Screw Fixation Research Articles

The Bony Density of the Pedicle Plays a More Significant Role in the Screw Anchorage Ability Than Other Regions of the Screw Trajectory.

Osteoporosis is a crucial risk factor for screw loosening. Our studies indicate that the bone mineral density (BMD) in the screw trajectory is a better predictor of screw loosening than the BMD of the lumbar spine or the screw insertion position. Research has shown that anchorage on the screw tip is the most significant factor for screw anchorage ability, while others argue that decreased bony quality in the pedicle poses a significant risk for screw loosening. This study aimed to determine whether the bony quality of the screw tip, pedicle, or screw-anchored vertebral body plays the most significant role in screw anchorage ability. A total of 73 patients who underwent single-segment bilateral pedicle screw fixation, along with posterior and transforaminal lumbar interbody fusion (PLIF and TLIF), from March 2019 to September 2020 were included in this retrospective study. The Hounsfield unit (HU) value of the fixed vertebral bodies, the entire screw trajectory, screw tip, screw-anchoraged vertebral body, and pedicles were measured separately. Data from patients with and without screw loosening were compared, and regression analyses were conducted to identify independent risk factors. Additionally, the area under the curve (AUC) values were computed to assess the predictive performance of different parameters. Furthermore, fixation strength was calculated in numerical models with varying bony densities in different regions. HU values were found to be significantly lower in the loosening group across most measuring methods (HU values in the pedicle, 148.79 ± 97.04, 33.06 ± 34.82, p < 0.001). Specifically, the AUC of screw loosening prediction was notably higher when using HU values of the pedicle compared to other methods (AUC in the pedicle > 0.9 and in the screw insertion position > 0.7). Additionally, computational results for fixation strength revealed a clear decline in screw anchorage ability in models with poor BMD in the pedicle region. Pedicle bone quality plays a more significant role in screw anchorage ability than that in other regions. The innovation of bony augmentation strategies should pay more attention to this region to optimize the screw anchorage ability effectively.

Restoring mobility: roles of percutaneous consolidation for pelvic ring bone lesions-a multicenter study.

This study aimed to assess the early functional rehabilitation outcomes following percutaneous consolidation for pelvic ring tumor lesions. In this multicenter retrospective study, patients with pelvic bone tumor lesions, whether primitive or metastatic, underwent percutaneous consolidation (cementoplasty, screw fixation, or both). The primary outcome was postoperative weight-bearing ambulation. Secondary outcomes included hospitalization duration, procedural complications, and long-term consolidation. Inclusion criteria were patients treated for prophylactic consolidation or pathological fractures. Kaplan-Meier analysis was used for the primary outcome and hospital stay, with p-values < 0.05 indicating significance. A total of 143 consecutive procedures were performed in 138 patients (mean age, 65 years ± 13; 68 men) who underwent percutaneous screw fixation, cementoplasty, or both. Postoperative weight-bearing ambulation was achieved in 142/143 cases (99%). In total, 117/143 (82%) of these were in the first 24 h. 81/143 (57%) were discharged within 24 h (median, one day; Q3, one day; Q4, 112 days). 133/138 (96.5%) patients achieved long-term consolidation. The most common pattern was isolated acetabular involvement (N = 40; 28%). Of the 19 adverse events, 10 were asymptomatic. Three patients had delayed infections and one required screw removal. Percutaneous consolidation effectively achieved postoperative weight-bearing ambulation and represents a safe and durable treatment option for patients with pelvic bone lesions. ClinicalTrials.gov: NCT06155890. Question How can radiology continue to help improve care for patients with metastatic pelvic ring lesions? Findings 99% of patients achieved postoperative weight-bearing, with 82% doing so within 24 h. Clinical relevance Percutaneous consolidation enabled rapid functional rehabilitation of oncology patients, allowing short hospital stays with low complication rates, and demonstrating the expanding role of radiologists in diagnosis, risk assessment, and treatment planning, thereby enhancing patient care.

Axis screw parallel to the sagittal plane versus traditional pedicle screw in the treatment of atlantoaxial fixation: a finite element study.

