Kai-Nan An

Mayo Clinic - Rochester, Рочестер, Minnesota, United States

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Publications (469)1015.83 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Cell-based tissue engineered tendons have potential to improve clinical outcomes following rotator cuff repair, especially in large or massive rotator cuff tears, which pose a great clinical challenge. The aim of this study was to develop a method of constructing a functional engineered tendon patch for rotator cuff repair with cyclic mechanical stimulation. Decellularized tendon slices (DTSs) were seeded with BMSCs and subjected to cyclic stretching for 1, 3, or 7 days. The mechanical properties, morphologic characteristics and tendon-related gene expression of the constructs were investigated. Viable BMSCs were observed on the DTS after 7 days. BMSCs penetrated into the DTSs and formed dense cell sheets after 7 days of mechanical stretching. Gene expression of type I collagen, decorin, and tenomodulin significantly increased in cyclically stretched BMSC-DTS constructs compared with the unstrained control group (P < 0.05). The ultimate tensile strength and stiffness of the cyclically stretched tendon constructs were similar to the unstrained control group (P > 0.05). In conclusion, mechanical stimulation of BMSC-DTS constructs upregulated expression of tendon-related proteins, promoted cell tenogenic differentiation, facilitated cell infiltration and formation of cell sheets, and retained mechanical properties. The patch could be used as a graft to enhance the surgical repair of rotator cuff tears. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Biomaterials 05/2015; 51. DOI:10.1016/j.biomaterials.2015.01.070 · 8.31 Impact Factor
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    ABSTRACT: The knee joint is generally characterized by very low friction and high wear resistance. Several previous studies have compared ACL with the commonly used allografts from tensile properties perspective. No study has reported about the graft tendons from a frictional perspective, which is an important parameter for ACL functional performance. Twenty hind legs were used to harvest FDP tendon, ACL, ACH, and patellar tendon. Samples were evaluated with surface friction testing, indentation testing for tendon compressive moduli, lubricin immunohistochemistry, and histologic analysis. Frictional force of FDP tendon and ACL was significantly less than that of patellar tendon and ACH at first and fifth cycles. At the tenth cycle, the FDP tendon, ACL, and ACH showed significantly less frictional force than patellar tendon; after 100 cycles, the FDP tendon and ACL showed significantly less frictional force than patellar tendon. The compressive moduli of the FDP tendon, ACL, and ACH were significantly greater than that of patellar tendon. Histologic results showed that FDP tendon and ACL had a smooth surface with a thin layer of epitenon cells; patellar tendon and ACH had a rough surface and a layer of paratenon. Lubricin was found on the surface and extracellular matrix of FDP tendon and ACL. There was only limited lubricin expression on the surface and extracellular matrix of the ACH and patellar tendon. The FDP tendon has friction force and lubricin expression similar to those of native ACL. However, patellar tendon and ACH show higher friction force and less lubricin expression than ACL. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Journal of Biomechanics 05/2015; DOI:10.1016/j.jbiomech.2015.04.041 · 2.50 Impact Factor
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    ABSTRACT: Background Total wrist arthroplasty (TWA) is a viable surgical treatment for disabling wrist arthritis. While current designs are a notable improvement from prior generations, radiographic loosening and failures remain a concern. Purpose The purpose of this investigation is to evaluate a new total wrist arthroplasty design kinematically. The kinematic function of a native, intact cadaveric wrist was compared with that of the same wrist following TWA. Method Six, fresh-frozen wrist cadaveric specimens were utilized. Each wrist was fixed to an experimental table and its range of motion, axis of rotation, and muscle moment arms were calculated. The following tendons were attached to the apparatus to drive motion: extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor carpi ulnaris (ECU), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), and abductor pollicis longus (APL). The wrist was then manually moved along a guide by an experimenter through a series of motions including flexion-extension, radial-ulnar deviation, and circumduction. The experiment was then performed on the specimen following implantation of the TWA. Results Following the TWA procedure, there were statistically significant decreases in the ulnar deviation and the flexion/ulnar deviation component of dart throw ranges of motion. There were no statistically significant changes in flexion, extension, radial deviation, the extension/radial deviation component of the dart thrower motion, or the circumduction range of motion. Conclusions Kinematic analysis of the new TWA suggests that a stable, functional wrist is achievable with this design. Clinical Relevance While appreciating the limitations of a cadaveric study, this investigation indicates that the TWA design studied merits study in human populations.
