Morbid Obesity: Increased Risk of Failure After Aseptic Revision TKA

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, hypothesizing that stemmed components would yield better clinical and radiological outcomes.

METHODS

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. Databases including PubMed, Embase, Scopus, and Web of Science were searched from inception to December 2023. The eligibility criteria were based on the PICO framework; Participants: Patients who have obesity undergoing TKA, Intervention: stemmed TKA, Comparator: standard keeled tibial TKA, Outcome: 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 three randomized clinical trials and seven 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 (GRADE) framework.

CONCLUSION

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.

Osteoarthritis in patients with obesity: The bariatric surgery impacts on its evolution

Obesity is one of the main modifiable risk factors for osteoarthritis (OA). Moreover, obesity is associated with greater pain intensity and functional limitation, but also with a significantly lower responder rate to intra-articular treatments. Consequently, an arthroplasty is indicated earlier and more frequently in patients with obesity. However, pain and functional symptoms improve slightly less after arthroplasty in patients with obesity, who display higher incidence of early and late complications following prosthetic surgery. Bariatric surgery (BS) has increased worldwide and is efficient to induce major and sustainable weight-loss. Importantly, BS significantly reduces pain and functional limitation in patients with symptomatic knee OA. Biomarkers analysis also revealed a decrease in catabolic factors and an increase in anabolic one after BS suggesting a structural protective effect in knee OA. Nevertheless, the impact of BS prior to arthroplasty remains unclear. BS seems to decrease short- and mid-term complications such as infections or thrombosis. However, BS does not appear to modify long-term complications rate, and may even increase it, especially revisions and infections. Although few studies have compared the symptomatic and functional outcomes of joint replacement with or without BS, these are not significantly improved by prior BS. Despite these heterogeneous results, medico-economic studies found that BS prior to arthroplasty was cost-effective. To conclude, BS could significantly reduce the symptoms of OA and potentially slow its progression, but appears more disappointing in preventing long-term complications of arthroplasties and improving their functional results.

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.

Body Mass Index and Revision Total Knee Arthroplasty: Does Cause for Revision Vary by Underweight or Obese Status?

BACKGROUND

Body mass index (BMI) impacts risk for revision total knee arthroplasty (rTKA), but the relationship between BMI and cause for revision remains unclear. We hypothesized that patients in different BMI classes would have disparate risk for causes of rTKA.

METHODS

There were 171,856 patients who underwent rTKA from 2006 to 2020 from a national database. Patients were classified as underweight (BMI < 19), normal-weight, overweight/obese (BMI 25 to 39.9), or morbidly obese (BMI > 40). Multivariable logistic regressions adjusted for age, sex, race/ethnicity, socioeconomic status, payer status, hospital geographic setting, and comorbidities were used to examine the effect of BMI on risk for different rTKA causes.

RESULTS

Compared to normal-weight controls, underweight patients were 62% less likely to undergo revision due to aseptic loosening, 40% less likely due to mechanical complications, 187% more likely due to periprosthetic fracture, 135% more likely due to periprosthetic joint infection (PJI). Overweight/obese patients were 25% more likely to undergo revision due to aseptic loosening, 9% more likely due to mechanical complications, 17% less likely due to periprosthetic fracture, and 24% less likely due to PJI. Morbidly obese patients were 20% more likely to undergo revision due to aseptic loosening, 5% more likely due to mechanical complications, and 6% less likely due to PJI.

CONCLUSION

Mechanical reasons were more likely to be the cause of rTKA in overweight/obese and morbidly obese patients, compared to underweight patients, for whom revision was more likely to be infection or fracture related. Increased awareness of these differences may promote patient-specific management to reduce complications.

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.

An Update on the Management and Optimization of the Patient with Morbid Obesity Undergoing Hip or Knee Arthroplasty

The prevalence of obesity in the United States is at a record high of 42%. In 1999, the Centers for Disease Control and Prevention recognized the obesity epidemic as a national problem, spurring the first generation of interventions for obesity prevention and control. Despite billions of dollars in funding, legislative changes, and public health initiatives, the trajectory of American obesity has not waivered. Obesity is also strongly associated with the development of osteoarthritis. The growing population of young, obese, and sick patients presents a unique dilemma for orthopedic surgeons performing joint replacement, as obesity levels and the demand for joint replacement are only expected to rise further.

A mapping review on preoperative prognostic factors and outcome measures of revision total knee arthroplasty

To map literature on prognostic factors related to outcomes of revision total knee arthroplasty (rTKA), to identify extensively studied factors and to guide future research into what domains need further exploration. We performed a systematic literature search in MEDLINE, Embase, and Web of Science. The search string included multiple synonyms of the following keywords: "revision TKA", "outcome" and "prognostic factor". We searched for studies assessing the association between at least one prognostic factor and at least one outcome measure after rTKA surgery. Data on sample size, study design, prognostic factors, outcomes, and the direction of the association was extracted and included in an evidence map. After screening of 5,660 articles, we included 166 studies reporting prognostic factors for outcomes after rTKA, with a median sample size of 319 patients (30 to 303,867). Overall, 50% of the studies reported prospectively collected data, and 61% of the studies were performed in a single centre. In some studies, multiple associations were reported; 180 different prognostic factors were reported in these studies. The three most frequently studied prognostic factors were reason for revision (213 times), sex (125 times), and BMI (117 times). Studies focusing on functional scores and patient-reported outcome measures as prognostic factor for the outcome after surgery were limited (n = 42). The studies reported 154 different outcomes. The most commonly reported outcomes after rTKA were: re-revision (155 times), readmission (88 times), and reinfection (85 times). Only five studies included costs as outcome. Outcomes and prognostic factors that are routinely registered as part of clinical practice (e.g. BMI, sex, complications) or in (inter)national registries are studied frequently. Studies on prognostic factors, such as functional and sociodemographic status, and outcomes as healthcare costs, cognitive and mental function, and psychosocial impact are scarce, while they have been shown to be important for patients with osteoarthritis.

