Bone Allografts impregnated with Tobramycin

Treatment of chronic bone infection is considered one of the most challenging procedures in orthopaedic surgery. Reduced susceptibility for traditional antibiotic therapy and extensive bone defects make surgical intervention mandatory for a successful outcome.

The EUROPEAN CELL and TISSUE BANK(ECTB/ÖGGV) has therefore developed a new product which makes biological reconstruction of bone defects and effective local prevention of infections and reinfections with a single surgical intervention feasible.

Human bone allografts are cleaned and processed using modern technologies. This Process allows to meet the increasing demand for safe allografts with local antimicrobial activity. The cleaning process is a gentle, safe and efficient cleaning process throughout the whole bone matrix even for massive allografts.

Its virus-inactivating effect is validated. Lipids and cellular components are removed completely. Collagen and osteoinductive proteins are treated with care. Mechanical properties are mainly unmodified. Thus incorporation in the recipient is faster and more complete. In addition, these characteristics are combined with local antimicrobial activity. 

The allografts are impregnated with antibiotics in a special process that leads to a product with slow elution of antibiotics. Thus higher local antibiotic concentration and longer lasting antimicrobial activity is achieved better than with any other method (16).

The resulting product OSmycin® T offers not only ultimate safety and quality, it makes debridement, complete dead space management, biological reconstruction of bone defectsas well as implantation of endoprostheses in debrided bone in a one stage approach feasible. 

Therefore stress for the patient, treatment periods and treatment expenses can be reduced distinctively.

Why Tobramycin?

Tobramycin is likely to penetrate Glycocalices and in high concentrations and shows a strain dependent biofilm activity (1, 2, 10). Tobramycin shows among the lowest cytotoxic effect of commonly used antibiotics (11).

Indications

OSmycin ® T is favourably used as filler after debridement of osseous sites infected with participation of gram-negative bacteria. Indications include osteitis after trauma or surgery,

hematogenic osteomyelitis and infected joint replacement. In cases of mixed infections (gram-positive and gram-negative) and chronic infections with inexplicit cultures combination with OSmycin® V is advisable, taking advantage of the synergistic activity of the two antibiotics (9, 15).

OSmycin® T is not suitable for treatment of soft tissue infection.

Innovative Processing Method for Innovative Products

The bone tissue is procured, tested and processed according to the EU Directives and Austrian Tissue Law Österreichisches Gewebesicherheitsgesetz.

The essential characteristic of processing is that supercritical CO2 technology is used, currently the most gentle and effective technology of cleaning bone allografts. 

Supercritical CO2 has the ability of high penetration throughout the whole bone matrix combined with high potential to solve lipids and cellular components associated with lipids (6).

Using this technology lipids and bone marrow are removed, while the collagen matrix consisting of collagen and minerals is mainly maintained. Osteoinductive proteins are treated with care. The native composition of the matrix promotes osteocunduction (8). 

The virus-inactivating effect of the process has been validated several times (7).

By removing fat and cellular components antigens are removed (12) and immunological reactions are avoided.

The purified matrix is impregnated with high loads of tobramycin, an aminoglycoside with super activity against most

 

 

 

 

 

 

 

 

 

gram-negative bacteria commonly found in bone infection. Due to the proprietary impregnation technique tobramycin is deposited throughout the whole graft, mainly in the lacunae of the spongy matrix. OSmycin® T elutes tobramycin slowly. 

Thus higher local antibiotic concentration and longer lasting antimicrobial activity is achieved better than with any other method. Release of the antibiotic is completed after several weeks and such is not likely to create resistances or initiate the formation of small colony variants. 

Concentrations in the immediate surrounding reach levels between 100 and 1000 times the levels reachable with systemic antibiotic therapy (16). Because of the unique properties of supercritical CO2 this innovative processing technology enables efficient and gentle cleaning of human bone allografts – also for cortical and massive allografts – and guarantees ultimate biological safety and quality of the products. Due to the special impregnation technique

tobramycin is eluted slowly. Higher local antibiotic concentration and longer lasting antimicrobial activity is achieved better than with any other method.

1cc (0.8g) OSmycin® T bone chips are impregnated with 180 mg of Tobramycin

10cc (1.8g) OSmycin® T bone chips are impregnated with 400 mg of Tobramycin

30cc (5.4g) OSmycin® T bone chips are impregnated with 1.200 mg of Tobramycin

Safe, Clean and Efficient!
Advantages

· The validated virus-inactivation grants ultimate safety. (7)

· Extraction of lipids and cellular components takes place deep into the bone matrix.

· The collagen matrix consisting of collagen and minerals is mainly maintained and osteoinductive proteins are treated with care.

· The native composition of the matrix promotes osteocunduction. (8)

· The mechanical and structural qualities are mainly equal to those of unprocessed bone tissue. (13)

· U sing impaction grafting the primary stability of purified allografts is favourable compared to not purified, fatty transplants. (4, 5)

· The cleaning process uses only non-toxic solvents.

