Proper Tunnel Research Articles

The Incidence and Rate of Return to Competitive Sport Post ACL Reconstruction: Literature Review

ACL injuries are common in competitive team-ball athletes and are frequently career ending or compromising. The rate of return to competitive sport after ACL injury/management is debatable as well as the surgical and rehabilitation factors that should be considered while managing ACL injuries in order to optimize the return of the athlete to competition. The aim of this research was to investigate the incidence and the rate of return to competitive sport after ACL injury and to explore the various factors which need to be considered in ACL surgery and rehabilitation to support the process of successful return to competitive play. Research aims were met through extensive review of relevant ACL management literature. The rate of return to competitive sport averages around half of the athletes operated for ACL injury with a high rate of re-injuries especially within the first six months after surgery. Proper tunneling technique is an important surgical factor in relation to return to sport and surgery should be done as early as the knee is fully extended addressing all the concomitant injuries. Rehabilitation should be individualized, gradual and comprehensive, covering all the biopsychosocial aspects of the athlete. Decisions of when and how to return to sport are complex and should be team-based and preferably whole- model-based. The rate of return to competitive sport after ACL injury management is relatively low and not as commonly used to be thought of. Many factors are to be considered to optimize the return to competitive sport after ACL injury management.

A New Tissue Engineering Strategy to Promote Tendon-bone Healing: Regulation of Osteogenic and Chondrogenic Differentiation of Tendon-derived Stem Cells.

In the field of sports medicine, repair surgery for anterior cruciate ligament (ACL) and rotator cuff (RC) injuries are remarkably common. Despite the availability of relatively effective treatment modalities, outcomes often fall short of expectations. This comprehensive review aims to thoroughly examine current strategies employed to promote tendon-bone healing and analyze pertinent preclinical and clinical research. Amidst ongoing investigations, tendon-derived stem cells (TDSCs), which have comparatively limited prior exploration, have garnered increasing attention in the context of tendon-bone healing, emerging as a promising cell type for regenerative therapies. This review article delves into the potential of combining TDSCs with tissue engineering methods, with ACL reconstruction as the main focus. It comprehensively reviews relevant research on ACL and RC healing to address the issues of graft healing and bone tunnel integration. To optimize tendon-bone healing outcomes, our emphasis lies in not only reconstructing the original microstructure of the tendon-bone interface but also achieving proper bone tunnel integration, encompassing both cartilage and bone formation. In this endeavor, we thoroughly analyze the transcriptional and molecular regulatory variables governing TDSCs differentiation, incorporating a retrospective analysis utilizing single-cell sequencing, with the aim of unearthing relevant signaling pathways and processes. By presenting a novel strategy rooted in TDSCs-driven osteogenic and chondrogenic differentiation for tendon-bone healing, this study paves the way for potential future research avenues and promising therapeutic applications. It is anticipated that the findings herein will contribute to advancing the field of tendon-bone healing and foster the exploration of TDSCs as a viable option for regenerative therapies in the future.

Poster 293: Tendon Center Is Offset From Native Footprint and Tunnel Center in Bone-Patellar Tendon-Bone Grafts

