Greater risks of complications, infections, and revisions in the obese versus non-obese total hip arthroplasty population of 2,190,824 patients: a meta-analysis and systematic review

Journal Pre-proof Obesity is associated with greater risks of complications, infections, and revisions in a total hip arthroplasty population of 2,190,824 patients: A meta-analysis and systematic review James Onggo, MBBS(Hons), Jason Onggo, B Eng, Richard de Steiger, MBBS, FRACS, PhD, Raphael Hau, MBBS, FRACS PII:

S1063-4584(19)31236-1

DOI:

https://doi.org/10.1016/j.joca.2019.10.005

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YJOCA 4545

To appear in:

Osteoarthritis and Cartilage

Received Date: 23 July 2019 Revised Date:

3 September 2019

Accepted Date: 15 October 2019

Please cite this article as: Onggo J, Onggo J, de Steiger R, Hau R, Obesity is associated with greater risks of complications, infections, and revisions in a total hip arthroplasty population of 2,190,824 patients: A meta-analysis and systematic review, Osteoarthritis and Cartilage, https://doi.org/10.1016/ j.joca.2019.10.005. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Obesity is associated with greater risks of complications, infections, and revisions in a total hip arthroplasty population of 2,190,824 patients: A meta-analysis and systematic review

Running title: Obesity in total hip arthroplasty

James Onggo, MBBS(Hons)a [[email protected]] Jason Onggo, B Enga [[email protected]] Richard de Steiger, MBBS, FRACS, PhDb [[email protected]] Raphael Hau, MBBS, FRACSa, c [[email protected]]

a

Department of Orthopaedic Surgery, Box Hill Hospital, Melbourne, Australia •

b

Department of Surgery Epworth Healthcare, University of Melbourne, Melbourne, Australia •

c

8 Arnold Street, Box Hill, VIC 3128

University of Melbourne, Parkville, VIC 3010

Department of Orthopaedic Surgery, Epworth Eastern Hospital, Melbourne, Australia •

1 Arnold Street, Box Hill VIC 3128

Corresponding Author: Name: James Randolph Onggo Email: [email protected] Postal address: Department of Orthopaedic Surgery, Box Hill Hospital, 8 Arnold Street, Box Hill, VIC 3128 Telephone: +61 423 258 748

KEYWORDS: •

Obesity

•

Morbid obesity

•

Outcomes

•

Complications

•

Total hip arthroplasty

•

Total hip replacement

Potential conflict of interest: The authors have no potential conflict of interest to declare.

ABSTRACT Background: Obesity is an epidemic, especially in developed countries. This affects the general health of these patients, especially when they are having a major surgical procedure such as total hip arthroplasty (THA). Several articles have described the effects of obesity on THA with varying conclusions. This meta-analysis aims to compare the outcomes, complications, and peri-operative parameters of THA in the obese (BMI≥30kg/m2) versus non-obese (BMI<30kg/m2) population as well as a subgroup analysis of morbidly obese (BMI≥40kg/m2) versus non-obese population.

Methods: A multi-database search was performed according to PRISMA guidelines. Data from studies assessing the outcomes and complications of THA in the obese and non-obese population were extracted and analyzed.

Results: Sixty-seven studies were included in this meta-analysis, consisting of 581,012 obese and 1,609,812 non-obese patients. Meta-analysis could not be performed on patient reported outcome measures due to heterogeneous reporting methods. Obese patients had a higher risk of all complications (OR=1.53, 95%CI: 1.30-1.80, p<0.001), deep infections (OR=2.71, 95%CI: 2.08-3.53, p<0.001), superficial infections (OR=1.99, 95%CI: 1.55-2.55, p<0.001), dislocations (OR=1.72, 95%CI: 1.66-1.79, p<0.001), reoperations (OR=1.61, 95%CI: 1.40-1.85, p<0.001), revisions (OR=1.44, 95%CI: 1.321.57, p<0.001), and readmissions (OR=1.37, 95%CI: 1.15-1.63, p<0.001). When sub-group analysis of morbidly obese (BMI≥40kg/m2) patients was performed, the risks of all these parameters were even greater.

Conclusion: Obese and morbidly obese patients are at higher risks of complications post THA than non-obese patients. Surgeons should be aware of these risks in order to counsel patients and adopt prophylactic strategies to reduce these risks where applicable.

1

Greater risks of complications, infections, and revisions in the obese versus non-obese total hip

2

arthroplasty population of 2,190,824 patients: A meta-analysis and systematic review

3 4

ABSTRACT

5

Background:

6

Obesity is an epidemic, especially in developed countries. This affects the general health of these

7

patients, especially when they are having a major surgical procedure such as total hip arthroplasty

8

(THA). Several articles have described the effects of obesity on THA with varying conclusions. This

9

meta-analysis aims to compare the outcomes, complications, and peri-operative parameters of THA in

10

the obese (BMI≥30kg/m2) versus non-obese (BMI<30kg/m2) population as well as a subgroup analysis

11

of morbidly obese (BMI≥40kg/m2) versus non-obese population.

12 13

Methods:

14

A multi-database search was performed according to PRISMA guidelines. Data from studies assessing

15

the outcomes and complications of THA in the obese and non-obese population were extracted and

16

analyzed.

17 18

Results:

19

Sixty-seven studies were included in this meta-analysis, consisting of 581,012 obese and 1,609,812

20

non-obese patients. Meta-analysis could not be performed on patient reported outcome measures due to

21

heterogeneous reporting methods. Obese patients had a higher risk of all complications (OR=1.53,

22

95%CI: 1.30-1.80, p<0.001), deep infections (OR=2.71, 95%CI: 2.08-3.53, p<0.001), superficial

23

infections (OR=1.99, 95%CI: 1.55-2.55, p<0.001), dislocations (OR=1.72, 95%CI: 1.66-1.79,

24

p<0.001), reoperations (OR=1.61, 95%CI: 1.40-1.85, p<0.001), revisions (OR=1.44, 95%CI: 1.32-

25

1.57, p<0.001), and readmissions (OR=1.37, 95%CI: 1.15-1.63, p<0.001). When sub-group analysis of

26

morbidly obese (BMI≥40kg/m2) patients was performed, the risks of all these parameters were even

27

greater.

28 29 30

1

31

Conclusion:

32

Obese and morbidly obese patients are at higher risks of complications post THA than non-obese

33

patients. Surgeons should be aware of these risks in order to counsel patients and adopt prophylactic

34

strategies to reduce these risks where applicable.

