Endoskeletal vs. Exoskeletal Prostheses for the Child with PFFD


We have fit 15 patients (congenital short femur associated with PFFD and Syme amputation) as above-knee amputees, first with exoskeletal and subsequently with endoskeletal prostheses. The exoskeletal prosthesis usually consists of a Silesian band, PFFD socket with Pelite Insert, external knee hinges and a Sach foot. This type of exoskeletal prosthesis is functional, comfortable and somewhat durable. The cosmesis of exoskeletal prostheses is often less than desirable, and the external knee hinges are unsightly and quickly wear out the brass bushings. The check strap, if used, often needs to be adjusted to prevent further damage of the joints and reduce the noise from terminal impact. External hinges can be modified to include a replaceable bumper which eliminates the check strap.

Endoskeletal prostheses are often lighter and more cosmetic than exoskeletal prostheses. However, the foam cover is not durable and in a young child may often need replacement. Some modular endoskeletal systems have a 4-bar polycentric knee which allows placement of the mechanical knee at an acceptable level with the contralateral knee. This type of knee is ideal for knee disarticulation and unilateral PFFD amputees with long residual limbs. The advantages and disadvantages of endoskeletal and exoskeletal prostheses for children with congenital short femur associated with PFFD and Syme amputation were discussed.

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