population-based cohort study

PurposeWe aimed to investigate surgical outcomes in octogenarians with subaxial cervical spine injuries and determine the predictors of complications and mortality.MethodsEligible for inclusion were all patients surgically treated between 2006 and 2018, with either anterior or posterior fixation for subaxial spine injuries. A cohort of octogenarians was identified and matched 1:1 to a corresponding cohort of younger adults. Primary outcomes were perioperative complications and mortality.ResultsFifty-four patients were included in each of the octogenarian and younger groups (median age: 84.0 vs. 38.5). While the risks for surgical complications, including dural tears and wound infections, were similar between groups, the risks of postoperative medical complications, including respiratory or urinary tract infections, were significantly higher among the elderly (p < 0.05). Additionally, there were no differences in operative time (p = 0.625) or estimated blood loss (p = 0.403) between groups. The 30 and 90-day mortality rates were significantly higher among the elderly (p = 0.004 and p < 0.001). These differences were due to comorbidities in the octogenarian cohort as they were revoked when propensity score matching was performed to account for the differences in American Society of Anesthesiology (ASA) grade. Multivariable logistic regression revealed age and ASA score to be independent predictors of complications and the 90-day mortality, respectively.ConclusionsOctogenarians with comorbidities were more susceptible to postoperative complications, explaining the increased short-term mortality in this group. However, octogenarians without comorbidities had similar outcomes compared to the younger patients, indicating that overall health, including comorbidities, rather than chronological age should be considered in surgical decision-making.

Factors Associated With Infection in Patients With Combined Pelvic Ring and Bladder Injuries.

To identify the infection rate in patients with combined pelvic ring and bladder injuries. Secondary aims included identifying treatment and injury factors associated with infection. Retrospective review. Single Level I Tertiary Academic Center. All patients over a 12-year period with combined pelvic ring and bladder injuries were evaluated. Exclusion criteria were nonoperative management of the pelvic ring, isolated posterior fixation, and follow-up <90 days. Primary outcome measured was deep infection of the anterior pelvis requiring surgical irrigation and debridement. In total, 106 patients with anterior stabilization of the pelvis in the setting of a bladder injury were included. Seven patients (6.6%) developed a deep infection and required surgical debridement within 90 days. Patients undergoing open reduction and internal fixation with plating of the anterior pelvis and acute concomitant bladder repair had an infection rate of 2.2% (1/43). Patients undergoing closed reduction and anterior fixation with either external fixation or percutaneous rami screw after bladder repair had an infection rate of 17.6% (3/17). There was a higher infection rate among patients with combined intraperitoneal (IP) and extraperitoneal (EP) bladder injuries (23%) when compared with those with isolated EP (3.8%) or IP (9.1%) bladder injuries (P = 0.029). Acute open reduction and internal fixation of the anterior pelvis in patients with combined pelvic ring and bladder injuries has a low infection rate. Patients with combined IP and EP bladder injuries are at increased risk of infection compared with those with isolated IP and EP injuries. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Reciprocal Changes in Sagittal Spinal Alignment After L5-S1 Anterior Lumbar Interbody Fusion

Degenerative diseases of the lumbar spine decrease lumbar lordosis (LL). Anterior lumbar interbody fusion (ALIF) at the L5-S1 disc space improves segmental lordosis, LL, and sagittal balance. This study investigated reciprocal changes in spinopelvic alignment after L5-S1 ALIF. A retrospective chart review identified patients who underwent L5-S1 ALIF with or without posterior fixation at a single institution (November 1, 2016-October 1, 2021). Changes in pelvic tilt, sacral slope, proximal LL (L1-L4), distal LL (L4-S1), total LL (L1-S1), segmental lordosis, pelvic incidence-LL mismatch, thoracic kyphosis, cervical lordosis, and sagittal vertical axis were measured on preoperative and postoperative radiographs. Forty-eight patients were identified. Immediate postoperative radiographs were obtained at a mean (SD) of 17 (20) days after surgery; delayed radiographs were obtained 184 (82) days after surgery. After surgery, patients had significantly decreased pelvic tilt (15.71° [7.25°] vs 17.52° [7.67°], p=0.003) and proximal LL (11.86° [10.67°] vs 16.03° [10.45°], p<0.001) and increased sacral slope (39.49° [9.27°] vs 36.31° [10.39°], p<0.001), LL (55.35° [13.15°] vs 51.63° [13.38°], p=0.001), and distal LL (43.17° [9.33°] vs 35.80° [8.02°], p<0.001). Segmental lordosis increased significantly at L5-S1 and decreased significantly at L2-3, L3-4, and L4-5. Lordosis distribution index increased from 72.55 (19.53) to 81.38 (22.83) (p<0.001). L5-S1 ALIF was associated with increased L5-S1 segmental lordosis accompanied by pelvic anteversion and a reciprocal decrease in proximal lumbar lordosis. These changes may represent a reversal of compensatory mechanisms, suggesting an overall relaxation of spinopelvic alignment after L5-S1 ALIF.

