Does Functional Cup Orientation Change at Minimum of 10 Years After Primary Total Hip Arthroplasty?

BackgroundCup orientation has been shown to influence the postoperative risk of impingement and dislocation following total hip arthroplasty (THA) and may change over time due to changes in pelvic tilt that occur with aging. The purpose of this study is to determine if there is a significant change in acetabular cup inclination and anteversion over a 10-year period following THA.MethodsA retrospective, multisurgeon, single-center cohort study was conducted of 46 patients that underwent THA between 1995 and 2002. A total of 46 patients were included, with a median age at surgery of 56 years, and a median time between initial postoperative radiograph and the most recent one being 13.5 years (minimum 10 years). Cup orientation was measured from postoperative and follow-up supine anterior-posterior pelvic radiographs. Using a validated software, inclination and anteversion were calculated at each interval and the change in cup anteversion and inclination angle was determined. Furthermore, the difference in the sacro-femoral-pubic angle was measured, reflecting the difference in pelvic tilt between intervals.ResultsNo significant difference was detected between measurements taken from initial postoperative radiograph and measurements a minimum of 10 years later (P > .45), with the median (interquartile range) change in anteversion, inclination, and sacro-femoral-pubic being 0° (−1° to 3°), 1° (−3° to 2°), and 0° (−2° to 3°), respectively.ConclusionOur study found no significant change in functional cup orientation a minimum of 10 years after THA. No shifts in functional cup orientation as a result of altering spinopelvic alignment seemed to be present over a 10-year period.     

Corrosion Concerns? Trends in Metal-on-Polyethylene Total Hip Arthroplasty Revision Rates and Comparisons Against Ceramic-on-Polyethylene up to 10 Years of Follow-Up

BackgroundWe compared the revision risk between metal-on-polyethylene (MOP) and ceramic-on-polyethylene (COP) total hip arthroplasty patients and evaluated temporal changes in short-term revision risks for MOP patients.MethodsPrimary MOP (n = 9480) and COP (n = 3620) total hip arthroplasties were evaluated from the Medicare data set (October 2005 to December 2015) for revision risk, with up to 10 years of follow-up using multivariate analysis. Temporal change in the short-term revision risk for MOP was evaluated (log-rank and Wilcoxon tests).ResultsRevision incidence was 3.8% for COP and 4.3% for MOP. MOP short-term revision risk did not change over time (P ≥ .844 at 1 year and .627 at 2 years). Dislocation was the most common reason for revision (MOP: 23.5%; COP: 24.8%). Overall adjusted revision risks were not different between MOP and COP up to 10 years of follow-up (P ≥ .181).ConclusionsConcerns with corrosion for metal heads do not appear to result in significantly elevated revision risk for MOP at up to 10 years. Corrosion does not appear as a primary reason for revision compared to other mechanisms.     

Does Hepatitis C Affect the Clinical and Patient-Reported Outcomes of Primary Total Hip Arthroplasty at Midterm Follow-Up?

Background

It is estimated that 3%-6% of orthopedic patients, many of whom may undergo lower extremity total joint arthroplasty, are infected with hepatitis C. The purpose of this study was to assess the outcomes of patients with hepatitis C who undergo total hip arthroplasty (THA) in comparison with a matched control cohort in terms of (1) patient-reported outcomes, (2) implant survivorship, and (3) complications.

Does Multiple Sclerosis Affect the Inpatient Perioperative Outcomes After Total Hip Arthroplasty?

Background

There is a paucity of studies evaluating the short-term perioperative outcomes of total hip arthroplasty (THA) in multiple sclerosis (MS) patients. Therefore, this study evaluated (1) patient factors; and (2) patient outcomes in MS THA patients compared to non-MS THA patients.

Does Standing Affect Acetabular Component Inclination and Version After THA?

Background  

Avoiding complications after hip arthroplasty with hard-on-hard bearings, especially metal-on-metal, correlates with the position of the acetabular component. Supine imaging with conventional radiography has traditionally been utilized to assess component inclination (abduction), as well as anteversion, after THA and surface replacement arthroplasty (SRA). However, most adverse events with hard bearings (excessive wear and squeaking) have occurred with loading. Standing imaging, therefore, should provide more appropriate measurements.     

