Study on reconstruction of the anterior cruciate ligament in the monkey knee using polyester artificial ligament]

We performed an experimental study of ACL reconstruction utilizing polyester artificial ligament(Leeds-Keio). The quality of regenerated ligaments was compared between two different procedures; in the one 1 cm wide Leeds-Keio ligament was used alone for reconstruction(Group 1) and in the other, Leeds-Keio ligament of the same size was augmented with one-third width of free patellar tendon (Group 2). Eighteen knees of nine Japanese monkeys were used. The specimens were obtained at 2, 6 and 12 months after the operation and investigated macroscopically, microscopically and biomechanically. Regenerated ligaments in Groups 1 and 2 appeared identical and grossly normal. However, more mature and stable ligament was noted in the cylinder of artificial ligaments after 2 months after operation in Group 2 than in Group 1 in terms of both quality and quantity. Biomechanically, however, the maximum the tension in the regenerated ligaments was approximately 1/2-1/3 of that of normal ACL. The authors believe that more mature ligament was made in ACL reconstruction when the artificial ligament was augmented with autogenous soft tissue.     

Increase in cell migration and angiogenesis in a composite silk scaffold for tissue‐engineered ligaments

The purpose of this study was to evaluate the biocompatibility of silk and collagen‐hyaluronan (HA) in vitro by assessing anterior cruciate ligament (ACL) cell and T‐lymphocyte cultures on scaffolds. The use of composite scaffolds as artificial ligaments in ACL reconstruction and their effects on angiogenesis were evaluated in vivo. The silk scaffold was knitted by hand and dry coated with collagen‐HA, whereas the composite silk scaffold was made by covering a silk scaffold with a lyophilized collagen‐HA substrate. The initial attachment and proliferation of human ACL cells on the composite silk scaffold was superior to the attachment and proliferation observed on the silk scaffold. The immune response was higher in both scaffolds after 72 h (p < 0.05) compared with the control culture condition without scaffolding, as assessed by T‐lymphocyte cultures in vitro. There was no significant difference in the immune response in vitro between the silk and composite silk scaffolds. Silk and composite silk scaffolds were implanted as artificial ligaments in ACLs removed from the knees of dogs, and they were harvested 6 weeks after implantation. On gross examination, the onset of an inflammatory tissue reaction, such as synovitis, was seen in both the silk scaffold and the composite silk scaffold groups. An histological evaluation of the artificial ligament implants revealed the presence of monocytes in the silk composite scaffold and the absence of giant cells in all cases. MT staining in the composite silk scaffold‐grafted group showed granulation tissue consisting of fibroblasts, lymphocytes, monocytes, and collagen fibers. In addition, CD31 staining revealed the formation of new blood vessels. On the other hand, no reparative tissues, such as blood vessels, collagen, and cells, were observed in the silk scaffold‐grafted group. These results suggest that the lyophilized collagen‐HA substrate is biocompatible in vitro and enhances new blood vessel and cell migration in vivo. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 495–503, 2009     

Biological and Biomechanical Evaluation of Autologous Tendon Combined with Ligament Advanced Reinforcement System Artificial Ligament in a Rabbit Model of Anterior Cruciate Ligament Reconstruction

Objective

To compare the biomechanical and histological changes in a rabbit model after reconstructing the anterior cruciate ligament (ACL) with solely autologous tendon and with autologous tendon combined with the ligament advanced reinforcement system (LARS) artificial ligament.

Methods

Anterior cruciate ligament reconstruction was performed in 72 knees from 36 healthy New Zealand white rabbits (bodyweight, 2500–3000 g). The Achilles tendons were harvested bilaterally. The left ACL were reconstructed solely with autografts (autologous tendon group), while the right ACL were reconstructed with autografts combined with LARS ligaments (combined ligaments group). The gross observation, histological determination, and the tension failure loads in both groups were evaluated at 12 weeks (n = 18) and 24 weeks (n = 18) postoperatively.

