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99.26.12Patella rev.0 GMK SURGICAL TECHNIQUE - PATELLA ADDENDUM INTRODUCTION The following surgical technique is an Addendum to the GMK Primary Surgical Technique. It describes the patella preparation by means of the new Medacta Clamp, to be used both with resurfacing and inset patella versions. For the other steps of the surgical technique, please refer to the official GMK Primary Surgical Technique. RESURFACING PATELLA Ref.no. 02.07S.721RES - Resurfacing patella tray 2 1. 2. 3. 4. 5. 4 1 Medacta clamp Adjustable cup Patella clamp base Spacer for patella clamp Micrometric resection guide 3 5 Clip the adjustable cup on the upper jaw of the Medacta clamp and the patella clamp base on the lower jaw of the Medacta clamp. A CAUTION: The upper surface of the patella clamp base is endowed with 4 spikes. Handle with care. Open completely the adjustable cup by rotating the screw A. Insert the blue spacer (red arrow). B CAUTION: To ensure the correct fixation, align the hole on the spacer to the hole on the adjustable cup before inserting the spacer (B). 1 99.26.12Patella rev.0 Assemble the micrometric resection guide on the patella clamp base. CAUTION: The lever A must be at this step fully released. C B 1. Center the slot C located on the resection guide on the square knob B located on the patella clamp base 2. Slide down the resection guide (1,2) until the same level is reached (3) 3. Lock the lever A to fix the connection. A 1 2 3 2 99.26.12Patella rev.0 Position the assembly on the patella, making sure to be aligned to the lateral shield of the patella. CAUTION: Resection jaws must be at this step fully open. Close the clamp until contact between the superior adjustable cup and the patella is reached. Then fix the position by moving the lever ahead. Read the patella thickness on the scale located at the top of the clamp (22 mm in the example). Thickness values range from 18 mm to 34 mm. CAUTION: The read value is only an indication and can differ from the real patella thickness. This value represents the distance between the top of the patella base clamp and the bottom of the adjustable cup and may differ from the real bone thickness. 3 99.26.12Patella rev.0 Read the residual bone stock after resection on the scale located at the side of the clamp (16 mm in the example). Bone stock values range from 12 mm to 24 mm. CAUTION: The read value is only an indication. This value represents the difference between the measured patella thickness and the distance between the bottom of the adjustable cup and the resection slot and may differ from the real bone thickness Residual bone stock = patella measured thickness – resection thickness. A To reproduce the same thickness of the natural patella, the bone stock scale has to be set (A) on the value corresponding to: patella measured thickness – 10 mm. CAUTION: The minimum bone stock allowed by the instrument is 12 mm. WARNING: An insufficient residual bone stock may cause patella fracture. When the resection level is deemed satisfactory, lock the jaws by rotating the corresponding screw. Perform the patellar cut by using an oscillating saw. 4 99.26.12Patella rev.0 Open the clamp by driving the two handles slightly down and simultaneously move back the lever. Unscrew the knob of the micrometric resection guides to open its jaws. Remove the whole assembly from the joint and disassemble the micrometric resection guides from the Medacta clamp. Size the resurfacing patellar implant by using the dedicated templates. Disassemble the adjustable cup from the Medacta clamp and clip the drilling guide (LAT marked) OPTION: In case a Keblish approach is used, a dedicated drilling guide is available on request (MED marked) As a general rule, the 2 peg holes (red circle) must be on the medial side of the patella once reduced. Lateral Facet Medial Facet Medial Facet Lateral Facet PATELLA IN PLACE EVERTED PATELLA 5 99.26.12Patella rev.0 Close the clamp until contact between the drilling guide and the resection is made. Then fix the clamp position by using the upper lever. Perform the 3 peg holes by using the dedicated drill. Remove the clamp from the joint. Rest the trial resurfacing patella on the bone, centering it on the 3 holes. Reduce the patella and test the knee joint through its full range of motion. 6 99.26.12Patella rev.0 Remove the trial patella. Assemble the patellar cup on the clamp. cement The bone cement must be prepared according to the related instructions for use, provided by the cement manufacturer. Once the cement has the right viscosity, it should be applied to the internal surface of the patellar implant. Lock the patella, by closing the Medacta clamp. Hold the implant in the final position and clear the extruded cement from the patella, ensuring that no cement remains on the articular surface. 