iLAST: Immersive Knee Rehabilitation - A New Prototype

Closed Human-Computer Interaction Master Project Embodiment Lab

1. Introduction
2. Goals
3. Approach
   1. Elicitation
   2. Analysis
   3. Specification
   4. Validation
4. Research Plan
5. References

1. Introduction

Injuries of the anterior cruciate ligament (ACL) are widespread in the field of competitive sport and have significant physical and psychosocial consequences, especially for young athletes [1]. Recovering from an ACL injury can include non-surgical or surgical treatment. In any case athletes must go through an ACL reconstruction (ACLR) process, in which they receive physiological therapy, strength training and coordination training. In a systematic review of Ardern et al. [2] was found, that only 65 \% of athletes who received an ACLR, return to their pre-injury level of sport and only 55 \% return to a competitive level. Virtual reality (VR) rehabilitation and telerehabilitation for orthopedic post-injury treatments are relatively new fields of research and have the goal of enhancing the physical recovery process of injured patients [3]. Moreover, VR rehabilitation offers advantages, that conventional does not. Conventional ACLR programs are often held in a clinical setting, which makes it hard to transfer the outcome to the everyday life [3]. A fully immersive virtual environment (VE) for ACLR treatment can be designed very similar to the reality, which can increase the effectiveness during the program and the sustainability after the program has been finished. Therefore, a well-designed VE to enhance ACLR treatment, can improve the recovery process. Further, VR-technology is usable at home and compared to continuous clinic visits relatively cheap [3]. In a study where conventional ACLR was compared to a therapy, that was based on exercising with a Wii Balance Board, no significant differences in terms of restoring neuromuscular abilities and increasing functional performance were found between the two therapies [4]. There is evidence, that neuromuscular rehabilitation plays an important role in the ACLR process, which can be specifically triggered by VR-environments by undergoing the principles of motor learning discussed by Gokeler et al. [1]. Furthermore, a game-like virtual environment, in which the VR-therapy takes place, can increase the patient’s motivation, which has positive effects on the outcome of motor learning itself [5]. Future findings concerning the optimization of ACLR treatment with the help of VR-applications are likely to be transferred to other cases than the competitive sport, e.g., the elderly or non-competitive sports. These advantages indicate that a VR-application, where the patient can exercise in, offers a lot of opportunities for increasing the effectiveness of the recovery after an ACLR. Thus, this project 's goal is, to develop a virtual training environment, that can be used by patients at home, subject to medical and physio-therapeutical correctness, but still provides game-like elements to intensify the patient 's experience such that the motivation of finishing the treatment stays stable to the point, where the injury is fully cured. The research project iLAST (Immersive Leg Coordination and Strength Therapy) was founded to research concrete implementations for this problem.

2. Goals

The goal of this project is firstly, elaborating software and hardware requirements for the VR-prototype for enhancing ACLR treatment. Secondly, implementing the defined requirements in Unity. The scope of implementations will be condensed out of all defined requirements. It is likely, that only the requirements will be chosen, that meet the main functionality of the prototype. This process includes the consideration of three perspectives, that must be combined in this project. These perspectives are the medical perspective, the technical perspective and the scientific perspective. Most likely, these perspectives will overlap and must be sorted into a system, that represents the best possible fulfillment of demand for each perspective. In addition, the level of fulfillment concerning the goals will be evaluated after the implementation. This will be realized by comparing the pre-defined requirements with the assembled prototype and benchmarking relevant parameters of the prototype in different scenarios in the application.

3. Approach

The approach to acquire the software requirements, follows the elaboration standard IEEE830-1998 [6]. The IEEE formulates four main steps for establishing the software requirements for a prototype: elicitation, analysis, specification and validation. More details about the four steps and their use concerning this project are given in the following.

3.1 Elicitation

To gather data there are two ways that will be used during this project. Firstly, there is literature ([1-9] and more) about VR-applications enhancing orthopedic rehabilitation procedures, which consequently leads to a deductive approach. These literature gives a good overview and introduction into the topic but is formulated too general to be used to specify requirements. Thus, a different elicitation technique, the semi-structured interview, has been chosen to get more data regarding the needs and problems the application must solve. The prototype needs to be elaborated from three perspectives. For each perspective a different interview protocol will be designed, that will survey information from one expert per perspective. The first one is about the medical and therapeutical viewpoint, which will mostly define the physical exercises, that users must absolve to recover from the injury. The second one is regarding the technical practicability of the rehabilitation procedure in VR. The technical requirements are firstly oriented to the guidelines given by Waltemate et al. [7], where they mention, that a real-time interactive system for motor learning must give the user permanent feedback of one 's own motion, have low latency, a high frame rate, offers minimal disturbance and uses a robust tracking method [7]. More details will be collected during the interview. The third perspective is relevant and necessary to combine existing findings in this and similar fields with the first and second perspective. Additionally, this perspective shall bring up ideas, that go beyond this combination for the prototype 's use in research and in the industry. The accumulated information is natural language encoded, thus informal, and must be transformed into a more formal way later by the interviewer.