Results

Gross examination of the knee joints showed that all combined ligaments were obviously covered by a connective tissue layer at 12 weeks, and were completely covered at 24 weeks. Fibrous tissue ingrowth was observed between fascicles and individual fibers in the bone–artificial ligament interface at both time points; this fibrovascular tissue layer localized at the bone–artificial ligament interface tended to be denser in specimens obtained at 24 weeks compared with those obtained at 12 weeks. The tension failure loads of the knees were similar in the autologous tendon group and the combined ligaments group at 12 weeks (144.15 ± 3.92 N vs. 140.88 ± 2.75 N; P > 0.05), and at 24 weeks (184.15 ± 1.96 N vs. 180.88 ± 3.21 N; P > 0.05).

Conclusion

Reconstructing the ACL in rabbits using autologous tendon combined with the LARS artificial ligament results in satisfactory biointegration, with no obvious immunological rejection between the autologous tendon and the artificial ligament, and is, therefore, a promising ACL reconstruction method.

     

Enhanced Fibroblast Cellular Ligamentization Process to Polyethylene Terepthalate Artificial Ligament by Silk Fibroin Coating

Artificial ligaments utilized in reconstruction of anterior cruciate ligament (ACL) are usually made of polyethylene terepthalate (PET) because of its good mechanical properties in vivo. However, it was found that the deficiencies in hydrophilicity and biocompatibility of PET hindered the process of ligamentization. Therefore, surface modification of the PET is deemed as a solution in resolving such problem. Silk fibroin (SF), which is characterized by good biocompatibility and low immunogenicity in clinical applications, was utilized to prepare a coating on the PET ligament (PET+SF) in this work. At first, decrease of hydrophobicity and appearance of amino groups were found on the surface of artificial PET ligament after coating with SF. Second, mouse fibroblasts were cultured on the two different kinds of ligament in order to clarify the possible effect of SF coating. It was proved that mouse fibroblasts display better adhesion and proliferation on PET+SF than PET ligament according to the results of several technical methods including SEM observation, cell adhesive force and spread area test, and mRNA analysis. Meanwhile, methylthiazolyldiphenyl‐tetrazolium bromide and DNA content tests showed that biocompatibility of PET+SF is better than PET ligament. In addition, collagen deposition tests also indicated that the quantity of collagen in PET+SF is higher than PET ligament. Based on these results, it can be concluded that SF coating is suggested to be an effective approach to modify the surface of PET ligament and enhance the “ligamentization” process in vivo accordingly.     

关节镜下LARS人工韧带及4股半腱肌肌腱重建前交叉韧带

目的评价LARS人工韧带和自体4股半腱肌肌腱关节镜下重建膝前交叉韧带（ACL）的临床疗效。方法对28例膝ACL断裂患者行关节镜下ACL重建术,根据重建材料的来源分为LARS人工韧带组（13例）和自体4股半腱肌肌腱组（15例）。采用ACL解剖等长重建技术建立胫骨、股骨骨道。并对两组的关节稳定性和Lysholm膝关节功能评分进行对比研究。结果术后膝关节稳定性LARS人工韧带组优于4股半腱肌肌腱组（P〈0.05）。移植后两组Lyshrolm膝关节功能评分较移植前提高（P〈0.05）。术后6个月LARS人工韧带组Lysholm评分（90.4分±5.3分）高于4股半腱肌肌腱组（81.2分±4.7分）（P〈0.05）。结论在关节镜下重建ACL术中,LARS人工韧带可作为自体材料的良好替代物。     

An experimental study on tissue induction in anterior cruciate ligament reconstruction with the scaffold-type polyester artificial ligament (Leeds-Keio)]

The effect of experimental autogenous tissue implantation (infrapatellar fat pad, fascia lata) together with scaffold type artificial ligament (Leeds-Keio) in ACL reconstruction was studied in 56 mongrel adult dogs. Specimens were examined macroscopically, histologically and by means of microangiography. The results were compared with those in which the artificial ligament was used alone. When infrapatellar fat pad was transferred on artificial ligament, tissue induction was observed 2 weeks after reconstruction. When ACL was reconstructed using a combination of artificial ligament and a small piece of fascia lata, maturated dense collagen fibers were observed 24 weeks after reconstruction. These results indicated that quicker tissue induction could be obtained in ACL reconstruction using an artificial ligament together with a infrapatellar fat pad, and that collagen fiber maturation was accelerated when ACL was reconstructed using an artificial ligament together with a small piece of fascia lata.     

