Improved Repair Techniques Research Articles

The comparative study of epoxy and bacterial injections for cracked concrete beam flexural strength

Cracks in concrete beams can significantly affect the performance of reinforced structures. To repair cracks in concrete, Traditional crack repair methods typically involve epoxy injection, but studies have suggested that epoxy may not fully restore the original strength. Therefore, concrete structure repair requires the development of new and more efficient materials. This study focuses on investigating the potential of Bacillus megaterium, a bacterium known for its self-healing properties in concrete. This bacterium has the capability to precipitate minerals like calcium carbonate, which can fill the cracks and increase the strength of concrete. Testing is carried out on reinforced concrete beams with existing cracks, sized at 100 mm x 100 mm x 500 mm. The specimens are divided into two groups, one repaired with epoxy injection and the other with bacterial injection, with varying additions of 10% and 15%. The research results show that the injection process with the addition of 15% bacteria is able to restore approximately 99.72% of the initial strength of the concrete beams. The results of this research contribute to the development of improved repair techniques that can restore the flexural strength of cracked concrete beams and extend the service life of concrete structures.

Translated article] Efficacy of transplantation of lipoaspired mesenchymal stem cells in the treatment of chronic rotator cuff tears. Experimental model in rats

Background and aimRotator cuff tears emerge in approximately 30% of the population over 60 years of age. Arthroscopic surgical treatment of these lesions is the treatment of choice, however, despite the improved repair techniques, the rate of re-tears ranges between 11 and 94%. Therefore, researchers seek to improve the biological healing process through the use of different alternatives such as mesenchymal stem cells (MSCs). Our objective is to evaluate the efficacy of a cellular therapy drug made from allogeneic stem cells derived from adipose tissue in a rat model of chronic rotator cuff injury. Material and methodsThe supraspinatus lesion was created in 48 rats for subsequent suturing at 4 weeks. MSCs in suspension were added to 24 animals after suturing, and HypoThermosol-FRS® (HTS) to 24 animals as a control group. Histology (Åström and Rausing scale) and the maximum load, displacement and elastic constant of the supraspinatus tendon were analysed in both groups 4 months after the repair. ResultsNo statistically significant differences were found in the histological score comparing the tendons treated with MSCs with respect to the tendons treated with HTS (P=0.811) nor in the results of maximum load (P=0.770), displacement (P=0.852) or elastic constant (P=0.669) of the tendon in both groups. ConclusionsThe addition of adipose-derived cells in suspension to the repair of a chronic cuff injury does not improve the histology or biomechanics of the sutured tendon.

Eficacia del trasplante de células madre mesenquimales de lipoaspirado en el tratamiento de lesiones crónicas del manguito rotador. Modelo experimental en ratas

Background and aimRotator cuff tears emerge in approximately 30% of the population over 60 years of age. Arthroscopic surgical treatment of these lesions is the treatment of choice, however, despite the improved repair techniques, the rate of re-tears ranges between 11 and 94%. Therefore, researchers seek to improve the biological healing process through the use of different alternatives such as mesenchymal stem cells (MSCs). Our objective is to evaluate the efficacy of a Cellular Therapy Drug made from allogeneic stem cells derived from adipose tissue in a rat model of chronic rotator cuff injury. Material and methodsThe supraspinatus lesion was created in 48 rats for subsequent suturing at 4 weeks. MSCs in suspension were added to 24 animals after suturing, and HypoThermosol-FRS® (HTS) to 24 animals as a control group. Histology (Åström and Rausing scale) and the maximum load, displacement and elastic constant of the supraspinatus tendon were analyzed in both groups 4 months after the repair. ResultsNo statistically significant differences were found in the histological score comparing the tendons treated with MSCs with respect to the tendons treated with HTS (P=.811) nor in the results of maximum load (P=.770), displacement (P=.852) or elastic constant (P=.669) of the tendon in both groups. ConclusionsThe addition of adipose-derived cells in suspension to the repair of a chronic cuff injury does not improve the histology or biomechanics of the sutured tendon.

Surgical treatment of mitral regurgitation.

