Tunnel Volume Research Articles

The influence of reduced cross-section on pressure transients from high-speed trains intersecting in a tunnel

Alleviation of the pressure transients caused by high-speed trains intersecting in a tunnel with partially reduced cross-section is investigated by numerical simulation. The RNG k-ε turbulence model and hybrid grid are adopted for the numerical simulation, which is validated by the moving model test. Two factors, the length of reduced section (L) and the train marshalling number, are considered to analyse the alleviation effect. The results show that, for reduction of the pressure transients induced by the intersection of three-car marshalling trains, the location of the change in cross-section is supposed to be near the location of the maximum value of the initial expansion wave (L → 240 ​m). In addition, for four-car marshalling trains intersecting in a tunnel of L ​= ​240 ​m, the excavation volume of the tunnel (tunnel volume) decreases by 14.4%, and the average pressure amplitude on the train surface decreases by 7.9%. Especially the pressure amplitude at the measurement point in the streamlined area of the tail car decreased by 28.6%. The reduced section tunnel has a good effect on decreasing the pressure transients around train body and the tunnel excavation volume (construction cost), which helps the tunnel design process.

Cancellous allogenic and autologous bone grafting ensure comparable tunnel filling results in two-staged revision ACL surgery

ObjectivesPatients with recurrent instability after anterior cruciate ligament (ACL) reconstruction often present with enlarged or misplaced tunnels and bone grafting is required prior to the actual revision reconstruction. Autologous bone grafting features limited quantity and donor site morbidity. These problems may be eliminated utilizing cancellous bone allografts, but their efficiency and reliability have not been investigated systematically. The aim of the present study was to compare tunnel filling rates attained by utilizing either allogenic or autologous cancellous bone grafts.Materials and methodsA total of 103 consecutive patients were enrolled retrospectively. All patients suffered from recurrent instability and underwent either allogenic or autologous cancellous bone grafting. Computed tomography (CT) was carried out before and after the bone grafting procedure. Based on preoperative CT scans, positioning and maximum diameter of the femoral and tibial tunnels were determined. Tunnel filling rates were calculated as a ratio of pre- and postoperative tunnel volumes. Primary outcome was the tibial tunnel filling rate. Femoral filling rates and density of the grafted bone were assessed secondarily.ResultsPreoperative CT scans revealed no significant differences between the two groups regarding distribution of misplacement and widening of the femoral or tibial tunnel. Postoperative CT scans were conducted after an interval of 5.2 months. Tunnel filling rates of 74.5% (± 14.3) femoral and 85.3% (± 10.3) tibial were achieved in the allogenic compared to 74.3% (± 15.9) femoral and 84.9% (± 9.4) tibial in the autologous group. With p values of 0.85 at the femur and 0.83 at the tibia, there were no significant differences between the groups. The density of the grafted bone revealed significantly higher values in the allogenic group.ConclusionsUtilizing cancellous bone allografts in two-staged revision ACL surgery provides for sufficient and reproducible filling of enlarged or misplaced tunnels. The filling rates are comparable to those achieved with autologous bone grafting. Advantages of allografts are the unrestricted quantity and the absence of any harvesting procedure.

The Effect of Hamatum Curvature Angle on Carpal Tunnel Volumetry: A Mathematical Simulation Model.