The development of posterior reduction forceps for atlantoaxial dislocation and its preliminary application in irreducible atlantoaxial dislocation

ObjectiveTo develop posterior reduction forceps for atlantoaxial dislocation and evaluate the preliminary clinical application of this forceps in assisting simple posterior screw-rod system reduction and fixation in the treatment of irreducible atlantoaxial dislocation.MethodsBased on the posterior atlantoaxial screw-rod system, posterior reduction forceps was developed to assist simple posterior screw-rod system for the treatment of irreducible atlantoaxial dislocation. From January 2021 to October 2022, 10 cases with irreducible atlantoaxial dislocation were treated with this technique. The Japanese Orthopaedic Association (JOA) score was applied before and after surgery to evaluate the neurological status of the patient, and the Atlanto-dental interval (ADI) was measured before and after surgery to evaluate the atlantoaxial reduction. X-ray and CT were performed to evaluate internal fixation, atlantoaxial sequence and bone graft fusion during regular follow-up. MRI was performed to evaluate the status of atlantoaxial reduction and spinal cord compression after surgery.ResultsAll 10 patients were successfully operated, and there were no complications such as spinal nerve and vascular injury. Postoperative clinical symptoms were significantly relieved in all patients, and postoperative JOA score and ADI were significantly improved compared with those before surgery (P < 0.05).ConclusionsThe developed posterior reduction forceps for atlantoaxial dislocation can assist the simple posterior screw-rod system in the treatment of irreducible atlantoaxial dislocation to avoid the release in anterior or posterior approach and reduce the difficulty of surgery. The preliminary results of this technique are satisfactory and it has a good application prospect.

Feasibility and safety report on robotic assistance for cervical pedicle screw fixation: a cadaveric study

This cadaveric study aimed to evaluate the safety and usability of a novel robotic system for posterior cervical pedicle screw fixation. Three human cadaveric specimens and C2-T3 were included. Freshly frozen human cadaver specimens were prepared and subjected to robot-assisted posterior cervical pedicle screw fixation using the robotic system. The accuracy of screw placement, breach rate, and critical structure violations were evaluated. The results were statistically compared with those of previous studies that used different robotic systems for cervical pedicle screw fixation. The robotic system demonstrated a high accuracy rate in screw placement. A significant number of screws were placed within predetermined safe zones. The total entry offset was 1.08 ± 0.83 mm, the target offset was 1.86 ± 0.50 mm, and the angle offset was 2.14 ± 0.77°. Accuracy rates comparable with those of previous studies using different robotic systems were achieved. The system was also feasible, allowing precise navigation and real-time feedback during the procedure. This cadaveric study validated the safety and usability of the novel robotic system for posterior cervical pedicle screw fixation. The system exhibited high precision in screw placement, and the results support the extension of the indications for robot-assisted pedicle screw fixation from the lumbar spine to the cervical spine.

Biomechanical Effect of Different Posterior Fixation Techniques on Stability and Adjacent Segment Degeneration in Treating Thoracolumbar Burst Fracture With Osteoporosis: A Finite Element Analysis.

