Influence of body mass index on revision rates after primary total knee arthroplasty

Body Mass Index and the Risk of Postoperative Complications After Total Knee Arthroplasty

INTRODUCTION

Given the growing prevalence of obesity, it is crucial to understand the effect of obesity on complications after total knee arthroplasty (TKA). This study aims to assess the relationship between body mass index (BMI) and postoperative periprosthetic joint infection (PJI), medical complications, and surgical complications after TKA.

METHODS

The Premier Healthcare Database was used to identify all primary elective TKAs between 2016 and 2021. The primary outcome was risk of PJI within 90 days of surgery. Using logistic regression, restricted cubic splines were generated to assess the relationship between BMI as a continuous variable and PJI risk. Bootstrap simulation was then done to identify a BMI inflection point on the final restricted cubic spline model past which the risk of PJI increased. The relationship between BMI and composite 90-day medical and surgical complications was also assessed.

RESULTS

A direct relationship was observed between increasing BMI and increasing risk of PJI with a BMI changepoint of 31 kg/m2 identified as being associated with increased risk. Above a BMI of 31 kg/m2, there was an average relative risk increase of PJI of 13.6% for every unit BMI. This relative risk per unit BMI increased from 5.8% for BMI 31 to 39 to 11.5% between BMI 40 and 49 kg/m2, and 21.3% for BMIs ≥50 kg/m2. Similarly, a direct relationship was also found between increasing BMI and both medical and surgical complications with BMI changepoints of 34 and 32 kg/m2 identified, respectively.

DISCUSSION

Obese patients with a BMI >31 kg/m2 were at increased risk of PJI. Although the relative risk increase was small per unit BMI above 31 kg/m2, the cumulative increase in risk may be marked for patients with higher BMIs.

CONCLUSION

These data should be used to inform discussions that involve shared decision making between patients and surgeons who weigh the risks and benefits of surgery.

Current Evidence Does Not Support the Use of Tibial Stem Extension in Total Knee Arthroplasty of Obese Patients: A Systematic Review

BACKGROUND

Obesity rates have been increasing globally, leading to a higher incidence of knee osteoarthritis and a surge in primary and revision total knee arthroplasty (TKA). The debate continues on the impact of obesity on TKA success, particularly regarding the use of stemmed tibial components in obese patients. This systematic review aimed to compare the effectiveness of stemmed tibial components versus standard keeled tibial components in obese patients undergoing TKA.

METHODS

A systematic review was conducted using databases including PubMed, Embase, Scopus, and Web of Science from inception to December 2023. The eligibility criteria were Participants: Patients who have obesity undergoing TKA; Intervention: stemmed TKA; Comparator: standard keeled tibial TKA; Outcomes: aseptic loosening, patient-reported outcome measures (PROMs), and overall revision. Data extraction and quality assessment were performed using the Newcastle-Ottawa Scale for cohort studies and the Cochrane risk-of-bias tool for randomized trials.

RESULTS

The search yielded 470 studies, with 10 studies (42,533 knees) meeting the inclusion criteria. These studies included 3 randomized controlled trials and 7 retrospective cohorts. The primary outcomes measured were aseptic loosening and overall revision rates, while secondary outcomes included PROMs. Results indicated mixed findings, with some studies suggesting improved outcomes with stemmed components in cases of aseptic loosening and mechanical failure, while others showed no significant difference. The PROMs did not show a significant difference between groups post-TKA. The certainty of the evidence was graded as "very low" using the Grading of Recommendations, Assessment, Development, and Evaluations framework.

CONCLUSIONS

Current literature does not provide conclusive evidence to support the routine use of stemmed tibial components in TKA for obese patients. The decision to use stem extensions should not solely rely on the patient's obesity status. Further high-quality studies are needed to clarify the role of stemmed components in TKA for this patient population.

LEVEL OF EVIDENCE

III.

Body Mass Index Did Not Affect the Risk of Revision 3-9 Years After Total Knee Replacement Surgery

Background

There are conflicting reports in the literature regarding the risk of revision after primary total knee replacement (TKR) in obese patients. The purpose of this study was to investigate if body mass index (BMI) influences the risk of revision 3-9 years after primary TKR.

Methods

All patients undergoing a primary TKR in our institution from 2014 to 2018 were included in a retrospective study. The effect of BMI on all-cause revision was estimated in a logistic regression analysis. A directed acyclic graph was created to identify variables affecting the primary endpoint (revision). According to the directed acyclic graph, adjustment was only needed for age and smoking. However, we also included variables thought to influence the revision risk based on clinical experience and previous research. The final logistic regression analysis was therefore adjusted for age, sex, smoking status, diabetes mellitus and the American Society of Anesthesiologists classification.

Results

One thousand fifty-nine primary TKR patients with a mean age of 68.1 (standard deviation 9.4) years were included. There were 609 (57.5%) women, and the median follow-up time was 5.6 (range 3.0-9.0) years. There were 41 (3.9%) revisions. BMI did not affect the risk of revision when adjusted for relevant covariates in a multivariate logistic regression analysis (odds ratio 0.99, 95% confidence interval 0.93-1.05, P = .6).

Conclusions

BMI did not influence the risk of revision rate 3-9 years after TKR.

Is Morbid Obesity a Modifiable Risk Factor in Patients Who Have Severe Knee Osteoarthritis and do Not Have a Formal Perioperative Optimization Program?

