Metabloc

One Instrument Set for Two Different AnchoragePhilosophies.

Metabloc™

Stem System

Product InformationSurgical Technique

Disclaimer

This document is intended exclusively for experts in the field, physicians in particular, and it is not intended for laypersons.

Information on the products and procedures contained in this document is of a general nature and does not represent medical advice orrecommendations. Because this information does not constitute any diagnostic or therapeutic statement with regard to any individualmedical case, examination and advising of the respective patient are absolutely necessary and are not replaced by this document in whole or in part.

Information contained in this document was gathered and compiled by medical experts and qualified Zimmer employees to the best oftheir knowledge. The greatest care was taken to ensure the accuracy and approachability of the information used and presented. Zimmerdoes not assume any liability, however, for the accuracy, completeness or quality of the information. Zimmer is not liable for tangible orintangible losses that may be caused by the use of this information.

3Metabloc Stem System – Product Information and Surgical Technique

Product InformationSurgical Technique

Metabloc Stem System

Table of Contents

Metabloc Stem Cemented and Uncemented 4

Metabloc Design 6

Preoperative Planning 7

Planning Stages 8

Operative Procedure 10

Postoperative Treatment 13

Example of a Cemented Metabloc Stem 14

Example of an Uncemented Metabloc Stem 15

Ordering information

Implants 16

Instruments without Rasp Handle 17

Rasp Handle 18

4 Metabloc Stem System – Product Information and Surgical Technique

Metabloc Stem Cemented and Uncemented

PhilosophyThe Metabloc system combines the characteristics of well-known hip re-placement designs which have proven themselves for many years and alsomeets the requirements of moderntotal hip arthroplasty. The stem isavailable in both cemented and unce-mented versions. It therefore coversa very broad range of indications.

The stem fills the metaphysis, ensuringproximal transmission of forces. The neck length and CCD angle increaseas the stem length increases. Thismeans that physiological conditionsare achieved in the hip joint asregards the lever arm.

The instruments are identical for both prostheses. The modular-shaped rasps are used as test stems. Thismakes instrumentation simpler andalso makes it possible to change overintraoperatively from cemented touncemented fixation and vice versa.


Fixation PrincipleThe Metabloc stem interlocks mainly inthe metaphysis thanks to its three-dimensional conical form. This producesa physiological transmission of forcesfor both stem versions. A gap of at least1 mm should remain between the stemand the cortex. This means that distalfixation is minimized with the unce-mented stem and a circular cement coatis obtained with the cemented stem.

IndicationsThe range of indications for the Metablocstem is considerably broader than forstem systems currently available. Thereasons for this are principally theoption of a cemented or uncementedversion, the proximal stem configurationand the wide range of sizes. The deci-sion on whether to use a cemented oruncemented prosthesis depends aboveall on the age, sex, cancellous bonequality and cortex index. The prosthesisis suitable for young and old patients. It can also be used for less severelydysplastic hips or in cases of revisionwhere there is still sufficient proximalbone stock.


Metabloc Design

• The proximal thickening with the rounded ribs ensures optimum distri-bution of forces in the cement coatand also a high degree of rotationalstability.

• The conical stem design producesself-centring in the medullary cavityas well as proximal interlocking. In this way, an undesirable varusposition can be avoided.

• The cemented stem is made of a forged steel alloy (FeCrNiMnMoNbN/Protasul®-S30) which was developedspecially for use with cement. Thenickel content is only about half thatof earlier alloys.

• The relatively high rigidity ofProtasul-S30 reduces unfavourabletension points in the cement coat.

• The surface of the prosthesis is finelyblasted. This ensures a good bondbetween the implant and the cement.

Cemented Metabloc Stem Uncemented Metabloc Stem

• The sharp-edged longitudinal ribs onthe proximal third of the stem becomeanchored deep in the metaphysealcancellous bone, thus guaranteeinggood primary stability.

• The ribs extend as far as the dia-physeal transition area, thus optimi-zing osseointegration. The tapering of the distal third of the stem preventscontact with the cortex. This preventsdistal transmission of forces.

• The prosthesis is made of a forgedtitanium alloy (Ti6Al7Nb/Protasul-100).This alloy has proven its value foruncemented implant fixation manytimes over the years.

• The coarse-blasted titanium surfacepromotes secondary implant fixationby means of osseointegration.

Metaphyseal structure of thecemented Metabloc stem

Shape of the ribs Metaphyseal structure of the uncemented Metabloc stem

Shape of the ribs

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Metabloc Stem cemented

Cone 12/14, CCD-Angle 132.5°

Ref.: 35.00.49-06. This reference number must correspond to that of the prosthesis

to be implanted. © All rights reserved, Zimmer GmbH, CH-8404 Winterthur, Switzerland

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Metabloc Stem uncementedCone 12/14, CCD-Angle 132.5°Ref.: 21.00.49-06. This reference number must correspond to that of the prosthesis to be implanted. © All rights reserved, Zimmer GmbH, CH-8404 Winterthur, Switzerland4/2003, Lit.No. 06.01102.000-WL

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Prosthetic TemplatesThe Metabloc stem planning templatesare drawn on the scale 1.15:1, corresponding to X ray magnification.Since the CCD angle and the length of the neck increase in line with increasing stem size in the Metablocdesign, there is a template for eachstem size.The prosthetic stem is shown along thephysiological axis of the femur relativeto the long axis of the body.The level of resection of the neck of thefemur (R) is drawn in at an angle of 45°to the stem’s axis. The heights of thecentre of the heads with short, medium,long and extra long neck lengths aremarked S, M, L and XL.The lateral view allows the fit in thesagittal plane to be checked on the lateral X ray of the femur.

