Stable Fixation Research Articles

Flicker adaptation improves acuity for briefly presented stimuli by reducing crowding.

Adaptation to flickering/dynamic noise improves visual acuity for briefly presented stimuli (Arnold et al., 2016). Here, we investigate whether such adaptation operates directly on our ability to see detail or by changing fixational eye movements and pupil size or by reducing visual crowding. Following earlier work, visual acuity was measured in observers who were either unadapted or who had adapted to a 60-Hz flickering noise pattern. Participants reported the orientation of a white tumbling-T target (four-alternative forced choice [4AFC], ⊤⊣⊥⊢). The target was presented for 110 ms either in isolation or flanked by randomly oriented T's (e.g., ⊣⊤⊢) followed by an isolated (+) or flanked (+++) mask, respectively. We measured fixation stability (using an infrared eye tracker) while observers performed the task (with and without adaptation). Visual acuity improved modestly (around 8.4%) for flanked optotypes following adaptation to flicker (mean, -0.038 ± 0.063 logMAR; p = 0.015; BF10 = 3.66) but did not when measured with isolated letters (mean, -0.008 ± 0.055 logMAR; p = 0.5; BF10 = 0.29). The magnitude of acuity improvement was associated with individuals' (unadapted) susceptibility to crowding (the ratio of crowded to uncrowded acuity; r = -0.58, p = 0.008, BF10 = 7.70) but to neither fixation stability nor pupil size. Confirming previous reports, flicker improved acuity for briefly presented stimuli, but we show that this was only the case for crowded letters. These improvements likely arise from attenuation of sensitivity to a transient low spatial frequency (SF) image structure (Arnold et al., 2016; Tagoh et al., 2022), which may, for example, reduce masking of high SFs by low SFs. We also suggest that this attenuation could reduce backward masking and so reduce foveal crowding.

Saccades and Microsaccades Coupling During Free-Throw Shots in Basketball Players.

We investigated the role of saccades and microsaccades when different levels of basketball players were engaged in an ecological free-throw condition. All participants made more correct than incorrect shoots, with a movement time initiation shorter in amateurs than in near-expert groups. Near-experts had more stable gaze fixation than amateurs, with higher microsaccade rate and duration and lower peak velocity. Amateurs showed higher saccade rate, peak velocity, and amplitude than near-experts. The temporal sequence of near-experts' microsaccade rate increased after the saccade peak; on the contrary, in amateurs, the saccade peak is shown after the decrement in microsaccade rates. The spatiotemporal characteristics of microsaccades and saccades may reflect an optimal sampling method by which the brain discretely acquires visual information and can differentiate between participants who use a fixation before the critical movement time and participants who move their eyes to catch more visual cues to make decisions.

Arthroscopic Autologous Iliac Crest Grafting with an Adjustable Loop Suspensory Device Yields Favorable Outcomes for Anterior Shoulder Instability with Glenoid Defects.

This study aims to evaluate the clinical and radiological outcomes of the arthroscopic autologous iliac crest grafting (AICG) procedure with an adjustable-loop suspensory fixation device in the treatment of anterior shoulder instability (ASI) with glenoid bone defects. A retrospective review was conducted on the patients who underwent arthroscopic AICG with an adjustable-loop suspensory fixation device from January 2017 to December 2020. Patients with traumatic ASI, significant glenoid bone defects, and a minimum follow-up of 24 months were included. Patient-reported outcomes (PROs), including the Oxford Shoulder Instability Score (OSIS), the Rowe score, the Walch-Duplay score, the Constant score, and the Visual Analogue Score (VAS), were compared preoperatively and postoperatively. Radiological assessments using computed tomography (CT) were performed before and after the procedure. Additional data on active range of motion, recurrence events, and complications were recorded. A total of 42 patients were included in the study, with a mean follow-up time of 35.2 months ranging from 25.1 to 55.9 months. Mean preoperative OSIS, Rowe score, Walch-Duplay score, and Constant score significantly improved from 24.4±7.2, 25.0±9.0, 25.2±9.8, 87.5±7.1 to 42.4±4.9, 92.4±8.1, 87.9±8.3, 93.6±4.5 at the last follow-up, respectively. All patients exceeded the minimal clinically important difference (MCID) for OSIS, Rowe, and Walch-Duplay scores. The graft union rate was 100%, and the glenoid area increased significantly from 82.5% preoperatively to 100.1% at the final follow-up. No patient experienced a recurrence of instability. Two recorded complications included one case of dysesthesia around the donor site and one case of postoperative shoulder stiffness. The outcomes of the arthroscopic AICG procedure, which utilizes an adjustable-loop suspensory fixation device, demonstrated stable bone graft fixation, high rates of graft integration, favorable clinical results, and a low incidence of complications. Moreover, the remodeling of the graft during the follow-up period significantly restored the width and concavity of the inferior glenoid, contributing to the overall recovery. Level IV, retrospective case series.

