Other

National Research Development Corporation

Howmedica International Inc.

University of Exeter

Robin S Ling

Alan J Lee

W E Mikhail

James J Elting

Peter Lawes

Tom J Slooff

Graham A Gie

Jacques J Vanderlinden

Lars Linder

A method of implanting an acetabular cup which includes the step of preparing an acetabular socket to receive a cup, placing cement in the acetabular socket before or after locating a tube in line with the acetabular socket and inserting the acetabular cup through the tube and into the socket.

Method and apparatus for implanting an acetabular cup

A prosthesis having attachment portion for insertion into or attachment to a patient's bone without bone cement. Parts of the attachment portion on the prosthesis are attached to the bone are covered with a mantle of synthetic resin material and which has a roughened outer surface with bone fragments or calcium phosphate fragments embedded therein.

Preformed mantle

An apparatus for performing hip prosthesis revision surgery includes means for preparation of the cavity left after removal of the original prosthesis. A tamp having a longitudinal passageway extending longitudinally through the stem portion thereof and a guidewire positioned in the cavity function to compact bone graft material in the cavity and form a precisely contoured new hip prosthesis receiving cavity.

System for performing hip prosthesis revision surgery

A tapered, collarless femoral hip joint prosthesis formed of Co-Cr-Mo alloy with highly polished surfaces is provided.

Femoral stem prosthesis

A total hip replacement femoral component has an outer surface shaped to conform to an acetabular socket and has an internal bore adapted to receive a femoral head. The head has been shaped and dimensioned to provide a spigot to enter the bore and be locked in place by a cement mantle between the bone and the walls of the bore. The head allows the hip component to move further over said spigot and re-lock should the cement creep or thereby any movement in the bone after assembly. The internal bore is inwardly tapered. Thus the taper can be co-axial with the femoral neck, but there may be advantages in orientating the axis of the taper as close to vertical as possible when in position so that it is closer to the average force vector acting on the femoral head during human activity.

Total hip replacement femoral component

A method and apparatus for performing hip prosthesis revision surgery includes preparation of the cavity left after removal of the original prosthesis. A tamp having a longitudinal passageway extending longitudinally through the stem portion thereof and a guidewire positioned in the cavity function to compact bone graft material in the cavity and form a precisely contoured new hip prosthesis receiving cavity.

An acetabular cup for use in a total hip prosthesis includes an implant/cement interface portion for location in a cement mantle. The cup has an enclosure element for allowing the cup to slide lengthwise to re-engage itself in the cement mantle to accommodate creep or movement thereof. Thus, should there be a tendency for the cup to become loose, the construction according to the invention is intended to relock the cup within the cement mantle. Thus, if the bone remodels, then the cement mantle will creep to re-adapt itself to the bone and the implant will re-engage in the cement mantle accommodating to the movement of the cement. If the bone cement is too highly stressed in places, it will creep in order to relieve this stress and the implant will re-settle.

Cemented taper lock acetabular cup

A bone implant assembly having an implant element whereof a stem portion is for insertion into a bone cavity, and wedge means for wedging between a proximal region of the cavity wall and the stem. The stem is tapered so that deeper insertion urges the wedge means against the wall. The wedge means may comprise lateral and medial wedges. Each may comprise a stem engaging portion with a low-friction surface, and an outer, wall engaging portion having a surface adapted for non-slip engagement, being a high friction surface and/or adapted for ingrowth of bone.

Fixation of implants in bone

A seal member for fitting over and sealing the opening of a cavity in a bone to allow pressurization of cement in the cavity has an aperture for sealingly receiving a cement delivery nozzle. The seal member may be a balloon seal, which may be inflatable and expandable, or a solid body of conformable material. In use, the seal member is urged against the opening, e.g. by force applied by the barrel of a cement delivery gun on an abutment means having an apertured pressure piece shaped to urge the seal member against the mouth of the opening.

Pressurization of cement in bones

An implant 22, e.g. for locating a hip prosthesis, is placed in the medullary canal 18 of a bone 20 (e.g. the femur) and secured by pressurized cement 24. A push-fit plug 10 prevents cement penetrating down the canal. The plug can be biodegradable so that in time it dissolves away and does not modify the flexural rigidity of the cement/bone system and the risk of fractures occurring at the level of the plug is reduced. Additionally or alternatively, the outwardly facing end portion 16 of the plug may be generally conical so that the thickness of the cement increases gradually and the flexural rigidity likewise changes gradually.

Plugs for the medullary canal of a bone

Surgical apparatus for locating a patient lying on his side to facilitate hip surgery by the so-called Southern approach comprises a first platform part to support the patient's lower hip, two posts upstanding from respectively opposite sides of this part to engage the patient about the rear and front of his pelvis, a second platform part extending from the first part to support the patient's lower leg, at least one further post upstanding from the second part, and a third platform part connected to the further post above the second part to support the patient's upper leg. Preferably the first posts are adjustable in mutually opening and closing manner, such posts are respectively shorter and longer, all posts are adjustable in height, and the third platform part is adjustably tilted.

Surgical apparatus

An endoprosthetic knee joint device is suited to a unicondylar procedure in which only one compartment of the knee is treated, or a duocondylar procedure, the latter employing a pair of like femoral components and a tibial component having a common platform defining separate recesses for similar pads. In addition the device maximizes the use of advantageous material properties, allows pad replacement in the event of wear, and allows pad thickness selection to correct for varus and valgus deformities.

Endoprosthetic knee joint

An endoprosthetic bone joint device developed for the elbow, but applicable elsewhere, has two hinge components respectively defining complementary first and second bearing surfaces for mutual articulatory engagement, and each apertured to define third bearing surfaces. When implanted the hinge components are first coupled by a further component passed through the apertures and defining fourth bearing surfaces to articulate with the third surfaces. At this stage all of the bearing surfaces are appropriately engaged and stabilization of the implantation securement is facilitated. Subsequently the coupling can be removed to reduce the effect of distraction stresses on the device. The first and second surfaces are suitably of spherical ball and socket form, and can be of a twinned form, while the third and fourth surfaces are suitably of circular cylindrical form extending diametrally through the ball and socket.

Endoprosthetic bone joint

An endoprosthetic femoral head device comprising a ball-shaped head connected, by way of a necked portion, to the wider end of a tapered intramedullary stem is modified to facilitate implantation involving detachment and re-attachment of the greater trochanter. The modification comprises the provision of a slot which extends longitudinally along the wider end of the stem, is open at one end, and has an interior width greater than that of its longitudinal mouth. A bolt-like member is adjustably located by its head in this slot with its shaft projecting from the device for passage through a bore formed in the detached trochanter. The trochanter is thus relocated and is secured by a fastener on the shaft free end. Preferably a spider-form washer with spring legs is located between the trochanter and fastener, and a screw-in plug is applied to the slot to positively locate the bolt head.

Growing community of inventors

Exeter, United Kingdom

Robin S Ling