Acute Bending Research Articles

Robotic-assisted anatomic anterior cruciate ligament reconstruction: a comparative analysis of modified transtibial and anteromedial portal techniques in cadaveric knees.

Introduction: This study employed surgical robot to perform anatomic single-bundle reconstruction using the modified transtibial (TT) technique and anteromedial (AM) portal technique. The purpose was to directly compare tunnel and graft characteristics of the two techniques. Methods: Eight cadaveric knees without ligament injury were used in the study. The modified TT and AM portal technique were both conducted under surgical robotic system. Postoperative data acquisition of the tunnel and graft characteristics included tibial tunnel position, tunnel angle, tunnel length and femoral tunnel-graft angle. Results: The mean tibial tunnel length of the modified TT technique was significantly shorter than in the AM portal technique (p < 0.001). The mean length of the femoral tunnel was significantly longer for the modified TT technique than for the AM portal technique (p < 0.001). The mean coronal angle of the tibial tunnel was significantly lower for the modified TT technique than for the AM portal technique (p < 0.001). The mean coronal angle of the femoral tunnel was significantly lower for the AM portal technique than for the modified TT technique (p < 0.001). The AM portal technique resulted in a graft bending angle that was significantly more angulated in the coronal (p < 0.001) and the sagittal planes (p < 0.001) compared with the modified TT technique. Discussion: Comparison of the preoperative planning and postoperative femoral tunnel positions showed that the mean difference of the tunnel position was 1.8 ± 0.4mm. It suggested that the surgical navigation robot could make predictable tunnel position with high accuracy. The findings may support that the modified TT technique has benefits on femoral tunnel length and obliquity compared with AM portal technique. The modified TT technique showed a larger femoral tunnel angle in the coronal plane than the AM portal technique. Compared with the modified TT technique, the more horizontal trajectory of the femoral tunnel in the AM portal technique creates a shorter femoral tunnel length and a more acute graft bending angle.

Usefulness of 3-Dimensional Computed Tomography Assessment of Femoral Tunnel after Anterior Cruciate Ligament Reconstruction.

Positioning of the femoral tunnel during anterior cruciate ligament (ACL) reconstruction is the most crucial factor for successful procedure. Owing to the inter-individual variability in the intra-articular anatomy, it can be challenging to obtain precise tunnel placement and ensure consistent results. Currently, the three-dimensional (3D) reconstruction of computed tomography (CT) scans is considered the best method for determining whether femoral tunnels are positioned correctly. Postoperative 3D-CT feedback can improve the accuracy of femoral tunnel placement. Precise tunnel formation obtained through feedback has a positive effect on graft maturation, graft failure, and clinical outcomes after surgery. However, even if femoral tunnel placement on 3D CT is appropriate, we should recognize that acute graft bending negatively affects surgical results. This review aimed to discuss the implementation of 3D-CT evaluation for predicting postoperative outcomes following ACL re-construction. Reviewing research that has performed 3D CT evaluations after ACL reconstruction can provide clinically significant evidence of the formation of ideal tunnels following anatomic ACL reconstruction.

Investigating the Tectonic and Structural Controls on the Geomorphic Evolution of Shiriya River Basin, Southern India

Abstract Morphotectonic analysis of a river basin using geomorphic indices helps to identify tectonic deformation. The aim of the present work is to determine geomorphic indices from the digital elevation model and to examine the extent to which structural characteristics of the Shiriya River Basin (SRB) have influenced its drainage morphology. GIS techniques are used to calculate geomorphic indices of the SRB. Morphotectonic and geomorphic analyses were carried out, which included evaluating various geomorphic indices. Hypsometric curve and hypsometric integral (0.46) indicate youth stage of the basin, asymmetry factor (43.23) and transverse topographic symmetry factor (0.37) indicate asymmetry of the basin, basin shape index (2.05) depicts the basin as elongated, sinuosity index (1.47) indicate the sinuous nature of the basin, valley floor width to height ratio is 10.21 and stream length gradient index is 113.75. The entire basin is divided into 18 fourth-order sub-basins for detailed analysis of morphotectonics. Relative active tectonic indices are calculated to identify the subbasin that had undergone pronounced structural disturbance. Out of 18 subbasins 13 subbasin belongs to moderate tectonic active category (class-2) and 5 subbasin belongs to active category (class 2). From the morpho structural analysis following results were arrived, all of which point towards significant structural control: Lower-order streams have an orientation in accordance with significant structural elements of the basin, such as foliations and lineations (E-W). Similarly, the alignment of higher-order streams follows the direction of the major lineaments of the basin (NW-SE). Eight waterfalls/cascades are positioned within the basin, all directed in accordance with the lineament (NW-SE), earthquake recorded near the basin, asymmetry of the basin, acute bending of streams, entrenched meanders, changes in the sinuous river path in several locations where lineament intersect the stream and shrinkage of estuary area indicate neotectonics and structural control over the development of drainage system in the SRB. These findings are essential for understanding the development of river drainage and landform evolution.

