Accuracy of the novel digital non-cross-arch surgical guides with integration of tooth undercut retention and screw-bone support for implant placement in mandibular free-end.

BACKGROUND: Large cross-arch free-end surgical guides can obscure the visual field, compromising surgical accuracy due to insufficient stability at the free-end. This in vitro study aims to evaluate the accuracy of novel digital non-cross-arch surgical guides designed for implant placement at the mandibular free-end, incorporating tooth undercut retention and screw-bone support. MATERIALS AND METHODS: A mandibular dental model lacking left molars was utilized to fabricate unilateral (cross-arch) tooth-supported surgical guides (GT I, n = 20). Subsequently, two additional types of surgical guides were fabricated: GT II (covering two teeth, n = 20) and GT III (covering three teeth, n = 20). These novel surgical guides were designed to utilize the undercut of the supporting teeth for retention and enhance stability with screw-bone support at the guide's free-end. Furthermore, 60 identical guiding blocks were assembled on the three types of surgical guides to facilitate the implants' insertion. On a phantom head, 120 implant replicas were placed at the Federal Dentaire Internationale (FDI) teeth positions #36 and #37 on the dental model, employing a combination of surgical guides and guiding blocks. To assess accuracy, planned and placed implant positions were compared using intraoral optical scanning. Discrepancies in angulation and linear deviations, including the coronal/apical 3D deviations, lateral deviation as well as depth deviation, were measured. Statistical analysis was performed using two-way ANOVA and Bonferroni test (α = 0.05). RESULTS: GT I exhibited significantly largest discrepancies, including angular and linear deviations at the crest and apex at every implant site. Especially in depth, at implant site #36, the mean deviation value of GT I (0.27 ± 0.13 mm) was twice as large as GT III (0.13 ± 0.07 mm), and almost twice as large as GT II (0.14 ± 0.08 mm). However, at implant site #37, this deviation increased to almost a five-fold relationship between GT I (0.63 ± 0.12 mm) and II (0.14 ± 0.09 mm), as well as between GT I and III (0.13 ± 0.09 mm). No significant discrepancies existed between the novel surgical guides at either implant site #36 or #37. CONCLUSION: This study provides a practical protocol for enhancing accuracy of implant placement and reducing the size of free-end surgical guides used at mandibular molar sites.

Biomechanical changes in the proximal femur before and after removal of femoral neck system.

BACKGROUND: As an innovative internal fixation system, FNS (femoral neck system) is increasingly being utilized by surgeons for the treatment of femoral neck fractures. At present, there have been numerous finite element analysis experiments studying the immediate stability of FNS and CSS in treating femoral neck fractures. However, there is scarce mechanical analysis available regarding the effects post internal fixation removal. This study aimed to investigate the alterations in mechanical parameters of the proximal femur before and after the removal of FNS (femoral neck system), and to assess potential distinctions in indicators following the extraction of CSS (Cannulated Screws). METHODS: A proximal femur model was reconstructed using finite element numerical techniques. The models for CSS and FNS were formulated utilizing characteristics and parametric definitions. The internal fixation was combined with a normal proximal femur model to simulate the healing state after fracture surgery. Within the framework of static analysis, consistent stress burdens were applied across the entirety of the models. The total deformation and equivalent stress of the proximal femur were recorded before and after the removal of internal fixation. RESULTS: Under the standing condition, the total deformation of the model before and after removing CSS was 0.99 mm and 1.10 mm, respectively, indicating an increase of 12%. The total deformation of the model before and after removing FNS was 0.65 mm and 0.76 mm, respectively, indicating an increase of 17%. The equivalent stress for CSS and FNS were 55.21 MPa and 250.67 MPa, respectively. The average equivalent stress on the cross-section of the femoral neck before and after removal of CSS was 7.76 MPa and 6.11 MPa, respectively. The average equivalent stress on the cross-section of the femoral neck before and after removal of FNS was 9.89 MPa and 8.79 MPa, respectively. CONCLUSIONS: The retention of internal fixation may contribute to improved stability of the proximal femur. However, there still existed risks of stress concentration in internal fixation and stress shielding in the proximal femur. Compared to CSS, the removal of FNS results in larger bone tunnels and insufficient model stability. Further clinical interventions are recommended to address this issue.

Improving standard volar plate fixation in 3D-guided corrective osteotomy of the distal radius: evaluation of a shim instrument.

