Effect of Physical Parameters on Outcomes of Total Knee Arthroplasty

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.

Anthropometric measures of obesity in patients with knee joint pathology: Body surface area versus body mass index

BACKGROUND

Obesity is quantified using body mass index. Body surface area may provide a superior and more anthropometric method of quantifying obesity in patients with musculoskeletal knee disease. This study compares the effect of weight, height, age and gender on body mass index and body surface area in a population with orthopaedic knee disease.

METHODS

An observational cohort study was conducted of patients presenting with musculoskeletal knee disease. Associations between body mass index, body surface area, age, gender, height, weight and operative versus non-operative management were analysed.

RESULTS

A total of 151 patients were included. Body surface area was more strongly correlated to weight than body mass index (r = 0.98, p < 0.001 versus r = 0.84, p < 0.001). Body surface area also reflects height which body mass index under presents (r = 0.65, p < 0.001 versus r = -0.08, p = 0.35). Body mass index and body surface area were correlated with one another (r = 0.70, p < 0.001). Age was inversely correlated with body surface area (r = -0.20, p = 0.013) but not body mass index (r = 0.05, p = 0.585). Body mass index did not differ between males and females (30.1 versus 30.9, p = 0.37); however, BSA scores were significantly higher in males than females (2.11 versus 1.91, p < 0.001). Neither body surface area nor body mass index scores influenced operative versus non-operative treatment.

CONCLUSION

Body surface area could be a useful alternative to body mass index when considering obesity in patients with musculoskeletal knee pathology. Body surface area better reflects the effects of height, weight, age and gender than body mass index.

Cemented vs. Cementless Fixation in Primary Knee Replacement: A Narrative Review

Knee osteoarthritis (OA) is one of the leading causes of disability around the globe. Osteoarthritis is mainly considered a disease affecting the elderly. However, more and more studies show that sports overuse, obesity, or congenital disorders can initiate a pathologic cascade that leads to OA changes in the younger population. Nevertheless, OA mostly affects the elderly, and with increasing life expectancy, the disease will develop in more and more individuals. To date, the golden standard in the treatment of the end-stage of the disease is total joint replacement (TJR), which restores painless knee motion and function. One of the weakest elements in TJR is its bonding with the bone, which can be achieved by bonding material, such as poly methyl-methacrylate (PMMA), or by cementless fixation supported by bone ingrowth onto the endoprosthesis surface. Each technique has its advantages; however, the most important factor is the revision rate and survivor time. In the past, numerous articles were published regarding TJR revision rate, but no consensus has been established yet. In this review, we focused on a comparison of cemented and cementless total knee replacement surgeries. We introduced PICO rules, including population, intervention, comparison and outcomes of TJR in a PubMed search. We identified 783 articles published between 2010 and 2023, out of which we included 14 in our review. Our review reveals that there is no universally prescribed approach to fixate knee prostheses. The determination of the most suitable method necessitates an individualized decision-making process involving the active participation and informed consent of each patient.

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.

Comparison of clinical outcomes between total hip replacement and total knee replacement

BACKGROUND

Total hip replacements (THR) and total knee replacements (TKR) are effective treatments for severe osteoarthritis (OA). Some studies suggest clinical outcomes following THR are superior to TKR, the reason for which remains unknown. This study compares clinical outcomes between THR and TKR.

AIM

To compare the clinic outcomes of THR anad TKR using a comprehensive range of patient reported outcome measures (PROMs).

METHODS

A prospective longitudinal observational study of patients with OA undergoing THR and TKR were evaluated using a comprehensive range of generic and joint specific PROMs pre- and post-operatively.

RESULTS

A total of 131 patients were included in the study which comprised the THR group (68 patients) and the TKR group (63 patients). Both groups demonstrated significant post-operative improvements in all PROM scores (P < 0.001). There were no significant differences in post-operative PROM scores between the two groups: Hip and Knee Osteoarthritis Outcome scores (P = 0.140), Western Ontario and McMaster Universities Osteoarthritis Index pain (P = 0.297) stiffness (P = 0.309) and function (P = 0.945), Oxford Hip and Knee Score (P = 0.076), EuroQol-5D index (P = 0.386) and Short-Form 12-item survey physical component score (P = 0.106). Subgroup analyses showed no significant difference (P > 0.05) between cruciate retaining and posterior stabilised prostheses in the TKR group and no significant difference (P > 0.05) between cemented and uncemented fixation in the THR group. Obese patients had poorer outcomes following TKR but did not significantly influence the outcome following THR.