Graft impingement increases anterior cruciate ligament graft signal more than acute graft bending angle: magnetic resonance imaging-based study in outside-in anterior cruciate ligament reconstruction.

In this study, the relationship between patient-specific geometric factors and tunnel placement in graft impingement was identified by using magnetic resonance imaging (MRI) signal intensity of anterior cruciate ligament (ACL) grafts. Ninety-two patients, who were treated between 2014 and 2020, were included retrospectively. These patients underwent primary remnant-preserving outside-in ACL reconstruction (ACLR) and were followed up with postoperative MRI at least one year after surgery. Plain radiographs and computed tomography (CT) were used to analyze tibial and femoral tunnel positions. Postoperative MRI was performed, at 32.8 ± 17.5months after surgery, to evaluate the graft signal intensity, the ACL/posterior cruciate ligament (PCL) ratio (APR), ACL/muscle ratio (AMR), tunnel positions, and graft impingement. Clinical and stability outcomes were analyzed using the International Knee Documentation Committee (IKDC) subjective and objective scores, Lysholm scores, and side-to-side differences (SS-D). The mean APR and AMR of the proximal third of the grafts were significantly lower than those of the middle third of the grafts (p = 0.017 and p = 0.045, respectively). Multivariate regression analysis showed that there was a negative association between the mean APR and AMR of entire intra-articular ACL graft and the distance from the anterior end of the intercondylar roof to the center of the tibial tunnel in the sagittal plane (p < 0.001 and p < 0.001, respectively) and the notch width index (p < 0.001 and p = 0.002, respectively). No significant correlations were found between tunneling and geometric factors, and clinical scores or SS-D. Graft impingement on the anterior tibial tunnel relative to the end of the intercondylar roof and narrow notch was a more significant contributing factor on increased signal intensities of the ACL graft, compared with the acute femoral bending angle in remnant-preserving outside-in ACLR. Therefore, surgeons should focus on intercondylar notch anatomy during tibial tunnel placement to avoid roof impingement. Level III.

A Novel Dual-Element Catheter for Improving Non-Uniform Rotational Distortion in Intravascular Ultrasound.

For the early diagnosis of atherosclerosis and interventions, intravascular ultrasound (IVUS) is a valuable tool for intravascular luminal imaging. Compared with the array-based method, mechanically rotating IVUS catheters dominate the clinical applications because of their less complexity and better suitability for high-frequency ultrasound imaging. However, mechanically rotating catheters are suffering from non-uniform rotational distortion (NURD) which hinders accurate image acquisition. In this study, a dual-element imaging catheter is proposed, in which two elements with the same frequency and similar performance are assembled in a back-to-back arrangement. When the catheter encounters a NURD due to acute bending, the abnormal image of one element can be replaced by the normal image of the opposite element, thus eliminating the NURD in the reconstructed image. Moreover, two images can be obtained in one rotation and the imaging frame rate is doubled in the absence of NURD. The performance of the two elements was quantitatively assessed by a wire phantom. And the complementary imaging protocols were evaluated by a tissue phantom and ex vivo porcine vessel. The results show that the proposed strategy can be promising in clinical studies.

Development and validation of a flexible fetoscope for fetoscopic laser coagulation.

