Anterior Approach Surgical Technique. Paragon Stem System. enabling people to enjoy life

Transcription

1 Anterior Approach Surgical Technique Paragon Stem System enabling people to enjoy life

2 Contents Pre-Operative Planning... 2 Suggested Templating Method... 2 Surgical Technique... 3 Surgical Approach... 3 Surgical Exposure... 3 Femoral Neck Resection... 3 Acetabulum Preparation... 3 Femoral Canal Preparation... 4 Femoral Canal Opening... 4 Broaching... 4 Trial Reduction... 5 Femoral Component Insertion... 5 Femoral Head Assembly... 5 Implant Dimensions

3 Pre-Operative Planning Suggested Templating Method Work from accurate radiographs. Ensure that the pelvis is centred over the pubic symphysis for the A/P Pelvis radiograph. For the lateral radiograph use a Lauenstein technique (frog leg lateral). It is recommended to use a radiographic marker or scale. Measure the diameter of the intramedullary canal. Using the templates provided, check at the isthmus on both the A/P and lateral radiographs. Select a stem size between the two readings as the target for stem broaching. The templates are provided at 100% and 120% magnification for compatibility with standard radiographs. Determine the hip s centre of rotation. Size the acetabular component using the appropriate templates. If medialising the acetabular shell the native centre of rotation may be slightly different from the centre of rotation for the templated interface porous shell, place a small mark on the radiograph at the centre of rotation of the selected porous shell. Determine preoperative leg length correction. Using the A/P Pelvis radiograph determine the leg length discrepancy from the contralateral hip or other clinical methods. Select a stem size that fits the intramedullary canal and fills the proximal metaphysis. Position the selected templated size on the A/P pelvis radiograph and select a neck angle and offset that places the "0" neutral femoral head at a position to correct the leg length discrepancy. Determine neck resection. Note the distance from the shoulder of the selected femoral stem to the lesser trochanter. Templates are printed with graduated markings for reference. Note: The final component size is to be determined intra-operatively. Templating is for planning purposes only. 2

4 Surgical Technique Surgical Approach The approach to the hip is the surgeon s choice; it varies and is influenced to a degree by the pathology present. This technique is specifically for implanting the Paragon Hip Stem using an Anterior or Direct Anterior approach. Position the patient supine on a fluoroscopy-capable table. The O.R. table must be able to extend at the hip and the hip must be positioned to permit fluoroscopic viewing. There are a number of options available to the surgeon to assist with exposure including traction table attachments and table mounted retractors. Surgical Exposure Surgical exposure will depend on which Surgical method is selected. Retractors are provided with the Paragon system specific for Anterior and Direct Anterior approach however their selection, placement and use is based on Surgeon preference on which exposure method they select. Additional surgical tools not specific to the Paragon system may also be used by the surgeon to assist with exposure supplied by the hospital or another other 3rd party such as table mounted retractors. Femoral Neck Resection Once exposure through the joint capsule is achieved via the chosen Anterior approach, insert the Femoral Head Removal Tool into the femoral head. Using this and distraction forces (either manual or mechanism assisted), dislocate the femoral head. Then, using preoperative radiographs as a guide, resect the femur in the desired location and orientation. Note that the angle of the osteotomy cut is 45 degrees to the long axis of the femur. Locate the inferior lesser trochanter, and determine the correct length for the neck resection. NOTE: During the anterior approach, it is difficult to perform a second or finishing resection so take care to make the first resection correctly. During Femoral head removal, use retractors to protect the tensor from sharp fragments on the resected femoral neck. Acetabulum Preparation After the femoral neck osteotomy is complete, prepare and implant the acetabular components. 3

5 Femoral Canal Preparation Palpate the vastus tubercle and place the Bone Hook distal to the vastus tubercle on the posterior side of the femur. Externally rotate the femur, and apply force to Bone Hook to elevate the proximal femur and allow visualisation. Take care when applying force during external rotation, especially on osteoporotic patients, since forces can result in fractures. Release the lateral capsule anterior to posterior from inside the greater trochanter towards the piriformis fossa. Perform releases to the capsule to the medial trochanter tip will further increase exposure. Use a Long Rongeur (Bone Nibbler) to remove lateral neck material from the resection. Femoral Canal Opening Open the proximal femur to the piriform fossa by using the Offset Box Chisel. Employ the starter rasp or curved starter rasp to identify the intramedullary canal of the proximal femur working laterally and posteriorly. Use Rongeur to remove any overhanging bone fragments from the greater trochanter, since these may interfere with broaching and send the broaches varus, or through the lateral wall of the femoral canal. Note: When x-ray templating shows a steeply tapering intramedullary canal, distal reaming may be performed prior to broaching to assist with insertion of the broaches and stem. Broaching Start with the smallest broach attaching it to the Anterior Broach handle. During broaching periodically withdraw the broach to help clear the broach teeth of bone fragments. The lateralising broach may be used at any time to lateralise the exposure to ensure correct broach trajectory is achieved. Advance the cutting teeth of the selected broach to the depth of the neck resection or to depth established in pre-operative planning. Continue the broaching process increasing the broach size sequentially until the broach size matches the size of the required implant. Once the final broach has been used it should be seated into the final implant position. Assess the stability of the broach to assure that the correct size implant has been selected. Technique tip: To minimise the risk of varus positioning, clear out bone from the medial aspect of the greater trochanter using the broaches. 4

