Read 4.0 mm Cannulated Screw Technique Guide text version

4.0 mm Cannulated Screw

Technique Guide

An Integral Part of the SYNTHES Cannulated Screw System

Original Instruments and Implants of the Association for the Study of Internal Fixation -- AO ASIF

The 4.0 mm Self-drilling, Self-tapping Cannulated Screw

Features

· Cannulated shaft accepts 1.25 mm diameter guide

1.25 mm guide wire 5.1 mm diameter low-profile head with 2.5 mm hex drive Spherical underside

wires (threaded and non-threaded wires available).

· Hemispherical head ensures optimal annular contact

with washers and Synthes plates when screws are angled.

· Low-profile head reduces possibility of soft tissue irritation. · Standard 2.5 mm hexagonal drive is compatible with

2.6 mm diameter shaft

screwdrivers in other commonly used Synthes sets.

· Reverse-cutting flutes assist in screw removal. · Choice of thread lengths offers best fit of threads into far

Reverse-cutting flutes

bone fragment, for greater interfragmentary compression.

· Cancellous thread profile uses deep cutting threads

with a large pitch to increase resistance to pullout. The large pitch also accelerates screw insertion and removal.

· Self-drilling, self-tapping screw tip facilitates screw

Cancellous thread profile Self-drilling, self-tapping flutes

insertion by eliminating the need for predrilling and tapping in most cases.

Thread Lengths

Materials

Short thread (thread length = 1/3 screw length)

Long thread (thread length = 1/2 screw length)

Implant quality 316L stainless steel

Titanium alloy Ti-6Al-7Nb

Indications

For fracture fixation of small bones and small bone fragments, such as:

· Fractures of the tarsals

and metatarsals

· Metatarsal and phalangeal

osteotomies

· Tarsometatarsal and

metatarsophalangeal arthrodeses

· Osteochondritis dissecans · Ligament fixation · Other small fragment,

cancellous bone fractures

Hallux valgus corrections

Metatarsophalangeal arthrodeses

Metatarsal and phalangeal osteotomies

Warning: This device is not approved for screw attachment or fixation to the posterior elements (pedicles) of the cervical, thoracic or lumbar spine.

1

AO Principles

In 1958, the AO ASIF (Association for the Study of Internal Fixation) formulated four basic principles, which have become the guidelines for internal fixation:

Anatomic Reduction

A guide wire marks the prescribed path for the cannulated screw and secures alignment of the fragments while the screw is being inserted. The cannulated screw is inserted over the wire and tightened to further compress the fragments and hold the reduction.

Stable Fixation

Cannulated screws provide interfragmentary compression and absolute stability across the fracture. The screws are available in different threads lengths, allowing the surgeon to optimize purchase in the far fragment for maximum compression and stability.

Preservation of Blood Supply

The use of small diameter guide wires allows precise placement of cannulated screws through small incisions. This technique minimizes disruption of soft tissue and preserves vascular blood flow for bone healing.

Early Mobilization

Cannulated screws, combined with AO technique, provide stable fracture fixation with minimal trauma to vascular supply. This helps to create an improved environment for bone healing, accelerating the patient's return to previous mobility and function.

2

Surgical Technique

Technique Tips

Cleaning Cannulations

Cleaning the cannulation in each instrument is imperative for proper function. Instruments should be cleared intraoperatively with the 1.25 mm Cleaning Stylet [319.38] to prevent accumulation of debris in the cannulation and potential binding of the instruments about the guide wire. Instruments should be cleaned postoperatively with both the stylet and 1.35 mm Cleaning Brush [319.25].

Drilling and Tapping

The self-drilling, self-tapping flutes of the 4.0 mm Cannulated Screw make predrilling and pretapping unnecessary in most cases. The sets include 2.7 mm Cannulated Drill Bits and a Cannulated Tap for use in dense bone, if needed.

2.7 mm/1.25 mm Double Drill Sleeve 312.35

Handle 311.43

1

Insert guide wire

Insert a 1.25 mm Guide Wire through the 2.7 mm/ 1.25 mm Double Drill Sleeve to the appropriate depth. Check placement of wire under image intensification. Remove the drill sleeve.

Cannulated Countersink 310.86

2

Countersink (optional)

In areas where soft tissue coverage is minimal, use the Cannulated Countersink to create a recess for the screw head. Countersinking will also facilitate screw insertion.

Note: In dense bone, if countersinking is not required, it may be helpful to use a 2.7 mm Cannulated Drill Bit [310.67] to penetrate the near cortex prior to screw insertion.

