HOME > Lapoc System Prostheses > M0771 P-BASS

eight-Stabilizing Knee with Pneumatic Cylinder
M0771 P-BASS
M0770 BASS

Activity Level and Body Weight Limits

Activity Level and Body Weight Limits
Activity Level Body Weight
2~4 100kg

Lighter and More Natural

Product Features



This knee is for users weighing less than 100 kg. There are two models to choose from based on the design of the upper knee: the M0770 BASS and the M0771 P-BASS. The basic functionality of both is the same.

Weight-Stabilizing Mechanism

Weight-Stabilizing Mechanism part

The BASS uses a weight-stabilizing mechanism to reduce wobble and noise. The brushes that conventionally hold the brake lining to knee-axle bearing are divided into three parts, with the sides holding the bearings and the central part holding the break lining. Thus, we've been able to greatly reduce the wobble and noise that develop as a result of wear and tear on conventional brushes.
The weight-stabilizing angle is widely adjustable, designed for stages of use ranging from the braking needed during the prosthetic walking training stage to the point where the brake can be completely released without wobble.

The Pneumatic Cylinder

The Pneumatic Cylinder part

The pneumatic cylinder's extension resistance and flexion resistance can each be adjusted independently and easily to suit the user's walking speed. The cylinder is designed for a wide range of walking paces, from a low-resistance "easy stroll" to "speed walks" that require a high level of resistance.

Adjustable Friction Mechanism

If you tighten the pneumatic cylinder's flexion resistance adjustment dial, the pneumatic cylinder load will push up the brake lining when the knee joint bends. If this happens, the flexion resistance that causes friction with the knee axle will grow large compared to the pneumatic cylinder on its own, which is more suitable for a faster walking pace. During extension, if the flexion resistance adjustment dial is loose, there will be very little friction applied, allowing for smooth swinging of the knee.

Lightweight, High in Strength

The knee frame using carbon-fibre reinforced polymer (CFRP)

The knee frame is made from carbon fiber reinforced plastic (CFRP), giving it exceptional strength. The overall weight of the knee joint is only 650 g, putting little burden on the user.

A Smooth Walking Gait

Thanks to these features, this knee joint lets you achieve a lighter, smoother, more natural gait that conforms to the activities of the user.

Page Top

The Concept

A Comment from the Developer

The prosthetic weight-stabilizing knees in the conventional Lapoc prosthetic leg system performed swing phase control by combining an extension assist spring with machine friction, but we were unable to achieve the natural gait our users were hoping for in that manner. Additionally, most weight-stabilizing knees share certain weaknesses in regard to stance phase control:
(1)The internal diameter of the weight-stabilizing mechanism is not consistent, narrowing during load impact and widening during load release.
(2)The wobble axle control diameter for preventing lateral wobble of the brake lock is short.
(3)The result of (1) and (2) is a vicious cycle in which lateral wobble causes an acceleration in wear and tear on the break lining, which in turn leads to greater lateral wobble.
For reasons such as these, there were issues that remained for designing knee joints. Thus, with the development of BASS, we worked to minimize these issues as much as possible, while at the same time aiming to create a weight-stabilizing knee that was easy to adjust.

Design Points

  1. We re-thought the conventional approach to weight-stabilizing mechanism design and came up with the idea of dividing up the brake lock, with the aim of improving durability by keeping the axle bearing portion and brake portion separate.
  2. Since knee joints always look so big, we designed this one to have a smaller front profile and fasten firmly to the shinbone. For the knee frame, we used the same carbon fiber reinforced plastic (CFRP) that is used to make aircraft wings, resulting in a lightweight, very strong design.
  3. Keeping usability on behalf of the prosthetists who would be adjusting the knee joint in mind, we designed it so that the weight stabilizing degree, pneumatic cylinder flexion resistance and extension resistance would all be independently and easily adjustable.


The BASS is a lightweight weight-stabilizing knee. Designed to fit in with the Japanese physique and lifestyle, it requires little energy to use and allows for a natural gait. Features such as swing phase control, low weight, and high strength, made possible by the highly durable weight-stabilizing mechanism and pneumatic cylinder, allow the user to achieve a lighter, smoother, more natural gait that conforms to the activities of the user.

Page Top

Product Specifications

M0770 and M0771 Product specification table
Module Number M0770 M0771
Product Name BASS P-BASS
Activity Level 2~4
Body Weight Limit 100 kg
Weight 650 g 690 g
Overall Length 222 mm 238 mm
Overall Width 71 mm
Material Aluminum Alloy and CFRP
Swing Phase Control Mechanism Pneumatic Cylinder
Stance Phase Control Mechanism Weight-Stabilizing Mechanism
Maximum Bend Angle 180°
Assembly Dimensions Assembly Dimensions

Page Top


The Origin of the Nickname

This knee joint was the first Lapoc product to be given a nickname. The name was chosen from submissions offered by the staff involved with Lapoc. It is powerful in appearance, and the carbon joint has the appearance of scales, suggesting a "black bass" from which the name BASS was derived.
At the time, it was quite unusual to bestow a nickname on a knee joint, and this created quite a commotion in response. The M0771 was given its name by a sales representative at a new products demonstration held at a manufacturer's workshop. Because the upper component of the knee is shaped like a pyramid, he referred to it as the P-BASS — "Pyramid + BASS = P-BASS" — and it stuck as the official name for the product.

Page Top