How Much Does Joint Replacement Depend on CAD/CAM Technology?

Because of CAD/CAM and 3D printing technology, significant and almost miraculous achievements have been reported for surgical procedures which involve hip replacement, knee surgery, prosthetics, and medical implants. Although it sounds incredible, the ability to print functioning body parts could happen in the near future. If indeed this turns out to be an achievement and the human body can accept printed body parts without rejection, the implications for extending human life will be enormous. Such an achievement will provide the capability for the human body to have bionic, robot-like implications.

This article reviews progress which has been made in applying CAD/CAM and 3D printing technology for joint replacement surgery, and how these technologies could revolutionize medical practice in augmenting the endurance and performance of physical body parts.

If CAD/CAM and 3D printing technology could provide the ability to create replaceable body parts, then these possibilities could become reality rather than wishful thinking:

• A 70 or 80-year old man (or woman) walks into a medical facility, has his old and almost non-functional hips re-designed, printed and fitted to his body, and he walks out with the hips of a teenager.
• An entertainer goes to a medical center, and orders replacement ears, or nose, or lips. The body parts are printed and they replace his old body parts.
• A soldier loses an arm or leg in the battlefield. Within a few months, the soldier is fitted with new limbs which not only replace the missing limbs, but which perform much better than the lost limbs.
• The career of many gifted athletes such as basketball or football players are cut short because of injuries to the knee, to the ankle, or to other joints. Instead of an injured athlete retiring before the age of 30, the athlete goes into a medical facility for joint replacement surgery. After a few weeks, the athlete emerges with bionic-type replacement joints which extend the career of the athlete for 10 more years.

Do these possibilities sound like day-dreaming or wishful thinking? Hopefully, this article will separate facts and realities from wishful thinking.

What Progress Has Been Made in Hip Replacement Surgery?

The company Stryker® is probably the leader in joint replacement surgery, so it is reasonable to look at what the state of the art is with this company. Stryker uses CAD technology for accurate alignment of hip or knee components. Accurate alignment is the key to obtaining reliable functioning and endurance of the joint. Replacement parts are engineered to closely replicate the functions of a normal, healthy joint. Currently, artificial joints are made with a variety of plastics and metals, which are alien to the human body, and have lifetimes of less than 20 years.

As an improvement on artificial body parts, the Mayo Clinic can print strong, flexible knee joints with nylon, so that the artificial body part mimics bone and cartilage functionality. Research in bioengineering and stem cell technology indicates that in the near future, replaceable bones and joints will be 3D printed, and the printed body parts will grow to match the patient’s own tissues.

What Progress Has Been Made In Bone Grafting?

Injuries and diseases which require bone grafting are many and common. Some of these injuries include fractures, arthritis, and dental diseases. Current methods for replacing missing bone include:

• Autologous bone grafting, which uses bone harvested from the patient’s own body,
• Allograft, which uses bone from a cadaver,
• Synthetic bone, with properties similar to the mechanical properties of human bone.

Autologous bone grafting is best, because there is less chance of graft rejection.

Bone grafting relies on the ability of bone tissue to regenerate under certain conditions.

3D printing of bone grafts is making rapid progress. Materials which are being considered for 3D printing are calcium phosphate, with additives that mimic bone properties, and bone growth.

What Progress Has Been Made In Printing Other Human Tissue And Body Parts?

It will be helpful to find out what progress has been made in printing other human tissue and body parts from the news media.

The following news extract (from Science Daily, May 16, 2014) appeared in an article which was released recently.

“Doctors and scientists in Southampton have completed their first hip surgery with a 3D printed implant and bone stem cell graft.”

“The 3D printed hip, made from titanium, was designed using the patient’s CT scan and CAD CAM (computer aided design and computer aided manufacturing) technology, meaning it was designed to the patient’s exact specifications and measurements.”

“The implant will provide a new socket for the ball of the femur bone to enter. Behind the implant and between the pelvis, doctors have inserted a graft containing bone stem cells.”

“The graft acts as a filler for the loss of bone. The patient’s own bone marrow cells have been added to the graft to provide a source of bone stem cells to encourage bone regeneration behind and around the implant.”

“The bone graft material that has been used has excellent biocompatibility and strength and will fill the defect behind the bone well, fusing it all together.”

“Another news article (from Design Engineering, Feb. 21, 2013) reported that “Cornell researchers bioengineer 3D printed ears that look and act like the real thing.”

These two news articles reveal the type of game-changing technology which will usher in a new level of bone grafting and tissue engineering, and which will change day dreaming and wishful thinking into reality.

What Possibilities Exist In Joint Replacement Surgery?

All the pieces are in place for stepping into the next level in bone grafting and tissue engineering, which will make it possible to print and replace body parts that the body will not reject. The day dreaming and wishful thinking presented at the beginning of this article now looks quite feasible.

Because of CAD/CAM and 3D printing technology, novel medical technology as it was presented in the original Star Trek TV series could become reality in terms of joint replacement surgery.

– IndiaCADworks