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Effects of Total Knee and Hip Arthroplasty on Body Weight Kyle R. Duchman, MD; Yubo Gao, PhD; Phinit Phisitkul, MD

abstract Full article available online at Healio.com/Orthopedics. Search: 20140225-61 Patients frequently report functional and subjective improvement following total hip (THA) and knee arthroplasty (TKA), but these improvements do not correlate with decreased body weight at 1- and 2-year follow-up. The purpose of this retrospective study was to investigate changes in body weight following THA and TKA at longer follow-up than the 1- to 2-year follow-up frequently reported in the literature. A retrospective review of patients undergoing THA and TKA, as well as other commonly performed lower extremity orthopedic surgeries, was completed for January 2002 to October 2011 at a single tertiary care facility. Adults who underwent a single lower extremity orthopedic procedure during that time period were included in the study. Patients undergoing THA and TKA were analyzed for clinically and statistically significant weight changes at 1- and minimum 2-year follow-up. At a mean follow-up of 4.82 years, TKA resulted in a statistically significant decrease in mean body weight (1.47 kg; P=.0109). This finding was unique to TKA. The proportion of individuals who experienced clinically significant weight loss between the 1- and minimum 2-year follow-up was higher than the proportion of individuals who gained clinically significant weight over the same time period following THA and TKA. The results of this study suggest that clinically significant weight loss may continue for several years beyond the 1- and 2-year follow-up that is frequently reported in the literature.

The authors are from the Department of Orthopaedics and Rehabilitation, University of Iowa Hospitals and Clinics, Iowa City, Iowa. The authors have no relevant financial relationships to disclose. Correspondence should be addressed to: Kyle R. Duchman, MD, Department of Orthopaedics and Rehabilitation, University of Iowa Hospitals and Clinics, 200 Hawkins Dr, 01008 JPP, Iowa City, IA 52242 ([email protected]). Received: April 2, 2013; Accepted: October 9, 2013; Posted: March 11, 2014. doi: 10.3928/01477447-20140225-61

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besity has continued to increase in prevalence over the past decade, affecting more than one third of the U.S. adult population according to the most recent National Health and Nutrition Examination Survey (NHANES) data.1 The prevalence of obesity appears to increase with age, peaking in the 6th and 7th decades of life.2 Such information is important to orthopedic surgeons because this age range coincides with the majority of patients who undergo total hip (THA) and knee arthroplasty (TKA).3,4 In addition, obesity is an independent risk factor for subsequent arthroplasty.5 Considering the demographic characteristics of patients undergoing arthroplasty, research has focused on the influence that preoperative body mass has on outcome following arthroplasty.6-8 Although the literature has failed to find a consistent correlation between preoperative body mass and postoperative outcomes, the improved functional and subjective outcomes consistently reported postoperatively do not correlate with weight loss.6-13 Currently, the majority of research on weight loss following orthopedic surgery has focused on THA and TKA. The literature has repeatedly revealed a trend toward postoperative weight gain, and studies have yet to reveal significant weight loss at 1- and 2-year follow-up despite the patient argument that improved postoperative function will aid in weight loss.6,9-15 These findings suggest that patients and surgeons should not expect weight loss or the associated cardiovascular and metabolic benefits of weight loss following total joint arthroplasty alone.10 However, such studies have failed to evaluate weight loss beyond 2-year follow-up. Such short-term follow-up may not allow enough time to adequately evaluate weight loss.13 The purpose of this study was to investigate weight change following THA and TKA for patients with a minimum 2-year follow-up at a large, tertiary care facility.

MARCH 2014 | Volume 37 • Number 3

Figure 1: Flow chart describing inclusion and exclusion criteria for total knee arthroplasty (TKA) and total hip arthroplasty (THA).

The authors’ goal was to determine how TKA and THA affect body weight at longer follow-up than previously reported in the literature while simultaneously evaluating nonmodifiable patient factors, including sex, age, and preoperative body mass index (BMI), that may influence body weight.

Materials and Methods Study Design This study was approved by the authors’ institutional review board prior to data collection and analysis. This retrospective cohort study aimed to investigate weight change following THA and TKA performed at a single tertiary care facility. The electronic medical record was queried from January 2002 to October 2011 to identify individuals who underwent THA or TKA while simultaneously identifying all individuals who underwent lower extremity orthopedic surgery for the purpose

of inclusion/exclusion criteria, including any of the following Current Procedural Terminology (CPT) codes: 26990-27299; 27301-27599; 27600-27899; 2985029916 and 29999. Children, defined as age younger than 18 years at the time of surgery, were excluded during the initial query, which returned 24,328 cases, including 681 THA (CPT 27130) and 888 TKA (CPT 27447) cases. Inclusion criteria beyond that of the initial query included follow-up at 3 time points, including preoperative and 1-year and minimum 2-year postoperative follow-up, primary procedure performed by an orthopedic attending, and a single surgery date for lower extremity surgery within the 10-year time frame of the study. Exclusion criteria included incomplete follow-up or incomplete data at follow-up, surgery performed by a nonorthopedic attending, bariatric surgery performed within the 10-year time frame

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tion are listed in Table 1 and referenced throughout the text for comparison when applicable.

Table 1

CPT Code Descriptions and Number of Procedures Performed CPT Code

Procedure Description

Abbreviated Description

Number

27447

Total knee arthroplasty

TKA

344

27130

Total hip arthroplasty

THA

294

29881

Arthroscopic meniscectomy

Menisc.

147

29888

Arthroscopic ACL reconstruction

ACL

85

27814

Open treatment bimalleolar ankle fracture

Bimal

42

27236

Open treatment femoral neck fracture

Fem Neck

36

29877

Arthroscopic knee chondroplasty

Chondro.

35

27244

Open reduction internal fixation peritrochanteric fracture

Peritroch.

34

27792

Open reduction internal fixation fibular fracture

ORIF Fib.

32

28296

Hallux valgus correction with metatarsal osteotomy

H. Valgus

31

Abbreviations: ACL, anterior cruciate ligament; CPT, Current Procedural Terminology.

Table 2

Demographics and Descriptive Statistics Procedure

TKA (n=344)

THA (n=294)

Male

121 (35.2)

123 (41.8)

Female

Sex, No. (%) 223 (64.8)

171 (58.2)

Obese, No. (%)

220 (64.0)

127 (43.2)

Age >65 y, No. (%)

164 (47.7)

130 (44.2)

Mean age at surgery, y

64.3

62.3

Mean preop weight, kg

92.4

87.2

Mean preop BMI, kg/m2

33

30.7

Min 2-year follow-up, y

4.82

4.71

Abbreviations: BMI, body mass index; min, minimum; preop, preoperative; THA, total hip arthroplasty; TKA, total knee arthroplasty.

of the study, and multiple lower extremity surgery dates within the queried time frame. These criteria yielded a total of 294 and 344 patients undergoing THA or TKA, respectively. The flowchart for this cohort can be seen in Figure 1. As part of the initial query, all lower extremity surgeries from January 2002 to

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October 2011 were identified for the purpose of excluding individuals who underwent multiple lower extremity surgeries in addition to THA or TKA. Although power prevented stratification of these lower extremity orthopedic surgeries, the 10 most frequently performed lower extremity orthopedic surgeries at the authors’ institu-

Weight Categories Preoperative BMI categories included normal weight (BMI,

Effects of total knee and hip arthroplasty on body weight.

Patients frequently report functional and subjective improvement following total hip (THA) and knee arthroplasty (TKA), but these improvements do not ...
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