In carpal tunnel volume measurements, the angle of the hamatum curvature is not considered a variable, and its effect on carpal tunnel volume has not been investigated. We hypothesize that a change in the anatomical angle of the hamatum curvature changes the carpal tunnel volume. To prove our hypothesis, we used a mathematical simulation model considering the carpal tunnel as a truncated cone. We reviewed the wrist CT scans of 91 adults (>18 years of age), including 51 men and 40 women. We measured the angle of the hamatum curvature in the CT scans. We measured cross-sectional areas at the outlet of the carpal tunnel at the level of the trapezium and hook of hamate (r1) and at the inlet at the level of the scaphoid and pisiform (r2) and the length (h) of the carpal tunnel. We attempted to calculate the effect of 2 degree by 2-degree changes in the angle of the hamatum curvature between the angles of 98° and 140° on the carpal tunnel volume. The mean angle of the hook of hamatum of the subjects was 122.55° ± 8.20° (range, 97.20° − 139.31°). No suitable cutoff point was found for the angle values. There was no difference between the gender groups according to the angle value. The data clearly show that there is a high correlation between carpal tunnel volume and the angle of hamatum curvature. The results of our study emphasize the importance of taking into account the anatomical features of the hamatum bone, especially the angle of curvature, which may play a predisposing role in idiopathic carpal tunnel syndrome.

Experimental study on surface settlements induced by sequential excavation of two parallel tunnels in drained granular soil

In this paper, twin tunnelling-induced surface settlements in drained granular soils were studied using 1 g physical models. A mechanical device was developed to achieve the simulation of a sequential twin-tunnelling process. The centre to centre spacing S between the two tunnels and the magnitude of the tunnel volume loss Vt were the two main variables considered in the experimental study. The relative difference between the settlements observed in the two tunnel events was presented in detail in terms of parameters including the maximum surface settlement Smax, trough width i, and soil volume loss Vs, whereby the twin-tunnel interaction and its effect on the surface settlements due to the second tunnel in drained soils were made clear.

Validity of computed tomographic measurements and morphological comparison of cubital tunnel in idiopathic cubital tunnel syndrome

BackgroundUlnar neuropathy is a common reason for referral to hand surgeons, and 10 to 30% of cubital tunnel syndrome (CuTS) is idiopathic. We hypothesized that the cause of idiopathic CuTS is in the bony structure.MethodsWe analyzed 79 elbows (39 idiopathic CuTS and 40 without CuTS symptom) using computed tomography and Materialize Mimics software to compare the differences between the two groups. We proposed a new bony cubital tunnel with a new boundary that could play a role in ulnar nerve compression symptom.ResultsThe mean cubital tunnel volume was 1245.6 mm3 in all patients, 1180.6 mm3 in CuTS patients, and 1282.3 mm3 in the control group. A significant difference (p = 0.015) between two groups was found. Bony cubital tunnel cross-sectional area, cubital tunnel depth, and cubital tunnel angle also showed significant differences.ConclusionThe shape of the bony cubital tunnel is an important cause of CuTS, and the normal variation of the volume and cross-sectional area of the cubital tunnel and cubital tunnel angle could influence the occurrence of idiopathic CuTS.

Conformational ensembles of non-peptide ω-conotoxin mimetics and Ca+2 ion binding to human voltage-gated N-type calcium channel Cav2.2

Chronic neuropathic pain is the most complex and challenging clinical problem of a population that sets a major physical and economic burden at the global level. Ca2+-permeable channels functionally orchestrate the processing of pain signals. Among them, N-type voltage-gated calcium channels (VGCC) hold prominent contribution in the pain signal transduction and serve as prime targets for synaptic transmission block and attenuation of neuropathic pain. Here, we present detailed in silico analysis to comprehend the underlying conformational changes upon Ca2+ ion passage through Cav2.2 to differentially correlate subtle transitions induced via binding of a conopeptide-mimetic alkylphenyl ether-based analogue MVIIA. Interestingly, pronounced conformational changes were witnessed at the proximal carboxyl-terminus of Cav2.2 that attained an upright orientation upon Ca+2 ion permeability. Moreover, remarkable changes were observed in the architecture of channel tunnel. These findings illustrate that inhibitor binding to Cav2.2 may induce more narrowing in the pore size as compared to Ca2+ binding through modulating the hydrophilicity pattern at the selectivity region. A significant reduction in the tunnel volume at the selectivity filter and its enhancement at the activation gate of Ca+2-bound Cav2.2 suggests that ion binding modulates the outward splaying of pore-lining S6 helices to open the voltage gate. Overall, current study delineates dynamic conformational ensembles in terms of Ca+2 ion and MVIIA-associated structural implications in the Cav2.2 that may help in better therapeutic intervention to chronic and neuropathic pain management.

