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1. Pre-operative Planning
Pre-operative templating is important and will usually allow the surgeon to select an implant of the appropriate size and offset for the hip to be reconstructed, and to plan the positions in which the components should be placed (Fig. 1).
Allowance must be made for the need to obtain a complete mantle of cement for the femoral component that is to be used. Alongside the stem profiles on the templates are marks that demonstrate the extent of cement mantles of varying widths. The first mark indicates the minimum mantle allowed. It may be necessary to template the opposite hip. 
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Fig. 1
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2. Surgical Exposure
The Exeter™ Hip can be implanted through the direct lateral or lateral approaches or through the Southern or posterior approach. The Southern or posterior approach is featured in this technique manual. Whichever approach is used, a full exposure of both the acetabulum and the proximal femur is essential for effective preparation of the bony cavities, cementing, and implant insertion.
Appropriate soft tissue releases shall be performed to allow adequate exposure of the whole socket rim and mobilisation of the proximal femur. The patient must be firmly and accurately supported in the lateral decubitus position (Fig. 2) to help ensure that the acetabular component is orientated correctly. It is also important not to flex the contralateral hip too much as this could reduce the lumbar lordosis, with subsequent risk of retroversion of the cup.
Either the femur or the acetabulum may be prepared first.
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Fig. 2
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3. Femoral Neck Resection
The level and orientation of neck resection is not critical as the Exeter™ Hip Stem has no collar or other features which will affect the osteotomy line. The level of section usually runs from mid-way between the upper margin of the lesser trochanter and the inferior aspect of the head, to the upper surface of the base of the neck (Fig. 3).
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Fig. 3
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4. Femoral Preparation
The leg is positioned and held with a femoral elevator. A gluteus medius retractor may be to fully expose the proximal femur (Fig. 4).
The opening in the cut surface of the femoral neck is developed from within the calcar toward the proximal aspect of the greater trochanter as far as necessary to allow the Exeter™ stem to be passed directly down the femur in the long axis of the medullary canal.
The cavity is opened using the straight Capener type gouge or a box chisel, to undercut the base of the neck, and develop the slot into the trochanteric region (Fig. 5), if necessary using a rongeur to resect the bone of the neck after undercutting. The taper pin reamer is used t o develop the slot to ensure that the femoral stem can be inserted down the mid-line of the femur.
T he taper pin reamer should be positioned within the canal so that it aligns with the popliteal space (Fig. 6), or with the patella if the lateral approach is being used. Trabecular bone is removed from within the calcar until a strong layer is encountered, usually this will leave 2 - 3mm of strong trabecular bone. This layer of trabecular bone provides a firm foundation for the micro-interlock of cement within the bone. A smaller rasp is used initially finishing with the rasp corresponding to the template considered appropriate for the femur. It is a serious mistake to over-rasp the canal and remove too much cancellous bone.(Fig 7)
If excess force is required to introduce a rasp to this level then the canal should be further developed with the taper pin reamer or gouge, without compromising the layer of strong trabecular bone.
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Fig. 4
Fig. 5
Fig. 6
Fig. 7
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8. Trial reduction
The proximal femur is re-exposed and the appropriate head trial is positioned onto t he rasp. A trial femoral head is placed over the spigot and the hip is reduced (Fig. 8). Head trials are colour coded; blue is for a minus (-) neck length, black for neutral and green for a plus (+) neck length.
Correct restoration of leg length may be assessed by comparing the relative positions of the femoral condyles. If the leg has been shortened this can be compensated for by implanting the stem to a higher level. Leg lengthening can be compensated by impacting the rasp further into the femur and repeating the trial reduction. A smaller rasp may be required.
When the correct leg length has been achieved, the trial femoral head is removed and a metal spigot protector is positioned over the neck trial. The stem introducer is mounted onto the metal spigot protector ensuring that it is aligned with the rasp (Fig. 9). The femur can be marked with diathermy and methylene blue dye at the level indicated by the leg length gauge (Fig. 10). Alternatively a K wire may be used. The spigot protector and neck trials are then removed. The rasp handle is reattached and the rasp removed.
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Fig. 8
Fig. 9
Fig. 10
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9. Further Femoral Preparation
The correct intramedullary plug size is selected by using Exeter™ plug trials. The appropriate size of intramedullary plug is mounted on the introducer (Fig. 11A), and driven in 17-18cm distal to the tip of the greater trochanter (Fig. 11B).
