Disclosure: The authors have no disclosures to report.
Musculoskeletal function following bariatric surgery
Article first published online: 13 MAY 2013
Copyright © 2013 The Obesity Society
Volume 21, Issue 6, pages 1104–1110, June 2013
How to Cite
Iossi, M. F., Konstantakos, E. K., Teel, D. D., Sherwood, R. J., Laughlin, R. T., Coffey, M. J. and Duren, D. L. (2013), Musculoskeletal function following bariatric surgery. Obesity, 21: 1104–1110. doi: 10.1002/oby.20155
- Issue published online: 26 JUL 2013
- Article first published online: 13 MAY 2013
- Accepted manuscript online: 6 NOV 2012 08:13AM EST
- Manuscript Accepted: 25 OCT 2012
- Manuscript Received: 26 OCT 2011
Bariatric surgery is an effective method for acute weight loss. While the impact of bariatric surgery on general medical conditions (e.g., type 2 diabetes) is well documented, few studies focus on physical functional outcomes following weight-loss induced by bariatric surgery.
Design and Methods
We report on 50 women aged 20-74 scheduled for Roux-en-Y gastric bypass (RYGB) procedure who were enrolled for a prospective 1-year study. Height, weight, and waist circumference were recorded preoperatively and at 6 and 12 months, postoperatively. To track musculoskeletal/physical function changes, the timed-get-up-and-go (TGUG) and short-form health survey-36 (SF-36) and short musculoskeletal function assessment (SFMA) questionnaires were administered.
Patients had significant weight loss and functional improvement. At 1 year mean weight loss was 48.5 kg and mean TGUG improvement was 3.1 s. SMFA and SF-36 also showed improvement in functional components with weight loss at 6 months and 1-year post surgery. Significant associations were observed between TGUG and SMFA measures at all time points. Final weight at 1 year post bariatric surgery was also significantly correlated with most functional outcomes and changes in these outcomes. Partial correlations controlling for age revealed additional associations between body weight and functional outcomes, especially at the 6-month visit.
Our results suggest that significant rapid weight loss, such as that attained by bariatric surgery, acutely improves musculoskeletal function in morbidly obese patients. Additionally, for patients with musculoskeletal disease or injury, weight loss resulting from bariatric surgery may serve as an adjunct for improving global functional outcome, and enhancing the rehabilitation potential.
Obesity is the second leading cause of preventable death in the United States (US)  and is associated with significant morbidity. The National Institutes of Health (NIH) defines overweight as a body mass index (BMI) of 25-29.9 and obesity as a BMI of at least 30 . With this definition, data from the most recent National Health and Nutrition Examination Survey (NHANES) indicated the 2005-2006 prevalence of obesity in the US to be 33.3% for men and 35.3% for women . Obesity is strongly associated with type 2 diabetes mellitus, coronary artery disease, and obstructive sleep apnea . Specifically, obesity has been implicated as a predictor of cardiovascular atherosclerosis independent of its effects on traditional risk factors [5, 6]. In addition, a BMI greater than 30 has been suggested to be associated with a 50-100% increased risk of death from all causes compared to individuals at a BMI of 20 to 25 . Clearly, obesity is associated with increased mortality and decreased general medical health.
In addition to its association with morbidity from general medical conditions, obesity is associated with decreased musculoskeletal function and joint related pain . Obese patients have greater impairments in instrumental activities of daily living (IADLs) and decreased walking performance compared with normal-weight groups . Obese patients also score lower on the physical component summary of the SF-36 as compared to normal weight patients . The prevalence of work-restricting musculoskeletal pain in the back, neck, hip, knee, and ankle as well as the percentage of people not working regularly is also higher in obese adult patients .
Obesity is a primary modifiable risk factor for osteoarthritis, with the relationship more clearly demonstrated for knee than for hip osteoarthritis . Studies also show an association between obesity and incidence of both total knee (TKA) and total hip arthroplasty (THA) for osteoarthritis, both in patients over and under 60 years of age [20, 21]. Morbidly obese patients (BMI > 40) also undergo TKA and THA 13 and 10 years earlier than normal weight (BMI < 25) patients, respectively . Again, these associations are stronger for knee than for hip replacement (40).
Treatment options for obesity include lifestyle modifications, pharmacotherapy, and surgical weight loss (bariatric surgery). Lifestyle modifications, including diet, exercise, and behavioral modification, are the first recommendations for weight loss and are successful for many patients, with typical weight loss of 0.5 kg week−127. The addition of exercise and/or pharmacotherapy increases the likelihood of long-term success [3, 23]. Surgical weight loss has become an increasingly common treatment option, when nonoperative measures are exhausted.