35 36

EVIDENCE LEVEL: Level II, Meta-analysis of heterogeneous studies

37 38

KEYWORDS:

39

•

Obesity

40

•

Morbid obesity

41

•

Outcomes

42

•

Complications

43

•

Total hip arthroplasty

44

•

Total hip replacement

45 46

INTRODUCTION

47

Obesity is fast becoming an epidemic, especially in developed countries.(1) While a body mass index

48

(BMI) exceeding 30kg/m2 is not a true reflection of general state of health or fitness level, the medical

49

co-morbidities of obesity (BMI≥30kg/m2) are well documented, and there is an association with the

50

development of hip osteoarthritis.(2, 3) The increase in BMI across our population has implications for

51

both the numbers of hip and knee arthroplasties being performed but also for subsequent outcomes.(1,

52

4)

53 54

Obese patients (BMI≥30kg/m2) have been reported to experience substantial improvements in pain,

55

function, and activity levels post THA.(5-9) However, some studies have also shown that THA in

56

obese patients can lead to longer operation duration(10-14) and higher peri-operative complication

57

rates.(1, 14-24) Due to the rising extent and degree of obesity worldwide, some studies have started

58

looking at the impact on patients with even higher rates of obesity with a BMI exceeding 40kg/m2 or

59

50kg/m2.(21, 25-29) While sample sizes have been small, these studies have shown even greater risks

2

60

of complications, with up to 7.7 times and 4.5 times respectively, the risk of all-cause complications

61

and revisions with higher BMI values.(25, 27)

62 63

This meta-analysis and systematic review compares the outcomes, complications, and peri-operative

64

parameters of THA in the obese versus non-obese (BMI<30kg/m2) population as well as a subgroup

65

analysis comparing morbidly obese (BMI≥40kg/m2) versus non-obese populations. This study aims to

66

determine numerical magnitudes to which complication risks are increased for the obese and morbidly

67

obese THA population.

68 69

METHODS

70

Literature Search

71

This meta-analysis was performed according to the Preferred Reporting Items for Systematic reviews

72

and Meta-Analyses (PRISMA) criteria.(30) A comprehensive search was conducted across multi-

73

databases (PubMed, OVID Medline, EMBASE) from the date of database inception to 5th May 2019.

74

The Medical Subject Heading and Boolean operator terms utilized for the search were: [(‘Total hip

75

arthroplasty’ OR ‘Total hip replacement’) AND (‘Obesity’ OR ‘Morbid obesity’ OR ‘Super obesity’

76

OR ‘Non-obese’ OR ‘overweight’) AND (‘Outcome’ OR ‘Complication’)]. Identified articles and their

77

corresponding references were reviewed according to the selection criteria for consideration of

78

inclusion.

79 80

Selection Criteria

81

All articles of any study design directly comparing the outcome and complications of THA in obese

82

and non-obese population were considered for inclusion. Non-English language studies, non peer-

83

reviewed studies, unpublished manuscripts, and studies not directly comparing obese and non-obese

84

THA outcomes and complications were excluded. Two independent authors reviewed records retrieved

85

from the initial search twice and excluded irrelevant ones. Titles and abstracts of remaining articles

86

were then screened against the inclusion criteria. Included articles were critically reviewed according to

87

a predefined data extraction form. Differences in opinions were resolved by discussion among authors

88

at all times.

89

3

90

Data Extraction

91

Extracted data parameters included details on study designs, publication year, patient numbers, basic

92

demographics, functional outcomes, complications, and peri-operative parameters. Functional

93

outcomes that were extracted included the EuroQoL 5-Dimension, Harris Hip Score, Merle d'Aubigne

94

and Postel score, Oxford Hip Score, pain scores, range of movement (includes flexion-extension,

95

external-internal rotation and abduction-adduction), UCLA activity scale, Western Ontario and

96

McMaster Universities Osteoarthritis Index score, 36-Item Short Form Health Survey, and 6-minutes

97

walking test. Metrics evaluated encompassed all-cause revisions, all complications, aseptic loosening,

98

deep and superficial infections, dislocations, nerve palsies, peri-prosthetic fractures, readmissions,

99

unplanned reoperations, and venous thrombo-emboli (VTE). Peri-operative parameters included

100

discharge to inpatient rehabilitation facility (IRF), mean blood loss (millilitres), mean length of stay

101

(days), and mean operative time (minutes). Data extracted was copied and organised into a Microsoft

102

Excel spreadsheet.

103 104

Methodology Assessment

105

Methodology quality of included studies was assessed with the Methodological Index for Non-

106

Randomized Studies (MINORS).(31) MINORS uses 12 criteria to assess non-randomized comparative

107

studies. Each criterion was scored with a 3-point system from 0 to 2 (0: not reported, 1: inadequately

108

reported and 2: adequately reported). The ideal score is 24 points.

109 110

Statistical Analysis

111

The odds ratio (OR) was used as a summary statistic. In the present study, both fixed- and random-

112

effects models were tested. In the fixed-effects model, it was assumed that treatment effect in each

113

study was the same, whereas in a random-effects model, it was assumed that there were variations

114

between studies. X2 tests were used to study heterogeneity between trials. I2 statistic was used to

115

estimate the percentage of total variation across studies, owing to heterogeneity rather than chance,

116

with values greater than 50% considered as substantial heterogeneity. I2 can be calculated as: I2 = 100%

117

x (Q - df)/Q, with Q defined as Cochrane’s heterogeneity statistics and df defined as degree of freedom.

118

If there was substantial heterogeneity, the possible clinical and methodological reasons for this were

119

explored qualitatively. In the present meta-analysis, the results using the random-effects model were

4

120

presented to take into account the possible clinical diversity and methodological variation between

121

studies. Specific analyses considering confounding factors were not possible because raw data were not

122

available. All p values were two-sided. Review Manager (version 5.3, Copenhagen, The Nordic

123

Cochrane Centre, The Cochrane Collaboration, 2014) was used for statistical analysis. All forest plots

124

have been stratified according to study types, mainly prospective, retrospective and case controlled

125

studies, to provide readers with a greater sense of the impact of the bias within each group.

126 127

RESULTS

128

Literature Search

129

A selection process flowchart to identify included studies is illustrated in Figure 1. A total of 1180

130

studies were identified from the initial search, of which 379 duplicates and 40 non-English language

131

articles were removed. Titles and abstracts of 761 remaining studies were screened in accordance to the

132

pre-defined inclusion criteria, of which 675 studies were excluded. Four additional studies(32-35) were

133

identified from citation search and 90 full-text articles were assessed for eligibility. A total 67

134

studies(1, 4-29, 32-71) were included, consisting of 19 prospective,(7, 8, 10, 13, 19, 26, 33, 36, 39, 42,

135

44, 54-57, 59, 62, 64, 70) 39 retrospective(1, 4-6, 9, 12, 14-16, 18, 20-24, 32, 34, 35, 37, 41, 43, 45-53,

136

58, 60, 61, 63, 65-67, 69, 71, 72), and nine case controlled studies.(11, 17, 25, 27-29, 38, 40, 68)

137 138

Demographics

139

A total of 581,012 obese and 1,609,812 non-obese patients were included in this study. The distribution

140

of gender amongst patients was reported by 47 studies (obese, n = 275,877; non-obese, n=1,199,361).

141

61.0% of obese patients were females (n = 168,338 of 275,877), while 60.7% of non-obese patients

142

were females (n = 728,470 of 1,199,361). From 54 studies that reported age for both groups, mean age

143

of index THA in the obese group ranged from 50.0(28) to 74.5 years,(60) with a minimum and

144

maximum age of between 17.0(58) and 91.0(47) years. The mean age of non-obese group ranged from

145

48.0(58) to 77.2 years,(60) with a minimum and maximum age of between 19.0(47, 48, 58) and

146

94.9(10) years.

