Patient Specific Instrumentation (PSI)

What is Patient Specific Instrumentation (PSI):

One of the important ingredients that makes your total knee replacement into a success is accurate placement of the knee replacement components on your tibia and femur bones.

Using standard instrumentation the placement of the components is already very accurate but with the use of patient specific instrumentation the chances of producing a poorly aligned knee is even further reduced.

The great majority of patients that are a candidate for total knee replacement will be able to have their knee replacement done using Patient specific instrumentation (PSI).

The Surrey Hip and Knee Clinic uses a system that requires a Magnetic  Resonance Imaging (MRI) of the knee, which  is used to produces a 3 dimensional reconstruction of the knee. Also a long leg X-Ray is done which provides information on overall limb alignment.

This information is than processed and the patient specific instrumentation in the form of Nylon cutting blocks are then manufactured which are customised for your knee and fit the bony anatomy very accurately.

Fig 1-1, fig1-2, fig 1-3 below shows the long leg X-ray shows the overall alignment of the knee.


Fig 2-1 & fig 2-1 below show the femoral cutting block is positioned and the resulting bony cuts will allow accurate placement of the femoral component

Fig 3-1 & fig 3-2 below show the tibial cutting block is positioned and the resulting bony cuts will allow placement of the tibial component.

When used during surgery these patient specific cutting blocks allow for accurate placement of the components and in that way optimise the function of the knee replacement.

Mr Busch has published on this and if you wish to see a publication please click below.


Patient Specific Instrumentation paper