C F Small

Queen's University, Kingston, Ontario, Canada

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Publications (22)17.29 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Computer assisted surgical interventions and research in joint kinematics rely heavily on the accurate registration of three-dimensional bone surface models reconstructed from various imaging technologies. Anomalous results were seen in a kinematic study of carpal bones using a principal axes alignment approach for the registration. The study was repeated using an iterative closest point algorithm, which is more accurate, but also more demanding to apply. The principal axes method showed errors between 0.35 mm and 0.49 mm for the scaphoid, and between 0.40 mm and 1.22 mm for the pisiform. The iterative closest point method produced errors of less than 0.4 mm. These results show that while the principal axes method approached the accuracy of the iterative closest point algorithm in asymmetrical bones, there were more pronounced errors in bones with some symmetry. Principal axes registration for carpal bones should be avoided.
    Journal of applied biomechanics 11/2010; 26(4):526-30. · 1.26 Impact Factor
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    ABSTRACT: The mechanical properties of the scapholunate ligament have been previously examined in small sample sizes, with ultimate load and occasionally stiffness reported. The present study examined 16 scapholunate ligaments in uniaxial extension at two rates and determined stiffness, ultimate load, and stress relaxation properties. Mean stiffness values of 66.4+/-28.6 N/mm at an elongation rate of 50 mm/min and 94.5+/-44.4 N/mm at an elongation rate of 100 mm/min were found. Relaxation behavior, determined by the percent load remaining after 100 s, was found to be 68.1+/-12%. Mean ligament ultimate loads were 357+/-110 N (n = 8). In eight specimens, failure occurred in bone. Positive correlations were observed between bone mineral density of the hand and ligament stiffness, ligament ultimate load, and bone ultimate load. No correlation was observed between bone mineral density and ligament load relaxation behavior. The results provide a comprehensive understanding of scapholunate ligament biomechanics and demonstrate a relationship between bone and ligament properties.
    Journal of Orthopaedic Research 08/2004; 22(4):867-71. · 2.88 Impact Factor
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    ABSTRACT: Three-dimensional (3-d) surface models of human carpal bones obtained from Computed Tomography (CT) were used to investigate their kinematic behavior throughout the entire physiological range of motion of the human wrist joint. The 3-d motion of the bones was visualized graphically by the finite helical axis (FHA) and smooth animations. It was found that extension mainly occurs in the radial-carpal joint and flexion is shared between the radial-carpal and midcarpal joints. During radial and ulnar deviation, the relative motion between the scaphoid and lunate was larger than in flexion-extension. This study will improve our understanding of carpal bone motion in a range of wrist poses, and will provide morphological data for the design of a functional wrist replacement arthroplasty.
    Medical Image Computing and Computer-Assisted Intervention -- MICCAI 2004, 7th International Conference Saint-Malo, France, September 26-29, 2004, Proceedings, Part II; 01/2004
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    ABSTRACT: To establish the accuracy, precision, and clinical feasibility of a novel technique of computer-assisted distal radius osteotomy for the correction of symptomatic distal radius malunion. Six patients underwent a computer-assisted distal radius osteotomy and were followed-up for an average of 25 months. Objective radiographic measurements and functional outcomes, as measured by clinical examination including grip strength and range of motion, and Disability of the Arm, Shoulder and Hand (DASH) questionnaires, were used. The mean radiographic parameters included an increase of radial inclination to 21 degrees from 12 degrees (normal, 23 degrees ). Dorsal and volar tilt (malunion) were corrected to 9 degrees from -30 degrees and 21 degrees, respectively (normal, 10 degrees ). Ulnar variance was corrected to 1.9 mm from 7.5 mm (normal, +1.5 mm). Normal is defined as the average of the contralateral limb radiographs. The mean clinical outcome measures at an average of 25 months included a DASH global score of 14, a DASH individual item average score of 1.6, and an average affected side grip strength of 79% when compared with the unaffected side. The results of the computer-assisted technique were comparable with published results of traditional non-computer-assisted opening wedge osteotomy techniques. This technique allows a surgeon to accurately and precisely recognize and correct 3-dimensional deformities of the distal radius including axial malalignment (supination). The technique has the added benefit of reducing radiation exposure to the patient and surgical team because fluoroscopy is not used during the procedure. Additional benefits of the computer-assisted technique include the ability to perform multiple surgical simulations to optimize the alignment plan, and it serves as an excellent teaching tool for less-experienced surgeons.
