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Orthopaedic, Trauma & Prosthetics
Wonderful FBK-58G

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Wonderful Orthopaedic, Trauma & Prosthetics

Wonderful FBK-58G

Product Code: OTAP-PLAC-4031

The step up to a free-swinging knee, for walkers who have earned it.

Move a proven walker off a locked or basic first joint and onto air-paced free swing. The FBK-58G brings four-link geometry, 870 g, a 150 kg load weight and 145° of flexion on the sheet, for the user whose test scores say the next stage has arrived.

Sections

Prosthetic Feet & Knees

Categories

Orthopaedic, Trauma & Prosthetics

Condition

New

Origin

China

Seller Type

Certified Professional Seller

CE & ISO Certified

Global Shipping

Supplier: Medigear

The second knee in a rehabilitation pathway is the role for Wonderful's FBK-58G, a pneumatic geometry four-link prosthetic knee joint for transfemoral and knee-disarticulation limbs. Its Chinese name on the sheet is 气动几何四连杆膝关节. Four figures are printed with it: 870 g, a load weight of 150 kg, material TI/AL7075 and a knee flexion range of 145°. The joint has no microprocessor, battery or electrical part, and the sheet lists no manual lock.

That absence defines the user. A first limb often carries a locked or heavily braked joint, because a new walker is still learning to hold the hip steady over the prosthesis. Once that control is there, a lock costs a stiff-legged gait and a hitched hip at every stride. Here the shank swings freely, and an air cylinder paces it as cadence rises and falls. The move is earned by measurement. A prosthetist and physiotherapist judge readiness against repeated walk tests and a mobility score, and nobody still building hip control should be put on this joint.

The photograph shows a black body with a silver-coloured curved link down one side, cut with angular recessed panels and fixed by a screw at each end. Three further screw heads sit on the black parts behind it, and a metal pyramid stands on a black top plate. Which components are titanium and which are 7075 aluminium is set out in the manufacturer's parts list, and the instructions for use describe the cylinder adjusters.

Build height, connection sizes and fastener dimensions are given on the manufacturer's drawing, which the enquiry team shares. It is available to buyers in more than 80 countries through Medigear.uk, and the enquiry team sets out stock and lead time.

The FBK-58G belongs at one point in a user's rehabilitation: after the first limb has done its work. Its candidate has finished early gait training, left the parallel bars, and walks indoors and outdoors on a locked or basic joint with steady hip control. What that person lacks is swing. A free shank paced by air lets step length and speed vary, which is the capacity US Medicare's functional level 3 describes as variable cadence.

Readiness is a team decision. The prosthetist prescribes, the physiotherapist brings the numbers, and the user states what the limb is for. In Gailey's 2002 study of 191 people, mean AMPPRO scores were 34.7 at K2 and 40.5 at K3 out of 47. Resnik and Borgia put the smallest real change at 3.4 points, 34.3 m on a two-minute walk and 45 m over six minutes. Gains beyond those margins across two sessions are progress that measurement error cannot explain.

Those studies validate the tests and say nothing about any knee. No trial has fixed a score at which a locked joint should give way to a free one, so services write their own criteria and audit them.

The change also carries risk. A user leaving a lock meets a joint that can bend under load if the hip is late, and falls training belongs in the first sessions. Pneumatic swing evidence is mixed: in a crossover trial of 28 transfemoral users, 19 preferred it, while energy cost at 2 and 3 km/h was higher.

Limb-fitting centres, rehabilitation units and private workshops are the usual settings. NHS trusts in England buy through the mandated NHS Supply Chain framework, and equivalent public procurement elsewhere asks the same. The conformity documentation those procurement routes require is issued by the manufacturer and shared by the enquiry team.

A defined place in the prescription sequence

Services that stage their prescriptions need a joint for the user who has passed the first stage. This one fills that slot with a free shank, air pacing and linkage stance geometry.

Free swing after a stiff-legged start

A user coming off a lock stops vaulting and hip-hitching to clear the toe, because the shank now bends through swing. That gait change is the reason for the move, and it shows on video within a session or two.

