There has been a significant increase in obesity in the United States over the past 20 years. Reports in the literature identify the association of obesity-related osteoarthritis and the likelihood of future total hip arthroplasty (THA) and total knee arthroplasty (TKA) in this patient population. However, little is known about the effect of preoperative exercise on immediate postoperative mobility and discharge disposition in obese total joint replacement patients. The purpose of this study was to examine the effect of preoperative exercise in the obese total joint replacement patient on early postoperative mobility and discharge disposition.
We retrospectively reviewed a consecutive series of patients with a body mass index (BMI) >30 kg/m2 who underwent primary total joint replacement surgery from June 2005 through October 2005 at 1 institution. Two hundred seven patients met the inclusion criteria. Sixty-five patients performed self-reported preoperative exercise, defined as physical activity deemed above and beyond that of activities of daily living. Fewer exercise patients, 6.8%, required the assistance of >2 caregivers for mobility on postoperative day 1 vs 17.4% for nonexercisers. Fifty-four percent of patients participating in preoperative exercise were discharged home vs 46% who did not participate in exercise. A preoperative exercise program can improve postoperative functional mobility and increase the likelihood of discharge home in total joint replacement patients with a BMI of >30 kg/m2.
There has been a significant increase in obesity in the United States over the past 20 years. In 2008, only 1 state, Colorado, had an obesity rate <20%.1 The National Institutes of Health (NIH) guidelines define obesity as a body mass index (BMI) of >30 kg/m2 and morbid obesity as a BMI of >40 kg/m2.2 Body mass index is calculated by dividing the patients weight in kilograms by the square of the patients height in meters. Obesity is a health condition associated with an increased incidence of multiple medical comorbidities, including osteoarthritis. Reports in the literature identify the association of obesity-related osteoarthritis and the likelihood of future total hip arthroplasty (THA) and total knee arthroplasty (TKA) in this patient population.3-9
The anticipated benefits of reducing pain and improving function following joint replacement surgery should not overshadow discussion of potential perioperative and postoperative risks. Obese and morbidly obese patients pose challenges not only for the surgical team, but for the postoperative medical, nursing, and rehabilitation staff.10,11 Preoperative knowledge of the risks and benefits may prove invaluable to both surgeon and patient.
In 2006, Rooks et al12 reported on the effect of preoperative exercise on functional measures in men and women undergoing THA and TKA. Several authors report on hospital length of stay and discharge disposition in the obese patient population.5,7,10,13,14 However, less is known about the effect of preoperative exercise on immediate postoperative mobility and discharge disposition in obese total joint replacement patients. We hypothesize a decrease in assistance with postoperative mobility and an increase in patients discharged home with obese THA and TKA patients participating in a preoperative exercise program.
Materials and Methods
After institutional review board approval, we retrospectively reviewed a consecutive series of patients with a BMI of >30 kg/m2 who underwent primary THA or TKA between June 2005 and October 2005. These patients were selected from the hospital database. During this period, several orthopedic surgeons performed >300 THAs and TKAs on this patient cohort. Two hundred seven patients met the inclusion and exclusion criteria. Seventy-six patients received primary THAs and 131 patients received primary TKAs using a traditional, noncomputer-assisted surgical approach. All surgeries were elective procedures.
Fifty-eight percent of the patients (120) were women and 42% (87) were men. Mean patient age at the time of surgery was 63.1 years (range, 31-87 years). The principal diagnosis was osteoarthritis. One hundred patients had a BMI of >30 kg/m2 and 107 patients had a BMI of >40 kg/m2.
The inclusion criteria for patients participating in a preoperative exercise program included adult men and women between the ages of 30 and 90 years and an underlying diagnosis of osteoarthritis, rheumatoid arthritis, or traumatic arthritis that required a primary THA or TKA. The patients had a documented BMI of >30 kg/m2 during the preoperative screening process.
The inclusion criteria for the comparison group (patients who did not participate in a preoperative exercise program) were the same. Exclusion criteria included use of the minimally invasive capsular preserving surgical approach with THA, a computer-assisted procedure, and having bilateral joint replacement surgeries performed on the same day.
Patients deemed eligible following retrospective review of the medical records were consecutively assigned to either the preoperative exercise group or the group that did not partake in a preoperative exercise program. For purposes of this study, preoperative exercise was defined during the preoperative screening process as participation in physical activity deemed above and beyond that of the activities of daily living. There were no eligibility guidelines with respect to type of activity or intensity. Therefore, self-reported, preoperative exercise or activity programs varied in both type and level of participation. Preoperative, self-reported physical activities included, but were not limited to, biking, stretching, walking, swimming, water aerobics, low-impact aerobics, going to a health club, and participating in formalized outpatient physical therapy.