Bariatric surgery is generally reserved for morbidly obese patients who are unsuccessful with lifestyle modification and pharmacotherapy. Indications for bariatric surgery include BMI > 40 kg m−2 or BMI > 35 kg m−2 with serious comorbidities . Currently, the primary options for weight loss operations in the US include laparoscopic RYGB, laparoscopic adjustable gastric banding, and biliopancreatic diversion with duodenal switch (BPD/DS) [7, 25]. RYGB has been reported by many to be the gold standard and most common surgical procedure for weight loss in the U.S [7, 25]. Outcome studies have shown the RYGB to result in excess weight loss of 55-75% [7, 25, 26, 28].
While the impact of bariatric surgery on general medical conditions such as type 2 diabetes is well documented , few studies focus on physical functional outcomes following weight loss induced by bariatric surgery (39). The purpose of this study was to provide a baseline for musculoskeletal complaints and physical function in obese patients to investigate the musculoskeletal functional improvement over the course of 1 year following bariatric weight loss surgery. Results of this study are helpful in augmenting current treatment algorithms for planning elective surgery in the obese. Applications for these findings include identifying plausible minimum timing between bariatric and musculoskeletal surgery designed to improve physical function in this patient population, and predicting improvement in physical function in people not currently being treated for a musculoskeletal condition.
Methods and Procedures
Fifty patients scheduled for the RYGB were prospectively enrolled. Additional study inclusion criteria included female sex, age 20 or older, and no history of previous bariatric surgery. An explanation of the study was given and informed consent was obtained at the time of enrollment. All procedures were reviewed by the local Institutional Review Boards, and study approval was obtained.
Of the 50 patients initially enrolled, three were excluded, leaving 47 study patients. Two of the excluded patients cancelled surgery altogether and the other selected an alternate bariatric procedure.
Subjects were evaluated 2 weeks preoperatively, as well as at target 6 and 12 months postoperatively. Height, weight, and waist circumference were recorded at each visit. To track musculoskeletal and physical function changes, the TGUG, SF-36 questionnaire, and SMFA questionnaire were administered at each visit.
Roux-en-Y procedure (RYGB)
RYGB is a primarily restrictive procedure and is the most common weight loss operation performed in the US [7, 25, 26, 28]. The purpose is to impart a change in appetite and feeling of early satiety resulting in decreased food intake. The method used in the current study includes creation of a small gastric pouch ( cm3) by dividing and stapling the proximal stomach. The jejunum is then divided about 50cm distal to the ligament of Treitz. The distal limb is brought up and connected to the gastric pouch creating a gastrojejunostomy. The proximal limb of the jejunum (the biliopancreatic limb) is anastamosed in a side-to-side fashion to the distal jejunum forming a jejunojejunostomy ∼150 cm distal to the gastrojejunostomy. Weight loss in the first year is generally rapid and close follow-up to minimize protein malnutrition and vitamin deficiencies is mandatory.
Somatic and functional assessments
Participants were measured for body weight, height, and waist circumference during their preoperative, 6- and 12-month clinical visits. BMI was computed as kg m−2.
Short-form health survey-36 (SF-36)
The SF-36 is a measure of functional outcomes using eight dimensions of function-related health. Dimensions included are bodily pain, vitality, physical functioning, role limitation attributable to physical health problems, general health, role limitation attributable to emotional problems, mental health, and social functioning. These scales also form two summary measures: the mental component summary and the physical component summary. The summary scores are standardized and range from zero to 100 points, with high scores indicating better function. There are 36 questions on the form and the time required for administration is ∼5-10 min.
Short musculoskeletal function assessment (SMFA) questionnaire
The SMFA questionnaire contains two parts: the bother index and the dysfunction index. The bother index has 12 items that allow patients to assess how much they are bothered by problems in broad functional areas, such as recreation and leisure, sleep and rest, work, and family measured on a five-point scale. Response format ranges from one point (not at all bothered) to five points (extremely bothered). There are 34 items in the dysfunction index which assesses the patients' perception of their functional performance (nine items assess how often the patients have difficulty when performing certain functions and the other 25 items assess the amount of difficulty that patients have when performing certain functions). The items are grouped into four categories: emotional status, mobility, daily activities, and function of the arm and hand. Each item has a five-point response format, ranging from one point for good function to five points for poor function.
