Over 120,000 people in the United States receive total hip replacements annually. This number is mainly composed of people suffering from arthritic and fractured hips. The recuperative process requires that weight bearing be limited on the prosthetic hip. Currently patients can only approximate their allowable reduced weight limit by standing on a scale and pressing down with the affected leg until the scale registers the amount of allowable pressure. The patient is then expected to remember and replicate this static measurement of pressure while walking. However, it is nearly impossible to do this with accuracy while re-learning to ambulate. Excessive premature weight bearing can necessitate repeat surgery and/or immobilization of the hip joint by an external brace.

We propose to solve this "pressing" problem by the addition of a weight detecting device to the shoe, a small transmitter worn on the shoe and a signal alert which is worn as a pendant around the neck. This three-piece device measures the pressure applied to the foot and transmits an FM signal to the pendant receiver which alerts the patient when a predetermined weight is reached. The alert is conveyed by light and sound, as well as vibration for the hearing impaired.

An average two to three week post-surgical rehabilitation stay for hip prosthesis implantation can be trimmed by two days using this device for better initial weight bearing and training. A two-day decrease in length of stay (at an average per diem hospital/rehabilitation cost of $950) would result in a savings of approximately $1900 per hip rehabilitation treatment. When multiplied by the 120,000 annual hip procedures performed, this would result in an annual health care cost savings of $228 million dollars. s



Students: Dorothy Weiss f Rebekkah Kerner

Teacher-Advisor:

Nancy Moscheo