147 148

A total of 14 studies reported a significantly younger patient cohort in the obese than non-obese group

149

(p<0.05). This is consistent with our meta-analysis that reveals obese and morbidly obese patients

5

150

being 2.57 years (95%CI: 1.62-3.52, p<0.001, obese n=18,296, non-obese, n=398,840) and 6.34 years

151

(95%CI: 5.37-7.31, p<0.001, morbidly obese n=2,070, non-obese n=192,729) younger than non-obese

152

patients at time of surgery. (Appendix 1.1-1.2) The prevalence of diabetes was also found to be higher

153

in the obese (OR: 2.21, 95%CI: 1.57-3.11, p<0.001, obese n=175,036, non-obese, n=757,822) group,

154

but ironically not the morbidly obese (OR=2.71, 95%CI: 0.94-7.84, p=0.07, morbidly obese=76,051,

155

non-obese=723,071) group when compared to the non-obese group. (Appendix 1.3-1.4) Follow-up

156

period was reported by 59 studies, ranging from the peri-operative period(13, 32, 39, 45, 47, 53, 64) up

157

to 14.9 years.(49) Study details are displayed in Table 1.

158 159

Methodology Assessment

160

The MINORS score for non-randomized studies ranged from 8 to 22, with an average value of 15.75.

161

Individual scores for each criterion are detailed in Appendix 2.

162 163

Clinical Outcomes

164

Due to heterogeneity of patient related outcome measures (PROMs) from 33 studies that included

165

13,149 obese (morbidly obese subgroup, n=888) and 22,547 non-obese patients, a comparative

166

statistical analysis could not be performed. We have synthesized and summarized all PROMs reported

167

and blood loss compared between the obese and non-obese groups in Table 2. There was no observable

168

trend that can be identified in PROMs as reported by different authors. In some cases, there were

169

conflicting results between different authors.

170 171

Complications

172

A total of 487,930 obese (morbidly obese subgroup, n=85,613) and 1,123,803 non-obese patients from

173

46 studies were included for statistical analysis of complications.

174 175

Obese THA patients had higher risks of all complications (OR=1.53, 95%CI: 1.30-1.80, p<0.001), deep

176

infections (OR=2.71, 95%CI: 2.08-3.53, p<0.001), (Figures 2-3 respectively) superficial infections

177

(OR=1.99, 95%CI: 1.55-2.55, p<0.001), dislocations (OR=1.72, 95%CI: 1.66-1.79, p<0.001),

178

reoperations (OR=1.61, 95%CI: 1.40-1.85, p<0.001), revisions (OR=1.44, 95%CI: 1.32-1.57,

179

p<0.001), and readmissions (OR=1.37, 95%CI: 1.15-1.63, p<0.001). (Appendix 3.1-3.5 respectively)

6

180

However, obese patients did not exhibit an increased risk of VTE (OR=1.44, 95%CI: 0.93-2.21,

181

p=0.10), peri-prosthetic fracture (OR=1.12, 95%CI: 0.98-1.28, p=0.08), aseptic loosening (OR=0.98,

182

95%CI: 0.78-1.22, p=0.84), or nerve palsies (OR=0.90, 95%CI: 0.30-2.67, p=0.84). (Appendix 3.6-3.9

183

respectively)

184 185

Subgroup analysis

186

Subgroup analysis comparing morbidly obese (n=85,613) and non-obese (n=1,123,803) patients

187

showed complication risks of an even greater magnitude. Morbidly obese patients showed a greater risk

188

of all complications (OR=2.68, 95%CI: 2.03-3.53, p<0.001), deep infections (OR=3.69, 95%CI: 3.16-

189

4.30, p<0.001), (Figures 4-5 respectively) superficial infection (OR=4.95, 95%CI: 3.87-6.33,

190

p<0.001), reoperations (OR=2.96, 95%CI: 2.21-3.96, p<0.001), revisions (OR=2.17 95%CI: 1.90-2.48,

191

p<0.001), dislocations (OR=2.12, 95%CI: 2.01-2.23, p<0.001), and readmissions (OR=1.99, 95%CI:

192

1.81-2.20, p<0.001). (Appendix 4.1-4.5 respectively) Similarly, morbidly obese patients also did not

193

exhibit a higher risk of VTE (OR=1.83, 95%CI: 0.81-4.17, p=0.15), peri-prosthetic fracture (OR=1.29,

194

95%CI: 0.48-3.45, p=0.61) or aseptic loosening (OR=1.23, 95%CI: 0.39-3.83, p=0.72). (Appendix

195

4.6-4.8 respectively) Further subgroup analysis comparing the complication profile between obese and

196

morbidly obese patients have been performed and illustrated in Appendix 5.1-5.10.

197 198

Peri-operative parameters

199

A total of 53,218 obese (morbidly obese subgroup, n=19,600) and 424,008 non-obese patients from 18

200

studies were included for statistical analysis of peri-operative parameters. Obese patients undergoing

201

THA had a significantly longer mean operative time (MD=8.71mins, 95%CI: 3.82-13.61, p<0.001),

202

and mean LOS (MD=0.45days, 95%CI: 0.15-0.75, p=0.003) than non-obese patients. However, mean

203

blood loss was comparable between both groups (MD=53.12mL, 95%CI: -65.18-171.41, p=0.38)

204

(Appendix 6.1-6.3 respectively)

205 206

Subgroup analysis

207

Subgroup analysis comparing between morbidly obese (n=19,600) and non-obese (n=424,008) patients

208

also showed a significantly increased mean operative time (MD=13.07mins, 95%CI: 5.88-20.26,

209

p<0.001), and mean LOS (MD=0.37days, 95%CI: 0.01-0.72, p=0.04). (Figure 6.4-6.5 respectively)

7

210

Subgroup analysis was not performed on mean blood loss due to a lack of raw data caused by

211

heterogeneous reporting methods.

212 213

In terms of discharge destination, there was a higher rate of THA patients being discharged to inpatient

214

rehabilitation facilities (IRF) in the obese then non-obese group (OR=1.30, 95%CI: 1.06-1.60, p=0.01).

215

This is further increased when subgroup analysis between morbidly obese and non-obese patients was

216

performed (OR=1.48, 95%CI: 1.33-1.66, p<0.001). (Appendix 6.6-6.7 respectively)

217 218

Survivorship

219

A combined Kaplan-Meier survival analysis to compare overall survivorship of the primary total hip

220

arthroplasty between the obese and non-obese group could not be performed due to the lack of raw

221

data. The survivorship rates of THA in both obese and non-obese groups have been summarised and

222

synthesised in Table 3.