Scores for the dysfunction index and the bother index are calculated by taking the sum of the responses and converting these scores, so that they range from zero to 100, with use of the formula: ([actual raw score − lowest possible raw score]/possible range of raw score) × 100. High scores indicate poor function. Unanswered items within a category for the dysfunction index are replaced with the individual's mean score for that category, unless fewer than 50% of items within the category were answered. For the bother index, substitution with the mean is not allowed as each item addresses a specific functional area. There are a total of 46 questions on the SMFA.
The timed “get-up-and-go” test (TGUG)
The TGUG is a validated test of balance and function. Subjects complete a sequence of movements and are observed for deviation from a confident, normal performance. The subject starts seated in a chair, rises and walks 3 m, turns without assistance, and then walks back to the chair, turns, and sits down. Time to complete the task is recorded. There is no formal training before administration. TGUG was administered during physical examinations for each patient preoperatively as well as at 6 months and 1 year following surgery.
Of the 50 patients prospectively enrolled for the study 3 were excluded, with 2 patients canceling surgery altogether and 1 selecting an alternate bariatric procedure. For the 47 women undergoing RYGB the average age at the time of surgery was 46.85 years (range: 20-74). One of the 47 patients died of an acute myocardial infarction 7 weeks postoperatively resulting in a mortality rate of 2.1%. Of the remaining 46 patients, 33 (72%) completed the target 6-month follow-up. Five of these patients were completely lost to follow-up with eight patients following up at a later date. Thirty-nine (85%) completed the 1-year evaluation leaving seven patients lost at final follow-up.
Secondary surgeries were reviewed for all the patients during the 1-year follow-up period. Thirteen patients had a total of 24 procedures in the follow-up period. Five of the subjects required esophagogastroduodenoscopy (EGD) in the 1-year postoperative period. Two of these five had a single procedure and three of the five had a total of 14 EGD procedures. Indications were for evaluation of abdominal pain, nausea/vomiting, and possible obstruction. Dilation was performed on two of the patients. Three patients underwent laparoscopic cholecystectomy 9-12 months after bariatric surgery; three patients had hernia surgery 8-11 months after their bariatric procedures; one had a lumbar discectomy 7 months after the bariatric procedure; and one patient had surgery for a ruptured ovarian cyst 12 months after bariatric surgery.
Body size and functional characteristics of subjects at the preoperative, 6-month, and 1-year visits are presented in 1. On average, 1 year after bariatric surgery, subjects lost 48.5 kg of body weight (range: −62.11 kg to −15.61 kg), and reduced their BMI by 17.9 U (37%). In terms of function, subjects improved in TGUG by 3.1 seconds (range: −11.0 to +3.19 s), improved in SMFA functional score by 28.5 points, and improved in SF-36 physical component score by 15.2 points. The SMFA bother score improved by 23.8 points and the mental component of the SF-36 improved by 3.1 points. With the exception of the SF-36 mental component summary, all 1-year improvements from baseline were statistically significant (1).
|Presurgical characteristics||6-Month follow-up characteristics||1-Year follow-up characteristics|
|Mean (SD)||Range||Mean (SD)||Range||Mean (SD)||Range|
|Weight (kg)||133.68 (28.59)||98.00-214.91||93.25 (18.04)a||64.70-150.76||84.98 (17.16)a, b||53.81-126.76|
|Height (cm)||164.72 (5.99)||154.94-177.80||–||–||–||–|
|Waist (cm)||128.67 (16.50)||99.00-175.00||98.41 (13.56)a||73.66-130.00||95.21 (14.81)a, b||65.0-122.0|
|TGUG (sec.)||12.64 (3.12)||8.75-20.78||10.27 (2.35)a||6.62-18.47||9.60 (2.68)a, b||6.13-20.30|
|SMFA-Bother||37.80 (20.03)||2.08-87.50||20.50 (18.56a)||2.08-66.67||16.74 (17.94)b||2.08-70.83|
|SMFA-Function||52.40 (19.92)||13.00-99.00||27.43 (18.64a)||9.00-77.50||24.58 (20.63)b||9.00-99.00|
|SF-36 Physical||30.07 (9.14)||17.12-51.97||48.89 (9.49)a||26.72-68.02||45.85 (11.44)b||17.12-60.49|
|SF-36 Mental||48.97 (12.44)||14.06-65.31||51.79 (11.36)||24.45-64.43||52.50 (9.82)||26.20-63.32|
|BMI (kg m−2)||48.96 (8.26)||37.01-72.02||34.22 (5.28)a||25.26-47.67||31.13 (5.09)a, b||21.01-40.09|
With regard to change over time during the study period, improvement was recorded at each postoperative visit, peaking at 1 year, for weight, BMI, TGUG, and both SMFA bother and function components. These changes were statistically significant for weight loss, change in BMI, and improvement in TGUG at 6 and 12 months and for SMFA bother and function at 6 months. In contrast to the continuous improvement seen for the above parameters, the score increase for the physical component score of the SF-36 peaked at 6 months. While the 1-year score declined slightly from the 6-month peak, improvement over preoperative and 3-month values was maintained. All changes in SF-36 physical component score were statistically significant. The SF-36 mental score showed no significant change at any time point during the follow-up period.
