Research Article
Early Complications of Revision Total Knee Arthroplasty in Morbidly Obese Patients
Carter J, Springer B* and Curtin B
Department of Orthopedic Surgery, OrthoCarolina Hip and Knee Center, USA
*Corresponding author: Bryan Springer, Department of Orthopedic surgery, OrthoCarolina Hip and Knee Center, 2001 Vail Ave Suite 200A, Charlotte, NC 28207, USA
Published: 29 Jul, 2016
Cite this article as: Carter J, Springer B, Curtin B. Early Complications of Revision Total Knee Arthroplasty in Morbidly Obese Patients. Clin Surg. 2016; 1: 1056.
Abstract
Morbid obesity is a known risk factor for complications and failure following primary total knee
arthroplasty. Complications following revision Total Knee Arthroplasty (rTKA), however, in the
morbidly obese (BMI >40) have not been well described. A retrospective cohort study was designed
to investigate the early complications of rTKA procedures performed between January 2009 and
December 2012. Comparisons were made between patients with a normal BMI (18.5-25) and patients
with morbid obesity (BMI >40). We found that 33 of 141 morbidly obese patients (23.4%) had a
complication compared to 10 of 96 patients with a BMI 18.5-25 (10.4%) (p=0.011). Morbidly obese
patients were younger (69.3 years versus 61.4 years, p <.0001) and their most frequent complication
in comparison to patients with normal BMI was wound healing problems (p=0.01). Morbidly obese
patients are at a significantly increased rate of early complications following rTKA compared to a
normal weight cohort, especially with regards to wound complications. The morbidly obese group
was significantly younger at the time of rTKA. Early intervention to help with weight management
prior to TKA is needed. In addition, this study highlights the importance of risk stratification for
morbidly obese patients undergoing rTKA.
Keywords: Revision total knee arthroplasty; Morbid obesity; Complications
Introduction
The incidence of revision Total Knee Arthroplasty (rTKA) has increased dramatically concomitant
with increasing numbers of primary Total Knee Arthroplasty (TKA) [1,2]. The relationship between
morbid obesity and poor outcomes in primary TKA has been well documented [3-6] and we are
seeing an ever increasing number of young, sick and obese patients undergoing primary TKA.
Early postoperative complications, including infection, wound dehiscence, and genitourinary
complications as well as post-operative mortality are noted to be significantly higher in obese
patients undergoing primary TKA as well [3].
The effect of morbid obesity (BMI>40) on rTKA has not been as clearly described. Some studies
suggest that Body Mass Index (BMI) has no significant effect on complications after rTKA [7].
Others have reported rates of re-revision after rTKA as high as 2.9 times greater in patients with a
BMI>40 [8] compared to rTKA patients who are not morbidly obese. Morbid obesity is associated
with an increased risk of moderate-severe functional limitations [9]. Kasmire et al. [10] showed that BMI had an impact on postoperative function and Range Of Motion (ROM) after rTKA as assessed
by The Western Ontario and McMaster Universities Arthritis Index (WOMAC®). Similarly, Pulos
et al. [11] reported on the effect of obesity (BMI >35) on revision total hip arthroplasty, noting that
complications, infection, re-admission, and re-operation were significantly increased in this group.
More recently, a review of 93 morbidly obese patients undergoing rTKA were shown to have a
significantly higher revision, reoperation and infection rate than a comparative group with normal
BMI at a minimum 5 year follow-up [12].
Much emphasis is now being placed on identifying early complications in an effort to limit
readmissions. The purpose of this cohort study is to determine (1) Is the rate of early complications
after revision TKA increased in the morbidly obese patient population compared to patients with
normal BMI? (2) Which complications are the most frequent in the morbidly obese population after
revision TKA?
Methods
Using our institutional database, a retrospective cohort study was designed to investigate the
early complications of rTKA procedures. All patients who underwent rTKA between January
2007 and December 2012 were included. A minimum of two years
of follow up was required. These patients were then selected into
two study groups: those with morbid obesity (BMI>40) and those
with a normal BMI (BMI 18.5-25). Patients undergoing re-revision
TKA and unicompartmental knee arthroplasty revision to a TKA
were excluded from the study. Patients undergoing rTKA for aseptic
loosening, periprosthetic joint infection, patellofemoral problems,
periprosthetic fractures, malpositioning, instability, and osteolysis
were included in the study. All patients received the same standardized
postoperative regimen. They all received perioperative antibiotics in
the hospital, risk-stratified anticoagulation, and formalized physical
therapy in the hospital and upon discharge.
Immediate medical postoperative complications included wound
complications, Deep Vein Thrombosis (DVT), Pulmonary Embolism
(PE), Myocardial Infarction (MI), mortality, and Intensive Care
Unit (ICU) admission. Post-hospitalization complications included
deep periprosthetic joint infection, cellulitis, aseptic loosening,
component subsidence, amputation, mortality, and revision surgery.
