Accuracy and repeatability of smartphone sensors for measuring shank-to-vertical angle

Reliability and Validity of a Smartphone Device and Clinical Tools for Thoracic Spine Mobility Assessments

Quantifying thoracic spine mobility with reliable and valid tools is a challenge for clinicians in practice. The aim of this study is to determine the reliability and validity of a smartphone device, bubble inclinometer and universal goniometer to quantify the static kyphotic curve and active range of motion of the thoracic spine. A total of 17 participants (mean age = 23.7 ± 2.3 years) underwent repeated measurements with three raters, on three separate days performing the lumbar-locked trunk rotation, standing full extension, standing full flexion, standing relaxed curve and seated trunk rotation assessments. Mostly "Good" to "Excellent" intra-rater (ICC ranging from 0.624 to 0.981) and inter-reliability (ICC ranging from 0.671 to 0.968) was achieved with the smartphone and clinical tools. "Excellent" validity (ICC ranging from 0.903 to 0.947) with the smartphone was achieved during lumbar-locked trunk rotation and standing relaxed curve assessment. "Good" validity (ICC ranging from 0.836 to 0.867) of the smartphone was achieved during the seated trunk rotation. The Samsung s9+ smartphone with the iSetSquare mobile application is a reliable and valid tool to use for clinical assessments assessing thoracic spine mobility.

Quantifying alignment bias during the fabrication and fitting of ankle-foot orthoses: A single center study

BACKGROUND

The sagittal plane alignment of ankle-foot orthoses (AFO) and AFO footwear combinations (AFO-FC) has been shown to influence gait outcomes. As such, clinicians often target a particular alignment during the fabricating and fitting of an AFO to maximize outcomes.

RESEARCH QUESTION

How does the alignment of an AFO change during the fabrication and fitting process with respect to the intended, benchmark sagittal plane alignment identified by the consulting orthotist?

STUDY DESIGN

Prospective METHODS: The assessment of AFO alignment was performed using a convenience sample of 125 custom molded AFOs from 68 individuals fabricated at our center (57 bilateral AFOs, 11 unilateral AFOs). The alignment of each AFO was measured at 5 distinct steps during the fabrication and fitting process using a recently validated method to measure AFO neutral angle using differential inclinometers.

RESULTS

Prior to fabrication, the intended, benchmark alignment set by the consulting orthotist was 90 degrees for 92% of AFOs, was between 1 and 7 degrees of dorsiflexion for 7% of AFOs and was 5 degrees of plantarflexion for 1% of AFOs. Repeated measures ANOVA showed that AFO alignment changed between all fabrication and fitting steps. Overall, paired t-tests confirmed that AFO alignment was consistently 2-5 degrees more dorsiflexed than the benchmark alignment. Prior to fitting shoes, 55% of fabricated AFOs measured more than 2 degrees from the benchmark alignment. After fitting shoes, nearly 87% of AFO-FCs were more than 2 degrees from the benchmark alignment.

SIGNIFICANCE

The finding of systematic dorsiflexion bias and changes in AFO alignment throughout the fabrication and fitting process indicates the need to improve AFO fabrication precision. The neutral angle measurement methodology - using differential inclinometers - provides a means to improve this precision by enabling orthotists to precisely quantify and make appropriate adjustments to AFO alignment throughout the entire fabrication and fitting process.

Smartphone Inclinometry Is a Valid and Reliable Tool for Measuring Frontal Plane Tibial Alignment in Healthy and Osteoarthritic Knees

OBJECTIVE

Frontal plane knee alignment plays an integral role in tibiofemoral knee osteoarthritis development and progression. Accessible methods for obtaining direct or indirect measures of knee alignment may help inform clinical decision making when specialized equipment is unavailable. The present study evaluated the concurrent validity, as well as intersession (within-rater) and interrater (within-session) reliability of smartphone inclinometry for measuring static frontal plane tibial alignment-a known proxy of frontal plane knee alignment.