Postoperative surgical and rehabilitation protocols for primary THA and TKA were similar among the arthroplasty surgeons. Patients were allowed to bear weight as tolerated with an assistive device. Two surgeons allowed only partial weight bearing during the immediate postoperative period. The majority of THA patients observed posterior THA precautions, and active-assisted therapeutic exercises were initiated on the first postoperative day. At the time, there were slight differences with perioperative pain regimes among the surgeons, and 1 surgeon deferred continuous passive motion machine application until the first postoperative day with TKA patients.
Functional mobility is defined to include bed mobility, supine-to-sit transfers, and sit-to-stand transfers. A data collection sheet developed by the authors was used to extract information from the medical record during the retrospective review. The data collection sheet contained fields for demographic information, BMI, date of surgery, type of surgery/surgeon, discharge disposition, and amount of assist for functional mobility. The amount of assist for functional mobility was recorded on the first postoperative day in which the patient was mobilized with physical therapy.
The McNemar test, typically used to test 2 study proportions obtained from the same group of respondents, was used to evaluate postoperative functional mobility between the exercise and nonexercise group.15 The z-test for 2 proportions was used to compare discharge disposition.16
Obese and morbidly obese patients often require more staff assistance with postoperative mobility after joint replacement surgery.5,10 Fewer preoperative exercise patients, 6.8%, required the assistance of >2 caregivers for functional mobility on postoperative day 1 vs 17.4% for nonexercisers. This result was statistically significant (P=.0261) with a 2-tailed confidence level of 99.8%. Tables 1 and 2 show the progression of patients through postoperative day 4 who required the assistance of >2 caregivers. The postoperative protocol variance among surgeons did not affect the level of functional mobility between the 2 groups.
Discharge disposition, home vs rehabilitation facility, was assessed. Fifty-four percent of patients participating in preoperative exercise were discharged home vs 46% who did not participate in exercise. Z-test calculations showed the difference was not statistically significant (P=.3524).
Of patients requiring the assistance of >1 person for postoperative functional mobility, only 3 were discharged home. Home discharge in this cohort included 2 exercise patients receiving THAs and 1 nonexercise patient receiving a THA. No patients requiring increased assistance with mobility who underwent TKA surgery were discharged to home. No patients with a BMI >40 kg/m2 who required the assistance of >2 caregivers for functional mobility were discharged home.
In November 2007, the American Medical Association, in collaboration with the American College of Sports Medicine, introduced the Exercise Is Medicine initiative.17 Together, the 2 groups called on all physicians, regardless of specialty, to educate their patients on the importance of incorporating physical activity into their daily routines. The American Academy of Orthopaedic Surgeons shares in this initiative and posts a position statement on their website, The Need for Daily Physical Activity, which may be used by both patients and health care providers as an educational tool when considering an exercise program.18 We consider the Exercise Is Medicine initiative as a valuable preoperative component for all patients considering joint replacement surgery.
We conducted a retrospective study to examine the effect of self-reported preoperative exercise in the obese total joint replacement patient. We looked at the impact of preoperative exercise intervention on early postoperative functional mobility and discharge disposition. To our knowledge, this is one of the few studies to examine the potential benefits of preoperative exercise on obese and morbidly obese patients undergoing primary total joint replacement surgery.3,12
It was found that fewer patients who performed a self-reported exercise routine prior to joint replacement surgery required the assistance of >2 caregivers for immediate postoperative functional mobility. A caveat to consider when interpreting this finding is that self-reported, preoperative exercise programs varied in both type and level of participation amongst obese total joint replacement patients. All patients were provided the opportunity to report participation in preoperative exercise to a health care provider during the preadmission screening process, and the self-reported information was recorded as part of the medical record. However, some patients may have failed to consider their daily walk or stretching as exercise and therefore did not report it. A retrospective review of the medical record would then indicate the patient was a nonexerciser. No patients in the nonexercise group were contacted for clarification of preoperative exercise participation.
Although more patients in the exercise group were discharged home compared to the nonexercise group, we cannot attribute this purely to preoperative exercise intervention.19-21 The nonrandomized, retrospective design did not control for age, comorbidities, socioeconomic status, preoperative education, or patient expectations and motivation.
We recognize the limitation of a retrospective study design. However, we believe the study provides valuable insight into the positive postoperative effects of preoperative exercise in a select group of obese total joint replacement patients. A prospective, randomized controlled design may have improved the clinical significance of our findings.
A self-reported preoperative exercise program can improve postoperative functional mobility and increase the likelihood of discharge to home in total joint replacement patients with a BMI >30 kg/m2. Our results support the feasibility of a larger, prospective study to examine the effect of formalized preoperative exercise on patients with a BMI <30 kg/m2 vs patients with a BMI >30 kg/m2 anticipating total joint replacement surgery.
- Obesity and Overweight for Professionals: Data and Statistics: US Obesity Trends. Centers for Disease Control and Prevention Web site. http://www.cdc.gov/obesity/data/trends.html. Accessed November 12, 2009.