223 224

DISCUSSION

225

This is the largest meta-analysis to date, that the authors are aware of, comparing the outcomes,

226

complications, and peri-operative parameters of THA in the obese and non-obese population. Our most

227

prominent findings are an increased risk of all complications, deep infections, superficial infections,

228

dislocations, reoperations, all-cause revisions, readmissions, discharge to IRF, prolonged mean length

229

of stay, and operative time in the obese population. These risks are even higher when subgroup analysis

230

of morbidly obese versus non-obese population was performed suggesting a direct correlation between

231

increased obesity and complications in THA. Our findings with regards to revision and infection are

232

supported by national joint replacement registries, which also demonstrate increased revisions for

233

infections with increasing levels of BMI.(73)

234 235

The greatest strength of this analysis is the extremely high number of patients included in quantitative

236

analysis, allowing for a better representation of the general population. This increases the external

237

validity of the results presented and improves its applicability to the general population.(74)

238

Furthermore, the most recent analysis by Ponnusamy(75) was performed with articles until August

239

2016. Since then, there are several high statistical powered articles that have been published and

8

240

included in this updated analysis. Previous analysis by Haverkamp(72) and Liu(76) did not investigate

241

the impact that the degree of obesity would have on complication rates. Our analysis has overcome this

242

by including a subgroup analysis of morbidly obese patients and showed even greater risks of

243

complications in the latter group. Whilst recent analysis by Ponnusamy(75) did perform subgroup

244

analysis for BMI exceeding 35, 40, and 45 patient groups, statistical analysis was focused mainly on

245

infection and revision rates only. However, it is our opinion that complications such as dislocations,

246

readmissions, and unplanned reoperations are also imperative to consider as they have huge financial,

247

social, and emotional consequences for the individual patients, their families, and the health system.

248

Hence, an updated meta-analysis on various complications with subgroup analysis is valuable.

249 250

Amongst the different complications, the risks of both peri-prosthetic fractures and aseptic loosening

251

were not significantly higher in the obese than non-obese group. An explanation for this observation is

252

that the obese group involved a younger population group at the time of primary THA possibly due to

253

earlier onset and accelerated progression of osteoarthritis.(5-10, 41, 47, 48, 51, 53, 63, 65, 68, 71)

254

Hence, bone density of the obese population is likely to be better. Younger patients are also found to

255

have a lower risk of revision for peri-prosthetic fracture than the older population.(73) Furthermore,

256

according to Wolff’s law, the increased loading on weight bearing long bones such as the femur will

257

further stimulate bone remodelling for additional strength and stiffness to resist the increased load.(77)

258

While it is postulated that larger forces acting on the prosthesis in obese patients may lead to aseptic

259

loosening, obese patients have been found to be associated with lower activity levels.(27, 45, 59) Since

260

aseptic loosening is a function of use and loading, the reduced activity level may lead to overall lower

261

force acting on the prosthesis. Moreover, a younger patient with superior bone quality may afford

262

better osseointegration of the implants at time of index THA. Both of these could have a synergistic

263

effect, thus leading to similar rates of aseptic loosening.

264 265

Despite obese patients having an associated lower activity level, the rate of VTE is also not

266

significantly higher in the obese than non-obese group. This could be explained by increased vigilance

267

that doctors place on ensuring that VTE prophylaxis is administered for these patients in acute hospital.

268

Guidelines that suggest that obesity has a moderate association with VTE(22, 23) may have led to

269

increased use of VTE prophylaxis in this group.

9

270

Interestingly, it is noted that the significantly higher rate of discharge to IRF in obese patients could

271

also be a driver of complications post THA. A recent meta-analysis by Onggo(78) found that patients

272

discharged to IRF have 4.87 and 2.82 times the risk of readmissions and peri-prosthetic complications

273

(including dislocations) post joint replacement surgeries. Hence, discharge destination may be a

274

significant confounder of this result.

275 276

This study has confirmed and expanded on previous reports of the complications of THA in patients

277

with obesity. However, there is little documented evidence to suggest the efficacy of weight loss prior

278

to THA in order to reduce the occurrence of complications. A recent meta-analysis reflected that

279

bariatric surgery prior to THA for the obese and morbidly obese population was not effective in

280

reducing the post-operative complication rates or improving clinical outcomes.(79) This lack of

281

reduction in complications suggests that the metabolic consequences of having been obese for so long

282

would require a substantial amount of time for the patient to recover. Hence, the health benefits would

283

significantly lag behind the weight loss from bariatric surgery prior to THA. Nevertheless, weight loss

284

from prior bariatric surgery may reduce operative time, length of stay, need for inpatient rehab,

285

unplanned re-admissions, and re-operations.

286 287

The result of this comprehensive analysis aims to raise awareness amongst general practitioners,

288

physicians and orthopaedic surgeons about the risks of hip replacement surgery in this population. The

289

authors believe that the results from this study should not be used to avoid performing THA in the

290

obese population, but rather to use this information in the shared informed consent process for this

291

patient group. The information may also allow surgeons and peri-operative physicians to be prepared

292

for these complications and better respond to them if or when they actually occur.

293 294

There are limitations to this analysis. Firstly, 66 of 67 included studies did not have a randomised

295

prospective study design, with 39 studies having a retrospective study design. Hence, selection and

296

recall bias cannot be completely excluded. The use of multicentre national registry based data in 23

297

studies may also lead to lower complication detection rates due to the issues of underreporting or

298

misreporting of complications, leading to Type 2 errors and an underestimation of the true association

299

between obesity and complications post THA. Furthermore, BMI is not a true representation of health

10

300

or fitness level and the cut-off of 30kg/m2 is an arbitrary value that is used for convenience and based

301

on preferred consensus rather than scientific reasoning. Since BMI is a dynamic parameter based on

302

height and weight of each patient, the effect of BMI changes post THA on the long-term rates of

303

complications and PROMs were not reported. This is important to investigate in future since there can

304

be considerable weight loss or gain post THA,(25) which may bring patients across the cut-off value of

305

BMI 30kg/m2. This also increases the complexity of issues surrounding data collection, whether

306

complications should be accounted for based on BMI groups measured pre-operatively, post-

307

operatively or dynamically during each follow-up visit. There are also differences in what is considered

308

to be the upper limit of healthy BMI amongst patients of various ethnic backgrounds.(80-82) This

309

consideration was not incorporated in our study analysis despite involving patients of various

310

backgrounds.

311 312

The heterogeneity of study protocols, patient demographics, clinical outcome measures and follow-up

313

timeframes could have also influenced the accuracy and reliability of evidence presented. Furthermore,

314

obese patients, due to the associated lower activity rate, are less likely to engage in early intensive

315

rehabilitation as compared to non-obese patients. As such, their recovery may take longer and show

316

significant differences in functional outcome measures, particularly in the early post-operative period.

317

Furthermore, explicit adjustment for confounders and factors known to influence outcomes following

318

THA was not performed due to the lack of raw data. This included factors such as gender differences,

319

method of anaesthesia, surgical approach, medical co-morbidities associated with obesity, prosthesis

320

choice, use of antibiotic prophylaxis, deep vein thrombosis prophylaxis, intra-operative use of

321

tranexamic acid to control bleeding and surgeon volume amongst others. However, it is unlikely that

322

there was significant variation in the type of prostheses or surgical volume between non-obese and

323

obese patients. Established co-morbidities associated with obesity such as diabetes, can also have great

324

impact on the outcomes of THA in the obese population. The statistically significant difference in

325

diabetes prevalence between obese and non-obese patients could be the driving force for higher rates of

326

complications, especially with higher BMI levels. Unfortunately, we were unable to adjust for the

327

difference in prevalence of diabetes and future studies could investigate the control of co-morbidities,

328

for example, glycated haemoglobin (HbA1c) levels for diabetic patients, to stratify the risks of these

329

co-morbidities at different severity levels. There were also insufficient reporting of raw data for

11

330

clinical outcomes and some specific complications. Hence, a meta-analysis was only performed on

331

complications and peri-operative parameters with sufficient data.

