Should Chronological Age be a Consideration in Patients Undergoing Elective Primary Total Knee Arthroplasty?

INTRODUCTION

The optimal time for total knee arthroplasty (TKA) requires a balance between patient disability and health state in order to minimize complications. While chronological age has not been shown to be predictive of complications in elective surgical patients, there is a point beyond which even optimized elderly patients would be at increased risk for complications. The purpose of this study was to examine the impact of chronological age on complications following primary TKA.

METHODS

Using an administrative database, the records of 2,129,191 patients undergoing elective unilateral TKA between 2006 and 2021 were reviewed. The primary outcomes of interest were cardiac and pulmonary complications, and their relationship to the Charlson-Deyo Comorbidity Index (CDI) and chronological age. Secondary outcomes included risk of renal, neurologic, infection, and intensive care utilization postoperatively. The results were analyzed using a graphical method. The impact of chronological age as a modifier of overall risk for complications was modeled as a continuous variable. An age cutoff threshold of 80 years was also assigned for clinical convenience.

RESULTS

The risk of complications correlated more closely to the Charlson-Deyo index (OR [odds ratio] 1.37 to 2.1) than chronological age (OR 1.0 to 1.1) across the various complications [Table-1. However, beyond age 80 years, the risks of cardiac, pulmonary, renal, and cerebrovascular complications were significantly increased for all CDI categories (OR 1.73 to 3.40) compared to patients below age 80 years [Table-2] [Figures 1A and 1B].

CONCLUSIONS

Chronologic age can impact the risk of complications even in well-optimized elderly patients undergoing primary TKA. As arthroplasty continues to transition to outpatient settings and inpatient denials increase, these results can help patients, physicians, and payors mitigate risk while optimizing the allocation of resources.

Clinical Outcomes of Isolated Polyethylene Exchange Versus Full Component Revision for the Management of Instability Following Total Knee Arthroplasty

BACKGROUND

Instability following total knee arthroplasty (TKA) is a common cause for revision. Isolated polyethylene exchange (IPE) can be performed to increase knee joint stability, but results have been mixed. The purpose of this study was to compare the survivorship and patient-reported outcomes of patients undergoing revision TKA for instability with IPE versus full component revision.

METHODS

We reviewed 280 primary TKAs undergoing revision TKA for instability. There were 181 knees that underwent revision with IPE, compared to 99 knees treated with full component revision. The mean follow-up was 32.8 months (range, 24.8 to 82.5). Patient demographics, radiographic parameters, prosthesis constraints, reoperations for instability, and patient-reported outcomes were compared.

RESULTS

The survivorship for instability was significantly higher at 2 years (99 versus 92%, P = .024) and 5 years (94 versus 84%, P = .024) for patients undergoing full component revision. Although there was no difference in Knee Injury and Osteoarthritis Outcome Score for Joint Replacements and Veterans RAND 12 physical component scores between the 2 groups at 6 weeks, 1 year, and 2 years after surgery, full revision patients reported greater pain relief (P = .006) and greater improvements in Veterans RAND 12 physical component scores (P = .027) at 1 year and Knee Injury and Osteoarthritis Outcome Score for Joint Replacements scores at 2 years (P = .017) compared to IPE patients. Men were associated with an increased risk for recurrent instability following IPE (hazard ratio 3.3, 95% confidence interval: [1.0 to 10.6]).

CONCLUSIONS

Isolated polyethylene exchange was not as reliable or durable compared to full component revision for the management of postoperative instability. These procedures should only be reserved in cases with competent collaterals and when component position, offset, and rotation are optimized.

Body morphometry did not affect the accuracy of a second-generation, miniature imageless navigation system for total hip arthroplasty (THA) using a posterior approach

Introduction

Some modern imageless navigation platforms for total hip arthroplasty (THA) rely on virtual frontal and sagittal planes determined with the patient in the lateral decubitus position. Body morphometry that changes with gender, body mass index, and other demographic factors may affect accuracy in patient positioning and consequently, navigation accuracy. The objective of this study was to analyze the influence of patient factors on the intraoperative accuracy of a second-generation imageless computer-assisted surgery platform.

Methods

325 consecutive patients undergoing posterior approach, navigated THA arthroplasty for primary osteoarthritis by a single surgeon were retrospectively reviewed. An optic-based imageless navigation system referenced off a generic sagittal and coronal plane was used to determine acetabular inclination and anteversion. Acetabular accuracy was determined by assessing differences between intraoperative values and those obtained from measuring standardized 6-week follow-up radiographs. The effect of age, gender, BMI, race, ethnicity, and laterality on acetabular accuracy was assessed via t-tests, Pearson correlation and ANOVA.

Results

Gender had a significant impact on raw inclination accuracy (females and males had an average error of 1.41° and -1.03°, respectively - p < 0.001). There was a weak correlation between acetabular accuracy and patient age and BMI as a continuous variable (both absolute γ < 0.2). No difference was found between acetabular accuracy and BMI groups.

Conclusion

This second-generation imageless computer assisted device provided accurate cup positioning regardless of patient's BMI. Gender was the only factor impacting inclination accuracy.

Contemporary Isolated Bearing Exchange for the Management of Hip Instability Following Primary Total Hip Arthroplasty

BACKGROUND

Isolated ball and liner exchanges (IBLEs) can be performed to increase hip joint stability, but historical results have been mixed due to a lack of head size options or dual mobility articulations. The purpose of this study was to evaluate the contemporary results of IBLEs in patients who have instability following primary total hip arthroplasty (THA).

METHODS

We retrospectively reviewed 65 primary THAs from 2016 to 2020 with hip instability undergoing IBLE or conversion to dual mobility articulation. There were 31 men and 34 women who had an average age of 70 years (range, 26 to 92). The mean time to revision from primary was 40.1 months (range, 1 to 120). In 52 cases, IBLE was performed using conventional bearings, while 13 hips were converted to dual mobility. Radiographic factors, including acetabular component orientation, reproduction of hip joint offset, leg lengths, and outcomes such as recurrent instability requiring subsequent revision and patient-reported outcome measure, were recorded and compared.

RESULTS

There were 12 (18.4%) hips that experienced subsequent instability and required another revision (17.3% ball and liner exchange versus 23.1% dual mobility articulation, P = .615). The mean time to rerevision for instability was 17.1 months. There were no significant differences in either acetabular component anteversion (P = .25) or restoration of hip joint offset (P = .87) in patients who required another revision for instability compared to those who did not, respectively. At 1 year, patients undergoing conventional bearing exchange reported higher Hip Dysfunction Osteoarthritis Outcome Score for Joint Replacements (P = .002) and Veterans Rand physical component (P = .023) scores compared to those who underwent a conversion to dual mobility articulation. Only age > 75 years at the time of surgery was associated with increased risk for dislocation (odds ratio 7.2, confidence interval 1.2 to 43.7, P = .032).

CONCLUSIONS

Isolated bearing exchanges for instability following THA remained at high risk for subsequent instability. Conversion to dual mobility articulations did not reduce the risk of reoperation.

Defining the Learning Period of a Novel Imageless Navigation System for Posterior Approach Total Hip Arthroplasty: Analysis of Surgical Time and Accuracy

Introduction

The use of imageless navigation in total hip arthroplasty (THA) is frequently associated with prolonged surgical times, predominantly during the learning period. The purpose of the present study was to characterize the learning period of a novel imageless navigation system, specifically as it related to surgical time and acetabular navigation accuracy.

Materials and Methods

This was a retrospective observational study of a consecutive group of 158 patients who underwent primary unilateral THA for osteoarthritis by a team headed by a single surgeon. All procedures used an imageless navigation system to measure acetabular cup inclination and anteversion angles, referencing a generic sagittal and frontal plane. Navigation accuracy was determined by assessing differences between intraoperative inclination and anteversion values and those obtained from standardized 6-week follow-up radiographs. Operative time and navigation accuracy were assessed by plotting moving averages of 7 consecutive cases. The learning period was defined using Mann-Kendall trend analyses, student t-tests and nonlinear regression modeling based on surgical time and navigation accuracy. Alpha error was 0.05.

Results

The average surgical time was 67.3 min (SD:9.2) (range 45-95). The average navigation accuracy for inclination was 0.01° (SD:4.2) (range - 10 to 10), and that for anteversion was - 4.9° (SD:3.8) (range - 14 to 5). Average surgical time and navigation accuracy were similar between the first and final cases in the series with no learning period detected.

Conclusions

There was no discernible learning period effect on surgical time or system measurement accuracy during the early phases of adoption for this imageless navigation system.

