Repair Construct Research Articles

Repair of the Ankle Syndesmosis

Objectives:Significant debate exists regarding the optimal repair techniques for unstable syndesmosis injuries. Techniques range from one to multiple screw fixation, suture-button fixation devices, or a combination of the two. The purpose of the current investigation was to biomechanically compare three common syndesmotic repair techniques using a simulated weight-bearing protocol with internal and external rotation of the foot.Methods:Twenty-four, lower leg specimens with mean age 54.25 years (range, 38 to 68 years) were utilized for testing. Following the creation of a complete syndesmotic injury (AITFL, ITFL, PITFL, interosseous membrane) specimens were repaired using one of three randomly assigned repair techniques: (1) one 3.5 mm syndesmotic screw, (2) one suture-button construct, and (3) two divergent suture-button constructs. For testing, specimens were oriented in neutral plantar/dorsiflexion and neutral internal/external rotation with the respect to the vertical tibia. Repairs were then cycled for 500 cycles between 7.5 Nm of internal/external rotation torque under a constant 750 N axial compressive load. At 0, 10, 100, and 500 cycles, torsional cyclic loading was interrupted to assess torsional stiffness and resistance to rotation within a physiologic range of motion. While axially loaded to 750 N, the foot was externally rotated to 15° and then rotated to 10° of internal rotation. Torsional cyclic loading was then resumed. Torque (Nm) and rotational position (degrees) were recorded continuously throughout testing. Three-dimensional data was also collected throughout testing to characterize the relative spatial relationships of the tibiofibular articulation.Results:Biomechanically, there were no significant differences between techniques when repairs were compared to the intact syndesmosis. Three-dimensional analysis revealed significant differences between all repair techniques for sagittal fibular translation with external rotation of the foot. Screw fixation had the smallest magnitude in sagittal translation (-2.5 mm), and a single suture-button construct demonstrated the largest magnitude of sagittal translation (-4.6 mm). Screw fixation also allowed for significantly lower sagittal translation with internal rotation of the foot (0.1 mm) when compared to both one (2.7 mm) and two (2.9 mm) suture-button repair constructs.Conclusion:All repairs provided a significant resistance to internal and external rotation, and only demonstrated mild reductions in strength and torsional stiffness throughout torsional cyclic testing.

Biomechanics Versus Biology: The Effect of Rotator Cuff Repair Constructs on Healing and Outcomes

Innovation in rotator cuff repair technique has driven our understanding of the biomechanical attributes necessary for optimizing tendon-bone healing. Despite these advances, rotator cuff repair failure and retear rates still remain high. With the evolution of arthroscopic technique and instrumentation, transosseous, single-row, double-row, and transosseous-equivalent repair configurations have all been shown to be effective clinically. Biomechanical studies have identified significant strengths and weaknesses when comparing current repair configurations. Limitations do exist when extrapolating laboratory data and correlating clinically. The biological milieu at the tendon-bone interface and patient-specific factors out of the surgeon’s control can determine the successful healing of a rotator cuff repair. Ultimately, the goals of rotator cuff repair include identifying the superior construct to provide the biomechanical environment to optimize biological healing within the constraints of the underlying pathology.

A Synthetic Thermosensitive Hydrogel for Cartilage Bioprinting and Its Biofunctionalization with Polysaccharides.

