TRABECULAR METAL ACETABULAR RESTRICTOR AND AUGMENT. Surgical Technique

Transcription

1 TRABECULAR METAL ACETABULAR RESTRICTOR AND AUGMENT Surgical Technique

2 ACETABULAR ASSESSMENT AND PREPARATION Intra-operatively, carefully assess any acetabular bone defects present. Note the location, extent, and type of bone defect. It is equally important to assess the quality and location of the host bone that remains for support of the acetabular reconstruction. Use progressively larger reamers to prepare the acetabulum for the Revision Shell or other Trabecular Metal Cup. Hold the reamer steady in the intended position and orientation in which the cup will be implanted. Following acetabular preparation, reassess the acetabulum to evaluate the quality of bone and defect type. Determine if an Acetabular Restrictor and/or Augment is necessary. If both are deemed necessary, the Restrictor is placed first, then the Augment. 1ACETABULAR AUGMENT BONE PREPARATION If augmentation is elected, minimize the removal of any additional bone in areas of bone deficiency. If needed, use a hemispherical reamer or burr to smooth the surface of the defect and facilitate stable placement and impaction of the Acetabular Augment. Note: The Augment is a partial hemisphere. The smallest size reamer corresponding to an augment outer diameter size is 48mm while the largest is 58mm. Consider the size array of augments if choosing a reamer for defect preparation. 2AUGMENT SIZING Effort should be made to provide for anatomical positioning of the cup. Use acetabular cup provisionals (Trabecular Metal Revision Shell provisional shown here) along with Acetabular Augment provisionals to facilitate decision making on the proper combination and position. Choose the cup provisional that is the same size as the last reamer used in hemispherical acetabular preparation. Select the Augment provisional size to match the defect or the last reamer used to prepare the defect. The Augment provisional can be held in place with the Augment Provisional Forceps or a Pin. Ensure maximum host bone contact against the surface of the Augment provisional in order to gain maximum support for the implant. Note: Different thicknesses are available for each size Augment provisional.

3 1ACETABULAR RESTRICTOR RESTRICTOR SIZING Thread the Sizing Tamp onto the provisional shell handle and introduce into the acetabulum. Use the Sizing Tamp to select an implant size appropriate for adequate defect coverage. 2RESTRICTOR INSERTION Select the Acetabular Restrictor implant that matches the size selected when using the Sizing Tamp. The Acetabular Restrictor Inserter/Positioner can be used to facilitate placement of the Restrictor into the acetabulum. Place the implant to allow a gap between the Restrictor and the cup that can be filled with bone graft. Impact the Restrictor into final position using the Restrictor Sizing Tamp construct. Note: Some bone smoothing may be needed to allow the Restrictor to sit properly. A burr or similar tool can be used prior to implant placement. 3AUGMENT INSERTION Assemble the Torque Limiter on the screwdriver (A). Note: This will help prevent advancement of screw heads through the Augment screw holes and stripping of the threads formed in the bone. Insert the Acetabular Augment implant using the Augment Implant Forceps. Pre-drill bone holes as needed (B). A depth gauge can be used to aid in determining screw lengths. Hold the implant in place and fix as appropriate with 6.5mm screws through any or all of the three screw holes provided (C). Ensure careful screw placement to avoid vascular and neurological injury. Once the Augment is secure and stable, evaluate its fit against the host bone and the fit of the cup provisional by reintroducing the cup provisional in order to ensure proper support for the cup. The Augment should be secure and stable against the host bone, independent of any subsequent cup implant. Note: The Augment can be placed in a variety of positions to fit into the defect. One option is shown here. A B C

4 3BONE GRAFTING Place morsellized bone graft over the top of the Restrictor and then compact with the Restrictor Sizing Tamp construct. Note: This is necessary to avoid contact between the Acetabular Restrictor and the cup. 4FINAL PREPARATION The acetabulum is now ready to accept an Acetabular Augment, if necessary, or a cup. Note: If screws will be used in the cup or Augment, it is important to note the location of the Restrictor so that screws do not come in contact with the Restrictor. 4BONE GRAFTING Pack morsellized bone graft into the Augment fenestrations and around any peripheral residual gaps or bone defects in the region of the Augment. Check the implant and bone graft position by reintroducing the provisional cup. 5SURFACE PREPARATION Place doughy bone cement across the concave surface of the Acetabular Augment that will contact the cup. Take care to limit the cement to this location and prevent cement from extruding into the depths of the acetabulum where it might impede bone ingrowth into Trabecular Metal. Fixation to all areas in contact with the host bone should remain uncemented. The Augment is now prepared to accept a cup. Note: Insert the cup in its proper orientation prior to cement curing. Note: Cup screwholes may be aligned with the augment fenestrations as desired.this accommodates securing the cup with bone screw placement through the Acetabular Augment. Contact should be avoided between the bone screws and the Augment.

