Kade L. Paterson

Concurrent validity of the Microsoft Kinect for assessment of spatiotemporal gait variables

Spatiotemporal characteristics of gait such as step time and length are often associated with overall physical function in clinical populations, but can be difficult, time consuming and obtrusive to measure. This study assessed the concurrent validity of overground walking spatiotemporal data recorded using a criterion reference - a marker-based three-dimensional motion analysis (3DMA) system - and a low-cost, markerless alternative, the automated skeleton tracking output from the Microsoft Kinect™ (Kinect). Twenty-one healthy adults performed normal walking trials while being monitored using both systems. The outcome measures of gait speed, step length and time, stride length and time and peak foot swing velocity were derived using supervised automated analysis. To assess the agreement between the Kinect and 3DMA devices, Bland-Altman 95% bias and limits of agreement, percentage error, relative agreement (Pearsons correlation coefficients: r) overall agreement (concordance correlation coefficients: rc) and landmark location linearity as a function of distance from the sensor were determined. Gait speed, step length and stride length from the two devices possessed excellent agreement (r and rc values >0.90). Foot swing velocity possessed excellent relative (r=0.93) but only modest overall (rc=0.54) agreement. Step time (r=0.82 and rc=0.23) and stride time (r=0.69 and rc=0.14) possessed excellent and modest relative agreement respectively but poor overall agreement. Landmark location linearity was excellent (R(2)=0.991). This widely available, low-cost and portable system could provide clinicians with significant advantages for assessing some spatiotemporal gait parameters. However, caution must be taken when choosing outcome variables as some commonly reported variables cannot be accurately measured.

Reliability of an inexpensive and portable dynamic weight bearing asymmetry assessment system incorporating dual Nintendo Wii Balance Boards

Weight bearing asymmetry (WBA) during dynamic tasks is prevalent in a variety of clinical populations. However, accurate measurement has previously been out of reach of the clinician due to the costly equipment and technical expertise required. The aim of this study was to assess the test-retest reliability of WBA data obtained using an inexpensive and simple to use dual force plate system incorporating unmodified Nintendo Wii Balance Boards (NWBB) and customized software. A secondary outcome measure, individual limb COP path velocity, which represents the postural sway under each limb was also examined. Twenty-three participants performed squats both with and without visual WBA feedback on two separate occasions. Weight-bearing asymmetry as a percentage of body mass and individual limb center of pressure (COP) path velocity were recorded during these trials, with intraclass correlation coefficient (ICC(2,1)) analysis performed to assess test-retest reliability. This system provided reliable values for both outcome measures when performed with and without real-time visual feedback of WBA (ICC(2,1) range=0.75-0.91). In conclusion, recording WBA and COP path velocity data using NWBB is reliable. Given that tens of millions of NWBB have been sold worldwide, and that reprogramming them for clinical purposes is within the reach of most software developers, similar systems may soon become commonplace in the clinical setting.

Stride dynamics, gait variability and prospective falls risk in active community dwelling older women

BACKGROUND Measures of walking instability such as stride dynamics and gait variability have been shown to identify future fallers in older adult populations with gait limitations or mobility disorders. This study investigated whether measures of walking instability can predict future fallers (over a prospective 12 month period) in a group of healthy and active older women. METHODS Ninety-seven healthy active women aged between 55 and 90 years walked for 7 min around a continuous walking circuit. Gait data recorded by a GAITRite(®) walkway and foot-mounted accelerometers were used to calculate measures of stride dynamics and gait variability. The participants physical function and balance were assessed. Fall incidence was monitored over the following 12 months. RESULTS Inter-limb differences (p≤0.04) in stride dynamics were found for fallers (one or more falls) aged over 70 years, and multiple fallers (two or more falls) aged over 55 years, but not in non-fallers or a combined group of single and non-fallers. No group differences were found in the measures of physical function, balance or gait, including variability. Additionally, no gait variable predicted falls. CONCLUSIONS Reduced coordination of inter-limb dynamics was found in active healthy older fallers and multiple fallers despite no difference in other measures of intrinsic falls risk. Evaluating inter-limb dynamics may be a clinically sensitive technique to detect early gait instability and falls risk in high functioning older adults, prior to change in other measures of physical function, balance and gait.

