Acetabular component positioning is commonly referenced with the pelvis in the supine position in direct anterior approach THA. Changes in pelvic tilt (PT) from the pre-operative supine to the post-operative standing positions have not been well investigated and may have relevance to optimal acetabular component targeting for reduced risk of impingement and instability. The aims of this study were therefore to determine the change in PT that occurs from pre-operative supine to post-operative standing, and whether any factors are associated with significant changes in tilt ≥13° in posterior direction. 13° in a posterior direction was chosen as that amount of posterior rotation creates an increase in functional anteversion of the acetabular component of 10°. 1097 THA patients with pre-operative supine CT and standing lateral radiographic imaging and 1 year post-operative standing lateral radiographs (interquartile range 12–13 months) were reviewed. Pre-operative supine PT was measured from CT as the angle between the anterior pelvic plane (APP) and the horizontal plane of the CT device. Standing PT was measured on standing lateral x-rays as the angle between the APP and the vertical line. Patients with ≥13° change from supine pre-op to standing post-op (corresponding to a 10° change in cup anteversion) were grouped and compared to those with a <13° change using unpaired student's t-tests. Mean pre-operative supine PT (3.8±6.0°) was significantly different from mean post-operative standing PT (−3.5±7.1°, p<0.001), ie mean change of −7.3±4.6°. 10.4% (114/1097) of patients had posterior PT changes ≥13° supine pre-op to standing post-op. A significant number of patients, ie 1 in 10, undergo a clinically significant change in PT and functional anteversion from supine pre-op to standing post-op. Surgeons should be aware of these changes when planning component placement in THA.
Dual mobility bearings are an attractive treatment option to obtain hip stability during challenging primary and revision total hip arthroplasty (THA) cases. Despite growing enthusiasm in the United States, long-term results of modern dual mobility implants are lacking. The purpose of this study is to analyze data submitted to the American Joint Replacement Registry (AJRR) to characterize utilization trends of dual mobility bearings in the United States. All primary and revision THA procedures reported to AJRR from 2012–2018 were analyzed. Patients of all ages were included and subdivided into dual mobility and traditional bearing surface cohorts. Independent variables included patient demographics, geographic region, hospital size, and teaching affiliation. Associations were determined by chi-square analysis and a logistic regression was performed to assess the association between dual mobility and independent variables.Background
Methods
The American Joint Replacement Registry (AJRR) was created to capture total hip (THA) and total knee arthroplasty (TKA) procedural data in order to conduct implant-specific survivorship analyses, produce risk-adjusted patient outcome data, and provide hospitals and surgeons with quality benchmarks. The purpose of this study is to compare early reports from the AJRR to other national registries to identify similarities and differences in surgeon practice and potential topics for future analysis. Hip arthroplasty data were extracted from the annual reports from the AJRR and other national registries including: the Australian registry; the New Zealand registry; the United Kingdom, Wales, and Isle of Man registry; the Norwegian registry; and the Swedish registry from 2014 to 2016. Data regarding femoral and acetabular fixation, bearing surface type, femoral head size, the use of dual mobility articulation bearings, hip resurfacing utilization, and THA revision burden were evaluated. Revision burden is defined as the ratio of implant revisions to the total number of arthroplasties performed in a given time period. Registry characteristics and patient demographic data were recorded across all registries. The results were compared between the various registries and reported using descriptive statistics.Introduction
Methods
The bearing surface is the critical element in determining the longevity of a total hip arthroplasty. Over the past decade problems associated with bearing surfaces and modular femoral tapers have had an impact on surgeon selection of both acetabular liners and modular femoral heads. The purpose of this study was to analyse THA bearing surface trends from 2007 through 2014 using a large national database. A retrospective review of the Nationwide Inpatient Sample (NIS) database was conducted from 2007 to 2014. All patients who underwent a primary THA were identified using International Classification of Diseases, 9th edition (ICD-9) procedure codes. Bearing surface data was extracted by identifying patients with ICD-9 procedure modifier codes. Patient and hospital characteristics were recorded for each patient. Descriptive statistics were employed to characterise bearing surface trends for the following bearing surfaces: metal on polyethylene (MoP); ceramic on polyethylene (CoP); ceramic on ceramic (CoC) and metal on metal (MoM). Univariate analysis was performed to identify differences between the bearing surface groups. During the study period, 2,460,640 primary THA discharges were identified, of which 1,059,825 (43.1%) had bearing surface data available for further analysis. The breakdown of the bearing surfaces used for these THAs were as follows: MoP − 49.1% (496,713); CoP − 29.1% (307,907); CoC − 4.2% (44,823); and MoM − 19.9% (210,381). MoM utilization peaked in 2008 with 51,033 cases representing 40.1% of THAs implanted that year. The usage steadily declined and by 2014 there were only 6,600 MoM cases representing only 4.0% of the THAs. From 2007 to 2014, the use of CoP bearing surfaces increased from 11,482 discharges (11.1% of cases) in 2007, to 83,300 discharges (50.8% of cases) in 2014. CoP utilization surpassed MoP in 2014. MoP accounted for 54.7% of discharges in 2011 and just 42.1% in 2014. During the study period, MoM bearing surface usage declined precipitously, while CoP surpassed MoP as the most prevalent bearing surface used in total hip arthroplasty patients. These changes in bearing surface usage over time were clearly influenced by concerns regarding high failure rates associated with MoM articulations and reports of taper corrosion associated with modular metal femoral heads.
The purpose of this study was to compare the biomechanical effects of the trapezius transfer and the latissimus dorsi transfer in a cadaveric model of a massive posterosuperior rotator cuff tear. Eight cadaveric shoulders were tested at 0°, 30°, and 60° of abduction in the scapular plane with anatomically based muscle loading. Humeral rotational range of motion and the amount of humeral rotation due to muscle loading were measured. Glenohumeral kinematics and joint reaction forces were measured throughout the range of motion. After testing in the intact condition, the supraspinatus and infraspinatus were resected, simulating a massive rotator cuff tear. The lower trapezius transfer was then performed. Three muscle loading conditions for the trapezius (12N, 24N, 36N) were applied to simulate a lengthened graph as a result of excessive creep, a properly tensioned graph exerting a force proportional to the cross-sectional area of the inferior trapezius, and an over-constrained graph respectively. Next the latissimus dorsi transfer was performed and tested with one muscle loading condition 24N. A repeated-measures analysis of variance was used for statistical analysis.Background:
Methods:
Individuals with large Hill-Sachs lesions may be prone to failure and reoccurrence following standard arthroscopic Bankart repair. Here, the Remplissage procedure may promote shoulder stability through infraspinatus capsulo-tenodesis directly into the lesion. Little biomechanicaldata about the Remplissage procedure on glenohumeral kinematics, stability, and range of motion (ROM) currently exists. What are the biomechanical effects of Bankart and Remplissage repair for large Hill-Sachs lesions?Background:
Questions/purposes:
