James A Johnson

The University of Western Ontario, London, Ontario, Canada

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Publications (114)215.58 Total impact

  • Journal of Shoulder and Elbow Surgery. 09/2014; 23(9):e235.
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    ABSTRACT: Abstract Computer models capable of predicting elbow flexion and extension range of motion (ROM) limits would be useful for assisting surgeons in improving the outcomes of surgical treatment of patients with elbow contractures. A simple and robust computer-based model was developed that predicts elbow joint ROM using bone geometries calculated from computed tomography image data. The model assumes a hinge-like flexion-extension axis, and that elbow passive ROM limits can be based on terminal bony impingement. The model was validated against experimental results with a cadaveric specimen, and was able to predict the flexion and extension limits of the intact joint to 0° and 3°, respectively. The model was also able to predict the flexion and extension limits to 1° and 2°, respectively, when simulated osteophytes were inserted into the joint. Future studies based on this approach will be used for the prediction of elbow flexion-extension ROM in patients with primary osteoarthritis to help identify motion-limiting hypertrophic osteophytes, and will eventually permit real-time computer-assisted navigated excisions.
    Computer aided surgery : official journal of the International Society for Computer Aided Surgery. 05/2014;
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    ABSTRACT: Distal humeral hemiarthroplasty is a treatment option for distal humeral fractures, nonunions, and avascular necrosis. The biomechanical effects, however, have not been reported. The purpose of this in vitro study was to quantify the effects of hemiarthroplasty and implant size on elbow joint kinematics. Eight fresh-frozen cadaveric arms were mounted in an in vitro motion simulator. An electromagnetic tracking system quantified elbow kinematics. A custom distal humeral stem was implanted by use of navigation, and 3 humeral articular spools were evaluated: optimally sized, undersized, and oversized. Statistical analysis was performed with repeated-measures analysis of variance. Distal humeral hemiarthroplasty altered elbow kinematics, regardless of implant size. In the valgus position, the optimally sized implant resulted in a mean increase in valgus angulation of 3° ± 1° (P = .003) as compared with the osteotomy control. In the varus position, the optimal and undersized implants both resulted in significant increases in varus angulation: 3° ± 1° (P = .01) and 3° ± 1° (P = .001), respectively. The undersized implant had the greatest alteration in kinematics, whereas the oversized implant best reproduced native elbow kinematics. This study showed a small but significant alteration in elbow joint kinematics with placement of a distal humeral hemiarthroplasty implant, regardless of implant size. This could be due to errors in implant positioning and/or differences in the shape of the humeral implant relative to the native elbow. These changes in joint tracking may cause abnormal articular contact and loading, which may result in pain and cartilage degeneration over time.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 04/2014; · 1.93 Impact Factor
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    ABSTRACT: Autograft reconstruction of the coronoid using the tip of the olecranon has been described as a treatment option for comminuted coronoid fractures or coronoid nonunions that are not repairable. The purpose of this in vitro biomechanical study of the coronoid-deficient elbow was to determine whether coronoid reconstruction using the tip of the ipsilateral olecranon would restore elbow kinematics. An elbow motion simulator was used to perform active and passive extension of six cadaveric arms in the horizontal, valgus, varus, and vertical orientations. Elbow kinematics were quantified with use of the screw displacement axis of the ulna with respect to the humerus. Testing was performed with an intact coronoid, a 40% coronoid deficiency, and a coronoid reconstruction using the tip of the ipsilateral olecranon. Creation of a 40% coronoid deficiency resulted in significant changes (range, 3.6° to 10.9°) in the angular deviations of the screw displacement axis relative to the intact state during simulated active and passive extension in the varus orientation with the forearm in pronation and in supination (p < 0.05). Reconstruction of the coronoid using the ipsilateral olecranon tip restored the angular deviations to those in the intact state (p > 0.05) with the arm in all orientations except valgus, in which there was a small but significant difference (0.4° ± 0.2°, p = 0.04) during passive motion with forearm supination. Reconstruction of the coronoid using the tip of the ipsilateral olecranon was an effective method for restoring normal kinematics over a range of elbow motion from 20° to 120° in a cadaveric model of an elbow with a 40% coronoid deficiency. This reconstruction technique may prove beneficial for patients with elbow instability due to coronoid deficiency. This study supports the biomechanical concept of coronoid reconstruction using the ipsilateral olecranon tip for coronoid fractures or nonunions involving 40% of the coronoid process.