Hydrogels based on triblock copolymers of polyethylene glycol and partially methacrylated poly[N-(2-hydroxypropyl) methacrylamide mono/dilactate] make up an attractive class of biomaterials because of their biodegradability, cytocompatibility, and tunable thermoresponsive and mechanical properties. If these properties are fine-tuned, the hydrogels can be three-dimensionally bioprinted, to generate, for instance, constructs for cartilage repair. This study investigated whether hydrogels based on the polymer mentioned above with a 10% degree of methacrylation (M10P10) support cartilage formation by chondrocytes and whether the incorporation of methacrylated chondroitin sulfate (CSMA) or methacrylated hyaluronic acid (HAMA) can improve the mechanical properties, long-term stability, and printability. Chondrocyte-laden M10P10 hydrogels were cultured for 42 days to evaluate chondrogenesis. M10P10 hydrogels with or without polysaccharides were evaluated for their mechanical properties (before and after UV photo-cross-linking), degradation kinetics, and printability. Extensive cartilage matrix production occurred in M10P10 hydrogels, highlighting their potential for cartilage repair strategies. The incorporation of polysaccharides increased the storage modulus of polymer mixtures and decreased the degradation kinetics in cross-linked hydrogels. Addition of HAMA to M10P10 hydrogels improved printability and resulted in three-dimensional constructs with excellent cell viability. Hence, this novel combination of M10P10 with HAMA forms an interesting class of hydrogels for cartilage bioprinting.

Fragmented adverbial clauses as resources for negotiating alignment: concessive repair patterns in French talk-in-interaction

The study presented in this paper aims at investigating the French adverbial conjunction mais ‘but’/‘although’ by means of a recently compiled corpus of World French. The study will describe and analyze two types of turn-final mais used in concessive repair constructions which have not been described in research on French syntax so far. These two uses of concessive mais exhibit subtle differences in their syntactic make-up but also in their sequential behavior in interaction (other-initiated down-toning of an overstatement vs. self-initiated down-toning of the relevance of an argument). Both the constructional and the sequential characteristics of the two patterns with turn-final mais will be discussed against the backdrop of a cross-linguistic comparison with English but and Finnish mutta ‘but’, with regard to similarities and differences between the uses of this lexical item in different languages. Both the analysis of French mais and its comparison with its English and Finnish counterparts support the conclusion that fragmented adverbial clauses can be used as resources for negotiating alignment in talk-in-interaction.

Paper #9 - Posterior shoulder instability in throwing athletes: a case-matched comparison of throwers and non-throwers

Introduction: The purpose of this study was to evaluate the results of arthroscopic capsulolabral repair for the treatment of posterior shoulder instability in a throwing athlete cohort when compared to non-throwers. Methods and Materials: Forty-eight overhead throwing athletes undergoing arthroscopic posterior capsulolabral reconstruction were case matched with 48 non-throwing athletes. These cohorts were followed as they underwent posterior capsulolabral reconstruction by measuring shoulder pain, function, return to sport, and operative failures. Operative details such as intra-articular pathology and repair construct were also recorded. Results: At a mean follow up of 37 (range 12-97) months post-operatively, no statistical differences were noted between throwers and non-throwers regarding ASES scores, stability, strength, or range of motion between throwers and non-throwers. Sixty percent of throwing athletes were able to return to their pre-injury level of competitive throwing. Throwers with a discreet labral tear intra-operatively had a 10-fold increased likelihood to return to sport (OR 9.6, p = .012). Similarly, throwers that had suture anchors constructs showed a 10-fold increased likelihood of return to play compared to anchor-less repairs (OR 9.6, p = .012). Non-throwers showed no variability by labral findings or fixation techniques. Pitchers had equivocal outcomes scores when compared to other throwers, but had poorer return to play rates (50% versus 60% full return, respectively). Conclusions: Arthroscopic capsulolabral plication for unidirectional posterior shoulder instability is an effective treatment for overhead throwing athletes. Intra-operatively, achieving an adequate capsular plication and stabilizing the repair via suture anchors will give this athletic population the best odds at returning to competitive sports. Significance: Comparison study; Level of evidence, 3. This is the first study directly comparing outcomes of posterior shoulder instability managed with arthroscopic stabilization between throwing and non-throwing athletes. It is also the largest series focusing on throwing athletes reported to date.