    05/2015; 4(2):121-7. DOI:10.1055/s-0035-1549288
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    ABSTRACT: Post-surgical treatment following laceration of the flexor pollicis longus (FPL) tendon has traditionally been based on analogies to finger flexor management. Although thumb and finger flexor tendons are similar, anatomic and biomechanical features unique to the FPL can make translating treatment techniques challenging.
    Journal of Hand Therapy 04/2015; DOI:10.1016/j.jht.2015.04.002 · 1.81 Impact Factor
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    ABSTRACT: Accurate diagnosis of wrist instability resulting from ligament injuries is crucial for providing the most effective interventions for preventing progression to osteoarthritis. Current imaging techniques are unable to detect injuries reliably and are static in nature, thereby capturing bone position information rather than motion which is indicative of ligament injury. A recently-developed technique, 4D (3D + time) CT enables 3D volume sequences to be obtained during wrist motion. The next step in successful clinical implementation of the tool is quantification and validation of measures obtained from the 4DCT image sequences. Methods of approach: Measures of bone motion and joint proximities are obtained by: segmenting bone volumes in each frame of the dynamic sequence, registering their positions relative to a known static posture, and generating surface polygonal meshes from which minimum distance (proximity) measures can be quantified. Method accuracy was assessed during in vitro simulated wrist movement by comparing a fiducial-based determination of bone orientation to a bone-based approach. The reported errors for the 4DCT technique were: 0.00- 0.68 deg in rotation; 0.02- 0.30 mm in translation. Results are on the order of the reported accuracy of other image-based kinematic techniques.
    Journal of Biomechanical Engineering 04/2015; 137(7). DOI:10.1115/1.4030405 · 1.75 Impact Factor
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    ABSTRACT: Dynamic loading on articular joints is essential for the evaluation of the risk of the articulation degeneration associated with occupational activities. In the current study, we analyzed the dynamic constraint loading for the thumb during pipetting. The constraint loading is considered as the loading that has to be carried by the connective tissues of the joints (i.e., the cartilage layer and the ligaments) to maintain the kinematic constraints of the system. The joint loadings are solved using a classic free-body approach, using the muscle forces obtained in a previous study (Wu et al., J Biomech, 47:392-9, 2014). The constraint forces in the thumb joint obtained in the current study are compared with those obtained in the pinch and grasp tests in a previous study (Cooney and Chao, J Bone Joint Surg Am, 59:27-36, 1977). The maximal compression force during pipetting is approximately 83% and 60% greater than those obtained in the tip pinch and key pinch, respectively, while substantially smaller than that obtained during grasping. The maximal lateral shear force is approximately six times, 32 times, and 90% greater than those obtained in the tip pinch, key pinch, and grasp, respectively. The maximal dorsal shear force during pipetting is approximately 3.2 and 1.4 times greater than those obtained in the tip pinch and key pinch, respectively, while substantially smaller than that obtained during grasping. Our analysis indicated that the thumb joints are subjected to repetitive, intensive loading during pipetting, compared to other daily activities.
