Surgical suturing of articular cartilage induces osteoarthritis-like changes

Local Morphological Response of the Distal Femoral Articular-Epiphyseal Cartilage Complex of Young Foals to Surgical Stab Incision and Potential Relevance to Cartilage Injury and Repair in Children

OBJECTIVE

Describe the local morphological response of the articular-epiphyseal cartilage complex to surgical stab incision in the distal femur of foals, with emphasis on the relationship between growth cartilage injury, enchondral ossification, and repair.

DESIGN

Nine foals were induced into general anesthesia at the age of 13 to 15 days. Four full-thickness stab incision defects were created in the cartilage on the lateral aspect of the lateral trochlear ridge of the left distal femur. Follow-up examination was carried out from 1 to 49 days postoperatively, including examination of intact bones, sawed slabs, and histological sections.

RESULTS

Incision defects filled with cells displaying fibroblast-, chondrocyte-, and osteoblast-like characteristics, potentially validating the rationale behind the drilling of stable juvenile osteochondritis dissecans lesions in children. Incisions induced necrosis within the cartilage on the margins at all depths of the defects. Sharp dissection may therefore be contraindicated in cartilage repair in young individuals. Incisions caused a focal delay in enchondral ossification in 2 foals, apparently related to the orientation of the incision defect relative to the direction of ossification. Defects became progressively surrounded by subchondral bone, in which granulation tissue containing clasts and foci of osteoblast-like cells was observed. Continued enchondral ossification was therefore likely to result in healing of uncomplicated defects to morphologically normal bone.

CONCLUSIONS

Epiphyseal growth cartilage injury had the potential to exert a negative effect on enchondral ossification. Enchondral ossification exerted a beneficial effect on repair. This relationship warrants consideration in future studies of cartilage injury and repair within the articular-epiphyseal cartilage complex of all species.

A Randomized, Controlled Trial Comparing Autologous Matrix-Induced Chondrogenesis (AMIC®) to Microfracture: Analysis of 1- and 2-Year Follow-Up Data of 2 Centers

Microfracture (MFx) is currently the recommended option for the treatment of small cartilage defects but is not regarded as suitable for the treatment of defects larger than 2.5 cm². To extent its applicability to medium-sized defects MFx has been combined with a collagen type I/III matrix (Chondro-Gide^®). This technique is called Autologous Matrix-Induced Chondrogenesis (AMIC^®) and meanwhile a clinically established treatment option for localized full-thickness small- to medium-sized cartilage defects. Despite its more spreading clinical use, clinical data published so far are limited to mainly case report series.

In this study, we report the first results of a randomized, controlled trial assessing the efficacy and safety of AMIC^® versus MFx. Patients enrolled in 2 centers were included in this analysis. 38 patients (aged 21-50 years, mean defect size 3.4 cm²) were randomized and treated either with MFx, with sutured AMIC^® or glued AMIC^®. Clinical outcomes (modified Cincinnati and ICRS score) could be assessed in 30 patients at 1-year and 27 patients at 2-years post-operation. Improvements in both scores were seen at 1-and 2-years post-operation, irrespective of the technique used. MRI assessment revealed a satisfactory and homogenous defect filling in the majority of patients. No treatment-related adverse events were reported.

This interim analysis confirms the mid-term results for AMIC^® reported in literature. It demonstrates clearly that clinical outcomes at 1-year post-operation are maintained at 2-years. Therefore we consider enhancing MFx with Chondro-Gide^® is a valid and safe cartilage repair option for small- to medium-sized cartilage defects of the knee.

One-Year Clinical and Radiological Results of a Prospective, Investigator-Initiated Trial Examining a Novel, Purely Autologous 3-Dimensional Autologous Chondrocyte Transplantation Product in the Knee

BACKGROUND

The 3-dimensional autologous chondrocyte transplantation (ACT3D) comprises isolation of chondrocytes from cartilage biopsies, cultivation to spheroids, and transplantation into the cartilage defect.

OBJECTIVES

To evaluate the patients' general health and functionality and to assess the defect repair after ACT3D with spheroids by MRI and MOCART scoring.