Standard volar plates often do not fit the surface of the malunited distal radius after osteotomy, necessitating an offset angle for accurate volar tilt correction. The correction can be achieved if the plate is held at the correct angle when the distal screws are locked. With the advantage of 3D surgical planning and patient-specific instruments, we developed a shim instrument to assist the surgeon in securing the plate at the intended angle when locking the distal screws, and evaluated radiological results. Five female patients aged 63-74 with dorsally angulated extra-articular malunions underwent surgery using 3D-printed guides and the shim instrument. The plate position, drilling guide alignment, screw placements, and distal radius correction on postoperative CTs were compared with the surgical plans. Errors were measured using an anatomical coordinate system, and standard 2D radiographic measures were extracted. Preoperative dorsal tilt ranged from 16° to 35°, and postoperative volar tilt from 1° to 11°. 3D analysis revealed mean absolute correction errors of 6.1° in volar tilt, 1.6° in radial inclination, and 0.6 mm in ulnar variance. The volar tilt error due to the shim instrument, indicated by the mean angle error of the distal screws to the plate, was 2.1° but varied across the five patients. Settling of the distal radius, due to tension during and after reduction, further contributed to a mean loss of 3.5° in volar tilt. The shim instrument helped with securing plates at the intended angle; however, further correction improvements should consider the tension between the fragments of osteoporotic bone.

Hidden blood loss and the influential factors after minimally invasive treatment of posterior pelvic ring injury with sacroiliac screw.

BACKGROUND: To analyze the perioperative bleeding and hidden blood loss (HBL) of sacroiliac screw minimally invasive treatment of pelvic posterior ring injury and explore the influential factors of HBL after operation for providing reference for clinical treatment. METHOD: A retrospective analysis was conducted on data from 369 patients with posterior pelvic ring injuries treated with sacroiliac screws internal fixation at our hospital from January 2015 to January 2022. The research was registered in the Chinese Clinical Trial Registry in July 2022 (ChiCTR2200061866). The total blood loss (TBL) and HBL of patients were counted, and the factors such as gender, age, and surgical duration were statistically analyzed. The influential factors of HBL were analyzed by multiple linear regression. RESULTS: The TBL was 417.96 ± 98.05 ml, of which the visible blood loss (VBL) was 37.00 ± 9.0 ml and the HBL was 380.96 ± 68.8 ml. The HBL accounted for 91.14 ± 7.36% of the TBL. Gender, surgical duration, fixed position, and fixed depth had significant effects on the HBL (P < 0.05). CONCLUSIONS: The HBL was the main cause of anemia after minimally invasive treatment of posterior pelvic ring injury with a sacroiliac screw. Gender, surgical duration, fixed position, and fixed depth were closely related to the occurrence of HBL. In clinical treatment, we should consider these influential factors and take effective measures to reduce the impact of HBL on patients.

Comparison of No Tap (two-step) and tapping robotic assisted cortical bone trajectory screw insertion.

Workflow for cortical bone trajectory (CBT) screws includes tapping line-to-line or under tapping by 1 mm. We describe a non-tapping, two-step workflow for CBT screw placement, and compare the safety profile and time savings to the Tap (three-step) workflow. Patients undergoing robotic assisted 1-3 level posterior fusion with CBT screws for degenerative conditions were identified and separated into either a No-Tap or Tap workflow. Number of total screws, screw-related complications, estimated blood loss, operative time, robotic time, and return to the operating room were collected and analyzed. There were 91 cases (458 screws) in the No-Tap and 88 cases (466 screws) in the Tap groups, with no difference in demographics, revision status, ASA grade, approach, number of levels fused or diagnosis between cohorts. Total robotic time was lower in the No-Tap (26.7 min) versus the Tap group (30.3 min, p = 0.053). There was no difference in the number of malpositioned screws identified intraoperatively (10 vs 6, p = 0.427), screws converted to freehand (3 vs 3, p = 0.699), or screws abandoned (3 vs 2, p = 1.000). No pedicle/pars fracture or fixation failure was seen in the No-Tap cohort and one in the Tap cohort (p = 1.00). No patients in either cohort were returned to OR for malpositioned screws. This study showed that the No-Tap screw insertion workflow for robot-assisted CBT reduces robotic time without increasing complications.

Comparison of treatment effects between clear aligners and fixed appliances in patients treated with miniscrew-assisted molar distalization.

