Novel and reproducible technique coping with intraoperative anchor pullout during arthroscopic rotator cuff repair.

PURPOSE: To evaluate the incidence of intraoperative anchor pullout during arthroscopic rotator cuff repair, to compare the outcomes of different methods of managing anchor pullout, and to introduce a new technique for anchor pullout. METHODS: 1076 patients who underwent arthroscopic rotator cuff repair using a single-row repair technique were included. In 483 patients, rotator cuff repair was performed using a screw-in type anchor, and in 593 patients, soft anchors were used. When intraoperative anchor pullout occurred, it was managed by buddy screwing, anchor insertion in a different location, cement augmentation, or by bar anchoring using a threaded Steinmann pin. Plain radiography and sonography were used to check anchor locations and healing. RESULTS: Fifty-two patients experienced anchor pullout intra- or postoperatively (48 and four patients, respectively). Anchor pullouts were more frequently observed for larger tears, women, older patients, and in patients with preoperative stiffness (limitations of both active and passive movements of the affected shoulder joint). For screw-in type anchors, pullout during surgery occurred in 16 patients (3.3%, 16/483), and all were managed using the buddy screwing technique. For soft anchor cases, pullout occurred in 32 patients (5.4%, 32/593) and was managed by anchor insertion in a different location (17 patients), cement augmentation (two patients), or bar anchoring using a threaded Steinmann pin (13 patients). Three patients managed by buddy screwing and two patients managed by anchor insertion in a different location had anchor failure after repair. Tendon healing at 6 months was observed in 12/16 patients treated by buddy screwing, 11/17 treated by anchor insertion in a different location, 2/2 treated by cement augmentation, and 12/13 treated by bar anchoring with a threaded Steinmann pin. CONCLUSION: Intraoperative anchor pullout during arthroscopic rotator cuff repair is an uncommon but cumbersome complication. There are some techniques already introduced to deal with this complication. In comparison, not one technique is overwhelmingly superior to others; however, our new technique which is bar anchoring with a threaded Steinmann pin could be another solution, since it could utilize primary anchor sites and results appear to be acceptable. Level of evidence III.

Effect of preoperative teres minor hypertrophy on reverse total shoulder arthroplasty.

BACKGROUND: The preoperative status of the teres minor (Tm) can affect the outcome of reverse total shoulder arthroplasty (RTSA). The effect of preoperative Tm hypertrophy on the outcome of RTSA is unclear. METHODS: A total of 86 shoulders that underwent RTSA were retrospectively enrolled. Of these, 48 cases with a Tm occupation ratio (OR) of >0.288 in the preoperative magnetic resonance image were assigned to the hypertrophic group, and 38 cases to the control group. The two groups were compared with respect to preoperative rotator cuff tear involvement, fatty infiltration, pre- and postoperative rotator cuff ORs, pain scores, functional scores, range of motion, and muscle strength. Postoperative Tm ORs in 1-year follow-up multidetector computed tomography were compared with preoperative Tm ORs. RESULTS: Preoperatively, integrities of infraspinatus (ISP) and supraspinatus were significantly different between the 2 groups (P = .001, 0.009, each). Preoperative ISP ORs were significantly related to preoperative Tm ORs (r = -0.534, P < .001). The mean pre- to postoperative change of Tm ORs in the hypertrophic group decreased (-0.029 ± 0.068), whereas that of the control group increased (+0.047 ± 0.092). Postoperative pain scores, functional scores, range of motion, and muscle strength were not different between groups. CONCLUSIONS: In cases of advanced rotator cuff tear requiring RTSA, Tm hypertrophy is found to be related to tear and atrophy of the ISP, suggesting that Tm hypertrophy is a compensatory change for ISP dysfunction. However, Tm hypertrophy was observed to diminish after RTSA. Preoperative Tm hypertrophy appears to have no beneficial effect on the outcomes of RTSA.

Overgrowth of the lower limb after treatment of developmental dysplasia of the hip: incidence and risk factors in 101 children with a mean follow-up of 15 years.