Fetoscopic laser coagulation for twin-to-twin transfusion syndrome is challenging for anterior placenta due to the rigidity of current tools. The capacity to keep entry port forces minimal is critical for this procedure, as is optimal coagulation distance and orientation. This work introduces technological tools to this end. A novel fetoscope is presented with a rigid shaft and a flexible steerable segment at the distal end. The steerable segment can bend up to 90[Formula: see text] even when loaded with a laser fiber. An artificial pneumatic muscle makes such acute bending possible while allowing for a low-weight and disposable device. The flexible fetoscope was validated in a custom-made phantom model to measure visual range and coagulation efficacy. The flexible fetoscope shows promising results when compared to a clinical rigid curved fetoscope to reach anterior targets. The new fetoscope was then evaluated in vivo (pregnant ewe) where it successfully coagulated placental vasculature. The flexible fetoscope improved the ability to achieve optimal coagulation angle and distance on anteriorly located targets. The fetoscope also showed the potential to lead fetoscopic laser coagulation and other fetal surgical procedures toward safer and more effective interventions.

S2747 Malignant Peritoneal Mesothelioma Seen on MRI Enterography During IBD Colitis Investigation in a 32-Year-Old Non-Asbestos Exposed Female Healthcare Worker

Introduction: This case describes an unexpected diagnosis of a malignant peritoneal mesothelioma (MPM) in a 32 y/o female physician without any known asbestos exposure. She presented to our department with a prior diagnosis of non-celiac gluten intolerance and intermittent but worsening left-sided abdominal pain for over 20 years. Several CTs suggested findings associated with IBD-related etiology and IBD specialist consultation was advised. After negative EGD/colonoscopy, an MRI Enterography revealed a small enhancing nodule suggestive of peritoneal malignancy. Pathology report after biopsy revealed a biphasic MPM. This case highlights the insidious nature of MPM and adds to the body of literature suggestive of IBD-mimicking symptomatology associated with this disease. Case Description/Methods: A 32 y/o F presented with chronic intermittent left-sided abdominal pain and gluten intolerance. Throughout her life, she reports 2-week periods of abdominal pain that is usually dull and sometimes sharp. The pain is focused LUQ with occasional LLQ pain. This is worsened by acute angle bending and deep palpation to the area. The patient still experiences pain despite a gluten-free diet. EGD is negative for celiac disease. CT imaging showed a left-sided pericolonic abscess and wall thickening of the lower descending and proximal sigmoid colon. An ill-defined soft tissue density in the left paracolic gutter was also seen and classified as a reactive lymph node. Abscess underwent CT aspiration; follow-up CT noted a new focal area of segmental wall thickening in the ascending colon with an inflamed diverticulum. IBD consult was recommended where negative EGD/colonoscopy resulted in MRI Enterography referral and results suggestive of peritoneal malignancy (Figure). Pathologic examination confirmed the presence of MPM, biphasic type (epithelial/spindle) with cytologic atypia and invasive growth being consistent with malignancy. The patient is on nivolumab, ipilimumab, carboplatin, pemetrexed and leuprolide for the next 3 months and considering debulking. Discussion: MPM presenting with decades long history of LUQ/LLQ pain exacerbations is rarely seen. CT results led to consideration of IBD etiology, as wall thickening, inflamed diverticulum, and a timeline suggestive of IBD was described. The lack of asbestos exposure highlighted the unlikely MPM differential. Prompt advanced imaging was key to diagnosis. Due to the insidious nature of MPM and poor outcomes, further exploration of timely advanced imaging is warranted.Figure 1.: MRI enterography reveals no evidence of active or chronic inflammatory bowel disease and no evidence of diverticulitis or diverticular abscess. There is a 10 mm enhancing nodule along the serosal margin of the splenic flexure in the left upper quadrant that is suspicious for a peritoneal malignancy.

A vital and disregarded anatomical landmark: Descending sigmoid colon flexure

Background: During the colonoscopy, colon tortuosity is a vital factor to complete the procedure successfully. Endoscopy can be difficult in cases with acute angle bending of adjacent colon segments. Aim: To assess the relationship of descending sigmoid colon flexure to vital anatomical points on CT in adult subjects. Methods: 114 adult subjects with CT examination of the abdominopelvic region were retrospectively analyzed. In 114 subjects, the angle between proximal sigmoid and descending colon was evaluated in degrees along with descending-sigmoid flexure position concerning the anterior aspect of the 5th lumbar vertebra, the median plane, and left anterior superior iliac spine. Results: Descending sigmoid flexure was seen in all 114 subjects. the LV-DSF was significantly higher in male subjects, with a distance of 123.7±23.1mm compared to female subjects where it was 115.6±21.2. This was statistically significant with p&lt;0.005. MP-DSF in male subjects was 97.8±15.6mm which was significantly higher than the female subjects having MP-DSF of 88.8±14.0mm. The minimum to maximum for males and females respectively were 52-149 and 44-116 which was a statistically significant difference with p&lt;0.001. However, for ASIS-DSF, the distance did not differ significantly between males and females with p=0.54 Conclusions.