BACKGROUND

Obesity is considered a modifiable risk factor prior to total knee arthroplasty (TKA); however, little data support this hypothesis. Our purpose was to evaluate patients who have a body mass index (BMI) >40 presenting for TKA to determine the incidence of: (1) patients who achieved successful weight loss through nutritional modification or bariatric surgery and (2) patients who underwent TKA over the study period without the presence of a formal optimization program.

METHODS

This was a retrospective, single-center analysis. Inclusion criteria included: Kellgren and Lawrence grade 3 or 4 knee osteoarthritis, BMI >40 at presentation, and minimum 1-year follow-up (mean 45 months) (N = 624 patients). Demographics, weight loss interventions, pursuit of TKA, maximum BMI change, and Patient-Reported Outcomes Measurement Information System scores were collected. Multivariable logistic and linear regressions evaluated associations of underlying demographic and treatment characteristics with outcomes.

RESULTS

There were 11% of patients who ended up pursuing TKA over the study period. Bariatric surgery was 3.7 times more likely to decrease BMI by minimum 10 compared to nonsurgical intervention (95% confidence interval [CI] [1.7, 8.1]; P = .001). Bariatric surgery resulted in mean BMI change of -3.3 (range, 0 to 22) compared to nonsurgical interventions (-2.6 [range, 0 to 12]) and no intervention (0.4 [range, 0 to 15]; P < .0001). Bariatric surgery patients were 3.1 times more likely to undergo TKA (95% CI [1.3, 7.1]; P = .008), and nonsurgical interventions were 2.4 times more likely to undergo TKA (95% CI [1.3, 4.5]; P = .006) compared to no intervention. Non-White patients across all interventions were less likely to experience loss >5 BMI compared to White patients (95% CI [0.2, 0.9]; P = .018).

CONCLUSIONS

Most patients were unable to reduce BMI more than 5 to 10 over a mean 4-year period without a formal weight optimization program. Utilization of bariatric surgery was most successful compared to nonsurgical interventions, although ultimate pursuit of TKA remained low in all cohorts.

Does Obesity Impact Outcomes of Total Knee Arthroplasty When Treated by High-Volume Surgeons? A Propensity-Matched Analysis From a High-Volume Urban Center

BACKGROUND

The impact of morbid obesity (MO) on outcomes following total knee arthroplasty (TKA) when performed by high-volume (HV) surgeons has not been investigated. This study aimed to assess complication rates and implant survivorship in MO patients operated on by HV surgeons.

METHODS

Patients undergoing primary, elective TKA between June 2011 and May 2022 with a HV surgeon (top 25% surgeons by the number of primary TKAs per year) were retrospectively reviewed. Patients were stratified by body mass index (BMI) into 3 groups: BMI ≥40 (MO), 30≤ BMI <40 (non-morbidly obese), and BMI <30 (nonobese) and 1:1:1 propensity matched based on baseline characteristics. Of the 12,132 patients evaluated, 1,158 were included in final matched analyses (386 per group). The HV surgeons performed a median of 104 TKAs annually (range, 90-173).

RESULTS

The MO patients had significantly longer surgery duration (P = .006) and hospital lengths of stay (P < .001). The 90-day postoperative complications (P = .38) and readmission rates (P = .39) were comparable between groups. Rates of all-cause, septic and aseptic revision were similar between groups at two-year (P = .30, P = .15, and P = .26, respectively) and the latest follow-up (P = .36, P = .52, and P = .38, respectively). Improvement in Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) scores at 6 months (P = .049) and one year (P = .015) was significantly higher in MO patients.

CONCLUSION

Clinical outcomes and complication rates following TKA by HV surgeons are comparable regardless of obesity status. The MO patients may benefit from referral to experienced surgeons to minimize procedural risks and improve outcomes.

LEVEL OF EVIDENCE

III.

Stemmed Versus Nonstemmed Tibia in Primary Total Knee Arthroplasty: A Similar Pattern of Aseptic Tibial Loosening in Obese Patients with Moderate Varus. 5-Year Outcomes of a Randomized Controlled Trial

Obesity is linked to early tibial tray failure after primary total knee arthroplasty (TKA) for osteoarthritis (OA), especially in patients with preoperative varus. This study compared standard and stemmed tibiae TKAs in patients with class I and II obesity with varus deformity. Between April 2013 and June 2020, a prospective study was conducted including patients with end-stage OA, body mass index between 30 and 40 kg/m2, and varus <15 degrees. Patients were randomly assigned to TKAs with either standard or long-stemmed tibiae and evaluated 5 years after surgery using the Knee Society Scoring (KSS). The knee society and modified radiographic evaluation systems were used for radiological evaluation. In total, 264 TKAs were performed in 264 patients (134 in the standard group and 130 in the stemmed group). The mean preoperative hip-knee-ankle angles for the standard and stemmed groups were 8.2 ± 3.2 degrees/varus and 9 ± 2.9 degrees/varus, respectively (p = 0.2), which improved to 5.1 ± 3 degrees/valgus and 5 ± 3.5 degrees/valgus after surgery (p = 0.52). There was no statistically significant difference between the objective KSS (92 vs. 92.9; p = 0.84) and the functioning KSS (73.4 vs. 74.8; p = 0.28). There were no aseptic loosening cases or radiographic differences. In-group analysis revealed significant outcomes differences in both groups if preoperative varus was >10 degrees irrespective of the stem design (p < 0.0001). Complications occurred in two patients; one with a late infection and one had a stem-related tibial fracture. Standard tibia TKAs yielded comparable results in obese patients to long-stemmed tibias. No aseptic tibial loosening was observed regardless of stem type, and worse clinical outcomes were associated with greater varus. CLINICAL TRIAL REGISTRY::  registered at http://www.researchregistry.com (researchregistry5717).LEVEL OF EVIDENCE: II; a prospective randomized trial.

