Pre-Operative Planning

Pre-operative templating will usually allow the surgeon to select the implant sizes appropriate for the hip to be reconstructed and to plan the position in which the cup should be placed.

Acetabular preparation: The true acetabulum should be identified. In complex cases the position of the transverse acetabular ligament is useful in establishing the position of the true acetabulum. Peripheral osteophytes should be removed. The true floor of the socket should be identified by  removing  any curtain osteophyte using either reamers or gouges.
Acetabular reamers are then used to remove articular  cartilage and, where possible, subchondral bone. Cancellous surface should be exposed wherever possible with the exception  of the true medial wall. The reamer should be used at 2mm increments ensuring that the anterior and posterior walls are not overreamed.
A cup size identical to or 2 mm smaller than the acetabular reamer is usually appropriate.A trial cup is  placed on the introduced and inserted into the prepared acetabulum in a position of 45° adduction and approximately 30° of flexion as indicated by the acetabular introducer in the correct position. There should be a small space around the trial socket for the flange.
Multiple fixation pits are made using the acetabular step drill, smaller drill holes are made around the rim of the acetabulum using the distal end of the step drill. Care should be taken not to perforate the inner table of the acetabulum. The wall is thinnest medially and anteriorly. If the cortex is breached, then bone graft should be used to fill the hole.
The trial flange is now placed on the trial cup and both applied on to the introducer. The window on the trial flange should allow the posterior ‘marking’ on the trial cup to be read. The trial flange is now trimmed with scissors to fit the size and shape of the acetabulum
Once trimming of the trial flange is complete, it is placed over the implant and the implant flange is then trimmed to match using scissors.
Final minor modifications may be made at this point. It is important to rehearse cup insertion so that the trimmed flange positions the socket in an appropriate location with the edges of the flange lying just within the mouth of theacetabulum. Th e inferior edge of the socket should lie at the level of the transverse ligament.

Acetabular cementing and pressurisation:

The acetabulum is thoroughly cleaned using lavage. It is irrigated with Hartmann's solution, and packed with swabs soaked in hydrogen peroxide whilst the surgical Simplex® bone cement is being mixed. These swabs are held firmly in place using the cup pusher until the cement is ready to use.
If using Simplex® bone cement it should be mixed for 1 minute, left to stand for 2 minutes and inserted in to the cavity between 3-4 minutes after mixing. A bolus of cement should be left in the acetabulum such that its surface is fractionally below the level of the mouth of the acetabulum. The acetabular pressuriser may then be applied. Over-filling of the acetabulum will result in cement being forced in to the peri-acetabular soft tissues. The cement should then be pressurised with an acetabular pressuriser using full force until the cement viscosity has risen to a doughy state. The sucker aspirator may be used to aid cleaning and drying of the acetabulum. For further details please refer to retractor aspirator op-tech EXEFY04E01.
Typically using surgical Simplex at a theatre temperature of 21°, 6-7 minutes should have elapsed after the commencement of mixing before the socket is pushed into place. A quantity of cement held in the surgeon’s hand will help indicate when the cup should be inserted. The viscosity should be chosen such that significant force is required to introduce the cup into the correct position in the acetabulum.

Acetabular implantation:

The acetabulum is thoroughly cleaned using lavage. It is irrigated with Hartmann's solution, and packed with swabs soaked in hydrogen peroxide whilst the bone cement is being mixed. These swabs are held firmly in place using the cup pusher until the cement is ready for use.
After the cup has been introduced to the pre-rehearsed position, it should be held in place under pressure with the pusher until the cement has fully polymerised. Firm pressure should be maintained on the flanged cup throughout this whole procedure until the cement has fully polymerised.

Final implantation