The John N. Insall Award: Does Melatonin Improve Subjective Sleep Quality After Total Knee Arthroplasty? A Randomized, Placebo-Controlled Trial

BACKGROUND

Sleep disturbance is a common problem following total knee arthroplasty (TKA). The objective of this study was to determine if exogenous melatonin improves sleep quality following primary TKA.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted. A total of 172 patients undergoing unilateral TKA for primary knee osteoarthritis were randomized to receive either 5 mg melatonin (n = 86) or 125 mg vitamin C placebo (n = 86) nightly for 6 weeks. The primary outcome was the Pittsburgh Sleep Quality Index (PSQI) at 6 weeks and 90 days postoperatively. Secondary outcomes included 6-week and 90-day patient-reported outcome measures (PROMs), morphine milligram equivalents prescribed, medication compliance, adverse events, and 90-day readmissions.

RESULTS

Mean PSQI scores worsened at 6 weeks before returning to the preoperative baseline at 90 days in both groups. There were no differences in PSQI scores between melatonin and placebo groups at 6 weeks (10.2 ± 4.2 versus 10.5 ± 4.4, P = .66) or 90 days (8.1 ± 4.1 versus 7.5 ± 4.0, P = .43). Melatonin did not improve the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, Lower Extremity Activity Scale, Visual Analog Scale for pain, or Veterans Rand 12 Physical Component Score or Mental Component Score at 6 weeks or 90 days. Poor sleep quality was associated with worse PROMs at 6 weeks and 90 days on univariate and multivariable analyses, but melatonin did not modify these associations. There were no differences in morphine milligram equivalents prescribed, medication compliances, adverse events, or 90-day readmissions between both groups.

CONCLUSIONS

Exogenous melatonin did not improve subjective sleep quality or PROMs at 6 weeks or 90 days following TKA. Poor sleep quality was associated with worse patient-reported function and pain. Our results do not support the routine use of melatonin after TKA.

Long-Acting Local Anesthetics for Total Knee Arthroplasty: Past, Present, and Future

Pain management remains a challenge in the optimization of outcomes after total knee arthroplasty. Multimodal analgesia is commonplace for modern elective joint replacement, combining various medications and anesthetics along the pain pathway. Local analgesics have the advantage of avoiding systemic effects and offering concentrated local delivery of medications. Long-acting local anesthetics provide the added advantage of providing sustained pain relief when other treatment options may no longer be effective. It is important to provide an update on current local analgesic strategies available with a review of the current literature, outlining the potential benefits and unique considerations of each treatment. Novel medications in development targeting pain management following total knee arthroplasty are possible options in the future.

Preoperative Evaluation, Anesthetic Considerations, and Perioperative Oral and Parenteral Medications in Total Knee Arthroplasty

Effective pain management protocol is critical to early mobilization, early discharge, and increasing patient satisfaction for hip and knee arthroplasty. Surgeons have tried to minimize dependence on opioids and opioid-related adverse events through multimodal protocols that use periarticular injections as well as oral and parenteral medications. The efficacy, cost, and adverse effects of each of these components need to be considered when formulating an evidence-based multimodal pain protocol. Recent advancements have changed understanding of the variability in metabolism of commonly given agents around the time of surgery. It is important to provide a systematic approach to the preoperative evaluation, anesthetic considerations, and the administration of oral and parenteral medications routinely used in total knee arthroplasty.

Why and What Happens to Patients Younger Than 60 Years Who Need Revision Total Knee Arthroplasty?

BACKGROUND

With the increasing number of young patients undergoing primary total knee arthroplasty (TKA), there will be an increase in the number of patients who require revision. While the results of TKA in younger patients are well known, there is little information regarding to the outcomes of revision TKA in this population. The purpose of this study was to evaluate the clinical outcomes in patients <60 years of age undergoing aseptic revision TKA.

METHODS

We retrospectively reviewed 433 patients undergoing aseptic revision TKA between 2008 and 2019. There were 189 patients <60 years compared to a group of 244 patients >60 years undergoing revision TKA for aseptic failures in terms of implant survivorships, complications, and clinical outcomes. Patients were followed for a mean of 48 months (range, 24 to 149).

RESULTS

A total of 28 (14.8%) patients less than 60 years of age required repeat revision compared to 25 (10.2%) 60 years or older (odds ratio (OR) 1.94, 95% confidence interval (CI) 0.73-5.22, P = .187). There were no differences regarding postprocedural Patient-Reported Outcomes Measurement Information System (PROMIS) physical health scores (72.3 ± 13.7 versus 72.0 ± 12.0, P = .66) and PROMIS mental health scores (66.6 ± 17.4 versus 65.8. ± 14.7, P = .72), at an average of 32.9 and 30.7 months, respectively. Postoperative infection occurred in 3 (1.6%) patients <60 years of age, while 12 (4.9%) postoperative infections occurred in patients 60 years or older (OR 0.75, 95% CI 0.06-10.2, P = .83).

CONCLUSION

There were no statistically significant differences in clinical outcomes between patients <60 versus > 60 years of age undergoing aseptic revision TKA.

The Microbiome of Osteoarthritic Hip and Knee Joints: A Prospective Multicenter Investigation

BACKGROUND

Recent advances in high-throughput DNA sequencing technologies have made it possible to characterize the microbial profile in anatomical sites previously assumed to be sterile. We used this approach to explore the microbial composition within joints of osteoarthritic patients.

METHODS

This prospective multicenter study recruited 113 patients undergoing hip or knee arthroplasty between 2017 and 2019. Demographics and prior intra-articular injections were noted. Matched synovial fluid, tissue, and swab specimens were obtained and shipped to a centralized laboratory for testing. Following DNA extraction, microbial 16S-rRNA sequencing was performed.

RESULTS

Comparisons of paired specimens indicated that each was a comparable measure for microbiological sampling of the joint. Swab specimens were modestly different in bacterial composition from synovial fluid and tissue. The 5 most abundant genera were Escherichia, Cutibacterium, Staphylococcus, Acinetobacter, and Pseudomonas. Although sample size varied, the hospital of origin explained a significant portion (18.5%) of the variance in the microbial composition of the joint, and corticosteroid injection within 6 months before arthroplasty was associated with elevated abundance of several lineages.

CONCLUSIONS

The findings revealed that prior intra-articular injection and the operative hospital environment may influence the microbial composition of the joint. Furthermore, the most common species observed in this study were not among the most common in previous skin microbiome studies, suggesting that the microbial profiles detected are not likely explained solely by skin contamination. Further research is needed to determine the relationship between the hospital and a "closed" microbiome environment. These findings contribute to establishing the baseline microbial signal and identifying contributing variables in the osteoarthritic joint, which will be valuable as a comparator in the contexts of infection and long-term arthroplasty success.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Spine or Hip First? Outcomes in Patients Undergoing Sequential Lumbar Spine or Hip surgery

INTRODUCTION

Lumbar spine pathology frequently coexists in patients who have hip arthrosis. There is controversy on whether lumbar or hip pathology should be first addressed. The purpose of this study was to evaluate the outcomes of sequential lumbar spine (LSP) or hip arthroplasty (THA).

METHODS

Using a large national database from 2010 to 2020, we reviewed the records of 241,279 patients who had concurrent hip arthritis and lumbar spine disease defined as spinal stenosis, lumbar radiculopathy, or degenerative disc disease. During the study period, 6,458 (2.7%) patients with concurrent hip/spine disease underwent sequential operative treatment of either the hip joint or lumbar spine within 2 years. The rates of subsequent surgery in either the hip or spine, opioid requirements, and rates of hip dislocation were determined and analyzed using compared Chi-squared analyses.

RESULTS

Patients undergoing THA first had lower risk of subsequent spinal procedure compared to patients who had spinal procedures first (5.7 vs. 23.7 %, P < 0.001). This disparity was maintained up to 5 years (P<0.001). Opioid requirements at 1 year were highest in patients who underwent spinal procedures only (836 pills/patient) compared to any other group (THA only (566 pills/patient), LSP and then THA (564 pills/patient), THA and LSP (586 pills/patient). Also, THA following LSP was associated with significantly higher rates of dislocation compared to patients undergoing THA first (3.2 versus 1.9%, P<0.001).

SUMMARY

Total hip arthroplasty first in patients who have concurrent spine disease was associated with lower risk of subsequent surgery, opioid requirement, and risk of postoperative instability compared to patients having lumbar procedure first.

What is the Value of a Balanced Total Knee Arthroplasty? Getting it Right the First Time

INTRODUCTION

Instability is a leading cause of early failure following total knee arthroplasty. Enabling technologies can improve accuracy, but their clinical value remains undetermined. The purpose of this study was to determine the value of achieving a balanced knee joint at the time of TKA.

