Independent volumetric internal fixation reduces posterior column acetabular fracture site motion as compared to plate/screw construct: A biomechanical analysis.

Aims & objectives: To establish whether a suprapectineal pelvic reconstruction plate and posterior column screw (P&S) construct or a single 6.5-mm cannulated posterior column screw (PCS) construct demonstrates greater mechanical stability for fixation of acetabulum fractures involving the posterior column (PC). We hypothesized that the PCS construct would result in less fracture site motion. Materials & methods: Twelve fourth-generation composite hemipelvi were utilized, 6 for each construct. The P&S construct consisted of a suprapectineal pelvic reconstruction plate with two 3.5-mm posterior column screws crossing the fracture site in lag-by-technique fashion and two screws anchoring the plate to the sciatic buttress. The PCS construct consisted of a single 6.5-mm partially threaded cannulated screw placed in an antegrade fashion. Both fixation models were cyclically loaded at 0.5 cycles/second at 400N and 800N, first in a sit-to-stand position that is expected during recovery, and subsequently in a squat-to-stand position to test overload conditions. Results: Under sit-to-stand loading, the PCS construct resulted in less motion at the fracture site than the P&S construct (0.06 ± 0.02 mm vs 0.1 ± 0.02 mm at 400N, p = 0.02; 0.13 ± 0.03 mm vs 0.19 ± 0.04 mm at 800N, p = 0.03). The PCS construct also demonstrated less fracture site motion under squat-to-stand loading (0.22 ± 0.13 mm vs 1.9 ± 0.5 mm at 400N, p = < 0.001; 1.48 ± 0.44 mm vs 4.77 ± 0.3 mm at 800N, p = < 0.001). At 800 N, half of the repairs failed during squat-to-stand loading (2 PCS, 4 P&S). Conclusion: Fixation of the posterior column of the acetabulum with a 6.5-mm cannulated screw demonstrated comparable fracture motion upon loading compared to the plate and screw construct.

Investigation of the appropriate thread depth for bioabsorbable screws.

The relatively low strength of bioabsorbable screws is a critical clinical issue. A shallower thread depth will increase a screw's strength, but the pull-out strength of the screw will decrease proportionally with the thread depth. We sought to provide further clarification of the relationships between (i) the thread depth and the pull-out strength, and (ii) the minor diameter and the shearing and bending strengths in bioabsorbable screws made of uncalcined and unsintered hydroxyapatite particles and poly-L-lactide (u-HA/PLLA). Seven types (thread depth from 0.1-0.7 mm) of screws with a major diameter of 4.5 mm were manufactured. Each screw type's pull-out strength was investigated using simulated bone. A shearing test and three-point bending test were both used to measure the physical strength of the screws. We then analyzed the relationships between the mechanical findings and the thread depth. The relationship between the thread depth and the pull-out strength showed a positive biphasic linear correlation with a boundary at 0.4-mm thread depth. The relationships between the minor diameter and both the shearing and bending strengths showed positive linear correlations within the range of dimensions tested. Within the scope of this study, a 0.4-mm thread depth proved to be an appropriate value that provides sufficient pull-out strength and screw strength for u-HA/PLLA screws with a 4.5-mm major diameter.

Comparison of three implant systems under preload loss: A finite element analysis validated by digital image correlation methods.

PURPOSE: This study evaluated the effects of screw preload loss on three implant systems, both in silico and in vitro. METHODS: Three finite element analysis (FEA) models of implant restorations were created using bone-level (BL, 4.8×12 mm; BLX, 4.5×12 mm) and tissue-level (TL, 4.8×12 mm) implant systems. The screws in each group were subjected to preloads of 100 N and 200 N, with an additional 130 N load applied to the crown tops. An in vitro study of the principal strain was conducted using digital image correlation (DIC) under the same conditions as for the FEA models. The results were evaluated for von Mises stress, principal strain, and sensitivity index. RESULTS: During loading, the highest stress levels were observed in the implants and screws. In the BL group, the screws experienced the highest von Mises stress at 466.04 MPa and 795.26 MPa in the 100 N and 200 N groups, respectively. The BLX group showed the highest von Mises stress at 439.33 MPa and 780.88 MPa in the implants in the 100 N and 200 N groups. Sensitivity analysis revealed that the screws and abutments in the TL group were significantly more affected by the preload changes. CONCLUSIONS: The abutment in the TL group was particularly sensitive to preload changes compared with those in the BL and BLX groups. Variations in the preload significantly affect the stress distribution in implants and screws. Maintaining screw preload stability under loading is crucial in clinical practice to prevent mechanical failure.

