John B. Arnold

Differences in foot kinematics between young and older adults during walking

Our understanding of age-related changes to foot function during walking has mainly been based on plantar pressure measurements, with little information on differences in foot kinematics between young and older adults. The purpose of this study was to investigate the differences in foot kinematics between young and older adults during walking using a multi-segment foot model. Joint kinematics of the foot and ankle for 20 young (mean age 23.2 years, standard deviation (SD) 3.0) and 20 older adults (mean age 73.2 years, SD 5.1) were quantified during walking with a 12 camera Vicon motion analysis system using a five segment kinematic model. Differences in kinematics were compared between older adults and young adults (preferred and slow walking speeds) using Students t-tests or if indicated, Mann-Whitney U tests. Effect sizes (Cohens d) for the differences were also computed. The older adults had a less plantarflexed calcaneus at toe-off (-9.6° vs. -16.1°, d = 1.0, p = <0.001), a smaller sagittal plane range of motion (ROM) of the midfoot (11.9° vs. 14.8°, d = 1.3, p = <0.001) and smaller coronal plane ROM of the metatarsus (3.2° vs. 4.3°, d = 1.1, p = 0.006) compared to the young adults. Walking speed did not influence these differences, as they remained present when groups walked at comparable speeds. The findings of this study indicate that independent of walking speed, older adults exhibit significant differences in foot kinematics compared to younger adults, characterised by less propulsion and reduced mobility of multiple foot segments.

Does Physical Activity Increase After Total Hip or Knee Arthroplasty for Osteoarthritis? A Systematic Review

Study Design Systematic review. Background Despite improvements in self-reported symptoms and perceived functional ability after total hip arthroplasty (THA) and total knee arthroplasty (TKA), it is unclear whether changes in objectively measured physical activity (PA) occur after surgery. Objective To determine if objectively measured PA increases after THA and TKA in adults with osteoarthritis. Methods Five electronic databases were searched from inception to March 3, 2015. All study designs objectively measuring PA before and after THA or TKA were eligible, including randomized controlled trials, cohort studies, and case-control studies. Two reviewers independently screened abstracts and full texts and extracted study demographic, PA, and clinical outcome data. Standardized mean differences (SMDs) and 95% confidence intervals were calculated for accelerometer- and pedometer-derived estimates of PA. Risk of methodological bias was assessed with Critical Appraisal Skills Programme checklists. Results Eight studies with a total of 373 participants (238 TKA, 135 THA) were included. Findings were mixed regarding improvement in objectively measured PA at 6 months after THA (SMDs, -0.20 to 1.80) and TKA (SMDs, -0.36 to 0.63). Larger improvements from 2 studies at 1 year postsurgery were generally observed after THA (SMDs, 0.39 to 0.79) and TKA (SMDs, 0.10 to 0.85). However, at 1 year, PA levels were still considerably lower than those of healthy controls (THA SMDs, -0.25 to -0.77; TKA SMDs, -1.46 to -1.80). Risk-of-bias scores ranged from 3 to 9 out of 11 (27%-82%) for cohort studies, and from 3 to 8 out of 10 (30%-80%) for case-control studies. Conclusion The best available evidence indicates negligible changes in PA at 6 months after THA or TKA, with limited evidence for larger changes at 1 year after surgery. In the 4 studies that reported control-group data, postoperative PA levels were still considerably less than those of healthy controls. Improved perioperative strategies to instill behavioral change are required to narrow the gap between patient-perceived functional improvement and the actual amount of PA undertaken after THA and TKA. Registered with PROSPERO (registration number CRD42014010155). Level of Evidence Therapy, level 2a. J Orthop Sports Phys Ther 2016;46(6):431-442. Epub 26 Apr 2016. doi:10.2519/jospt.2016.6449.

Quantifying foot kinematics inside athletic footwear: a review

Movement of the foot and ankle are essential for human locomotion. Recent in vivo research using invasive techniques has highlighted the complexity of joint kinematics of the foot and ankle. Consequently, a detailed quantification of foot bone motion is often required. This presents challenges if non-invasive methods are used; even more so if footwear is incorporated into these investigations. A description of foot movement within footwear (in-shoe foot kinematics) is particularly valuable due to the plethora of potential applications in foot and ankle biomechanics. The objective of this review is to appraise existing literature and describe methods for quantifying foot kinematics inside athletic running type footwear and to provide a perspective on future directions for research. A number of methods were identified that have been implemented in an attempt to quantify in-shoe foot kinematics. Although varied, these all present threats to the validity of measurement in the form of either structural modification of footwear or surface marker application to the external shoe surface. Due to discrepancies in foot kinematics measured with markers applied on the external shoe surface compared to skin or bone mounted markers, it appears inappropriate to rely on external shoe markers to infer in-shoe foot motion. The impact of footwear modification on shoe structure and foot kinematics to gain access to anatomical landmarks of the foot requires further investigation. The recognition of the limitations imposed by these methods and the emergence of new non-invasive methods that allow for investigation during shod activity will facilitate more realistic representation and accurate investigation of foot motion inside the shoe.

