Operative Technique

2.0mm & 3.0mm

Asnis MicroCannulated Screw System

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This Operative Technique sets forth detailed recommended procedures for using Stryker Osteosynthesis devices and instruments. It offers guidance that should be followed, but, as with any technical guide, each surgeon must consider the particular needs of each patient and make appropriate adjustments as required.

Note: The bone screws referenced in this Operative Technique are not approved for screw attachment or fixation to the posterior elements (pedicles) of the cervical, thoracic or lumbar spine.

1. Introduction 3

2. Features & Benefits 4

3. Examples of Applications & Relative Contraindications 5

5. Operative Technique

5.1 Asnis Micro General Considerations 6

5.2 Austin/Chevron Osteotomy 9

5.3 Extraction 14

6. Ordering Information 15

Table of Contents

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Cannulated Screws have a long, proven clinical history in Orthopaedic surgery. Along with the arthroscope and image intensifier, cannulated screws have been a major facilitator of minimally invasive surgery. Extensive surgical exposure of bone fragments and intensive soft tissue stripping have been changed to a minimally invasive percutaneous procedure.

The Asnis Micro 2.0mm and 3.0mm cannulated titanium screws dedicated for foot and hand surgery offer an effective solution for trauma and reconstructive indications. The Asnis Micro System is designed to facilitate surgical procedures by simplifying screw placement, insertion and removal.

Small screw diameters, combined with low profile screw heads and the advanced cutting characteristics of the Asnis Micro Cannulated Screws are combined to meet the surgeons' needs in their daily practice.

These important features make the Asnis Micro the system of choice.

Introduction

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2.0mm and 3.0mm Diameters developed to meet the special needs of foot and hand surgeons

Low Profile Screw Heads specially designed for reduced potential of soft tissue irritation

Type III Anodization implants with Colour Coding for better distinction in the O.R.

Equal Shaft and Core Diameters developed for minimization of stress risers

Reverse Cutting Flutes to facilitate implant removal

Self Cutting Screw Design with an efficient cutting tip to improve insertion properties

Features and Benefits

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Relative Contraindications

Examples of Applications

Note:For additional information we refer to the Instruction For Use (IFU), Ref.-No. 90-01971 delivered with each implant and IFU, Ref.-No. 90-01972 delivered with each instrument.

• Fractures of the Phalanges, Metatarsals, Tarsals and Ankle

• Fractures of the Phalanges, Metacarpals, Carpals and Distal Radius

• Fractures of the Patella• Corrective Osteotomies of the Fore-

, Mid- and Hind Foot and the Hand• Arthrodeses in the Fore-, Mid- and

Hind Foot• Ligament Fixation

The physician’s education, training and professional judgement must be relied upon to choose the most appropriate device and treatment option.

The Asnis Micro 2.0mm and 3.0mm Cannulated Screws are designed for fixation of fracture fragments, intra-articular fractures and fixation of osteotomy sites in the hand and foot.

• Compromised vascularity that would inhibit adequate blood supply to the fracture on the operative site

• Any active or suspect latent infection or marked local inflammation in or about the affected area

• Material sensitivity documented or suspected

• Patients having inadequate tissue coverage over the operative site

• Bone stock compromised by diseases, infection or prior implantation that can not provide adequate support and/or fixation

• Implant utilization that would interfere with anatomical structures or physiological performance

• An overweight or obese patient can produce loads on the implant which can lead to failure of the fixation or to failure of the device itself

• Any mental or neuromuscular disorder which could create an unacceptable risk of fixation failure or complications in postoperative care

• Other medical or surgical conditions which would preclude the potential benefit of the surgery.

Indications & Contraindications

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Guide Wire Insertion

Insert the K-Wire using the Double Drill Guide at the entry point of the final screw placement to the appropriate depth. Use the image intensifier to control reduction and K-Wire placement.

Note:In case of dense cortical or pediatric bone, puncture the proximal cortex before inserting the K-Wire, by using the solid drill bit manually or by power according to the screw diameter chosen.

Countersinking of the Screw Head (Optional Step)

Where soft tissue coverage is minimal, the option for countersinking the screw head for further recess of the low profile screw head may be used.

Assemble the Elastosil Handle with the Cannulated Countersink by pushing the sleeve towards the tip, inserting the Countersink Head and releasing the sleeve.

Note:Pre-drilling is not required for this step.