Pacing that follows the walker

Air resistance in the cylinder rises as the shank moves faster. Someone who has just learned to vary speed gets a shank that keeps up at a stroll and at a brisk walk, within whatever range the instructions for use give.

A decision that can be measured

The same tests that justify the change can be rerun on the new joint. A service gets a before-and-after record in metres, seconds and AMPPRO points, which is what a funder or auditor asks to see.

Stance help from the linkage

Four links move the centre of rotation as the joint bends. Near full extension that geometry lets body weight hold the knee straight, which matters to a walker meeting an unlocked joint for the first time.

Deep flexion for daily tasks

The sheet gives 145° for the bare joint. For someone used to a rigid leg under a table or in a car seat, that range changes how sitting, kneeling and dressing are done.

Load weight printed at 150 kg

A printed figure gives the workshop a starting point for component selection. The limb's final rating then follows its lowest-rated part.

Nothing electrical to manage

No charger, firmware or battery enters the user's routine or the service's workload, and no electrical safety testing applies. The user has one new skill to learn, which is walking on a free joint.

Four-link polycentric frame

Four links join the upper and lower sections, so the pivot point shifts through the bend. The manufacturer's drawing shows the link lengths and the alignment reference line.

Pneumatic swing cylinder

Flexing the shank compresses air, and the compressed air helps return it. How many adjusters the cylinder has, and what each one does, is described in the instructions for use.

"Geometry" in the product name

The English name includes the word, and the Chinese name uses 几何. The manufacturer's written configuration explains whether that denotes a stance-locking position beyond ordinary four-link stability.

870 g mass

Printed in brackets beside the code. Weigh the joint when it arrives and log the reading with the serial number, since supplied connectors alter what the user carries.

150 kg load weight

This is the sheet's figure for the joint. The manufacturer's test report provides the ISO 10328 loading level, which the enquiry team shares.

145° knee flexion range

A goniometer reading on the completed limb belongs in the fitting record. Socket brim and cosmetic cover both take degrees off the bare-joint figure.

Titanium and 7075 aluminium

Material is printed as TI/AL7075. The parts list with the quotation assigns each metal to links, pivots and connectors.

Silver-coloured side link

In the photograph, a curved silver-coloured link runs down one side of the joint. Angular recessed panels are cut into its face, and a screw fixes it at the top and at the bottom.

Black body and rear parts

The photograph shows a black body behind the side link, with three more screw heads visible on the black parts toward the rear. Check each pivot for play at review.

Pyramid on a black top plate

A metal pyramid rises from a black plate at the top of the joint in the photograph. The drawing identifies its size and the adaptersit fitst.

Lower end

The base in the photograph is black, with a small screw at one side. The drawing states what it accepts and the tightening value for that screw.

Fasteners and torque

The instructions for use list thread sizes and tightening values for the whole assembly. Note the wrench setting in the record alongside the cylinder positions.

FBK prefix and G suffix

Both are printed on the sheet with no key. The manufacturer's written configuration, shared by the enquiry team, sets out the series and the suffix meaning.

Unpowered operation

Linkage and compressed air do all the work. The joint has no sensor or stored programme, so its behaviour depends on alignment and adjuster positions.

Manufacturer quality statements

Wonderful's website claims ISO 13485 and CE certification for the company as a whole. The manufacturer issues model-level documents and shares them with the enquiry team.

Choose the FBK-58G for the user who has finished with a locked or basic first joint and can prove it: steady hip control, discharge from early gait training, and walk-test and AMPPRO gains larger than measurement error. It suits services that stage prescriptions and want a mechanical second stage at 870 g. Hold back for anyone still building standing balance, anyone who relies on a manual lock and anyone above the limb's settled rating. Agree who signs the readiness decision and which scores it rests on. Settle the ISO 10328 loading level, the meaning of "Geometry", FBK and G, and the cylinder service terms in writing.

Medigear.uk lists the FBK-58G for business buyers worldwide and can arrange delivery, installation, commissioning, familiarisation and service cover. Ask the enquiry team for the ISO 10328 test report, the written configuration, the drawing, the instructions for use and the warranty terms before ordering.

