GAIT RETRAINING TO IMPROVE STANCE TIME ASYMMETRY REDUCES KNEE EXTERNAL ADDUCTION MOMENTS: A CASE STUDY OF A UNILATERAL TRANSTIBIAL AMPUTEE 1
Hannah M. Rice, 1,2Steve T. Jamison, 3,4Alison L. Pruziner, 1Irene S. Davis
1
Spaulding National Running Center, Harvard Medical School, Cambridge, MA, USA. 2 The University of Delaware, Newark, DE, USA 3 Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD, USA. 4 DoD-VA Extremity Trauma and Amputation Center of Excellence email:
[email protected] INTRODUCTION Individuals with a unilateral transtibial amputation (TTA) are at increased risk of developing osteoarthritis (OA) in their intact limb knee [1]. During walking, these individuals load their intact limb for longer than their amputated limb and this asymmetric loading may result in joint pain [2]. Furthermore, greater knee external adduction moments (KEAM) have been reported in the intact versus amputated limb of these individuals [3]. Real-time feedback has previously been used to decrease asymmetry during a single treadmill walking session in individuals with a unilateral TTA [4]. It remains unclear whether a treadmill-based gait retraining program with a faded feedback design can improve symmetry in individuals with a unilateral TTA, and whether such changes translate to a reduced KEAM in the intact limb during overground walking. The objective of this case study was to evaluate the effect of gait retraining using real-time feedback on stance time asymmetry and intact limb KEAM during overground walking in an individual with a unilateral TTA. It was hypothesized that following retraining, stance time asymmetry would decrease, resulting in reduced intact limb KEAM. METHODS This case study involved a 40 year old female (67.9kg; 1.67m) with a left traumatic TTA. The participant had high functional capability, and reported no discomfort during walking. Following screening to ensure the participant met the inclusion criterion of ≥ 5% stance time asymmetry, a pretraining gait assessment was completed, followed by gait retraining, and finally a post-training assessment. During assessments, 7 trials were collected in which the participant walked along a
30-m runway at 1.1m.s-1 ±5%, contacting a force plate (AMTI, Watertown, MA) at its center, with the intact limb. Kinematic data were obtained using a 10-camera Vicon (Oxford, UK) system and fullbody markers. Twelve gait retraining sessions were conducted on an instrumented treadmill (AMTI, Watertown, MA) over a 7 week period. A harness was worn throughout retraining sessions to prevent injury if a fall occurred. A custom program (C-motion, Germantown, MD) calculated and displayed realtime stance time asymmetries for each gait cycle. This was displayed on a large screen positioned in front of the treadmill (Fig. 1).
Figure 1: Demonstration of real-time stance time asymmetry feedback. Colored bars indicate the magnitude and side of the stance time asymmetry.
Duration of retraining sessions increased from 10 to 30 minutes over 12 sessions. Feedback was provided for the entirety of the first 6 sessions. The amount of feedback was reduced in each of the final 6 sessions in a faded feedback design, to encourage internalization of the new walking pattern [5]. RESULTS Following gait retraining, stance time asymmetry was reduced by 32% (Fig. 2), and this corresponded with a 14% decrease in KEAM (Fig. 3). Post retraining there was a 2% increase in peak vertical
GRF, an 8% reduction in peak medial GRF, and a 3° increase in peak knee adduction angle (Table 1).
Figure 2: Mean (SD) stance time asymmetry during walking pre and post gait retraining.
baseline level of symmetry. It is plausible that the magnitude of change from pre to post training would be greater in a more asymmetric participant. Additional research is required to determine the success of this program in a larger population, and the ability of the participant to maintain changes without exposure to real-time feedback. As such, a follow-up assessment is planned after a period in which the participant undertakes focused walk training without feedback. If a more symmetric gait pattern can be maintained, the long-term risk of knee OA in the intact limb of individuals with a unilateral TTA may be reduced. CONCLUSIONS Based on this case study, gait retraining using visual real-time feedback is promising for improving stance time symmetry and reducing KEAM in individuals with a unilateral transtibial amputation. REFERENCES
Figure 3: Mean (SD) KEAM in the intact limb during walking pre and post gait retraining.
DISCUSSION The gait retraining program reduced stance time asymmetry in a participant with unilateral TTA. Intact limb KEAM was also reduced, likely as a result of the reduced peak medial GRF, despite the fact that the real-time feedback exclusively provided stance time asymmetry information. It is important to highlight that the changes in stance time asymmetry and intact limb KEAM observed in this case study occurred in a participant with a high
1. Lloyd CH, et al. Gait Posture 32, 296-300, 2010. 2. Nolan L, et al. Gait Posture 17, 142-51, 2003. 3. Royer TD, et al. Gait Posture 23, 303-6, 2006. 4. Dingwell JB, et al. POI 20, 101-10, 1996. 5. Crowell HP, et al. Clin Biomech, 26, 78-83, 2011.
ACKNOWLEDGEMENTS This work was supported by the BADER Consortium (DoD OR100017), a Department of Defense, Congressionally Directed Medical Research Programs cooperative agreement (W81XH-11-2-0222) and the DoD-VA Extremity Trauma & Amputation Center of Excellence (Public Law 110-417, National Defense Authorization Act 2009, Section 723). The views expressed in this abstract are those of the authors and do not necessarily reflect the official policy of the Departments of the Army, Navy, Defense, nor Veteran’s Affairs.
