Subdermal Tendon Implant

Abstract

A subdermal tendon implant for use in repairing and reconstructing tendons which is compatible with the human cellular structure and includes the process of making the implant. The subdermal implant is resistant to degeneration and substantially eliminates adhesions allowing full range of motion after healing and includes in its structure a flexible sheeting of chemically inert material sculptured to a desired size and shape and means for anchoring the implant to prevent it from moving axially along the tendon.

Description

SUMMARY OF THE INVENTION

This invention relates to improvements in tendon surgery and more particularly, to improvements in a method and apparatus for repairing and reconstructing tendons.

Accordingly, a primary object of this invention is an improved subdermal tendon implant which is compatible with the surrounding body tissue.

A further object is an improved method and structure which substantially eliminates adhesions between the tendon and surrounding tissues preventing subsequential restrictive fibrosis.

Another object is an implant which is chemically inert and demonstrates a very low order of reactivity eliminating any incapacitating foreign body reactions.

Another object is a novel means for anchoring the subdermal implant to substantially immovable tissue to prevent it from moving axially along the tendon.

Another object is a subdermal implant which keeps the tendon perfectly positioned under normal tension preventing lateral displacement of the tendon.

Another object is an improved structure which causes no restriction in movement or deformity allowing essentially full range of motion after healing.

Another object is an underlay and pulley which do not cause infection or extrusion and are resistant to absorption, hardening and degeneration.

Another object is an implant having nonwetting surfaces which minimize sticking or encrustation allowing the implant to act like a membrane permitting the tendon to move freely across its surface.

Another object is an improved method of constructing a subdermal implant which may be quickly positioned during the operative stage and is tough and durable after the operative stage.

Another object is a tendon implant which is adaptable to a variety of clinical situations including tendolysis, primary repairs, and secondary reconstruction and grafts.

Other objects and advantages will be apparent from the ensuing specification and drawings for this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated by the accompanying drawings wherein:

FIG. 1 is a perspective view with portions removed showing a subdermal underlay in position;

FIG. 2 is an enlarged end sectional view of the underlay shown in FIG. 1;

FIG. 3 is a perspective view with portions removed showing a subdermal pulley in position;

FIG. 4 is an enlarged end sectional view of the pulley shown in FIG. 3;

FIG. 5 is a perspective view with portions removed showing both a subdermal underlay and pulley in position;

FIG. 6 is a top view of a subdermal underlay;

FIG. 7 shows a diagrammatic view of the method of constructing an underlay;

FIG. 8 shows a top view of a pulley with portions removed for clarity; and

FIG. 9 shows a mesh material used in constructing a subdermal pulley.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In tendon surgery the problem of subsequential restrictive fibrosis due to adhesion is omnipresent and frequently severely limiting in clinical results. With this problem in mind, coupled with the knowledge that healing and restitution of tendons occurs almost solely from the surrounding tissue, research was begun. After extensive testing and obtaining data on various tendon accessories the subdermal tendon implant 10 disclosed in this application was developed. Then numerous laboratory experiments were conducted using the subdermal tendon implant with canine preparations and ultimately with specific clinical applications. The results were extremely favorable with both groups experiencing virtually no adhesions or fibrosis retaining essentially full range of motion. In addition no infections or extrusions developed during the postoperative period.

FIGS. 1 through 5 show the subdermal tendon implant 10 as it is used in tendon surgery on a finger 12. FIGS. 6 through 9 disclose the implant in more detail and in particular show the process of making the implant. The subdermal tendon implant 10 basically includes a flexible sheeting 14 of chemically inert material sculptured to a desired size and shape with a mesh or netting 16 bonded to a surface of the sheeting material.

FIGS. 1 and 2 show an operative use of a subdermal tendon implant sculptured to form an underlay 18 taking the shape of an elongated member. The underlay preferably has a mesh or netting 16 bonded to an inferior surface 30 of the sheeting 14. The sheeting is approximately 0.020 inch thick and may be reinforced to provide added strength and prevent stretch. The underlay 18 may be fabricated or trimmed to a width of approximately 1.0 cm. and has lengths ranging from about 1.0 to 2.5 cms.

The underlay 18 is positioned under areas of tendon exploration or repair to eliminate adhesions and later anchorage. As shown in FIGS. 1 and 2 the surface containing the mesh or netting 16 is placed inferiorly against substantially immovable tissues 20 such as a bone or joint capsule. The mesh or netting material causes fibroblastic infiltration to occur thereby securing the implant 10 in place with periosteal attachment. This is extremely important as it allows the tendon to move across the underlay without causing displacement. It is also important to note that this leaves the nonreactive superior surface 22 of the sheeting material opposite the explored or repaired tendon 24.

FIGS. 3 and 4 show an operative use of the subdermal tendon implant 10 sculptured to the size and shape of a pulley 26. The pulley is also an elongated member having shackle end portions 28 linked together by a central portion. The pulley is sutured into place over the tendon 24 with the mesh or netting 16 bonded to the inferior surface of the shackle ends 28 as best shown in FIGS. 8 and 9. As is true with the underlay 18, the mesh material of the pulley causes fibroblastic infiltration to occur thereby securing the implant to adjacent body tissues.

The pulley 26 is fabricated from the same sheeting material as the underlay 18, however, the thickness of the material is normally less than that of the underlay and is about 0.007 inch. The lengths of the pulley 26 range from about 1.0 to 1.5 cms.

The pulley 26 is devised to aid tendon placement and balance keeping the tendon perfectly positioned under normal tension. In addition it should be noted that the portion of the pulley 26 touching the tendon 24 is nonreactive sheeting material keeping the tendon free of fibrosis or adhesion for the distance of excursion under the pulley.