This study aims to conduct a finite element analysis (FEA) to assess the bio-mechanical properties of C2 sagittal-parallel pedicle screw (PPS) in fixation for atlantoaxial instability, thereby providing a theoretical foundation for its clinical application. A total of 5 intact C1-2 finite element models were established. Based on this, instability models were developed and two different fixation methods were applied for each model: C1 lateral mass screw (LMS) combined with C2 sagittal-parallel pedicle screw (C1LMS + C2PPS), and C1 lateral mass screw combined with C2 traditional pedicle screw (C1LMS + C2PS). Under a physiological load of 40N, a pure moment of 1.5 Nm was used to simulate movements of the cervical spine in flexion, extension, lateral bending, and axial rotation. The von Mises stress of implants and the segment range of motion (ROM) were analyzed and compared statistically. The intact model was validated and showed good consistency with other studies in terms of range of motion (ROM). In flexion and extension, the C1LMS + C2PPS resulted in lower segment ROM (12.4% and 6.3% decrease) and stress concentration (15.9% decrease in flexion) compared to C1LMS + C2PS. However, in lateral bending and axial rotation, the C1LMS + C2PPS exhibited higher segment ROM (42.9% and 5.9% increase) and stress concentration (8.7% and 21.4% increase) compared to C1LMS + C2PS. Both methods were safe and stable for the fixation of atlantoaxial instability. Compared to C1LMS + C2PS, the use of C1LMS + C2PPS may provide better stability and a lower risk of implant failure in flexion and extension. Clinically, it is feasible to utilize the C2 sagittal-parallel pedicle screw in fixing atlantoaxial instability.

Enhancing Pedicle Screw Fixation Training: A Novel Approach Using Head-Mounted Devices for Video-Assisted Debriefing

BackgroundVideo-assisted debriefing (VAD) is promising for medical skill training, but its effectiveness requires further exploration. The aim of this study was to investigate the effectiveness of point-of-view VAD in spinal surgery training. MethodsForty surgical residents were randomly divided into control and video-assisted (VA) groups, both of which underwent pedicle screw fixation procedures while being graded by a consulting surgeon in terms of their technical skills (primary outcome). On the second day, both groups received verbal debriefing and coaching from a senior consultant surgeon; for the VA group, this step was performed while watching a recorded point-of-view video of the procedure alongside the resident surgeon. Both groups then underwent a new testing round and participated in a questionnaire survey regarding their debriefing experience. ResultsAfter the debriefing session, the residents in the VA group had significantly greater technical skills than did those in the control group did (37±9.7 vs. 25±8.5, p<0.001). The VAD method was better than the traditional method in terms of steps such as recognizing anatomical structures, piloting holes in the bone, tapping, screw insertion and judging the location of the pedicle screws. ConclusionsVAD is more effective than traditional verbal debriefing for improving residents’ surgical skills, particularly for obtaining a more comprehensive understanding of anatomical structures, imitating detailed surgical techniques as well as promoting initiative. However, in terms of mastery of surgical skills, VAD is not significantly beneficial for tactile perception of the surrounding tissue, indicating that a certain amount of practice is still necessary.

Palmar Plate Fixation in Scaphoid Nonunions—Surgical Technique and Review of the Literature

AbstractEven today, the treatment of scaphoid nonunions remains challenging for the treating hand surgeon. Considering the biomechanical principles of wrist kinematics, especially the three-dimensional movement of the scaphoid, it is evident that a single headless compression screw does not provide sufficient stability to counteract all these forces, particularly rotational forces. Palmar plate fixation was initially introduced as a salvage procedure after failed screw fixation. It ensures very high rotational stability but also supports correction of the humpback deformity, reconstruction of scaphoid length, and prevents bone graft extrusion. However, indications have since been extended to include primary nonunion treatment in cases with humpback deformity or comminuted fractures. Even in recalcitrant cases (substantial bone loss, prior surgery failure, avascular necrosis, or durations exceeding 2 years), high union rates and favorable functional outcomes have been reported. This article attempts to summarize the biomechanical principles, indications, surgical techniques, and results following palmar angular stable plate fixation in scaphoid nonunions.