    The Journal of Bone and Joint Surgery 04/2014; 96(7):590-6. · 3.23 Impact Factor
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    ABSTRACT: Recurrent shoulder instability is commonly associated with Hill-Sachs defects. These defects may engage the glenoid rim, contributing to glenohumeral dislocation. Two treatment options to manage engaging Hill-Sachs defects are the remplissage procedure, which fills the defect with soft tissue, and the Latarjet procedure, which increases glenoid arc length. Little evidence exists to support one over the other. We performed a biomechanical comparison of the remplissage procedure to the traditional Latarjet coracoid transfer for management of engaging Hill-Sachs defects in terms of joint stiffness (resistance to anterior translation), ROM, and frequency of dislocation. Eight cadaveric specimens were tested on a shoulder instability simulator. Testing was performed with a 25% Hill-Sachs defect with an intact glenoid and after remplissage and Latarjet procedures. Joint stiffness, internal-external rotation ROM, and frequency of dislocation were assessed. Additionally, horizontal extension ROM was measured in composite glenohumeral abduction. After remplissage, stiffness increased in adduction with neutral rotation (12.7 ± 3.7 N/mm) relative to the Hill-Sachs defect state (8.7 ± 3.3 N/mm; p = 0.016). The Latarjet procedure did not affect joint stiffness (p = 1.0). Internal-external rotation ROM was reduced in abduction after the Latarjet procedure (49° ± 14°) compared with the Hill-Sachs defect state (69° ± 17°) (p = 0.009). Horizontal extension was reduced after remplissage (16° ± 12°) relative to the Hill-Sachs defect state (34° ± 8°) (p = 0.038). With the numbers available, there was no difference between the procedures in terms of the frequency of dislocation after reconstruction: 84% of specimens (27 of 32 testing scenarios) stabilized after remplissage, while 94% of specimens (30 of 32 testing scenarios) stabilized after the Latarjet procedure. Both procedures proved effective in reducing the frequency of dislocation in a 25% Hill-Sachs defect model, while neither procedure consistently altered joint stiffness. In the treatment of shoulder instability with a humeral head bone defect and an intact glenoid rim, this study supports the use of both the remplissage and Latarjet procedures. Clinical studies and larger cadaveric studies powered to detect differences in instability rates are needed to evaluate these procedures in terms of their comparative efficacy at preventing dislocation, as any differences between them seem likely to be small.
    Clinical Orthopaedics and Related Research 01/2014; · 2.79 Impact Factor
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    ABSTRACT: Computational measurement of joint contact distributions offers the benefit of non-invasive measurements of joint contact without the use of interpositional sensors or casting materials. This paper describes a technique for indirectly measuring joint contact based on overlap of articular cartilage computer models derived from CT images and positioned using in vitro motion capture data. The accuracy of this technique when using the physiological nonuniform cartilage thickness distribution, or simplified uniform cartilage thickness distributions, is quantified through comparison with direct measurements of contact area made using a casting technique. The efficacy of using indirect contact measurement techniques for measuring the changes in contact area resulting from hemiarthroplasty at the elbow is also quantified. Using the physiological nonuniform cartilage thickness distribution reliably measured contact area (ICC=0.727), but not better than when bone specific uniform cartilage thicknesses were assumed (ICC=0.673). When a contact pattern agreement score (sagree) was used to assess the accuracy of cartilage contact measurements made using physiological nonuniform or simplified uniform cartilage thickness distributions in terms of size, shape and location, their accuracies were not significantly different (p>0.05). The results of this study demonstrate that cartilage contact can be measured indirectly based on the overlap of cartilage contact models. However, the results also suggest that in some situations inter-bone distance measurements and an assumed cartilage thickness may suffice for predicting joint contact patterns.