    The Journal Of Hand Surgery 12/2003; 28(6):951-8. · 1.57 Impact Factor
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    ABSTRACT: A three-dimensional developmental finite element model has been created to analyze load transmission pathways in the constrained carpus during static compressive loading. The bone geometry was extracted from an in vivo computed tomography scan using a combination of commercial and proprietary software. The complete geometry, including bone, cartilage, and ligament tissues, was compiled using a commercial finite element program. This model extends the state of biomechanical modeling by being the first to incorporate all eight carpal bones of the wrist and the related soft tissues in three dimensions. The model results indicate that cartilage material modulus and unconstrained carpal rotation have substantial impacts on the articular contact patterns and pressures.
    Annals of Biomedical Engineering 07/2003; 31(6):718-25. · 3.23 Impact Factor
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    ABSTRACT: PurposeTo establish the accuracy, precision, and clinical feasibility of a novel technique of computer-assisted distal radius osteotomy for the correction of symptomatic distal radius malunion.
    Fuel and Energy Abstracts 01/2003; 28(6):951-958.
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    ABSTRACT: We investigated the dependence of 20 radiographic carpal measurements (carpal indices) on rotational positioning errors in posteroanterior and lateral radiographs. The measurements were made from "true perspective" digitally reconstructed radiographs created from computed tomography data. Most posteroanterior indices were not affected by rotation. Carpal height, carpal height ratio, revised carpal height ratio, capitate-radius distance, and carpal ulnar translocation were particularly robust. Lateral-view indices involving the scaphoid were the most sensitive to simulated malpositioning: radioscaphoid, scapholunate, and scaphocapitate angles were reduced from 58 degrees, 48 degrees, and 56 degrees at true lateral to 30 degrees, 24 degrees, and 34 degrees, respectively, at 20 degrees external rotation. Observers were unable to estimate the degree of malpositioning accurately in either view. Our results support use of the "scaphopisocapitate" criterion for assessing correct positioning in lateral plain radiographs.
    The Journal Of Hand Surgery 06/2002; 27(3):435-42. · 1.57 Impact Factor
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    ABSTRACT: The objective was to develop a fixation-based three-dimensional presurgical planner and an intraoperative guidance system for distal radius osteotomy. Fixation-based surgery is a technique premised on using a fixation device, such as a fracture-fixation plate, during the alignment and distraction phases of an osteotomy. The planning system and guidance system were coded using OpenGL on UNIX workstations. In vitro tests were performed to compare the reproducibility of the computer-enhanced technique to that of the traditional technique, and an in vivo pilot study was initiated. In vitro, the computer-enhanced technique produced a significant reduction by more than one half in both the maximum error of correction and the standard deviation of the correction error. Preliminary in vivo results on six patients suggest that similar error diminution will occur during regular clinical application of the technique. Both studies showed that the computer system is simple to use. The planning system allowed the surgeon to perform multiple simulations of the surgical procedure preoperatively, which were used to optimize the plan and identify potential problems during realignment. The use of a fixation-based technique avoided the complexity of attempting to guide the surgeon to realign a bone fragment in six degrees of freedom of correction, and eliminated the use of X-ray fluoroscopy for achieving the alignment.
