Tunnel Drilling Research Articles

Investigation of the specific charge variations in determining the optimal methods for drilling and blasting of tunnels

In this research, in order to compare and select the optimum patterns, two parameters of specific charge and specific drilling are used. Two explosive substances, including ammonium nitrate and fuel oil (ANFO) and Amulet, are used to charge the holes located on the cross-section of the tunnels in order to advance by 3 meters. Also, the cross-section of the selected tunnels was 19, 28, 32, 40, 48, 50, 65, and 76 square meters with horseshoe, circle and D-shaped. The diameter of the explosive hole is 48 mm for the Norwegian method and 51 mm for the two energy balance models and the Swedish method to compare them. A total of 160 designs are prepared for three types of limestone, sandstone and marl. The results obtained for two parameters of specific charge and special drilling for the selected rock material are completely opposite. Also, in the Swedish methods, according to the Amulet, the values of the calculated parameters are close to the energy balance model. Finally, according to the geomechanical parameters of the rock, for the Swedish method and the energy balance model in charging with amulet explosives, the energy balance model and the Holemberg-Persson method are proposed in the optimal design for the tunnel drilling and blasting pattern. In addition, for the Norwegian method and the energy balance model in charging the holes with ANFO, the energy balance model is prior to the Norwegian method. The amount of stemming of holes in different parts of the tunnel face is less for the Swedish method than the Norwegian and energy balance models.

Analysis of vibration signals near ground surface during blasting excavation of a tunnel in fractured rock

This study aims to analyze the vibration signals near the ground surface due to the underneath drilling and blasting activities in a fissured rock tunnel. Blasting induced vibration on the ground surface was continuously monitored in a fissured rock tunnel drilling and blasting excavation project in field. Wavelet packet analysis of the vibration signals using Matlab was carried out for signal denoising, differential blasting delay time interval identification, and three-way time-frequency energy analysis. The results show that within a 30 m range from the palm face, the dominant frequency bands of blasting-induced vibrations on the ground surface were concentrated in the range of 0–130 Hz. Two prominent peak frequency bands were identified at 31.25–39.063 Hz (low-frequency band) and 93.75–101.56 Hz (high-frequency band), accounting for 12% of the total energy. Among the three directions of ground surface vibrations, the energy decay was the most significant in the x-direction (tunnel excavation direction), which amounted to 54.29% of the overall energy decay with increasing distance. The energy decay within the 50–80 Hz range was the most pronounced (more than 90%), when the angle between the vibration propagation direction and the fissure or joint direction was 75°. The conclusions provide the insights in the attenuation of blast-induced vibrations in fissured rock and can potentially assist in the design of blasting vibration control.

Remnant Preservation Anterior Cruciate Ligament Reconstruction: Modified All-Inside Technique With Appendiceal Tibial Tunnel

The number of anterior cruciate ligament (ACL) ruptures treated arthroscopically has increased. In most cases, the rupture of the ligament occurs in the femoral attachment, leaving a robust stump attached to the tibia. ACL reconstruction with stump preservation might have some advantages: rapid reinnervation and revascularization of the graft. Most techniques have used an interference screw in tibial fixation, which could be more difficult to achieve the graft diameter within 8 to 10 mm in most situations. Therefore, we describe a technique for modified “all-inside” ACL reconstruction with remnant preservation using an appendiceal tibial tunnel to optimize the graft size. After tunnel drilling in anatomic positions, the ACL stump is bored centrally up to the diameter of the graft to be passed. After passing the graft from the tibial tunnel to the remnant to the femoral tunnel, adjustable loops are used to fix the femoral side and the tibial side by an appendiceal tibial tunnel.

Minimally Invasive 2-Incision Patellar Tendon Autograft Anterior Cruciate Ligament Reconstruction Using Retrograde Reamer Guide to Prevent Graft-Construct Mismatch

Graft-tunnel mismatch (GTM) is a known technical challenge that can occur with anterior cruciate ligament reconstruction when using a patellar tendon autograft. Two-incision anterior cruciate ligament reconstruction is a well-established technique with excellent outcomes and can serve as an excellent tool to prevent GTM. Traditionally, 2-incision femoral tunnel drilling has been performed using an over-the-top guide through a lateral incision, but more modern retrograde reamer guides can allow this to be done percutaneously. We detail how a minimally invasive 2-incision femoral tunnel drilling technique can be used in patients with patellar tendon lengths that are longer than average to avoid GTM.