CONCLUSION

Contrary to some literature, THR and TKR are equally efficacious in alleviating the pain and disability of OA when assessed using a comprehensive range of PROMs. The varying knee prosthesis types and hip fixation techniques did not significantly influence clinical outcome. Obesity had a greater influence on the outcome following TKR than that of THR.

Body surface area and treatment failure in peritoneal dialysis-associated peritonitis

INTRODUCTION

This study mainly discussed the relationship between body surface area (BSA) and treatment failure of peritoneal dialysis-associated peritonitis (PDAP).

METHODS

The exposures were BSA grouped by the tertiles of BSA levels. The association between BSA and the risk of treatment failure in PDAP, defined as the temporary or permanent switch to hemodialysis and kidney transplantation, was evaluated in Cox proportional hazards models.

RESULTS

A total of 483 episodes in 285 patients were recorded in our center. As a three-level categorical variable, in reference to G3, the G1 of BSA displayed a 4.054-fold increased venture of treatment failure in a fully adjusted model. In sensitivity analysis, a lower value of BSA (G1) was identified as an independent risk factor for peritonitis episodes (odds ratio = 2.433, 95% confidence interval: 1.184-4.999, p = 0.015).

CONCLUSION

A lower level of body surface area was remarkably associated with a higher incidence of treatment failure among peritoneal dialysis-associated peritonitis episodes.

Total Hip and Knee Arthroplasty Surgery in the Morbidly Obese Patient: A Critical Analysis Review

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Obesity, defined as body mass index (BMI) ≥30, is a serious public health concern associated with an increased incidence of stroke, diabetes, mental illness, and cardiovascular disease resulting in numerous preventable deaths yearly.

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From 1999 through 2018, the age-adjusted prevalence of morbid obesity (BMI ≥40) in US adults aged 20 years and older has risen steadily from 4.7% to 9.2%, with other estimates showing that most of the patients undergoing hip and knee replacement by 2029 will be obese (BMI ≥30) or morbidly obese (BMI ≥40).

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In patients undergoing total joint arthroplasty (TJA), morbid obesity (BMI ≥40) is associated with an increased risk of perioperative complications, including prosthetic joint infection and mechanical failure necessitating aseptic revision.

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The current literature on the role that bariatric weight loss surgery before TJA has on improving surgical outcomes is split and referral to a bariatric surgeon should be a shared-decision between patient and surgeon on a case-by-case basis.

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Despite the increased risk profile of TJA in the morbidly obese cohort, these patients consistently show improvement in pain and physical function postoperatively that should be considered when deciding for or against surgery.

Fat tissue is a poor predictor of 1 year outcomes after total knee arthroplasty: A secondary analysis of a randomized clinical trial

BACKGROUND AND OBJECTIVE

Obesity may increase the risk of adverse events after total knee arthroplasty (TKA). Although body mass index (BMI) is commonly used in categorizing obesity, its accuracy is limited. Body fat percentage (BFP) might indicate adiposity status and predict arthroplasty-related outcomes better than BMI. We investigated whether BFP is predictive of TKA-related outcomes.

METHODS

In this secondary analysis, BFP was measured preoperatively from 294 participants of a randomized trial that investigated the effects of tourniquet and anesthesia methods on TKA. Data concerning in-hospital assessments and events were collected. Knee range of motion (ROM) was measured, the Brief Pain Inventory-short form and Oxford Knee Score questionnaires were used to collect data on patient-reported pain and function, and the 15-dimensional health-related questionnaire was used to assess quality of life preoperatively and 3 and 12 months postoperatively. The patients reported satisfaction to TKA 3 and 12 months postoperatively. Data concerning infectious and thromboembolic events within 90 postoperative days and revision surgery, manipulation under anesthesia, and mortality within 1 year were collected. A separate post hoc analysis was performed for 399 participants to assess the effects of BMI on the respective outcomes.

