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Orthopaedic, Trauma & Prosthetics
Wonderful 4F21-AL-2

✓ Certified Professional Seller

Wonderful Orthopaedic, Trauma & Prosthetics

Wonderful 4F21-AL-2

Product Code: OTAP-PLAC-3145

Material, bore and build height, chosen to the limb being built.

The 4F21 is a single clamp design offered in several configurations. Which one a build needs is decided by the user's weight, the pylon diameter already specified, and the space available between socket and floor. Listed on Medigear.uk for UK business buyers.

Sections

Prosthetic Components & Adaptors

Categories

Orthopaedic, Trauma & Prosthetics

Condition

New

Origin

China

Seller Type

Certified Professional Seller

CE & ISO Certified

Global Shipping

Supplier: Medigear

A tube clamp is one of the simplest fittings in a prosthesis and one of the most consequential. The pylon is a plain cylinder with nothing to engage, so the clamp holds it purely by friction: a slot through the body allows the bore to close as the screws are drawn up, and the pressure between bore and tube resists the pylon rotating or sliding under load.

Two of the limb's defining measurements are set at that joint. How far the pylon enters the bore establishes the distance between socket and foot. How it is turned before the screws are tightened establishes toe-out or toe-in. Both remain adjustable, which is why a clamped joint is used rather than a bonded one, and both are revisited as a user's alignment needs develop through rehabilitation.

Three variables then decide which version of the fitting a given build requires.

Material sets the ceiling on clamping force. Available friction depends on clamping pressure, clamping pressure depends on how much force the screws can apply, and that is limited by where the threads and body begin to deform. Stainless tolerates higher torque than a light alloy of the same geometry, which allows more grip and so a higher load before the joint can slip, and it also behaves better against water and grit at a fitting sitting low on the limb. Aluminium keeps mass down, which matters well down the build where weight is accelerated through every swing. Material therefore follows the user's weight and activity level rather than preference.

Bore diameter is a compatibility absolute. Modular systems use two pylon diameters, the larger specified where loads are higher because resistance to bending rises sharply with diameter for a given wall thickness. A clamp is bored for one or the other and no adaptor reconciles them, so the diameter is settled at specification and pylon, clamp and any tube adapters above all follow it.

Build height is a space constraint. There is a fixed distance between the bottom of the socket and the floor, set by the patient: a long residual limb leaves little room, a knee disarticulation less still because the socket extends to where the anatomical knee sat, and a short transfemoral limb leaves ample space. Every fitting spends part of that budget, and where the total exceeds what is available, components must be substituted for lower-profile alternatives. A taller clamp is useful where space is plentiful, since it absorbs length that would otherwise need a longer pylon.

Two published figures apply across all variants and should come from the manufacturer rather than judgement. Clamp screw torque is what converts the material's capacity into actual grip, and it is specific to material and screw specification. Minimum tube insertion depth determines the contact area the friction acts over. Under-torque and shallow insertion both reduce holding capacity, and neither gives any visible sign until the joint moves.

These are components supplied for fitting within a prosthesis by a qualified prosthetist, who establishes the build height available, selects material and bore to the patient, cuts the pylon, sets length and rotation and tightens to the specified torque. Variant specifications, ratings, torque and insertion depth are provided by the seller at quotation, with UKCA or CE marking documentation, the declaration of conformity, instructions for use and warranty terms issued by the manufacturer or held by the seller.

Modular transtibial and transfemoral builds use a tube clamp at the pylon connection, with the variant chosen to the patient.

Heavier users and higher activity levels are served by the stainless variants, which support higher clamping force.

Weight-sensitive builds are served by the aluminium variants, which reduce mass low down the limb.

Higher load builds are commonly specified on the larger pylon diameter, which determines the bore required.

Long residual limb and knee disarticulation fittings are constrained by build height, which decides which variant can be used.

Limb length and toe-out are both established at this fitting and revisited as alignment needs change.

Clinics holding stock need the family across materials and bores, since neither is interchangeable once ordered.

One Design, Configured to the Build

Material, bore and build height are selected against the patient and the components already specified.

Material Chosen for Clamping Capacity

Stainless supports higher screw torque and so more grip, while aluminium keeps mass down low in the limb.

Bore Matched to the Pylon

The clamp is bored for one of the two modular diameters, settled at specification along with the tube and adapters.

Height Matched to the Space

Build height is chosen against the measured distance between socket and floor after the foot and any knee are accounted for.