Influence of Tunneling in Cohesionless Soil for Different Tunnel Geometry and Volume Loss under Greenfield Condition

This paper presents the numerical analysis of settlement to profile the vulnerable zone or influence zone due to tunneling activities in cohesionless deposits for free field or Greenfield conditions. The analysis considers the factors like saturated density (γsat), unsaturated density (γunsat), angle of shearing resistance (φ), deformation modulus (ES), volume loss (VL), and the support pressure of the shield head at the tunnel face. The obtained results using a finite element program (FEM) PLAXIS 3D are compared with measured and predicted surface settlement using field measuring instruments, and analytical and empirical solution show a reasonable agreement and are found to be conservative. From literature, for Greenfield condition the ground settlement equal to 10 mm is taken as the minimum value to map the influencing zone considering the fact that the structure which lies beyond this zone would undergo negligible settlement. Settlement trough and 10 mm settlement contour characteristics are presented for different tunnel sizes placed at the same depth and the same tunnel size placed at different depths, respectively. Various influencing zones are arrived for the sandy grounds of different denseness based on the parametrical studies involving parameters such as tunnel size “D,” tunnel axis depth “z,” and volume loss “VL.”

Bioresorbable Stent in Anterior Cruciate Ligament Reconstruction.

The exact causes of failure of anterior cruciate ligament (ACL) reconstruction are still unknown. A key to successful ACL reconstruction is the prevention of bone tunnel enlargement (BTE). In this study, a new strategy to improve the outcome of ACL reconstruction was analyzed using a bioresorbable polylactide (PLA) stent as a catalyst for the healing process. The study included 24 sheep with 12 months of age. The animals were randomized to the PLA group (n = 16) and control group (n = 8), subjected to the ACL reconstruction with and without the implantation of the PLA tube, respectively. The sheep were sacrificed 6 or 12 weeks post-procedure, and their knee joints were evaluated by X-ray microcomputed tomography with a 50 μm resolution. While the analysis of tibial and femoral tunnel diameters and volumes demonstrated the presence of BTE in both groups, the enlargement was less evident in the PLA group. Also, the microstructural parameters of the bone adjacent to the tunnels tended to be better in the PLA group. This suggested that the implantation of a bioresorbable PLA tube might facilitate osteointegration of the tendon graft after the ACL reconstruction. The beneficial effects of the stent were likely associated with osteogenic and osteoconductive properties of polylactide.

PO 18239 - Malerba Z-type osteotomy for the treatment of adult acquired flatfoot deformity

Introduction: Adult acquired flat foot deformity (AAFD) is a condition characterized by tendon and ligament failure that leads to progressive midfoot collapse and to hindfoot valgus. Calcaneal osteotomies are among the oldest and most conventional procedures for the treatment of angular limb deformities; they aim to reestablish the alignment and the line of action vector of the triceps surae muscle. Various disadvantages of classic osteotomies have been established in recent years, such as fixation loss, insufficient correction and reduced tarsal tunnel volume. Malerba Z-type osteotomy aims to resolve possible complications resulting from the usual incisions, to enhance the procedure and to allow multiplane corrections. Objective: To describe the functional and radiographic outcomes of Malerba Z-type osteotomy in patients with AAFD subjected to reconstructive surgery. Methods: Ten patients diagnosed with AAFD, with a mean age of 45 years (35-55), were operated on from January 2017 to January 2018. All patients underwent weight-bearing radiographs and alignment measurements and functional assessment using the pain visual analog scale (VAS) and the American Orthopedic Foot and Ankle Society (AOFAS) scale preoperatively and at the final evaluation at a mean of 12 months (6-18 months) after surgery. Results: The 10 patients showed positive progression after the surgery, reporting no major complications. Only one case of superficial dehiscence and one case of transient sural nerve neuropraxia (in different patients) were observed. On average, the AOFAS score increased by 50 points on average (25.7 to 76.6), and the VAS score decreased by 4 points (8.3 to 3.4). The mean calcaneal pitch increased from 5.5° to 15.2°. Nine patients transitioned from valgus malalignment (hindfoot angle greater than 10°) to the physiological (5 to 10° valgus) range. Conclusion: Ankle-foot realignment is an essential condition for surgical success in AAFD; it promotes a soft-tissue healing environment while maintaining an adequate muscle line of action. Malerba Z-type osteotomy was found to be a safe technique with high potential for deformity correction, leading to functional and radiographic improvement in patients who undergo this surgery.

