Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments Surgical Technique

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Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments

Trabecular Metal Acetabular Revision System Buttress and Shim Augments Surgical Technique

Table of Contents A Viable Alternative to Structural Allograft

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Buttress and Shim Augment Surgical Technique

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Preoperative Planning

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Acetabular Assessment and Preparation

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Choose the Appropriate Component

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Prepare the Bone for the Buttress Augment

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Implant the Buttress Augment

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Implant the Revision Shell

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Cement the Acetabular Liner

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Product Information

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Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments

A Viable Alternative To Structural Allograft

Give Bone a Solid Hold

• The Straight Buttress and Column Buttress Augments provide superior structural support to the Trabecular Metal Revision Shell as an alternative to preparing and using structural allograft.

• The Buttress Augment shape is comparable to a “Figure 7” distal femoral allograft, without the potential for resorption, loss of structural integrity or disease transmission.

• Shim Augments provide the ability to optimize the fit of either buttress device to host bone.

• Host bone is conserved while the buttress augment provides structural support for more natural implant positioning and orientation.

• The Buttress Augment and Trabecular Metal Revision Shell construct provide a solution for addressing Paprosky Type IIIA superior segmental and/or cavitary defects without custom implants or bulk allografts.

• Acetabular cup position and patient kinematics remain uncompromised. • Sizing options allow usage of Buttress Augments with any Trabecular Metal Revision Shell.

• Fully-interconnected trabecular structure with two to three times the porosity of other porous materials enables extensive biologic ingrowth and strong attachment.1 • Trabecular Metal material acts as a scaffolding for biologic ingrowth and remodeling while providing load bearing structural support.2 • High coefficient of friction against bone provides enhanced stability.3 • Low stiffness of Trabecular Metal material can produce more normal physiological loading and reduce stress shielding.4

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Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments

Preoperative Planning The Paprosky classification system is based on the severity of bone loss and the ability to obtain cementless fixation for a given bone loss pattern.5 In this classification system, a Type-IIIA Defect is described as an acetabulum that will not provide adequate initial component stability to achieve reliable biological fixation. Preoperative radiographs show superior and lateral migration of the component greater than 3cm above the obturator line (with adjustment for magnification).6 The remaining acetabular rim will not provide initial structural support for the acetabular shell. Support of the implant with a structural augment is necessary in the short term to provide initial stability and thus allow ingrowth in contact with the host bone.5 Augments also restore the center of rotation to the proper anatomic location.

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Acetabulum Assessment and Preparation

Carefully assess any acetabular bone defects intraoperatively, noting the location, extent, and defect type. Also assess the quality and location of the host bone that remains for support of the acetabular reconstruction (Fig. 1). Identify the hip center and use progressively larger reamers to size and shape the acetabulum for the Trabecular Metal Revision Shell (Fig. 2). Hold the reamer steady in the intended position and orientation in which the shell will be implanted.

Pelvic Discontinuity

Bone Loss Bone Loss Fig. 1

Reassess the acetabulum to evaluate the quality of bone and defect type. Determine which Trabecular Metal components will be used to reconstruct the acetabulum. If a Trabecular Metal medial wall Restrictor is to be used, it should be placed before the other components. Contained defects in the acetabulum may be filled with morselized bone graft.

Fig. 2

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Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments

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Choose the Appropriate Component

Insert the selected size Trabecular Metal Revision Shell Provisional to determine areas of host bone contact, inherent stability, and the location of the segmental bone loss where the Trabecular Metal Straight Buttress or Column Buttress will be used. Effort should be made to provide for anatomical positioning of the cup. Then use the Straight Buttress and/ or Column Buttress Provisionals to determine the size that will best fill the defect. The Straight Buttress (Fig. 3) is available in two sizes: 54mm and 58mm. The Column Buttress (Fig. 4) is available in two configurations, Left Posterior/ Right Anterior and Right Posterior/Left Anterior, both similar in size to the 54mm Straight Buttress. Be sure to use the configuration most appropriate for addressing the column deficiency which is present.

