Outcomes of Total Knee Arthroplasty Revisions in Obese and Morbidly Obese Patient Populations

BackgroundThe obese population is at higher risk for complications following primary total knee arthroplasty (TKA), but little data is available regarding revision outcomes. This study aimed to investigate the role of body mass index (BMI) in the cause for revision TKA and whether BMI classification is predictive of outcomes.MethodsA multi-institutional database was generated, including revision TKAs from 2012 to 2019. Data collection included demographics, comorbidities, surgery types (primary revision, repeat revision), reasons for revision, lengths of hospital stay, and surgical times. Patients were compared using 3 BMI categories: nonobese (18.5 to 29.9), obese (30 to 39.9), and morbidly obese (≥40). Categorical and continuous variables were analyzed using chi-square and 1-way analysis of variance tests, respectively. Regression analyses were used to compare reasons for revision among weight classes.ResultsObese and morbidly obese patients showed significant risk for repeat revision surgery in comparison to normal weight patients. Obese patients were at higher risk for primary revision due to stiffness/fibrosis and repeat revision due to malposition. In comparison to the obese population, morbidly obese patients were more likely to require primary revision for dislocation and implant loosening.ConclusionSignificant differences in primary and repeat revision etiologies exist among weight classes. Furthermore, obese and morbidly obese patients have a greater risk of requiring repeat revision surgery. These patients should be informed of their risk for multiple operations, and surgeons should be aware of the differences in revision etiologies when anticipating complications following primary TKA.     

The relationship between obesity and the age at which hip and knee replacement is undertaken

We audited the relationship between obesity and the age at which hip and knee replacement was undertaken at our centre. The database was analysed for age, the Oxford hip or knee score and the body mass index (BMI) at the time of surgery. In total, 1369 patients were studied, 1025 treated by hip replacement and 344 by knee replacement. The patients were divided into five groups based on their BMI (normal, overweight, moderately obese, severely obese and morbidly obese). The difference in the mean Oxford score at surgery was not statistically significant between the groups (p > 0.05). For those undergoing hip replacement, the mean age of the morbidly obese patients was ten years less than that of those with a normal BMI. For those treated by knee replacement, the difference was 13 years. The age at surgery fell significantly for those with a BMI > 35 kg/m(2) for both hip and knee replacement (p > 0.05). This association was stronger for patients treated by knee than by hip replacement.     

Effects of the Obesity Epidemic on Total Hip and Knee Arthroplasty Demographics

BackgroundHigher body mass index (BMI) is a well-known risk factor for the development of hip and knee osteoarthritis and predicts total hip arthroplasty (THA) and total knee arthroplasty (TKA) at an earlier age. The purpose of this study is to document the nationwide trends in age and obesity in primary THA and TKA throughout the obesity epidemic.MethodsA retrospective analysis of the National Inpatient Sample database was conducted on patients undergoing primary THA and TKA for primary OA between 2002 and 2017. Analysis of variance and chi-square tests were performed to examine changes in age and obesity percentage over time, respectively. Pearson correlations were used to assess the relationship between patient age, BMI, and year of surgery.ResultsA total of 688,371 THA and 1,556,651 TKA were identified over the sixteen-year period. Between 2002 and 2017, the proportion of obese patients increased for both THA (7.0% to 22.7%, P < .001) and TKA (10.7% to 30.4%, P < .001). Mean age significantly decreased for both THA (66.7 to 65.9 years, P < .001) and TKA (67.6 to 66.8 years; P < .001). Over time, BMI significantly increased (THA: r = 0.221 vs. TKA: r = 0.272) and patient age decreased (THA: r = -0.031 vs. TKA: r = -0.137) for both procedures (P < .001 for all).ConclusionTHA and TKA patients have become younger and increasingly more obese throughout the obesity epidemic, as obesity rates have tripled over this time period. The current investigation is the first to demonstrate significant trends in both age and obesity in the THA and TKA populations on a national level.Level of EvidenceIII.     