The Effect of Calcaneal Displacement Osteotomies on Tarsal Tunnel Pressures

Category:Basic Sciences/BiologicsIntroduction/Purpose:Calcaneal displacement osteotomies are frequently utilized procedures to correct hindfoot varus and valgus deformities and are frequently used in conjunction with other procedures to restore normal alignment of the foot.Complications associated with this procedure include overcorrection, undercorrection, iatrogenic fracture, wound dehiscence, and infection. Additionally, neurologic deficit associated with lateralizing calcaneal osteotomy has been documented in the literature. Changes in ankle alignment have been shown to significantly alter tarsal tunnel pressure and volume, and a MRI study by Bruce et. al showed that lateral osteotomy fragment displacement results in significant reduction of tarsal tunnel volume. We hypothesized that a lateral displacement calcaneal osteotomy would result in an increase in tarsal tunnel pressure compared baseline tarsal tunnel pressures or those with a medial displacement calcaneal osteotomy.Methods:We performed cadaveric dissections on five foot and ankle cadavers. The laciniate ligament covering the tarsal tunnel was visualized at 2 cm proximal to the medial malleolus and a nick incision was made to insert the ICP monitoring probe; the tunnel was left intact distally. A 45 degrees lateral incision was made in line with the osteotomy site and a calcaneal osteotomy was performed in line with the incision approximately 1 cm anterior to the attachment of the achilles tendon. A Codman ICP monitoring probe was then used to measure baseline tarsal tunnel pressure measurements prior to calcaneal displacement. The osteotomy was then displaced medially and laterally and fixed in place in place with a K-wire (Figure 1). Tarsal tunnel pressures were measured at 5 mm and 8 mm displacement in both directions.Results:Average tarsal tunnel pressures at baseline were 2.8 mmHg (range, 1-5 mmHg). Average tarsal tunnel pressures with 5 mm and 8 mm of medial calcaneal displacement were 1.0 mmHg (range, 0-4 mmHg) and 0.8 mmHg (range, 0-3 mmHg), and with lateral calcaneal displacement were 7.4 mmHg (range, 3-13 mmHg) and 14.4 mmHg (range, 10-22 mmHg). There was no significant difference in tarsal tunnel pressures with either 5 mm (p=.067) or 8 mm (P=.067) of medial calcaneal displacement compared to baseline. There was, however, a significant increase in tarsal tunnel pressures with both 5 mm (p=.039) and 8 mm (p=.001) of lateral calcaneal displacement compared to tarsal tunnel pressures at baseline and with 5 mm (p=.002) and 8 mm (p=.001) of medial calcaneal displacement.Conclusion:Tibial nerve palsy following lateral displacement calcaneal osteotomy has recently been shown to have an incidence as high as 34%. Osteotomies decreasing volume in the tarsal tunnel could cause iatrogenic compression of the tibial nerve. Based on the results of our study, displacing the calcaneus laterally increases the tarsal tunnel pressures on average five times above baseline tarsal tunnel pressures. Medial displacement, however, does not appear to have any significant effect on pressures within the tunnel. The findings in this study provide further clinical evidence in support of prophylactic tarsal tunnel release prior to performing a lateralizing calcaneal osteotomy.