Complications were obtained from a chart review of clinic follow-up
notes and recorded in RedCap, a secure online database. Patients who
lacked two years of follow-up notes in clinic were contacted by phone
to capture any extra complications that may have occurred.
Comparisons were made between patients with a normal BMI
(18.5-25) and patients with morbid obesity (BMI>40). Chi-Square
and Fishers Exact tests were used to determine differences in
complication rates between groups.
Table 1
Results
985 Revision TKAs were performed between January 2007 and
December 2012. Of these, 704 were excluded because their BMI was
between 25 and 40. 29 patients did not have a documented BMI.
15 were not included in the analysis because they did not meet the
inclusion criteria (re-revision, failed UKA).
The remaining 237 patients had a BMI<25 (96 pts) and BMI
>40 (141pts). Average follow up was 3.1 years. Of these, 96 (40.5%)
had a BMI 18.5-25 and 141 (59.5%) had a BMI>40. The morbidly
obese group was also significantly younger at time of revision surgery
(mean age 61.1 years versus 68.9 years, p<.0001). Overall, 43 of 237
patients (18.1%) had a complication. Thirty-three of 141 morbidly
obese patients (23.4%) had a complication compared to 10 of 96
patients with a BMI 18.5-25 (9.4%) (p=0.011).
The most common complications were wound complications,
which occurred significantly more in the morbidly obese group
(p=0.04). None of the other complications assessed had a statistically
significant difference. However, for every category of complications
analyzed, the occurrence was higher in the morbidly obese group.
There were four deep venous thromboses (DVTs) in the morbidly
obese group, while only one DVT in the normal BMI group (p=0.65).
There were six deep infections in the morbidly obese compared to
two deep infections in the normal BMI group (p=0.48). Six morbidly
obese patients had a postoperative cellulitis compared to zero patients
with normal BMI (p=0.08) (Table 1). With the numbers available we
also found no significant difference in manipulations, ICU admission,
amputation, and mortality.
Discussion
Obesity is known to be a significant risk factor for the development
of osteoarthritis of the knee [13]. As such, we are seeing a dramatic
rise in the utilization of primary TKA in obese patients [4,6]. There is a
growing preponderance of evidence highlighting the negative impact
of morbid obesity on TKA outcomes [3-6]. More recent data has
suggested the same trends apply to revision hip and knee arthroplasty
[9,11,12]. Our study demonstrates that rTKA in the morbidly obese
patient population is associated with a 2.6x increased rate of early
complications compared to patients with a normal weight (BMI 18.5-
25).
There are several limitations to a study of this design. It was
designed to investigate the early complications only, and may
miss further complications that occurred at a later date such as
aseptic loosening, wear, osteolysis and late infection that may occur
outside our average follow-up of three years. Secondly, although
complications are relatively objective, we did not evaluate the
functional outcomes of patients. Other studies have suggested poorer
functional outcomes in rTKA in morbidly obese patients [12]. Thus,
while some patients may not have experienced a formal complication,
their outcome may or may not be considered a clinical success.
Thirdly, overall complications in both cohorts were low. With the
numbers available in our study, failure to reach statistical significance
in several other categories may have resulted from an underpowered
study. In addition, the retrospective study involved multiple surgeons
over a long period of time with varying techniques that could
impact outcome. Lastly, and most importantly, we did not control
for comorbidities, therefore the true effect of obesity on outcomes,
rather than the effect of their associated comorbidities is impossible
to elucidate.
We noted a 2.6x increase in complications in the morbidly obese
compared to those with a normal BMI. This is similar to the increased
complication rates reported in re-revision TKA (2.9x increase) [8]
and in aseptic revision knees in the morbidly obese (3.8 fold increase)
[12]. The morbidly obese had significantly increased complications
despite having an age that was on average eight years younger. Prior
studies have indicated that there is a national trend for an increased
utilization of TKA in a younger, sicker and more obese cohort [6].
The age discrepancy is concerning, indicating that not only are obese
patients undergoing primary TKA at a younger age, their initial
surgery is potentially less durable requiring revision surgery at a
younger age as well.
We found a statistically significant higher rate of wound
complications in the morbidly obese cohort compared to those of a
normal weight following rTKA. Wound complications in the obese
undergoing TKA is well documented in the literature [3,14-16].
Wound healing problems, such as prolonged drainage are a harbinger
for the development of deep periprosthetic infection (PJI) [3,17,18].
Although, we did not show a statistical difference in PJI among our
two groups, there was a 6x higher rate of infection or cellulitis in the
morbidly obese group compared to the nonobese. In addition, every
other complication identified in the study (DVT, aseptic loosening),
although not statistically significant with the numbers presented, was
higher in the morbidly obese group.
Morbidly obese patients are at a significantly higher risk of early
complications following rTKA compared to a normal weight cohort.