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

BackgroundObesity 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.MethodsData 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.ResultsA 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.ConclusionBy 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 evidenceLevel III, Retrospective Cohort Study.     

Morbid Obesity and Excessive Hospital Resource Consumption for Unilateral Primary Hip and Knee Arthroplasty

Two objectives of this study were (i) to estimate the number of primary total hip arthroplasty (THA) or total knee arthroplasty (TKA) performed on morbidly obese people in the United States, and (ii) to estimate the economic impact of morbid obesity on hospital resource use. In 2006, approximately 2.9% (6713 cases) of primary THA and 4.2% (20 964 cases) of primary TKA recipients were diagnosed as morbidly obese. Despite the controversy associated with increased infection risk and failure rate, a large number of morbidly obese people seem to consider that the benefits outweigh the risks. When sex, age, race, and primary payer were held constant, the hospital resource consumption for unilateral primary THA and TKA was 9% ($1432) and 7% ($1025) higher among morbidly obese patients than among nonobese patients, respectively.     

Results of Cemented Posterior-Stabilized Total Knee Arthroplasty in Obese Patients With an Average 10-Year Follow-Up

BackgroundObese and morbidly obese patients undergoing primary total knee arthroplasty (TKA) place significant stress at the bone-cement-implant interface over the life of the patient. The purpose of this study is to evaluate results of cemented, posterior-stabilized TKA in obese and morbidly obese patients at an average follow-up of 10 years.MethodsRetrospective study of 181 patients who had a cemented, posterior-stabilized TKA between 2000 and 2013 with body mass index >35 at the time of surgery was conducted. Clinical data and radiographs were evaluated along with survivorship, complications, and revisions. Minimum follow-up was 5 years with an average follow-up of 10 years.ResultsThere were 135 women and 46 men in the study, with mean age of 60.2 years (range 43-80), mean body mass index of 42.0 (range 35.1-66.1), and an average follow-up of 10 years (range 5-18). There were a total of 39 failures (22%) that underwent revision TKA surgery with mean time to revision of 8 years. Failures included 25 (14%) cases of aseptic loosening; 9 (5%) polyethylene wear; 2 (1%) prosthetic joint infection; and 3 additional revisions for instability, pain, and stiffness. There were a total of 11 cases of isolated tibial component loosening and 13 for both tibial and femoral loosening. Survivorship at 15 years with aseptic loosening as the endpoint was 86.7%, and for all causes 79.6% at 15 years.ConclusionAseptic loosening is the leading cause of failure following TKA in obese and morbidly obese patients with decreasing survivorship from 96.1% to 91.2% and 86.7% at 5, 10, and 15 years, respectively.     

Increased operating room time in patients with obesity during primary total knee arthroplasty: conflicts for scheduling

Obesity is associated with increased complications related to total knee arthroplasty (TKA), but the relationship between body mass index (BMI) and operating room time during TKA is unknown. A total of 454 unilateral primary TKAs (2005-2009) were reviewed and categorized by BMI (normal weight, 18.5-25 kg/m(2); overweight, 25-30 kg/m(2); obese class I, 30-<35 kg/m(2); class II, 35-40 kg/m(2); class III, >40 kg/m(2)). Intraoperative time measurements (total room time, anesthesia induction time, tourniquet time, closing time, surgery time) were compared across the BMI groups. Comparing normal weight to obese class III, time differences were significant in total room time (24 minutes, P < .01), surgery time (16 minutes, P < .01), tourniquet time (7.5 minutes, P < .01), and closure time (8 minutes, P < .01). Armed with this information, BMI can be used to better allocate operating room time for TKA.     