Finite element analysis. To investigate the biomechanical effect of four posterior fixation techniques on stability and adjacent segment degeneration in treating thoracolumbar burst fractures with osteoporosis. In terms of stability and adjacent segment degeneration, there remains no consensus or guidelines on the optimal technique for the treatment of thoracolumbar burst fractures in patients with osteoporosis. Images of CT scans were imported into MIMICS and further processed by Geomagic to build three-dimensional models of the T10-L5 region. A v-shaped osteotomy was performed on the L1 vertebral body to simulate a burst fracture in the setting of osteoporosis. Subsequently, four fixation techniques were designed using SolidWorks software. Range of motion (ROM) of the global spine, ROM distribution, ROM of adjacent segment, Von Mises stress on adjacent intervertebral disks, and facet joints were analyzed. Among the four groups, the cortical bone screw fixation (CBT) showed the highest global ROM at 1.86°, while long-segmented pedicle screw fixation (LSPS) had the lowest global ROM at 1.25°. The LSPS had the smallest percentage of ROM of fractured vertebral body to fixed segment at 75.04%, suggesting the highest stability after fixation. The maximum ROM of the adjacent segment was observed in the CBT at 1.32°, while the LSPS exhibited the smallest at 0.89°. However, the LSPS group experienced larger maximum stress on the adjacent intervertebral disks (9.60MPa) and facet joints (3.36MPa), indicating an increasing risk of adjacent segment disease. LSPS provided the greatest stability, while CBT provided the smallest amount of stability. However, the elevated stress on adjacent intervertebral disks and facet joints after LSPS fixation increased the possibility of adjacent segment degeneration. Cement-augmented pedicle screw fixation (CAPS) and combined cortical bone screw and pedicle screw fixation (CBT-PS) demonstrated significant biomechanical advantages in providing moderate fixation strength while reducing stress on the intervertebral disks and facet joints.

Frequent Sural Nerve Injury with Posterior Approach for Ankle Fracture Fixation.

The purpose of this study was to report the incidence of iatrogenic sural nerve injury in a large, consecutive sample of surgically managed ankle fractures and to identify factors associated with sural nerve injury and subsequent recovery. We hypothesize that a direct posterior approach may be associated with higher risk of iatrogenic sural nerve injury. A retrospective cohort study of 265 skeletally mature patients who sustained ankle fractures over a 2-year period was done. All were treated with open reduction and internal fixation of fractured malleoli. Patient, injury, and treatment features were documented. The presence (n = 26, 9.8%) of sural nerve injury and recovery of sural nerve function were noted. All 26 sural nerve injuries were iatrogenic, occurring postoperatively after open reduction and internal fixation. Patients who sustained sural nerve injuries had more ankle fractures secondary to motor vehicle collisions (23.1% versus 9.2%), more associated trimalleolar fractures (69.2% versus 33.9%), and more Orthopaedic Trauma Association/AO 44B3 fractures (57.7% versus 25.1%), all P < 0.05. A posterior approach to the posterior malleolus through the prone position was used in 20.4% of patients. All 26 of the sural nerve injuries (100%) occurred when the patient was placed prone for a posterior approach, P < 0.001. Therefore, 26 of the 54 patients (48%) treated with a posterior approach sustained an iatrogenic sural nerve injury. 62% of patients had full recovery of sural nerve function with no residual numbness, and patients with nerve recovery had fewer associated fracture-dislocations (23.1% versus 100%, P = 0.003). A posterior approach for posterior malleolus fixation was associated with a 48% iatrogenic sural nerve injury rate, with 62% recovering full function within 6 months of injury. Morbidity of this approach should be considered, and surgeons should be cautious with nerve handling. Level III, Therapeutic.

Finite element analysis of the biomechanical effects of anterior and posterior cervical fusion surgery for bilateral cervical dislocation

Lower cervical spine injuries often manifest as lower cervical vertebral fractures and dislocations, as well as lower cervical facet joint dislocations. Especially in cases of bilateral facet joint dislocations, it is important to rapidly and effectively relieve spinal cord and nerve root compression to prevent secondary spinal cord injury, while also providing reliable and long-lasting stability to the injured segment after surgery. Combined anterior and posterior approaches have the advantages of both pure anterior or posterior approaches, but the actual situation is complex and variable, making systematic theoretical analysis crucial. This study, with bilateral facet joint dislocation of the C6 segment and cervical spinal cord injury as the research background, established a three-dimensional model of the cervical spine C3-C7 after implementing four types of anterior-posterior combined surgeries. The four surgical approaches consist of four combinations: anterior parallel or inclined screw placement combined with posterior Margel or Anderson method screw insertion. Through finite element method, a systematic comparative analysis of the theoretical effects of the four combined surgeries in treating bilateral facet joint dislocation of the cervical spine was conducted. The conclusion was that the variations in the four combined fixation methods have a certain impact on the biomechanical characteristics of the intervertebral disc nucleus. There is a clear mutual influence relationship among anterior and posterior fixation instruments. Based on the model used in this study, it is recommended to use a torque greater than 2.1 nm to tighten the locking nut of the posterior rod to ensure reliable internal fixation.