The free synovial graft as a shield for collagen ingrowth in cruciate ligament repair

The anterior cruciate ligament (ACL) was excised bilaterally in the knee joint of three dogs and was replaced in a conventional manner with a composite polyglycolic acid (PGA) and Dacron braided ligament prosthesis. In one knee of each dog, the ligaments were wrapped with a free synovial graft taken from the suprapatellar pouch in an attempt to keep the prosthesis extrasynovial, while the ligaments in the opposite three knees were left uncovered and thus directly exposed to synovial fluid. The dogs were killed at approximately one year postoperation, and microscopic sections of all ligaments were taken. The three knees with the synovial sheath showed a significantly greater bulk of fibrous tissue along the ligament scaffold grossly and a greater abundance of collagen producing cells microscopically, compared to the unwrapped ligaments. The gross and microscopic findings were identical in each of the three knees with the covered ligaments and were equally consistent in the three that had been left unprotected from the synovial fluid. These findings suggest that a free synovial graft may simulate the normal protective role of the synovial membrane and allow and/or induce collagen ingrowth in synthetic or autogeneic tissue stints for the repair of acute cruciate ligament tears.     

关节镜下部分重建治疗膝关节前交叉韧带不完全断裂

目的 探讨前交叉韧带(ACL)不完全断裂的关节镜下诊断及镜下部分蕈建治疗的疗效和意义. 方法 2004年6月至2006年12月,经关节镜确诊ACL不完伞断裂29例,其中前内侧束断裂21例,后外侧束断裂8例.全部患者于关节镜下重建损伤部分的韧带组织,选用LARS韧带蕈建11例,自体四股腘绳肌腱移植重建18例,术中完整保留未断裂部分的切带纤维束. 结果全部患者均获随访,平均随访15个月(12～30个月),治疗康复12个月时,门诊进行统一标准膝关节功能评定,膝关节Lysholm评分手术前、后比较差异有统计学意义(P<0.05). 结论正常ACL的前内侧束和后外侧束各自有不同的功能,对于ACL不完全断裂,准确判断ACL的断裂程度十分重要.有效地重建断裂部分的ACL,能够恢复双束韧带的完整统一,更有益于良好地恢复关节功能,避免晚期并发症的发生,对恢复膝关节稳定和功能有着重要的意义.     

关节镜下一期自体腘绳肌腱重建前交叉韧带联合LARS韧带重建后交叉韧带

目的探讨关节镜下一期应用自体腘绳肌腱重建前交叉韧带联合LARS人工韧带重建后交叉韧带的临床疗效。方法自2009-02—2010-06对14例膝关节前、后交叉韧带断裂及严重膝关节脱位患者在关节镜下一期采用自体腘绳肌腱重建前交叉韧带联合LARS人工韧带重建后交叉韧带,同时处理合并的侧副韧带及半月板损伤。末次随访时采用膝关节Lysholm评分、IKDC评分评定疗效。结果术后14例均获随访23~36个月,平均29.5个月。均无膝关节肿痛症状、感染、伸膝障碍发生。末次随访时,膝关节屈曲达120°~130°;膝关节IKDC评分：A类11例（78.6%）,B类2例（14.3%）,C类1例（7.1%）;膝关节Lysholm评分（89.2±4.6）分,较术前（54.7±5.3）分明显提高,差异有统计学意义（t=32.156,P=8.91E-14）。结论关节镜下一期应用自体腘绳肌腱重建前交叉韧带联合LARS人工韧带重建后交叉韧带治疗膝关节多韧带损伤临床疗效满意。     