Washers

In osteoporotic bone or where the cortex is thin, Washers may be placed under the screw head in order to spread the load over a bigger area. After countersinking Washers can not be used.

Apply the Countersink over the K-Wire and prepare the bone for countersinking by turning the instrument clockwise.

To disassemble the Cannulated Countersink push the sleeve forward and remove the tip.

Operative Technique

Asnis Micro General Considerations

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Measurement of the Screw Length

Slide the Direct Measuring Gauge over the K-Wire and position it in direct contact with the bone.

The end of the K-Wire against the Direct Measurement Gauge scale provides a direct reading of the correct screw length.

Note:The Direct Measurement Gauge measures directly to the tip of the K-Wire. This ensures that the final screw position corresponds with the initial tip position of the K-Wire.

It is recommended to subtract 1-2mm from the measurement to avoid potential penetration or damage of the articular surface.

When Washers are used, the hight of the implant needs to be considered for the overall screw length.

Pre-Drilling (Optional Step)

In case of hard cortical or pediatric bone, pre-drilling can be used. Insert the Cannulated Drill Bit according to your screw diameter into a power or manual cannulated drill. Slide it over the K-Wire and overdrill the K-Wire to its tip by using the Double Drill Guide.

Optionally the Solid Drill may be used without the use of a K-Wire.

Note:In order to avoid damaging the K-Wire use low speed or a manual drill.

Operative Technique

Asnis Micro General Considerations

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Screw Insertion

To prepare for insertion place the screw over the K-Wire onto the bone and draw the Holding Sleeve towards the handle, so that the screw head is visible.

Insert the screw over the K-Wire by turning the screwdriver clockwise.

After final insertion remove the screwdriver from the screw and verify the K-Wire and screw position with the image intensifier.

After the positions have been verified remove and discard the K-Wire.

Screw Insertion Set Up

Assemble the Cannulated Screwdriver onto the Elastosil Handle as described for the Cannulated Countersink on page 6.

Take the Holding Sleeve and slide it over the Cannulated Screwdriver until it engages.

Pull the sleeve towards the handle so that the tip of the screwdriver is visible.

Place the screwdriver into the chosen screw, push the sleeve forward and take the screw securely out of the rack.

Optionally screws may also be taken from the screw rack by using the Screw Foreceps.

To remove the Holding Sleeve compress the bushing. The entire Holding Sleeve can now be removed from the Screw Driver.

Operative Technique

Asnis Micro General Considerations

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Bone Preparation

Make a dorsal medial skin incision crossing the first Metatarsal Phalangeal Joint. Retract the soft tissues carefully, being certain to protect the neuro vascular bundle in the skin flap.

Perform a lateral release if necessary through the same incision. This would include the release of the adductor tendon and the fibular sesamoidal ligament.

Note:Be aware of the superficial branch of the deep peroneal nerve.

Resect the medial eminence, with protection of the sagittal groove.

Perform a t-shaped incision of the capsule thus exposing the joint.

Operative Technique

Austin / Chevron Osteotomy

10

Osteotomy

Perform a V-shaped osteotomy at the head-neck level at an angle of 60°, with the apex at the K-Wire.

Translate the capital fragment laterally.

60°

Note:The head will follow the direction which is predetermined by the K-Wire placement.

Insert the K-Wire in the center of the metatarsal head depending on the required osteotomy.

Operative Technique

Austin / Chevron Osteotomy

11

Note:Pre-drilling is not required for this step.

Washers

In osteoporotic bone or where the cortex is thin, Washers may be placed under the screw head in order to spread the load over a bigger area.

After countersinking Washers can not be used.

Guide Wire Insertion

Place the K-Wire for the screw in the appropriate position aiming at the center of the metatarsal head.Insert the K-Wire through the metatarsal head until the tip is visible and then retract it slightly so that the tip is below the level of articular cartilage.

Assemble the Cannulated Countersink by pushing the sleeve towards the tip, inserting the Cannulated Countersink and releasing the sleeve.

Countersink of the Screw Head (Optional Step)

Where soft tissue coverage is minimal, countersinking may be considered.

Apply the Countersink over the K-Wire and prepare the bone for countersinking by turning the instrument clockwise

Note:In case of dense cortical bone, puncture the cortex before inserting the K-Wire, by using the drill bit manually or by power according to the screw diameter chosen.