A case report on the comprehensive management of recurrent fractures in polyostotic Paget’s disease

Paget’s disease of the bone is a chronic and long-lasting disorder that causes bones to grow larger and become weaker than normal. Pelvis, skull, spine, and leg bones are the most commonly affected bones and Paget’s disease affects just one or a few bones from the skeletal system. This metabolic bone disease does not come with specific symptoms and the people affected are found with no symptoms in some scenarios. However, bone changes occur which can result in ostealgia or osteodynia, malformed and fragile bones prone to recurrent fractures, tumors, inflammation, and arthritis in the joints close to the affected bones. At times, Paget’s illness is discovered by incident during a routine X-ray or blood test. The symptoms can be managed with surgical interventions and medications which improve pain and control the effects of the disease. The exact factor causing the condition is unknown but some factors contributing may include genetic, lifestyle factors, such as poor diet, or bone injury in early life which may trigger the development of Paget’s disease. Our case report explicates about a 70-year-old male patient who had an alleged history of slip and fall at home and sustained an injury to the right thigh and leg. The patient was a known case of Paget’s disease who underwent dynamic hip screw fixation surgery for right femur in the former hospital admission. This case report elaborates on the medical management with calcium and vitamin supplements along with bone modifying agents and surgical intervention proceeded in the recurrent fractures with the underlying mechanism of the illness.

Management of Hypertrophic non-Union After Isolated Fibular Shaft Fracture With Percutaneous Screw Fixation: A Case Report

Management of Hypertrophic non-Union After Isolated Fibular Shaft Fracture With Percutaneous Screw Fixation: A Case Report

Percutaneous sacroiliac screw fixation with a 3D robot-assisted image-guided navigation system

Abstract Objective Presentation and description of percutaneous sacroiliac (SI) screw fixation with the use of a 3D robot-assisted image-guided navigation system and the clinical outcome of this technique. Indications Pelvic fractures involving the posterior pelvis. Contraindications Patients not suited for surgery. Surgical technique Planning the screws on the diagnostic computer tomogram (CT). Matching with a low-dose CT in the operating room. Lateral incision. Verify the guidewire position with the personalized inlet and outlet views. After correct positioning, place a cannulated screw over the guidewire. For fragility fractures, augmentation is recommended. Finish the surgery with a final 3D scan to confirm correct placement of the screws and cement. Postoperative management Direct postoperative mobilization with pain-adapted full weight-bearing. Results Data of 141 patients between January 2018 and August 2022 were analyzed (average age 82 ± 10 years, 89% female). Most of the fractures were type II fragility fractures of the pelvis (FFP; 75%). The median hospital stay was 12 ± 7 days and the median surgery duration for a unilateral SI screw was 26 min. In total 221 S1 screws and 17 S2 screws were applied. No screws showed signs of loosening or migration. Of the five suboptimally placed screws, one screw was removed due to sensory impairment. All patients with cement leakage remained without symptoms. Conclusion The surgical technique with the use of a 3D robot-assisted image-guided navigation system is a technique for safe fixation of dorsal fragility fractures of the pelvis and is associated with fewer complications.

Comparison of mechanical stability of modified pedicle screw fixator and unilateral lumbopelvic fixation for treating sacroiliac joint disruption: A finite element analysis study.

This study aimed to investigate the mechanical stability of a modified pedicle screw fixator and compare it with unilateral lumbopelvic fixation for treating sacroiliac joint disruption using finite element simulation technology. The digital model of a normal spine-pelvis-femur containing the main pelvic and lumbar ligaments was established based on computed tomography images. A sacroiliac joint disruption model was built and validated, which was stabilized with the models of a modified pedicle screw fixator or unilateral lumbopelvic fixation. A 400 N follower loading was applied to the lumbar vertebrae for the 2 fixation models to analyze displacement and stress distribution. In addition, the construct stiffness was calculated. The peak amounts of sacral vertical displacement, horizontal displacement, posterior displacement, and overall displacement were 0.70 mm, 0.17 mm, 0.73 mm, and 0.88 mm, respectively, in the modified pedicle screw fixator model, which were less than those in the unilateral lumbopelvic fixation model (1.17 mm, 0.31 mm, 2.21 mm, and 2.29 mm, respectively). Compared with unilateral lumbopelvic fixation, the percentage decreases of the modified pedicle screw fixators were 40.2%, 45.2%, 67.0%, and 61.6%, respectively. The peak stress of the internal fixation and pelvis in the modified pedicle screw fixator model was 351.23 MPa and 39.91 MPa, which has 15.5% and 70.4% lower than in the unilateral lumbopelvic fixation model. The construct stiffness of the modified pedicle screw fixator (571 N/ mm) was 67% better than that of unilateral lumbopelvic fixation (342 N/mm). The finite element simulation results showed that the modified pedicle screw fixator model demonstrated smaller sacral displacement, fewer stresses on the internal fixation and bone, and higher construct stiffness compared with the unilateral lumbopelvic fixation model. Thus, the modified pedicle screw fixator may provide biomechanical advantages over unilateral lumbopelvic fixation in the treatment of sacroiliac joint disruption.