Twisted Tower – A Feasibility Study for Cold‐Bent Insulating Glass Units with an Elastic Edge Seal

This paper describes a case study of cold bent insulating glass units (IGUs) for use in facades or roofs using the example of a demonstrator called the “Twisted Tower”. Modern designs often try to combine a curved shape with transparency. Cold bending IGUs is a cost efficient method to achieve both. In such applications the bending angles are often limited by the allowable deformations of the primary seal which ensures the gas tightness of the IGU. This investigation shows IGUs with much more acute bending angles than in standard applications were achieved using a flexible yet durable thermoplastic spacer ensuring superior gas tightness. This work investigates the geometry, the deformations and fixing options for the bent IGU form. The results demonstrate the advantages of using such spacer systems for these applications.

Comparing the Use of Flexible and Rigid Reaming Systems Through an Anteromedial Portal for Femoral Tunnel Creation During Anterior Cruciate Ligament Reconstruction: A Systematic Review.

Background:Recent studies have suggested that femoral tunnel drilling during anterior cruciate ligament (ACL) reconstruction (ACLR) with the use of a flexible reaming system through a standard anteromedial portal (AM-FR) may result in a different tunnel geometry compared with a rigid reamer through an accessory anteromedial portal with hyperflexion (AM-RR).Purpose:To summarize radiologic, anatomic, and clinical outcomes from available studies that directly compared the use of AM-FR versus AM-RR for independent femoral tunnel creation during ACLR.Study Design:Systematic review; Level of evidence, 4.Methods:A literature search was performed using the MEDLINE (PubMed) and Web of Science databases to identify all studies that directly compared radiologic, anatomic, and clinical outcomes between the use of AM-FR and AM-RR. The literature search, data recording, and methodological quality assessment was performed by 2 independent reviewers. The outcomes analyzed included resultant ACL graft positioning and graft bending angle; femoral tunnel positioning, aperture morphology, length, and widening; posterior wall breakage; and distance from various posterolateral knee structures.Results:A total of 13 studies met the eligibility criteria for inclusion. There was no difference in femoral tunnel aperture location between techniques. There were conflicting findings among studies regarding which technique resulted in a more acute graft bending angle. One study reported greater femoral tunnel widening upon follow-up with the use of AM-FR. AM-FR produced longer and more anteverted femoral tunnels than did AM-RR. The difference in tunnel length was significant and more prominent in lesser degrees of knee flexion. With AM-FR, femoral tunnels were farther from the lateral collateral ligament and peroneal nerve, and 1 of 5 studies had fewer reports of posterior wall breakage. There has been no literature comparing the clinical or functional outcomes of these techniques.Conclusion:Although no clinical studies exist comparing AM-FR and AM-RR for femoral tunnel creation during ACLR, both systems allow for reproducible positioning of an anatomic femoral tunnel aperture. The use of AM-FR results in longer and more anteverted femoral tunnels than using AM-RR, with exit points on the lateral femur that are different but safe. Surgeons should be aware of the technical differences with each method; however, further study is needed to identify any clinically important difference that results.

Influence of Graft Bending Angle on Femoral Tunnel Widening After Double-Bundle ACL Reconstruction: Comparison of Transportal and Outside-In Techniques.

Background:Previous studies have suggested that increased mechanical stress due to acute graft bending angle (GBA) is associated with tunnel widening and graft failure after anterior cruciate ligament (ACL) reconstruction. Few studies have compared the GBA between the outside-in (OI) and the transportal (TP) techniques.Purpose:To evaluate the influence of GBA on clinical outcomes and tunnel widening after ACL reconstruction with OI versus TP technique.Study Design:Cohort study; Level of evidence, 3.Methods:Included in the study were 56 patients who underwent double-bundle ACL reconstruction (n = 28 in the OI group and n = 28 in the TP group). Clinical outcomes (Lysholm, International Knee Documentation Committee, Tegner score, and knee laxity) 1 year postoperatively were evaluated. Computed tomography scans at 5 days and 1 year postoperatively were used for imaging measurements, and the femoral tunnel was divided into the proximal third, middle, and aperture sections. The GBA and cross-sectional area (CSA) were measured using image analysis software and were compared between groups. A correlation analysis was performed to determine if the GBA affected clinical outcomes or tunnel widening.Results:No significant difference was observed in clinical outcomes between the groups. The GBA of both the anteromedial (AM) and posterolateral bundles were more acute in the OI group compared with the TP group (P < .05). The CSA at the AM tunnel aperture increased significantly in the OI group (84.2% ± 64.3%) compared with the TP group (51.4% ± 36.7%) (P = .04). However, there were no differences in the other sections. In the Pearson correlation test, GBA was not correlated with tunnel widening or clinical outcomes.Conclusion:Regardless of technique, the GBA did not have a significant influence on tunnel widening or clinical outcomes. Considering a wider AM tunnel aperture, a more proximal and posterior AM tunnel position might be appropriate with the OI technique.

