What are the influencing factors on hip and knee arthroplasty survival? Prospective cohort study on 63619 arthroplasties

Statins and long-term risk of revision surgery after total hip arthroplasty in osteoarthritis: a multi-source data linkage study

Background

Statins, widely used lipid lowering drugs, have been associated with pleiotropic beneficial effects. Notably, studies conducted in vitro and in vivo suggest a link between statins and bone metabolism. Observational data in humans also hint at a decreased fracture rate among statin users. Revision of total hip arthroplasty (THA) is a serious and costly medical event. Whether statins might influence THA failure is not clear. Aim of the current study is to assess how the preoperative use of statins may influence the risk of THA revision in patients with hip osteoarthritis (OA).

Methods

We performed a retrospective analysis of patients who underwent THA for OA in the Italian RIPO registry of Emilia-Romagna. Electronic health records were scrutinized to gather information regarding comorbidities and statin prescriptions. We employed propensity score (PS) matching to pair 1:1 statin users (SU) with statin non-users (SNU), considering factors such as age, sex, and the duration of follow-up. Survival of THA was compared between the two groups; secondary analyses were performed to ascertain the role of mortality, sex, indication for statin treatment, and statin potency or lipophilicity.

Results

10,927 patients were classified as SU and PS-matched with SNU. SU showed a reduced risk of THA revision over a 15-year period (adjHR 0.76, 95% CI: 0.67-0.88; p < 0.001). Notably, this observation remained consistent regardless of the indication for statin therapy or the specific characteristics of the statin medications prescribed, and it was more pronounced among male patients (adjHR 0.64, 95% CI: 0.52-0.80, p < 0.001).

Conclusion

Our findings suggest that statin treatment is associated with a decreased risk of long-term THA revision in patients with OA, irrespective of the original indication for statin therapy.

The impact of anterior cruciate ligament deficiency severity on the outcomes of fixed-bearing unicompartmental knee arthroplasty: a retrospective study

OBJECTIVE

Anterior cruciate ligament deficiency (ACLD) has traditionally been regarded as a contraindication for unicompartmental knee arthroplasty (UKA). However, advancements in surgical techniques and improvements in prosthetic manufacturing have challenged this notion. Controversy persists regarding whether the anterior cruciate ligament (ACL) influences the postoperative outcomes of fixed-bearing (FB) UKA. This study aimed to evaluate the impact of varying severities of ACLD on the clinical outcomes of FB-UKA.

METHODS

This retrospective analysis included 81 patients (87 knees) who underwent FB-UKA for anteromedial osteoarthritis (AMOA). Patients were categorised into three groups on the basis of preoperative MRI and intraoperative findings: the intact ACL group (31 knees), the partial ACLD group (39 knees), and the complete ACLD group (17 knees). Patient demographics (age, body mass index [BMI]), preoperative hip-knee-ankle angle (HKA), follow-up duration, and preoperative and last follow-up data, collected more than one year postoperatively, were recorded, including the Hospital for Special Surgery knee score (HSS), Lysholm score, visual analogue scale (VAS) for pain, range of motion (ROM), postoperative X-ray assessment of the position of the femoral component relative to the tibial component, as well as evaluation of radiolucent lines on the postoperative X-rays. Statistical analyses were conducted to determine differences in clinical outcomes, including pre-and postoperative changes, among the three groups. Postoperative complications, such as infection, aseptic loosening, prosthetic dislocation, or periprosthetic fractures requiring revision surgery, were recorded.

RESULTS

There were no significant differences among the three groups in terms of age, BMI, follow-up duration, preoperative HKA, baseline Lysholm score, HSS knee score, VAS score, or ROM (P > 0.05). Postoperatively, all three groups showed significant improvements in the Lysholm score, HSS knee score, VAS score, and ROM (P < 0.001), with no significant differences in the extent of improvement among the groups (P > 0.05). The position of the femoral component relative to the tibial component did not differ significantly among the groups (P > 0.05), and no radiolucent lines were observed in any of the patients. No patients experienced complications such as infection, aseptic loosening, periprosthetic fractures, or prosthetic dislocations that required revision surgery at the latest follow-up.

CONCLUSION

FB-UKA is a viable surgical option for the treatment of AMOA. For patients with AMOA and stable anteroposterior knee alignment, ACLD does not adversely affect short- to midterm outcomes following FB-UKA. Even in cases of partial or complete ACLD, careful patient selection and optimised surgical techniques can yield outcomes comparable to those in patients with intact ACLs.

Does the Addition of a Tibial Stem Extender in Total Knee Arthroplasty Decrease Risk of Aseptic Loosening in Patients with Obesity? An Analysis from the American Joint Replacement Registry

Mechanical loosening is a leading cause of failure of total knee arthroplasties (TKAs) for which obesity may be a risk factor. With rising rates of obesity and increasing incidence of TKA, the identification of factors to mitigate this cause of failure is necessary. The purpose of this study is to determine if the use of a tibial stem extender (TSE) decreases the risk of mechanical loosening in patients with obesity undergoing TKA. The American Joint Replacement Registry and linked Centers for Medicare & Medicaid Services claims database were utilized to identify a patient cohort with a body mass index (BMI) of 30 kg/m2 or greater and age 65 years or older who underwent primary elective TKA between 2012 and 2021. Patients were divided into cohorts based on obesity class and TSE utilization. The estimated association of TSE use, BMI categories, and covariates with the risk of revisions for mechanical loosening in both unadjusted and adjusted settings was determined. Hazard ratios and their 95% confidence intervals for the risk of mechanical loosening were calculated. A total of 258,775 TKA cases were identified. A total of 538 of 257,194 (0.21%) patients who did not receive a TSE and one patient out of 1,581 (0.06%) with a TSE were revised for mechanical loosening. In adjusted analysis, TSE use was not protective against mechanical loosening and BMI > 40 was not a significant risk factor. Use of a TSE was not found to be protective against mechanical loosening in patients with obesity; however, analysis was limited by the small number of outcome events in the cohort. Further analysis with a larger cohort of patients with TSE and a longer follow-up time is necessary to corroborate this finding.

Risk analyses for perioperative morbidities after aseptic knee revision arthroplasty

INTRODUCTION

Total lower limb arthroplasties are standard orthopedic surgeries that are steadily increasing in modern civilization. In proportion, the number of revision arthroplasties and the corresponding financial burden for healthcare systems will increase. The present clinical investigation analyzed morbidities after aseptic revision knee arthroplasty.

METHODS

Data from 122 patients following aseptic revision TKA (total knee arthroplasty) were collected. The study collected information on systemic and surgical complications during hospitalization and follow-up, blood transfusion units, and changes in Hb and CRP levels. Hb and CRP were measured preoperatively and on postoperative days 1, 2, and 4. Statistical analyses were performed using IBM SPSS version 29.

RESULTS

Significant differences were observed in systemic, surgery-related and blood transfusion rates and reasons for knee replacement changes based on age and gender. Of the patients, 38.5% received a full component change, 11.5% received a partial component replacement (either femoral or tibial), 30.3% had an isolated inlay change, and 19.7% underwent debridement only. Femoral and tibial loosening were more frequent in patients over 75 years and those with longer intervals between the initial operation and re-presentation (p = 0.001). Patients with movement deficits and malposition presented earlier for consultation (p = 0.02). Prolonged high CRP levels were significantly correlated with systemic complications, longer hospital stays, and extended operative times.

