Authors: Jennifer M Aldridge Whitehead Erik J Wolf Charles R Scoville Jason M Wilken
Publish Date: 2014/02/11
Volume: 472, Issue: 10, Pages: 3093-3101
Abstract
Stair ascent can be difficult for individuals with transfemoral amputation because of the loss of knee function Most individuals with transfemoral amputation use either a steptostep nonreciprocal advancing one stair at a time or skipstep strategy nonreciprocal advancing two stairs at a time rather than a stepoverstep reciprocal strategy because steptostep and skipstep allow the leading intact limb to do the majority of work A new microprocessorcontrolled knee Ottobock X2® uses flexion/extension resistance to allow stepoverstep stair ascentWe compared selfselected stair ascent strategies between conventional and X2® prosthetic knees examined betweenlimb differences and differentiated stair ascent mechanics between X2® users and individuals without amputation We also determined which factors are associated with differences in knee position during initial contact and swing within X2® usersFourteen individuals with transfemoral amputation participated in stair ascent sessions while using conventional and X2® knees Ten individuals without amputation also completed a stair ascent session Lowerextremity stair ascent joint angles moment and powers and ground reaction forces were calculated using inverse dynamics during selfselected strategy and cadence and controlled cadence using a stepoverstep strategyOne individual with amputation selfselected a stepoverstep strategy while using a conventional knee while 10 individuals selfselected a stepoverstep strategy while using X2® knees Individuals with amputation used greater prosthetic knee flexion during initial contact 325° p = 0003 and swing 682° p = 0001 with higher intersubject variability while using X2® knees compared to conventional knees initial contact 16° swing 62° The increased prosthetic knee flexion while using X2® knees normalized knee kinematics to individuals without amputation during swing 884° p = 0179 but not during initial contact 657° p = 0002 Prosthetic knee flexion during initial contact and swing were positively correlated with prosthetic limb hip power during pullup r = 0641 p = 0046 and pushup/early swing r = 0993 p 0001 respectivelyParticipants with transfemoral amputation were more likely to selfselect a stepoverstep strategy similar to individuals without amputation while using X2® knees than conventional prostheses Additionally the increased prosthetic knee flexion used with X2® knees placed large power demands on the hip during pullup and pushup/early swing A modified strategy that uses less knee flexion can be used to allow stepoverstep ascent in individuals with less hip strengthThe institution of one or more of the authors JMW EJW has received during the study period funding from The Center for Rehabilitation Sciences Research Department of Physical Medicine and Rehabilitation Uniformed Services University of Health Sciences Bethesda MD USA
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