Page 1. J BONE JOINT SURG [BR] 2011; 93-B:SUPP IV 399 International Society for Technology in Art... more Page 1. J BONE JOINT SURG [BR] 2011; 93-B:SUPP IV 399 International Society for Technology in Arthroplasty Big Island, Hawaii, USA : 22–24 October 2009 President: Richard Komistek, PhD Correspondence should be addressed ...
Procedures for quantitative walking analysis include the assessment of body segment movements wit... more Procedures for quantitative walking analysis include the assessment of body segment movements within defined gait cycles. Recently, methods to track human body motion using inertial measurement units have been suggested. It is not known if these techniques can be readily transferred to clinical measurement situations. This work investigates the aspects necessary for one inertial measurement unit mounted on the lower back to track orientation, and determine spatio-temporal features of gait outside the confines of a conventional gait laboratory. Apparent limitations of different inertial sensors can be overcome by fusing data using methods such as a Kalman filter. The benefits of optimizing such a filter for the type of motion are unknown. 3D accelerations and 3D angular velocities were collected for 18 healthy subjects while treadmill walking. Optimization of Kalman filter parameters improved pitch and roll angle estimates when compared to angles derived using stereophotogrammetry. A Weighted Fourier Linear Combiner method for estimating 3D orientation angles by constructing an analytical representation of angular velocities and allowing drift free integration is also presented. When tested this method provided accurate estimates of 3D orientation when compared to stereophotogrammetry. Methods to determine spatio-temporal features from lower trunk accelerations generally require knowledge of sensor alignment. A method was developed to estimate the instants of initial and final ground contact from accelerations measured by a waist mounted inertial device without rigorous alignment. A continuous wavelet transform method was used to filter and differentiate the signal and derive estimates of initial and final contact times. The technique was tested with data recorded for both healthy and pathologic (hemiplegia and Parkinson’s disease) subjects and validated using an instrumented mat. The results show that a single inertial measurement unit can assist whole body gait assessment however further investigation is required to understand altered gait timing in some pathological subjects.
Total knee arthroplasty (TKA) is a common surgery to relieve knee pain and increase range of moti... more Total knee arthroplasty (TKA) is a common surgery to relieve knee pain and increase range of motion due to osteoarthritis (OA) in older patients. Minimally invasive, computer navigated techniques are gaining popularity for knee replacement surgery. These techniques may have potential to provide better functional outcomes over a shorter period of time. Little data exists comparing the early functional recovery of patients following total knee replacement surgery performed using various common approaches. This study compares the functional gait of patients two months after surgery performed using one of four common approaches to determine if differences exist in the immediate recovery. This knowledge will aid surgeons determine the best approach to use when performing surgery. This study was approved by the appropriate Institutional Review Board. Subjects volunteered to participate in the study and signed informed consent prior to testing. Subjects were excluded if the had significant diseases of the other joints of the lower extremity or a diagnosed disorder with gait disturbance. Patients were randomly assigned to receive unilateral primary TKA using standard parapatellar, mini-parapatellar, mini-midvastus, or mini-subvastus approaches. All patients received the same preoperative, perioperative, and postoperative critical pathways and standard orders. All incisions were five inches and all patients and examiners blinded to type of approach. Surgery was performed by one of two fellowship trained orthopedic surgeons. Patients visited the gait laboratory two months after receiving TKA. Motion data was captured using a ten-camera motion capture system (Motion Analysis Corp., Santa Rosa, CA). Three-dimensional force data was recorded using four floor embedded force platforms (AMTI Inc., Watertown, MA). Patients were asked to walk at a self selected speed along a 6.5 metre walkway. A minimum of five good foot strikes for each limb were recorded. Data were collected using EVaRT 5 software (Motion Analysis Corp., Santa Rosa, CA) and analyzed using OrthoTrak 6.2.8 (Motion Analysis Corp., Santa Rosa, CA) and MatLab software (The Mathworks Inc., Natick, MA). Statistical analysis was performed using SPSS 14.0 software (SPSS Inc., Chicago, Il) (α = 0.05). Fifty-two patients (72 ± 6 years) volunteered to participate in the study. The approaches used were: standard parapatellar – 12; mini-parapatellar – 12; mini-midvastus – 14; mini-subvastus – 14. Statistical analysis found no significant differences in any of the variables measured except minimum knee flexion angle during stance (p=.046). The variables measured included the maximum and minimum injured lower limb joint angles in all planes during both stance and swing phase of gait. Also measured were the maximum joint moments in all planes during stance and hip, knee, and ankle powers. Patients who received TKA using the mini-subvastus approach had greater knee extension through much of the single stance phase of the gait cycle which contributed to a lower (but not significant) peak knee flexion moment. These patients also had the highest ground reaction shear forces with higher ankle power absorption at foot strike and generation at push off. Mini-subvastus patients used a higher cadence to walk with a greater velocity then patients who received surgery using the other approaches. The results of this study show only minor differences in gait between patients who have received surgery using the different approaches. The limited numbers of patients in the study and the large variation in outcomes so soon after surgery mean that in most cases the differences that were measured do not reach significant level. This study shows that the surgical approach used to implant the device has no apparent effect on the ability of the person to ambulate following surgery, however further study with increased numbers of patients and observation over a longer period of time will allow a stronger conclusion. The knowledge gained from this and future studies will enable surgeons to make decisions on type of approach based on factors other than expectations of functional outcome.