OBJECTIVES: The biomechanics in achieving molar distalization may differ between fixed appliances and clear aligners in the control of tooth movement. The objective of this study was to compare the treatment effects between clear aligners (CA) and fixed appliances (FA) in patients treated with miniscrew-assisted molar distalization. METHODS: The sample consisted of 46 subjects with mild-to-moderate crowding. A total of 22 patients treated with clear aligners (age, 25.66 ±â€…6.11 years old) and 24 patients treated with fixed appliances (age, 24.04 ±â€…4.95 years old) for miniscrew-assisted molar distalization were included in this study. The dental and skeletal changes were evaluated by the pre- and post-treatment lateral cephalograms. RESULTS: Significant changes were found with the vertical variables SN-OP angle (2.24 ±â€…3.22°, P < .05) and SN-MP angle (0.73 ±â€…1.15°, P < .05) for the FA group when compared with the CA group (SN-OP angle 0.41 ±â€…2.26° and SN-MP angle -0.21 ±â€…1.38°, P > .05). Both treatment groups achieved a 2-3 mm. molar distalization with significant intrusion of the upper molars. The CA group showed significantly less distal tipping of molars (U6^PP angle -2.29 ±â€…3.29° and L6^MP angle -2.92 ±â€…2.49°, P < .05) compared to the FA group (-5.24 ±â€…4.28° and -5.53 ±â€…5.03°, P < .05). In addition, significant retraction and lingual inclination of the upper and lower incisors were found in both groups. LIMITATIONS: The changes of tooth position were evaluated by 2D lateral cephalograms, not 3D measurements. CONCLUSIONS: Compared to fixed appliances, clear aligners seemed to have better control of vertical dimension and distal tipping of molars in patients treated with miniscrew-assisted molar distalization.

Study on the therapeutic effect of Kirschner wire tension band combined with anchor cross-stitch technique in the treatment of comminuted patellar inferopolar fractures.

PURPOSES: Fractures of the inferior patellar pole, unlike other patellar fractures, present challenges for traditional surgical fixation methods. This article introduces the clinical technique and outcomes of using Kirschner wire tension band combined with anchor screw cross-stitch fixation for comminuted inferior patellar pole fractures. METHODS: This retrospective case series study included 14 patients with comminuted inferior patellar pole fractures treated at our institution from September 1, 2020, to April 30, 2022. All patients underwent surgery using the Kirschner wire tension band with anchor screw cross-stitch technique. Follow-up assessments involved postoperative X-rays to evaluate fracture healing, as well as clinical parameters such as healing time, Visual Analog Scale (VAS) scores, range of motion (ROM), and Bostman scores. RESULTS: All patients were followed for an average of over 12 months, with no cases of internal fixation failure. Knee joint stability and function were excellent. X-rays revealed an average healing time of approximately 10.79 ± 1.53 weeks, hospitalization lasted 5.64 ± 1.15 days, surgery took approximately 37.86 ± 5.32 minutes, and intraoperative blood loss was 33.29 ± 8.15 ml. One patient experienced irritation from the internal fixation material. At the final follow-up, the Bostman score averaged 28.29 ± 0.83, knee joint flexion reached 131.07° ± 4.88°, all patients achieved full knee extension, and the VAS score was 0.36 ± 0.63. CONCLUSION: Kirschner wire tension band with anchor screw cross-stitch fixation for comminuted inferior patellar pole fractures delivered satisfactory clinical outcomes. This surgical method, characterized by its simplicity and reliability, is a valuable addition to clinical practice.

Finite element analysis of the stability of retrograde intramedullary nail and plate-screw combinations for periprosthetic femoral fractures following total knee replacement.