    Journal of Biomechanical Engineering 04/2015; 137(8). DOI:10.1115/1.4030311 · 1.75 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the feasibility and reliability of passive muscle stiffness measurements in children by shear wave ultrasound elastography. We conducted a prospective cross-sectional study quantifying the passive stiffness of bilateral lateral gastrocnemius muscles during passive stretching in 20 typically developing children (age range, 2.0-12.6 years). Data collected included passive stiffness of the lateral gastrocnemius muscle (shear modulus in kilopascals) at 4 positions of progressive passive foot dorsiflexion, demographic characteristics of the participants, and comparison of demographic characteristics with the shear modulus. Passive stiffness increased with increasing stretching (mean [SD] range of stiffness, 7.1 [2.0] to 36.2 [22.0] kPa). For all 4 foot positions, no significant difference was found between right and left legs (range, P = .42 to P = .98) or between the sexes (range, P = .28 to P > .99). No correlation of passive muscle stiffness with age, body mass index, or ankle range of motion was found. The reliability of measurements was good to excellent (mean [95% confidence interval] range of reliability, 0.67 [0.44-0.83] to 0.80 [0.63-0.90]). Measurements of passive stiffness of the lateral gastrocnemius muscle are feasible and reliable in children as young as 2 years. Because this study found no significant difference between sex and the side tested in this age group, future studies involving children of this age range may not need to be stratified on the basis of these parameters. Defining normal passive muscle stiffness in children is critical for identifying and understanding the implications of abnormal passive muscle stiffness in children with neuromuscular disorders. © 2015 by the American Institute of Ultrasound in Medicine.
    Journal of ultrasound in medicine: official journal of the American Institute of Ultrasound in Medicine 04/2015; 34(4):663-70. DOI:10.7863/ultra.34.4.663 · 1.53 Impact Factor
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    ABSTRACT: In this paper, we model a simplified glenohumeral joint as a cam-follower mechanism during experimental simulated dislocation. Thus, humeral head trajectory and translational forces are predicted using only contact surface geometry and compressive forces as function inputs. We demonstrate this new interpretation of glenohumeral stability and verify the accuracy of the method by physically testing a custom-molded, idealized shoulder model and comparing data to the output of the 2D mathematical model. Comparison of translational forces between experimental and mathematical approaches resulted in r(2) of 0.88 and 0.90 for the small and large humeral head sizes, respectively. Comparison of the lateral displacement resulted in r(2) of 0.99 and 0.98 for the small and larger humeral head sizes, respectively. Comparing translational forces between experiments and the mathematical model when varying the compressive force to 30N, 60N, and 90N resulted in r(2) of 0.90, 0.82, and 0.89, respectively. The preliminary success of this study is motivation to introduce the effects of soft tissue such as cartilage and validation with a cadaver model. The use of simple mathematical models such as this aid in the set-up and understanding of experiments in stability research and avoid unnecessary depletion of cadaveric resources. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Journal of Biomechanics 03/2015; DOI:10.1016/j.jbiomech.2015.02.053 · 2.50 Impact Factor
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    ABSTRACT: Pre-surgical measurement of supraspinatus muscle extensibility is important for rotator cuff repair. The purpose of the present study was to explore the potential feasibility of a shear wave ultrasound elastography (SWE)-based method, combined with B-mode ultrasound, to measure the in vivo stiffness of the supraspinatus muscle non-invasively and thus obtain key information about supraspinatus muscle extensibility. Our investigation comprised two steps. First, we determined the orientation of the supraspinatus muscle fibers in cadaveric shoulders without rotator cuff tear in order to optimize the ultrasound probe positions for SWE imaging. Second, we investigated the feasibility of quantifying the stiffness of the normal supraspinatus muscle by SWE in vivo. The supraspinatus muscle was divided into four anatomical regions: anterior superficial (AS), posterior superficial (PS), anterior deep (AD), and posterior deep (PD). Each region was examined by SWE. The SWE stiffnesses of AD, AS, PD, and PS were 40.0 ± 12.4, 34.0 ± 9.9, 32.7 ± 12.7, 39.1 ± 15.7 kPa, respectively. SWE combined with B-Mode ultrasound imaging could be a feasible method for quantifying the local stiffness of the rotator cuff muscles. Clin. Anat., 2014. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.