Pretubercular Subcutaneous Thickness Is a Protective Factor for Superficial Wound Complications After Total Knee Arthroplasty in Nonmorbidly Obese Patients

BackgroundAnterior knee subcutaneous thickness has been associated with increased risk of early reoperation for surgical site infection after primary total knee arthroplasty (TKA) in morbidly obese patients. However, most patients undergoing TKA are not morbidly obese. The aims of this study were to (1) assess the association between anterior knee subcutaneous thickness and early superficial wound complications and (2) determine a threshold value for anterior knee subcutaneous thickness measures that can assist in preoperative risk stratification in nonmorbidly obese TKA patients.MethodsUsing retrospective analysis, we reviewed 494 primary TKAs performed in patients with a body mass index <40 kg/m² at our institution from January 1, 2010 to December 31, 2017. All patients developing a superficial surgical site infection within 90 days of index arthroplasty requiring treatment with antibiotics or reoperation were identified. Prepatellar thickness and pretubercular thickness were measured on preoperative lateral radiographs and associated with 90-day superficial wound complications.ResultsSixty-two of the 494 patients developed a superficial wound complication within 90 days of index arthroplasty. TKA patients in the superficial wound complication group had significantly less pretubercular thickness (P = .027). Risk of developing 90-day superficial wound complication was 1.85-fold lower when pretubercular thickness was ≥12 mm (P = .028). Prepatellar thickness (P = .895) was not significantly associated with superficial wound complications.ConclusionIncreased pretubercular thickness is a protective factor for developing superficial wound complications, with 12 mm being an ideal threshold value for preoperative risk stratification in nonmorbidly obese patients undergoing primary TKA surgery.     

A comparison of outcomes in morbidly obese,obese and non-obese patients undergoing primary total knee and total hip arthroplasty

Background

Obesity is a growing public health issue with the prevalence of morbid obesity, (Body Mass Index (BMI) ≥ 40 kg/m²) increasing. There is some evidence these patients have more peri- and post-operative complications and poorer outcomes when undergoing arthroplasty procedures. This audit aimed to determine and compare the outcomes of non-obese, obese and morbidly obese patients undergoing arthroplasty at our institution.

Overweight and Obese Patients Require Total Hip and Total Knee Arthroplasty at a Younger Age

Osteoarthritis (OA) of the hip and knee is associated with obesity but the exact effect remains unknown. The aim of this study was to investigate the independent association between the age at which total hip (THA) and knee arthroplasty (TKA) are required for end-stage severe OA according to body mass index (BMI) category. A retrospective study of 3,699 patients undergoing primary THR and 4,740 patients undergoing a primary TKA for the treatment of end-stage OA. Patient demographics, BMI, comorbidity, social deprivation, Short form 12 and Western Ontario and McMaster Universities OA Index score pre-operatively were collected. Linear regression analysis identified that there was an earlier age at which THA and TKA were performed with increasing obesity BMI category compared with normal-weight patients when adjusting for confounding variables. Using the normal weight category as the reference group overweight (0.9 years [95% confidence interval, CI] 0.0–1.8) and obese patients in class 1 (3.1 years, 95% CI 2.1–4.2), 2 (5.2 years, 95% CI 3.7–6.7), and 3 (7.4 years, 95% CI 5.0–9.8) required their THA at a significantly (p ≤ 0.04) earlier age. Again, using normal weight category as the reference group overweight (2.1 years, 95% CI 1.3–2.9) and obese patients in class 1 (4.7 years, 95% CI 3.8–5.6), 2 (6.7 years, 95% CI 5.6– 7.7) and 3 (10.5 years, 95% CI 8.9–12.1) required their TKA at a significantly (p < 0.001) earlier age. Overweight and obese patients required their THA and TKA at a significantly younger age. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:348-355, 2020     

