Artificial Ligament Research Articles

Anterior cruciate ligament reconstruction: a look at prosthetics - past, present and possible future

Biological tissue autograft reconstruction using the patellar tendon or quadrupled semitendinosus/gracilis tendons has become the most popular procedure in surgical treatment of a ruptured ACL. This article provides a review of the history of the use of prosthetics with respect to ACL reconstruction grafts including Carbon Fibre, Gore-Tex and Dacron prosthetics as well as the Leeds-Keio Artificial Ligament and the Kennedy Ligament Augmentation Device (LAD). Emphasis is placed on the Ligament Advanced Reinforcement System (LARS) as preliminary investigations of its use have been encouraging. Significant progress has been made recently with respect to the understanding of ACL anatomy, composition, biomechanics, and healing processes, leading to innovative techniques using approaches based in tissue engineering principles and computer - assisted surgery. While research into improved ACL treatment options continues, the synthesis of recent advancements provides a new optimism towards the regeneration of an ACL mirroring its original stability, function, and longevity.

A case report of traumatic osteoarthritis associated with LARS artificial ligament use in anterior cruciate ligament reconstruction

BackgroundA ligament advanced reinforcement system (LARS) artificial ligament has been proposed for use in anterior cruciate ligament (ACL) reconstruction, and many reports have shown its success in ACL reconstruction. However, there are great concerns about the potential risk of complications, which might prevent its extensive use. Late failure may occur due to serious complications.Case presentationWe report a rare case of serious osteoarthritis that occurred 2 years postoperatively in a 51-year-old man who underwent reconstruction with an LARS artificial ligament. In X-rays, the tibial tunnel was placed too posteriorly. MRI showed that the tibial tunnel was enlarged, and there was a large effusion in the knee joint. The LARS device was rough and worn. Histologically, a large number of fibroblasts and a few multinucleated giant cells infiltrated the graft fibres.ConclusionOur findings remind surgeons that an LARS device should be with great caution in ACL reconstruction.

A Cell-free Biodegradable Synthetic Artificial Ligament for the Reconstruction of Anterior Cruciate Ligament in a Rat Model

Traditional Anterior Cruciate Ligament (ACL) reconstruction is commonly performed using an allograft or autograft and possesses limitations such as donor site morbidity, decreased range of motion, and potential infection. However, a biodegradable synthetic graft could greatly assist in the prevention of such restrictions after ACL reconstruction. In this study, artificial grafts were generated using "wet" and "dry" electrospinning processes with a biodegradable elastomer, poly (ester urethane) urea (PEUU), and were evaluated in vitro and in vivo in a rat model. Four groups were established: (1) Wet PEUU artificial ligament, (2) Dry PEUU artificial ligament, (3) Dry polycaprolactone artificial ligament (PCL), and (4) autologous flexor digitorum longus tendon graft. Eight weeks after surgery, the in vivo tensile strength of wet PEUU ligaments had significantly increased compared to the other synthetic ligaments. These results aligned with increased infiltration of host cells and decreased inflammation within the wet PEUU grafts. In contrast, very little cellular infiltration was observed in PCL and dry PEUU grafts. Micro-computed tomography analysis performed at 4 and 8 weeks postoperatively revealed significantly smaller bone tunnels in the tendon autograft and wet PEUU groups. The Wet PEUU grafts served as an adequate functioning material and allowed for the creation of tissues that closely resembled the ACL.