332 333

CONCLUSION

334

Obese and morbidly obese patients are at higher risks of complications post THA than non-obese

335

patients. Surgeons should be aware of increased risks of superficial and deep infections, dislocations,

336

readmissions, all-cause revisions and unplanned reoperations in order to counsel patients and adopt

337

prophylactic strategies into clinical practice to reduce these risks where possible.

338 339

Words: 3296

340 341

ACKNOWLEDGEMENTS:

342

There are no other acknowledgements to make

343 344 345

CONTRIBUTIONS: •

Corresponding author: Conception and design, analysis and interpretation of data, drafting of

346

article, critical revision of article, final approval of article, statistical expertise, collection and

347

assembly of data

348

•

349

2nd author: Conception and design, analysis and interpretation of data, drafting of article, critical revision of article, final approval of article, collection and assembly of data

350

•

3rd author: Conception and design, critical revision of article, final approval of article

351

•

Supervising author: Conception and design, critical revision of article, final approval of article

352 353

FUNDING:

354

None to declare.

355 356

COMPETING INTERESTS:

357

None to declare.

358 359

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Figure Legends Figure 1. PRISMA Chart Figure 2. All complications Figure 3. Deep infection Figure 4. All complications (subgroup analysis) Figure 5. Deep infections (subgroup analysis)

Appendix 1.1. Mean age difference Appendix 1.2. Mean age difference (subgroup analysis) Appendix 1.3. Diabetic rates Appendix 1.4. Diabetic rates (subgroup analysis)

Appendix 2. MINORS score

Appendix 3.1. Superficial/wound issues Appendix 3.2. Dislocations Appendix 3.3. Reoperations Appendix 3.4. Revisions Appendix 3.5. Readmissions Appendix 3.6. Venous thromboembolism Appendix 3.7. Peri-prosthetic fracture Appendix 3.8. Aseptic loosening Appendix 3.9. Nerve palsies

Appendix 4.1. Superficial/wound issues (subgroup analysis) Appendix 4.2. Reoperations (subgroup analysis) Appendix 4.3. Revisions (subgroup analysis) Appendix 4.4. Dislocation (subgroup analysis) Appendix 4.5. Readmissions (subgroup analysis) Appendix 4.6. Venous thromboembolism (subgroup analysis) Appendix 4.7. Peri-prosthetic fractures (subgroup analysis) Appendix 4.8. Aseptic loosening (subgroup analysis)

Appendix 5.1. All complications (Morbidly Obese vs Obese)

Appendix 5.2. Deep infection (Morbidly Obese vs Obese) Appendix 5.3. Reoperations (Morbidly Obese vs Obese) Appendix 5.4. Superficial/wound issues (Morbidly Obese vs Obese) Appendix 5.5. Peri-prosthetic fractures (Morbidly Obese vs Obese) Appendix 5.6. Revisions (Morbidly Obese vs Obese) Appendix 5.7. Dislocation (Morbidly Obese vs Obese) Appendix 5.8. Venous thromboembolism (Morbidly Obese vs Obese) Appendix 5.9. Readmissions (Morbidly Obese vs Obese) Appendix 5.10. Aseptic loosening (Morbidly Obese vs Obese)

Appendix 6.1. Operative time Appendix 6.2. Length of stay Appendix 6.3. Mean blood loss Appendix 6.4. Operative time (subgroup analysis) Appendix 6.5. Length of stay (subgroup analysis) Appendix 6.6. Discharge to inpatient rehabilitation facilities Appendix 6.7. Discharge to inpatient rehabilitation facilities (subgroup analysis)

Table 1. Demographics Table 2. Patient reported outcome measures Table 3. Survivorship summary

Table 1. Demographics No of hips Articles

Year

Aderinto

2005

Adhikary

2016

Alvi

2015

Andrew Antoniadis Arsoy

2008 2018 2014

Azodi

2008

Study Design

No of patients BMI<30 BMI≥30

BMI<30

BMI≥30

30≤BMI<40

BMI≥40

81

59

-

27646

21829

19305

Mean Follow-up period (years)

Mean Age (years)

Male

Female

Male

Female

BMI<30

BMI≥30

-

28

53

26

33

68

67

pvalue >0.05

18280

3549

-

-

-

-

-

-

-

23562

18378

5184

-

-

-

-

-

-

1069 125 84

350 129 42

332 -

18 42

402 24

667 57

126 11

222 29

69.1 70 56.7

65.5 70 56,4

<0.001 0.66 >0.05

1813

272

-

-

1813

0

272

0

-

-

-

2.0 1.0 Peri-operative period only Peri-operative period only 3.0 5.0 5.0 2.0

BMI<30

BMI≥30

Bennett

2010

Prospective Retrospective registry Retrospective registry Prospective Case controlled Case controlled Retrospective registry Case controlled

35

35

-

35

8

21

8

21

61.4

61.6

>0.05

Bowditch

1999

Prospective

62

18

18

-

28

34

7

11

66

65

>0.05

Bradley

2014

Retrospective

158

94

77

17

-

-

-

-

Chan Chee Davis Deakin Dienstknecht (Bauer hip) Dienstknecht (Microhip) Dowsey Dowsey

1996 2010 2011 2018

Prospective Case controlled Prospective Retrospective

141 55 1096 516

25 55 521 390

350

40

60 12 181

81 41 335

8 12 143

17 41 207

71.4 63.7 70

63

>0.05 0.78 <0.001

2013

Prospective

42

41

-

-

14

28

17

24

61

61

0.983

0.3

2013

Prospective

36

15

-

-

12

24

5

10

62

61

0.983

0.3

2008 2010

746 277

461 194

417 173

44 21

116

161

69

125

68.6

67

0.18

Foster

2015

519

270

242

28

256

263

159

111

64

61.1

-

1.0 1.0 Peri-operative period only

Fu

2016

10997

9213

7617

1596

4553

6444

4530

4683

-

-

-

George

2017

Retrospective Prospective Retrospective registry Retrospective registry Retrospective registry

145514

160241

-

-

-

-

-

-

-

-

-

71.9

69

69*

-

68.1 63.6

3.0

Gurunathan

2018

Retrospective

580

384

329

55

308

272

185

199

69*

60*

<0.001

Hanly Haverkamp Hungerford Ibrahim

2016 2008 2014 2005

Retrospective Retrospective Retrospective Retrospective

186 373 93 179

39 42 43 164

-

39 -

85 87 40 48

101 286 53 114

9 12 23 58

30 30 20 93

67.2 65.3 59 69.6

61.4 64 58 66.4

<0.001 0.56 -

5.0 3.0 4.0

3.3 5.4

Peri-operative period only >2.0 14.9 2.0 >1

Issa Issa Iwata Jackson

2013 2016 2018 2009

Jameson (cemented)

