Evaluation, Adaptation, and Comparison of a Pneumatic Prosthetic System to an Otto Bock 3R20 Knee Joint in Transfemoral Amputee Patients

Abstract

Introduction:

The loss of a lower limb due to amputation represents a challenge in daily life activities, affecting a person’s independence and quality of life, making the use of a prosthesis necessary. One of the most common types of amputation is above the knee (transfemoral), for which various knee prosthesis models and mechanisms exist. These components are selected based on the patient’s mobility level. Prosthesis prices vary and increase depending on the components used. The OttoBock® 3R20® and 3R36® models, which use the same mechanical system but differ in materials, consist of a mechanical, polycentric knee joint. Due to the cost-benefit balance of this mechanism, it is the most widely used at the Instituto Nacional de Rehabilitación Luis Guillermo Ibarra Ibarra (INRLGII). Therefore, this project aims to implement a pneumatic return mechanism to provide greater stability and a smoother gait compared to the current mechanical return system.

General Objective:

To modify the mechanical return mechanism of the OttoBock® 3R20® or 3R36® knee joint by implementing a pneumatic return system and compare them through a dynamic gait study in hospitalized transfemoral amputee patients at the INR.

Specific Objectives:

• To implement the pneumatic return mechanism.

• To adapt the pneumatic system to the OttoBock® 3R20® or 3R36® knee joint.

• To fit and align the prosthetic knee to transfemoral amputee patients.

• To provide physical and occupational rehabilitation training using both the mechanical and pneumatic joint.

• To perform motion analysis of both joints.

• To compare the results between the original OttoBock® 3R20/3R36 joint and the modified version.

Methodology

An observational, longitudinal, and comparative study will be conducted on transfemoral amputee patients at the National Rehabilitation Institute. The mechanical return mechanism of the 3R20® or 3R36® prosthesis will be modified by incorporating a pneumatic system. The dynamic gait performance of each system will be evaluated and compared.

Expected Results

To obtain a comparable dataset of gait analysis between the two knee mechanisms, evaluating the feasibility of adaptation, as well as the advantages and disadvantages of using the pneumatic prosthesis.

Timeline

The protocol will be developed over a period of 18 months, beginning with the evaluation of the patients' residual limb, taking measurements, socket manufacturing, and prosthesis implementation. Follow-up will include physical and occupational therapy, along with gait evaluation using both mechanisms.