About
48
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Introduction
Dr. Koo received his BEng(1st Hon) in Manufacturing Eng., MPhil in Rehab Eng., and PhD in Biomedical Eng. (Biomechanics Focus) from Hong Kong Polytechnic University in 1992, 1995, and 2002. He was a post-doc fellow at Johns Hopkins University between 2002 & 2003. He is currently a Professor at New York Chiropractic College. His research interests include: ultrasound bioinstrumentation, muscle mechanics; orthopedic biomechanics, stroke rehabilitation, seating biomechanics & manual therapy research.
Current institution
Additional affiliations
January 2006 - present
September 2018 - present
September 2011 - August 2018
Publications
Publications (48)
Objective: This study aimed to refine a magnetic resonance imaging (MRI)-ultrasound registration (ie, alignment) technique to make noninvasive, nonionizing, 3-dimensional measurement of the lumbar segmental motion in vivo.
Methods: Five healthy participants participated in this validation study. We scanned the lumbar region of each participant 5 t...
Objective
Novel accelerometry methods have been developed to assess and localize vibrations from zygapophyseal (Z) joint audible sounds (crepitus and cavitations) during normal lumbar motion and side‐posture spinal manipulation. This study assessed the reliability and validity of the methods.
Methods
A lumbar spine was embedded in silicone in the...
Freehand three-dimensional (3D) ultrasound has been used independently of other technologies to analyze complex geometries or registered with other imaging modalities to aid surgical and radiotherapy planning. A fundamental requirement for all freehand 3D ultrasound systems is probe calibration. The purpose of this study was to develop an actuator-...
Comprehensive assessments of scoliotic deformity and spinal instability require repetitive three-dimensional (3D) measurements of motion segments at different functional postures. However, accurate 3D measurement of the spine is a challenging task. In this paper, we present a novel, non-invasive, non-ionizing technique to quantify 3D poses of lumba...
Three-dimensional (3D) measurement of the spine can provide important information for functional, developmental, diagnostic, and treatment-effect evaluations. However, existing measurement techniques are either 2-dimensional, highly invasive, or involve a high radiation dose, prohibiting their widespread and repeated use in both research and clinic...
Objective:
Intraclass correlation coefficient (ICC) is a widely used reliability index in test-retest, intrarater, and interrater reliability analyses. This article introduces the basic concept of ICC in the content of reliability analysis.
Discussion for researchers:
There are 10 forms of ICCs. Because each form involves distinct assumptions in...
Objective:
The purpose of this study was to evaluate the performance of 5 analysis methods in quantifying scoliotic deformity, using the spatial positions of SP tips acquired by a custom-developed ultrasound-based system, with different curve fitting methods and angle metrics in terms of their correlation with Cobb angle, test-retest reliability,...
Quantifying passive stretching responses of individual muscles helps the diagnosis of muscle disorders and aids the evaluation of surgical/rehabilitation treatments. Utilizing an animal model, we demonstrated that shear elastic modulus measured by supersonic shear wave elastography increases linearly with passive muscle force. This study aimed to u...
In a companion ex vivo study of chicken muscles [1], we demonstrated that muscle elasticity measured by Supersonic shear wave elastography (SWE) increases linearly with passive tension, and hence, SWE could be an indirect measurement of passive muscle force. Objectives of the present study were: (1) Determine the test-retest reliability of SWE for...
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and
Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early
dhildhood mortality and growth failure data and their association with maternal
As muscle is stretched, it reacts with increasing passive resistance. This passive force component is important for normal muscle function. Unfortunately, direct measurement of passive muscle force is still beyond the current state-of-the-art. This study aimed to investigate the feasibility of using Supersonic shear wave elastography (SSWE) to indi...
The purpose of this study was to construct a computerized deformation-controlled indentation system and compare its test-retest reliability, repeatability, and sensitivity with a manual algometer for pressure pain threshold (PPT) measurements.
Pressure pain threshold measurements were made on 16 healthy subjects for 2 sessions on bilateral erector...
Background:
The inherent properties of surface electromyography limit its potential for multi-degrees of freedom control. Our previous studies demonstrated that wrist angle could be predicted by muscle thickness measured from B-mode ultrasound, and hence, it could be an alternative signal for prosthetic control. However, an ultrasound imaging mach...
Objectives of this study were to (1) quantify the immediate effect of Nimmo technique on muscle elasticity, pain perception, and disability and (2) evaluate comparative effectiveness of treating all primary and secondary trigger points (TrPs) vs primary TrP only.
Fourteen chronic low back pain subjects recruited from a chiropractic college were tes...
Soft tissue exhibits nonlinear stress-strain behavior under compression. Characterizing its nonlinear elasticity may aid detection, diagnosis, and treatment of soft tissue abnormality. The purposes of this study were to develop a rate-controlled Mechano-Acoustic Indentor System and a corresponding finite element optimization method to extract nonli...
A bone reposition device includes first and second bone supports for supporting first and second portions of a fracture or osteotomize bone about a fracture or osteotomize site, a plurality of sequentially connected connection members and a plurality of joints each with at least a pair of adjacent parts for connecting the connection members therebe...
Muscle thickness is a widely used parameter for quantifying muscle function in ultrasound imaging. However, current measurement techniques generally rely on manual digitization, which is subjective, time consuming, and prone to error. The primary purposes of this study were to develop an automated muscle boundary tracking algorithm to overcome thes...
Accurate anatomical reduction is a crucial step for operative treatment of diaphyseal fractures of long bone. Failure to realign the fracture site would result in delayed union, malunion, or non-union. Closed reduction is a reduction of a fractured bone by manipulation without incision into the skin. Conventionally, it is conducted under fluoroscop...