RESULTS

A 1-unit increase in BFP affected the ROM by -0.37° (95% confidence interval (CI) = -0.60 to -0.13) 12 months after surgery. BFP was not significantly associated with the operation time or adverse events. However, the number of most adverse events remained too low for adjusted analysis. A 1-unit increase in BMI increased the operation time by 0.57 min (95% CI = 0.10 to 1.04) and affected the ROM by -0.47° (95% CI = -0.74 to -0.20) 12 months postoperatively. Neither BFP nor BMI was significantly associated with acute pain, pain management, length of stay, or with pain, function, quality of life, or satisfaction to TKA at 12 months after surgery.

CONCLUSIONS

BFP seems to be a poor predictor of in-hospital results and of patient-reported outcomes 1 year after TKA.

TWITTER HANDLE

In this secondary analysis of a randomized trial, body fat percentage was poorly predictive of clinical outcomes during hospital stay and of patient-reported outcomes 1 year after TKA.

Medial Patellofemoral Ligament Reconstruction in Obese Patients Results in Low Complication Rates and Improved Subjective Outcomes

Purpose

To compare outcomes, activity scores, and complication rates of obese and non-obese patients undergoing medial patellofemoral ligament (MPFL) reconstruction.

Methods

A retrospective review identified patients undergoing MPFL reconstruction for recurrent patellofemoral instability. Patients were included if they had undergone MPFL reconstruction and had follow-up for a minimum of 6 months. Patients were excluded if they underwent surgery less than 6 months earlier, had no outcome data recorded, or underwent concomitant bony procedures. Patients were divided into 2 groups based on body mass index (BMI): BMI of 30 or greater and BMI less than 30. Presurgical and postsurgical patient-reported outcomes including Knee Injury and Osteoarthritis Outcome Score (KOOS) domains and the Tegner score were collected. Complications requiring reoperation were recorded. P < .05 was defined as a statistically significant difference.

Results

A total of 55 patients (57 knees) were included. There were 26 knees with a BMI of 30 or greater and 31 knees with a BMI less than 30. There were no differences in patient demographic characteristics between the 2 groups. Preoperatively, no significant differences were found in KOOS subscores or Tegner scores (P = .21) between groups. At minimum 6-month follow-up (range, 6.1-70.5 months), patients with a BMI of 30 or greater showed statistically significant improvements in the KOOS Pain, Activities of Daily Living, Symptoms, and Sport/Recreation subscores. Patients with a BMI less than 30 showed a statistically significant improvement in the KOOS Quality of Life subscore. The group with a BMI of 30 or greater had significantly lower KOOS Quality of Life (33.34 ± 19.10 vs 54.47 ± 28.00, P = .03) and Tegner (2.56 ± 1.59 vs 4.78 ± 2.68, P = .05) scores. Complication rates were low, with 2 knees (7.69%) requiring reoperation in the cohort with a BMI of 30 or greater and 4 knees (12.90%) requiring reoperation in the cohort with a BMI less than 30, including 1 reoperation for recurrent patellofemoral instability (P = .68).

Conclusions

In this study, MPFL reconstruction in obese patients was safe and effective, with low complication rates and improvements in most patient-reported outcomes. Compared with patients with a BMI less than 30, obese patients had lower quality-of-life and activity scores at final follow-up.

Level of Evidence

Level III, retrospective cohort study.

Tibial Stems in Primary Total Knee Arthroplasty: A literature Review

Abstract: This article displays a review of the specialty literature regarding the surgery of primary total knee arthroplasty (TKA), and more specifically refers to the complicated cases of primary total knee replacement where due to some preexisting pathologic circumstances, the orthopaedic surgeon must anticipate the risks and enhance the stability of the implant to obtain a long lifespan without revision surgeries. We collected the findings throught literature and compared them to our own surgical experience to create a rationale for the selection of the best knee prosthesis in surgical practice. Keywords: total knee arthroplasty; primary total knee arthroplasty; implant; prosthesis; tibial stem extension;

Obesity paradox among patients undergoing total knee arthroplasty: a retrospective cohort study

BACKGROUND

Obesity has been recognized as the risk factor for postoperative complication for surgical patients. However, recent studies have showed protective effect of obesity in surgical and non-surgical patients. Our study is to examine the association of body mass index(BMI) with early postoperative complications in patients undergoing total knee arthroplasty.