    Clinical Anatomy 03/2015; 28(2). DOI:10.1002/ca.22498 · 1.16 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the biomechanical properties of modified repair techniques for flexor tendon reconstruction and the effects of surface modification using carbodiimide-derivatized synovial fluid plus gelatin (cd-SF-G), compared to the traditional repair techniques. The second and fifth digits from 16 canine forepaws were randomly divided into 4 groups: 1) traditional graft repairs (TGR group) including distal Bunnell repair and proximal Pulvertaft weave repair; 2) modified graft repairs (MGR group) including distal graft bony attachment repair and proximal step-cut repair; 3) Group TGR coated with cd-SF-G (TGR-C group); and 4) Group MGR coated with cd-SF-G (MGR-C group). Digit normalized work of flexion (nWOF), ultimate failure strength, and stiffness were measured. The nWOF in MGR group was significantly less than TGR group (P < 0.05). The nWOF in groups treated with cd- SF-G was significantly less than their untreated counterparts (P < 0.05). Ultimate load to failure of the MGR-C group was significantly greater than the TGR-C group (P < 0.05), but no significant difference in stiffness was found between these two groups. The modified techniques can not only improve tendon gliding abilities but can also improve breaking strength. Additionally, surface modification with cd-SF-G significantly decreased the work of flexion. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Journal of Orthopaedic Research 02/2015; 33(5). DOI:10.1002/jor.22844 · 2.97 Impact Factor
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    ABSTRACT: Carpal tunnel syndrome (CTS) is a peripheral neuropathy characterized by non-inflammatory fibrosis of the subsynovial connective tissues (SSCT). A rabbit model of CTS was developed to test the hypothesis that SSCT fibrosis causes the neuropathy. We used a cell-seeded collagen-gel contraction model to characterize the fibrosis in this model in terms of cellular mechanics, specifically to compare the ability of SSCT cells from the rabbit model and normal rabbits to contract the gel, and to assess the effect of transforming growth factor-β1,which is upregulated in CTS, on these cells. SSCT fibrosis was induced in six retired breeder female rabbits which were sacrificed at 6 weeks (N = 3) and 12 weeks (n = 3). An additional two rabbits served as controls. SSCT was harvested according to a standard protocol. Gels seeded with SSCT cells from rabbits sacrificed at 6 weeks had significantly higher tensile strength (p < 0.001) and Young's modulus (p < 0.001) than gels seeded with cells from rabbits sacrificed at 12 weeks or control animals. TGF-β1 significantly increased the decay time constant (p < 0.001), tensile strength (p < 0.001) and Young's modulus (p < 0.001) regardless of the cell source. This model may be useful in screening therapeutic agents that may block SSCT fibrosis, identifying possible candidates for CTS treatment. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Journal of Orthopaedic Research 01/2015; 33(5). DOI:10.1002/jor.22835 · 2.97 Impact Factor
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    ABSTRACT: Augmented soft tissue mobilization (ASTM) has been used to treat Achilles tendinopathy and is thought to promote collagen fiber realignment and hasten tendon regeneration. The objective of this study was to evaluate the biomechanical and histological effects of ASTM therapy on rabbit Achilles tendons after enzymatically induced injury. This study was a non-human bench controlled research study using a rabbit model. Both Achilles tendons of 12 rabbits were injected with collagenase to produce tendon injury simulating Achilles tendinopathy. One side was then randomly allocated to receive ASTM, while the other received no treatment (control). ASTM was performed on the Achilles tendon on postoperative days 21, 24, 28, 31, 35, and 38. Tendons were harvested 10 days after treatment and examined with dynamic viscoelasticity and light microscopy. Cross-sectional area in the treated tendons was significantly greater than in controls. Storage modulus tended to be lower in the treated tendons but elasticity was not significantly increased. Loss modulus was significantly lower in the treated tendons. There was no significant difference found in tangent delta (loss modulus/storage modulus). Microscopy of control tendons showed that the tendon fibers were wavy and type III collagen was well stained. The tendon fibers of the augmented soft tissue mobilization treated tendons were not wavy and type III collagen was not prevalent. Biomechanical and histological findings showed that the Achilles tendons treated with ASTM had better recovery of biomechanical function than did control tendons. Copyright © 2015 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.
