Total Hip replacement- C stem AMT-Elite (Depuy) cemented hip (femur first)

The patient is placed in the lateral position with a bolster applied over their sacral lumbar junction as seen in the picture. The lower limb has a TED stocking and a Flowtron around the calf. There is a prop placed anteriorly on the anterior superior iliac spine. The aim is to position the pelvis in a perpendicular position to the flat operating table. The uppermost anterior superior iliac spine should be positioned exactly above the lowermost anterior superior Iliac spine (ASIS).

Prior to surgery it is prudent to check the patient’s leg lengths in the floppy lateral position as shown above. Make sure to abduct the leg to get a true reflection of the leg length. Remember this length for comparison later in the case.
Prior to positioning it is important to check the patient’s leg lengths when they are supine prior to positioning this will identify if the leg is shorter/longer or equal relate the clinical picture to pelvic radiograph to plan your operation.

Pre-operative radiograph confirms diagnosis – Osteoathritis, radiographic features are osteophytes, subchondral sclerosis, cysts and loss of joint space.

Computerised templating. Use the radiograph in conjunction with your clinical findings to assess leg length and plan your mechanical reconstruction. Template for cup size and orientation, template for femoral stem size, offset and leg length.

Pre-operatively test of the stiffness of the hip. The hip here has been put in to internal rotation. Rotate the leg internally until it reaches its maximal rotation. If the angle of internal rotation is low the chances of dislocation are much less.

The patient is prepped and draped. Prior to this 2% Chlorhexidine prep has been applied to the skin. An Ioban preparatory skin drape (Iodine impregnated) has been applied to the thigh. The incision has been marked on the patient. The incision is centred over the tip of the greater trochanter, distally the incision is straight in line with the vastus lateralis fibres and proximally the incision curves towards the posterior iliosacral joint.

Incision through the skin into the fat. Cut perpendicular to the skin, if the dermis is not cut perpendicular the skin edges are harder to close.

The fascia lata is identified and a fasciotomy is made with the scalpel. The fascia lata is then opened with the use of dissecting scissors both distally and proximally (as shown) in the line of the skin incision. Proximally the fibres of gluteus maximus are split in the direction of its fibres using blunt dissection.

A Charnley Bow retractor is applied with an anterior curved leaf under the anterior fascia lata. Posteriorly a “squared” leaf of the retractor is applied under the posterior edge of the fascia lata taking care not catch and damage the sciatic nerve by delving deeply and blindly with the retractor. The sciatic nerve exits the pelvis through the lower part of the sciaitic notch. It is particularly at risk during the posterior approach to the hip. Identify the nerve at this point to identify where it is before proceeding, if it looks small it may of divided into its tibial and common peroneal branches before piriformis. The nerve appears below the piriformis muscle and lies over superior gemellus, obturator internus, inferior gemellus and finally the ischial spine.

The posterior aspect of the greater trochanter is shown after the trochanteric bursal tissue has been removed.

For the posterior approach to the hip the piriformis tendon is identified as shown. An incision is made in line with the piriformis tendon over its superior border. In this photograph we have a Langenbach retractor holding the gluteal musculature. Internally rotate the femur to lengthen the tendon and aid identification. The piriformis tendon can be found by palpating the greater trochanter and when you feel a small “nipple” of bone the tendon is adjacent to this. Once the fat is swept/dissected off the tendon it is readily seen.

This image shows the position of our retractors. A sharp Hohmann is placed superior to the piriformis tendon placed in the incision made in step 9. To achieve this pass the curved dissecting scissors into the incision you have made with them superior to the piriformis tendon next place the sharp Hohmann retractor over the scissors into the same space, then remove the scissors. To insert the distal Hohmann retractor use the curved dissecting scissors to enter the space between the joint capsule superiorly and the quadratus femoris muscle inferiorly. A blunt Hohmann is then placed in the same tract made by the scissors and the scissors are then removed in essence swapping the Hohmann retractor for the scissors.

A 2 Vicryl stay suture is applied to the piriformis tendon using 2 “throws” of the suture into the tendon as close to its insertion on the greater trochanter as possible. Maintain as much length of the tendon as you can.

Now an arthrotomy is made as an L-shaped limb starting proximally at the edge of the acetabulum heading towards the tip of the greater trochanter, the arthrotomy is then continued distally along the edge femoral neck until the quadratus femoris muscle is reached. Inferiorly and distally there is often a venous vessel which bleeds – this will require diathermy.
A second stay suture is now applied to the joint capsule along its free edge after the arthrotomy has been performed.
Using the two stay sutures that are now in place reflect the tissues posteriorly to protect the sciatic nerve throughout the rest of the operation.

