Available online 2 December 2022

Author links open overlay panelAbstractBackground

Knee arthroplasty for knee arthritis is a commonly performed surgery yielding excellent functional results and good pain relief. It is associated with post-surgical complications according to the type of anesthesia and BMI class.

Methods

The National Surgical Quality Improvement Project database for the years 2005–2012 for patients >18 years of age who underwent knee arthroplasty, condyle and plateau, medial and/or lateral compartment. The surgical site complications, bleeding occurrences necessitating transfusion, unplanned readmissions, and mortality stratified according to anesthesia type and BMI class over a period of 30-days were examined.

Results

A total of 78,275 patients were included for analysis; regional anesthesia showed a consistent protective effect from surgical site complications more prominent with increasing obesity class with respective ORs and their corresponding 95% CI for pre-obesity, class I, II, and III obesity being 0.95 [0.89–1.09], 0.75 [0.68–0.83], 0.64 [0.57–0.72], and 0.61 [0.54–0.7].

Conclusions

Higher BMI values are a protective factor for the risk of bleeding requiring transfusion in patients undergoing total knee arthroplasty. Moreover, regional anesthesia is the preferred choice of anesthesia as well if postoperative complications are considered. A significant decrease in the rate of post-operative blood transfusions was seen in patients with high BMI and regional anesthesia.

Introduction

Knee arthroplasty is an increasingly common surgical intervention aimed at improving pain and function in patients with knee arthritis [1]. The risks of fatal or life-threatening events are increased several-fold after such a major surgery depending on patient characteristics and the type of anesthesia [2]. Obesity has been identified as an independent risk factor for the early development of osteoarthritis of the knee requiring joint replacement [3]. It is currently described as a global epidemic affecting more than 2 billion people worldwide which will logically also predict the need for more knee arthroplasty procedures [4]. Obesity is also considered the predecessor of several postoperative complications. However, we stumble upon conflicting results in the literature, whereby obesity does not appear to negatively influence the outcomes after knee surgery [5,6]. There are other factors we must be aware of that could affect the outcome of total knee surgery such as the choice of anesthesia and the complication profile expected of each [7]. Regional anesthesia has proven to reduce postoperative pain and opiate-related adverse effects along with facilitating rehabilitation which leads to its increased use [8]. However, it still has its inherent problems related to block failure rate, operating room delays, and operator reliability. Thus, a more individualized approach is required considering each patients characteristic and specific risks. Although multiple studies have evaluated the effect of obesity on total knee arthroplasty only a few have stratified patients according to BMI taking into consideration the type of anesthesia performed as well. Accordingly, the purpose of the following article was to study the effect of BMI on postoperative complications of patients undergoing knee arthroplasty using two different types of anesthesia. This study was conducted using the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) database.

Section snippetsMaterials and methods

We did a retrospective cohort study on all patients who have undergone knee arthroplasty reported in the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) database. The ACS-NSQIP is a surgical outcome database of hundreds of US and worldwide hospitals intended to study the risk of complications for surgical interventions [9]. It collects information related to preoperative risk factors, operative data, and 30-day postoperative outcomes of morbidity and

Results

A total of 78,275 patients fitting the inclusion were identified and divided according to BMI as follows: 11,649 Normal (14.9%), 19,012 Pre-Obesity (24.3%), 22,210 Class I obesity (28.4%), 14,180 Class II obesity (18.1%), and 11,224 Class III obesity (14.3%).

Descriptive statistics for the demographic and clinical characteristics of participants according to BMI category and anesthesia type are shown in Table 1. There is no statistically significant difference between the two anesthesia types

Discussion

In our current study, we assessed for differences in complication profiles between different BMI classes using general and regional anesthesia in knee arthroplasty patients. Our study population represents clinically similar samples between the different groups. There were statistically significant differences of race, age of patient, pre-operative BUN, pre-operative hematocrit, and albumin between general and regional anesthesia groups among all strata; however, these differences were of no

Financial disclosures

None.

Declaration of competing interst

None.

Acknowledgment

All authors have received no funding for this manuscript and have no conflict of interests to declare.

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