A LESO Based Backstepping Controller Considering Coal Seam Hardness for Rotary Speed in Coal Mine Tunnel Drilling Process

A LESO Based Backstepping Controller Considering Coal Seam Hardness for Rotary Speed in Coal Mine Tunnel Drilling Process

Reconstruction of the medial collateral ligament complex with aflat semitendinosus auto- or allograft

Replacement of superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL) with an allograft. Chronic 3° isolated medial instability and combined anteromedial or posteromedial instability. Infection, open growth plates, restricted range of motion (less than E/F 0-0-90°). Longitudinal incision from medial epicondyle to superficial pes anserinus and exposure of the medial collateral ligament complex. Thawing of the allogeneic semitendinosus tendon graft at room temperature, reinforcement of the tendon ends with sutures and preparation of atwo-stranded graft. Placement of guidewires in the sMCL and POL insertions and control with image intensifier. Tunnel drilling. Pulling the graft loop into the femoral bone tunnel and fixation with aflip button. Pulling the two graft ends into the tibial tunnels. Tibial fixation by knotting the suture ends in a20° flexion on the lateral cortex. Suture the tendon bundles to the remaining remnants of the medial collateral ligament complex to adopt the flat structure of the natural medial collateral ligament complex. Six weeks partial weight-bearing, immediately postoperatively splint in the extended position, after 2weeks movable knee brace for another 4-6weeks. Mobility: 4weeks 0-0-60, 5th and 6th weeks 0-0-90. From 2015-2021, this surgical procedure was performed in 19patients (5women, 14men, age34years). Mean Lysholm score at follow-up after at least 2years was 89 (76-99) points. In 6patients, there was restricted range of motion 3months postoperatively, which resulted in further therapy (3 ×systemic cortisone therapy, 3 ×arthroscopically supported manipulations under anesthesia).

Refixation of aposterior medial root lesion in combination with centralization by ameniscotibial suture

Refixation of aposterior root lesion of the medial meniscus via atibial drill tunnel and prevention of extrusion using ameniscotibial suture (centralization). Posterior root lesion of the medial meniscus. Grade4 cartilage damage in the corresponding compartment, uncorrected varus or valgus deformities, symptomatic instabilities, extensive degenerative tears apart from the root region. Knee arthroscopy via the high anterolateral standard portal. Diagnostic arthroscopy to check indication. Locate the insertion zone on the tibial plateau and local debridement until the bone of the tibial plateau is visible. Insertion of atargeting device and drilling of atargeting wire into the center of the insertion zone in the area of the intercondylar eminence. Overdrill the target wire with a4.5 mm drill. Reinforcement of the medial meniscus posterior horn with braided suture material. The reinforcing thread is inserted into the bone tunnel via an eyelet wire with athread loop. Optional additional centralization with incision in the middle part of the meniscus. Reinforcement of the meniscus base with braided suture material using the "outside in" technique and fixation of the inner meniscus base at the edge of the tibial plateau using atransosseous extraction suture or asuture anchor. Six weeks nonweight-bearing (0kg), then gradually increased load. Range of motion: 4weeks E/F 0-0-60°, 2weeks 0-0-90°, optionally use of avalgus brace (varus of < 5°). In root lesions of the medial meniscus, transosseous refixation significantly improves knee function (Lysholm, Hospital for Special Surgery, International Knee Documentation Committee, visual analog scale for pain, Tegner, and Knee Injury and Osteoarthritis Outcome scores) and reduces osteoarthritis progression. However, atransosseous suture alone could not significantly reduce postoperative extrusion. However, previous studies have shown that additional centralization can significantly reduce extrusion.

