Dear Todd, Justin, et al.
IDEAS ON THE BURSA
I should start by saying that I am not a doctor and have no desire to be
one. However, I would like to put my two cents worth to foster some
discussion about bursas and the amputee. However, I am an amputee and
prosthetist, and have a structural/functionalist logic style.
In the past, I have had three bursas. Each time they were the symptom that
highlighted a bone spur (I was a growing child). I was able to have
modifications done to the prosthesis to accommodate the bursa, but
ultimately had surgeries (after x-rays) to remove the bone spurs. However,
not every bursa is a sign of a bone spur…but it was in my case.
In light of the recent posts, I would like to point out that the prosthetic
socket interface with regard to the residual limb should be considered more
of a fibrous joint than a solid non-moving interface. In the below knee
amputee, during knee contraction the gastroc-soleus complex compresses and
the tibia and fibula move posterior in the socket. This can be seen in a
plastic check socket, a gap may form at the anterior tibia in many socket
situations. In the above knee amputee, the need for posting of the femur
demonstrates that the femur also moves posteriorly as the hamstring muscle
group compresses. Thus, due to the movement of the bones inside the socket,
the socket to residual limb interface should be considered to have
characteristics similar to a fibrous joint.
With this movement, a shear force occurs and the skin adheres by friction to
the socket interface, as well as the bone moves in comparison to the
surrounding muscle tissue. It appears from the recent posts and my very
limited research, that a bursa will form as the body’s mechanism to limit
the friction with regard to shear forces. Thus, not only the amount of
movement is important, but also the friction of the interface materials and
the load carried through the area. Specifically, for a bursa on the distal
tibia, the greater the end bearing, the higher the friction becomes.
Further, certain socket types allow for a lower frictional resistance with
regard to the deformation of the soft tissues and movement of the bones
inside the socket. From my personal experience (although more research is
necessary in this area), I believe that a locking gel liner increases the
friction of the residual limb with regard to its ability to deform under
amputee pathologic gait. However, there is also a benefit to this, such as
a longer lever arm and less movement inside the socket. Every amputee is
different, and one needs to evaluate the person to determine what system is
the best for their lifestyle.
Further, the internal characteristics likely play a major role in the
formation of bursas. I would appreciate a trained medical doctor to
elaborate on this. I am under the impression that a nicely beveled bone
allows for and easier movement through the soft tissues as the soft tissues
deform during ambulation. I also believe that the healing process after the
surgery varies from person to person, and thus the smoothness of the cut
bones will vary. I had an excellent surgeon and I obtained my bursas many
years after my surgery, but attributed that to growth since I was an
adolescent at the time of my amputation. I also do not know how the body
heals after an amputation and if the loading effects of end bearing (total
contact) walking can re-stimulate bone formation.
>From my limited reseach, life, and prosthetic experience, the bursa
formation is a compounding issue. In order to limit the friction, the body
creates more fluid (volume). However, by creating more volume in a confined
area (the prosthetic socket), the friction is increased (not decreased).
Thus, with more friction, the body creates a bigger bursa. Thus, it often
cannot heal because the cause is not fixed. In order to fix the cause, the
friction and shear need to be limited. This can be done both
prosthetically, surgically, chemically, by changing one’s lifestyle
(walking), and likely in other ways that I am forgetting.
Prosthetically, I would suggest the person see their prosthetist to limit
the shear or frictional force by socket shape, interface type, suspension
type, or loading characteristics. I am not a doctor, so I would refer the
person to a doctor about internal changes and chemical changes. As to ones
lifestyle, that is for the person to decide upon full knowledge of the
situation.
This is my two cents worth about bursas. I hope that it fosters discussion
and leads to a better understanding of both the socket interface and the
physiology as to why a bursa may occur. I would appreciate any opinions as
to my beliefs, especially to the concept that a prosthetic socket to
residual limb interface should be considered a joint and not a rigid body.
Ideally one wants a rigid body for weight transfer, and a movable joint for
shock absorption…with the individual balance achieved based upon the
characteristics of the person using the prosthetic and his or her lifestyle
and basis for happiness.
Sincerely,
Donnie Priest
From: Justin Foster
Reply-To:
Justin Foster
To:
[email protected]
Subject: Re: [OANDP-L] transtibial
bursa
Date: Thu, 18 Aug 2005 11:18:06 -0700
>Todd and
List,
>
>This came at an opportune time, as I just saw someone
yesterday with
>a
>similar condition… He is toward the
extreme activity level,
>(probably the
>most active or second
most active person I work with) and has what
>appears
>to be a
bursa over the ant. dist. tib… He wears a 9mm locking
>Alpha
and
>the socket is certainly a PTB variant, not by any means a TSB
>design. I
>wonder if the common denominator here is the PTB
design, with a
>relative
>void in the ant. dist. tib!?! I am
planning to have him try a
>”contoured”
>liner with
the extra gel hopefully keeping the distal tib “safe”. It
>just
>seems odd that a bursa would form under the 9mm alpha’s
insane
>cushioning
>ability, and in the cases below, under
Ossur’s quite thick Comfort
>Plus
>system… Maybe the distal
tib relief needs to be filled?!? Any
>thoughts???
>
>Thanks in advance,
>
>Justin
Foster
>Prosthetist/Orthotist
>
>>—–Original
Message—–
>>From: Orthotics and Prosthetics List
[mailto:[email protected]]
>>On
>>Behalf Of Tod
Norton
>>Sent: Tuesday, August 16, 2005 2:53 PM
>>To:
[email protected]
>>Subject: [OANDP-L] transtibial
bursa
>>
>>Over the last six months I have seen three
patients who have
>>developed what
>>has been diagnosed
as a bursa on their anterior distal tibia. None
>>of
the
>>patients complained of any pain or discomfort while
developing the
>>the
>>bursa. All three patients are
relatively new moderately active
>>patients.
>>Two are
wearing PTB sockets with Iceross comfort plus liners, the
>>third
is
>>wearing a PTB suction socket with an Alps cushion liner. It
is
>>particularly
>>odd to me that I haven’t seen this
ever in ten years and suddenly I
>>have
>>seen it three
times. Thanks for ideas or suggestions.
>>Todd Norton, CP,
LP
>
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