Mitral repair is the best treatment for degenerative mitral regurgitation. Many patients are referred too late for optimal outcomes. The US repair vs. replacement rate is only 60-80%, at a time when the inferiority of replacement has been established. Therefore, widely used traditional techniques of repair are being reappraised. Identification of risk factors predictive of poor early and late outcome have improved timing for surgical referral. Composite risk scores have been developed. Novel echocardiographic, cardiac MRI, and molecular level risk factors could improve timing. Analysis of factors contributing to low repair rates is also of critical importance. The role of institutional and surgeon volumes have been identified. More detailed data on the importance of dynamic function of the mitral valve have led to improved repair techniques such as intraoperative simulation of end diastole and early systole, use of expanded polytetrafluoroethylene neochords instead of leaflet resection, and dynamic instead of rigid annuloplasty. Our perception of mitral regurgitation has changed from a seemingly simple condition to one of considerable complexity at multiple levels. National guidelines should be studied and followed.

Recent advances and future trends in knee arthroscopy

Knee arthroscopic surgery continues to advance in leaps and bounds. The anterior cruciate ligament (ACL) remains the most controversial structure to be operated on in the knee, and although the enthusiasm for double- bundle reconstruction has waned, there is a definite preference for anatomic reconstruction using an individualized approach. Despite early failed attempts at ACL primary repair, there is a renewed interest in this preservative approach with the application of technologically advanced instruments and implants. The thrust toward meniscal preservation too continues as better understanding of meniscal healing, improved repair techniques, and novel methods to enhance healing have encouraged surgeons to repair tears previously deemed irreparable. Similarly, articular cartilage surgery has advanced with better understanding of cellular mechanisms and the development of newer techniques of cartilage regeneration. Although the focus in the present era has been to restore anatomy with optimal biomechanical constructs, upcoming technology will address biological concerns in healing, especially with degenerate tissues. Future trends in knee arthroscopy include application of scaffolds, orthobiologics, stem cells, and bioreactors to generate personalized, and patient specific autogenous tissue engineered implants. This review article summarizes the latest developments in knee arthroscopy and predicts future trends in this rapidly advancing subspecialty.

Reattachment of the flexor and extensor tendons at the epicondyle in elbow instability: a biomechanical comparison of techniques

BackgroundElbow dislocation represents a common injury, especially in the younger population. If treated surgically, the reattached tendons require a high amount of primary stability to allow for an early rehabilitation to avoid postoperative stiffness. The purpose of this study was to assess the biomechanical properties of a single and a double row technique for reattachment of the common extensor and common flexor muscles origin. We hypothesized that the double row technique would provide greater stability in terms of pullout forces than the single row technique.MethodsTwelve cadaveric specimens were randomized into two groups of fixation methods for the common extensor tendon or the common flexor tendon at the elbow (1): a single row technique using two knotted 3.0 mm suture anchors, and (2) a double row technique using an additional knotless 3.5 mm anchor. The repairs were cyclically loaded over 500 cycles at 1 Hz from 10 N to a maximum of 100 N (extensors) or 150 N (flexors), and then pulled to failure. Stiffness and maximum load at failure and mode of failure were recorded and calculated.ResultsNo significant differences in stiffness were observed between the two techniques for both the extensor and flexor reattachment (P = 0.701 and P = 0.306, respectively). The mean maximum load at failure indicated that the double row construct was significantly stronger than the single row construct. This was found to be true for both the extensor and flexor reattachment (213.6; SD 78.7 N versus 384.1; SD 105.6 N, P = 0.010 and 203.7; SD 65.8 N versus 318.0; SD 64.6 N, P = 0.013, respectively).ConclusionsThe double row technique provides significant greater stability to the reattached common flexor or extensor origin to the medial or lateral epicondyle. Thus, it should be considered in the development of improved repair techniques for stabilizers of the elbow.Study designControlled laboratory study.

The Road Steel Bridge Over Bosut River in Serbia Part 1: The Assessment of the Bridge

Maintenance requirements for existing bridges outpace more and more available resources each day. Besides improved repair techniques, this situation emphasizes the need for a comprehensive approach to bridge management. An important activity in bridge maintenance is the inspection and assessment process, which includes determination of the general condition and structural safety of each bridge, as well as estimation of deterioration rates. Eventually, some idea of the structure repair can be determined. In this paper, the assessment of road steel bridge over Bosut river in Serbia was presented. During exploitation, numerous damages appeared on the bridge structural elements, mostly due to hundred years’ old exploitation and inadequate maintenance of the bridge. In order to evaluate the real condition of the bridge structure and possibilities for further exploitation, the assessment of the bridge was carried out. The assessment included: detailed visual inspection of all accessible elements with registration of characteristic defects and damages, evaluation of incorporated materials quality, determination of the depth of cracks in the river piers and structural calculation according to current regulations for road bridges loads. Based on the results of both field and laboratory tests, it was concluded that the durability of bridge structure is significantly reduced, due to advanced corrosion process of steel material.