METHODS

A Markov model was developed to determine the value from reduced revisions and improved outcomes associated with TKA joint balance. Patients were modelled for the first 5 years following TKA. The threshold to determine cost-effectiveness was set at an Incremental Cost Effectiveness Ratio (ICER) of $50,000/quality-adjusted life year (QALY). A sensitivity analysis was performed to evaluate the influence of QALY improvement (ΔQALY) and Revision Rate Reduction (ΔRevision) on additional value generated compared to a conventional TKA cohort. The impact of each variable was evaluated by iterating over a range of ΔQALY (0 to 0.046) and ΔRevision (0 to 30%) and calculating the value generated while satisfying the ICER threshold. Finally, the impact of surgeon volume on these outcomes were analyzed.

RESULTS

The total value of a balanced knee for the first 5 years was $8,750, $6,575, and $4,417 per case, for low, medium, and high-volume surgeons, respectively. Change in QALY accounted for greater than 90% of the value gain with a reduction in revisions making up the rest in all scenarios. The economic contribution of revision reduction was relatively constant regardless of surgeon volume ($500/case).

CONCLUSIONS

Achieving a balanced knee had the greatest impact on QALY improvement over early revision rate. These results can help assign value to enabling technologies with joint balancing capabilities.

Wound complications following revision total knee arthroplasty: Prevalence and outcomes

BACKGROUND

Wound complications following revision TKA can be catastrophic and can compromise joint and even limb. The purpose of this study was to determine the prevalence of superficial wound complications requiring return to the OR in revision TKA, rates of subsequent deep infection, factors that increase the risk of superficial wound complications, and the outcomes of revision TKA following development of superficial wound complications.

METHODS

We retrospectively reviewed 585 consecutive TKA revisions with at least two years follow-up, including 399 aseptic revisions and 186 reimplantations. Superficial wound complications without deep infection requiring return to the OR within 120 days were compared to controls.

RESULTS

Fourteen patients following revision TKA (2.4%) required return to the OR for a wound complication, including 7 of 399 (1.8%) patients who underwent aseptic revision TKA and 7 of 186 (3.8%) patients undergoing reimplantation TKA (p = 0.139). Aseptic revisions with wound complications were more likely to develop subsequent deep infection (HR 10.04, CI 2.24-45.03, p = 0.003), but this did not hold true for reimplantations (HR 1.17, CI 0.28-4.91, p = 0.829). Risk factors for wound complication included atrial fibrillation when all patients were combined (RR 3.98, CI 1.15-13.72, p = 0.029), connective tissue disease in the aseptic revision group (RR 7.1, CI 1.1-44.7, p = 0.037), and a history of depression in the re-implantation group (RR 5.8, CI 1.1-31.5, p = 0.042).

Dual-Mobility Articulations in Total Hip Arthroplasty: A Durable Game Changer or the Next Cause for Concern?

The use of dual-mobility articulations in total hip arthroplasty (THA) is increasing. The appeal of dual-mobility implants rests in their ability to increase the effective ball head size for a given THA construct compared with conventional bearings, thereby reducing the risk of postoperative instability. Although the concept of dual-mobility articulation in THA is not new and early clinical experience dates back to the 1970s, its widespread use is a relatively recent phenomenon. Furthermore, unlike European surgeons who routinely use monoblock dual-mobility acetabular components in THA, the most common dual-mobility implants used in North America and worldwide are of a modular nature in which a metallic liner is coupled to a multibearing acetabular component and thus creating a metal-on-metal interface. It is important to review the evidence for the indications for dual-mobility implants in both primary and revision THA; present basic science data on the risk of corrosion in modular dual-mobility implants; and highlight the possible ongoing questions and concerns with dual-mobility implants. The goal is to provide a balanced critical review of this technology and define its current place in the hip surgeon's armamentarium.

Personalizing Revision Tibial Baseplate Position and Stem Trajectory With Custom Implants Using 3D Modeling to Optimize Press-fit Stem Placement

Background

A common tibial construct for revision total knee arthroplasty includes a long diaphyseal engaging press-fit stem. Due to tibial canal bowing, compromises are often necessary to match patient anatomy when choosing stemmed implants. The objective of this study is to determine through 3-D modeling whether current implant press-fit options appropriately fit patient anatomy, or whether an alternative angle between the stem and baseplate could increase the cortical engagement of long press-fit tibial stems.

Methods

Preoperative computerized tomography scans from 100 patients undergoing TKA were imported into an image-processing software program. Three-dimensional models were created with tibial stems placed at a fixed perpendicular angle and a custom angle to the revision tibial baseplate. Stem diameter, depth, offset, and contact surface area were measured and analyzed between the 2 groups.

Results

Significantly more cortical contact, larger stem diameter, and smaller offset of the custom keel from the center of the baseplate were associated with free custom tibial stem placement vs a fixed perpendicular baseplate-stem interface (P < .001). Statistically significant differences were also found between different patient demographics.

Conclusions

Custom free-angle stem placement allows for increased stem diameter and cortical contact of press-fit tibial stems compared to existing constructs that must interface with the baseplate at a 90-degree angle. Current revision tibia implants limit fixation of tibial press-fit stems and often mismatch with patient anatomy. Alternative ways to fit patient anatomy may be beneficial for patients with extreme mismatch. In the future, custom keel angles may help to resolve this problem.

An Enhanced Understanding of Culture-Negative Periprosthetic Joint Infection with Next-Generation Sequencing: A Multicenter Study

BACKGROUND

The challenges of culture-negative periprosthetic joint infection (PJI) have led to the emergence of molecular methods of pathogen identification, including next-generation sequencing (NGS). While its increased sensitivity compared with traditional culture techniques is well documented, it is not fully known which organisms could be expected to be detected with use of NGS. The aim of this study was to describe the NGS profile of culture-negative PJI.

METHODS

Patients undergoing revision hip or knee arthroplasty from June 2016 to August 2020 at 14 institutions were prospectively recruited. Patients meeting International Consensus Meeting (ICM) criteria for PJI were included in this study. Intraoperative samples were obtained and concurrently sent for both routine culture and NGS. Patients for whom NGS was positive and standard culture was negative were included in our analysis.

RESULTS

The overall cohort included 301 patients who met the ICM criteria for PJI. Of these patients, 85 (28.2%) were culture-negative. A pathogen could be identified by NGS in 56 (65.9%) of these culture-negative patients. Seventeen species were identified as common based on a study-wide incidence threshold of 5%. NGS revealed a polymicrobial infection in 91.1% of culture-negative PJI cases, with the set of common species contributing to 82.4% of polymicrobial profiles. Escherichia coli, Cutibacterium acnes, Staphylococcus epidermidis, and Staphylococcus aureus ranked highest in terms of incidence and study-wide mean relative abundance and were most frequently the dominant organism when occurring in polymicrobial infections.

CONCLUSIONS

NGS provides a more comprehensive picture of the microbial profile of infection that is often missed by traditional culture. Examining the profile of PJI in a multicenter cohort using NGS, this study demonstrated that approximately two-thirds of culture-negative PJIs had identifiable opportunistically pathogenic organisms, and furthermore, the majority of infections were polymicrobial.

LEVEL OF EVIDENCE

Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Does a 2-Stage Debridement Result in Higher Rates of Implant Retention Compared With Single Debridement Alone?

BACKGROUND/METHODS

We retrospectively reviewed 89 patients with acute prosthetic joint infection treated with debridement, antibiotics, and implant retention (DAIR) or 2-DAIR. Patients had <3 weeks of symptoms and met Musculoskeletal Infection Society criteria for infection. Sixty-three patients were treated with DAIR, whereas 26 patients were managed using a 2-DAIR protocol where patients underwent initial debridement, antibiotic bead placement, and subsequent return to the operating room at an average of 16.3 days for repeat debridement and modular component exchange. Patients received a 6-week course of intravenous antibiotics and 3 months of oral antibiotics for suppression. Demographics, comorbidities, implant retention rates, and complications were compared between the groups. The McPherson host type and infection type classification system were used to categorize patients in both the DAIR and 2-DAIR groups. Regression analysis was performed to control postoperative vs acute hematogenous infection, procedure, and comorbidities. The McPherson host types and infection types were not different between DAIR and 2-DAIR patients, P = .728 and P = .061, respectively.

RESULTS

There was no difference in the overall implant retention rate between DAIR and 2-DAIR (63.49% vs 69.23%, P = .605). The average days to reinfection was significantly longer for the 2-DAIR cohort compared with DAIR (271.3 vs 165.3, P = .024) in patients who failed treatment. However, when controlling for infection, microorganism, index procedure, and comorbidities, there was no difference in days to reinfection (P = .679). There were no differences in complications, 90-day readmission, or revision rates between the groups.

CONCLUSIONS

A staged debridement for acute prosthetic joint infection did not improve the rates of infection control. Randomized trials are needed to define indications and potential benefits of 2-DAIR.

