Tendon prosthesis and method of manufacturing the same

Biocompatibility is an essential aspect of the medical device industry. Biocompatibility testing ensures that devices do not contain materials or substances that could be harmful to patients during initial use or over the course of time. Biocompatibility tests can be used to detect many possible negative side effects of a product on patient. These may include effects on cells and physiological systems, tissue irritation and inflammation, immunological and allergic reactions and the possibility of cellular mutations leading to cancer. Email:marketing@medicilon.com.cn web:www.medicilon.com

A knitted ligament prosthesis (100) has at least two knitted sections (112, 114), where each knitted section has at least one row of fiber. The knitted prosthetic device also has at least one intra- articular section (122) disposed between the at least two knitted sections. In addition, the at least one mtra-articular section has at least one single continuous fiber traversing the at least one mtra-articular section and the at least two knitted sections, where the at least one single continuous fiber forms a plurality of traverses extending between the at least two knitted sections.

The sericin may be extracted, or removed, from the fibroin fibers before alignment into a yarn or at a higher level in the hierarchical geometry of the fiber construct. The yarn is preferably handled at low tension, i.e. the force applied to the construct does not exceed the material's yield point during any processing step. However, if the yarn is to be employed as a non cyclic-load bearing yarn in the device, the material's yield may be exceeded. Moreover, the yarn is handled with care after the sericin is removed. Processing equipment is likewise configured to reduce abrasiveness and sharp angles in the guide fixtures that contact and direct the yarn during processing to protect the fragile fibroin fibers from damage. For example, extraction residence times may range approximately from instantaneous submersion to ten hours. In general, the extraction is slow enough to minimize damage to the exposed filaments and is determined by the configuration of the yarn being treated. When a silk fiber construct with multiple fibers organized in parallel has been extracted under these conditions, a "single" larger sericin free yarn resulted. In other words, individual fibers cannot be separated back out of the construct due to the mechanical interaction between the smaller fibroin filaments once exposed during extraction. Furthermore, due to the mechanical interplay between the sericin-free micro filaments, extraction of twisted or cabled yarns typically results in less "lively" yarns and structures. As a result, a greater degree of flexibility exists in the design of the yarns and resulting fabrics; for example, one may employ higher twist per inch (TPI) levels, which may normally create lively yarns that are difficult to form into fabrics. The added benefit of higher TPIs is the reduction in yarn and fabric stiffness, i.e. matrix elasticity may be increased.

It should be appreciated that the prothestic devices of the present invention, are not limited to the use of silk, and may be formed from a strong polymer that is capable of being knitted. In particular, the polymer is preferably bioresorbable to allow substantial in-growth, both in the device itself and within and around the bone tunnels to maintain to improve the strength of the device- tissue construct over time. The process of in-growth is discussed in further detail hereinbelow.

Moreover, embodiments may be processed with a surface treatment, which increases material hydrophilicity, biocompatibility, and handling for ease of cutting and graft pull-through, as well as anti-microbial and anti-fungal coatings. Specific examples of surface treatments include, but are not limited to, plasma modification, fibronectin, denatured collagen, collagen gels, peptides with a hydrophilic and a hydrophobic end, covalently linked proteins and peptides, physically bound and chemically stabilized peptides and gels, DNA/RNA aptamers, Peptide Nuclei Acids, avimers, modified and unmodified polysaccharide coatings, carbohydrate coating, anti-microbial coatings, anti-fungal coatings and/or phosphorylcholine coatings. The preferable concentration range for smaller proteins and peptides (in the range of 1000 kDa to 20,000 kDa) is from O.Olμg/mg device to 100 μg/mg device. For larger proteins, a preferred concentration range is from O.Olmg/mL to 5mg/mL.

In general, embodiments of the present invention employ materials which that have undergone extensive biocompatibility testing in accordance with the ISO- 10993 recommendations for a permanent implantable device. Generally, the materials are biocompatible, non-cytotoxic, non- irritating, non-toxic, non-pyrogenic, non-mutagenic, non-clastogenic, nonhemolytic, and non-antigenic with no evidence of sensitization or complement activation.

Referring again to FIG. 1, knitted sections 112 and 114 may be formed from a weft-knitted fabric or a warp-knitted fabric. One or more single continuous weft insertion yarns 123 form the intra-articular section 122 with one or more longitudinal fibers connecting the knitted sections 112 and 114. Each of the knitted sections 112 and 114 has one or more rows, also known as courses. As shown in FIG. 16, the rows 75 may be made of a plurality of loops 76. The single continuous weft insertion yarns 123 are laid into, or received by, one or more courses in each knitted section 112 and 114 and traverse across the knitted sections 112 and 114.

A single continuous weft insertion yarn 123 in ligament prosthesis 100 refers to a single yarn that traverses the intra-articular section 122 and the knitted sections 112 and 114 to form a plurality of traverses extending between the knitted sections 112 and 114. For instance, the continuous yarn 123 may be laid in and traversed in a repetitive S-shaped or Z-shaped pattern, extending from the first knitted section to the second knitted section where it pivots and returns back to the first knitted section where it may pivot again and repeat the sequence several times. Examples of an S-shaped or Z-shaped pattern are described further below. In other words, each traverse of the single continuous yarn 123 is a continuation of the previous traverse extending in the opposite longitudinal direction. In this way, a single continuous yarn 123 with more than one traverse may connect the two knitted sections 112 and 114 and form the intra-articular section 122. The pivot points are not limited to any one location.

Of course, the ligament prosthesis 100 may contain more than one single continuous yarn 123 laid in and traversed in a repetitive pattern extending between the first knitted section and the second knitted section, thereby connecting the two knitted sections 112 and 114 with more than one traverse from more than one single continuous yarn 123. The traverses of the multiple single continuous yarns 123 may extend in the same direction, opposite directions, or any combination thereof.