Spring Placement Research Articles

A modified tweezer for stable open coil spring placement

A modified tweezer for stable open coil spring placement

Designing continuous equilibrium structures that counteract gravity in any orientation

This paper presents a framework that can transform reconfigurable structures into systems with continuous equilibrium. The method involves adding optimized springs that counteract gravity to achieve a system with a nearly flat potential energy curve. The resulting structures can move or reconfigure effortlessly through their kinematic paths and remain stable in all configurations. Remarkably, our framework can design systems that maintain continuous equilibrium during reorientation, so that a system maintains a nearly flat potential energy curve even when it is rotated with respect to a global reference frame. This ability to reorient while maintaining continuous equilibrium greatly enhances the versatility of deployable and reconfigurable structures by ensuring they remain efficient and stable for use in different scenarios. We apply our framework to several planar four-bar linkages and explore how spring placement, spring types, and system kinematics affect the optimized potential energy curves. Next, we show the generality of our method with more complex linkage systems that carry external masses and with a three-dimensional origami-inspired deployable structure. Finally, we adopt a traditional structural engineering approach to give insight on practical issues related to the stiffness, reduced actuation forces, and locking of continuous equilibrium systems. Physical prototypes support the computational results and demonstrate the effectiveness of our method. The framework introduced in this work enables the stable, and efficient actuation of reconfigurable structures under gravity, regardless of their global orientation. These principles have the potential to revolutionize the design of robotic limbs, retractable roofs, furniture, consumer products, vehicle systems, and more.

THE SACRAL SPRINGS OF THE LVIV REGION IN THE STRUCTURE OF LANDSCAPES

Water springs as a component of the landscape not only ensure the water balance of the territory, but also influence the formation of culture and traditions of regional communities. The scientific interest of studying water springs, in particular sacral ones, is connected with their important social and natural functions.
 In the period when Russia's aggression (war) against Ukraine continues, the study of the sacred features of geographical objects will provide not only a scientific result, but also contribute to the preservation of the leading worldview ideas and values of society.
 The article describes the physical and geographical prerequisites for the formation of water sources in the Lviv region. The greatest potential of fresh groundwater in the region is recorded in the Volhynian-Podolian artesian basin, where aquifer complexes are confined to Neogene, Upper Cretaceous, and in the east to Devonian deposits. The studied territory has a significant potential of mineral waters of different chemical composition and medicinal properties.
 According to the materials of the Basin Management of Water Resources of the Western Bug and San Rivers, there are 454 water sources in the territory of Lviv region, of which 111 are consecrated, with a total flow rate of 65.94 l/s. 84% of the sacral springs of the Lviv region are in satisfactory condition and equipped. The largest number of them is confined to the basin of the Dniester River. In this basin, out of 72 functioning sanctified springs, 58 are in satisfactory condition and equipped, 14 need improvement and cleaning. Undoubtedly, the largest number of springs in the Dniester basin is due to the fact that it is the main water artery of the Lviv region, with a catchment area of 11,420 km2 and a length of 207 km. Within the region, the basin of the Western Bug River covers an area of ‒ 6,586 km2. There are 20 sacral springs, 16 of them are in satisfactory condition and equipped. In the basin of the Styr River, 16 sacral springs are recorded, which are characterized by a satisfactory condition. The smallest number of sacral springs is located in the basin of the San River, the discharge of which reaches only 1.2 l/s.
 Spatial analysis of the placement of sacral springs within the physical-geographical regions/districts proves that their highest concentration is recorded in the flat part of the region. The largest share of them is observed in the Roztochia-Opillya mountainous physical-geographical region (45), in particular in the Mykolaiv-Berezhany physical-geographical district (33). There are 24 sacral springs in the Precarpathian highland region; in the region of Male Polissya – 17; Outer Carpathian region – 13; West Podillya highland region − 11. The rest of the physical and geographical regions within the Lviv region (Volyn highland region, Vododilno-Verkhovyna region) occupy relatively small areas, where almost no sacral springs have been recorded.
 The revealed dependencies of the spatial placement of sacral springs within the Lviv region show that their distribution, density, grouping and functioning clearly depend on the surrounding natural features, which forms their structural organization. Such organization is largely implemented in the spatial grouping of springs. There are single, double, blocks (groups), compacted-spatial, network-dispersed and ribbon groupings of sacral springs. Each of the types of such groups is characterized by its own characteristics, which is realized in their sacral use.
 The current state of the most famous sacral springs of the region, which are characterized by a large flow of visitors, is analyzed. All these sources have a good infrastructure, which ensures the realization of spiritual, cognitive educational needs of visitors.
 Performing the role of the central object of the formation of the sacral landscape, sacral springs have a landscape-organizing function, which gives them an exceptional stabilizing and order-protecting value.
 Keywords: sacral landscape, sacral spring, Lviv region.

