The Lawrence D. Dorr Surgical Techniques & Technologies Award: Using Big Heads and Small Acetabular Components With...

Contemporary total hip arthroplasty (THA) employs larger femoral heads to optimize hip stability. However, the combination of large femoral heads and comparatively small acetabular components poses a potential risk for implant failure secondary to polyethylene (PE) liner fracture or dissociation. The purpose of this study was to evaluate the incidence of liner fracture or dissociation, implant survivorship, and PE wear rates in primary THAs using large femoral heads and small acetabular components.

Between 2000 and 2017, we retrospectively identified 882 primary THAs with 36 mm femoral heads and acetabular components ≤52 mm with highly cross-linked polyethylene liners. Mean age was 66 years, 88% were females, and mean body mass index was 30 kg/m². We evaluated the cumulative incidences of dislocation, any revision, and any reoperation utilizing a competing risk model. Osteolysis and femoral head penetration were assessed with a validated radiographic technique at minimum 10-year follow-up (n = 18). Mean follow-up was 4 years.

There were no liner fractures or dissociations in the entire cohort. The 10-year cumulative incidences of dislocation, any revision, and any reoperation were 3.2%, 5.6%, and 9.3%, respectively. Mean linear femoral head penetration was 0.042 mm/y and mean volumetric wear rate was 44 mm³/y. No THAs demonstrated evidence of osteolysis or component loosening at long-term follow-up.

In a large cohort of primary THAs pairing large femoral heads with small acetabular components, there was no evidence of liner fracture or dissociation. Cumulative incidences of dislocation, any revision, and any reoperation were low at mid-term.

IV.