Tobacco Use Is Associated with More Severe Adverse Outcomes Than Morbid Obesity after Aseptic Revision TKA

The association of morbid obesity with increased revision total knee arthroplasty (rTKA) complications is potentially confounded by concurrent risk factors. This study was performed to evaluate whether morbid obesity was more strongly associated with adverse aseptic rTKA outcomes than diabetes or tobacco use history-when present as a solitary major risk factor. Demographic characteristics, surgical indications, and adverse outcomes (reoperation, revision, infection, and amputation) were compared between 270 index aseptic rTKA performed for patients with morbid obesity (n = 73), diabetes (n = 72), or tobacco use (n = 125) and 239 "healthy" controls without these risk factors at a mean 75.7 (range: 24-111) months. There was no difference in 2-year reoperation rate (17.8 vs. 17.6%, p = 1.0) or component revision rate (8.2 vs. 8.4%) between morbidly obese and healthy patients. However, higher reoperation rates were noted in patients with diabetes (p = 0.02) and tobacco use history (p < 0.01), including higher infection (p < 0.05) and above knee amputation (p < 0.01) rates in patients with tobacco use history. Multivariate analysis retained an independent association between smoking history and amputation risk (odds ratio: 7.4, 95% confidence interval: 1.7-55.2, p < 0.01). Morbid obesity was not associated with an increased risk of reoperation or component revision compared with healthy patients undergoing aseptic revision. Tobacco use was associated with increased reoperation and above knee amputation. Additional study will be beneficial to determine whether risk reduction efforts are effective in mitigating postoperative complication risks.

Projected Prevalence of Obesity in Primary Total Knee Arthroplasty: How Big Will the Problem Get?

BACKGROUND

Obesity is a well-established risk factor for complications following primary total knee arthroplasty (TKA). The purpose of this study is to utilize 3 national databases to develop projections of obesity within the general population and primary TKA patients in the United States through 2029.

METHODS

Data from the National Surgical Quality Improvement Program (NSQIP), the Behavior Risk Factor Surveillance System (BRFSS), and the National Health and Nutrition Examination Survey were queried for years 1999-2019. Current Procedural Terminology code 27447 was used to identify primary TKA patients in NSQIP. Individuals were categorized according to body mass index (kg/m²) by year: normal weight (≤24.9); overweight (25.0-29.9); obese (30.0-39.9); and morbidly obese (≥40). Multinomial logistic regression was used to project categorical body mass index data for years 2020-2029.

RESULTS

A total of 8,372,221 individuals were included (7,986,414 BRFSS, 385,807 NSQIP TKA). From 2011 to 2019, the prevalence of normal weight and overweight individuals declined in the general population (BRFSS) and in primary TKA. Prevalence of obese/morbidly obese individuals increased in the general population from 31% to 36% and in primary TKA from 60% to 64%. Projection models estimate that by 2029, 46% of the general population will be obese/morbidly obese and 69% of primary TKA will be obese/morbidly obese.

CONCLUSION

By 2029, we estimate ≥69% of primary TKA to be obese/morbidly obese. Increased resources dedicated to care pathways and research focused on improving outcomes in obese arthroplasty patients will be necessary as this population continues to grow.

LEVEL OF EVIDENCE

Level III, Retrospective Cohort Study.

Factors Associated With Nonunion and Infection Following Ankle Arthrodesis Using a Large Claims Database: Who Has Elevated Risk?

Background:

Complications such as nonunion and infection following ankle arthrodesis can lead to increased patient morbidity and financial burden from repeat operations. Improved knowledge of risk factors can improve patient selection and inform post–ankle arthrodesis surveillance protocols.

Methods:

This is a large retrospective, database study with structured query of a national insurance claims database (PearlDiver Technologies) for patients treated with ankle arthrodesis from 2015 to 2019 as identified by International Classification of Diseases, Tenth Revision (ICD-10), codes. Patients with any operation 1 year prior to or following ankle arthrodesis were excluded from analysis to prevent attributing complications to another operation. Likelihoods of nonunion and infection within 1 year and 3 years following ankle arthrodesis were analyzed using Kaplan-Meier estimations. Patient characteristics associated with the identified complications following ankle arthrodesis were analyzed using multivariable logistic regression analyses.

Results:

Our query yielded 2463 patients in the 5-year period who underwent ankle arthrodesis. Nonunion occurred in 11% (95% CI 10-12) of patients within 1 year of ankle arthrodesis and 16% (95% CI 14-17) of patients within 3 years. Infection occurred in 3.9% (95% CI 3.1-4.7) of patients within 1 year of ankle arthrodesis and in 6.2% (95% CI 5.1-7.2) of patients within 3 years. Obese patients increased odds of nonunion on multivariable analysis (OR 1.6, 95% CI 1.3-2.0; P < .001). On multivariable analysis, diabetes (OR 1.7, 95% CI 1.2-2.6; P = .010) and each 1-unit increase in Elixhauser Comorbidity Index scores (OR 1.1, 95% CI 1.1-1.2; P < .001) contributed to increased odds of infection after ankle arthrodesis.

Conclusion:

Nonunion and infection following ankle arthrodesis have a 3-year probability of 16% and 6%, respectively. More than one-quarter of patients with nonunion following ankle arthrodesis experience a delay in diagnosis beyond 1 year. The risk of post–ankle arthrodesis nonunion is highest in patients with obesity; the risk of post–ankle arthrodesis infection is highest in patients with diabetes or an elevated Elixhauser Comorbidity Index score.

Level of Evidence:

Level III, prognostic study.

