Is overweight or obesity a perioperative risk factor in total hip replacement?

doi:10.4236/health.2010.22023

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Vol.2, No.2, 157-161 (2010)

doi:10.4236/health.2010.22023

SciRes

Health

Is overweight or obesity a perioperative risk factor in

total hip replacement?

Mushtaq AlAssaf1, Michael Kolbeck2, Wolfgang Hönle1, Alexander Schuh2

1Department of Orthopaedic Surgery, Neumarkt Clinic, Neumarkt, Germany

2Research Unit Orthopaedics and General Surgery, Neumarkt Clinic, Neumarkt,Germany; [email protected]

Received 20 October 2009; revised 31 December 2009; accepted 3 January 2010.

ABSTRACT

Introduction: A large proportion of patients who

undergo total hip replacement (THR) are obese.

Aim of the present study is to investigate the

influence of Body Mass Index (BMI) on compli-

cations following THR in a single surgeon in the

short term follow-up. Material and method: This

study was based on the retrospective review of

charts and BMIs from 171 patients who had

undergone THR between April 2005 and March

2006 at our hospital. All operations were per-

formed by a single surgeon. All patients were

followed up 6 weeks after operation. Results: 27

/ 171 patients (15.8%) were found to have com-

plications. Systemic minor complications in-

cluded arrythmia in 1 case, urinary tract infec-

tion in two cases, ileus in two cases, renal in-

sufficiency in 3 cases, confusion in 2 cases and

anaemia in 14 cases (8.2%) requiring blood tr-

ansfusion. There was one case of pulmonary

embolism as a major systemic complication.

Local minor complications included one single

dislocation and 1 superficial wound infection.

Body mass index ranged from 20.8 to 46.7 with a

mean of 28.6. Hospital length of stay ranged

from 10 to 42 days with a mean of 13. The leng-

th of operation time between obese and non-

obese patients varied significantly in our study.

There was no increased risk for complications

and length of hospital stay. Discussion: We can

conclude that there are no economic or medical

reasons for excluding obese patients from THR

as there is no increased risk for complications

and length of hospital stay.

Keywords: Total Hip Replacement, Complication,

Obesity, BMI, Bleeding

1. INTRODUCTION

A large proportion of patients who undergo total hip re-

placement (THR) are obese 17,18. There has been mu-

ch concern that obesity is associated with anaesthetic

and operative complications after THR. Obese patients

have a higher risk of adverse cardiovascular and respi-

ratory events and obesity is an independent risk factor

for the development of type II diabetes mellitus, a condi-

tion that carries an increased risk of post-operative mor-

bidity. Other studies have demonstrated an increased risk

of venous thromboembolic disease following joint re-

placement surgery in the obese. There is a strong asso-

ciation between obesity and prolonged wound drainage

post-operatively which, in turn, is associated with a

higher rate of wound infection and blood loss 1,4,20.

Namba et al. 15 concluded that obese patients have a

4.2 times higher risk of post-operative infection follow-

ing THR. Furthermore, obesity has a bearing on health

economics, with obese patients having an increased

length of hospital stay compared with the general popu-

lation 3,12. Recently a weak correlation BMI and the

complication rate in THR has been published by Patel A

et al. 17. He stated that orthopaedic surgeons should be

aware of the slightly higher risk in THR in such patients.

On the other hand several authors found no increased

post-operative complications rate in obese patients un-

dergoing THR 2,9,11,19. Aim of this study was to in-

vestigate the influence of BMI on complications follow-

ing THR in a single surgeon.

2. MATERIAL AND METHOD

This study was based on the retrospective review of

charts and BMIs from 171 patients who had undergone

THR between April 2005 and March 2006 at our hospi-

tal. All operations were performed by a single surgeon

(WH). Prior to surgery weight and height of the patients

were recorded by nursing staff. BMI was calculated as

the body weight in kilograms divided by the height in

metres squared. Co-morbid conditions were also re-

corded. Any complications reported by the patient or the

medical staff were recorded. Complications were group-

M. AlAssaf et al. / HEALTH 2 (2010) 157-161

158

ed into systemic and local, each group being subdivided

into minor and major according to Patel 17. A compli-

cation that could be treated with medical and conserva-

tive management or that was not a risk to the artificial

joint and/or the patient was listed as a minor complica-

tion (superficial infection, ooze, pain). Any complication

that needed surgical/medical intervention and posed a

risk to the joint or the patient was listed as a major com-

plication (dehiscence, deep infection, post- operative

stiffness requiring manipulation under anaesthesia,

haematoma requiring second operation, cardiac arrest,

deep vein thrombosis, cardiovascular accident, conges-

tive cardiac failure, systemic infection, intensive care

unit admission, myocardial infarction, pulmonary embo-

lism). There were 75 men and 96 women. Average

height was 168 cm (Min: 147, Max: 193). Average

weight was 81 Kg (Min: 53, Max: 160). Average age at

time of operation was 66 years (Min: 43, Max: 90). We

reviewed all BMIs and divided the patients into 4 groups:

BMI < 26 (Optimal and under weight), 26 - 30 (Clini-

cally overweight), 31 - 40 (Clinically obese), > 40

(Morbidly obese) 4. Patient clinical complexity level

(PCCL) was assigned. PCCL of women was 0 in 62

cases, 1 in 1 case, 2 in 14 cases, 3 in 12 cases and 4 in 7

cases. PCCL of men was 0 in 55 cases, 2 in 7 cases, 3 in

10 cases and 4 in 3 cases. The indications for THR were

dysplastic coxarthrosis (15), primary arthrosis of the hip

(124), inflammatory arthritis (2), secondary osteoarthri-

tis (26), rheumatoid arthritis (3), necrosis of the femoral

head (1).

On the acetabular side, a standard cementless acetabu-

lar cup according to Wagner was used in 148 cases, in 19

cases a cemented full-profile polyethylene cup in 4 cases

an acetabular reconstruction ring. On the femoral side, 1

case was treated with the cementless Cone Prosthesis

according to Wagner, 154 with a cementless CLS stem

and 16 with a cemented Müller Straight Stem. The bear-

ing surfaces were polyethylene/ceramic in all cases. All

procedures were performed in an ultra-clean-air theater

(with antibiotic prophylaxis). During their stay at the

hospital, all patients were treated with low molecular

weight Heparin and compression stockings as a prophy-

laxis against deep vein thrombosis. For the duration of 8

weeks, partial weight bearing of 20 kg with the support

of lower arm crutches was required. Average operation

time was 65 min (Min: 42, Max: 170).

Data were first fed in electronic format into Excel.

Accuracy of the electronic data was confirmed by three

independent observers. Data were then analysed for fre-

quencies and Chi-squared test. All patients were fol-

lowed up by one of us (MA) 6 weeks after operation.

3. RESULTS

Body mass index ranged from 20.8 to 46.7 with a mean

of 28.6. 27 / 171 patients (15.8%) were found to have

complications. Systemic minor complications included

arrythmia in 1 case, acute hypertension in one case, uri-

nary tract infection in two cases, ileus in two cases, renal

insufficiency in 3 cases, confusion in 2 cases and anae-

mia in 14 cases (8.2%) requiring blood transfusion.

There was one case of pulmonary embolism as a major

systemic complication. Local minor complications in-

cluded one single dislocation and 1 superficial wound

infection. Hospital length of stay ranged from 10 to 42

days with a mean of 13. Average loss of haemoglobin in

women was -3.5 (Min: -0.8, Max: -9.2) and in men -3.8

(Min: -1, Max: -7.7) (Table 1). Table 2 shows the dif-

ferent complications and related BMI.

For the purpose of analysis patients were split into 4

groups of BMI (Table 3) with a complication rate rang-

ing from 6.2 - 41.5% (17/ 41 (41.5%), 4/64 (6.2%), 5/ 62

(8.0%) and 2/6 (33.3%). When patients were put into

BMI groups there was no effect on complication rate

with increasing BMI.

Table 1. Distibution of demographic data and BMI.

BMI vs Hemoglobin loss Mean (g/dl)

Women

< 26 -3,84

26 - 30 -3,88

31 - 40 -3,68

> 40 -3,30

Men

< 26 -4,77

26 - 30 -3,72

31 - 40 -4,11

> 40 ---

BMI vs. Length of hospital stay Mean (days)

Women

< 26 13,5

26 - 30 13,14

31 - 40 13,82

> 40 14,66

Men

< 26 13,5

26 - 30 13,12

31 - 40 15,62

> 40 ---

BMI vs. Duration of operation Mean (hours)

Women

< 26 1:08

26 - 30 1:04

31 - 40 1:07

> 40 1:27

Men

< 26 1:02

26 - 30 1:04

31 - 40 1:09

> 40 ---

M. AlAssaf et al. / HEALTH 2 (2010) 157-161

159

Table 2. Complications and BMI.