It has long been suggested that various biological rhythms exhibit some degree of synchrony, and ... more It has long been suggested that various biological rhythms exhibit some degree of synchrony, and that stepping frequency is often linked to breathing frequency. Coupling of breathing and stepping rhythms is considered present when the interval between walking and breath events is constant for a series of breaths. Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation, altering breathing patterns and timing, which may in turn affect walking patterns due to coupling between breathing and walking. Many tools are available to assess coupling of different signals, however the nonlinear characteristics of walking and breathing patterns suggest that a nonlinear measure would be preferable. Cross sample entropy (xSE) was developed to quantify the probability that the patterns present in one signal will also be found in the other signal. The purpose of this study was to assess the coupling of breathing and walking patterns of persons, with and without COPD, using xSE. It was hypothesized that persons with COPD would exhibit lower xSE, indicating more closely coupled breathing and walking rhythms. Six patients with COPD and 12 healthy older controls walked on a treadmill for 3 minutes, at 5 speeds, while breathing and walking data were recorded. No significant differences in xSE were found between the groups except at the lowest speed, 20% lower than their self-selected pace (p = 0.029). When walking slowly, xSE for patients with COPD was less than controls, indicating that at these speeds breathing and walking patterns are most similar
ABSTRACT This study proposes the use of a combination of Weighted Fourier Linear Combiner and Fou... more ABSTRACT This study proposes the use of a combination of Weighted Fourier Linear Combiner and Fourier Linear Combiner algorithms to estimate lower trunk orientation angles during walking using the three angular velocity components measured by an inertial measurement unit. The proposed method enables the determination in real-time of the rotations around three local orthogonal axes defined relative to their initial orientations (pitch, roll, and yaw). Since the method is based on the analytical integration of a Fourier series, it is suitable for the analysis of quasi-periodic movements such as gait.
Total knee arthroplasty (TKA) is a common surgery to relieve knee pain and increase range of moti... more Total knee arthroplasty (TKA) is a common surgery to relieve knee pain and increase range of motion due to osteoarthritis (OA) in older patients. Minimally invasive, computer navigated techniques are gaining popularity for knee replacement surgery. These techniques may have potential to provide better functional outcomes over a shorter period of time. Little data exists comparing the early functional recovery of patients following total knee replacement surgery performed using various common approaches. This study compares the functional gait of patients two months after surgery performed using one of four common approaches to determine if differences exist in the immediate recovery. This knowledge will aid surgeons determine the best approach to use when performing surgery. This study was approved by the appropriate Institutional Review Board. Subjects volunteered to participate in the study and signed informed consent prior to testing. Subjects were excluded if the had significant...
Medical & Biological Engineering & Computing, 2022
Maintenance of postural control is a complex task that requires the integration of different sens... more Maintenance of postural control is a complex task that requires the integration of different sensory-motor processes. To improve postural control, balance training is often implemented using unstable surfaces. Little is known, however, about how different surfaces compare in terms of postural control strategy. Non-linear dynamical system analysis, like recurrent quantification analysis (RQA) applied to the center of pressure (CoP) trajectory, represents a useful tool in this respect. The aim of this study is to investigate the effects of different unstable supports on the CoP trajectory through a complementary approach based on linear and non-linear analyses. Seventeen healthy adults performed barefoot single-leg balance trials on a force plate and on three different balance training devices (soft disc, foam pad, and pillow). Sets of parameters were extracted from the CoP trajectories using classical stabilometric analysis (sway path, mean velocity, root mean square) and RQA (percent recurrence and determinism, maximum line length, entropy). Both classical and RQA analyses highlighted significant differences between stable (force plate) and unstable conditions (p < 0.001). Conversely, only classical stabilometric parameters showed significant differences among the considered balance training devices, indicating that the different characteristics of the devices do not influence the dynamic/temporal structure of the CoP trajectory. Analysis of the center of pressure trajectory during single-leg standing on three different balance training devices and on a rigid surface using both linear and non-linear techniques.
