Partial Knee

Cementing the components
The femoral and tibial surfaces are roughened by multiple small drill holes made with the cement key drill, (fig. 44).

The components are fixed with two separate mixes of cement.

The tibial component
A small amount of cement is placed on the tibial bone surface and flattened to produce a thin layer.

The component is inserted and pressed down, first posteriorly and then anteriorly, so that excess cement is squeezed out at the front.

The right-angled tibial impactor is used (with a small hammer) to complete the insertion.

Excess cement is removed with a small curette from the margins of the component. The femoral trial component is then inserted and the cement is pressurized while it sets by inserting the appropriate feeler gauge. During setting, the leg is held in 45º flexion. Do not fully extend the leg as pressure in this position may tilt the tibial component anteriorly. When the cement has set, remove the feeler gauge and femoral component and look carefully for cement that may have extruded. The flat plastic probe is made to slide along the tibial articular surface, feeling for cement at the edges and posteriorly.

The femoral component
From the second mix, a little cement is pushed into the large femoral drill-hole and the concave surface of the femoral component is filled with cement. The loaded component is applied to the condyle and impacted with the punch held at 30º to the long axis of the femur.

Excess cement is removed from the margins with a small curette.

The cement is pressurized as it sets by inserting the appropriate feeler gauge and holding the leg in 45º flexion, as above. When the cement has set, the feeler gauge is removed. The medial and lateral margins of the component are cleared of any extruded cement. The posterior margin cannot be seen but can be palpated with a curved dissector. The reconstruction is completed by snapping the chosen bearing into place, (fig. 45 & 46). Routine closure of the wound follows.

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