Effect of body mass index on symptomatic venous thromboembolism and prosthesis revision risk after total knee arthroplasty: a long-term study from China

OBJECTIVE

To investigate the effect of body mass index (BMI) on the risk of symptomatic VTE and prosthesis revision after total knee arthroplasty (TKA).

METHODS

Seven thousand one hundred eighty-two patients with primary unilateral TKA treated in our hospital from 2011 to 2020 were divided into four groups according to BMI: BMI < 25 kg/m², BMI 25 kg/m²-29.9 kg/m², BMI 30 kg/m²-34.9 kg/m² and BMI ≥ 35 kg/m². Incidence, Odds ratio and Kaplan-Meier survival analysis were used to evaluate the effects of BMI on symptomatic VTE and prosthesis revision risk after TKA.

RESULTS

The incidence of VTE after TKA was 8.9‰(64/7182). There was no significant difference in the incidence of VTE among different BMI groups(P = 0.452). Deep vein thrombosis mainly occurred in the distal lower extremities, especially in intermuscular veins. Revision rate of prosthesis after TKA was 6.4‰(46/7182). There was no significant difference in revision rate among different BMI groups(P = 0.718). In the univariate analysis of TKA, compared with patients with normal BMI, the risk of postoperative VTE and prosthesis revision in patients with overweight, obesity class I and obesity class II did not increase. Higher prosthesis revision rate and lower prosthesis survival rate were observed in BMI ≥ 35 kg/m² group, although the difference was not statistically significant.

CONCLUSIONS

Through such a retrospective large sample data of long-term follow-up, we believe that the higher BMI was not associated with the increased risk of symptomatic VTE and prosthesis revision after TKA. When TKA was used for appropriate indications, high BMI should not be considered as a contraindication.

Posterior-Stabilized Antibiotic Cement Articulating Spacer With Endoskeleton-Reinforced Cam Reduces Rate of Post-Cam Mechanical Complications in Prosthetic Knee Infection: A Preliminary Study

BACKGROUND

Posterior-stabilized antibiotic cement articulating spacers (PS spacers) reduce spacer mechanical complications in prosthetic knee infections (PKIs); however, joint dislocation after femoral cam fracture has been reported. We hypothesized that the rate of post-cam mechanical complications is lower in PS spacers with an endoskeleton-reinforced cam.

METHOD

A retrospective study of PKIs using PS spacers with or without a Kirschner wire-reinforced cam (K-PS or nK-PS spacers, respectively) was conducted between 2015 and 2019. The rates of post-cam mechanical complications and reoperation, as well as risk factors for post or cam failure, were analyzed.

RESULTS

The cohort included 118 nK-PS and 49 K-PS spacers. All patients were followed up for 2 years. The rate of joint subluxation/dislocation after femoral cam fracture was lower in K-PS (0%) than in nK-PS spacers (17.8%; P = .002). The reoperation rate for spacer mechanical complications was lower in K-PS (0%) than in nK-PS spacers (11.9%; P = .008). The identified risk factors for femoral cam fractures were body mass index ≥25 kg/m², femoral spacer size ≤2, and surgical volume ≤12 resection arthroplasties per year.

CONCLUSION

This preliminary study highlights that K-PS spacers have a lower rate of post-cam mechanical complications than nK-PS spacers. We recommend the use of PS spacers with endoskeleton-reinforced cam when treating PKIs performed by surgeons with lower surgical volumes, especially in patients with higher body mass index and smaller femoral spacer sizes.

Outcomes of Total Joint Arthroplasty in Black, Asian, Minority Ethnic Groups Versus Local Population: A Retrospective Review

BACKGROUND

 Total hip and knee replacement decrease the disability caused by osteoarthritis of the lower extremities. Although it has been established that racial and ethnic minorities underutilize these procedures, little data on postoperative outcomes exists. The impact of race on postoperative Oxford scores and complications following total joint arthroplasty (TJA) will be investigated in this retrospective review.

METHODS

 A retrospective review of 120 elective primary TJA procedures was undertaken between January 2016 and December 2019 in a single institution. To measure variations between the various groups, t-tests were used on their Oxford scores, and chi-squared bivariate regression was used to classify all categorical variables and the association of ethnicity and surgery type with gender.

RESULTS

 There were 62 (51.6%) White patients and 59 (49.1.0%) Black, Asian, Minority Ethnic (BAME) patients in total. The majority of the patients were females (60.9% vs 39.2%, p = 0.032). Low vitamin D levels were seen in a small percentage of patients in the sample (15.8% vs 84.2%, p = 0.460). There is a statistically important connection (p = 0.001) between the surgery type (total knee replacement [TKR]/total hip replacement [THR]) and gender; 41 females had TKR surgery, and 32 had THR surgery.

CONCLUSION

The study found that the relationships between ethnicity (White/BAME) and gender as well as surgery type (TKR/THR) and gender are statistically important. In all cases with low vitamin D and normal vitamin D levels, White patients had higher overall Oxford hip scores than the BAME patients. To comprehend the differences discovered, further research is needed. To try to eliminate the difference, targeted approaches should be created.