身体质量指数对全膝关节置换患者膝关节功能的影响

目的采用Meta分析的方法,评价非肥胖组、超重组、肥胖组及病理性肥胖组患者全膝关节置换膝关节功能的差异。 方法计算机检索PubMed、荷兰医学文摘数据库(EMBASE)、知网、万方等中英文数据库从1989年1月至2017年12月关于不同身体质量指数全膝关节置换患者膝关节功能的文献。纳入回顾性或前瞻性纵向研究、按世界卫生组织身体质量指数(BMI)分组的全膝关节置换术(TKA)患者、膝关节功能评价采用纽约特种外科医院膝关节评分标准(HSS)或美国膝关节协会评分(KSS)、效应指标为样本量、均数和标准差的文献,排除文献重复或资料相似、BMI分组未落上述分组范围内及未提供样本量、均数和标准差的文献。由2名研究者独立对文献进行筛选、资料提取和质量评价后,用Stata 12.0软件进行Meta分析。 结果最终纳入13篇文献。Meta分析结果示,非肥胖组、超重组、肥胖组及病理性肥胖组患者的术后膝关节功能评分均高于术前(P<0.01),另外,肥胖组患者的术前膝关节功能评分低于非肥胖组[SMD ＝0.32,95%CI(0.07,0.58),P＝0.012],术后膝关节功能评分低于超重组[SMD ＝0.18,95%CI(0.04,0.32),P＝0.013]。 结论全膝关节置换术后不同体质指数患者膝关节功能评分均有大幅提高,但27 ≤体质指数<30则可能对术前及术后膝关节功能造成负面影响。     

Impact of Bariatric Surgery on Inpatient Complication,Cost, and Length of Stay Following Total Hip or Knee Arthroplasty

BackgroundMorbid obesity is an important risk factor for arthroplasty and also closely associated with worse postoperative outcomes. Bariatric surgery is effective in losing weight and decreasing comorbidities associated with obesity. However, no study had demonstrated the influence of bariatric surgery on the outcome of arthroplasty in a large population.MethodsWe used 2006-2014 discharge records from the Nationwide Inpatient Sample, and identified study population and inpatient complications by International Classification of Diseases, 9th Revision, Clinical Modification diagnosis/procedure codes. Propensity score analysis was used to match total hip arthroplasty (THA) or total knee arthroplasty (TKA) patients with morbid obesity and THA or TKA patients with bariatric surgery.ResultsProportion of morbid obesity in both TKA and THA patients demonstrated a rising trend, while proportion of bariatric surgery in morbidly obese TKA and THA patients remains steady after 2007. For THA patients, there was fewer pulmonary embolism, more blood transfusion and anemia, and shorter length of stay in bariatric surgery group. For TKA patients, bariatric surgery group had a lower risk of pulmonary embolism, respiratory complications, death, and shorter length of stay, but bariatric surgery group had a higher risk of blood transfusion and anemia.ConclusionThere is evidence that bariatric surgery prior to arthroplasty, especially THA, appears to reduce rates of pulmonary complications and length of stay. But anemia and blood transfusion seem to be more common in patients with prior bariatric surgery.     

Association Between Body Mass Index and Thirty-Day Complications After Total Knee Arthroplasty

Background

Although previous studies have evaluated the effect of obesity on the outcomes of total knee arthroplasty (TKA), most considered obesity as a binary variable. It is important to compare different weight categories and consider body mass index (BMI) as a continuous variable to understand the effects of obesity across the entire range of BMI. Therefore, the objective of this study is to analyze the effect of BMI on 30-day readmissions and complications after TKA, considering BMI as both a categorical and a continuous variable.

Body Mass Index and the Impact on Hospital Resource Use in Patients Undergoing Total Knee Arthroplasty

We identified all total knee arthroplasty patients between 1996 and 2004 and classified them by preoperative body mass index (BMI) as normal (BMI, 18.5-24.9 kg/m²), overweight (BMI, 25.0-29.9 kg/m²), obese (30-34.9 kg/m²), or morbidly obese (≥ 35.0 kg/m²). Of 5521 patients, 769 had a normal BMI, 1938 were overweight, 1539 were obese, and 1275 were morbidly obese. Adjusted length of stay was no different between normal (4.85 days), overweight (4.84 days), obese (4.86 days), or morbidly obese patients (4.93 days) (P = .30). Overall costs were similar among normal ($15?386), overweight ($15?430), obese ($15?646), or morbidly obese patients ($15?752) (P = .24). Postsurgical costs were no different among normal ($9860), overweight ($9889), obese ($10?063), or morbidly obese patients ($10?136) (P = .44). Our results suggest that increased BMI does not lead to increased hospital resource use for total knee arthroplasty.     

