Variables affecting initial stability of impaction grafting for hip revision

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Bone Grafting Techniques

Background:

• Impaction grafting is used for bone stock restoration in hip revision surgery.
• Early massive subsidence has been reported, raising concerns about implant stability.

Purpose of the Study:

• To identify prognostic factors for stem and cup migration after impaction grafting in hip revision.
• To analyze the relationship between surgical variables, patient characteristics, and implant migration.

Main Methods:

• A cohort of 56 hip revision patients undergoing impaction grafting was followed for 1-5 years.
• Stem and cup migration were assessed and correlated with 13 potential predictors, including stem design, positioning, femoral anatomy, patient factors, and bone graft density.

Main Results:

• All significant migration occurred within the first 3 months post-surgery.
• Average stem alignment change was 4.8 degrees, with age, femoral diameter, stem design, and graft density explaining 50% of this change.
• Average stem subsidence was 2.7 mm and average cup migration was 3.0 mm.
• No predictors explained the variability in cup migration or distal stem migration.

Conclusions:

• While certain factors predict stem alignment changes, cup migration and distal stem migration variability remain unexplained.
• Assessing implant stability during surgery may be crucial for mitigating unpredictable migration.