Patient and Operative Risk Factors for Osteoarthritis After Primary Anterior Cruciate Ligament Reconstruction: A Cohort Study of 41,976 Patients

Background: The reported incidence of posttraumatic knee osteoarthritis (PTOA) after primary anterior cruciate ligament reconstruction (ACLR) varies considerably. Further, there are gaps in identifying which patients are at risk for PTOA after ACLR and whether there are modifiable factors. Purpose: To (1) determine the incidence of PTOA in a primary ACLR cohort and (2) identify patient and perioperative factors associated with the development of PTOA after primary ACLR. Study Design: Cohort study; Level of evidence, 3. Methods: Data from the Kaiser Permanente ACLR Registry were used to conduct a cohort study. Patients who had undergone primary ACLR without a previous diagnosis of osteoarthritis were identified (2009-2020). The crude incidence of PTOA was calculated using the Aalen-Johansen estimator with a multistate model. The association of patient and operative factors with the development of PTOA after primary ACLR was modeled as a time to event using multistate Cox proportional hazards regression. Models stratified by age (<22 and ≥22 years) were also conducted because of the effect modification of age. Results: The study sample included 41,976 cases of primary ACLR. The incidence of PTOA was 1.7%, 5.1%, and 13.6% at 2, 5, and 10 year follow-ups, respectively. Risk factors for PTOA that were consistently identified in the overall cohort and age-stratified groups included a body mass index ≥30 versus <30 and an allograft or quadriceps tendon autograft versus a hamstring tendon autograft. Patients presenting with knee pain after ACLR were further identified when considering postoperative factors. Other risk factors for PTOA in the overall cohort included age ≥22 versus <22 years, bone–patellar tendon–bone autograft versus hamstring tendon autograft, hypertension, cartilage injury, meniscal injury, revision after primary ACLR with concomitant meniscal/cartilage surgery, multiligament injury, other activity at the time of injury compared with sport, and tibial tunnel drilling technique rather than the anteromedial portal. Conclusion: Knee pain after ACLR may be an early sign of PTOA. Surgeons should consider the adverse associations of a higher body mass index and an allograft or quadriceps tendon autograft with the development of PTOA, as these were factors identified with a higher risk, regardless of a patient’s age at the time of primary ACLR.

Functional and Symptomatic Improvements Based on the Femoral Tunnel Drilling Technique in Anterior Cruciate Ligament (ACL) Reconstruction.

The current literature comparing femoral tunnel techniques often reports on short-term outcomes after anterior cruciate ligament reconstruction (ACLR), but only a few studies have analyzed long-term outcomes. In addition, many studies have compared transtibial to anteromedial portal techniques without differentiating whether rigid or flexible reaming is used, making it difficult to infer how the techniques truly compare to one another. This study aimed to detect differences in patient-reported outcome scores in those treated with three different femoral tunnel drilling techniques. This study is a prospective cohort study. Of 650 patients treated for anterior cruciate ligament (ACL) injuries with ACLR, 350 were 5+ years out from surgery. Of these patients, 111 completed patient-reported outcome surveys (PROs). The Kruskal-Wallis H test was used to detect differences between patients treated with either of the three femoral tunnel drilling techniques: transtibial (TT), anteromedial portal with rigid reaming (AMP-RR), or anteromedial portal with flexible reaming (AMP-FR). Bonferroni correction was applied to the p-values to reduce the risk of making a type 1 error. No differences were found between the three groups in demographics or postoperative PROs. However, there was a significant change between pre-surgery and post-surgery PROs. TT, when compared to AMP-RR, had a greater increase in satisfaction and greater improvement in a patient's ability to go up and down the stairs from pre-surgery to post-surgery. AMP-FR, when compared to TT, had greater improvement of the patient's knee stiffness/swelling. AMP-FR, when compared to AMP-RR, had greater improvement in knee pain during stairs and the ability to go down the stairs. No differences in return to sport, additional procedures on the affected knee (meniscal surgeries or cyclops lesion excisions), or revision surgery rates were found. Overall, postoperative PROs did not show statistically significant differences between the three femoral tunnel drilling techniques. Differences, however, were identified in the responses to specific questions on PRO surveys, which may have otherwise been overlooked. It is important to recognize the differences between TT, AMP-RR, and AMP-FR in the improvement of stair climbing and swelling/stiffness as these likely directly affect a patient's satisfaction from pre-ACLR to post-ACLR.

3D C-arm navigated suture button implantation for AC joint dislocations - the pilot study.

