Experiences In Fitting Patellar Tendon Bearing Prostheses To Juvenile Amputees

Claude N. Lambert, M. D.

Since this is the first communication to the clinic chiefs in the Juvenile Amputee Program, it has been difficult for me to decide the format of my report and the subject material to be presented. In view of the fact that our clinic has accepted the philosophy of fitting a great many of our below-knee amputees, and particularly the children, with patellar tendon bearing prostheses, a preliminary report of our experiences in this area may be of value to the clinic chiefs.

Our first patient was fitted with a patellar tendon bearing prosthesis on April 14, 1960. Fifty-nine prostheses have been ordered to date; 48 have been fitted and the other 11 are in the process of fabrication. Of the 48 patients who have been fitted, 22 are under the age of 21 ; 12 are males and 10 females. (In our clinic the age of 21 is the deciding line between the children and the adult programs by State law.)

The distribution of these 22 patients by age and sex is as follows:

Age Males Females
1 2 1
3 1 2
6 - 1
7 1 -
8 - 2
11 1 -
13 1 -
14 2 1
17 3 1
18 1 1
19 - 1

Among the adults who have been fitted (over age 21), the oldest have been a woman of 65 and a man of 70 years. Among the 22 in the children's group, there are 7 males and 2 females who are traumatic amputations. The causes of their amputations were as follows :

  Males Females
Train accident 5 -
IV Intravenous Gangrene 1 1
Auto Accident - 1
Gunshot 1 -

Five males and 6 females had anomalies (hemimelia) and were converted to belew-knee amputations. Two females had trve congenital amputations.

Seven males and 7 females had worn standard below-knee prostheses before being fitted with the patellar tendon bearing type, while five males and 3 females were first fittings. Five males and five females had left below-knee amputations, and 7 males and 5 females had right below-knee amputations. One male is a bilateral below-knee amputee. (Two of our adults are also bilateral below-knee amputees.)

Primary Fittings

Concerning those who were fitted with a patellar tendon bearing as a first prosthesis, and have worn the device 4 to 16 months, we have the following information:

Eight (5 males and 3 females) were under 15 years of age. Five were congenital anomalies surgically converted to amputations at 4 days, 9, 11, 37 and 41 months of age respectively. They were fitted with patellar tendon bearing prostheses at age 10, 14, 16, 40 and 45 months. They have worn their patellar tendon bearing prostheses for 12, 8, 7, 6 and 1 month, respectively. One other youngster in this group sustained a gunshot wound at the age of 8 years and 10 months, with a resulting cord injury. Amputation (right below-knee) was done at 14 years and 4 months of age, and he was fitted with a patellar tendon bearing prosthesis at 14 years and 9 months. He has worn it for four months.

Most of these children have been fitted with a thigh strap and a waist band, and one patient, who has congenital absence of the tibia, has a thigh corset, kick strap, and waist band. All of them are doing well and thus far appear to have experienced no untoward effects.

Two 17-year-olds, both victims of traffic accidents, have been fitted. They had their amputations at 17 years and one month and 17 years and five months, and received their prostheses four months and five months after surgery, respectively. The first youth received a new prosthesis after 11 months wear, due to stump shrinkage, and has now worn a patellar tendon bearing prosthesis for 14 months. The second required several adjustments due to stump shrinkage. Kemblo rubber 1/8 inch was added to his socket insert after four months wear and then again after a further three months. About two weeks later (a total of 7 1/2 months wear) he required a new socket insert. Four months later, after only 11 months wear, he needed a completely new prosthesis. He has now worn a patellar tendon bearing prosthesis for 16 months. Both patients are doing well and have no apparent untoward after-effects.