The Effect of Medial Displacement Calcaneal Osteotomy on Tarsal Tunnel Volume

Category:HindfootIntroduction/Purpose:Tarsal tunnel volume is affected by position of the foot and the alignment of the ankle. Although medial displacement calcaneal osteotomy (MDCO) significantly alters the alignment of the hindfoot, the change of tarsal tunnel volume after this procedure has not yet been well documented. Therefore, authors investigated the volumetric change of tarsal tunnel after MDCO using Computed Tomography (CT) scan.Methods:This retrospective study involved 101 feet of 91 patients who underwent a MDCO at our institution from March 2016 to December 2018. We compared the tarsal tunnel volume from the preoperative and postoperative CT scan images under following protocols. On a sagittal scout image, the oblique axial plane was drawn parallel to the long axis of the calcaneus using talonavicular joint as a landmark. Serial oblique axial images were displayed using PACS (PathSpeed, GE Healthcare, Chicago, IL, USA) with both the soft tissue and the bone window settings. The volume of tarsal tunnel was evaluated from just distal to the tip of medial malleolus anterior colliculus to distance of 3 cm distal using 10 consecutive images by drawing the border of tarsal tunnel. The volume was calculated by adding 10 cross-sectional areas and then multiplying by 3 mm corresponding to slice thickness.Results:The mean preoperative and postoperative tarsal tunnel volume were 12229 mm3 (SD, 1842 mm3) and 12762 mm3 (SD, 1803 mm3), respectively. There was 4.6% (SD, 3.4%) of volume increase after MDCO (p <0.001). Results indicated high inter- and intraobserver reliability coefficients (r = 0.97, r = 0.98, respectively).Conclusion:MDCO increased the volume of tarsal tunnel. This finding might support clinicians performing MDCO as a conjunctive surgical option in treating patients with tarsal tunnel syndrome.

ACL reconstruction with adjustable-length loop cortical button fixation results in less tibial tunnel widening compared with interference screw fixation.

To compare tunnel widening and clinical outcome after anterior cruciate ligament reconstruction (ACLR) with interference screw fixation and all-inside reconstruction using button fixation. Tunnel widening was assessed using tunnel volume and diameter measurements on computed tomography (CT) scans after surgery and 6months and 2years later, and compared between the two groups. The clinical outcome was assessed after 2years with instrumented tibial anteroposterior translation measurements, hop testing and International Knee Documentation Committee (IKDC), Lysholm and Tegner activity scores. The study population at the final follow-up was 14 patients with screw fixation and 16 patients with button fixation. Tibial tunnels with screw fixation showed significantly larger increase in tunnel volume over time (P = 0.021) and larger tunnel diameters after 2years in comparison with button fixation (P < 0.001). There were no significant differences in femoral tunnel volume changes over time or in tunnel diameters after 2years. No significant differences were found in the clinical outcome scores. All-inside ACLR using button fixation was associated with less tibial tunnel widening and smaller tunnels after 2years in comparison with ACLR using screw fixation. The need for staged revision ACLRs may be greater with interference screws in comparison with button fixation at the tibial tunnel. The clinical outcomes in the two groups were comparable. II. RCT: Consort NCT01755819.

An Analytical Drain Current Model for the Cylindrical Channel Gate-All-Around Heterojunction Tunnel FETs

In this paper, we present analytical models which are valid in all regions of operation and can accurately predict the potential profile and the output, as well as the transfer characteristics of the gate-all-around heterojunction tunnel field-effect transistors. Our potential model takes into account the charge carriers in the channel, as well as the space charges in the depletion regions of the two reservoirs. Later, this potential model is utilized to calculate the band-to-band tunneling generation rates at any spatial coordinate in the tunneling volume. Next, these rates are integrated over tunneling volume to find the total tunneling current. This leads to an analytical model for the drain current. We validate our models against the data obtained via numerical simulations for several common heterojunction tunnel devices at various geometries and bias conditions.