Internal plication for spring confinement to lengthen intestine in a porcine model.

Short bowel syndrome and its resultant nutritional deficiencies are the most common cause of intestinal failure. Significant intestinal lengthening using intraluminal springs is feasible in porcine models using an external plication technique. We hypothesize that an internal plication technique will yield significant intestinal lengthening, which may lead to future endoscopic spring placement. Uncompressed springs measuring 7.5 cm with a diameter of 1.0 cm were compressed to 2.0 cm. A gelatin-encapsulated compressed nitinol spring was inserted into the jejunal lumen of juvenile pigs and held in place with endoluminal sutures just proximal and distal to the spring-containing segment. A control segment distal to the spring was marked. Pigs were euthanized on postoperative day 7. Spring and control segments were collected for analyses. There was an average lengthening by 72% of the spring segment compared to the control segment. Two out of 7 springs stayed within both sets of plications and doubled in length. Histology showed normal mucosal integrity of the spring segment and plicated areas with similar muscular thickness but increased crypt depth and villus length compared to the control segment. Internal plication resulted in significant bowel lengthening. Five springs had slipped through proximal, distal or both sets of plications, resulting in less lengthening than those that remained fixed. A more consistent methodology for endoluminal suturing is needed to produce more lengthening.

Predicting Changes in Cephalic Index Following Spring-mediated Cranioplasty for Nonsyndromic Sagittal Craniosynostosis: A Stepwise and Machine Learning Algorithm Approach.

Spring-mediated cranioplasty (SMC) is an increasingly utilized technique to treat patients with nonsyndromic sagittal craniosynostosis, but variables impacting outcomes are incompletely understood. The purpose of this study was to determine variables most predictive of outcomes following SMC, primarily changes in cephalic index (CI). Patients with nonsyndromic sagittal craniosynostosis undergoing SMC at our institution between 2014 and 2021 were included. Cephalic index was measured from patient computed tomography scans, x-rays, or by caliper-based methods. Parietal bone thickness was determined from patient preoperative computed tomography. Stepwise multiple regression analysis, least absolute shrinkage and selection operator, and random forest machine learning methods were used to determine variables most predictive of changes in CI. One hundred twenty-four patients were included. Stepwise multiple regression analysis identified duration of spring placement ( P =0.007), anterior spring force ( P =0.034), and anterior spring length ( P =0.043) as statistically significant predictors for changes in CI. Least absolute shrinkage and selection operator analysis identified maximum spring force (β=0.035), anterior spring length (β=0.005), posterior spring length (β=0.004), and duration of spring placement (β=0.0008) as the most predictive variables for changes in CI. Random forest machine learning identified variables with greatest increase in mean squared error as maximum spring force (0.0101), anterior spring length (0.0090), and posterior spring length (0.0056). Maximum and total spring forces, anterior and posterior spring lengths, and duration of spring placement were the most predictive variables for changes in CI following SMC. Age at surgery and other demographic variables were inferior predictors in these models.

