1. Summary
Obesity has tripled globally since 1975. Excess body weight and obesity leads to increased joint loading, which stresses the articular cartilage beyond its biological reparative capabilities, resulting in subsequent joint failure. There is evidence that weight loss in overweight and obese persons can significantly reduce the risk of development of knee osteoarthritis (OA) and pain. On the other hand, it seems that the body mass index (BMI) is not in itself associated with the incidence and progression of hip osteoarthritis.
Performing surgery on overweight or obese patients increases the technical demands on the surgeon. Surgical exposure and implant positioning may be more challenging due to the volume of fat tissue precluding optimal visualisation of the surgical field. Moreover, perioperative complications such as infection, as well as overall in-hospital deaths, are more frequent in obese patients. The need for revision surgery after joint replacement also increases, since the risk of prosthetic loosening has been shown to increase with obesity. Weight loss prior to joint replacement surgery has been shown to reduce the length of hospital stay. However weight loss immediately before surgery, as an acute preoperative measure, may also have negative implications and increase the risk of complications. New policies and strategies combatting obesity have emerged and must be developed to incorporate considerations relating to musculoskeletal health and surgery.
2. Introduction
During the last century, technological developments in orthopaedic and trauma care have led to major benefits for patients. Many surgical procedures have a good outcome, but in order to improve the results further a focus on patient-related risk factors has become increasingly important. Obesity is one of these factors.
Obesity poses a major risk for serious non-communicable diseases. Obesity paradoxically coexists with undernutrition in a global perspective.
A person with a BMI of 30 or more is generally considered to be obese and a person with a BMI equal to or more than 25 is considered as overweight (WHO 2020). Apart from being a major risk factor for diabetes, cardiovascular disease and cancer, obesity and being overweight pose specific problems for the musculoskeletal system.
3. Epidemiology
The condition has tripled in prevalence since 1975. In 2016, more than 1.9 billion adults aged 18 or over were overweight. Of these, over 650 million were considered to be obese. (WHO obesity-and-overweight 2020). In the OECD area more than one in two adults and nearly one in six children are overweight or obese today (https://www.oecd.org/health/obesity-update.htm).
During recent years it has become clear that the obesity epidemic not only affects high-income countries, but is now also on the rise in middle- and low- income countries, particularly in urban contexts (WHO, obesity-and-overweight 2020). More than one in two adults and nearly one in six children are overweight or obese in the OECD area, as reported 2017 (OECD Obesity update 2017)
The level of BMI seen in children and adolescents has levelled off at high levels in high income countries, but is accelerating in Asia (NCD Risk Factor Collaboration 2017). This causes a health concern for future generations.
Prevalence of overweight among adults (>18 years) 1975-2016. (WHO risk factors/overweight 2020)
New policies and strategies combatting obesity have emerged and must include considerations of musculoskeletal health. The lifespan of obese persons is up to 8-10 years shorter (for a BMI of 40-45) than that of a normal-weight person, reflecting the same loss of life expectancy suffered by smokers. In some European countries the odds of disability, defined as a limitation in activities of daily living (ADL), are almost twice as high in the obese population compared to individuals of normal weight (OECD Health systems 2017).
4. Obesity and Joint Problems
a- Obesity and joint loading
Excess body weight and obesity leads to increased joint loading, which primarily affects load-bearing joints. This can stress the articular cartilage beyond its biological reparative capabilities, resulting in joint failure and osteoarthritis. The knee joint is particularly at risk. For example, it is estimated that a force of nearly 3 to 6 times one’s body weight is exerted across the hip and knee while walking; an increase in body weight of 1kg therefore increases the force acting on the joint by this factor – 3-6kg. (Felson DT et al. 1996, Bergmann G et al. 2007). Interestingly, being overweight has also been associated with higher rates of hand osteoarthrosis (OA) in some studies, suggesting the involvement of a circulating systemic factor as well as simple mechanical considerations (Carman WJ et al. 1994). Data from the first National Health and Nutrition Examination Survey (HANES I) indicates that obese women have nearly 4 times the risk of knee OA compared to non-obese women; for obese men, the risk was nearly 5 times higher (Anderson et al. 1988). Reijman et al. (2007) found, in a cohort study including more than 3500 patients, that increasing BMI is associated with a corresponding increase in the incidence and progression of knee osteoarthritis. On the other hand, however, it seems that BMI is not related to the incidence and progression of hip osteoarthritis.