Objectives: Much literature has been devoted to determining the proper tunnel positioning during arthroscopic anterior cruciate ligament (ACL) reconstruction (ACLR). However, to date, no literature has assessed whether the tunnel centroid closely approximates the final bone-patellar tendon-bone (BTB) graft positioning following interference screw fixation. Thus, the purpose of this human cadaveric study was to assess the difference in position between the native ACL footprint, drilled tunnel, and tendinous portion of a BTB graft following ACLR. It was hypothesized that the tendon position would be significantly more offset than the tunnel position from the native ACL footprint, given that the patellar tendon is not centered on the bone plugs of the BTB graft. Methods: Ten cadaveric specimens were included. A standard BTB graft was harvested from each specimen using an oscillating saw and scalpel and bone plugs were sized to a diameter of 10 mm for graft passage. The native ACL footprint (femur and tibia) of each specimen was mapped with a MicroScribe 3-dimensional (3D) coordinate digitizer. The centroid of each femoral footprint was determined by creating a 3D surface patch using an area-weighted technique. A guidewire was placed at the centroid of the native footprint and a 10 mm tunnel was overreamed to best approximate the centroid of the native footprint. The borders of the tunnel were then subsequently mapped out using the digitizer. A BTB graft was passed and secured in hyperextension with an 8 x 20 mm interference screw. Following fixation, the tendinous portion of the graft was mapped and a centroid was derived. This was repeated for the tibial side. Results: On the femur, mean cross-sectional area of the ACL footprint, tunnel, and tendinous portion of the graft were 154.89 ± 55.10 mm2, 86.45 ± 12.65 mm2, and 40.14 ± 10.68 mm2, respectively. The tendinous portion provided 26.7% coverage of the native footprint. The tendon centroid was significantly further than the tunnel centroid from the native footprint (2.90 ± 0.98 mm2 vs 0.38 ± 0.15 mm2, p ≤ 0.001). The tendon was mean 2.84 ± 0.83 mm2 from the tunnel, in the 6 o’clock direction (inferior). On the tibia, mean cross-sectional area of the ACL footprint, tunnel, and tendinous portion of the graft were 143.60 ± 19.00 mm2, 86.48 ± 8.76 mm2, 42.84 ± 6.70 mm2. The tendinous portion provided 30.01% coverage of the native footprint. The tendon centroid was significantly further that the tunnel centroid from the native footprint centroid (3.13 ± 0.23 mm2 vs 0.28 ± 0.07 mm2, p ≤ 0.001). The tendon centroid was mean 3.02 ± 0.16 mm2 from the tunnel centroid in the 11 o’clock direction (posterolateral). Conclusions: The findings of this study suggest that the soft tissue portion of BTB grafts is significantly offset from the tunnel centroid following ACLR fixation. While previous studies have emphasized tunnel placement from an isometry and biomechanical standpoint, future studies should study tunnel position in the context of where the soft tissue of the BTB graft ends up relative to the tunnel centroid. Future avenues of study would include determining whether a tunnel "cheat distance and direction" can be determined to routinely center the soft tissue of the ACLR graft appropriately within the anteromedial bundle of the native ACLR footprint for an optimal anatomic reconstruction.

EPB-TBM cutterhead torque and thrust modelling in rock tunnels through an analytical method and TSFS model

The analysis of cutterhead torque and thrust force is of utmost importance in the selection of a proper tunnel boring machine (TBM) and in achieving optimal operation of the earth pressure balance (EPB) machine for a specific project. This study focuses on the analysis of cutterhead torque and thrust force using data collected from the recent metro project of Tehran, specifically the southern extension of Tehran metro line 6, (TML6-SE). To assess the impact of geotechnical and operational parameters on the measured torque and thrust, a database consisting of 457 data points was established. The excavation of a significant portion of the project took place in a dense and robust limestone using a refurbished EPB machine with a diameter of 9.19m, initially designed for soft ground excavation. To complete this section of the tunnel, the cutterhead was equipped with disc cutters instead of rippers. Consequently, existing theoretical models for estimating torque and thrust of an EPB machine were modified to accommodate the hard rock boring process. Additionally, the Takagi-Sugeno fuzzy system (TSFS) was utilized in this study. The results of the models yielded quantitative conclusions, and the comparison between the measured and predicted target parameters demonstrated high accuracy. This study contributes to the understanding of the influence of various parameters on the performance of EPB machines in hard rock boring conditions, as well as providing insight into the potential adjustments needed in theoretical models for predicting cutterhead torque and thrust force. The proposed models showed satisfactory and reliable accuracy, with all models having an R2 value above 0.7 and loss function values nearing zero.

