Load Limits After Orthopaedic Surgery: Biofeedback vs. Conventional Method (AppPWB)

The aim of this single-centre prospective randomized-controlled clinical trial is to assess whether patients adhere to prescribed weight bearing limits after surgical orthopaedic or traumatological interventions more accurately after instruction using a biofeedback method than using the standard method.

Partial weight bearing, commonly prescribed post-surgery in orthopaedics and traumatology, aims to stimulate healing while preventing overloading. Partial weight bearing refers to that the patient is only allowed to put 10 to 50% of their body weight on the affected limb.

The most commonly used method for instructing partial weight bearing with the patient is using a personal scale. This means that the patient can only exercise in a static position and the perceived load must be transferred to dynamic activities of daily living without further feedback. Previous reports indicate that patients often struggle to adhere to prescribed partial weight-bearing limits, frequently exceeding the specified load by 100% or more. However, when additional feedback was incorporated into training, approximately 90% of subjects successfully adhered to the partial load.

Portable or wearable measuring systems, such as pressure-sensitive insoles, offer feedback during dynamic tasks, facilitating a smoother transition to daily activities. Unlike the standard one-time instruction using a scale, these systems provide repeated feedback at each step, promoting a higher frequency of exercises. This aids patients in developing a better sense of the correct load.

This single-centre prospective randomized-controlled clinical trial aims to investigate the effectiveness of pressure insoles connected to a smartphone via Bluetooth and operated using an app in improving partial weight bearing adherence. The insoles provide direct feedback through acoustic and visual signals if the affected leg is overloaded, possibly leading to a lower proportion of steps over the load limit compared to those without feedback. Participants are randomized into either the intervention group (dynamic condition - plantar pressure insoles) or the control group (static condition - standard one-off instruction using a scale).

The primary objective is to determine whether the proportion of steps exceeding the weight bearing limit is lower in the intervention group compared to the control group 2 weeks after surgery. Secondary objectives include assessing subjective ratings of the permitted load, perceived pain, and mobility. Additionally, the trial hypothesizes that patients using the insoles can estimate applied load more accurately. The intervention group will also provide feedback on the usability of the app and insoles.

The results of this trial will contribute to enhancing postoperative treatment of patients undergoing orthopaedic surgery, thereby improving treatment outcomes and optimizing therapy regimens.

Eligibility Criteria:
Inclusion Criteria:

* Patients with prescribed partial weight bearing (joint-independent) for at least 2 weeks
* Unilateral injury of the lower extremity
* Having their own smartphone
* Age 18 years and older

Exclusion Criteria:

* Patients with prescribed full weight bearing
* Patients with prescribed complete unloading
* Patients with prescribed self-selected loading "according to pain"
* Bilateral injuries of lower extremities
* Upper extremity injuries precluding the use of crutches
* Use of walking aids prior to injury
* Neurological conditions affecting gait
* Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc.,
* Previous enrolment in a clinical trial
* Body mass \> 135 kg
* Age under 18 years