Outcomes of Total Hip Arthroplasty After Acetabular Open Reduction and Internal Fixation in the Elderly—Acute vs Delayed Total Hip Arthroplasty

BackgroundOptimum management for the elderly acetabular fracture remains undefined. Open reduction and internal fixation (ORIF) in this population does not allow early weight-bearing and has an increased risk of failure. This study aimed to define outcomes of total hip arthroplasty (THA) in the setting of an acetabular fracture and compared delayed THA after acetabular ORIF (ORIF delayed THA) and acute fixation and THA (ORIF acute THA).MethodsAll acetabular fractures in patients older than 60 years who underwent ORIF between 2007 and 2018 were reviewed (n = 85). Of those, 14 underwent ORIF only initially and required subsequent THA (ORIF delayed THA). Twelve underwent an acute THA at the time of the ORIF (ORIF acute THA). The ORIF acute THA group was older (81 ± 7 vs 76 ± 8; P < .01) but had no other demographic- or injury-related differences compared with the ORIF delayed THA group. Outcome measures included operative time, length of stay, complications, radiographic assessments (component orientation, leg-length discrepancy, heterotopic ossification), and functional outcomes using the Oxford Hip Score (OHS).ResultsOperative time (P = .1) and length of stay (P = .5) for the initial surgical procedure (ORIF only or ORIF THA) were not different between groups. Four patients had a complication and required further surgeries; no difference was seen between groups. Radiographic assessments were similar between groups. The ORIF acute THA group had a significantly better OHS (40.1 ± 3.9) than the ORIF delayed THA group (33.6 ± 8.5) (P = .03).ConclusionIn elderly acetabulum fractures, ORIF acute THA compared favorably (a better OHS, single operation/hospital visit, equivalent complications) with ORIF delayed THA. We would thus recommend that in patients with risk factors for failure requiring delayed THA (eg, dome or roof impaction) that ORIF acute THA be strongly considered.     

Does Vitamin D Status Affect the Attainment of In-Hospital Functional Milestones After Total Hip Arthroplasty?

Our study aims to identify the prevalence of low vitamin D status in patients undergoing total hip arthroplasty (THA) and to evaluate the association between serum vitamin D level and the attainment of in-hospital functional milestones. We collected data from patients who underwent THA and had preoperative serum vitamin D (serum 25-hydroxy vitamin D) levels measured. From 200 patients, 79 (39.5%) had low serum vitamin D (serum 25-hydroxy vitamin D <32 ng/mL). There were no associations between serum vitamin D level and the attainment of in-hospital functional milestones as well as length of hospital stay or perioperative complications after THA. Because low vitamin D status did not compromise the short-term functional outcomes after THA, surgery need not be delayed, but low vitamin D levels should be corrected once identified.     

Periprosthetic Femur Fractures After Total Hip Arthroplasty: Does the Mode of Failure Correlate With Classification?

BackgroundPeriprosthetic femur fracture is one of the most common indications for reoperation after total hip arthroplasty. Our objectives were to evaluate the incidence of reoperation after the surgical treatment of periprosthetic femur fractures and to compare the mechanisms of failure between fractures around a stable femoral component and those with an unstable femoral component.MethodsWe identified a consecutive series of 196 surgically treated periprosthetic fractures after total hip arthroplasty between 2008 and 2017. Mean age was 72 years (range, 29-96 years), and 108 (55%) were women. The femoral component was unstable in 127 cases (65%) and stable in the remaining 69 cases (35%). Mean follow-up was 2 years.ResultsThe 2-year cumulative probability of any reoperation was 19%. The most common indication for reoperation among the cases with a stable femoral component was nonunion, and the most common indication for reoperation among the cases with an unstable femoral component was infection. Fractures that originated at the distal aspect of the femoral component were associated with a high risk of nonunion (6 of 28 cases, P < .01) and reoperation (9 of 28 cases, P = .03).ConclusionSurgeons should take measures to mitigate the failure modes that are distinct based on fracture type. The high infection rate after surgical management of B₂ fracture suggests that additional antiseptic precautions may be warranted. For B₁ fractures, particularly those originating near the distal aspect of the femoral component, augmenting fixation with orthogonal plating, spanning the entire femur, or revising the stem in cases of poor proximal bone should be considered.     