CONCLUSIONS

Aseptic knee revision arthroplasty is a complex procedure with perioperative morbidities that can significantly impact outcomes. Age and gender are crucial factors in managing complications during hospitalization and follow-up. Elderly patients, particularly those over 75 years, are more prone to aseptic loosening and require tailored preoperative preparation. The study underscores the importance of individualized patient care strategies to mitigate risks and improve outcomes in aseptic knee revision arthroplasty.

TRIAL REGISTRATION

Not applicable.

Does interaction occur between risk factors for revision total knee arthroplasty?

INTRODUCTION

Several risk factors for revision TKA have previously been identified, but interactions between risk factors may occur and affect risk of revision. To our knowledge, such interactions have not been previously studied. As patients often exhibit multiple risk factors for revision, knowledge of these interactions can help improve risk stratification and patient education prior to TKA.

MATERIALS AND METHODS

The State Inpatient Databases (SID), part of the Healthcare Cost and Utilization Project (HCUP), were queried to identify patients who underwent TKA between January 1, 2006 and December 31, 2015. Risk factors for revision TKA were identified, and interactions between indication for TKA and other risk factors were analyzed.

RESULTS

Of 958,944 patients who underwent TKA, 33,550 (3.5%) underwent revision. Age, sex, race, length of stay, Elixhauser readmission score, urban/rural designation, and indication for TKA were significantly associated with revision (p < 0.05). Age was the strongest predictor (p  < 0.0001), with younger patients exhibiting higher revision risk. Risks associated with age were modified by an interaction with indication for TKA (p < 0.0001). There was no significant interaction between sex and indication for TKA (p = 0.535) or race and indication for TKA (p = 0.187).

CONCLUSIONS

Age, sex, race, length of stay, Elixhauser readmission score, urban/rural designation, and indication for TKA are significantly associated with revision TKA. Interaction occurs between age and indication.

Do modifiable patient factors increase the risk of postoperative complications after total joint arthroplasty?

INTRODUCTION

Numerous studies demonstrate that modifiable lifestyle risk factors can influence patient outcomes including survivability, quality of life, and postoperative complications following orthopaedic surgery. The purpose of this study was to determine the impact of modifiable lifestyle risk factors on postoperative medical and surgical complications following a total joint arthroplasty (TJA) in a large national healthcare system.

METHODS

A retrospective chart review of a large national health system database was performed to identify patients who underwent TJA between 2017 and 2021. TJA included total knee arthroplasty, total hip arthroplasty, and total shoulder arthroplasty. Modifiable lifestyle risk factors were defined as tobacco use, narcotic drug abuse, hypertension, and diabetes mellitus. Postoperative medical complications and postoperative surgical complications were collected. Logistic regression and odds ratio point estimate analysis were conducted to assess for associations between postoperative complications and modifiable lifestyle risk factors.

RESULTS

Of the 16,940 patients identified, the mean age was 71 years, mean BMI was 29.7 kg/m2, and 62% were women. We found that 3.5% had used narcotics, 8.7% were past or current smokers, 24% had diabetes, and 61% had hypertension; in addition, 5.4% experienced postoperative medical complications and 6.4% experienced postoperative surgical complications. Patients who used narcotics were 90% more likely to have postoperative complications (p < 0.0001) and 105% more likely to experience prosthetic complications (p < 0.0001). Similarly, patients with tobacco use were 65% more likely to have postoperative complications (p < 0.0001) and 27% more likely to experience prosthetic complications.

CONCLUSIONS

Our results demonstrate critical rates of increased postoperative medical and surgical complications after TJA for patients with narcotic abuse, tobacco use, or diabetes mellitus. Furthermore, adopting preoperative interventions and optimization programs informed by our findings on specific modifiable risk factors could aid orthopaedic surgeons in optimizing patient health.

LEVEL OF EVIDENCE

III; Retrospective study.

Unicompartmental Knee Arthroplasty Versus Opening-Wedge High Tibial Osteotomy for Spontaneous Osteonecrosis of the Knee: A Retrospective Cohort Study

Background

Unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) are treatment options for patients with medial spontaneous osteonecrosis of the knee (SONK).

Purpose

To compare the clinical outcomes after UKA and HTO in patients with SONK.

Study Design

Cohort study; Level of evidence, 3.

Methods

This retrospective study included 42 patients who had undergone Oxford UKA and 40 patients who had undergone opening-wedge HTO between 2014 and 2020. All patients were diagnosed with isolated medial SONK without subchondral collapse of the femoral condyle and tibial plateau. The patients were preoperatively and postoperatively evaluated using the Lysholm knee scoring system, the Western Ontario and McMaster Universities Osteoarthritis Index, and a numeric rating scale assessing patient satisfaction.

Results

Patients in the UKA group were significantly older than those in the HTO group (median age, 71.5 years [IQR, 68.0-76.5 years] vs 65.0 years [IQR, 60.0-70.0 years], respectively; P < .001). The median follow-up time was 3.78 years (IQR, 2.45-4.53 years) for the UKA group and 3.87 years (IQR, 2.90-5.60 years) for the HTO group. Significant improvements in functional scores were observed in both the UKA and HTO groups (P < .001 for all), with no significant between-group differences in scores at the final follow-up (≥2 years after surgery). The satisfaction rate was similar (80.95% for UKA and 75.0% for HTO).

Conclusion

According to the study results, significant improvements in clinical outcomes were seen after opening-wedge HTO with microfracture for a younger group of patients with SONK without subchondral collapse, while Oxford UKA had a comparable effect on an older group of patients. Both UKA and HTO were found to be viable surgical approaches for SONK at short- to midterm follow-up.

Septic Hip Revision Arthroplasty-A Perioperative and Follow-Up Risk Analysis

Background: Septic hip revision arthroplasty is a complex procedure associated with significant perioperative risks. This study aimed to analyze perioperative and follow-up risk factors in patients undergoing septic hip revision arthroplasty. Methods: A retrospective analysis was conducted on 96 patients who underwent septic revision total hip arthroplasty between 2018 and 2021 at a university hospital. Demographic data, surgical details, pathogen analyses, and complication data were collected and analyzed. The first and second hospitalizations were investigated. Data analyses were conducted with SPSS Version 29.0. Results: The mean age of patients was 69.06 ± 11.56 years, with 59.4% being female. On average, 1.3 ± 0.8 pathogens were detected per patient. Staphylococcus species were the most common pathogens. Women experienced significantly more complications during the first revision hospitalization (p = 0.010), including more surgical (p = 0.022) and systemic complications (p = 0.001). Anemia requiring transfusion was more common in women (70.1% vs. 43.5%, p = 0.012). A higher BMI was associated with a higher count of pathogens (p = 0.019). The number of pathogens correlated with increased wound healing disorders (p < 0.001) and the need for further revision surgeries (p < 0.001). Conclusions: This study identifies gender as a significant risk factor for complications in septic hip revision arthroplasty. Female patients may require more intensive perioperative management to mitigate risks. The findings underscore the need for personalized approaches in managing these complex cases to improve outcomes.

What are the age-related factors linked to aseptic revisions in constrained and unconstrained TKA as well as UKA? A register-based study from the German arthroplasty registry (EPRD)

PURPOSE

The implantation rate of total knee arthroplasties (TKA) is continuously growing. Aseptic problems are a major cause of revision. The aim of the following study was to determinate the incidence of aseptic revisions in primary knee arthroplasty as well as aseptic revision rates and influencing factors according to the patients' age and type of procedure.