5 BONE VOID FILLER The Augment and Restrictor fill bone deficiencies as an alternative to preparing and using structural allografts. Host bone is conserved while the implant size, position, and orientation are determined by the defect. Acetabular Cup position and patient kinematics remain uncompromised, as when using structural grafts. The Augment, shaped similar to a partial hemisphere, comes in three thicknesses and six sizes, allowing for fit in various defects. BONE INGROWTH WITH STRUCTURAL SUPPORT Fully interconnected trabecular structure with two to three times the porosity of other implant materials enables extensive tissue ingrowth and strong attachment. 1 Trabecular Metal acts as a scaffolding for bone to grow into and remodel while providing load bearing structural support, unlike structural allografts that can resorb and fail. High coefficient of friction 1 against bone provides great initial stability. Low stiffness of Trabecular Metal can produce more normal physiological loading and reduce stress shielding. 2 Augment fenestrations provide significant volume for morsellized bone graft, which may aid in bone growth and remodeling. 3 The Restrictor is concave and comes in three diameters, allowing for coverage of medial wall defects and containment of morsellized bone graft 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 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 Steinberg ME, Garino JP, editors. Revision total hip arthroplasty. Lippincott Williams and Wilkins; 1999; Philadelphia, PA.

6 ORDER INFORMATION ACETABULAR AUGMENT Augment Size 48, 10mm thick Augment Size 50, 10mm thick Augment Size 52, 10mm thick Augment Size 54, 10mm thick Augment Size 56, 10mm thick Augment Size 58, 10mm thick Augment Size 48, 20mm thick Augment Size 50, 20mm thick Augment Size 52, 20mm thick Augment Size 54, 20mm thick Augment Size 56, 20mm thick Augment Size 58, 20mm thick Augment Size 50, 30mm thick Augment Size 52, 30mm thick Augment Size 54, 30mm thick Augment Size 56, 30mm thick Augment Size 58, 30mm thick ACETABULAR RESTRICTOR Restrictor, 26mm diameter Restrictor, 32mm diameter Restrictor, 38mm diameter TRILOGY* BONE SCREWS mm x 15mm mm x 20mm mm x 25mm mm x 30mm mm x 35mm mm x 40mm mm x 50mm mm 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. *Trilogy Acetabular System Bone Screws and Instruments are manufactured by Zimmer, Inc. Trabecular Metal Acetabular Augment System developed in cooperation with David G. Lewallen, MD, Orthopaedic Surgeon, Mayo Clinic, and Arlen D. Hanssen, MD, Orthopaedic Surgeon, Mayo Clinic. SCREW INSTRUMENTS Trilogy Holed Instrument Set (Includes one each of the following:) Flex Shaft w/ Modular Connector Drill Bit, 15mm length Drill Bit, 30mm length Drill Bit, 45mm length Drill Guide Tap, 4.5mm dia Tap, 6.5mm dia Tap Guide, 4.5mm dia Tap Guide, 6.5mm dia Tap Handle Straight Screwdriver Universal Screwdriver Modular Universal Handle Screw Holding Forceps, Screw Holding Forceps, Depth Gauge Case (Including base and lid) Screwdriver Torque Limiter (ordered separately, not in kit) INSTRUMENTS Acetabular Augment & Restrictor Instrument Set (Includes one each of the following:) Augment Prov. Size 48, 10mm thick Augment Prov. Size 50, 10mm thick Augment Prov. Size 52, 10mm thick Augment Prov. Size 54, 10mm thick Augment Prov. Size 56, 10mm thick Augment Prov. Size 58, 10mm thick Augment Prov. Size 48, 20mm thick Augment Prov. Size 50, 20mm thick Augment Prov. Size 52, 20mm thick Augment Prov. Size 54, 20mm thick Augment Prov. Size 56, 20mm thick Augment Prov. Size 58, 20mm thick Augment Prov. Size 50, 30mm thick Augment Prov. Size 52, 30mm thick Augment Prov. Size 54, 30mm thick Augment Prov. Size 56, 30mm thick Augment Prov. Size 58, 30mm thick Restrictor Sizing Tamp, 26mm dia Restrictor Sizing Tamp, 32mm dia Restrictor Sizing Tamp, 38mm dia Restrictor Inserter / Positioner Screwdriver Torque Limiter Augment Implant Forceps Augment Provisional Forceps Augment & Restrictor Instrument Case Please refer to package insert for complete product information, including contraindications, warnings, precautions, and adverse effects. Contact your Zimmer Representative or visit us at ML Printed in USA 2002, 2003 Zimmer, Inc.