Page 1. J BONE JOINT SURG [BR] 2011; 93-B:SUPP IV 399 International Society for Technology in Art... more Page 1. J BONE JOINT SURG [BR] 2011; 93-B:SUPP IV 399 International Society for Technology in Arthroplasty Big Island, Hawaii, USA : 22–24 October 2009 President: Richard Komistek, PhD Correspondence should be addressed ...
Procedures for quantitative walking analysis include the assessment of body segment movements wit... more Procedures for quantitative walking analysis include the assessment of body segment movements within defined gait cycles. Recently, methods to track human body motion using inertial measurement units have been suggested. It is not known if these techniques can be readily transferred to clinical measurement situations. This work investigates the aspects necessary for one inertial measurement unit mounted on the lower back to track orientation, and determine spatio-temporal features of gait outside the confines of a conventional gait laboratory. Apparent limitations of different inertial sensors can be overcome by fusing data using methods such as a Kalman filter. The benefits of optimizing such a filter for the type of motion are unknown. 3D accelerations and 3D angular velocities were collected for 18 healthy subjects while treadmill walking. Optimization of Kalman filter parameters improved pitch and roll angle estimates when compared to angles derived using stereophotogrammetry. A Weighted Fourier Linear Combiner method for estimating 3D orientation angles by constructing an analytical representation of angular velocities and allowing drift free integration is also presented. When tested this method provided accurate estimates of 3D orientation when compared to stereophotogrammetry. Methods to determine spatio-temporal features from lower trunk accelerations generally require knowledge of sensor alignment. A method was developed to estimate the instants of initial and final ground contact from accelerations measured by a waist mounted inertial device without rigorous alignment. A continuous wavelet transform method was used to filter and differentiate the signal and derive estimates of initial and final contact times. The technique was tested with data recorded for both healthy and pathologic (hemiplegia and Parkinson’s disease) subjects and validated using an instrumented mat. The results show that a single inertial measurement unit can assist whole body gait assessment however further investigation is required to understand altered gait timing in some pathological subjects.
Total knee arthroplasty (TKA) is a common surgery to relieve knee pain and increase range of moti... more Total knee arthroplasty (TKA) is a common surgery to relieve knee pain and increase range of motion due to osteoarthritis (OA) in older patients. Minimally invasive, computer navigated techniques are gaining popularity for knee replacement surgery. These techniques may have potential to provide better functional outcomes over a shorter period of time. Little data exists comparing the early functional recovery of patients following total knee replacement surgery performed using various common approaches. This study compares the functional gait of patients two months after surgery performed using one of four common approaches to determine if differences exist in the immediate recovery. This knowledge will aid surgeons determine the best approach to use when performing surgery. This study was approved by the appropriate Institutional Review Board. Subjects volunteered to participate in the study and signed informed consent prior to testing. Subjects were excluded if the had significant diseases of the other joints of the lower extremity or a diagnosed disorder with gait disturbance. Patients were randomly assigned to receive unilateral primary TKA using standard parapatellar, mini-parapatellar, mini-midvastus, or mini-subvastus approaches. All patients received the same preoperative, perioperative, and postoperative critical pathways and standard orders. All incisions were five inches and all patients and examiners blinded to type of approach. Surgery was performed by one of two fellowship trained orthopedic surgeons. Patients visited the gait laboratory two months after receiving TKA. Motion data was captured using a ten-camera motion capture system (Motion Analysis Corp., Santa Rosa, CA). Three-dimensional force data was recorded using four floor embedded force platforms (AMTI Inc., Watertown, MA). Patients were asked to walk at a self selected speed along a 6.5 metre walkway. A minimum of five good foot strikes for each limb were recorded. Data were collected using EVaRT 5 software (Motion Analysis Corp., Santa Rosa, CA) and analyzed using OrthoTrak 6.2.8 (Motion Analysis Corp., Santa Rosa, CA) and MatLab software (The Mathworks Inc., Natick, MA). Statistical analysis was performed using SPSS 14.0 software (SPSS Inc., Chicago, Il) (α = 0.05). Fifty-two patients (72 ± 6 years) volunteered to participate in the study. The approaches used were: standard parapatellar – 12; mini-parapatellar – 12; mini-midvastus – 14; mini-subvastus – 14. Statistical analysis found no significant differences in any of the variables measured except minimum knee flexion angle during stance (p=.046). The variables measured included the maximum and minimum injured lower limb joint angles in all planes during both stance and swing phase of gait. Also measured were the maximum joint moments in all planes during stance and hip, knee, and ankle powers. Patients who received TKA using the mini-subvastus approach had greater knee extension through much of the single stance phase of the gait cycle which contributed to a lower (but not significant) peak knee flexion moment. These patients also had the highest ground reaction shear forces with higher ankle power absorption at foot strike and generation at push off. Mini-subvastus patients used a higher cadence to walk with a greater velocity then patients who received surgery using the other approaches. The results of this study show only minor differences in gait between patients who have received surgery using the different approaches. The limited numbers of patients in the study and the large variation in outcomes so soon after surgery mean that in most cases the differences that were measured do not reach significant level. This study shows that the surgical approach used to implant the device has no apparent effect on the ability of the person to ambulate following surgery, however further study with increased numbers of patients and observation over a longer period of time will allow a stronger conclusion. The knowledge gained from this and future studies will enable surgeons to make decisions on type of approach based on factors other than expectations of functional outcome.