Stress Analysis of Periodontal Tissue in en Masse Retraction With Integration of Maxillary Anterior Teeth: A Three-Dimensional Finite Element Method Study.

OBJECTIVE: To simulate the en masse traction technique with the integration (EMTI) of six maxillary anterior teeth using a finite element model (FEM) and explore various protocols for maxillary protrusion. The study aimed to investigate root displacement and stress distribution in the periodontal ligament (PDL) by varying the retraction position and direction of EMTI applied to the maxillary anterior teeth. No actual participants were involved. MATERIALS AND METHODS: The FEM model included six teeth (central and lateral incisors and canines) with a PDL thickness of 0.3 mm. The model encompassing the alveolar bone (ALB) and EMTI had 180,528 elements and 47,836 nodes. The EMTI integrated six anterior teeth via a 0.9-mm-diameter stainless steel lingual wire, equipped with three moment arms extending toward the root apex: one midline (central arm) and two distal to the canines (lateral arms). The position and direction of the traction force applied to the three moment arms of the EMTI were varied to assess crown and apex displacement, as well as PDL stress. RESULTS: Lingual tipping was consistent across all protocols, emphasizing controlled incisor tipping. The application of horizontal traction at 10 mm and traction at 7 mm from the central and lateral arms of the EMTI, respectively, demonstrated the most uniform stress distribution across the PDL of all six anterior teeth. CONCLUSIONS AND CLINICAL SIGNIFICANCE: The FEM analysis results suggest that the new EMTI method, which retracts the maxillary anterior teeth as a unit, is effective for tooth movement and PDL stress distribution. The EMTI technique, with its specific traction protocols and emphasis on controlled tipping, appears to be a promising approach for addressing maxillary protrusions.

Impact of landmark crater creation on improving accuracy of pedicle screw insertion in robot-assisted scoliosis surgery.

PURPOSE: This study evaluated the impact of the Landmark Crater (LC) method on pedicle perforation rates in robot-guided surgery for pediatric scoliosis for each pedicle diameter. METHODS: Seventy-six scoliosis patients underwent robot-assisted posterior spinal fusion. The cohort consisted of 19 male and 57 female patients, with a mean ± standard deviation age of 17.5 ± 7.7 years and a preoperative Cobb angle of 57.0 ± 18.5°. The LC method is a method in which craters that serves as a landmark are created in advance at the planned PS insertion site of all pedicles within the intraoperative CT imaging area. The patients were divided into the LC group, in which PS insertion was performed using the LC method, and the control group using the conventional PS insertion method. Overall and pedicle perforation rates for each pedicle outer diameter were compared between the groups by Fisher's exact test. RESULTS: The LC group exhibited a significantly lower pedicle major perforation rate than did the control group (2.7% vs. 6.2%, P = 0.001). The perforation rates in pedicles with a pedicle outer diameter > 6 mm, 4-6 mm, 2-4 mm, and < 2 mm were 0.61%, 1.6%, 5.1%, and 21%, in the LC group and 0.75%, 4.1%, 12%, and 50% in the control group, respectively. CONCLUSION: In robot-assisted surgery for pediatric scoliosis, the LC method enabled significantly lower pedicle perforation rates over the conventional method. Both the LC and conventional methods exhibited higher perforation rates for smaller pedicle diameters.

Accuracy of Cervical Pedicle Screw Insertion With and Without a Navigation-Linked High-Speed Drill: A Retrospective Clinical Study.