2014

Jameson (uncemented)

2014

Jeschke

2018

Jibodh

2004

Jones Judge Judge

2012 2010 2014

Jung

2017

Kessler

2007

Khatod

2014

Lash Lehman

2013 1994

Li

2017

Lubbeke Lubbeke Maisongrosse McCalden McLaughlin

2007 2010 2015 2011 2006

McLawhorn

2017

Meller Michalka Motaghedi

2016 2012 2014

Murgatroyd

2014

Namba

2012

Oosting

2017

Pirruccio

2019

Rajgopal

2013

Case Controlled Case controlled Case controlled Retrospective Retrospective registry Retrospective registry Retrospective registry

46 144 31 1612

23 48 31 414

-

23 48 -

18 57 6 751

22 78 25 861

9 19 6 198

11 26 25 216

55 62.7 68

50 54 62.6 63

0.71 0.76 <0.001

1640

1016

-

-

615

1025

354

662

74.3

71.8

<0.001

>0.5

1738

1141

-

-

759

979

518

623

66.7

64.4

<0.001

>0.5

110628

20950

17343

3607

-

-

-

-

-

-

-

>1.0

Retrospective

123

84

66

18

56

67

30

54

65.7

62.1

<0.05

Prospective Prospective Prospective Retrospective registry Prospective Retrospective registry Prospective Retrospective Retrospective registry Prospective Prospective Retrospective Prospective Retrospective Retrospective registry Retrospective Retrospective Prospective Retrospective registry Retrospective registry

140 623 2027

91 202 652

213 699

11 47

-

-

-

-

-

-

-

5414

4024

3525

499

-

-

-

-

-

47

20

18

2

-

-

-

-

21574

14536

-

-

-

-

-

-

985 142

454 60

52

8

106

36

35

25

1293

747

657

90

530

763

314

1906 386 425 1859 103

589 117 77 1431 95

1225 -

206 -

811 157 123 803 40

1095 229 302 1056 63

302 54 22 700 58

Prospective Retrospective registry Case controlled

68.2

-

3.0 6.2 3.3 6.4

6.0 3.1 6.1

Peri-operative period only 3.0 1.0 >1

-

-

-

0.3

-

-

2.9*

48

50.3

-

1.0 4.1

433

66.4

63.1

0.006

>0.5

287 63 55 731 37

69 69 77.2 69.6 57

67.2 64.3 74.5 64.4 54

<0.05 0.08 <0.001 -

63.6 67.5

3.5

3.4 7.9

4.5

4.9 8.4

14.3

14.6

1944

789

716

73

840

1104

411

378

66.2

63.9

<0.001

>2.0

376682 113 40

10712 78 20

-

10712 -

144607 47 -

232075 66 -

3382 37 -

7330 41 -

74.7 67.7

70.4 67

0.53 -

0.1 <0.01

3393

1964

1745

219

1560

1833

932

1032

68

64

<0.001

1.0 to 2.0

17831

11896

-

-

-

-

-

-

-

-

-

-

243

54

-

-

80

163

15

39

68.6

68.5

>0.05

Peri-operative period only

39293

39293

-

8492

18280

21013

18280

21013

-

-

-

39

78

39

39

6

33

22

56

53.1

52.8

0.98

64

0.1 5.0

4.3

Rapahel

2013

30

20

Retrospective 113 79 Retrospective 434 356 Retrospective 485 137 Retrospective 2001 354 197 Stickles registry 2014 Case controlled 1154 266 Tai Retrospective 2011 21414 4855 Traina registry Retrospective 2014 22087 9730 Wallace registry Retrospective 2017 702360 189207 Werner registry 2015 Prospective 118 76 Wu 2010 Retrospective 1612 414 Yeung Retrospective 2018 55459 45501 Zusmanovich registry BMI = Body mass index, * = values presented in median, - = data not available Russo Shaparin Stevens

2015 2016 2012

Prospective

17

3

24

29

21

25

-

-

-

71 302 -

8 54 -

199 127

235 358

141 37

215 100

62.6 64.3 70.4

58.5 61.2 69.5

0.02 >0.05

Peri-operative period only 0.1 0.1 1.0

170

27

-

-

-

-

70.2

66.4

-

1.0

69.2*

62.4*

<0.001

10.9

-

-

-

-

489

115

571

126

4668

187

8641

12773

2105

2750

9033

697

8374

13713

3713

6017

70.1

66.6

-

0.5

123407

65800

273920

428440

69371

119836

-

-

-

-

76 -

0 -

32 758

83 854

29 199

44 215

69.9 68

68.3 63

<0.001

5.0 >2.0

38206

7295

-

-

-

-

-

-

-

0.1

70

Table 2. Patient reported outcome measures Articles

Number of hip BMI<30 BMI≥30 BMI≥40

Aderinto 2005

81

59

-

Andrew 2008

1069

350

18

Antoniadis 2018

Arsoy 2014

Bennett 2010

125

84

35

129

42

35

-

42

35

Chee 2010

55

55

-

Deakin 2018

516

390

40

Outcome measure

BMI<30

BMI≥30

BMI≥40

p-value

Pre-op HHS 3 year HHS Pre-op OHS 5 year OHS

44 90 43.3 (8.0) 19.4 (8.6)

42.5 85 46.2 (7.1) 22.2 (9.3)

>0.05 <0.01 <0.001 0.005

5 year change in OHS

23.7 (9.4)

23.7 (9.7)

Pre-op HHS Post-op HHS Post-op change in weight (kg)

42 (9.2) 97 (3.2) 1.9 (6.4)

60 (8.7) 95 (4.1) 4.2 (22.5) 33.9 (12.8) 74.9 (16.5) 39.7 (20.0) 50.7 (5.2) 26.2 (10.2) 24.7 (9.8) 73.7 (16.7) 90.3 (8.7) 17 (18.5) 6.6 (7.7) 26.6 (10.4) 20 (11.9) 10.4 (9.2) 29.8 (8.6) 19 (13.2) 85 48.1 41 (8) 0.450 (0.220) 0.883 (0.161) 88 (12) 88 (12) 19 (8) 41 (6) 0.429 (0.192) 0.886 (0.164) 46 (16) 88 (11) 18 (7) 43 (5) 35.4 (10.7) 79.8 (17.0) 44.1 (16.8) 0.43 (0.29) 0.68 (0.28) 72 (20) 77 (18) 4.6 (1.9) 5.3 (1.9) 59.1 (7.9) 85 (9) 39 84 39

46.7 (6.4) 25.6 (9.9) 20.7 (10.8) 4.2 (22.5) 33.9 (12.8) 74.9 (16.5) 39.7 (20.0) 50.7 (5.2) 26.2 (10.2) 24.7 (9.8) 73.7 (16.7) 90.3 (8.7) 17 (18.5) 6.6 (7.7) 26.6 (10.4) 20 (11.9) 10.4 (9.2) 29.8 (8.6) 19 (13.2) 39 (8) -

0.774

-

0.855

-

0.773 0.718 0.381 0.684

-

0.774

-

0.855

-

0.773 0.718 0.381 0.684

30.2 (8.9)