METHODS

Twenty healthy individuals and 38 patients with knee osteoarthritis were measured for frontal plane tibial alignment by a pair of raters using smartphone inclinometry, manual inclinometry, and 3-dimensional motion capture simultaneously. Healthy participants were measured on 2 separate days. Bland-Altman analysis, supplemented with intraclass correlation coefficient (ICC)(2,k), was used to assess concurrent validity. ICC(2,k), SEM, and minimum detectable change with 95% confidence limits (MDC95) were used to assess measurement reliability.

RESULTS

Compared against motion capture, smartphone inclinometry measured frontal plane tibial alignment with a mean difference of 0.7 and 1.1 degrees (biased toward varus) for healthy participants and participants with knee osteoarthritis, respectively (ICC[2,k] ≥ 0.87). Smartphone inclinometry measurements demonstrated adequate intersession (within-rater) relative (ICC[2,k] = 0.91) and absolute (SEM = 0.7 degrees; MDC95 = 1.8 degrees) reliability, which outperformed manual inclinometry (ICC[2,k] = 0.85; SEM = 1.0 degrees; MDC95 = 2.6 degrees). Interrater (within-session) reliability of smartphone inclinometry was acceptable in both cohorts (ICC[2,k] = 0.93; SEM = 0.4 degrees to 1.2 degrees; MDC95 = 1.2 degrees to 3.2 degrees).

CONCLUSION

Smartphone inclinometry is sufficiently valid and reliable for measuring frontal plane tibial alignment in healthy individuals and patients with medial tibiofemoral knee osteoarthritis.

IMPACT

Smartphones are readily accessible by clinicians and researchers. Our assessment of measurement validity and reliability supports the use of smartphone inclinometry as a clinically available tool to measure frontal plane tibial alignment without medical imaging or specialized equipment.

Assessment of the Shank-to-Vertical Angle While Changing Heel Heights Using a Single Inertial Measurement Unit in Individuals with Incomplete Spinal Cord Injury Wearing an Ankle-Foot-Orthosis

Previous research showed that an Inertial Measurement Unit (IMU) on the anterior side of the shank can accurately measure the Shank-to-Vertical Angle (SVA), which is a clinically-used parameter to guide tuning of ankle-foot orthoses (AFOs). However, in this context it is specifically important that differences in the SVA are detected during the tuning process, i.e., when adjusting heel height. This study investigated the validity of the SVA as measured by an IMU and its responsiveness to changes in AFO-footwear combination (AFO-FC) heel height in persons with incomplete spinal cord injury (iSCI). Additionally, the effect of heel height on knee flexion-extension angle and internal moment was evaluated. Twelve persons with an iSCI walked with their own AFO-FC in three different conditions: (1) without a heel wedge (refHH), (2) with 5 mm heel wedge (lowHH) and (3) with 10 mm heel wedge (highHH). Walking was recorded by a single IMU on the anterior side of the shank and a 3D gait analysis (3DGA) simultaneously. To estimate validity, a paired t-test and intraclass correlation coefficient (ICC) between the SVA_IMU and SVA_3DGA were calculated for the refHH. A repeated measures ANOVA was performed to evaluate the differences between the heel heights. A good validity with a mean difference smaller than 1 and an ICC above 0.9 was found for the SVA during midstance phase and at midstance. Significant differences between the heel heights were found for changes in SVA_IMU (p = 0.036) and knee moment (p = 0.020) during the midstance phase and in SVA_IMU (p = 0.042) and SVA_3DGA (p = 0.006) at midstance. Post-hoc analysis revealed a significant difference between the ref and high heel height condition for the SVA_IMU (p = 0.005) and knee moment (p = 0.006) during the midstance phase and for the SVA_IMU (p = 0.010) and SVA_3DGA (p = 0.006) at the instant of midstance. The SVA measured with an IMU is valid and responsive to changing heel heights and equivalent to the gold standard 3DGA. The knee joint angle and knee joint moment showed concomitant changes compared to SVA as a result of changing heel height.