OBJECTIVE: Periprosthetic fractures following total knee replacement are rare but challenging. The goal of the treatment is to achieve the most stable fixation that allows early mobilization. Therefore, the aim of this study was to evaluate the biomechanical results of the use of different fixation systems in the treatment of distal femur periprosthetic fractures with finite element analysis. MATERIALS AND METHODS: A total knee prosthesis was implanted in Sawbone femur models. A transverse fracture line was created in the supracondylar region and was fixed in four different groups. In group 1, fracture line fixation was fixed using retrograde intramedullary nailing. In group 2, fixation was applied using a lateral anatomic distal femoral. In group 3, in addition to the fixation made in group 1, a lateral anatomic distal femoral plate was used. In group 4, in addition to the fixation made in group 2, a 3.5 mm Limited Contact Dynamic Compression Plate (LC-DCP) was applied medially. Computed Tomography (CT) scans were taken of the created models and were converted to three-dimensional models. Axial and rotational loading forces were applied to all the created models. RESULTS: The least deformation with axial loading was observed in the double plate group. Group 3 was determined to be more advantageous against rotational forces. The greatest movement in the fracture line was found in group 2. The application of the medial plate was determined to reduce the tension on the lateral plate and increase stability in the fracture line. CONCLUSIONS: Combining a lateral anatomic plate with intramedullary nailing or a medial plate was seen to be biomechanically more advantageous than using a lateral plate or intramedullary nailing alone in the treatment of distal femoral periprosthetic fractures.

Effectiveness of cannulated screw fixation for femoral neck fracture assisted by three-dimensional printing navigation template in middle-aged and elderly patients.

OBJECTIVE: We sought to explore the effectiveness of cannulated screw fixation for femoral neck fractures in middle-aged and elderly patients assisted by a three-dimensional printing navigation template. PATIENTS AND METHODS: A total of 98 middle-aged and elderly patients who underwent cannulated screw fixation for femoral neck fractures were retrospectively analyzed. They were allocated into two groups, each comprising 49 patients. Surgical indexes, hip function, and pain levels were compared between the two groups. RESULTS: The study group, assisted by the three-dimensional printing navigation template, exhibited significantly reduced nail insertion, fewer instances of C-arm fluoroscopy, shorter operation time, quicker time to bone union, earlier initiation of walking exercise, shorter time to weight-bearing walking, and reduced hospital stay than those in the control group (all p<0.001). However, the study group also experienced higher blood loss compared to the control group (p<0.001). Postoperatively, at 3 months and 12 months, the study group demonstrated significantly higher scores compared to the control group (both p<0.001) and reported significantly lower pain scores than that in the other group at 1 week and 12 months post-surgery (both p<0.001). Furthermore, the study group experienced significantly fewer postoperative complications than the control group (p=0.029). CONCLUSIONS: Cannulated screw fixation for femoral neck fractures assisted by a 3D printing navigation template is more effective and safer than traditional fixation methods. This approach represents a promising alternative for surgical management.

Treatment of AVN-Induced Proximal Pole Scaphoid Nonunion Using a Fifth and Fourth Extensor Compartmental Artery as a Vascularized Pedicle Bone Graft: A Retrospective Case Series.

BACKGROUND Scaphoid nonunion (SN) is a challenging condition in wrist pathology, often resulting in severe consequences if left untreated. Surgical intervention, particularly using vascularized bone grafts (VBGs), is a promising but uncertain approach. The 4+5 extensor compartment artery (ECA) pedicled graft, less commonly used for SN, has potential benefits due to its vascular supply and accessibility to the scaphoid. This study aimed to evaluate the effectiveness of the 4+5 ECA pedicled graft combined with headless compression screw fixation in treating avascular necrosis (AVN)-induced proximal pole SN. Radiological results, functional outcomes, and complications related to this method were assessed. MATERIAL AND METHODS This was a retrospective analysis of 19 proximal pole SN cases with AVN treated using the 4+5 ECA-VBG technique from 2016 to 2022. Patients underwent preoperative evaluation and postoperative follow-up for at least 1 year. Data on surgery, demographics, radiological assessments, and functional outcomes were recorded and analyzed statistically. RESULTS All patients achieved radiographic union within 8.5 weeks postoperatively, with revascularization of proximal pole necrosis. Significant improvements in functional outcomes were observed, including pain reduction, increased wrist range of motion, improved grip and pinch strength, and enhanced wrist scores. No major complications were reported. CONCLUSIONS The 4+5 ECA-VBG technique, with headless compression screw fixation, showed high success rates in treating AVN-induced proximal pole SN. This method offers comprehensive restoration of wrist function and minimal complications, making it a viable option for SN management, especially in AVN cases. Further research is needed to confirm these results and establish standardized protocols for SN treatment.

Biomechanical evaluation of reinsertion and revision screws in the subaxial cervical vertebrae.