Biomechanical evaluation of the simple cinch stitch for arthroscopic rotator cuff repair

BackgroundThe tissue-suture interface is described as the most vulnerable and susceptible area in the muscle–tendon–bone construction of arthroscopic rotator cuff repair. Various stitching techniques have been described to enhance the strength, fixation and stability of the repair, but technical and biomechanical challenges remain.Purpose was to examine the biomechanical properties of the simple cinch stitch in comparison to other stitches commonly used for rotator cuff repair. MethodsInfraspinatus tendons were harvested from sheep and split in half. The tendons were randomized into five different stitch configuration groups for biomechanical testing: simple stitch; horizontal stitch; FiberChain®; simple cinch stitch; and modified Mason-Allen stitch. Each specimen was first cyclically loaded on a universal materials testing machine under force control from 5 to 30N at 0.25Hz for twenty cycles. Then, each specimen was loaded to failure under displacement control at a rate of 1mm/s. Cyclic elongation, peak-to-peak displacement and ultimate tensile load were measured. The type of failure was recorded. FindingsNo differences in cyclic elongation or peak-to-peak displacement were seen between stitch configurations. In the load-to-failure test, the simple cinch stitch demonstrated significantly higher ultimate load than the simple and the horizontal stitch configurations. The comparison to the FiberChain® Suture revealed no statistical significant differences.The FiberChain® Suture demonstrated significantly higher ultimate load than the simple stitch. No statistical significance could be demonstrated in comparison to the horizontal stitch or the simple cinch stitch.The ultimate tensile load of the modified Mason-Allen stitch was significantly higher than that of the other stitch configurations. InterpretationThe simple cinch stitch has an ultimate tensile load comparable to the FiberChain® suture and is superior to the simple stitch and the horizontal stitch. The major advantage of the simple cinch technique is that it is possible to perform the stitch entirely arthroscopically, without the need to perforate the tissue a second time or to use special suture materials. Study designControlled laboratory study.

Fresh and Frozen Tissue-Engineered Three-Dimensional Bone-Ligament-Bone Constructs for Sheep Anterior Cruciate Ligament Repair Following a 2-Year Implantation.

Injuries to the anterior cruciate ligament (ACL) often require surgical reconstruction utilizing tendon grafts to restore knee function and stability. Some current graft options for ACL repair are associated with poor long-term outcomes. Our laboratory has fabricated tissue-engineered bone–ligament–bone (BLB) constructs that demonstrate native ligament regeneration and advancement toward native ACL mechanical properties in a sheep ACL reconstruction model. Prior work has shown that freezing BLBs as a method of preservation resulted in similar outcomes compared with fresh BLBs after 6-month implantation. The purpose of this study was to evaluate the long-term efficacy of fresh and frozen BLBs. We hypothesized that both fresh and frozen BLBs would show continued regeneration of structural and functional properties toward those of native ACL after a 2-year implantation. Following removal of the native ACL, fresh (n = 2) and frozen (n = 2) BLBs were implanted arthroscopically. After 2 years of recovery, sheep were euthanized and both the experimental and contralateral hindlimbs were removed and radiographs were performed. Explanted knees were initially evaluated for joint laxity and were then further dissected for uniaxial tensile testing of the isolated ACL or BLB. Following mechanical testing, explanted contralateral ACL (C-ACL) and BLBs were harvested for histology. Two years post-ACL reconstruction, fresh and frozen BLBs exhibited similar morphological and biomechanical properties as well as more advanced regeneration compared with our 6-month recovery study. These data indicate that an additional 1.5-year regeneration period allows the BLB to continue ligament regeneration in vivo. In addition, freezing the BLBs is a viable option for the preservation of the graft after fabrication.

The effect of acoustic radiation force on osteoblasts in cell/hydrogel constructs for bone repair.