Operative Technique

Austin / Chevron Osteotomy

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Note:The Direct Measurement Gauge measures directly to the tip of the K-Wire. This ensures that the final screw position corresponds with the initial tip position of the K-Wire.

It is recommended to subtract 1-2mm from the measurement to avoid potential penetration or damage of the articular surface.

When Washers are used, the hight of the implant needs to be considered for the overall screw length.

Pre-Drilling (Optional Step)

In case of hard cortical bone, pre-drilling can be used.Insert the cannulated drill bit according to your screw diameter into a power or manual cannulated drill. Slide it over the K-Wire and overdrill the K-Wire to its tip by using the Double Drill Guide.

Optionally the Solid Drill may be used without the use of a K-Wire.

Note:In order to avoid damaging the K-Wire use low speed or a manual drill.

Measurement of the Screw Length

Slide the Direct Measuring Gauge over the K-Wire and position it in direct contact with the bone. The end of the K-Wire against the Direct Measurement Gauge scale provides a direct reading of the correct screw length.

Operative Technique

Austin / Chevron Osteotomy

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Screw Insertion

To prepare for insertion, place the screw over the K-Wire onto the bone and draw the Holding Sleeve towards the handle so that the screw head is visible.

Insert the screw over the K-Wire by turning the instrument clockwise.

After final insertion remove the screwdriver from the screw and verify the K-Wire and screw position with the image intensifier.

After the positions have been verified remove and discard the K-Wire.

Resect the remaining head and neck prominence in a parallel plane to the medial border of the foot.

Screw Insertion Set Up

Assemble the Cannulated Screwdriver onto the Elastosil Handle as described for the Cannulated Countersink on page 6.

Take the Holding Sleeve and slide it over the Cannulated Screwdriver until it engages.

Pull the sleeve towards the handle so that the tip of the screwdriver is visible.

Place the screwdriver into the chosen screw, push the sleeve forward and take the screw securely out of the rack.

Operative Technique

Austin / Chevron Osteotomy

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Holding Sleeve Support

In case of difficult screw extraction due to bone quality, the Holding Sleeve in combination with the Solid Drill can be used as a support for lifting and turning the screw.

Operative Technique

Extractor

If a screw head has been sheared off, the Extractor may be used to remove the screw shaft.

Note:The Extractor may be used for 2.0mm and 3.0mm Asnis Micro screws.

Assemble the Extractor onto the Elastosil Handle as shown on page 6 and place the Extractor into the screw shaft.

Turn the instrument counter-clockwise to remove the remaining screw.

Extraction

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Ref.-No. Total Length Thread Length

