O&P Library > Reference Section > Interview: Charles Pritham, CPO

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Interview: Charles Pritham, CPO

(Mr. Pritham's answers are in blue)


In early 1981 Ivan Long, CP presented a two day class at John Sabolich's facility teaching his "Long's Line Prosthesis" technique. The CAT-CAM socket design evolved from this brief introduction of what is now classified as the ischial containment narrow M-L socket design.

Question: Who coined the term "ischial containment" and how did that come about?

The name ischial containment is derived from the phrase ischial-ramal containment coined by Prof. Charles Radcliffe at a consensus conference convened in Miami Beach in the late 80's by ISPO. This meeting was held to attempt to make sense of the proliferation of claims and counter-claims around the entire issue of AK socket design. Flexible sockets were also a topic of discussion. Long was in attendance with Sabolich making a brief appearance. Radcliffe talked to Long and others, and then offered his concept of the design parameters involved. He described them collectively at the ischial-ramal containment design.

Question: John Sabolich's CAT-CAM socket represents the first variant of the ischial containment design. Can you map out the other variants of the ischial containment design that emerged during the '80's and 90's?

Long was exploring the issues involved at least as far back at the 70's when he published an article in AOPA's journal describing Long's Line. John apparently learned of the idea from there and somehow or another became involved with Ivan Long. John began publicizing his efforts in the 80's and at one time or another called the various iterations on socket design, CAT-CAM, SCAT-CAM, and OKC socket. At about the same time Ivan Long began to publicize his own efforts. Kevin Carroll was working for Sabolich in this period and stayed with the company after it was sold to Novacare (later Hanger) by Sabolich and John left the company. At some later point Novacare or Hanger rechristened the design Comfort-Flex. Aside from this train of development there were a number of other people who became involved after they learned of Long's and Sobolich's efforts and began developing their own ideas. It is probably worth keeping in mind that Radcliffe's explanation of the design concepts involved was the first rational explication on the topic, albeit belated. Most of the earlier explanations of what it was the developers said they were doing and why they were doing it just didn't make any sense. Particularly when they said they had discovered entirely new biomechanical concepts. A socket is still a socket and a TF [Transfemoral] residual limb is still a TF residual limb.

Question: Ivan Long, CP didn't widely introduce his limb design until 1985, under the new name of Normal Shape Normal Alignment (NSNA). By the mid 1980's the CAT CAM design was well exposed, with I believe, two week courses were being taught at UCLA. In your opinion, do most ischial containment socket design variations come from the CAT CAM design or Ivan Long's NSNA design as the primary inspiration?

UCLA provided a forum for a number of developers to present their ideas and developed their own from these various courses. Chris Hoyt, Tim Staats, Marlo Ortiz, and others were active in this effort. The schools UCLA, NU, and later Dominquez Hills developed teaching methods for dissemination of what we now call ischial containment sockets. Despite the confusion that surrounded the gestation and birth of the socket design, I consider it one trail of development with numerous branches and dead ends. Marlo's MAS socket can probably best be considered a further evolution of the IC design and that derives from his experiences with the various variants developed on the West Coast to pursue the IC concept.

Question: According to the classic literature, the biomechanical design goals of the quadrilateral socket are identical to the ischial containment narrow M-L design. Do you recall who extolled the "entirely new biomechanical concepts" associated with the IC design and what they might have been?

John Sabolich was probably the strongest proponent of that point of view, although any number of people parroted these claims without thinking through the issues involved. As I recall Ivan long made no particular claim aside from improving the adduction angle of the femur.

In 1990 Dr. Frank Gottschalk (et. al) published an article in the JPO, titled "Does Socket Configuration influence the position of the femur in Above Knee Amputation?" Dr. Gottschalk's study involved X-rays of 27 quadrilateral sockets and 23 ischial containment sockets measuring the adduction / abduction angles of the amputated femur under weight bearing conditions inside the socket. An analysis of variance showed no significant difference between the femoral angles found in the quadrilateral and ischial containment socket. Dr. Gottschalk concluded from his research that socket configuration and alignment did not influence the position of the femur and proposed a surgical technique to ensure proper adduction of the femoral remnant.

Question: What is your opinion of Dr. Gottschalk's conclusions regarding the influence of alignment and socket design on the amputated femur and how influential do you think his research has been?

I accept Gottschalk's analysis of his research, although I am sure that there are those that would disparage the methodology used. I really don't think it had a major impact, not from any inherent weakness in his argument, but rather from a basic unwillingness to accept any claim that ran counter to what many in the field wanted to believe.

You were the editor of Clinical Prosthetics and Orthotics when Ivan Long, CP and John Sabolich, CPO published their articles on their alignment and socket designs in the Fall 1985 issue; you were also editor of the Journal of Prosthetics and Orthotics when the 1989 Gottschalk's study was published.

Question: How long were you the editor of both journals?

I was editor of CPO from 1982-1888. i was editor of JPO from 1988 (when it was formed by the merger of CPO and AOPA's journal) until 1992.

Question: What did you think about the new designs published in 1985, from the perspective of that time period?

By the time the Long and Sabolich articles were published both had been on the lecture circuit and there was a great deal of tumult and confusion about the various AK designs being publicized. I felt that there was a need to get something specific in writing circulated widely to avoid further confusion and combat much of the second hand misinformation being bruited about.

Question: In 1989, were there any questions raised by the peer reviewers of Gottschalk's article that you recall?

The Gottschalk article was not subjected to peer review as I recall. That really did not start for JPO until later.

In the index section of the Fall '89 issue is annotated, under Dr. Gottschalk's article it says:

This paper has been presented at both the AOPA and Academy meetings. Each presentation has drawn a crowd and been hotly debated. We present it here to those who have not had the opportunity to hear the presentation and to those who want to "hear" it again.

Question: Can you share any recollections of the stir that this research paper caused? Did the JPO publish letters to the editor during those years, and were there any follow up written debates (e.g. letters to the editor) on this subject?

While the various presentations by Gottschalk often caused debate, I do not recall a similar reaction from the publication of his article or any letters to the editor about it.

Question: Clinical Prosthetics and Orthotics (CPO) and Orthotics and Prosthetics were eminently readable and completelypractitioner focused. Given your editorial experience, what do you think of the current evolution of the prosthetic journals?

I believe that the current version of CPO is publishing articles that are sounder in terms of their scientific structure and totally irrelevant to the average practitioner. Most of the classic articles from Artificial Limbs would not pass muster the editorial board, yet the best of them are still relevant today and are the basis of what we do as prosthetists.

O&P Library > Reference Section > Interview: Charles Pritham, CPO

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