Purpose of Review 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. Recent Findings 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. Summary 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.

Subacute, nontraumatic hip pain is often a diagnostic challenge. Femoroacetabular impingement (FAI) is a common cause of atraumatic hip pain that is poorly understood. FAI is a result of abnormal morphologic changes in either the femoral head or the acetabulum. FAI is more prevalent in people who perform activities requiring repetitive hip flexion, but it remains common in the general population. Evaluation begins with physical examination maneuvers to rule out additional hip pathology and provocation tests to reproduce hip pain. Diagnosis is often made by radiography or magnetic resonance imaging. Initial treatment is generally more conservative, featuring activity modification and physical therapy, whereas more aggressive treatment requires operative management.

Objectives: The primary objective of this study was to analyze the relationship of percentage of surgical overlap with patient outcomes to determine if a detrimental level of overlap exists. Background: Overlapping surgery is defined as 1 attending physician supervising 2 or more operative cases simultaneously, without the critical portions of the cases occurring concurrently. To date, no study has examined the relationship of percent overlap, or the percentage of 1 case that is spent overlapping with another, to outcomes, efficiency, safety, and complications. Methods: This study is a retrospective cohort study conducted at a large tertiary referral center. The primary outcomes of interest included operative duration, in-hospital mortality, 30-day readmission, and patient safety indicators (PSIs). The Cochran-Armitage test for trend was used to evaluate the outcomes of interest. P values of ≤0.05 were considered statistically significant. Results: A total of 87,426 cases were included in this study. There were 62,332 cases without overlap (Group 0), 10,514 cases with 1% to 25% overlap (Group 1), 5303 cases with 26% to 50% overlap (Group 2), 4296 cases with 51% to 75% overlap (Group 3), and 4981 cases with >75% overlap (Group 4). In-hospital mortality decreased as overlap increased (P trend<0.0001). Operative time increased with increasing overlap (P trend<0.0001) while readmission rates showed no statistical significance between groups (P trend=0.5078). Rates of PSIs were lower for Groups 1, 2, and 3 (1.69%, 2.01%, and 2.08%) when compared to Group 0 (2.24%). Group 4 had the highest rate of PSIs at 2.35% (P=0.0086). Conclusion: Overlapping surgery was shown to have reduced in-hospital mortality and similar PSI and readmission rates when compared to nonoverlapping cases. Operative time was shown to increase in overlapping surgeries when compared to nonoverlapping surgeries. The results from this study indicate that the percentage of surgical overlap does not detrimentally affect most patient outcomes, especially with overlap of <75%.