METHODS

Data collection was performed using the German Arthroplasty Registry. Influencing factors were analyzed according to the patients' age and type of procedure. Risk factors were calculated using multiple Log-rank test with the Holm's method. Incidence and comparison of aseptic revisions according to the patients' age and type of procedure were analyzed using Kaplan-Meier-estimates. Cox regression was applied to calculate the hazard ratio.

RESULTS

Overall, 300,998 knee arthroplasties with 254,144 (84.4%) unconstrained TKA, 9,993 (3.3%) constrained TKA and 36,861 (12.3%) unicondylar knee arthroplasties (UKA) were analyzed. Patients younger than 65 years suffered a significantly higher aseptic revision rate than older patients (p < 0.0001). After one year, a revision rate of 1.1% was recorded for patients 65-74 years, 1.6% for patients under 65 years, and 1.3% for patients beyond 74 years. After seven years, patients younger than 65 years sustained in 5.0%, patients 65-74 years in 2.9% and patients beyond 74 years in 2.4% revision. In unconstrained TKA, an increased Elixhauser-score (HR = 1,75; HR = 1,54; HR = 1,7; p < 0,001) was a risk factor regardless the age. A TKA volume of 101-250 regardless the age (HR = 0,66; HR = 0,69; HR = 0,79) and > 250 under 75 years (< 65: HR = 0,72; 65-74: HR = 0,78; p = 0,001) were protective for aseptic revision. In UKA, male gender (HR = 0,81; HR = 0,72; HR = 0,57; p < 0,001), a UKA volume ≥ 51 for patients under 75 years (< 65: HR = 0,62; 65-74: HR = 0,59; p = 0,003) as well as cemented UKA for patients younger than 75 years (< 65: HR = 0,37; 65-74: HR = 0,37; p < 0,001) were detected as preventive factors.

CONCLUSION

A significant increased rate of aseptic revisions was reported for patients younger than 65 years compared to older patients. An increased Elixhauser score was a risk factor, whereas male and a high volume of performed UKA or TKA could be identified as preventive factors.

LEVEL OF EVIDENCE

III, cohort study.

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

The impact of retaining the femoral stem in revision total hip arthroplasty: a systematic review, meta-analysis, and meta-regression

INTRODUCTION

The management of well-fixed femoral stems in revision total hip arthroplasty (rTHA) remains a subject of debate, with concerns over potential complications arising from stem retention. This study aimed to investigate the re-revision rates due to aseptic loosening of the stem, overall re-revision rates, dislocation rates, and factors influencing these outcomes in rTHA with a retained well-fixed femoral stem.

MATERIALS AND METHODS

A systematic search was conducted across several databases including PubMed, EMBASE, and CENTRAL to identify pertinent publications from their inception through 2023. We specifically focused on studies that reported outcomes of rTHA with retained well-fixed femoral stems. The study designs incorporated in our research encompassed both cohort studies and case series studies. Thirty-five studies involving isolated acetabular revision and retaining the stem were included, representing a total of 3497 patients. Data extraction was tailored to the study questions. Meta-analyses, meta-regression, and subgroup analyses were conducted to evaluate the outcomes and their relationship with various factors. Pooled results, meta-regression, and subgroup analyses were performed using random-effects models. To assess and reduce bias, we employed Egger's test and the trim and fill method.

RESULTS

The meta-analysis included 3497 patients with a mean follow-up of 9.28 years. The 10-year risk of re-revision after retaining femoral stem using highly cross-linked polyethylene was 1.7% (95% CI 1.1%-2.3%; I2: 60%) for stem aseptic loosening and 8.8% (95% CI 6.2%-11.4%; I2: 78%) overall re-revision. Dislocation risk was 5.7% (95% CI 4.1-7.0%; I2: 61%). Ceramic heads showed lower stem failure risk than metal heads in long-term follow-ups (P < 0.001). The posterolateral approach in revision surgery resulted in better long-term outcomes compared to the direct lateral approach (P < 0.001). Follow-up duration, timeline of study, Harris Hip Score, type of stem fixation, femoral head material, BMI, age, stem age, and surgical approach were evaluated as influential factors on these outcomes.

CONCLUSION

The re-revision rate due to aseptic loosening of the retained stem during rTHA was found to be significantly low, supporting the idea of retaining well-fixed stems during rTHA. The overall re-revision and dislocation rates also presented comparable or better outcomes to prior studies. A range of factors, including the use of highly cross-linked polyethylene and ceramic femoral heads, was found to influence these outcomes.

LEVEL OF EVIDENCE

IV.

PROSPERO REGISTRATION NUMBER

CRD42022351157.

Diabetes mellitus is a potential risk factor for aseptic loosening around hip and knee arthroplasty

BACKGROUND

Aseptic loosening is a leading cause of revision following total hip and knee arthroplasty which is caused by chronic inflammation around the prosthesis. Diabetes mellitus causes systemic inflammatory changes which could increase the risk of aseptic loosening. This study investigated the association between diabetes mellitus and aseptic loosening around hip and knee arthroplasty.

METHODS

A case-control study was conducted at a single arthroplasty centre over the seven-year period of January 2015 to December 2021. Cases were defined as any adult patient undergoing revision hip or knee arthroplasty for aseptic loosening. Controls were randomly selected patients undergoing primary total hip or knee arthroplasty during the same period at a 1:4 ratio. Risk factors were compared between the two groups.

RESULTS

A total of 440 patients were included in our study - 88 in the aseptic loosening group and 352 patients in the control group. The odds of having diabetes mellitus in the aseptic loosening group was 2.78 (95%CI 1.31-5.92, P = 0.01). Other risk factors were not significantly different between the two groups.

CONCLUSIONS

The incidence of diabetes mellitus is significantly greater in patients undergoing revision arthroplasty for aseptic loosening. Further research is required to explore whether this association is indeed causative.

Preoperative mental distress is associated with poorer physical improvements after revision total hip arthroplasty

Aims

Despite the increasing prevalence of mental health disorders in revision arthroplasty patients, the impact of preoperative mental distress on functional outcomes after revision total hip arthroplasty (rTHA) remains unclear. Our study aims to investigate the impact of preoperative mental distress on functional outcomes after rTHA.

Methods

Prospectively collected data of 84 rTHAs was extracted from a single institution's joint replacement registry. Preoperative Short Form-36 (SF-36) mental component summary (MCS) was used to dichotomize patients to those who were distressed (MCS <50) and non-distressed (MCS ≥50). Multivariable analysis was used to analyze the impact of preoperative mental distress on various outcomes such as the SF-36 physical component summary (PCS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford Hip Score (OHS), patient satisfaction and expectation fulfilment at 6 months and 2 years postoperatively.

Results

Compared to non-distressed patients, patients with preoperative mental distress had poorer improvements in PCS (+11.4 vs + 16.9, p = 0.007) and lower rates of minimal clinically important difference (MCID) attainment (55.2% vs 73.0%, p = 0.026) at 2 years postoperatively. However, there were no significant differences in improvements for WOMAC and OHS (p > 0.05). Despite experiencing greater absolute improvements in MCS (+12.1 vs -2.1, p < 0.001) and higher MCID attainment rates (65.5% vs 24.3%, p = 0.005) at 2 years, preoperatively distressed patients had lower MCS levels compared to their non-distressed counterparts at all time points (p-value<0.05). There were no significant differences in patient satisfaction (p = 0.509) or expectation fulfilment (p-value = 0.342) at 2 years postoperatively.

Conclusion

Revision THA led to substantial mental health improvements in patients with preoperative mental distress. Despite this, preoperative mental distress was associated with poorer physical improvements after surgery.

Does body mass index influence long-term outcomes after anatomic total shoulder arthroplasty?

