Three Dimensional Bone Printing

Bone restoration for patients is sometimes hard to be attained especially when there are infections or trauma, this had been a challenge to achieve in the past years. As there are complications to the conventional autografts or allografts, these challenges have led to the emerging of a new way to provide healthy bone tissues that are strong and patient-compatible. 

Three Dimensional Bone Printing technique is used for Patients requiring skeletal augmentation, for example, Facial asymmetry, Patients with facial trauma, Infections, Trauma, Congenital diseases.They are usually fit to be aided with three-dimensional bone printing procedure to restore normal human anatomy and function of the bone and the affected part.

Current Bone Restoration Techniques

Autograft is the best procedure but it has its limitations which are:

1) Cumbersome procedure

2) Produces deficit at the point from where the part is removed for the patient.

Allografting generally presents with the difficulty to find a donor and if the donor is found, the patient has to take lifelong immunosuppressive therapy because of these limitations in allografting 3D Bone Printing (3DP) seems to be a good alternative and this lead to its development. As the produced 3D printed bones would be compatible with the patient and will not need immunosuppressors!

3D Bone Printing Procedure 

3D Printing Bones

Three-dimensional bone printing technique uses a bone-like customized implant which is 3d printed and is converted to the real bone when placed inside the patient's body.

Computerized tomography Scan (CT) is done to the patient and a patient-specific implant is prepared by biochemical engineers and surgeon.The design is printed on Calcium Phosphate which is the main constituent of the bone.

The 3D Bone Printing procedure usually involves 4 steps:

1) Creating homogenous powder bed from powder granules by using rollers

The size of the powder granules determines the smoothness and thickness of the powder bed formed which affect the resolution of the final print. Flowability of powder is important to the spreading of powder.

High flowability and finer size granules help in the formation of higher resolution hexamethyl-disiloxane which is being used to decrease the van der walls forces that can reduce flowability of fine sized particles.

2) Spraying binder solution droplets on the powder bed in several passes guided by a CAD file. The binder solution may be an organic or aqueous solution (e.g., phosphoric acid23 or dextrin24).

3) The 2D layer formed is dried and new layers are added to it, 

The above 3 processes are performed over and over again until the 3d structure is completely prepared

4) Depowering and removing of excess powder from the 3D printed structure.

The printing process is highly precise and very accurate providing the design that perfectly fits the deformity even in highly complex shapes and sizes which can be designed with ease. The implanted bone fuses with the patient's bone in about a month following normal procedures of bone attachment.

Fusing the 3D printed structure is as follows:

1) Formation of a fibrocartilaginous callus

2) Formation of a bony callus

3) Remodeling and an addition of compact bone.

Advantages of Three Dimensional Bone Printing

Unlike other 3D printed ceramics (like Hydroxyapatite or Beta-TCP), this procedure does not require a thermal process (sintering). As Sintering causes shrinkage of ceramics which results in a non-optimal fit of the resulting structure.

The bones are hyperelastic which can be can be easily cut, rolled, folded, and pressed into areas missing bone material, the bone is also highly porous which allow the growth of blood vessels normally providing blood to the surrounding tissues and preventing tissue death (necrosis) from hypoxia or low oxygen supply to the tissue.

Skull 3D Printing 

Conclusion 

Thus we can say that three-dimensional bone printing (3DP) has opened new possibilities in human tissue engineering, that look promising and have great potential to aid in human care.