Background and purpose - There are few studies on overgrowth of the affected limb after treatment of developmental dysplasia of the hip (DDH). We investigated the incidence of overgrowth and its risk factors in DDH patients.Patients and methods - 101 patients were included in this study. Overgrowth was defined by 2 criteria: when the height of the femoral head of the affected side was higher than that of the contralateral side by more than 10 mm, or by more than 15 mm. The potential risk factors of distinct overgrowth were retrospectively examined using multivariable analysis.Results - When overgrowth was defined as femoral head height difference (FHHD) > 10 mm, its incidence was 44%, and only femoral osteotomy was identified as a significant risk factor with a relative risk (RR) of 1.6 (95% confidence interval [CI] 1.0-2.5). When overgrowth was defined as FHHD > 15 mm, its incidence was 23%, and femoral osteotomy was identified as the only significant risk factor with an RR of 2.3 (CI 1.2-4.5). Overgrowth developed more frequently in patients who underwent femoral osteotomy at the age of 2 to 4 years (87%) than in the others (46%) (p = 0.04).Interpretation - Overgrowth of the affected limb is common in DDH patients. Patients who underwent femoral osteotomy, especially at the age of 2 to 4 years, may require careful follow-up because of the substantial risk for overgrowth.

Role of Surfactant in Evaporation and Deposition of Bisolvent Biopolymer Droplets.

Inkjet printing of biopolymer droplets is gaining popularity because of its potential applications in regenerative medicine, particularly the fabrication of tissue-regenerative scaffolds. The quality of bioprinting, which affects cellular behaviors and the subsequent tissue formation, is determined by the solvent evaporation and deposition processes of biopolymer droplets, during which instantaneous local viscosity and surface tension changes occur because of the redistribution of the biopolymer inside the drop. Such dynamics is complex and not well understood. Most biopolymer inks also contain multiple solvents of distinct evaporation rates, further complicating the system dynamics. Using high-speed interferometry, we directly observe in real time the instantaneous drop shape of inkjet-printed picoliter gelatin drops containing glycerol and water. It is observed that, for bisolvent gelatin drops with surfactants, highly viscous gelatin and glycerol accumulated near the pinned contact line at an early stage suppress the evaporation-driven outward flow and create a stagnation zone near the contact line region. Lower surface tension at the contact line, because of its high local surfactant concentration, as compared to the drop apex induces a strong Marangoni recirculation, which in conjunction with a stagnation zone in the contact line region causes the instantaneous drop shape to transition from a spherical cap to a volcano shape during evaporation and resulting in a volcano-like deposition profile. In contrast, the suppressed evaporation outward flow together with a weak Marangoni flow leads to a domelike deposition for the case without surfactant. The role of surfactant in polymer drop deposition with water-only solvent is also investigated and compared against that of bisolvent drops. For the single-solvent case, the deposition profile is found to shift from a coffee-eye shape in the presence of surfactant to a uniform deposition without surfactant. The results reveal new insight into the complex role surfactant plays during polymer drop evaporation and deposition processes.

Micropattern-controlled wicking enhancement in hierarchical micro/nanostructures.

Wicking in hierarchical micro/nanostructured surfaces has attracted significant attention due to its potential applications in thermal management, moisture capturing, drug delivery, and oil recovery. Although some studies have shown that hierarchical structures enhance wicking over micro-structured surfaces, others have found very limited wicking improvement. In this study, we demonstrate the importance of micropatterns in wicking enhancement in hierarchical surfaces using ZnO nanorods grown on silicon micropillars of varying spacings and heights. The wicking front over hierarchical surfaces is found to follow a two-stage motion, where wicking is faster around micropillars, but slower in between adjacent pillar rows and the latter stage dictates the wicking enhancement in hierarchical surfaces. The competition between the added capillary action and friction due to nanostructures in these two different wicking stages results in a strong dependence of wicking enhancement on the height and spacing of the micropillars. A scaling model for the propagation coefficient is developed for wicking in hierarchical surfaces considering nanostructures in both wicking stages and the model agrees well with the experiments. This microstructure-controlled two-stage wicking characteristic sheds light on a more effective design of hierarchical micro/nanostructured surfaces for wicking enhancement.

