Iranian Firm Makes Cost-Effective Hydraulic Knee Joint

“This product enables the person to control the speed of movement in the two phases of flexion and extension separately. Also, the EBS mechanism in this joint, while entering the standing phase and when the heel hits the ground until entering the foot flexion phase, is responsible for controlling the secondary flexion and stability of the joint,” said Reza Iranpour, the managing director of the knowledge-based company.

Noting that the technology leads to a reduction in the energy consumed by the person while walking and a reduction in the impact felt in the remaining limb, pelvis and spine, he said, “When EBS is inactive, the intersection of the lines of the 4-bar mechanism is located close to the instantaneous axis of rotation of the joint, which allows the person to bend the joint at will. However, when the EBS system is activated, this intersection is moved away from the instantaneous axis of rotation, and the locking mechanism prevents the joint from bending due to the passage of the weight line. This intelligent design provides the user with security and stability of movement.”

“Meantime, the resistance of the EBS system is directly related to the speed of movement, meaning that at higher speeds, the EBS function does not prevent the joint from moving smoothly,” Iranpour said.

In a relevant development in August, researchers at the University of Tehran (UT) had also designed and produced a passive artificial knee with dual function for amputees.

Rezan Nasiri, a professor at the Machine Intelligence and Robotics Department of University of Tehran (UT), said in an interview with Iranian media that amputees make up the majority of the physically disabled community in the country, and a large number of them are war veterans.”

Expressing her regret that the artificial body parts available in the country are either not of good quality in their construction and design, or they are available for huge prices, she added, “Among the most important of these artificial body parts is the artificial knee for above-knee amputees, which greatly affects the way they walk.”

 “For that, this research group, in the form of the master's degree research project jointly conducted by Ayoub Davoudi and Zain El Abedin Soleimani, in 2025 started studying the biomechanics of the body during walking, the role of the knee and how it functions during walking and finally designed an effective artificial knee at a low cost,” the professor added.

"By studying the biomechanics of the human body, we found that the knee has a dual function during walking, so that when it is on the ground (stance phase), it has high hardness and when it is swinging off the ground (swing phase) it has low hardness,” the professor went on to say.

“The result of this research work was the design of a new passive prosthetic knee with a dual function similar to the natural knee,” the researcher said, adding, “This design was tested on above-knee amputees and was patented in the US Patent Office under the name passive prosthetic knee in 2022."

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