Fast Power Coefficient vs. Tip–Speed Ratio Curves for Small Wind Turbines with Single-Variable Measurements following a Single Test Run

Small wind turbines (SWTs) face tremendous challenges in being developed into a more reliable and widespread energy solution, with a number of efficiency, reliability, and cost issues that are yet to be resolved. As part of the development stages of an SWT, testing the resulting efficiency and determining appropriate working ranges are of high importance. In this paper, a methodology is presented for testing SWTs to obtain characteristic performance curves such as Cp (power coefficient) vs. TSR (tip–speed ratio), and torque vs. ω, in a simpler and faster yet accurate manner as an alternative energy solution when a wind tunnel is not available. The performance curves are obtained with the SWT mounted on a platform moving along a runway, requiring only a few minutes of data acquisition. Furthermore, it is only required to measure a single variable, i.e., the generator output voltage. A suitable physics-based mathematical model for the system allows for deriving the desired performance curves from this set of minimal data. The methodology was demonstrated by testing a prototype SWT developed by the authors. The tested prototype had a permanent magnet synchronous generator, but the methodology can be applied to any type of generator with a suitable mathematical model. Given its level of simplicity, accuracy, low cost, and ease of implementation, the proposed testing method has advantages that are helpful in the development process of SWTs, especially if access to a proper wind tunnel is prevented for any reason. To validate the methodology, Cp vs. TSR curves were obtained for an SWT prototype tested under different test conditions, arriving always at the same curve as would be expected. In this case, the test prototype reached a maximum power coefficient (Cp) of 0.35 for wind velocities from 20 to 50 km/h for a TSR of 5.5.

Analysis of Excavation Method on Inlet Tunnel of Controller Construction of Rukoh Dam Pidie District – Aceh Province

The tunnel of controller construction is located in Panton Bunot Village, Tiro Sub District, Pidie District, Aceh Province. The tunnel construction aims to flow the water from Kr. Tiro River to Rukoh inundation for water supply to Rukoh Dam in Keumala Sub District, Pidie District. The research aimed to comprehend engineering geological condition in the study area and determine excavation method at the inlet and proper tunnel support system. The determination of proper excavation method becomes crucial and it is required in maintaining affectivity and efficiency during tunnel construction process. Than excavation method determination is carried out calculation by using empirical method based on output parameter of laboratory test to the rock samples from core drilling in the tunnel track. The outputs are rock conditions as rock mass quality (RQD), discontinuity area density of the rock and rock stress strength. The condition of tunnel track was dominated by silt stone having very poor quality. UCS value was 3 Mpa – 10 Mpa. Joins spacing was less that 60 mm. Empirical analysis of excavation method explained that tunnel opening of Rukoh Controller Construction was highly weathered (HW) and required ripping as excavation type.

Risk Factors for Failures in Anterior Cruciate Ligament Reconstruction

This article provides a narrative review of the risk factors for anterior cruciate ligament reconstruction (ACLR) failures, as well as strategies to prevent such failures. Early timing for ACLR is not a risk factor for arthrofibrosis anymore according to recent studies. Vancomycin-soaked grafts appear to decrease infection rates after ACLR and are cost-effective. Proper tunnel placement is critical for anatomic ACLR to restore knee kinematics and joint stability. The article proposes a reproducible and accurate method for tunnel positioning. Increased sagittal plane tibial slope has been identified as a risk factor for primary ACLR failure. An anterior closing wedge proximal tibial osteotomy is suggested as a viable option for reducing posterior tibial slope. The lateral extra-articular tenodesis procedure in ACLR is effective in restoring both anterior tibial translation and rotatory stability.

