The aim of this study is to compare clinical outcomes of patients considered to be high risk for prosthetic dislocation undergoing primary total hip arthroplasty (THA) with the use of a dual mobility bearing versus a conventional, single bearing design.

This study aims to compare the clinical outcomes of patients considered to be at high risk for prosthetic dislocation undergoing primary total hip arthroplasty (THA) with the use of a dual mobility bearing versus a conventional, single-bearing design.

We hypothesize that in primary THA patients considered to be at high risk for prosthetic dislocation, the use of dual-mobility components will be associated with a lower dislocation rate in the first year following the index procedure. We do not anticipate a difference. In other clinical outcome measures or functional outcome scores between the two cohorts.

Study Design: Randomized controlled trial with two groups: THA with dual mobility.

44 components vs THA with single-bearing designs

Inclusion Criteria:

• Primary THA for a diagnosis of osteoarthritis or inflammatory arthritis in the setting of a history of prior lumbar or lumbosacral fusion performed at least 6 months prior to their THA. In addition, patients considered high-risk for potential prosthetic dislocation will be included based on the presence of one or more of the following: neuromuscular disorder (e.g. cerebral palsy, Parkinson's disease, history of a stroke), dementia or cognitive impairment, substance or alcohol abuse (>10 drinks per week), acute displaced femoral neck fracture, age > 75 years, inflammatory arthritis, and increased preoperative range of motion (calculated as described by Krenzel et al.: combined flexion, adduction, internal rotation > 115 degrees).

Exclusion Criteria:

• Less than 18 years of age
• Revision THA
• spinopelvic fusion that is more recent than 6 months prior to THA
• isolated cervical or thoracic fusion
• intent to undergo a revision spinopelvic fusion within one year of their index THA
• a history of prior infection in the affected hip
• a history of prior open surgery on the affected hip (i.e. prior proximal femur fracture or osteotomy)
• or a preoperative diagnosis of post-traumatic arthritis, avascular necrosis, or fracture