    Journal of biomechanics 01/2014; · 2.66 Impact Factor
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    ABSTRACT: Background The optimal articular shape for distal humeral hemiarthroplasty has not been defined because of a paucity of data quantifying the morphology of the normal distal humerus. This study defines the osseous anatomy and anatomic variability of the distal humerus using 3-dimensional imaging techniques. Methods Three-dimensional surface models were created from computed tomography scans obtained from 50 unpaired human cadaveric elbows. Geometric centers of the capitellum and the trochlear groove defined the anatomic flexion-extension axis. A coordinate system was created, and the distal humerus was sectioned into 100 slices along this axis. The C line was defined as the line of best fit connecting the geometric centers of each of the slices. Results The anatomic flexion-extension axis of the distal humerus was found to be an average of 1° ± 1° from the C line (range, 0°-3°) in the coronal plane and 2° ± 1° (range, 0°-7°) in the transverse plane. The average trochlear width was 22 ± 3 mm, and the average trochlear height was 18 ± 2 mm. The mean width of the capitellum was 17 ± 2 mm; the height was 23 ± 2 mm (P < .001). Conclusions The difference in the capitellum width and height demonstrates that the capitellum is ellipsoid, not spherical. A data bank of humeral dimensions may be used for the development of future distal humeral hemiarthroplasty implants. A more anatomic implant may optimize kinematics and maximize contact area, thus minimizing contact stresses on the native ulna and radius.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 01/2014; · 1.93 Impact Factor
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    ABSTRACT: Background Hemiarthroplasty is a treatment option for selected distal humerus fractures. The purpose of this study was to determine the effect of distal humeral hemiarthroplasty and implant size on articular contact in the elbow. We hypothesized that implants produce significantly different contact areas compared with the native elbow, and that oversized and undersized implants will alter contact area compared to the optimal sized implant. Methods Eight cadaveric arms were tested in an elbow simulator and the kinematics were recorded. Three-dimentional reconstructions of bones and cartilage were generated from computed-tomography images to determine contact patterns. The native articulation was compared to optimally sized, oversized, and undersized implants (Latitude Anatomic Hemiarthroplasty). Changes in contact patterns relative to the native articulation were measured using total contact area and a contact patch agreement score, defined as the sum of distance between contact patches × area. The score indicates how well the size, shape, and location of the contact patches agrees with the native contact pattern. Findings The native articulation had significantly lower ulnohumeral contact patch agreement scores compared to all implants tested (p < 0.05). Mean ulnohumeral and radiocapitellar contact area decreased an average 44% (p = 0.03) and 4% (p = 0.07) respectively following placement of an optimally sized implant. There was no effect of implant size on contact area or contact patch agreement score (p > 0.05). Interpretation Shape differences of the elbow implants relative to the native joint may be responsible for altered contact patterns and could be improved with design modifications. These changes may predispose the elbow to degenerative arthritis. The lack of influence of implant size suggests that implant shape and materials may be more important than implant sizing during surgery. Level of Evidence: Basic Science Study
    Clinical biomechanics (Bristol, Avon) 01/2014; · 1.76 Impact Factor
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    ABSTRACT: Purpose To examine the effects of dorsal angulation deformities of the distal radius with and without triangular fibrocartilage complex (TFCC) rupture on the 3-dimensional kinematics of the distal radioulnar joint (DRUJ) during simulated active motion. Methods Nine fresh-frozen cadaveric specimens were tested in a forearm simulator that produced active forearm rotation. Dorsal angulation deformities of the distal radius with 10°, 20°, and 30° angulation were created. Changes in the position of the ulna relative to the radius at the DRUJ as a consequence of each dorsal angulation deformity were quantified during simulated active supination in terms of volar, ulnar, and distal displacement of the ulna. Testing was performed initially with the TFCC intact and repeated after complete sectioning of the TFCC at its ulnar insertion. Results Increasing dorsal angulation deformities of the distal radius significantly increased volar, ulnar, and distal displacement of the ulna when the TFCC was intact. Sectioning of the TFCC significantly increased volar displacement of the ulna in dorsal angulation deformities. As little as 10° of dorsal angulation significantly increased distal displacement of the ulna with the TFCC intact and resulted in a significant increase in volar, ulnar, and distal displacement of the ulna with sectioned TFCC. Conclusions Dorsal angulation deformities of the distal radius affect the 3-dimensional kinematics of the DRUJ, especially with the TFCC sectioned. Clinical relevance The progressive change in DRUJ kinematics with increasing dorsal angulation may partially explain the relationship between the magnitude of dorsal angulation of distal radius fractures and functional outcomes in younger patients. The status of the TFCC should be evaluated carefully, as well as the magnitude of osseous deformity in patients with distal radius fractures and malunions, because changes in DRUJ kinematics caused by dorsal angulation are greater when the TFCC is ruptured.