Because of a known relationship between performance on TGUG and age, outcome data were also analyzed by age group with patients divided into four groups: 30 years of age and younger, 30 to 40 years of age, 40-50 years of age, and 50 years of age and older. There were no differences between age groups in body size and physical characteristics at the presurgical visit (one-way ANOVA; P > 0.05), nor were there differences between age groups in terms of mean body weight or physical characteristics at 6 months or 1-year post surgery (one-way ANOVA; P > 0.05).
With regard to TGUG, subjects in each age group improved by approximately the same amount on average (Figure 1). There was an obvious trend for age both preoperatively and at 1-year follow-up, with younger subjects performing better (faster) than older subjects. Improvements were also observed in each age group for both functional components of the SMFA and SF-36 (paired-sample t test; P < 0.05) (Figures 2 and 3). For each age group, the majority of SMFA function improvement occurred by 6 months, with a much smaller degree of improvement occurring between 6 months and 1 year. There was no increase (worsening) of scores between 6 months and 1 year in any age group. Similarly, the SF-36 physical component scores showed the majority of improvement by 6 months, but as opposed to the SMFA trend, a small decline in scores (worsening) between 6 months and 1 year was demonstrated. Therefore, as seen for the overall study population, the decline in the physical component score of the SF-36 after 6 months was also observed within each age group (Figure 1-5).
Significant improvement was also observed in each age group for the bother component of the SMFA with most of the improvement occurring by 6 months (paired-sample t test; P < 0.05) (Figure 4). (Note: Because at least one question was left blank in the bother section of SMFA in all subjects (n = 3) of the “under 30” group, no data are presented for that group). Although some improvement was indicated for each age group in the mental component of the SF-36, statistical significance was not reached (Figure 5).
To evaluate relationships between weight loss and functional outcomes, Pearson product moment correlation analyses were conducted. Additionally, to address the effects of age on measures of function, partial correlations were also analyzed controlling for age.
At the preoperative clinical visit, correlations between body weight and the outcome measures from the SF-36 and SMFA forms were not significant. TGUG and the SF-36 outcomes were also not significantly correlated. However, TGUG was correlated with each of the SMFA scores (2). The same results were found when partial correlations controlling for age were examined (3).
|Presurgical||6-Month follow-up||1 Year follow-up|
|Weight||TGUG||Weight||weight Δ||TGUG||TGUG Δ||Weight||weight Δ||TGUG||TGUG Δ|
|Presurgical||6-Month follow-up||1 Year follow-up|
|Weight||TGUG||Weight||weight Δ||TGUG||TGUG Δ||Weight||weight Δ||TGUG||TGUG Δ|
By 6 months postbariatric surgery, weight loss and TGUG each showed significant relationships with the questionnaire outcome measures. Weight loss was significantly correlated with improvement in SMFA Function and improvement in SMFA bother. TGUG and improvement in TGUG were both significantly correlated with SMFA outcome scores.
When these relationships were examined in light of the role of age (partial correlations controlling for age), results for TGUG correlations were similar but not identical to the standard Pearson correlation results. However, with age in the model, the relationship between body weight and the functional and mental outcome measures became very clear. Weight at 6 months postbariatric surgery was significantly correlated with all outcome measures from the SF-36 and SMFA, as well as change in SMFA Function score. Weight loss was significantly correlated with improvement in SMFA Function and bother. TGUG, while maintaining a significant relationship with all SMFA scores, was also significantly correlated with the SF-36 physical component score. When age is controlled for, change in TGUG was only significantly correlated with SMFA Function.
At 1 year post bariatric surgery, the pattern of these relationships remains. Body weight correlated significantly with the SF-36 physical component score and improvement in SF-36 physical component score in addition to the SMFA Function and bother scores. The amount of weight lost at 1 year was significantly correlated with the SMFA bother score, as well as improvement in the SMFA function and other scores. TGUG correlated significantly with SF-36 mental score and each of the SMFA outcome measures as well as improvement in each of the SMFA measures.
