The outcomes of total knee arthroplasty in morbidly obese patients: a systematic review of the literature

Abstract

IntroductionThe increasing prevalence of obesity has led to an increase in total knee arthroplasties (TKAs) being undertaken in patients with a higher body mass index (BMI). TKA in morbidly obese patients can be technically challenging due to numerous anatomical factors and patient co-morbidities. The long-term outcomes in this patient group are unclear. This systematic review aims to compare the long-term revision rates, functional outcomes and complication rates of TKAs in morbidly obese versus non-obese patients.MethodsA search of PubMed, EMBASE and PubMed Central was conducted to identify studies that reported revision rates in a cohort of morbidly obese patients (BMI ≥ 40 kg/m2) that underwent primary TKA, compared to non-obese patients (BMI ≤ 30 kg/m2). Secondary outcomes included Knee Society Objective Scores (KSOS), Knee Society Functional Scores (KSFS), and complication rates between the two groups. The difference in revision rates was assessed using the Chi-squared test. The Wilcoxon signed-rank test was used to compare pre-operative and post-operative functional scores for each group. KSOS and KSFS for morbidly obese and non-obese patients were compared using the Mann–Whitney test. Statistical significance was defined as p ≤ 0.05.ResultsNine studies were included in this review. There were 624 TKAs in morbidly obese patients and 9,449 TKAs in non-obese patients, average BMI values were 45.0 kg/m2 (range 40–66 kg/m2) and 26.5 kg/m2 (range 11–30 kg/m2) respectively. The average follow-up time was 4.8 years (range 0.5–14.1) and 5.2 years (range 0.5–13.2) respectively, with a revision rate of 7% and 2% (p < 0.001) respectively. All functional scores improved after TKA (p < 0.001). Pre- and post-operative KSOS and KSFS were poorer in morbidly obese patients, however, mean improvement in KSOS was the same in both groups and comparable between groups for KSFS (p = 0.78). Overall complication rates, including infection, were higher in morbidly obese patients.ConclusionsThis review suggests an increased mid to long-term revision rate following primary TKA in morbidly obese patients, however, these patients have a functional recovery which is comparable to non-obese individuals. There is also an increased risk of perioperative complications, such as superficial wound infection. Morbidly obese patients should be fully informed of these issues prior to undergoing primary TKA.

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

“…Obesity is considered a risk factor for both developing knee osteoarthritis (OA) and progression requiring TKA surgery at younger age (Changulani et al 2008, Singer et al 2018. Moreover, many studies have shown that morbid obesity is associated with increased risk of revision following TKA (Springer et al 2013, Roche et al 2018, Tohidi et al 2018, Boyce et al 2019. However, most of the studies report overall risk for revision without detailing reasons for revision.…”

“…However, most of the studies report overall risk for revision without detailing reasons for revision. The effect of obesity on revision besides an increased risk for periprosthetic joint infection (PJI) has not been thoroughly discussed in the literature (D'Apuzzo et al 2015, Wagner et al 2016, Jung et al 2017, Roche et al 2018, Boyce et al 2019. There might be a complex relation between weight and height, and TKA outcome.…”

Preoperative optimization to prevent periprosthetic joint infection in at-risk patients

“…41 Obesity is associated with a longer operation time, more postoperative complications, and higher revision rates. 42,43 It was shown by multiple studies that obesity increases the risk of PJI with odds ratios between 1.73 to 6.4. 33,44,45 Malinzak reviewed more than 6000 total joint arthroplasties and found the odds of PJI is 3.2 and 18.3 times in morbidly obese and extreme obesity patients (BMI greater 50 kg/m 2 ).…”

Perioperative Nursing Considerations for Patients Undergoing Total Hip or Knee Arthroplasty

“…Overweight patients may be at an increased risk for anesthesia‐related complications related to airway management and medication dosing . In addition, morbidly obese patients with a body mass index greater than 40 kg/m may experience complications (eg, superficial SSI, prosthetic implant infection) more frequently than nonobese patients …”