BACKGROUND: This study aimed to evaluate the biomechanical effects of reinserted or revised subaxial cervical vertebral screws. METHODS: The first part aimed to gauge the maximum insertional torque (MIT) of 30 subaxial cervical vertebrae outfitted with 4.0-mm titanium screws. A reinsertion group was created wherein a screw was wholly removed and replaced along the same trajectory to test its maximum pullout strength (MPOS). A control group was also implemented. The second part involved implanting 4.0-mm titanium screws into 20 subaxial cervical vertebrae, testing them to failure, and then reinserting 4.5-mm revision screws along the same path to determine and compare the MIT and MPOS between the test and revision groups. RESULTS: Part I findings: No significant difference was observed in the initial insertion's maximum insertion torque (MIT) and maximum pull-out strength (MPOS) between the control and reinsertion groups. However, the MIT of the reinsertion group was substantially decreased compared to the first insertion. Moderate to high correlations were observed between the MIT and MPOS in both groups, as well as between the MIT of the first and second screw in the reinsertion group. Part II, the MIT and MPOS of the screw in the test group showed a strong correlation, while a modest correlation was observed for the revision screw used in failed cervical vertebrae screw. Additionally, the MPOS of the screw in the test group was significantly higher than that of the revision screw group. CONCLUSION: This study suggests that reinsertion of subaxial cervical vertebrae screws along the same trajectory is a viable option that does not significantly affect fixation stability. However, the use of 4.5-mm revision screws is inadequate for failed fixation cases with 4.0-mm cervical vertebral screws.

Biportal endoscopy-assisted lateral mass screw fixation using a third portal.

BACKGROUND: The technique of spinal decompression under endoscopy has been widely applied, but reports on endoscopic cervical fixation are rare. The unilateral biportal endoscopic (UBE) technique stands out for its lesser muscle intrusion and more flexible surgical approach. METHOD: We applied the UBE approach for cervical fixation and laminectomy. We achieved bilateral lateral mass screw fixation by making an auxiliary UBE portal combined with the Roy-Camille and Magerl techniques. CONCLUSIONS: Our successful implementation of cervical fixation using the UBE technique at the C3/4 level suggests its efficacy. This approach is a valuable and minimally invasive option for cervical fixation.

Medial Hoffa Fracture: A Case Report and Literature Review of Approach and Management.

BACKGROUND Hoffa fractures are an uncommon form of coronal fracture that impact the femoral condyle. As a result, they are not very prevalent. It is necessary to perform anatomical reduction and rigorous fixation on these fractures; however, there is no consensus among medical professionals on the surgical procedure and implant that would be the most successful in treating these fractures. CASE REPORT A 50-year-old woman who had poliomyelitis in her right lower limb presented with a displaced medial Hoffa fracture of her left knee. She had fallen and was suffering from poliomyelitis. The trauma that caused this fracture had a modest energy level. Open reduction and internal fixation with 2 retrograde cannulated screws were included in her surgical procedure. An approach known as the medial parapatellar route was used for this treatment. As part of her postoperative rehabilitation, she participated in physiotherapy, exercises that did not require weight bearing, exercises that used passive and active assistance, activities that involved partial and full weight bearing, and exercises that involved complete weight bearing. At the 2-year follow-up, the patient's left knee continued to be painless and stable, and it had unrestricted range of motion across the whole extremity. It was determined via radiographs that the fracture had healed without any problems or arthritic changes developing. She was able to walk without help and carry out her daily tasks since she was able to walk with the use of a cane. CONCLUSIONS Retrograde cannulated screws can be a reliable and successful choice for treatment of medial Hoffa fractures, with positive results according to both clinical and radiographic characteristics. Further research is needed to analyze the outcomes over a longer period of time and make comparisons between this technique and others.

[The use of fixed expanders with orthodontic miniscrews support in children with mesial occlusion]. / Ispol'zovanie nes"emnykh rasshiritelei s vnutrikostnoi oporoi u detei s mezial'noi okklyuziei.