The surgical treatment of acute traumatic AC joint dislocations is still a subject of scientific debate in the literature. The arthroscopically assisted stabilization procedure with a suture button system has been successfully established and is widely used in daily practice. It is minimally invasive and allows the anatomical reconstruction of the torn coracoclavicular ligaments in one step with a permanent implant that does not have to be removed in a second operation. This clinical pilot study is the first to describe the new method of navigated suture button implantation with the future aim of further reducing surgical invasiveness and further increasing surgical precision. 10 patients with a Rockwood 3b/5 injury could be included in the prospective study (DRKS00031855) within 5 months according to inclusion and exclusion criteria. Surgical stabilization was performed with a suture button system via a navigated coracoclavicular drill tunnel. Demographic and radiological data as well as information on health and shoulder function were collected from patient records, X-rays, DVT scan and 3 questionnaires (DASH, NHS and Eq.5D) at the preoperative, intraoperative and postoperative (discharge, 6 weeks and 3 months) time points. All operations could be performed within 8.8 days (± 6.81) after trauma. The average operation time was 50.3min (± 8.81). The mean distance of the drill hole in the clavicle to the AC joint was 26.6mm (± 2.63). The radiologically measured vertical coracoclavicular distance was 38.8mm (± 6.16) at discharge and 41.11mm (± 7.51) at 3 months. This loss of reduction was not statistically significant. In contrast, the DASH, NHS and Eq.5D results showed significant improvement from discharge to 3 months postoperatively. Image-guided 3D C-arm navigated AC joint suture button stabilization is feasible in everyday surgical practice. It may be possible to achieve a further reduction in invasiveness while at the same time increasing the accuracy of implant positioning. Further clinical studies with a larger number of patients and a longer follow-up period are necessary to enable a comparison with conventional methods.

Surgical accidents and postoperative complications of recurrent shoulder dislocation treated by suture button fixation with bone occlusion

To summarize the surgical accidents and postoperative complications of the treatment of recurrent shoulder dislocation by suture button fixation and bone occlusion, and to provide clinical reference. The clinical data of 16 patients with recurrent shoulder dislocation treated with modified arthroscopic Latarjet suture button fixation and bone occlusion between July 2017 and April 2023 were retrospectively analyzed. Among them, 15 were male and 1 was female. The age ranged from 16 to 45 years, with an average of 26 years. Admission examination showed the range of motion of shoulder joint was normal; the shoulder joint fear test was positive; En-face CT scan measured 10%-20% of the glenoid defects, averaging 13.4%; and MRI examination revealed bone Bankart injury. The disease duration ranged from 2 to 20 years, with an average of 7.1 years. The shoulder joint was dislocated 8- 45 times, with an average of 17.4 times, and the shoulder joint was unstable. The occurrence of surgical accidents and postoperative complications as well as corresponding measures and outcomes were recorded. All the incisions healed by first intention without any complications such as incision infection or vascular injury. All 16 cases were followed up for an average of 3.6 years (range, 1-7 years), and no shoulder redislocation occurred. Four types of intraoperative surgical accidents and two types of postoperative complications occurred in the early stage of implementation of the technique. Intraoperative surgical accidents included 1 case of difficulty in passing subscapular muscle through coracotomy with large size, which was treated with exchange rod or finger through subscapular muscle split; 2 cases of coracoidal process fracture, of which 1 case was treated conservatively, and the other case was sutured to the base of tendon and fixed through tunnel; 1 case of glenoid fracture occurred in the glenoid tunnel, which was fixed with knot-free anchors; the posterior loop plate fixation was abnormal in 2 cases, of which 1 case was re-fixed and the other case was renovated. Postoperative complications included coracoid bone mass displacement in 1 case, conservative biceps rehabilitation was given to avoid premature external rotation; 1 case of radial nerve injury of healthy upper limb and musculocutaneous nerve injury of affected side was given oral medication and physiotherapy. The above conditions recovered well after corresponding treatment. Suture button fixation with bone occlusion is a safe method for the treatment of recurrent shoulder dislocation. Careful operation should be performed during coracoid interception and glenoid tunnel drilling, especially in the fixation process.