Morphologic Analysis of the Carpal Tunnel and Median Nerve Following Open and Endoscopic Carpal Tunnel Release.

Background: Endoscopic carpal tunnel release (ECTR) has purported advantages over open release such as reduced intraoperative dissection and trauma and more rapid recovery. Endoscopic carpal tunnel release has been shown to have comparable outcomes to open release, but open release is considered easier and safer to perform. Previous studies have demonstrated an increase in carpal tunnel volume, regardless of the technique used. However, the mechanism by which this volumetric increase occurs has been debated. Our study will determine through magnetic resonance imaging (MRI) analysis the morphologic changes that occur in both open carpal tunnel release (OCTR) and ECTR, thereby clarifying any morphologic differences that occur as a result of the 2 operative techniques. We hypothesize that there will be no morphologic differences between the 2 techniques. Methods: This was a prospective study to compare the postoperative anatomy of both techniques with MRI. Nineteen patients with clinical and nerve conduction study-confirmed carpal tunnel syndrome underwent either open or endoscopic release. Magnetic resonance imaging was performed preoperatively and 6 months postoperatively in all patients to examine the volume of the carpal tunnel, transverse distance, anteroposterior (AP) distance, divergence of tendons, and Guyon's canal transverse and AP distance. Results: There was no significant difference in the postoperative morphology of the carpal tunnel and median nerve between OCTR and ECTR at 6-month follow-up on MRI. Conclusion: We conclude that there are no morphologic differences in OCTR and ECTR. It is an increase in the AP dimension that appears to be responsible for the increase in the volume of the carpal tunnel.

A Randomized Controlled Trial of PEEK Versus Titanium Interference Screws for Anterior Cruciate Ligament Reconstruction With 2-Year Follow-up

Background: Graft fixation with interference screws for anterior cruciate ligament (ACL) reconstruction is a highly successful technique. Polyether ether ketone (PEEK) is a novel thermoplastic polymer with high biocompatibility and mechanical properties that mimic native bone, and it can be imaged on computed tomography or magnetic resonance imaging (MRI) without signal flare. Purpose: To compare the clinical performance of ACL reconstruction with PEEK and titanium interference screws at 2 years and to evaluate a novel method of measuring tunnel volume. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: A total of 133 patients underwent arthroscopic ACL reconstruction with 4-strand hamstring autografts and were randomized to have titanium or PEEK interference screws for femoral and tibial tunnel fixation. At 2 years, subjective Lysholm and International Knee Documentation Committee scores were assessed and clinical examination performed. At 12 months, MRI was performed to assess graft incorporation and cyst formation, and a novel technique was employed to measure tunnel volumes. Results: There were no significant differences in graft rerupture rate, contralateral ACL rupture rate, subjective outcomes, or objective outcomes. In the titanium and PEEK groups, MRI demonstrated high overall rates of graft integration (96%-100% and 90%-93%, respectively) and ligamentization (89% and 84%) and low rates of synovitis (22% and 10%) and cyst formation (0%-18% and 13%-15%). There was a higher proportion of patients with incomplete graft integration within the femoral tunnel in the PEEK group as compared with the titanium group (10% vs 0%, P = .03); however, the authors suggest that metal artifact precluded proper assessment of the graft in the titanium group by MRI. Tunnel volumes also appeared to be equivalent in the 2 groups and were measured with a novel technique that was highly reproducible in the PEEK group secondary to the absence of flare. Conclusion: Two-year clinical analysis of PEEK interference screws for femoral and tibial fixation of ACL reconstructions showed equivalent clinical performance to titanium interference screws. Given the excellent mechanical characteristics, biological compatibility, and absence of metal artifact on MRI, PEEK has become our material of choice for interference screw fixation in ACL reconstruction.

Flexor Tenosynovectomy for Recurrent Carpal Tunnel Syndrome: A Retrospective Case Series of 108 Hands.