3.2 Analysis

The informal data gathered from the interviews must be analyzed, structured and formalized. It is also desirable, that the problem statements, that the application should attack, will be written down in text form. The results of the elicitation must give enough information about the necessities of this project 's medical, scientific and technical requirements, which can then determine the concrete software specifications in the next step of the elaboration.

3.3 Specification

To have a good overview of the results of the analysis, the data can be displayed visually via models. The models should represent the problems, that were mentioned by the interviewees and connect them together to a system. Derived from the visual representations and the analyzed data in text form, concrete hardware and software specifications can be formulated.

3.4 Validation

Based on the specific requirements, the prototype can be tested. Firstly, the prototype will be tested qualitatively by looking at the requirements and evaluate in which way they have been satisfied. Secondly, the application shall be tested quantitatively by logging the latency, the frame rate, the frame time and the workload of the CPU, GPU and RAM. The qualitative parameters will be surveyed during different moments in the application to find out minimum and maximum values, which give the best impression of how robust the prototype is in different scenarios.

4. Research Plan

5. References

[1] A. Gokeler, D. Neuhaus, A. Benjaminse, D.R. Grooms, J. Baumeister, “Principles of Motor Learning to Support Neuroplasticity After ACL Injury: Implications for Optimizing Performance and Reducing Risk of Second ACL Injury,” in Sports Med. Jun. 2019, vol. 49, no. 6, pp. 853-865. doi: 10.1007/s40279-019-01058-0

[2] C. L. Ardern, J.A. Feller, N. Taylor, K.E. Webster, “Fifty-five per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and metaanalysis including aspects of physical functioning and contextual factors” in British Journal of Sports Medicine, Aug. 2014, vol.48, no 21, pp. 1543-1552, doi: 10.1136/bjsports-2013-093398

[3] A.R. Youseff, M. Gumaa, “Virtual Reality in Orthopedic rehabilitation” in Virtual Reality in Health and Rehabilitation, I. CRC Press, Boca Raton, FL, USA, 2020, ch. 16, pp. 215-230; eBook ISBN: 9780429351365

[4] G. Baltaci, G. Harput, B. Haksever, B. Ulusoy, H. Ozer, “Comparison between Nitendo Wii Fit and conventional rehabilitation of functional performance outcomes after harmstring anterior cruciate ligament reconstruction: prospective, randomized, controlled, double-blind clinical trial” in Knee Surgery Sports Traumatology Arthroscopy, 2013, vol. 21, pp. 880-887, doi: 10.1007/s00167-012-2034-2

[5] G. Wulf, R. Lewthwaite, “Optimizing performance through intrinsic motivation and attention for learning: the OPTIMAL theory of motor learning” in Psychon Bull Rev, Jan. 2016, vol. 23, pp. 1382-1414, doi: 10.3758/s13423-015-0999-9

[6] IEEE830-1998, “IEEE Recommended Practice for Software Requirements Specifications”, IEEE, New York, NY, USA, 1998, available: http://www.math.uaa.alaska.edu/~afkjm/cs401/IEEE830.pdf., accessed: 2021-03-11

[7] T. Waltemate, F. Hülsmann, T. Pfeiffer, S. Kopp, M. Botsch, “Realizing a Low-latency Virtual Reality Environment for Motor Learning”, in Proceedings of the 21st ACM Symposium on Virtual Reality Software and Technology, VRST ‘15, New York, NY, USA: ACM, 2015, pp.139-147

[8] M. Lucio-Alonso, R. Mendoza-González, H. Luna-García, Z. A. Maldonado-Morales, M. A. Rodríguez-Díaz, F. J. Luna-Rosas, “A first version of design guidelines for virtual environments to support physical rehabilitation,” in Proceedings of the 5th Workshop on ICTs for improving Patients Rehabilitation Research Techniques Association for Computing Machinery, New York, NY, USA, Sep. 11, 2019, pp. 157–161. DOI:https://doi.org/10.1145/3364138.3364171

[9] F. Schmidt, “Analyse konventioneller Physiotherapie nach Knieverletzungen für die Verbesserung eines Therapiesystems in Virtueller Realität” May 19, 2019, unpublished

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