Previous Prosthesis Wearers

Of the children who had previously worn prostheses, there were nine (5 females and 4 males) fitted in the below 15 years of age group. Of this group, two were congenital amputations. The first was fitted with a standard prosthesis at the age of one year and two months, and the other at six years and six months. They have worn patellar tendon bearing prostheses for 3 months and 11 months, respectively. Another youngster had congenital anomalies bilaterally converted to tight above-knee and left below-knee amputations at 18 months of age. She received right knee end bearing and standard left below-knee prostheses at 21 months of age. After wearing the standard below-knee for 12 years and 7 months, she received her left patellar tendon bearing prosthesis at 14 years and 6 months and has worn it for 11 months. She needed a new socket after eight months wear because the rubber deteriorated.

Two youngsters had amputations following I-V Therapy at 7 months and 10 months of age. The first was fitted with a standard prosthesis at 18 months and wore it for 5 years and 9 months. He was then fitted with a patellar tendon bearing type, which he has worn 8 months. The second received her standard below-knee prosthesis at 20 months of age and wore it 4 years and 8 months. She was then fitted with a patellar tendon bearing prosthesis which she has worn for 9 months.

Another youngster in the group sustained crushing injuries to both feet in a train accident, resulting in a right below-knee amputation and a left mid-tarsal amputation at 6 years and 9 months of age. He received a right standard below-knee prosthesis at 7 years and 4 months, and wore it for 5 years and 2 months when he was fitted with a right patellar tendon bearing prosthesis which he has now worn for 14 months. He also required a new socket insert due to deterioration of the rubber after 10 months (He prefers to have only a shoe filler on the left foot.)

One youngster wears a thigh corset, waist band and kick strap because of a very short stump. Another uses only a condylar strap support. The others have thigh straps and waist bands in addition to condylar straps. All regard the patellar tendon bearing type as being more comfortable, easier to put on, and better appearing. Several children are now taking part in such activities as jumping, ice skating, and dancing and want to continue wearing this type prosthesis. (The greater comfort allows them to participate in these new activities.)

One of our adolescents had been a satisfied good wearer of a standard below-knee prosthesis. She was dissatisfied at first when changed to a patellar tendon bearing type. We encouraged her to continue to wear the patellar tendon bearing type prosthesis and now, six months later, she is very enthusiastic about it.

Miscellaneous Considerations

All of the juvenile amputees have X-rays taken of their knee joints every six months. The X-rays are not taken with their prostheses on - I see no particular advantage to this - but we do take X-rays of the opposite knee for control.

Thus far we have not noted any demonstrable changes in the epiphyseal line of either distal femur or proximal tibia. The study, of course, has been going on for less than 18 months, and changes may not become apparent until more time has passed. These will be carefully examined and reported at a later date.

Our chief discussion has been with the prosthetists. We have ordered total contact patellar tendon bearing pros theses, but most if not all of these,are not total contact prostheses. There is a space of from one to two centimeters between the end of the stump and the lining of the prosthesis. When the stump shrinks, the prosthetists explained, the stump contacts too solidly with the socket and produces pain. It is possible that better total contact would be obtained after the second prosthesis when, theoretically at least, all shrinkage has occurred.

We are interested in learning if other clinic chiefs have encountered problems of this nature. I discussed the manufacturing problem recently with Blair Hanger, of Northwestern University. He expressed the view that the critical standard of total contact is not met in clinical practice, although the schools are now teaching it.

If cost of revision, relining, etc., is not a factor, it might be advisable to conduct a definite trial of total contact sockets. With cost being a major factor and the patients getting along well, perhaps we should also have time for further observation of the stump-socket relationship.

Stump shrinkage problems have occurred, with all of the patients with the "fresh" amputations especially affected. There has been the problem of need for new socket inserts because of the Kemblo rubber deterioration. Of those who have worn standard prostheses, the majority prefer the patellar tendon bearing type. Other than the problem of shrinkage with need for new inserts and/or sockets and the rubber deterioration (all these items are expensive), other repairs and adjustments have been minor.

Claude Lambert is Clinic Chief, Amputee Clinic University of Illinois, College of Medicine