History of previous surgery is associated with higher risk of revision after primary total knee arthroplasty: a cohort study from the Geneva Arthroplasty Registry

Background and purpose - Prior to primary total knee arthroplasty (pTKA), 6-34% of patients have undergone surgical procedure(s) of their knee. We investigated whether history of previous surgeries influences the risk of revision of pTKA, the risk according to the type of previous surgery, and how previous surgery influences specific causes of revision and the time of revision.Patients and methods - This is a prospective cohort study from the Geneva Arthroplasty Registry. All pTKA between 2000 and 2016 were included and followed until December 31, 2019. Outcomes were risk of revision, evaluated using Kaplan-Meier survival and Cox and competing risks regression, the specific causes, and time of revision.Results - Of 3,945 pTKA included (mean age 71 years, 68% women), 21% had a history of previous surgery, with 8.3% revisions vs. 4.3%, at 3-20 years' follow-up (mean 8.6). 5- and 10-year cumulative failure by previous surgery (yes vs. no) were 6.6% (95% CI 5.1-8.5) vs. 3.3% (CI 2.7-4.0), and 8.4% (CI 6.6-10.6) vs. 4.5% (CI 3.8-5.4). Baseline differences explained only part of the higher risk (adjusted HR 1.5, CI 1.1-2.1). The risk of failure was higher for all causes of revision considered. Patients in the previous surgery group had a higher risk of an early revision.Interpretation - A history of previous surgery adversely affected the outcome with a 1.5 times higher cumulative risk of all-cause revision over the course of up to 20 years after index surgery. The increased risk was seen for all causes of revision and was highest in the first years.

Ethnic Disparities and Incidence of Postoperative Complications in Obese Patients Undergoing Total Knee Arthroplasty: Analysis of the American College of Surgeons National Surgical Quality Improvement Program Data Set

INTRODUCTION

Total knee arthroplasty (TKA) is common but complex operation. A paucity of literature exists on differences between Hispanics and non-Hispanics with TKA. Our study aims to investigate the association between Hispanic ethnicity and complications in obese patients undergoing TKA.

METHODS

This is a retrospective cohort study using the National Surgical Quality Improvement Program database for patients with body mass index ≥30 kg/m2 who underwent TKA. Exposure in this study was ethnicity (Hispanic versus non-Hispanic), and the primary outcome was postoperative complications. Associations between ethnicity and baseline characteristics and between covariates and the outcome were assessed via bivariate analysis. Multiple logistic regression was done to determine associations between Hispanic ethnicity and complications while controlling for confounders.

RESULTS

Thirty five thousand twenty-seven patients were included in our study, of which 6.3% were Hispanic. Among obese adults, Hispanics had a 1.24 (95% CI 1.11 to 1.39) times greater odds of having a postoperative complication after TKA than non-Hispanics. This increased to 1.36 (95% CI 1.20 to 1.54) after adjusting for confounders. Hispanics were notably more likely to receive transfusion (2.62% vs. 1.59%, P < 0.001) and have prolonged length of stay (13.29% vs. 11.12%, P = 0.002) but were less likely to have wound disruption (0.05% vs. 0.27%, P = 0.042).

CONCLUSION

In a national database, Hispanic ethnicity was associated with greater odds of postoperative complication in obese patients undergoing TKA compared with non-Hispanics. Future studies focusing on a wide range metrics of social determinants of health are needed to further investigate barriers and intervention to eliminate racial/ethnic disparities in surgical patients.

Patients' risk factors for periprosthetic joint infection in primary total hip arthroplasty: a meta-analysis of 40 studies

BACKGROUND

Periprosthetic joint infection (PJI) is a catastrophic complication after total hip arthroplasty (THA). Our meta-analysis aimed to identify the individual-related risk factors that predispose patients to PJI following primary THA.

METHODS

Comprehensive literature retrieval from Pubmed, Web of Science, and the Cochrane Library was performed from inception to Feb 20th, 2021. Patient-related risk factors were compared as per the modifiable factors (BMI, smoke and alcohol abuse), non-modifiable factors (gender, age), and medical history characteristics, such as diabetes mellitus (DM), avascular necrosis (AVN) of femoral head, femoral neck fracture, rheumatoid arthritis (RA), cardiovascular disease (CVD), and osteoarthritis (OA) etc. The meta-analysis was applied by using risk ratios with 95% corresponding intervals. Sensitivity analysis and publication bias were performed to further assess the credibility of the results.

RESULTS

Overall, 40 studies with 3,561,446 hips were enrolled in our study. By implementing cumulative meta-analysis, higher BMI was found associated with markedly increased PJI risk after primary THA [2.40 (2.01-2.85)]. Meanwhile, medical characteristics including DM [1.64 (1.25-2.21)], AVN [1.65 (1.07-2.56)], femoral neck fracture [1.75 (1.39-2.20)], RA [1.37 (1.23-1.54)], CVD [1.34 (1.03-1.74)], chronic pulmonary disease (CPD) [1.22 (1.08-1.37)], neurological disease [1.19 (1.05-1.35)], opioid use [1.53 (1.35-1.73)] and iron-deficiency anemia (IDA) [1.15 (1.13-1.17)] were also significantly correlated with higher rate of PJI. Conversely, dysplasia or dislocation [0.65 (0.45-0.93)], and OA [0.70 (0.62-0.79)] were protective factors. Of Note, female gender was protective for PJI only after longer follow-up. Besides, age, smoking, alcohol abuse, previous joint surgery, renal disease, hypertension, cancer, steroid use and liver disease were not closely related with PJI risk.