Mechanisms of anterior cruciate ligament neovascularization and ligamentization

Columbia-Rambouillet cross-bred sheep were used to study the revascularization and ligamentization process of anterior cruciate ligament (ACL) reconstruction over a 6-month period using basic histology, immunohistochemistry, and electron microscopy. The reconstruction technique studied was a quadruple-hamstring, interference screw fixation technique. Further, these specimens, after retrieval at 6, 12, and 26 weeks, were compared with human arthroscopic 'second looks' and with 10 en bloc specimens obtained when a cruciate- sacrificing total knee replacement was performed. The study showed that, with this reconstruction technique, Sharpey's fibers were seen at 6 weeks in both sheep and human specimens. The intratunnel specimens showed proliferative chondrification, then ossification of the matrix. Intra-articular neovascularization, ligamentization, and junction ossification occurred. Myoblasts or smooth muscle cells appear to mediate the ligamentization as evidenced in electron microscopy by proliferate collagen manufacture. These myoblasts were seen in both the healing sheep and human second looks, but not seen in mature ACL grafts or in normal ACLs. At 6 months postoperatively, the sheep ACL reconstruction appeared clinically, histologically, and immunohistochemically indistinguishable from the normal sheep ACL. A correlation of this work with published animal studies in which biomechanical testing was performed and with human 'second looks' would imply that an ACL reconstruction may be vulnerable during this period of neovascularization and ligamentization.Arthroscopy 1998 Oct;14(7):702-16     

Intraosseous incorporation of composite collagen prostheses designed for ligament reconstruction

Composite collagen prostheses are potentially useful for reconstruction of the anterior cruciate ligament (ACL). We evaluated the intraosseous response to composite collagen prostheses to determine if “biological fixation” could be used to secure the prostheses within surgical bone tunnels. The rate of degradation of the prosthesis and the response of the tissue were evaluated, as a function of collagen crosslinking agent and time, in nonloaded bone tunnels in rabbits. Prostheses were fabricated by the alignment of 200 reconstituted type-I collagen fibers (60 μm in diameter) and the embedding of the fibers within a collagen matrix. The prostheses degraded rapidly within the bone tunnels in comparison with soft-tissue implantation sites. Dehydrothermal-cyanamide crosslinked collagen fibers were completely degraded by 8 weeks. Only 10% of glutaraldehyde crosslinked collagen fibers remained intact at 12 weeks. Fibrous tissue and inflammatory cells rapidly infiltrated the prostheses, and new bone surrounded the circumference of the prostheses, advancing toward the center at longer times. At the lateral cortex, where fibrous tissue emerged, the bone/soft-tissue interface was delineated by a tidemark, similar to that observed in a normal ligament insertion site. Preliminary pull-out testing of the soft tissue; this suggests rapid incorporation of the prostheses within the bone tunnels. Composite collagen prostheses designed for ACL reconstruction degrade rapidly in bone and induce rapid ingrowth of fibrous tissue and bone. These results suggest that tissue ingrowth in the bone tunnels might provide biological fixation for collagen prostheses used for ACL reconstruction.     

Repair and reconstruction of the anterior cruciate ligament by the “Sandwich technique”

Summary The effect of complete ensheathment of the repaired or reconstructed anterior cruciate ligament (ACL) in the infrapatellar fat pad was studied in a rabbit model. Four to 16 weeks after repair of a transected ACL or insertion of an autologous tendon graft these tissues were evaluated by histology and microangiography. Following ACL repair a high incidence of ligament atrophy was evident in both the ensheathed (43%) and the non-ensheathed control (54%) group. In functional ligaments a similar sequence of remodelling events was evident in both the ensheathed and the non-ensheathed group: infiltration of the transected area by mesenchymal cells, maturation of these cells to fibroblasts, and increasing organization of newly formed collagen fibres. An initial hypervascular reaction was followed by a decrease in the number and an increase in the longitudinal orientation of blood vessels. Despite a similar sequence of remodelling events, however, this process was considerably accelerated in repaired ligaments ensheathed with infrapatellar fat pad compared with non-ensheathed controls. At 16 weeks only the ensheathed repaired ACL resembled the normal ACL morphologically, even though it was still hypercellular. The tendon autograft followed a similar course from an initially avascular and acellular tissue towards a structure similar to the normal ACL. In the ensheathed ligaments and tendon grafts vascular and cellular ingrowth as well as subsequent maturation were again accelerated. This effect may be attributable to improved revascularization and cell repopulation, as well as protection from synovial fluid by the surrounding fat pad.     