BACKGROUND

As of 2018, upwards of 42% of the US adult population was considered obese based on body mass index (BMI) scales. With the annual number of total joint replacements increasing, this study aimed to evaluate the impact BMI has on anatomic total shoulder arthroplasty (aTSA) outcomes.

METHODS

This was a retrospective analysis of 128 shoulders requiring primary aTSA. Patients were stratified into 3 cohorts based on their BMI at surgery: underweight/normal weight (U/NW; BMI ≤25.0), overweight (25.0 < BMI ≤ 30.0), and obese (BMI >30.0). BMI was separately analyzed as a continuous variable. Clinical endpoints were range of motion scores, including forward elevation, external rotation, and internal rotation, and patient-reported outcomes, including visual analog scale (VAS) scores, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) scores, and the Simple Shoulder Test (SST). Survivorship curves were calculated using Kaplan-Meier analysis.

RESULTS

Forty-four, 50, and 34 patient shoulders were in the U/NW, overweight, and obese cohorts, respectively. The mean follow-up time was 11.4 years. The U/NW cohort had more females (73%) compared with the overweight (34%; P = .0030) and obese (35%; P = .0015) groups; no differences were seen in revision rates. BMI was negatively correlated with age at surgery (r = -0.19, P = .014); it was not correlated with any of the 6 postoperative clinical endpoints. All 3 cohorts saw significant improvements in forward elevation, external rotation, internal rotation and VAS, ASES, and SST scores when compared preoperatively to postoperatively (P < .001). There were no significant differences between the 3 cohorts with respect to postoperative range of motion. Postoperative ASES scores were higher for the overweight cohort (82.6 ± 18.6) compared with both the U/NW (63.0 ± 25.1) and obese cohorts (70.5 ± 26.8) (P < .001). The overweight cohort also had higher SST (P = .0012) postoperative scores compared with the U/NW and obese cohorts; VAS scores were comparable between groups (P = .12). The nonobese (BMI <30) group (n = 94) showed 5-, 10-, and 15-year implant survival of 98.9%, 94.9%, and 83.9%, respectively compared to 97.1%, 93.7%, and 87.0% in the obese (BMI ≥30) group (n = 34). The log rank test revealed no significant difference in survival curves (P = .82).

CONCLUSION

To our knowledge, this is the longest follow-up study analyzing clinical endpoints stratified by BMI for aTSA. We saw that patients with a higher BMI required shoulder replacement at a significantly younger age. However, we also report that regardless of BMI, all patients saw significant improvements in patient-reported outcomes and range of motion scores postoperatively.

Comparison of Survival Rate and Outcomes Between Conventional and Navigation-Assisted Primary Total Knee Arthroplasty in Severe Varus Knees: A Minimum 10-Year Follow-Up

BACKGROUND

This study aimed to compare the long-term clinical and radiographic outcomes and survival rates between navigation-assisted (NAV) total knee arthroplasty (TKA) and conventional (CON) TKA in patients with preoperative severe varus deformity.

METHODS

From January 2005 to December 2011, 152 TKAs and 62 TKAs with preoperative hip-knee-ankle (HKA) angles more than 15° were enrolled in the CON-TKA and NAV-TKA group with 135.7 months follow-up. Clinical outcomes (Western Ontario and McMaster University Osteoarthritis Index and Knee Society Scores), radiographic outcomes (HKA, α, β, γ, and δ angles), and survivorship were compared between the groups.

RESULTS

The mean value of radiographic outcomes was not statistically different; however, outliers of the HKA angle were significantly higher in the CON-TKA group (18.4% versus 8.1%, P = .04). However, long-term clinical outcomes were similar between both groups. The cumulative survival rate was 96.1% in the CON-TKA group and 96.8% in the NAV-TKA group, with no difference between the groups (P = .962).

CONCLUSION

NAV-TKA showed fewer outliers in the HKA angle for severe preoperative varus deformity compared with CON-TKA. The long-term clinical outcomes and survival rates were similar between the 2 techniques. A survival rate of more than 96% was observed in both groups.

STUDY DESIGN

Level III, retrospective comparative study.

Beneficial effect of a zirconium-nitride-coated implant in total knee arthroplasty revision for suspected metal hypersensitivity

INTRODUCTION

Revision of total knee arthroplasty (rTKA) for suspicion of metal hypersensitivity (MHS) may require hypoallergenic implants. Results for coated implants have not been reported. The aim of the present study was to assess short-term results and survival of rTKA for MHS using a multilayer implant coating.

HYPOTHESIS

Multilayer implant coating improves functional results in rTKA, with survival comparable to primary coated implants.

MATERIAL AND METHODS

A single-center retrospective observational study included 28 patients (30 knees) undergoing rTKA for MHS using a coated implant between May 2011 and November 2016. Exclusion criteria comprised implant malpositioning and history of infection in the affected knee. Clinical and radiological results were assessed on the International Knee Society (IKS) and SF-36 functional scores and Ewald radiological score. Survival was calculated on Kaplan-Meier estimation.

RESULTS

Mean follow-up was 3.8 years. Mean IKS score increased by 40.2 points (40%) [range, 28.1-52.3] (p<0.05). Mean range of motion increased by 17° [range, 9.5-24.5°] (p<0.05). Mean physical and mental SF-36 components were respectively 44.7 and 46.1. Survivorship was 93%.

DISCUSSION

There was significant functional improvement after rTKA for MHS. There were no short-term complications related to the zirconium nitrate coating. However, studies with longer follow-up will be needed for confirmation.

LEVEL OF EVIDENCE

IV; retrospective study.

Coronal knee alignment measurements differ on long-standing radiographs vs. by navigation

BACKGROUND

The long-standing radiograph (LSR) is the reference tool for assessing knee alignment after total knee arthroplasty (TKA). However, its value is debatable, as many factors can influence measurement accuracy. Computer-assisted surgery (CAS) provides accurate measurements. Few studies have compared LSR and computer-assisted measurements of knee alignment. The objective of this study was to compare hip-knee-ankle (HKA) angle values obtained before and after TKA on LSRs to those obtained during CAS.

HYPOTHESIS

The HKA angle values measured on LSRs before and after surgery are identical to those measured during CAS.

MATERIAL AND METHODS

The HKA angles of 126 knees were measured on bipedal full-weight-bearing LSRs obtained before and 3 months after TKA. The results were compared to the values obtained during CAS.

RESULTS

Before surgery, the standard deviation was 2.672, with limits of agreement of {-5.391; + 5.082}. The intra-class coefficients were good for the overall measurements (0.9), good for detecting>10° varus (0.89), fair for<10° varus and valgus (0.66 and 0.71, respectively), poor for>10° valgus (0.43) and poor for normal alignment (0). Post-operatively, the standard deviation was 3.113, with limits of agreement of {-6.426; +5.776}. The intra-class coefficient was poor for the overall measurements (0.20), negative for normal alignment (-0.05) and<10° valgus (-0.05), and positive for<10° varus (0.017) and for>10° varus and valgus (0.33).

CONCLUSION

Before TKA, the LSR overestimates the deformity compared to CAS. After surgery, the two methods are not comparable. These findings underline the relevance of routinely obtaining LSRs and for using LSR results to estimate costs for healthcare insurance reimbursement purposes.

LEVEL OF EVIDENCE

IV, retrospective observational cohort study.

A Prospective, Longitudinal Study of the Influence of Obesity on Total Knee Arthroplasty Revision Rate: Results from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

The aim of this study was to investigate the relationship of obesity with all-cause revision and revision for infection, loosening, instability, and pain after total knee arthroplasty (TKA) performed in Australia.