Ultrasound, or the application of acoustic energy, is a minimally invasive technique that has been used in diagnostic, surgical, imaging, and therapeutic applications. Low-intensity pulsed ultrasound (LIPUS) has been used to accelerate bone fracture repair and to heal non-union defects. While shown to be effective the precise mechanism behind its utility is still poorly understood. In this study, we considered the possibility that LIPUS may be providing a physical stimulus to cells within bony defects. We have also evaluated ultrasound as a means of producing a transdermal physical force that could stimulate osteoblasts that had been encapsulated within collagen hydrogels and delivered to bony defects. Here we show that ultrasound does indeed produce a measurable physical force and when applied to hydrogels causes their deformation, more so as ultrasound intensity was increased or hydrogel stiffness decreased. MC3T3 mouse osteoblast cells were then encapsulated within hydrogels to measure the response to this force. Statistically significant elevated gene expression for alkaline phosphatase and osteocalcin, both well-established markers of osteoblast differentiation, was noted in encapsulated osteoblasts (p < 0.05), suggesting that the physical force provided by ultrasound may induce bone formation in part through physically stimulating cells. We have also shown that this osteoblastic response is dependent in part on the stiffness of the encapsulating hydrogel, as stiffer hydrogels resulted in reducing or reversing this response. Taken together this approach, encapsulating cells for implantation into a bony defect that can potentially be transdermally loaded using ultrasound presents a novel regenerative engineering approach to enhanced fracture repair.

사례 데이터 분석을 통한 공동주택 계획수선 주요 항목 도출: 법령 상의 장기수선계획 수립기준 현실화를 중심으로

장기수선계획은 공동주택 수선공사의 시행 기준으로서 장기수선충당금의 적립과 예방보전을 통한 효과적인 시설물관리의 기반을 제공하는 것이며 정부에서는 장기수선계획의 중요성을 감안하여 공동주택의 장기수선공사를 위한 대상항목과 수선주기, 수선율을 법으로 정하고 있다. 그러나 수립기준에 포함된 수선공사의 항목이 최근의 공법 등을 반영하여 적기에 개정되지 못함에 따라 실제 아파트 단지에서 장기수선계획의 빈번한 변경, 수선공사를 둘러싼 논란, 충당금 사용 상의 어려움을 가져오고 있다. 이러한 문제를 해결하기 위해서는 실태분석을 통해 계획수선 항목의 적정성을 평가하여 수립기준을 조정하는 것이 요구된다. 본 연구에서는 장기수선계획과 수선공사 데이터를 통해 파악할 수 있는 현황을 바탕으로 주요 수선항목을 도출하고 수립기준을 조정하는 방안을 제안함으로써 장기수선계획의 운영을 담당하는 관리주체의 부담을 저감함과 동시에 적정수준의 수선충당금 적립을 유도하여 건물 내구연한의 연장과 수선공사 실질화를 위한 방안을 제안하고자 하였다. 이를 위해 광범위하게 장기수선계획 사례를 수집하여 계획에의 항목 채택률을 검토하고, 장기수선충당금 사용내역과 관리비 상의 수선유지비 내역을 분석하였다. 주요 항목을 도출함에 있어서는 보수적인 방식으로서 불필요한 항목만을 최소한으로 삭제하는 배제방식과 각 항목의 계획 반영률이 일정 수준 이상이면서 공사내역이 있는 항목만을 가려내는 선택방식 등 두 가지 방식으로 접근하였다. 그 결과 현재의 147개 항목 중 118개와 73개 항목이 배제방식과 선택방식을 통해 각각 주요 항목으로 정리되었다. 장기수선계획 수립을 위한 법적기준은 실제 적용되는 공법과 재료의 현황을 주기적으로 반영하는 것이 필요하다는 점에서 본 연구의 결과는 기준의 실용성 제고에 기여할 것으로 기대된다. The long-term repair program is significant as the execution standard for apartment in repair construction, and provides the basis for effective facility management through appropriation reserve and preventive maintenance. Considering its importance, the government legislates the items, cycle, and ratio for long-term repair. However, the frequent changes, controversies on repair, and difficulties in using appropriation reserve are caused as the items have not been revised on time reflecting up-to-date construction technologies. In order to resolve these problems, it is required to improve the standard by evaluating the appropriateness of repair items throughout the analysis of actual conditions. This study aims to suggest the revision plan for the criteria with the major items based on the status identified by the actual long-term repair programs and historical repair construction data. To do this, the adoption ratios of items to program are reviewed by collecting the real cases of the long-term repair programs. Developing improvement plan was approached in two ways such as "exclusion method" deleting minimum unnecessary items and "selection method" sorting out items with high adoption ratio and evidence of repair in a positive manner. Aa a result, the major items were identified as 118 items and 73 items by exclusion method and selection method respectively from the current 147 items. The outcomes of this study are expected to contribute enhancing the practicality of the standard in that the regulation for long-term repair program should periodically reflect the status of currently applied construction methods and materials.