Right Posterior/Left Anterior Column Buttress Augment

54mm Straight Buttress Augment

Note: Buttress Augments should be supported by placing the “step” on

Fig. 3 Straight Superior Defect (Paprosky Type IIIA)

Fig. 4 Left Posterior Column Defect (Paprosky Type IIIA)

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Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments

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Prepare the Bone for the Buttress Augment

With the Revision Shell Trial in place, position the Straight Buttress or Column Buttress Provisional against the ilium (Fig. 5). Use a rongeur to remove bone as necessary, being careful to minimize the amount of bone removed. A burr can be used to smooth the surface of the defect to facilitate stable placement and optimize the fit of the Buttress Augment. Use a depth gauge through the screw holes in the flange of the Straight Buttress or Column Buttress Provisional to assess implant/bone contact. It is important to achieve maximum contact between the buttress augment and the host bone of the ilium. If additional contact is needed, determine the appropriate size Trabecular Metal Shim Augment to achieve appropriate contact (Fig. 5a). Place the Shim Provisional beneath the flange of the Buttress Augment or Column Buttress Provisional and rotate as needed to obtain optimal component-to-host bone contact (Fig. 6). Ensure proper shim and flange screwhole alignment. Note the location of the provisional components. Remove the provisional components. Note: Maximum host bone contact and bone support are needed to optimize implant performance.

Fig. 5a

Fig. 5

Fig. 6

5° Shim Augment

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Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments

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Implant the Buttress Augment

If using a Shim, ensure the orientation of the Shim with respect to the Straight Buttress or Column Buttress is the same as it was during trialing. Cement the two components with doughy PALACOS®* bone cement on the back table. Care should be taken to prevent cement from extruding into the screw holes on either component (Fig. 7).

Fig. 7

With the provisional shell in place, fit the augment in the appropriate position on the ilium. Insertion of the implant can be done by hand or with the Augment Forceps by grasping the two screw holes on the top of the Straight Buttress or Column Buttress. Drill the screw holes through the desired holes in the augment flange to accept 6.5mm cancellous screws (Fig. 8). Screws should be positioned to achieve optimal fixation in the ilium. Assemble the Torque Limiter onto the screwdriver. Note: Using the Torque Limiter prevents advancement of screw heads through the screw holes or stripping of the threads formed in the bone.

Fig. 8

To achieve initial fixation, insert 6.5mm HGP II cancellous screws using the predrilled holes (Fig. 9). Ensure careful screw placement to avoid vascular and neurological injury. Fill any remaining voids with cancellous bone graft. Check the implant and bone graft position by reintroducing the provisional cup.

* PALACOS is a trademark of Heraeus Kulzer GmbH. Under license from Heraeus Kulzer GmbH, Hanau, Germany.

Fig. 9

Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments

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Implant the Revision Shell

Attach the cup inserter to the rim of the selected Trabecular Metal Revision Shell. Place doughy PALACOS bone cement across the concave surface of the buttress augment where it will contact the shell (Fig. 10). Take care to limit the cement to this location and prevent cement from extruding onto host bone where it might impede bone ingrowth into the Trabecular Metal Implants.

Fig. 10

Insert the revision shell in proper anatomical orientation prior to cement curing, with screwholes located in the area of ideal host bone fixation (Fig. 11). Place HGP II cancellous screws into the revision shell being careful to avoid contact between the bone screws and the augment (Fig. 12).

Fig. 11

Fig. 12

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Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments

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Cement the Acetabular Liner

Cement the Longevity® Highly Crosslinked Polyethylene Revision Shell Liner with doughy PALACOS Bone Cement (Fig. 13). The Revision Shell Liners are available in several head articulation options, including 28, 32, 36, and 40mm inner diameters. Optional: Bone wax covering unused screw holes can prevent cement extrusion through the holes and potential interference with bone ingrowth into the Trabecular Metal Revision Shell. Additionally, covering screw heads may aid in screw removal if future revision surgery is needed.

Straight Buttress Construct

Fig. 13

Left Posterior Column Buttress Construct

1 Bobyn JD, Hacking SA, Chan SP, et al. Characterization of a new porous tantalum biomaterial for reconstructive orthopaedics. Scientific Exhibit, Proc of AAOS, Anaheim, CA. 1999. 2 Nehme, Lewallen, Hanssen. Modular Porous Metal Augments for Treatment of Severe Acetabular Bone Loss During Revision Hip Arthroplasty. Clinical Orthop, No. 429, December 2004. pp201-208. 3 Yongde Z, Ahn PB, Fitzpatrick DC, Heiner AD, Poggie RA, Brown TD. Interfacial frictional cancellous bone, cortical bone, and a novel porous tantalum biomaterial. Journal of Musculoskeletal Research, Vol. 3, No. 4, 1999. 245-251. 4 Pedersen DR, Brown TD, Poggie RA. Finite element analysis of periarticular stress of cemented, metal-backed, and porous tantalum-backed acetabular components. 45th Annual Orthopaedic Research Society Meeting, Anaheim, CA. 1999. 5 Paprosky WG, Perona PG, Lawrence JM. Acetabular defect classification and surgical reconstruction in revision arthroplasty. A 6-year follow-up evaluation. J Arthroplasty. 1994;9:33-44. 6 Sporer SM, Paprosky WG, O’Rourke M. Managing Bone Loss in Acetabular Revision. J Bone Joint Surgery. 2005;87-2:1620-30.