Background: The etiology of recurrent carpal tunnel syndrome (CTS) is unclear, and outcomes following secondary surgery in this demographic have been poorer than primary surgery. Fibrosis and hypertrophy have been identified in the flexor tenosynovium in these patients. The authors use flexor tenosynovectomy (FTS) for recurrent CTS after primary carpal tunnel release and present a review of these patients. Methods: A retrospective chart review was performed of 108 cases of FTS for recurrent CTS from 1995 to 2015 by 4 attending surgeons at one institution. Demographic information, symptoms, and outcomes were among the data recorded. A phone survey was conducted on available patients where the shortened version of the Disabilities of the Arm, Shoulder and Hand Questionnaire (QuickDASH) and satisfaction were assessed. Results: Average office follow-up was 12 months. Average age was 57.5 years. A total of 104 (96%) reported symptom improvement and 48 (44%) reported complete symptom resolution. Forty patients were available for long-term follow-up at an average 6.75 years postoperatively via phone interview. Average QuickDASH score was 31.2 in these patients. Thirty-six (90%) of 40 patients were initially satisfied at last office visit, and 31 (78%) of 40 were satisfied at average 6.9 years, a maintenance of satisfaction of 86%. Satisfied patients were older (58 years) than unsatisfied patients (51 years). Conclusion: Both long-term satisfaction and QuickDASH scores in our cohort are consistent with or better than published results from nerve-shielding procedures. The authors believe a decrease in both carpal tunnel volume and potential adhesions of fibrotic or inflammatory synovium contributes to the benefits of this procedure. This remains our procedure of choice for recurrent CTS.

Empirical and semi-analytical methods for evaluating tunnelling-induced ground movements in sands

Empirical formulas and closed-form solutions provide, in many cases, good predictions of tunnelling-induced ground movements which, when combined with their computational efficiency, make them valuable for tunnel-structure interaction analyses. For sandy soils, however, there is a shortage of available methods that can adequately describe the changes in soil deformation patterns that occur as a result of tunnel volume loss, soil relative density, and geometrical parameters. In this paper, two approaches are adopted to describe centrifuge test outcomes for tunnelling in dry silica sand of varying relative density. Firstly, empirical expressions for the prediction of settlement trough shape and magnitude are presented; additionally, a set of equations is given to describe the settlement troughs using modified Gaussian curves. Next, semi-analytical expressions (modifying an elastic analytical solution for incompressible soil and ovalized tunnel) are developed to predict both vertical and horizontal movements within the ground. Results from both methods can capture the main effects that cover-to-diameter ratio, relative density, and volume loss have on surface and subsurface ground movement profiles. The proposed expressions can be used for the calibration/verification of tunnel-structure interaction analysis methods by using outputs from comparable centrifuge tests; once verified, these methods may be more widely applied to other scenarios and used within design or risk-assessment exercises.

Mechanized tunneling induced ground movement and its dependency on the tunnel volume loss and soil properties

SummaryThis study investigates the ground movements due to mechanized tunnel excavation by applying two‐dimensional finite element analyses. To assess the contribution of the compressibility and plasticity of the soil on the ground movements, different constitutive models are employed to describe the soil behavior. The influence of volume loss around the tunnel on the surface volume loss is investigated, and a quadratic correlation between them is proposed. Consequently, the empirical Gaussian distribution curve, which is generally used to determine the tunneling induced settlement trough, is improved by applying the proposed quadratic correlation between surface volume loss and tunnel volume loss. Furthermore, the settlement trough width parameter has been derived by a linear function of tunnel volume loss as well. The proposed equations are validated via a case study of centrifuge tests from the literature. The results show that the proposed modification enhances the empirical solution by having better knowledge on the model parameters. Additionally, tunnel overburden and coefficient of lateral earth pressure at rest (K0) are taken into account to study their influence on the tunneling induced surface settlements. Finally, global sensitivity analysis is applied to evaluate the relative importance of corresponding model parameters in terms of their influence on the ground movements.