CONCLUSION

Our finding suggested that the individual-related risk factors for PJI after primary THA included high BMI, DM, AVN, femoral neck fracture, RA, CVD, CPD, neurological disease, opioid use and IDA, while protective factors were female gender, dysplasia/ dislocation and OA.

Greater risk of all-cause revisions and complications for obese patients in 3 106 381 total knee arthroplasties: a meta-analysis and systematic review

BACKGROUND

Obesity is a major public health issue and has considerable implications on outcomes of total knee arthroplasty (TKA). However, there has been conflicting evidence and conclusions on the effects of obesity on TKA. This meta-analysis compares the outcomes, complications, and peri-operative parameters of TKA in the obese (body mass index [BMI] ≥ 30 kg/m² ) versus non-obese (BMI < 30 kg/m² ) population as well as subgroup analysis of morbidly obese (BMI ≥ 40 kg/m² ) versus non-obese population.

METHODS

A meta-analysis was conducted with a multi-database search according to PRISMA guidelines on 12 September 2019. Data from all published literature meeting inclusion criteria were extracted and analysed.

RESULTS

Ninety-one studies were included, consisting of 917 447 obese and 2 188 834 non-obese TKA. Obese patients had higher risk of all-cause revisions (odds ratio [OR] = 1.15, 95% CI: 1.08-1.24, p < 0.0001), all complications (OR = 1.21, 95% CI: 1.06-1.38, p = 0.004), deep infections (OR = 1.47, 95% CI: 1.27-1.69, p < 0.0001), superficial infections (OR = 1.59, 95% CI: 1.32-1.91, p < 0.0001), wound dehiscence (OR = 1.46, 95% CI: 1.24-1.72, p < 0.0001) and readmissions (OR = 1.21, 95% CI: 1.05-1.40, p = 0.009). Subgroup analysis of morbidly obese patients revealed greater risks of all-cause revisions (OR = 1.25, 95% CI: 1.10-1.43, p = 0.0009), deep infections (OR = 1.98, 95% CI: 1.05-3.75, p = 0.04), superficial infections (OR = 2.44, 95% CI: 2.08-2.88, p < 0.0001) and readmissions (OR = 1.33, 95% CI: 1.20-1.47, p < 0.0001). No analysis was performed on patient reported outcome measures due to heterogeneous reporting methods.

CONCLUSION

Obese and morbidly obese patients have higher risks of revisions and infections post TKA. Surgeons should counsel patients of these risks during the informed consenting process and adopt preventative strategies into clinical practice to reduce risks where possible. In conclusion, obesity is a significant, modifiable risk factor for increased complications following TKA.

Soft-tissue thickness radiographic measurement: a marker to evaluate acute periprosthetic joint infection risk in total hip replacement

The objective of our study was to evaluate the association between acute periprosthetic joint infection (APJI) and radiographic measurement of soft-tissue thickness in elective total hip replacement surgery. A case-control study was conducted to compare the soft-tissue thickness radiographic measurement (SRM) at the hip in patients diagnosed with APJI based on Tsukayama et al. (2003) criteria after total hip replacement with patients that were not infected, at a single institution from 2013 to 2019. To minimize selection bias, each case was matched with two controls using the following methodology: patients of the same sex, with an age variation of ± 5 years, and nearest in surgery date to the cases were selected. All postoperative radiographs were performed in the first 24 h after total hip arthroplasty (THA) surgery as it is protocolized in our institution. Soft-tissue thickness radiographic measurement was defined as the distance from the tip of the greater trochanter to the skin following a perpendicular line to the femoral diaphysis in postoperative anteroposterior hip radiographs. In total, 78 patients were included (26 cases and 52 controls). The SRM median of the cases was 76.19 mm (SD: 26.518) and 53.5 mm (SD: 20.47) in controls. A multivariate logistic regression model showed an independent association between APJI and SRM (odds ratio (OR) = 1.033, 95 % confidence interval (CI) 1.007–1.059, p=0.012). Patients with an SRM greater than 60 mm had a 7-fold increase in the odds of APJI (OR = 7.295, 95 % CI = 2.364–22.511, p<0.001). The results of our study suggest an association between large SRM at the hip and the risk of APJI in patients with primary total hip arthroplasty. SRM may be a helpful and easy tool for evaluating the risk of APJI before elective primary total hip replacement surgery.

Revision Rates and Functional Outcomes Among Severely, Morbidly, and Super-Obese Patients Following Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Obesity has been associated with a greater burden of symptomatic knee osteoarthritis. There is some evidence that patients with a very high body mass index (BMI) may have a higher risk of complications and poor outcomes following total knee replacement compared with non-obese patients or obese patients with a lower BMI. We hypothesized that increasing degrees of obesity would be associated with deteriorating outcomes for patients following total knee replacement.

METHODS

We performed a comprehensive systematic review of 4 medical databases (MEDLINE, AMED, Ovid Healthstar, and Embase) from inception to August 2016. We extracted data to determine revision risk (all-cause, septic, and aseptic) and functional outcome scores (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], Knee Society Score, Oxford Knee Score, EuroQol-5D, and Short Form [SF]-12 Physical Component Summary) in patients with severe obesity (BMI ≥35 kg/m), morbid obesity (BMI ≥40 kg/m), and super-obesity (BMI ≥50 kg/m) in comparison with patients with a normal BMI (<25 kg/m). Meta-analysis was performed using a random effects model.