HTX-011 in Combination with Multimodal Analgesic Regimen Minimized Severe Pain and Opioid Use after Total Knee Arthroplasty in an Open-Label Study

Total knee arthroplasty (TKA) can be associated with significant postoperative pain despite multimodal analgesic (MMA) protocols, and most patients require the use of opioids postoperatively. HTX-011 is a dual-acting local anesthetic containing bupivacaine and low-dose meloxicam in an extended-release polymer. In a prior randomized controlled trial (RCT), HTX-011 reduced pain and opioid use through 72 hours after TKA compared with bupivacaine hydrochloride. This open-label study (NCT03974932) evaluated the efficacy and safety of HTX-011 combined with an MMA regimen in patients undergoing TKA under spinal anesthesia. All patients received intraoperative HTX-011 (400 mg bupivacaine/12 mg meloxicam) in combination with an MMA regimen consisting of preoperative acetaminophen, celecoxib, and pregabalin and postoperative acetaminophen and celecoxib until discharge. Opioid rescue was allowed upon patient request for additional pain control. Pain scores, opioid consumption, discharge readiness, and adverse events were recorded. Fifty-one patients were treated. Compared with the prior RCT, HTX-011 with this MMA regimen further lowered pain scores and reduced opioid use. Mean patient-reported pain scores remained in the mild range, and 82% of patients or more did not experience severe pain at any individual time point through 72 hours after surgery. Mean total opioid consumption was low over 72 hours: 24.8 morphine milligram equivalents (1-2 tablets of oxycodone 10 mg/day). Approximately 60% of patients were ready for discharge by 12 hours, and 39% were discharged without an opioid prescription and did not call back for pain management. The treatment regimen was well tolerated, and no added risk was observed with the addition of MMA. HTX-011 with an MMA regimen reduced postoperative pain and opioid use following TKA.

What Is the Alignment and Balance of a Total Knee Arthroplasty Performed Using a Calipered Kinematic Alignment Technique?

METHODS

We simulated calipered kinematic alignment total knee arthroplasty (cKATKA) using alignment data and ligament tensions acquired during 607 consecutive robotic-assisted TKAs performed using a dynamic ligament tensor. The distal femur was resected parallel to the native joint line accounting for cartilage loss. The proximal tibial resection necessary to achieve extension gap balance was calculated for each knee. Similarly, symmetric posterior condylar resections prescribed by this method were simulated and the tibial resection needed to achieve a balanced flexion gap calculated. Finally, the resultant limb alignment and degree of joint balance in both flexion and extension of each knee were determined and categorized according to the preoperative knee alignment.

RESULTS

Increasing preoperative varus deformity required a greater tibial varus cut to achieve a balanced extension gap (P < .0001). There was no correlation between tibial varus angle and flexion gap balance (P > .1). For mild varus deformities 81% and 95% of knees could be balanced and have an overall limb alignment within 3° and 5° from the mechanical axis respectively. For knees with moderate-severe varus, only 37% and 74% could be balanced within these alignment boundaries (P < .01). Overall, 95% of these simulated knees could be balanced with an overall alignment within 0° ± 5°. However, 50% of the simulated TKAs had looser medial gaps in flexion compared to the lateral gap.

CONCLUSIONS

Application of the cKATKA method can yield TKAs within 0° ± 5° of mechanical axis alignment by simply adjusting the proximal tibial resection without ligament releases. However, an undesirable flexion gap balance was predicted in nearly 50% of the TKAs.

The Diagnosis and Treatment of Acetabular Bone Loss in Revision Hip Arthroplasty: An International Consensus Symposium

Despite growing evidence supporting the evaluation, classification, and treatment of acetabular bone loss in revision hip replacement, advancements have not been systematically incorporated into a single document, and therefore, a comprehensive review of the treatment of severe acetabular bone loss is needed. The Stavros Niarchos Foundation Complex Joint Reconstruction Center at Hospital for Special Surgery held an Acetabular Bone Loss Symposium on June 21, 2019, to answer the following questions: What are the trends, emerging technologies, and areas of future research related to the evaluation and management of acetabular bone loss in revision hip replacement? What constitutes the optimal workup and management strategies for acetabular bone loss? The 36 international experts convened were divided into groups, each assigned to discuss 1 of 4 topics: (1) preoperative planning and postoperative assessment; (2) implant selection, management of osteolysis, and management of massive bone loss; (3) the treatment challenges of pelvic discontinuity, periprosthetic joint infection, instability, and poor bone biology; and (4) the principles of reconstruction and classification of acetabular bone loss. Each group came to consensus, when possible, based on an extensive literature review. This document provides an overview of these 4 areas, the consensus each group arrived at, and directions for future research.

Robotic-Assisted versus Manual Unicompartmental Knee Arthroplasty: Contemporary Systematic Review and Meta-analysis of Early Functional Outcomes

Robotic-assisted unicompartmental knee arthroplasty (RA-UKA) aims to improve accuracy of component placement. Studies have shown improvement in radiographic positioning/alignment with RA-UKA but have not addressed clinical outcome measures (COMs). The purpose of this study was to determine if RA-UKA is associated with improved early revision rates and functional outcome scores (FOS) compared with manual UKA. A systematic review of all English language articles from 1999 to 2019 on RA-UKA using Medline, EMBASE, Scopus, and Web of Science databases identified 277 studies. Seven (three randomized controlled trials) met inclusion criteria. Revision rates/FOS were aggregated for RA-UKA and manual UKA; a forest plot was constructed utilizing inverse variance/Mantel-Haenszel fixed-effects meta-analysis. The seven articles included a total of 363 RA-UKA patients and 425 manual UKA patients. Mean age was 66 ± 3.5 and 65 ± 4.0 years, and mean body mass index (BMI) was 26.8 ± 2.1 and 27.1 ± 1.5 kg/m², respectively. Mean follow-up was 25.5 months (4.5-48) and 29.1 months (4.5-48) for RA-UKA and manual UKA, respectively. At latest follow-up, RA-UKA patients showed a 26% ± 12 improvement in COMs versus 24% ± 12 improvement for manual UKA patients (p = 0.6). The revision rate was 3% for both groups (p = 0.8); however, a meta-analysis of RCTs showed no difference. Robotic and manual UKAs offer comparable improvements in pain, FOS, and revision rates. The effects of follow-up duration, ceiling effects of COMs, and surgeon experience remain unknown. Future studies comparing robotic versus manual UKAs with longer term follow-up may inform further benefits of each, with respect to component durability, alignment, and functional improvement.

Is Conversion TKA a Primary or Revision? Clinical Course and Complication Risks Approximating Revision TKA Rather Than Primary TKA

BACKGROUND

Conversion total knee arthroplasty (convTKA) is associated with increased resource utilization and costs compared with primary TKA. The purpose of this study is to compare 1) surgical time, 2) hospitalization length (LOS), 3) complications, 4) infection, and 5) readmissions in patients undergoing convTKA to both primary TKA and revision TKA patients.

METHODS

The American College of Surgeons National Surgical Quality Improvement Project database was queried from 2008 to 2018. Patients undergoing convTKA (n = 1,665, 0.5%) were defined by selecting Current Procedural Terminology codes 27,447 and 20,680. We compared the outcomes of interest to patients undergoing primary TKA (n = 348,624) and to patients undergoing aseptic revision TKA (n = 8213). Univariate and multivariate logistic regression was performed to identify the relative risk of postoperative complications.

RESULTS

Compared with patients undergoing primary TKA, convTKA patients were younger (P < .001), had lower body mass index (P < .001), and were less likely to be American Society of Anesthesiologist class III/IV (P < .001). These patients had significantly longer operative times (122.6 vs 90.3 min, P < .001), increased LOS (P < .001), increased risks for any complication (OR 1.94), surgical site infection (OR 1.84), reoperation (OR 2.18), and readmissions (OR 1.60) after controlling for confounders. Compared with aseptic TKA revisions, operative times were shorter (122.6 vs 148.2 min, P < .001), but LOS (2.91 vs 2.95 days, P = .698) was similar. Furthermore, relative risk for any complication (P = .350), surgical site infection (P = .964), reoperation (P = .296), and readmissions (P = .844) did not differ.

CONCLUSION

Conversion TKA procedures share more similarities with revision TKA rather than primary TKA procedures. Without a distinct procedural and diagnosis-related group, there are financial disincentives to care for these complex patients.

LEVEL OF EVIDENCE

II.

Dual Mobility Reduces Dislocations-Why I Use It in All Revisions

BACKGROUND

Instability remains the most common complication after revision total hip arthroplasty (THA) and presents a unique treatment dilemma for the orthopedic surgeon. Dual mobility (DM) bearing articulations have been used in France since the 1970s, but have only become more widely adopted in the United States over the last decade. The purpose of this symposium was to discuss the role for DM bearings in revision THA.