INTRODUCTION: Cervical pedicle screw (CPS) fixation provides high stability but poses a risk of nerve and vascular injury. Although useful for reducing CPS deviation rates, navigation systems cannot completely eliminate deviation. This study aimed to compare two methods for creating insertion paths, one using a navigation-linked high-speed drill (NAVI drill) and the other using conventional manual probing. METHODS: Our study comprised 104 patients with 509 CPSs at the C3-6 level who were treated at our institution between 2017 and 2023. CPS deviations were graded according to the Neo classification system, and the deviation direction (medial, lateral, cranial, or caudal) was assessed. Complications associated with CPS deviation were also investigated. We compared cases that used the NAVI drill (Group M) with those that used manual probing (Group N). RESULTS: Group M included 45 cases (252 screws), and Group N included 59 cases (257 screws). The CPS deviation rate was grade 1 or higher in 14.7% and 17.1% of cases in Groups M and N, respectively (p = 0.469). It was grade 2 or higher in 1.2% and 4.3% of cases in Groups M and N, respectively (p = 0.222). The medial, lateral, caudal, and cranial deviation direction rates were 56.8%, 2.7%, 40.5%, and 0% in Group M and 13.6%, 72.7%, 11.4%, and 2.3% in Group N, respectively (p < 0.001). In one case in Group N, a grade 3 lateral deviation resulted in vertebral artery injury (VAI). CONCLUSIONS: The use of the NAVI drill was associated with a slightly lower, albeit insignificant, CPS deviation rate. However, it significantly lowered the proportion of lateral deviations. Therefore, the NAVI drill is a useful tool for preventing VAI.

Biomechanical study of the stability of posterior cervical expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation: a finite element analysis.

BACKGROUND: Posterior cervical expansive open-door laminoplasty (EODL) may cause postoperative C5 palsy, and it can be avoided by EODL with bilateral C4/5 foraminotomy. However, prophylactic C4/5 foraminotomy can compromise cervical spine stability. To prevent postoperative C5 palsy and boost cervical stability, We propose a new operation method: EODL combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation. However, there are no studies on the biomechanical properties of this surgery. PURPOSE: Evaluating the biomechanical characteristics of EODL combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation and other three classic surgery. METHODS: An original model (A) and four surgical models (B-E) of the C2-T1 vertebrae of a female patient were constructed. (B) EODL; (C) EODL combined with bilateral C4/5 foraminotomy; (D) C3-6 expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation; (E) C3-6 expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and C3-6 lateral mass screw system. To compare the biomechanical properties of cervical posterior internal fixation; (E) C3-6 expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and C3-6 lateral mass screw system. To compare the biomechanical properties of cervical posterior internal fixation methods, six physiological motion states were simulated for the five models using a 100N load force and 1.5Nm torque. The biomechanical advantages of the four internal fixation systems were evaluated by comparing the ranges of motion (ROMs) and maximum stresses. RESULTS: The overall ROM of Model C outperformed the other four models, reaching a maximum ROM in the extension state of 10.59°±0.04°. Model C showed a significantly higher ROMs of C4/5 segment than other four models. Model D showed a significantly lower ROM of C4/5 segment than both Model B and Model C. Model E showed a significantly lower ROM of C4/5 segment than Model D. The stress in the four surgical models were mainly concentrated on the internal fixation systems. CONCLUSION: EODL combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation can maintain the stability of the spine and has minimal effects on the patient's cervical spine ROMs in the extension and flexion state. As a result, it may be a promising treatment option for cervical spondylotic myelopathy (CSM) to prevention of postoperative C5 palsy.

The Effect of Osteopenia and Osteoporosis on Screw Loosening in MIS-TLIF and Dynamic Stabilization.

STUDY DESIGN: Retrospective series. OBJECTIVE: Screw loosening in the surgical treatment of lumbar spine disease is a major complication of osteopenia or osteoporosis. This study investigated the risk of screw loosening following either MIS-TLIF or pedicle screw-based dynamic stabilization (DS) in patients with osteopenia or osteoporosis. METHODS: We retrospectively enrolled patients receiving 1- or 2-level MIS-TLIF or DS in a single institute. All patients were diagnosed as having lumbar spondylosis without concurrent spondylolisthesis and found by dual-energy X-ray absorptiometry to have osteopenia or osteoporosis. Screw loosening was identified by X-ray and CT. Clinical outcomes were also assessed. RESULTS: A total of 103 patients (50 MIS-TLIF and 53 DS) were confirmed to have osteopenia (-2.5

Elderly trochanteric fracture outcomes: Unveiling the risks of excessive postoperative sliding - A retrospective multicenter (TRON group) investigation.