The effect of particle wettability on the stick-slip motion of the contact line.

Contact line dynamics is crucial in determining the deposition patterns of evaporating colloidal droplets. Using high-speed interferometry, we directly observe the stick-slip motion of the contact line in situ and are able to resolve the instantaneous shape of the inkjet-printed, evaporating pico-liter drops containing nanoparticles of varying wettability. Integrated with post-mortem optical profilometry of the deposition patterns, the instantaneous particle volume fraction and hence the particle deposition rate can be determined. The results show that the stick-slip motion of the contact line is a strong function of the particle wettability. While the stick-slip motion is observed for nanoparticles that are less hydrophilic (i.e., particle contact angle θ ≈ 74° at the water-air interface), which results in a multiring deposition, a continuous receding of the contact line is observed for more hydrophilic nanoparticles (i.e., θ ≈ 34°), which leaves a single-ring pattern. A model is developed to predict the number of particles required to pin the contact line based on the force balance of the hydrodynamic drag, interparticle interactions, and surface tension acting on the particles near the contact line with varying particle wettability. A three-fold increase in the number of particles required for pinning is predicted when the particle wettability increases from the wetting angle of θ ≈ 74° to θ ≈ 34°. This finding explains why particles with greater wettability form a single-ring pattern and those with lower wettability form a multi-ring pattern. In addition, the particle deposition rate is found to depend on the particle wettability and vary with time.

Deposition of Colloidal Drops Containing Ellipsoidal Particles: Competition between Capillary and Hydrodynamic Forces.

Ellipsoidal particles have previously been shown to suppress the coffee-ring effect in millimeter-sized colloidal droplets. Compared to their spherical counterparts, ellipsoidal particles experience stronger adsorption energy to the drop surface where the anisotropy-induced deformation of the liquid-air interface leads to much greater capillary attractions between particles. Using inkjet-printed colloidal drops of varying drop size, particle concentration, and particle aspect ratio, the present work demonstrates how the suppression of the coffee ring is not only a function of particle anisotropy but rather a competition between the propensity for particles to assemble at the drop surface via capillary interactions and the evaporation-driven particle motion to the contact line. For ellipsoidal particles on the drop surface, the capillary force (Fγ) increases with the particle concentration and aspect ratio, and the hydrodynamic force (Fµ) increases with the particle aspect ratio but decreases with drop size. When Fγ/Fµ > 1, the surface ellipsoids form a coherent network inhibiting their migration to the drop contact line, and the coffee-ring effect is suppressed, whereas when Fγ/Fµ < 1, the ellipsoids move to the contact line, resulting in coffee-ring deposition.

Colloidal Drop Deposition on Porous Substrates: Competition among Particle Motion, Evaporation, and Infiltration.

Recent interest in printable electronics and in particular paper- and textile-based electronics has fueled research in inkjet printing of colloidal drops on porous substrates. On nonporous substrates, the interplay of particle motion and solvent evaporation determines the final deposition morphology of the evaporating colloidal drop. For porous substrates, solvent infiltration into the pores adds a layer of complexity to the deposition patterns that have not been fully elucidated in the literature. In this study, the deposition of picoliter-sized aqueous colloidal droplets containing nanometer- and micrometer-sized particles onto nanoporous anodic aluminum oxide substrates is examined for different drop and particle sizes and relative humidities as well as pore diameters, porosities, and wettabilities of the porous substrates. For the cases considered, solvent infiltration is found to be much faster than both evaporation and particle motion near the contact line, and thus when the substrate fully imbibes the solvent, the well-known "coffee-ring" deposition is suppressed. However, when the solvent is only partially imbibed, a residual droplet volume exists upon completion of the infiltration. For such cases, two time scales are of importance: the time for particle motion to the contact line as a result of both diffusion and advection, t(P), and the evaporation time of the residual drop volume, t(EI). Their ratio, t(P)/t(EI), determines whether the coffee-ring deposition will be formed (t(P)/t(EI) < 1) or suppressed (t(P)/t(EI) > 1).