METHODS

Data for patients undergoing primary TKA for osteoarthritis from January 1, 2015, to December 31, 2020, were obtained from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). The rates of all-cause revision and revision for infection, loosening, instability, and pain were compared for non-obese patients (body mass index [BMI], 18.50 to 29.99 kg/m 2 ), class-I and II obese patients (BMI, 30.00 to 39.99 kg/m 2 ), and class-III obese patients (BMI, ≥40.00 kg/m 2 ). The results were adjusted for age, sex, tibial fixation, prosthesis stability, patellar component usage, and computer navigation usage.

RESULTS

During the study period, 141,673 patients underwent primary TKA for osteoarthritis in Australia; of these patients, 48.0% were class-I or II obese, and 10.6% were class-III obese. The mean age was 68.2 years, and 54.7% of patients were female. The mean follow-up period was 2.8 years. Of the 2,655 revision procedures identified, the reasons for the procedures included infection in 39.7%, loosening in 14.8%, instability in 12.0%, and pain in 6.1%. Class-I and II obese patients had a higher risk of all-cause revision (hazard ratio [HR], 1.12 [95% confidence interval (CI), 1.03 to 1.22]; p = 0.007) and revision for infection (HR, 1.25 [95% CI, 1.10 to 1.43]; p = 0.001) than non-obese patients. Class-III obese patients had a higher risk of all-cause revision after 1 year (HR, 1.30 [95% CI, 1.14 to 1.52]; p < 0.001), revision for infection after 3 months (HR, 1.72 [95% CI, 1.33 to 2.17]; p < 0.001), and revision for loosening (HR, 1.39 [95% CI, 1.00 to 1.89]; p = 0.047) than non-obese patients. The risks of revision for instability and pain were similar among groups.

CONCLUSIONS

Obese patients with knee osteoarthritis should be counseled with regard to the increased risks associated with TKA, so they can make informed decisions about their health care. Health services and policymakers need to address the issue of obesity at a population level.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Proton Pump Inhibitors and the Risk of Early Aseptic Loosening in Hip and Knee Arthroplasty

Introduction

The use of proton pump inhibitors (PPIs) has been associated with a higher risk of osteoporotic fractures and non-unions rates. However, the relation between the use of PPIs and the development of aseptic loosening in arthroplasty procedures has not been studied. The objective of this study is to analyze the relation between the use of PPIs, and the risk of early aseptic loosening in total knee arthroplasty (TKA) and total hip arthroplasty (THA).

Materials and methods

A nested case-control study was conducted on patients who were subjected THA or TKA in our center between 2010 and 2014. Cases were patients subjected to revision surgery due to early aseptic loosening during the study period. Cases were matched with controls who did not require any type of revision surgery by type of joint replacement (THA/TKA), gender, age (+/- 2 years), and follow-up time (±6 months). Odds Ratios were adjusted to potential confounders.

Results

The crude and adjusted ORs (95% CI) of undergoing revision surgery for aseptic loosening following primary total knee arthroplasty or total hip arthroplasty, were 6.25 (2.04-19.23) and 6.10 (1.71-21.73), respectively, for any use PPIs compared with non-users. Crude and adjusted ORs, were 11.6 (2.93-45.88) and 17.1 (2.41-121.66), respectively, for patients with a Proportion of Days Covered (PDC) for PPIs <.5 (Table 2). In addition, the crude and adjusted ORs of undergoing revision surgery, were 5.05 (1.59-16.02) and 5.01 (1.36-18.44), respectively, for patients with a PDC for PPIs ≥.5.

Discussion

These results suggest that PPIs should be used with caution in patients with TKA and THA, and that the use of these drugs should not be prolonged unless there was a justifiable indication.

Conclusions

The use of PPIs and was associated with a higher risk of early aseptic loosening in patients subjected to THA and TKA.

Prediction of complications and surgery duration in primary TKA with high accuracy using machine learning with arthroplasty-specific data

PURPOSE

The number of primary total knee arthroplasties (TKA) is expected to rise constantly. For patients and healthcare providers, the early identification of risk factors therefore becomes increasingly fundamental in the context of precision medicine. Others have already investigated the detection of risk factors by conducting literature reviews and applying conventional statistical methods. Since the prediction of events has been moderately accurate, a more comprehensive approach is needed. Machine learning (ML) algorithms have had ample success in many disciplines. However, these methods have not yet had a significant impact in orthopaedic research. The selection of a data source as well as the inclusion of relevant parameters is of utmost importance in this context. In this study, a standardized approach for ML in TKA to predict complications during surgery and an irregular surgery duration using data from two German arthroplasty-specific registries was evaluated.

METHODS

The dataset is based on two initiatives of the German Society for Orthopaedics and Orthopaedic Surgery. A problem statement and initial parameters were defined. After screening, cleaning and preparation of these datasets, 864 cases of primary TKA (2016-2019) were gathered. The XGBoost algorithm was chosen and applied with a hyperparameter search, a cross validation and a loss weighting to cope with class imbalance. For final evaluation, several metrics (accuracy, sensitivity, specificity, AUC) were calculated.

RESULTS

An accuracy of 92.0%, sensitivity of 34.8%, specificity of 95.8%, and AUC of 78.0% were achieved for predicting complications in primary TKA and 93.4%, 74.0%, 96.3%, and 91.6% for predicting irregular surgery duration, respectively. While traditional statistics (correlation coefficient) could not find any relevant correlation between any two parameters, the feature importance revealed several non-linear outcomes.

CONCLUSION

In this study, a feasible ML model to predict outcomes of primary TKA with very promising results was built. Complex correlations between parameters were detected, which could not be recognized by conventional statistical analysis. Arthroplasty-specific data were identified as relevant by the ML model and should be included in future clinical applications. Furthermore, an interdisciplinary interpretation as well as evaluation of the results by a data scientist and an orthopaedic surgeon are of paramount importance.

LEVEL OF EVIDENCE

Level IV.

High Reoperation Rate in Mobile-Bearing Total Ankle Arthroplasty in Young Patients

Background and Objectives: Due to inferior survival rates compared to hip and knee arthroplasty, total ankle arthroplasty (TAA) was previously mainly recommended for older and less active patients. However, given the encouraging survival rates and clinical outcomes of modern generations of TAA, some authors have also advocated TAA in young patients. Thus, the aim of this study was to evaluate age related reoperation, revision and survival rates of third-generation mobile-bearing TAAs. Materials andMethods: In this retrospective study, 224 consecutive TAA patients with a minimum follow up (FU) of 2 years were analyzed. Patients were retrospectively assigned to two study groups (Group A: age < 50 years; Group B: age ≥ 50 years). Revision was defined as secondary surgery with prothesis component removal, while reoperation was defined as a non-revisional secondary surgery involving the ankle. Results: After a mean FU of 7.1 ± 3.2 years, the reoperation rate (Group A: 22.2%; Group B: 5.3%; p = 0.003) and revision rate (Group A: 36.1%; Group B: 13.8%; p = 0.003) were higher within Group A. An age of under 50 years at time of surgery was associated with higher reoperation (odds ratio (OR): 6.54 (95% CI: 1.96–21.8); p = 0.002) and revision rates (OR: 3.13 (95% CI: 1.22–8.04); p = 0.018). Overall, lower patient age was associated with higher reoperation (p = 0.009) and revision rates (p = 0.001). Conclusions: The ideal indication for TAA remains controversial, especially regarding patient age. The findings of this study show high reoperation and revision rates in patients aged under 50 years at time of surgery. Therefore, the outcomes of this study suggest that the indication for TAA in young patients should be considered very carefully and that the association between low patient age and high reoperation rate should be disclosed to all eligible patients.