METHODS

We reviewed the existing literature on outcomes after DM bearing articulations in revision THA. We also report several case examples of the use of DM in difficult revision THA cases, including acetabular bone loss, failed constrained liner, and adverse local tissue reaction. Finally, we briefly discuss the limitations associated with the use of DM.

RESULTS

Several large retrospective series demonstrate that DM bearings reduce the incidence of dislocation after revision THA when compared with conventional single bearing THA. Specific complications related to DM bearings including polyethylene wear, loosening, intraprosthetic dislocation, and corrosion remain a concern, but appear to have drastically improved over time with modern implant designs.

CONCLUSION

Contemporary DM designs have been established as an effective bearing option to reduce instability in revision THA, although concerns do exist. High-quality prospective studies are necessary to further define the role this bearing option has in the coming years.

Clinical Concerns With Dual Mobility- Should I Avoid it When Possible?

The utilization of dual mobility (DM) articulations in total hip arthroplasty (THA) is increasing. The principal appeal of DM implants is its ability to reduce postoperative instability by maximizing the effective ball head size for each reconstruction. However, while DM implants have been used worldwide for over 3 decades, the experience in North America is more limited. Moreover, there remains concerns with intraprosthetic dissociation, wear, metallosis, and soft tissue impingement. Therefore, the purpose of this article is to review the available evidence for these potential issues. First, intraprosthetic dissociation (IPD) is a unique complication of DM implants. Although the rate has decreased with improvements in materials and design, the reported prevalence is approximately 1%. Second, wear in DM implants can be unpredictable and increased wear has been reported in younger, active patients. Third, corrosion in modular DM implants has been described and elevations in serum cobalt and chromium levels have been reported. While the clinical significance of these elevations is unclear, it remains a source of concern with these implants. Finally, psoas impingement and entrapment can be a source of persistent groin pain after THA. DM articulations are a valuable addition to the armamentarium of total hip surgeons. However, these bearings are not free of complications. Consequently, current data only support selective use of DM bearings in patients at increased risk for postoperative instability after arthroplasty.

Fretting Corrosion, Third-Body Polyethylene Damage, and Cup Positioning in Primary vs Revision Dual Mobility Total Hip Arthroplasty

BACKGROUND

Dual mobility (DM) articulations were introduced for total hip arthroplasty to reduce the risk of instability for patients who have a high risk of dislocation. The use of DM constructs in both primary and revision total hip arthroplasty has been steadily increasing, leading to concerns regarding potential risks of fretting corrosion, polyethylene wear, metal release, and failure due to component positioning.

METHODS

A total of 56 retrieved DM constructs were collected. The inner and outer polyethylene liner surfaces were assessed for 7 damage mechanisms, and fretting corrosion was evaluated for the femoral stem, head, and modular liner. Three polyethylene liners with the greatest amounts of embedded debris were examined using scanning electron microscopy. Energy-dispersive X-ray spectroscopy was used to determine the elemental content of the debris. Acetabular cup orientation was analyzed radiographically using the EBRA (Einzel-Bild-Roentgen-Analyse) method.

RESULTS

The devices were revised most frequently for infection (36%), loosening (21%), and instability/dislocation (18%). The most common polyethylene damage mechanisms were scratching, pitting, burnishing, and embedded debris, and no difference in total damage was found between primary and revision cases. Scanning electron microscopy/energy-dispersive X-ray spectroscopy revealed that debris morphology and composition were consistent with porous titanium coating, resulting from cup loosening or broken screws and augments. A total of 71% and 50% of the constructs were determined to be within the Lewinnek safe zone for inclination and anteversion, respectively.

CONCLUSION

The most notable mechanisms of surface damage were due to third-body debris, especially for the polyethylene surfaces which articulate against cobalt-chromium femoral heads and acetabular liners. Scratching of the femoral head and the metal liner from this debris may support the clinical use of ceramic for DM bearing surfaces in the future.

Spine Fusions, Yoga Instructors, and Hip Fractures: The Role of Dual Mobility in Primary Total Hip Arthroplasty

BACKGROUND

Despite the increased use of dual mobility (DM) in primary total hip arthroplasty (THA), debate exists regarding the indications for its use. No specific algorithm exists to guide this decision-making process. Therefore, the purpose of this article is to summarize the currently available literature regarding the use of DM in primary THA and provide evidence-based guidelines based on specific patient populations and risk factors for instability.

METHODS

We reviewed the current literature for studies evaluating risk factors for dislocation in primary THA, as well as the clinical use and results of DM in primary THA. Based on the strength of the literature, we discuss the use of DM in specific patient populations. We provide a decision-making algorithm to determine whether a patient may be indicated for DM in primary THA.

RESULTS

Surgeons should consider preoperative patient demographics, risk factors for instability (eg, significant hip-spine issues), type of procedure to be performed (eg, conversion arthroplasty), and indications for surgery (eg, THA for femoral neck fracture). Based on this algorithmic assessment, DM may be warranted in the primary THA setting if a patient's combined risk reaches an established threshold based on the literature.

CONCLUSION

This evidence-based algorithm may help guide current practice in the use of DM in primary THA. We advocate the continued judicious use of DM in hip arthroplasty. Longer term studies are needed in order to evaluate the durability of DM, as well as any complications related to the DM articulation.

Can a robot help a surgeon to predict a good total knee arthroplasty?

AIMS

Neither a surgeon's intraoperative impression nor the parameters of computer navigation have been shown to be predictive of the outcomes following total knee arthroplasty (TKA). The aim of this study was to determine whether a surgeon, with robotic assistance, can predict the outcome as assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) for pain (KPS), one year postoperatively, and establish what factors correlate with poor KOOS scores in a well-aligned and balanced TKA.

METHODS

A total of 134 consecutive patients who underwent TKA using a dynamic ligament tensioning robotic system with a tibia first resection technique and a cruciate sacrificing ultracongruent TKA system were enrolled into a prospective study. Each TKA was graded based on the final mediolateral ligament balance at 10° and 90° of flexion: 1) < 1 mm difference in the thickness of the tibial insert and that which was planned (n = 75); 2) < 1 mm difference (n = 26); 3) between 1 mm to 2 mm difference (n = 26); and 4) > 2 mm difference (n = 7). The mean one-year KPS score for each grade of TKA was compared and the likelihood of achieving an KPS score of > 90 was calculated. Finally, the factors associated with lower KPS despite achieving a high-grade TKA (grade A and B) were analyzed.

RESULTS

Patients with a grade of A or B TKA had significantly higher mean one-year KPS scores compared with those with C or D grades (p = 0.031). There was no difference in KPS scores in grade A or B TKAs, but 33% of these patients did not have a KPS score of > 90. While there was no correlation with age, sex, preoperative deformity, and preoperative KOOS and Patient-Reported Outcomes Measurement Information System (PROMIS) physical scores, patients with a KPS score of < 90, despite a grade A or B TKA, had lower PROMIS mental health scores compared with those with KPS scores of > 90 (54.1 vs 50.8; p = 0.043). Patients with grade A and B TKAs with KPS > 90 were significantly more likely to respond with "my expectations were too low", and with "the knee is performing better than expected" compared with patients with these grades of TKA who had a KPS score of < 90 (40% vs 22%; p = 0.004).

CONCLUSION

A TKA balanced with robotic assistance to within 1 mm of difference between the medial and lateral sides in both flexion and extension had a higher KPS score one year postoperatively. Despite accurate ligament balance information, a robotic system could not guarantee excellent pain relief. Patient expectations and mental status also significantly affected the perceived success of TKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):67-73.

Reduced postoperative morbidity in computer-navigated total knee arthroplasty: A retrospective comparison of 225,123 cases

BACKGROUND

Total knee arthroplasty (TKA) is one of the most common elective surgical procedures in the United States, with more than 650,000 performed annually. Computer navigation technology has recently been introduced to assist surgeons with planning, performing, and assessing TKA bone cuts. The aim of this study is to assess postoperative complication rates after TKA performed using computer navigation assistance versus conventional methods.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was queried for unilateral TKA cases from 2008 to 2016. The presence of the CPT modifier for use of computer navigation was used to separate cases of computer-navigated TKA from conventional TKA. Multivariate and propensity-matched logistic regression analyses were performed to control for demographics and comorbidities.

RESULTS

There were 225,123 TKA cases included; 219,880 were conventional TKA (97.7%) and 5,243 were navigated (2.3%). Propensity matching identified 4,811 case pairs. Analysis demonstrated no significant differences in operative time, length of stay, reoperation, or readmission, and no differences in rates of post-op mortality at 30 days postoperatively. Compared to conventional cases, navigated cases were at lower risk of serious medical morbidity (18% lower, p = 0.009) within the first 30 days postoperatively.

