Forces and moments telemetered from two distal femoral replacements duringvarious activities

Two distal Femoral replacements were instrumented to measure axial Force, t orque and bending moments in the prosthesis shaft. Data are reported up to 2.5 years for the following activities: uni- and bi-lateral standing, walki ng, stair climbing and descending, treadmill walking, jogging and jumping. In the first subject the greatest averaged peak shaft forces found were: jo gging 3.6 Bodyweight (BW), stair descending 3.1 BW, walking 2.8 BW, treadmi ll walking 2.75 BW, and stair ascending 2.8 BW. Bending moments about the a ntero-posterior axis (varus-valgus) and medio-lateral axis (flexion-extensi on) peaked in the range 8.5-9.8 and 4.7-7.6 BW cm respectively, over the fo llow-up period. Axial torques peaked in the range 0.2-1.3 BW cm, outwardly directed. At most follow-up sessions, forces and moments during jogging wer e generally greater than those for other gait activities. In the second sub ject forces and moments were generally only 45-70% of those in the first su bject, due to inadequate musculature around the knee. The data can be appli ed to the design and testing of distal femoral replacements and even to tot al knee replacements, and contributes to the knowledge of forces acting in the distal femur during activity. (C) 2001 Elsevier Science Ltd. All rights reserved.