    Computer Aided Surgery 02/2001; 6(3):160-9. · 0.78 Impact Factor
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    ABSTRACT: A protocol for analysing three-dimensional metacarpophalangeal (MCP) joint motion in vivo using two markers on the proximal phalanx is described. The analysis uses an assumption that the rotation of the phalanx about its own long axis is zero. In an experimental study 24 volunteers had surface markers applied to the dorsal surfaces of their hands and index and long finger proximal phalanges, with three-dimensional marker positions recorded in two hand and finger postures in an incomplete box design using a test-retest protocol. Kinematic parameters from the optoelectronic system were compared with those obtained from three-dimensional reconstruction of bone landmarks and of the marker positions identified on stereoradiographs. Pronation/supination angles obtained from bone landmarks showed high test-retest variability, reflecting the difficulty in obtaining reliable pronation/supination data in small bones without the use of implanted markers. Changes in MCP joint extension and deviation angles determined using two surface markers agree with those obtained from bone landmarks. The results indicate a reproducible protocol for tracking MCP joint motion using only two phalangeal markers, suggesting that the 'no-rotation assumption' can be applied without affecting measures of extension and deviation motion in the normal joint.
    Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine 02/2001; 215(4):415-9. · 1.42 Impact Factor
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    ABSTRACT: . Fixation-based surgery is a new technique for achieving difficult corrections in some orthopedic procedures. The method is premised on using a fixation device, such as a fracture-fixation plate, during the alignment and distration phases of an open-wedge osteotomy. The basic idea is similar to assembly of manufactured components: pilot holes are drilled in the bone fragments, the fixation plate is attached to one fragment and, when the fragment is moved, the alignment has been achieved when the pilot holes in one fragment line up with predetermined through holes in the fixation plate. The method has been specifically developed to address osteotomy of the distal radius to correct a malunited fracture. The method has been validated in laboratory studies. Clinical trials suggest that the method is no slower than the conventional technique, there is almost no intraoperative X-ray exposure, and that exceptionally large corrections can easily be achieved. 1 Rationale and Objec...
    12/2000;
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    J Carey, C F Small, D R Pichora
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    ABSTRACT: The purpose of this study was to measure the structural stiffness (load/displacement response) and elastic modulus (stress-strain response) of the glenoid labrum at different locations throughout the tissue. It was intended that the results of this work would serve to define the properties of the labrum. This in turn may permit a better understanding of labral function and of the mechanics of injury or degeneration and may ultimately contribute to improving the design of future labral reconstruction procedures. In addition, these data may allow incorporation of labral properties into a glenoid arthroplasty component. The testing procedure consisted of rapid compression of the labrum using a flat indentor. Stiffness and modulus results demonstrated differences between the superior and inferior portions of the labrum. The elastic moduli findings for the labrum were 0.18 +/- 0.17, 0.11 +/- 0.16, and 0.23 +/- 0.20 MPa for the inferior anterior, inferior, and inferior posterior sections, respectively. The superior anterior, superior, and superior posterior sections were respectively 0.19 +/- 0.09, 0. 32 +/- 0.22, and 0.41 +/- 0.32 MPa. These results are similar to those of knee menisci. The modulus findings for the substrate cartilage were 1.92 +/- 0.78, 1.99 +/- 0.70, and 2.00 +/- 1.33 MPa for the inferior anterior, inferior, and inferior posterior sections, respectively. The superior anterior, superior, and superior posterior sections were respectively 1.60 +/- 0.79, 1.29 +/- 0.75, and 1.42 +/- 0.54 MPa, which are comparable to previous cartilage findings.
    Journal of Biomedical Materials Research 10/2000; 51(4):711-6.
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    ABSTRACT: Fixation-based surgery is a new technique for achieving difficult cor- rections in some orthopedic procedures. The method is premised on using a fixa- tion device, such as a fracture-fixation plate, during the alignment and distration phases of an open-wedge osteotomy. The basic idea is similar to assembly of manufactured components: pilot holes are drilled in the bone fragments, the fix- ation plate is attached to one fragment and, when the fragment is moved, the alignment has been achieved when the pilot holes in one fragment line up with predetermined through holes in the fixation plate. The method has been specifically developed to address osteotomy of the distal ra- dius to correct a malunited fracture. The method has been validated in laboratory studies. Clinical trials suggest that the method is no slower than the conventional technique, there is almost no intraoperative X-ray exposure, and that exception- ally large corrections can easily be achieved.
