Biomet Assent

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TM



The Ascent™ Total Knee System is taking total knee replacement to new heights by

building on over twenty years of clinical experience. One thing has become clear in

total knee replacement: surgeons need and want several choices for their patients.

Surgeon choice is critical and may be the most important factor in long-term patient

satisfaction. Biomet responded to this need by combining its clinical experience,

extensive engineering resources, and the clinical experience of Rick Bassett, M.D.

and Michael Jacobs, M.D. The combination of these resources provides Biomet’s

surgeon customers with a clinically proven, user friendly system: the culmination of

experience from the most responsive company in orthopaedics. The goals of the

Ascent™ Knee System are to:

• Incorporate design features of proven Biomet knee designs

• Consistently restore function, stability and durability to the knee, thereby

meeting the needs of total knee patients today and tomorrow

• Provide instrumentation that allows reproducible results and offers the ability to

choose the level of constraint intraoperatively

• Develop new technology to further enhance total knee replacement into the

twenty-first century

The porous coated devices depicted in this brochure are marketed for use with bone cement

in the United States.

The Ascent™ system was designed in conjunction with Rick Bassett, M.D., Valley Baptist Hospital,

Harlingen, Texas; and Michael Jacobs, M.D., Good Samaritan Hospital, Baltimore, Maryland.

TM



Primary Cruciate Retaining Femorals

Retinacular Relief

On both the medial and lateral sides of the anterior flange, the Ascent™ femoral

component has the added benefit of retinacular relief. Retinacular relief is achieved

by streamlining the anterior sides of the component. The retinaculum must travel

over the sides of the femoral component for the patella to sit within the femoral

groove. By reducing the distance the retinaculum has to travel, the Ascent™

minimizes the need for lateral releases.

Swept-Back Femoral Design

The swept-back design of the component offers

tremendous advantages to both the quadriceps

mechanism and the patella. Several authors

maintain that “less boxy” designs provide a

smoother transition for the patellar

component as the knee goes into

flexion.1 The ease of transition may

result in fewer patellar clunks, less

patellar wear, and a reduction in soft

tissue impingement.



Deep Patellar Groove

Much has been said about the design of a femoral

component and its effects on patellar perfor-

mance. The Ascent™ femoral component

maintains a deep patellar groove. A deep patellar

groove coupled with a true dome patellar

articulation helps decrease stresses on the patella

by improving patellar tracking, and dispersing

stress over a large contact area.

Optimal Range of Motion

By design, the Ascent™ knee specifically addresses range of motion. The Ascent™

knee offers a tighter posterior proximal radius, this allows easier rollback and provides

up to an additional 10 degrees of flexion.2



(Amount of Bone Removed)

Cruciate Substituting Femorals

Posterior Stabilized Constrainable Femurs

The Ascent™ Posterior Stabilized System offers a

tremendous amount of intraoperative flexibility.

This system allows the surgeon to progress from a

posterior stabilized to a constrained device

simply by changing the tibial bearing. The

surgeon is not required to make any additional

bone resection when converting to the

constrained bearing.

Box Volume

The Ascent™ open and closed box P/S femoral components have a significantly

smaller box volume in comparison to other competitive designs, minimizing bone

removal (Figure 1). The polyethylene P/S tibial spine does not protrude above the

top of the open P/S box. Many competitive designs use what appears to be a very

small P/S femoral box. However, significant amounts of bone must be removed to

accommodate the tibial spine.

Figure 1



Stability

In cruciate sacrificing knees, the height required

for the P/S Femoral Cam to jump over the P/S Post

is referred to as the “hop height.” The Ascent™

knee has a hop height of 18.5mm at 90 degrees

of flexion. A notable feature for the Ascent™

knee is that it maintains its hop height at deep

flexion angles where dislocations occur (Figure 2).5

Interchangeability

The condylar radius makes the Ascent™

posterior stabilized design fully interchangeable.

All posterior stabilized femoral components

articulate with all posterior stabilized tibial

components, providing full flexibility and

optimal bone coverage.

All posterior stabilized femoral components interchange withall posterior stabilized tibial components.

Figure 2



Tibial Trays

Biomet’s tibial plate coverage is designed to

accommodate a wide range of bone sizes based on

the work of Mensch and Amstutz. The geometry

of the nine sizes utilizes the best available bone

on the tibial plateau, while offering uniform

distribution of tibio-femoral forces.

Plate Options

Primary tibial trays are made from both titanium and cobalt chrome alloys. Titanium

baseplates come either with an Interlok® finish or a titanium porous plasma sprayed.

Porous plasma sprayed baseplates accept up to four 6.5mm cancellous bone screws.

Both the porous and stemmed tibial plates can be used with block or wedge aug-

ments. All augments are fixed to the baseplates via screws. Cobalt chrome baseplate

options come in either fixed I-beam or fixed cruciate fin with an Interlok® finish.