Preoperative Planning

Planning templatecemented 06.01103.000

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Planning templateuncemented 06.01102.000

AimsPreoperative planning permits selection of the appropriate stem size and the correctposition of the femoral components. As soon as the anatomical acetabular cup centre and the height of the centre of the head have been determined, the centre ofrotation and leg length, which should be the same on both sides, can be established.If the cup centre is positioned higher for technical reasons to obtain fixation, the centre of the head must be raised to correspond. Operative planning is carried outusing prosthetic preoperative templates on a standard X ray of the pelvis.

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Metabloc Stem uncementedCone 12/14, CCD-Angle 132.5°Ref.: 21.00.49-06. This reference number must correspond to that of the prosthesis to be implanted. © All rights reserved, Zimmer GmbH, CH-8404 Winterthur, Switzerland4/2003, Lit.No. 06.01102.000-WL

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The planning stages are shown using the example of a case of unilateral osteoarthrosisin which the healthy hip serves as a reference side. The anatomical acetabular centre andthe height of the centre of the head are reconstructed.

Planning Stages

1. Determining the anatomicalcentre of the acetabulum and theheight of the centre of the headThe teardrop line and the perpendicularthrough the pubic symphysis (body’slong axis) are indispensible for planning.Using a circular template, the centre of rotation is determined in the healthyhip. The long axis of the femur on thehealthy side and the perpendicular to itat the level of the centre of the head arealso sketched in.The distance measured from the centreof rotation to the teardrop or teardropline are transferred to the hip to be oper-ated, thus establishing the anatomicalcentre of the acetabulum. The heightof the centre of the head is transferredin like manner.

2. Determining the stem sizeThe template of the probable stem sizeis laid over the femur to be operated,centring the stem in the medullarycavity and placing the M line at the levelof the sketched line marking the centreof the head. The stem size is correctwhen there is still a gap of about 1 mmbetween the stem outline and the medial margin of the diaphyseal cortex.

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Ref.: 35.00.49-06. This re

ference number must correspond to that of the prosthesis

to be implanted. © All rights re

served, Zimmer GmbH, CH-8404 Winterthur, Switzerland

4/2003, Lit.No. 06.01103.000-WL

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3. Drawing the prosthesis andthe femurA transparent drawing sheet is now laidover the template and the X ray film, the edge of which must be flush withthe long edge of the template. The outline of the prosthetic stem with theline of the centre of the head (M) andthe resection line for the neck of thefemur (R) and the outline of the femurare transferred to the drawing paper.

4. Drawing the pelvisThe drawing sheet is laid parallel to thebody’s long axis and the centre ofthe prosthetic head is placed over the sketched-in centre of the acetabulum.The outlines of the pelvis are now drawn in. At this stage of drawing, theselected cup is also tried anatomicallyfor size and entered on the planningsketch.

5. Final drawingAll of the information needed for theoperation (type and size of prostheticcomponents, measured distancesand possible bone grafting) is finallynoted on the planning sketch.The distances from the centre of thehead to the tip of the greater trochanterand from the level of resection or from the end of the cone to the base of the lesser trochanter are measuredusing the template gauge (1.15:1).

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Ref.: 35.00.49-06. This re

ference number must correspond to that of the prosthesis

to be implanted. © All rights re

served, Zimmer GmbH, CH-8404 Winterthur, Switzerland

4/2003, Lit.No. 06.01103.000-WL

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Operative Procedure

Femoral neck osteotomy 45° to stemaxis, slit-like opening of the medullarycavity with the gouge in about 10°–15°anteversion and sufficiently dorsolat-erally.

Prepare the medullary cavity with theawl as far as the corresponding mark(prosthetic size), using the tip of thegreater trochanter as reference point.

Widen the medullary cavity with shaped rasps in increasing order ofsize. Check anteversion. Drive in the rasps until the upper margin ot theteeth is at the level of resection. About 3 mm of cancellous bone shouldbe preserved between the rasp and the cortex. If rotational forces appliedon the rasp produce mobility betweenrasp and cancellous bone you can try to increase one rasp size to assurerasp torsional stability (respect3 mm of cancellous bone). Otherwise, in cases of less than 3 mm cancellousbone stock or osteoporotic bone, change strategy to cemented stem.

The removable trial neck is insertedinto the rasp. There are three differenttrial necks, according to the rasp size.

After the insertion of the trial neck,measure the distances from the end ofthe cone to the resection level and tothe base of the lesser trochanter.