Biomechanical Comparison of Parallel and Crossed Suture Repair for Longitudinal Meniscus Tears.

Background:Longitudinal meniscus tears are commonly encountered in clinical practice. Meniscus repair devices have been previously tested and presented; however, prior studies have not evaluated repair construct designs head to head. This study compared a new-generation meniscus repair device, SpeedCinch, with a similar established device, Fast-Fix 360, and a parallel repair construct to a crossed construct. Both devices utilize self-adjusting No. 2-0 ultra–high molecular weight polyethylene (UHMWPE) and 2 polyether ether ketone (PEEK) anchors.Hypothesis:Crossed suture repair constructs have higher failure loads and stiffness compared with simple parallel constructs. The newer repair device would exhibit similar performance to an established device.Study Design:Controlled laboratory study.Methods:Sutures were placed in an open fashion into the body and posterior horn regions of the medial and lateral menisci in 16 cadaveric knees. Evaluation of 2 repair devices and 2 repair constructs created 4 groups: 2 parallel vertical sutures created with the Fast-Fix 360 (2PFF), 2 crossed vertical sutures created with the Fast-Fix 360 (2XFF), 2 parallel vertical sutures created with the SpeedCinch (2PSC), and 2 crossed vertical sutures created with the SpeedCinch (2XSC). After open placement of the repair construct, each meniscus was explanted and tested to failure on a uniaxial material testing machine. All data were checked for normality of distribution, and 1-way analysis of variance by ranks was chosen to evaluate for statistical significance of maximum failure load and stiffness between groups. Statistical significance was defined as P < .05.Results:The mean maximum failure loads ± 95% CI (range) were 89.6 ± 16.3 N (125.7-47.8 N) (2PFF), 72.1 ± 11.7 N (103.4-47.6 N) (2XFF), 71.9 ± 15.5 N (109.4-41.3 N) (2PSC), and 79.5 ± 25.4 N (119.1-30.9 N) (2XSC). Interconstruct comparison revealed no statistical difference between all 4 constructs regarding maximum failure loads (P = .49). Stiffness values were also similar, with no statistical difference on comparison (P = .28).Conclusion:Both devices in the current study had similar failure load and stiffness when 2 vertical or 2 crossed sutures were tested in cadaveric human menisci.Clinical Relevance:Simple parallel vertical sutures perform similarly to crossed suture patterns at the time of implantation.

Biomechanical Test for Repair Technique of Full-thickness Rotator Cuff Tear

The arthroscopic rotator cuff repair is now considered a mainstream technique with highly satisfactory clinical results. However, concerns remain regarding healing failures for large and massive tears and high revision rate. In recent decades, various repair strategies and construct configurations have been developed for rotator cuff repair with the understanding that many factors contribute to the structural integrity of the repaired construct. The focus of biomechanical test in arthroscopic repair has been on increasing fixation strength and restoration of the footprint contact characteristics to provide early rehabilitation and improve healing. These include repaired rotator cuff tendon-footprint motion, increased tendon-footprint contact area and pressure, and tissue quality of tendon and bone. Recent studies have shown that a transosseous tunnel technique provides improved contact area and pressure between rotator cuff tendon and insertion footprint, and the technique of using double rows of suture anchors to recreate the native footprint attachment has been recently described. The transosseous equivalent suture bridge technique has the highest contact pressure and fixation force. In this review, the biomechanical tests about repair techniques of rotator cuff tear will be reviewed and discussed.

