Few things about reporting unicompartmental knee radiographs

Tibial component
medial to the medial spine.
extend to the medial margin of the tibia or by up to 2 mm.
reach the posterior cortex of the tibia
a few millimetres away from the vertical wall
Femoral component
overhang the bone 2–3 mm proximally.
No retained osteophytes posteriorly.
Alignment
is not critical because of the spherical shape of the femoral component.
Malalignment of the femoral component of up to 10° is acceptable.
Malalignment of the tibial component of up to 5°is acceptable.
Cement
Good cement penetration round the components
Excess cement should have been removed.
Tibia cuts 

should not extend too deep as they can lead to tibial plateau fracture.

Radiolucencies

Particularly under the tibial component, are common.Physiological radiolucencies are typically 1mm thick and have a dense sclerotic margin. They can be up to 2mm thick. They are commonly partial but occasionally complete. They tend to develop during the first year and consolidate in the second. Thereafter they remain static.
Pathological radiolucencies are much thicker and do not have a well-defined border. They are progressive and are associated with real problems such as loosening or infection.
Wear

Not a recognized complicationBearing dislocation
diagnosed by the radiopaque markers being displaced. The bearing may dislocate or sublux in any direction including into the intercondylar notch.

An example of reporting template:
The tibial component is medial to the medial spine, extends to the medial margin of the tibia, and reaches the posterior cortex of the tibia - all within normal limits.
The femoral component hangs outside the articular surface by 5.8 mm and is unchanged - stable appearance.
No retained osteophytes posteriorly.
The tibial and femoral component alignments are within acceptable range.
There is good cement penetration round the tibial component.
The tibial cut appears appropriate.
On the AP view, there is lucency around the femoral component, measuring up to 3 mm laterally and up to 6 mm medially, but there is no lucency on the lateral view. This needs clinical correlation for any symptoms and signs of loosening. If the plan is to observe, a serial radiograph would be useful in 3 months. If the clinical symptoms and signs are suggestive of loosening, nuclear bone scan and/or weight bearing varus/valgus strain can be useful.
No evidence of bearing dislocation.

Reference: Read the article here