Revision Surgery for Instability After Total Hip Arthroplasty: Does Timing Matter?

BackgroundInstability is a common reason for revision surgery after total hip arthroplasty (THA). Recent studies suggest that revisions performed in the early postoperative period are associated with higher complication rates. The purpose of this study is to assess the effect of timing of revision for instability on subsequent complication rates.MethodsThe Medicare Part A claims database was queried from 2010 to 2017 to identify revision THAs for instability. Patients were divided based on time between index and revision surgeries: <1, 1-2, 2-3, 3-6, 6-9, 9-12, and >12 months. Complication rates were compared between groups using multivariate analyses to adjust for demographics and comorbidities.ResultsOf 445,499 THAs identified, 9298 (2.1%) underwent revision for instability. Revision THA within 3 months had the highest rate of periprosthetic joint infection (PJI): 14.7% at <1 month, 12.7% at 1-2 months, and 10.6% at 2-3 months vs 6.9% at >12 months (P < .001). Adjusting for confounding factors, PJI risk remained elevated at earlier periods: <1 month (adjusted odds ratio [aOR]: 1.84, 95% confidence interval [CI]: 1.51-2.23, P < .001), 1-2 months (aOR: 1.45, 95% CI: 1.16-1.82, P = .001), 2-3 months (aOR: 1.35, 95% CI: 1.02-1.78, P = .036). However, revisions performed within 9 months of index surgery had lower rates of subsequent instability than revisions performed >12 months (aOR: 0.67-0.85, P < .050), which may be due to lower rates of acetabular revision and higher rates of head-liner exchange in this later group.ConclusionWhen dislocation occurs in the early postoperative period, delaying revision surgery beyond 3 months from the index procedure may be warranted to reduce risk of PJI.     

Does Surgical Approach Influence the Natural History of the Unstable Total Hip Arthroplasty?

BackgroundDislocation following total hip arthroplasty (THA) is a significant complication that occurs in 0.3%-10% of cases with 13%-42% of patients requiring revision surgery. The literature has primarily focused on the dislocation risk associated with different surgical approaches. However, little is known about the natural history of the dislocated hip and whether surgical approach of the index THA is associated with further instability and revision surgery.MethodsThis is a retrospective, single-center, multi-surgeon consecutive case series of all patients who experienced THA dislocation from 2002 to 2020. Patients were excluded if the initial dislocation was secondary to infection or fracture. The natural history of the cohort as per approach was determined. Outcome measurements of interest were the number of dislocations; the treatment surrounding each dislocation; the necessity and type of revision; and the complications encountered.ResultsOf the 75 patients, 58 (77%) dislocated within 6 months following primary THA. The anterior group had greater odds of dislocation within 2 weeks post-THA compared to the lateral and posterior groups (P = .04). The mean number of dislocations per patient was significantly lower in the anterior (1.5 ± 0.7) compared to the lateral (2.4 ± 1.2) and posterior (2.1 ± 1.0) groups (P = .02). Revision surgery was needed in 30% (6/20) of patients in the anterior, 69% (25/36) of the posterior, and 68% (13/19) of the lateral groups (P = .01).ConclusionThis study illustrates that while primary THA dislocations happen earlier with the anterior approach, they are typically less complicated and have a lower risk of recurrent instability and revision surgery.     

Can Flexed-Seated and Single-Leg Standing Radiographs Be Useful in Preoperative Evaluation of Lumbar Mobility in Total Hip Arthroplasty?