The impact of increasing body mass on peak and mean plantar pressure in asymptomatic adult subjects during walking

Introduction : The implication of high peak plantar pressure on foot pathology in individuals both with and without diabetes has been recognized. The aim of this study was to investigate and clarify the relationship between increasing body mass and peak and mean plantar pressure in an asymptomatic adult population during walking. Methods : Thirty adults without any relevant medical history, structural foot deformities or foot posture assessed as highly pronated or supinated, and within a normal body mass index range were included in the study. An experimental, same subjects, repeated measures design was used. Peak and mean plantar pressure were evaluated with the F-Scan in-shoe plantar pressure measurement system under four different loading conditions (0, 5, 10, and 15 kg) simulated with a weighted vest. Pressure data were gathered from three stances utilizing the mid-gait protocol. Results : There were statistically significant increases in peak pressure between the 10 and 15 kg load conditions compared to the control (0 kg) within the heel and second to fifth metatarsal regions. The first metatarsal and hallux regions only displayed statistically significant increases in peak pressure between 15 kg and the control (0 kg). The midfoot and lesser digits regions did not display any statistically significant differences in peak pressure between any load conditions compared to the control (0 kg). The second to fifth metatarsal region displayed statistically significant increases in mean pressure in the 5, 10 and 15 kg groups compared to the control (0 kg). A statistically significant increase in peak pressure between the 15 kg and control (0 kg) group was evident in all other regions. Conclusion : The relationship between increasing body mass and peak and mean plantar pressure was dependent upon the plantar region. This study provides more detail outlining the response of peak and mean pressure to different loading conditions than previously reported in the literature. Further research including measurement of temporal parameters is warranted.

Lateral Wedge Insoles for Reducing Biomechanical Risk Factors for Medial Knee Osteoarthritis Progression: A Systematic Review and Meta‐Analysis

Lateral wedge insoles are intended to reduce biomechanical risk factors of medial knee osteoarthritis (OA) progression, such as increased knee joint load; however, there has been no definitive consensus on this topic. The aim of this systematic review and meta‐analysis was to establish the within‐subject effects of lateral wedge insoles on knee joint load in people with medial knee OA during walking.

Repeatability of stance phase kinematics from a multi-segment foot model in people aged 50 years and older

Confidence in 3D multi-segment foot models has been limited by a lack of repeatability data, particularly in older populations that may display unique functional foot characteristics. This study aimed to determine the intra and inter-observer repeatability of stance phase kinematic data from a multi-segment foot model described by Leardini et al. [2] in people aged 50 years or older. Twenty healthy adults participated (mean age 65.4 years SD 8.4). A repeated measures study design was used with data collected from four testing sessions on two days from two observers. Intra (within-day and between-day) and inter-observer coefficient of multiple correlations revealed moderate to excellent similarity of stance phase joint range of motion (0.621-0.975). Relative to the joint range of motion (ROM), mean differences (MD) between sessions were highest for the within-day comparison for all planar ROM at the metatarsus-midfoot articulation (sagittal plane ROM 5.2° vs. 3.9°, MD 3.1°; coronal plane ROM 3.9 vs. 3.1°, MD 2.3°; transverse plane ROM 6.8° vs. 5.16°, MD 3.5°). Consequently, data from the metatarsus-midfoot articulation in the Istituto Ortopedico Rizzoli (IOR) foot model in adults aged over 50 years needs to be considered with respect to the findings of this study.