CONCLUSION

After controlling for multiple known risk factors, navigated TKA patients demonstrated lower risk for medical morbidity, predominantly driven by lower risk for blood transfusion. Given these findings, computer-navigation is a safe surgical technique in TKA.

Metal ion levels with use of modular dual mobility constructs: Can the evidence guide us on clinical use?

Introduction

Dual mobility (DM) use in total hip arthroplasty (THA) has increased, particularly for prevention and management of instability. However, a modular interface raises concern for metal ion generation. The purpose of this study was to determine the 1) serum cobalt and chromium levels; 2) prevalence of ion levels >1 mcg/L; and 3) effect of femoral head material on ion levels following THA using modular DM bearings.

Methods

We performed a systematic review (MEDLINE, Embase, Cochrane databases) for articles relating to metal ion levels and modular DM (MDM) THA. Eight studies (290 patients) met the inclusion criteria. We recorded post-operative ion levels at a minimum of 12 months, and compared levels with ceramic (n = 125) and metal femoral heads (n = 165). A meta-analysis could not be performed due to poor study quality and heterogeneity.

Results

At average follow-up of 30.4 months, mean cobalt level was 0.71 mcg/L, and mean chromium level was 0.66 mcg/L [22 patients (8%) had elevated ion levels above 1 mcg/L]. When compared to MDM with a ceramic head, metal head use had higher cobalt (1.26 vs. 0.42 mcg/L) and chromium levels (1.23 vs. 0.46 mcg/L). MDM with a metal head was 1.30 times more likely to have elevated ion levels >1 mcg/L. There was no effect of ion levels on outcome scores.

Conclusions

Measurable elevations of serum cobalt and chromium levels are present in patients with well-functioning MDM THAs. The impact and contributions of the additional metal liner interface are still unclear. The use of a ceramic head appears to mitigate ion release, while reducing other mechanisms of metallosis like taper corrosion. Higher quality studies are necessary to understand whether MDM bearings pose long term issues. Until then, the judicious use of MDM articulations is recommended.

Micromotion Analysis of Various Tibial Constructs in Moderate Tibial Defects in Revision Total Knee Arthroplasty

BACKGROUND

The purpose of this study is to compare the micromotion of various tibial reconstruction strategies including short cemented and long cementless stems with or without metaphyseal augmentation.

METHODS

A moderate tibial bone defect was milled into dual density polyurethane test blocks. Mechanical testing was performed on 4 test constructs: (1) short cemented stem (75-mm total length) alone; (2) short cemented stem with a symmetric metaphyseal cone; (3) a press-fit (175-mm total length) diaphyseal engaging tibial construct without a cone, and (4) the same press-fit tibial construct with a metaphyseal cone augment. Micromotion of the baseplate/cone construct with respect to the tibia block was measured during a stair descent loading profile for 10,000 cycles. The peak-to-peak micromotion of these various tibial constructs was compared. Unpaired t-tests were used to evaluate differences in peak-to-peak micromotion among the various tibial constructs tested. An analysis of variance was performed for final validation.

RESULTS

The cemented short stem demonstrated similar varus/valgus displacement, internal/external rotation, compression, and lift-off micromotion values under loading compared to a cementless long stem. A tibial cone improved compression and lift-off micromotion for both cemented and cementless constructs. A short 50-mm cemented stem with a cone demonstrated a lower micromotion at the anterior SI location compared to a press-fit 150-mm cementless stem without a tibial cone.

CONCLUSIONS

A short cemented tibial component with a cone achieved similar micromotion during simulated stair descent compared to a cementless diaphyseal press-fit implant in cases of moderate tibial defects.

Mortality and Complications in Patients with Metastatic Disease after Primary Total Hip and Total Knee Arthroplasty

BACKGROUND

Although palliative therapies such as radiation are usually performed to improve quality of life in patients with metastatic disease, arthroplasty for joint pain may be indicated in some cases. Therefore, the purpose of this study is to evaluate the 30-day mortality risk, the risk of complications including infection and venous thromboembolic events, and the rate of 30-day reoperations and readmissions in patients with metastatic disease undergoing primary total hip and total knee arthroplasty (THA/TKA).

METHODS

We reviewed the National Surgical Quality Improvement Program database from 2008 to 2018 to evaluate rates of postoperative complications after elective primary THA/TKA in patients with disseminated cancer. After exclusions, 205,007 patients undergoing primary THA and 352,337 undergoing primary TKA were retained for analysis: 942 (0.2%) with disseminated cancer. Chi-square was used to compare proportions between groups. Univariate and multivariate logistic regression was used to model the odds ratio of patients with disseminated cancer compared with those without disseminated cancer.

RESULTS

After adjustment for covariates, patients with disseminated cancer had a higher risk of death (OR: 5.25, 95% CI: 2.47-11.17), any complication (OR: 1.95, 95% CI: 1.63-2.33), deep venous thrombosis (OR: 2.39, 95% CI: 1.32-4.35), pulmonary embolism (OR: 3.07, 95% CI: 1.52-6.17), cardiovascular complications (OR: 2.98, 95% CI: 1.47-6.04), transfusion (OR: 2.21, 95% CI: 1.82-2.69), reoperations (OR: 1.89, 95% CI: 1.28-2.78), readmissions (OR: 2.51, 95% CI: 1.95-3.23), and longer length of stay (4.3 vs 2.7 days).

CONCLUSION

Patients with disseminated cancer have significantly elevated risk of complications after elective primary THA/TKA. Understanding the severity of complications is critical to the risk-benefit analysis that confronts patients and surgeons considering surgery.

LEVEL OF EVIDENCE

II.

How to Develop a Fair Revision Arthroplasty Bundle? Using Perioperative Complications and Readmissions to Investigate

BACKGROUND

The next frontier for value-based health care in total joint arthroplasty is revision surgery. Although the disparity in health care utilization between revision procedures compared with primary total hip and total knee arthroplasty (THA/TKA) procedures is recognized, no agreement regarding the risk adjustment necessary to make revision bundles fair to both payors and providers exists. The purpose of this study is to use the risk of perioperative complications and readmissions of patients undergoing revision THA/TKA to establish the foundations of a fair revision arthroplasty bundle.

METHODS

We retrospectively evaluated a consecutive series of 484 aseptic THA/TKA revisions performed at our institution over a 12-month period and compared complications, length of stay, reoperations, and 90-day readmissions to a group of 802 consecutive patients undergoing primary THA/TKA.

RESULTS

169 (34.9%) patients experienced major complications after revision THA/TKA compared with 176 (21.9%) patients undergoing primary THA/TKA (P < .001), (OR 1.91 CI 1.49-2.45, P < .001). Patients undergoing revision TKA were 3.64 times more likely to require hospitalization greater than 3 days (OR 2.59-5.12, CI 95%, P < .001), whereas patients undergoing revision THA were 4.46 times more likely to require hospitalization greater than 3 days (OR 2.89-6.87, CI 95%, P < .001). Revision patients were 3X more likely to have a 90-day readmission and 4X more likely to have a reoperation.

CONCLUSION

For a revision bundle to be fair and widely adopted, either significant financial incentive must be instituted or the latitude given to exclude outliers from the final reconciliation. This must be adjusted to not disincentivize institutions from providing care for failed hip and knee arthroplasties.

Instability After All-Cause Acetabular-Only Revision Total Hip Arthroplasty Remains a Clinical Problem

BACKGROUND

The purpose of this study is to (1) evaluate the rate of instability and reoperation after acetabular component-only revision, (2) compare instability rates across various head sizes, and (3) determine patient factors correlating with postoperative instability.

METHODS

We retrospectively reviewed all isolated acetabular component revisions (n = 200) at our institution between 2007 and 2017. Patients with less than one-year follow-up were excluded. Patients were subdivided into 4 head size groups: (1) 32 mm or less, (2) 36 mm or more, (3) dual mobility, and (4) constrained liners. Factors including the body mass index, cup position, prior revision(s), and subsequent reoperation were compared across groups.

RESULTS

189 patients (200 hips) met the inclusion criteria. The overall rate of instability was 12% (n = 24), and 37 (18.5%) cases underwent subsequent revision, including 11 cases for recurrent instability. There was no significant difference in postoperative dislocation or reoperation for instability across the various groups. The use of a constrained liner trended toward the highest rate of postoperative instability (36.4%, P = .090). History of preoperative instability was a significant risk factor for postoperative instability with or without history of prior revision (P = .011 and P = .001, respectively).

CONCLUSION

Contemporary isolated acetabular revision is still associated with significant rates of instability. Surprisingly, the head size was not a predictive factor for postoperative dislocation or reoperation, but a prior history of instability was associated with postoperative instability. Patients revised to a constrained liner experienced highest rates of failure and remain an unsolved clinical problem.

