Novel In-Shoe Exoskeleton for Offloading of Forefoot Pressure for Individuals With Diabetic Foot Pathology.

INTRODUCTION: Infected diabetic foot ulcers are the leading cause of lower limb amputation. This study evaluated the ability of in-shoe exoskeletons to redirect forces outside of body and through an exoskeleton as an effective means of offloading plantar pressure, the major contributing factor of ulceration. METHODS: We compared pressure in the forefoot and hind-foot of participants (n = 5) shod with novel exoskeleton footwear. Plantar pressure readings were taken during a 6-m walk at participant's self-selected speed, and five strides were averaged. Results were taken with Achilles exotendon springs disengaged as a baseline, followed by measurements taken with the springs engaged. RESULTS: When springs were engaged, all participants demonstrated a decrease in forefoot pressure, averaging a 22% reduction ( P < .050). Patient feedback was universally positive, preferring the exotendon springs to be engaged and active. CONCLUSIONS: Offloading is standard of care for reducing harmful plantar pressure, which may lead to foot ulcers. However, current offloading modalities are limited and have issues. This proof-of-concept study proposed a novel offloading approach based on an exoskeleton solution. Results suggest that when the novel exoskeletons were deployed in footwear and exotendon springs engaged, force was successfully transferred from the lower leg through the exoskeleton-enabled shoe to ground, reducing load on the forefoot. The results need to be confirmed in a larger sample. Another study is warranted to examine the effectiveness of this offloading to prevent diabetic foot ulcer, while minimizing gait alteration in daily physical activities.

The effects of graft size and insertion site location during anterior cruciate ligament reconstruction on intercondylar notch impingement.

BACKGROUND: Intercondylar notch impingement is detrimental to the anterior cruciate ligament (ACL). Notchplasty is a preventative remodeling procedure performed on the intercondylar notch during ACL reconstruction (ACLR). This study investigates how ACL graft geometry and both tibial and femoral insertion site location may affect ACL-intercondylar notch interactions post ACLR. A range of ACL graft sizes are reported during ACLR, from six millimeters to 11mm in diameter. Variability of three millimeters in ACL insertion site location is reported during ACLR. This study aims to determine the post-operative effects of minor variations in graft size and insertion location on intercondylar notch impingement. METHODS: Several 3D finite element knee joint models were constructed using three ACL graft sizes and polar arrays of tibial and femoral insertion locations. Each model was subjected to flexion, tibial external rotation, and valgus motion. Impingement force and contact area between the ACL and intercondylar notch compared well with experimental cadaver data from literature. RESULTS: A three millimeter anterior-lateral tibial insertion site shift of the maximum size ACL increased impingement force by 242.9%. A three millimeter anterior-proximal femoral insertion site shift of the maximum size ACL increased impingement by 346.2%. Simulated notchplasty of five millimeters eliminated all impingement for the simulation with the greatest impingement. For the kinematics applied, small differences in graft size and insertion site location led to large increases in impingement force and contact area. CONCLUSIONS: Minor surgical variations may increase ACL impingement. The results indicate that notchplasty reduces impingement during ACLR. Notchplasty may help to improve ACLR success rates.

The effects of knee joint kinematics on anterior cruciate ligament injury and articular cartilage damage.

This study determined which knee joint motions lead to anterior cruciate ligament (ACL) rupture with the knee at 25° of flexion. The knee was subjected to internal and external rotations, as well as varus and valgus motions. A failure locus representing the relationship between these motions and ACL rupture was established using finite element simulations. This study also considered possible concomitant injuries to the tibial articular cartilage prior to ACL injury. The posterolateral bundle of the ACL demonstrated higher rupture susceptibility than the anteromedial bundle. The average varus angular displacement required for ACL failure was 46.6% lower compared to the average valgus angular displacement. Femoral external rotation decreased the frontal plane angle required for ACL failure by 27.5% compared to internal rotation. Tibial articular cartilage damage initiated prior to ACL failure in all valgus simulations. The results from this investigation agreed well with other experimental and analytical investigations. This study provides a greater understanding of the various knee joint motion combinations leading to ACL injury and articular cartilage damage.

Failure locus of the anterior cruciate ligament: 3D finite element analysis.

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.

Effect of frontal plane tibiofemoral angle on the stress and strain at the knee cartilage during the stance phase of gait.

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.

The effect of the frontal plane tibiofemoral angle and varus knee moment on the contact stress and strain at the knee cartilage.

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.

The combined effect of frontal plane tibiofemoral knee angle and meniscectomy on the cartilage contact stresses and strains.

Abnormal tibiofemoral alignment can create loading conditions at the knee that may lead to the initiation and progression of knee osteoarthritis (OA). The degenerative changes of the articular cartilage may occur earlier and with greater severity in individuals with abnormal frontal plane tibiofemoral alignment who undergo a partial or total meniscectomy. In this investigation, subject specific 3D finite element knee models were created from magnetic resonance images of two female subjects to study the combined effect of frontal plane tibiofemoral alignment and total and partial meniscectomy on the stress and strain at the knee cartilage. Different amounts of medial and lateral meniscectomies were modeled and subject specific loading conditions were determined from motion analysis and force platform data during single-leg support. The results showed that the maximum stresses and strains occurred on the medial tibial cartilage after medial meniscectomy but a greater percentage change in the contact stresses and strains occurred in the lateral cartilage after lateral meniscectomy for both subjects due to the resultant greater load bearing role of the lateral meniscus. The results indicate that individual's frontal plane knee alignment and their unique local force distribution between the cartilage and meniscus play an important role in the biomechanical effects of total and partial meniscectomy.

Managing gait disorders in older persons residing in nursing homes: a review of literature.

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.

Effects of a plyometric program on vertical landing force and jumping performance in college women.

OBJECTIVES: 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. DESIGN: Six week prospective exercise intervention. SETTING: Division I university campus. PARTICIPANTS: Twenty college females who competed recreationally in basketball were randomly assigned to a training (n=10) or control (n=10) group. MAIN OUTCOME MEASURES: 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. RESULTS: 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. CONCLUSIONS: 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.

Integrated physical therapy intervention for a person with pectus excavatum and bilateral shoulder pain: a single-case study.

OBJECTIVE: To examine the effects of an individualized physical therapy (PT) program for a subject with pectus excavatum and bilateral shoulder pain. DESIGN: 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. SETTING: University laboratory. PARTICIPANT: A 22-year-old man. INTERVENTION: A 3-month PT program including breathing exercises and therapeutic exercises. MAIN OUTCOME MEASURES: Exercise tolerance, ventilatory muscle strength, chest wall and abdominal excursion, self-perception of the pectus excavatum, and other anthropometric and volumetric tests. RESULTS: 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. CONCLUSION: 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.

Finite element modeling following partial meniscectomy: effect of various size of resection.

INTRODUCTION: 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. METHODS: 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. FINDINGS: 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.

Evaluation of power prediction equations: peak vertical jumping power in women.

PURPOSE: 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. METHODS: 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. RESULTS: 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) CONCLUSIONS: 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.