Excellence in Research:A Hybrid Transtibial Technique Combines the Strengths of theAnteromedial Portal and Transtibial Approaches: A Prospective Randomized Controlled Trial

Objectives:Improved biomechanical and clinical outcomes have been reported when femoral anterior cruciate ligament (ACL) tunnels are centered on the native footprint. The anteromedial (AM) portal technique achieves improved aperture position when compared to a transtibial (TT) approach but sacrifices technical ease and creates a shorter more acutely angulated tunnel. A hybrid transtibial technique (HTT) technique using medial portal guidance of a flexible transtibial guide wire without the need for knee hyperflexion may combine the strengths of both the AM and TT approaches. The authors hypothesized that this HTT technique would achieve anatomic femoral tunnel apertures similar to the AM technique, but with longer and less angulated femoral tunnels similar to a TT technique.Methods:A prospective randomized controlled trial was implemented where 30 consecutive patients with acute, primary ACL tears were randomized to receive a TT, AM or HTT technique for their reconstruction. A total of 46 patients were assessed for eligibility in the investigation (Figure 1). All patients underwent 3D CT scans of the operative knee 6 weeks postoperatively to characterize tunnel positions. Femoral and tibial tunnel aperture positions and tunnel lengths, as well as the graft bending angle in the sagittal and coronal plane were measured.Results:There were no significant differences between the patient demographics of the three groups. Tibial tunnel lengths and aperture positions were identical between the three groups. The AM portal and HTT techniques achieved identical femoral aperture positions in regards to both height (p=0.75) and depth (p=0.72). On the other hand, compared to the AM portal and HTT techniques, respectively, femoral apertures created by the TT technique were significantly higher (p<0.001 and p<0.001) and shallower (p=0.001 and p<0.001) in the notch. The average femoral tunnel lengths varied significantly between the three groups measuring 35.16 mm, 41.64 mm, and 54.13 mm for the AM, HTT and TT groups, respectively (p<0.001). Lastly, there were no differences between the average coronal (164.0 degrees versus 158.8 degrees, p=0.190) and sagittal (114.0 degrees versus 111.0 degrees, p=0.358) graft bending angles between the TT and HTT groups, respectively. By contrast, compared to the TT and HTT groups, respectively, the graft bending angles created with an AM technique were significantly more acutely angled in the coronal (146.3 degrees, p<0.001, p<0.006) and sagittal (100.5 degrees, p=0.014, p=0.013) planes.Conclusion:The HTT technique achieves femoral aperture positions equally as anatomic as an AM portal technique, but with longer and less acutely oriented grafts similar to a transtibial approach. These advantages will decrease the incidence of graft tunnel mismatch as well as reduce the amount of stress imparted onto the graft by avoiding an acute graft bending angle. As such, this hybrid approach may represent a beneficial combination of both transtibial and AM portal techniques.

Graft bending angle of the reconstructed posterior cruciate ligament gradually decreases as knee flexion increases.

