Absorbable Implants and Methods for Their Use in Hemostasis

Abstract

The present invention relates to mechanically hemostatic body-absorbable compositions having a putty-like consistency comprising a finely powdered polysaccharide and a biocompatible liquid comprising one or more block copolymers of ethylene oxide and propylene oxide.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. provisional application No. 60 / 504,978 filed Sep. 23, 2003STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002](Not Applicable)REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON COMPACT DISC (SEE 37 CFR 1.52(e)(5))[0003](Not Applicable)BACKGROUND OF THE INVENTION[0004]1. Field of the Invention[0005]The invention relates to the management, treatment, therapy, and beneficial control of osseous conditions such as hemorrhage and defects, through the use of materials having various viscosities, cohesive strengths, and consistencies, most particularly putty-like materials as well as creams, pastes, ointments, lotions, and gels. More particularly, various novel, surgically implantable, absorbable formulations, which may contain absorption accelerants, bone growth-inducing materials, anti-infective or anti-neoplastic agents to reduce the risk of ...

AI Technical Summary

Benefits of technology

[0027]A sterile, absorbable bone hemostatic agent, that is, a material that will provide virtually immediate surgical hemostasis and also will absorb in the body after a relatively short period of time without compromising hemostasis efficacy, would have significant medical advantages over presently available materials. It would minimally inhibit osteogenesis and subsequent bone healing. Moreover, bone-healing adjuvants such as growth factors, particularly, for example, platelet derived growth factor (PDGF) and / or bone morphogenic proteins (BMPs) and others, could be added to the formulations to stimulate the bone healing process. Furthermore, adding agents such as collagen, demineralized bone matrix (DBM), and / or hydroxyapatite could make the hemostatic material beneficially osteoconductive and osteoinductive. The addition of a suitable anti-infective agent such as antibiotics typified by tobramycin and gentamicin or bacteriostatic and bacteriocidal materials such as iodine, silver salts, colloidal silver, or the like serve to reduce the potential for infection, particularly in contaminated open wounds such as compound fractures. The addition of colorants would aid in visibility during the operative procedure. The addition of radiopaque substances allows the observation of post-operative sequelae using radiography. The addition of chemotherapeutic agents or radionuclides is useful when the putty is used, for example, in bone cavities arising from tumor resection. Analgesic compounds to reduce pain, and vasoconstrictors and blood clot-inducing agents to reduce hemorrhage, are useful additives.

[0029]The invention provides implantable, appropriately absorbable, biocompatible, putty-like compositions that are useful as mechanical hemostatic tamponades for the control of osseous hemorrhage arising from surgical intervention or trauma and for providing an osteoinductive matrix to foster improved bone healing.

[0034]The anti-infective agent, which may be an antibiotic, a bacteriostatic or a bacteriocidal material, may be added to the putty-like mass or may be reversibly bound to additives, e.g. gelatin or collagen, which are to be contained within the putty. For example, using iodine as the anti-infective agent, a complex of iodine with gelatin, collagen or PVP may be used. In addition, colloidal silver, silver salts, or silver complexes with gelatin or other polymers may be used. Still further, antibiotics, in addition to being capable of being added to the putty as described above, may be added as part of a delivery system, preferably as part of a component of the putty. In particular, gentamicin, bound to powdered collagen, is an example of a useful antibiotic release system. Similarly, anti-neoplastic agents may be added to the putty-like composition in the same manner, preferably as a free agent, to provide an effective anti-tumorigenic material. Analgesics to reduce pain, blood clot-inducing agents to act as chemical hemostatic agents, and anti-inflammatory agents, may also be added. Furthermore, radiopaque components may be added to allow radiographic observation and colorants to improve intra-operative performance.

Problems solved by technology

The first of these is the occurrence of osseous hemorrhage.

The second issue is that of bone growth to promote healing (osteogenesis) of the traumatized bone.

None of these techniques promotes osteogenesis to any significant extent.

These compositions are designed for inducing osteogenesis and healing in the defect but, because of their consistency, non-cohesiveness and other attributes of their composition, they do not reliably adhere to injured bone and are not effective hemostatic agents.

The disadvantages of makeshift devices employing, for example, oxidized cellulose as well as the tissue-destructive use of electrocautery (discussed below) are not satisfactory alternatives.

Because available bone waxes are not absorbable and reside indefinitely where they are placed by the surgeon, they act as permanent physical barriers that inhibit osteogenesis, thereby preventing or slowing bone healing.

If such infection does occur, it is usually chronic and difficult to treat using conventional anti-infective therapy and re-operation, to surgically excise the infected site, often becomes necessary.

For these reasons, commercially available bone waxes do not enjoy widespread orthopedic use.

However, they are not effective hemostatic products for bone because of their inappropriate physical form (knitted fabric) and are too difficult to use effectively on cut bone because of lack of adherence within the bone pores.

The use of electrocautery, which thermally sears oozing blood vessels closed, is time-consuming and produces widespread tissue damage which may delay osteogenesis as well as allow soft tissue in-growth that interferes with normal bone union, presenting difficult problems for orthopedic surgeons in general and spine surgeons in particular.

Collagen in various forms, alone or in combination with fibrin and suspended in various delivery vehicles has been proposed as a bone hemostatic agent but problems with, for example, storage stability, cohesiveness, and biocompatibility have prevented practical fruition.

The adaptation of synthetic absorbable polymers to this application has not succeeded, apparently because of technical difficulties in suitably formulating hydrolytically unstable synthetic absorbable polymers into practical products with reasonable package shelf life, useful handling properties and acceptable biocompatibility and absorption rates.

Attempts at providing absorbable bone hemostatic agents have not been completely successful.

A microcrystalline collagen lyophilized sponge (U.S. Pat. No. 6,454,787), designed for soft tissue hemostasis, is not as well-suited for bone bleeding control.

A hemostatic agent employing polylactide (U.S. Pat. No. 4,186,448), lactide / glycolide oligomers (U.S. Pat. Nos. 5,143,730, 6,420,454), moldable polymer blends (U.S. Pat. No. 5,641,502), absorbable, hydrogel-forming synthetics (U.S. Pat. No. 6,413,539) are not easily adapted to bone hemostasis.

Polydioxanone (U.S. Pat. No. 4,443,430) synthetic absorbable polymer materials are difficult to employ because of their relative instability in biocompatible, protonic delivery vehicles.

However, this technology, together with similar absorbable compositions, described in U.S. Pat. No. 4,439,420 and U.S. Pat. No. 4,650,665, are deficient because they are designed for drug delivery over extended absorption time periods not thought optimal for rapid bone healing and because they contain dextran, a polysaccharide presently believed to be a toxicologically unacceptable implant material.

However, it is probable that the surface-active composition may easily be washed away after implantation.

No information or data concerning efficacy as a hemostatic device were presented and apparently no experiments were done to determine the absorption rate of the material when actually used as a bone hemostatic device.

In addition, the preferred composition described in the patent contains a component, i.e., dextran, which is not acceptable toxicologically.

Finally, 4,439,420 compositions are “completely free of fibrous materials” which may be a significant disadvantage for optimum osteogenesis, a desirable characteristic for a bone hemostatic device.