Abstract
Introduction
Patients undergoing primary total hip arthroplasty (THA) with prior lumbar spine fusion (LSF) are at high risk for instability with reported incidence of dislocation as high as 8.3%. The use of dual mobility cups in patients undergoing revision THA, another high risk group, has demonstrated decreased incidence of instability. Purpose of this study was to evaluate the risk of instability in patients undergoing primary THA with a history of prior LSF using dual mobility cups.
Methods
This was a multi-center retrospective study with 93 patients undergoing primary THA using a dual mobility cup with prior history of instrumented LSF. The primary outcome investigated was instability. Secondary variables investigated included number of levels fused, approach, length of stay, and other complications. The minimum follow-up time was 1 year since the majority of dislocations occur during first year following the primary THA.
Results
There were 56 females and 47 males with average age of 66 years (46–87) and average BMI of 30. Mean follow up was 31 months (range 12 – 124.2). Surgical approach included: posterior (63), direct lateral (15), anterior (11), direct superior (4). 44% had one level fusion, 29% with 2 levels, and 15% with 3 or more levels fused. There were no dislocations or infections in this study group. There was one intraoperative fracture and one DVT.
Conclusions
Patients undergoing primary THA with prior LSF are a high risk group with an increased risk for instability due to the loss of normal spino-pelvic relationship. The use of dual mobility cups in a high risk group of patients in this study demonstrated excellent results with no incidence of dislocation. Despite the limitations in this study with varying approaches and multiple sites, the use of dual mobility cups to decrease the incidence of instability in patients with prior LSF appears promising.
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