Clinical outcomes of arthroscopic suture fixation combined with loop plate vs. posterior approach open reduction and cannulated screw fixation for treating tibial avulsion fractures of the posterior cruciate ligament: a retrospective study.

Comparison of the efficacy of arthroscopic suture fixation combined with loop plate vs. the posterior approach involving open reduction and intramedullary nail fixation in treating posterior cruciate ligament tibial avulsion fractures (PCLTAFs). A retrospective analysis was conducted on the clinical data of patients diagnosed with PCLTAF who were admitted to Northern Jiangsu People's Hospital between June 2019 and March 2022. Based on distinct surgical procedures, the patients were categorized into two groups: arthroscopic group (33 cases), involving a single bone tunnel, high-strength suture, loop plate, and anchor screw fixed under arthroscopy, and open reduction and internal fixation (ORIF) group (13 cases), involving a modified posterior medial approach and fixation using 1-2 cannulated screws. Key parameters, including surgical duration, postoperative fracture alignment, fracture-healing duration, range of motion changes, postoperative Lysholm scores, and VAS scores were documented and compared between the two groups. The study cohort comprised 46 patients, with 28 males and 18 females, and the median age was 29 years old (range: 15-69). There were no significant differences in the baseline characteristics, including knee Lysholm scores, between the two groups. The arthroscopic group exhibited significant improvement in all eight Lysholm score indicators (all P < 0.001). The total Lysholm score also exhibited significant improvement before and after surgery in both groups (P < 0.001). Following surgery, the arthroscopic group demonstrated improvements in all indicators, but had a slightly longer operating time compared to the ORIF group. No significant differences were observed in the Lysholm scores for the knee joint between the two patient groups before and after surgery (P > 0.05). Arthroscopic suture fixation in conjunction with looped plate binding can significantly improve knee function and clinical effect for patients in the treatment of PCLTAF, promotingearly postoperative functional recovery of patients.

Evaluation of Preoperative Factors That Affect the Alpha Angle of Screw Insertion After the Open Latarjet Procedure.

The open Latarjet procedure yields excellent results as a treatment for anterior shoulder instability. The position of the bony fragment and the insertion angle of the screw (the alpha angle) are critical factors for a successful procedure. The alpha angle is considered overangulated at >25°, which is associated with poor bone fixation and healing. To assess preoperative patient anatomic factors that affect the alpha angle in the Latarjet procedure for anterior shoulder instability. Case-control study; Level of evidence, 3. In this retrospective study, 76 patients who underwent the open Latarjet procedure between October 2009 and December 2023 were included. Postoperative computed tomography scans were reviewed for the alpha angle, and patients were classified into 2 groups: group 1 (alpha angle ≥25°) and group 2 (alpha angle <25°). Preoperative patient characteristics and radiological parameters obtained from preoperative computed tomography scans were analyzed and compared between groups 1 and 2. We developed a novel method to measure the depth of the chest and the angle between the deltopectoral interval and the plane of screw insertion. We also measured the thickness of the pectoralis major and subscapularis muscles. Of the 76 patients in this study, 41 and 35 patients were included in groups 1 and 2, respectively. The mean alpha angles of groups 1 and 2 were 36° and 12°, respectively, and the body mass index was significantly higher in group 1 (P < .001). In addition, group 1 had a significantly longer distance from the anterior edge of the glenoid to the skin margin of the deltopectoral interval (P < .001). The angle between the deltopectoral interval and the plane of screw insertion (traction angle) was significantly larger in group 1 (P < .001), and the pectoralis major and subscapularis muscles were thicker in group 1 (P = .017 and P = .032, respectively). The alpha angle after the Latarjet procedure was strongly related to the patient's weight, body mass index, depth of the chest, and the angle between the deltopectoral interval and the plane of screw insertion. To our knowledge, this is the first study in which the preoperative factors that facilitate proper screw fixation in the Latarjet procedure are reported.