Lymphedema Is a Significant Risk Factor for Failure After Primary Total Hip Arthroplasty

BACKGROUND

Lymphedema is a chronic disease characterized by fluid buildup and swelling that can lead to skin and soft-tissue fibrosis and recurring soft-tissue infections. Literature with regard to the increased risk of complications following a surgical procedure in patients with lymphedema is emerging, but the impact of lymphedema in the setting of primary total hip arthroplasty (THA) remains unknown. The purpose of this study was to review outcomes following primary THA performed in patients with lymphedema compared with a matched cohort without lymphedema.

METHODS

Using our institutional total joint registry and medical records, we identified 83 patients (57 were female and 26 were male) who underwent THA with ipsilateral lymphedema. For comparison, these patients were matched 1:6 (based on sex, age, date of the surgical procedure, and body mass index [BMI]) to a group of 498 patients without lymphedema who underwent primary THA for osteoarthritis. Subsequently, postoperative complications and implant survivorship were evaluated for each group. The mean follow-up for each group was 6 years. Survivorship was compared between cohorts using Kaplan-Meier methodology and included both survivorship free of infection and survivorship free of reoperation or revision. Univariate Cox regression analysis was utilized to assess the association between patient factors for the time to event outcomes noted above.

RESULTS

In patients with a history of lymphedema, there was an increased risk of complications (hazard ratio [HR], 1.97; p < 0.01), including reoperation for any cause (HR, 3.16; p < 0.01) and postoperative infection (HR, 4.48; p < 0.01). The 5-year infection-free survival rate was 90.3% for patients with lymphedema compared with 97.7% for patients without lymphedema (p < 0.01).

CONCLUSIONS

Patients with lymphedema are at increased risk for complications, including reoperation and infection, following primary THA. These data emphasize the importance of appropriate preoperative counseling in this population and should encourage efforts to identify methods to improve outcomes, including further investigation of the effects of preoperative optimization of lymphedema prior to THA and methods for improved perioperative management.

LEVEL OF EVIDENCE

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

Primary and Revision Total Knee Arthroplasty in Patients With Pulmonary Hypertension: High Perioperative Mortality and Complications

BACKGROUND

Although perioperative medical management during total knee arthroplasty (TKA) has improved, there is limited literature characterizing outcomes of patients with pulmonary hypertension (HTN). This study examined mortality, medical complications, implant survivorship, and clinical outcomes in this medically complex cohort.

METHODS

We identified 887 patients with pulmonary HTN who underwent 881 primary TKAs and 228 revision TKAs from 2000 to 2016 at a tertiary care center. Patients were followed up at regular intervals until death, revision surgery, or last clinical follow-up. Perioperative medical complications were individually reviewed. The risk of death was examined by calculating standardized mortality ratios and Cox proportional hazards regression models. Cumulative incidence analysis was used for reporting mortality, revision, and reoperation with death as a competing risk.

RESULTS

The 90-day mortality was 0.7% and 4.8% for primary and revision TKAs, respectively. The risk of death was 2-fold higher compared to primary (hazard ratio 2.54, 95% confidence interval [CI] 2.12-3.05) and revision (hazard ratio 2.16, 95% CI 1.78-2.62) TKA patients without pulmonary HTN. Rate of medical complications within 90 days from surgery was 6.5% and 14% in primary and revision TKAs. The 10-year cumulative incidence of any revision was 5% and 16% in primaries and revisions, respectively.

CONCLUSION

Patients with pulmonary HTN undergoing primary and revision TKAs had excess risk of death and experience a high rate of medical complications within 90 days of surgery. Counseling of risks, medical optimization, and referral to tertiary centers should be considered.

LEVEL OF EVIDENCE

Level IV.

Lymphedema: A Significant Risk Factor for Infection and Implant Failure After Total Knee Arthroplasty

BACKGROUND

Lymphedema is characterized by fluid buildup and swelling, leading to skin fibrosis and recurring soft-tissue infections. There is a paucity of data examining the impact of lymphedema in total knee arthroplasty (TKA). The purpose of this study was to review the outcomes of TKA in patients with lymphedema compared with a matched cohort with primary osteoarthritis.

METHODS

One hundred forty-four knees underwent primary TKA with a preceding diagnosis of ipsilateral lymphedema. The mean follow-up was 7 years. A blinded 1:2 match of knees with lymphedema to a group of knees without lymphedema undergoing primary TKA was performed. Matching criteria included sex, age, date of surgery, and body mass index. The mean follow-up for the comparison cohort was 8 years.

RESULTS

Lymphedema increased revision hazard ratio [HR] 7.60; P < 0.001), reoperation (HR, 2.87; P < 0.001), and infection (HR, 6.19; P < 0.001) in addition to periprosthetic fracture (P = 0.04) and tibial component loosening (P = 0.01). The mean time to infection trended toward later time points in knees with lymphedema (19 versus 2 months, P = 0.25).

DISCUSSION

Lymphedema increased the risk of revision, reoperation, and infection. These data highlight the need for appropriate patient counseling and the need for further investigation into the effects of preoperative and postoperative optimization of lymphedema management in the TKA setting.

LEVEL OF EVIDENCE

Therapeutic Level III.

Varus-valgus constraint in 416 revision total knee arthroplasties with cemented stems provides a reliable reconstruction with a low subsequent revision rate at early to mid-term review

AIMS

Varus-valgus constrained (VVC) implants are often used during revision total knee arthroplasty (TKA) to gain coronal plane stability. However, the increased mechanical torque applied to the bone-cement interface theoretically increases the risk of aseptic loosening. We assessed mid-term survivorship, complications, and clinical outcomes of a fixed-bearing VVC device in revision TKAs.