How Does Implant Survivorship Vary with Different Corail Femoral Stem Variants? Results of 51,212 Cases with Up to 30 Years Of Follow-up from the Norwegian Arthroplasty Register

BACKGROUND

The Corail® cementless stem (DePuy Synthes) has been used in Norway since 1987 and is one of the most frequently used stems in THA worldwide. Although the published survival results of the standard Corail stem have been good, little is known about the long-term (more than 20 years) survival of other stem design variants. Further, some changes were made to the extramedullary part of the stem in 2003, and the effect of these changes on survival is unknown.

QUESTIONS/PURPOSES

(1) What is the survival up to 30 years of the standard collarless Corail femoral stem, and were extramedullary changes (slimmer, polished and rectangular neck, shorter taper) associated with differences in survivorship? (2) How does the 10-year survival and the risk of revision of other Corail stem variants, including the standard collared stem, coxa vara collared stem, and high offset collarless stem, compare with those of the standard collarless stem? (3) Which factors are associated with an increased risk of revision of the Corail stem, and are there any differences in those factors among the four stem variants?

METHODS

Data for this study were drawn from the Norwegian Arthroplasty Register. Since 1987, THAs have been registered in the Norwegian Arthroplasty Register with completeness of data greater than 97% for primary THAs and 93% for revisions. To study survivorship with up to 30 years of follow-up (1987 to 2018; median 7.7-year follow-up), and to compare the original stem with stems with extramedullary modifications, we included 28,928 standard collarless Corail stems in 24,893 patients (mean age at time of implantation 62 years; 66% [16,525 of 24,893] were women). To compare the newer stem variants with the standard collarless stem (2008 to 2018), we included 20,871 standard collarless, 10,335 standard collared, 6760 coxa vara collared, and 4801 high offset collarless stems. Survival probabilities were estimated using the Kaplan-Meier method with endpoints of stem revision, revision due to aseptic stem loosening, and periprosthetic fracture. The endpoint of all noninfectious causes of THA revision (including cup revision) was additionally analyzed for the long-term comparison. The proportion of patients who died was limited, and there was no difference in death rate between the groups compared. Therefore, we believe that competing events were not likely to influence survivorship estimates to a large degree. To compare different stem variants and evaluate factors that could be associated with the risk of revision, we calculated hazard ratios using Cox regression analyses with adjustments for gender, age group, surgical approach, diagnosis, and stem size.

RESULTS

The 30-year Kaplan-Meier survival of the standard collarless stem was 88.4% (95% confidence interval 85.4% to 91.4%), 93.3% (95% CI 91.1% to 95.5%), and 94.4% (95% CI 92.0% to 96.8%) using stem revision for any noninfectious cause, aseptic loosening, and periprosthetic fracture of the femur as endpoints, respectively. There was no difference in survival between the original stem and the modified stem. The 10-year Kaplan-Meier survivorship free of stem revision (all causes including infection) was 97.6% (95% CI 97.2% to 98.0%) for the standard collarless stem, 99.0% (95% CI 98.8% to 99.2%) for the standard collared stem, 97.3% (95% CI 96.3% to 98.3%) for the coxa vara collared stem, and 95.0% (95% CI 93.6% to 96.4%) for the high offset collarless stem. Compared with the standard collarless stem, the standard collared stem performed better (HR 0.4 [95% CI 0.3 to 0.6]; p < 0.001) and the high offset collarless stem performed more poorly (HR 1.4 [95% CI 1.1 to 1.7]; p = 0.006) with any stem revision as the endpoint, and similar results were found with revision for aseptic stem loosening and periprosthetic fracture as endpoints. Controlling for the noted confounders, the standard collared stem had a lower revision risk. The high offset collarless stem had an increased stem revision risk for any reason (HR 1.4 [95% CI 1.1 to 1.7]; p = 0.006) and aseptic loosening (HR 1.6 [95% CI 1.1 to 2.3]; p = 0.022). Other factors associated with an increased risk of stem revision for all stem variants were being a man (HR 1.7 [95% CI 1.4 to 2.0]; p < 0.001), age 70 to 79 years and 80 years and older compared with the age group of 50 to 59 years (HR 1.6 [95% CI 1.2 to 2.0]; p < 0.001 and HR 1.9 [95% CI 1.4 to 2.6]; p < 0.001, respectively), the anterior approaches (direct anterior Smith-Petersen and anterolateral Watson-Jones combined) compared with the posterior approach (HR 1.4 [95% CI 1.1 to 1.7]; p = 0.005), as well as a preoperative nonosteoarthritis diagnosis (HR 1.3 [95% CI 1.0 to 1.6]; p = 0.02) and small stem sizes (sizes 8-11) compared with the medium sizes (sizes 12-15) (HR 1.4 [95% CI 1.1 to 1.6]; p = 0.001). The very small sizes (8 and 9) were associated with a 2.0 times higher risk of revision (95%. CI 1.4 to 2.6; p < 0.01) compared with all other sizes combined.

CONCLUSION

When using the uncemented Corail stem, surgeons can expect good results with up to 30 years of follow-up. Our results should be generalizable to the typical surgeon at the average hospital in a comparable setting. From our results, using a collared variant would be preferable to a collarless one. Due to an increased risk of periprosthetic fracture, caution with the use of the uncemented Corail stem in patients older than 70 years, especially in women, is warranted. Poorer stem survival should also be expected with the use of small stem sizes. The risk of periprosthetic fractures for the Corail uncemented stem versus cemented stems in different age categories has not been extensively examined, nor has the use of a collar for different age groups and genders, and both should be subjects for further investigation.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Cementless Ceramic-on-Ceramic Total Hip Replacement in Children and Adolescents

Background: total hip replacement (THR) is a rare surgical option in children and adolescents with disabling hip diseases. The aim of this study is to report results from a retrospective cohort of patients aged 18 years or less who underwent cementless Ceramic-on-Ceramic (CoC) THR at a single institution, investigating clinical and radiographic outcomes, survival rates, and reasons for revision of the implants. Materials and methods: we queried the Registry of Prosthetic Orthopedic Implants (RIPO) to identify all children and adolescents undergoing THR between 2000 and 2019 at a single Institution. Inclusion criteria were patients undergoing cementless CoC THR, aged less than 18 years at surgery, followed for at least 2 years. Sixty-eight patients (74 hips) matched all the inclusion criteria and were enrolled in the study. We assessed the clinical and radiographic outcomes, the rate of complications, the survival rate, and reasons for revision of the implants. Results: The mean follow-up was 6.6 ± 4.4 years (range 2-20). The most frequent reason for THR was post-traumatic or chemotherapy-induced avascular necrosis (38%). The overall survival rate of the cohort was 97.6% (95% CI: 84.9-99.7%) at 5 years of follow-up, 94.4% (95% CI: 79.8-98.6%) at 10 years and 15 years of follow-up. Two THR in two patients (2.7%) required revision. With the numbers available, Cox regression analysis could not detect any significant interaction between preoperative or intraoperative variables and implant survivorship (p-value 0.242 to 0.989)." The average HOOS was 85 ± 14.3 (range 30.6-100). Overall, 23 patients (48%) reported excellent HOOS scores (>90 points), 21 patients (44%) reported acceptable HOOS scores (60-90 points) while 4 patients (8%) reported poor outcomes (<60 points). Twenty-one patients (43%) were regularly involved into moderate- to high-intensity sport activities (UCLA ≥ 6). Conclusions: Cementless CoC THR is a successful procedure in children and teenagers, having demonstrated high implant survivorship and low rates of complications and failure. A meticulous preoperative planning and implant selection is mandatory, to avoid implant malposition, which is the main reason of failure and revision in these cases. Further studies are needed to assess the impact of the THR on the psychosocial wellbeing of teenagers, as well as risks and benefits and cost-effectiveness in comparison to the hip preserving surgical procedures.