A method to investigate the effect of shoe-hole size on surface marker movement when describing in-shoe joint kinematics using a multi-segment foot model

To investigate in-shoe foot kinematics, holes are often cut in the shoe upper to allow markers to be placed on the skin surface. However, there is currently a lack of understanding as to what is an appropriate size. This study aimed to demonstrate a method to assess whether different diameter holes were large enough to allow free motion of marker wands mounted on the skin surface during walking using a multi-segment foot model. Eighteen participants underwent an analysis of foot kinematics whilst walking barefoot and wearing shoes with different size holes (15 mm, 20mm and 25 mm). The analysis was conducted in two parts; firstly the trajectory of the individual skin-mounted markers were analysed in a 2D ellipse to investigate total displacement of each marker during stance. Secondly, a geometrical analysis was conducted to assess cluster deformation of the hindfoot and midfoot-forefoot segments. Where movement of the markers in the 15 and 20mm conditions were restricted, the marker movement in the 25 mm condition did not exceed the radius at any anatomical location. Despite significant differences in the isotropy index of the medial and lateral calcaneus markers between the 25 mm and barefoot conditions, the differences were due to the effect of footwear on the foot and not a result of the marker wands hitting the shoe upper. In conclusion, the method proposed and results can be used to increase confidence in the representativeness of joint kinematics with respect to in-shoe multi-segment foot motion during walking.

Effects of Taping and Orthoses on Foot Biomechanics in Adults with Flat-Arched Feet.

PURPOSE There is a paucity of evidence on the biomechanical effects of foot taping and foot orthoses in realistic conditions. This study aimed to determine the immediate effect and relationships between changes in multisegment foot biomechanics with foot taping and customized foot orthoses in adults with flat-arched feet. METHODS Multisegment foot biomechanics were measured in 18 adults with flat-arched feet (age 25.1 ± 2.8 yr; height 1.73 ± .13 m, body mass 70.3 ± 15.7 kg) during walking in four conditions in random order: neutral athletic shoe, neutral shoe with tape (low-Dye method and modified method) and neutral shoe with customized foot orthoses. In-shoe foot biomechanics were compared between conditions using a purpose developed foot model with three-dimensional kinematic analysis and inverse dynamics. RESULTS Foot orthoses significantly delayed peak eversion compared to the neutral shoe (44% stance vs 39%, P = 0.002). Deformation across the midfoot and medial longitudinal arch was reduced with both the low-Dye taping (2.4°, P < 0.001) and modified taping technique (5.5°, P < 0.001). All interventions increased peak dorsiflexion of the first metatarsophalangeal joint (1.4°-3.2°, P < 0.001-0.023). Biomechanical responses to taping significantly predicted corresponding changes to foot orthoses (R2 = 0.08-0.52, P = 0.006 to <0.001). CONCLUSIONS Foot orthoses more effectively altered timing of hindfoot motion whereas taping was superior in supporting the midfoot and medial longitudinal arch. The biomechanical response to taping was significantly related to the subsequent change observed with the use of foot orthoses.

Does the Method of Component Fixation Influence Clinical Outcomes After Total Knee Replacement? A Systematic Literature Review

A systematic literature review was conducted to identify the best available evidence describing the differences in clinical outcome associated with the different methods of total knee replacement (TKR) fixation. Randomized trials published between 1980 and January 2011 comparing differences in clinical outcome scores between groups allocated to either cemented or uncemented fixation for TKR were included. Nine of the 11 studies included in the review reported no significant differences in clinical outcomes between groups with either cemented or uncemented prosthesis components. Critical appraisal of methodological bias revealed consistent shortcomings in study design and execution. It is apparent that more rigorous studies with longer follow-up periods are required to verify which method of fixation may be preferable in enhancing clinical outcomes.

Improvements in knee biomechanics during walking are associated with increased physical activity after total knee arthroplasty

Total knee arthroplasty (TKA) in people with knee osteoarthritis increases knee‐specific and general physical function, but it has not been established if there is a relationship between changes in these elements of functional ability. This study investigated changes and relationships between knee biomechanics during walking, physical activity, and use of time after TKA. Fifteen people awaiting TKA underwent 3D gait analysis before and six months after surgery. Physical activity and use of time were determined in free‐living conditions from a high resolution 24‐h activity recall. After surgery, participants displayed significant improvements in sagittal plane knee biomechanics and improved their physical activity profiles, standing for 105 more minutes (p = 0.001) and performing 64 min more inside chores on average per day (p = 0.008). Changes in sagittal plane knee range of motion (ROM) and peak knee flexion positively correlated with changes in total daily energy expenditure, time spent undertaking moderate to vigorous physical activity, inside chores and passive transport (r = 0.52–0.66, p = 0.005–0.047). Restoration of knee function occurs in parallel and is associated with improvements in physical activity and use of time after TKA. Increased functional knee ROM is required to support improvements in total and context specific physical activity.