Experimental Investigation of Load Sharing Behavior for Timber Half-Caps of Toodyay Bridge

This study investigates the load sharing capabilities for half-caps of a 190m long timber bridge. The bridge has 31 spans over the Avon River in Toodyay, Western Australia. It was constructed from local hardwood timbers and had a series of repairs. However as the width between kerbs was only 5.5 m and it was no footpath it was decided to replace the bridge by a new wider concrete structure. The proposed removal of the existing bridge provided an opportunity to carry out a research program aimed at bridge inspection, estimation of timber material properties, required for more accurate modeling of structural failure as well as selection of improved repair techniques and strengthening methods. Non- destructive evaluation of the bridge prior to construction of a new one was conducted using trucks to provide both static and dynamic loadings. Half-cap load sharing was examined for north and south loading of the bridge deck at the pier and span positions. This paper deals with the results obtained only the north loading case at the pier position. As Toodyay Bridge 631 is a typical timber bridge in Western Australia, the findings of this study can be applied to other bridges to prolong their lifetime.

Current concepts in arthroscopic rotator cuff repair: single vs. double row repair

Purpose of review: Both arthroscopic and open rotator cuff repair techniques have significant recurrence rates in large and massive tears, which has motivated development of improved repair techniques. Double-row and suture-bridge repair techniques offer potential biologic and biomechanical advantages over single-row repairs and may enhance stability and healing. Recent findings: In the past year, several biomechanical studies have shown improved strength, durability, contact area and contact pressure for double-row rotator cuff repair compared with single-row techniques. In addition, the first in-vivo anatomic study demonstrated that double-row repairs more accurately restore the supraspinatus footprint and the first clinical follow up focusing on double-row repair revealed decreased rates of structural failure compared with single row. Furthermore, increased attention has been focused on simplifying transosseous-equivalent, or ‘suture bridge’ constructs and studying their biomechanical properties. Summary: Based on recently published studies, double-row rotator cuff repair offers improved restoration of footprint anatomy, greater strength, durability, and contact pressure compared with single-row repair. Suture-bridge techniques may improve these parameters even further.

Is a good perioperative echocardiographic result predictive of durability in ischemic mitral valve repair?

Chronic ischemic mitral regurgitation is associated with poor long-term survival. Despite the increasing popularity of valve repair, its durability and long-term outcome for ischemic mitral regurgitation have recently been questioned. Seventy-eight patients underwent repair for ischemic mitral regurgitation between 1996 and 2002 at our institution. Of these patients, 73 had complete clinical and echocardiographic follow-up. Preoperative, intraoperative, and postoperative clinical data were obtained, and the results of echocardiograms were reviewed to assess the rate of recurrence of regurgitation after repair and to identify predictive factors. The mean preoperative mitral regurgitation grade, New York Heart Association class, and left ventricular ejection fraction were 2.72, 2.65, and 39.4%, respectively. Mortality was 12.3% at 30 days and 30.1% at a mean follow-up of 39 +/- 25 months. Immediate postoperative echocardiography showed absent or mild mitral regurgitation in 89.4% of patients and showed moderate mitral regurgitation in 10.6%. Freedom from reoperation was 93.2%. Recurrent moderate mitral regurgitation (2+) was present in 36.7% of patients, and severe mitral regurgitation (3+ to 4+) was present in 20.0% at mean follow-up of 28.1 +/- 22.5 months. Only age (P = .0130) and less marked preoperative posterior tethering (P = .0362) were predictive of recurrent mitral regurgitation. Patients with a preoperative New York Heart Association class greater than II and recurrent mitral regurgitation greater than 2+ had decreased survival (P = .0152 and P = .0450, respectively). Significant recurrent mitral regurgitation occurs following repair for ischemic mitral regurgitation, despite good early results. This finding raises questions about the need for improved repair techniques, better patient selection, or eventual mitral valve replacement in selected patients.

プロペラ補修技術の歩み

Since the advent of the first screw propeller in the mid part of the 18th century continued advances have been made in their design and manufacture rigth up to the present time, and now with the need for fuel efficient ships both shipowners & shipbuilders have demanded more efficient propeller design using the most advanced technology in their production.During the life of a ship the propeller can suffer mechanical damage and the use of special alloys in their manufacture has resulted in the need for greatly improved repair techniques. The highest quality propeller repair and reconditioning work can only be carried out under strictly controlled conditions with the full cooperation of all persons concerned.This paper introduces a suitable repair procedure and emphasises the need to adhere to the rules and guides if a reliable repair is to be satisfactorily carried out.