Arthroscopic Fixation Technique for Avulsion Fracture of the Posterior Cruciate Ligament From the Tibia

This study describes an arthroscopic pullout fixation technique for small and comminuted avulsion fractures of the posterior cruciate ligament from the tibia. Intra-articular surgery required 3 arthroscopic portals, the anterolateral, anteromedial, and posteromedial portals. To simplify surgery, the posterolateral portal was omitted. A 2.4-mm K-wire was inserted through the anterior incision to the center of the bone fragment. This central guidewire was subsequently overdrilled with a 4.0-mm cannulated drill. The fixation material consisted of Pass Telos artificial ligaments inserted through the fiber loop of a fixed suspensory device such as RIGIDLOOP. The leading end of the thread of the RIGIDLOOP was pulled out through the anteromedial portal. The button of RIGIDLOOP was gradually advanced through the bone tunnel. The button was pulled out and flipped over the bony fragment. The artificial ligament was pulled distally to reduce the bony fragment, and fixed onto the tibia using a ligament button while applying anterior drawer force to the proximal tibia with the knee flexed at 90°. This minimally invasive procedure was successful in treating small and comminuted avulsion fracture of the tibial attachment of the posterior cruciate ligament.

Comparison of the effectiveness of autologous grafts for anterior cruciate ligament reconstruction: A protocol for an overview of systematic review and network meta-analysis.

Background:Anterior cruciate ligament rupture is a common motor system injury, and the most effective treatment is anterior cruciate ligament reconstruction (ACLR). Choosing the right graft is an important factor to ensure the success of the surgery. Current research shows that the clinical effect of autologous ligaments is better than that of allogeneic ligaments and artificial ligaments. However, there are differences between the autogenous ligaments, and how to choose them is still controversial. This study evaluated the published systematic reviews on the efficacy of different autologous ligament grafts in ACLR, and based on this, conducted a network meta-analysis of related randomized controlled trials.Methods:We searched 8 international and Chinese databases including PubMed, Embase, Web of Science, and Cochrane Library. The methodological quality of systematic reviews will be evaluated by Assessing the Methodological Quality of Systematic Reviews-2 (AMSTAR2) measurement tool. Cochrane's risk of bias tool will be used to assess the risk of bias of included randomized controlled trials, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach will be used to evaluate the evidence quality. Network meta-analysis will be applied to evaluate the therapeutic effect of different autologous grafts. The main outcome measures are IKDC score, clinical failure rate, Lachman test, Lysholm score, and the incidence of complications. Odds ratio and its 95% confidence interval will be used to synthesize the dichotomy results, while the mean difference and 95% confidence interval of continuous variables will be used for continuous variables.Results:This study will provide comprehensive evidence for the application of autologous grafts in ACLR.Conclusion:The results of this study will help clinicians make appropriate decisions.Protocol Registration number:INPLASY202090061.

Electrodeposition of calcium phosphate onto polyethylene terephthalate artificial ligament enhances graft-bone integration after anterior cruciate ligament reconstruction

It is a big challenge to develop a polyethylene terephthalate (PET) artificial ligament with excellent osteogenetic activity to enhance graft-bone integration for ligament reconstruction. Herein, we evaluated the effect of biomineralization (BM) and electrodeposition (ED) method for depositing calcium-phosphate (CaP) on the PET artificial ligament in vitro and in vivo. Scanning electron microscopy and energy-dispersive X-Ray spectrometer mapping analysis revealed that the ED-CaP had more uniform particles and element distribution (Ca, P and O), and thermogravimetric analysis showed there were more CaP on the PET/ED-CaP than the PET/BM-CaP scaffold. Moreover, the hydrophilicity of PET scaffolds was significantly improved after CaP deposition. In vitro study showed that CaP coating via BM or ED method could improve the attachment and proliferation of MC3T3-E1 cells, and ED-CaP coating significantly increased osteogenic differentiation of the cells, in which the Wnt/β-catenin signaling pathway might be involved. In addition, radiological, histological and immunohistochemical results of in vivo study in a rabbit anterior cruciate ligament (ACL) reconstruction model demonstrated that the PET/BM-CaP and PET/ED-CaP scaffolds significantly improved graft-bone integration process compared to the PET scaffold. More importantly, larger areas of new bone ingrowth and the formation of fibrocartilage tissue were observed at 12 weeks in the PET/ED-CaP group, and the biomechanical tests showed increased ultimate failure load and stiffness in PET/ED-CaP group compared to PET/BM-CaP and PET group. Therefore, ED of CaP is an effective strategy for the modification of PET artificial ligament and can enhance graft-bone integration both in vitro and in vivo.

