• Introduction
  • Study preparation
  • Remotely monitoring the home exercises plan using re.flex
  • 67% total compliance to treatment
  • Using re.flex the patient had a 55% cost reduction and saved 169 hours spent in traffic
  • Conclusions

Remote physical therapy using motion tracking sensors is a promising way of increasing adherence, improving outcomes and reducing the costs of treatment for patients with knee osteoarthritis (minor, mild or medium stage), following a home exercise program (HEP).
There is strong evidence showing that patients who adhere to their prescribed exercises are significantly better at achieving their goals and demonstrate a greater increase in physical function [1][2]

The patient selected for the case study is a 41 years old male who was diagnosed with knee osteoarthritis on both of his knees and was prescribed with physical therapy, in order to postpone the surgery.
He was part of a larger group of 10 patients with gonarthrosis enrolled in a 24-week digital plan, using a novel remote patient monitoring system called re.flex, in order to postpone their surgery.
During the initial consultation, he stated that had previous experience with physical therapy in the clinical setting and recorded a low level of adherence, the patient agreed to test the re.flex sensors and train at home under the remote guidance of a physiotherapist available in the system.
His rehabilitation plan was designed by his orthopedic doctor and was comprised of active and isometric exercises.

We have observed that the Oxford Knee Scores improved from 25 to 33 points after 6 months of treatment, which translated into significant improvements of the knee function and a low level of pain.
Performing the physical therapy sessions using the re.flex sensors proved to have no adverse effects after a total of 55 sessions.


Gonarthrosis arthropathy is the most prevalent disease worldwide and the most common cause of disability. [3]

World Health Organization estimates that the number of people affected by bone and joint disease will double in the next 20 years. [4]
It has been shown that physical therapy hat the power to stop the progression of the disease and reduction of disability. [5]

Remote patient monitoring using motion tracking sensor solutions recorded positive results in the literature. A 12 week digital home care program for patients with chronic knee pain significantly improved the (KOOS) and (KOOS-PS) scales and patients had a 67% reduction in surgery interest. (6)

Unlike the small number of sensor devices available on the market, re.flex sensors allow orthopedic surgeons and physiotherapists to design complex rehabilitation protocols and gather actionable rehabilitation data.
Due to the technological innovations proposed by the system, re.flex can track 12 parameters of the knee and hip movement, which enables clinicians to design and tailor complete protocols, based on each patient’s individual needs, from a video database of 150 exercises.

Using sensors in orthopedic rehabilitation has the potential of increasing adherence for patients suffering from chronic knee and hip osteoarthritis while saving time and costs.
The purpose of this paper is to evaluate the time and money saved by a patient involved in a long term physiotherapy plan and the compliance to treatment.

Clinical study preparation

Laurentiu F. sustained an ACL tear during a basketball match back in 2011. After the ACL reconstruction, he was prescribed with a 4-month physical therapy plan.
Because of his busy schedule, he missed a few sessions in the first 2 months of physiotherapy and eventually quit without achieving complete recovery.
In 2018 he felt intense pain in both of his knees and his ability to climb stairs and perform basic movements were restricted.
After consulting with his orthopedic surgeon he had MRI scans that showed an advanced gonarthrosis on both of his knees. OKS was 23 points and the Total Knee Arthroscopy was considered to be inevitable.

Dr. Bogdan Andrei decided to have a conservative approach and designed a physiotherapy plan in the re.flex application containing active and isometric exercises meant to restore the range of motion and muscle mass, with the objective of postponing the surgery as much as possible.

Dr. Andrei Bogdan is the owner of Centrokinetic, a chain of physical therapy clinics

“I’ve seen over time that patients with knee osteoarthritis proved to be non-compliant to the physical training performed in the clinic. Having the option to monitor their home activity with re.flex gives the physiotherapists a powerful tool to gather the data and use it to objectively tailor the treatment plan, without asking the patient to come to the clinic every time”, said Dr. Bogdan Andrei.

The patient started the physiotherapy exercises using the re.flex sensors in December 2018 and he was trained to use the solution by a physical therapist, during the course of 2 home visits.

Remotely monitoring the home exercises plan using re.flex

re.flex – Recovery made simple is a remote patient monitoring tool for orthopedic physiotherapy treatment designed to be easy to use, cost-effective and capable of collecting the most relevant rehabilitation data.
The system records the progress of the knee flexion, correctness of the execution, compliance to treatment and self-reported pain.

In the present study, the patient followed a progressive physical therapy plan with 10 exercises which gradually evolved into a 14 exercise plan, as the patient improved his strength and ability to perform.