OBJECTIVE: Prevention of the development of pronounced skeletal abnormalities in patients with mesial occlusion. MATERIALS AND METHODS: Biometric analysis of control and diagnostic models of dentition was performed in 60 patients with dental anomalies before and after treatment in 3 mutually perpendicular planes to identify violations in the formation of dental arches by sagittal and transversal dimensions, and alveolar processes - by vertical dimensions (methods of A. Pont, G. Korkhaus). Measurements of 23 parameters of TRG and sections of CBCT were carried out using the modified Nad-Ars technique with analysis of skeletal parameters before and after treatment. Treatment was carried out using dilators for the upper jaw in combination with a facial mask and further dynamic observation using active retention devices. RESULTS: The results of treatment showed an increase in the length of the anterior segment of the upper dental arch by 2.8±0.55 mm (p<0.05 mm); expansion in the area of temporary molars by 2.85±0.65 mm (p<0.05); in the area of permanent molars by 2.75±0.55 mm (p<0.05); in the area of the apical basis of HF by 3.82±0.45 mm (p<0.05). The length of the lower dental arch in the anterior segment has not changed. Analysis of TRG parameters showed a significant increase in the values of

The effect of Ding's screws and tension band wiring for treatment of olecranon fractures: a biomechanical study.

Although tension band wiring (TBW) is popular and recommended by the AO group, the high rate of complications such as skin irritation and migration of the K-wires cannot be ignored. Ding's screw tension band wiring (DSTBW) is a new TBW technique that has shown positive results in the treatment of other fracture types. The objective of this study was to evaluate the stability of DSTBW in the treatment of olecranon fractures by biomechanical testing. We conducted a Synbone biomechanical model by using three fixation methods: DSTBW, intramedullary screw and tension band wiring (IM-TBW), and K-wire TBW, were simulated to fix the olecranon fractures. We compared the mechanical stability of DSTBW, IM-TBW, and TBW in the Mayo Type IIA olecranon fracture Synbone model using a single cycle loading to failure protocol or pullout force. During biomechanical testing, the average fracture gap measurements were recorded at varying flexion angles in three different groups: TBW, IM-TBW, and DSTBW. The TBW group exhibited measurements of 0.982 mm, 0.380 mm, 0.613 mm, and 1.285 mm at flexion angles of 0°, 30°, 60°, and 90° respectively. The IM-TBW group displayed average fracture gap measurements of 0.953 mm, 0.366 mm, 0.588 mm, and 1.240 mm at each of the corresponding flexion angles. The DSTBW group showed average fracture gap measurements of 0.933 mm, 0.358 mm, 0.543 mm, and 1.106 mm at the same flexion angles. No specimen failed in each group during the cyclic loading phase. Compared with the IM-TBW and TBW groups, the DSTBW group showed significant differences in 60° and 90° flexion angles. The mean maximum failure load was 1229.1 ± 110.0 N in the DSTBW group, 990.3 ± 40.7 N in the IM-TBW group, and 833.1 ± 68.7 N in the TBW group. There was significant difference between each groups (p < 0.001).The average maximum pullout strength for TBW was measured at 57.6 ± 5.1 N, 480.3 ± 39.5 N for IM-TBW, and 1324.0 ± 43.8 N for DSTBW. The difference between maximum pullout strength of both methods was significant to p < 0.0001. DSTBW fixation provides more stability than IM-TBW and TBW fixation models for olecranon fractures.

[Intraoperative slide rail CT assistance in percutaneous sacroiliac joint screws for the treatment of pelvic posterior ring injury].

OBJECTIVE: To compare the clinical efficacy of intraoperative slide rail CT combined with C-arm X-ray assistance and just C-arm for percutaneous screw in the treatment of pelvic posterior ring injury. METHODS: A retrospective analysis was performed on the patient data of 76 patients with posterior pelvic ring injury admitted to the Department of Orthopedic Trauma from December 2018 to February 2022. Among them, 39 patients in the CT group were treated with C-arm combined with slide rail CT-assisted inline fixation including 23 males and 16 females with an average age of (44.98±7.33) years old;and the other 37 patients in the C-arm group were treated with intraline fixation treatment under only C-arm fluoroscopy including 24 males and 13 females with an average age of (44.37±10.82) years old. Among them, 42 patients with anterior ring fractures were treated with percutaneous inferior iliac spines with internal fixation (INFIX) or suprapubic support screws to fix the anterior pelvic ring. Postoperative follow-up time, operation time, complications of the two groups were compared. Results of Matta reduction criteria, Majed efficacy evaluation, the CT grading and the rate of secondary surgical revision were compared. RESULTS: The nailing time of (32.63±7.33) min in CT group was shorter than that of (52.95±10.64) min in C-arm group (t=-9.739, P<0.05). The follow-up time between CT group (11.97±1.86) months and C-arm group (12.03±1.71) months were not statistically significant(P>0.05). The postoperative complication rates between two groups were not statistically significant (χ2=0.159, P>0.05). Results of Matta reduction criteria (Z=2.79, P<0.05), Majeed efficacy evaluation(Z=2.79, P<0.05), CT grading (Z=2.83, P<0.05) in CT group were better than those in C-arm group(P<0.05); the secondary surgical revision rate in the CT group was significantly lower than that in the C-arm group (χ2=5.641, P<0.05). CONCLUSION: Compared with traditional C-arm fluoroscopy, intraoperative slide rail CT combined with C-arm assisted percutaneous sacroiliac joint screw placement surgery has the characteristics of short operation time, high accuracy and safety, and significant decrease in postoperative secondary revision rate, and is one of the effective methods for re-establishing the stability of the posterior ring of pelvic fracture.