Internal bracing with an artificial ligament for superficial medial collateral ligament injury impairs the mechanical property of repaired native ligament: A porcine study

BackgroundSuperficial medial collateral ligament (sMCL) injury is common, but there are no in vivo studies describing the biomechanical efficacy of anatomic repair with internal bracing for grade 3 injuries. MethodsWe used a porcine model to evaluate the efficacy of internal bracing using an artificial ligament for the early repair of acute, grade 3 sMCL injuries. Sixteen male castrated pigs were randomly assigned to a repair group: (1) anatomic repair using two suture anchors (Group R; n = 9) or (2) anatomic repair with internal bracing augmentation (Group IB; n = 7). The left knees were allocated to a sham surgery group (Group S; n = 16). All animals were sacrificed 4 weeks after surgery. The right and left femur-sMCL-tibia complexes were mounted on a tensile tester and stretched to failure using the same conditions as preconditioning at a cross-head speed of 50 mm/min. The internal bracing in Group IB was removed prior to the biomechanical testing. The failure mode and structural properties (upper yield load, maximum load, linear stiffness, and elongation at failure) were determined. ResultsSignificant differences in failure mode were observed among the three groups. All sMCLs repaired with just the suture anchors (Group R) were avulsed from the femoral attachment, while most of the sMCLs repaired with internal bracing augmentation (Group IB) exhibited mid-substance tears (Group R vs Group IB, P = 0.0023). In Group S, 14 sMCLs were avulsed from the femoral attachment and two were avulsed from the tibial attachment (Group IB vs Group S, P < 0.001). No significant difference was observed between Group R and Group S. There were no significant differences in the upper yield load, maximum load, linear stiffness, or elongation at failure among the groups. ConclusionsLoading of an artificial ligament for internal bracing did not result in better structural properties of the repaired sMCL itself.

Frame Coating of Single-Walled Carbon Nanotubes in Collagen on PET Fibers for Artificial Joint Ligaments.

The coating formation technique for artificial knee ligaments was proposed, which provided tight fixation of ligaments of polyethylene terephthalate (PET) fibers as a result of the healing of the bone channel in the short-term period after implantation. The coating is a frame structure of single-walled carbon nanotubes (SWCNT) in a collagen matrix, which is formed by layer-by-layer solidification of an aqueous dispersion of SWCNT with collagen during spin coating and controlled irradiation with IR radiation. Quantum mechanical method SCC DFTB, with a self-consistent charge, was used. It is based on the density functional theory and the tight-binding approximation. The method established the optimal temperature and time for the formation of the equilibrium configurations of the SWCNT/collagen type II complexes to ensure maximum binding energies between the nanotube and the collagen. The highest binding energies were observed in complexes with SWCNT nanometer diameter in comparison with subnanometer SWCNT. The coating had a porous structure—pore size was 0.5—6 μm. The process of reducing the mass and volume of the coating with the initial biodegradation of collagen after contact with blood plasma was demonstrated. This is proved by exceeding the intensity of the SWCNT peaks G and D after contact with the blood serum in the Raman spectrum and by decreasing the intensity of the main collagen bands in the SWCNT/collagen complex frame coating. The number of pores and their size increased to 20 μm. The modification of the PET tape with the SWCNT/collagen coating allowed to increase its hydrophilicity by 1.7 times compared to the original PET fibers and by 1.3 times compared to the collagen coating. A reduced hemolysis level of the PET tape coated with SWCNT/collagen was achieved. The SWCNT/collagen coating provided 2.2 times less hemolysis than an uncoated PET implant. MicroCT showed the effective formation of new bone and dense connective tissue around the implant. A decrease in channel diameter from 2.5 to 1.7 mm was detected at three and, especially, six months after implantation of a PET tape with SWCNT/collagen coating. MicroCT allowed us to identify areas for histological sections, which demonstrated the favorable interaction of the PET tape with the surrounding tissues. In the case of using the PET tape coated with SWCNT/collagen, more active growth of connective tissue with mature collagen fibers in the area of implantation was observed than in the case of only collagen coating. The stimulating effect of SWCNT/collagen on the formation of bone trabeculae around and inside the PET tape was evident in three and six months after implantation. Thus, a PET tape with SWCNT/collagen coating has osteoconductivity as well as a high level of hydrophilicity and hemocompatibility.