GelMA encapsulating BMSCs-exosomes combined with interference screw or suture anchor promotes tendon-bone healing in a rabbit model

The tendon-bone junction (TBJ), a critical transitional zone where tendons and bones connect, is particularly prone to injury due to the forces from muscle contractions and skeletal movements. Once tendon-bone injuries occur, the complex original tissue structure is difficult to restore, increasing the risk of re-tear. In this study, we initially established a rabbit model of tendon-bone injury and treated it using either interference screw or suture anchor. Biomechanical testing demonstrated the maximum tension and strength of TBJ with interference screw fixation were superior. However, histologic and immunohistochemical results showed more tissue regeneration and expression of cartilage markers at the site of injury with suture anchor fixation. Moreover, Gelatin Methacryloyl encapsulated with exosomes from mesenchymal stem cell (GelMA-exosomes) were prepared, showing a consistent and stable exosome release characteristic. The combined application of GelMA-exosomes with either interference screws or suture anchors further enhanced the healing of tendon-bone injuries, which may be achieved by promoting cellular proliferation as well as regulating the decreased expression of local pro-inflammatory factors IL-1β, IL-6 and TNF-α and increased expression of anti-inflammatory factors IL-10 and TGF-β. This provides a viable therapeutic strategy to enhance tendon-bone healing.

Experimental study of fractures of the posterior pelvic ring C1.1 using LC-II screws and internal fixation by plate

IntroductionTo compare the biomechanical outcomes of C1.1 posterior pelvic ring fractures treated with different numbers of LC-II screws and plate internal fixation.Materials and methodsNine adult preserved pelvic specimens were used. After being measured by bone densitometry, the specimens were randomly divided into 3 groups of 3 pelvic specimens each. The C1.1 pelvic fractures were generated by iliac osteotomies and anterior pelvic ring osteotomies. The fractures were fixed and randomly divided into three groups: (1) one LC-II screw, (2) two LC-II screws, and (3) two reconstruction plates. The anterior pelvic rings were all fixed with pubic branch screws. A biomechanical testing machine loaded all specimens vertically, recording the displacement and ultimate load of the specimens to quantify the stiffness.ResultsWhen loads up to 1000 N were applied, the displacement of the iliac bone was close between the one LC-II screw and the two LC-II screw group specimens; (P > 0.05); when loads such as 1000 N, 1200 N and 1400 N were applied, there was no significant difference in displacement between the plate fixation group and the two LC-II screw fixation group (P > 0.05), both of which were superior to the one LC-II screw fixation group (P < 0.05). There was no significant difference in compressive stiffness between the two LC-II screw fixation groups and the plate fixation group (P > 0.05), and both were superior to the one LC-II screw fixation group (P < 0.05) the ultimate load of both the two LC-II screws and the steel plate is greater than that of one LC-II screw (1.74 times the ultimate load of one LC-II screw for the two LC-II screws and 1.83 times the ultimate load of one LC-II screw for the steel plate).ConclusionFor posterior pelvic ring fractures of type C1.1, placement of two LC-II screws provides comparable posterior pelvic ring stability compared to reconstructed plates. At loads below 1000 N, one LC-II screw fixation and two LC-II screws were comparable in restoring posterior pelvic ring stability.

Effectiveness of sacroiliac screw implantation assisted by three-dimensional printed faceted honeycomb guide plate in treatment of posterior pelvic ring fracture