BACKGROUND: Intramedullary nailing (IMN) for femoral trochanteric fractures (FTF) is the primary surgical intervention. Excessive lag screw sliding (ES) of the femoral neck screw sometimes occurs. This multicenter investigation sought to 1) determine the prevalence of ES, 2) evaluate the relationship between ES and postoperative complications, and 3) identify the factors of ES in elderly patients with FTF undergoing IMN. METHODS: From 2016 to 2020, 1448 patients with FTF were treated using a short IMN across 11 institutions (TRON group). Upon applying exclusion criteria, 519 patients (127 men, 392 women; mean age, 84.4 years) were included. The postoperative sliding distance was measured immediately after surgery and at final follow-up. A sliding distance of ≥8 mm categorized patients as having ES. We identify the factors contributing to ES using the logistic regression analysis, with a p < 0.05 as statistical significance. RESULTS: ES was observed in 116 patients (22.4 %). Patients with ES had a higher incidence of postoperative cut-out and peri-implant fracture. Logistic regression analysis showed that achieving optimal reduction in both AP and lateral views (odds ratio (OR) 0.48, p = 0.0012) and the use of a double screw system or twin screws with integrated locking mechanism significantly reduced the risk of ES (OR 0.27, 0.17; p = 0.0027, <0.001). CONCLUSIONS: The incidence rate of ES was 22.4 %. ES was associated with a higher risk of postoperative complications. The surgeons should aim for optimal reduction and use a double screw or twin screws with an integrated interlocking mechanism as the implant of choice.

Management of Rarest Type of Talus Fracture: A Case Report.

This is a case of the rarest type of talus fracture in a 28-year-old male who presented with pain in his right ankle and foot following a road traffic accident. He was unable to bear weight or walk after the injury. Imaging studies indicated fractures in the head and neck of the talus, as well as the talar dome, with a fracture line extending into the subtalar joint. The patient underwent open reduction and internal fixation using mini fragment plating and Herbert screw fixation for the osteochondral fragment. Both the intraoperative and postoperative periods were without complications. The patient was placed in plaster of Paris (POP) slab immobilization for four weeks and was advised to avoid weight-bearing while using a walker for eight weeks, after which physiotherapy commenced. Follow-up assessments showed satisfactory fracture union, good range of motion in the ankle, an excellent American Orthopedic Foot and Ankle Society (AOFAS) score, an excellent 17-Italian Foot Function Index (FFI) score, and a good Hawkins score.

Trends in management of odontoid fractures 2010-2021.

Background Context: Odontoid fractures are relatively common. However, the literature is unclear how these fractures are best managed in many scenarios. As such, care is varied and poorly characterized. Purpose: To investigate the trends and predictive factors of surgical versus nonsurgical treatment and anterior versus posterior stabilization of odontoid fractures. Study Design/Setting: Retrospective database cohort study. Patient Sample: Adult patients with odontoid fractures between 2010 and 2021. Outcome Measures: Yearly trends and predictors of odontoid fracture management. Methods: Adult patients with odontoid fractures were abstracted from the large, national, administrative M161Ortho Pearldiver dataset. For operative versus nonoperative care of odontoid fractures, yearly rates were determined (since 2016 based on coding limitations). For anterior versus posterior stabilization, yearly rates were determined (2010-2021). Univariate and multivariable analyses were performed for both sets of comparisons. Results: For assessment of nonsurgical versus surgical management from 2016 to 2021, a total of 42,754 patients with odontoid fracture were identified, of which surgical intervention was done for 7.9%. Predictive factors of surgical intervention included being managed by a neurosurgeon (OR:1.29), being from Midwest United States (OR:1.35 relative to West), male sex (OR:1.20), and decreasing age (OR: 0.82 per decade) (p < .001 for each). Of those undergoing surgical intervention, 33.6% had anterior surgery while 66.4% had posterior surgery (anterior surgery decreased from 36.4% in 2010 to 27.2% in 2021, p < .001). Predictive factors of undergoing anterior versus posterior approach include having a neurosurgeon surgeon (OR:1.98), being from the Southern (OR:1.61 relative to Northeast), and having Medicare insurance (OR: 1.31) (p < .001 for each). Conclusions: The overall rate of surgery for odontoid fractures has remained similar over the past years. Of those undergoing surgery, less are being done from anterior. While these decisions were predicted by some clinical factors, both also correlated with nonclinical factors suggesting room for more consistent algorithms.