Preparing polycaprolactone scaffolds using electrospinning technique for construction of artificial periodontal ligament tissue

ObjectivesThe strategies of tissue-engineering led to the development of living cell-based therapies to repair lost or damaged tissues, including periodontal ligament and to construct biohybrid implant. This work aimed to isolate human periodontal ligament stem cells (hPDLSCs) and implant them on fabricated polycaprolactone (PCL) for the regeneration of natural periodontal ligament (PDL) tissues. MethodshPDLSCs were harvested from extracted human premolars, cultured, and expanded to obtain PDL cells. A PDL-specific marker (periostin) was detected using an immunofluorescent assay. Electrospinning was applied to fabricate PCL at three concentrations (13%, 16%, and 20% weight/volume) in two forms, which were examined through field emission scanning electron microscopy (FESEM). The isolated hPDLSCs were implanted on the fabricated PCL. After 21 days, FESEM was conducted to evaluate the implanted scaffolds, and an MTT assay was performed to characterize the biological response of the PCL scaffold at different cell exposure durations (24, 48, and 72 h). ResultsPeriostin was expressed in the expanded PDL cells, and this result revealed that 20% weight/volume PCL scaffold with a pore size of more than 10 μm was the best. The growth rates of PDLSCs were high. Cytotoxicity test of fabricated PCL scaffold demonstrated no significant change in the cell viability when compared with the negative control and no deteriorating or inhibitory effect on growth after different durations. ConclusionsA cell sheet was successfully formed by using PCL as a scaffold to cover dental implants and promote PDL cell attachment, proliferation, and growth for biohybrid implant construction.

Effectiveness comparison of LARS artificial ligament and autogenous hamstring tendon in one-stage reconstruction of anterior and posterior cruciate ligaments

To compare the effectiveness of arthroscopic one-stage reconstruction of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) with LARS artificial ligament and autogenous hamstring tendon, respectively. A retrospective study was performed on 23 patients with ACL and PCL injuries, who were treated with one-stage reconstruction, between June 2013 and June 2017. The ACL and PCL were reconstructed with LARS artificial ligament in 11 patients (artificial ligament group) and autogenous hamstring tendon in 12 patients (autogenous tendon group). There was no significant difference in gender, age, side of injury, cause of injury, time from injury to operation, and preoperative Lysholm score and International Knee Documentation Committee (IKDC) score between the two groups ( P>0.05). The operation time, the time of recovery of daily activities and preoperative exercise level, the occurrence of surgical-related complications, Lysholm score, IKDC score, and the results of knee stability assessment were recorded and compared between the two groups. The operation time and the time of recovery of daily activities and preoperative exercise level were significantly shorter in artificial ligament group than in autogenous tendon group ( P<0.05). All incisions healed primarily. In autogenous tendon group, the common fibular nerve injury occurred in 1 case and intermuscular vein thrombosis occurred in 1 case. No complication occurred in the remaining patients of the two groups. All the patients were followed up 24-54 months (mean, 36.4 months). At last follow-up, the Lysholm score and IKDC score of the two groups were significantly higher than preoperative scores ( P<0.05). There was no significant difference between the two groups ( P>0.05). The varus and valgus stress tests of the two groups were negative. There was no significant difference in anterior drawer test, posterior drawer test, and Lachman test between the two groups ( P>0.05). The effectiveness of arthroscopic one-stage reconstruction of ACL and PCL with LARS artificial ligament or autogenous hamstring tendon was similar. The knee function and stability recover well. But the patients with LARS artificial ligament reconstruction can resume daily activities and return to exercise earlier.

