Publications (10)16.36 Total impact
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Article: Failure locus of the anterior cruciate ligament: 3D finite element analysis.
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ABSTRACT: Anterior cruciate ligament (ACL) disruption is a common injury that is detrimental to an athlete's quality of life. Determining the mechanisms that cause ACL injury is important in order to develop proper interventions. A failure locus defined as various combinations of loadings and movements, internal/external rotation of femur and valgus and varus moments at a 25(o) knee flexion angle leading to ACL failure was obtained. The results indicated that varus and valgus movements were more dominant to the ACL injury than femoral rotation. Also, Von Mises stress in the lateral tibial cartilage during the valgus ACL injury mechanism was 83% greater than that of the medial cartilage during the varus mechanism of ACL injury. The results of this study could be used to develop training programmes focused on the avoidance of the described combination of movements which may lead to ACL injury.Computer Methods in Biomechanics and Biomedical Engineering 05/2011; 15(8):865-74. · 0.85 Impact Factor -
Article: Effect of frontal plane tibiofemoral angle on the stress and strain at the knee cartilage during the stance phase of gait.
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ABSTRACT: Subject-specific three-dimensional finite element models of the knee joint were created and used to study the effect of the frontal plane tibiofemoral angle on the stress and strain distribution in the knee cartilage during the stance phase of the gait cycle. Knee models of three subjects with different tibiofemoral angle and body weight were created based on magnetic resonance imaging of the knee. Loading and boundary conditions were determined from motion analysis and force platform data, in conjunction with the muscle-force reduction method. During the stance phase of walking, all subjects exhibited a valgus-varus-valgus knee moment pattern with the maximum compressive load and varus knee moment occurring at approximately 25% of the stance phase of the gait cycle. Our results demonstrated that the subject with varus alignment had the largest stresses at the medial compartment of the knee compared to the subjects with normal alignment and valgus alignment, suggesting that this subject might be most susceptible to developing medial compartment osteoarthritis (OA). In addition, the magnitude of stress and strain on the lateral cartilage of the subject with valgus alignment were found to be larger compared to subjects with normal alignment and varus alignment, suggesting that this subject might be most susceptible to developing lateral compartment knee OA.Journal of Orthopaedic Research 12/2010; 28(12):1539-47. · 2.81 Impact Factor -
Article: The effect of the frontal plane tibiofemoral angle and varus knee moment on the contact stress and strain at the knee cartilage.
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ABSTRACT: Subject-specific models were developed and finite element analysis was performed to observe the effect of the frontal plane tibiofemoral angle on the normal stress, Tresca shear stress and normal strain at the surface of the knee cartilage. Finite element models were created for three subjects with different tibiofemoral angle and physiological loading conditions were defined from motion analysis and muscle force mathematical models to simulate static single-leg stance. The results showed that the greatest magnitude of the normal stress, Tresca shear stress and normal strain at the medial compartment was for the varus aligned individual. Considering the lateral knee compartment, the individual with valgus alignment had the largest stress and strain at the cartilage. The present investigation is the first known attempt to analyze the effects of tibiofemoral alignment during single-leg support on the contact variables of the cartilage at the knee joint. The method could be potentially used to help identify individuals most susceptible to osteoarthritis and to prescribe preventive measures.Journal of applied biomechanics 11/2010; 26(4):432-43. · 0.76 Impact Factor -
Article: Managing gait disorders in older persons residing in nursing homes: a review of literature.
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ABSTRACT: Managing gait disorders in the nursing home setting is a challenge. Nursing home residents can present with a variety of factors that may contribute to the presentation of gait abnormalities. The development of an individualized intervention program can be effective in improving a resident's ability to ambulate. This article reviews the research pertaining to the management of gait disorders including deconditioning, therapeutic exercise intervention, dementia, and cardiovascular and cardiopulmonary systems. The review provides the reader with strategies to help improve and understand gait performance in older persons residing in nursing homes.Journal of the American Medical Directors Association 06/2009; 10(4):230-7. · 4.64 Impact Factor -
Article: Integrated physical therapy intervention for a person with pectus excavatum and bilateral shoulder pain: a single-case study.
