Total Hip replacement- Exeter femoral stem and Tritanium acetabular component (Stryker)

Pre-operative radiograph showing bilateral osteoarthritis of the hips. the right was more symptomatic and is present below. The left has a deformity consistent with a SUFE as a child.

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 in the line of the skin incision. Proximally the fibres of gluteus maximus are split in the direction of its fibres using blunt dissection until you can completely visualise the greater trochanter of the hip when the muscle belly is retracted.

A Charnley bow retractor has been applied, place one leaf anteriorly and one posteriorly under the tensor fasica lata. The trochanteric bursa overlying the greater trochanter is seen. As we are using a posterior approach the sciatic nerve is at risk. Do not delve deeply and blindly with the retractors, instruments or your hands!
The sciatic nerve exits the pelvis through the lower part of the sciatic notch. It is particularly at risk during the posterior approach to the hip. Identify the nerve in the posterior fatty tissue to the greater trochanter before proceeding, if it looks small it may have 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.

Excise the trochanteric bursa with dissecting scissors to reveal the posterior aspect of the femur and its short external rotators.

For the posterior approach to the hip the piriformis tendon (annotated P) is identified as shown. An incision is made in line with the piriformis tendon over its superior border. Place the scissors over the superior aspect of the piriformis tendon and bluntly dissect superio-anteriorly to make a channel for a sharp hohmann to be placed superiorly to the acetabulum.

Once the scissors are in place superiorly, slide a sharp Hohmann retractor over the top of the scissors and then remove the scissors. In this picture the sharp Hohmann(S) is in place and an inferior blunt Hohmann is about to be placed.
A distal Hohmann retractor is inserted inferiorly to the joint capsule.
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. The blunt Hohmann retractor is shown above entering the tract made.

Final position of the superior and inferior Hohmann retractors, with the piriformis tendon and short external rotators displayed between them on the posterior aspect of the joint capsule.

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. Once the suture is in position apply tension to the the suture and incise it as close the greater trochanter as you can, reflect the tendon posteriorly so that you see the posterior hip joint capsule.

Now an arthrotomy is made into the joint capsule. The arthrotomy is 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 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 in situ 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. Just cut the anterior capsule remaining, you will often see a sudden release of tissue with the medial neck being more visible and the femur should protrude slightly more from the wound. Sometimes you may get some venous bleeding from vessels under quadratus femoris, Control this bleeding now.

Sweep the remaining fibres along the medial aspect of the femoral head with a Bristow to expose the medial femoral neck and the upper limit of the calcar.

Apply a blunt Hohmann under the medial side of the femoral neck to allow good visualisation before it is resected.
An osteotomy is made with the sagittal saw at the level of the neck(not shown) and cut as per pre-operative templating. Measure up from the easily palpable lesser trochanter to your planned resection level before cutting to ensure accurate cut placement. Be careful not too “shoot” through with the saw blade as you can damage structures below, such as the obturator vessels.

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.

Anteriorly a retractor has been placed under the femoral neck with its pointed tip just anterior to the anterior aspect of the acetabulum to allow for anterior retraction of the femur and expose of the acetabulum.
Posteriorly a Judd pin has been inserted in to the ischium. If a clockface was centered over the acetabulum, with 12 o’clock being superiorly this in would be inserted between 7 and 9 o’clock.
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 in-situ this acts as a retractor. Extend the hip during ischial pin placement to relax the sciaitic nerve and decrease the risk of nerve injury.

This is an example of a trial head applied to Exeter broach, outside of the patient, to demonstrate its appearance.

A superior Judd is now 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 and angled perpendicularly to the ischial bone. Clock face position between 12 and 3 o’clock.

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. Approximate position of reflected head (R).

Use a Bovey to remove the foveal tissue and ligament in the base of the acetabulum to expose the floor of the acetabulum and the the transverse ligament.

The transverse acetabular ligament(T) is identified.
This is a valuable landmark for cup positioning as reported in the seminal paper by Beverland and his team. Aligning your acetabular component with the transverse acetabular ligament seems to be the optimal cup position for specifically reducing dislocation rates (0.6%).