Analysis of Curative Effect of Artificial Ligament Reconstruction Under Knee Arthroscopy in the Treatment of Posterior Cruciate Ligament Injury.

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Fast-Growing Bacterial Cellulose with Outstanding Mechanical Properties via Cross-Linking by Multivalent Ions.

Bacterial cellulose is an organic product of certain bacterias’ metabolism. It differs from plant cellulose by exhibiting a high strength and purity, making it especially interesting for flexible electronics, membranes for water purification, tissue engineering for humans or even as artificial skin and ligaments for robotic devices. However, bacterial cellulose’s naturally slow growth rate has limited its large-scale applicability to date. Titanium (IV) bis-(ammonium lactato) dihydroxide is shown to be a powerful tool to boost the growth rate of bacterial cellulose production by more than one order of magnitude and that it simultaneously serves as a precursor for the Ti4+-coordinated cross-linking of the fibers during membrane formation. The latter results in an almost two-fold increase in Young’s modulus (~18.59 GPa), a more than three-fold increase in tensile strength (~436.70 MPa) and even a four-fold increase in toughness (~6.81 MJ m−³), as compared to the pure bacterial cellulose membranes.

Biomineralizaion of hydroxyapatite on polyethylene terephthalate artificial ligaments promotes graft-bone healing after anterior cruciate ligament reconstruction: An in vitro and in vivo study.

The purpose of the present study is to modify the polyethylene terephthalate ligament with hydroxyapatite via biomineralization and to investigate its effect on graft-bone healing. After biomineralization of hydroxyapatite, the surface characterization of polyethylene terephthalate ligament was examined by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and water contact angle measurements. The compatibility and osteoinduction, along with the underlying signaling pathway involved of hydroxyapatite-polyethylene terephthalate ligament, were evaluated in vitro. Moreover, a rabbit anterior cruciate ligament reconstruction model was established, and the polyethylene terephthalate or hydroxyapatite-polyethylene terephthalate artificial ligament was implanted into the knee. The micro-computed tomography analysis, histological, and immunohistochemical examination as well as biomechanical test were performed to investigate the effect of hydroxyapatite coating in vivo. The results of scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction showed that the hydroxyapatite was successfully deposited on the polyethylene terephthalate ligament. Water contact angle of the hydroxyapatite-polyethylene terephthalate group was significantly smaller than that of the polyethylene terephthalate group. The in vitro study showed that hydroxyapatite coating significantly improved adhesion and proliferation of MC3T3-E1 cells. The osteogenic differentiation of cells was also enhanced through the activation of ERK1/2 pathway. The micro-computed tomography, histological, and immunohistochemical results showed that biomineralization of hydroxyapatite significantly promoted new bone and fibrocartilage tissue formation at 12 weeks postoperatively. Moreover, the failure load and stiffness in the hydroxyapatite-polyethylene terephthalate group were higher than that in the polyethylene terephthalate group. Therefore, biomineralizaion of hydroxyapatite enhances the biocompatibility and osseointegration of the polyethylene terephthalate artificial ligament, thus promoting graft-bone healing for anterior cruciate ligament reconstruction through the activation of ERK1/2 pathway.

Australian Footballers Returning from Anterior Cruciate Ligament Reconstruction Later than 12Months have Worse Outcomes.