- Clinical Guidelines on the Identification, Evaluation, and Treatment of Over-Weight and Obesity in Adults: The Evidence Report, 1998. National Institutes of Health Web site. http://nhlbi.nih.gov/guidelines/obesity/ob_gdlns.pdf. Accessed November 12, 2009.
- Busato A, Röder C, Herren S, Eggli S. Influence of high BMI on functional outcome after total hip arthroplasty. Obes Surg. 2008; 18(5):595-600.
- Karlson EW, Mandl LA, Aweh GN, Sangha O, Liang MH, Grodstein F. Total hip replacement due to osteoarthritis: the importance of age, obesity, and other modifiable risk factors. Am J Med. 2003; 114(2):93-98.
- Vincent HK, Weng JP, Vincent KR. Effect of obesity on inpatient rehabilitation outcomes after total hip arthroplasty. Obesity (Silver Spring). 2007; 15(2):522-530.
- Gillespie GN, Porteous AJ. Obesity and knee arthroplasty. Knee. 2007; 14(2):81-86.
- Fehring TK, Odum SM, Griffin WL, Mason JB, McCoy TH. The obesity epidemic: its effect on total joint arthroplasty. J Arthroplasty. 2007; 22(6 suppl 2):71-76.
- Crowninshield RD, Rosenberg AG, Sporer SM. Changing demographics of patients with total joint replacement. Clin Orthop Relat Res. 2006; (443):266-272.
- Iorio R, Robb WJ, Healy WL, et al. Orthopaedic surgeon workforce and volume assessment for total hip and knee replacement in the United States: preparing for an epidemic. J Bone Joint Surg Am. 2008; 90(7):1598-1605.
- McDonald JE, Huo MH. Total hip replacement: unique challenges in the obese and geriatric populations. Curr Opin Orthop. 2008; 19(2):33-36.
- Gallagher S. Caring for the overweight patient in the acute care setting: addressing caregiver injury. Journal of Healthcare, Safety, Compliance, and Infection Control. 2000; 4(8):379-382.
- Rooks DS, Huang J, Bierbaum BE, et al. Effect of preoperative exercise on measures of functional status in men and women undergoing total hip and knee arthroplasty. Arthritis Rheum. 2006; 55(5):700-708.
- Barsoum WK, Murray TG, Klika AK, et al. Predicting patient discharge disposition after total joint arthroplasty in the United States. J Arthroplasty. In press.
- Munin MC, Rudy TE, Glynn NW, Crossett LS, Rubash HE. Early inpatient rehabilitation after elective hip and knee arthroplasty. JAMA. 1998; 279(11):847-852.
- McNemar test calculator. Dimension Research, Inc, Web site. http://www.dimensionresearch.com/resources/calculators/mcnemar.html. Accessed November 25, 2009.
- Z-test for two proportions calculator. Dimension Research, Inc, Web site. http://www.dimensionresearch.com/resources/calculators/ztest.html. Accessed November 25, 2009.
- Davis RM. Exercise: a dose of medicine we can all use. American Medical Association Web site. http://www.ama-assn.org/ama/no-index/news/18118.shtml. Published November 8, 2007. Accessed November 25, 2009.
- Position statement: the need for daily physical activity. American Academy of Orthopaedic Surgeons Web site. http://www.aaos.org/about/papers/position/1138.asp. Published February 1997. Updated December 2008. Accessed November 25, 2009.
- Oldmeadow LB, McBurney H, Robertson VJ, Kimmel L, Elliott B. Targeted postoperative care improves discharge outcome after hip or knee arthroplasty. Arch Phys Med Rehabil. 2004; 85(9):1424-1427.
- de Pablo P, Losina E, Phillips CB, et al. Determinants of discharge destination following elective total hip replacement. Arthritis Rheum. 2004; 51(6):1009-1017.
- Bozic KJ, Wagie A, Naessens JM, Berry DJ, Rubash HE. Predictors of discharge to an inpatient extended care facility after total hip or knee arthroplasty. J Arthroplasty. 2006, 21(6 Suppl 2):151-156.
Drs Robbins, Bono, and Ward are from the Department of Orthopedic Surgery, New England Baptist Hospital, Tufts University School of Medicine, and Dr Robbins and Mss Barry, Doren, and McNinch are from the Department of Rehabilitation Services, New England Baptist Hospital, Boston, Massachusetts.
Drs Robbins, Bono, and Ward and Mss Barry, Doren, and McNinch have no relevant financial relationships to disclose.
Correspondence should be addressed to: Claire E. Robbins, PT, DPT, MS, Department of Orthopedic Surgery, New England Baptist Hospital, 125 Parker Hill Ave, Boston, MA 02120 (firstname.lastname@example.org).