Outcomes of revision anterior cruciate ligament reconstruction secondary to reamer-irrigator-aspirator harvested bone grafting

IntroductionPatients with widened or misplaced tunnels may require bone grafting prior to revision anterior cruciate ligament (ACL) reconstruction. Utilising reamer-irrigator-aspirator (RIA) harvested bone from the femur showed promising filling rates. Nevertheless, the procedure has neither been validated in a larger population nor been assessed with regards to radiological and clinical outcome of the subsequently conducted revision ACL reconstruction. Therefore, the aim of this study was to evaluate tunnel filling rates, positioning of the revision tunnels and outcome parameters of such two-staged revision ACL reconstructions. Material and methodsA total of 15 consecutive patients were prospectively enrolled in this case series. CT scans were analysed before and after autologous RIA harvested bone grafting. Tunnel volumes and filling rates were calculated based on manual segmentation of axial CT scans. Revision ACL reconstruction was carried out after a mean interval of 6.2 months (±3.7) and positioning of the revision tunnels was assessed by plane radiographs. The mean follow-up was 19.8 months (±8.4) for objective evaluation and 37.1 months (±15.4) for patient reported outcomes. The clinical outcome was assessed by the quantification of the anterior tibial translation, the IKDC objective score, the Tegner activity scale and the Lysholm score. ResultsInitial CT scans revealed mean tunnel volumes of 3.8cm3 (±2.7) femoral and 6.1cm3 (±2.4) tibial. Filling rates of 76.1% (±12.4) femoral and 87.4% (±5.9) tibial were achieved. Postoperative radiographs revealed significantly improved tunnel positioning with anatomical placement in all but one case at the femur and in all cases at the tibia. At follow up, patients showed significantly improved anterior tibial translations with residual side-to-side differences of 1.7 mm (±0.8) and significantly improved IKDC objective scores. Furthermore, significantly higher values were achieved on the Tegner activity scale (5.3 ± 1.4 vs. 2.8 ± 0.5) and the Lysholm score (85.4 ± 7.9 vs. 62.5 ± 10.5) compared to the preoperative status. ConclusionAutologous RIA harvested bone grafting ensures sufficient bone stock consolidation allowing for anatomical tunnel placement of the subsequently conducted revision ACL reconstruction. The two-staged procedure reliably restores stability and provides satisfying subjective and objective outcomes. Thus, RIA harvested bone grafting is an eligible alternative to autologous iliac crest or allogenic bone grafting.

Tibial Nerve Palsy After Lateralizing Calcaneal Osteotomy.

Background: Lateralizing calcaneal osteotomy (LCO) is a common procedure used to correct hindfoot varus. Several complications have been described in the literature, but only a few articles describe tibial nerve palsy after this procedure. Our hypothesis was that tibial nerve palsy is a common complication after LCO. Methods: A retrospective study of patients undergoing LCO for hindfoot varus between 2007 and 2013 was performed. A total of 15 patients (18 feet) were included in the study. The patients were examined for tibial nerve deficit, and all the patients were examined with a computed tomography (CT) scan of both feet. Patients with a preexisting neurological disease were excluded. The primary outcome was tibial nerve palsy, and the secondary outcomes were reduction of the tarsal tunnel volume, the distance from subtalar joint to the osteotomy, and the lateral step at the osteotomy evaluated by CT scans. Results: Three of the 18 feet examined had tibial nerve palsy at a mean follow-up of 51 months. The mean reduction in tarsal tunnel volume when comparing the contralateral nonoperated foot to the foot operated with LCO was 2732 mm3 in the group without neurological deficit and 2152 mm3 in the group with neurological deficit (P = .60). Conclusion: 3 of 18 feet had tibial palsy as a complication to LCO. We were not able to show that a larger decrease in the tarsal tunnel volume, a more anterior calcaneal osteotomy, or a larger lateral shift of the osteotomy is associated with tibial nerve palsy. Levels of Evidence: Level IV: Retrospective case series.