A computer aided method for closed tibial shaft fracture reduction based on measurements of 12 projection parameters (6 angulations and 6 translations) from an anteroposterior radiograph, a lateral radiograph, and a transverse projection photograph is examined. The development, validation and reliability of the computer aided method are presented....
This study was to extend previous neuromusculoskeletal modeling efforts through combining the in vivo ultrasound-measured musculotendon parameters on persons after stroke.
A subject-specific neuromusculoskeletal model of the elbow was developed to predict the individual muscle force during dynamic movement and then validated by joint trajectory. Th...
Previous musculoskeletal modeling studies have adopted the assumption of the same maximum isometric muscle stress among the prime elbow flexors. This study aimed at estimating the maximum isometric muscle stress based on subject-specific modeling parameters measured in vivo and validating that assumption.
Subject-specific musculoskeletal models of...
We recently developed an algorithm to perform closed fracture reduction using unilateral external fixator. Although its validity has been verified experimentally, the whole reduction process was not evaluated owing to the lack of a device that could facilitate its implementation in clinical practice. The objective of this study is to develop a prot...
An innovative computer-aided method to plan and execute long bone fracture reduction using Dynafix unilateral external fixator (EF) is presented and validated. A matrix equation, which represents a sequential transformation from proximal to distal ends, was derived and solved for the amount of rotation and translation required at each EF joint to c...
We developed a neuromusculoskeletal model to simulate the stretch reflex torque induced during a constant angular velocity elbow extension by tuning a set of physiologically-based parameters. Our model extended past modeling efforts in the investigation of elbow spasticity by incorporating explicit musculotendon, muscle spindle, and motoneuron pool...
Neuromusculoskeletal (NMS) modeling is a valuable tool in orthopaedic biomechanics and motor control research. To evaluate the feasibility of using electromyographic (EMG) signals with NMS modeling to estimate individual muscle force during dynamic movement, an EMG driven NMS model of the elbow was developed. The model incorporates dynamical equati...
A primary function of external fixator is to stabilize the fracture site after fracture reduction. Conventional fracture reduction method would result in fixator configurations deviated from its neutral configuration. How the non-neutral configurations would affect the biomechanical performance of unilateral external fixators is still not well-docu...
Axial dynamization has been shown in previous studies to promote callus formation, improve bone healing at fracture sites, and enhance bone remodeling. However, the possibility of non-axial movements or uniform fracture site compression during dynamization, and the appropriate relaxation of fixator joints to achieve such function, have not been inv...
Osteoporosis is a major public health problem that is characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. Poor bone quality in patients with osteoporosis presents the surgeon with difficult treatment decisions. Bone fracture...
The combination of human physiology with engineering modeling, analytical tools with advanced computer graphic visualization,
has brought the vision of the “Virtual Human” close to reality. This paper presents a full-featured biomechanical simulator
for the human musculoskeletal system with provisions to incorporate virtual implants or devices and...
To determine the distribution of weakness across elbow range of motion (ROM) in subjects with hemiparesis.
A detailed analysis of elbow torque and associated electromyographic signals of 5 prime elbow muscles generated during maximum isometric voluntary flexion (MIVF) and extension (MIVE) at 8 different elbow positions.
Rehabilitation center resear...
In the management of extremity trauma, after inserting the pins and applying the external fixator, adjustment of the bone segment is often necessary to reduce the fracture and correct any residual deformities. For a unilateral external fixator, the ability to adjust rotational and translational deformities is limited. Furthermore, the potential mal...
Koo TK, Mak AF, Hung LK, Dewald JP. Joint position dependence of weakness during maximum isometric voluntary contractions in subjects with hemiparesis. Arch Phys Med Rehabil 2003;84:1380–6.Objective: To determine the distribution of weakness across elbow range of motion (ROM) in subjects with hemiparesis.Design: A detailed analysis of elbow torque...
This study aimed at estimating the musculotendon parameters of the prime elbow flexors in vivo for both normal and hemiparetic subjects.
A neuromusculoskeletal model of the elbow joint was developed incorporating detailed musculotendon modeling and geometrical modeling.
Neuromusculoskeletal modeling is a valuable tool in orthopedic biomechanics and...
Spasticity often interferes with function, limits independence and may cause considerable disability. Elbow joint movement is involved in many daily living activities. A surface EMG driven musculoskeletal model was developed to predict joint trajectory and to compare the differences in the model parameters between the normal and spastic subjects. T...
This study aimed at investigating the effects of sitting posture on ischial pressure and pelvic orientation for two types of cushions.
Two types of seating devices, Roho and Polyurethane (PU) Foam cushions, six predefined postures, and two subject groups, Normal and Paraplegic, were tested. Ischial pressure and pelvic orientation were monitored. Th...
In the first part of this study, the inflation-pressure and interface-pressure profiles of an active cushion system, the Talley active air bellows cushion, were examined continuously for one complete working cycle using the dynamic pressure monitor. The relationship between the inflation pressure and the interface pressure was explored. A well-defi...
xiv, 206 leaves : ill. ; 30 cm. PolyU Library Call No.: [THS] LG51 .H577P REC 2002 Koo Neuromusculoskeletal (NMS) modeling is a valuable tool in orthopaedic biomechanics and motor control research. In this study, three NMS models of the upper extremity were developed, which described three different testing conditions: (1) maximum isometric volunta...
A bone reposition device includes first and second bone supports for supporting first and second portions of a fracture or osteotomize bone about a fracture or osteotomize site, a plurality of sequentially connected connection members and a plurality of joints each with at least a pair of adjacent parts for connecting the connection members therebe...