The first set of exercises: knee flexion supine, single-leg raises supine, hip abduction supine, hip flexion heel over thumb supine, single leg air circles, bicycle flexions, bridge, knee extension seated.

After several remote interactions with the assigned physiotherapist, the treatment plan was correlated with the progress and the volume was increased.
Second set of exercises: Isometric bridge, isometric knee extension seated, isometric seated knee abduction, isometric hip abduction standing, isometric hip flexion standing, isometric standing hip flexion straight knee, isometric knee flexion standing, power walk in place, squat, isometric wall squats, lunges, balance steps, calf stretch, step up with knees high.

physical therapy digital device
Fig 1: re.flex sensor kit (march 2022)

67% total compliance to treatment

Over the course of 24 weeks, Laurentiu F. performed a total of 113 remote physiotherapy sessions using the re.flex sensors, which translates into a total of 67.26% compliance to treatment.

In order to understand the potential of the re.flex sensors to increase adherence, we need to take into consideration that the physiotherapist did not proactively engage with the patient to influence the adherence.

The only interactions were initiated by the patient with the scope of increasing the volume of the sessions or questions regarding the progress.

Unlike other exercise prescription systems using mobile applications that only provide the patient with self-reported progress through video exercises, re.flex sensors are capable of collecting real-time rehabilitation data. This important differentiator keeps the patient connected with the physiotherapist and orthopedic surgeon.

These results should represent a baseline for further investigation into the impact that the physiotherapist’s intervention has on keeping the remote patient engaged in the rehabilitation plan.

Fig 2: A snapshot from the re.flex's knee assessment module (march 2022)

Using re.flex the patient had a 55% cost reduction and saved 169 hours spent in traffic

The present study took place in Bucharest (Romania), one of the most crowded cities in Europe.
For each physiotherapy session, a Romanian patient has to pay an average of 20 Euros for a group session together with other 20 patients. A 1-on-1 session in the clinic is around 35 euros.
If he had performed all of the 113 sessions in the clinic setting, Laurentiu F. had to pay a total of 2260 Euros, without taking into consideration the transportation costs and the time spent in traffic.
He only paid for re.flex 765, or 33% of the costs from the clinic.

In order to provide a clear picture of the difference between an in-clinical rehabilitation and one using a digital solution, we need to look also into time saved. We need to add at least 2 hours spent in traffic for each session, which means 226 hours saved and a total of 2825 km (25 km / session).
Using his personal car, those 2825 km would have cost him 226 liters of gas, meaning 263 Euros.

The purpose of this paper is to set a baseline for further research into the cost-effectiveness and medical outcomes of a digital assisted physical therapy program, using re.flex, for patients in different stages of gonarthrosis. The design of the system enables data collection and multiple parameters of the knee and hip movement are recorded, along with the key metrics: adherence to the home exercise prescription and pain.
From our initial data gathered with multiple outpatient physical therapy clinics, in different countries around the world, patients between 40-65 years old are very open to enroll in a digital physical therapy program with re.flex and the level of human involvement required to produce positive adherence is low. However, the 65-80 years old group requires more attention, mostly the patients who are not familiar with smartphones.

Clinical evidence generated by Dr. Bogdan Andrei, Kt. Alex Ivan – Centrokinetic physiotherapy, Bucharest, Romania, 2019

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1) Jack K, McLean SM, Moffett JK, Gardiner E. Barriers to treatment adherence in physiotherapy outpatient clinics: A systematic review. Manual Therapy, 2010, 15: 220–228

2) Di Fabio RP, Mackey G, Holte JB. Disability and functional status in patients with low back pain receiving workers’ compensation: a descriptive study with implications for the efficacy of physical therapy. Physical Therapy. 1995 Mar 1;75(3):180-93. 

3) J.C.R. Ledezma, V.S. Gloria, B.V.J. Maria Gonarthrosis Prevalence in the Elderly, its Associated Factors and Degrees of Disability. Biomedical and Pharmacology Journal, Dec 2014

4) The burden of musculoskeletal conditions at the start of the new Millenium, World Health Organization, 2003

5) Mersija Kasumovic, Emir Gorcevic, Semir Gorcevic, Jasna Osmanovic.  Efficacy of Physical Therapy in the Treatment of Gonarthrosis in Physically Burdened Working Men. Mater Sociomed. 2013; 25(3): 203–205.

6)  G. Mecklenburg, MPhil ; P. Smittenaar1*; J.C.-Hledik ; D. Perez1 ; S Hunter  Effects of a 12-Week Digital Care Program for Chronic Knee Pain on Pain, Mobility, and Surgery Risk: Randomized Controlled Trial 

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