BackgroundThe purpose of this study is to determine whether simulated radiographs in the “flexed-seated” or “step-up” positions better demonstrate a patient’s range of spinopelvic motion between standing and sitting positions than relaxed sitting and standing radiographs.MethodsAn institutional review board approved cohort of 43 patients with hip osteoarthritis whom underwent full body sitting-standing radiographs from August 2016 to December 2017 at a single institution was reviewed. Subjects underwent single-leg step-up standing and flexed-seated radiographs, and relaxed standing and sitting radiographs. Sacral slope, spinopelvic tilt (SPT), and lumbar lordosis were measured in all radiographs. Alignment parameters were compared between both sets of imaging, and the change in SPT between the imaging modalities was plotted and stratified by pre-existing lumbar pathology.ResultsThere were significant differences between the relaxed standing and step-up radiographs and the relaxed and flexed-seated radiographs for sacral slope, SPT, and lumbar lordosis (P < .002 for all), with the exception of SPT in the relaxed and step-up standing postures (P = .110). When transitioning from the standing to sitting position, the mean changes in SPT differed significantly between both sets of radiographs. Most importantly, when plotting changes in SPT between flexed and relaxed sitting postures, patients with fusions and flatback deformity trended toward greater anterior pelvic tilting, a position of greater risk of posterior dislocation.ConclusionFlexed sitting and single-leg standing imaging may emphasize the compensatory mechanisms of patients with concomitant hip and spine pathology more than relaxed imaging using our measurements. Our method may provide insight into high dislocation risk patients compared to the previously published hip measurement method.Level of EvidenceIII.     

Does Balancing a Total Hip Arthroplasty Require a New Paradigm? Functional 3-Dimensional Balancing in Total Hip Arthroplasty

BackgroundTraditional principles for successful outcomes in Total Hip Arthroplasty (THA) have relied largely on placing the socket in the native position and trying to restore static anatomical femoral parameters gauged on X-rays or intra-operative measurement. Stability is conventionally achieved by making appropriate changes during the time of trial reduction. Post-operative complications of dislocation and significant Limb Length Discrepancy (LLD) requiring foot wear modification represents opposite ends of the spectrum from a biomechanical perspective and these continue to be relatively high. A move towards giving more importance to functional dynamic parameters rather than static anatomical parameters and less reliance on stability testing at trial reduction is warranted.MethodsIntraoperative 3D functional balancing of THA without stability testing at trial reduction was practiced in all subjects undergoing THA in our unit from April 2014. To date 1019 patients have had their hips replaced with the same technique. They were followed up till April 2020 for post-operative complications of dislocation and significant LLD needing footwear modification. A secondary cohort of 114 patients from 1st January to December 31st 2017 within this primary group were analyzed clinically and radiologically to ascertain the implications of functional 3D balancing on X-ray parameters, clinical outcome scores (Harris Hip Score and Oxford Hip Score), ability to squat, and subtle subjective post-operative perception of limb lengthening (POPLL).ResultsIn the primary group of 1019 patients, there were only two dislocations and no patient needed footwear modification for LLD. In the detailed analysis of the secondary cohort of 114 patients, the correlation with restoration of static radiological parameters was inconsistent. 40 patients could not squat and 4 patients had subtle subjective post-operative perceived limb lengthening (POPLL). Measured outcomes such as HHS and OHS were improved in all patients with significant statistical significance (P < 0.001).ConclusionThis study underlines the fact that more importance must be given to functional dynamic parameters by 3D balancing of the THA and not on static anatomical X-rays parameters and stability testing during trial reduction. This represents a paradigm shift in the evolution of total hip arthroplasty.Level of EvidenceA Level II study. (Data collected from the ongoing prospective study) (http://www.spine.org/Documents/LevelsofEvidenceFinal.pdf).Supplementary InformationThe online version contains supplementary material available at 10.1007/s43465-021-00505-3.     

Predictors and Functional Implications of Change in Leg Length After Total Knee Arthroplasty

Background

Leg lengthening occurs in 83% of primary total knee arthroplasty (TKA). The effects of leg length discrepancy (LLD) on THA patients are well established. However, patient function and satisfaction associated with LLD after primary TKA has not been analyzed. This study aimed to quantify the magnitude of limb lengthening, identify radiographic and perceived LLD, and correlate these with predictive factors and functional outcomes in a series of TKA patients.