Determining optimal bead central angle by applying machine learning to wire arc additive manufacturing (WAAM).

Wire arc additive manufacturing (WAAM) is being extensively used in various industrial fields. In WAAM, if a bead is deposited without considering the central angle, its shape may collapse with increasing number of layers. To address this problem, a new method for optimizing the bead geometry using a support vector machine (SVM) classifier was established in this study. The ranges of the optimal deposition conditions were determined using the SVM classifier and verified by experiments. Geometric data of deposited beads were extracted using a laser profiler, and an SVM binary classifier was used to predict suitable ranges of the deposition conditions. Data were extracted through 20 single-layer basic experiments, classification was performed based on 4°, and the appropriateness of SVM classification was found through 8 single-layer and 3 multi-layer verification experiments. The results showed that the SVM classifier successfully selected the ranges of the optimal deposition conditions. Verification experiments revealed that the results in all cases were appropriately classified based on the boundary of the classification line. Moreover, the SVM classifier was efficient even when a small amount of input data was available. The contribution of this study is that the developed method can help build desired bead geometries in scenarios where deposition is required in the WAAM process, such as re-manufacturing. Thus, this method can be used in real-world industrial applications through further research on the bead shape with multi-layer deposition.

Shape- and orientation-dependent diffusiophoresis of colloidal ellipsoids.

We present the diffusiophoresis of ellipsoidal particles induced by ionic solute gradients. Contrary to the common expectation that diffusiophoresis is shape independent, here we show experimentally that this assumption breaks down when the thin Debye layer approximation is relaxed. By tracking the translation and rotation of various ellipsoids, we find that the phoretic mobility of ellipsoids is sensitive to the eccentricity and the orientation of the ellipsoid relative to the imposed solute gradient, and can further lead to nonmonotonic behavior under strong confinement. We show that such a shape- and orientation-dependent diffusiophoresis of colloidal ellipsoids can be easily captured by modifying theories for spheres.

4D printing of self-folding and cell-encapsulating 3D microstructures as scaffolds for tissue-engineering applications.

Technology of tissue-engineering advanced rapidly in the last decade and motivated numerous studies in cell-engineering and biofabrication. Three-dimensional (3D) tissue-engineering scaffolds play a critical role in this field, as the scaffolds provide the biomimetic microenvironments that could stimulate desired cell behaviors for regeneration. However, despite many achievements, the fabrication of 3D scaffold remains challenging due to the difficulty of encapsulating cells in 3D scaffolds, controlling cell-cell organization in 3D, and being adapted by users unfamiliar with 3D biofabrication. In this study, we circumvent these obstacles by creating a four-dimensional (4D) inkjet-printing platform. This platform produces micropatterns that self-fold into a 3D scaffold. Seeding live cells uniformly onto the micropatterns before self-folding leads to cell-encapsulating 3D scaffolds with layer-wise cell-cell organization. Photo-crosslinkable biomaterial-inks of distinct swelling rates were synthesized from gelatin, and the biomaterial-inks were patterned by a customized high-precision inkjet-printer into bilayer micropatterns that were capable of self-folding into 3D microstructures. A mathematical model was developed to help design self-folding and to aid the understanding of the self-folding mechanism. Human umbilical vein endothelial cells (HUVECs) were embedded in self-folded microtubes to mimic microvessels. HUVECs in the microtube spread, proliferated, showed high cell viability, and engrafted on the microtube's inner wall mimicking the native endothelial cells. For physician and biologist end-users, this 4D printing method provides an easy-to-use platform that supports standard two-dimensional cell-seeding protocol while enabling the users to customize 3D cellularized scaffold as desired. This work demonstrated 4D printing as a promising tool for tissue-engineering applications.

