Primarily Constraining Custom Triflange Patients: Weighing the Risks of Instability Versus Fixation?

BACKGROUND

Custom triflange acetabular components (CTACs) can be used to manage patients with severe acetabular bone loss. However, instability remains one of the primary reasons for reoperation and revision for these patients. Primarily constraining these patients is an attractive option to minimize the risk of instability, but theoretically puts more stress on the implant fixation and leads to subsequent failure. Therefore, this study aimed to compare outcomes between patients managed with CTACs with standard liners (SLs) versus those with constrained liners (CLs) at the index procedure.

METHODS

We identified patients treated with a CTAC for severe acetabular bone loss with a minimum two-year follow-up. Patients received either a CL or SL. Patient demographics and intraoperative details were described, and comparative survival analyses were conducted on all time-to-complication outcomes: years to triflange component failure (aseptic revision and all indications), other revisions of the component exclusive of CTAC, reoperation where no components were exchanged, and dislocation.

RESULTS

There were 37 patients treated with CTAC who received SLs and 44 who received CLs, for a total cohort of 81. The median follow-up time was 4.2 years (interquartile range, 2.6 to 6.7; min/max range, two to 15). Analysis showed no significant survival estimate differences in years to triflange component failure (aseptic revision, P = 0.800, and all indications, P = 0.800), other revisions of the construct exclusive of CTAC (P = 0.500), reoperation where no components were exchanged (P = 0.400), and dislocation (P = 0.500).

DISCUSSION AND CONCLUSION

Our findings suggest the use of acute CL appears to represent a safe and appropriate option in patients with substantial instability risks without increased risk of component failure compared to SLs over time. Therefore, we recommend consideration of CL in high-risk instability patients requiring CTAC.