The phenomenon of "ligamentization": anterior cruciate ligament reconstruction with autogenous patellar tendon

Reconstruction of the anterior cruciate ligament (ACL) with patellar tendon (PT) is a common procedure for the symptomatic ACL-deficient knee. Questions regarding graft incorporation, viability, and nutrition of the transplanted tissue are of concern. This relates to the graft's response to its new intrasynovial milieu and new physical forces. These factors were studied in a rabbit model of ACL reconstruction using PT and were evaluated with histological and biochemical parameters with respect to time. A histological and biochemical metamorphosis of the grafted PT occurred in this study. Autografts demonstrated a gradual assumption of the microscopic properties of normal ACL; by 30 weeks postoperatively, cell morphology was ligamentous in appearance. Normally, type III collagen is not observed in PT, however, a gradual increase in its concentration was seen in the grafts; by 30 weeks its concentration (10%) was the same as in normal ACL. Similarly, glycosaminoglycans content increased from its normally low level in PT to that found in native ACL. Collagen-reducible crosslink analysis demonstrated that grafted tissue changed from the normal PT pattern of low dihydroxylysinonorleucine (DHLNL) and high histidinohydroxymerodesmosine (HHMD) to the pattern seen in normal ACL (high DHLNL and low HHMD) by 30 weeks. These data suggest that when PT is placed in the anatomic and environmental milieu of the ACL, a "ligamentization" of the grafted tissue results; also the autograft initially depends on synovial fluid nutrition, as revascularization occurs after 6 weeks.     

Development of ligament-bone junction in anterior cruciate ligament reconstruction with the scaffold type polyester artificial ligament (Leeds-Keio) in the dog]

The anterior cruciate ligament (ACL) was reconstructed in sixty mongrel dogs with artificial ligament (Leeds-Keio). The tibial ligament-bone junction was completely removed before the reconstruction in order to investigate the remodelling process of the junction. The dogs were divided into five groups. In all of these the artificial ligament was taut when implanted except for one group which had deliberately a slack reconstruction. In three groups the reconstructions included the use of a strip of infrapatellar synovium alone or with a strip of fascia lata within or outside the artificial ligament. After two, four, twelve and twenty-four weeks, the tibial junction was investigated macroscopically, histologically and by means of microangiography. Newly formed fibrocartilage and functionally aligned collagen were observed in the junction 12 weeks after the initial surgery in all groups, but not in the group with a slack reconstruction. From the results of this study, it was concluded that infrapatellar synovial transfer improved tissue induction in the early stages, and further, the additional use of the fascia speeded up the remodelling process.     

Replacement of the anterior cruciate ligament with a bone-ligament-bone anterior cruciate ligament allograft in dogs

Acute replacement of the canine anterior cruciate ligament (ACL) with a frozen, bone-ligament-bone anterior cruciate ligament preparation was studied using biochemical, immunologic, and biomechanical testing methods. Nine dogs were used for the study, six dogs received allografts and three received autografts. No tissue antigen matching was performed. All nine dogs were killed nine months after surgery. Necropsy examination revealed that the ACL was not present in three joints (one autograft, two allografts). The two autograft and four allograft ligaments available for mechanical testing sustained mean maximum loads that were 10% and 14%, respectively, of the mean maximum loads sustained by the contralateral ACL. Autoradiography indicated that cellular activity was more pronounced in the autograft specimens. Hydroxyproline uptake was 200% and 45% of normal in the autograft and allograft ligaments, respectively. Both autograft and allograft specimens were producing Type I collagen at the time of killing. Antidonor dog leukocyte antigen (DLA) antibody was detected in the synovial fluid taken at the time of killing from six of six dogs that received allografts and in zero of three dogs that received autografts.     

Editorial Commentary: Reduce the Failure Risk: A Challenge to Reduce the Risk of Using Hybrid Graft in Anterior Cruciate Ligament Reconstruction

Hybrid grafting (augmentation of small hamstring autografts with allograft tissue) is preferred by many surgeons for anterior cruciate ligament (ACL) reconstruction. Although a recent, well-conducted, systematic review reported no significant differences in failure risk between hybrid graft and autograft ACL reconstruction, a trend toward a greater failure risk using the hybrid graft existed in many of the included studies. Three potential causes of hybrid graft ACL reconstruction failure that are absent in autograft ACL reconstruction are different levels of graft revascularization and ligamentization, differences in the tendon-bone healing capacity between the allograft and autograft portions in the bone tunnel, and processing of the graft. Research advances in these areas will further reduce the failure risk of hybrid graft ACL reconstruction.     