Reliability and validity of the Microsoft Kinect for evaluating static foot posture.

BackgroundThe evaluation of foot posture in a clinical setting is useful to screen for potential injury, however disagreement remains as to which method has the greatest clinical utility. An inexpensive and widely available imaging system, the Microsoft Kinect™, may possess the characteristics to objectively evaluate static foot posture in a clinical setting with high accuracy. The aim of this study was to assess the intra-rater reliability and validity of this system for assessing static foot posture.MethodsThree measures were used to assess static foot posture; traditional visual observation using the Foot Posture Index (FPI), a 3D motion analysis (3DMA) system and software designed to collect and analyse image and depth data from the Kinect. Spearman’s rho was used to assess intra-rater reliability and concurrent validity of the Kinect to evaluate foot posture, and a linear regression was used to examine the ability of the Kinect to predict total visual FPI score.ResultsThe Kinect demonstrated moderate to good intra-rater reliability for four FPI items of foot posture (ρ = 0.62 to 0.78) and moderate to good correlations with the 3DMA system for four items of foot posture (ρ = 0.51 to 0.85). In contrast, intra-rater reliability of visual FPI items was poor to moderate (ρ = 0.17 to 0.63), and correlations with the Kinect and 3DMA systems were poor (absolute ρ = 0.01 to 0.44). Kinect FPI items with moderate to good reliability predicted 61% of the variance in total visual FPI score.ConclusionsThe majority of the foot posture items derived using the Kinect were more reliable than the traditional visual assessment of FPI, and were valid when compared to a 3DMA system. Individual foot posture items recorded using the Kinect were also shown to predict a moderate degree of variance in the total visual FPI score. Combined, these results support the future potential of the Kinect to accurately evaluate static foot posture in a clinical setting.

Gait variability in younger and older adult women is altered by overground walking protocol

patients: results from the Swedish Trial in Old Patients with Hypertension-2. J Hypertens 2000; 18: 1671–5. 22. Rosen AB. Indications for and utilization of ACE inhibitors in older individuals with diabetes. Findings from the National Health and Nutrition Examination Survey 1999 to 2002. J Gen Intern Med 2006; 21: 315–9. 23. Alter DA, Stukel TA, Newman A. Proliferation of cardiac technology in Canada: a challenge to the sustainability of Medicare. Circulation 2006; 113: 380–7. 24. Gerber Y, Rihal CS, Sundt TM et al. Coronary revascularization in the community. A population-based study, 1990 to 2004. J Am Coll Cardiol 2007; 50: 1223–9. 25. Beckett NS, Peters R, Fletcher AE et al. Treatment of hypertension in patients 80 years of age or older. N Engl J Med 2008; 358: 1887–98. 26. Shepherd J, Blauw GJ, Murphy MB et al. Pravastatin in elderly individuals at risk of vascular disease (PROSPER): a randomised controlled trial. Lancet 2002; 360: 1623–30.

The Reliability of Spatiotemporal Gait Data for Young and Older Women During Continuous Overground Walking

OBJECTIVE To examine the reliability and systematic bias in spatiotemporal gait parameters recorded in healthy women during repeated single and continuous overground walking trials. DESIGN Test-retest. SETTING University laboratory. PARTICIPANTS Young (n=13) and older adult (n=14) women volunteers. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Spatiotemporal data were collected from an 8.1-m GAITRite mat during 10 trials of discrete single walks and 10 laps of a continuous circuit presented in random order over 2 separate test sessions. Paired t tests, intraclass correlation coefficients (ICCs), SE of measurement, and coefficients of variation (CV) were calculated. RESULTS The relative and absolute measures of reliability showed most spatiotemporal variables recorded during the single and continuous walking protocols were reliable. Step length, foot angle, and step and stance times were found to be the most reliable parameters, with ICCs ranging from 0.84 to 0.95, CVs from 2.06% to 4.02%, and SE of measurements of 1.59 to 2.04 cm for step length, 1.32 degrees to 1.71 degrees for foot angle, and 0.011 to 0.025 seconds for step and stance times. Reliability estimates were similar for the single and continuous trial conditions and between the young and older women. Although small mean differences in the gait parameters were found across the test sessions, many of these parameters showed systematic bias (P<or=.05). In the single trial condition, the majority (65%) of the gait parameters showed significant bias, whereas in the continuous condition only 19% of the parameters exhibited bias. For the young women, 54% of the parameters showed systematic bias (P<or=.05) in the single trial condition, whereas 77% of the parameters exhibited bias for the older women. In the continuous walking condition, 38% of the gait parameters showed systematic bias (P<or=.05) for the young women, whereas no systematic bias was found in the gait parameters of the older women. CONCLUSIONS This study shows that both the single and continuous walking protocols are reliable methods for the collection of gait data in young and older women. It also shows that a continuous overground walking protocol produces less bias in test-retest spatiotemporal gait data. Therefore, a continuous protocol may be a better method when attempting to monitor gait changes over time, especially for older women.