The femoral head has been dislocated. The head is marked with annotation F, the dislocation manoeuvre is to internally rotate the hip as it is adducted over the lower limb. Note – if this is a protrusio case it may be prudent to cut the femoral neck insitu prior to dislocation. If there are excessive osteophytes posteriorly sometimes it is necessary to remove the osteophyte rim from the posterior acetabulum wall with an osteotome first. Both these manoeuvres are there to prevent fracture of the femur or posterior acetabular wall during the dislocation manoeuvre.

Cut the anterior capsule fibres, under quadratus femoris. This release aids femoral head exposure by allowing increased rotation of the femur.

An osteotomy is made with the sagittal saw at the level of the neck cut as per pre-operative templating. Measure up from the lesser trochanter to your planned resection level. A neck resection guide is available for this system.

Sometimes a superior osteotomy into the femoral head neck junction is required to complete the femoral neck osteotomy to remove the femoral head as shown above. This osteotomy is made only when the first osteotomy does not completely separate the femoral head from the neck and is only a few mm in depth – use an osteotome 1.5 to 2cm in width.

Use the osteotome in the gap made by the sagittal saw to release the femoral head. Sometimes fibres remain attached infero-anteriorly which require incision with either a Bovie or scalpel to complete the femoral head resection. Keep the femoral head available until the end of the case in case you need bone graft later in the case.

In this total hip replacement we are performing the stem first. This is only possible in modular broach designs such as the C-Stem AMT used in the case. The image highlights the position of the Muller retractor with the two prongs placed either side of the calcar just superior to the lesser trochanter. Annotation E – is the entry point for the box chisel see next slide.

Resect any remaining soft tissue from the piriform fossa. A box chisel is then utilised to start the femoral canal preparation. Aiming from the starting point E and dialling in the version of the stem you wish in the canal proximally. Use the box chisel to remove the metaphyseal bone remaining proximally.

Second stage of canal preparation is to use the pencil reamer. You will know you are in the correct place as the pencil reamer will easily follow a correct path of least resistance in most typical canals.
The previous entry point with the box osteotome ensures you will be correct in the lateral position and pencil reamer will pass easily. If the pencil reamer does not pass easily, you may have started in a poor position, the patient may have a tight femoral canal or there maybe an overhanging trochanter.

The canal proximally is widened with the second pencil reamer on the C-Stem AMT set. Use this in a clockwise direction once the top of the reamer has reached the level of the osteotomy there is no need to go further, if the canal is tight you may not reach this depth.

Final canal preparation before broaching shows a Charnley curette in the femoral canal this is utilised to remove loose cancellous bone both in the lateral aspect of the canal and the medial aspect of the canal as seen in image 23. Remove all loose cancellous bone.

Medial cancellous bone removal with the curette.

First broach applied into proximal femur. Hammer the broaches in until you have the desired size. This will be guided by your pre-operative templating. However intraoperatively if the broach has a nice snug fit and is down to the level of your resection then do not force a large broach into the canal as you risk fracture. Sizes range from 1 to 8. Men typically are in the larger sizes, rarely an 8 is used. The commonest size for a female is 2 and for a male is size 3/4.

The broach is now left insitu and we will return to the femur later. In this case there was no need for any calcar planning. However the C-Stem AMT does have a machine driven calcar planar to allow you to plane the remnants of the proximal femur flush with the implanted C-Stem broach, it was not required in this case.
I prefer to use a narrow No7 retractor of the Stryker minimally invasive instrument set. This is a narrow and large curved sharp ended retractor. The sharp end is placed over the anterior aspect of the acetabulum and inferior to trunnion of the C-Stem AMT broach left in-situ. The retractor is pulled anteriorly while the leg is abducted and externally rotated. The femur is now anterior to the acetabulum. Warning do not pass the retractor aggressively over the anterior margin of the acetabulum – femoral nerve neuropraxia has been described.

A Judd pin has been inserted in to the ischium. To insert this Judd pin place the tip of the pin inside the acetabulum gradually walk it back until you go over the acetabulum margin posteriorly in the space before the short external rotators are and then aiming for the ischium hammer the pin insitu this acts as a retractor.

A superior Judd pin has also been placed. Use the tip of the pin to go superior to the acetabulum under the gluteal musculature aiming to retract the gluteal muscles with the pin once it has been hammered into the ilium.

A long handled scalpel is now used to dissect the remnants of the labrum away from the acetabulum in a 360o fashion. Sometimes you might need to release the reflected head of rectus femoris to allow the femur to mobilise forward to gain better exposure of the acetabulum. The reflected head is extra-arcticular on the superior anterior margin of the acetabulum – release the fibres by sharp dissection onto the bone.

