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Wonderful Orthopaedic, Trauma & Prosthetics

Wonderful 3F33

Product Code: OTAP-PLAC-4023

A substantial hydraulic knee for users who want a solid unit beneath them.

Give a steady walker a knee with real substance in the hand and under the socket. The 3F33 controls its swing with oil, folds to 135° and puts 1155 g of titanium and aluminium at the joint, so the order starts with asking what that kilogram buys.

Sections

Prosthetic Feet & Knees

Categories

Orthopaedic, Trauma & Prosthetics

Condition

New

Origin

China

Seller Type

Certified Professional Seller

CE & ISO Certified

Global Shipping

Supplier: Medigear

Mass is the first fact about Wonderful's 3F33, a hydraulic prosthetic knee joint for transfemoral limbs, because the sheet prints 1155 g beside the code. The Chinese name, 液压膝关节, translates as hydraulic knee joint and is silent on linkage. The other lines give a load of 150 kg, a material of TI/AL (titanium and aluminium) and a knee flexion range of 135°. Wonderful's web listings for this code print 120 kg, so limbs are planned at 120 kg until the test report settles the figure. No part is electrical, and no lock is described.

A kilogram at the joint is the price, and the sheet leaves the purchase unnamed. A larger cylinder, a longer body or structural bulk are all possible. So the buyer's first job is to ask the manufacturer to justify it with the ISO 10328 test level, the cylinder's function and the intended users. Weight is not automatically a harm. In a 2003 study of 10 dysvascular transfemoral users, two-minute walk distance did not change significantly with 150 g, 770 g or 1,625 g added, and 5 preferred 770 g. Prescribe this knee where the wearer puts a robust build ahead of a light limb, and keep it away from frail or low-mobility users.

The photograph shows a tall, dark grey unit with a long body that tapers toward its base. A small metal fitting stands on top, an open upper section reveals inner links, two oval windows sit lower down, and a ring with a side screw closes the base. Standard supply is the knee alone.

The manufacturer's drawing, shared by the enquiry team, gives the build height and the connection at each end. It is available to buyers in more than 80 countries through Medigear.uk, and the enquiry team sets out stock and lead time.

Prescribing the 3F33 begins with a question to the factory and ends with a judgement about one wearer. The question is what 1155 g buys. A service should have the answer in writing, with the ISO 10328 test level, the cylinder's function in swing and stance, and the users Wonderful designed it for. Until that arrives, the knee is a heavy hydraulic unit of unexplained purpose, and nobody should be fitted on a guess.

The judgement is whether this person carries a kilogram well. Evidence gives some room. Meikle and colleagues reported in 2003 that 10 dysvascular transfemoral users walked no shorter a distance in two minutes with 150 g, 770 g or 1,625 g added, and 5 of them preferred the 770 g condition. A 1997 treadmill study of 10 men with transtibial amputation, a different level, measured oxygen uptake 4.7% higher with 907 g added, a change the authors did not find significant. Both samples were small and made up of capable walkers. Neither tested this model or a full day of use.

So the candidates are steady community walkers with sound hip strength, a well-fitting socket and a liking for a limb that feels planted. Heavier adults may be among them, within a planning figure of 120 kg for the knee and the lowest rating in the limb.

Frail users, low-mobility walkers, people in early rehabilitation and anyone needing a locked leg belong on another specification.

Settings include limb-fitting centres, private prosthetic clinics, rehabilitation hospitals and workshops building limbs for export. NHS trusts in England order through the mandated prosthetics framework, and public buyers in other countries follow their own routes. The conformity documentation those procurement routes require is issued by the manufacturer and shared by the enquiry team.

A substantial unit for wearers who like one

Some users trust a limb they can feel swinging beneath them. At 1155 g this knee gives that sense of presence, and a trial fitting shows quickly whether the wearer welcomes it.

Weight that published research does not condemn

Ten transfemoral users in a 2003 study walked as far in two minutes with up to 1,625 g added. A clinician can cite that finding, with its small sample, when a referrer objects to the mass on principle.

Oil damping that follows walking speed

A hydraulic cylinder resists harder the faster its oil is driven. The shin therefore keeps pace when the wearer speeds up for a crossing or slows in a queue, within the settings the instructions describe.