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ABSTRACT: To examine the effects of an individualized physical therapy (PT) program for a subject with pectus excavatum and bilateral shoulder pain. Single-case study of a man diagnosed with moderate-to-severe pectus excavatum and constant bilateral shoulder pain. Exercise tolerance was measured through the Bruce protocol and home exercise log, pulmonary function, ventilatory muscle strength, echocardiography, chest wall and abdominal excursion, self-perception of pectus excavatum, and a variety of anthropometric and volumetric tests before and after PT. University laboratory. A 22-year-old man. A 3-month PT program including breathing exercises and therapeutic exercises. Exercise tolerance, ventilatory muscle strength, chest wall and abdominal excursion, self-perception of the pectus excavatum, and other anthropometric and volumetric tests. The most striking anthropometric and volumetric test change was the pectus severity index (in H2O), which decreased from 50 to 20 mL H2O (60% change). The subject reported no shoulder pain at rest and with recreational activity after 8 weeks of intervention. An individualized PT program provided minimal-to-moderate improvements on many characteristics of pectus excavatum. Bilateral shoulder pain was eliminated. An individualized PT program integrating cardiopulmonary and musculoskeletal interventions that is provided to other patients with pectus excavatum may provide similar results. However, PT provided to younger patients with the pectus excavatum may be of even greater benefit because of a less mature skeleton. Further investigation of the effects of PT intervention provided to younger and older persons with the pectus excavatum is needed.Archives of physical medicine and rehabilitation 12/2008; 89(11):2195-204. · 2.18 Impact Factor -
Article: Effects of a plyometric program on vertical landing force and jumping performance in college women.
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ABSTRACT: To examine the effects of a plyometric program on peak vertical ground reaction force as well as kinetic jumping characteristics in recreationally athletic college women. Six week prospective exercise intervention. Division I university campus. Twenty college females who competed recreationally in basketball were randomly assigned to a training (n=10) or control (n=10) group. The absolute change values for vertical ground reaction force, countermovement jump height, peak and average jump power, and peak jump velocity. Comparisons were made using Mann-Whitney U tests. Vertical ground reaction force decreased in the intervention group (-222.8+/-610.9N), but was not statistically different (p=0.122) compared to the change observed in the control group (54.6+/-257.6N). There was no difference in the absolute change values between groups for countermovement jump height (1.0+/-2.8cm vs. -0.2+/-1.5cm, p=0.696) or any of the associated kinetic variables following the 6-week intervention. Although not statistically significant, the mean absolute reduction in vertical ground reaction force in the training group is clinically meaningful. Eight of the 10 women in the training group reduced vertical ground reaction force by 17-18%; however, improvements in jumping performance were not observed. This indicates that programs aimed at enhancing performance must be designed differently from those aimed at reducing landing forces in recreationally athletic women.Physical therapy in sport: official journal of the Association of Chartered Physiotherapists in Sports Medicine 12/2008; 9(4):185-92. · 0.67 Impact Factor -
Article: Finite element modeling following partial meniscectomy: effect of various size of resection.
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ABSTRACT: Meniscal tears are a common occurrence in the human knee joint. Orthopaedic surgeons routinely perform surgery to remove a portion of the torn meniscus. This surgery is referred to as a partial meniscectomy. It has been shown that individuals who have decreased amount of meniscus are likely to develop knee osteoarthritis. This research presents the analysis of the stresses in the knee joint upon various amounts of partial meniscectomy. To analyse the stresses in the knee joint using finite element method an axisymmetric model was developed. Articular cartilage was considered as three layers, which were modelled as a poroelastic transversely isotropic superficial layer, a poroelastic isotropic middle and deep layers and an elastic isotropic calcified cartilage layer. Eight cases were modelled including a knee joint with an intact meniscus, 10%, 20%, 30%, 40%, 50%, 60% and 65% medial meniscotomy. Under the axial load of human weight on the femoral articular cartilage with 40% removal of meniscus high contact stresses took place on cartilage surface. Further, with 30%, 40%, 50% of meniscectomy significant amount of contact area noticed between femoral and tibial articular cartilage. After 65% of meniscectomy the maximal shear stress in the cartilage increased up to 225% compared to knee with intact meniscus. It appears that meniscectomies greater than 20% drastically increases the stresses in the knee joint.Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2006; 1:2098-101. -
Article: Evaluation of power prediction equations: peak vertical jumping power in women.