    The Journal of hand surgery 01/2014; · 1.33 Impact Factor
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    ABSTRACT: Background Distal humeral hemiarthroplasty is a treatment option for distal humeral fractures, nonunions, and avascular necrosis. The biomechanical effects, however, have not been reported. The purpose of this in vitro study was to quantify the effects of hemiarthroplasty and implant size on elbow joint kinematics. Methods Eight fresh-frozen cadaveric arms were mounted in an in vitro motion simulator. An electromagnetic tracking system quantified elbow kinematics. A custom distal humeral stem was implanted by use of navigation, and 3 humeral articular spools were evaluated: optimally sized, undersized, and oversized. Statistical analysis was performed with repeated-measures analysis of variance. Results Distal humeral hemiarthroplasty altered elbow kinematics, regardless of implant size. In the valgus position, the optimally sized implant resulted in a mean increase in valgus angulation of 3° ± 1° (P = .003) as compared with the osteotomy control. In the varus position, the optimal and undersized implants both resulted in significant increases in varus angulation: 3° ± 1° (P = .01) and 3° ± 1° (P = .001), respectively. The undersized implant had the greatest alteration in kinematics, whereas the oversized implant best reproduced native elbow kinematics. Conclusion This study showed a small but significant alteration in elbow joint kinematics with placement of a distal humeral hemiarthroplasty implant, regardless of implant size. This could be due to errors in implant positioning and/or differences in the shape of the humeral implant relative to the native elbow. These changes in joint tracking may cause abnormal articular contact and loading, which may result in pain and cartilage degeneration over time.
    Journal of Shoulder and Elbow Surgery. 01/2014;
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    ABSTRACT: The purpose of this biomechanical study was to compare anterograde with retrograde screw fixation for allograft reconstruction of Hill-Sachs defects. In 8 pairs of fresh-frozen humeral heads, a 40% Hill-Sachs defect was created. The resultant wedge-shaped osteochondral fragment was used as allograft. For each technique, two 3.75-mm screws were used for fixation. To test the strength of fixation, a custom tool was used that would apply load to the graft. By use of a materials testing machine, a staircase cyclic loading protocol was performed (500 cycles at 10, 20, 30, and 40 N) and then load to failure. Graft displacement was measured by an optical tracking system. For the 2 techniques, graft displacement increased with increasing load and increasing number of cycles up to a mean of 0.9 ± 0.42 mm for anterograde fixation and 1.1 ± 0.79 mm for retrograde fixation. This increase was significant within each technique across all 4 loading levels (P < .05). However, there were no significant differences in graft displacement between the 2 techniques at any loading level or number of cycles (P = .16 to P = .96). In addition, the load to failure between the anterograde and retrograde techniques (98.5 N and 95.6 N, respectively) was not significantly different (P = .706). The initial fixation and failure strength of anterograde and retrograde graft fixation techniques for substantial Hill-Sachs defects do not significantly differ in a biomechanical cadaveric model. This biomechanical study supports that in an engaging Hill-Sachs defect, both anterograde and retrograde screw fixation techniques can be used for fixation of humeral head allografts.
