Up to 10-Year Follow-Up of Thin Polyethylene Liners in Total Hip Arthroplasty.

BACKGROUND

Using thin polyethylene liners with large-diameter femoral heads in total hip arthroplasty (THA) may decrease the risk of instability. This study investigated the 1-to-10-year survivorship of thin highly cross-linked polyethylene (HXLPE) liners.

METHODS

This was a retrospective cohort study of patients who underwent primary THA for osteoarthritis at a single institution. Patients who received an HXLPE liner with a thickness of 3.9, 5.9, or 7.9 mm and a variety of femoral head and cup sizes were included. Surgical information, patient-reported outcome measures, and 1- to 10-year outcomes were collected. Of the 4,951 cases included, 92 utilized a 3.9-mm liner, 2,690 utilized a 5.9-mm liner, and 2,169 utilized a 7.9-mm liner, with respective mean lengths of follow-up of 4.5 years (range, 1.2 to 12.2), 6.1 years (range, 1.0 to 12.1), and 6.1 years (range, 1.0 to 12.4).

RESULTS

There was no significant difference in revisions or reoperations among the cohorts. Among those revised, 7.9 mm liners were more likely to have instability as the revision indication when compared to 5.9 mm liners (0.1 versus 0.04%). The 3.9 mm group had no revisions for instability or polyethylene wear. At six months postoperatively, the Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS-JR) was significantly greater in patients who had a 3.9 mm liner (P = 0.004). At two, five, and 10 years postoperatively, HOOS-JR was equivalent across groups (P = 0.760, P = 0.098, P = 0.685, respectively). At five years, the 3.9 mm group had a significantly lower improvement in HOOS-JR (P = 0.036), but this difference equalized between groups at 10 years

CONCLUSIONS

Thin and standard-size HXLPE liners in THA have similar functional and clinical outcomes up to ten years postoperatively. Liners of 3.9 mm may safely be used while providing the benefit of reduced revision for instability.