Anteversion of an acetabular component is often difficult to ascertain in THA patients in whom excessively anteverted or retroverted femurs may result in limited ROM or risk of dislocation. Restriction of motion, however, is determined by the combination of version of both components.
The patient shows cup loosening in Gruen zone III.

This situation can occur when the initial press- fit is not adequate, the bone quality is poor, and when socket stability relies on the polar screws.
The cranial migration of the rotation hip center is associated with an increased angle of inclination of the cup and, as in this case, there is a dislocation of the prosthetic head due to the action of the abductor muscles. The surgeon, seeking the greatest amount of host bone, must restore the anatomical level of the hip center and ensure that the cup provides adequate coverage of the prosthetic head, with both angle of inclination and anteversion in line with this objective.

Also, it is of paramount importance to obtain the appropriate combined anteversion (anteversion angle of the socket plus anteversion angle of the stem), which should not exceed 30 degrees to ensure the stability of the joint in revision cases (Matsushita A, et al. Clin Orthop Relat Res. 2010). The Lima REVISION System, including both the DELTA-REVISION TT cup and the REVISION stem, easily solves the two most important issues in the case report: 1) defect in the acetabular roof (Paprosky IIC); and 2) joint instability.

The DELTA-REVISION TT cup allows a Trabecular TitaniumTM augment to be added on the top by means of small screws. This augment perfectly fits the defect in the host bone and leaves the liner in the correct orientation. The lower hook and upper fins tighten the cup host bone, providing adequate stability. However, since the the cup maybe conditioned by the to the primary orientation of defect, this must be compensated on the femoral side to avoid joint instability.

The surgeon can choose any degree of neck-anteversion thanks to the modular REVISION stem. Furthermore, the 4-degree slope at the trunnion formed by the two stem-components (diaphyseal and metaphyseal) can also direct the metaphysis in flexion, extension, varus or valgus depending on the most appropriate position for each case. The different sizes of the proximal component ensure the correct leg length.