    Arthroscopy The Journal of Arthroscopic and Related Surgery 11/2013; · 3.10 Impact Factor
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    ABSTRACT: The effect of radial head implant length on forearm biomechanics is not well understood. This study examined the influence of an increase or decrease in radial head implant length on forearm load transfer as measured by interosseous membrane tension, and changes in radiocapitellar joint contact properties. An upper extremity simulator was utilized to examine six cadaveric specimens with five different radial head implant lengths (-4 mm, -2 mm, anatomically correct, +2 mm, +4 mm). A load sensing device was woven into the fibers of the interosseous membrane (IOM) to quantify its tension. An interpositional pressure measurement sensor was used to determine radiocapitellar joint contact area and pressure. Axial loads of 160 N were applied to the forearm through active pronation and supination with the elbow fixed at 90o of flexion. Increasing radial head implant length by 4 mm unloaded the IOM in all cases. Decreasing implant length by 4 mm significantly increased the IOM tension (p=0.005). No significant differences were found in IOM tension between the correct head implant length and the -2 mm implant (p=0.29). Contact pressure significantly increased with increasing radial head implant length (p=0.021) and contact area diminished with both an increase and decrease in radial head implant length, but this was not statistically significant (p=0.051). Increasing radial head implant length decreased IOM tension and increased radiocapitellar joint contact pressure. These findings illustrate the importance of precise restoration of radial length when performing a radial head replacement. If the native radial head length is difficult to accurately assess, avoid increasing the length of the radial head to prevent detrimental changes in the biomechanics of the forearm and the potential for clinically important radiocapitellar joint pathology.
    Journal of orthopaedic trauma 10/2013; · 1.78 Impact Factor
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    ABSTRACT: BACKGROUND:As an alternative to the standard single-point suture-anchor technique, a suture-bridge technique has been described for the treatment of bony Bankart fractures. There is, however, little evidence supporting one technique over the other.Purpose/ HYPOTHESIS:To compare the failure strength, fixation stability, and loading mechanics of the 2 techniques for the fixation of bony Bankart fractures. We hypothesized that use of the double-point suture-bridge technique would result in superior strength and fixation stability because of the increased compression and contact area between the bony fragment and glenoid fracture site. STUDY DESIGN:Controlled laboratory study. METHODS:A total of 16 shoulders (8 pairs) were tested with an intact glenoid, after creation of a 15% bony Bankart fracture, and after fragment fixation using a single-point or suture-bridge technique. Paired specimens were randomly assigned to each technique. Cyclic progressive loading was applied via a materials testing machine to the glenoid concentrically and eccentrically according to a staircase protocol. Failure strength, fragment displacement, glenoid strain load transfer, and contact area were quantified. RESULTS:No significant differences in failure strength were found between the single-point and suture-bridge techniques (mean strength, 74 ± 28 N vs 77 ± 56 N, respectively; P = .91). Additionally, no significant differences were found for glenoid load transfer (P ≥ .318) and glenohumeral joint contact (P = .357) between the 2 techniques. Centralized loading, however, produced significant differences in fragment displacement at 5, 150, and 200 N (P ≤ .045), with the single-point technique permitting greater fragment displacement in all cases (0.06-0.28 mm). Similarly, eccentric loading caused significantly greater fragment displacement with the single-point technique at ≥25 N compared with the suture-bridge technique (mean range, 0.38-0.63 mm vs 0.14-0.19 mm, respectively; .009 ≤ P ≤ .048). CONCLUSION:Single-point and suture-bridge techniques for the fixation of bony Bankart fragments have equivalent failure strengths and load transfers. The suture-bridge technique does provide statistically greater initial fracture fragment stability; however, the clinical implications of this are presently unknown. CLINICAL RELEVANCE:This study will aid in the selection of the optimal repair technique for bony Bankart fractures by providing important insights into the quality of initial fixation and ultimate strength.