135° of flexion for sitting and kneeling

The shin folds far enough to tuck under a chair, sit in a car or kneel at a low cupboard. That range is printed on the sheet and repeated on the manufacturer's listings.

A clear set of questions for the supplier

Because the sheet is short, the buyer knows exactly what to ask: test level, cylinder function, intended users and material split. A service that sends those four questions gets a file it can defend at audit.

No battery and no electrical testing

The knee is purely mechanical. Nothing needs charging overnight, no firmware is updated, and the service has no electrical safety test to schedule for it.

Titanium and aluminium in one frame

Two metals are named on the material line. Once the certificate shows which parts are which, a workshop can plan inspection of pivots and load paths properly.

An honest exclusion list from the start

Frail users, low-mobility walkers and anyone needing a lock are ruled out before bench time is spent. Screening referrals against that list protects both the wearer and the budget.

1155 g mass

The figure is printed beside the code on the sheet and matches Wonderful's listings. It is the largest single entry in the limb's weight budget below the socket.

Hydraulic cylinder

Both names on the sheet, English and Chinese, call the joint hydraulic. Oil passing through restrictions supplies the resistance, and the instructions for use show where it is adjusted.

Two published load figures

Sheet and website disagree, at 150 kg and 120 kg. Limbs are planned at 120 kg, and the ISO 10328 test report states which figure stands and at what loading level.

135° knee flexion range

How deeply the limb folds decides comfort in low seats, vehicles and on a bicycle. This number is consistent across the sheet and both listings.

Titanium and aluminium construction

"TI/AL" is printed once, against one mass. The manufacturer's material certificate names each alloy and the parts made from it.

Linkage type

The product name stops at hydraulic knee joint, and one web listing adds the word double. Pivot count and position are shown on the manufacturer's drawing, and they shape how stable the knee is early in stance.

Tall tapering body

In the photograph the unit is long and narrows steadily toward its lower end. A body of that length takes up shin space, so the drawing's build height matters to wearers with long residual limbs.

Top fitting

A small metal fitting stands proud of the upper end in the image. The drawing gives its type and the socket adapter it accepts.

Open upper frame

Above the midpoint, the photograph shows a gap in the frame with dark links inside and a shiny round cap alongside. These look like moving parts of the joint, and the drawing labels them.

Oval windows in the lower body

Two oval openings appear in the lower half of the pictured unit, with a yellow part visible through the upper one. What sits behind them is identified in the instructions for use.

Base ring with side screw

The pictured unit ends in a round ring carrying a screw at one side. Whether that ring clamps a tube, and at what diameter and torque, is given on the drawing.

Stance behaviour

Manufacturer web copy mentions a slight bend at heel contact and a response to downhill slopes. The instructions for use are the authority on both, and gait training follows them.

Service arrangements

Seal life, the overhaul route for the cylinder and the service interval appear in the manufacturer's maintenance schedule. The quotation from the enquiry team carries the warranty terms.

Manufacturer's quality statements

Wonderful's website describes ISO 13485 and CE certification, and its listing for this code cites ISO 9001 and testing ahead of packing. A 2022 EU declaration published in the company's name includes the code.

Order the 3F33 when two things are true. The manufacturer has explained in writing what 1155 g buys, and the wearer in front of the prosthetist is a steady walker who wants a solid knee and has the strength to swing it. Leave it for frail users, low-mobility walkers and anyone who needs a lock. Plan the limb at 120 kg unless the test report supports the sheet's 150 kg, and let the lowest-rated part set the limb's rating. Settle the cylinder's stance behaviour, the metal split and the service route in the same exchange.

Medigear.uk lists the 3F33 for business buyers worldwide and can arrange delivery, installation, commissioning, familiarisation and service cover. Ask the enquiry team for the written account of the mass, the ISO 10328 test report, instructions for use, drawing, material certificate and declaration of conformity before ordering.

FAQ

Frequently Asked Questions

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

The sheet prints the mass and stops there, so the answer has to come from Wonderful. Three explanations are plausible: a larger oil cylinder, a longer frame that replaces part of the shin tube, or thick structural sections. Each one changes who benefits. Ask for a written account covering the cylinder's function, the ISO 10328 test level and the users the design was meant for, and file it with the order.