Extra Medullary Fixation in Unstable Proximal Femoral Fractures by PF-LCP.

Perception that extra-medullary fixation of these fractures are fraught with difficulties and deficiencies is becoming inappropriate. This device provides angular stable fixation retaining fracture biology with minimum interference to osseous and soft-tissue vascularity and it does not require reaming which destroys 80% of endosteal vasculature for 6-12weeks. PFLCP averts iatrogenic fracture in lateral trochanteric wall (LTW) which is frequent with DHS, protects LTW from secondary fracture in post-operative period. Aim is to assess outcome of unstable proximal femur fracture fixation by PFLCP. Study included 64 from 2016 to 2020, divided in two groups. (A) Unstable intertrochanteric fracture and (B) subtrochanteric fracture (Seinsheimer types II-V). All fractures fixed by MIPO with PFLCP. Loss of reduction, infection, cut-out, cut-through, backing of screws, bending or breaking of plate and screw, malunion, non-union and revision were evaluated. Fracture healing and functional recovery assessed by Reborne Score and Parker Mobility Score (PMS) respectively. Out of 64, 24 achieved pre-injury PMS, 32 declined by 1 point, 6 declined by 2 points and 1 by 3 points, one required revision. Using various parameters 37.5% patients had excellent results and 50% had good results, 9.38% had average and 3.12% had poor result. None reported non-union or breakage of plate. PFLCP provides angular stable fixation, torsional stability with high biomechanical strength to resist deforming stresses. MIPO avoids soft-tissue stripping reducing blood-loss, retains periosteal blood supply to inter-fragmentary bone fragments, enhancing fracture healing, reducing complications, such as delayed healing, nonunion, infection and implant failure.

Implantation of S1AIS has priority as a sacroiliac joint fixation technique.

The sacral alar-iliac screw (SAIS) fixation technique has evolved from spinopelvic fixation which originated from S2AIS to sacroiliac joint fixation, with more reports regarding its application of S2AIS than S1AIS. However, there is a lack of comparative evidence to determine which technique is superior for sacroiliac joint fixation. This study aimed to determine which of the screws was superior in terms of implantation safety and biomechanical stability for sacroiliac joint fixation. CT data of 80 normal pelvises were analyzed to measure the insertable range, trajectory lengths and widths of both S1AIS and S2AIS on 3D reconstruction models. Φ 6.5mm and 8.0mm screws were implanted on the left and right sides of fifty 3D printed pelvic models respectively to observe for breach of screw implantation. Ten synthetic pelvis models were used to simulate type C Tile injuries, and divided into 2 groups with an anterior plate and posterior fixation using one S1AIS or S2AIS on each side. The stiffness and maximum load of the plated and fixated models were measured under vertical loading. The trajectory lengths and widths of the S1AIS and S2AIS were similar (p > 0.05) and there was no breach for Φ 6.5mm SAIS. However, both the insertable range and trajectory length on the sacral side of S2AIS (234.56 ± 10.06mm2, 40.97 ± 2.81mm) were significantly less, and the breach rate of the posterior lateral cortex of the Φ 8.0mm S2AIS (46%) was significantly higher than the S1AIS (307.55 ± 10.42 mm2, 42.16 ± 3.06mm, and 2%, p < 0.05). The stiffness and maximum load of S2AIS were less than S1AIS but the difference was not statistically significant (p > 0.05). S1AIS and S2AIS have similar screw trajectories and stability. However, S1AIS has a larger insertable range, less breach of the posterior lateral sacral cortex and longer trajectory length on the sacral side than S2AIS, which indicates S1AIS has higher implantation safety and a trend of better mechanical performance over S2AIS for sacroiliac joint fixation. Furthermore, S2AIS with an excessively large diameter should be used with caution for sacroiliac joint fixation.