METHODS

A total of 416 consecutive revision TKAs (398 patients) were performed at our institution using a single fixed-bearing VVC TKA from 2007 to 2015. Mean age was 64 years (33 to 88) with 50% male (199). Index revision TKA diagnoses were: instability (n = 122, 29%), aseptic loosening (n = 105, 25%), and prosthetic joint infection (PJI) (n = 97, 23%). All devices were cemented on the epiphyseal surfaces. Femoral stems were used in 97% (n = 402) of cases, tibial stems in 95% (n = 394) of cases; all were cemented. In total, 93% (n = 389) of cases required a stemmed femoral and tibial component. Femoral cones were used in 29%, and tibial cones in 40%. Survivorship was assessed via competing risk analysis; clinical outcomes were determined using Knee Society Scores (KSSs) and range of movement (ROM). Mean follow-up was four years (2 to 10).

RESULTS

The five-year cumulative incidence of subsequent revision for aseptic loosening and instability were 2% (95% confidence interval (CI) 0.2 to 3, number at risk = 154) and 4% (95% CI 2 to 6, number at risk = 153), respectively. The five-year cumulative incidence of any subsequent revision was 14% (95% CI 10 to 18, number at risk = 150). Reasons for subsequent revision included PJI (n = 23, of whom 12 had previous PJI), instability (n = 13), and aseptic loosening (n = 11). The use of this implant without stems was found to be a significant risk factor for subsequent revision (hazard ratio (HR) 7.58 (95% CI 3.98 to 16.03); p = 0.007). KSS improved from 46 preoperatively to 81 at latest follow-up (p < 0.001). ROM improved from 96° prerevision to 108° at latest follow-up (p = 0.016).

CONCLUSION

The cumulative incidence of subsequent revision for aseptic loosening and instability was very low at five years with this fixed-bearing VVC implant in revision TKAs. Routine use of cemented and stemmed components with targeted use of metaphyseal cones likely contributed to this low rate of aseptic loosening. Cite this article: Bone Joint J 2020;102-B(4):458-462.

Morbid Obesity Is Associated With an Increased Risk of Wound Complications and Infection After Lower Extremity Soft-tissue Sarcoma Resection

BACKGROUND

Obesity is associated with wound complications after lower extremity surgery. Excision of soft-tissue sarcomas is urgent, and unlike the elective surgery, obesity cannot be modified preoperatively. The purpose of this study was to evaluate the effect of obesity on treatment outcome.

METHODS

Six hundred fifty-three patients (343 men; mean age, 56 ± 18 years) with a lower extremity soft-tissue sarcoma were reviewed. The mean body mass index (BMI) was 27.1 ± 5.7 kg/m, with 189 obese patients (29%) having a BMI of ≥30 kg/m and 27 morbidly obese patients (4%) having a BMI of ≥40 kg/m. Complications and functional and oncologic outcomes were compared between groups.

RESULTS

Two hundred eighty-five patients (40%) sustained a postoperative complication, most commonly a dehiscence (n = 175; 24%) and infection (n = 147; 21%). On multivariate analysis, morbid obesity was associated with wound complications (P = 0.002) and infection (P = 0.01). Morbid obesity was not associated with local tumor recurrence (P = 0.56). No difference was found in the mean Toronto Extremity Salvage Score (P = 0.11) or Musculoskeletal Tumor Society (P = 0.41) scores between the groups.

DISCUSSION

Morbid obesity was associated with postoperative wound complications and infection. However, after surgery, obese patients can expect no difference in oncologic outcome, with an excellent functional result.

The Effect of Body Mass Index on 30-day Complications After Revision Total Hip and Knee Arthroplasty

BACKGROUND

We aimed to explore the effect of body mass index (BMI) on 30-day complications after aseptic revision total knee arthroplasty (rTKA) and aseptic revision total hip arthroplasty (rTHA), considering BMI as both a categorical and continuous variable.

METHODS

A total of 18,866 patients (9093 rTHA and 9773 rTKA) patients were included for analysis using the American College of Surgeons National Surgical Quality Improvement Project database. Thirty-day rates of readmissions, reoperations, and major and minor complications were compared between different weight categories (overweight: BMI >25 and ≤30 kg/m²; obese: BMI >30 and ≤40 kg/m²; morbidly obese: BMI >40 kg/m²) and the normal weight category (BMI >18.5 and ≤25 kg/m²) using multivariate regression models. Spline regression models were created to study BMI as a continuous variable.

RESULTS

Both readmission rates and reoperation rates increased for rTKA as BMI increased (P < .005). There was a linear relationship between BMI and readmission rates for rTKA. Morbid obesity was associated with an increased reoperation rate for rTHA on univariate analysis (P = .022); however, multivariate analysis showed no statistically significant increase in readmission or reoperation rates as BMI increased for rTHA.

CONCLUSIONS

The relationship between BMI and complications after revision total joint arthroplasty is a J-shaped curve with the lowest rates of complications occurring around a BMI of 30 kg/m². The relationship between BMI and perioperative complications is stronger for revision TKA as opposed to revision THA.

Morbid Obesity in Revision Total Knee Arthroplasty: A Significant Risk Factor for Re-Operation

BACKGROUND

The purpose of this study is to compare surgical and clinical outcomes between matched groups of morbidly obese (body mass index [BMI] >40 kg/m²) and non-morbidly obese (BMI <40 kg/m²) patients undergoing first-time revision total knee arthroplasty with a minimum 5-year follow-up.

METHODS

Two groups of 87 patients (BMI >40 or <40 kg/m²) were matched 1:1 based on age at the time of revision, gender, and diagnosis for revision (aseptic or septic causes).