FAQ

Frequently Asked Questions

Everything buyers need to know about sourcing medical equipment through MediGear.

The treating team decides, never the supplier and never the user alone. In most services the prosthetist prescribes, the physiotherapist supplies the gait and outcome data, and a rehabilitation physician signs off where the service requires it. The user's own goals belong in that discussion, since a free knee asks for more attention on rough ground. Write the decision and the scores behind it into the record on the day it is made.

Three are common. The Amputee Mobility Predictor with a prosthesis (AMPPRO) scores 21 tasks out of 47, and in Gailey's 2002 study of 191 people the mean was 34.7 at K2 and 40.5 at K3. Timed walks add distance, and the Timed Up and Go adds a turn and a sit. None of these tools was designed to pick a knee, so they inform the team's judgement and do not replace it.

Resnik and Borgia (Physical Therapy, 2011) retested 44 people with a unilateral lower-limb amputation. The smallest change beyond measurement error was 34.3 m on the two-minute walk, 45 m on the six-minute walk and 3.4 points on the AMPPRO. A gain below those figures may be noise. Repeat the test under the same conditions before treating it as a milestone.

Reid and colleagues (Journal of Rehabilitation Medicine, 2015) tested 86 people with lower-limb amputations at mixed levels. Six-minute walk distance averaged 271.8 m in the K1 and K2 group and 408.2 m at K3. A two-minute distance of 113 m or more predicted at least 300 m over six minutes. These are group averages across amputation levels, so they describe a population and set no pass mark for one person.

No. The K-levels come from US Medicare, which defines level 3 as the ability or potential to walk at variable cadence, and that payer's policy reserves fluid and pneumatic knees for level 3 and above. It is a funding rule in one country. Elsewhere the decision rests on clinical judgement backed by repeated measures, and no trial has set a threshold for moving from a locked joint to a free one.

It is wrong as a first limb for anyone still building hip extensor strength and standing balance, and for a user who depends on a manual lock, since the sheet lists none. A Timed Up and Go of 19 seconds or longer flagged repeated falls in one study of 40 people with transtibial amputations, which is a reason to wait and retrain. Users above the limb's settled load rating are excluded too.

The sheet prints "Pneumatic Geometry Four-Link Knee Joint", and the Chinese name uses 几何, meaning geometric. In a four-link joint the linkage geometry places the centre of rotation so that body weight helps hold the knee straight in stance. Whether this model adds a distinct geometric locking position is set out in the manufacturer's written configuration, which the enquiry team shares.

Neither the sheet nor the manufacturer's public listings define them, and no listing for this code was found on the manufacturer's website. The letters may mark a product line, a frame design or a finish. Quote FBK-58G in full on the order, check it against the label on receipt, and ask the enquiry team for the manufacturer's written configuration.

It is the figure printed for this joint alone, and the sheet gives it without an ISO 10328 loading level. The manufacturer's test report, shared by the enquiry team, names the level and the conditions. Every limb takes the rating of its weakest part. Many structural adapters carry 125 kg, and a limb built with one of them is a 125 kg limb whatever the joint above it can bear.

A user who has walked stiff-legged gains a bend for sitting, kneeling and getting into a car. Rowe and colleagues (Gait and Posture, 2000) measured 20 older adults with healthy knees and found that stairs and chairs took 90–120° and a bath about 135°. The 145° on the sheet belongs to the bare joint, so measure the finished limb with its socket and cover fitted.

Seals wear, and resistance can shift with temperature. The service interval, seal life, adjuster tools and any cadence range for this unit are set out in the manufacturer's instructions for use. A user new to free swing changes quickly in the first months, so plan early reviews to retune the cylinder as walking speed climbs.

The FBK-58G is typically Class I under UK MDR 2002, or higher depending on use, as stated on the manufacturer's declaration of conformity, which the enquiry team shares. A limb built around it for a named patient is a custom-made device, and the workshop that builds it holds the manufacturer duties. NHS trusts in England buy through the mandated NHS Supply Chain Prosthetic Components and Associated Products framework, running from 24 November 2025 to 23 November 2027, and equivalent public procurement elsewhere names its own route.