    Journal of Manipulative and Physiological Therapeutics 01/2015; 12(2). DOI:10.1016/j.jmpt.2014.12.003 · 1.25 Impact Factor
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    ABSTRACT: The purpose of the current study was to develop a novel technology to enhance tendon-to-bone interface healing by trypsinizing and mineralizing (TM) an intrasynovial tendon allograft in a rabbit bone tunnel model. Eight rabbit flexor digitorum profundus (FDP) tendons were used to optimize the trypsinization process. An additional 24 FDP tendons were stratified into control and TM groups; in each group, 4 tendons were used for in vitro evaluation of TM and 8 were transplanted into proximal tibial bone tunnels in rabbits. The samples were evaluated histologically and with mechanical testing at postoperative week 8. Maximum failure strength and linear stiffness were not significantly different between the control and TM tendons. A thin fibrous band of scar tissue formed at the graft-to-bone interface in the control group. However, only the TM group showed obvious new bone formation inside the tendon graft and a visible fibrocartilage layer at the bone tunnel entrance. This study is the first to explore effects of TM on the intrasynovial allograft healing to a bone tunnel. TM showed beneficial effects on chondrogenesis, osteogenesis, and integration of the intrasynovial tendon graft, but mechanical strength was the same as the control tendons in this short-term in vivo study. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.
    Journal of Orthopaedic Research 01/2015; 33(4). DOI:10.1002/jor.22779 · 2.97 Impact Factor
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    ABSTRACT: The major concern of using a large animal model to study rotator cuff repair is the high rate of repair retears. The purpose of this study was to test a non-weight-bearing (NWB) canine model for rotator cuff repair research. First, in the in vitro study, 18 shoulders were randomized to 3 groups. 1) Full-width transections repaired with modified Mason-Allen sutures using 3-0 polyglactin suture, 2) Group 1 repaired using number 2 (#2) polyester braid and long-chain polyethylene suture, and 3) Partial-width transections leaving the superior 2 mm infraspinatus tendon intact without repair. In the in vivo study of 6 dogs, the infraspinatus tendon was partially transected as the same as the in vitro group 3. A radial neurectomy was performed to prevent weight bearing. The operated limb was slung in a custom-made jacket for 6 weeks. In the in vitro study, mean ultimate tensile load and stiffness in Group 2 were significantly higher than Group 1 and 3 (p<0.05). In the in vivo study, gross inspection and histology showed that the preserved superior 2-mm portion of the infraspinatus tendon remained intact with normal structure. Based on the biomechanical and histological findings, this canine NWB model may be an appropriate and useful model for studies of rotator cuff repair.
    PLoS ONE 01/2015; 10(6):e0130576. DOI:10.1371/journal.pone.0130576 · 3.53 Impact Factor
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    ABSTRACT: To determine if radiocapitellar contact pressures would be elevated with nonanatomical (circular) prostheses over those mimicking native anatomy and if such pressures would be related to the depth and contour of the articular dish and to the pattern of prosthetic articulation against the lateral trochlear ridge. Three commercially available circular radial head designs were compared with an anatomical radial head and 2 modified anatomical prototype radial head designs in 10 cadaveric specimens. Each prosthesis and specimen combination was loaded in neutral rotation and maximal extension with a custom testing apparatus while measuring contact areas and pressures using thin-film pressure sensors. Anatomical radial head prototype 2 had similar radiocapitellar contact areas and mean pressures as the native radial head; all other designs showed significant decreases in contact area and increased mean pressures. Peak contact pressures were also measured and were significantly elevated with all prostheses tested. Anatomical designs are statistically more likely to mimic normal contact with the lateral trochlear ridge and its adjacent sulcus than circular prostheses. They are also significantly less likely to have contact pressures above the 5 MPa threshold that is thought to be harmful to cartilage. The depth of the articular dish had a significant effect on contact area and pressure. Commercially available radial head prostheses demonstrated reduced radiocapitellar contact areas and elevated contact pressures during compressive loading. These were significantly greater with symmetrical circular prostheses than with asymmetrical elliptical designs. The prosthesis that best mimicked native contact behavior was the anatomical radial head prototype 2 owing to its design for articulating with the capitellum, the lateral trochlear ridge, and the sulcus between. Because radial head prostheses have the potential to cause capitellar erosion or arthritic change, those with lower contact pressures may lead to fewer such complications. Copyright © 2014 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.
