Letter to the Editor on “A Longitudinal Analysis of Weight Changes before and after Total Knee Arthroplasty: Weight Trends, Patterns, and Predictors”

The investigators conducted a 2-year longitudinal study of perioperative (1-year preoperative and 1-year postoperative) bodyweight changes in a large sample of persons undergoing knee arthroplasty at an academic institution in the central United States.[1] Over a decade ago, we conducted a very similar knee arthroplasty weight change study,[2] also in a central U.S. academic center. Replication studies are important to confirm or refute prior findings, but it is important for the reader to be able to quickly find references of prior work that examined very similar questions. For reasons unknown, our prior knee arthroplasty paper was not referenced by the authors. They referenced a similar study we published on weight changes prior to and following hip arthroplasty[3] but did not reference the more relevant knee arthroplasty paper.[2]

The similarities between our earlier paper[2] and the paper by Oyem et al[1] are notable. Our focus was on the issue of clinically important 5% or greater weight gain prior to and following surgery as well as weight loss or gain prior to surgery, similar to the current paper. We used a 5% or greater weight gain up to 5 years following surgery as the clinically important outcome of interest, whereas the authors of the current paper used a 1-year postoperative period. Additionally, we compared our findings on patients with knee arthroplasty to a population-based nonarthroplasty sample from the National Institutes of Health funded Rochester Epidemiology Project based in Olmsted County, Minnesota, the home of Mayo Clinic and the site for our knee arthroplasty cases. We found that the odds of patients with knee arthroplasty gaining a clinically important amount of weight was odds ratio = 1.6, 95% confidence interval = 1.2–2.2, as compared with the population-based sample over the 5 years following surgery. Much like the study by Oyem et al, we also found that persons who lost the most weight prior to knee arthroplasty were at greatest risk for postoperative weight gain after adjustment for the other variables in the models. Unlike the study by Oyem et al, younger patients in our study were more likely to gain a clinically important amount of weight postoperatively compared with older patients. Another difference was that patients who gained weight during the 5 years prior to surgery in our study were not more likely to lose 5% or more bodyweight following surgery. Some of these differences were likely due to differences in study period. Ours was a 10-year study[2] (5-year preoperative to 5-year postoperative), whereas Oyem et al[1] conducted a 2-year study.

These two studies, when combined, offer some consistent messages, and carry greater impact than each study in isolation. While many patients maintain stable weight prior to and following knee arthroplasty, preoperative weight loss leads to postoperative weight gain and the greater the loss prior to surgery, the greater the gain following surgery. The authors echoed our recommendations for ongoing weight loss strategies following surgery, particularly for younger patients and those who lose weight prior to surgery. Patients with knee arthroplasty are more likely to gain a clinically important amount of weight as compared with the nonarthroplasty population.

Publication History

Accepted Manuscript online:
06 September 2024

Article published online:
04 October 2024

• References

• 1 Oyem PC, Rullán PJ, Pasqualini I. et al. A longitudinal analysis of weight changes before and after total knee arthroplasty: weight trends, patterns, and predictors. J Knee Surg 2024; 37 (08) 612-621
• 2 Riddle DL, Singh JA, Harmsen WS, Schleck CD, Lewallen DG. Clinically important body weight gain following knee arthroplasty: a five-year comparative cohort study. Arthritis Care Res (Hoboken) 2013; 65 (05) 669-677
• 3 Riddle DL, Singh JA, Harmsen WS, Schleck CD, Lewallen DG. Clinically important body weight gain following total hip arthroplasty: a cohort study with 5-year follow-up. Osteoarthritis Cartilage 2013; 21 (01) 35-43