This is consistent with the trends reported after primary TKA. Unlike
primary TKA, however, many rTKA are not elective and may require
urgent surgical intervention regardless of a patient’s BMI and limited
time and options to optimize patients. Our finding emphasizes the
need for medical optimization and weight management of morbidly
obese patients prior to undertaking primary TKA. In addition,
patients, surgeons, hospitals and payors must understand the
increased risks associated with morbidly obese patients undergoing
rTKA. Methods to appropriately risk stratify patients are imperative.
Acknowledgements
The authors like to acknowledge and thank Dr. Susan Odum, PhD and the OrthoCarolina Research Institute for their work on this project.
References
- Bozic KJ, Kurtz SM, Lau E, Ong K, Chiu V, Vail TP, et al. The epidemiology of revision total knee arthroplasty in the United States. Clinical orthopedics and related research. 2010; 468: 45-51.
- Kurtz SM, Ong KL, Schmier J, Zhao K, Mowat F, Lau E. Primary and revision arthroplasty surgery caseloads in the United States from 1990 to 2004. The Journal of arthroplasty. 2009; 24: 195-203.
- D'Apuzzo MR, Novicoff WM, Browne JA. The John Insall Award: Morbid obesity independently impacts complications, mortality, and resource use after TKA. Clinical orthopedics and related research. 2015; 473: 57-63.
- Fehring TK, Odum SM, Griffin WL, Mason JB, McCoy TH. The obesity epidemic: its effect on total joint arthroplasty. The Journal of arthroplasty. 2007; 22: 71-76.
- Namba RS, Paxton L, Fithian DC, Stone ML. Obesity and perioperative morbidity in total hip and total knee arthroplasty patients. The Journal of arthroplasty. 2005; 20: 46-50.
- Odum SM, Springer BD, Dennos AC, Fehring TK. National obesity trends in total knee arthroplasty. The Journal of arthroplasty. 2013; 28: 148-151.
- Bieger R, Kappe T, Jung S, Wernerus D, Reichel H. Does the body mass index influence the results of revision total knee arthroplasty?. Zeitschrift fur Orthopadie und Unfallchirurgie. 2013; 151: 226-230.
- Aggarwal VK, Goyal N, Deirmengian G, Rangavajulla A, Parvizi J, Austin MS. Revision total knee arthroplasty in the young patient: is there trouble on the horizon? The Journal of bone and joint surgery. American volume. 2014; 96: 536-542.
- Singh JA, O'Byrne MM, Harmsen WS, Lewallen DG. Predictors of moderate-severe functional limitation 2 and 5 years after revision total knee arthroplasty. The Journal of arthroplasty. 2010; 25: 1091-1095, 1095: e1091-1094.
- Kasmire KE, Rasouli MR, Mortazavi SM, Sharkey PF, Parvizi J. Predictors of functional outcome after revision total knee arthroplasty following aseptic failure. The Knee. 2014; 21: 264-267.
- Pulos N, McGraw MH, Courtney PM, Lee GC. Revision THA in obese patients is associated with high re-operation rates at short-term follow-up. The Journal of arthroplasty. 2014; 29: 209-213.
- Watts CD, Wagner ER, Houdek MT, Lewallen DG, Mabry TM. Morbid Obesity: Increased Risk of Failure after Aseptic Revision TKA. Clinical orthopedics and related research. 2015; 473: 2621-2627.
- Niu J, Zhang YQ, Torner J, Nevitt M, Lewis CE, Aliabadi P, et al. Is obesity a risk factor for progressive radiographic knee osteoarthritis?. Arthritis and rheumatism. 2009; 61: 329-335.
- Baker P, Petheram T, Jameson S, Reed M, Gregg P, Deehan D. The association between body mass index and the outcomes of total knee arthroplasty. The Journal of bone and joint surgery. 2012; 94: 1501-1508.
- Friedman RJ, Hess S, Berkowitz SD, Homering M. Complication rates after hip or knee arthroplasty in morbidly obese patients. Clinical orthopaedics and related research. 2013; 471: 3358-3366.
- Turki AS, Dakhil YA, Turki AA, Ferwana MS. Total knee arthroplasty: Effect of obesity and other patients' characteristics on operative duration and outcome. World journal of orthopedics. 2015; 6: 284-289.
- Belmont PJ Jr, Goodman GP, Waterman BR, Bader JO, Schoenfeld AJ. Thirty-day postoperative complications and mortality following total knee rthroplasty: incidence and risk factors among a national sample of 15,321 patients. The Journal of bone and joint surgery. 2014; 96: 20-26.
- Kerkhoffs GM, Servien E, Dunn W, Dahm D, Bramer JA, Haverkamp D. The influence of obesity on the complication rate and outcome of total knee arthroplasty: a meta-analysis and systematic literature review. The Journal of bone and joint surgery. 2012; 94: 1839-1844.