Comparison of Under-Actuated and Fully Actuated Serial Robotic Arms: A Case Study

Abstract Under-actuated robots are very interesting in terms of cost and weight since they can result in a state-controllable system with a number of actuators lower than the number of joints. In this paper, a comparison between an under-actuated planar three-degrees-of-freedom (DOF) robot and a comparable fully actuated two-degrees-of-freedom robot is presented, mainly focusing on the performances in terms of trajectories, actuator torques, and vibrations. The under-actuated system is composed of two active rotational joints followed by a passive rotational joint equipped with a torsional spring. The fully actuated robot is inertial equivalent to the under-actuated manipulator: the last link is equal to the sum of the last two links of the under-actuated system. Due to the conditions on the inertia distribution and spring placement, in a simple point-to-point movement the last passive joint starts and ends in a zero-value configuration, so the three DOF robot is equivalent, in terms of initial and final configuration, to the two DOF fully actuated robot, thus they can be compared. Results show how while the fully actuated robot is better in terms of reliable trajectory and actuator torques, the under-actuated robot wins in flexibility and in vibrations at a given configuration.

Distraction enterogenesis in the murine colon

Background/PurposeDistraction enterogenesis with intraluminal spring technology has been successfully used to lengthen segments of murine small intestine. We hypothesized that biocompatible springs could also be used to lengthen murine large intestine. MethodsAge and weight matched C57BL/6 mice underwent surgical insertion of nitinol spring-loaded capsules into the cecum. Segment lengths were measured at initial spring placement and at euthanasia after 7 and 14 days. Histologic adaptations were evaluated at scarification. ResultsCecal segments loaded with compressed springs lengthened an average of 150%, which was significantly longer than control segments loaded with either empty capsules or uncompressed springs. Muscularis layers tended to be thicker in the compressed spring groups compared to control groups. ConclusionsInsertion of a compressed nitinol spring into the cecum results in significant colonic lengthening in a mouse model. The ability to increase cecum length serves as proof of concept that distraction enterogenesis technology may be feasibly applied to large intestinal models. The use of distraction enterogenesis technology shows promise for application to clinical models in the treatment of pediatric intestinal disease.

Utility of Preoperative Helmet Molding Therapy in Patients With Isolated Sagittal Craniosynostosis.

The purpose of this study was to review our institution's experience using helmet molding therapy in children with isolated non-syndromic sagittal craniosynostosis before placement of cranial springs and provide objective measurements of craniometric changes to help determine its role in treatment.Patients who underwent preoperative helmet molding therapy for sagittal craniosynostosis were retrospectively reviewed. Three-dimensional surface tomography scans were used to measure head circumference, cranial width, cranial length, cranial index (CI), and cranial vault asymmetry.Seventeen patients underwent orthotic helmeting therapy before spring mediated cranial vault expansion. Patients spent a median of 48 days (interquartile range [IQR] 32, 57) in preoperative orthotic helmeting therapy. There were increases in both cranial width and length post-helmeting (median: 107.5 mm [IQR 104.8, 110.4] versus 115.6 mm [IQR 114.5, 119.3]; P < 0.001) (median: 152.8 mm [IQR 149.2, 154.9] versus 156.8 mm [IQR 155.0, 161.5]; P < 0.001), respectively. There was a greater increase in cranial width (P = 0.015). Consequently, patients' CI improved after preoperative helmeting (median: 0.702 [IQR 0.693, 0.717] versus 0.739 [0.711, 0.752]; P < 0.001). There was no evidence of growth restriction from helmeting (pre-helmeting Head circumference [HC]: median 96.8 percentile [IQR 90.6, 99.9] versus post-helmeting HC: 98.7 percentile [IQR 94.7, 99.8]; P = 0.109).Preoperative helmeting in patients with non-syndromic isolated sagittal craniosynostosis can be used to improve CI before surgical correction. Significant benefits can be achieved in shorter preoperative helmeting durations than previously reported with no evidence of cranial growth restriction, which supports its feasibility and utility in children undergoing spring mediated cranial vault expansion.

The potential for parasite spill-back from commercial bumblebee colonies: a neglected threat to wild bees?