Full weight bearing after internal fixation of isolated distal fibular fractures with anatomically contoured locking plates: Our institutional experience

Isolated fractures of the distal fibula mainly affect young, active people. In most cases, fixation is by open reduction with or without casting for six weeks without weight bearing. The current trend is to reduce this period of non-weight-bearing in order to promote earlier functional rehabilitation. The improved mechanical stability resulting from the use of plates with locking screws has changed the postoperative management of many fractures, but there is little evidence for the ankle.Between October 2013 and August 2015, 36 patients were enrolled in a prospective study to evaluate the performance of internal fixation of isolated distal fibular fractures using a lateral anatomically contoured titanium locking plate (InitialA® plate from Newclip Technics, Haute Goulaine, France) with immediate mobilisation and full weight bearing.No patient required further surgery due to mechanical failure or non-union. The bone healing rate was 100 % at 3 months. Two patients had septic complications requiring plate removal and antibiotic treatment and were eventually cured.The use of anatomically contoured locking plates provides strong and stable fixation, allowing immediate full weight-bearing. Such a technique has the advantage of a short recovery time and an early return to work without additional complications.

Oculomotor differences in adults with and without probable developmental coordination disorder.

Adults with Developmental Coordination Disorder (DCD), sometimes referred to as dyspraxia, experience difficulties in motor development and coordination, which impacts on all aspects of their daily lives. Surprisingly little is known about the mechanisms underlying the difficulties they experience in the motor domain. In childhood DCD, aspects of oculomotor control have been shown to be altered. The purpose of this study was to determine whether oculomotor differences are present in adults with and without probable DCD. Visual fixation stability, smooth pursuit, and pro-and anti-saccade performance were assessed in 21 adults (mean age 29 years) with probable DCD/dyspraxia (pDCD) and 21 typically-developing (TD) adults (mean age 21 years). Eye tracking technology revealed that oculomotor response preparation in the pro- and anti-saccade tasks was comparable across groups, as was pursuit gain in the slower of the two smooth pursuit tasks. However, adults with pDCD made significantly more saccades away from the fixation target than those without DCD and significantly more anti-saccade errors. Further, compared to TD adults, adults with pDCD demonstrated difficulties in maintaining engagement and had lower pursuit gain in the faster pursuit task. This suggests that adults with pDCD have problems with saccadic inhibition and maintaining attention on a visual target. Since this pattern of results has also been reported in children with DCD, oculomotor difficulties may be persistent for those with DCD across the lifespan. An awareness of the impact of atypical oculomotor control in activities of daily living across the lifespan would support clearer understanding of the causes and impacts of these difficulties for those with DCD.

Effect of nystagmus on VEP-based objective visual acuity estimates

In order to determine the effect of nystagmus on objective visual acuity (VA) estimates, we compared subjective (VApsych) and objective (VEP, VAVEP) VA estimates in participants with nystagmus. For this purpose, 20 participants with nystagmus (NY) caused by idiopathic infantile nystagmus, albinism, achiasma or acquired nystagmus were recruited in this study. Estimates of BCVA (best corrected visual acuity) were determined psychophysically (VApsych; FrACT, Freiburg visual acuity test) and electrophysiologically (VAVEP; EP2000) according to ISCEV (International Society of Clinical Electrophysiology of Vision) guidelines. For each participant the eye with the stronger fixation instability [Nidek microperimeter (MP-1), Nidek Instruments] was included for further analysis. VApsych vs VAVEP were compared via paired t-tests and the correlation of the difference between VApsych and VAVEP (∆VA) vs the degree of fixation instability was tested with Pearson correlation (r). We found VAVEP to be better than VApsych [by 0.12 Logarithm of the Minimum Angle of Resolution (logMAR); mean ± standard error (SE) of VAVEP vs VApsych: 0.176 ± 0.06 vs. 0.299 ± 0.06, P = 0.017] and ∆VA to be correlated linearly with the degree of fixation instability (r2 = 0.21,p = 0.048). In conclusion, on average we report a small VA overestimation, around 1 line, for VAVEP compared to VApsych in NY. This overestimation depended on the magnitude of the fixation instability. As a rule of thumb, a reduction of the fixation probability in the central 4° from 100 to 50% leads on average to a VAVEP overestimation of around 0.25 logMAR, i.e. 2.5 lines.