Improving Lower Limb Weight Distribution Asymmetry During the Squat Using Nintendo Wii Balance Boards and Real-Time Feedback

McGough, R, Paterson, K, Bradshaw, EJ, Bryant, AL, and Clark, RA. Improving lower limb weight distribution asymmetry during the squat using Nintendo WII balance boards and real-time feedback. J Strength Cond Res 26(1): 47–52, 2012—Weight-bearing asymmetry (WBA) may be detrimental to performance and could increase the risk of injury; however, detecting and reducing it is difficult in a field setting. This study assessed whether a portable and simple-to-use system designed with multiple Nintendo Wii Balance Boards (NWBBs) and customized software can be used to evaluate and improve WBA. Fifteen elite Australian Rules Footballers and 32 age-matched, untrained participants were tested for measures of WBA while squatting. The NWBB and customized software provided real-time visual feedback of WBA during half of the trials. Outcome measures included the mean mass difference (MMD) between limbs, interlimb symmetry index (SI), and percentage of time spent favoring a single limb (TFSL). Significant reductions in MMD (p = 0.028) and SI (p = 0.007) with visual feedback were observed for the entire group data. Subgroup analysis revealed significant reductions in MMD (p = 0.047) and SI (p = 0.026) with visual feedback in the untrained sample; however, the reductions in the trained sample were nonsignificant. The trained group showed significantly less WBA for TFSL under both visual conditions (no feedback: p = 0.015, feedback: p = 0.017). Correlation analysis revealed that participants with high levels of WBA had the greatest response to feedback (p < 0.001, ρ = 0.557). In conclusion, WBA exists in healthy untrained adults, and these asymmetries can be reduced using real-time visual feedback provided by an NWBB-based system. Healthy, well-trained professional athletes do not possess the same magnitude of WBA. Inexpensive, portable, and widely available gaming technology may be used to evaluate and improve WBA in clinical and sporting settings.

The effects of enhanced plantar sensory feedback and foot orthoses on midfoot kinematics and lower leg neuromuscular activation

Excessive foot pronation has been associated with injuries of the lower extremity. No research has investigated the effect of enhancing plantar sensory feedback on foot pronation. The aim of this study was to determine whether a shoe with enhanced plantar sensory feedback reduces midfoot pronation. Midfoot kinematics and electromyography of the peroneus longus, tibialis anterior and medial gastrocnemius of 21 males (age: 21.0±4.0 years, height: 176.8±5.0 cm, mass: 73.3±6.5 kg) were recorded whilst walking in a neutral shoe, a neutral shoe with a prefabricated foot orthotic and a neutral shoe with nodules located on the plantar-medial insole (experimental shoe). Friedmans ANOVA and Wilcoxon tests were used to evaluate differences between shoe conditions. Mean midfoot-tibia angles during ground contact were significantly more supinated when wearing the experimental shoe (+7.14°, p=0.023) or orthotic (+3.83°, p=0.006) compared to the neutral shoe. During the loading phase, midfoot angles were significantly more supinated when wearing the experimental shoe compared to the orthotic (+5.53°, p=0.008) or neutral shoe (+6.20°, p=0.008). In the midstance phase, midfoot supination was significantly higher in the orthotic compared to the neutral shoe (+2.79°, p=0.006). Finally, supination was increased during the propulsive phase when wearing the experimental shoe compared to the orthotic (+7.43°, p=0.010) or neutral shoe (+10.83°, p=0.009). No significant (p<0.05) differences in muscle activation were observed. These results suggest that increasing plantar sensory feedback to the medial aspect of the foot reduces midfoot pronation during an acute bout of walking. Further work is needed to explore whether these effects remain over longer time periods.