The Transverse acetabular ligament: an aid to orientation of the acetabular component during primary total hip replacement: a preliminary study of 1000 cases investigating post-operative stability.
Archbold HA, Mockford B, Molloy D, McConway J, Ogonda L, Beverland D .J Bone Joint Surg Br. 2006 Jul;88(7):883-6.

Note the camera view is now on the anterior side of the patient in the this picture.
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. Reaming for the tritanium shell should be 1mm less than the shells outer dimension, or line to line when hard bone is encountered.

Acetabulum after reaming. Aim for good exposed cancellous bone circumferentially. Ensure no soft tissue is around the edges of the acetabulum.
Windowed trial shells are available to assess your cup size, assessment of fit, congruency and position prior to implantation of the definitive cup. The windows allow the surgeon to confirm seating of the component down onto the acetabular floor. They have not been used in this case as the reaming was optimal and surgeon experience allows this step to be omitted. This is due to surgeon training, experience and preference.

The Tritanium cup is shown. It has been mounted on a straight introduction handle.
Avoid catching the back of the shell on retractors and soft tissues prior to entering the mouth of the acetabulum. Ensure the patient hasn’t moved from your original placement on the operating table as this will affect where you are placing the cup.

Impact the acetabular shell aiming for 40-45 degrees inclination and aligning the face of the shell to the transverse acetabular ligament (reference 1).
Ensure the cup is fully seated, be careful if during impaction significant resistance is met – ensure no soft tissue has been dragged in behind the shell and that the acetabular preparation is correct. If you have reamed 1mm under the shell size and the cup is difficult to impact ream line to line and retry cup insertion. It has a rough surface to allow for frictional fit and initial stability and may require line to line reaming in harder bone. Cup positioning can be helped by applying the CuttingEdge Abduction/Anteversion Alignment Guide to the impactor handle (Note this can also be applied to the trial windowed shell handle). Once the shell has started to enter the acetabulum confirm you are happy with its alignment before final seating into the floor of the acetabulum. It is easier to reposition now before final seating.
If the cup is not stable once impacted augment its stability with cancellous bone screws through its cluster holes. In this case the cup was stable and no screws were required. Screw holes are drilled with a 3.3mm drill bit and the screw depth is then measured. Screws are 6.5mm in diameter and the lengths available are 16mm, 20,25,30,35,40,45,50,55 and 60mm.
The Tritanium cup is available as a hemispherical solid back shell, or with cluster holes. It can be used with polyethylene or a ceramic insert. It comes in 2mm incremental sizes ranging from 44mm to 66mm.

Insert your chosen liner.
In this case I am using a X3 (Stryker Tm) polyethylene liner with an inner diameter of 32mm. Align the indentation in the polyethylene (I) with the Barbs (B) of the shell. Four alignment barbs are present on the rim of the shell.
Polyethylene liners can come in neutral, 10 degree elevated or elevated rim types. Inner diameters include 22,26,28,32,36,40 and 44mm. A 32 mm inner diameter liner is only possible with shell sizes of 46mm or larger.
Ceramic liners have inner diameters of 28,32 and 36mm.
The choice of liner should be based on both patient factors and surgeon preference. Ceramic liners have a small risk of fracture, whereas polyethylene liners may wear out quicker. The combination of a ceramic head and polyethylene liner is becoming the optimal choice of bearing as ceramic heads rarely fracture and have lower wear rates than metal heads when combined with a polyethylene liner.

Once the polyethylene is aligned in the shell, impact it into the shell using the impactor shown above, use the correct size ball to match the inner diameter of the polyethylene.
Confirm seating of the liner 360 degrees around the shell, ensure the taperlock mechanism is working by running a small osteotome between the shell and liner ensuring no separation occurs.

The image highlights the position of the Muller retractor (M) with the two prongs placed either side of the calcar just superior to the lesser trochanter.
The forceps shown point to 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. Version of the femoral stem should be around 15 – 20 degrees – to mimic the natural version of the femoral neck.