Table 1: Temporal, kinetic and kinematic parameters, pre and post gait retraining in the intact limb. Variable Mean (SD) pre Mean (SD) post % change Stance time asymmetry (%) 5.0 (9.0) 3.4 (6.3) -32 Peak KEAM (N.m) 49.7 (5.9) 42.9 (5.0) -14 Peak vertical GRF (N) 832.5 (41.0) 851.5 (25.4) +2 Peak medial GRF (N) 63.3 (4.0) 58.1 (13.9) -8 Peak knee adduction angle (°)
1.3 (0.5)
4.6 (0.5)
change (°)
+ 3.3
Gait retraining to improve stance time asymmetry reduces knee external adduction moments: A case study of a unilateral transtibial amputee 1Hannah
1
M. Rice, PhD,
1,2Steve
T. Jamison, PhD,
3,4Alison
L. Pruziner, PT, DPT, ATC,
1Irene
S. Davis, PhD, PT, FAPTA
Spaulding National Running Center, Department of Physical Medicine and Rehabilitation, Harvard Medical School, Cambridge, MA. 2 BADER Consortium, University of Delaware, Newark, DE. 3 Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD. 4 DoD-VA Extremity Trauma and Amputation Center of Excellence.
Introduction
Results
• Individuals with a unilateral transtibial amputation (UTTA) are at greater risk of developing intact knee OA1
Table 1: Intact limb gait variables pre and post gait retaining Variable
• This may result from:
Mean (SD) pre Mean (SD) post change
• longer stance time on the intact side versus amputated side during walking2
Stance time asymmetry (%)
5.0 (0.0)
3.4 (6.3)
-32 %
Peak KEAM (N.m)
49.7 (5.9)
42.9 (5.0)
-14 %
• greater knee external adduction moments in the intact side versus amputated side during walking3
Peak vertical GRF (N)
832.5 (41.0)
851.5 (25.4)
+2 %
Peak medial GRF (N)
63.3 (4.0)
58.1 (13.9)
-8 %
Peak knee adduction (°)
1.3 (0.5)
4.6 (0.5)
+3.3 °
• Stance time asymmetry has been reduced with real–time feedback during a single treadmill walking session in individuals with a UTTA4
Discussion
• Unknown whether this ‘new’ gait can be learned
Purpose
Fig. 1: Demonstration of real-time stance time asymmetry feedback. Colored bars indicate the magnitude and side of the stance time asymmetry
• Following gait retraining, stance time asymmetry was reduced • Supports previous findings following one session4 • Learning effect demonstrated
This case study aimed to evaluate the effect of gait retraining using real-time feedback on stance time asymmetry and intact limb knee external adduction moments (KEAM) in an individual with a UTTA.
• Reduced KEAM, likely due to reduced peak medial GRF • Despite only stance time asymmetry feedback
• May reduce risk of intact knee OA, if changes maintained
We hypothesized that following retraining, the individual would demonstrate: 1. Reduced stance time asymmetry
• Greater changes may be observed in individuals who demonstrate greater baseline asymmetry
2. Reduced intact limb KEAM
• Ability to maintain these changes longer-term to be assessed
Conclusions
Methods Participant • 40 year-old female (67.9 kg; 1.67 m), with a traumatic UTTA of the left limb •
High functional capability
•
Treadmill-assessed baseline asymmetry ≥ 5%
Fig. 2: Mean (SD) stance time asymmetry during walking, pre and post gait retraining
References & Acknowledgements
Protocol • Overground gait assessment, pre and post gait retraining:
1. Lloyd et al. (2010). Gait Posture, 32, 296-300.
• walking at 1.1 m.s-1 (±5%) • force and kinematic data collected
2. Nolan et al. (2003). Gait Posture, 17, 142-51. 3. Royer et al. (2006). Gait Posture, 23, 303-6. 4. Dingwell et al. (1996). POI, 20, 101-10.
• 12 treadmill gait retraining sessions across 7 weeks: • duration increased from 10 to 30 minutes • amount of feedback reduced in faded design • custom real-time feedback program (C-motion) • stance time asymmetry displayed for each gait cycle (Fig.1)
The results of this case study suggest that gait retraining using real-time feedback can improve stance time asymmetry, resulting in reduced KEAM in individuals with a unilateral, transtibial amputation. This may reduce the long-term risk of overuse injury in the intact limb.
Fig. 3: Mean (SD) KEAM in the intact limb during walking pre and post gait retraining
This work was supported by the BADER Consortium (DoD OR100017), a Department of Defense, Congressionally Directed Medical Research Programs cooperative agreement (W81XH-11-2-0222) and the DoD-VA Extremity Trauma & Amputation Center of Excellence (Public Law 110-417, National Defense Authorization Act 2009, Section 723). The views expressed in this abstract are those of the authors and do not necessarily reflect the official policy of the Departments of the Army, Navy, Defense, nor Veteran’s Affairs.