    The Journal Of Hand Surgery 12/2014; 40(2). DOI:10.1016/j.jhsa.2014.11.005 · 1.66 Impact Factor
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    ABSTRACT: To determine the effect of capitellar impaction fractures on radiocapitellar stability in a model that simulated a terrible triad injury. Six cadaveric elbows were dissected free of skin and muscles. Tendons were preserved. The lateral collateral ligament was released and repaired (surgical control). Two sizes of capitellar impaction defects were created. After lateral collateral ligament release and repair, we then sequentially created osseous components of a terrible triad injury (partial radial head resection and coronoid fracture) through an olecranon osteotomy that was fixed with a plate. Radiocapitellar stability was recorded after the creation of each new condition. Significantly less force was required for radiocapitellar subluxation after the creation of 20° and 40° capitellar defects compared with the surgical control (intact capitellum). After the addition of a Mason type II radial head defect and then a coronoid defect, stability decreased significantly further. Impaction fractures of the distal portion of the capitellum may contribute to a loss of radiocapitellar stability, particularly in an elbow fracture-dislocation. Because these injuries may be unrecognized, consideration should be given to diagnosing and addressing them. Copyright © 2014 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.
    The Journal Of Hand Surgery 12/2014; 40(3). DOI:10.1016/j.jhsa.2014.10.031 · 1.66 Impact Factor
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    ABSTRACT: Numerous structural and compositional changes - related not only to age, but also activity level and sex - may affect skeletal muscle stiffness across the adult age-span. Measurement techniques available thus far have largely limited passive stiffness evaluations to those of entire joints and muscle-tendon units. Shear wave elastography is an increasingly popular ultrasound technique for evaluating the mechanical properties of skeletal muscle tissue. The purpose of this study was to quantify the passive stiffness, or shear modulus, of the biceps brachii throughout adulthood in flexed and extended elbow positions. We hypothesized that shear modulus would be higher in males relative to females, and with advanced age in both sexes. Shear wave elastography quantified biceps brachii stiffness at 90° elbow flexion and full extension in a large sample of adults between 21 and 94years old (n=133; 47 males). Regression analysis found sex and age were significant parameters for older adults (>60years) in full extension. As expected, shear modulus values increased with advancing age; however, shear modulus values for females tended to be higher than those for males. This study begins to establish normative trends for skeletal muscle shear modulus throughout adulthood. Specifically, this work establishes for the first time that the higher passive joint torque often found in males relative to females likely relates to parameters other than muscle shear modulus. Indeed, perhaps increases in skeletal muscle passive stiffness, though potentially altering the length-tension curve, serve a protective role - maintaining the tendon-muscle-tendon length-tension curve within a functional range. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Clinical biomechanics (Bristol, Avon) 11/2014; 30(1). DOI:10.1016/j.clinbiomech.2014.11.011 · 1.88 Impact Factor
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    ABSTRACT: Bone grafting procedures are increasingly popular for the treatment of anterior shoulder instability. In patients with a high risk of recurrence, open coracoid transplantation is preferred but can be technically demanding. Free bone graft glenoid augmentation may be an alternative strategy for high-risk patients without significant glenoid bone loss. This biomechanical cadaveric study assessed the stabilizing effect of free iliac crest bone grafting of the intact glenoid and the importance of sagittal graft position. Eight fresh frozen cadaveric shoulders were tested. The bone graft was fixed on the glenoid neck at 3 sagittal positions (50%, 75%, and 100% below the glenoid equator). Displacement and reaction force were monitored with a custom device while translating the humeral head over the glenoid surface in both anterior and anteroinferior direction. Peak force (PF) increased significantly from the standard labral repair to the grafted conditions in both anterior (14.7 ± 5.5 N vs 27.3 ± 6.9 N) and anteroinferior translation (22.0 ± 5.3 N vs 29.3 ± 6.9 N). PF was significantly higher for the grafts at the 50% and 75% positions compared with the grafts 100% below the equator with anterior translation. Anteroinferior translation resulted in significantly higher values for the 100% and 75% positions compared with the 50% position. This biomechanical study confirms improved anterior glenohumeral stability after iliac crest bone graft augmentation of the anterior glenoid. The results also demonstrate the importance of bone graft position in the sagittal plane, with the ideal position determined by the direction of dislocation. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.