Typical amount of bone removed when using the box chisel.

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.

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.

Good clearance of cancellous bone from the lateral side of the femur.
This will allow easier and straight placement of the femoral broach avoiding varus stem position.

Utilising the femoral broaches of the Exeter stem system.
Use serial broaching to prepare the femoral canal. The femoral canal is serially broached starting with an Exeter 37.5 stem 0. Smaller patients can start with the 35.5 broach.
Ensure the serial broaches used are placed in the correct version for the patients femoral canal.

Final position of Exeter stem broach in femoral canal.
Ensure the centre of rotation of the femoral stem replicates the natural centre of rotation of the patients femoral head by inserting the stem to the correct length and using the correct offset stem. Final stem size in this case was an Exeter 44 No 2.

A 32mm plus 0 head trial head has been applied to the Exeter stem.
The hip has now been reduced. Test the hip for stability.
See the Exeter/Gap cage II technique on OrthOracle for description and pictures of stability testing:
Exeter stem (Stryker) and Gap II restoration acetabular cage (Stryker) for acetabular metastases.

I am now happy with the hip in terms of its stability and leg length and therefore can finish the femoral preparation.
The hip is carefully dislocated and trial femoral component removed to allow definitive preparation of the femoral canal.
A Hardinge cement restrictor is now inserted down the femoral canal to 16cm. Exeter canal restrictors exist. 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.
The femoral canal is then packed with a rolled swab. This occurs while the cement is being mixed by the scrub team.

Cementation of the femoral canal.
The cement is applied in a distal to proximal direction after 2 minutes 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 is now filled with cement. Leave the venting suction catheter in until the cement has been pressurised.

Cut the tube of your cement gun off and follow with pressurisation 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.

Cement after pressurisation filling the femoral canal. 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.

The Exeter stem has now been opened and is mounted on its introducing handle.
Note the plastic protector on its trunnion and distal centraliser. Two centralisers exist and come in the stem’s packet, one has 3 flutes (as shown) and one is unfluted – this should be used in narrow femoral canals.
The Exeter stems are 150mm long and have offsets of 37.5mm, 44mm, 50mm and 56mm. In each offset range their are differing sizes ranging from 0 through to 4 for the 37.5mm stem, 0 to 6 for the 44mm stem, 1 to 5 for the 50mm stem and 1-2 for the 56mm offset stem. (Smaller stem sizes are available 30,33 and 35.5mm). It is a modular stem with differing head size options available.

The Exeter stem is inserted in to the cement at 3 minutes 15 seconds starting at posterolateral corner with the tip of the implant.
This will allow you to have the stem in correct AP and lateral alignment. Insert the stem in the same version and depth as per trialling.

Once the cement has cured remove the stem holder.

Local anaesthetic and adrenaline injected into the subcutaneous tissues.

Once the cement has cured retest the the hip replacement construct with trial heads.
Once stability and equal leg lengths has been confirmed the definitive ceramic head is applied to a cleaned and dried trunnion with one heavy hammer blow. A 32 + 0mm ceramic head was accepted.

Hip enlocated ensure no loose pieces of tissue/bone or cement are in the articulation. Ensure the posterior structures haven’t “folded” into the joint.

Posterior repair, the stay sutures are pulled through two greater trochanteric drill holes. Place the superior limbs of the two stay sutures through the superior hole and then the same for the inferior sutures.

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.

Next close the fat layer – closed with continuous 0 Vicyl.

The skin is now closed using a 2/0 quill subcuticular suture running in the subdermal layer first.

The skin is now closed using a barbed 2/0 quill subcuticular suture returning back in the skin layer.

The skin is now closed. Tissue glue is applied to the wound.

Dressing applied to wound after tissue glue and steri-strips have been applied to the wound.

Post-operative AP radiograph. Analyse for stem position, cup position, to exclude fractures and for appropriate “biomechanical” reconstruction (in particular stem offset and leg length).