Total hip arthroplasty with monobloc press-fit acetabular components and large-diameter bearings for atypical acetabula is safe: a consecutive case series of 125 hips with mean follow-up of 9 years.

BACKGROUND: Large-diameter head (LDH) total hip arthroplasty (THA) with a monobloc acetabular component improves hip stability. However, obtaining initial press-fit stability is quite challenging in atypical acetabula. The purpose of this study was to assess primary and secondary fixation of monobloc cups in atypical acetabula. METHODS: In this consecutive case series, the local arthroplasty database was used to retrospectively identify patients with secondary osteoarthritis who underwent primary hip replacement with press-fit only LDH monobloc acetabular components between 2005 and 2018 and who had a minimum of 2 years of follow-up. Radiographic evaluation was performed at last follow-up, and patient-reported outcome measures (PROMs) were assessed with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Forgotten Joint Score (FJS), and the Patient's Joint Perception (PJP) question. RESULTS: One hundred and six LDH THAs and 19 hip resurfacings were included in the study. Preoperative diagnoses included hip dysplasia (36.8%), Legg-Calve-Perthes disease (32.0%), osteoarthritis with acetabular deficiency (17.6%), periacetabular osteotomy (8.0%), arthrodesis (4.0%), and osteopetrosis (1.6%). After a mean follow-up of 9.2 years, no aseptic loosening of the acetabular component was recorded nor observed on radiologic review. There were 13 (10.4%) revisions unrelated to the acetabular component fixation. The mean WOMAC and FJS scores were 9.2 and 80.9, respectively. In response to the PJP question, 49.4% of the patients perceived their hip as natural, 19.1% as an artificial joint with no restriction, 31.5% as an artificial joint with restriction, and none as a non-functional joint. CONCLUSION: Primary press-fit fixation of monobloc acetabular components with LDH implanted in atypical acetabula led to secondary fixation in all cases with low revision and complication rates and great functional outcomes. With careful surgical technique and experience, systematic use of supplemental screw fixation is not essential in THA with atypical acetabula.

Monobloc press-fit cups with large-diameter bearings are safe in revision total hip arthroplasty.

BACKGROUND: Instability is a major cause of failure of revision total hip arthroplasty (THA) which can be avoided with the use of monobloc press-fit cups with large diameter heads (LDH). OBJECTIVE: This consecutive case series analyses whether LDH monobloc components are a safe and clinically beneficial option for revision THA. METHODS: This consecutive case series includes 47 revision THA with LDH monobloc acetabular cup. Acetabular bone defects were Paprosky type I (42), type IIA (2) and type IIC (3). The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Forgotten Joint Score (FJS) and the Patient's Joint Perception (PJP) scores were analysed and a radiographic evaluation for signs of implant dysfunction was performed. RESULTS: After a mean follow-up of 4.5 years, there were 5 (10.6%) acetabular cup re-revisions: 2 loss of primary fixation and 3 instabilities. Implant survivorship at 4-years was 89.4% (95% CI: 89.3 to 89.5). Recurrent hip dislocation was reported in 1 patient (2.1%) and remains under conservative treatment. The mean WOMAC and FJS were 19.5 (16.8; 0.0 to 58.3) and 57.3 (28.9; 6.3 to 100.0), respectively. Regarding the PJP, 3 (8.8%) patients perceived their hip as natural, 8 (23.5%) as an artificial joint with no restriction, 14 (41.2%) with minor restriction and 9 (26.5%) with major restriction. CONCLUSION: In cases of revision THA with limited bone loss, press-fit primary fixation with LDH monobloc acetabular components are valuable options that offer excellent mid-term out-comes with low re-revision and joint instability rates.