No Difference in Survivorship Following Primary Total Hip Arthroplasty Using Ultraporous Acetabular Cups and Cross-Linked Polyethylene With and Without Acetabular Screws in a Large United States Health Care System.

BACKGROUND

Modern cementless acetabular cups for total hip arthroplasty (THA) typically have screw options. Historically, screws were thought to improve stability, but came at the cost of pathways for osteolysis. Modern cups and liners may have made both concerns obsolete, and the utility of screws are now contested. We sought to determine modern implant survivorship relative to screw use.

METHODS

We conducted a cohort study. A US health care system's Total Joint Replacement Registry was used to identify patients ≥ 18 years who underwent uncomplicated primary THA for osteoarthritis (2010 to 2021) with an ultraporous cup and cross-linked polyethylene liner, with or without one to two acetabular screws. The primary outcome was acetabular revision for aseptic loosening. Secondary outcomes were aseptic revision for acetabular fracture and any revision for acetabular/femoral loosening and periprosthetic fracture. Multiple Cox proportional hazard regression was used to evaluate revision risk. There were 46,785 THAs identified. Screw use declined from 65.3 to 49.9%.

RESULTS

No difference was observed in 10-year revision risk for acetabular loosening (0.2 versus 0.1%, hazard ratio 1.97, 95% confidence interval = 0.84 to 4.59, P = 0.119). There was one revision for acetabular fracture with and three revisions without screws. There was no difference in risk of overall acetabular or femoral revision, loosening, or periprosthetic fracture. There remained no difference in acetabular-sided loosening between routine screw users and nonusers (0.15 versus 0.06%, hazard ratio 1.26, 95% confidence interval 0.42 to 3.75, P = 0.683).

CONCLUSIONS

In this study of survivorship following routine uncomplicated primary THA with modern cups and liners, screw usage patterns were associated with neither an advantage nor disadvantage - neither screw usage nor avoidance was associated with differences in acetabular loosening revision risk. Screw use was not associated with harm but remains debatable if there is an added benefit.

LEVEL OF EVIDENCE: Level III.