Validation and Cross-cultural Adaptation of the Korean Version of the Zurich Claudication Questionnaire in Patients With Lumbar Spinal Stenosis.

STUDY DESIGN: Linguistic and psychometric validation of a translated questionnaire. OBJECTIVE: To validate the Korean version of Zurich claudication questionnaire (ZCQ) both linguistically and psychometrically. SUMMARY OF BACKGROUND DATA: The ZCQ is considered as a disease specific and gold standard measure for evaluation of patients with lumbar spinal stenosis (LSS). However, there has been no validated Korean version of the ZCQ. METHODS: The ZCQ was translated forward and backward, culturally adapted by 2 independent translators, and approved by an expert committee. The final version of the Korean ZCQ was added to a routine questionnaire including a visual analog pain scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and the European Quality of Life-5 dimensions (EQ-5D). Psychometric validation included reliability by internal consistency using Cronbach's alpha, the test-retest reliability using intraclass correlation coefficient (ICC), and concurrent validity by comparing the Korean ZCQ to VAS for back/leg pain, ODI, and EQ-5D using Pearson correlation. RESULTS: A total of 109 patients were included in this study. The test-retest intraclass correlation coefficient (ICC) of the ZCQ was shown to have good reliability for all three domains: the ICCs for symptom, function, and satisfaction domains were 0.79, 0.84, and 0.91, respectively. Internal consistency of the Korean ZCQ for the symptom, function, and satisfaction domains was also excellent (Cronbach α = 0.894, 0.939, and 0.961, respectively). For concurrent validity, all three domains of the Korean ZCQ were significantly correlated with external criteria including VAS for back/leg pain, ODI, and EQ-5D. In the assessment of responsiveness, 21 patients who completed the ZCQ both before and after surgery demonstrated significantly different scores for symptom and disability domains. CONCLUSION: The validated Korean version of the ZCQ is a transculturally equivalent, reliable, and valid tool for use in assessing symptoms, function, and satisfaction with treatment in patients with LSS. LEVEL OF EVIDENCE: 3.

Quantitative evaluation of acquisition parameters in three-dimensional imaging with multidetector computed tomography using human skull phantom.

This study evaluated the quantitative measurements of three-dimensional (3D) volume images using multidetector row computed tomography (MDCT) and one skull specimen. Twenty-one linear distances were measured five times each by vernier caliper. A dry human skull was imaged with MDCT for various acquisition parameters at slice thicknesses of 1.25, 2.50, 3.75, and 5.00 mm for the different acquisition modes of axial and spiral scan. The distance of each corresponding item displayed on 3D rendered images was measured seven times by an uninvolved observer using a 3D software tool. Data analysis was performed to determine if there were any statistically significant differences in acquisition parameters. No significant image differences were found among the scan modes for each slice thickness. For a given scan mode, acquisition slice thickness was the important factor for quantitative measurement of 3D rendered CT images.

Quantitative analysis of three-dimensional rendered imaging of the human skull acquired from multi-detector row computed tomography.

The purpose of this study was to evaluate the quantitative accuracy of three-dimensional (3D) rendered images acquired with multi-detector row computed tomography (MDCT) by means of distance measurements of a dry human skull for various slice thicknesses and acquisition modes. A radiologist directly measured the distance of line items on the skull surface to establish reference "gold standards." The skull specimen was scanned with a MDCT with various scanning parameters (slice thicknesses and acquisition modes). An observer measured the corresponding distances of the same items on 3D rendered images. The quantitative accuracy of distance measurements was statistically evaluated. There were no significant statistical differences (P value <.05) in accuracy of distance measurements among the scan modes. However, the results showed that acquisition slice thickness was the influential factor in determining the accuracy of the 3D rendered MDCT images. The quantitative analysis of distance measurement may be a useful tool evaluating the accuracy and defining optimal parameters of 3D rendered images.