Preoperative radiographic findings associated with postoperative spinopelvic risk factors for instability following total hip arthroplasty.

Postoperative spinopelvic changes are associated with increased dislocation risk following total hip arthroplasty (THA). The aim of this study was to identify preoperative patient and radiographic factors associated with high-risk postoperative spinopelvic parameters. A retrospective review of consecutive THA patients who received preoperative and postoperative sitting and standing lateral lumbar spine-hip radiographs with minimum radiographic and clinical follow-up of 10 months was performed.

Increased dislocation rates following total hip arthroplasty in patients with ankylosing spondylitis.

Background: Patients with ankylosing spondylitis (AS) experience abnormal spinopelvic motion due to chronic inflammation of the axial skeleton, predisposing them to impingement and dislocation. The purpose of this study was to evaluate total hip arthroplasty (THA) dislocation rates in AS patients and evaluate the effects of age and gender on dislocation risk.

Methods: Patients who underwent primary THA from 2005 to 2014 were identified using the PearlDiver database.

How much change in pelvic sagittal tilt can result in hip dislocation due to prosthetic impingement? A computer simulation study.

Developing spinal pathologies and spinal fusion after total hip arthroplasty (THA) can result in increased pelvic retroversion (e.g., flat back deformity) or increased anterior pelvic tilt (caused by spinal stenosis, spinal fusion or other pathologies) while bending forward.

Is Combined Anteversion Equally Affected by Acetabular Cup and Femoral Stem Anteversion?

Background: To create a safe zone, an understanding of the combined femoral and acetabular mating during hip motion is required. We investigated the position of the femoral head inside the acetabular liner during simulated hip motion. We hypothesized that cup and stem anteversions do not equally affect hip motion and combined hip anteversion.

The Effect of Functional Pelvic Tilt on the Three-Dimensional Acetabular Cup Orientation in Total Hip Arthroplasty Dislocations.

Background: Anterior and posterior pelvic tilt appears to play a role in total hip arthroplasty (THA) stability. When changing from the standing to the sitting position, the pelvis typically rotates posteriorly while the hips flex and this affects the femoro-acetabular positions. This case-control study compares changes in 3-D acetabular cup orientation during functional pelvic tilt between posterior THA dislocations vs stable THAs.

Functional Anatomy of the Hip Joint.

Background: The functional anatomy of the osteoarthritic hip joint in the sagittal plane has not been defined. The purpose of this study was to define the functional anatomy of the hip using clinical and radiographic analyses.

Methods: 320 hips had preoperative standing and sitting lateral spine-pelvis-hip X-rays.

The Effects of Pelvic Incidence in the Functional Anatomy of the Hip Joint.

Background: The spine-pelvis-hip interaction during postural change should be considered in the functional anatomy of the hip. The component parts of this anatomy and how they influence hip function are important to know. Pelvic incidence (PI) is one of these components.

Spinopelvic Motion and Impingement in Total Hip Arthroplasty.

The stability of a total hip arthroplasty relies on proper positioning of the acetabular cup. Recent research has shown that this cup position is more dynamic than previously thought. The 3-dimensional orientation of the acetabular cup changes when the pelvis tilts anteriorly or posteriorly.

Functional Safe Zone Is Superior to the Lewinnek Safe Zone for Total Hip Arthroplasty: Why the Lewinnek Safe Zone Is Not Always Predictive of Stability.

Background: The Lewinnek "safe zone" is not always predictive of stability after total hip arthroplasty (THA). Recent studies have focused on functional hip motion as observed on lateral spine-pelvis-hip x-rays. The purpose of this study was to assess the correlation between the Lewinnek safe zone and the functional safe zone based on hip and pelvic motion in the sagittal plane.

Late Dislocation Following Total Hip Arthroplasty: Spinopelvic Imbalance as a Causative Factor.

Background: Late dislocations after total hip arthroplasty (THA) are challenging for the hip surgeon because the cause is often not evident and recurrence is common. Recently, decreased spinopelvic motion has been implicated as a cause of dislocation. The purpose of this study was to assess the mechanical causes of late dislocation, including the influence of spinopelvic motion.

Restoration of center of rotation and balance of THR.

Improvements in early hip arthroplasties focused on surgical techniques with subsequent studies emphasizing restoration of the hip center of rotation for longevity of the implant. Current literature suggests femoral stem anteversion of 10-20°, cup anteversion of 20-25° and a combined anteversion of 25-40° in males, 30-45° in females. Inclination goal appears to be 45° precisely to balance between impingement & dislocation versus edge loading & accelerated wear.

The Opioid Crisis and the Orthopedic Surgeon.

Opioid use and abuse has become a national crisis in the United States. Many opioid abusers become addicted through an initial course of legal, physician-prescribed medications. Consequently, there has been increased pressure on medical care providers to be better stewards of these medications.

Why total knees fail-A modern perspective review.

Historically, the most common mechanism of total knee arthroplasty (TKA) failures included aseptic loosening, instability and malalignment. As polyethylene production improved, modes of failure from polyethylene wear and subsequent osteolysis became less prevalent. Newer longitudinal studies report that infection has become the primary acute cause of failure with loosening and instability remaining as the overall greatest reasons for revision.

The Current Knowledge on Spinopelvic Mobility.

Recent studies may suggest that our conventional knowledge of risk factors for dislocation may need rethinking. Previous studies have demonstrated a large majority of total hip arthroplasty instability with acetabular cups implanted in safe zones. Recently discovered spinopelvic motion is a coordinated biomechanical relationship among acetabular anteversion, pelvic tilt, and lumbar lordosis.