More anterior placement of femoral tunnel position in ACL-R is associated with postoperative meniscus tears

PurposeThe purpose of this study was to investigate the relationship between tunnel position in ACL reconstruction (ACL-R) and postoperative meniscus tears.MethodsThis was a single institution, case–control study of 170 patients status-post ACL-R (2010–2019) separated into two matched groups (sex, age, BMI, graft type). Group 1—symptomatic, operative meniscus tears (both de novo and recurrent) after ACL-R. Group 2—no postoperative meniscus tears. Femoral and tibial tunnel positions were measured by 2 authors via lateral knee radiographs that were used to measure two ratios (a/t and b/h). Ratio a/t was defined as distance from the tunnel center to dorsal most subchondral contour of the lateral femoral condyle (a) divided by total sagittal diameter of the lateral condyle along Blumensaat’s line (t). The ratio b/h was defined as distance between the tunnel and Blumensaat’s line (b) divided by maximum intercondylar notch height (h). Wilcoxon sign-ranks paired test was used to compare measurements between groups (alpha set at p < 0.05).ResultsGroup 1 had average follow up of 45 months and Group 2 had average follow up of 22 months. There were no significant demographic differences between Groups 1 and 2. Group 1—a/t was 32.0% (± 10.2), which was significantly more anterior than group 2, 29.3% (± 7.3; p < 0.05). There was no difference in average femoral tunnel ratio b/h or tibial tunnel placement between groups.ConclusionsA relationship exists between more anterior/less anatomic femoral tunnel position and the presence of recurrent or de novo, operative meniscus tears after ACL-R. Surgeons performing ACL-R should strive for recreation of native anatomy via proper tunnel placement to maximize postoperative outcomes.Level of evidenceLevel III.

Novel tunnel staining technique to reduce premature entry in manual small-incision cataract surgery.

Mastering manual small-incision cataract surgery (MSICS) for beginner surgeons is difficult. In the initial days of residency or training, surgeons struggle to make a proper scleral tunnel and keratome entry. It commonly results in premature entry and iris prolapse. Most of the literature has shed light on premature entry during tunnel construction by a crescent blade, whereas a significant majority of iris prolapse happens due to improper keratome entry. This novel trypan blue dye-assisted tunnel staining (TBTS) technique helps in proper tunnel demarcation which can reduce the incidence of premature entry with a keratome.

Cyclops lesions associated with both bundles and selective bundle repair of the anterior cruciate ligament.

The remnant of a ruptured anterior cruciate ligament (ACL) can increase the risk of impingement or a cyclops lesion, which can increase challenges to proper tunnel placement. To evaluate the prevalence of cyclops lesions after ACL reconstruction and to assess the difference in the incidence of cyclops lesions between single-bundle repair and selective bundle repair of the ACL. This retrospective study included 151 patients who were diagnosed with an ACL tear after knee joint magnetic resonance imaging (MRI) who underwent ACL reconstruction surgery. MRI diagnosis of cyclops lesion formation was made if a soft-tissue mass was seen anteriorly in the intercondylar notch near the tibial insertion of the reconstructed ACL, based on sagittal T2-weighted (T2W) imaging. The size of the cyclops lesions was recorded as the largest diameter on the sagittal T2W imaging. A cyclops lesion was detected in 74 (38.5%) cases. Cyclops lesions were detected more frequently in cases with single-bundle repair of the ACL, but the results were not statistically significant (P = 0.609). Compared with selective bundle repair, cyclops lesions had a significantly higher prevalence in the posterolateral (PL) bundle repair than in the anteromedial (AM) bundle repair (P = 0.027) based on MR images at 6-12 months after surgery. The incidence of cyclops lesions did not differ significantly in single-bundle repair and selective bundle repair of ACL. However, selective PL bundle repair of the ACL showed a significantly increased incidence of cyclops lesions compared with selective AM bundle repair.

Postoperative high astigmatism - Refractive surprise following manual small-incision cataract surgery

Postoperative astigmatism plays an important role in the final visual outcome of cataract surgery. In small-incision cataract surgery, proper tunnel construction is of utmost importance for good structural integrity, leading to sutureless self-sealing wounds with lesser astigmatism. We report a case of postoperative high astigmatism following manual small-incision cataract surgery due to large, irregular, superficial, and more anterior corneal entry that lead to poor tunnel valve effect and wound sagging. This resulted in a poor postoperative unaided visual outcome.

Numerical Study on the Effect of Enhanced Buffer Materials in a High-Level Radioactive Waste Repository

In deep geological disposal system designs, it is important to minimize the installation area for cost effectiveness while satisfying the thermal requirements of the systems. An effective method to reduce the installation area for the systems is to employ an enhanced buffer material, as this can decrease the spacing between the disposal tunnels and deposition holes. Therefore, this study aims to evaluate the effect of an enhanced buffer material on the thermal behavior of the systems and their spacing. First, the discrete element method (DEM) was adopted to validate the thermal conductivity of the enhanced buffer material used, which was a mixture of bentonite and graphite. Then, a 3D finite element method (FEM) was conducted to analyze the proper disposal tunnel and hole spacing considering three cases with thermal conductivities values of the buffer as 0.8 W/(m K), 1.0 W/(m K), and 1.2 W/(m K). The results showed that the disposal tunnel and hole spacing could be reduced to 30 m and 6 m, respectively, when the temperature of the buffer surface facing the canister was 100 °C with a thermal conductivity value of approximately 1.2 W/(m K) or if more than 3% of graphite is added.

III–V nanowire backward diodes with high sensitivity above 1 MV W−1 for low-power microwave energy harvesting

Improved sensitivity of over 1 MV W−1, which exceeds that of conventional well-designed Schottky barrier diodes, was achieved in p-GaAs0.4Sb0.6/n-InAs nanowire backward diodes (NW BWDs) for low-power microwave energy harvesting at 2.4 GHz under zero-bias. The antimony composition in the GaAsSb NWs was increased to 0.6 to form proper interband tunneling of the BWDs. A linear detected characteristic of detection was obtained even when microwave input power was less than 1 μW. Furthermore, the reduction of parasitic capacitance due to the adoption of a reduced pad area helped in the improvement of the sensitivity of the NW BWDs. A large dynamic range in detection of low-power microwaves was obtained through the employment of an extended anode structure. Device simulations clarified that carrier depletion in GaAsSb NWs was the main cause of increased forward breakdown voltage, which resulted in the large dynamic range exhibited by the NW BWDs.

Non-Target Soil Deformation Mapping by Photogrammetry for Underground Tunnel Model Test

A complex urban environment requires frequent underground tunneling to resolve heavy traffic congestion. With new underground lines being constructed close to existing underground lines the soil deformation around the underground tunnels should be studied and analyzed with proper tunnel model tests. Therefore, we conducted non-target soil deformation mapping using photogrammetry for two different underground tunnel models of sandy soil and clay. Self-calibrated cameras were used to acquire before and after images of the models with the loading test. With accurately estimated exterior orientation parameters (EOPs), the soil deformation was measured via image matchings between two images. Different image matching parameters were tested and the effect of filtering was investigated to produce soil deformation vectors on the images. Experimental results showed that sandy soil and clay required different matching window sizes for the best results. In addition, the deformation vector filtering was helpful to suppress outliers only when an image matching threshold was not applied. With proper matching parameter setup and filtering, the visually informative soil deformation vector map could be generated using photogrammetry.

Revision of Failed-Posterior Cruciate Ligament (PCL) Reconstruction Due To Tibial Tunnel Misplacement: A Case Report

Objectives:Posterior cruciate ligament (PCL) reconstruction failure is a rare condition found. The failure caused by some factors, including improper graft tunnel placement. The proper tibial tunnel placement in PCL reconstruction is still controversial. To have an anatomical tunnel is essential to decrease the risk of failure. The use of PCL jig only to guide the direction of the tibial tunnel may not always give good results.Case presentation:We report a case of a 29-year-old male with a total rupture of ACL and PCL that underwent reconstruction for both ligaments. We found the failure of the PCL graft 2 years after the surgery was related to the tibial tunnel placement which was placed not in proper anatomical site. We performed revision PCL surgery with a transseptal portal technique to ensure the tibial tunnel is placed inappropriate position.Result:The cause of failure was associated with the miss position of the tibial tunnel. The tibial tunnel performed in previous surgery was too anterior than the anatomical footprint. This condition might be caused by a surgical technique that depending only on PCL jig to guide the tibial tunnel direction and location. We performed a transseptal portal technique to get better visualization on the posterior aspect of the knee to achieve the proper direction of the tibial tunnel.Conclusion:The use of PCL jig as the only tool for guiding tibial tunneling should be avoided. An additional tool such as a transseptal portal is required to ensure the proper anatomical tibial tunnel to achieve good PCL graft placement.