    The American journal of sports medicine 09/2013; · 3.61 Impact Factor
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    ABSTRACT: Accurate determination of the flexion-extension axis of the elbow affects the outcome of implant replacement. The current study proposes an automated approach capable of determining the FE axis based on a stack of axial computer tomographic (CT) imaging slices of the distal humerus. The core of the algorithm consists of an original technique employing control polygon deformation used to approximate the segmented outer cortical bone points with closed B-Splines, followed by curvaturebased and least squares fitting methods for determination of the two relevant geometric centers. The new approach was validated against a conventional voxelbased FE axis determination procedure involving marching cubes algorithm.
    Computer-Aided Design and Applications 08/2013; 10(4):551-565.
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    ABSTRACT: The coronoid process has been recognized as a critical component in maintaining elbow stability. In the case of comminuted coronoid fractures, where repair is not possible or has failed, a prosthesis may be beneficial in restoring the osseous integrity of the elbow joint. The hypothesis of this in vitro biomechanical study was that a coronoid prosthesis would restore stability to the coronoid-deficient elbow. An anatomically shaped metallic coronoid prosthesis was designed and developed based on computed tomography-derived measurements and optimized to account for average cartilage thickness. Elbow kinematics and stability were determined for 8 cadaveric arms in active and passive elbow flexion in the varus, valgus, horizontal, and vertical positions using an elbow motion simulator. Varus-valgus angulation and internal-external rotation of the ulna relative to the humerus were quantified in the intact state, after collateral ligament sectioning and repair (control state), after a simulated 40% transverse coronoid fracture, and after implantation of the coronoid prosthesis. Internal rotation of the ulna increased with a 40% coronoid fracture in the horizontal and varus positions. Increases in varus angulation after coronoid fracture were also observed in the horizontal and varus positions, during active and passive flexion, respectively. Following implantation of the coronoid prosthesis, elbow kinematics were restored similar to control levels in all elbow positions. Our findings support our hypothesis that an anatomically shaped coronoid prosthesis would be effective in restoring stability to the coronoid-deficient elbow. This study provides evidence that the use of an anatomical implant restores stability to the coronoid-deficient elbow and rationale for further study and development of this method. For comminuted coronoid fractures, where repair is not possible or has failed, our research indicates that a prosthesis may be a feasible treatment option.
    The Journal of hand surgery 07/2013; · 1.33 Impact Factor
  • Joshua W Giles, James A Johnson, George S Athwal
    The American journal of sports medicine 07/2013; 41(7):NP32. · 3.61 Impact Factor
  • The American journal of sports medicine 07/2013; 41(7):NP31-2. · 3.61 Impact Factor
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    ABSTRACT: Little information exists on radial head implant diameter sizing methods. When the native head is absent due to extensive comminution or previous excision, the lesser sigmoid notch may be a useful landmark for sizing. We evaluated the reliability of native radial head measurements, and the lesser sigmoid notch, as landmarks for radial head implant diameter sizing. We examined 27 fresh frozen ulnae and their corresponding radial heads. The maximum, minimum, and dish diameters of the radial heads were measured. A radial head implant diameter was selected based on the congruency of the trial implants with the radius of curvature of the lesser sigmoid notch. Intraobserver and interobserver reliability for all measurements and implant selection were assessed using intraclass correlation coefficients (ICC). Correlations between the native radial head measurements and the selected radial head implant diameter or the lesser sigmoid notch radius of curvature were assessed using the Pearson correlation coefficient (PCC). Radial head diameter measurements demonstrated strong to excellent intraobserver (ICC ≥ 0.75) and interobserver reliability (ICC ≥ 0.82). The lesser sigmoid notch sizing method showed poor interobserver reliability (ICC = 0.34). Only a moderate correlation was found between the native radial head and the lesser sigmoid notch (PCC ≤ 0.80) or the selected radial head implant size (PCC ≤ 0.59). Radial head diameter measurements showed excellent reliability, suggesting that the excised radial head, when available, should be used to select the implant diameter. The reliability of using the lesser sigmoid notch for sizing the diameter of radial head implants was only moderate, suggesting this is an unreliable landmark for implant diameter sizing.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 06/2013; · 1.93 Impact Factor