RESULTS

The morbidly obese group had a significantly greater incidence of re-operation (34.5% [30/87] vs 16.1% [14/87], P = .005) and re-revision (27.6% [24/87] vs 12.6% [11/87], P = .014) with a significantly lower 10-year survivorship for re-operation (P = .05) and subsequent revision (P = .014). In particular, the aseptic sub-group had a greater incidence of re-operation (29.9% [20/67] vs 13.4% [9/67], P = .021) and re-revision (26.9% [18/67] vs 11.9% [8/67], P = .029). The non-morbidly obese group demonstrated higher final Western Ontario and McMaster Universities Index scores (63.1 ± 19.5 vs 55.5 ± 22.5, P = .030) and a greater change between pre-operative and final KSS (45.6 ± 44.3 vs 39.7 ± 48.4, P = .040) and SF-12 Mental component (3.6 ± 10.8 vs -1.4 ± 10.3, P = .013).

CONCLUSION

Morbidly obese patients undergoing revision total knee arthroplasty have a greater risk of re-operation and re-revision while experiencing lower clinical outcome scores compared to non-morbidly obese patients. These patients should be informed of the higher potential for re-operation and the possibility of poor results.

Early complications of revision total knee arthroplasty in morbidly obese patients

INTRODUCTION

Morbid obesity is a known risk factor for complications and failure following primary total knee arthroplasty. Complications following revision total knee arthroplasty (rTKA) in the morbidly obese (BMI > 40) have not been well described. A retrospective cohort study was designed to investigate the early complications of rTKA in morbidly obese patients.

METHODS

Revision TKA procedures were performed between January 2009 and December 2012 at a single institution. Comparisons were made between patients with a normal BMI (18.5-25) and patients with morbid obesity (BMI > 40).

RESULTS

Thirty-three of 141 morbidly obese patients (23.4%) had a complication compared to 10 of 96 patients with a BMI 18.5-25 (10.4%) (p = 0.011). Morbidly obese patients were younger (69.3 vs. 61.4 years, p < 0.0001), and their most frequent complication in comparison with patients with normal BMI was wound healing problems (p = 0.01).

CONCLUSION

Morbidly obese patients are at a significantly increased rate of early complications following rTKA compared to a normal weight cohort, especially with regard to wound complications. The morbidly obese group was significantly younger at the time of rTKA. In addition, this study highlights the importance of risk stratification for morbidly obese patients undergoing rTKA.

Morbid Obesity Increases the Risk of Postoperative Wound Complications, Infection, and Repeat Surgical Procedures Following Upper Extremity Limb Salvage Surgery for Soft Tissue Sarcoma

BACKGROUND

Obesity is a known risk factor for wound complications; however, unlike elective upper extremity procedures, where obesity can be modified preoperatively, excision of soft tissue sarcomas (STSs) is not elective, and as such, obesity cannot be modified. There is a paucity of data concerning the impact of obesity on wound healing in upper extremity sarcoma surgery.

METHODS

A total of 261 (159 males and 102 females) patients with a STS of the upper extremity from 2006-2014 were reviewed. The mean age and body mass index (BMI) were 56 (18-97) years and 26.6 (15.4-40.8) kg/m², respectively. Sixty-nine patients (26%) were classified as obese (BMI ⩾30 kg/m²): class I (obese, BMI = 30-34.9 kg/m²; n = 48, 18%), class II (severely obese, BMI = 35.0-39.9 kg/m²; n = 16, 6%), and class III (morbidly obese, BMI ≥ 40 kg/m²; n = 5, 2%). Functional outcomes were also compared between obese and nonobese patients using the Musculoskeletal Tumor Society (MSTS) 1993 rating system and Toronto Extremity Salvage Scores (TESS).

RESULTS

Forty-nine patients (19%) sustained a wound dehiscence, delayed healing, or infection. Class III obesity increased the risk of wound complications (hazard ratio [HR] = 8.19, 95% confidence interval [CI] = 1.96-22.96, P < .001) and infection (HR = 10.09, 95% CI = 1.60-34.83, P = .01). There was no difference in the mean TESS (93 vs 90, P = .13) or MSTS93 (95 vs 93, P = .39) between obese and nonobese patients.

CONCLUSIONS

The results of this study indicate morbid obesity significantly increased the risk of a postoperative wound complication and infection. However, following upper extremity limb salvage surgery, obese patients should expect to have excellent functional outcome.

Readmission Following Revision Total Knee Arthroplasty: An Institutional Cohort

Purpose: Total knee arthroplasty (TKA) is the most common joint replacement surgery performed in the United States. Given the aging and increasingly comorbid patient populations undergoing these procedures, complication rates and the need for subsequent hospital readmission are only expected to rise. It is, therefore, crucial to investigate the risk factors leading to readmission in order to improve patient outcomes. The purpose of this study is to identify significant risk factors for readmission following revision TKA procedures.

Methods: Patients undergoing revision TKA were identified at our institution from 2006-2017. The primary outcome was hospital readmission after revision TKA. Patient demographics, comorbidities, and postoperative complications were recorded and compared between readmitted and non-readmitted patients.

Results: Forty-five (26.2%) of the 171 cases were readmitted following revision TKA. The leading diagnoses at readmission varied from arthrofibrosis in 28.9% of patients, implant infection in 22.2% of patients, and implant failure in 20.0% of patients. Male gender was found to be a significant independent variable for readmission. This study also found that 51.1% of all readmitted patients continued to have complaints that required additional hospital readmissions. The average number of total readmissions was 2.1 per readmitted patient.

Conclusion: This study was successful in identifying variables associated with readmission following revision TKA, as well as presenting information regarding the diagnoses associated with readmission. Our data also showed that if a patient was readmitted after revision TKA, it was likely that they would be admitted again. Due to the increasing prevalence and cost of these procedures, further studies are needed to better understand the risk factors and comorbidities leading to readmission in order to improve the perioperative care of these patients.