3

Surgical Technique (continued)

3

Measure for screw length

Cannulated Screw Measuring Device 319.15

Slide the tapered end of the Cannulated Screw Measuring Device over the guide wire, down to the bone. Read the scale at the end of the guide wire to determine appropriate screw length. This reading will place the screw 5 mm short of the tip of the guide wire, allowing the threaded portion of the guide wire to remain in the bone during screw insertion.

Example: If the reading indicates 34 mm, use a 34 mm screw to place the screw 5 mm short of the wire tip. Note: If countersinking, this should be done prior to measuring for screw length.

4

Insert the screw

Place the appropriate length screw over the guide wire. Use the Cannulated Hexagonal Screwdriver and Holding Sleeve to insert the screw. Remove and discard the guide wire.

Note: Power insertion of screws without use of the Holding Sleeve increases the risk of stripping the hex recess. If power insertion is preferred, use the Cannulated Hexagonal Screwdriver Shaft [314.10] and Holding Sleeve. Note: In osteoporotic bone, a washer may be used to prevent the screw head from sinking into the bone.

Cannulated Hexagonal Screwdriver 314.29

Holding Sleeve 314.08

4

4.0 mm Cannulated Screw Instrument and Implant Sets

Synthes offers the following 4.0 mm Cannulated Screw Instrument and Implant sets:

· 4.0 mm Cannulated Screw Instrument and Implant Set [105.135] · 4.0 mm Titanium Cannulated Screw Instrument and Implant Set [145.135] · 3.5 mm/4.0 mm Cannulated Screw Combined Instrument and Implant Set [105.14]

Graphic Cases

Each set includes a graphic case that houses and organizes all of the set's implants and instruments in order to facilitate surgery, sterilization and inventory control. The graphic case also provides space for some of the most common "Also Available" instruments and implants. Screw racks are removable to enable separate sterilization of implants, and replacements can be ordered separately or as part of the graphic case. Set Description: 4.0 mm Cannulated Screw Instrument and Implant Set [105.135] 4.0 mm Titanium Cannulated Screw Instrument and Implant Set [145.135] 3.5 mm/4.0 mm Cannulated Screw Combined Instrument and Implant Set [105.14] Graphic Case: 690.337 690.351 304.300 Screw Rack: 690.337.50 690.351.50 304.213 (3.5 mm) 304.313 (4.0 mm)

5

Implants

Stainless Steel Titanium

4.0 mm Cannulated Screws, short thread [207.610 ­ .650] 10 mm­50 mm lengths, 2 mm increments, thread length 1/3 screw length

4.0 mm Titanium Cannulated Screws, short thread [407.610 ­ .650] 10 mm ­50 mm lengths, 2 mm increments, thread length 1/3 screw length

Washer, 7.0 mm [219.98] To prevent screw head from sinking into osteoporotic bone

Titanium Washer, 7.0 mm [419.98] To prevent screw head from sinking into osteoporotic bone

Also Available

4.0 mm Cannulated Screws, long thread [207.716 ­ .750] 16 mm­50 mm lengths, 2 mm increments, thread length 1/2 screw length

4.0 mm Titanium Cannulated Screws, long thread [407.716 ­ .750] 16 mm­50 mm lengths, 2 mm increments, thread length 1/2 screw length

6

Instruments

Included in both stainless steel and titanium sets

1.25 mm Threaded Guide Wire, 150 mm [292.62] Maintains reduction during drilling. Threaded spade point tip allows easy penetration into the bone and maximum resistance to inadvertent removal. See "Also Available" on last page for other 1.25 mm guide wires.

Cannulated Screw Measuring Device [319.15] Provides a direct reading for screw length. Measurement places screw tip at thread/shaft junction of guide wire.

2.7 mm Cannulated Drill Bit [310.67] 160 mm, 1.35 mm cannulation, quick coupling.

2.7 mm/1.25 mm Double Drill Sleeve [312.35] Protects soft tissue during guide wire placement and drilling.

310.86

311.43

Cannulated Countersink [310.86] Cuts a recess for the screw head. Quick-connects to Handle, with quick coupling [311.43].

311.63

311.43

Cannulated Tap for 4.0 mm Cannulated Screws [311.63] Allows precise tapping in dense bone, when necessary; 147 mm/60 mm.* Quick-connects to Handle, with quick coupling [311.43].

* Total length/tap depth

7

Instruments (continued)

Included in both stainless steel and titanium sets

Holding Sleeve 314.08

314.29

Cannulated Hexagonal Screwdriver, 2.5 mm hex [314.29] Fully cannulated for insertion of any 4.0 mm Cannulated Screw over the guide wire. Accommodates Holding Sleeve [314.08].