When age is accounted for in these relationships at the 1-year postsurgery visit, body weight correlates significantly with each of the SMFA outcome measures. Weight loss is correlated with SF-36 physical component score and change in physical component score, as well as change in each of the SMFA scores. TGUG is significantly correlated with the SF-36 mental score and each of the SMFA outcome measures.
Increasing rates of obesity in the US have led to more Americans with comorbid medical conditions (type 2 diabetes, cardiovascular disease, etc) as well as reduced functional abilities for activities of daily living . Many of these consequences of obesity can be reversed with significant weight loss by nonsurgical or surgical means. The present study shows that RYGB weight loss surgery results in significant weight loss at 1 year as well as improvement in musculoskeletal function as measured by SF-36, SMFA, and TGUG. The RYGB procedure was chosen for this investigation because it has the most predictable course of weight loss which allowed us to track improvement in physical function with weight loss [7, 25, 26, 28]. Specifically, a meta-analysis by Buchwald et al., reported 2,742 patients undergoing RYGB to have a mean absolute weight loss of 43.48 kg and a mean BMI reduction of 16.70 kg m−2 . Worth noting is that weight loss with RYGB peaks at 12-16 months and continues up to 1.5-2 years . Complications from the RYGB were manageable and were corrected. The 1-year mortality of 2.1% was in line with that reported in the literature.
We have shown that physical function improves following substantial rapid weight loss after RYGB in obese women (2, Figures 2-5). Statistically significant improvements were observed in TGUG, SMFA function and bother scores, and SF-36 function scores at 6 months and 1 year. While moderate improvements were observed in the SF-36 mental component, statistical significance was not achieved.
Possible limitations of the current study are that it focused only on patients undergoing RYGB surgery, and lack of a control group in the study design. Different results may be expected in patient groups undergoing alternative methods for weight loss, including nonsurgical weight loss and other surgical methods (including gastric banding). Additionally, we excluded men from the study, and therefore our results cannot be extended to both sexes, nor can we comment on potential sex differences in functional outcomes following bariatric surgery.
While the present study did not focus on joint-specific pain, the findings may have implications for decisions and timing regarding musculoskeletal surgery, particularly lower extremity reconstructive surgery. Obesity is a primary modifiable risk factor for the development of osteoarthritis and is associated with the need for total joint arthroplasty (TJA), particularly at the knee . Our results indicate that RYGB is an effective form of weight loss in morbidly obese patients resulting in a 1-year mean loss of 48.5 kg and 30% mean reduction in BMI. While this is short-term data, studies have indicated weight loss results to be sustainable long-term with excess weight loss of 56% maintained at 7 years . In addition, while there is conflicting literature [32, 33], many studies find that obesity is associated with an increased risk of complications, particularly infection, following musculoskeletal surgery . Thus, acute weight loss in the morbidly obese patient, via surgical or non-surgical means, may improve musculoskeletal surgery outcomes in multiple ways, including reduction in complications and increased success of recovery and rehabilitation following TJA surgery.
It is possible that weight loss prior to reconstructive surgery would improve functional outcome, as our results show improved physical function following RYGB. Minimally, this would make rapid significant weight loss, such as that observed after bariatric surgery, a potential adjunct to reconstructive surgery for improvement of pain and function in the obese patient. In addition, such weight loss may augment postoperative rehabilitation as obesity has been demonstrated to have a negative impact on inpatient rehabilitation following hip and knee arthroplasty .
In conclusion, the current study showed improvement in physical functioning of obese patients 1 year after RYGB bariatric surgery. The majority of the improvement occurs in the first 6 months. When considering reconstructive surgery on obese patients, it is prudent to recommend weight loss as a means of improving physical function with or without surgery. If the patient is undergoing weight loss surgery, we recommend waiting 6 months for reconstructive surgery to maximize the functional benefits of the weight loss, as functional improvements should lead to improved surgical outcomes.
We thank John P. Maguire, M.D., and Kim Hedgecorth, C.M.A., for their cooperation and guidance.
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- 3Center for Disease Control. Centers for disease control and prevention: overweight and obesity [Internet]. Atlanta (GA): Division of Nutrition, Physical Activity and Obesity, National Center for Chronic Disease Prevention and Health Promotion. Cited 2008 Sept 23. Available at: http://www.cdc.gov/nccdphp/dnpa/obesity.
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- 15Risk factors for the development of osteoarthrosis of the knee. Clin Orthop Relat Res 1990;261:242-246.,