FIG. 5 shows the operative use of both an underlay 18 and pulley 26 on a finger 12. It should be pointed out that the underlay and pulley may be used together as shown in FIG. 5 or may be used separately as shown in FIGS. 1 through 4. In addition the chemically inert surface of the sheeting material is always adjacent the tendon 24 with the surface containing the mesh material adjacent body tissues 20 such as the bones shown in FIG. 5.

FIGS. 6 through 9 disclose the subdermal tendon implant 10 in more detail. In particular FIG. 6 shows a top view of the inferior surface 30 of an underlay 18 with the mesh or netting 16 bonded to the flexible sheeting.

The sheeting 14 is preferably made from a chemically inert material which is compatible with the human cellular structure. In addition it is preferable that the sheeting 14 have nonwetting surfaces which minimize sticking or encrustation. Further the material should be resistent to absorption, hardening and degeneration and as previously mentioned contains the quality of nonadherence to tissue. A flexible silicone elastomer manufactured by Dow Corning sold under the trademark Silastic has been found to substantially meet the above-mentioned qualifications. In addition other medical-grade silicone elastomers, or materials similar to Silastic, or equivalents thereof have been found as satisfactory material for the sheeting.

As previously mentioned the sheeting 14 is preferably reinforced with a polyester material or similar synthetic fiber to eliminate stretch and permit suture attachment.

FIG. 7 shows in detail the process of making a subdermal tendon implant 10. The sheeting 14 is fabricated or sculptured to the desired size and shape and the mesh 16 is bonded to a surface of the sheeting by an adhesive 32. The adhesive is preferably a medical adhesive such as silicone adhesive. When this is completed the implant is ready to be placed subcutaneously with the smooth, nonreactive superior surface 22 of the sheeting adjacent the repaired or explored tendon and the inferior surface 30 containing the mesh material adjacent body tissues for rapid fixation.

FIG. 8 shows a pulley 26 with mesh 16 secured to the inferior surface of one of the shackle ends 28. The mesh 16 to be secured to the other shackle end 28 is shown in FIG. 9 and may be made from polyester netting or similar synthetic fiber. As mentioned previously the polyester netting causes fibroblastic infiltration through the mesh 16 thereby securing the implant to adjacent tissues.

The use, operation and function of this invention are as follows:

After constructing this invention the subdermal tendon implant 10 is ready for use in tendon surgery. The nonreactive sheeting surface 22 is positioned opposite the explored or repaired tendon while the mesh surface 30 is placed inferiorly against adjacent tissues for rapid fixation. In particular, the subdermal pulley 26 is sutured into place over the tendon 24 as shown in FIGS. 3, 4 and 5 while the subdermal underlay 18 is placed under the tendon 24 and sutured into place as shown in FIGS. 1 and 2. It is important to note that the subdermal tendon implant will be firmly attached via the bonded mesh 16 by the third postoperative week.

The subdermal implant 10 provides a medical device which is adapted to keep the tendons perfectly positioned and free to fibrosis or adhesions. In addition the implants do not cause infections or extrusions while permitting the patient to retain essentially full range of motion after the operation.

In addition to being safe and free from incapacitating foreign body reaction the subdermal implant may be quickly positioned during the operation with results that are more reliable than previous experiences with autogenous fascia or connective tissues. Further the invention described in this application may be utilized for a wide variety of difficult clinical situations, including tendolysis, primary repairs and secondary reconstruction or grafts.

Claims

I claim:

1. A subdermal tendon implant for use in tendon surgery including:

an elongated member having a smooth, nonwetting inferior surface and a smooth, nonwetting superior surface, said elongated member adapted to be positioned between a viable, constantly moving, damaged tendon and the surrounding body tissue, and being made from a flexible, substantially inert material that is compatible with human cellular structure;

a mesh material bonded to only a portion of the inferior surface of the elongated member, said mesh material adapted to contact substantially immovable body tissue with the remaining smooth, nonwetting inferior surface adapted to contact the damaged tendon; and

suture means for anchoring the implant to the substantially immovable body tissue to prevent it from moving axially along the constantly moving, damaged tendon during the early stages of healing.

2. The structure of claim 1 further characterized in that the elongated member is made from a reinforced, medical-grade silicon elastomer.

3. The structure of claim 1 further characterized in that the mesh material is made from a polyester netting adapted to cause fibroblastic infiltration through the mesh material securing the subdermal tendon implant to the substantially immovable body tissue by periosteal attachment.

4. The structure of claim 1 further characterized in that the elongated member is sculptured to form at each end a shackle portion linked together by a central portion, said mesh material being bonded only to the inferior surface of the shackle end portions.

5. The process of making a subdermal tendon implant from a flexible sheeting of substantially inert, nonreactive material having a smooth exterior surface, the process including the steps of:

sculpturing the flexible sheeting to a desired size and shape;

bonding a mesh material to at least a portion of one surface of the flexible sheeting;

positioning the flexible sheeting with the bonded mesh material subcutaneously between a damaged tendon and the surrounding body tissue so that a portion of the smooth exterior surface of the sheeting material rests against the damaged tendon and the portion of the surface containing the mesh material rests against substantially immovable body tissue; and

fixedly securing the flexible sheeting with the bonded mesh material to the substantially immovable body tissue to anchor the subdermal tendon implant for rapid fibrous fixation.

6. The process as set forth in claim 5 further including the initial step of sculpturing the flexible sheeting to form an elongated member.

7. The process as set forth in claim 5 further including the initial step of sculpturing the flexible sheeting to form at each end a shackle portion linked together by a central portion.