MATERIALS AND METHODS

All patients who had primary total knee arthroplasty between January 2014 and December 2019 were included. Medical records were retrospectively reviewed and BMI was categorized as underweight(BMI < 18.5), normal weight(18.5 < BMI < 24.9), overweight I(25 < BMI < 27.4), overweight II(27.5 < BMI < 29.9), obese I(30 < BMI < 34.9) and obese II(BMI ≥ 35). The association between BMI and occurrence of early postoperative complications was examined and logistic regression was used to calculate relationship between BMI and early postoperative complications.

RESULTS

A total of 2969 patients were included in our analysis. The overall complication rate in patients undergoing total knee arthroplasty was 14.8%, with the highest complication being 22.2% in the underweight group, the second highest in the normal weight group(17.5%), the lowest in the overweight I(13.8%) and obese I(12.0%) group and then higher again in obese II group(16.7%). In multivariable analyses, overweight I (OR 0.737, 95% CI 0.559-0.972, P = 0.031) and obese I (OR 0.631, 95% CI 0.449-0.885, P = 0.008) were associated with lower risk of early postoperative complications after total knee arthroplasty.

CONCLUSION

In this retrospective study, overweight and obese patients had a lower risk of early postoperative complications after total knee arthroplasty. Further studies are necessary to confirm and investigate the mechanism of obesity paradox in this surgical population.

TRIAL REGISTRATION

This study had been registrated in www.chictr.org.cn on 25/10/2021 and the registration ID was ChiCTR2100052408.

Movement Is Life-Optimizing Patient Access to Total Joint Arthroplasty: Obesity Disparities

Thirty five percent of the American population is considered obese (body mass index [BMI] > 30). Obesity disproportionately affects African Americans, Hispanics, and women. Obesity is associated with postoperative complications, including wound complications, infections, and revision total joint arthroplasty (including total hip arthroplasty and total knee arthroplasty). Current BMI benchmarks (many institutions rely on a BMI of 40) selectively preclude patients from having surgery. Patients in these underserved populations can be optimized through the lens of shared decision making through the assessment of food security (eg, food deserts and food swamps), ability to afford healthy food, knowledge of social safety net and community resources to access healthy food, nutrition and weight loss referrals to programs that accept all forms of insurance, weight loss measurements as a percentage of body weight lost instead of BMI cutoffs, pharmacologic modalities, and bariatric surgery.

Prediction of 90-Day Local Complications in Patients After Total Knee Arthroplasty: A Nomogram With External Validation

Background:

Local complications after total knee arthroplasty (TKA) significantly affect the patient’s prognosis. Nomograms can be a useful tool for predicting such complications.

Purpose:

To compare the preoperative and intraoperative factors of patients who underwent TKA with and without complications and to construct and validate a nomogram based on selective predictors of local complications within 90 days postoperatively.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

The nomogram was developed in a primary cohort that consisted of 410 patients who underwent primary TKA at the authors’ institution between January 2015 and September 2018. Predictor variables included 4 major local complications that can occur within 90 days: reoperation (including implant revision or removal for any reason and manipulation under anesthesia), infection, bleeding requiring ≥4 unit transfusion of red blood cells within 72 hours of surgery, and peripheral nerve injury. The authors used least absolute shrinkage and selection operator (LASSO) regression analysis for data dimension reduction and feature selection. Multivariable logistic regression analysis was used to develop the nomogram. Performance of the nomogram was assessed using C-index, calibration plot, area under the receiver operating characteristic curve (AUC), and decision curve analysis (DCA). The model was subjected to bootstrap validation and external validation using a prospective cohort of 249 patients.

Results:

Four significantly prognostic factors were incorporated into the nomogram: age-adjusted Charlson Comorbidity Index, American Society of Anesthesiologists score, tourniquet time, and estimated intraoperative blood loss. The model displayed good discrimination, with a C-index of 0.819 and an AUC of 0.819. The calibration curves showed optimal agreement between nomogram prediction and actual observation. A high C-index value of 0.801 could still be reached in bootstrap validation. Application of the nomogram in the validation cohort showed good discrimination (C-index, 0.731) and good calibration. DCA demonstrated that the nomogram was clinically useful.

