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Comparative Study
. 2017 Mar;24(2):224-230.
doi: 10.1016/j.knee.2016.11.014. Epub 2017 Feb 5.

Smartphone assessment of knee flexion compared to radiographic standards

Matthew J Dietz  1 , Daniel Sprando  2 , Andrew E Hanselman  3 , Michael D Regier  4 , Benjamin M Frye  3
Affiliations
Comparative Study

Smartphone assessment of knee flexion compared to radiographic standards

Matthew J Dietz et al. Knee. 2017 Mar.

Abstract

Background: Measuring knee range of motion (ROM) is an important assessment for the outcomes of total knee arthroplasty. Recent technological advances have led to the development and use of accelerometer-based smartphone applications to measure knee ROM. The purpose of this study was to develop, standardize, and validate methods of utilizing smartphone accelerometer technology compared to radiographic standards, visual estimation, and goniometric evaluation.

Methods: Participants used visual estimation, a long-arm goniometer, and a smartphone accelerometer to determine range of motion of a cadaveric lower extremity; these results were compared to radiographs taken at the same angles.

Results: The optimal smartphone position was determined to be on top of the leg at the distal femur and proximal tibia location. Between methods, it was found that the smartphone and goniometer were comparably reliable in measuring knee flexion (ICC=0.94; 95% CI: 0.91-0.96). Visual estimation was found to be the least reliable method of measurement.

Conclusions: The results suggested that the smartphone accelerometer was non-inferior when compared to the other measurement techniques, demonstrated similar deviations from radiographic standards, and did not appear to be influenced by the person performing the measurements or the girth of the extremity.

Keywords: Accelerometer; Measurement; Motion; Smartphone.

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Figures

Figure 1
Figure 1
a) Custom device allowing for articulation of the hip around a fixed axis and positioning of the foot to create various flexion angles. b) This device allowed for observation of the leg with an unobstructed view. The femur and tibia were divided into thirds (proximal femur – PF, middle femur - MF, distal femur – DF) and (proximal tibia – PT, middle tibia – MT, distal tibia – DT). The smartphone was either placed on the anterior leg (blue rectangle) or on the side of the leg (yellow rectangle).
Figure 1
Figure 1
a) Custom device allowing for articulation of the hip around a fixed axis and positioning of the foot to create various flexion angles. b) This device allowed for observation of the leg with an unobstructed view. The femur and tibia were divided into thirds (proximal femur – PF, middle femur - MF, distal femur – DF) and (proximal tibia – PT, middle tibia – MT, distal tibia – DT). The smartphone was either placed on the anterior leg (blue rectangle) or on the side of the leg (yellow rectangle).
See this image and copyright information in PMC

References

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