关节镜下膝关节前、后交叉韧带重建53例

目的总结关节镜下前、后交叉韧带（ACL、PCL）及膝内外侧复合体重建的经验。方法关节镜下移植中1/3骨-髌腱-骨组织、4股腘绳肌腱及LARS人工韧带重建膝关节ACL、PCL。合并膝内、外侧结构损伤患者在重建的同时进行膝关节侧副韧带和关节囊的修补。术后佩戴可调式膝关节固定带3个月行康复训练。结果53例随访2个月～5年4个月,Lysholm评分由术前平均（20±4.6）分提高到（85±7.3）分。所有患者术前抽屉试验及Lachman试验存在阳性体征,术后1例后抽屉试验阳性,4例Lachman试验弱阳性。所有患者关节功能明显改善。结论在关节镜直视下交叉韧带重建能准确定位ACL、PCL解剖止点,具有损伤小,关节粘连率低,恢复快的优点,能达到坚强固定,早期功能锻炼的目的。     

阴茎悬韧带及其周围组织器官的局部解剖

目的:研究阴茎悬韧带及其周围组织器官的解剖特点,为相关手术提供解剖学依据.方法:对28具成年男性尸体阴茎悬韧带及其周围器官组织进行解剖,详细测量记录每个标本阴茎悬韧带的位置、宽度及其与周围组织器官的关系.结果:阴茎悬韧带与阴茎门部神经血管关系密切,由三个部分组成,层次分明.松解浅层和中层韧带后可以获得3.5～5.0 cm(平均4.1 cm)长度增量;深层位于阴茎两侧脚附着于两侧耻骨下支.结论:阴茎悬韧带松解术应以解剖学为基础,长度增量受神经血管蒂长度的限制.     

人工韧带用于前交叉韧带修复重建：目前产品与经验

人工韧带产品自20世纪70年代开始用于临床重建前交叉韧带(anterior cruciate ligament,ACL),经历了较为坎坷的发展历程。早期人工韧带产品重建ACL疗效欠佳,大多以失败告终。近20年来随着新人工韧带产品的出现,临床应用其重建ACL逐渐增多,常用人工韧带包括Leeds-Keio TM、LARSTM(Ligament Advanced Reinforcement System)、Trevira HochfestTM,其中LARSTM应用较多。上述人工韧带具有优越的力学性能,累积失败和并发症发生率较早期产品有显著改善,但也有各自不足之处。     

三种不同移植物重建前交叉韧带的疗效分析

目的 观察及比较关节镜下自体四股半腱肌肌腱、深低温同种异体骨-腱-骨(B-PT-B)复合体、LARS人工韧带重建膝前交叉韧带(ACL)的临床疗效.方法 对55例膝ACL断裂患者行关节镜下ACL重建术,根据重建ACL的材料来源分为自体四股半腱肌肌腱组(20例)、深低温同种异体B-PT-B复合体组(20例)、LABS人工韧带组(15例),并对3组在股四头肌肌力、关节稳定性、Lysholm膝关节功能评分等方面进行对比研究.结果 术后3个月股四头肌肌力恢复情况:LARS人工韧带组较自体组、异体组恢复快,而自体组与异体组无明显差异;术后3个月膝关节稳定性:LARS人工韧带组较自体组、异体组好,自体组与异体组无明显差异,Lysholm评分:自体组(86.3±4.1)分与异体组(88.6±3.8)分无明显差异,但LARS人工韧带组(95.4±4.2)分明显高于前2组(P＜0.05).术后12个月,3组股四头肌肌力恢复情况、膝关节稳定性、功能评分差异无统计学意义(P＞0.05).结论 关节镜下同种异体韧带、LAPS人工韧带重建膝ACL疗效满意,可作为自体材料的良好替代物,但患者所承担费用较高;LARS人工韧带可在术后早期进行膝关节功能活动.