    Medical Image Computing and Computer-Assisted Intervention - MICCAI 2000, Third International Conference, Pittsburgh, Pennsylvania, USA, October 11-14, 2000, Proceedings; 01/2000
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    ABSTRACT: The in vitro mechanical properties of 14 wrist extensor tendons salvaged at surgery from patients with inflammatory (rheumatoid) arthritis and noninflammatory arthrosis were measured in uniaxial tension and compared. The rheumatoid tendons had higher extensibility at low stresses, lower stiffness in the linear portion of the stress-strain curve, greater rates of stress relaxation, and lower ultimate strengths than did the nonrheumatoid tendons. Differences in tangent modulus, stress remaining at 100 seconds, and ultimate tensile strength were significant at the 95% confidence level. In vivo, mechanically impaired tendons may play an important role in destabilization of the wrist in patients with rheumatoid arthritis.
    Journal of Orthopaedic Research 08/1998; 16(4):472-4. · 2.88 Impact Factor
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    F J Valero-Cuevas, C F Small
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    ABSTRACT: OBJECTIVE: The hypothesis tested was that generation of torque at the wrist affects joint kinematics. DESIGN: An in vivo study of normal wrist kinematics during plantar flexion motion against a constant load was undertaken, using a custom-designed instrumented apparatus to track the motion of the hand during the task. BACKGROUND: Despite clinical observations of a relationship between motion-loading and pain in wrists affected by rheumatoid arthritis, there is little published literature on thein vivo kinematics of the normal human wrist under load. METHODS: Ten volunteers with no wrist pathology were tested while generating torques of zero, 1.1 and 2.2 N m in a planar, unidirectional flexion motion. Hand kinematics were computed using the Planar Rigid Body Method algorithm and an 8 degrees angular step size. The finite radius of motion and the range and standard deviation of the residuals to a fitted second-order curve were used as indices of changes in the kinematics. RESULTS: The magnitude of both the range and standard deviation of the residuals were found to increase significantly with torque at the 95% confidence level. CONCLUSIONS: The wrist does not behave like a smooth mechanism when generating torque. Load affects carpal kinematics. RELEVANCE: We propose that fluctuations in the finite radius of motion are the natural kinematic consequence of intercarpal motion known to occur during wrist flexion. Wrist kinematics may be particularly sensitive to load and joint integrity because orchestrated intercarpal motion depends on the soundness of articular and ligamentous structures, the first to be affected in joint degenerating conditions such as rheumatoid arthritis. Thus, wrist kinematics under load may be a key to characterizing joint integrity. In wrist pathologies, simple planar testing of carpal kinematics under reproducible and controlled joint torque conditions may be a useful way to assess joint involvement before the onset of gross dysfunction, and to evaluate treatment outcomes.
    Clinical biomechanics (Bristol, Avon) 05/1997; 12(3):154-159. · 1.76 Impact Factor
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    ABSTRACT: Three-dimensional analysis of joint motion in vivo provides a tool for assessing the extent to which pathological conditions such as rheumatoid arthritis affect function. Kinematic analyses using conventional six-degree-of-freedom characterizations are strongly coordinate-system depen dent and require careful interpretation. An alternative method, examining the motion in configuration space, permits identification of the number of degrees of freedom used to perform the motion.Radial-ulnar deviation movements of the wrist joint were tracked optoelectronically in a group of twenty-eight volunteers with rheumatoid arthritis, and an age- and gender-matched group of control subjects. Normal wrists demonstrated highly repeatable one-dimensional configuration spaces for five cycles of hand movement. Wrists affected by rheumatoid arthritis displayed more disorganized and two-dimensional configuration spaces.Two parameters from the configuration space trajectories were defined to quantify the range of motion (ROM) and amount of inconsistency or ‘jitter’ in the movement. Plots of jitter against ROM for the population of fifty-six subjects showed strong separation of the case and control groups, with rheumatoid wrists displaying lower ROM and higher jitter. These indices provide a simple means of quantifying differences between rheumatoid and normal wrists with minimal coordinate-system dependence.
    Human Movement Science - HUM MOVEMENT SCI. 01/1997; 16(2):309-322.
