Trans-USA Hip Disarticulation/Transpelvic Prostheses Tour: Part Seven - Scheck & Siress in Chicago
The final leg on "Steve and John's Excellent Adventure" was back where we started, in Chicago. Jim Kaiser CP from Scheck and Siress was kind enough to arrange for several patients who wore transpelvic and hip disarticulation prostheses to meet with us for a very interesting afternoon of exchanging information.
This was an excellent conclusion to our transcontinental excursion since we were able to meet with a variety of patients who wore high-level prostheses on a daily basis. All were very willing to share their experiences, successes, and frustrations and to demonstrate what they could do with their particular artificial limb. The five patients included two women and three men, and they varied in age from their early twenties to middle age. Some were thin, some fit and trim, and others quite heavy: a good cross section of the US population.
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All wore thermoplastic sockets made of a polypropylene-polyethylene copolymer, which Jim has found to be more durable than laminated plastics and other alternatives. Some had flexible inner sockets within a more rigid frame while others were one-piece designs. Most used polycentric knees for the added stability they offer, and the more active individuals had hydraulic swing phase controls as well. Most of those with a hip disarticulation walked without any balance aids but both transpelvic amputees used a single point cane when out of doors.
One of the most interesting aspects of this visit was the chance to see how Jim has continued to use a variation on the hip flexion bias system originally marketed by Tom Haslem CP several decades ago. This involves a modification to the Otto Bock 7E4 free motion hip joint by adding a sliding sleeve that is machined from a durable white plastic. A coil spring encircles the thigh tube inferior to the sleeve and is compressed when the patient extends the hip joint.
When the prosthetic limb is unloaded, the spring tension translates into a burst of hip flexion, which causes knee flexion and a noticeably more rapid gait. Selecting the proper spring is a clinical determination influenced primarily by the amputee's body weight and cadence. When the spring resistance has been optimized and the amputee has learned how to take advantage of the increased hip and knee flexion and the resulting toe clearance, they can walk at a pace that is much closer to average than with a passive hip joint.
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This result was particularly impressive when demonstrated by a lithe young man with a transpelvic amputation. He was able to walk briskly without any balance aids, although he preferred to use a single cane when outdoors and in crowds. With the aid of the cane, he could walk so fast that the hip flexion bias could no longer keep up with his cadence, whereupon he broke into a hop-skip pattern on the sound side. It is important to remember that the hip flexion bias also tends to make the knee unstable, so this hip joint modification works best when combined with an inherently stable knee such as the polycentric example shown here.
To view a short clip of this patient's gait with this modification, click here . Note the long stride and rapid cadence compared to most transpelvic amputees, although the leg is still too slow, forcing him to vault a midstance to allow time for the prosthesis to swing through.
Even though Steve and I were pretty well exhausted after criss-crossing the USA continuously for two solid weeks, we were also a bit sad that our adventure had come to an end. It was very invigorating professionally to see so many high-level patients who were ambulating independently on a regular basis, and to have lengthy discussions with them and with their prosthetists, who eagerly identified those factors thought to have contributed to the successful long-term outcome.
Although there were a number on individual variations in the specifics of each prosthesis, there were also many common elements. Interestingly, we did not see any laminated hard sockets even though such designs were commonplace in the 1980s. About half the practitioners we visited used a fully thermoplastic design; the others used a flexible thermoplastic inner socket with a rigid laminated carbon fiber frame. Polycentric knees were typical, with fluid swing phase controls for the more active individuals to allow some measure of variable cadence. None of the patients we saw had a locked knee joint or a locked hip joint, although these are "standard issue" in some countries. Almost all patients had dynamic response feet, with some also having an articulated ankle, usually multiaxial.
Overall, it was encouraging to see convergent clinical trends despite the relatively low incidence of such high level amputations. Each practitioner emphasized a slightly different aspect of the fitting options, but all the prostheses were lightweight, intimately fitted, and well suspended. Virtually every prosthetist emphasized the importance of meticulous test socket fitting and repeated dynamic alignment trials, and their patients echoed the significance of these factors. If this admittedly non-randomized group of patients is any indication, modern prostheses of this type can be relatively comfortable and permit a functional gait for independent community ambulation, albeit at a slower pace and with more effort than before the amputation.