The purpose of the study was to determine the change in the graft bending angles at the femoral and tibial tunnel aperture in single-bundle posterior cruciate ligament (PCL) reconstruction. It was hypothesized that different knee flexion and different tunnel directions may affect changes of the femoral and tibial graft bending angle. The right knees of 12 male subjects were scanned with a high-resolution computed tomography scanner at 4 different knee flexion angles (0°, 45°, 90° and 135°). To begin with, the 3D knee models were created and manipulated with the use of several modeling programs. Single-bundle PCL reconstruction was then virtually conducted in a 90° flexion model: The femoral and tibial graft bending angle, according to the various knee flexion angles, was calculated using a special software program. The femoral graft bending angle significantly decreased as the knee flexion increased between 0° and 135° (all p < 0.001). The femoral graft bending angle of the AL graft showed the most obtuse angles among the three types of the graft beyond 45° of knee flexion. For the tibial graft bending angle, the anteromedial tunnel group showed significantly more acute tibial graft bending angle than the anterolateral tunnel group in all three types of the graft at all flexion angles (all p < 0.001). Changes in the femoral graft bending angle were generally affected by different knee flexion angles. The effect of tibial tunnel direction on the tibial graft bending angle was found to be significant. The clinical relevance is that a mostly obtuse femoral graft bending angle was shown by the AL graft among three types of the graft.

Theoretical assessment of donor–acceptor complexes [X(PPh3)2 → AlH2]+ (X = C–Pb): structures and bonding

Quantum chemical investigations at the BP86/def2-SVP, BP86/def2-TZVPP and BP86/TZ2P+ levels of theory have been done for the series of AlH2+ complexes that carry carbodiphosphorane and analogues called tetrylones [X(PPh3)2–AlH2]+ (Al-XPPh) (X = C–Pb) using charge and partitioning methods. The most stable structures of Al-XPPh have been found for carbone CPPh as a mildly side-on style in carbone complex Al-CPPh, while the heavier tetrylone adducts Al-SiPPh−Al-PbPPh have significantly different side-on fashions SiPPh−PbPPh, which exhibit the more acute bending angles in tilted forms linked to AlH2+ fragment. Bond dissociation energies (BDEs), De (kcal/mol), slightly decrease from the strongest bonded carbone, Al-CPPh, to the weaker bonded heavier homologues. The bulky tetrylone ligands XPPh have significantly influenced to the Al-X bond strength in complexes Al-XPPh when calculating BDEs with dispersion interaction. The NBO analysis revealed that the [X(PPh3)2 → AlH2]+ donation comes mainly from the σ- and π-contributions of the ligands. The EDA–NOCV calculations showed that the bond sturdiness of the Al–X bond results from the decrease in [X(PPh3)2 → AlH2]+ donation and electrostatic attraction. The EDA–NOCV data also indicated that AlH2+–tetrylone complexes exhibit not only (PPh3)2X → AlH2+ strong σ-donors and weak π-donors but also (PPh3)2X ← AlH2+ weak π-back donation as π–π electrons shared in complexes.

Comparison of Modified Transtibial and Outside-In Techniques in Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

To compare the bending angle of anterior cruciate ligament (ACL) graft at femoral tunnel, graft maturation, and tunnel positions and the clinical outcomes of the modified transtibial (mTT) and outside-in (OI) techniques. Patients who met the inclusion criteria were divided into the mTT group (n= 50) and the OI group (n= 50). Using 3-dimensional computed tomography (3-D CT), tunnel placement and femoral tunnel bending angle were analyzed. The 3.0-T magnetic resonance imaging (MRI) was used to assess the graft signal intensity (indicative of maturation) with signal/noise quotient (SNQ). Graft tension and synovialization were evaluated with second-look arthroscopy in all cases. Clinical and functional tests were completed at 36months of follow-up. When tunnel placements were analyzed using the quadrant method, no significant differences were found between the mTT group and the OI group. The femoral graft bending angle was reduced in the mTT group, and the total mean of SNQ values and mean SNQ values at the femoral intraosseous and proximal graft of the mTT group were significantly lower than in the OI group (P < .001), respectively. The femoral graft bending angle on the coronal and axial planes showed moderate-to-strong correlation with the SNQ values at the femoral intraosseous and proximal graft. Second-look arthroscopy revealed better synovialization in the mTT group than in the OI group (P= .040), with no significant difference in graft tension between the 2 groups (P= .328). Anatomic tunnel placements did not vary between the mTT group and the OI group. However, the mTT group had more benefits in femoral graft bending angle and showed higher graft maturity and better synovial coverage than the OI group, although there were no significant differences in clinicaloutcomes. The acute femoral graft bending angle might negatively affect the maturation of proximal graft. LEVELOF EVIDENCE: Level III, retrospective comparative study.

Optimal Condition to Create Femoral Tunnel Considering Combined Influence of Knee Flexion and Transverse Drill Angle in Anatomical Single-Bundle ACL Reconstruction Using Medial Portal Technique: 3D Simulation Study.