Published evidence says not automatically. Meikle and colleagues (Archives of Physical Medicine and Rehabilitation, 2003) added 150 g, 770 g and 1,625 g to the prostheses of 10 dysvascular transfemoral users. Two-minute walk distance did not change significantly, with means of 53.4 m, 55.1 m and 52.8 m. Five preferred 770 g, four preferred 150 g and one preferred 1,625 g. The limits matter too. Those 10 people were independent community walkers; a two-minute test says nothing about fatigue across a day, and the study did not test the 3F33.

Frail users and low-mobility walkers come first on that list. Someone with weak hip muscles, a short residual limb or a new first prosthesis has to lift 1155 g at every step, and a short walking test on fitter people does not show they can. Anyone who depends on a locked leg for standing or transfers is also outside the brief, since the sheet describes no lock. Wearers whose body weight plus carried load passes the limb's planning figure are excluded.

It fits a wearer who walks steadily in the community, has the hip strength to drive a substantial unit and likes a limb that feels solid. Some people describe a very light prosthesis as vague or hard to place, and half the participants in the 2003 study chose a moderately weighted limb. A prosthetist makes the match after checking socket fit, strength and daily distance. Trial fitting with the wearer's own verdict counts for a great deal here.

Plan at 120 kg. The sheet prints "Load Weight:150Kg", while two listings for 3F33 on Wonderful's own website print 120 kg, and one manufacturer lists a range of 120 to 150 kg. Neither source gives the ISO 10328 loading level behind its number. The test report, issued by the manufacturer and shared by the enquiry team, states the rating and the level, and it is the only document that can lift the planning figure.

No. Any figure for this knee describes the knee alone, and a finished limb carries only what its lowest-rated part carries. Many structural adapters, tubes and feet are rated at 125 kg, which would cap a limb at 125 kg even if the test report supported 150 kg. At the 120 kg planning figure, the knee itself may be the limiting part. Write the limb rating on the build file beside each component's own figure.

One listing for this code names it a double hydraulic knee joint. It describes a slight bend as the heel meets the ground and an adjustment of bending angle on downhill slopes, yet the same passage calls the cylinder pneumatic. The listing titles also carry the words lock and manual locking, and no lock appears on the sheet. Treat all of this as the manufacturer's unconfirmed web copy. Establish from the instructions for use what the cylinder does in stance before promising a wearer slopes or stairs.

"TI/AL" sits beside a single mass, which reads as one knee made from both metals. The manufacturer's material certificate specifies where each metal is used, naming the alloys part by part. The split matters because the two metals differ in strength, wear at the pivots, and how a workshop inspects them for cracks. It may also explain some of the 1155 g.

The photograph shows a tall, dark grey unit with a long body that narrows toward the base. A small metal fitting sits on top; below it, a shiny round cap sits on the upper frame beside an open section with links visible inside. The lower body has two oval windows, with a yellow part visible in the upper one, and ends in a ring carrying a side screw. None of these details is named on the sheet, so the drawing identifies them.

Oil thickens in cold weather and thins in heat so that the swing can feel different between seasons. Seals wear. A weeping cylinder is normally returned to the manufacturer or an approved workshop. The service interval, permitted adjustments, and operating temperature range are given in the instructions for use. Any oil on the outside of the unit is a reason to stop using the limb and have it inspected.

The 3F33 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 declaration under EU Regulation 2017/745 dated 26 June 2022, published online in the manufacturer's name, lists "Hydraulic knee joint" with the code 3F33 as Class I under Rule 1. Structural testing of lower-limb prostheses falls under ISO 10328. When a workshop builds a limb for a named person, that limb is a made-to-order device, and the workshop holds the manufacturer duties for it.

The compliant route is the NHS Supply Chain framework for Prosthetic Components and Associated Products, which NHS England has mandated for prosthetic products. Artificial Limbs is the only lot, and the term runs from 24 November 2025 to 23 November 2027. NHS procurement routes require that framework path, and equivalent public procurement elsewhere asks the same of the suppliers it uses.