Stem Options

The modular primary tray provides for the intraoperative selection of the stem to

match the specific needs of the patient. The combination of a Morse-type taper and

screw fixation helps maintain a solid connection between the stem and plate.

Various primary stem options meet specific patient needs.

Tibial augmentation blocks and wedges are available for theporous and stemmed trays. Canal filling and long stemextensions are available for the stemmed tray.

Based on the work of Mensch andAmstutz, a broad range of tibial sizescovers virtually any requirement.



Compressive Locking Mechanism

Since 1989, Biomet’s locking bar has been clinically utilized and confirmed as a truly

reliable locking mechanism. Unlike snap-in designs, Biomet’s system features a

unique slide-in bar that compresses the polyethylene within the locking mechanism,

and reduces micromotion between the plate and polyethylene. Maximum polyethyl-

ene thickness is maintained at the periphery due to intercondylar placement of the

locking mechanism.Locking bar generates a compressivepolyethylene fit onto the tibial plate while

obtaining consistent bearing edge thickness.



ArCom® Polyethylene

Wear

Knee wear is predominantly a fatigue mecha-

nism, which may lead to delamination and

pitting of the bearing surface. Direct compression

molded devices using 1900H raw polyethylene

have demonstrated clinically superior resistance

to this type of breakdown.1 With traditional

machining, stresses are created near the surface

of the component. The cutting tool shears the

polyethylene and pulls the material apart,

creating a region of residual stress. The residual

stress may sensitize the material to localized

breakdown and oxidation. Oxidation may

negatively impact the fatigue characteristics of

Argon Packaged: Compression Molded

+ =

+ =

Extruded Bar Stock Machining Oxidized Cross-Section

1900H Resin Direct Molding Non-Oxidized Cross-Section

the polyethylene, causing delamination. Since delamination is a major concern in

total knees, Biomet has made the commitment to direct compression mold the

Ascent™ tibial bearings to minimize the potential for wear and oxidative breakdown.

ArCom® polyethylene is tailored to address the specific wear mechanisms found in

total knee replacement.



Controlling oxidation is an important aspect in theperformance of tibial bearings. Machining operations are amajor source of stress and need to be considered to controloxidation before sterilization. Ascent™ tibial bearings aredirect molded out of 1900H Resin to minimize the potentialfor wear and oxidation breakdown.4



Revision

The Ascent™ Knee System addresses the

complex bone defects that revision cases often

present. With various modular options, the surgeon

has the ability to customize the implant to fit

patient needs. Multiple stem lengths and diameters,

along with femoral condylar augmentation and

tibial wedges, are available—maximizing the

ability to address bone defects. The intraopera-

tive flexibility is enhanced with the option of a

posterior stabilized or constrained bearing

depending on collateral deficiency. Additionally,

the surgeon is able to choose either a five or

seven degree femoral valgus angle for correct

placement within the femoral canal.



Instrumentation

Precise, simple instrumentation enables the

surgeon to achieve optimal component position.

Optimal component position establishes balance

and appropriate tension which subsequently

improves function and increases longevity. The

Ascent™ instrumentation enhances function

and longevity through design, accuracy and

simplicity. This user-friendly instrumentation also

provides the flexibility to change from a cruciate

retaining to a posterior stabilized or constrained

knee within a single integrated system. The

instrumentation is easily understood by the scrub

team and central supply. Efficient and user

friendly, Ascent™ instrumentation prevents

confusion and serves to decrease operative time.

TM



The Family

AGC®•Maxim®•FINN®•Ascent™

THE COMPLETE KNEE SYSTEM

Finn®

Knee

TM



P.O. Box 587, Warsaw, IN 46581-0587 • 219.267.6639 • ©1999 Biomet, Inc. All Rights ReservedWeb site: http://www.biomet.com • eMail: [email protected]

Form No. Y-BMT-631/103199/M

References

1

Beadling, Lee; “Direct-Molded Components Shown to Resist Oxidation,” Orthopaedics Today,Vol. 17, No. 4, April 1997 [Citing Furman B., Li S., and Ritter M.].

2Basset, Rick W.; “Results of 1,000 Performance Knees—Cementless Versus Cemented Fixation,” Journal of Arthroplasty , pp. 409–413 Vol. 13, No. 4, 1998.

3Data on file at Biomet.

4Data on file at Biomet.

5Robinson, R.P., M.D.; Striplin, D.B., M.D.; “Posterior Dislocation of the Insall/Burstein IIPosterior Stabilized Total Knee Prosthesis,” The American Journal of Knee Surgery, pp. 79–83 Vol.5, No. 2, Spring 1992.

ArCom®, Ascent™, Finn®, Interlok® and T-1™ are trademarks of Biomet, Inc.

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