There is evidence that early return to competition post-anterior cruciate ligament (ACL) injury increases risk of re-injury. To compare subsequent ACL and other injury risks following ACL reconstruction for Australian Football League (AFL) players returning to competition at different times post-injury. AFL players returning from ACL reconstruction in the 1992-2014 seasons were divided into three groups based on return to competition time (< 10, 10-12 and > 12months). Non-reconstructed injuries and artificial ligament reconstructions were excluded. Subsequent ACL injury rates were calculated based on time since injury and number of return matches played. Risk of other knee and hamstring muscle injuries was also calculated. There were 233 ACL reconstructions that returned to play in the AFL during the time period under study and met our inclusion criteria. The per-game risk of subsequent ACL injury decreased with a log decay from 1.2 to 0.15% during the first 20 games back (R 2 = 0.43). Players returning at > 12months had higher overall percentage of future career games missed through subsequent ACL injuries (4.8% vs. 2.4%), and through all hamstring and knee injuries combined (12.6% vs. 8.4%) than players who returned at ≤ 12months (both P < 0.001). Players returning at > 12months had higher risk of knee cartilage (3.7%) and patella tendon (0.6%) injury than those returning at 10-12months (1.5%, 0.1%, respectively). Players returning from ACL reconstruction at greater than 12months had significantly higher rates of future games missed through both subsequent ACL injuries and through all hamstring and knee injuries combined. It may be true that both early and late return to play lead to suboptimal outcomes compared to average return-to-play times.

Artificial ligament made from silk protein/Laponite hybrid fibers

With developments in tissue engineering, artificial ligaments are expected to be future materials for anterior cruciate ligament (ACL) reconstruction. However, poor healing of the intraosseous part after ACL reconstruction significantly hinders their applications in this field. In this study, a bioactive clay Laponite (LAP) was introduced into the regenerated silk fibroin (RSF) spinning dope to produce functional RSF/LAP hybrid fibers by wet-spinning. These RSF/LAP hybrid fibers were then woven into artificial ligament for ACL reconstruction. The structure and mechanical properties of RSF/LAP hybrid fibers were extensively studied by different means. Results confirmed the presence of LAP in RSF fibers and revealed that the addition of LAP slightly deteriorated the comprehensive mechanical properties of RSF fibers. However, they were still much tougher (with higher breaking energy) than those of degummed natural silkworm silk that was earlier used for making artificial ligament. The artificial ligament woven from RSF/LAP hybrid fibers showed better cytocompatibility and osteogenic differentiation with mouse pre-osteoblasts in vitro than those made from degummed natural silkworm silks and pure RSF fibers. Furthermore, in vivo study in a rat ACL reconstruction model demonstrated that the presence of LAP in the artificial ligament could significantly enhance the graft osseointegration process and also improve the corresponding biomechanical properties of the artificial ligament. Based upon these results, the RSF/LAP hybrid fibers, which can be mass produced by wet-spinning process, are believed to have a great potential for use as artificial ligament materials for ACL reconstruction. Statement of SignificanceIn this study, we successfully introduced Laponite (LAP), a kind of clay that has the function of osteogenic induction, into regenerated silk fibroin (RSF) fibers, which was prepared by a mature wet-spinning method developed in our lab. We believe that through artificial spinning, additional functional components can be added into RSF fibers, which one can hardly achieve with natural silks. We showed that the artificial ligament woven from RSF/LAP hybrid fibers had better cytocompatibility and osteogenic differentiation for mouse pre-osteoblasts in vitro, and significantly enhanced the graft osseointegration process and improved the corresponding biomechanical properties in a rat ACL reconstruction model in vivo, compared to those artificial ligaments made from degummed natural silkworm silks and pure RSF fibers.

Artificial ligaments applied in anterior cruciate ligament repair and reconstruction: Current products and experience

The application of artificial ligament products in anterior cruciate ligament (ACL) surgeries has gone through a long twisty way. In the 1970s, early artificial ligament products were initially used for ACL surgeries, which showed poor clinical efficacy and eventually ended up in failure. Over the last 20 years, there has been a growing number of ACL reconstruction with new artificial ligament products, including the Leeds-Keio TM, the LARS TM (Ligament Advanced Reinfocement System), and the Trevira Hochfest TM. Among these new products, the LARS TM has been more commonly applied for ACL surgeries. Although these new artificial ligament products have good mechanical properties and show significant improvement of cumulative failure and complication rate, they still have limitations.