There is evidence that weight loss in the overweight and obese can significantly reduce the risk of development of knee OA (Felson DT et al. 1992). In the Framingham study, Felson and colleagues noted that if obese men (BMI over 30) lost enough weight to fall into the overweight category (BMI 26-30) and men in the overweight category lost enough weight to move into the normal weight category (BMI less than 26), knee OA would decrease by 21.5%. Similar changes in weight category by women would result in a 33% decrease in the burden of knee OA. A handful of studies have indicated that weight loss substantially reduces reports of pain as well.
b- Metabolic syndrome
Obesity is often linked to metabolic syndrome. This condition includes the deposition of excess body fat around the waist, high blood pressure, high levels of blood sugar and high serum levels of triglycerides in parallel with low serum levels of high density lipoproteins. Cardiovascular diseases such as myocardial infarction and stroke, as well as type 2 diabetes, are common complications. Inflammation in the white adipose tissue is considered to be a crucial step contributing to the pathologies characterizing metabolic syndrome, as well as to atherosclerosis.
c- Worse outcomes after fracture surgery in patients with metabolic syndrome
There are conflicting data regarding the fracture risk in patients with metabolic syndrome compared to controls. This possibly reflects nutritional status and its importance to general health. Epidemiological studies have shown a lower fracture incidence in patients with metabolic syndrome (Yang L et al. 2016). However, patients with metabolic syndrome who sustain a hip fracture were found to have increased risk of complications but decreased odds of in-hospital mortality, again possibly due to nutritional status (Cichos et al. 2018). The surgical treatment for supination-external rotation ankle fractures (the most common variety) in patients with metabolic syndrome have shown worse clinical outcomes compared to controls (Park et al. 2019).
d- Obesity and Low Back Pain
Dario et al. (2017) found, in interesting studies involving sets of twins, that obesity-related measurements did not increase the risk of developing chronic Low Back Pain (LBP) or care-seeking for LBP. The results do not support a causal direct relationship between obesity and chronic LBP. On the other hand, familial factors such as genetics play a major role.
Somewhat different is the situation in juveniles, however. Studies by Samartzis et al. (2011) found that the presence of juvenile disc degeneration was strongly associated with being overweight and with obesity, LBP, increased LBP intensity and diminished physical and social functioning. Furthermore, an elevated BMI was significantly associated with increased severity of disc degeneration. This study has public health implications regarding being in the overweight or obese categories and the development of lumbar disc disease.
e- Obesity and outcome after joint replacement
Obesity increases the risk of joint failure with the subsequent need for joint replacement. Furthermore, the age at which arthroplasty of the hip and the knee was carried out was markedly lower for patients with a BMI over 35. This association was found to be stronger for knee than for hip replacement (Changulani et al. 2008). Barrett (2018) included eight studies in his review and there were 66238 THAs in morbidly obese patients and 705619 THAs in patients with a BMI < 30. The overall revision rate was higher, with 7.99% in the morbidly obese patients versus 2.75% in the non-obese controls. On the other hand, the functional outcome of arthroplasty was at least comparable to non-obese patients, so the rewards are maintained even if the risks are greater.
The need for revision surgery after joint replacement increases with obesity, particularly since the risk of prosthetic loosening has been shown to be higher in the obese (Electricwala et al. 2016, Goodnough et al. 2018).
5. Perioperative Challenges When Operating on Overweight and Obese Patients
Performing surgery on overweight or obese patients puts additional technical demands on surgeons. Surgical exposure and implant positioning may be more challenging due to the volume of fat tissue precluding optimal vision of the surgical field. Moreover, perioperative complications, such as infection and overall in-hospital deaths, are more frequent in obese patients (D’Apuzzo et al. 2015). Weight loss prior to joint replacement surgery has been shown to reduce the length of stay, which has implications on cost and patient burden (Keeney et al. 2019).
Despite the goal of normal weight, weight loss immediately before surgery as an acute preoperative measure may have negative implications on nutritional status. A catabolic state in the lead up to surgery may also increase the perioperative risks. It must always be kept in mind that obesity and nutritional status are not the same.
Conclusion
- •
Excess body weight and the global obesity epidemic pose risks for musculoskeletal health, adding to the already known suffering and costs stemming from metabolic and cardiovascular health problems.
- •
Increased joint loading due to obesity increases the risk of osteoarthritis.
- •
Subsequent weight loss in obese patients has been shown to reduce the risk of developing osteoarthritis apart from mitigating perioperative risks.
- •
Metabolic syndrome, often linked to obesity, has been shown to lead to worse clinical outcomes after fracture surgery.
6. List of Activities Needed
- •
EFORT needs to stimulate engagement in public health policy and strategies combatting the obesity epidemic.
- •
EFORT needs to support European orthopaedic and trauma surgeons in efforts to improve their knowledge on perioperative optimisation and rehabilitation of obese patients.
- •
The EFORT Foundation invites experienced institutes, as well as National and Speciality Societies, to share their experience and information material, descriptions of working routines and their web links to create a European data bank on the topic of obesity.
