<p>Being Underweight Is Associated with Worse Surgical Outcomes of Total Knee Arthroplasty Compared to Normal Body Mass Index in Elderly Patients</p>

Abstract

Being underweight has never been studied in relation to the radiologic and clinical outcomes of total knee arthroplasty (TKA) in elderly patients. The aim of this study was to determine the effect of being underweight on TKA radiological and clinical outcomes and to investigate whether being underweight influences postoperative complications compared to normal body mass index (BMI) in elderly patients. Patients and Methods: A total of 118 female patients aged 65 years or older with BMI < 25 kg/m 2 who underwent primary TKA were divided into two groups based on BMI: group A: 18.5 kg/m 2 < BMI < 25 kg/m 2 ; group B: BMI < 18.5 kg/m 2. The radiologic and clinical outcomes were evaluated at follow-up of 6, 12, and 24 months after surgery such as the hipknee-ankle angle, the American Knee Society (AKS) score, Western Ontario and McMaster University score (WOMAC), and patellofemoral (PF) scale. Moreover, postoperative complications during follow-up were investigated. Results: Preoperative clinical scores did not differ significantly between the two groups. Postoperative WOMAC pain (1.8 ± 1.9 versus 3.4 ± 2.6, p = 0.02), WOMAC function (12.4 ± 8.1 versus 16.5 ± 8.5, p = 0.012) and PF scales (26.1 ± 3.6 versus 23.7 ± 4.1, p = 0.002) were worse in the underweight group at 12 and 24 months after surgery. The frequency of postoperative complications did not differ significantly between groups. In multivariate linear regression analysis, underweight patient group was significantly associated with worse postoperative WOMAC and PF scores (p = 0.002, 0.005). Conclusion: Although postoperative complications of TKA did not differ between groups, underweight patients had worse clinical outcomes of TKA compared to patients with normal BMI in elderly patients. Therefore, care should be taken when performing TKA in elderly underweight patients.

Underweight Body Mass Index Is Associated With Increased In-Hospital Complications and Length of Stay After Revision Total Joint Arthroplasty

“…16-18 More recently, underweight BMI has been identified as a predictor for mortality, increased complications, and increased length of stay after primary TJA. 19-23 Similarly, these findings were duplicated in a recent total shoulder arthroplasty study by Ottesen et al, 24 which demonstrated an increased risk of adverse events in underweight patients. To the authors' knowledge, this study is the first to identify underweight BMI as a risk factor for increased complications and length of stay after rTJA.…”

Impact of being underweight on peri-operative and post-operative outcomes of total knee or hip arthroplasty: A meta-analysis

“…A total of eighteen studies[ 10 , 11 , 19 - 34 ] were included in this review. Twenty-two eligible studies[ 4 , 35 - 37 ] were screened from a pool of 671 records identified from both electronic and manual searches, purely based on title and abstract.…”

“…Thirteen retrospective cohort studies[ 10 , 11 , 19 - 23 , 25 , 26 , 28 , 29 , 31 , 33 ] and five prospective cohort studies[ 24 , 27 , 30 , 32 , 34 ] were included. The studies included a total of 1136506 subjects undergoing TKA or THA with a mean age of 65.32 years.…”

“…Out of these recruited subjects undergoing TKA or THA, 213028 subjects were NW individuals with a BMI between 18.5 and 24.9, and only 10785 subjects were UW individuals with a BMI < 18.5. Sixteen studies[ 10 , 19 , 21 - 34 ] assessed the outcomes for THA and nine studies[ 11 , 19 , 20 , 23 , 26 , 28 , 30 , 31 , 33 ] for TKA. Only seven studies[ 19 , 23 , 26 , 28 , 30 , 31 , 33 ] presented data with both THA and TKA.…”

“…Sixteen studies[ 10 , 19 , 21 - 34 ] assessed the outcomes for THA and nine studies[ 11 , 19 , 20 , 23 , 26 , 28 , 30 , 31 , 33 ] for TKA. Only seven studies[ 19 , 23 , 26 , 28 , 30 , 31 , 33 ] presented data with both THA and TKA. The demographic characteristics of the included studies are provided in Table 2 .…”