Is It Safe To Run With That (2)? – Bone Remodelling…

One of the first questions I am often asked when fellow amputees and ‘normal’ people find out about ITAP is: ‘Can you run with that?’.  As with most things in life, the answer is not a simple one!

Everyday movements impart various forces through the body that are borne by the skeleton. Obviously, for an implant attached prosthetic leg, ground impact and other forces will be conducted by the prosthetic into the skeleton via the implant/bone interface.  Considerable effort and ingenuity is therefore expended by the designers of implants to ensure that their devices maximise the process of integrating themselves within the residual bone in the stump after surgical implantation (known as osseointegration). If the osseointegration reaches a suitably high quality then the implant should be sufficiently strongly attached to the bone to withstand the various forces encountered in everyday life. It is now thought that the process of osseointegration can be stimulated soon after surgery by gradually loading the implant with initially small but appropriately increasing forces during the course of the recipients rehab.  This is exactly what I experienced in the months after my surgery, guided by the excellent physiotherapist that supervised my recovery.  As I understand it, small forces initially stimulate the microscopic inclusion of bone into the adjacent surface of the implant, giving a ‘tight fit’, which continues into significant bone remodelling as the rehab forces increase, resulting in stronger overall bone to support the entire structure of the implant.

In order to protect their ‘investment’ in myself as a trial patient, I was advised by the ITAP designers that I should refrain from any high impact activities after my implantation.  The forces experienced by a lower limb whilst running are likely to be considerably larger and at a higher rate of repetition than anything that would be generally experienced on a day to day basis and would definitely be considered high impact . For an implant to withstand these forces, the quality of integration between bone and implant would need to be proportionally higher than otherwise required and this would need to be combined with with additional overall bone strength.  Some years ago now, I had a very gentle attempt at running and fortunately suffered no ill effects.  As a result of this experience I speculated that it may be possible to run safely with an implant and the appropriate prosthetics, assuming the inherent springiness of a blade would provide some level of cushioning from the impact forces, and after gradually building up the intensity of exercise to allow the bone within the stump to cope with the forces involved via the process of remodelling.

After that significant preamble, I have finally come to the point of my post. Whilst trolling through my computer files recently I found a photograph I had taken some time ago of one of my follow up x-rays (three years post-op I think). The thickness of the bone where the implant emerges looked pretty impressive to me so I dug out a post-op x-ray for comparison (left = post-op, right = three years later).

image

Looking at the two images, the differences that three years of weight bearing use have wrought upon what remains of my femur are clear to behold. All the cycling, mountains and long walks appear to have had an effect – demonstrable evidence of the effect of bone remodelling.

Back to the question at hand; is it sensible to run with an implant? There’s still no definitive answer but I’d happily have another go, especially with appropriate prosthetics, now I’ve seen how my implant is embedded in the bone!

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2 Responses to Is It Safe To Run With That (2)? – Bone Remodelling…

  1. Nancy Enns says:

    I see that it was June 4 2014 that this was posted. How goes the running??? My son is an above the knee amp and is looking at this BUT he loves to run. So had you tried to run again??

    • admin says:

      Hi,
      I’ve not formally run since unfortunately. Partly this is due to a lack of motivation, partly due to a lack of components, and the two factors reinforce each other! My prosthetics really aren’t suitable for running and without the funds or motivation to obtain ones that are I have left the blade running to others. Should I somehow be able to obtain a running leg I would expect that with time I could gradually work up to running. This may not be the case with all osseo systems though. ITAP doesn’t require the removal of any material from the residual bone to fit the implant whereas other systems do. This hollowing out of the residual bone can potentially lead to weak points in the bone / implant system so running is not advisable. It’s a difficult choice to make but if I were offered ITAP on the condition of never being able to run I would definitely take it – the other benefits are extraordinary!

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