Arthroscopic Delivery of Injectable Bone Graft for Staged Revision Anterior Cruciate Ligament Reconstruction

Bone defects caused by femoral and tibial tunnel enlargement can pose a significant technical challenge when planning to perform revision anterior cruciate ligament reconstruction. A number of options have been described for managing osseous deficiencies, including the use of large autograft or allograft bone dowels to provide sufficient tunnel fill and subsequent structural support for revision surgery. These techniques can be time-consuming and technically demanding to ensure proper tunnel fill and press-fit stability of the bone graft. We describe our preferred technique for arthroscopic bone grafting using a mixture of demineralized cortical bone graft augmented with platelet-rich plasma delivered through a simple delivery system.

Morphological changes in tibial tunnels after anatomic anterior cruciate ligament reconstruction with hamstring tendon graft

BackgroundThree-dimensional (3D) reconstructed computed tomography (CT) is crucial for the reliable and accurate evaluation of tunnel enlargement after anterior cruciate ligament (ACL) reconstruction. The purposes of this study were to evaluate the tibial tunnel enlargement at the tunnel aperture and inside the tunnel and to clarify the morphological change at the tunnel footprint 1 year after the anatomic triple-bundle (ATB) ACL reconstruction using 3D CT models.MethodsEighteen patients with unilateral ACL rupture were evaluated. The ATB ACL reconstruction with a semitendinosus tendon autograft was performed. 3D computer models of the tibia and the three tibial tunnels were reconstructed from CT data obtained 3 weeks and 1 year after surgery. The cross-sectional areas (CSAs) of the two anterior and the one posterior tunnels were measured at the tunnel aperture and 5 and 10 mm distal from the aperture and compared between the two periods. The locations of the center and the anterior, posterior, medial, and lateral edges of each tunnel footprint were also measured and compared between the two periods.ResultsThe CSA of the posterior tunnel was significantly enlarged at the aperture by 40.4%, whereas that of the anterior tunnels did not change significantly, although the enlargement rate was 6.1%. On the other hand, the CSA was significantly reduced at 10 mm distal from the aperture in the anterior tunnels. The enlargement rate in the posterior tunnel was significantly greater than that in the anterior tunnels at the aperture. The center of the posterior tunnel footprint significantly shifted postero-laterally. The anterior and posterior edges of the posterior tunnel footprint demonstrated a significant posterior shift, while the lateral edge significantly shifted laterally. There was no significant shift of the center or all the edges of the anterior tunnels footprint.ConclusionsThe posterior tibial tunnel was significantly enlarged at the aperture by 40% with the morphological change in the postero-lateral direction reflected by the ACL fiber orientation 1 year after the ATB ACL reconstruction. The proper tibial tunnel location in the ACL reconstruction should be determined considering the tunnel enlargement in postero-lateral direction after surgery.

Quantitative radiographic assessment of the anatomic attachment sites of the anterior and posterior complexes of the proximal tibiofibular joint.