It has long been suggested that various biological rhythms exhibit some degree of synchrony, and ... more It has long been suggested that various biological rhythms exhibit some degree of synchrony, and that stepping frequency is often linked to breathing frequency. Coupling of breathing and stepping rhythms is considered present when the interval between walking and breath events is constant for a series of breaths. Chronic obstructive pulmonary disease (COPD) is characterized by persistent airflow limitation, altering breathing patterns and timing, which may in turn affect walking patterns due to coupling between breathing and walking. Many tools are available to assess coupling of different signals, however the nonlinear characteristics of walking and breathing patterns suggest that a nonlinear measure would be preferable. Cross sample entropy (xSE) was developed to quantify the probability that the patterns present in one signal will also be found in the other signal. The purpose of this study was to assess the coupling of breathing and walking patterns of persons, with and without COPD, using xSE. It was hypothesized that persons with COPD would exhibit lower xSE, indicating more closely coupled breathing and walking rhythms. Six patients with COPD and 12 healthy older controls walked on a treadmill for 3 minutes, at 5 speeds, while breathing and walking data were recorded. No significant differences in xSE were found between the groups except at the lowest speed, 20% lower than their self-selected pace (p = 0.029). When walking slowly, xSE for patients with COPD was less than controls, indicating that at these speeds breathing and walking patterns are most similar
ABSTRACT This study proposes the use of a combination of Weighted Fourier Linear Combiner and Fou... more ABSTRACT This study proposes the use of a combination of Weighted Fourier Linear Combiner and Fourier Linear Combiner algorithms to estimate lower trunk orientation angles during walking using the three angular velocity components measured by an inertial measurement unit. The proposed method enables the determination in real-time of the rotations around three local orthogonal axes defined relative to their initial orientations (pitch, roll, and yaw). Since the method is based on the analytical integration of a Fourier series, it is suitable for the analysis of quasi-periodic movements such as gait.
Total knee arthroplasty (TKA) is a common surgery to relieve knee pain and increase range of moti... more Total knee arthroplasty (TKA) is a common surgery to relieve knee pain and increase range of motion due to osteoarthritis (OA) in older patients. Minimally invasive, computer navigated techniques are gaining popularity for knee replacement surgery. These techniques may have potential to provide better functional outcomes over a shorter period of time. Little data exists comparing the early functional recovery of patients following total knee replacement surgery performed using various common approaches. This study compares the functional gait of patients two months after surgery performed using one of four common approaches to determine if differences exist in the immediate recovery. This knowledge will aid surgeons determine the best approach to use when performing surgery. This study was approved by the appropriate Institutional Review Board. Subjects volunteered to participate in the study and signed informed consent prior to testing. Subjects were excluded if the had significant...
Medical & Biological Engineering & Computing, 2022
Maintenance of postural control is a complex task that requires the integration of different sens... more Maintenance of postural control is a complex task that requires the integration of different sensory-motor processes. To improve postural control, balance training is often implemented using unstable surfaces. Little is known, however, about how different surfaces compare in terms of postural control strategy. Non-linear dynamical system analysis, like recurrent quantification analysis (RQA) applied to the center of pressure (CoP) trajectory, represents a useful tool in this respect. The aim of this study is to investigate the effects of different unstable supports on the CoP trajectory through a complementary approach based on linear and non-linear analyses. Seventeen healthy adults performed barefoot single-leg balance trials on a force plate and on three different balance training devices (soft disc, foam pad, and pillow). Sets of parameters were extracted from the CoP trajectories using classical stabilometric analysis (sway path, mean velocity, root mean square) and RQA (percent recurrence and determinism, maximum line length, entropy). Both classical and RQA analyses highlighted significant differences between stable (force plate) and unstable conditions (p < 0.001). Conversely, only classical stabilometric parameters showed significant differences among the considered balance training devices, indicating that the different characteristics of the devices do not influence the dynamic/temporal structure of the CoP trajectory. Analysis of the center of pressure trajectory during single-leg standing on three different balance training devices and on a rigid surface using both linear and non-linear techniques.
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Papers by John McCamley