[Short term follow-up of femoral neck dynamic cross screw system and threaded cannulated screw in the treatment of vertically unstable femoral neck fractures].

OBJECTIVE: To analyze and compare the clinical effects of femoral neck dynamic cross screw system (FNS) and cannulated screws(CS) in the treatment of vertically unstable femoral neck fractures. METHODS: The clinical data and short-term follow-up results of 40 patients with vertically unstable femoral neck fractures admitted from July 2020 to August 2021 were retrospectively analyzed. According to different internal fixation methods, 40 patients were divided into two groups, 20 cases in FNS group included 11 males and 9 females with a median of 58.5(50.3, 62.5) years old, and 20 in CS group included 9 males and 11 females with a median of 52.0(40.5, 58.0) years old. The operation time, knife edge length, blood loss and treatment cost of two gruops were observed and compared. The postoperative fracture healing and internal fixation were evaluated with X-ray imaging data, and the femoral neck shortening of the affected side was measured. The incidence of thigh irritation, the time of partial weight bearing and full weight bearing, early necrosis of femoral head, reoperation revision and Harris scores were compared between two groups. RESULTS: FNS group was followed up for 18.0(15.0, 19.0) months, CS group for 17.0(15.0, 18.8) months. There was no significant difference in operation time, incision length and blood loss between two groups(P>0.05). The cost of diagnosis and treatment in FNS group was higher than that in CS group(P<0.001). In FNS group, there was no irritation sign of the affected side thigh, while in CS group, there were 6 cases with discomfort or irritation sign of the lateral thigh(P<0.05). The average time of partial weight bearing activity in CS group was later than that in FNS group(P<0.05); However, there was no significant difference in the activity time of complete weight bearing between two groups(P=0.011>0.05). At the last follow-up, the shortened length of the affected femoral neck in CS group was greater than that in FNS group(P<0.05). There was no early necrosis of femoral head and reoperation in both groups. There was no significant difference in Harris score between two groups 12 months after operation(P>0.05). CONCLUSION: FNS treatment of vertically unstable femoral neck fractures can significantly reduce the incidence of lateral thigh irritation sign, and effectively reduce the postoperative shortening rate of vertically unstable femoral neck fractures, which can provide a relatively stable anti rotation force and anti cutting force, so that patients can go to the ground relatively early, which is conducive to the recovery of the affected hip joint function after surgery. It is a new option for the surgical treatment of vertically unstable femoral neck fractures. However, due to the high cost of treatment, In clinical practice, appropriate surgical treatment is selected according to the actual situation.

Evaluation of the horizontal approach to the medial malleolar facet in sagittal talar fractures through dorsiflexion and plantarflexion positions.