RESULTS

We screened 3,142 titles and abstracts and 454 full-text articles to identify 40 eligible studies, of which 37 were included in the meta-analysis. Compared with patients with a normal BMI, the risk ratio for an all-cause revision surgical procedure was 1.19 (95% confidence interval [CI], 1.03 to 1.37; p = 0.02) in patients with severe obesity, 1.93 (95% CI, 1.27 to 2.95; p < 0.001) in patients with morbid obesity, and 4.75 (95% CI, 2.12 to 10.66; p < 0.001) in patients with super-obesity. The risk ratio for septic revision was 1.49 (95% CI, 1.28 to 1.72; p < 0.001) in patients with severe obesity, 3.69 (95% CI, 1.90 to 7.17; p < 0.001) in patients with morbid obesity, and 4.58 (95% CI, 1.11 to 18.91; p = 0.04) in patients with super-obesity. There were no significant differences (p > 0.05) in risk of aseptic revision. Based on the Knee Society Scores reported in a single study, patients with super-obesity had outcome scores, expressed as the standardized mean difference, that were 0.52 lower (95% CI, 0.80 lower to 0.24 lower; p < 0.001) than non-obese controls; however, no difference was observed for severe or morbidly obese patients.

CONCLUSIONS

The risk of septic revision is greater in patients with severe obesity, morbid obesity, and super-obesity, with progressively higher BMI categories associated with a higher risk. However, the risk of aseptic revision was similar between all obese and non-obese patients. Functional outcome improvements are also similar, except for super-obese patients, in whom data from a single study suggested slightly lower scores. These findings may serve to better inform evidence-based clinical, research, and policy decision-making.

LEVEL OF EVIDENCE

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

Inconsistent relationship between body weight/body mass index prior to total knee arthroplasty and the 12-year survival

BACKGROUND

The primary hypothesis was that body weight (BW) and body mass index (BMI) significantly impact the long-term survival rate after implantation of a mobile bearing total knee arthroplasty (TKA).

METHODS

A national, multicentric, retrospective study was performed in France. A total of 1604 TKAs were included. The 10-year follow-up was documented, and the influence of BW and BMI on the survival rate was assessed.

RESULTS

There was a significant influence of the BW on the 12-year survival rate for any reason and for infection; but this influence was not proportional to the BW or BMI. There was no significant influence of the BMI on the 12-year survival rate for any reason, for any mechanical reason or for infection.

CONCLUSION

Our results suggest that a higher BMI should not be considered as a risk factor for revision for mechanical purpose if a mobile bearing TKA with confirming design is implanted.

Differences in Perioperative Outcomes and Complications Between African American and White Patients After Total Joint Arthroplasty

BACKGROUND

Racial disparities in healthcare utilization and outcomes have been reported and have wide-reaching implications for individual patient and healthcare system; as providers we bear an ethical burden to address this disparity and provide culturally competent care. This study will examine the influence of race on length of stay, discharge disposition, and complications requiring reoperation following total joint arthroplasty (TJA).

METHODS

Single institution retrospective analysis of a consecutive series of 7208 primary TJA procedures performed between July 2013 and June 2017 was conducted. Chi-squared and t-tests were used to quantify differences between the groups and multiple logistic regression was used to identify race as an independent risk factor.

RESULTS

In total, 6182 (84.3%) white and 1026 (14.0%) African American (AA) patients were included. AA patients were younger (63.62 vs 66.84 years, P < .001), more likely female (68.8% vs 57.0%, P < .001), had a longer length of stay (2.19 vs 2.00 days, P < .001), more likely to experience septic complications (1.3% vs 0.5%, P = .002) and manipulation under anesthesia (3.9% vs 1.8%, P < .001), and less likely to discharge home (67.1% vs 81.1%, P < .001). Multiple logistic regression showed that AA patients were more likely to discharge to a facility (adjusted odds ratio 2.63, 95% confidence interval 2.19-3.16, P < .001) and experience a manipulation under anesthesia (adjusted odds ratio 1.90, 95% confidence interval 1.26-2.85, P = .002).

CONCLUSION

AA patients undergoing TJA were younger with longer length of stay and a higher rate of nonhome discharge; AA race was identified as an independent risk factor. Further study is required to understand the differences identified in this study. Targeted interventions should be developed to attempt to eliminate the disparity.

Weight affects survival of primary total knee arthroplasty: study based on the Danish Knee Arthroplasty Register with 67,810 patients and a median follow-up time of 5 years

Background and purpose - Obesity is a rising issue worldwide and growing evidence supports poor outcome amongst obese patients following total knee arthroplasty (TKA). Using nationwide registries we investigated the association between bodyweight and risk of revision of primary TKA. Patients and methods - All primary TKA performed during 1997-2015, weight at time of primary TKA and subsequent TKA revisions were identified in the Danish Knee Arthroplasty Register (DKR). Data on comorbidities and a priori selected confounding variables were collected from nationwide registries. The association between weight and 1st time TKA revision was calculated as both crude and adjusted hazard ratios (aHR) with 95% confidence intervals (CI) using Cox regression. Results - Of 67,810 identified primary TKAs, 4.8% were revised within a median follow-up time of 5.4 years. No association between weight and risk of any revision in patients aged 18-54 and 55-70 years was found. Increased risk of any revision was seen in patients >70 years, 80-89 kg (aHR =1.5, CI 1.2-1.8), 90-99 kg (aHR =1.7, CI 1.3-2.1) and patients >99 kg (aHR =1.6, CI 1.3-2.1), as well as those weighing 45-60 kg (aHR =1.4, CI 1.1-1.9) compared with same aged patients weighing 70-79 kg. Interpretation - We found a complex association between weight and knee arthroplasty survival. There was an increased risk of any revision in patients older than 70 years of age weighing <60 kg and >80 kg. Patients aged 18-55 years weighing 60-69 kg had a lower risk of revision compared with all other weight groups, whereas weight was not found to affect risk of any revision in patients aged 55-70 years.