Alumina ceramic-on-ceramic hybrid total hip arthroplasty. A median of 15 years follow-up

INTRODUCTION

The optimum choice of bearing surfaces in total hip replacement (THR) in the younger and active patient remains controversial. The aim of this study was to report the 10 year clinical outcomes, and a median of 15 year implant survival and incidence of complications in a series of Alumina ceramic-on-ceramic THRs utilising an uncemented shell and cemented stem.

METHODS

From January 2004 to December 2007, 175 consecutive patients (195 hips) underwent primary THR. The acetabular components was Trident Peripheral Self Locking (Stryker Orthopaedics) with a third-generation ceramic head and liner (Alumina ceramic, Stryker Orthopaedics). The stem utilised was an Exeter V-40 (Stryker Orthopaedics). Data were collated on demographics, surgical factors, clinical outcomes, radiographic outcomes and revision.

RESULTS

23 patients (27 THRs) died during the follow-up period at a median of 7.8 (3.8 to 9.0) years post-operatively due to causes unrelated to the THR. Median age at time of surgery was 55 (interquartile range 48-60) years. Median follow-up for surviving patients was 15.2 years. Survivorship for all-cause revision was 97.2%. Increasing patient age at time of surgery was associated with a higher OHS at 10 years (p = 0.022). 32 mm head diameter had an improved OHS at 3 months (p = 0.014) and 10 years (p = 0.030). Posterior surgical approach had a statistically significant better OHS at 3 months (p = 0.015) and 1 year (p < 0.001), but the effect was not significant at 10 years (p = 0.440).

CONCLUSION

The findings of this study support excellent long-term outcomes and survivorship of Alumina ceramic-on-ceramic bearing in a hybrid THR in a younger population. Surgical factors leading to a more favourable outcome were the use of a 32 mm femoral head and a posterior approach. Increasing age at surgery demonstrated the most sustained improvement in 10 year clinical outcomes.

Effect of Oxidative Stress on Bone Remodeling in Periprosthetic Osteolysis

The success of implant performance and arthroplasty is based on several factors, including oxidative stress-induced osteolysis. Oxidative stress is a key factor of the inflammatory response. Implant biomaterials can release wear particles which may elicit adverse reactions in patients, such as local inflammatory response leading to tissue damage, which eventually results in loosening of the implant. Wear debris undergo phagocytosis by macrophages, inducing a low-grade chronic inflammation and reactive oxygen species (ROS) production. In addition, ROS can also be directly produced by prosthetic biomaterial oxidation. Overall, ROS amplify the inflammatory response and stimulate both RANKL-induced osteoclastogenesis and osteoblast apoptosis, resulting in bone resorption, leading to periprosthetic osteolysis. Therefore, a growing understanding of the mechanism of oxidative stress-induced periprosthetic osteolysis and anti-oxidant strategies of implant design as well as the addition of anti-oxidant agents will help to improve implants’ performances and therapeutic approaches.

Absence of signature inflammatory markers in synovial fluid for total knee arthroplasties revised for arthrofibrosis

INTRODUCTION

Current diagnostic criteria for arthrofibrosis are limited. Since many patients will be aspirated during their clinical course, synovial fluid analysis may supplement current diagnostic criteria for arthrofibrosis. The goal of this study was to determine a unique synovial fluid and inflammatory marker profile for diagnosing arthrofibrosis.

HYPOTHESIS

Patients with arthrofibrosis following total knee arthroplasty will have a unique synovial fluid aspirate profile compared to control patients to aid in diagnosis.

MATERIALS AND METHODS

Between 2013 and 2017, 32 patients (32 total knee arthroplasties [TKAs]) underwent revision TKAs for arthrofibrosis. Fourteen patients had pre-revision aspirations. They were 2:1 matched based on age, sex, body mass index (BMI), and year of revision to 28 patients who underwent aseptic revision TKAs for reasons other than arthrofibrosis (control group). Mean age at revision was 66years, with 64% males.

RESULTS

In TKAs revised for arthrofibrosis, mean total cell count was 828cells/uL. These aspirates contained a mean distribution of 46% macrophages (range: 4-76%), 31% lymphocytes (range: 11-68%), 21% neutrophils (range: 0-75%), 1% other cells (mainly synovial cells; range: 0-11%), and 1% eosinophils (range: 0-7%). There was no significant difference in mean total cell count (p=0.8) or mean distribution of macrophages (p=0.6), lymphocytes (p=0.1), neutrophils (p=0.2), eosinophils (p>0.9), or serum inflammatory markers (p>0.7) when compared to controls. All aspirations were culture negative for infection.

DISCUSSION

The profile of arthrofibrotic synovial fluid aspirates and serum inflammatory marker values were similar to patients revised for non-arthrofibrotic aseptic etiologies. This suggests synovial fluid and serum inflammatory markers in non-infected knees with arthrofibrosis should expect to have characteristics similar to synovial fluid and inflammatory marker profiles in other aseptic diagnoses.

LEVEL OF EVIDENCE

III; retrospective case-control study.

Implementation and results of an enhanced recovery (fast-track) program in total knee replacement patients at a French university hospital

INTRODUCTION

In total knee replacement (TKR) surgeries, "fast-track" or enhanced recovery after surgery (ERAS) programs are being developed, but their impact on care pathway quality and safety has not been fully explored in the French literature. The present study aimed to compare results in TKR between fast-track and conventional pathways, addressing the following questions: (1) Are 90-day rates of complications, readmission and surgical revision higher with fast-track? (2) Is mean length of stay (LoS) shorter with fast-track? (3) Are postoperative pain and clinical results improved by fast-track? And, (4) are patients and care staff satisfied with these new programs?

HYPOTHESIS

Implementing fast-track for TKR in a university hospital center is beneficial for the patient and does not impair the quality and safety of care.

PATIENTS AND METHOD

A case-control study was performed using a retrospective analysis of prospectively collected data. A fast-track program was implemented for TKR by modifying the care pathway. This involved instituting a therapeutic education consultation, optimizing blood sparing, modifying surgical practices, and hastening early mobilization thus actively involving patients in their own management. Between January 2017 and January 2019, 216 patients with a mean age of 69.23±7.80years and mean BMI of 30.15±4.79kg/m² were included in the fast-track group, with 335 matched patients included in the conventional group.

RESULTS

At 90days, there were no significant inter-group differences in rates of infection (fast-track=1.39%, conventional=0.90%; p=0.34), readmission (fast-track=3.24%, conventional=3.58%; p=0.49), or surgical revision (fast-track=2.78%, conventional=2.69%; p=0.298). The visual analog scale (VAS) pain rating was 1.56±1.36 in the fast-track group versus 5±2.41 in the conventional group; p<0.001. LoS was 3.17±1.59days in fast-track versus 7.25±1.85days in the conventional group; p<0.001. Ninety-five percent of patients and 96% of care staff were satisfied with the fast-track program.