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    ABSTRACT: PURPOSE: To determine the locations and volumes of bone requiring resection to restore range of motion in patients with osteoarthritis of the elbow, using computational modeling. METHODS: A total of 30 patients with primary osteoarthritis of the elbow and restricted range of motion underwent computed tomography. We used the computed tomography data to generate 3-dimensional models. We simulated flexion and extension of the elbow by flexing and extending the radius and ulna about the flexion-extension axis. The locations and volumes of impinging bone were calculated by the model at flexion angles of 0°, 10°, 20°, 120°, 130°, and 140°. RESULTS: Flexion simulations demonstrated bony overlap in many patients between the coronoid process and the coronoid fossa and between the radial head and the radial fossa. The volumes of these overlapping regions increased as the flexion angle increased. Extension simulations demonstrated bony overlap between the tip and sides of the olecranon and the corresponding regions of the olecranon fossa in most patients. These overlapping volumes increased in greater degrees of elbow extension. In addition, we found bony overlap in extension in several patients between the radial head and an osteophyte present on the posterior aspect of the capitellum. The mean total overlapping volumes at each flexion angle were 59 mm(3) at 120°, 238 mm(3) at 130°, and 589 mm(3) at 140° in flexion; and 184 mm(3) at 20°, 395 mm(3) at 10°, and 741 mm(3) at 0° in extension. CONCLUSIONS: Three-dimensional computational models identified the locations and volumes of bony impingement in patients with osteoarthritis of the elbow. They also highlighted certain unique regions of impingement, such as between the radial head with a posterior capitellar osteophyte in extension. CLINICAL RELEVANCE: This modeling approach may provide the surgeon with a useful patient-specific guide to ensure complete resection of impinging osteophytes.
    The Journal of hand surgery 05/2013; · 1.33 Impact Factor
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    ABSTRACT: It is important to study joint contact mechanics to better understand the processes which lead to cartilage degradation. The purpose of this study was to develop and validate a finite element (FE) model of a human elbow capable of predicting joint contact area and stress. A cylindrical constrained elbow joint loading apparatus was used to measure the cartilage compression and contact area for a single cadaveric specimen. A computer model of the same joint was created based on computed tomography images of the specimen, and the same loading was simulated using FE contact analysis. The model-predicted joint compression and contact area corresponded closely with experiment-measured results (differences of -4.9% and +9.6%). A sensitivity analysis showed that the model results were sensitive to cartilage and bone material properties, as well as the cartilage thickness distribution. The results of this study underline the importance of using accurate material properties and physiological cartilage thickness distributions when simulating cartilage contact mechanics.
    Journal of biomechanics 05/2013; · 2.66 Impact Factor

Publication Stats

703 Citations
215.58 Total Impact Points

Institutions

  • 2003–2014
    • The University of Western Ontario
      • • The Hand and Upper Limb Centre
      • • Department of Surgery
      • • Department of Mechanical and Materials Engineering
      • • Division of Orthopaedic Surgery
      London, Ontario, Canada
    • Lawson Health Research Institute
      London, Ontario, Canada
    • St. Joseph's Health Care London
      London, Ontario, Canada
  • 2013
    • University of Zurich
      Zürich, Zurich, Switzerland
  • 2002–2012
    • St. Joseph's Health Centre, Toronto
      Toronto, Ontario, Canada
  • 2007
    • St. Joseph's Hospital
      Savannah, Georgia, United States
    • University of Washington Seattle
      • Department of Orthopaedics and Sports Medicine
      Seattle, WA, United States
  • 2006
    • University of Guelph
      • School of Engineering
      Guelph, Ontario, Canada
    • Dalhousie University
      Halifax, Nova Scotia, Canada