To investigate the effectiveness of sacroiliac screw implantation assisted by three-dimensional (3D) printed faceted honeycomb guide plate in the treatment of posterior pelvic ring fracture. The clinical data of 40 patients with posterior pelvic ring fractures treated with sacroiliac screw implantation between December 2019 and December 2022 were retrospectively analyzed. Among them, 18 cases were treated with sacroiliac screws fixation assisted by 3D printed faceted honeycomb guide plate (guide plate group), and 22 cases were treated with sacroiliac screws percutaneously fixation under fluoroscopy (conventional group). There was no significant difference in baseline data ( P>0.05) such as gender, age, time from injury to operation, and Dennis classification between the two groups. The implantation time, frequency of C-arm X-ray fluoroscopy, frequency of guide pin adjustment of each sacroiliac screw, and postoperative complications and bone healing were recorded. Majeed score was used to evaluate the functional recovery at 6 months after operation, and CT was used to observe whether the screw penetrated the bone cortex. The deviation between the virtual position and the actual position of the screw tip, the sacral foramen, and the screw entry point was measured on the sagittal CT images of the guide plate group. The number of screws implanted in S 1 and S 2 vertebral bodies was 14 and 16 respectively in the guide plate group, and 17 and 18 respectively in the conventional group. The implantation time of each sacroiliac screw, the frequency of C-arm X-ray fluoroscopy, and the frequency of guide pin adjustment in S 1, S 2, and all vertebrae in the guide plate group were significantly less than those in the conventional group ( P<0.05). Patients in both groups were followed up 8-48 months, with an average of 19.7 months. There was no incision infection, screw displacement, or internal fixation loosening in both groups. Callus growth was observed in all patients at 12 weeks after operation, and bone healing was achieved in all patients. The healing time ranged from 12 to 24 weeks, with an average of 15.7 weeks. No sacroiliac screw penetrated the bone cortex in the guide plate group; 2 patients in the conventional group had sacroiliac screws penetrating the bone cortex without damaging blood vessels or nerves. In the guide plate group, the deviation between the virtual position and the actual position of the screw tip, the sacral foramen, and the screw entry point were (2.91±1.01), (2.10±0.74), and (1.67±0.70) mm, respectively, with an average deviation of (2.19±1.22) mm. There was no significant difference in Majeed function evaluation between the two groups at 6 months after operation ( P>0.05). The application of 3D printed faceted honeycomb guide plate in sacroiliac screw implantation for posterior pelvic ring fracture can shorten the screw implantation time, reduce the frequency of fluoroscopy and guide pin adjustment, and reduce the risk of screw penetration through the bone cortex.

How I do it: spine jack expansion kyphoplasty for AO spine A4 complete burst fracture with neurological deficit.

Some patients suffering from thoracolumbar complete burst fracture causing neurological deficit may be eligible for single-stage posterior-only three column reconstruction with spine jack expansion kyphoplasty. Short segment monoaxial pedicle screws are placed. Spine jack working channels are positioned in the comminuted vertebral body. Then, the surgeon can perform jack expansion kyphoplasty and short-segment fixation and distraction in the order best suited, considering whether the collapsed vertebral body has been expanded thanks to hyperlordosis positioning. This strategy allows to regain both native vertebral body height and proper regional sagittal balance. Wide decompression with laminectomy and arthrectomy is necessary at the level of posterior wall recession. Combination of short segment pedicle screw fixation with distraction and open spine jack kyphoplasty is technically feasible and avoids the need for corpectomy in complete burst fractures with neurological deficit.

Effectiveness of unilateral biportal endoscopy technique combined with percutaneous pedicle screw fixation in treatment of lumbar burst fractures