Elevated Body Mass Index Is Associated With Early Total Knee Revision for Infection

Background

Obesity affects over half a billion people worldwide, including one-third of men and women in the United States. Obesity is associated with higher postoperative complication rates after total knee arthroplasty (TKA). It remains unknown whether obese patients progress to revision TKA faster than nonobese patients.

Higher Body Mass Index Leads to Longer Operative Time in Total Knee Arthroplasty

Obesity has been shown to be a risk factor for degenerative knee arthritis and its incidence is increasing in epidemic proportions. Obesity has also been shown to be a risk factor for surgical complications associated with total knee replacement (TKR) surgery. There have been no prior investigations examining the relationship between body mass index (BMI) and surgical time during TKR. Two hundred and seventy three patients were evaluated and stratified by BMI. There was a direct linear relationship between BMI and operative time. In addition, the higher the BMI group, the younger the age at surgery, and obese class III patients experienced a higher rate of early post-operative complication. Therefore, patients should be counseled that obesity prior to TKR surgery might lead to a longer operative time and any sequelae associated with further exposure of the operative wound, especially with regard to higher rates of prosthetic joint infection (PJI).     

Increased Survivorship of Cementless versus Cemented TKA in the Morbidly Obese. A Minimum 5-Year Follow-Up

Background

Total knee arthroplasty (TKA) in the morbidly obese patients can be challenging with an increased risk of complications. Studies have shown increased aseptic failures with well-aligned cemented TKAs in the obese patient. The purpose of this study is to determine if TKA in the morbidly obese (body mass index [BMI] ≥ 40) using cementless implants would demonstrate improved results and survivorship compared to cemented TKA at a minimum 5-year follow-up.

The effects of increasing obesity on outcomes of vascular surgery

The aim of this study was to determine whether vascular patients are becoming progressively more obese and whether morbid obesity affects outcomes from vascular surgery. Data for the index vascular procedures of infrainguinal bypass, carotid endarterectomy, and abdominal aortic aneurysm (AAA) repair were collected in a computer database for 1996-2006. Body mass index (BMI) was stratified into <18.5 kg/m2 as underweight, >35 kg/m2 as morbidly obese, and other as control (18.5 < BMI < 35). The data were analyzed with respect to operation duration, length of stay, complication rates, and mortality rates. Results were adjusted for potential confounding variables, including mode of admission, diabetes, cardiac history, renal function, and smoking. A total of 1,317 patients were reviewed, and 1,105 cases were deemed suitable for analysis. The incidence of morbid obesity increased in a linear manner from 1.3% to 9% over the 10-year period. The operation duration was longer for morbidly obese subjects compared with normals. This was only statistically significant for AAA repair category, with a mean operating time of 158.4 +/- 65.5 min for patients with BMI <35 kg/m2 vs. 189.8 +/- 92.2 min for morbidly obese patients (p < 0.014). Infection rates were consistently higher in the morbidly obese group; however, this reached a statistically significant rate among AAA repair cases (43.5% [n = 16] vs. 34.8% [n = 159], p < 0.004). There were no significant differences in other complications, graft failure, length of stay, or mortality. Vascular patients are becoming progressively more obese. Procedures performed on morbidly obese subjects take longer, and these patients have higher rates of infectious complications. This is mainly attributable to AAA. This did not translate into poorer final outcomes in this study, although significant differences might emerge from a larger sample.     