A tight fit for the plug is essential. The proximal femoral seal and backing plate are positioned onto the cement gun nozzle. These are placed over the proximal end of the femur to ensure a good fit (Fig. 12A). If a good fit cannot be achieved, the other size of seal should be tried, or the femoral slot altered to ensure a tight seal. If a tight fit cannot be obtained after any of these measures, the use of the gun should be abandoned and the ‘suck-down’ technique should be used with doughy cement and vigorous finger packing. The canal is thoroughly cleaned using lavage. A catheter is placed in the distal end of the canal and connected to suction. Ribbon gauze soaked in 10 vols. hydrogen peroxide is packed into the femur to maintain haemostasis in the canal and to provide a clean dry surface into which the cement can key. The ribbon gauze and suction catheter are removed immediately before cement injection starts.
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Fig. 11A
Fig. 11B
Fig. 12A
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10. Femoral Cementing
Using Simplex® bone cement, the cement should be mixed in a mixing bowl for 1 minute and then poured into the cement barrel, which should be left to stand for 30 seconds. Three mixes may be necessary for large femora. The nozzle is fixed to the barrel, the femoral seal and backing plate positioned, and the cement gun is primed. Cement is introduced in a retrograde (ie. from distal to proximal) fashion (Fig. 12B). Typically, using Simplex® bone cement and with a theatre temperature of 21°C, this is usually 21⁄2 to 3 minutes after commencement of mixing. As the cement reaches the upper part of the canal, the nozzle of the gun is cut off distal to the femoral seal.
The femoral seal is then impacted forcibly onto the upper end of the femur, and the remaining cement is slowly pumped into the femur (Fig. 12C). This action will maintain a steady pressure to overcome the bleeding pressure inside the femur. When pressurisation is correctly performed, a steady extrusion of fat through the walls of the upper femur may be seen.
Cement injection and pressurisation is continued until the viscosity of the cement starts rising. Typically, using Simplex bone cement and with a theatre temperature of 21°C, this is seldom less than 6 minutes from commencement of mixing, judged by a small sample held in the hand. The femoral stem is then inserted.
The aim should be to delay stem insertion as long as possible remembering that during stem insertion interface pressures in the canal are directly related to the viscosity of the cement.
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Fig. 12B
Fig. 12C
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11. Stem Implantation
The hollow centraliser must be used with the Exeter™ stem. Each Exeter™ V40™ stem is supplied with a winged and a wingless centraliser. If an intramedullary plug of less than 10mm is used it may be preferable to use a wingless centraliser. The use of the hollow centraliser prevents ‘end-bearing’ of the stem, and ensures that the proximal, expanded taper of the stem will engage properly in the cement mantle. The selected stem is mounted on the introducer. It is important to note that the handle of the introducer is exactly in the mid-line of the stem and so the introducer and the stem can be lined up with the medullary canal of the femur. The stem introducer can be used with one hand, and has a smooth trigger action which releases the introducer pin from the dimple in the lateral shoulder of the stem implant. The stem is introduced through the proximal femoral opening closer to the posterior femoral cortex than the anterior, and aiming at the middle of the popliteal fossa if the Southern or posterior approach is used, or the patella if the direct lateral or lateral approach is used (Fig. 13).
The stem can be driven into the canal through the stem seal and its backing plate which should be held firmly in position on the cut surface of the femoral neck. Otherwise the stem is driven into place with the surgeon’s thumb occluding the medial exit from the upper end of the femur between the stem and the calcar, to further pressurise the cement into the cancellous bone (Fig. 14A). During stem insertion, there should be further extrusion of fat through the walls of the femur.
The insertion should be brisk until the stem reaches a position approximately 1cm. above its final position. Insertion thereafter should be slower, gradually bringing the stem to its final predetermined position as judged by the leg length gauge (Fig. 14B). The femur can be marked with diathermy and methylene blue dye at the level indicated by the gauge.
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Fig. 13
Fig. 14A
Fig. 14B
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When the final position has been reached and the introducer removed, the stem seal and backing plate are positioned and firm pressure maintained on the top of the cement until it polymerises (Fig. 15A, B & C, D).
Ensure that the stem does not back out during cement polymerisation.
The surgeon may wish to use the stem seal pusher to apply firm pressure onto the stem seal until the cement polymerises (Fig. 16). The surgeon should remove all cement from the cut surface of the cortical calcar.
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Fig. 15A,B,C,D
Fig. 16
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12. Reduction
The spigot protector is then removed and the spigot thoroughly cleaned. A further trial reduction may be carried out using the appropriate trial heads on the V40™ spigot. Checks are then made again for correct leg length and stability. educed and increased neck lengths are available. The appropriate size of femoral head is removed from its packaging and placed over the stem spigot. It is secured in place by firm blows with the palm of the hand. Alternatively, the head may be pushed on by hand & rotated 10º. Neither excess force, impaction nor hard instruments should be used as this may damage the fine polished surface (Fig. 17).
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Fig. 17
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