BACKGROUND: Talar fractures often require osteotomy during surgery to achieve reduction and screw fixation of the fractured fragments due to limited visualization and operating space of the talar articular surface. The objective of this study was to evaluate the horizontal approach to the medial malleolus facet by maximizing exposure through dorsiflexion and plantarflexion positions. METHODS: In dorsiflexion, plantarflexion, and functional foot positions, we respectively obtained the anterior and posterior edge lines of the projection of the medial malleolus on the medial malleolar facet. The talar model from Mimics was imported into Geomagic software for image refinement. Then Solidworks software was used to segment the medial surface of the talus and extend the edge lines from the three positions to project them onto the "semicircular" base for 2D projection. The exposed area in different positions, the percentage of total area it represents, and the anatomic location of the insertion point at the groove between the anteroposternal protrusions of the medial malleolus were calculated. RESULTS: The mean total area of the "semicircular" region on the medial malleolus surface of the talus was 542.10 ± 80.05 mm2. In the functional position, the exposed mean area of the medial malleolar facet around the medial malleolus both anteriorly and posteriorly was 141.22 ± 24.34 mm2, 167.58 ± 22.36mm2, respectively. In dorsiflexion, the mean area of the posterior aspect of the medial malleolar facet was 366.28 ± 48.12 mm2. In plantarflexion, the mean of the anterior aspect of the medial malleolar facet was 222.70 ± 35.32 mm2. The mean overlap area of unexposed area in both dorsiflexion and plantarflexion was 23.32 ± 5.94 mm2. The mean percentage of the increased exposure area in dorsiflexion and plantarflexion were 36.71 ± 3.25% and 15.13 ± 2.83%. The mean distance from the insertion point to the top of the talar dome was 10.69 ± 1.24 mm, to the medial malleolus facet border of the talar trochlea was 5.61 ± 0.96 mm, and to the tuberosity of the posterior tibiotalar portion of the deltoid ligament complex was 4.53 ± 0.64 mm. CONCLUSIONS: Within the 3D model, we measured the exposed area of the medial malleolus facet in different positions and the anatomic location of the insertion point at the medial malleolus groove. When the foot is in plantarflexion or dorsiflexion, a sufficiently large area and operating space can be exposed during surgery. The data regarding the exposed visualization area and virtual screws need to be combined with clinical experience for safer reduction and fixation of fracture fragments. Further validation of its intraoperative feasibility will require additional clinical research.

The effect of different hybrid rigid internal fixation techniques on the postoperative stability following a mandibular advancement using a bilateral sagittal split ramus osteotomy: A retrospective three-dimensional comparative study.

OBJECTIVE: To three-dimensionally evaluate post-operative mandibular stability following bilateral sagittal split ramus osteotomies between hybrid and non-hybrid rigid internal fixation techniques. MATERIALS AND METHOD: Seventy adults with skeletal class II deformity who underwent bilateral split sagittal osteotomy with mandibular advancement were included. Patients were divided into four groups based on their fixation techniques: hybrid technique (HT) groups I, II, and IV received a 4-hole 2 mm miniplate with either a bicortical screw (BS), additional 2 mm 4-hole miniplate, or two-hole miniplate, while non-HT group III received a 4-hole 2 mm miniplate with four mini-screws (MS). Measurements were taken pre-operatively (T0), immediately postoperatively (T1), and ≥1 year after surgery (T2) using 3D Slicer software. RESULTS: Age, sex, and follow-up period did not correlate significantly with postoperative relapse or stability. Significant differences were observed in the advancement on the right side between groups II, III, and IV and on the left side between groups I, III, and IV. However, the type of surgical intervention showed no significant effect on postoperative relapse and stability. All groups of fixations showed satisfactory stability with irrelevant relapse (< 2 mm or 2°). CONCLUSION: The study demonstrated satisfactory and comparable stability among different fixation groups on patients undergoing mandibular advancement following bilateral split sagittal osteotomy. The results highlighted the importance of considering the degree of advancement when planning orthognathic surgery and managing postoperative outcomes.

Image fusion-based low-dose CBCT enhancement method for visualizing miniscrew insertion in the infrazygomatic crest.

Digital dental technology covers oral cone-beam computed tomography (CBCT) image processing and low-dose CBCT dental applications. A low-dose CBCT image enhancement method based on image fusion is proposed to address the need for subzygomatic small screw insertion. Specifically, firstly, a sharpening correction module is proposed, where the CBCT image is sharpened to compensate for the loss of details in the underexposed/over-exposed region. Secondly, a visibility restoration module based on type II fuzzy sets is designed, and a contrast enhancement module using curve transformation is designed. In addition to this, we propose a perceptual fusion module that fuses visibility and contrast of oral CBCT images. As a result, the problems of overexposure/underexposure, low visibility, and low contrast that occur in oral CBCT images can be effectively addressed with consistent interpretability. The proposed algorithm was analyzed in comparison experiments with a variety of algorithms, as well as ablation experiments. After analysis, compared with advanced enhancement algorithms, this algorithm achieved excellent results in low-dose CBCT enhancement and effective observation of subzygomatic small screw implantation. Compared with the best performing method, the evaluation metric is 0.07-2 higher on both datasets. The project can be found at: https://github.com/sunpeipei2024/low-dose-CBCT .