Quantitative guidelines for radiographic identification of the anterior and posterior ligaments of the proximal tibiofibular joint have not been well defined. The purpose of this study was to provide reproducible, quantitative descriptions of radiographic landmarks identifying the anterior and posterior ligament complexes of the proximal tibiofibular joint. It was hypothesized that consistent quantitative data regarding the radiographic location of the anterior and posterior proximal tibiofibular joint ligament complexes could be identified. The footprint centers of the individual ligament bundles of the anterior and posterior complexes of the proximal tibiofibular joint were labeled with radio-opaque markers in ten non-paired, fresh-frozen cadaveric knee specimens. Anteroposterior (AP) and lateral radiographs of the proximal tibiofibular joint were obtained, and distances between the markers and pertinent radiographic landmarks were recorded. On AP radiographs, the tibial span of the anterior complex was 12.8 ± 3.9mm and started at a median of 11.4mm distal to the tibial plateau; the fibular span was 11.6 ± 6.8mm and started at a median of 5.1mm from the apex of the fibular styloid. The tibial span of the posterior complex was 11.7 ± 8.4mm and began at a median of 12.1mm distal to the tibial plateau; the fibular span was 11.8 ± 7.9mm and began at a median of 3.1mm distal to the apex of the fibular styloid. Values were similar for lateral radiographs. The attachment locations of the proximal tibiofibular anterior and posterior complexes could be quantitatively correlated to reliable osseous landmarks and radiographic lines. This information will allow for consistent radiographic assessments of proper tunnel placement intraoperatively and postoperatively during anatomic reconstructions of the proximal tibiofibular joint.

Establishing the buttonhole technique as a puncture alternative for arteriovenous fistulas. Experience of a centre over 3 years

Abstract Introduction The buttonhole (BH) puncture technique for arteriovenous fistulas is an alternative to the classical staggered puncture. Purpose We present 3 years’ results incorporating the BH puncture technique for arteriovenous fistulas in our dialysis unit. Material and methods Twenty-two patients were started on BH technique, 15 men and 7 women (mean age: 62 years; SD: 12), with time spent on dialysis when starting the BH technique of 34 months (SD: 34, median: 27, range: 3–136). Seven patients received acenocoumarol and 9 antiplatelet agents. The vascular access median time at the beginning of the technique was 27 months (range: 3–252). Results Between 5 and 8 consecutive dialysis sessions were necessary to achieve a proper tunnel puncture. No patient suffered major complications. The average time on BH technique until December 2015 was 12 months (SD: 10, median: 9, range: 1–45). By the end of the study, 5 patients were performing self-puncture. Haemostasis times post-dialysis were reduced from 18.6 min (SD: 8, prior to the BH technique), to 12.2 min (SD: 3 after BH) ( p = 0.0005). Conclusions The BH technique is an alternative puncture technique for dialysis patients. Self-puncture and reduction in haemostasis time are potential beneficial aspects. A greater diffusion of this technique in the haemodialysis units would allow it to be better applied. A highly motivated nursing staff is key and a necessary condition for its implementation.

Instauración de la técnica de buttonhole como alternativa de punción para las fístulas arteriovenosas. Experiencia de un centro en 3 años

The buttonhole (BH) puncture technique for arteriovenous fistulas is an alternative to the classical staggered puncture. We present 3years' results incorporating the BH puncture technique for arteriovenous fistulas in our dialysis unit. Twenty-two patients were started on BH technique, 15 men and 7 women (mean age: 62 years; SD: 12), with time spent on dialysis when starting the BH technique of 34 months (SD: 34, median: 27, range: 3-136). Seven patients received acenocoumarol and 9 antiplatelet agents. The vascular access median time at the beginning of the technique was 27 months (range: 3-252). Between 5 and 8 consecutive dialysis sessions were necessary to achieve a proper tunnel puncture. No patient suffered major complications. The average time on BH technique until December 2015 was 12 months (SD: 10, median: 9, range: 1-45). By the end of the study, 5patients were performing self-puncture. Haemostasis times post-dialysis were reduced from 18.6min (SD: 8, prior to the BH technique), to 12.2minutes (SD: 3 after BH) (P=.0005). The BH technique is an alternative puncture technique for dialysis patients. Self-puncture and reduction in hemostasis time are potential beneficial aspects. A greater diffusion of this technique in the hemodialysis units would allow it to be better applied. A highly motivated nursing staff is key and a necessary condition for its implementation.