Evaluation of Dynamic Prosthetic Alignment Techniques for Individuals with Transtibial Amputation

125 Pages·2012·2.43 MB·English

Evaluation of Dynamic Prosthetic Alignment Techniques
for Individuals with Transtibial Amputation
by
Caroline (Wen Jia) Chen
A thesis submitted in conformity with the requirements
for the degree of Master of Health Science in Clinical Engineering
IBBME
University of Toronto
©Copyright by Caroline (Wen Jia) Chen 2012
ii

Evaluation of Dynamic Prosthetic Alignment Techniques
for Individuals with Transtibial Amputation
Caroline (Wen Jia) Chen
Master of Health Science in Clinical Engineering
Supervisor: Dr. Jan Andrysek
IBBME
University of Toronto
2012
Abstract
Although dynamic prosthetic alignment is an important process for the rehabilitation of
transtibial amputees, such alignment technique is subjective and inconsistent. Using
biomechanical variables and questionnaire assessments, this study compared an
instrument-assisted dynamic alignment technique using the Compas™ system and
conventional alignment techniques on nine adults with unilateral transtibial amputation.
A focus group discussion was conducted with six prosthetists to understand clinical
practice of dynamic alignment and their perception of the Compas™ system. Results
found that Compas™ produced more anterior weight line displacement and greater
varus moment on the prosthesis than conventional alignment techniques. Alignment
changes did not affect pelvic acceleration, and the instrument-assisted alignment
technique produced certain biomechanical changes but not necessarily better
alignments. Although the current version of the Compas™ system is not clinically
feasible, it can be used as a teaching/justification tool. Further investigation with larger
sample size and ankle alignment or moment measures is needed.
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Acknowledgments
I would like to thank my supervisor Dr. Jan Andrysek for his guidance and for this
research opportunity, and my committee members Dr. Ricardo Torres-Moreno and Dr.
Elaine Biddiss for their insightful feedback for critical analysis. I would also like to thank
the clinicians from Sunnybrook Health Sciences Centre, Karen Fairley, Winfried Heim,
Amy Richardson and Russell J Clements for their participation in the study, recruitment,
and clinical expertise.
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Table of Contents
Abstract ................................................................................................................................. ii
Acknowledgments ................................................................................................................ iii
List of Tables ....................................................................................................................... viii
List of Figures ........................................................................................................................ ix
List of Appendices ............................................................................................................... xiii
Chapter 1 Introduction and Motivation ................................................................................. 1
Chapter 2 Background and Literature Review ........................................................................ 2
1. Incidence and Prevalence of Extremity Amputations ................................................... 2
2. Amputee Rehabilitation .............................................................................................. 2
3. Prosthetic Alignments ................................................................................................. 3
3.1 Bench alignment ................................................................................................... 6
3.2 Static alignment .................................................................................................... 6
3.3 Dynamic alignment ............................................................................................... 7
4. Effects of a Prosthetic Misalignment ........................................................................... 8
4.1 Physiological and biomechanical effects ................................................................ 8
4.2 Gait deviation effects ............................................................................................ 9
5. Limitations of Conventional Alignment Techniques ................................................... 11
6. Prosthetic Outcome Measures for Dynamic Alignment .............................................. 12
7. Transtibial Prosthesis Model ..................................................................................... 14
7.1 Locations for alignment change ........................................................................... 14
8. Summary .................................................................................................................. 14
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Chapter 3 Objectives and Research Questions ...................................................................... 16
1. Primary Research Question ....................................................................................... 16
2. Secondary Research Questions ................................................................................. 17
3. Tertiary Research Questions ..................................................................................... 17
Chapter 4 Methods .............................................................................................................. 18
1. Clinical Setting .......................................................................................................... 18
2. Targeted Population and Recruitment ....................................................................... 18
3. Experimental Protocol .............................................................................................. 19
3.1 Visit 1 .................................................................................................................. 20
3.2 Visit 2 .................................................................................................................. 22
4. Instruments .............................................................................................................. 22
4.1 LASAR system ..................................................................................................... 23
4.2 Compas™ system ................................................................................................ 24
4.3 Shimmer™ tri-axial accelerometer ....................................................................... 28
5. Alignment Changes and Expected Outcomes using Model ......................................... 29
5.1 Expected weight line displacement ...................................................................... 30
5.2 Expected peak moment change ........................................................................... 32
6. Outcome Measures ................................................................................................... 34
6.1 Quantitative biomechanical variables .................................................................. 34
6.2 Characteristics assessments ................................................................................ 37
6.3 Subjective questionnaires ratings ........................................................................ 37
7. Data Analysis ............................................................................................................ 38
7.1 Weight line displacement data ............................................................................ 38
7.2 Peak below-socket moment data ........................................................................ 39
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7.3 Pelvic acceleration RMS data ............................................................................... 40
7.4 Statistics ............................................................................................................. 41
8. Focus Group Protocol ................................................................................................ 42
8.1 Roundtable discussion session............................................................................. 43
8.2 Analysis .............................................................................................................. 43