Large/Massive Tears, Fatty Infiltration, and Rotator Cuff Muscle Atrophy: A Review Article With Management Options Specific to These Types of Cuff Deficiencies

Context: There are many studies in the literature looking into factors affecting outcomes in rotator cuff surgery. The aetiology of rotator cuff deficiency is often multi-factorial and there are many facets towards successful management in this often debilitating condition. Evidence Acquisition: We performed a literature search of MEDLINE and Embase databases using the terms large rotator cuff tears, fatty infiltration rotator cuff, rotator cuff atrophy, rotator cuff augmentation, rotator cuff tendon transfers, allografts rotator cuff repair, xenograft rotator cuff repair and synthetic grafts rotator cuff repair. Results: In this article, we focus particularly on the aetiology, pathology and prognosis of large tears, fatty infiltration and muscle atrophy of the rotator cuff. An overview of the various treatment strategies and current/future concepts are also discussed in managing patients with these types of rotator cuff deficiencies. Conclusions: Large tears, fatty infiltration and muscle atrophy of the cuff are challenging. An in-depth understanding of these elements may prove vital for the practising orthopedician in determining the right course of management. Techniques in strengthening the repair construct using augmentation play an important role in the treatment of this condition.

Establishment of Genome-edited Human Pluripotent Stem Cell Lines: From Targeting to Isolation.

Genome-editing of human pluripotent stem cells (hPSCs) provides a genetically controlled and clinically relevant platform from which to understand human development and investigate the pathophysiology of disease. By employing site-specific nucleases (SSNs) for genome editing, the rapid derivation of new hPSC lines harboring specific genetic alterations in an otherwise isogenic setting becomes possible. Zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 are the most commonly used SSNs. All of these nucleases function by introducing a double stranded DNA break at a specified site, thereby promoting precise gene editing at a genomic locus. SSN-meditated genome editing exploits two of the cell's endogenous DNA repair mechanisms, non-homologous end joining (NHEJ) and homology directed repair (HDR), to either introduce insertion/deletion mutations or alter the genome using a homologous repair template at the site of the double stranded break. Electroporation of hPSCs is an efficient means of transfecting SSNs and repair templates that incorporate transgenes such as fluorescent reporters and antibiotic resistance cassettes. After electroporation, it is possible to isolate only those hPSCs that incorporated the repair construct by selecting for antibiotic resistance. Mechanically separating hPSC colonies and confirming proper integration at the target site through genotyping allows for the isolation of correctly targeted and genetically homogeneous cell lines. The validity of this protocol is demonstrated here by using all three SSN platforms to incorporate EGFP and a puromycin resistance construct into the AAVS1 safe harbor locus in human pluripotent stem cells.

Establishment of Genome-edited Human Pluripotent Stem Cell Lines: From Targeting to Isolation

Genome-editing of human pluripotent stem cells (hPSCs) provides a genetically controlled and clinically relevant platform from which to understand human development and investigate the pathophysiology of disease. By employing site-specific nucleases (SSNs) for genome editing, the rapid derivation of new hPSC lines harboring specific genetic alterations in an otherwise isogenic setting becomes possible. Zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 are the most commonly used SSNs. All of these nucleases function by introducing a double stranded DNA break at a specified site, thereby promoting precise gene editing at a genomic locus. SSN-meditated genome editing exploits two of the cell's endogenous DNA repair mechanisms, non-homologous end joining (NHEJ) and homology directed repair (HDR), to either introduce insertion/deletion mutations or alter the genome using a homologous repair template at the site of the double stranded break. Electroporation of hPSCs is an efficient means of transfecting SSNs and repair templates that incorporate transgenes such as fluorescent reporters and antibiotic resistance cassettes. After electroporation, it is possible to isolate only those hPSCs that incorporated the repair construct by selecting for antibiotic resistance. Mechanically separating hPSC colonies and confirming proper integration at the target site through genotyping allows for the isolation of correctly targeted and genetically homogeneous cell lines. The validity of this protocol is demonstrated here by using all three SSN platforms to incorporate EGFP and a puromycin resistance construct into the AAVS1 safe harbor locus in human pluripotent stem cells.