Influence of silk fibroin/sodium alginate coatings on the mineralization of silk fibroin fiber artificial ligament prototypes

The goal of the present work is to investigate the effects of varying coatings on in vitro mineralization of silk fibroin fiber artificial ligaments (SFALs). Silk fibroin (SF) and sodium alginate (SA) aqueous solutions with varying concentrations were respectively employed for coating surfaces of the SFALs to improve calcium phosphate (CaP) deposition. Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and Energy-dispersive X-ray spectroscopy were utilized for characterizations. Furthermore, the surface of the SFAL was modified with SF/SA composite coatings. The volume ratios of the SF to the SA were set at 2:8, 4:6, 5:5, 6:4 and 8:2. The results show that either the SF or the SA coatings can improve the mineralization of the SFALs in vitro. The concentration of 1% for the SF and the SA coatings is conducive to deposit more calcium ions and obtain a biomimetic Ca/P ratio. Furthermore, the SF/SA composite coatings facilitate a thicker and uniform deposition layer than the SF and the SA coatings. The sediments are spherical particles and are more uniform in size. Therefore, the SF/SA composite coatings have more significant efficacy, particularly when the volume ratio of the SF to the SA was 4:6. The present work indicates that the SF/SA coatings possess excellent potential in promoting the osseointegration of artificial ligaments implanted in bone tunnels.

Management of patellar tendon avulsion following total knee arthroplasty using artificial ligament

Management of patellar tendon avulsion following total knee arthroplasty using artificial ligament

Histological analysis of ACL reconstruction failures due to synthetic-ACL (LARS) ruptures.

Introduction:Anterior Cruciate Ligament (ACL) reconstruction is an established surgical procedure. Synthetic ligaments represent an option for ACL reconstruction. Their popularity declined for the raising concerns due to re-ruptures, knee synovitis and early arthritis related to I and II generation artificial ligaments. The introduction of a III generation synthetic ligament (Ligament Advanced Reinforcement System-LARS) permitted renewed interest in the adoption of this kind of graft. Main purpose of our study was to describe the histological findings on samples obtained from a consecutive series of ACL revision surgeries due to LARS ACL reconstruction failures. Secondary aim was to determine the reason for LARS rupture.Methods:In a period between 2016 and 2018 eleven patients underwent ACL revision surgery due to LARS ACL reconstruction failure. At the time of the arthroscopic procedure, samples of synovial membrane and remnants of the torn LARS were sent to the Pathological-Anatomy Institute of our Hospital for a histological analysis.Results:Histological analysis of the synovial tissues confirmed the arthroscopic evidence of synovitis mainly characterized by chronic inflammation with predominance of multinucleated giant cells. The adoption of polarized light microscopy revealed the presence of brightly bi-refractive material (LARS wear particles) in the synovial tissue; at higher magnification wear debris were detected inside the cytoplasma of multi nucleated cells. The histological analysis of the removed LARS revealed a surrounding typical foreign body reaction with poor signs of fibrovascular ingrowth of the synthetic ligament.Conclusions:Our findings could not clearly advocate a unique mechanism of LARS-ACL reconstruction failure: biologic issues (poor tissue ingrowth) and mechanical issues (fibers properties and tunnel position) probably concur in a multi factorial manner. ACL reconstruction using artificial ligaments can not be considered a simple surgery. Artificial augments require some expertise and could therefore achieve better results if used by skilled sport surgeons other than trainees or low volume surgeons. The Authors believe that ACL reconstruction with synthetic devices still have restricted indications for selected patients (e.g. elderly patients who require a fast recovery, professional athlete, autologous tendons not available and/or refusing donor tendons). Our study arises additional suspicion on the unresponsiveness of synthetic fibers and claim some concern in the implantation of synthetic devices. (www.actabiomedica.it)

Acute quadriceps tendon rupture repaired by suture anchors and artificial ligament in 2 cases

Acute quadriceps tendon rupture repaired by suture anchors and artificial ligament in 2 cases