Commercially-reared bumblebee colonies provide pollination services to numerous crop species globally. These colonies may harbour parasites which can spill-over to wild bee species. However, the potential for parasites to spread from wild to commercial bumblebees, which could then lead to parasite spill-back, is poorly understood. To investigate this, parasite-free commercial Bombus terrestris audax colonies, which are used commercially for strawberry pollination, were placed into seasonal strawberry crops for either 6- or 8-week blocks across two key time periods, early spring and early summer. Bumblebees were removed from colonies weekly and screened for the presence of parasites. In the early spring placement, only one parasite, the highly virulent neogregarine Apicystis bombi, was detected at a low prevalence (0.46% across all bees screened). In contrast, all colonies placed in the crop in the early summer became infected. A trypanosome, Crithidia bombi, and A. bombi were the most prevalent parasites across all samples, reaching peak prevalence in screened bees of 39.39% and 18.18% respectively at the end of the experimental period. The prevalence of A. bombi was greater than most UK records from wild bumblebees, suggesting that commercial colonies could enhance levels of A. bombi infection in wild bees through spill-back. Studies on larger geographical scales with different commercial colony densities are required to fully assess spill-back risk. However, seasonal management, to minimise spill-back opportunities, and treatment of commercial colonies to prevent infection, could be implemented to manage the potential risks of parasite spill-back to wild bees.Implications for insect conservation Our results show that commercial bumblebee populations do pick up infections, most likely from wild bees, and that these infections can reach prevalences where they may pose a threat to wild bees via parasite spill-back. More research is required to clarify the extent of this potential threat.

Outcomes of Endoscopic Versus Open Spring Assisted Surgery for Sagittal Craniosynostosis.

Spring-assisted surgery (SAS) has been shown to be an effective technique for correction of isolated sagittal craniosynostosis in patients less than 6 months of age. At their institution, the authors adopted a minimally invasive technique in 2010, using a shorter incision and an endoscope. A retrospective chart review of 101 patients with isolated, nonsyndromic, sagittal craniosynostosis, who underwent SAS, was performed in order to compare perioperative and clinical outcomes of the open (n = 51) and minimally-invasive (n = 50) approaches. Surgeries were performed by 2 neurosurgeons and 3 plastic surgeons, between 2005 and 2018. The pre and postoperative cephalic indices were not significantly different in both groups. Minimally-invasive spring placement required a longer operative time than the open approach, with the mean minimally-invasive operative time at 65 minutes, compared to 53 minutes (P < 0.0001). Spring removal operative time was not significantly different, with the minimally-invasive operative time at 31 minutes versus 29 minutes (P = 0.48). There were no significant differences in major or minor complications when comparing the open and minimally-invasive approaches. In conclusion, both the open and the minimally-invasive SAS techniques are effective for early correction of isolated sagittal craniosynostosis, although the minimally-invasive approach requires a longer operative time for spring placement.

Intestinal adaptation following spring insertion into a roux limb in mice

Background/PurposeIntraluminal springs have recently been shown to lengthen segments of intestine in a process known as distraction enterogenesis. We hypothesized that biocompatible springs could be used to lengthen defunctionalized murine small intestine and would lead to identifiable intestinal adaptations at the molecular level. MethodsAge and weight matched C57BL/6 mice underwent surgical insertion of nitinol spring-loaded capsules into a Roux limb of jejunum. Segment lengths were measured at initial spring placement and at euthanasia after 14 and 21 days. Histology and gene expression of the Roux limb were evaluated at scarification and compared to untreated control segments. ResultsIntestinal segments loaded with compressed springs lengthened an average of 240%, which was significantly longer than control segments loaded with either empty capsules or uncompressed springs. Muscularis thickening was greater in spring-treated mice compared to controls without springs. Crypt depth and Lgr5+ expression was greater in mice that received compressed spring treatments when compared to control groups. ConclusionsInsertion of a compressed nitinol spring into a Roux limb results in significant intestinal lengthening, smooth muscle thickening, and Lgr5+ expression in a mouse model. The ability to increase small bowel length in a defunctionalized murine model may be used to understand the mechanism of distraction enterogenesis.