METHODS

Thirty-seven patients with isolated chondral lesions of the knee underwent ACT3D with spheroids through medial arthrotomy. Patient-administered scores were assessed at baseline (day before transplantation), at 6 weeks, and at 3, 6, and 12 months. MRI and MOCART scoring were performed at 3 and 12 months after ACT3D.

RESULTS

Patients were diagnosed with full-thickness patellofemoral (n = 16), femoral condylar (n = 18), or both defect types (n = 3), International Cartilage Repair Society (ICRS) grade 3 or 4, with defect sizes between 1.0 and 12.0 cm(2). On average, 59.5 spheroids/cm(2) in defect size were transplanted. An overall statistically significant improvement from baseline to 12 months was observed for all assessment scores (Lysholm, International Knee Documentation Committee [IKDC], SF-36, Tegner) combined with a significant reduction in the visual analog scale (VAS) for pain and an advanced defect filling. Subgroup analyses revealed a positive clinical outcome independent on defect size, defect locations, spheroid dosage, age, duration of symptoms, and severity of complaints at baseline. Seven patients experienced in total 8 adverse events, of which knee joint effusion and blocking were assessed as possibly or probably related to ACT3D.

CONCLUSIONS

The patient-administered assessment scores along with the fast defect filling with ACT3D using spheroids demonstrated an increase in activity level and quality of life after a 1-year follow-up.

Cell-Seeded Collagen Matrix-Supported Autologous Chondrocyte Transplantation (ACT-CS): A Consensus Statement on Surgical Technique

OBJECTIVE

Autologous chondrocyte transplantation has become an established therapy for full-thickness cartilage defects. Cell-seeded collagen matrix-supported autologous chondrocyte transplantation (ACT-CS) has been introduced as a modification of conventional ACT, which allows easier handling and is intended to combine the advantages of using a cell suspension (i.e., cell viability and mitotic activity) with the stability and self-containment provided by a matrix of biomaterials. Unlike other techniques and products, this seeding step can be easily applied using a porcine collagen type I/III membrane and autologous chondrocytes in an operating room setting. Although some suturing is required, this technique provides the distinct advantage of not requiring a water-tight seal of the bilayer membrane, as is required using the classic cell suspension technique. Comparable to other modifications of ACT, the ACT-CS procedure requires a specific surgical technique that focuses on the following important details: (1) accurate debridement of the cartilage defect; (2) preparation of the cells, and seeding and containment of the cells within the transplantation site; and (3) sealing and suturing around the defect.

DESIGN

A consensus meeting of leading European orthopedic surgeons specializing in cartilage repair was convened to discuss and standardize the surgical aspects of this technique.

RESULTS & CONCLUSIONS

The present article describes and discusses the adoption of these best surgical practices for implementing the ACT-CS technique, including more detailed descriptions of each phase of the surgery in order to standardize and optimize patient outcomes.

Acrylamide Polymer Double-Network Hydrogels: Candidate Cartilage Repair Materials with Cartilage-Like Dynamic Stiffness and Attractive Surgery-Related Attachment Mechanics

BACKGROUND

In focal repair of joint cartilage and meniscus, initial stiffness and strength of repairs are generally much less than surrounding tissue. This increases early failure potential. Secure primary fixation of the repair material is also a problem. Acrylamide polymer double-network (DN) hydrogels are candidate-improved repair materials. DN gels have exceptional strength and toughness compared to ordinary gels. This stems from the double-network structure in which there is a high molar ratio of the second network to the first network, with the first network highly crosslinked and the second loosely crosslinked. Previous studies of acrylic PAMPS/PDMAAm and PAMPS/PAAm DN gels demonstrated physicochemical stability and tissue compatibility as well as the ability to foster cartilage formation.

METHODS

Mechanical properties related to surgical use were tested in 2 types of DN gels.

RESULTS

Remarkably, these >90%-water DN gels exhibited dynamic impact stiffness (E*) values (~1.1 and ~1.5 MPa) approaching swine meniscus (~2.9 MPa). Dynamic impact energy-absorbing capability was much lower (median loss angles of ~2°) than swine meniscus (>10°), but it is intriguing that >90%-water materials can efficiently store energy. Also, fine 4/0 suture tear-out strength approached cartilage (~2.1 and ~7.1 N v. ~13.5 N). Initial strength of attachment of DN gels to cartilage with acrylic tissue adhesive was also high (~0.20 and ~0.15 N/mm(2)).

