Ohkawa T1,2, Fukui T1
1Bunkyo Gakuin University, Department of Physical Therapy, Fujimino, Japan, 2Kashiwatanaka Hospital, Physical Therapy, Kashiwa, Japan
Background: A decreased tibial torsion angle (TTA), which is measured approximately 20° twisted externally under normal conditions as a characteristic of medial knee osteoarthritis (KOA), has been reported. Free moment (FM), the torque around the center of pressure, is reported to reflect the tibial torsional deformation during the stance phase. FM during gait could be an important index to characterize KOA.
Purpose: This study aimed to clarify whether FM could be an index to characterize gait in KOA and to further examine the relationship between TTA and FM.
Methods: Eleven patients with KOA (one man and 10 women; age, 72.8±4.1 years; Kellgren-Lawrence grade of Ⅱ or Ⅲ) and 10 matched healthy volunteers (one man and nine women; age, 71.1±5.2 years) participated in this study. The FM of the left stance phase at a self-selected comfortable speed was measured using a motion capture system (OptiTrack; Natural Point Inc., USA) and a force plate (AccuGait; AMTI Inc., USA). Motion data and the force plate were captured at a sampling rate of 120 Hz. Motion data were used to calculate walking speed. The clockwise FM was defined as a positive value and normalized by body weight. The mean value of three success trials was used for the analysis. In addition, the TTA was manually measured using a goniometer.
The KOA and control groups were compared for walking speed, peak FM, impulse of positive FM (IFMp), impulse of negative FM, and TTA by using the Mann-Whitney test. The relationship between tibial torsion angle and each of the FM parameters was investigated within groups by using the Spearman rank correlation coefficient. For the KOA group, the relationship between the Kellgren-Lawrence grade and FM parameters was also examined in the same manner. Statistical analyses were performed using SPSS Statistics (IBM Inc., Japan). A significance level of 0.05 was used.
Results: Compared with the control group, the walking speed of the KOA group was significantly slower and the TTA was smaller. No significant difference in FM was found between the two groups.
In the relationship between TTA and the FM parameters, a positive correlation (ρ = 0.71) was found for peak FM in the control group, but in the KOA group, a negative correlation was observed for peak FM and IFMp (ρ = −0.73 and −0.63, respectively). No significant correlations were found between KOA severity and the FM parameters.
Conclusion(s): Although no significant difference was found between the KOA and control groups with respect to the magnitude of FM, the decrease in TTA, which is characteristic of KOA, was suggested to be related to FM.
Implications: In patients with KOA, FM at walking, which is a daily activity, is useful as an indicator of accumulated torsional stress in the lower limbs. However, whether the relationship between decreased TTA and FM is the cause or result remains unclear. Further studies are needed to investigate the influence of the difference in walking speed on the amplitude of FM.
Keywords: Free moment, Knee osteoarthritis, Tibial torsion
Funding acknowledgements: None
Purpose: This study aimed to clarify whether FM could be an index to characterize gait in KOA and to further examine the relationship between TTA and FM.
Methods: Eleven patients with KOA (one man and 10 women; age, 72.8±4.1 years; Kellgren-Lawrence grade of Ⅱ or Ⅲ) and 10 matched healthy volunteers (one man and nine women; age, 71.1±5.2 years) participated in this study. The FM of the left stance phase at a self-selected comfortable speed was measured using a motion capture system (OptiTrack; Natural Point Inc., USA) and a force plate (AccuGait; AMTI Inc., USA). Motion data and the force plate were captured at a sampling rate of 120 Hz. Motion data were used to calculate walking speed. The clockwise FM was defined as a positive value and normalized by body weight. The mean value of three success trials was used for the analysis. In addition, the TTA was manually measured using a goniometer.
The KOA and control groups were compared for walking speed, peak FM, impulse of positive FM (IFMp), impulse of negative FM, and TTA by using the Mann-Whitney test. The relationship between tibial torsion angle and each of the FM parameters was investigated within groups by using the Spearman rank correlation coefficient. For the KOA group, the relationship between the Kellgren-Lawrence grade and FM parameters was also examined in the same manner. Statistical analyses were performed using SPSS Statistics (IBM Inc., Japan). A significance level of 0.05 was used.
Results: Compared with the control group, the walking speed of the KOA group was significantly slower and the TTA was smaller. No significant difference in FM was found between the two groups.
In the relationship between TTA and the FM parameters, a positive correlation (ρ = 0.71) was found for peak FM in the control group, but in the KOA group, a negative correlation was observed for peak FM and IFMp (ρ = −0.73 and −0.63, respectively). No significant correlations were found between KOA severity and the FM parameters.
Conclusion(s): Although no significant difference was found between the KOA and control groups with respect to the magnitude of FM, the decrease in TTA, which is characteristic of KOA, was suggested to be related to FM.
Implications: In patients with KOA, FM at walking, which is a daily activity, is useful as an indicator of accumulated torsional stress in the lower limbs. However, whether the relationship between decreased TTA and FM is the cause or result remains unclear. Further studies are needed to investigate the influence of the difference in walking speed on the amplitude of FM.
Keywords: Free moment, Knee osteoarthritis, Tibial torsion
Funding acknowledgements: None
Topic: Musculoskeletal: lower limb; Musculoskeletal
Ethics approval required: Yes
Institution: Kashiwatanaka hospital
Ethics committee: Kashiwatanaka hospital ethics committee
Ethics number: 11
All authors, affiliations and abstracts have been published as submitted.