Triple-Loaded Single-Row Versus Suture-Bridge Double-Row Rotator Cuff Tendon Repair With Platelet-Rich Plasma Fibrin Membrane: A Randomized Controlled Trial

To compare the structural healing and clinical outcomes of triple-loaded single-row with suture-bridging double-row repairs of full-thickness rotator cuff tendons when both repair constructs are augmented with platelet-rich plasma fibrin membrane. A prospective, randomized, consecutive series of patients diagnosed with full-thickness rotator cuff tears no greater than 3cm in anteroposterior length were treated with a triple-loaded single-row (20) or suture-bridging double-row (20) repair augmented with platelet-rich plasma fibrin membrane. Theprimary outcome measure was cuff integrity by magnetic resonance imaging (MRI) at 12months postoperatively. Secondary clinical outcome measures were American Shoulder and Elbow Surgeons, Rowe, Simple Shoulder Test, Constant, and Single Assessment Numeric Evaluation scores. The mean MRI interval was 12.6months (range, 12-17months). A total of 3 of 20 single-row repairs and 3 of 20 double-row repairs (15%) had tears at follow-up MRI. The single-row group had re-tears in 1 single tendon repair and 2 double tendon repairs. All 3 tears failed at the original attachment site (Cho type 1). In the double-row group, re-tears were found in 3 double tendon repairs. All 3 tears failed medial to the medial row near the musculotendinous junction (Cho type 2). All clinical outcome measures were significantly improved from the preoperative level (P < .0001), but there was no statistical difference between groups postoperatively. There is no MRI difference in rotator cuff tendon re-tear rate at 12months postsurgery between a triple-loaded single-row repair or a suture-bridging double-row repair when both are augmented with platelet-rich plasma fibrin membrane. No difference could be demonstrated between these repairs on clinical outcome scores. I, Prospective randomized study.

Regional biomechanical and histological characterization of the mitral valve apparatus: Implications for mitral repair strategies

The aim of this study was to investigate the regional and directional differences in the biomechanics and histoarchitecture of the porcine mitral valve (MV) apparatus, with a view to tailoring tissue-engineered constructs for MV repair. The anterior leaflet displayed the largest directional anisotropy with significantly higher strength in the circumferential direction compared to the posterior leaflet. The histological results indicated that this was due to the circumferential alignment of the collagen fibers. The posterior leaflet demonstrated no significant directional anisotropy in the mechanical properties, and there was no significant directionality of the collagen fibers in the main body of the leaflet. The thinner commissural chordae were found to be significantly stiffer and less extensible than the strut chordae. Histological staining demonstrated a tighter knit of the collagen fibers in the commissural chordae than the strut chordae. By elucidating the inhomogeneity of the histoarchitecture and biomechanics of the MV apparatus, the results from this study will aid the regional differentiation of MV repair strategies, with tailored mitral-component-specific biomaterials or tissue-engineered constructs.

Medial Meniscal Root Avulsion: A Biomechanical Comparison of 4 Different Repair Constructs