Two Measurements Set at One Fitting

Insertion depth sets limb length and rotation before tightening sets toe-out, both adjustable afterwards.

Grip Across the Full Contact Area

Closing the slot grips the pylon by friction over its whole contact length rather than at any single point.

Adjustment That Survives the Bench

Alignment changes during rehabilitation are accommodated by loosening, resetting and retightening to torque.

Torque Specified by Material

The figure that converts material capacity into actual grip is specific to the variant and comes from the manufacturer.

Insertion Depth Established

Minimum pylon engagement determines the contact area the friction acts over.

Variants Compared in One Place

A buyer sees the options against each other rather than across separate listings.

Supply and Documentation Arranged

Medigear.uk can arrange supply, documentation and the provision of consumables.

Tube Clamp Fitting for Modular Prostheses

Joining a pylon to an adapter, supplied across material, bore and build height variants.

Reference Family: 4F21

With suffixes denoting material, bore and build height, to be confirmed against the full table.

Manufacturer

Wonderful Rehabilitation, to be confirmed at quotation.

Material Options

Aluminium and stainless steel, with grade and alloy to be confirmed.

Finish

Anodised on aluminium variants and bare on stainless, to be confirmed.

Bore Diameter Options

Corresponding to the two modular pylon diameters, to be confirmed.

Build Height Options

More than one height offered, to be confirmed against the reference table.

Clamp Slot and Screws

Slot closing onto the tube, with screw size, count and type confirmed at quotation.

Clamp Screw Torque

Confirmed at quotation by material and screw specification.

Minimum Tube Insertion Depth

Confirmed at quotation.

Maximum Body Weight by Material

Confirmed at quotation for each variant.

Product Weight by Variant

Confirmed at quotation.

Proximal Connection

Confirmed at quotation.

Compatible Pylons and Adapters

Confirmed at quotation, matched to bore diameter.

UKCA or CE Marking and Declaration of Conformity

Issued by the manufacturer and requested from the seller at quotation.

Instructions for Use

Provided by the seller at quotation, and required before fitting.

Warranty Terms

Set by the seller at quotation.

The 4F21 is a single tube clamp design supplied across materials, bore diameters and build heights, joining a pylon to an adapter in a modular lower limb prosthesis. The fitting itself is simple: a plain cylindrical pylon offers nothing to engage, so the clamp holds it by friction as a slot in the body closes under its screws, and two of the limb's defining measurements are established there, with insertion depth setting the distance between socket and foot and rotation before tightening setting toe-out. Which configuration a build needs comes down to three things. Material sets the ceiling on clamping force, since grip depends on how hard the screws can be driven before threads or body deform, and it also governs mass and corrosion behaviour. Bore diameter is absolute, because a clamp takes one of the two modular pylon sizes and nothing reconciles the difference. Build height is a space constraint, decided by the distance left between socket and floor once the foot and any knee are accounted for. None is adjustable after purchase, so all three are specified on the order. Selection and fitting are the work of the prescribing prosthetist. Variant specifications, ratings, torque and insertion depth are provided by the seller at quotation alongside UKCA or CE documentation. Medigear.uk lists the range for UK business buyers and can arrange supply, documentation and the provision of consumables. Enquire for a written quotation.

FAQ

Frequently Asked Questions

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

It is a tube clamp fitting joining a pylon to an adapter in a modular lower limb prosthesis, supplied in several material, bore and build height configurations.

By friction. A slot allows the bore to close as the screws are tightened, and the resulting pressure resists the tube rotating or sliding.

Aluminium and stainless steel in the materials offered, with bore diameters corresponding to the two modular pylon sizes and more than one build height.

Stainless supports higher clamping force and suits heavier users and wet conditions; aluminium keeps mass down low in the build. The choice follows weight and activity.

By the pylon diameter already specified for the build. A clamp takes one diameter and no adaptor reconciles the two.

By the space measured between socket and floor once the foot and any knee are accounted for.

No. Material, bore and build height are all fixed at manufacture, which is why all three are specified on the order.

AL and SS denote material, 3 and 34 denote bore, and EL appears to denote build height. No single code states all three, so all three should be stated explicitly.

Insertion depth sets length, and turning the pylon before tightening sets toe-out or toe-in. Both remain adjustable.

Both determine actual grip, and both reduce holding capacity without any visible sign until the joint moves.

A qualified prosthetist, who selects the variant, cuts the pylon, sets length and rotation and tightens to the specified torque.