Surgical Technical Evidence Review for Elective Total Joint Replacement Conducted for the AHRQ Safety Program for Improving Surgical Care and Recovery

Background:

Use of enhanced recovery pathways (ERPs) can improve patient outcomes, yet national implementation of these pathways remains low. The Agency for Healthcare Research and Quality (AHRQ; funder), the American College of Surgeons, and the Johns Hopkins Medicine Armstrong Institute for Patent Safety and Quality have developed the Safety Program for Improving Surgical Care and Recovery—a national effort to catalyze implementation of practices to improve perioperative care and enhance recovery of surgical patients. This review synthesizes evidence that can be used to develop a protocol for elective total knee arthroplasty (TKA) and total hip arthroplasty (THA).

Study Design:

This review focuses on potential components of the protocol relevant to surgeons; anesthesia components are reported separately. Components were identified through review of existing pathways and from consultation with technical experts. For each, a structured review of MEDLINE identified systematic reviews, randomized trials, and observational studies that reported on these components in patients undergoing elective TKA/THA. This primary evidence review was combined with existing clinical guidelines in a narrative format.

Results:

Sixteen components were reviewed. Of the 10 preoperative components, most were focused on risk factor assessment including anemia, diabetes mellitus, tobacco use, obesity, nutrition, immune-modulating therapy, and opiates. Preoperative education, venous thromboembolism (VTE) prophylaxis, and bathing/Staphylococcus aureus decolonization were also included. The routine use of drains was the only intraoperative component evaluated. The 5 postoperative components included early mobilization, continuous passive motion, extended duration VTE prophylaxis, early oral alimentation, and discharge planning.

Conclusion:

This review synthesizes the evidence supporting potential surgical components of an ERP for elective TKA/THA. The AHRQ Safety Program for Improving Surgical Care and Recovery aims to guide hospitals and surgeons in identifying the best practices to implement in the surgical care of TKA and THA patients.

Morbid Obesity in Total Knee Arthroplasty: Joint-Specific Variance in Outcomes for Operative Time, Length of Stay, and Readmission

BACKGROUND

It is increasingly apparent that the effect of obesity in arthroplasty is joint-specific. This study evaluates the effects of morbid obesity on primary total knee arthroplasty by comparing short-term outcomes between a morbidly obese (body mass index ≥40 kg/m²) and a normal weight (body mass index 18.5-<25 kg/m²) cohort at our institution between January 2003 and December 2010.

METHODS

One hundred seventeen morbidly obese patients were compared with 94 normal weight patients. Operative time, length of stay, complications, 30-day readmission, and readmission length were compared.

RESULTS

Morbid obesity conveyed no significant increase in 30-day readmission. Operative time was increased at 100 minutes in the morbidly obese group, compared with 90.5 minutes (P = .026).

CONCLUSION

Morbid obesity conveyed no increased risk of length of stay or readmission in this cohort.

Results of a Modular Revision System in Total Knee Arthroplasty

BACKGROUND

Revision total knee arthroplasty (TKA) poses unique challenges compared with primary TKA such as bone loss, deformity, and ligament instability. Modular component options allow flexibility to deal with these complexities. The purpose of this study was to evaluate midterm outcomes for revision TKA using a modular revision knee system with complete interchangeability and multiple options for augmentation, offset, constraint, and stem extensions.

METHODS

A query of our practice registry revealed 257 consented patients (274 knees and 278 TKA) with minimum 2-year follow-up who underwent aseptic revision TKA with a modular system (Vanguard Super Stabilized Knee; Zimmer Biomet, Warsaw, IN) between 2005 and 2013. Four patients were rerevised to a second Vanguard Super Stabilized Knee within the study period. Mean age was 68 years, and mean number of previous surgeries was 2 (1-14).

RESULTS

At mean follow-up of 6.0 years (range, 2-11 years), there have been 25 aseptic revisions involving one or more components (9.0%): 15 aseptic loosening with concomitant instability in 2, 8 others with instability, 1 with hypersensitivity, and 1 revised elsewhere for unknown cause. Ten knees were revised for infection. Range of motion improved from 100° preoperatively to 105° most recently. Knee Society clinical scores improved from 45 to 79, and function scores from 46 to 56. Radiographic evaluation revealed satisfactory position, fixation, and alignment in 97% and abnormal findings in 7 knees: 4 limited to the patella, 1 tibial radiolucency, 1 femoral and tibial radiolucency, and 1 tibial subsidence.

CONCLUSION

The results of this modular TKA revision system at 6 years mean follow-up are promising for use in complex scenarios, with a low frequency of aseptic rerevision, good knee stability, and substantial improvements in range of motion and clinical and functional outcomes.

Type 2 diabetes and in-hospital complications after revision of total hip and knee arthroplasty

PURPOSE

To assess the effect of type 2 diabetes (T2DM) on hospital outcomes such as in hospital postoperative complications (IHPC), length of hospital stay (LOHS) and in-hospital mortality (IHM) after the revision of total hip arthroplasty (RHA) and total knee arthroplasty (RKA) and to identify factors associated with IHPC among T2DM patients undergoing these procedures.

METHODS

We performed a retrospective study using the Spanish National Hospital Discharge Database, 2005-2014. We included patients who were ≥40 years old that had undergone RHA and RKA. For each T2DM patient, we selected a year-, gender-, age- and Charlson Comorbidity Index-matched non-diabetic patient.

