Notes From The Prosthetics Research Program

This material continues the series of abstracts from reports issued by prosthetics research laboratories in the United States and Canada. The items which follow are taken from the activity report for April-May-June 1967 published by the U.S. Army Medical Biomechanical Research Laboratory (Col. Peter M. Margetis, Director, and Dr. Fred Leonard, Scientific Director).

-Editor

Electric Elbow

Two of these units continue to be tested at New York University. Preliminary results have revealed mechanical problems with the drive mechanism. A new worm gear unit has been designed. Initially, a few will be fabricated and tested in the laboratory and then clinically evaluated. This new unit should be lighter and more reliable.

Electric Hand

During this period, excellent progress has been made. Six hands (three left, three right) have been completed. One unit has been fitted using a Condyle type of suspension and a sequencing control circuit, operated by stump pronation. The fitting appeared to be successful.

Six three-level control switches have been fabricated. These units require a total excursion of 3/8 inch.

A three-level strain gage switch has been designed and bread boarded. This unit incorporates sequencing at the two active levels.

The overall hand system efficiency has been analyzed, and a system efficiency of 12 percent was obtained. Several modifications are being investigated which should result in increased efficiency.

Resilient Hand, Size V

The mechanical operating mechanisms, the foam fillers, and the cosmetic gloves for the left and right hands have been completed and are being assembled at this time. Except for minor fitting problems, the Size V hand should be ready for amputee testing.

Resilient Hand, Size IV

Work will be resumed on the Size IV hand, which consists of making design modifications to reduce the overall size of the operating mechanisms to provide a thicker resilient foam covering and a more pleasing cosmetic appearance of the hand.

Resilient Hand, Size III

Work continues to produce this hand size, using a reduced in size operating mechanism to conform to the preselected No. III hand size.

FLAC Hook

Evaluation of this device continues at New York University.

Voluntary Opening, Center Control Hook

A preliminary design and analysis of a center control hook has been started.

Muscle Bulge Switch

A three-level muscle bulge switch has been designed to fit into the cap of a prosthesis. Switch activation is accomplished by contracting the pectoralis. Three switches were fabricated and tried on experimental prosthesis caps. Problems of the switch binding and preventing actuation were encountered. Modifications were made and new drawings submitted to the machine shop.

The Use Of Certain Plastic Materials In Reconstructive Surgery Of The Knee Joint *

* From the El Paso Orthopedic Surgery Group, El Paso, Texas. Reprinted from The Bulletin of the Dow Corning Center for Aid to Medical Research, April 1967.

L. Breck. Presented at meeting of the Pan Pacific Surgical Association, Honolulu, September, 1966.

Since 1944, cellophane, Silastic sheeting, and Ivalon sponge have been used clinically in orthopedic surgery. In certain cases where the quadriceps muscle was abnormally adherent to the femur, results were often disappointing when the muscle was freed surgically. Placement of a thin piece of cellophane between the bone and the muscle permitted at least 90 degrees of motion in 27 of 34 cases.

Since the cellophane tended to wad up, Silastic sheets, .020 inch in thickness, were substituted. This material retains sutures, remains in place well, and is readily sterilized by autoclaving. Excellent results have been had with it in six cases. All patients have a painless or nearly painless knee.

For knee joints, when the medial or lateral tibial table is rough and has been partially destroyed, the implanting on it of Ivalon sponge has produced a smooth, hard surface against which the femur can articulate. Of the six cases done by the author with this procedure, all have had good results.