Long-Term Outcomes of Spring-Assisted Surgery for Sagittal Craniosynostosis.

Spring-assisted surgery is an accepted alternative to cranial vault remodeling for treatment of sagittal craniosynostosis. The long-term safety and efficacy profiles of spring-assisted surgery have not been established. This study is a retrospective examination of all patients treated with spring-assisted surgery (n = 175) or cranial vault remodeling (n = 50) for sagittal craniosynostosis at the authors' institution from 2003 to 2017. Data collected included demographic and operative parameters, preoperative and postoperative Cephalic Indices, and complications. Whitaker grades were assigned blindly by a craniofacial surgeon not involved in patients' care. The mean age at surgery was significantly lower for the spring-assisted surgery group compared with the cranial vault remodeling group (4.6 months versus 22.2 months; p < 0.001). Even when combining spring placement with spring removal operations, total surgical time (71.1 minutes versus 173.5 minutes), blood loss (25.0 ml versus 111.2 ml), and hospital stays (41.5 hours versus 90.0 hours) were significantly lower for the spring-assisted surgery cohort versus the cranial vault remodeling group (p < 0.001 for all). There were no differences in infection, reoperation rate, or headaches between the groups. The percentage improvement in Cephalic Index was not significantly different at 1 (p = 0.13), 2 (p = 0.99), and 6 (p = 0.86) years postoperatively. At 12 years postoperatively, the spring-assisted surgery group had persistently improved Cephalic Index (75.7 preoperatively versus 70.7 preoperatively). Those undergoing spring-assisted surgery had significantly better Whitaker scores, indicating less need for revision surgery, compared with the cranial vault remodeling group (p = 0.006). Compared with the authors' cranial vault remodeling technique, spring-assisted surgery requires less operating room time and is associated with less blood loss, but it has equivalent long-term Cephalic Indices and subjectively better shape outcomes. Therapeutic, III.

Hope Springs Eternal: Insights Into the Durability of Springs to Provide Long-Term Correction of the Scaphocephalic Head Shape.

Spring-mediated cranial vault expansion (SMC) has become a primary treatment modality at our institution to correct scaphocephalic head shape in the setting of isolated sagittal craniosynostosis (CS). Spring-mediated cranioplasty is associated with minimal procedural morbidity and reliable clinical efficacy, although long-term outcomes are not well elucidated. Herein we describe our institutional experience and lessons learned with SMC. We hypothesize that SMC performed in young infants offers durable scaphocephalic correction as measured by cephalic index (CI) at the 1, 3, and 5-year postoperative timepoints.Patients with isolated sagittal CS who underwent SMC at our institution during an 8-year period were retrospectively studied. The primary outcome measure was long-term head shape determined by CI at the 1, 3, and 5-year postoperative timepoints. Secondary outcomes included patient and spring factors associated with change in CI, including age and spring force. All statistical tests were 2-tailed with P < 0.05 denoting significance.In total, 88 patients underwent SMC at a median age of 3.3 months with a median preoperative CI 69 (interquartile range: [66, 71]). The postoperative CI increased to 73 [71, 76] at postoperative day 1. At 1 month, the CI increased by 8.6 to 77 (P < 0.0001) and appeared to reach a plateau at 3 months (76, [74, 78]) without further improvement (P < 0.10). At 5 years, CI remained stable without relapse (76, [75, 81], demonstrating an 8.9 increase from preoperative CI. Age at time of spring placement and change in CI were inversely related (P < 0.005). Total spring force directly correlated with increased change in postoperative CI at the 6-month postoperative timepoint (P < 0.02).In summary, SMC offers durable correction of scaphocephaly as measured by CI for patients with isolated sagittal CS at the 5-year postoperative timepoint. The cranial expansion observed 1-month post-spring implantation may serve as a proxy for long-term CI.