The transverse acetabular ligament is identified. This is a valuable landmark for cup positioning (reference 1). Aligning your acetabular component with the transverse acetabular ligament seems to be the optimal cup position for specifically reducing dislocation rates (0.6%).

Acetabular preparation now starts after the foveal ligament remnants have been excised in the base of the acetabulum the first reamer is used to remove the sclerotic bone and remnants of cartilage in the foveal fossa. subsequent reamers are used to widen the acetabulum until good cancellous bleeding bone is seen circumfrentially in the remaining acetabular bone. As this is a cemented technique a perfect sphere is not required, sometimes a slightly ovoid acetabulum remains, the most important factor is to remove all sclerotic bone and soft tissue.

Once serial reaming has been performed to expand the acetabulum and a cancellous bone bed is left. To gain optimal cementation you must place multiple keyholes into the circumference of the acetabulum. Care being taken not to go through the medial wall. The medial floor is the thinnest area and it would be perforated by this drill. The acetabulum should look like a watering can head with the number of keyholes made.

Pre-formed elite cup is shown. On the posterior aspect there is a raised lip which should be placed along the posterior wall of the native socket. Ensure correct orientation of the cup between left and right sides. Choose a cup based on your acetabular reaming, it is recommended that the reamer should be 6mm greater than the outer diameter of the cup. The commonest Elite cup sizes are 43mm, 47mm, 50mm and 53mm.

The flange around the elite cup has been cut to allow for cup seating in the acetabulum superiorly there is a remnant of flange left to ensure good pressurisation during the cementation and complete coverage superiorly. Rarely you need to leave flange inferiorly or anteroposteriorly but should be utilised if there are defects in the acetabular wall margins.

The acetabular component is now mounted on the acetabular introducer. Some surgeons find it easier to cut the cups flange with the cup mounted.

Trial reduction of elite cup in to socket. Ensuring that the cup is aligned with the transverse acetabular ligament and the cup is not open.
The anterversion of the cup should be about 15 to 20 degrees – this is typically the orientation of the transverse acetabular ligament (TAL). If a native acetabulum is retoroverted do not use the TAL as a guide. Also aiming for an inclination angle of approximately 45o this is guided by the handle which should be parallel to the floor of the operating room. Check that the flange covers any defect superiorly and furthermore check that no further rim of the cup needs to be excised.

The position of cup is confirmed with its relationship to transverse acetabular ligament (annotation A), the cups face should be aligned with the TAL and its inferior border should sit below the TAL. Once you are happy with the cup position you may then proceed to cementation.

The acetabulum has been lavaged with pulsatile chlorhexidine and is now being dried with a dry swab in the acetabulum and sucker in the base of the socket. Some designs allow for a suction catheter to be implanted in to the patient’s ilium to allow the cement to be sucked further in to the cancellous bone during cementation. This has not been used in this case.

First test your patient’s leg lengths. There is no point continuing if the leg lengths are grossly long or short at this point one must readdress your femoral stem if this is the case. As the leg lengths are equal here we proceeded to test the hip for stability. Next test for abductor subluxation (Shuck test). With the leg in neutral and slightly abducted leg test for femoral head distraction from the socket. If there is no distraction then the offset and or leg length may be too much, if there is more than 0.5cm of distraction then the offset and or leg length may not be adequate. Test again with different head sizes, different neck offsets and consider repositioning the stem to obtain optimum stability and leg lengths.

Once the high viscosity cement has been vacumn mixed (in this case Palacos) the cement at approximately 2 minutes 15 seconds is then placed in to the acetabulum. Clean any blood off the cement at this stage with a dry swab.

This is the acetabulum cement pressurisation system. It is a rubber bung on the end of an introducer that allows for good pressurisation of the cement into the cancellous bone.

The cement is pressurised using the rubberised pressuriser for until approximately 3 minutes and 30 seconds after the cement mixing started.
The image shows the acetabular component mounted prior to being compressed in to the acetabular cement. Place the leading edge of the cup inferiorly into the cement mantle, once it is seated below the TAL close the acetabular component into the cement mantle – do this by using the pusher instrument to close the cup. Whilst this is occuring ensure correct alignment with the TAL by “steering” the introducer to the correct position. Once the cup is closed removed the introducing handle.

Now continue pressurisation of the cup using a correctly sized ball for the inner diameter of the cup on a introducing stick.

Position of cup at final cement curing again aligned with transverse acetabular ligament.

As we have already prepared the femoral stem and left the broach insitu we are now able to apply a modular neck and head to the stem. We can now test the stability and leg lengths of our hip reconstruction. Use the femoral neck as per pre-operative templating and femoral head size, in this case the 32+9mm femoral head is being trialled.