The ballistic articular structure injury classification (BASIC) system: clarifying ballistic articular injuries.

This study aims to (1) devise a classification system to categorize and manage ballistic fractures of the knee, hip, and shoulder; (2) assess the reliability of this classification compared to current classification schemas; and (3) determine the association of this classification with surgical management. We performed a retrospective review of a prospectively collected trauma database at an urban level 1 trauma centre. The study included 147 patients with 169 articular fractures caused by ballistic trauma to the knee, hip, and shoulder. Injuries were selected based on radiographic criteria from plain radiographs and CT scans. The AO/OTA classification system's reliability was compared to that of the novel ballistic articular injury classification system (BASIC), developed using a nominal group approach. The BASIC system's ability to guide surgical decision-making, aiming to achieve stable fixation and minimize post-traumatic arthritis, was also evaluated. The BASIC system was created after analysing 73 knee, 62 hip, and 34 shoulder fractures. CT scans were used in 88% of cases, with 44% of patients receiving surgery. The BASIC classification comprises five subgroups, with a plus sign indicating the need for soft tissue intervention. Interrater reliability showed fair agreement for AO/OTA (k = 0.373) and moderate agreement for BASIC (k = 0.444). The BASIC system correlated strongly with surgical decisions, with an 83% concurrence in treatment choices based on chart reviews. Conventional classification systems provide limited guidance for ballistic articular injuries. The BASIC system offers a pragmatic and reproducible alternative, with potential to inform treatment decisions for knee, hip, and shoulder ballistic injuries. Further research is needed to validate this system and its correlation with patient outcomes. Level III, Diagnostic Study.

Screw placement through a higher medial portal provides better initial stability in arthroscopic ACL tibial avulsion fracture fixation: a finite element analysis

ObjectiveThe objective of this study was to investigate the initial stability of different screw placements in arthroscopic anterior cruciate ligament (ACL) tibial avulsion fracture fixation.MethodsA three-dimensional knee model at 90° flexion was utilized to simulate type III ACL tibial avulsion fracture and arthroscopic screw fixation through different portals, namely the central transpatellar tendon portal (CTP), anterolateral portal (ALP), anteromedial portal (AMP), lateral parapatellar portal (LPP), medial parapatellar portal (MPP), lateral suprapatellar portal (LSP), medial suprapatellar portal (MSP). A shear force of 450 N was applied to the finite element models at 30° flexion to simulate the failure condition. The displacement of the bony fragment and the volume of the bone above 25,000 µ-strain (damaged bone volume) were calculated around the screw path.ResultsWhen the screw was implanted through CTP, the displacement of the bony fragment reached the maximum displacement which was 1.10 mm and the maximum damaged bone volume around the screw path was 148.70 mm3. On the other hand, the minimum displacement of the bony fragment was 0.45 mm when the screw was implanted through LSP and MSP. The minimum damaged bone volume was 14.54 mm3 around the screw path when the screw was implanted through MSP.ConclusionScrews implanted through a higher medial portal generated less displacement of the bony fragment and a minimum detrimental strain around the screw path. The findings are clinically relevant as they provide biomechanical evidence on optimizing screw placement in arthroscopic ACL tibial avulsion fracture fixation.

Structural, blood flow and functional changes in the macular area and the expression of aqueous humor factors in myopia.