S7A-07 SESSION 7A: SAGITTAL SYNOSTOSIS AN UPDATE ON THE OUTCOMES OF SPRING-ASSISTED SURGERY FOR SAGITTAL CRANIOSYNOSTOSIS

Introduction: Spring-assisted surgery (SAS) is an efficacious means for correcting scaphocephaly due to sagittal craniosynostosis. Early intervention for sagittal craniosynostosis using spring-assisted surgery (SAS) is an alternative to calvarial vault remodeling. SAS is performed for patients younger than 6 months of age, and it requires two operations: one for spring placement and a second for spring removal. The long-term safety and efficacy of this technique continue to be reviewed as this technique gains greater acceptance. The nuances of optimizing outcome will also be reviewed. Methods: We performed a retrospective examination of the electronic medical record for all patients treated with SAS for isolated sagittal synostosis at our institution with at least 1 year of follow up (N=179). Cephalic index (CI) was calculated from CT scans, laser Doppler scans, and 3DMD stereophotogammetry. Perioperative data was collected on OR time, blood loss, transfusion rates, and hospital stay, and complications were also collected. Results: There were 179 patients who underwent SAS from 2001 to February 2018. The mean gestationally-corrected age at spring placement and spring removal were 4.4 months and 9.4 months, respectively. Operative time for spring placement was 44.9 minutes, and for spring removal was 26.8 minutes. The mean hospital length of stay for spring placement was 35 hours, and for spring removal was 7.6 hours. One patient required a blood transfusion for the initial placement operation and none for the removal procedure. Mean CI prior to SAS was 70. This improved to 75 after spring placement (p<0.001) and was 74.0 at 1 year after spring placement. This has been maintained with a mean of 75.7 at 12 years post op. Major complications, defined as those requiring a return to the operating room to address spring malposition, exposure, or infection, occurred at a rate of 6.1% with the majority of these occurring during the initial learning curve of the procedure. Conclusion: SAS for isolated craniosynostosis continues to have consistent correction of CI that is maintained over time and a favorable complication profile, as shown by this updated analysis. Outcomes are optimized by earlier placement, accurate positioning in relation to the coronal and lambdoid sutures, and accurate force selection based on type of scaphocephaly and patient profile. The spring removal procedure can be done safely as an outpatient. Finally, after the initial learning curve, the endoscopic approach mirrors the outcomes of the open spring placement.

S2-11 SESSION 2: POSTERIOR VAULT DISTRACTION ENDOSCOPIC SPRING-MEDIATED DISTRACTION FOR UNILAMBDOID CRANIOSYNOSTOSIS

Introduction: Implantable springs were first described in craniofacial surgery in 1997. The springs were designed to remodel the calvarium following release of a prematurely fused suture in craniosynostosis. Open surgical repair of lambdoid synostosis with spring-mediated distraction has subsequently been described. In other parts of the calvarium, endoscopic placement of springs has been successful. To our knowledge, no cases have been reported using an endoscopic approach with springs for unilambdoid craniosynostosis. We aim to describe our technique and demonstrate outcomes in the successful use of endoscopically placed distraction springs for unilambdoid synostosis. Methods: We performed a retrospective analysis of our series of endoscopic unilambdoid synostosis repairs. Cases were analyzed based on patient characteristics, operative details, and outcomes. The operation commences by approaching the lambdoid suture endoscopically. A suturectomy is performed and burr holes are placed on either side of the suture, perpendicular to the suturectomy. The springs are bent preoperatively to a predetermined force. Two springs are placed across the suturectomy defect and the skin is closed. The patient is monitored for improvement in head shape and cranial x-rays are performed to measure the degree of distraction. Results: Seven patients underwent endoscopic spring-mediated distraction for unilambdoid craniosynostosis. Six patients had the springs removed and one is scheduled for spring removal at a future date. The average age at the time of operation was 9.4 months (range: 3.9 - 11.0). The average force of each spring placed was 7.1 Newtons (range: 5.5 – 8.0). The average length of hospital stay after spring placement was 1.9 days (range: 1–2). The average duration between spring placement and removal was 5.6 months (range: 4.5 - 6.6). Four patients had x-rays immediately after placement and prior to removal. Each spring expanded an average distance of 15.3 mm (range: 3 - 25.3). There were no surgical complications. One patient had both preoperative and postoperative CT scans available. The angle of the cranial base, calculated by comparing foramen magnum to cribriform plate angles, improved 6.7 degrees (13.7 preoperatively to 7 postoperatively). Topographical scans were available for 3 patients. These all demonstrated improvements in head shape. Conclusion: Endoscopic spring-mediated distraction is a safe and effective treatment of unilambdoid craniosynostosis. The series represents the largest experience with this technique. Our approach could be considered in all cases of unilambdoid synostosis given the efficacious improvement in vault remodeling, low patient morbidity, short operating time, and minimal inpatient stay.

