Radiological assessment of bone quality and bone remodeling after primary and revision hip replacement

Abstract

The minimum follow-up was two years. Follow-up was carried out at 6 weeks, 3 months, 6 months 1 year postoperatively and yearly thereafter. Radiological assessments were performed for stability of the cage, graft and component loosening, and for bony remodeling on the graft-host/cage-host/cage-graft interfaces. Main functional outcomes were the Oxford Hip Score (OHS) values. Complications were noted.Our third study included revision THA cases operated between January 2015 and December 2017 using the Wagner Self-Locking (SL) monoblock stem, which is a tapered and fluted titanium stem, well suited for use in both AL and periprosthetic femoral fracture (PFF) cases of the proximal femur. A thorough follow-up was performed at 3, 6, 12 and 24 months after surgery and yearly thereafter. Main radiological result was an objective evaluation of bone stock via Secondary Bone Stock (SBS) and Osteointegration and Secunder Stability (O-SS) scores merged in Global Radiological Score (GRxS). Functional status followed by OHS. Results:We found perfect bone contact around the Proxima stem in every cases immediately after the procedure. The bony integration continued, and was maintained for all cases, except one. The overall malalignment rate reached 12% for all cases. A 7-year Kaplan-Meier survival rate of 97.6% was determined for stem revision. HHS increased an average of 51 points between preoperative test and last follow-up.Around the anti-protrusion cage (APC) we found contact at the graft and the host bones, and satisfactory trabecular formation was observed at the graft-host interface after 24 months. On two occasions there was loosening of the ischial screws, not affecting the overall stability of the implant. OHS values increased significantly.With the use of Wagner SL stem, we found a significant difference between the GRxS results at each 5 timepoints (Friedman x 2 = 70.812; p < 0.001; KendallW = 0.88515/large/). Except immediately after the operation, we found a significant difference between the PFF and AL groups at each timepoint. We observed 89% (17.7/20 points) of bony architecture remodeling after 6 months in the PFF group, whilst the AL cases needed 2 years to reach almost this level of reconstruction (86%, 17.1/20 points). There was no difference in functional outcomes between the groups. Conclusions:The bone preserving Proxima uncemented metaphyseal short stem provides excellent radiological and clinical results in the medium term. To our knowledge this is the