Joint torque variability and repeatability during cyclic flexion-extension of the elbow

Simulation of a control method for active kinesiotherapy with an upper extremity rehabilitation exoskeleton without force sensor

Exoskeleton-aided active rehabilitation is a process that requires sensing and acting upon the motion intentions of the user. Typically, force sensors are used for this. However, they increase the weight and cost of these wearable devices. This paper presents the methodology for detecting users' intentions only with encoders integrated with the drives. It is unique compared to other algorithms, as enables active kinesiotherapy while adding no sensory systems. The method is based on comparing the measured motion with the one computed with the idealised model of the multibody system. The investigation assesses the method's performance and its robustness to model and measurement inaccuracies, as well as patients' unintended motions. Moreover, the PID parameters are selected to provide the optimal regulation based on the dynamics requirements. The research proves the presented concept of the control approach. For all the tests with the final settings, the system reacts to a change in the user's intention below one second and minimises the changes in proportion between the system's acceleration and the generated user's joint torque. The results are comparable to those obtained by EMG-based systems and significantly better than low-cost force sensors.

Elbow joint biomechanics during ADL focusing on total elbow arthroplasty - a scoping review

BACKGROUND

Overloading is hypothesized to be one of the failure mechanisms following total elbow arthroplasty (TEA). It is unclear whether the current post-operative loading instruction is compliant with reported failure mechanisms. Aim is therefore to evaluate the elbow joint load during activities of daily living (ADL) and compare these loads with reported failure limits from retrieval and finite element studies.

METHODS

A scoping review of studies until 23 November 2021 investigating elbow joint load during ADL were identified by searching PubMed/Medline and Web of Science. Studies were eligible when: (1) reporting on the elbow joint load in native elbows or elbows with an elbow arthroplasty in adults; (2) full-text article was available.

RESULTS

Twenty-eight studies with a total of 256 participants were included. Methodological quality was low in 3, moderate in 22 and high in 3 studies. Studies were categorized as 1) close to the body and 2) further away from the body. Tasks were then subdivided into: 1) cyclic flexion/extension, 2) push-up, 3) reaching, 4) self-care, 5) work. Mean flexion-extension joint load was 17 Nm, mean varus-valgus joint load 9 Nm, mean pronation-supination joint load 8 Nm and mean bone-on-bone contact force 337 N.

CONCLUSION

The results of our scoping review give a first overview of the current knowledge on elbow joint loads during ADL. Surprisingly, the current literature is not sufficient to formulate a postoperative instruction for elbow joint loading, which is compliant with failure limits of the prosthesis. In addition, our current instruction does not appear to be evidence-based. Our recommendations offer a starting point to assist clinicians in providing informed decisions about post-operative instructions for their patients.

Development of a multibody model to assess efforts along the spine for the rehabilitation of adolescents with idiopathic scoliosis

INTRODUCTION

Gait analysis has often been recognized as helpful for the therapeutic follow-up of adolescents with idiopathic scoliosis (IS).

METHODS

A multibody model of the human body was developed to display the intervertebral efforts along the spine of each adolescent with IS, and highlight the efforts that significantly differ from typical age-matched healthy adolescents. The intervertebral efforts of one adolescent with IS and an age-matched adolescent during a complete gait cycle were computed and compared.

RESULTS

All intervertebral efforts are larger in the adolescent with IS compared to the healthy adolescent, except for the vertical torque. The average medio-lateral torque and force for the participant with IS are respectively 200% and 114% higher.

CONCLUSION

This study revealed that the pathological efforts are not concentrated around critical points but distributed along the spine. Thus, higher average efforts along the spine in adolescent with IS may influence the spine deformity due to mechanical modulations according to the Hueter-Volkmann Law. The potential of this model is promising for the therapeutic follow-up of adolescents with IS because it provides real-time efforts along the spine, as well as the corresponding information about the asymmetrical behavior of the spine during gait.