Small Hexagonal Screwdriver Shaft, 2.5 mm hex [314.03] Recommended for removal of 4.0 mm Cannulated Screws, connects to Handle, with quick coupling [311.43].

Screw Forceps [319.97]

1.25 mm Cleaning Stylet [319.38] For intraoperative clearing of 4.0 mm Cannulated Screw instruments.

1.35 mm Cleaning Brush [319.25] For postoperative cleaning of 4.0 mm Cannulated Screw instruments.

8

Set Contents

4.0 mm Cannulated Screw Instrument and Implant Set [105.135] (with stainless steel implants)

690.337 4.0 mm Cannulated Screw Instrument and Implant Set Graphic Case

4.0 mm Titanium Cannulated Screw Instrument and Implant Set [145.135] (with titanium implants)

690.351 4.0 mm Titanium Cannulated Screw Instrument and Implant Set Graphic Case

207.610 ­.650 4.0 mm Cannulated Screws, short thread, 10 mm­50 mm*, 3 ea. 219.98 Washer, 6 ea. 292.62 310.67 310.86 311.43 311.63 312.35 314.03 314.08 314.29 319.15 319.25 319.38 319.97 1.25 mm Threaded Guide Wire, 150 mm, 2 pkgs. of 10 2.7 mm Cannulated Drill Bit, 160 mm, 2 ea. Cannulated Countersink Handle, with quick coupling Cannulated Tap for 4.0 mm Cannulated Screws 2.7 mm/1.25 mm Double Drill Sleeve Small Hexagonal Screwdriver Shaft Holding Sleeve Cannulated Hexagonal Screwdriver Cannulated Screw Measuring Device 1.35 mm Cleaning Brush 1.25 mm Cleaning Stylet Screw Forceps

407.610 ­.650 4.0 mm Titanium Cannulated Screws, short thread, 10 mm­50 mm*, 3 ea. 419.98 Titanium Washer, 6 ea. 292.62 310.67 310.86 311.43 311.63 312.35 314.03 314.08 314.29 319.15 319.25 319.38 319.97 1.25 mm Threaded Guide Wire, 150 mm, 2 pkgs. of 10 2.7 mm Cannulated Drill Bit, 160 mm, 2 ea. Cannulated Countersink Handle, with quick coupling Cannulated Tap for 4.0 mm Cannulated Screws 2.7 mm/1.25 mm Double Drill Sleeve Small Hexagonal Screwdriver Shaft Holding Sleeve Cannulated Hexagonal Screwdriver Cannulated Screw Measuring Device 1.35 mm Cleaning Brush 1.25 mm Cleaning Stylet Screw Forceps

Also Available

4.0 mm Cannulated Screws, long thread:* 207.716 ­.750 16 mm­50 mm lengths, (thread length=1/2 screw length) 4.0 mm Titanium Cannulated Screws, long thread:* 407.716 ­.750 16 mm­50 mm lengths, (thread length=1/2 screw length) 292.621 292.626 310.68 314.10 1.25 mm Threaded Guide Wire, spade point on both ends, 150 mm 1.25 mm Non-threaded Guide Wire, spade point (one end),150 mm, 10/pkg. 3.5 mm Cannulated Drill Bit, 160 mm, 1.35 mm cannulation, quick coupling Cannulated Hexagonal Screwdriver Shaft for power insertion of 4.0 mm cannulated screws 105.14 3.5 mm/4.0 mm Cannulated Screw Combined Instrument and Implant Set (available only with stainless steel implants) Screw Rack, for 4.0 mm Cannulated Screws (stainless steel) Screw Rack, for 4.0 mm Titanium Cannulated Screws Small Battery Drive with 14.4 V Battery Pack Sets: with Hudson Reduction Drive Unit with Modified Trinkle Reduction Drive Unit with Trinkle Reduction Drive Unit

690.337.50 690.351.50

105.954H 105.954M 105.954T

* 2 mm increments

SYNTHES (USA)

1690 Russell Road Paoli, PA 19301-1262 Telephone: (610) 647-9700 Fax: (610) 251-9056 To order: (800) 523-0322

SYNTHES (CANADA) LTD.

2566 Meadowpine Boulevard Mississauga, Ontario L5N 6P9 Telephone: (905) 567-0440 Fax: (905) 567-3185 To order: (800) 668-1119

Original Instruments and Implants of the Association for the Study of Internal Fixation -- AO ASIF

© 1995 SYNTHES (USA)

SYNTHES and ASIF are registered trademarks of SYNTHES (USA) and SYNTHES AG Chur.

Printed in U.S.A. GP0161-G 6/04 J3270-C

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4.0 mm Cannulated Screw Technique Guide

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