Conclusion:

The authors developed and validated a novel nomogram that can provide individual prediction of local complications within 90 days for patients after TKA. This practical tool may be conveniently used to estimate individual risk and help clinicians take measures to minimize or prevent the incidence of complications.

Novel radiographic hip fat thickness ratio correlates with early re-operation following total hip arthroplasty

INTRODUCTION

Obesity is thought to lead to increased failure rates following total hip arthroplasty (THA). Site-specific fat distribution has been suggested to be a better indicator of risk, compared to body mass index. Fat thickness measurement methods were developed for total knee arthroplasty, however, there is limited data on the methods for THA. The aim of this study was to assess the interobserver and intraobserver reliability of a newly defined radiographic subcutaneous fat thickness ratio and investigate the correlation of this ratio with early failure following THA.

METHODS

321 patients who underwent primary THA at a single institution between 2014 and 2017, with at least 1-year of follow-up and a preoperative pelvis anteroposterior x-ray radiograph were included in this study. A high hip fat thickness ratio (HFTR) was arbitrarily defined as ⩾2. Early failure was defined as revision or re-operation for any reason and death related to operation first year following THA.

RESULTS

The HFTR was shown to have excellent intraobserver and interobserver reliability. High HFTR was associated with higher risk of early failure following THA (odds ratio 3.8, [95% confidence interval, 1.2-12.1], p < 0.05). The same association persisted when HFTR was analysed as a continuous variable (p < 0.01) and in multivariate analysis (p < 0.05).

CONCLUSIONS

HFTR can be used to assess periarticular soft tissue distribution and may be regarded as a useful and reproducible tool for assessing risk of early failure following THA.

Obesity Increases Risk of Failure to Achieve the 1-Year PROMIS PF-10a Minimal Clinically Important Difference Following Total Joint Arthroplasty

INTRODUCTION

The aims of this study were to determine if increasing body mass index (BMI) is a risk factor for failure to attain the 1-year Patient Reported Outcomes Measurement Information System Physical Function (PROMIS PF-10a) minimal clinically important difference (MCID) following total joint arthroplasty (TJA) and to determine a possible BMI threshold beyond which this risk increases significantly.

METHODS

This retrospective study was performed using 3506 TJAs sourced from a regional-based registry. An anchor-based MCID threshold of 7.9 was chosen. PROMIS PF-10a scores were collected at the preoperative and 1-year postoperative timepoints, and the change was used to determine failure to achieve the 1-year MCID. Demographic and surgical variables were also collected. The association between BMI and failure to achieve 1-year PROMIS PF-10 MCID was then evaluated using logistic regression. A BMI threshold was determined using receiver operating characteristic (ROC) curve analysis.

RESULTS

Increasing BMI assessed continuously was a significant risk factor for failure to achieve the MCID (P < .001). "Obese Class I" (30-35 kg/m²), "Obese Class II" (35-40 kg/m²), and "Obese Class III" (>40 kg/m²) subgroups compared to "Normal BMI" (<25 kg/m²) were significantly associated (P < .05) with this adverse outcome as well.

CONCLUSION

Our study showed that increasing BMI is a risk factor for failure to achieve the 1-year PROMIS PF-10a MCID following TJA. Among our patients, an increase in 1 kg/m² increased the risk of failure to achieve the MCID by 2%. With these findings, surgeons will be better equipped to preoperatively advise patients with elevated BMIs considering TJA.

Modular Tibial Stem Use and Risk of Revision for Aseptic Loosening in Cemented Primary Total Knee Arthroplasty

BACKGROUND

Modular tibial stem extensions in total knee arthroplasty (TKA) are designed to reduce the risk of aseptic loosening of the tibial base plate. However, these implants add significant cost and an evaluation of their effectiveness in reducing this risk of loosening has not been studied in a large cohort. We sought to evaluate modular tibial stem utilization in primary TKA.