体重指数及年龄对人工关节置换术后下肢深静脉血栓形成的影响

目的探讨体重指数及年龄对人工关节置换术后下肢深静脉血栓形成(deepveinthrombosis,DVT)的影响。方法采用病例对照研究,分析2004年4月～2004年8月符合纳入条件行髋、膝人工关节置换术的95例患者的临床资料。其中男27例,女68例。年龄23～78岁,平均60岁。体重指数(bodymassindex,BMI)14.34～40.39kg/m2,平均25.88kg/m2。人工髋关节置换43例48髋,人工膝关节置换52例80膝。患者按WHOBMI标准分层,即:非肥胖BMI≤25.00kg/m2、超重BMI25.01～27.00kg/m2、肥胖BMI27.01～30.00kg/m2、病理性肥胖BMI>30.00kg/m2,以及按年龄分为≤40岁、41～60岁、61～70岁、>70岁4层,研究其与关节置换术后DVT的相关性。患者术前及术后7～10d均行低分子肝素抗凝预防术后DVT,并于术后7～10d采用彩色多普勒检查双下肢深静脉血流通畅情况及DVT发生率。结果术后45例患者发生DVT,发生率为47.4%,近端DVT发生率为3.2%。DVT组BMI为27.50±3.18kg/m2,高于无DVT组(24.42±4.51kg/m2),差异有统计学意义(P<0.05);分层后,BMI>25kg/m2的患者发生DVT的风险是BMI≤25kg/m2患者的2.24倍(P<0.05);BMI按WHO标准进行分层后,超重、肥胖及病理性肥胖的患者发生DVT的风险分别是非肥胖患者的7.04、4.80及9.60倍,差异均有统计学意义(P<0.05),肥胖患者发生DVT的风险比其他两层患者低,而病理性肥胖患者发生DVT的风险最高。DVT组年龄为65.24±6.98岁,高于无DVT组(54.84±15.11岁),差异有统计学意义(P<0.05)。41～60岁、61～70岁及>70岁组患者发生DVT的风险分别是年龄≤40岁患者的24.0、38.2及24.4倍,差异均有统计学意义(P<0.05)。结论肥胖(BMI>25kg/m2)及高龄(年龄>40岁)是影响人工关节置换术后DVT形成的高危因素,其中61～70岁的患者发生DVT的风险最高。肥胖、高龄患者行人工关节置换术时应予足够预防性抗凝治疗,术后严密观察双下肢情况,必要时行超声或静脉造影检查,防止发生致命性肺栓塞。     

Preoperative Weight Loss and Postoperative Weight Gain Independently Increase Risk for Revision After Primary Total Knee Arthroplasty

BackgroundThe current American Association of Hip and Knee Surgeons (AAHKS) guidelines recommend preoperative weight loss before total knee arthroplasty (TKA) in patients with body mass index (BMI) ≥40 kg/m². However, there is a paucity of evidence on TKA outcomes after preoperative weight loss. This study therefore evaluated predictors of preoperative and postoperative BMI changes and their impact on outcomes after TKA.MethodsThis is a retrospective review of 3058 primary TKAs at an academic institution from 2015 to 2019. BMI was collected on the day of surgery. Preoperative and postoperative BMI at 6 months and 1 year were also obtained. BMI change of ≥5% was considered clinically significant. Mean follow-up was 3.2 years. Patient demographics, acute postoperative outcomes, and all-cause revisions were compared between patients who gained, lost, or maintained weight using univariate and multivariable analyses.ResultsPreoperative weight loss was predictive of postoperative weight gain (P < .001), and preoperative weight gain was predictive of postoperative weight loss (P < .001). Cox regression analysis revealed that ≥5% BMI loss preoperatively increased risk for all-cause revisions (P = .030), while ≥5% BMI gain postoperatively increased risk for prosthetic joint infections (P = .016). Patients who lost significant weight both before and after surgery had the highest risk for all-cause revisions (P = .022).ConclusionWeight gain postoperatively was associated with inferior outcomes. Significant weight loss before surgery led to a “rebound” in weight gain, and independently increased risk for all-cause revision. Therefore, current recommendations for weight loss before TKA in morbidly obese patients should be re-evaluated.