There has been no previous study using three-dimensional (3D) measurement on femoral tunnel characteristics according to the combined influence of various flexion angles of knee and transverse drill angles in single-bundle ACL reconstruction with transportal technique. The purpose of this study was to determine optimal condition of knee flexion angle and transverse drill angle to create secure femoral tunnel in single-bundle ACL reconstruction with transportal technique considering tunnel length, tunnel wall breakage, and graft bending angle. This study was conducted using simulation of 3D computed tomography of thirty subjects. Three variables of femoral tunnel changed according to combined influence of four flexion angles of knee and three transverse drill angles were measured: tunnel length, wall breakage, and graft bending angle. There was no case of short femoral tunnel less than 25 mm at 120° and 130° of flexion. There was no case of breakage of femoral tunnel at 120° of flexion with maximum transverse drill angle (MTA) and MTA-10° and at 130° of flexion. Considering effect on graft bending angle, decrease of flexion angle and transverse drill angle could be appropriate in creating femoral tunnel. Increased flexion angle and transverse drill angle secured femoral tunnel having sufficiently long length without wall breakage. However, avoiding excessive flexion angle and maximum transverse drill angle could be recommended because they tended to cause more acute graft bending angle.

Contact area between femoral tunnel and interference screw in anatomic rectangular tunnel ACL reconstruction: a comparison of outside-in and trans-portal inside-out techniques.

The purpose of this study was to compare the femoral tunnel length, the femoral graft bending angle at the femoral tunnel aperture, and the contact area between the femoral tunnel wall and an interference screw used for fixation in anatomic rectangular tunnel anterior cruciate ligament (ACL) reconstruction (ART ACLR). The study included 149 patients with primary ACL injury who underwent ART ACLR. Preoperatively, flexion angle of the index knee was checked under general anaesthesia. Those of less than 130° of passive flexion were assigned to the outside-in (OI) technique (78 patients), while the others to the trans-portal inside-out (TP) technique (71 patients). The patients underwent computed tomography with multiplanar reconstruction at 3-5weeks post-operatively. Femoral tunnel length, graft bending angle, and contact ratio between the IFS and femoral tunnel were assessed. P<0.05 was considered statistically significant. The femoral tunnel length in the OI technique was significantly longer than that in the TP technique (P<0.001). The femoral graft bending angle in the OI technique was significantly more acute than that in the TP technique (P<0.001). The contact ratio in the OI technique was significantly larger than that in the TP technique at every point in the femoral tunnel (P<0.001). The OI technique resulted in a more acute femoral graft bending angle, longer mean femoral tunnel length, and larger contact ratio than the TP technique after ART ACLR. Retrospective comparative study, Level III.

Role of tube size and intranasal compression of the nasotracheal tube in respiratory pressure loss during nasotracheal intubation: a laboratory study

BackgroundSmall nasotracheal tubes (NTTs) and intranasal compression of the NTT in the nasal cavity may contribute to increasing airway resistance. Since the effects of size, shape, and partial compression of the NTT on airway resistance have not been investigated, values of airway resistance with partial compression of preformed NTTs of various sizes were determined.MethodsTo determine the factors affecting the respiratory pressure loss during the nasotracheal intubation, physical and fluid dynamics simulations were used. The internal minor axes of NTTs in the nasal cavity of intubated patients were measured using dial calipers. In physical and fluid dynamics simulations, pressure losses through the tubular parts, compressed parts, and slip joints of NTTs with internal diameters (IDs) of 6.0, 6.5, 7.0, 7.5, and 8.0 mm were estimated under partial compression.ResultsThe median internal minor axes of the 7.0- and 7.5-mm ID NTTs in the nasal cavity were 5.2 (4.3–5.6) mm and 6.0 (4.2–7.0) mm, respectively. With a volumetric air flow rate of 30 L/min, pressure losses through uncompressed NTTs with IDs of 6.0-, 6.5-, 7.0-, 7.5- and 8.0-mm were 651.6 ± 5.7 (6.64 ± 0.06), 453.4 ± 3.9 (4.62 ± 0.04), 336.5 ± 2.2 (3.43 ± 0.02), 225.2 ± 0.2 (2.30 ± 0.00), and 179.0 ± 1.1 Pa (1.82 ± 0.01 cmH2O), respectively; the pressure losses through the slip joints were 220.3 (2.25), 131.1 (1.33), 86.8 (0.88), 57.1 (0.58), and 36.1 Pa (0.37 cmH2O), respectively; and the pressure losses through the curvature of the NTT were 71.6 (0.73), 69.0 (0.70), 64.8 (0.66), 32.5 (0.33), and 41.6 Pa (0.42 cmH2O), respectively. A maximum compression force of 34.1 N increased the pressure losses by 82.0 (0.84), 38.0 (0.39), 23.5 (0.24), 16.6 (0.17), and 9.3 Pa (0.09 cmH2O), respectively.ConclusionPressure losses through NTTs are in inverse proportion to the tubes’ IDs; greater pressure losses due to slip joints, acute bending, and partial compression of the NTT were obvious in small NTTs. Pressure losses through NTTs, especially in small NTTs, could increase the work of breathing to a greater extent than that through standard tubes; intranasal compression further increases the pressure loss.