To compare the macular area parameters and aqueous humor factors between myopia and emmetropia. Convenience sampling was used to select patients who visited the Changzhi Aier Eye Hospital's department of ophthalmology from December 2018 to December 2022 as the study participants. They were divided into three groups according to whether they were diagnosed as mild myopia myopic, highly myopic or not as follows: the mild myopia group (60 cases, 108 eyes), the high myopia group (46 cases, 78 eyes) and the healthy emmetropia group (40 cases, 65 eyes). The differences in the macular integrity (MI) assessment, optical coherence tomography and optical coherence tomography angiography parameters and aqueous humor factors were compared between the three groups. AL in high myopia group was the highest, and that in emmetropia group was the lowest. The BCVA of mild myopia group was the highest. The RS in the high myopia group were significantly lowest in the three groups (26.42 ± 1.04 vs. 28.34 ± 0.76 vs. 31.92 ± 0.77) (F = 5.374, p = 0.013). The 63% BCEA, 95% BCEA and MI in the high myopia group were significantly highest (p < 0.05). The mean RPE thickness, mean CT and mean RT in the high myopia group were lowest (p < 0.05). The blood flow density were lowest in the superficial fovea, paracentral fovea and different subdivisions of the paracentral fovea in the high myopia group (p < 0.05). The VEGF concentration in the aqueous humor of the high myopia group was lowest (25.62 ± 17.43 vs. 32.45 ± 24.67 vs. 64.37 ± 21.14) (F = 9.237, p < 0.001). The MMP-2 concentration was highest (483 ± 201.48 vs. 410 ± 142.37 vs. 386 ± 154.34) (F = 5.542, p = 0.018). The VEGF concentration in the aqueous humor factor was negatively correlated with the AL in the myopia group (r = -0.438, p = 0.002), the MMP-2 concentration was positively correlated with the AL (r = 0.484, p = 0.010). Patients with high myopia showed decreased retinal light sensitivity, fixation stability, superficial blood flow density and retinal thickness compared with people with emmetropia. A decreased VEGF concentration and increased MMP-2 concentration in the aqueous humor factor have potential associations with the development of high myopia.

Biomechanical Comparison of Corticopedicular Spine Fixation versus Pedicle Screw Fixation in a Lumbar Degenerative Spondylolisthesis Finite Element Analysis Model

To compare the stability of a corticopedicular posterior fixation (CPPF) device with traditional pedicle screws for decompression and fusion in adult degenerative lumbar spondylolisthesis. Finite element analysis (FEA) was used in a validated model of grade 1 L4-L5 spondylolisthesis to compare segmental stability after laminectomy alone, laminectomy with pedicle screw fixation, or laminectomy with CPPF device fixation. A 500-N follower load was applied to the model and different functional movements were simulated by applying a 7.5-Nm force in different directions. Outcomes included degrees of motion, tensile forces experienced in the CPPF device, and stresses in surrounding cortical bone. At maximum loading, laminectomy alone demonstrated a 1° increase in flexion range of motion, from 6.35° to 7.39°. Laminectomy with pedicle screw fixation and CPPF device fixation both reduced spinal segmental motion to ≤1° at maximum loading in all ranges of motion, including flexion (0.94° and 1.09°), extension (-0.85° and -1.08°), lateral bending (-0.56° and -0.96°), and torsion (0.63° and 0.91°), respectively. There was no significant difference in segmental stability between pedicle screw fixation and CPPF device fixation during maximum loading, with a difference of ≤0.4° in any range of motion. Tensile forces in the CPPF device remained ≤51% the ultimate load to failure (487 N) and stress in surrounding cortical bone remained ≤84% the ultimate stress of cortical bone (125.4 MPa) during maximum loading. CPFF fixation demonstrated similar segmental stability to traditional pedicle screw fixation whereas tensile forces and stress in surrounding cortical bone remained below the load to failure.

Determining the Optimal Intramedullary Screw Canal Fill Ratio in Length Unstable Metacarpal Fractures: A Biomechanical Investigation

Intramedullary (IM) screw fixation is gaining popularity in the treatment of metacarpal fractures. Despite its rapid adoption, there is a paucity of evidence regarding parameters to optimize effectiveness. This study aimed to quantify the relationship between stability, IM screw size, and canal fill using a cadaveric model. Thirty cadaveric metacarpals (14 index, 13 middle, and three ring fingers; mean age: 58.3 years, range: 48-70) were selected to allow for canal fill ratios of 0.7-1.1 for screws sized 3.0, 3.5, and 4.5 mm. Metacarpals underwent a 45° volar-dorsal osteotomy at the midpoint before fixation with an IM screw. Specimens were subjected to 100 cycles of loading at 10 N, 20 N, and 30 N before load-to-failure testing. Correlation coefficients for angular displacement on the final cycle at each load, peak load to failure, and average stiffness were assessed. Correlation coefficients for the angular displacement on the 100th cycle were as follows: 10 N, R= 0.62, 20 N, R= 0.57, and 30N, R= 0.58. Correlation values for peak load to failure as a function of canal fit were as follows: 3.0 mm, R= 0.5, 3.5 mm, R= 0.17, and 4.5 mm, R= 0.44. The canal fill ratio that intersected the line-of-best fit at an angular deformity of 10° was 0.74. Average peak forces for 3.0-, 3.5-, and 4.5-mm screws were 79.5, 136.5, and 179.6 N, respectively. Average stiffness for each caliber was 14.8, 33.4, and 52.3 N/mm. Increasing screw diameter and IM fill resulted in more stable fixation, but marginal gains were seen in ratios >0.9. A minimum fill ratio of 0.74 was sufficient to withstand forces of early active motion with angular deformity <10°. An understanding of the relationship of IM fill ratio of metacarpal screws to fracture stability may provide a framework for clinicians to optimally size these implants.