RESULTS

We identified 44,055 and 39,938 patients who underwent RHA (12.72% with T2DM) and RKA (15.01% with T2DM). We matched 4,700 and 5,394 couples with RHA and RKA, respectively. Any IHPC was more frequent among patients with T2DM than among non-T2DM patients (19% vs. 15.64% in the RHA cohort and 12.94% vs. 11.09% in the RKA cohort, respectively). For patients who underwent RHA, postoperative infection (4.51% vs. 2.94%, p<0.001), acute post-hemorrhagic anemia (9.53% vs. 7.70%, p<0.001), mean LOHS and IHM were significantly higher in patients with T2DM. Among RKA patients, the incidence of acute posthemorrhagic anemia (7.21% vs. 5.62%; p = 0.001) and urinary tract infection (1.13% vs. 0.72%; p = 0.029) was significantly higher in patients with diabetes. Older age, obesity, infection due to internal joint prosthesis, myocardial infarction, congestive heart failure, mild liver disease and renal disease and emergency room admission were significantly associated with a higher risk of IHPC in T2DM patients. IHPC decreased over time only in T2DM patients who underwent RHA (OR 0.94, 95%CI 0.89-0.98).

CONCLUSIONS

Patients with T2DM who underwent RHA and RKA procedures had more IHPC after controlling for the effects of possible confounders. LOHS and IHM were also higher among RHA patients with diabetes. Older age, comorbidity, obesity and emergency room admission were strong predictors of IHPC in diabetic patients.

Morbid Obesity and Total Knee Arthroplasty: A Growing Problem

Obesity is an epidemic, with approximately 35% of the US population affected. This rate is unlikely to decline and may increase the demand for total knee arthroplasty (TKA). Data regarding the risks, benefits, and potential complications of TKA in this patient population are conflicting. Preoperative considerations are optimization of nutritional status, safe weight loss strategies, and bariatric surgery. Intraoperative concerns unique to this population include inadequate exposure, implant alignment, and durable implant fixation; postoperative issues include tibial loosening, wound complications, cardiovascular events, and respiratory complications. A thorough understanding of the medical and surgical complications associated with TKA in the obese patient will facilitate research efforts and improve outcomes.

[Fixed bearing unicondylar arthroplasty in medial osteoarthritis of the knee]

OBJECTIVE

The unicondylar prosthesis replaces the medial femerotibial compartment only, the part presenting with osteoarthritic changes. The remaining compartments of the knee present less osteoarthritic changes and thus can be preserved.

INDICATIONS

Osteoarthritis of the medial femorotibial compartment is the ideal indication for unicondylar arthroplasty. The knee should show an intraarticular deformity, which means the malalignment is caused by the osteoarthritic changes of the medial compartment.

CONTRAINDICATIONS

Malalignment of >5°, flexion contracture of >10°, mediolateral instability and symptomatic osteoarthritis of a second compartment should be considered as contraindications for unicondylar arthroplasty.

SURGICAL TECHNIQUE

In the current article, implantation of the BalanSys® system is presented. Femoral bony resection is solely ligament balanced. The technique allows creation of an optimal extension and flexion gap. Bone cuts were performed using a soft tissue tension device for measuring the extension and flexion gap.

POSTOPERATIVE MANAGEMENT

Full weight bearing on crutches is allowed immediately after surgery without restriction in flexion. Crutches are recommended for 4 weeks in order to compensate for neuromuscular deficits. Anticoagulation is recommended for 11-14 days according to the AWMF guidelines (S3 guidelines, Release:15 October 2015).

RESULTS

The clinical follow-up after 2 years showed 87 ± 13 points in the knee score and 80 ± 10 points in the function score. The mean range of motion increased from 113°±24° prior to surgery to 122°±23° after surgery. A preoperative extension deficit of 10° was observed in 9 patients and reduced postoperatively in 3 patients.

Strategies to Prevent Periprosthetic Joint Infection After Total Knee Arthroplasty and Lessen the Risk of Readmission for the Patient

There is yet to be a standardized total knee arthroplasty (TKA) surgical protocol that has been studied to a sufficient degree to offer evidence-based practices regarding infection and readmission prevention. Although high-level evidence is often sought to provide guidance concerning protocol- and process-level decisions, the literature is often confusing and nondefinitive in its conclusions and recommendations regarding periprosthetic joint infection and readmission prevention. Areas of study that require further investigation include the following: the role of patient optimization and preoperative mitigation of risk; perioperative antibiotics; operating room environment; blood management; operative techniques, implants, and infection prevention measures; wound care management; and post acute care. Patient-associated modifiable risk must be optimized to decrease poly joint infection rates after TKA. Protocol measures for TKA need to be standardized, and evidence-based practice measures need to be validated.

Risk of Reinfection After Treatment of Infected Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to determine the incidence of subsequent reinfections after initial treatment of an infected total knee arthroplasty, identify risk factors leading to reinfection, and compare results among the varying treatment modalities.

METHODS

A total of 1,493,924 primary TKA patients were identified from the Medicare data between October 1, 2005, and December 31, 2011. Patients who encountered periprosthetic joint infection (PJI) after TKA were identified using International Classification of Diseases, Ninth Revision, Clinical Modification code 996.66. The risk of subsequent PJI was stratified based on the first-line treatment and compared between the various first-line treatment groups.

RESULTS

A total of 16,622 patients (1.1%) were diagnosed with PJI. The Kaplan-Meier risk of PJI was 0.77% at 1 year and 1.58% at 6 years. Age (P < .001), Charlson score (P < .001), hospital control (P < .001), race (P = .036), census region (P = .031), gender (P < .001) were identified as risk factors for PJI. Of the PJI patients, 20.8% (n = 2806) were treated with incision and drainage (I&D), 15.9% (n = 2150) treated with I&D and liner exchange, 22.7% (n = 3069) treated with 1-stage revision, 39.7% (n = 5364) treated with 2-stage revision, and 0.98% (n = 132) treated with amputation. After first-line treatment, 26% of patients with PJI had a subsequent PJI. Patients undergoing I&D as a first-line treatment had the highest risk of reinfection, with risks of 28.2% at 1 year and 43.2% at 6 years. One-stage revision patients had 33.9% greater adjusted risk of reinfection than 2-stage revision patients (P < .001).