To compare the effectiveness of unilateral biportal endoscopy (UBE) technique assisted spinal canal decompression combined with percutaneous pedicle screw internal fixation versus traditional open decompression and internal fixation for treatment of lumbar burst fractures. A retrospective study was conducted on the clinical data of 61 patients with single-segment lumbar burst fractures who met the selection criteria and were admitted between October 2022 and December 2023. Of them, 25 patients received UBE technique assisted decompression combined with percutaneous pedicle screw fixation (UBE group), while 36 patients were treated with traditional posterior unilateral hemilaminectomy decompression and internal fixation (open group). There was no significant difference in baseline data between the two groups ( P>0.05), including gender, age, body mass index, fracture segment, cause of injury, AO classification of lumbar fractures, and preoperative height ratio of the anterior margin of injured vertebra, segmental kyphosis angle, rate of spinal canal invasion, the classification of American Spinal Injury Association (ASIA) grading, visual analogue scale (VAS) score, and Oswestry disability index (ODI). The operation time, intraoperative blood loss, and postoperative complications were recorded and compared between the two groups. VAS score, ODI, and ASIA grading were used to evaluate the effectiveness before operation, at 1 week after operation, and at last follow-up. Lumbar anteroposterior and lateral X-ray films and CT were performed to measure the segmental kyphosis angle, height ratio of the anterior margin of injured vertebra, and the rate of spinal canal invasion. Surgery was successfully completed in both groups. No complication such as dural sac, nerve root, or vascular injury was found during operation, and all incisions healed by first intention. There was no significant difference in operation time between the two groups ( P>0.05), the UBE group revealed significant less intraoperative blood loss when compared with open group ( P<0.05). Patients in both groups were followed up 6-20 months, with an average of 13 months. There was no loosening, breakage, or failure of internal fixation in all patients. The ASIA grading, VAS score, ODI of the two groups significantly improved at 1 week after operation and further improved at last follow-up ( P<0.05). There was no significant difference in ASIA grading at 1 week after operation and last follow-up between the two groups ( P>0.05), but the VAS score and ODI in the UBE group were significantly superior to the open group ( P<0.05). At 1 week after operation, the height ratio of the anterior margin of injured vertebra, segmental kyphosis angle, rate of spinal canal invasion significantly improved when compared to preoperative ones ( P<0.05), the height ratio of the anterior margin of injured vertebra and segmental kyphosis angle significantly decreased at last follow-up when compared to the values at 1 week after operation ( P<0.05), but the rate of spinal canal invasion was further significantly improved, and there was no significant difference between the two groups at different time point postoperatively. UBE technique assisted spinal canal decompression combined with percutaneous pedicle screw fixation is a safe and effective treatment for lumbar burst fractures, which with little trauma and faster recovery when compared with traditional open decompression and internal fixation.

Inclusion of Muscle Forces Affects Finite Element Prediction of Compression Screw Pullout but Not Fatigue Failure in a Custom Pelvic Implant

Custom implants used for pelvic reconstruction in pelvic sarcoma surgery face a high complication rate due to mechanical failures of fixation screws. Consequently, patient-specific finite element (FE) models have been employed to analyze custom pelvic implant durability. However, muscle forces have often been omitted from FE studies of the post-operative pelvis with a custom implant, despite the lack of evidence that this omission has minimal impact on predicted bone, implant, and fixation screw stress distributions. This study investigated the influence of muscle forces on FE predictions of fixation screw pullout and fatigue failure in a custom pelvic implant. Specifically, FE analyses were conducted using a patient-specific FE model loaded with seven sets of personalized muscle and hip joint contact force loading conditions estimated using a personalized neuromusculoskeletal (NMS) model. Predictions of fixation screw pullout and fatigue failure—quantified by simulated screw axial forces and von Mises stresses, respectively—were compared between analyses with and without personalized muscle forces. The study found that muscle forces had a considerable influence on predicted screw pullout but not fatigue failure. However, it remains unclear whether including or excluding muscle forces would yield more conservative predictions of screw failures. Furthermore, while the effect of muscle forces on predicted screw failures was location-dependent for cortical screws, no clear location dependency was observed for cancellous screws. These findings support the combined use of patient-specific FE and NMS models, including loading from muscle forces, when predicting screw pullout but not fatigue failure in custom pelvic implants.

Percutaneous Screw Fixation for the Management of Delayed Unions in Pediatric Lateral Humeral Condylar Fractures.

The use of in situ screw fixation for the treatment of pediatric lateral humeral condyle (LCH) delayed unions has recently been reported. While attractive, the currently available literature consists of small retrospective studies with mixed results. As such, the present study aims to describe the outcome of a group of children with delayed unions of LCH fractures treated with in situ fixation using a single, percutaneously placed cannulated screw in compression. A retrospective review of all pediatric patients (below 18y) with lateral condyle fractures of the humerus treated surgically for delayed union between 2013 and 2023 at a single, tertiary referral center was completed. Clinical and radiologic variables related to the initial injury and delayed union were abstracted from the medical record, as were surgical variables. Radiographs were evaluated for union postoperatively; time to union was determined by the senior authors. Descriptive statistics were used to summarize demographic and outcome variables. A total of 12 consecutive patients met the inclusion criteria. The mean age at the time of initial injury was 5.6 years; subjects were followed for a mean of 3.0 years following initial presentation. All were treated with a single, percutaneously placed screw in compression at a mean of 10.5 months after the original injury. Radiographic union was achieved in 11 (91.7%) patients. At the latest follow-up, all patients were pain free and demonstrated a functional arc of motion without evidence of avascular necrosis. A total of 2 patients required revision for loss of fixation. In one patient, a persistent lucent line was observed, and 1 patient was found to have a cubitus valgus deformity, both of which were not clinically relevant. Our results suggest that with the use of proper technique (a 4.5 cannulated screw inserted through the metaphyseal portion of the lateral condyle fragment, engaging the most medial/distal aspect of the humeral shaft), radiographic union and clinical healing can be achieved in the majority of patients. Percutaneous screw fixation should be considered as an option for cases of noninfected pediatric lateral condyle delayed unions. Level IV-evidence therapeutic studies.