Biomechanical evaluation of different medial column fixation patterns for valgus pilon fractures

BackgroundThe purpose of this study was to perform a biomechanical analysis to compare different medial column fixation patterns for valgus pilon fractures in a case-based model.MethodsBased on the fracture mapping, 48 valgus pilon fracture models were produced and assigned into four groups with different medial column fixation patterns: no fixation (NF), K-wires (KW), intramedullary screws (IS), and locking compression plate (LCP). Each group contained wedge-in and wedge-out subgroups. After fixing each specimen on the machine, gradually increased axial compressive loads were applied with a load speed of one millimeter per minute. The maximum peak force was set at 1500 N. Load-displacement curves were generated and the axial stiffness was calculated. Five different loads of 200 N, 400 N, 600 N, 800 N, 1000 N were selected for analysis. The specimen failure was defined as resultant loading displacement over 3 mm.ResultsFor the wedge-out models, Group-IS showed less displacement (p < 0.001), higher axial stiffness (p < 0.01), and higher load to failure (p < 0.001) than Group-NF. Group-KW showed comparable displacement under loads of 200 N, 400 N and 600 N with both Group-IS and Group-LCP. For the wedge-in models, no statistical differences in displacement, axial stiffness, or load to failure were observed among the four groups. Overall, wedge-out models exhibited less axial stiffness than wedge-in models (all p < 0.01).ConclusionsFunctional reduction with stable fixation of the medial column is essential for the biomechanical stability of valgus pilon fractures and medial column fixation provides the enough biomechanical stability for this kind of fracture in the combination of anterolateral fixation. In detail, the K-wires can provide a provisional stability at an early stage. Intramedullary screws are strong enough to provide the medial column stability as a definitive fixation. In future, this technique can be recommended for medial column fixation as a complement for holistic stability in high-energy valgus pilon fractures.

Age-Based Developmental Biomarkers in Eye Movements: A Retrospective Analysis Using Machine Learning.

This study aimed to identify when and how eye movements change across the human lifespan to benchmark developmental biomarkers. The sample size comprised 45,696 participants, ranging in age from 6 to 80 years old (M = 30.39; SD = 17.46). Participants completed six eye movement tests: Circular Smooth Pursuit, Horizontal Smooth Pursuit, Vertical Smooth Pursuit, Horizontal Saccades, Vertical Saccades, and Fixation Stability. These tests examined all four major eye movements (fixations, saccades, pursuits, and vergence) using 89 eye-tracking algorithms. A semi-supervised, self-training, machine learning classifier was used to group the data into age ranges. This classifier resulted in 12 age groups: 6-7, 8-11, 12-14, 15-25, 26-31, 32-38, 39-45, 46-53, 54-60, 61-68, 69-76, and 77-80 years. To provide a descriptive indication of the strength of the self-training classifier, a series of multiple analyses of variance (MANOVA) were conducted on the multivariate effect of the age groups by test set. Each MANOVA revealed a significant multivariate effect on age groups (p < 0.001). Developmental changes in eye movements across age categories were identified. Specifically, similarities were observed between very young and elderly individuals. Middle-aged individuals (30s) generally showed the best eye movement metrics. Clinicians and researchers may use the findings from this study to inform decision-making on patients' health and wellness and guide effective research methodologies.

Application of Multi-Rod Constructs for the Revision of Thoracolumbar Fractures.