Initials Complication Sex Age BMI

BE1 Acute hypertension f 56 42,2

GM1 Acute renal failure f 80 20,8

NR1 Acute renal failure m 62 32,0

TG1 Acute renal failure f 73 30,1

KF1 Postoperative Delirium m 79 23,4

RM1 Postoperative Delirium f 90 21,2

KF1 Arrhythmia m 79 23,4

AE1 Haemorrhage f 81 25,8

AC1 Haemorrhage f 66 24,7

GH1 Haemorrhage f 70 22,6

GM1 Haemorrhage f 80 20,8

KH1 Haemorrhage f 77 25,2

KM1 Haemorrhage f 46 23,7

NR1 Haemorrhage m 62 32,1

PM1 Haemorrhage f 55 26,4

RA1 Haemorrhage f 59 23,4

SB1 Haemorrhage f 81 25,6

SH1 Haemorrhage m 76 28,7

TG1 Haemorrhage f 73 30,1

WC1 Haemorrhage f 90 24,5

WM1 Haemorrhage f 82 21,3

KP1 Ileus, not particularly specified m 68 34,3

SA1 Ileus, not particularly specified m 75 30,3

GM1 Infection, not particularly specified f 80 20,8

EG1 Dislocation m 56 35,9

BE1 Pulmonary embolism f 56 42,2

BR1 Urinary tract infection f 78 25,0

KF1 Urinary tract infection m 79 23,4

Table 3. Correlation between complications and BMI divided

into four groups.

Complications BMI groups

No Yes

< 26 Count 24 17

26 - 30 Count 60 4

31 - 40 Count 57 5

> 40 Count 4 2

4. DISCUSSION

The numbers of patients presenting for THR who are

obese is increasing and there have been concerns that

these patients have an increased risk of complications

and a reduced benefit of surgery in terms of function and

pain relief 3,9,13,14,16. A higher risk for obese pa-

tients in respect to deep infection dislocations and revi-

sion rate for septic loosening has been postulated 7,8,

10,12,21.

Stickles et al. 23 reported a higher rate of orthopae-

dic complications (infection, dislocation, component

failure) with increasing BMI in the first year after THR.

Obese patients are often considered poor candidates

for total joint arthroplasty. These patients tend to have

longer hospital stays and higher total charges compared

with nonobese patients 6. Ibrahim et al. 9 could not

found any difference in the length of hospital stay be-

tween obese and non-obese patients. This compares fa-

vourably with our results. Within the current literature,

the effect of obesity on THA remains varied. Some re-

ports have found no difference in the rate of periopera-

tive complications between obese and non-obese patients.

Anderson et al. 2 and Soballe et al. 22 found no rela-

tionship between obesity and postoperative complica-

tions. Lehman et al. 11 showed no difference in the

prevalence of perioperative complications in obese pa-

M. AlAssaf et al. / HEALTH 2 (2010) 157-161

160

tients with similar gains in pain relief and functional

abilities as non-obese patients. Chan and Villar 5

showed no difference in the quality of life in the short

term following THA between obese and non-obese pa-

tients. With our study results we can follow Andrew et al.

3 and Ibrahim et al. 9 that there is no association be-

tween obesity and the risk of revision surgery or other

complications. Especially we could not found any in-

creased risk for hematoma, dislocation rate and infection

rate and the rate of blood transfusion in the short term

follow up.

Certainly a limitation of this study is the short period

of follow-up. This limitation is of particular importance

to the rate of revision surgery. A major advantage of our

study is a consecutive patient series who were operated

by the same orthopaedic surgeon. Patel et al. 17 came

to the same conclusion in a patient cohort who was op-

erated by seven different orthopaedic surgeons. Interest-

ingly Bowditch et al. 4 found a higher rate of blood

loss in obese patients. A lack of this study is the small

number of 80 Patients operated by four surgeons. To be

able to compare different studies we suggest a larger

series of patients operated by the same orthopaedic sur-

geon and the use of the same classification system for

obesity. We believe that the lack of consensus regarding

the impact of obesity on THR may be explained in part

by the different definitions of obesity which have been

used 3. The aim of our study was to investigate the

influence of BMI on early complications in THR. The

length of operation between obese and non-obese pa-

tients varied significantly in our study. Nevertheless we

can conclude that there are no economic or medical rea-

sons for excluding obese patients from THR, especially

as there is no increased risk for complications and length

of hospital stay. We fully agree with Andrew et al. 3

who postulated that patients should still be encouraged

to reduce their weight prior to surgery but it seems un-

acceptable for patients to be denied treatment in the form

of hip replacement solely on the basis of their BMI.

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