    Journal of shoulder and elbow surgery / American Shoulder and Elbow Surgeons ... [et al.] 11/2014; 24(4). DOI:10.1016/j.jse.2014.09.018 · 2.37 Impact Factor
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    ABSTRACT: Carpal tunnel syndrome (CTS) is a very common pathology. Its most common diagnosis is idiopathic. Although it is accepted that chronic increase in pressure within the carpal tunnel is responsible for median nerve neuropathy, the exact pathophysiology leading to this pressure increase remains unknown. All the histological studies of the carpal tunnel in the CTS find a noninflammatory thickening of the subsynovial connective tissue (SSCT), which seems to be a characteristic of this pathology. Numerous animal models have been developed to recreate CTS in vivo to develop and improve preventive strategies and effective conservative treatments by a better understanding of its pathophysiology. The creation of a shear injury of the SSCT in a rabbit model induced similar modifications to what is observed in CTS, suggesting that this could be a pathway leading to idiopathic CTS.
    11/2014; 3(4):220-6. DOI:10.1055/s-0034-1394133
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    ABSTRACT: Carpal tunnel syndrome (CTS) is an idiopathic disease that results from increased fibrosis of the subsynovial connective tissue (SSCT). A recent study found overexpression of both transforming growth factor-β (TGF-β) and connective tissue growth factor (CTGF) in the SSCT of CTS patients. This study investigated TGF-β and CTGF expression in a rabbit model of CTS, in which SSCT fibrosis is induced by a surgical injury. Levels of TGF-β1 and CTGF at 6, 12, 24 weeks after injury were determined by immunohistochemistry A significant increase in TGF-β1 and a concomitant significant increase in CTGF were found at 6 weeks, in addition to higher cell density compared to normal (all p<0.05), Interestingly, CTGF expression was reduced at 12 and 24 weeks, suggesting that an initial insult results in a time limited response. We conclude that this rabbit model mimics the fibrosis found in human CTS, and may be useful to study pathogenetic mechanisms of CTS in vivo.
    PLoS ONE 09/2014; 9(9):e108312. DOI:10.1371/journal.pone.0108312 · 3.53 Impact Factor

Publication Stats

6k Citations
1,015.83 Total Impact Points

Institutions

  • 1985–2015
    • Mayo Clinic - Rochester
      • • Division of Orthopaedic Surgery
      • • Department of Orthopedics
      Рочестер, Minnesota, United States
  • 2014
    • Brown University
      Providence, Rhode Island, United States
  • 2013
    • Zimmer Holdings Inc.
      Warsaw, Indiana, United States
  • 2012
    • Bangkok University
      Krung Thep, Bangkok, Thailand
  • 2011
    • Osaka University
      • Division of Orthopaedic Surgery
      Suika, Ōsaka, Japan
  • 2005–2011
    • Sapporo Medical University
      • Division of Orthopaedic Surgery
      Sapporo, Hokkaidō, Japan
  • 2010
    • Logan University
      Missouri, United States
  • 2009
    • University of Rhode Island
      Кингстон, Rhode Island, United States
  • 2007
    • Imperial College London
      Londinium, England, United Kingdom
    • Naval Medical Center San Diego
      • Orthopedic Surgery Clinic
      San Diego, California, United States
  • 2006
    • Sapporo University
      Sapporo, Hokkaidō, Japan
  • 2002–2006
    • Baylor College of Medicine
      • Department of Orthopedic Surgery
      Houston, Texas, United States
    • Sungkyunkwan University
      • Samsung Medical Center
      Seoul, Seoul, South Korea
  • 2003
    • National Cheng Kung University
      • Institute of Biomedical Engineering (IBE)
      臺南市, Taiwan, Taiwan
    • Mayo Foundation for Medical Education and Research
      • Department of Physical Medicine and Rehabilitation
      Scottsdale, AZ, United States
  • 2001–2002
    • Brock University
      • Faculty of Applied Health Sciences
      St. Catharines, Ontario, Canada