- •
EFORT aims to stimulate national authorities to support public health policies and strategies aimed at combatting the obesity epidemic and bringing the topic into public view via media.
7. References
Anderson J, Felson DT. Factors associated with osteoarthritis of the knee in the First National Health and Nutrition Examination (HANES I).
Am J Epidemiol. 1988;128:179–89. [
PubMed: 3381825]
Barrett K, Prasad A, Boyce L, Dawson-Bowling S, Achan P, Millington S, Hannaet S A. Total hip arthroplasty outcomes in morbidly obese patients A systematic review.
EFORT Open Rev. 2018;3(9):507–12. [
PMC free article: PMC6174856] [
PubMed: 30305935]
Bergmann G., Graichen, F., Rohlmann A., Westerhoff P., Bender A, Gabel U, Heinlein B. Die Belastung orthopädischer Implantate, Messungen und praktische Anwendungen: Der Orthopäde.
2007;36(3):195–204. [
PubMed: 17333070]
Carman WJ, Sowers M, Hawthorne VM, Weissfeld LA. Obesity as a risk factor for osteoarthritis of the hand and wrist: a prospective study.
Am J Epidemiol. 1994;139:119–29. [
PubMed: 8296779]
Changulani M, Kalairajah Y, Peel T, Field RE. The relationship between obesity and the age at which hip and knee replacement is undertaken.
J Bone Joint Surg Br. 2008;90(3):360–3. [
PubMed: 18310761]
Cichos KH, Churchill JL, Phillips SG, Watson SL, McGwin G Jr, Ghanem ES, Ponce BA. Metabolic syndrome and hip fracture: Epidemiology and perioperative outcomes.
Injury. 2018;49(11):2036–41. [
PubMed: 30236796]
Dario AB, Ferreira ML, Refshauge K, Luque-Suarez A, Ordoñana JR, Ferreira PH. Obesity does not increase the risk of chronic low back pain when genetics are considered. A prospective study of Spanish adult twins.
Spine J. 2017;17(2):282–90. [
PubMed: 27751965]
Dario AB, Ferreira ML, Refshauge K, Sanchez-Romera JF, Luque-Suarez A, Hopper JL, Ordonana JR, Ferreira PH. Are obesity and body fat distribution associated with low back pain in women? A population-based study of 1128 Spanish twins.
Eur Spine J. 2016;25(4):1188–95. [
PubMed: 26084786]
Electricwala AJ, Narkbunnam R, Huddleston III JI, Maloney WJ, Goodman SB, Amanatullah DF. Obesity is Associated With Early Total Hip Revision for Aseptic Loosening.
J Arthroplasty. 2016;31(S9):217–20. [
PubMed: 27108056]
Felson DT, Zhang Y, Anthony JM, Naimark A, Jennifer J, Anderson JJ. Weight Loss Reduces the Risk for Symptomatic Knee Osteoarthritis in Women: The Framingham Study.
Ann Intern Med. 1992;116(7):535–9. [
PubMed: 1543306]
Goodnough LH, Finlay AK, Huddleston III JI, Goodman SB, Maloney WJ, Amanatullah DF. Obesity Is Independently Associated With Early Aseptic Loosening in Primary Total Hip Arthroplasty.
J Arthroplasty. 2018;33:e882–e386. [
PubMed: 29089226]
Ezzati M., NCD Risk Factor Collaboration (NCD-RisC) (2017). Worldwide Trends in Body-Mass Index, Underweight, Overweight, and Obesity from 1975 to 2016: A Pooled Analysis of 2416 Population-Based Measurement Studies in 128.9 Million Children, Adolescents, and Adults.
Lancet. 2017;390:2627–42. [
PMC free article: PMC5735219] [
PubMed: 29029897]
Park YH, Kim W, Park JH, Kim HJ. Impact of metabolic syndrome on patient outcomes of supination-external rotation ankle fracture.
Injury. 2019;50(7):1388–91. [
PubMed: 31176479]
Reijman M, et al. Body mass index associated with onset and progression of osteoarthritis of the knee but not of the hip: the Rotterdam Study.
Ann Rheum Dis. 2007;66(2):158–62. [
PMC free article: PMC1798486] [
PubMed: 16837490]
Samartzis D et al. A population-based study of juvenile disc degeneration and its association with overweight and obesity, low back pain, and diminished functional status.
J Bone Joint Surg Am. 2011;93(7):662–70. [
PubMed: 21471420]
Yang L, Lv X, Wei D, Guo J, Zhang T. Metabolic syndrome and the risk of bone fractures: A Meta-analysis of prospective cohort studies.
Bone. 2016;84:52–6. [
PubMed: 26708924]