Ten-Year Mortality and Revision After Total Knee Arthroplasty in Morbidly Obese Patients

BACKGROUND

Although morbid obesity has been associated with early surgical complications after total knee arthroplasty (TKA), evidence of long-term outcomes is limited. We conducted a population-based study to determine the association between morbid obesity and 10-year survival and revision surgery in patients undergoing primary TKA.

METHODS

A cohort study of 9817 patients aged 18-60 years treated with primary TKA from April 1, 2002 to March 31, 2007 was conducted using Ontario administrative health-care databases of universal health-care coverage. Patients were followed up for 10 years after TKA. Risk ratios (RRs) of mortality and TKA revision surgery in patients with body mass index > 45 kg/m² (morbidly obese patients) compared with body mass index ≤45 kg/m² (nonmorbidly obese) were estimated adjusting for age, sex, socioeconomic status, and comorbidities.

RESULTS

About 10.2% (1001) of the cohort was morbidly obese. Morbidly obese patients were more likely to be female than nonmorbidly obese patients (82.5% vs 63.7%, P < .001) but otherwise similar in characteristics. Morbidly obese patients had higher 10-year risk of death than nonmorbidly obese patients (adjusted RR 1.50, 95% confidence interval 1.22-1.85). About 8.5% (832) of the patients had at least 1 revision procedure in the 10 years after TKA; revision rates did not differ by obesity (adjusted RR 1.09, 95% confidence interval 0.88-1.34).

CONCLUSION

Morbidly obese patients ≤60 years had a 50% higher 10-year risk of death but no difference in the risk of revision surgery. Results of this population-based study inform evidence-based perioperative counseling of morbidly obese patients considering TKA.

Bariatric Surgery Improves Outcomes After Lower Extremity Arthroplasty in the Morbidly Obese: A Propensity Score-Matched Analysis of a New York Statewide Database

BACKGROUND

The purpose of this study was to compare risks for revision and short-term complications after total joint arthroplasty (TJA) in matched cohorts of morbidly obese patients, receiving and not receiving prior bariatric surgery.

METHODS

Patients undergoing elective TJA between 1997 and 2011 were identified in a New York Statewide database, analyzing total knee arthroplasty (TKA) and total hip arthroplasty (THA) separately. Propensity scores were used to match morbidly obese patients receiving and not receiving bariatric surgery prior to TJA. Cox proportional hazard modeling assessed revision risk. Logistic regression evaluated odds for complications.

RESULTS

For TKA, 2636 bariatric surgery patients were matched to 2636 morbidly obese patients. For THA, 792 bariatric surgery patients were matched to 792 morbidly obese patients. Matching balanced all covariates. Bariatric surgery reduced co-morbidities prior to TJA (TKA P < .0001; THA P < .005). Risks for in-hospital complications were lower for THA and TKA patients receiving prior bariatric surgery (odds ratio [OR] 0.25, P < .001; and OR = 0.69, P = .021, respectively). Risks for 90-day complications were lower for TKA (OR 0.61, P = .002). Revision risks were not different for either THA (P = .634) or TKA (P = .431), nor was THA dislocation risk (P = 1.000).

CONCLUSION

After accounting for relevant selection biases, bariatric surgery prior to TJA was associated with reduced co-morbidity burden at the time of TJA and with reduced post-TJA complications. However, bariatric surgery did not reduce the risk for revision surgery for either TKA or THA.

Risk Reduction Compared with Access to Care: Quantifying the Trade-Off of Enforcing a Body Mass Index Eligibility Criterion for Joint Replacement

BACKGROUND

Morbidly obese patients with severe osteoarthritis benefit from successful total joint arthroplasty. However, morbid obesity increases the risk of complications. Because of this, some surgeons enforce a body mass index (BMI) eligibility criterion above which total joint arthroplasty is denied. In this study, we investigate the trade-off between avoiding complications and restricting access to care when enforcing BMI-based eligibility criteria for total joint arthroplasty.

METHODS

In this retrospective cohort study, the Veterans Health Administration (VHA) Corporate Data Warehouse (CDW) and Veterans Affairs Surgical Quality Improvement Program (VASQIP) databases were reviewed for patients undergoing total joint arthroplasty from October 2011 through September 2014. We determined, if various BMI eligibility criteria had been enforced over that period of time, how many short-term complications would have been avoided, how many complication-free surgical procedures would have been denied, and the positive predictive value of BMI eligibility criteria as tests for major complications. To provide a frame of reference, we also determined what would have happened if eligibility for total joint arthroplasty were arbitrarily determined by flipping a coin.

