Thijs Lutjeboer, Jaap J. van Netten, Klaas Postema, Juha M. Hijmans
University of Groningen, University Medical Center Groningen, Department of Rehabilitation Medicine, 9700 RB Groningen, The Netherlands. E-mail: t.lutjeboer@umcg.nl
DOI: 10.2340/16501977-2494

Objective: Adherence is a prerequisite for the effectiveness of orthopaedic footwear. The aim of this study is to assess the validity of a new temperature sensor for objective assessment of footwear use and non-use.
Design: Observational study.
Methods: The validity of a temperature sensor (Orthotimer, Balingen, Germany) to discriminate between time periods of use and non-use of footwear over a period of 48 h was assessed using 3 algorithms, in 10 healthy participants (mean age 32. 8 years (standard deviation (SD) 14. 1 years)). Footwear use measured with the sensor was compared with a reference standard, footwear use measured with a time-lapse sports camera secured to the shoe.
Main outcome measure: Hours of footwear use.
Results: Mean footwear use measured with the camera was 8. 10 (SD 2. 46) h per day. Mean footwear uses measured with the sensor and calculated with the 3 algorithms were 8. 16 (SD 2. 37), 8. 86 (SD 2. 48) and 4. 91 (SD 3. 17) h per day for the Groningen algorithm, algorithm-25, and algorithm-29, respectively. The correlation between footwear use assessed with the camera and with the sensor was: rGroningen = 0. 995, ralg25 = 0. 919 and ralg29 = 0. 680).
Conclusion: The temperature sensor is a valid instrument to measure footwear use and non-use when using the Groningen algorithm.

Orthopaedic footwear is frequently prescribed to patients with a wide variety of pathologies, such as diabetes mellitus, rheumatoid arthritis, degenerative foot disorders and muscle disorders. For these patients, orthopaedic footwear is used for a range of serious foot and/or ankle problems; for example, to prevent the onset or recurrence of foot ulcers, to reduce pain, to support anatomical foot deformities, enhance stability and mobility, and redistribute plantar pressure.
Orthopaedic footwear is only effective if they are used. To date, the use of orthopaedic footwear has mostly been assessed using questionnaires, interviews or diaries. However, these methods are not objective and lack accuracy. Temperature measurement can be used to determine the use of orthopaedic footwear. This study uses a new temperature sensor to objectively monitor use and non-use of orthopaedic footwear. Ten healthy participants were monitored over a period of 48 h using the sensor in their footwear. Footwear use based on the sensor data was compared with the reference standard, a camera attached to the footwear. The study found that the temperature sensor is a valid instrument to measure footwear use and non-use.