Testing for an anterior dislocation in the leg extended position and fully externally rotated leg the implant construct should not dislocate – this is an exaggerated example the surgeon is standing away from the patient for the purposes of the photograph. If there is any dislocation in this manoeuvre it is imperative that you address your component positioning as a hip performed through the posterior approach that dislocates anteriorly at this point is a highly unstable construct and will dislocate.

Sleep test with the leg adducted over the contralateral limb hold the foot and internally rotate the foot, at this point, allow the leg to flop in to this position and the hip should be stable.

With the hip flexed at 90o gradually internally rotate the hip until it dislocates. Please refer back to the original degree of internal rotation of the hip prior to surgery as seen in image 3. You should aim for a minimum of 30o greater than the IR range pre-operatively in the stiff hip. In the mobile hip prior to surgery one must get a significantly higher arc of internal rotation to be acceptable aiming for between 70 and 90o.

We are now happy with the hip in terms of its stability and leg length and therefore we can finish the femoral preparation. A Hardinge cement restrictor is now inserted down the femoral canal to 16cm. C-Stem specific cement restrictors are available and are measured using a sound down the canal. I prefer the one sized Hardinge cement restrictor. You may trim the Hardinge restrictor, however I only ever consider this in the tightest of femoral canals.

Further canal preparation, the canal is lavaged with a pulsatile long nozzeled jet as shown. This removes loose bone, debris, blood and fat from the cancellous bone.

A suction catheter is the inserted down the femoral canal and the femoral canal is then packed with a rolled swab. This occurs while the cement is being mixed by the scrub team.

The C-Stem AMT with appropriately sized cement centraliser applied to the stem distally. The cement restrictor is sized by using sounds which are on the tray.

Cementation of the femoral canal – the cement is applied in a distal to proximal direction after 2minutes and 15 seconds from the start of mixing. Place your nozzle of your cement gun down the femoral canal withdraw to approximately 1cm prior to instilling cement this allows blood pooling distally to be sucked up. Instil the cement and ride it almost like a surf wave allowing the canal to fill from distal to proximal. Whilst leaving the suction catheter in situ.

The canal has now been filled with cement.

Cut the tube of your cement gun off and follow with pressurising of the cement in the femoral canal. Pressurise the canal with one movement of the gun handle and then remove the venting tube whilst pressuring. Allow pressurisation up to 3 minutes and 15 seconds.

The forceps show the correct entry point of the femoral stem if you go to the posterolateral corner as identified you will allow your stem to be perfectly positioned in the AP and lateral projections.

If you are teaching a trainee to perform this operation, place your thumb over the cement manltle in such a way that only that posterolateral corner of cement is visible. Then you force your trainee to put the stem in the correct starting position. Furthermore as the stem is introduced in its early stages keep your thumb here to allow some degree of pressurisation.

The C-stem AMT is now implanted in correct anteversion and length as per trialling. The white handle is the C-stem introducer.

The cement is now cured and the stem is in the correct position. Ensure that the cement has cured prior to any further work.
Typically the Palacos cement used in this case would be cured around the 10 minute mark but may take up to 11-12 minutes depending on theatre conditions. The cement curing around the femoral stem is longer than around the polyethylene cup on the acetabulum as the femoral stem acts as a heat sink whereas the polyethylene cup acts as a thermal insulator speeding up the cements exothermic reaction.

Repeat trialling the femoral head. In this example a 32+5mm trial head is being used, Once you are happy with the construct clean the trunnion and apply the definitive femoral head in a twisting motion on the clean trunnion impacting with one large heavy blow. Multiple blows are not encouraged.

Using 2 drill holes through the lateral aspect of the greater trochanter make two passages for the superior and inferior limbs of the stay sutures attached to the short external rotators and piriformis tendon.

Using a suture passer the stay sutures are returned through the greater trochanter via the two drill holes.

This shows the stay sutures being passed through the lateral aspect of the greater trochanter with the ceramic head applied to the femoral stem enlocated in the Elite cup.

The short external stay sutures have been tied over the greater trochanter as seen by the knot above and the posterior repair is now sound.

The fascia lata is closed with a continuous loop PDS suture.

The fat layer has now been closed using a continuous 0 Vicryl suture.

The skin is now closed using a 2/0 quill subcuticular suture running in the dermal layer and then returning back in the skin layer. The skin is now closed.

Tissue glue has been applied followed by the steristrips.

Dressing.

Post operative radiograph (AP pelvis and lateral view). It is important to look for the following features.
Cement mantle around acetabular component
Cement mantle around femoral component
Leg length compare heights of lesser trochanters
Offest of construct
Ensure head is enlocated correctly in the socket.