Functional Outcomes of a Dynamic Condylar Screw for Unstable Femoral Intertrochanteric Fractures in Patients Above 50.

BACKGROUND: Hip fractures are among the most common fractures encountered in the emergency departments by orthopedic trauma teams. The optimal treatment method and implant choice for unstable intertrochanteric fractures are subject to debate, with various options available, including intramedullary and extramedullary implants. METHODS: In this descriptive cross-sectional study, the researchers examined patients with unstable intertrochanteric fractures (classified as 31A2 according to the AO Foundation/Orthopaedic Trauma Association (AO/OTA) classification) who had undergone open reduction and internal fixation with a 95° dynamic condylar screw (DCS). The study was conducted at the Gezira Centre for Orthopedic Surgery and Traumatology (GCOST) during the latter half of 2022. Functional outcomes were assessed using the modified Harris Hip Score (mHHS). RESULTS: A total of 30 patients were enrolled in this study, with a mean age of 73 ± 12.27 years. Of these, 11 (36.7%) were male, and 19 (63.3%) were female. The mHHS was 73.6 ± 14.654. Among the surveyed patients, seven (23.3%) reported poor outcomes, 13 (43.3%) reported fair outcomes, six (20%) reported good outcomes, and four (13.3%) reported excellent outcomes. The Kruskal-Wallis test revealed statistically differences in mean mHHS scores between gender groups (p = 0.024) and between age groups (p = 0.04). However, no significant differences were found across different modes of trauma groups (p = 0.73), affected hip groups (p = 0.35), comorbidity groups (p = 0.84), or postoperative complication groups (p = 0.06). CONCLUSION: Our study found that DCS treatment for unstable intertrochanteric fractures yielded acceptable functional outcomes, making it a viable and effective treatment option.

Corrigendum: Outcomes of olecranon fractures in adolescents: comparison of tension band wiring and Herbert screw fixations.

[This corrects the article DOI: 10.3389/fped.2023.1269628.].

Magnetic Resonance Imaging-Based Vertebral Bone Quality Score for Prediction of Cage Subsidence and Screw Loosening in Patients Undergoing Degenerative Lumbar Surgery: A Meta-analysis.

OBJECTIVE: Poor bone quality is a risk factor for postoperative complications after degenerative lumbar fusion surgery. The magnetic resonance imaging-based vertebral bone quality (VBQ) score is a good tool for assessing bone quality, and this is the first meta-analysis performed to summarize the predictive value of the VBQ score for cage subsidence and screw loosening in patients undergoing degenerative lumbar surgery. METHODS: Studies were comprehensively searched in electronic databases. The quality of the studies was assessed. The pooled sensitivity, specificity and summary receiver operating characteristic curve were calculated. Publication bias was assessed and meta-regression was conducted. RESULTS: We ultimately included 9 studies with a total of 1,404 patients with a mean age of 60.4 years and a percentage of females of 57.0%. According to the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies 2) tool to assess methodological quality, the quality of the included studies was relatively low and risks of bias might exist. Results showed that a high VBQ was significantly associated with cage subsidence and screw loosening, and risk factor analysis revealed that the merged odds ratio was 5.37 for cage subsidence and 3.87 for screw loosening. With a VBQ cutoff value of 3.34±0.45, the pooled sensitivity and specificity for the diagnosis of postoperative complications were 0.75 and 0.75, respectively, and the area under the curve was 0.82 (95% confidence interval, 0.78-0.85). CONCLUSION: A high VBQ was associated with a high risk of cage subsidence and screw loosening in patients who underwent degenerative lumbar surgery. The VBQ score could be considered for identifying high-risk patients for further evaluation.

A novel technique for C1-C2 posterior screw insertion using patient-specific guides created by CT-based 3D printing.