The Method of 3D C-arm Navigated AC Joint Stabilization-Surgical Technique

Background: The arthroscopically assisted stabilization of AC joint dislocations with a suture button system is an established procedure that is widely and successfully used in everyday practice. The main advantages of this one-step method are the minimally invasive procedure and the anatomical reconstruction of the ruptured coracoclavicular ligaments with a permanent implant. With this technical note study, for the first time, the new method of navigated suture button implantation in everyday clinical practice is described with the future goal of further reducing invasiveness and increasing precision. Materials and Methods: The surgical technique is explained using precise descriptions and illustrations, photos, X-rays, and 3D reconstructions based on clinical cases. The step-by-step system setup and patient positioning, AC joint reduction and retention, 3D scan and drill tunnel planning, stab incision and Kirschner wire navigation, and cannulated drilling and implant positioning, as well as closure and documentation are described in detail. Results: The standard coracoclavicular stabilization of AC joint dislocations with the 3D C-arm navigated suture button method is described in detail. Furthermore, the feasibility of an additive horizontal acromioclavicular suture cerclage, the implantation of an additional coracoclavicular suture button system, and the single-stage cannulated screw fixation of non-displaced fractures is demonstrated. Conclusion: The navigated suture button method aims to be simple, safe, minimally invasive, and precise. Prospective clinical studies with a long follow-up should be carried out to determine the clinical and radiological outcome in comparison with current methods.

Clinical Outcomes of a Novel Hybrid Transtibial Technique for Femoral Tunnel Drilling in Anterior Cruciate Ligament Reconstruction: A Large Single-Center Case Series With a Minimum 2-Year Follow-up.

A novel hybrid transtibial (HTT) approach to femoral tunnel drilling in anterior cruciate ligament reconstruction (ACLR) has been developed that circumvents the need for knee hyperflexion and orients the graft in the most anatomic position without sacrificing the tunnel length or aperture. Patients who underwent ACLR utilizing the HTT technique would achieve excellent patient-reported outcome scores and experience low rates of graft failure and reoperations. Case series; Level of evidence, 4. Patients who underwent primary ACLR at a single institution between 2005 and 2020 were retrospectively reviewed. Patients treated with the HTT, anteromedial portal (AMP), and transtibial (TT) approaches were matched based on age, sex, and body mass index ±3 kg/m2. Demographic and surgical data as well as femoral tunnel angle measurements on anteroposterior and lateral radiographs were collected for the 3 groups. However, clinical outcomes were only reported for the HTT group because of concerns of graft heterogeneity. A total of 170 patients (median age, 26.5 years [interquartile range (IQR), 18.0-35.0 years]) who underwent ACLR using the HTT approach were included. The median coronal- and sagittal-plane femoral tunnel angles were 47° (IQR, 42°-53°) and 40° (IQR, 34°-46°), respectively. The sagittal-plane femoral tunnel angles in the HTT group were significantly more horizontal compared with those in the TT group (P < .0001), whereas the coronal-plane femoral tunnel angles in the HTT group were found to be significantly more vertical compared with those in the AMP group (P = .001) and more horizontal compared with those in the TT group (P < .0001). The graft failure and reoperation rates in the HTT group at a minimum 2-year follow-up were 1.8% (3/170) and 4.7% (8/170), respectively. The complication rate was 6.5% (11/170), with the most common complication being subjective stiffness in 7 patients. The median Lysholm score was 89.5 (IQR, 79.0-98.0); the median International Knee Documentation Committee score was 83.9 (IQR, 65.5-90.8); and the median Veterans RAND 12-Item Health Survey physical and mental component summary scores were 55.0 (IQR, 52.6-55.9) and 56.2 (IQR, 49.1-59.3), respectively. ACLR using the HTT technique was associated with low graft retear and revision surgery rates and good patient-reported outcome scores at medium-term follow-up and demonstrated femoral tunnel obliquity on postoperative radiographs that correlated with optimal parameters previously reported in cadaveric and biomechanical studies.

Drilling the tibial tunnel in an arthroscopic popliteus bypass from the anteromedial tibial cortex decreases risk of popliteal vascular injury

PurposeDrilling the tibial tunnel in tibiofibular-based posterolateral corner (PLC) reconstructions is usually performed with a starting point from Gerdy's tubercle. Drilling the tunnel starting from the anteromedial tibial cortex could reduce the risk of popliteal neurovascular (PNV) injury. The purpose of this study is to assess the distance on Magnetic Resonance Imaging Scans (MRI) of the PNV bundle and peroneal nerve (PN) to these two different tunnel trajectories. MethodsA total of 87 MRI scans were assessed. The ideal exit point of the tibial tunnel in PLC reconstructions was marked. We added 10 mm from this point in a straight posterior and in an oblique trajectory, mimicking the two different tunnel trajectories and measured the distance to the PNV bundle and PN from these two points. ResultsThe mean distance of the tip of the guide wire drilled with a trajectory from Gerdy's tubercle to the PNV bundle and the peroneal nerve was respectively 13.2 mm (SD = 3.96) and 17.7 mm (SD = 4.39). The mean distance of the tip of the guide wire drilled with a trajectory from the anteromedial tibial cortex to the PNV bundle and the PN was respectively 19.6 mm (SD = 4.19) and 12.2 mm (SD = 3.96).). Drilling in a trajectory from the anteromedial tibial cortex significantly increases the distance to the PNV bundle (p < 0.001). ConclusionTibial tunnel drilling in a tibiofibular based PLC reconstruction from the anteromedial tibial cortex significantly increases the distance to the popliteal artery but with a decreased distance to the peroneal nerve. Level of evidencelevel IV.