DISCUSSION

Fast-track implementation ensured quality and safety of care; it did not increase the rate of complications in primary TKR. Mean length of stay was drastically reduced. Both patients and care staff were very satisfied with these new procedures.

LEVEL OF EVIDENCE

III; case-control study.

Should all hip and knee prosthetic joints be aspirated prior to revision surgery?

AIMS

It is essential to exclude a periprosthetic joint infection (PJI) prior to revision surgery. It is recommended to routinely aspirate the joint before surgery. However, this may not be necessary in a subgroup of patients. The aim of our study was to investigate if specific clinical and implant characteristics could be identified to rule out a PJI prior to revision surgery.

METHODS

We retrospectively evaluated clinical and implant characteristics of patients who underwent a hip or knee revision surgery between October 2015 and October 2018. Patients were diagnosed with a PJI according to the MSIS diagnostic criteria.

RESULTS

A total of 156 patients were analyzed, including 107 implants that were revised because of prosthetic loosening and 49 because of mechanical failure (i.e. instability, malalignment or malpositioning). No PJI was diagnosed in the group with mechanical failure. In the prosthetic loosening group, 20 of 107 were diagnosed with a PJI (19%). Although there was a significantly lower chance of having a PJI with an implant age of > 5 years combined with a CRP < 5 mg/L, an infection was still present in 3 out of 39 cases (8%).

CONCLUSION

Implants with solely mechanical failure without signs of loosening and low inflammatory parameters probably do not require a synovial fluid aspiration. These results need to be confirmed in a larger cohort of patients. In case of prosthetic loosening, all joints need to be aspirated before surgery as no specific characteristic could be identified to rule out an infection.

Anterior Cruciate Ligament Deficiency is Not Always a Contraindication for Medial Unicompartmental Knee Arthroplasty: A Retrospective Study in Nondesigner's Japanese Hospital

BACKGROUND

An intact anterior cruciate ligament (ACL) is thought to be prerequisite for successful unicompartmental knee arthroplasty (UKA), but recent studies reported successful midterm results of UKA in ACL-deficient (ACLD) knees. We hypothesized that ACLD is not always a contraindication for medial UKA when preoperative radiographs showed typical anteromedial knee patterns.

METHODS

From April 2012 to March 2016, 401 Oxford mobile-bearing UKAs in 282 patients were retrospectively identified from our database. Patients whose ACL was severely damaged, but preoperative X-rays showed typical anteromedial osteoarthritis patterns, were categorized into the ACLD group. From intraoperative data, those whose ACL was intact were categorized into the ACL functional (ACLF) group. There were 32 and 369 knees in the ACLD and ACLF groups, respectively, and mean follow-up periods were 66.1 and 63.8 months for the ACLD and ACLF groups, respectively. We compared the postoperative clinical outcome and component survivorship, with an endpoint of component revision, between ACLD groups and ACLF groups.

RESULTS

In both groups, the Oxford knee score, Knee Society score, Tegner activity score, and knee range of motion in extension were improved after surgery. The UKA component survival rate at five years was 100% in the ACLD group and 98.9% in the ACLF group. There were no significant differences between the groups.

CONCLUSION

Mid-term clinical outcomes of Oxford mobile-bearing UKA in ACLD knees were similar to those in ACLF knees. ACL deficiency is not always a contraindication for medial unicompartmental knee arthroplasty in patients with typical anteromedial osteoarthritis radiographs.

Unicompartmental knee arthroplasty has higher revisions than total knee arthroplasty at long term follow-up: a registry study on 6453 prostheses

PURPOSE

The purpose of this study is to analyse long-term unicompartmental knee arthroplasty (UKA) focusing on survivorship, causes of failure and revision strategy.

METHODS

This study is a retrospective analysis of data from a regional arthroplasty registry for cases performed between 2000 and 2017. A total of 6453 UKAs were identified and the following information was analysed: demographic data, diagnosis leading to primary implant, survivorship, complication rate, causes of failure, revision strategies. UKA registry data were compared with total knee arthroplasty (TKA) registry data of 54,012 prostheses, which were implanted in the same time period.

RESULTS

6453 UKAs were included in the study: the vast majority of them (84.4%) were implanted due to primary osteoarthritis followed by deformity (7.1%) and necrosis of the condyle (5.1%). When compared to TKA, UKA showed lower perioperative complication rate (0.3% compared to 0.6%) but higher revision rate (18.2% at 15 years, compared to 6.2% for TKA). No correlation was found between diagnosis leading to primary implant and prosthesis survival. The most frequent cause of failure was total aseptic loosening (37.4%), followed by pain without loosening (19.8%). Of the 620 UKAs requiring revision, 485 were revised with a TKA and 61 of them required a re-revision; on the other hand, of the 35 cases where another UKA was implanted, 16 required a re-revision.

CONCLUSION

UKA is associated with fewer perioperative complications but higher revision rates when compared to TKA. Its survivorship is not affected by the diagnosis leading to primary implant. Revision surgery of a failed UKA should be performed implanting a TKA, which is associated with a lower re-revision rate when compared to another UKA.

LEVEL OF EVIDENCE

Level 3, therapeutic study.

Direct anterior approach or posterior approach in total hip arthroplasty: A direct comparative study protocol

BACKGROUND

Two familiar surgical methods, posterior approach (PA) and direct anterior approach (DAA), have been extensively utilized in the treatment of total hip arthroplasty (THA) with similar long-term rates of success. The sufficient sample size and a good clinical trial are urgently needed. Considering the above factors, we implemented a retrospective research to compare the prognosis of patients with primary THA receiving the techniques of PA or DAA.

METHODS

This is an observational retrospective research that prospectively collected information via several surgeons at a center utilizing the 2 above treatment methods for unilateral primary total hip arthroplasty. A review of primary THA performed with DAA or PA between February 2017 and February 2019 was conducted in our hospital. The inclusion criteria contained the degenerative changes in end-stage of hip owing to the rheumatoid arthritis, inflammatory arthritis, and osteoarthritis, as well as the Crowe I and II dysplasia that did not require the enhancement. The primary endpoint was the Harris hip score. The measures of secondary outcome contained the operation time, length of incision, hospital stay, the complications after operation, as well as patient satisfaction. The Statistical Package for Social Sciences version 20.0 was utilizing for the statistical analysis (IBM Corporation, Armonk, NY).

RESULTS

We assumed that the 2 treatment methods possess similar results.

TRIAL REGISTRATION

This study protocol was registered in Research Registry (researchregistry6008).

A Perspective on Biotribology in Arthroplasty: From In Vitro toward the Accurate In Silico Wear Prediction

Nowadays hip arthroplasty is recognized as one of the most successful orthopedic surgical procedures, even if it involves challenges to overcome, such that lately, younger and more active patients are in need of total arthroplasty. Wear is still one of the main issues affecting joint prostheses endurance, and often causes loosening accompanied by implant failures. Actual in vitro wear tests executed by mechanical simulators have a long duration, are very expensive, and do not take into account all the possible daily activities of the patients; thus, the challenge to obtain a complete in silico tribological and dynamical model of (bio) tribo-systems could give the possibility to overcome the actual testing procedures and could contribute as a tool for a more accurate tribological design of human prostheses. This prospective paper is intended to underline actual research trends toward the challenge of having accurate numerical algorithms to be used both in preclinical testing and in the optimizations of the prostheses design. With this aim we depicted the possible in silico approach in artificial joints’ wear assessment over time, accounting for contact mechanics, numerical stress–strain analysis, musculoskeletal multibody, and synovial lubrication modelling (boundary/mixed, hydrodynamic, and elastohydrodynamic).