METHODS

We conducted a cohort study using our integrated healthcare system's Total Joint Replacement Registry. Patients who underwent cemented primary TKA were identified (2009-2019). Propensity scores were used to 1:1 match patients without to those with a stem extension. Cox proportional-hazards regression was used to evaluate the risk for revision due to aseptic loosening.

RESULTS

Ten thousand four hundred seventy six TKA with a modular tibial stem were matched to 10,476 TKA without a tibial stem. Stem utilization associated with a lower risk of revision for loosening across all postoperative follow-up (hazard ratio = 0.38, 95% confidence interval = 0.17-0.85).

CONCLUSION

In a matched cohort study, we observed presence of a stem extension was associated with a lower risk of revision for aseptic loosening. Further study to identify specific risk factors for aseptic loosening and confirm the findings presented here are warranted.

LEVEL OF EVIDENCE

Level III.

The relationship between obesity and primary Total Knee Replacement: A scoping review of the literature

BACKGROUND

Primary Total Knee Replacement (TKR) is one of the most commonly performed elective orthopaedic procedures globally. Many patients undergoing this type of surgery are overweight or obese. In the UK, clinical commissioning groups have imposed arbitrary Body Mass Index (BMI) thresholds for TKR surgery. Many obese patients undergoing TKR believe they will lose weight following the procedure because of increased mobility.

AIM

This paper aims to present the findings of a scoping literature review about the relationship between obesity and primary TKR and to make recommendations for clinical practice, education and policy.

METHODS

A scoping literature review investigated the impact of BMI/body weight on the need for TKR, the impact of body weight and or BMI on patient outcomes following TKR, weight loss/gain following TKR and the implications of obesity on cost of TKR.

FINDINGS

Seventy-one papers were included in the review. Seven studies reported statistically significant associations between increased BMI/obesity with the need for TKR. Thirty of the studies reported worse outcomes for obese patients compared to non-obese comparisons. Forty of the studies reported no difference between obese and non-obese participants, including some where outcomes of obese patients were better than non-obese comparisons. Eight studies reported on changes to weight before and after TKR, three of the studies reporting a higher percentage losing weight than gaining weight and four studies reporting that obese patients gained weight. The 8th study reported that morbidly obese patients largely returned to their baseline BMI postoperatively.

CONCLUSION

The findings of the review challenge the legitimacy of setting BMI thresholds to control access to TKR surgery. There is an urgent need to develop evidence based approaches to support weight loss and weight management for this group of patients. Obese patients undergoing TKR should receive specific information regarding potential additional risks of complications and poorer outcomes. There is a need for health promotion regarding the association of being overweight/obese in young adulthood and developing osteoarthritis of the knee joints requiring TKR in middle and older age.

Gender Differences in Contribution of Smoking, Low Physical Activity, and High BMI to Increased Risk of Early Reoperation After TKA

BACKGROUND

The reliable preoperative identification of patients at a high risk of early reoperations (<2 years after primary surgery) after total knee arthroplasty (TKA) could lead to adjustments of the surgical procedure and counseling, thus lowering the percentage of revision surgeries.

METHODS

The unselected cohort consisted of 1885 patients (695 men and 1190 women) who underwent TKA implantation between September 2010 and April 2017 at a single tertiary orthopedic center. Multivariate patient similarity networks were applied to identify patient groups at a high risk of early reoperations based on 25 preoperative parameters.

RESULTS

Early reoperations (109 cases, 5.8%) were less frequent in women (4.4%; median time to reoperation, 2.0 months) than in men (8.2%; 7.5 months), reaching the highest incidence in younger men (10.9%; <66 years). Of the tested preoperative parameters, the risk of reoperation in men was more likely associated with smoking or obesity (body mass index [BMI] > 30). In women, low physical activity and high BMI were the most likely risk factors for early reoperations. Other factors did not affect the risk of early reoperations, including the primary diagnosis, comorbidities, and surgeon-implanting TKA.

CONCLUSION

This study demonstrates the effect of smoking, physical activity, and BMI on the risk of early reoperation after TKA, with the different contribution in men/women. Identification of patient subgroups with a higher risk of early revision after TKA is needed for clinical implementation of precision medicine in orthopedics.