0.03

Pre-op HHS

55.1 (10.2)

Post-op HHS

89.6 (14.0)

Post-op change in HHS

34.6 (12.0)

Pre-op OHS

46.5 (6.8)

1 year OHS

22.3 (8.7)

1 year change in OHS

24.2 (9.6(

Pre-op ROM

72.6 (19.2)

1 year ROM 1 year change in ROM Pre-op external rotation

97.4 (9.9) 27 (18.8) 6.9 (7.3)

1 year external rotation

32.6 (9.6)

1 year change in external rotation Pre-op internal rotation 1 year internal rotation 1 year change in internal rotation 5 year HHS 5 year change in HHS 1 year OHS

Pre-op HHS 3 month HHS Pre-op OHS 3 month OHS

26 (13.5) 10.3 (8.1) 32.7 (8.9) 23 (12.6) 91 52 34 (7) 0.428 (0.285) 0.810 (0.277) 48 (15) 84 (18) 20 (8) 39 (10) 0.500 (0.254) 0.842 (0.241) 46 (16) 88 (16) 21 (8) 42 (6)

Pre-op HHS

36.6 (11.4)

1 year HHS

80.8 (16.9)

1 year change in HHS

44.1 (18.0)

Pre-op EQ-5D index

0.49 (0.3)

Post-op EQ-5D index

0.75 (0.25)

Pre-op EQ-5D VAS Post-op EQ-5D VAS Pre-op UCLA activity Post-op UCLA activity Pre-op HHS 6 week HHS Pre-op HHS Post-op HHS Pre-op HHS

75 (18) 83 (14) 5.0 (2.3) 5.8 (2.1) 57.1 (11.2) 84 (11) 41 91 41

Pre-op EQ-5D index Dienstknecht (Bauer hip) 2013

3 month EQ-5D index 42

41

-

Pre-op HHS 3 month HHS Pre-op OHS 3 month OHS Pre-op EQ-5D index

Dienstknecht (Microhip)2013

3 month EQ-5D index 36

15

-

44 Dowsey 2010

746

461

Foster 2015

349

155

10

Hungerford 2014

93

43

Issa 2013

46

23

23

Issa 2016

144

48

48

-

70.5 (18.8) 40.3 (18.3) 0.41 (0.31)

0.473 0.001 0.07 0.03 <0.01 <0.01 0.17 0.011 0.06 0.78 0.8 0.003 0.02 0.98 0.004 0.02 0.97 0.054 0.09 0.01 0.825 0.001

0.03 0.63 -

0.71 (0.3)

-

72 (13) 74 (13) 3.6 (1.6) 6.0 (2.4) 39 84 39

0.393 0.476 <0.05 <0.05 0.42

Iwata 2018

31

31

-

Post-op HHS Post-op SF-36, mental Post-op SF-36, physical Pre-op UCLA activity Post-op UCLA activity Pre-op Merle d'Aubigne and Postel score Post-op Merle d'Aubigne and Postel score Post-op HHS Post-op flexion

Jackson 2009

Jameson 2014

Jameson 2014

1612

1640

1738

414

1016

1141

-

-

-

91

-

Judge 2010

623

202

11

Judge 2014

2027

652

47

Kessler 2007

47

20

2

-

Li 2017

1293

747

90

Lubbeke 2007

589

1906

-

8.71

-

0.75

17.19

16.74

-

0.097

93.2 (7.9)

-

<0.001

-

<0.001

-

0.192

-

0.011 0.25 0.008

-

<0.001

-

<0.001

-

<0.001

-

<0.001

-

<0.001 <0.001

-

<0.001

-

<0.001

-

<0.001

-

<0.001

-

<0.001

-

<0.001

59.2 14.1 12.8

89.9 (8.9) 113.1 (16.9) 31.0 (10.8) 23.2 (6.7) 24.7 (8.9) 11.2 (7.9) 0.305 (0.315) 0.728 (0.235) 60.8 (20.7 70.7 (18.6) 15.3 (7.4) 35.7 (9.6) 0.253 (0.316) 0.705 (0.306) 60.1 (22.7) 70.9 (20.6) 15.1 (7.3) 37.0 (10.1) 60.5 25.7 13.7

-

>0.20 0.01 >0.20

42.8

38.7

-

-

62.3 19.5 18

63 35.2 24.3

-

>0.20 <0.001 >0.20

122.5 (18.1)

Pre-op EQ-5D index (cemented)

0.392(0.307)

Post-op EQ-5D index (cemented)

0.779 (0.217)

Pre-op EQ-5D VAS (cemented)

68.3 (19.2)

Post-op EQ-5D VAS (cemented)

76.6 (17.4)

Pre-op OHS (cemented) Post-op OHS (cemented) Pre-op EQ-5D index (uncemented) Post-op EQ-5D index (uncemented)

19.2 (8.1) 39.4 (8.3) 0.414 (0.306) 0.823 (0.228)

Pre-op EQ-5D VAS (uncemented)

68.5 (20.1)

Pre-op WOMAC pain score 6 month WOMAC pain score 3 year WOMAC pain score 3 year change in WOMAC pain score Pre-op WOMAC function score 6 month WOMAC function score 3 year WOMAC function score 3 year change in WOMAC function score Pre-op WOMAC 1 year WOMAC 1 year change in WOMAC score Pre-op OHS 1 year OHS Pre-op WOMAC score 3 month WOMAC score

1 year WOMAC score 454

8.58

25.2 (6.1) 23.6 (9.1) 14.0 (8.5)

1 year change in OHS

985

0.002 0.001 0.001 0.001 0.001

Post-op adduction Post-op external rotation Post-op internal rotation

1 year OHS

Lash 2013

82 46 39 2.2 3.9

32.5 (6.9)

Post-op OHS (uncemented)

140

82 46 39 2.2 3.9

Post-op abduction

Post-op EQ-5D VAS (uncemented) Pre-op OHS (uncemented)

Jones 2012

91 58 49 3.5 6.2

1 year change in WOMAC score

78.6 (17.3) 19.9 (8.1) 40.8 (8.1)

39.1

31.3

-

-

57.6* 13.5* 37.5* 17.02 40.04 58 (24) 8 (8)

61.5* 22.9* 33.3* 13.69 35.9 57 (16) 17 (19) 39.75 (7.03) 24.6 (8.9) 79.06 (14.27) 46.95 (17.38) 10.46 (1.92) 7.74 (2.69) 28.3 41.2 45.5 88.4 48.0 (14.8) 87.4

68,1* 14.1* 56.1* 12.25 36.43 -

0.012 0.012 0.012 0.51 0.33

-

0.0039

42 (6.52) 23.64 (8.64) 82.78 (13.51) 46.39 (17.38)

1 year HAAS

10.51 (2.08)

1 year change in HAAS

7.07 (2.84)

Pre-op SF-36, physical 6 month SF-36, physical pre-op pain VAS 6 month pain VAS

32.7 46.5 51.1 90.6

pre-op HHS (men)

50.9 (16.2)

5 year HHS (men)

90.5 (13.0)

