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3146 YLH Assisting in a Total Hip Replacement Femoral Stem Implant

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Hello. A total hip replacement is required when the cartilage covering the head of the femur, and the socket of the hip, wear down. This means that bone rubs against bone, causing pain and mobility issues. The hip joint can be replaced with an artificial implant. The socket, or acetabulum, is replaced with an implant made from high density polyethylene or ceramic, and the femoral head is replaced with a metal stem with a ceramic or metal head. This video will demonstrate the procedure for inserting a femoral stem into the femur, with cement. In practice, the preparation and placement of the implant will be done by the surgeon, but if you understand the procedure you will be able to more effectively assist the surgeon. Firstly, it is important that you are familiar with the equipment used in the procedure. Surgical Oscillating Saw: This is used to remove the femoral head. Mallet Box Chisel: This is used for removing a small box of bone from within the femur once the head has been removed. It has a pointed end which helps to scoop out bone and allows access to the femoral canal. Taper pin reamers: A taper pin reamer is the tool inside the femur and is available in small and large. Broaches: Broaches, also known as rasps, are used to shape the cavity of the femur as they are a similar shape and size as the femoral stem implant. They are available in various offsets and sizes. There are three small holes at the neck of the broach to help with the final positioning of the implant. The holes match markings on the plug introducer and stem implant. Broach Handle: The broaches can be mounted onto the broach handle. To open the handle, press the button on the side to release the arm. You can now insert the broach into the top of the handle, ensuring that it is in line. Close the handle by pushing the arm back into place. Press the button to release the broach. Plug sizers: These range in size and are used for determining the size of the canal at its narrowest point, which is known as the isthmus of the femur. Plugs and Plug introducer: There are two types of plug introducer ends, either straight or fluted. Simply place the plug on the end of the introducer. If the plug is 10mm or smaller, use the straight introducer end. Trial heads: To fine tune the balance of the total hip replacement, there are a number of trial heads of differing sizes and offsets: standard, plus and minus. Femoral stem implant: This is often referred to simply as ‘the stem’. Stem introducer: This device is used for inserting the stem implant into the canal. It has a clip on the end which can be moved depending on which side the hip is being operated on; this is the preference of the surgeon. To move the clip, unscrew the tip of the introducer, and move the clip into the desired position, before screwing the tip back into place. To load the stem onto the introducer, hook the adapter of the definitive implant onto the introducer and clip the stem into place. The tip of the introducer fits into a hole on the shoulder of the stem. Confirm that it is stable by gently moving the introducer from side to side. To release the implant, pull the trigger on the introducer and unclip the stem from the tip. Centraliser: This is placed onto the end of the stem implant to allow proper engagement of the distal end of the stem into the cement mantle. Definitive head: The definitive head is the actual stainless steel or ceramic head that will be implanted into the patient. Horse collar: This keeps the stem in place whilst the cement sets. For this stage of the total hip replacement, the patient’s leg must be positioned to achieve straight line access into the canal of the femur. Retractors will be used for surgical access. The first step is to remove the head of the femur using the surgical oscillating saw. Once the head has been removed, the surgeon will use the box chisel and mallet to scoop out the cancellous, or spongy, bone. Next, the smallest taper pin reamer is advanced into the canal of the femur in a cork screw motion to cut through the bone. This is repeated with the larger taper pin reamer. Load the smallest broach, normally size 44-0, onto the broach handle, by pressing the button, releasing the arm, inserting the broach and clicking the arm back into place. Using the mallet, the surgeon will advance the broach into the canal of the femur. The broaches are used in sequential increments until a firm fit is achieved. Once the broach is wedged within the canal, the surgeon will unclip the handle, leaving the broach in place. The surgeon needs to pay particular attention to the holes on the side of the broach to determine the correct length. With the broach in place, a trial reduction can be performed to assess for leg length and joint stability in a full range of motion. To do this, trial heads are pushed onto the end of the broach. The trial heads can be easily interchanged. Once the correct head size has been chosen, the broach can be removed with the broach handle. The surgeon may need the mallet to assist with removal. The stem can be inserted with or without cement. For a cemented stem, the canal must be sized to determine what size plug will fit snugly into the patient’s isthmus. The surgeon will pass plug sizers of increasing size into the canal. The correct one is the first one that will jam into the canal. Here, the 12 and 14 plug sizers are too small as they fall through the canal, whereas the 16 plug sizer wedges into isthmus and is the correct size. Now load the appropriately sized plug onto the plug introducer. here are markings on the plug introducer which correspond with the markings on the broach and stem. The surgeon will pass the plug and introducer into the canal as far as is possible, before withdrawing the introducer. The plug will be seated in the correct position within the canal. The femur is now ready for the stem implant to be inserted. Mount the stem onto the stem introducer, ensuring it clicks into place. Place the centraliser on the tip of the stem. Mix up two batches of cement and load the cement into the cement gun. Insert suction tubing into the canal before the cement is injected. This allows for any trapped fluid or air to be removed, and it provides a good cement mantle. As the canal fills with cement, the gun and suction tubing will be slowly withdrawn. Once the gun is out of the canal, the cement in the nozzle is pushed back with the pusher. The long plastic tube at the end of the gun can then be snapped off. The surgeon will inject more cement into the femur, under pressure, to ensure good fixation. Once the cement reaches the appropriate viscosity, the femur is ready to receive the stem implant. The surgeon will pass the stem, loaded on the introducer, into the canal. Once the markings line up in the desired position, the trigger on the introducer can be pulled to release the stem. Clip the horse collar around the stem so that it stays in the correct place whilst the cement sets. Once the cement has set, which takes about 10 minutes, the collar and the adapter on the stem can be removed. A second trial reduction will be performed by attaching the trial head to the stem. Once the surgeon is happy, the trial head can be removed and replaced with the definitive head. The procedure is now complete and the hip can be reduced.

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Duration: 9 minutes and 5 seconds
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Language: English
License: Dotsub - Standard License
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Views: 1
Posted by: richardwh on Nov 14, 2016

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