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Yongyudh Vajaradul
Siriraj Hospital, Mahidol University, Bangkok, Thailand

Hendadura Piyanandana Jayathilaka
Medical Lab Technologist
Sri Lanka Model Human Tissue Bank

Introduction:

Bone substitutes prepared from bovine bone decalcified by muriatic acid treatment has already been used to fill small bone defect more then 100 years ago. Bone substitute materials can be grouped into the main group, they are 1). Calcium phosphate like Osporum (deproteinize bone), Kiel Bone (organic bone), Oswestry bone marketed today as macroporous Bio-OssR and EndoboneR.

The ideal bone substitute should be non-toxic, biocompatible, able to support the loads subjected on the host bone; bioactive, osteoinductive, allows new bone ingrowth or ongrowth, disappear with the same speed as the new growth occurs, close to biomechanical values of the natural bones, easy to handle and moldable or shapeable preoperative.

Some beneficial properties of bone substitute materials are low inflammatory reaction and normally good bone formation. The disadvantages includes slow and inconstant resorption and osteogenic properties (Burwells, 1969) and they could not be used to bridge defects. Also, their manufacturing is troublesome. To solve the manufacturing problem of the biomaterial, easy to handle the grafts and ready to use, the Bangkok Biomaterial Center has commenced on a project of manufacturing Bone Tablets from Human Bone Allografts. These allografts shall be consisting of bones like Femoral heads and tibial shavings discarded after joint arthoplasty procedures. In order to establish the process and laboratory trials as well as a comparative model to determine the compression strength and other bio-mechanical properties of this product, the Center started making bone tablets with a bovine bone model. This will enable to establish the process of manufacturing as well serve as a comparative model to Human Bone Tablets, which is the desired final product.

 

One of the major disadvantage of freeze dried bone allografts is that they are brittle in nature and do not have sufficient compression strength to sustain the body load on the host-allograft juncture. There has been many attempts world wide for various kind of bone substittues and to some extent sucess has also been achieved. The Bangkok Biomaterial Center, along with its instrinc strength of a full fledge laboratory and the dynamic leadership of Prof. Yongyudh Vajaradul has commenced on the production of Radiation Sterilized Freeze Dried Bone Allograft Tablets. The major area of applications of these bone substitute products are stone brick support in spinal deformities, dental cavities, oral & maxillofacial surgeries and filling up of holes caused due to bone loss. This project was in the pipe-line for more than 2 years due to huge overload of on-going research works. However in August 2000, the bone tablet project study was launched. A unique feature of this manufacturing cum-research project is that the inital phase i.e Bovine Bone Model work has been entirely done by the International Atomic Energy Agency Fellows of the 2nd batch Master Degree Course.

 

OBJECTIVES

Include production of bone tablets in the product line of Bangkok Biomaterial Center.

To conduct comparative study of biomechanical properties of human and bovine bone tablets.

To determine the clinical effectiveness of bone tablets.

To study the feasibility of commencing production of bone tablets in industrial scale.

To establish the process and prepare a blue print of resources for manufacturing, chemical and bio-mechanical laboratory testings and clinical trials.

To keep with the trend of research & development and innovative products from Bangkok Biomaterial Center.

To promote the cause of research & developments in the field of Tissue Banking.

To orient and impart practical training to the Advance Training Course -Cum- Master Degree students (IAEA Fellows) through the system of conducting on-hand research & developments in advance topics of radiation sterilization and tissue banking.

 

PROCEDURE

Manufactuing stages and other technical details of this product are covered under the product patent and thereby all the details cannot be disclosed at this stage. However it is expected once the patent process is completed, the complete details shall be presented as a scientific paper in tissue banking journals and text books. However in the interest of our valuable readers, we are tempted to shed a little light on the manufacturing procedure but only on the Bovine Bone Tablet manufacturing.

Material and Methods

Bovine Bone. Bovine bone is purchased from the market, put into ice container, and transported to Bangkok Biomaterial Center.

Chemical.

Hydrogen peroxide 3%. 100 ml of 6% Hydrogen Peroxide diluted with bio-filtered water until 200ml.

Sodium Hypo-Chlorite 0.5%. 17.5 ml of 5.7% Sodium hypo-Chlorite diluted with bio- filtered water until 200 ml

Bio-filtered water

70% of ethanol

 

Equipment and Instrument

Scalpel and blade

Forceps

Bone cutter

Scissors

Band saw machine

Varnier caliper

Washing machine

Ultrasonic cleaner

Bone grinding machine

Freeze Drier machine

Vacuum sealing machine

Sterile PE bag

Sterile Tray

Beaker glass

Measuring Cylinder

Compressor machine for mold the bone (KORSCHR)

 

WORKING STEPS

All the soft tissue and fat from bovine bone (ribs) are removed by using scalpel.

The cleaned bone is cut into 1 cm of length by using the band saw machine and re-cut 2 times longitudinally to 3 pieces.

The cut bone is washed with bio-filtered water in washing machine for 15 minutes and the washing is repeated again 3 times.

The cut bone is soaked in 200 ml of 3% Hydrogen Peroxide for 30 minutes and then washed with bio-filtered water in washing machine for 15 minutes.

Cleaned bone is soaked with bio-filtered water and cleaned in an ultrasonic water bath at room temperature for 15 minutes.

The bone is then soaked in 0.5% of Sodium hypo-Chlorite for 15 minutes and then washed with biofiltered water in ultrasonic cleaner for 15 minutes and this process is repeated again 3 times.

Bone is grinded with a bone grinder and the ground bone is divided into two group,the they are freeze-dried and non freeze dried.

The bone is then sent to the pharmaceutical factory for moulding into tablet form.

Mechanical and chemical properties of the bone tablets are determined at KMIT and MTEC.

 

CONCLUSIONS

It is expected that this innovative product of bone tablet from Bangkok Biomaterial Center will revolutionize the clinical applicationof allografts and will be a step into the new millenium of tissue banking.

 

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Bovine bone being cleaned of soft tissue                             Cleaned bone being measured before cutting

 

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Cut bone chip put in the washing machine                  Cleaned bone being treated with Hydrogen peroxide

 

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Cleaning in ultrasonic bath with Hydrogen peroxide               Overnight treatment in Hydrogen peroxide

 

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Cleaning in ultrasonic bath                                   Sodium Hypochlorite treatment

 

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Washed and clean bone chips                             Bone chips being put in the grinding machine

 

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2nd Batch bone chips lyophilized and vacuum packed              Round bone tablet sample

 

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Round bone tablet sample without any mixture       Oval bone tablet with & without skimmed milk powder

 

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Bone tablet of various type packed in blister packing      Compression test of round bone tablet in progress 

 

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Compression of oval bone tablet in progress

The IAEA fellows, the BBC and KMIT teams after completing the compression test

                          

                                                                                               

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Moisture content test machine

IAEA fellow Mr. Jayathilaka conducting the moisture content test at MTEC

                       

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