-

0.3474

-

0.0014

-

0.8447

-

0.836

-

0.0435

26.6 39.6 38.2 88.4

<0.001 <0.001 <0.001 >0.05

-

>0.05

-

>0.05

Lubbeke 2010

Maisongrosse 2005

McCalden 2011

McLaughlin 2006

McLawhorn 2017

Michalka 2012

386

425

1859

103

1944

113

117

77

1431

95

789

78

-

-

206

-

Pre-op HHS (women)

45.5 (14.3)

5 year HHS (women)

87.8 (13.2)

5 year HHS

91.4 (11.5)

10 year HHS

87.3 (12.8)

Pre-op Merle d'Aubigne and Postel score 5 year Merle d'Aubigne and Postel score 10 year Merle d'Aubigne and Postel score Post-op UCLA score Post-op HHS

15.7 (2.4)

15.5 (2.3)

-

0.729

5.5 (2.0)

5.0 (1.7) 68.8 (13.7) 44.2 (13.22) 87,6 (10.9) 43.7 (14.6) 39.9 (15.4) 40.6 (20.0) 52 89 0.62 (0.01 0.87 (0.01) 0.25 (0.01) 71.97 (0.82) 80.88 (0.64) 8.67 (0.80) 42.9 (7.11) 24.6 (10.0) 19.5 (11.2) 28.3 (5.93) 38.2 (9.00) 45.4 (12.58_ 53.5 (11.38) 311.7 (104) 2.9 (3.2) 1.7 (1.6) 179 (82) 39.05 (0.38) 50.3 52.6 2.4 27.8 40.4 12.7 44.4 79.3 34.9 52.4 (16.8)

-

-

-

0.30

70.9 (13.4)

Post-op change in WOMAC

39.2 (21.0) 53 89

Pre-op EQ-5D index

0.66 (0.01)

2 year EQ-5D index

0.90 (0.004)

2 year change in EQ-5D index

0.24 (0.01)

Pre-op EQ-5D VAS

76.62 (0.58)

2 year EQ-5D VAS

84.93 (0.47)

2 year change in EQ-5D VAS

8.23 (0.59)

Pre-op OHS

43.5 (7.23)

Post-op OHS

25.3 (8.13)

Post-op change in OHS

20.7 (13.4)

Pre-op SF-12, physical

28.8 (6.71)

Post-op SF-12, physical

38.5 (10.5)

Pre-op SF-12, mental

46.1 (11.82)

Post-op SF-12, mental

52.0 (11.14)

73

-

3393

1964

219

6 month OHS Pre-op SF-36, mental 1 year SF-36, mental 1 year change in SF-36, mental Pre-op SF-36, physical 1 year SF-36, physical 1 year change in SF-36, physical Pre-op WOMAC 1 year WOMAC score 1 year change in WOMAC score

Stickles 2001

354

197

27

Tai 2014

162

82

-

Pre-op HHS

0.08

0.367

41.0 (16.1)

Murgatroyd 2014

-

-

Pre-op WOMAC score

Pre-op pain VAS Post-op pain VAS PCA analgesia consumption (mL)

0.019

15.7 (1.9)

41.8 (14.7)

-

-

16.2 (2.1)

Post-op change in HHS

20

<0.05

0.001

88.3 (12.9)

40

-

-

Post-op HHS

Motaghedi 2014

<0.05

9.5 (1.8)

45.8 (15.2)

6MWT (m)

-

10.0 (1.8)

Pre-op HHS

Pre-op HHS Post-op HHS

(10.8) 44.6 (12.6) 79.6 (16.4) 85.1 (15.4) 83.6 (15.2)

319.1 (109.3) 3.4 (3.3) 2.1 (2.2) 193 (79) 41.31 (0.46) 52.6 53.8 1.1 28.5 42 13.5 48.4 80.3 31.8 58.7 (15.8)

35.7 (12.5) 86.4 (11.9) 49.2 (15.4) 32.4 (15.0) 48.9 (21.1) 0.54 (0.03) 0.85 (0.02) 0.31 (0.02) 67.79 (2.19) 76.03 (1.91) 8.12 (2.02) 46.9 (7.35) 24.0 (7.48) 24.0 (11.6) 28.1 (8.12) 39.8 (9.06) 42.2 (11.23) 46.8 (11.83) 249.0 (115.4) 36.7 (1.16) 50.4 53.2 2.9 23.9 37 13.1 39.9 75.9 35.9 -

<0.001 0.082 <0.001 <0.001 0.002 <0.0001 <0.0001 0.0216 <0.0001 <0.0001 0.4291 0.086 0.783 0.374 0.827 0.829 0.40 0.079 0.028 >0.05 >0.05 >0.05 <0.001 0.1352 0.2035 0.2545 0.0734 0.0274 0.4822 0.0286 0.0494 0.5352 0.006

88.9 0.001 (12.8) 36.5 Post-op change in HHS 35.3 (17.0) 0.668 (18.8) Post-op abduction 29.2 (8.0) 27.9 (6.5) 0.239 Post-op adduction 23.2 (5.6) 22.5 (5.1) 0.331 Post-op external rotation 24.5 (6.6) 25.6 (6.6) 0.182 Post-op internal rotation 13.1 (9.4) 10.9 (8.3) 0.07 Pre-op HHS 53 49 6 week HHS 80 78 6 month HHS 89 89 Pre-op LEAS 8.9 8.5 118 76 6 month LEAS 10.4 10.1 Wu 2015 Pre-op SF-12, physical 33.3 30 6 month SF-12, physical 47.6 46.6 Pre-op SF-12, mental 50.1 48.2 6 month SF-12, mental 54.6 54.2 1612 414 Post-op HHS 93.2 89.9 Yeung 2010 <0.001 HHS= Harris hip score, LEAS = Lower extremity activity scale, OHS = Oxford hip score, SF-36 = 36 Item Short Form Health Survery, VAS = Visual analog scale, UCLA = University of California, Los Angeles, WOMAC = Western Ontario and McMaster Universities Osteoarthritis Index, 6MWT = 6 minute walking test, * = Median values presented in Post-op HHS

94.1 (7.1)

Table 3. Survivorship summary Articles Chee 2010 Haverkamp 2008 Issa 2013 Issa 2016 Jackson 2009 McCalden 2011

McLaughlin 2006 Yeung 2010

All-cause survivorship BMI<30 BMI≥30 5 year = 100% 5 year = 90.9% 10 year = 94.9% 10 year = 91.0% 15 year = 85.9% 15 year = 79.5% 20 year = 75.6% 20 year = 79.5% 3 year = 100% 3 year = 96% 6 year = 97.8% 6 year = 89.6% 11 year= 95.2%

11 year = 96.7%

1 year = 99.1% 2 year = 99.1% 5 year = 97.6% 10 year = 97.6% 15 year = 93.7% 18 year = 95% (femoral) 18 year = 26 % (acetabular) 11 year = 95.2%

1 year = 98.9% 2 year = 98.3% 5 year = 97.1% 10 year = 94.6% 15 year = 91.1% 18 year = 94% (femoral) 18 year = 39% (Acetabular) 11 year = 96.7%