Osseointegration Limb Replacement

Leg

What is osseointegration?

Osseointegration is the scientific term for bone ingrowth into a metal implant. An artificial implant is permanently, surgically anchored and integrated into bone, which then grows into the implant.

Osseointegration is most commonly used in dental implants and joint replacement surgery. It has been very successful in these uses for decades.

What is osseointegration limb replacement?

In this surgery, a limb prosthesis is connected directly to the skeleton. The prosthesis is a custom-made, porous, coated titanium implant that is aligned with the bone of the residual limb.

Osseointegration limb replacement surgery can be done in the following bones:

• the femur (thighbone)
• tibia (leg bone)
• humerus (upper arm bone)
• radius and ulna (forearm bones)
   

What are the advantages of osseointegration over traditional prosthetic limbs?
 

In general, this procedure:

• improves mobility (control of the prosthetic leg)
• improves proprioception
• reduces nerve pain
• eliminates common problems associated with sockets

Patients with an osseointegrated limb have better physical control over – and a more intimate, emotional connection to – their prosthetic leg or arm, compared to those using a traditional socket prosthesis. The direct skeletal connection between the prosthesis and the patient’s own natural bone provides superior stability, strength and energy transfer (in which muscle strength from the residual limb is diminished where it connects with the prosthesis).

In particular, patients who have an osseointegrated prosthetic limb have dramatically improved proprioception, called osseoperception. Touch vibrations to the implant (such as during impact with the ground while walking) can be transferred through to the person’s natural bone. This helps patients walk more smoothly, feel more stable and effectively transfer all of the strength of their residual limb to the prosthesis.

Bone-anchored prostheses have been shown to lead to better patient outcomes than standard, socket-based prostheses. An osseointegrated prosthetic limb reduces or eliminates common problems associated with sockets, including:

• pinching
• sweating
• poor fit or need for frequent refitting
• poor ability to control the prosthesis
• lack of patient confidence due to mobility challenges
• nerve pain
• skin, irritation, sores and ulcers

In traditional prosthetic leg systems, there can be a poor fit between the residual limb and the socket. Many patients experience significant changes in the size and shape of their residual limb during the first 12 to 18 months after amputation surgery.
In addition, the angle at which the remaining leg bone rests inside the socket is frequently uneven with the prosthetic leg. This is called malalignment. Such awkward angles can cause balance problems and poor energy transfer. This can make it difficult for patients to move well and can even lead to falls and fractures.

Improved movement in the upper limbs

In patients with arm and hand prostheses, the large harness and socket that is often used in upper extremity prosthetics is eliminated. This enables the patient to actively use their body’s natural shoulder and elbow movement.

Osseointegrated arm implants are also compatible with myoelectric (bionic) prostheses. These allow muscle twitches in the residual arm to communicate with the arm prosthesis to allow patients to actively move their prosthetic elbow, wrist and hand. New technologies use pattern recognition algorithms to relay muscle movement signals in real time from the residual limb to the brain and then back to microcontrollers that control the movement of the bionic arm or hand. In some cases, targeted muscle reinnervation (TMR) is used to enhance the muscle signals.

Individual types of prosthetic limbs designed for different purposes, such as swimming or running, can be easily connected to and disconnected from the implant abutment using an Allen wrench (hex key) or quick-connect hardware.

Reduced nerve pain

Many amputees also experience nerve pain in the residual limb, which is caused by a neuroma. This is often described as “phantom” leg or arm pain. In most cases, wearing a socket prosthesis puts added pressure on the remaining limb, which worsens this nerve pain.

New surgical procedures to ease the pain associated with amputation neuromas can now also be performed together with osseointegration surgery. These include:

• targeted muscle reinnervation (TMR)
• regenerative peripheral nerve interface (RPNI) with free muscle graft
   

Who is a candidate for osseointegration limb replacement?
 

Osseintegration leg or arm replacment is especially helpful for amputees who are having a poor experience with their socket prosthesis.

The use of a socket is often especially difficult for patients whose residual limb is any of the following:

• short
• wide
• scarred
• painful