6 Calcar Milling Once the final broach has been reached, the calcar mill can be used on the broach to further prepare the resected femur. While this step is optional for a non-collared Paragon stem, it is mandatory for a collared Paragon stem. Trial Reduction Bury the teeth of the final broach to the resection level and disengage the broach handle. The modular trial necks slide onto the post on the proximal end of the broach. Select the trial neck based on preoperative planning and on your previous intraoperative assessments. Slide the appropriate trial neck onto the broach. Place a modular trial head onto the trial neck and reduce the hip. Assess leg length, range of motion, and stability. Adjust as necessary by choosing a different neck/head combination. Leg length and offset may be fine-tuned by changing the neck and/or heads. Where possible select a 0 or -3.5mm femoral head with an offset stem instead of increasing offset with head length. Remove the trial neck, reattach the broach handle and remove the broach. Femoral Component Insertion Select the Paragon stem that correlates to the same size as the last used broach. Engage in the femoral canal by hand and finish its introduction with the impactor for the last few centimetres. Note: The stem is 0.30 mm thicker than the corresponding broach to allow 0.15mm press-fit either side of the implant. Femoral Head Assembly Once the stem has been inserted, stability should be assessed one final time using the appropriate head trial. The selected femoral head implant is then inserted over the neck trunnion and impacted using the supplied head impactor before final reduction. 5

7 Implant Dimensions A/P M/L STEM STANDARD OFFSET 130 STEM WIDTH WIDTH LENGTH OFFSET (D) NECK HEIGHT (E) SIZE (A) (B) (C) Paragon Stem Standard Offset dimensions A/P M/L STEM HIGH OFFSET 130 STEM WIDTH WIDTH LENGTH OFFSET (D) NECK HEIGHT (E) SIZE (A) (B) (C) Paragon Stem High Offset dimensions (A) (B) NECK ANGLE (D) (C) (E) 6

8 Instrument Catalogue Paragon Instrument Box 1 Male Broaches Catalogue Number Size GM Paragon Trial Femoral Head Catalogue Number Head Size (mm) Offset (mm) GM GM GM GM GM GM GM GM GM GM GM GM GM GM GM GM Paragon Broach - Male Catalogue Number Size GM GM GM GM GM GM GM GM GM GM GM GM GM

9 Paragon Trial Neck Standard Female Catalogue Number Size GM GM GM GM Paragon Trial Neck High Offset - Female Catalogue Number Size GM GM GM GM Paragon Femoral Head Impactor Catalogue Number Size GM Anterior Hip Tray Catalogue Number Size GM Paragon Femoral Head Removal Tool - Hudson Catalogue Number Size GM Paragon Offset Box Chisel Catalogue Number Size GM Paragon Curved Rasp Catalogue Number Size GM

10 Paragon Threaded Stem Positioner Catalogue Number Size GM Paragon Anterior Broach Handle (Left) Catalogue Number Size GM Paragon Anterior Broach Handle (Right) Catalogue Number Size GM Paragon Anterior Broach Handle (Left) Catalogue Number Size GM Paragon Anterior Broach Handle (Right) Catalogue Number Size GM

11 Paragon Lateralising Rasp - Male Catalogue Number Size GM Paragon Offset Stem Inserter Catalogue Number Size GM Paragon Stem Extractor Catalogue Number Size GM Paragon T-Handle (Silicone) Catalogue Number Size GM Paragon Calcar Mill Female (Cutouts) Catalogue Number Size GM GM Small Large Anterior Hip Retractor Tray Catalogue Number Size GM

12 Paragon Gelpi Retractor Catalogue Number Size GM Paragon Bone Hook Catalogue Number Size GM Paragon Long Bone Nibbler Catalogue Number Size GM Paragon Femoral Neck Elevator Catalogue Number Size GM Paragon Long Cobb Elevator Catalogue Number Size GM Paragon Double Prong Hohmann 90 Degrees Blunt 44mm Catalogue Number Size GM Paragon Single Prong Extended Hohmann 75 Degrees Blunt 22mm Catalogue Number Size GM Paragon Single Prong Hohmann 75 Degrees Blunt 22mm Catalogue Number Size GM

13 Paragon Double Bend Hohmann 15mm Catalogue Number Size GM Paragon Heavy Mallet 1kg Catalogue Number Size GM

14 Implant Catalogue Paragon Stem Standard PCHA Catalogue Number Size GM GM GM GM GM GM GM GM GM GM GM GM Paragon Stem High Offset PCHA Catalogue Number Size GM GM GM GM GM GM GM GM GM GM GM GM Paragon Stem Standard Collared PCHA Catalogue Number Size GM GM GM GM GM GM GM GM GM GM GM GM Paragon Stem High Offset Collared PCHA Catalogue Number Size GM GM GM GM GM GM GM GM GM GM GM GM

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