The revision procedure for failure of internal fixation after thoracolumbar fracture is controversial. Combined anterior and posterior surgery is associated with higher risk more intraoperative bleeding and tissue damage. The success rate of simple anterior surgery needs further confirmation, and posterior surgery lacks stability of internal fixation. This study evaluates the feasibility and surgical effect of multi-rod constructs in the revision of thoracolumbar fractures. Eleven patients with thoracolumbar fractures who underwent previous construct failure and were treated with revision and internal fixation with the multi-rod technique from March 2017 to September 2018 were analyzed. The original internal fixation was removed and replaced in the medial insertion of satellite rods and bone graft. The average follow-up time was 15.97 months. The intraoperation blood loss, the time of the operation, activation and discharge and the rate of rod fracture were calculated. The sagittal Cobb angle before revision, after revision and at the last follow-up were compared. The clinical effect was evaluated by visual analogue scale (VAS) and Oswestry Disability Index questionnaire (ODI). The average operation time was 107 min, the intraoperative blood loss was 131.81 mL, the active time was 1.59 days, and the discharge time was 10.89 days. No rod fractured again during the follow-up period. The paired t-test was used to compare the Cobb angle, VAS score, and ODI before and after surgery. There was significant difference in the sagittal Cobb angle between the pre-revision and the posterior sagittal position (p = 0.000), and no significant difference was found between post-revision and last follow-up (p = 0.551). VAS and ODI were greatly improved at the last follow-up. The literature on revision of thoracolumbar fractures is insufficient and comprises varying opinions. This paper proposes a new treatment option. The application of the multi-rod constructs in the revision of thoracolumbar fractures is safe, simple, and effective and might provide guidance for future clinical work.

Research Progress on the Treatment of Geriatric Intertrochanteric Femur Fractures with Proximal Femur Bionic Nails (PFBNs).

Intertrochanteric femur fracture is the most common hip fracture in elderly people, and the academic community has reached a consensus that early surgery is imperative. Proximal femoral nail anti-rotation (PFNA) and InterTan are the preferred internal fixation devices for intertrochanteric femur fractures in elderly individuals due to their advantages, such as a short lever arm, minimal stress shielding, and resistance to rotation. However, PFNA is associated with complications such as nail back-out and helical blade cut-out due to stress concentration. As a new internal fixation device for intertrochanteric femur fractures, the proximal femoral biodegradable nail (PFBN) addresses the issue of nail back-out and offers more stable fracture fixation, a shorter lever arm, and stress distribution compared to PFNA and InterTan. Clinical studies have shown that compared to PFNA, PFBNs lead to faster recovery of hip joint function, shorter non-weight-bearing time, and faster fracture healing. This article provides a literature review of the structural characteristics, biomechanical analysis, and clinical studies of PFBNs, aiming to provide a theoretical basis for the selection of internal fixation devices for the treatment of intertrochanteric femur fractures in elderly patients and to improve the quality of life of patients during the postoperative period.

Foveolar Drusen Decrease Fixation Stability in Pre-Symptomatic AMD.

This study aims at linking subtle changes of fixational eye movements (FEM) in controls and in patients with foveal drusen using adaptive optics retinal imaging in order to find anatomo-functional markers for pre-symptomatic age-related macular degeneration (AMD). We recruited 7 young controls, 4 older controls, and 16 patients with presymptomatic AMD with foveal drusen from the Silversight Cohort. A high-speed research-grade adaptive optics flood illumination ophthalmoscope (AO-FIO) was used for monocular retinal tracking of fixational eye movements. The system allows for sub-arcminute resolution, and high-speed and distortion-free imaging of the foveal area. Foveal drusen position and size were documented using gaze-dependent imaging on a clinical-grade AO-FIO. FEM were measured with high precision (RMS-S2S = 0.0015degrees on human eyes) and small foveal drusen (median diameter = 60 µm) were detected with high contrast imaging. Microsaccade amplitude, drift diffusion coefficient, and ISOline area (ISOA) were significantly larger for patients with foveal drusen compared with controls. Among the drusen participants, microsaccade amplitude was correlated to drusen eccentricity from the center of the fovea. A novel high-speed high-precision retinal tracking technique allowed for the characterization of FEM at the microscopic level. Foveal drusen altered fixation stability, resulting in compensatory FEM changes. Particularly, drusen at the foveolar level seemed to have a stronger impact on microsaccade amplitudes and ISOA. The unexpected anatomo-functional link between small foveal drusen and fixation stability opens up a new perspective of detecting oculomotor signatures of eye diseases at the presymptomatic stage.

