Sagittal Pelvic Kinematics in Hip Arthroplasty

The orientation of the spine relative to the pelvis-particularly that in the sagittal plane-has been shown in both kinematic and radiographic studies to be paramount in governance of acetabular alignment during normal bodily motion. The purpose of this review is to better understand the challenges faced by arthroplasty surgeons in treating patients that have concurrent lumbar disease and are therefore more likely to have poorer clinical outcomes after THA than in patients without disease.

The concept of an "acetabular safe zone" has been well described in the past regarding the appropriate orientation of acetabular component in THA. However, this concept is now under scrutiny, and rising forth is a concept of functional acetabular orientation that is based on clinically evaluable factors that are patient and motion specific. The interplay between the functional position of the acetabulum and the lumbar spine is complex. The challenges that are thereby faced by arthroplasty surgeons in terms of proper acetabular cup positioning when treating patients with concomitant lumbar disease need to be better understood and studied, so as to prevent catastrophic and costly complications such as periprosthetic joint dislocations and revision surgeries.