RESULTS

In this study, 27,671 total joint arthroplasties were reviewed. With a BMI criterion of ≥40 kg/m, 1,148 patients would have been denied a surgical procedure free of major complications, and 83 patients would have avoided a major complication. The positive predictive value of a complication using a BMI of ≥40 kg/m as a test for major complications was 6.74% (95% confidence interval [CI], 5.44% to 8.33%). The positive predictive value of a complication using a BMI criterion of 30 kg/m was 5.33% (95% CI, 4.99% to 5.71%). Flipping a coin had a positive predictive value of 5.05%.

CONCLUSIONS

A 30 kg/m criterion for total joint arthroplasty eligibility is marginally better than flipping a coin and should not determine surgical eligibility. With a BMI criterion of ≥40 kg/m, the number of patients denied a complication-free surgical procedure is about 14 times larger than those spared a complication. Although the acceptable balance between avoiding complications and providing access to care can be debated, such a quantitative assessment helps to inform decisions regarding the advisability of enforcing a BMI criterion for total joint arthroplasty.

LEVEL OF EVIDENCE

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

Weight Gain After Primary Total Knee Arthroplasty Is Associated With Accelerated Time to Revision for Aseptic Loosening

BACKGROUND

Obesity is a major health problem worldwide and is associated with complications after total knee arthroplasty (TKA). It remains unknown whether a change in body mass index (BMI) after primary TKA affects the reasons for revision TKA or the time to revision TKA.

METHODS

A total of 160 primary TKAs referred to an academic tertiary center for revision TKA were retrospectively stratified according to change in BMI from the time of their primary TKA to revision TKA. The association between change in BMI and time to revision was also analyzed according to indication for revision of TKA using Pearson's chi-square test.

RESULTS

The mean change in BMI from primary to revision TKA was 0.82 ± 3.5 kg/m². Maintaining a stable weight after primary TKA was protective against late revision TKA for any reason (P = .004). Patients who failed to reduce their BMI were revised for aseptic loosening earlier, at less than 5 years (P = .020), whereas those who reduced their BMI were revised later, at over 10 years (P = .004).

CONCLUSION

Maintaining weight after primary TKA is protective against later revision TKA for any reason but failure to reduce weight after primary TKA is a risk factor for early revision TKA for aseptic loosening and osteolysis. Orthopedic surgeons should recommend against weight gain after primary TKA to reduce the risk of an earlier revision TKA in the event that a revision TKA is indicated.

A Bundle Protocol to Reduce the Incidence of Periprosthetic Joint Infections After Total Joint Arthroplasty: A Single-Center Experience

BACKGROUND

Periprosthetic joint infection (PJI) represents a devastating complication of total hip arthroplasty (THA) or total knee arthroplasty (TKA). Modifiable patient risk factors as well as various intraoperative and postoperative variables have been associated with risk of PJI. In 2011, our institution formulated a "bundle" to optimize patient outcomes after THA and TKA. The purpose of this report is to describe the "bundle" protocol we implemented for primary THA and TKA patients and to analyze its impact on rates of PJI and readmission.

METHODS

Our bundle protocol for primary THA and TKA patients is conceptually organized about 3 chronological periods of patient care: preoperative, intraoperative, and postoperative. The institutional total joint database and electronic medical record were reviewed to identify all primary THAs and TKAs performed in the 2 years before and following implementation of the bundle. Rates of PJI and readmission were then calculated.

RESULTS

Thirteen of 908 (1.43%) TKAs performed before the bundle became infected compared to only 1 of 890 (0.11%) TKAs performed after bundle implementation (P = .0016). Ten of 641 (1.56%) THAs performed before the bundle became infected, which was not statistically different from the 4 of 675 (0.59%) THAs performed after the bundle that became infected (P = .09).

CONCLUSION

The bundle protocol we describe significantly reduced PJIs at our institution, which we attribute to patient selection, optimization of modifiable risk factors, and our perioperative protocol. We believe the bundle concept represents a systematic way to improve patient outcomes and increase value in total joint arthroplasty.

Prevention of Infection in Orthopedic Prosthetic Surgery

Total joint arthroplasty is a generally safe orthopedic procedure; however, infection is a potentially devastating complication. Multiple risk factors have been identified for development of prosthetic joint infections. Identification of patients at risk and preoperative correction of known risk factors, such as smoking, diabetes mellitus, anemia, malnutrition, and decolonization of Staphylococcus carriers, represent well-established actions to decrease the infection risk. Careful operative technique, proper draping and skin preparation, and appropriate selection and dosing of antimicrobials for perioperative prophylaxis are also very important in prevention of infection.

Clinical Factors, Disease Parameters, and Molecular Therapies Affecting Osseointegration of Orthopedic Implants

Total hip and knee arthroplasty are effective interventions for management of end-stage arthritis. Indeed, about 7 million Americans are currently living with artificial hip and knee joints. The majority of these individuals, however, will outlive their implants and require revision surgeries, mostly due to poor implant osseointegration and aseptic loosening. Revisions are potentially avoidable with better management of patient-related risk factors that affect the osseointegration of orthopedic implants. In this review, we summarize the published clinical literature on the role of demographics, biologic factors, comorbidities, medications and aseptic loosening risk. We focus on several systemic and local factors that are particularly relevant to implant osseointegration. Examples include physiological and molecular processes that are linked to hyperglycemia, oxidative stress, metabolic syndrome and dyslipidemia. We discuss how orthopedic implant osseointegration can be affected by a number of molecular therapies that are antiresorptive or bone anabolic (i.e. calcium, vitamin D, bisphosphonates, calcitonin, strontium, hormone replacement therapy, selective estrogen-receptor modulators).