Spring-Mediated Cranioplasty in Sagittal Synostosis: Does Age at Placement Affect Expansion?

The aim of this study is to evaluate the effect of timing of surgery and spring characteristics on correction of scaphocephalic deformity in patients undergoing spring-mediated cranioplasty (SMC) for sagittal craniosynostosis. The authors conducted a review of patients with sagittal craniosynostosis who underwent SMC at a tertiary referral center between July 2011 and March 2017, with a primary outcome measure of head shape, both preoperatively and postoperatively, determined by cephalic index (CI). Patient demographics and operative details including timing of surgery and spring characteristics were collected. Differences in CI preoperation and postoperation were compared using Wilcoxon signed-rank test. Ordinary least-squares linear regression was used to assess the impact of timing, number of springs, maximum single spring force, and total spring force on postoperative change in CI. Thirty-six subjects (12 males and 24 females) were included in the study. Mean age at spring placement was 3.9 months (range: 1.9-9.2) with a mean follow-up of 1.4 years (range: 0.3-5.2). The mean number of springs used was 3 (range: 2-4). The mean maximum single spring force was 9.9 Newtons (N) (range: 6.9-13.0) and the mean total spring force was 24.6 N (range: 12.7-37.0). Mean CI increased from 70 ± 0.9 preoperatively to 77 ± 1.0 postoperatively (P < 0.001). Age at spring placement was significantly associated with change in CI: for every month increase in age, the change in CI decreased by 1.3 (P = 0.03). The number of springs used, greatest single spring force, and total spring force did not correlate with changes in CI (P = 0.85, P = 0.42, and P = 0.84, respectively). In SMC, earlier age at time of surgery appears to correlate with greater improvement in CI, at least in the short-term. While spring characteristics did not appear to affect head shape, it is possible that the authors were underpowered to detect a difference, and spring-related variables likely deserve additional study.

Application of Palpebral Spring in Asian Patients With Paralytic Lagophthalmos.

Literature on palpebral springs is scarce, and even more so for the Asian population. In this study, the authors evaluated their experience with palpebral spring placement for paralytic lagophthalmos in an Asian population. The authors report the unique challenges encountered due to the distinctive features in Asian eyelids and how they overcome them. To the best of our knowledge, this is the first report on the application of palpebral springs in Asians. All patients treated for paralytic lagophthalmos in the Department of Surgery, Queen Mary Hospital, from November 2013 to December 2015, were included in this study. The authors retrieved and analyzed the demographic data, preoperative assessment details, and treatment outcomes. A total of 17 patients were recruited. The median interval between facial palsy occurrence and surgery was 66 months. Preoperatively, vertical palpebral fissure was 12.3 ± 1.7 mm with margin reflex distance 1 of 3.7 ± 0.3 mm and margin reflex distance 2 of 8.6 ± 1.6 mm. Lagophthalmos before surgery was 9.6 ± 2.3 mm. After the palpebral spring surgeries, vertical palpebral fissure was reduced to 9.1 ± 1.4 mm. margin reflex distance 1 is slightly reduced (3.3 ± 0.8 mm) and margin reflex distance 2 improved to 5.8 ± 1.0 mm. Lagophthalmos reduced significantly to 0.8 ± 1.3 mm. Seven patients required revision procedures. Palpebral spring is a safe and effective treatment for Asian patients with paralytic lagophthalmos. However, surgeons should be aware of the unique challenges associated with the anatomy of Asian eyelids. Special adaptation of the procedure is required to optimize the outcome.