CONCLUSIONS

DN gel strength and toughness properties stem from optimized entanglement of the 2 network components. DN gels thus have obvious structural parallels with cartilaginous tissues, and their surgical handling properties make them ideal candidates for clinical use.

Mid-term results of Autologous Matrix-Induced Chondrogenesis for treatment of focal cartilage defects in the knee

Articular cartilage defects heal poorly. Autologous Matrix-Induced Chondrogenesis (AMIC) is an innovative treatment for localized full-thickness cartilage defects combining the well-known microfracturing with collagen scaffold and fibrin glue. The purpose of this prospective study was to evaluate the medium-term results of this enhanced microfracture technique for the treatment of chondral lesions of the knee. Thirty-two chondral lesions in 27 patients were treated with AMIC. Within the context of clinical follow-up, these patients were evaluated for up to 5 years after the intervention. Five different scores (Meyer score, Tegner score, Lysholm score, ICRS score, Cincinnati score) as well as radiographs were used for outcome analysis. Articular resurfacing was assessed by magnetic resonance imaging (MRI). The average age of patients (11 females, 16 males; mean body mass index 26, range 20-32) was 37 years (range 16-50 years). The mean defect size of the chondral lesions was 4.2 cm(2) (range 1.3-8.8 cm(2)). All defects were classified as grade IV according to the Outerbridge classification. The follow-up period was between 24 and 62 months with a mean of 37 months. Twenty out of 23 individuals (87%) questioned were subjectively highly satisfied with the results after surgery. Significant improvement (P < 0.05) of all scores was observed as early as 12 months after AMIC, and further increased values were notable up to 24 months postoperatively. MRI analysis showed moderate to complete filling with a normal to incidentally hyperintense signal in most cases. Results did not show a clinical impact of patient's age at the time of operation, body mass index and number of previous operations (n.s.). In contrast, males showed significant higher values in the ICRS score compared to their female counterparts. AMIC is an effective and safe method of treating symptomatic full-thickness chondral defects of the knee in appropriately selected cases. However, further studies with long-term follow-up are needed to determine whether the grafted area will maintain structural and functional integrity over time.

Histopathology atlas of animal model systems - overview of guiding principles

Animal model systems represent an important adjunct and surrogate for studies of osteoarthritis (OA) in humans. They provide a means to study OA pathophysiology as well as aid in the development of therapeutic agents and biological markers for diagnosing and prognosing the disease. Thus, it is of great importance for the OA scientific community, both in academic as well as industrial research, to standardize scoring systems for evaluating the OA disease process and to make results between different studies comparable. The task of the histopathology initiative of OARSI was to achieve a consensus of scoring systems for the most important species used in OA animal model research (dog, guinea pig, horse, mouse, rabbit, rat, and sheep/goat), which are presented in the various chapters in this special volume of Osteoarthritis & Cartilage together with extra chapters on basic methodology (histochemistry, statistics, morphometry), the specific terminology and a general discussion of animal models in OA research. Standardized definitions are suggested for basic but essential terms such as "grading" and "staging" in order to promote their consistent use and thereby promote improved understanding and data interpretation across all model systems. Thus, this introductory chapter presents an overview of the guiding principles for assessment of important OA animal model systems. Use of such systems, independently or in conjunction with other systems in parallel, should facilitate comparability of results across animal model studies.

The cell biology of suturing tendons

Trauma by suturing tendon form areas devoid of cells termed "acellular zones" in the matrix. This study aimed to characterise the cellular insult of suturing and acellular zone formation in mouse tendon. Acellular zone formation was evaluated using single grasping sutures placed using flexor tendons with time lapse cell viability imaging for a period of 12h. Both tension and injury were required to induce cell death and cell movement in the formation of the acellular zone. DNA fragmentation studies and transmission electron microscopy indicated that cells necrosed. Parallel in vivo studies showed that cell-to-cell contacts were disrupted following grasping by the suture in tensioned tendon. Without tension, cell death was lessened and cell-to-cell contacts remained intact. Quantitative immunohistochemistry and 3D cellular profile mapping of wound healing markers over a one year time course showed that acellular zones arise rapidly and showed no evidence of healing whilst the wound healing response occurred in the surrounding tissues. The acellular zones were also evident in a standard modified "Kessler" clinical repair. In conclusion, the suture repair of injured tendons produces acellular zones, which may potentially cause early tendon failure.