Research on the theory and method of reduced-hole blasting for large cross-section tunnel based on explosive energy dissipation

The traditional tunnel drilling and blasting method places cut holes at the lower center of the excavation face, resulting in an excessive number of blasting holes. With the continuous increase in cross-section area, this design concept can no longer meet the requirements of safe and efficient tunnel boring for large cross-section tunnels. This paper puts forward the theory and method of reduced-hole blasting for large cross-section tunnels, as an alternative to the traditional drilling and blasting method of the “more holes, less charge” design concept. Based on the explosion energy dissipation law and rock’s critical crushing energy dissipation characteristics, the calculation method of the extrapolation distance of the wedge-cut holes is given. The optimum extrapolation distance of the wedge-cut holes was verified using numerical simulation and field tests. The results show that the number of drilling holes can be reduced by about 15.8% using the theory and method proposed in this paper, and at the same time, the damage of retained rock can be effectively controlled. The results of this study can provide a reference for the design of blast network parameters for similar large cross-section tunnels.

The method of femoral tunnel drilling in anterior cruciate ligament reconstruction does not influence the return to sport rate

BackgroundLimited evidence is available comparing the modified transtibial (MTT) and transportal (TP) techniques in anterior cruciate ligament (ACL) reconstruction and their impact on returning to sports participation. The objective was to analyze the outcomes after arthroscopic reconstruction of the ACL in recreational athletes with a 2-year postoperative follow-up, comparing the MTT and TP techniques, based on the method used to drill the femoral tunnel. HypotesisThe rate of return to sport would be comparable regardless of the surgical technique used. Material and methodsA retrospective study was conducted with 66 patients who underwent arthroscopic monofascicular ACL reconstruction between September 2016 and March 2020. Patients aged between 16 and 50 years old, recreational athletes at Tegner levels 6 and 7, with a 2-year follow-up were included. Groups were established for comparative analysis (MTT vs TP) based on the method for drilling the femoral tunnel. The main outcome variable was the return to sport at the same level. Secondary variables included patient satisfaction evaluated with a visual analogue scale (VAS) and knee function according to the Lysholm scale. ResultsAt 2 years of postoperative follow-up, the return to sport rate was 30.3 % in the MTT group and 33.3 % in the TP group (p = 0.791). There were no significant differences between both groups in patient satisfaction (p = 0.664) and knee function (p = 0.113). ConclusionDrilling the femoral tunnel with the MTT and TP techniques did not influence the rate of return to sport, patient satisfaction, and knee function in recreational athletes with 2 years of postoperative follow-up. Level of evidenceIII.

The tibial capsular reflection and septum in posterior compartment are safe and reliable soft-tissue landmark for tibial tunnel drilling in posterior cruciate ligament reconstruction.

To investigate the validity of using tibial capsular reflection and septum in the posterior compartment as landmark during posterior cruciate ligament (PCL) reconstruction (PCLR). Anatomic measurements were obtained for 12 fresh human cadaveric knee specimens to observe the spatial position of the tibial insertion of the PCL in relation to the posterior septum and the capsular reflection in the posterior compartment. Sixty patients who underwent reconstruction of the PCL between 2020 and 2023 were also retrospectively investigated. The tibial tunnel was replaced in all patients using the same method (with reference to the tibial capsular reflection and the posterior septum). The placement of the tibial tunnel was assessed using X-ray fluoroscopy intraoperatively and computed tomography and three-dimensional reconstruction postoperatively. All fibres in the tibial insertion of the PCL in the 12 cadaveric specimens were located in the posteromedial compartment, adjacent to the posterior septum. The inferior border of the PCL insertion is adjacent to the tibial capsular reflection, which is attached at the champagne glass drop-off of the posterior tibia. In our previous cases, none of the patients experienced postoperative or intraoperative complications such as neurovascular injury, and the angle between the pin and the PCL facet was 93.1 ± 3.9° as measured on intraoperative radiographs. The mean distance from the centre of the tibial tunnel outlet to the inferior border of the PCL insertion was 5.6 ± 1.1 mm, and the distance from the centre of the tibial tunnel outlet to the outer border of the PCL insertion as a percentage of the length of the inferior border of PCL insertion was 42.2 ± 6.3%. The tibial capsular reflection and septum in the posterior compartment are safe and reliable soft-tissue landmark for tibial tunnel drilling in PCLR. Level Ⅳ.

