1st Joint ESMAC-GCMAS Meeting - Análise de Marcha

O-34
PAIRED OUTCOME ASSESSMENT OF A MICROPROCESSOR CONTROLLED
KNEE VS A MECHANICAL PROSTHESIS
KR Kaufman, BK Iverson, DJ Padgett, RH Brey, JA Levine, MJ Joyner
Mayo Clinic, Rochester, MN, USA
Summary/Conclusions
The study has performed a multi-factorial analysis of patient outcomes using a microprocessor
controlled knee compared to a conventional mechanical knee. A paired comparison was
performed on 14 transfemoral amputees. The results demonstrated an improvement in gait and
balance when using the microprocessor knee which translated into increased activity during
daily life.
Introduction
Microprocessor controlled knee joints appeared on the market a decade ago and have some
data regarding their function. Comparative studies document improved gait symmetry 1,5 and
lower energy consumption 2,3,5 . The purpose of this study was to quantify the functional
characteristics of active transfemoral amputees using a microprocessor controlled knee
compared to the most prescribed mechanical knee joint.
Statement of clinical significance
Recent advances in prosthetic technology are leading to increased functionality.
Microprocessor controlled knee joints are more sophisticated and more expensive than
mechanical mechanisms. These prosthetic components need to be objectively analyzed in
order to verify the claims of manufacturers and the views of prosthetists and transfemoral
amputees currently using this technology.
Methods
This study employed a crossover design whereby only the knee component was changed. Each
subject was tested using a mechanical knee prosthesis (Mauch SNS or CaTech) and retested 2-
3 months later after receiving a microprocessor controlled knee joint (OttoBock C-leg).
Fourteen subjects were studied (mean age 42 + 9 years). All subjects were long-term
prosthesis users (20 + 11 years). Objective gait measurements were collected with a
computerized video motion analysis system utilizing ten infrared cameras (Eva RealTime 3D,
Motion Analysis Corp, Santa Rosa, CA). Simultaneously, ground reaction forces were
collected from four forceplates (Kistler Instrument Corp., Amherst NY, Model 8281B; AMTI,
Watertown MA, Model BP2416). The 3D marker coordinates and forceplate data were used as
input to a commercial software program (OrthoTrak 5.0, Motion Analysis Corp., Santa Rosa,
CA) to calculate the joint kinematics and kinetics. Subjects’ balance was tested on the Equitest
Posturography System. Energy consumption measurements were made using a commercially
available automated system (Medical Graphics Model CPX-D, St. Paul MN) modified to
interface to a respiratory mass spectrometer (Perkin Elmer 1100). Testing was performed at
0.45, 0.9, and 1.3 m/sec. Total daily energy expenditure was quantified using doubly-labeled
water. The Prosthetic Evaluation Questionnaire (PEQ) was used to obtained the patient’s
subjective perspective. Statistical comparisons were made using a paired t-test. Statistical
significance was set at an alpha level of 0.05.
Results
Subjects demonstrated improved gait and balance characteristics after receiving the
microprocessor controlled prosthetic knee joint. The knee moment demonstrated a significant
shift from an internal flexion moment toward a more normal extension moment during
midstance (Fig. 1). The subjects achieved greater gait symmetry. Their balance was
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