A simple nomogram for predicting early complications in patients after primary knee arthroplasty

BACKGROUND

This study sought to construct a nomogram for patients based on preoperative and intraoperative variables to individually predict the likelihood of complications within 30 days after primary knee arthroplasty.

METHODS

Data were obtained from the medical record of patients who underwent primary knee arthroplasty at our institution from 2015 to 2018. Preoperative and intraoperative factors were collected critically. Predictor variables include 15 common complications occurring within 30 days. The predictive model was developed using multivariable logistic regression and least absolute shrinkage and selection operator regression. Clinical usefulness and calibration of the predicting model were assessed using C-index, calibration plot, receiver operating curve, and decision curve analysis. Internal validation was assessed using the bootstrapping validation.

RESULTS

The prediction nomogram identified six variables associated with complications, including hemoglobin, tourniquet time, operative time, estimated intraoperative blood loss, American Society of Anesthesiologists Classification (ASA class) and type of anesthesia. The model displayed good discrimination with a C-index of 0.822 (95% confidence interval: 0.760-0.884), an area under the curve of 0.822 and good calibration. High C-index value of 0.810 could still be reached in the interval validation. Decision curve analysis showed that the nomogram was clinically useful when intervention was decided at the complications possibility threshold in the three percent to 100% range.

CONCLUSION

We constructed and validated a nomogram for predicting the probability of postoperative complications within 30 days after primary knee arthroplasty. Our nomogram may prove to be a useful tool for guiding physicians in terms of their decisions.

Diagnosis and management of implant debris-associated inflammation

Introduction: Total joint replacement is one of the most common, safe, and efficacious operations in all of surgery. However, one major long-standing and unresolved issue is the adverse biological reaction to byproducts of wear from the bearing surfaces and modular articulations. These inflammatory reactions are mediated by the innate and adaptive immune systems.Areas covered: We review the etiology and pathophysiology of implant debris-associated inflammation, the clinical presentation and detailed work-up of these cases, and the principles and outcomes of non-operative and operative management. Furthermore, we suggest future strategies for prevention and novel treatments of implant-related adverse biological reactions.Expert opinion: The generation of byproducts from joint replacements is inevitable, due to repetitive loading of the implants. A clear understanding of the relevant biological principles, clinical presentations, investigative measures and treatments for implant-associated inflammatory reactions and periprosthetic osteolysis will help identify and treat patients with this issue earlier and more effectively. Although progressive implant-associated osteolysis is currently a condition that is treated surgically, with further research, it is hoped that non-operative biological interventions could prolong the lifetime of joint replacements that are otherwise functional and still salvageable.

Weight and height separated provide better understanding than BMI on the risk of revision after total knee arthroplasty: report of 107,228 primary total knee arthroplasties from the Swedish Knee Arthroplasty Register 2009-2017

Background and purpose - Obesity defined as increased BMI is commonly associated with higher revision rates following total knee arthroplasty (TKA). We examined the effect of BMI on the rate of revision after TKA, for both infection and other reasons, and analyzed weight and height separately to provide better understanding of the risk profile.Patients and methods - The Swedish national knee arthroplasty register was used to identify 107,228 patients operated with primary TKA for osteoarthritis between 2009 and 2017. Cox proportional hazards regression was used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for BMI (categories: < 18.5, 18.5-24.9, 25-29.9, 30-34.9, 35-39.9, ≥ 40), weight (categories: < 65, 65-89, 90-114, ≥ 115 kg) and height (categories: < 160, 160-179, ≥ 180 cmResults - There were 2,503 revisions in the follow-up period; 1,036 for infection and 1,467 for other reasons. Higher BMI and weight categories were associated with a similar and statistically significantly increased risk of revision for all causes and for infection. The risk of revision for infection was almost twice in the highest BMI and highest weight group: HR = 3.4 (CI 2.3-4.7) and HR = 3.1 (CI 2.5-3.9) respectively. For BMI and weight categories there was no statistically significant association between revision for other reasons than infection, contrary to the tallest height category where it was statistically significant (HR = 1.3 [CI 1.1-1.5]).Interpretation - BMI, weight, and height may be associated with different types of risks for revision following TKA.