40-30108

40-30109

40-30110

40-30111

40-30112

40-30113

40-30114

40-30214

40-30115

40-30215

40-30116

40-30216

40-30117

40-30217

40-30118

40-30218

40-30119

40-30219

40-30120

40-30220

40-30121

40-30221

40-30122

40-30222

40-30123

40-30223

40-30124

40-30224

40-30125

40-30225

40-30126

40-30226

40-30127

40-30227

40-30128

40-30228

40-30129

40-30229

40-30130

40-30230

40-30132

40-30232

40-30134

40-30234

40-30136

40-30236

40-30138

40-30238

40-30140

40-30240

8mm

9mm

10mm

11mm

12mm

13mm

14mm

14mm

15mm

15mm

16mm

16mm

17mm

17mm

18mm

18mm

19mm

19mm

20mm

20mm

21mm

21mm

22mm

22mm

23mm

23mm

24mm

24mm

25mm

25mm

26mm

26mm

27mm

27mm

28mm

28mm

29mm

29mm

30mm

30mm

32mm

32mm

34mm

34mm

36mm

36mm

38mm

38mm

40mm

40mm

�.0mm Asnis Micro Cannulated Screw

Ref.-No. Total Length Thread Length

40-20108

40-20110

40-20111

40-20112

40-20113

40-20114

40-20115

40-20116

40-20117

40-20217

40-20118

40-20218

40-20119

40-20219

40-20120

40-20220

40-20122

40-20222

40-20124

40-20224

40-20126

40-20226

40-20128

40-20228

40-20130

40-20230

8mm

10mm

11mm

12mm

13mm

14mm

15mm

16mm

17mm

17mm

18mm

18mm

19mm

19mm

20mm

20mm

22mm

22mm

24mm

24mm

26mm

26mm

28mm

28mm

30mm

30mm

�.0mm Asnis Micro Cannulated Screw

4mm

4mm

5mm

5mm

6mm

6mm

6mm

7mm

5mm

8mm

5mm

8mm

5mm

9mm

5mm

9mm

5mm

10mm

6mm

10mm

6mm

12mm

6mm

12mm

6mm

14mm

4mm

4mm

4mm

4mm

4mm

4mm

4mm

6mm

4mm

7mm

4mm

7mm

4mm

8mm

5mm

8mm

5mm

9mm

5mm

9mm

5mm

9mm

5mm

10mm

5mm

10mm

6mm

10mm

6mm

10mm

6mm

12mm

6mm

12mm

6mm

12mm

6mm

12mm

6mm

14mm

6mm

14mm

7mm

16mm

7mm

16mm

8mm

18mm

8mm

18mm

Ref.-No.

40-20900

�.0mm Asnis Micro Washer

Ref.-No.

40-30900

�.0mm Asnis Micro Washer

Ordering Information – Implants

Special Order

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45-20001

45-20004

45-20005

45-20011

45-20006

45-20007

45-20008

45-20009

45-20014

45-20015

45-30001

45-30004

45-30005

45-30011

45-30006

45-30007

45-30008

45-30009

45-30014

45-30015

Cannulated Screwdriver 2.0 mm, AO Coupling

Solid Screwdriver, 2.0mm, AO Coupling

Cannulated Drill 1.7 mm, AO Coupling, Single Use

Solid Drill 1.7mm, AO Coupling

Cannulated Tap 2.0 mm, AO Coupling, Single Use

Cannulated Countersink 2.0mm, AO Coupling, Single Use

Holding Sleeve for 2.0mm Screws

Double Drill Guide 0.8/1.7mm

Cleaning Stylet 0.8mm

K-Wire 0.8 mm x 100 mm, Single Use

Cannulated Screwdriver 3.0 mm, AO Coupling

Solid Screwdriver 3.0mm, AO Coupling

Cannulated Drill 2.1mm, AO Coupling, Single Use

Solid Drill 2.1mm, AO Coupling

Cannulated Tap 3.0 mm, AO Coupling, Single Use

Cannulated Countersink 3.0mm, AO Coupling, Single Use

Holding Sleeve for 3.0 mm Screws

Double Drill Guide 1.2/2.1mm

Cleaning Stylet 1.2mm

K-Wire 1.2 mm x 100 mm, Single Use

REF Description

2.0mm Asnis Micro Instruments

3.0mm Asnis Micro Instruments

Ordering Information - Instruments

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45-90010

45-90020

45-90200

900106

29-32400

29-32000

29-32010

29-35000

29-35200

Asnis Micro, Direct Measuring Gauge 0.8/1.2 mm

Extractor for Asnis Micro

Asnis Micro Elastosil Handle, AO Coupling

Screw Forceps

Tray for Asnis Micro 2.0 and 3.0 System

Screw Rack for Asnis Micro 2.0mm/3.0mm Screws (including Lid)

Lid for Asnis Micro Screw Rack

Container „Stryker Foot Solutions“ (3 Levels without Lid)

Lid for Asnis Micro 2.0 and 3.0 System (Container Lid)

REF Description

Asnis Micro Generic Instruments

Ordering Information - Instruments

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Notes

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Notes

Biologics

Surgical Products

Neuro & ENT

Trauma, Extremities & Deformities

Biologics

Surgical Products

Neuro & ENT

Trauma, Extremities & Deformities

Stryker Leibinger GmbH & Co. KGBötzinger Strasse 39-41D-79111 FreiburgGermany

www.osteosynthesis.stryker.com

The information presented in this brochure is intended to demonstrate a Stryker product. Always refer to the package insert, product label and/or user instructions before using any Stryker product. Surgeons must always rely on their own clinical judgment when deciding which products and techniques to use with their patients. Products may not be available in all markets. Product availability is subject to the regulatory or medical practices that govern individual markets. Please contact your Stryker representative if you have questions about the availability of Stryker products in your area.

Stryker Corporation or its subsidiary owns the registered trademark: Stryker Stryker Corporation or its subsidiary owns, uses or has applied for the following trademarks: AsnisTM Micro Wacker-Chemie GmbH owns the following trademark: ElastosilLiterature Number : 90-17001LOT A122007

Copyright © 2007 StrykerPrinted in Germany