Is there a geomorphic expression of interbasin groundwater flow in watersheds? Interactions between interbasin groundwater flow, springs, streams, and geomorphology

AbstractInterbasin groundwater flow (IGF) can play a significant role in the generation and geochemical evolution of streamflow. However, it is exceedingly difficult to identify IGF and to determine the location and quantity of water that is exchanged between watersheds. How does IGF affect landscape/watershed geomorphic evolution? Can geomorphic metrics be used to identify the presence of IGF? We examine these questions in two adjacent sedimentary watersheds in northern New Mexico using a combination of geomorphic/landscape metrics, springflow residence times, and spatial geochemical patterns. IGF is expressed geomorphically in the landscape placement of springs and flow direction and shape of stream channels. Springs emerge preferentially on one side of stream valleys where landscape incision has intercepted IGF flow paths. Stream channels grow toward the IGF source and show little bifurcation. In addition, radiocarbon residence times of springs decrease and the geochemical composition of springs changes as the connection to IGF is lost.

Development and testing of an absorbable spring for cranial expansion in rabbits

ObjectiveUse of metal springs for treatment of craniosynostosis is gaining ground in the surgical armamentarium, as these springs simplify operative technique, help to avoid extended approaches, and thus minimize morbidity. Nevertheless, these devices have to be removed eventually. The purpose of this study was to perform cranial expansion with a fully integrated, biodegradable polymer spring in an animal model and to assess the efficacy of and histological reaction to this device. Material and methodsThis was an experimental, unblinded, prospective study. Twelve female New Zealand rabbits (Oryctolagus cuniculus) aged 6 weeks were randomly allocated to two groups. Control animals underwent linear craniectomy alone. Intervention animals underwent craniectomy with placement of a poly(lactic-co-glycolic acid)/polyisoprene (PLGA/PI) copolymer blend spring for cranial expansion transverse to the ostectomy. Expansion was measured radiographically over 12 weeks with amalgam markers. At the end of the experiment period, histological analysis was performed to quantify inflammatory reaction. ResultsThe copolymer blend springs had a mean strength of 4.2N. In the intervention group, cranial expansion at the frontal markers was 9.6–11.67 mm (significantly greater than in controls). Histological analysis showed minor inflammatory reactions. ConclusionIn this animal model, cranial expansion by linear craniectomy followed by bioabsorbable spring placement was feasible and well tolerated by adjacent tissues.

Repeated Mechanical Lengthening of Intestinal Segments in a Novel Model

Purpose: Currently, animal models used for mechanical intestinal lengthening utilize a single lengthening procedure prior to analysis or restoration back into continuity. Here we developed a novel surgical model to examine the feasibility of repeated lengthening of intestinal segments. Methods: A Roux-en-Y jejunojejunostomy with a blind Roux limb was created in rats. An encapsulated polycaprolactone spring was placed into a 1cm segment of the Roux limb. After 4weeks, a second encapsulated PCL spring was inserted into a 1cm portion of the lengthened segment. After another 4weeks, the repeatedly lengthened segments were retrieved for histological analyses. Results: Jejunal segments of the Roux limb were successfully lengthened from 1.0cm to 2.6±0.7cm. Four weeks after the second PCL spring placement, 1.0cm of the previously lengthened segment increased to 2.7±0.8cm. Stronger mechanical force was required to achieve subsequent re-lengthening. Lengthened and re-lengthened segments had increased smooth muscle thickness and crypt depth when compared to normal jejunal mucosa. Conclusion: Using the Roux-en-Y model, previously lengthened segments of intestine can be successfully re-lengthened. Intestinal segments may be subjected to multiple lengthening procedures to achieve clinically significant length for the treatment of short bowel syndrome.