Quantifying Individual Components of the Timed Up and Go Using the Kinect in People Living With Stroke

Background. The Microsoft Kinect presents a simple, inexpensive, and portable method of examining the independent components of the Timed Up and Go (TUG) without any intrusion on the patient. Objective. This study examined the reliability of these measures, and whether they improved prediction of performance on common clinical tests. Methods. Thirty individuals with stroke completed 4 clinical assessments, including the TUG, 10-m walk test (10MWT), Step Test, and Functional Reach test on 2 testing occasions. The TUG was assessed using the Kinect to determine 7 different functional components. Test–retest reliability was assessed using intraclass correlation coefficient (ICC), redundancy using Spearman’s correlation, and score prediction on the clinical tests using multiple regression. Results. All Kinect-TUG variables possessed excellent reliability (ICC(2,k) > 0.90) except trunk flexion angle (ICC = 0.73). Trunk flexion angle and first step length were nonredundant with total TUG time. When predicting 10MWT and Step Test scores, adding step length into regression models comprising age and total TUG time improved model performance by 7% (P <.01) and 6% (P =.03), respectively. Specifically, an interquartile range increase in first step length (0.19 m) was associated with a 0.15 m/s faster gait speed and 1.8 more repetitions on the Step Test. These effect sizes were comparable to our minimal detectable change scores of 0.17 m/s for gait speed and 1.71 repetitions for the Step Test. Conclusions. Using the Kinect to independently assess the multiple components of the TUG may provide reliable and clinically useful information. This could enable efficient and information-rich large-scale assessments of physical deficits following stroke.

Intra-articular injection of photo-activated platelet-rich plasma in patients with knee osteoarthritis: a double-blind, randomized controlled pilot study

BackgroundImprovements in knee osteoarthritis (OA) symptoms with platelet-rich plasma (PRP) have been attributed to its ability to modify intra-articular inflammatory processes. Photo-activation of peripheral blood also improves inflammatory mediators associated with OA, however combined photo-activated PRP (PA-PRP) has not been investigated. This pilot study assessed the feasibility, safety and symptomatic and functional change following injections of PA-PRP compared to hyaluronic acid (HA) in people with knee osteoarthritis (OA).MethodsThirty seven people with knee OA were enrolled in this double-blind randomized controlled pilot study set in a sports medicine clinic. Participants were randomly allocated to receive three injections of either PA-PRP or HA. The patients and the administering doctor were blinded to group allocation. Outcomes included recruitment and safety data, 100 mm visual analogue pain score (VAS), the Knee Osteoarthritis Outcome Score (KOOS), Knee Quality of Life (KQoL) scale, maximum hopping distance and number of knee bends in 30 s at four and 12 weeks.ResultsTwenty three (62 %) participants met the inclusion criteria, of which 12 (32 %) were randomized to the PA-PRP group and 11 (30 %) to the HA group. Two participants did not complete the intervention and two withdrew following their first assessment. Minor pain and swelling during the injection period was reported by two participants from the PA-PRP group. The PA-PRP group demonstrated significant improvements in the VAS (p < 0.01, ETA = 0.686), KOOS Pain (p < 0.05, ETA = 0.624), KQoL Physical (p < 0.05, ETA = 0.706) and KQoL Emotional subscales (p < 0.05, ETA = 0.715) at four and 12 weeks. The PA-PRP group also significantly improved hoping (p < 0.05, ETA = 0.799) and knee bends (p < 0.01, ETA = 0.756) at four or 12 weeks. The HA group showed improvements on only the KOOS Function subscale at 12 weeks (p < 0.01, ETA = 0.602). After controlling for baseline values, there were no significant between-group differences at either time-point.ConclusionsThis study provides proof-of-concept evidence concerning the feasibility and safety of PA-PRP injections necessary to inform a larger clinical trial in people with knee OA. Our preliminary results also suggest PA-PRP improves self-reported pain, symptoms and lower extremity function, however no between-group differences were found. Photo-activated PRP may provide a safe and effective novel treatment for knee OA.Trial registrationACTRN12611000651987