7 99.26.12Patella rev.0 INSET PATELLA Ref.no. 02.07S.721INS - Inset patella tray Size the inset patellar implant by using the dedicated templates or, alternatively, the reamer guides. CAUTION: The reamer guide is endowed with 3 spikes. Handle with care. 8 99.26.12Patella rev.0 Clip the adjustable cup on the upper jaw of the Medacta clamp and the patella clamp base on the lower jaw of the Medacta clamp. A CAUTION: The upper surface of the patella clamp base is endowed with 4 spikes. Handle with care. Open completely the adjustable cup by rotating the screw A. Insert the blue spacer (red arrow). B CAUTION: To ensure the correct fixation, align the hole on the spacer to the hole on the adjustable cup before inserting the spacer (B). Close the clamp on the patella, fix its position by using the upper lever and read the bone thickness on the upper scale (red circle). Then unlock the lever to open the clamp and disassemble the adjustable cup. CAUTION: The read value is only an indication and can differ from the real patella thickness. This value represents the distance between the top of the patella base clamp and the bottom of the adjustable cup and may differ form from the real bone thickness. Clip the reamer guide of the correct size on the clamp, making sure that the three spikes are facing the patella. Close the clamp until contact between the reamer guide and the patella is made. 9 99.26.12Patella rev.0 To assemble the reamer of the suitable size to the reamer holder, insert the reamer on the tip of the reamer holder (1), turn it 90° (2) until it is fixed to the reamer holder. 2 1 Before drilling, check that the depth gauge A is in neutral position. If necessary the reaming depth can be modified by screwing the depth gauge (1 turn = 1 mm). A Fix the depth gauge by turning the fixation screw B. NOTICE: When the depth gauge is in the neutral position, the drilling depth corresponds to the patella implant thickness of the validated side. B NEUTRAL POSITION DEEPER HOLE MORE SHALLOW HOLE 10 99.26.12Patella rev.0 Release the lever and remove the clamp from the joint. insert the trial inset patella on the bone, centering it on the central hole. Reduce the patella and test the knee joint through its full range of motion. Remove the trial patella. Assemble the patellar cup on the clamp. cement The bone cement must be prepared according to the related instructions for use, provided by the cement manufacturer. Once the cement has the right viscosity, it should be applied to the internal surface of the patellar implant. Lock the patella, by closing the Medacta clamp. Hold the implant in the final position and clear the extruded cement from the patella, ensuring that no cement remains on the articular surface. 11 99.26.12Patella rev.0 Instrumentation nomenclature Ref. No. Description Picture Q.ty 02.07.10.1075 Medacta clamp 1 02.07.10.1141 Patella clamp base 1 02.07.10.1148 Patella cement cup 1 02.07.10.1148 Micrometric resection guide 1 02.07.10.1093 Patella drilling guide 1 02.07.10.0428* Patella drilling guide (Keblish approach) 1 02.07.10.0425 Spacer for patella clamp adjustable cup 1 02.07.10.1154 Patella clamp adjustable cup 1 02.02.10.0404 Patella peg drill (Ø4.5 L 155) Hudson coupling 1 02.07.10.1159 Trial resurfacing patella # 1 1 02.07.10.1064 Trial resurfacing patella # 2 1 02.07.10.1160 Trial resurfacing patella # 3 1 02.07.10.1169** Patella template Ø20 1 02.07.10.1166* Patella template # 1 Ø24 1 02.07.10.1167* Patella template # 2 Ø28 1 02.07.10.1168* Patella template # 2 Ø32 1 12 99.26.12Patella rev.0 Ref. No. Description Picture Q.ty 02.07.10.1161** Trial inset patella ø20 1 02.07.10.1162 Trial inset patella ø24 1 02.07.10.1163 Trial inset patella ø28 1 02.07.10.1164 Trial inset patella ø32 1 02.07.10.1142** Reamer Guide Ø20 1 02.07.10.1143 Reamer Guide Ø24 1 02.07.10.1144 Reamer Guide Ø28 1 02.07.10.1165 Reamer Guide Ø32 1 Reamer Holder 1 T12893** Reamer Ø20 1 T12894 Reamer Ø24 1 T12895 Reamer Ø28 1 T13716 Reamer Ø32 1 T12896 Legend: *on demand **on demand (not for US market) Part numbers subject to change. Note for sterilization: The instrumentation is not sterile upon delivery. It must be cleaned before use and sterilized in an autoclave respecting the regulations of the country EU, directives where applicable and following the instruction for use of the autoclave manufacturer. For detailed instructions please refer to the document “Recommendations for cleaning decontamination and sterilization of Medacta® International reusable orthopedic devices” available at www.medacta.com. GMK®, Medacta® are registered trademarks of Medacta International SA, Castel San Pietro, Switzerland. 13