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    ABSTRACT: OBJECTIVE: A study was undertaken to determine the experimental accuracy of a non-invasive optoelectonic 3-dimensional tracking system in assessing wrist joint motion. DESIGN: This was an in vivo experimental study involving volunteer subjects performing prescribed wrist motions. BACKGROUND: Current clinical practice does not include routine kinematic analysis for evaluating arthritic disease state, although motion disorders are common. METHODS: Surface markers were applied to 24 subjects assigned two hand postures in a test-retest factorial design for the expected range of motion. The marker positions were measured optoelectronically and using calibrated stereoradiography, to determine the positions of the surface markers and of key bone landmarks. Alignment and motion were compared for the three measurement techniques. Standard kinematic analyses were performed to extract Euler angles and equivalent screw displacement axes for paired postures. RESULTS: The three measurement techniques were highly correlated for wrist flexion-extension. Uncertainties were less than 6 degrees, similar to uncertainties from bone landmark identification errors when implanted markers cannot be used. Measures of motion exhibited higher correlations than those for alignment. Equivalent screw displacement axis orientations had poor intraclass correlations, reflecting sensitivity to coordinate system definitions. CONCLUSIONS: For motion analysis in the wrist in vivo, a non-invasive optoelectronic measurement system is as accurate as stereoradiographic analysis of bone segments.
    Clinical biomechanics (Bristol, Avon) 01/1997; 11(8):481-483. · 1.76 Impact Factor
  • Journal of Biomechanics - J BIOMECH. 01/1994; 27(6):768-768.
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    ABSTRACT: Characterization of the motion of the hand and wrist requires reference to the underlying bones which, for three-dimensional analyses, are assumed to be rigid bodies. Stereoradiogrammetric techniques involving the identification of prominent bone landmarks have been used as the standard against which surface markers used for in vivo testing have been evaluated. The precision and accuracy with which the 3D positions of bone landmarks in the hand and wrist could be determined was evaluated in a small inter-observer and inter-cadaver study and compared to the precision and accuracy with which implanted lead markers could be located. A subset of landmarks suitable for evaluating wrist and metacarpal-phalangeal joint motion was identified; the mean precision for identifying these points was better than 1.1 mm in all hand positions with a mean inter-observer accuracy of 2.3 mm. These values show that the average uncertainty in locating bone landmarks is at best roughly twice that for implanted markers.
    Journal of Biomedical Engineering 10/1993; 15(5):371-8.
  • C F Small, J T Bryant
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    ABSTRACT: A refinement to a previously described three-dimensional reconstruction algorithm based on point identification in calibrated non-orthogonal radiograms (stereo-pairs) is described. The modification involves a computation of the focal point magnitude of the point in three dimensions, analogous to focusing in two dimensions, as well as the most likely location of the target point in 3-space; the focal point magnitude may be thought of as the precision of the point identification. Multiple observer studies of the same stereopair can be used to estimate three-dimensional reconstruction accuracy by providing an average location and a mean distance from average. Both measures are useful parameters for initial selection of bone landmark references and for error propagation studies.
    Journal of Biomedical Engineering 04/1993; 15(2):163-6.
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    ABSTRACT: A method and apparatus for quantitative measurement of the alignment and motion of the joints of the hand in three dimensions has been developed using stereoradiogrammetric principles. Alignment in planes of flexion-extension and radial-ulnar deviation can be determined to within 2.5 degrees; rotation about the long axis of the metacarpals or phalanges is more difficult to determine, and can be measured to within 7 degrees. Stereo views subtending angles in the range of 40 degrees were found to optimize the total system accuracy.
    Journal of Biomedical Engineering 04/1993; 15(2):99-105.

Publication Stats

235 Citations
17.29 Total Impact Points

Institutions

  • 1992–2010
    • Queen's University
      • • Department of Mechanical and Materials Engineering
      • • Division of Orthopaedic Surgery
      Kingston, Ontario, Canada
  • 2002–2004
    • Kingston General Hospital
      Kingston, Ontario, Canada
  • 2000
    • University of Ottawa
      • Department of Mechanical Engineering
      Ottawa, Ontario, Canada