C1-C2 fixation has been developed for the rigid fusion of atlantoaxial instability. C1 lateral mass screw (C1 LMS)-C2 pedicle screw fixation is used more frequently due to its rigid fixation and high bone fusion rate. However, C1 screw placement is relatively unsafe even with recently developed image-based navigation systems. Patient-specific screw guide templates (PSGT) were developed to improve the accuracy and safety of C1 screw placement. Herein, we investigated the outcomes of the C1-C2 posterior fixation technique using PSGT. This was a retrospective study of six patients who underwent posterior cervical spinal fusion using the PSGT between January 2022 and April 2023. Operative time, estimated blood loss, intraoperative radiation dose, surgical cost, and screw placement accuracy were evaluated and compared with those achieved with preoperative CT-based navigation (navigation group, n = 15). Screw accuracy was assessed using Neo's classification. PSGT showed good results, although the differences were not statistically significant (operation time: 104.3 ± 9.7 min vs 116.4 ± 20.8 min; estimated blood loss: 56.7 ± 72.4 mL vs 123.2 ± 162.3 mL; and radiation dose: 1.8 ± 1.2 mSv vs 2.6 ± 0.8 mSv, respectively). PSGT was particularly better in terms of the accuracy of C1 LMS (PSGT: 100%, navigation: 83.3%). The deviation at the entry point was minimal, and the difference between the sagittal and transversal angles from the preoperative plan was small. We investigated the clinical efficacy of using the PSGT for C1-C2 posterior fixation. PSGT improved the accuracy of C1 LMS insertion.

Preventing Proximal Radio-Ulnar Joint Screw Penetration during Coronoid Fracture Fixation: A 3D-Digital Modeling and Cadaver Study.

Objective: Intra-articular screw penetration is a probable complication of coronoid fracture fixation. The present study aimed to determine the best radiography technique for visualizing the proximal radioulnar joint (PRUJ) space. Moreover, it aimed to determine the safe angle and length of the screw to avoid PRUJ penetration during coronoid fracture fixation. Methods: The Mimics software was used to construct a three-dimensional model of a healthy man's forearm from a computer tomography scan. It was analyzed using the Solidworks software to determine the X-ray angle that clearly showed the PRUJ space to detect penetration of screws from the coronoid process into the PRUJ and determine the maximum screw angle and length that could be used without intra-articular penetration. To verify these findings, a cadaveric study combined with radiographs was conducted. Results: To visualize PRUJ space, the optimal X-ray angle was 13º lateral to the perpendicular line when the forearm was positioned at full supination. If the coronoid process was segmented into zones 1 (closest to the radioulnar joint) to 4 (farthest from the joint), the screw could only be inserted at a right angle in zone 1. In zones 2, 3, and 4, inclination angles less than 15, 35, and 60 would prevent intra-articular penetration, respectively. Conclusions: The X-rays could visualize the PRUJ space with an anteroposterior radiograph at an angle of 13º ulnar deviation from the perpendicular plane. During coronoid process fracture fixation, shorter screws with less lateral inclination were safer when inserting screws in the zones of the coronoid process adjacent to the PRUJ.

A complete facet resection and cervical pedicle screw placement enhances both gross total resection and motion preservation for the cervical spinal dumbbell tumor.

OBJECTIVE: To describe single-index-level fusion surgery using a cervical pedicle screw (CPS) after the complete facet resection of spinal dumbbell tumors and to compare it with partial facet resection without fusion. METHODS: We retrospectively reviewed patients who underwent surgery for dumbbell-shaped cervical spine tumors. They were categorized into the fused group (complete facet resection with fusion using CPS) and the unfused group (partial facet resection without fusion). We compared demographics, tumor characteristics, resection rates (gross total, subtotal, or partial), and regrowth rates between the groups. Complete facet resection was performed for maximal tumor removal. In the fused group, single-index-level fusion was achieved using CPS. Despite tumor-associated erosion of the index vertebra's pedicle and/or lateral mass, the CPS was directly inserted into the vertebral body through an imaginary virtual pedicle without a lateral mass or pedicle purchase. RESULTS: A total of 34 patients underwent surgery for dumbbell-shaped cervical tumors; half were classified into each group. There were no significant differences in demographic or tumor characteristics, including Asazuma classification, or histological diagnosis (P > 0.05). However, the gross total resection rate was significantly higher in the fused group (16/17, 94.1% vs 9/17, 52.9%; P-value = 0.011). Tumor recurrence was observed in three (17.6%) patients in the unfused group; no recurrence (0%) occurred in the fused group. CONCLUSION: Complete facet resection with fusion using CPS significantly increased the gross total tumor removal rate, compared with partial resection without fusion. Therefore, CPS improved fusion surgery for maximal motion preservation, resulting in single-level fusion surgery.