Mid-term efficacy of non-contact orthopedic robot navigation in the treatment of lumbar spondylolisthesis

ObjectiveThis study was aimed to explore the mid-term efficacy of non-contact orthopedic robot navigation in the treatment of lumbar spondylolisthesis.MethodsThe clinical data of young and middle-aged patients with lumbar spondylolisthesis were retrospectively analyzed and divided into an observation group and a control group according to surgical methods. The observation group was treated with minimally invasive transforaminal interbody fusion (MIS-TLIF) combined with orthopedic robot-navigated percutaneous pedicle screw fixation; while the control group underwent traditional posterior lumbar interbody fusion (PLIF). Perioperative indicators, waist and leg pain Visual Analog Scale (VAS) scores, Oswestry Disability Index (ODI), and complications were compared between groups.ResultsA total of 32 patients with lumbar spondylolisthesis were included in this study, with the average age of 50.3 ± 2.7 years old. There were 17 patients in the observation group and 15 patients in the control group. Although the new surgical technique for the observation group may require longer operative time, it showed significant advantages in reducing intraoperative bleeding, postoperative drainage, and shortening hospital stay. These benefits might result in faster recovery for patients, reduced risk of complications, and improved overall quality of life. The new technology was also significantly better compared to the traditional method in terms of VAS scores and ODI at 1 week, 1 month, 3 months, and 6 months post-surgery. These results provided patients with better treatment options and potentially a faster path to recovery. One case with infectious incision in the observation group and one case with intraspinal hematoma formation in the control group were observed. However, there was no statistical difference in the complication rates between the two groups (P > 0.05).ConclusionThe non-contact orthopedic robot navigation for the treatment of lumbar spondylolisthesis was demonstrated to be minimally invasive, precise, and stable surgical method. It is a treatment option worth considering for suitable patients.

Comparison of dynamic hip screw with anti-rotation screw and femoral neck system internal fixation for the treatment of garden II-IV type femoral neck fractures.

Femoral neck fractures, which are fractures occurring from the femoral head to the base of the femoral neck, are prevalent in the elderly population. With the progression of societal aging, the incidence of femoral neck fractures has been steadily increasing, making it a significant global issue that urgently needs to be addressed. To compare the efficacy and safety of dynamic hip screw (DHS) with anti-rotation screw and femoral neck system (FNS) internal fixation for the treatment of Garden II-IV type femoral neck fractures. A total of 90 patients with Garden II-IV type femoral neck fractures were randomly assigned to either the control group (n= 45) treated with DHS and anti-rotation screw or the experimental group (n= 45) treated with FNS. Surgical outcomes, including incision size, blood loss, operation time, fluoroscopy frequency, and fracture healing time, were compared. Postoperative complication rates, reoperation rates, Harris scores, and visual analogue scale (VAS) scores were also assessed. The experimental group demonstrated significantly reduced incision length, blood loss, operation time, and fluoroscopy frequency compared to the control group (P< 0.01). No significant differences were observed in fracture healing time, Garden classification, or fracture reduction outcomes between the two groups (P> 0.05). At 6 months post-treatment, both groups showed significant improvements in Harris scores and VAS scores compared to pre-treatment (P< 0.05), with no significant differences between the groups (P> 0.05). The rates of internal fixation failure, nonunion, and avascular necrosis of the femoral head, as well as overall incidence of postoperative complications and reoperation rates, showed no significant differences between the two groups (P> 0.05). Both DHS with anti-rotation screw and FNS internal fixation demonstrated comparable efficacy and safety profiles in the treatment of Garden II-IV type femoral neck fractures. The experimental group showed advantages in terms of reduced incision length, blood loss, operation time, and fluoroscopy frequency, while maintaining similar clinical outcomes and complication rates.