Abstracts Presented at the 7th Biennial Congress of the International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine| Volume 28, ISSUE 9, SUPPLEMENT , e341-e342, September 01, 2012

Paper 12: Biomechanical Analysis of Total Knee Arthroplasty Patients and Controls During Comfortable and Fast Walking



      Previous studies using motion analysis to assess level walking following total knee arthroplasty (TKA) have shown that patients walk with biomechanical deficiencies compared to healthy controls. The aim of this study was to determine whether these deficits change with more demanding tasks and whether the deficits during level walking are indicative of greater deficits in tasks closer to the maximum capacity of patients.


      40 patients who had undergone a successful TKA more than 12 months previously and 40 age and sex-matched control subjects were evaluated. There were 22 females and 18 males in each group. Three dimensional motion analysis was performed using 2 force plates and 8 infrared cameras. Patients performed 6 walks and at a self-selected comfortable speed and 3-5 walks at their maximum safe speed. Comparisons of spatiotemporal parameters and peak lower limb kinematics and kinetics were made between control and TKA subjects and between comfortable and fast walking trials.


      During comfortable walking the TKA and control groups walked at similar speeds although the TKA group had a significantly reduced cadence (p=0.005). The TKA group had a reduced knee flexion angle during both loading (p<0.001) and swing (p=0.001), reduced internal tibial rotation (p<0.001), and increased external tibial rotation (p<0.001). Kinetically, 87% of patients walked with a biphasic sagittal knee moment pattern that is associated with normal gait. Despite this, the TKA group had reduced maximum flexion (p=0.012), adduction (p<0.001) and external rotation (p=0.022) moments at the knee compared to the controls. Similar differences between patients and controls for these parameters were seen at the fast speed.
      Compared to comfortable walking, the TKA and control groups increased their cadence during fast walking by 23% and 20% respectively, and both groups increased their stride length by 17%. Both groups demonstrated similar changes in knee angles when walking at fast speed compared to comfortable speed. However, despite similar increases in the ground reaction force for both groups, the knee flexion and adduction moments of the TKA group did not increase during fast walking at the same rate as the control group. The increase in flexion and adduction moments by the TKA group was 51% and 23% compared to the control group increases of 66% and 37%.


      The TKA patients in this study were able to make appropriate temporospatial adjustments to enable walking at a faster speed, indicating that they were not at their functional limit during comfortable walking. However, the reduced knee flexion moment during fast walking indicated a reduced ability to adapt to the greater functional challenge of this task. The reduced knee flexion angle during loading in the TKA group may reduce the ability of the limb to absorb impact and may have implications for loosening. On the other hand, the reduction in knee adduction moment seen in this group is encouraging in terms of loading of the prosthesis.