Ultrasonography-guided canal decompression combined with vertebroplasty and cement-augmented pedicle screw fixation for stage III Kümmell's disease with neurological deficits: a retrospective cohort study.

BACKGROUND: Percutaneous vertebroplasty or kyphoplasty is the preferred procedure for stage I and II Kümmell's diseases (KDs), but there exist controversies on the operative option of stage III KD. This study aimed at exploring the safety and efficacy of ultrasonography-guided canal decompression (UG-CD) combined with vertebroplasty and cement-augmented pedicle screw fixation (CA-PSF) for treating stage III KD with neurological deficit (ND). METHODS: Between September 2017 and December 2023, all patients who received the UG-CD combined with vertebroplasty and CA-PSF for managing stage III KD with NDs were reviewed retrospectively with their demographic and operation data, and complications recorded. Besides, the scores of Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI), together with imaging data including the kyphotic Cobb angle (KCA), wedge angle (WA), spinal canal area (SCA) at the narrowest level as well as anterior (AHR) and middle (MHR) height ratios were measured and compared between pre- and post-operation. RESULTS: A total of eleven patients with a mean age of 70.09 ± 2.98 years old were included in our study with their surgical time, hospitalization length, blood loss, and follow-up time being 150.91 ± 17.94 min, 202.09 ± 39.95 ml, 8.18 ± 1.17 days, and 16.91 ± 4.09 months, respectively. During the final follow-up, the KCA, WA, VAS scores, ODI scores, AHR, MHR, and SCA were significantly improved (P < 0.01). Intraoperatively, one case suffered a transient decrease in the motor evoked potential. Another case experienced a cerebrospinal fluid leakage postoperatively that was then successfully treated. CONCLUSION: UG-CD combined with vertebroplasty and CA-PSF could be a feasible procedure for safely and effectively handling stage III KD with NDs.

Analysis on the related factors of misplacement of freehand pedicle screws via posterior approach in degenerative scoliosis.

BACKGROUND: To study the risk factors associated with misplacement of freehand pedicle screws through a posterior approach for degenerative scoliosis. METHODS: A total of 204 patients who underwent posterior pedicle screw-rod system surgery for degenerative scoliosis in our hospital from December 2020 to December 2023 were retrospectively analyzed. Patient demographics, radiographic accuracy, and surgery-related information were recorded. RESULTS: A total of 204 patients were included. A total of 2496 screws were placed. 2373 (95.07%) were in good position. Misplacement screws were 123 (4.93%). None of the patients had postoperative spinal nerve symptoms due to screw malposition. The misplacement rate of thoracic (T10-T12) pedicle screws was 11.11% (60/540). Misplacement of pedicle screws in the lumbar spine (L1-L5) was 3.22% (63/1956). Age, gender, surgeon, and operation time had no significant effect on misplacement of pedicle screws (P>0.05). Body mass index, Hu value, number of screw segments, Cobb angle, vertebral rotation, and spinal canal morphology had some correlation with pedicle screw misplacement. Among them, BMI, Hu value, number of screw segments, Cobb angle, and vertebral rotation grade were independent risk factors for PS misplacement (P<0.05). The height of the posterior superior iliac spine had a significant effect on pedicle screw misplacement in the lower lumbar spine (L4/5) (P<0.05). CONCLUSION: BMI, Hu value, number of screw levels, Cobb angle, and vertebral rotation grade were independent risk factors for pedicle screw misplacement in patients with degenerative scoliosis. Posterior superior iliac spine height has a large impact on PS placement in the lower lumbar spine. Patients with degenerative scoliosis should be preoperatively planned for the size and direction of the placed screws by X-ray and CT three-dimensional, to reduce the misplacement rate of pedicle screws.