10-Year Follow-Up Outcomes of a Modular Dual-Mobility in Primary Total Hip Arthroplasty.

BACKGROUND: Our purpose was to evaluate the 10-year clinical outcomes and survivorship of modular dual-mobility (MDM) bearings in primary total hip arthroplasty (THA).

METHODS: We queried our prospective registry database regarding the use of MDM in primary THA. The surgeries were performed by six fellowship-trained surgeons through direct anterior or direct lateral approaches. Most MDM indications were for patients who were used to activities with a high risk of instability or intraoperative findings of subluxation or impingement. A total of 92 MDM bearings were used in 87 patients in the initial 6-month experience. The average age was 62 years (range, 30 to 93), and the average BMI was 29 (range, 17 to 42). There were 87.4 women and 12.6% men. There were seven patients (eight hips) who died prior to the latest follow-up (all with a well-functioning arthroplasty). We obtained a 10-year follow-up in 77 (88.5%) patients comprising 81 (88%) original MDM bearings. Outcomes included hip Disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS JR) and Short-Form/Veterans Rand-12 (SF/VR-2) Physical and Mental Health scores.

RESULTS: The HOOS JR score improved from 24.91 to 78.41 (P < 0.0001), the SF/VR-12 Physical Health score improved from 30.53 to 43.73 (P < 0.0001), and the Mental Health score improved from 35.73 to 54.25 (P < 0.0001). There were four revisions, but none for adverse local tissue reactions or instability. There were no postoperative dislocations in any patient. Radiographs showed no evidence of loosening or osteolysis. Laboratory tests and Magnetic Resonance Imaging (MRI) in asymptomatic patients yielded no positive results.

CONCLUSION: This series of MDM bearings in primary THA shows excellent functional outcomes at 10 years of follow-up with no failures related to the MDM bearing. It is an excellent alternative in primary hip arthroplasty for patients at higher risk of instability.