Highly extensile approach for comminuted ulna coronoid process fractures with mini-plate fixation: a case series of 31 patients

BackgroundFor the treatment of coronoid process fractures, medial, lateral, anterior, anteromedial, and posterior approaches have been increasingly reported; however, there is no general consensus on the method of fixation of coronal fractures. Here, we present a highly-extensile minimally invasive approach to treat coronoid process fractures using a mini-plate that can achieve anatomic reduction, stable fixation, and anterior capsular repair. Further, the study aimed to determine the complication rate of the anterior minimally invasive approach and to evaluate functional and clinical patient-reported outcomes during follow-up.MethodsThirty-one patients diagnosed with coronoid fractures accompanied with a “terrible triad” or posteromedial rotational instability between April 2012 and October 2018 were included in the analysis. Anatomical reduction and mini-plate fixation of coronoid fractures were performed using an anterior minimally invasive approach. Patient-reported outcomes were evaluated using the Mayo Elbow Performance Index (MEPI) score, range of motion (ROM), and the visual analog score (VAS). The time of fracture healing and complications were recorded.ResultsThe mean follow-up time was 26.7 months (range, 14–60 months). The average time to radiological union was 3.6 ± 1.3 months. During the follow-up period, the average elbow extension was 6.8 ± 2.9° while the average flexion was 129.6 ± 4.6°. According to Morrey’s criteria, 26 (81%) elbows achieved a normal desired ROM. At the last follow-up, the mean MEPI score was 98 ± 3.3 points. There were no instances of elbow instability, elbow joint stiffness, subluxation or dislocation, infection, blood vessel complications, or nerve palsy. Overall, 10 elbows (31%) experienced heterotopic ossification.ConclusionAn anterior minimally invasive approach allows satisfactory fixation of coronoid fractures while reducing incision complications due to over-dissection of soft tissue injuries. In addition, this incision does not compromise the soft tissue stability of the elbow joint and allows the patient a more rapid return to rehabilitation exercises.

Multimodal phenotyping of foveal hypoplasia in albinism and albino-like conditions: a pediatric case series with adaptive optics insights

Aim of the present study is to evaluate the relationship between genetic and phenotypic data in a series of patients affected by grade I and II of foveal hypoplasia with stable fixation and good visual acuity using multimodal imaging techniques. All patients underwent complete clinical and instrumental assessment including structural Optical Coherence Tomography (OCT), OCT Angiography and Adaptive Optics (AO) imaging. Central macular thickness (CMT), inner nuclear layer (INL), vessel density in superficial capillary plexus were the main variables evaluated with OCT technology. Cone density, cone spacing, cone regularity, cone dispersion and angular density were the parameters evaluated with AO. Genetic evaluation and trio exome sequencing were performed in all affected individuals. Eight patients (3 males and 5 females) with a mean age of 12.62 years (range 8–18) were enrolled. The mean best corrected visual acuity (BCVA) was 0.18 ± 0.13 logMAR, mean CMT was 291.9 ± 16.6 µm and INL was 26.2 ± 4.6 µm. The absence of a foveal avascular zone (FAZ) was documented by examination of OCT-A in seven patients in the superficial capillary plexus. However, there was a partial FAZ in the deep plexus in patients P5 and P8. Of note, all the patients presented with major retinal vessels clearly crossing the foveal center. All individuals exhibited a grade I or II of foveal hypoplasia. In 5 patients molecular analyses showed an extremely mild form of albinism caused by compound heterozygosity of a TYR pathogenic variant and the hypomorphic p.[Ser192Tyr;Arg402Gln] haplotype. One patient had Waardenburg syndrome type 2A caused by a de novo variant in MITF. Two patients had inconclusive molecular analyses. All the patients displayed abnormalities on OCT-A. Photoreceptor count did not differ from normal subjects according to the current literature, but qualitative analysis of AO imaging showed distinctive features likely related to an abnormal pigment distribution in this subset of individuals. In patients with foveal hypoplasia, genetic and multimodal imaging data, including AO findings, can help understand the physiopathology of the foveal hypoplasia phenotype. This study confirms that cone density and visual function can both be preserved despite the absence of a pit.