Limb flexion-induced axial compression and bending in human femoropopliteal artery segments

BackgroundHigh failure rates of femoropopliteal artery (FPA) interventions are often attributed in part to severe mechanical deformations that occur with limb movement. Axial compression and bending of the FPA likely play significant roles in FPA disease development and reconstruction failure, but these deformations are poorly characterized. The goal of this study was to quantify axial compression and bending of human FPAs that are placed in positions commonly assumed during the normal course of daily activities. MethodsRetrievable nitinol markers were deployed using a custom-made catheter system into 28 in situ FPAs of 14 human cadavers. Contrast-enhanced, thin-section computed tomography images were acquired with each limb in the standing (180 degrees), walking (110 degrees), sitting (90 degrees), and gardening (60 degrees) postures. Image segmentation and analysis allowed relative comparison of spatial locations of each intra-arterial marker to determine axial compression and bending using the arterial centerlines. ResultsAxial compression in the popliteal artery (PA) was greater than in the proximal superficial femoral artery (SFA) or the adductor hiatus (AH) segments in all postures (P = .02). Average compression in the SFA, AH, and PA ranged from 9% to 15%, 11% to 19%, and 13% to 25%, respectively. The FPA experienced significantly more acute bending in the AH and PA segments compared with the proximal SFA (P < .05) in all postures. In the walking, sitting, and gardening postures, average sphere radii in the SFA, AH, and PA ranged from 21 to 27 mm, 10 to 18 mm, and 8 to 19 mm, whereas bending angles ranged from 150 to 157 degrees, 136 to 147 degrees, and 137 to 148 degrees, respectively. ConclusionsThe FPA experiences significant axial compression and bending during limb flexion that occur at even modest limb angles. Moreover, different segments of the FPA appear to undergo significantly different degrees of deformation. Understanding the effects of limb flexion on axial compression and bending might assist with reconstructive device selection for patients requiring peripheral arterial disease intervention and may also help guide the development of devices with improved characteristics that can better adapt to the dynamic environment of the lower extremity vasculature.

Three-Dimensional Reconstruction Computed Tomography Evaluation of the Tunnel Location and Angle in Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction: A Comparison of the Anteromedial Portal and Outside-in Techniques

PurposeThe purpose of this study was to compare the geometry and position of the femoral tunnel between the anteromedial portal (AMP) and outside-in (OI) techniques after anatomic single-bundle anterior cruciate ligament (ACL) reconstruction.Materials and MethodsWe evaluated 82 patients undergoing single-bundle ACL reconstruction with hamstring autografts using either the AMP (n=40) or OI (n=42) technique. The locations of the tunnel apertures were assessed by postoperative 3-dimensional computed tomography imaging. The femoral graft bending angle, femoral tunnel aperture shape, femoral tunnel length, and posterior wall breakage were also measured.ResultsThe mean femoral tunnel position parallel to the Blumensaat line was more caudally positioned in the AMP group than in the OI group (p=0.025) The mean femoral graft angle in the OI group (99.6°±7.1°) was significantly more acute than that of the AMP group (108.9°±10.2°, p<0.001). The mean height/width ratio of the AMP group (1.21±0.20) was significantly more ellipsoidal than that of the OI group (1.07±0.09, p<0.001).ConclusionsThe mean femoral tunnel position was significantly shallower in the AMP technique than in the OI technique. The OI technique might be more disadvantageous than the AMP technique in terms of the more acute bending angle.