Use of Force Platform Variables to Quantify the Effects of Prosthetic Alterations on the Gait of a Patient with Fibular Hemimelia

PAUL SALO, MD,* JAMES A. HARDER, MD,R. O. ROBINSON, DC, KATHRYN TEDFORD, PT, GEORGE CLYNCH, CP AND B. NIGG, DSc. Nat


Fibular hemimelia, the commonest congenital limb deficiency, is usually treated by Syme amputation in infancy or childhood. Prosthetic fitting is complicated by progressive leg length discrepancy, genu valgum, medial collateral ligament laxity, and patellar subluxation. It has been assumed that the resulting ligamentous stress and the "medial heel whip" gait pattern can be minimized by changing the geometry of the prosthesis. Further surgery is undertaken when alterations to the prosthesis no longer adequately compensate the patient's needs. The purpose of this study was to determine whether force platform measurements could be used to quantify the effects of prosthetic alterations on gait. A teenage male patient who had undergone a Syme amputation for right fibular hemimelia was studied. He was fitted with a prosthesis constructed so that the foot could be moved in any direction in the transverse plane and rotated about an axis normal to that plane. Force platform data were collected which compared the gait pattern of the intact leg with the prosthetic leg. Seven positions of the prosthetic foot were considered. There was considerable asymmetry for all positions of the prosthetic foot. Most parameters were significantly changed by alterations in foot position. Rotational displacements appeared to alter gait variables more than other displacements.

*332A, 4935 40th Avenue, NW, Calgary, Alberta T3A 2N1