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ABSTRACT: The purpose of this investigation was to: 1) compare actual peak power (PPactual) to estimated values (PPest) derived from three different prediction equations (Sayers and Harman), 2) determine the ability of the prediction formulas to monitor change following 6 wk of plyometric training, and 3) generate a new regression model. colon; Twenty college females (age = 20.1 +/- 1.6 yr; body mass = 65.9 +/- 8.9 kg) were randomly assigned to a control or intervention group. Pre- and posttest countermovement jump (CMJ) height and PPactual were determined simultaneously on a force platform. Body mass and maximal CMJ height were used to predict peak power. colon; All three PPest were significantly correlated 0.84-0.99) and post (r = 372.4 W) was significantly less to PPactual and to each other on pre (r = 0.88-0.99) tests. PPactual (2425.4 +/- 2920.8 +/- 482.6 W; CMJ = 2925.1 +/- 409.7 than PPest (Sayers: SJ = 473.0 W) but was not different from PPest (Harman: 2585.0 +/- 409.7 W). Posttests revealed similar differences between PPactual and PPest for the intervention group, however no significant differences were observed for the control group. Mean differences from pre and posttests did not differ within or between PPest. Regression analysis determined the formula: ppest = 65.1 x (jump height) + 25.8 x (body mass) - 1413.1 (R = 0.92; SEE = 120.8), which slightly determined (0.77%) peak power is compared with PPactual in our cross-validation sample (n = 7) colon; Changes in peak power is accurate using any of the regression equations; however, the new prediction formula and that of Harman seem to more precisely estimate peak power. Strict jumping technique along with simultaneous measurement of power and jump height should be used as the standard for comparison.Medicine & Science in Sports & Exercise 10/2004; 36(9):1589-93. · 4.43 Impact Factor -
Article: A kinematic and kinetic analysis of college aged female basketball players during landing following a jump training program
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ABSTRACT: Females incur a high rate of knee injuries, while playing the sport of basketball. Many females injure their anterior cruciate ligament, while landing from a jump. The three purposes of this study were: (1) to evaluate the kinetic and kinematic effects of two different arm positions, (Overhead and Anterior), while holding a basketball, during bilateral (BO, BA) and unilateral leg landing (UO, UA), from a.30 meter box; (2) to test the effect of a jump training program on landing characteristics and on lower extremity strength and vertical jump (3). Twenty female college aged recreational basketball players, (10 intervention, 10 control), participated in the study. A Qualisys four camera system, Biodex dynamometer, AMTI and Kistler force plates were used for analysis. Three way mixed procedure repeated measure ANOVA's (2 x 2 x 4) (group x time x condition), were used to determine the differences between the landing conditions and between the control and intervention groups for the landing test over time. Paired t-tests were used to analyze the vertical jump and lower extremity strength for the intervention group. Results . The UA landing condition produced longer time to peak moment z (Mz) positive (P = .010) and negative (P = .008), compared to BO. The intervention group demonstrated decreased peak landing force (Fz), following participation in the program (P < .0001) and a slower rate to peak Fz/body weight. There were no significant improvements in the vertical jump (p = .6044) and average power (p = .6778) in the post test for the intervention group. Right knee peak extension torque increased at 180 degrees/sec (p = .0033) for the intervention group. Conclusion . Single leg landing with arms held anterior may be less safe than landing with both legs with arms overhead. Participation in the jump training program resulted in increased in decreased landing forces, decreased rate to peak Fz, and improved right quadriceps strength.ETD Collection for University of Connecticut. -
Article: A kinematic and kinetic analysis of college aged female basketball players during landing following a jump training program /
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ABSTRACT: Abstract (2 leaves) bound with copy. Thesis (Ph. D.)--University of Connecticut, 2004. Includes bibliographical references.
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2004–2011
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Northeastern University
- • Department of Mechanical and Industrial Engineering
- • Department of Physical Therapy
Boston, MA, USA
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