World J Surg Surg Res | Volume 2, Issue 1 | Research Article | Open Access

SOLEFORCE®: A Novel Biofeedback Device that Improves Patient Compliance with Lower Extremity Partial Weight-Bearing

David T Zhang*, David C Goral, Austin T Fragomen and S Robert Rozbruch

Department of Orthopedic Surgery, Limb Lengthening and Complex Reconstruction Service, Hospital for Special Surgery, USA

*Correspondance to: David T Zhang 

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Background: Previous studies have demonstrated that orthopedic patients’ ability to accurately
reproduce partial weight bearing is poor. When told to perform partial weight bearing, patients
tend to significantly underestimate how much weight they are putting on their leg. We developed a
customized thin film sensory insole Soleforce® (stylized “SOLEFORCE®”, RGD Technologies LLC),
which is placed inside the footwear of a patient to register forces transmitted through a lower limb
to provide continuous biofeedback for actual weight bearing with each step. We hypothesize that
patient compliance with weight-bearing restrictions improves with the use of mobile continuous
force plate measurement.
Material and Methods: We prospectively evaluated 21 patients who had partial weight bearing
restrictions after orthopedic surgery (absolute restrictions, in lb). Patients served as their own
control: with and without Soleforce® feedback. We calculated a precision value for patients before
and after Soleforce® feedback. We used a paired Student’s t-test to compare the patients’ precision
values. We also used descriptive statistics to summarize patient improvement with biofeedback.
Results: The average precision value for the patients improved from 1.31 (range 0.23-2.00) before
Soleforce® feedback to 1.09 (0.84-1.70) after feedback. This was statistically significant (P=0.037).
With biofeedback, the proportion of patients who were within 25% of their allowed weight range
improved from 9.5% to 90.5%. The proportion of steps which were within 25% of the allowed weight
range improved from 18.7% to 71.9%.
Conclusion: Biofeedback using the Soleforce® leads to improved precision for adhering to weightbearing
restrictions. This should improve safety by empowering the patient to be more compliant
with the physician’s weight-bearing prescription.


Partial weight bearing; Biofeedback; Physical therapy


Zhang DT, Goral DC, Fragomen AT, Rozbruch SR. SOLEFORCE®: A Novel Biofeedback Device that Improves Patient Compliance with Lower Extremity Partial Weight-Bearing. World J Surg Surgical Res. 2019; 2:1181..

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