HTX-011 Reduced Pain and Opioid Use After Primary Total Knee Arthroplasty: Results of a Randomized Phase 2b Trial

BACKGROUND

HTX-011 is an extended-release, dual-acting local anesthetic consisting of bupivacaine and low-dose meloxicam in a novel polymer that is administered by needle-free application during surgery. The active ingredients are released from the polymer by controlled diffusion over 72 hours.

METHODS

This phase 2b, double-blind, placebo-controlled and active-controlled trial enrolled patients undergoing primary unilateral total knee arthroplasty under general anesthesia. Two hundred thirty-two patients were randomized into 4 groups: HTX-011 400 mg bupivacaine/12 mg meloxicam, applied without a needle into the surgical site, the same dose of HTX-011 with a separate 50 mg ropivacaine injection into the posterior capsule, bupivacaine hydrochloride (HCl) 125 mg injection, and saline placebo injection. Only opioids were permitted for postoperative pain rescue. Primary and key secondary endpoints were mean area under the curve of pain intensity scores over 48 hours and 72 hours, respectively, for HTX-011 groups vs placebo.

RESULTS

Both HTX-011 groups had significantly reduced mean pain intensity vs placebo through 48 and 72 hours (both P < .001). Ropivacaine added a small initial benefit in the first 12 hours. Both HTX-011 groups also had decreased mean pain intensity vs bupivacaine HCl alone through 48 and 72 hours (P < .05). The HTX-011 groups had significantly earlier discharge readiness along with lower opioid consumption through 72 hours. HTX-011 alone or with ropivacaine was well-tolerated with a safety profile similar to controls.

CONCLUSION

Needle-free application of HTX-011 400 mg bupivacaine/12 mg meloxicam provided superior pain reduction through 72 hours after total knee arthroplasty compared with placebo and bupivacaine HCl alone.

Third generation delta ceramic-on-ceramic bearing for total hip arthroplasty at mid-term follow-up

Purpose

to evaluate the results of Delta ceramic-on-ceramic (CoC) for total-hip-arthroplasty (THA).

Methods

261 THA using Delta-CoC, retrospectively analyzed. A 36 mm head was used in 189 cases and a 32/40 mm in the others. The series have been compared to a group of 89 THA with Forte-CoC.

Results

The Harris-Hip-Score improved from 49.1 ± 14.3 to 92.0 ± 8.9 (P < 0.001). In the Delta group there were one ceramic fracture and 2 dislocations. Two hips underwent revision. There were one revision in the Forte group for instability and one squeaking hip.

Conclusions

The new ceramic bearings provides a safe bearing for THA, with rare complications.

Are the Wear and Osteolysis Outcomes Different between Annealed and Remelted First-Generation Highly Crosslinked Polyethylene after Long-Term Implantation?

First-generation highly crosslinked polyethylene (HXLPE) was developed to reduce polyethylene wear debris and subsequent osteolysis. Two thermal stabilization strategies were developed, annealing and remelting, to remove free radicals remaining in the polymer. Both types of HXLPEs have demonstrated better wear resistance to conventional polyethylene in hip arthroplasty. However, few studies have directly compared the mid- to long-term clinical outcomes of first-generation HXLPEs. We sought to address the following research questions: (1) is there a difference between the revision reasons for HXLPE formulations (annealed and remelted), (2) is there a difference in oxidation between annealed and remelted HXLPEs, (3) is there a difference in the linear penetration rate of annealed and remelted HXLPEs, and (4) does the formulation of first-generation HXLPEs affect the prevalence of osteolysis? A total of 129 first-generation HXLPE acetabular liners were collected in a multicenter retrieval program. These components were implanted for 5 or more years and were fabricated from annealed or remelted HXLPE. Reasons for revision, body mass index, age, sex, and activity levels were collected from medical records. Oxidation was measured at four regions of interest: bearing surface, backside surface, locking mechanism, and rim. Liner penetration was directly measured from retrievals using a micrometer. Osteolysis was reported in the operative notes by the revising surgeon and a thorough review of the operative notes and radiographs. Revision reasons included infection, instability, pain, and loosening. The annealed liners had higher oxidation indices than remelted liners. There was no difference in linear penetration rates between cohorts. There was no difference in osteolysis prevalence between cohorts. We found remelted HXLPE to be more oxidatively stable than annealed HXLPE but did not find a significant difference in the linear penetration rates or the prevalence of osteolysis. Our findings demonstrate sustained long-term wear resistance of both cohorts of HXLPE. We did not find evidence to support a long-term clinical difference between the formulations of HXLPE.

Metagenomic next-generation sequencing of synovial fluid demonstrates high accuracy in prosthetic joint infection diagnostics: mNGS for diagnosing PJI

Aims

The aim of this study was to evaluate the performance of metagenomic next-generation sequencing (mNGS) in detecting pathogens from synovial fluid of prosthetic joint infection (PJI) patients.

Methods

A group of 75 patients who underwent revision knee or hip arthroplasties were enrolled prospectively. Ten patients with primary arthroplasties were included as negative controls. Synovial fluid was collected for mNGS analysis. Optimal thresholds were determined to distinguish pathogens from background microbes. Synovial fluid, tissue, and sonicate fluid were obtained for culture.

Results

A total of 49 PJI and 21 noninfection patients were finally included. Of the 39 culture-positive PJI cases, mNGS results were positive in 37 patients (94.9%), and were consistent with culture results at the genus level in 32 patients (86.5%) and at the species level in 27 patients (73.0%). Metagenomic next-generation sequencing additionally identified 15 pathogens from five culture-positive and all ten culture-negative PJI cases, and even one pathogen from one noninfection patient, while yielding no positive findings in any primary arthroplasty. However, seven pathogens identified by culture were missed by mNGS. The sensitivity of mNGS for diagnosing PJI was 95.9%, which was significantly higher than that of comprehensive culture (79.6%; p = 0.014). The specificity is similar between mNGS and comprehensive culture (95.2% and 95.2%, respectively; p = 1.0).

Conclusion

Metagenomic next-generation sequencing can effectively identify pathogens from synovial fluid of PJI patients, and demonstrates high accuracy in diagnosing PJI.

Cite this article: Bone Joint Res 2020;9(7):440–449.

Microvascular free flap coverage for salvage of the infected total knee arthroplasty

Aims

The integrity of the soft tissue envelope is crucial for successful treatment of infected total knee arthroplasty (TKA). The purpose of this study was to evaluate the rate of limb salvage, infection control, and clinical function following microvascular free flap coverage for salvage of the infected TKA.

Methods

We retrospectively reviewed 23 microvascular free tissue transfers for management of soft tissue defects in infected TKA. There were 16 men and seven women with a mean age of 61.2 years (39 to 81). The median number of procedures performed prior to soft tissue coverage was five (2 to 9) and all patients had failed at least one two-stage reimplantation procedure. Clinical outcomes were measured using the Knee Society Scoring system for pain and function.

Results

In all, one patient was lost to follow-up prior to 12 months. The remaining 22 patients were followed for a mean of 46 months (12 to 92). At latest follow-up, four patients (18%) had undergone amputation for failure of treatment and persistent infection. For the other 18 patients, 11 patients (50%) had maintained a knee prosthesis in place while seven patients had undergone resections for persistent infection but retained their limbs (32%). Reoperations were common following coverage and reimplantation. The median number of additional procedures was two (0 to 6). Clinical function was poor in patients who underwent reimplantation and retained a knee prosthesis following free flap coverage with a mean KSS score for pain and function of 44 (0 to 70) and 30 (0 to 65), respectively. All patients required an assistive device. Extensor mechanism problems and extensor lag requiring bracing were common following limb salvage and prosthesis reimplantation.

Conclusion

Microvascular tissue transfer for management of infected TKA can be successful in limb salvage (82%) but clinical outcomes in salvaged limbs were poor. Cite this article: Bone Joint J 2020;102-B(6 Supple A):176–180.

Higher Rate of Early Revision Following Primary Total Knee Arthroplasty in Patients Under Age 55: A Cautionary Tale

BACKGROUND

There has been an increased number of total knee arthroplasties (TKAs) performed in young and active patients. Although improved materials have decreased the likelihood of early catastrophic wear, concerns remain with the performance and survivorship of TKA implants in this patient population. The purpose this study is to evaluate perioperative complications, patient-reported outcomes, and implant survivorship of TKAs performed in patients under age 55.

METHODS

We retrospectively reviewed 4259 primary TKAs performed over a 4-year period. There were 741 TKAs in patients under age 55. The primary outcome of interest was rate of revision at 30 days, 1, 2, and 5-year time points. Secondary outcomes included postoperative transfusion rate, length of stay, rate of deep vein thrombosis/pulmonary embolism, need for manipulation under anesthesia, readmission and reoperation within 30 days, as well as patient-reported outcomes.