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Trabecular Metal™ Acetabular Revision System Buttress and Shim Augments

Product Information Screw Instruments

Buttress Augments Prod. No.

Description

Prod. No.

Description

00-4894-001-54

Straight Buttress Augment, size 54mm

00-6260-099-02

00-4894-001-58

Straight Buttress Augment, size 58mm

Trilogy® Holed Instrument Set (Includes one each of the following:)

00-4894-300-00

Column Buttress Augment, Left Posterior/Right Anterior

00-6260-002-00

Flex Shaft w/ Modular Connector

00-4894-400-00

Column Buttress Augment, Right Posterior/Left Anterior

00-6260-003-01

Drill Bit, 15mm length

00-6260-003-02

Drill Bit, 30mm length

00-6260-003-03

Drill Bit, 45mm length

00-6260-006-00

Drill Guide

00-6260-007-01

Tap, 4.5mm dia.

Shim Augments Prod. No.

Description

00-6260-007-02

Tap, 6.5mm dia.

00-4894-001-05

Trabecular Metal Shim, 5 degree

00-6260-008-01

Tap Guide, 4.5mm dia.

00-4894-001-10

Trabecular Metal Shim, 10 degree

00-6260-008-02

Tap Guide, 6.5mm dia.

00-4894-001-15

Trabecular Metal Shim, 15 degree

00-6260-010-00

Tap Handle

00-6260-024-00

Straight Screwdriver

00-6260-025-00

Universal Screwdriver

00-6260-026-00

Modular Universal Handle

HGP II Bone Screws Prod. No.

Description

00-6260-013-00

Screw Holding Forceps, 15°

00-6624-065-20

6.5mm x 20mm

00-6260-014-00

Screw Holding Forceps, 45°

00-6624-065-25

6.5mm x 25mm

00-6611-098-00

Depth Gauge

00-6624-065-30

6.5mm x 30mm

00-6260-085-01

Case (Including base and lid)

00-6624-065-35

6.5mm x 35mm

00-4215-200-00

00-6624-065-40

6.5mm x 40mm

Screwdriver Torque Limiter (ordered separately, not in kit)

00-6624-065-50

6.5mm x 50mm

00-6624-065-60

6.5mm x 60mm

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

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Instruments

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2

5

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Prod. No.

Description

00-7105-006-00

Buttress and Shim Augment Provisional Kit (includes one each of the following:)

00-7106-023-00

Buttress and Shim Augment Provisional Drop-In Tray (drops into Trabecular Metal Augment Instrument Case 00-7106-020-00)

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00-4216-001-05

Trabecular Metal Shim Provisional, 5 degree

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00-4216-001-10

Trabecular Metal Shim Provisional, 10 degree

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00-4216-001-15

Trabecular Metal Shim Provisional, 15 degree

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00-4216-001-54

Straight Buttress Provisional, Size 54mm

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00-4216-001-58

Straight Buttress Provisional, Size 58mm

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00-4216-300-00

Column Buttress Provisional, Left Posterior/Right Anterior

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00-4216-400-00

Column Buttress Provisional, Right Posterior/Left Anterior

This documentation is intended exclusively for physicians and is not intended for laypersons. Information on the products and procedures contained in this document is of a general nature and does not represent and does not constitute medical advice or recommendations. Because this information does not purport to constitute any diagnostic or therapeutic statement with regard to any individual medical case, each patient must be examined and advised individually, and this document does not replace the need for such examination and/or advice in whole or in part. Please refer to the package inserts for important product information, including, but not limited to, contraindications, warnings, precautions, and adverse effects.

Contact your Zimmer representative or visit us at www.zimmer.com The CE mark is valid only if it is also printed on the product label.

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