Preparing the Medullary CavityThe Metabloc stem can be inserted via all operative approaches with the patient inthe supine or lateral position. The individual operative steps are shown below for the posterior approach with the patient in the lateral position. However, all of thetechnical details can be transferred analogously to other access routes.


Cemented Metabloc StemPut on the test head for trial reduction.Check the height of the centre ofthe head with a Kirschner wire. Checkthe range of movement, stability, soft tissue tension and leg length.

Extract the test prosthesis (shapedrasp). Insert the bone plug. After placing a suction drain, insert thecement using a silicone gasket.

Insert the stem and remove the suctiondrain at the same time. Remove the silicone gasket and gradually drive home the stem to the planned levelwhich has been confirmed by trialreduction.

Carefully clean the cone with water andgauze strips. Put on the head with arotary movement and lock it with a lightblow of the hammer on the reposition-ing lever.

Reduce the joint and check the functionof the components again. Wound clo-sure, suction drain.


Uncemented Metabloc StemPut on the test head for trial reduction.Check the height of the centre ofthe head with a Kirschner wire. Checkthe range of movement, stability, soft tissue tension and leg length.

Remove the test prosthesis (rasp). Insertthe prosthetic stem, parallel to the axis of the femur. Drive it in carefully withthe impactor and hammer. If there isany contact between the stem and thecortex, the awl should be used again.

Carefully clean the cone with water andgauze strips. Put on the head with arotary movement and lock it with a lightblow of the hammer on the reposition-ing lever.

Reduce the joint and check the functionof the components again. Wound clo-sure, suction drain.


There is no significant difference in aftercare between the cemented and the uncemented Metabloc stems.With the cemented fixation, full weight-bearing is possible after the wound hashealed. With the uncemented stem, avoidance of weight-bearing is advisable for two months so as not to interfere with osseointegration.During the rehabilitation period, assessment of the clinical course is indicated. X ray check-ups should later be done at intervals of 2 to 5 years.

Postoperative Treatment


Example of a Cemented Metabloc Stem

Preoperative. Bilateral osteoarthrosis with considerable restriction of function.

Postoperative. Metabloc stem cemented, Standard cup uncemented.


Preoperative. Unilateral osteoarthrosis with painful limitationof walking.

Postoperative. Uncemented total hip replacement: Metabloc stem, CLS cup.

Example of an Uncemented Metabloc Stem


Implants

L

Metabloc™ stem, cemented

FeCrNiMnMoNbNProtasul®-S30

Size Length REF

3 120 mm 35.00.49-034 126 mm 35.00.49-046 138 mm 35.00.49-068 150 mm 35.00.49-08

10 162 mm 35.00.49-1012 174 mm 35.00.49-1214 174 mm 35.00.49-14

Metabloc™ stem, uncemented

Ti6Al7NbProtasul®-100

Size Length REF

3 120 mm 21.00.49-034 126 mm 21.00.49-045 132 mm 21.00.49-056 138 mm 21.00.49-067 144 mm 21.00.49-078 150 mm 21.00.49-089 156 mm 21.00.49-09

10 162 mm 21.00.49-1011 168 mm 21.00.49-1112 174 mm 21.00.49-1213 174 mm 21.00.49-1314 174 mm 21.00.49-14

STERILE R STERILE R

L


Handle with quick couplingREF

75.00.25

Awl for 75.00.25Size REF

small 4–9 71.00.49-14medium 9–12 71.00.49-16large 12–14 71.00.49-18

Metabloc™ trial neckSize REF

3–5 01.00471.0156–8 01.00471.0169–14 01.00471.017

Metabloc™ modular raspSize REF

3 01.00472.0034 01.00472.0045 01.00472.0056 01.00472.0067 01.00472.0078 01.00472.0089 01.00472.009

10 01.00472.01011 01.00472.01112 01.00472.01213 01.00472.01314 01.00472.011

Repositioning leverREF

75.01.38Plastic top

REF

78.00.38

Repositioning top∅ mm REF

28 78.00.38-2832 78.00.38-32

Instruments without Rasp Handle

AwlREF

75.05.31

Boxed chiselREF

72.13.02-10

Extraction instrumentREF

75.85.75

Metabloc™ plastic tray (complete, butdoes not include rasp handle)

REF

ZS01.00479.911

Metabloc™ plastic tray (empty)REF

01.00479.902

Metabloc™ tray insert (empty)REF

01.00479.901

Standard tray cover greyREF

01.00029.031

Trial heads∅ mm Size REF

28 S 01.01559.12828 M 01.01559.22828 L 01.01559.32828 XL 01.01559.428

32 S 01.01559.13232 M 01.01559.23232 L 01.01559.33232 XL 01.01559.432


Plastic tray for rasp handle (empty)REF

01.06010.901

Standard tray cover greyREF

01.00029.031

Straight rasp handle with strike plateREF

01.00001.001

Long barREF

70.00.01

Double offset handle with strike plateREF

right 01.00001.002

Double offset handle with strike plateREF

left 01.00001.003

Rasp Handle

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