Advances in Tissue Engineering Techniques for Articular Cartilage Repair

The limited repair potential of human articular cartilage contributes to development of debilitating osteoarthritis and remains a great clinical challenge. This has led to evolution of cartilage treatment strategies from palliative to either reconstructive or reparative methods in an attempt to delay or "bridge the gap" to joint replacement. Further development of tissue engineering-based cartilage repair methods have been pursued to provide a more functional biological tissue. Currently, tissue engineering of articular cartilage has three cornerstones; a cell population capable of proliferation and differentiation into mature chondrocytes, a scaffold that can host these cells, provide a suitable environment for cellular functioning and serve as a sustained-release delivery vehicle of chondrogenic growth factors and thirdly, signaling molecules and growth factors that stimulate the cellular response and the production of a hyaline extracellular matrix (ECM). The aim of this review is to summarize advances in each of these three fields of tissue engineering with specific relevance to surgical techniques and technical notes.

Cell-Laden and Cell-Free Matrix-Induced Chondrogenesis versus Microfracture for the Treatment of Articular Cartilage Defects: A Histological and Biomechanical Study in Sheep

OBJECTIVE

The aim of this study was to evaluate the regenerative potential of cell-laden and cell-free collagen matrices in comparison to microfracture treatment applied to full-thickness chondral defects in an ovine model.

METHODS

Animals (n = 30) were randomized into 5 treatment groups, and 7-mm full-cartilage-thickness defects were set at the trochlea and medial condyle of both knee joints and treated as follows: 2 scaffolds in comparison (collagen I/III, Chondro-Gide(®); collagen II, Chondrocell(®)) for covering microfractured defects (autologous matrix-induced chondrogenesis), both scaffolds colonized in vitro with autologous chondrocytes (matrix-associated chondrocyte transplantation), or scaffold-free microfracture technique. One year after surgery, cartilage lesions were biomechanically (indentation test), histologically (O'Driscoll score), and immunohistochemically (collagen type I and II staining) evaluated.

RESULTS

All treatment groups of the animal model induced more repair tissue and showed better histological scores and biomechanical properties compared to controls. The average thickness of the repair tissue was significantly greater when a scaffold was used, especially the collagen I/III membrane. However, none of the index procedures surpassed the others from a biomechanical point of view or based on the histological scoring. Collagen type II expression was better in condylar defects compared to the trochlea, especially in those treated with collagen I/III membranes.

CONCLUSION

Covering of defects with suitable matrices promotes repair tissue formation and is suggested to be a promising treatment option for cartilage defects. However, it failed to improve the biomechanical and histological properties of regenerated articular cartilage compared to microfracture alone in an ovine model under the given circumstances.

The elusive path to cartilage regeneration

Numerous attempts have been made to develop an efficacious strategy for the repair of articular cartilage. These endeavours have been undaunted, if not spurred, by the challenge of the task and by the largely disappointing outcomes in animal models. Of the strategies that have been lately applied in a clinical setting, the autologous-chondrocyte-transplantation technique is the most notorious example. This methodology, which was prematurely launched on the clinical scene, was greeted with enthusiasm and has been widely adopted. However, a recent prospective and randomized clinical trial has revealed the approach to confer no advantage over conventional microfracturing. Why is the repair of articular cartilage such a seemingly intractable problem? The root of the evil undoubtedly lies in the tissue's poor intrinsic healing capacity. But the failure of investigators to tackle the biological stumbling blocks systematically rather than empirically is hardly a less inauspicious circumstance. Moreover, it is a common misbelief that the formation of hyaline cartilage per se suffices, whereas to be durable and functionally competent, the tissue must be fully mature. An appreciation of this necessity, coupled with a thorough understanding of the postnatal development of articular cartilage, would help to steer investigators clear of biological cul-de-sacs.