Chapter 5 Results ................................................................................................................. 44
1. Participants Characteristics ....................................................................................... 44
2. Results from LASAR Weight Line Displacement Data ................................................. 46
2.1 Results for primary research question ................................................................. 46
2.2 Results for second research question ................................................................... 48
2.3 Results for third research question ...................................................................... 52
3. Results from Below-Socket Peak Moment Data ......................................................... 53
3.1 Results for primary research question ................................................................. 54
3.2 Results for second research question ................................................................... 56
3.3 Results for third research question ...................................................................... 60
4. Results from RMS Values of Pelvic Acceleration Data ................................................ 62
4.1 Results for primary research question ................................................................. 62
4.2 Results for second research question ................................................................... 63
4.3 Results for third research question ...................................................................... 65
5. Results from Cadence Data ....................................................................................... 66
5.1 Results for primary research question ................................................................. 66
5.2 Results for third research question ...................................................................... 67
5.3 Results for validating acceleration data ............................................................... 68
6. Results from Subjective Questionnaire Ratings.......................................................... 70
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7. Results from Focus Group Discussion ........................................................................ 74
7.1 Focus group participants’ information ................................................................. 74
7.2 Focus group findings summary ............................................................................ 74
Chapter 6 Discussions and Limitations .................................................................................. 82
1. Discussions ............................................................................................................... 82
1.1 Findings for primary research question and clinical implications .......................... 82
1.2 Findings for secondary research questions and clinical implications ..................... 86
2. Limitations of Study Design ....................................................................................... 89
Chapter 7 Conclusion and Future Work ................................................................................ 94
References ........................................................................................................................... 96
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List of Tables
Table 1: Transtibial prosthetic settings and possible resulted gait deviations................. 11
Table 2: Tests during clinical visits and corresponding outcome measures .................... 20
Table 3: Research objectives and expected outcome measures ...................................... 35
Table 4: Participants’ demographics ................................................................................. 45
Table 5: Participants’ BMI and LCI scores ......................................................................... 46
Table 6: Alignment setup brought home by participants from Visit 1 ............................. 52
Table 7: Average peak moment variables and statistical test results .............................. 54
Table 8: Average normalized peak moment variables and statistical test results ........... 55
Table 9: Average RMS of pelvic acceleration variables and statistical test results .......... 63
Table 10: Preferred alignment setup for both visits by participants and prosthetists .... 71
Table 11: Prosthetists’ perceptions with the Compas system ......................................... 78
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List of Figures
Figure 1: Cartesian orthogonal system ............................................................................... 4
Figure 2: Alignment processes flow .................................................................................... 4
Figure 3: Example of alignment change of a transtibial prosthesis (Chow et al. 2006) ..... 5
Figure 4: Bench alignment of prosthetic components on a mechanical jig (Sin, 2001) ..... 6
Figure 5: A typical gait cycle (Plotnik et al, 2006) ............................................................. 10
Figure 6: Screw adjusting locations for tilt or shift alignment change ............................. 14
Figure 7: The LASAR system .............................................................................................. 23
Figure 8: Determining AP limb weight line (left), AP total weight line (middle) and ML
limb weight line displacement to knee centre (right) (Breakey, 1998) ............................ 24
Figure 9: Compas™ system (Orthocare Innovations, 2009) ............................................. 25
Figure 10: Compas™ system trial analysis plot ................................................................. 26
Figure 11: External ankle moments of the prosthetic limb of an unilateral transtibial
prosthetic user from literature (Klodd et al, 2010) .......................................................... 26
Figure 12: Compas™ system analysis suggestions (left: good alignment; right:
inadequate alignment) ...................................................................................................... 27
Figure 13: Shimmer™ accelerometer (Shimmer, 2011).................................................... 28
Figure 14: Biomechanical model of a transtibial prosthesis with alignment changes ..... 30
Figure 15: AP alignment change and expected weight line displacement ....................... 31
Figure 16: ML alignment change and expected weight line displacement ...................... 31
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Figure 17: AP alignment change and expected peak moment change ............................ 32
Figure 18: ML alignment change and expected peak moment change ........................... 33
Figure 19: Forefoot and heel peak moment (Nm) vs. time (s) in the AP direction
(MATLAB) .......................................................................................................................... 39
Figure 20: Varus and valgus peak moment (Nm) vs. time (s) in the ML direction
(MATLAB) .......................................................................................................................... 40
Figure 21: AP limb weight line displacement for two alignment techniques; ................. 47
Figure 22: AP total weight line displacement for two alignment techniques .................. 47
Figure 23: ML limb weight line displacement for two alignment techniques; ................. 48
Figure 24: AP limb weight line difference and alignment change .................................... 49
Figure 25: AP total weight line difference and alignment change ................................... 49
Figure 26: Individual AP limb weight line differences and alignment changes ................ 50
Figure 27: Individual AP total weight line differences and alignment changes ............... 51
Figure 28: ML limb weight line difference and alignment change Red circle: A suspected
outlier were noted ............................................................................................................. 51
Figure 29: AP limb weight line values between visits; ...................................................... 52
Figure 30: AP total weight line values between visits ...................................................... 53
Figure 31: ML limb weight line values between visits; ..................................................... 53
Figure 32: Individual varus peak moment between two alignment techniques .............. 55
Figure 33: AP forefoot peak moment difference and alignment change ......................... 56