CONCLUSION

Two-stage reimplantation, despite 19% recurrence, had the highest success rate. Given the higher failure rates of I&D and single-stage revisions, guidelines need to be established for their specific indications.

Subcutaneous Fat Thickness Is Associated With Early Reoperation and Infection After Total Knee Arthroplasty in Morbidly Obese Patients

BACKGROUND

Morbid obesity has been associated with increased complications after primary total knee arthroplasty (TKA), but previous studies have failed to take factors such as body composition and fat distribution into consideration. The aims of this study were to (1) assess the interobservable and intraobservable reliabilities of measuring anterior knee subcutaneous fat thickness on lateral knee radiographs and (2) determine if these measurements associate with early complications in patients with morbid obesity.

METHODS

Using a retrospective case-control analysis, we reviewed 1689 primary TKAs performed in morbidly obese patients at our institution from 1995 to 2012. All patients (n = 58) who required reoperation for wound complication or infection within 90 days were compared to a matched cohort of morbidly obese patients who did not require early reoperation. Distances from patella skin (prepatellar thickness) and tibial tubercle skin (pretubercular thickness) were measured on routine lateral knee radiographs and associated with outcomes.

RESULTS

Intraobserver and interobserver reliabilities were excellent for both measurements. Knees in the reoperation group had significantly greater prepatellar (P = .0001) and pretubercular (P = .0006) soft tissue thickness. Prepatellar thickness ≥15 mm and pretubercular thickness ≥25 mm increased the risk of early reoperation by 2.0× (P = .0003) and 1.6× (P = .023), respectively, and were more predictive measurements than body mass index.

CONCLUSION

Anterior knee subcutaneous fat thickness can be reproducibly measured on lateral knee radiographs and is associated with a significantly increased risk of early reoperation for wound complications and infection after primary TKA in morbidly obese patients.

Morbidly Obese vs Nonobese Aseptic Revision Total Hip Arthroplasty: Surprisingly Similar Outcomes

BACKGROUND

We aimed to compare the outcomes between matched morbidly obese (BMI ≥ 40 kg/m(2)) and nonobese (BMI <30 kg/m(2)) patients undergoing first-time aseptic revision THA with at least 4 years of follow-up.

METHODS

Groups were matched 1:1 using sex, age, and date of revision surgery (123 patients in each group).

RESULTS

The overall incidence and risk of complication, reoperation, and re-revision were similar between groups. Morbidly obese patients were more likely to dislocate (odds ratio [OR], 3.3; P = .03), but were less likely to develop polyethylene wear (OR, 0.1; P = .04) and aseptic loosening (OR, 0.3; P = .03).

CONCLUSION

Quality outcome measures such as hospital readmission were not addressed by this study and could be the basis for future studies.

LEVEL OF EVIDENCE

level III, prognostic study.

Insulin Dependence Increases the Risk of Failure After Total Knee Arthroplasty in Morbidly Obese Patients

The aims of this study were to compare the outcomes between nondiabetic (n=1284), type II diabetic (n=530), and insulin-dependent type II diabetic (n=164) morbidly obese (body mass index ≥40 kg/m(2)) patients undergoing primary total knee arthroplasty at 6-year follow-up. Patients with type II diabetes mellitus (DM) had similar outcomes when compared with non-DM patients. However, patients with insulin dependence had an increased risk of reoperation (hazard ratio [HR], 1.8; P=.005), revision (HR, 2; P=.02), and periprosthetic joint infection (HR, 2.1; P=.03), as well as decreased 10-year implant survivorship (84% vs 92%; P=.01) when compared to non-DM patients. Prospective studies should further evaluate outcomes and optimization measures within this population.

LEVEL OF EVIDENCE

Level III-prognostic study.

Painful knee arthroplasty: current practice

Primary total knee arthroplasty is the treatment for end-stage arthritis of the knee; in the last years, it is becoming more common and reliable, due to technical and implant improvement. With larger implant rates, the overall complications will increase and pain is the most common sign of implant failure. Pain can be related to a lot of different clinical findings, and the surgeon has to be aware of the various etiologies that can lead to failure. Pain does not always mean revision, and the patient has to be fully evaluated to have a correct diagnosis; if surgery is performed for the wrong reason, this will surely lead to a failure. In this paper, the authors revised the more common causes of failure that can have a painful onset proposing an approach for diagnosis and treatment.

Bariatric surgery does not improve outcomes in patients undergoing primary total knee arthroplasty

Bariatric surgery has been advocated as a means of reducing body mass index (BMI) and the risks associated with total knee arthroplasty (TKA). However, this has not been proved clinically. In order to determine the impact of bariatric surgery on the outcome of TKA, we identified a cohort of 91 TKAs that were performed in patients who had undergone bariatric surgery (bariatric cohort). These were matched with two separate cohorts of patients who had not undergone bariatric surgery. One was matched 1:1 with those with a higher pre-bariatric BMI (high BMI group), and the other was matched 1:2 based on those with a lower pre-TKA BMI (low BMI group).

In the bariatric group, the mean BMI before bariatric surgery was 51.1 kg/m2 (37 to 72), which improved to 37.3 kg/m2 (24 to 59) at the time of TKA. Patients in the bariatric group had a higher risk of, and worse survival free of, re-operation (hazard ratio (HR) 2.6; 95% confidence interval (CI) 1.2 to 6.2; p = 0.02) compared with the high BMI group. Furthermore, the bariatric group had a higher risk of, and worse survival free of re-operation (HR 2.4; 95% CI 1.2 to 3.3; p = 0.2) and revision (HR 2.2; 95% CI 1.1 to 6.5; p = 0.04) compared with the low BMI group.

While bariatric surgery reduced the BMI in our patients, more analysis is needed before recommending bariatric surgery before TKA in obese patients.

Cite this article: Bone Joint J 2015;97-B:1501–5.