Global radiological score for femoral cementless revision stem

The purpose of this study was to evaluate the outcomes of total hip arthroplasty (THA) revision with cementless stems using a numeric global radiological score (GRxS) that summarizes two previously validated scores: secondary bone stock (SBS) and osseointegration-secondary stability (O-SS).

One hundred fifty cases of THA were evaluated at a mean follow-up of 6.5 ± 3.7 years. The GRxS combines the SBS, which evaluated cortical bone thickness, bone density and bone defects in each Gruen zone and the O-SS, which evaluated the location and extent of a single radiolucent line. To calculate the GRxS, the SBS and O-SS were each expressed on a 10-point scale and given equal weighing. The final result was a number out of 20. The GRxS was used to assign a radiological grade to each THA case: very good (20), good (18-15), average (13-12), or poor (≤ 10). The numerical mean (Nm) was calculated for each grade. The inter- and intra-observer reproducibility was evaluated.

The inter-observer reproducibility was good (0.8) and the intra-observer reproducibility was very good (0.9). The GRxS was considered very good in 46 cases (Nm 20), good in 57 cases (Nm 16.6), average in 25 cases and poor in 22 cases. There was a significant relationship between the GRxS and the Harris Hip and Postel Merle d'Aubigné scores (p < 0.0001), and the initial bone stock (p = 0.0001).

The GRxS is reliable and reproducible. This information can be used by surgeons to adapt the surgical technique to bone characteristics (especially during revision cases) and to compare the outcomes of different implant designs.