RESULTS

There were 3518 patients over 55 years and 741 patients under 55 years. Overall, 175 patients required revision (4.1%). Patients under 55 years had significantly higher cumulative revision rate at 1 (3.4% vs 1.8%, P < .001), 2 (5.0% vs 2.4%, P < .001), and 5 years (7.3% vs 3.7%, P < .001). Patients under 55 years had a higher rate of early reoperation. Patients over 55 years required more transfusions and suffered a higher rate of early deep vein thrombosis. Patients over 55 years had significantly greater improvements in Patient Reported Outcome Measurement Information System Global 10 Physical scores at 6 months postoperatively compared to patients under 55 years.

CONCLUSIONS

Despite improvements in TKA implants, young and active patients remained at higher risk of early revision compared to older patients. The data should be used to counsel young prospective TKA patients about the early risk of reoperation and non-wear-related complications.

Reasons for Revision, Oxidation, and Damage Mechanisms of Retrieved Vitamin E-Stabilized Highly Crosslinked Polyethylene in Total Knee Arthroplasty

BACKGROUND

In order to improve oxidation resistance, antioxidants such as vitamin-E are added to polyethylene used in the bearing surfaces of orthopedic components. Currently, little is known about the efficacy of this treatment in vivo. This study therefore reports on the reasons for revision, surface damage mechanisms, and oxidation of retrieved vitamin E-stabilized highly crosslinked polyethylene (HXLPE) for total knee arthroplasty.

METHODS

We examined 103 retrieved knee inserts fabricated from vitamin E (VE)-stabilized HXLPE and 67 fabricated from remelted HXLPE as a control. The implantation times were 1.2 ± 1.3 and 1.5 ± 1.3 years for the VE and control cohorts, respectively. The inserts were evaluated for 7 surface damage mechanisms using a semiquantitative scoring method and analyzed for oxidation using Fourier-transform infrared spectroscopy. Reasons for revision were also assessed using operative notes created at time of retrieval.

RESULTS

Both groups were revised primarily for instability, infection, and loosening. Burnishing, pitting, and scratching were the most common damage mechanisms observed, with the VE cohort demonstrating less surface damage than the control. Measured oxidation for the cohort was low, with a median oxidation index of 0.09 ± .05 for the articulating surface, 0.05 ± 0.06 for the backside, 0.08 ± 0.06 for the anterior/posterior surfaces, and 0.08 ± 0.05 for the stabilizing post. As compared to the control cohort, oxidation tended to be less for the VE group at the articulating (P < .001) and backside (P = .003) surfaces, although the median differences were minimal and may not be clinically significant.

CONCLUSION

The results indicate positive fatigue damage resistance and oxidation resistance for the retrieved VE-stabilized total knee arthroplasty inserts.

HTX-011 reduced pain intensity and opioid consumption versus bupivacaine HCl in bunionectomy: phase III results from the randomized EPOCH 1 study

BACKGROUND AND OBJECTIVES

There is a need for local anesthetics that provide consistent analgesia through 72 hours after surgery. This study evaluates the use of HTX-011 (bupivacaine and meloxicam in Biochronomerpolymer technology), an extended-release, dual-acting local anesthetic, in reducing both postoperative pain over 72 hours and postoperative opioid use when compared with bupivacaine hydrochloride (HCl) and saline placebo. Inclusion of low-dose meloxicam in HTX-011 is designed to reduce local inflammation caused by surgery, potentiating the analgesic effect of bupivacaine. Previously, significant synergy has been observed with bupivacaine and meloxicam with both given locally together.

METHODS

EPOCH 1 was a randomized, double-blind, placebo-controlled and active-controlled phase III study in subjects undergoing a primary unilateral, distal, first metatarsal bunionectomy in which subjects received either a single intraoperative dose of HTX-011, immediate-release bupivacaine HCl or saline placebo.

RESULTS

A total of 412 subjects were dosed. The results for the primary and all four key secondary endpoints were statistically significant in favor of HTX-011. HTX-011 demonstrated superior, sustained pain reduction through 72 hours, significantly reduced opioid consumption and resulted in significantly more opioid-free subjects compared with saline placebo and bupivacaine HCl. Safety was similar across groups with fewer opioid-related adverse events observed in the HTX-011 group.

CONCLUSIONS

HTX-011 demonstrated significant reduction in postoperative pain through 72 hours with significant reduction in opioid consumption and a significant increase in the proportion of opioid-free subjects compared with saline placebo and the most widely used local anesthetic, bupivacaine HCl.

TRIAL REGISTRATION NUMBER

NCT03295721.

Does metal porosity affect metal ion release in blood and urine following total hip arthroplasty? A short term study

INTRODUCTION

The surface area of exposed metal in a trabecular-titanium acetabular component is wider compared to traditional-titanium implants. The purpose of this study is to establish if this increase in surface area can lead to a significant increase in systemic metal levels.

METHODS

19 patients with conventional acetabular component and 19 with trabecular-titanium cup were compared. Aluminum, Vanadium and Titanium in blood and urine were assessed before surgery and at intervals for 2 years. The samples were analysed using an inductively coupled plasma mass spectrometry.

RESULTS

Patients with trabecular-titanium did not have significantly higher metal ion levels compared to patients with conventional cups up to 2 years. A trend over time was statistically significant in both blood and urine for aluminum and titanium concentrations.

CONCLUSIONS

The three-dimensionality and the wide surface of the trabecular-titanium acetabular component did not affect metal ion release compared to traditional implants after 2 years.

Does Prior Bariatric Surgery Affect Implant Survivorship and Complications Following Primary Total Hip Arthroplasty/Total Knee Arthroplasty?

BACKGROUND

The purpose of this study is to evaluate the impact of prior bariatric surgery on survivorship, outcome, and complications following primary total hip arthroplasty (THA)/total knee arthroplasty (TKA).

METHODS

Using the Medicare 5% part B data from 1999 to 2012, we analyzed patients who underwent primary THA (n = 47,895) and primary TKA (n = 86,609). Patients with prior bariatric surgery before arthroplasty were compared to patients with other common metabolic conditions. Kaplan-Meier risk of revision THA/TKA for those with and without bariatric surgery and each of the metabolic bone conditions was calculated. The risk for infection was also evaluated. Regression analysis was used to determine the relative risk of revision at various time intervals for those with and without each of the metabolic conditions. Analysis was also adjusted for the metabolic conditions, age, gender, socioeconomic status, and Charlson comorbidity index.

RESULTS

The prevalence of patients with prior bariatric surgery within 24 months of primary THA/TKA was 0.1%. Benchmarked against other common chronic metabolic conditions, bariatric surgery prior to THA was not associated with an increased risk for revision surgery at all measured intervals but positively correlated with increased risk for developing infections. Conversely, patients undergoing primary TKA following bariatric surgery were at increased risk for revision compared to controls but not at increased risk for infection.

CONCLUSION

The impact of bariatric surgery prior to elective THA/TKA remains unclear. These patients remain at increased risk for infections following THA and revisions following TKA.

Should Medicare Remove Total Knee Arthroplasty From Its Inpatient Only List? A Total Knee Arthroplasty Is Not a Partial Knee Arthroplasty

BACKGROUND

The Centers for Medicare and Medicaid Services have solicited comments to consider removing total knee arthroplasty (TKA) from the Inpatient Only list, as it has done for unicompartmental knee arthroplasty (UKA). The purpose of this study is to determine whether Medicare-aged patients undergoing TKA had comparable outcomes to those undergoing UKA.

METHODS

We queried the American College of Surgeons-National Surgical Quality Improvement Program database for all patients aged 65 years or older who underwent elective TKA or UKA from 2014 and 2015. Demographic variables, comorbidities, length of stay (LOS), 30-day complication, and readmission rates were compared between UKA and TKA patients. A multivariate regression analysis was then performed to identify independent risk factors for complications and hospital LOS greater than 1 day.

RESULTS

Of the 50,487 patients in the study, there were 49,136 (97%) TKA patients and 1351 UKA patients (3%). Medicare-aged TKA patients had a longer mean LOS (2.97 vs 1.57 days, P < .001), had a higher complication rate (9% vs 3%, P < .001), and were more likely to be discharged to a rehabilitation facility (31% vs 9%, P < .001) than Medicare-aged UKA patients. When controlling for other variables, TKA patients were more likely to experience a complication (odds ratio, 2.562; P < .001) and require LOS >1 day (odds ratio, 14.679; P < .001) than UKA patients.

CONCLUSION

TKA procedure in the Medicare population is an independent risk factor for increased complications and LOS compared to UKA. Policymakers should use caution extrapolating UKA data to TKA patients and recognize the inherent disparities between the 2 procedures.