To evaluate the time-zero load-to-failure strength of 4 different constructs used to repair medial meniscal root avulsions. Sixty fresh-frozen cadaveric knees with a mean age of 74 years were used for this study. Each knee was dissected to isolate the attachment of the posterior root of the medial meniscus to the tibial plateau. An Instron machine (Instron, Norwood, MA) with a custom-designed clamp was used to avulse the intact posterior meniscal root in 12 control specimens. An additional 48 specimens were tested after transection of the native meniscal root to evaluate the pullout strength of 4 different repair constructs using No. 0 FiberWire suture (Arthrex, Naples, FL): a single suture (n= 12), a double suture (n= 12), a loop stitch (n= 12), and a locking loop stitch (n= 12). Analysis of variance was used to compare load to failure and stiffness of all 4 groups; pair-wise, between-group differences were also assessed. Repair failure occurred most commonly by suture pullout in 94% of the specimens in the repair groups. For the controls, failure occurred most commonly at the meniscus-clamp interface. Failure load was highest for the control group (mean, 359.5 ± 168 N), followed in descending order by the locking loop stitch (191.4 ± 45.1 N), loop stitch (119.6 ± 55.0 N), double suture (96.2 ± 51.4 N), and single suture (58.2 ± 29.6 N). The control group was significantly stronger than 3 of the experimental groups (single suture [95% CI, 3.8 to 11.3], double suture [95% CI, 2.1 to 6.4], and loop stitch [95% CI, 2.0 to 4.5]; P < .0001) but not the locking loop stitch (P= .003; 95% CI, 1.2 to 3.2). The locking loop stitch was significantly stronger than the single suture (P< .0001; 95% CI, 2.0 to 5.4) and double suture (P= .003; 95% CI, 1.2 to 2.9). The locking loop stitch was significantly stiffer than the single suture (P < .0001; 95% CI, 3.8 to 20.3), double suture (P < .0001; 95% CI, 2.0 to 9.8), and loop stitch (P= .03; 95% CI, 1.1 to 5.5) but not significantly different from the control group (P= .93; 95% CI, 0.3 to 1.9). Age and gender had no effect on pullout strength. The results of this study show that the locking loop stitch provided time-zero load-to-failure strength that most closely approximated the strength of the native meniscal root in addition to being significantly stronger and stiffer than 3 other commonly used repair methods. The true strength of the native meniscal root is unknown based on limitations with our testing methodology. The locking loop stitch exhibited the highest load to failure and stiffness of the 4 fixation methods tested, despite the fact that none of the fixation methods replicated the strength of the intact meniscal root. It is currently unknown what strength of fixation is required for healing of meniscal root repairs.

Member design and strength characteristics of the MMA mortar composites (I)

The repair of manhole raise has been caused much construction times and disruption of traffic flow, serious environmental pollution from crushed construction wastes, and budget waste due to the repeated repair construction works. In order to overcome such problems, we have developed the new manhole repairing composite structures by using a glass fiber-reinforced polymer (GFRP) pipe, which can raise manhole to the regular height of the overlayed road pavement with rapid construction and minimum traffic jams. This environmental-friendly technology is method completed by the methyl methacrylate monomer (MMA) double wide flanged GFRP pipe composite structures in order to raise manhole to the regular height. In this paper, two kinds of the compressive strength tests of MMA mortar composites were conducted and evaluated by a general compressive strength test, and compressive strength test after freezing-thawing resistance test. It was found that this MMA mortar composites will be used for the application of the double wide flanged GFRP pipe composite structures.

Structural Failure Mechanisms of Common Flexor Tendon Repairs.

This study investigated the exact failure mechanisms of the most commonly used conventional tendon repair techniques. A new method, radiographing repair constructs in antero-posterior and lateral projections before and after tensioning was used. This allowed to precisely analyse failure mechanisms in regards to geometrical changes in all three dimensions. Additionally the biomechanical stability focusing on gapping was tested. Sheep fore limb deep flexor tendons were harvested and divided in eight groups of ten tendons. Three common variants of the Kessler repair method and four common 4-strand repair techniques were tested. Additionally a new modification of the Adelaide repair was tested. Biomechanical testing showed no significant differences in gapping for the three tested 2-strand Kessler repair groups. Once a double Kessler or 4-strand Kessler repair was performed the stability of the repair improved significantly. Further significant improvements in biomechanical stability could be achieved by using cross locks in the repair like in the Adelaide repair method. Qualitative analysis using radiographs showed that all Kessler repair variants unfolded via rotations around the transverse suturing component, no matter which variant was used. Additional to the commonly described constriction of the repair construct, the rotating deformation is the main reason for repair site gapping in Kessler tendon repair methods. The term "locking" in a Kessler repair is misleading. The cruciate repairs tended to loose grip and drag (cheese-wire) through the tendon and therefore lead to gapping. The most stable repair constructs in all three dimensions were the Adelaide repair and its interlocking modification. This is due to the superior anchoring qualities of its cross locks and three dimensional stability.

コンクリート改修施工技術「外壁複合改修工法」の調査研究

コンクリート改修施工技術「外壁複合改修工法」の調査研究