My Thoughts on Bone Implant Prosthetics

| | Physician Peer Review, Technology & Integration

Zenias April 2018 Article on Prosthetic Limbs
There has recently been increased public interest in bone implant prosthetics. These are different than what most people are familiar with regarding lower extremity devices because part of the prosethetic implant inserts directly into bone. Although this may appear to be a new device, in reality it has been around for many years in Europe.

The Osseoanchored Prostheses for the Rehabilitation of Amputees (OPRA) was developed in Sweden and began being implanted there in the 1990s.  The first prospective study began in 1999 with 51 subjects and ran for two years.  The results showed increased function at 12 and 24 months when compared to the previous prosthetics and good patient satisfaction.  Further studies thereafter continued to show benefits.  The implanted device is made of titanium.  It was designated by the FDA as a Humanitarian Use Device (HUD) on July 11, 2008 and received full FDA approval on July 16, 2015.

This device is not indicated for just any lower extremity amputation.  It is indicated for a very specific patient population.  The indications for use of the device are adult patients who have transfemoral (mid-thigh) or trans-tibial (mid-calf) due to trauma or cancer and have rehabilitation problems with or cannot use a conventional socket prosthesis.

Some of the problems a patient can have with a conventional socket include recurrent skin infections or ulcerations, short stump preventing use of a socket, fluctuations in volume of stump, soft tissue scarring, extensive skin grafting, socket problems due to excessive sweating, and restricted mobility.

In other words, the conventional socket prosthetic is still the main stay for most lower extremity amputees.  If a patient is unable to tolerate or successfully use the socket prosthetic, then there may be an indication to use this device, and this device can be life changing. Candidates are not considered for the device if they are not skeletally mature, have atypical skeletal anomalies, are older than 65 and younger than 22, weigh over 220 pounds including the prosthesis, have osteoporosis or other medical co-morbidities.

Use of this device requires a two-stage surgical implantation process. The first stage is implanting several of the internal device fixtures within the canal of the bone stump.  Six months of non-weight-bearing are needed to allow the device to become anchored in the bone.  The second stage is to add the external abutment screw that will allow fixation of the external prosthetic device. An extensive rehabilitation process is then undertaken with full weight-bearing using the prosthetic allowed at six months after the second stage.  In other words, it’s a full year commitment to do this procedure.

There are complications associated with the device.  The most definite risk is of infection but the clinical evidence demonstrates that the complications due to infections are manageable.  One study showed an infection rate of 61% although most were superficial.  Other complications include mechanical complication of the implant, pain and other injury.  The implant success rate has been over 90% at two years of follow up.

This device has been a life changer for those who found themselves with limited mobility and independence. There has been a note increased independence with activities of daily living, improved hip motion, improve mobility with this device with being able to walk longer distances and improved sitting comfort.

Zenia Cortes, MD, Orthopedic Surgeon

Dr. Zenia Cortes brings her combined expertise in sports and orthopaedic medicine to UniMed Direct, along with insights from her experience in peer and utilization review.