· Processed chips, femoral heads and blocks have no immune response of the recipient.

· I corporation at the recipient therefore takes place faster and more complete. (3, 8, 14)

· Due to the special impregnation technique tobramycin is eluted slowly. Higher local antibiotic concentration and longer lasting antimicrobial activity is achieved better than with any other method. (16)

· Concentrations of tobramycin in the immediate surrounding reach levels between 100 and 1000 times the levels reachable with systemic antibiotic therapy. (16)

· Release of the antibiotic is completed after several weeks and such is not likely to create resistances or initiate the formation of small colony variants.

· The allografts are double packaged in blisters or glass vials and sterilized.

· Storage takes place under room temperature conditions for up to 3 years.

· The products are easy to handle and user-friendly shaping saves time in the OR.

Application and Bone Graft Impacting

Radical debridement is a prerequisite for cure in any orthopaedic infection. All unvascularized bone must be removed down to slightly bleeding surfaces. The site should be rinsed thoroughly with saline until all macroscopically visible debris is cleared. Osseous dead space and bony defects are then filled up with OSmycin® T, using mild to moderate impaction forces, depending on the required effect. Mild impaction will result in accelerated incorporation, moderate forces increase primary stability. Insertion of osteosynthetic material or endoprostheses may precede or follow the grafting procedure, according to local circumstances. Drainage preferably should be performed without suction.

 

 

Literature:

Literature

1. Anwar H, Costerton JW. Enhanced activity of combination of tobramycin and piperacillin for eradication of sessile biofilm cells of Pseudomonas aeruginosa. Antimicrob Agents, Chemother 1990;34-9:1666-71.

2. Anwar H, Strap JL, Costerton JW. Eradication of biofilm cells of Staphylococcus aureus with tobramycin and cephalexin. Can J Microbiol 1992;38-7:618-25.

3. Aspenberg P, Thoren K. Lipid extraction enhances bank bone incorporation. An experiment in rabbits. Acta Orthop Scand 1990; 61-6:546-8.

4. Cornu O, Bavadekar A, Godts B, Van Tomme J, Delloye C, Banse X. Impaction bone grafting with freeze-dried irradiated bone. Part I. Femoral implant stability: cadaver experiments in a hip simulator. Acta Orthop Scand 2003; 74-5:547-52.

5. Cornu O, Bavadekar A, Godts B, Van Tomme J, Delloye C, Banse X. Impaction bone grafting with freeze-dried irradiated bone. Part II. Changes in stiffness and compactness of morselized grafts: experiments in cadavers. Acta Orthop Scand 2003; 74-5:553-8.

6. Fages J, Marty A, Delga C, Condoret JS, Combes D, Frayssinet P. Use of supercritical CO2, for bone delipidation. Biomaterials 1994; 15-9:650-6.

7. Fages J, Poirier B, Barbier Y, Frayssinet P, Joffret ML, Majewski W, Bonel G, Larzul D.Viral inactivation of human bone tissue using supercritical fluid extraction. Asaio J 1998; 44-4:289-93.

8. Frayssinet P, Rouquet N, Mathon D, Autefage A, Fages J. Histological integration of, allogeneic cancellous bone tissue treated by supercritical CO2 implanted in sheep bones. Biomaterials 1998; 19-24:2247-53.

9. Gonzalez Della Valle A, Bostrom M, Brause B, Harney C, Salvati EA. Effective bactericidal, activity of tobramycin and vancomycin eluted from acrylic bone cement. Acta Orthop, Scand 2001;72-3:237-40.

10. Gristina AG, Costerton JW. Bacterial adherence to biomaterials and tissue. The significance of its role in clinical sepsis. J Bone Joint Surg Am 1985;67-2:264-73.

11. Miclau T, Edin ML, Lester GE, Lindsey RW, Dahners LE. Bone toxicity of locally applied, aminoglycosides. J Orthop Trauma 1995;9-5:401-6.

12. Thoren K, Aspenberg P, Thorngren KG. Lipid extraction decreases the specific immunologic response to bone allografts in rabbits. Acta Orthop Scand 1993; 64-1:44-6.

13. Thoren K, Aspenberg P, Thorngren KG. Lipid extracted bank bone. Bone conductive, and mechanical properties. Clin Orthop Relat Res 1995-311:232-46.

14. Thoren K, Aspenberg P. Increased bone ingrowth distance into lipid-extracted bank, bone at 6 weeks. A titanium chamber study in allogeneic and syngeneic rats. Arch Orthop, Trauma Surg 1995; 114-3:167-71.

15. Watanakunakorn C, Tisone JC. Synergism between vancomycin and gentamicin or, tobramycin for methicillin-susceptible and methicillin-resistant Staphylococcus aureus strains. Antimicrob Agents Chemother 1982;22-5:903-5.

16. Winkler H, Janata O, Berger C, Wein W, Georgopoulos A. In vitro release of vancomycin, and tobramycin from impregnated human and bovine bone grafts. J Antimicrob, Chemother 2000;46-3:423-8.