Robot-assisted anterior cruciate ligament reconstruction based on three-dimensional images

Background Tunnel placement is a key step in anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to evaluate the accuracy of bone tunnel drilling in arthroscopic ACL reconstruction assisted by a three-dimensional (3D) image-based robot system. Methods Robot-assisted ACL reconstruction was performed on twelve freshly frozen knee specimens. During the operation, three-dimensional images were used for ACL bone tunnel planning, and the robotic arm was used for navigation and drilling. Twelve patients who underwent traditional arthroscopic ACL reconstruction were included. 3D computed tomography was used to measure the actual position of the ACL bone tunnel and to evaluate the accuracy of the robotic and traditional ACL bone tunnel. Results On the femoral side, the positions of robotic and traditional surgery tunnels were 29.3 ± 1.4% and 32.1 ± 3.9% in the deep-to-shallow direction of the lateral femoral condyle (p = 0.032), and 34.6 ± 1.2% and 21.2 ± 9.4% in the high-to-low direction (p < 0.001), respectively. On the tibial side, the positions of the robotic and traditional surgical tunnels were located at 48.4 ± 0.9% and 45.8 ± 2.8% of the medial-to-lateral diameter of the tibial plateau (p = 0.008), 38.1 ± 0.8% and 34.6 ± 6.0% of the anterior-to-posterior diameter (p = 0.071), respectively. Conclusions In this study, ACL reconstruction was completed with the assistance of a robot arm and 3D images, and the robot was able to drill the bone tunnel more accurately than the traditional arthroscopic ACL reconstruction.

Utilizing Crushed Limestone as a Sustainable Alternative in Shotcrete Applications.

Solving the challenges facing the mining industry is crucial for shaping the global attitude towards clean energy technologies associated with critical minerals extracted from depth. One of these challenges is the well-known explosion-like fractures (rockbursts) or spalling failures associated with the initiation of internal cracks. To prevent such catastrophic failure, shotcrete, as a cement grout, is widely used in tunnel support applications. In areas where the tunnels are constructed within the limestone strata using tunnel boring machines (TBM), drilling, and/or blasting, millions of cubic meters of crushed limestone (CL) in powder form are extracted and landfilled as waste. Given the fact that natural sand consumption as a raw material in the construction industry exceeds previous records, recycling of such excavation material is now becoming increasingly needed. From this perspective, this study aims to utilize crushed limestone as a potentially sustainable alternative to natural sand in shotcrete applications in deep tunnels. Accordingly, several strength characterization and crack initiation determinations through various stress-strain-based models were carried out on cylindrical samples containing different proportions of crushed limestone. By increasing the crushed limestone content in the shotcrete mix, the crack initiation stress (as a measure of the in situ spalling strength) increased as well. The results suggest that the crushed limestone has good potential to replace the natural sand in the shotcrete mixture used in tunnel support applications.

Automatic early warning of rockbursts from microseismic events by learning the feature-augmented point cloud representation

This study proposes an automatic early warning system for rockbursts in deeply buried tunnels using microseismic data. A novel machine learning model is introduced, which is the first to treats the microseismic event data as a high-dimensional point cloud. The model utilizes a fast approximated convolution (FAC) method to effectively and efficiently learn features from the raw event data with small model sizes. The model is trained and tested using microseismic data from the Hanjiang-To-Weihe water diversion project. Two competing models, a time series model and a traditional threshold model, are also constructed for comparison. Results show that the proposed model achieves reliable early warnings for 90.1% of rockbursts in the tunnel. This study presents a new and feasible rockburst prediction method that can be used independently or as a supplement to current assessment and management approaches for both tunnel boring machines (TBMs) and drilling- and blasting-excavated tunnels.