Osseointegration for limbs involves inserting a metal rod into an arm or leg bone. The bone then fuses with the rod in a manner similar to fracture healing. The resulting implant offers numerous benefits but also introduces some health risks.
Traditional Prosthetic Attachments
Traditional prostheses used a fitted socket, often combined with a harness or other type of suspension system.
Modern materials, casting, and fitting methods have allowed for increased use of fitted sockets solely on their own using vacuum, suction, or lock mechanisms.
Unfortunately, even modern sockets still cause skin abrasion, lesions, sweating, etc., which discourages their use.
A traditional prosthesis can also tire the user because it is essentially dead weight.
Osseointegration provides an alternative mechanism for attachment by eliminating the need for external sockets.
Prosthetic Attachments With Osseointegration
As mentioned in the introductory paragraph, osseointegration involves inserting a metal rod into an arm or leg bone. Part of the rod protrudes from the residual limb. This abutment is then connected to a prosthesis as shown in these two diagrams of the OPRA™ Implant System from Integrum.
The main advantages of this approach include:
For more information on these advantages, please see Part 1 of our interview series with Dr. Laurent Frossard.
The main disadvantages include:
For more information on these disadvantages, please see Part 2 of our interview series with Dr. Laurent Frossard.
Improved Osseoperception
Osseoperception refers to the transfer of vibrations from the osseointegrated rod to the attached bone.
A recent study by the DeTop Consortium proved that vibrations traveling through the bone can be perceived by the ear. This helps the wearer distinguish between different stimuli.
For example, this young man can feel when he’s touching his partner’s arm vs the bowl vs the countertop:
A person with an osseointegrated leg prosthesis can identify the type of surface he or she is walking on. This improves safety, especially when the surface changes suddenly.
The advantages of osseoperception go beyond function. Amputees who have undergone osseointegration feel more connected to their surroundings. In a world where those with limb differences often feel isolated, this increased connectedness improves their sense of well-being.
Osseointegration With Bionic Arm / Hand
Combining osseointegration with a bionic arm allows users to fully utilize their shoulder:
Osseointegration With Bionic Leg / Foot
The increased strength and stability of osseointegrated implants make them ideal for lower limb amputees. When combined with the advanced capabilities of a bionic prosthesis like Ottobock’s C-Leg, the results can be transformative.
Jerry Monteiro lost his right leg to bone cancer at the age of 15. He hadn’t walked without crutches for 35 years. Yet, here he is, only 1 year after surgery, out for a walk. Note the ability of the bionic knee to automatically adjust on stairs.
Osseointegration With Built-In Neural Interface and Myoelectric Sensors
A growing trend for both amputation and post-amputation surgeries is the incorporation of advanced techniques and/or technologies that prepare a residual limb for the use of a bionic device.
Such is the case with Integrum’s e-Opra Implant System, which combines osseointegration with an integrated neural interface and embedded myoelectric sensors:
The label “Cuff e.” near the bottom center of the diagram shows an electrode cuff attached to the nerve. This is the neural interface. As with other neural interfaces, the electrode cuff can apply an electrical charge to the nerve to trick the brain into experiencing a specific sensation. What sensation? Whatever best resembles the sensory feedback provided by an attached bionic device, such as the pressure detected by a bionic finger when the finger makes contact with an object.
The other embedded sensors detect myoelectric signals that result from muscle movements, which are then translated into commands for a bionic device, such as opening or closing a bionic hand.
The appeal of this integrated solution is that, since the patient is undergoing major surgery anyway, including the neural interface and myoelectric sensors can be done with significantly less cost and pain than performing the operations separately.
Note that the e-Opra Implant System is still in its trial phase.
Related Information
Osseointegration hasn’t been perfected yet. To understand how it can still be improved, see Part 3 of our interview series with Dr. Laurent Frossard.
The procedure also isn’t for everyone. If you’re considering it, see Part 4 of our interview series with Dr. Laurent Frossard: Key Issues for Osseointegration Patients.
For a quick summary of all related surgical techniques, see Surgical Techniques That Improve the Use of Bionic Limbs.
For a comprehensive description of all current upper-limb technologies, devices, and research, see A Complete Guide to Bionic Arms & Hands.
For a comprehensive description of all current lower-limb technologies, devices, and research, see A Complete Guide to Bionic Legs & Feet.