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Functional outcomes following surgical-site infections after operative fixation of closed ankle fractures
Accepted Manuscript Title: Functional outcomes following surgical-site infections after operative fixation of closed ankle fractures Author: Markus G. Naumann Ulf Sigurdsen Stein Erik Utv˚ag Knut Stavem PII: DOI: Reference:
S1268-7731(16)30450-7 http://dx.doi.org/doi:10.1016/j.fas.2016.10.002 FAS 968
To appear in:
Foot and Ankle Surgery
Received date: Revised date: Accepted date:
30-6-2016 5-10-2016 16-10-2016
Please cite this article as: Naumann Markus G, Sigurdsen Ulf, Utv˚ag Stein Erik, Stavem Knut.Functional outcomes following surgical-site infections after operative fixation of closed ankle fractures.Foot and Ankle Surgery http://dx.doi.org/10.1016/j.fas.2016.10.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. 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.
Functional outcomes following surgical-site infections after operative fixation of closed ankle fractures
Markus G Naumann, MD1 Ulf Sigurdsen, MD, PhD2 Stein Erik Utvåg, MD, PhD2,3 Knut Stavem, MD, MPH, PhD3,4,5
1
Department of Orthopaedics, Østfold Hospital, Norway
2
Department of Orthopaedics, Akershus University Hospital, Norway
3
Institute of Clinical Medicine, University of Oslo, Norway
4
Department of Pulmonary Medicine, Medical Division, Akershus University Hospital,
Norway 5
Health Services Research Unit, Akershus University Hospital, Norway
Corresponding author: Markus G Naumann, Department of Orthopaedics, Østfold Hospital, Postboks 300, 1714 Grålum, Norway Email: [email protected] Tel.: +47-47263913 1
Highlights
The study assessed functional outcomes 3 to 6 years after ankle surgery
Computerized charts were reviewed to identify superficial and deep infections (SSI)
Superficial and deep SSIs occurring within 6 months of surgery were analysed
A deep SSI was associated with worse functional outcomes on three different scales
2
Functional outcomes following surgical-site infections after operative fixation of closed ankle fractures
Abstract Background To compare the functional outcomes between patients with and without postoperative surgical-site infection (SSI) after surgical treatment in closed ankle fractures. Methods Retrospective cohort study with prospective follow-up. Of 1,011 treated patients, 959 were eligible for inclusion in a postal survey. Functional outcomes were assessed using three self-reported questionnaires. Results In total 567 patients responded a median of 4.3 years (range 2.7 to 6.2 years) after surgery. In total 29/567 had an SSI. The mean Olerud and Molander Ankle Score was 19.8 points lower for patients with a deep SSI (p=0.02), the Lower Extremity Functional Scale score was 10.2 points lower (p<0.01) and the Self-Reported Foot & Ankle Questionnaire score was 5.0 points higher (p=0.10) than for those without an SSI, after adjusting for age, sex, smoking status, diabetes, physical status, fracture classification and duration of surgery. Conclusions Patients with a deep SSI had worse long-term functional outcomes than those without an SSI.
Keywords Surgical site infection Closed ankle fracture ORIF Functional outcome Questionnaire OMAS
3
LEFS SEFAS
4
1. Introduction Ankle fractures are common injuries that constitute approximately 9% of all fractures, with an estimated incidence of 101–108 per 100,000 inhabitants per year [1,2]. About 50% of ankle fractures require surgical stabilization with open reduction and internal fixation (ORIF) [2,3]. Surgical-site infections (SSIs) in closed ankle fractures treated by ORIF are common, reportedly afflicting from 1.4% to 9.8% of patients [4-9]. The influence of postoperative infections on the functional outcomes in patients with closed ankle fractures treated by ORIF has received little attention. In a case series of Weber type-B ankle fractures, the functional outcome scores were lower for patients with infectious complications than for those without infections [10]. A recent case–control study found that the self-reported functional outcome scores were lower for patients with postoperative infections following ORIF in ankle fractures than in age- and gender-matched patients without infectious complications [11]. However, both of these studies included only a small number of patients in the analysis of functional outcomes and did not use multivariable analysis [10,11] which means that the results may have been influenced by other differences between the comparison groups. The objective of the present study was to determine whether patients with an SSI have lower self-reported outcome scores than those without infection following ORIF in closed ankle fractures, adjusting for possible confounding variables. The study involved a crosssectional survey of a large retrospective cohort of patients with fractures of the ankle in two Norwegian hospitals.
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2. Material and methods 2.1. Subjects and study design This was a retrospective cohort study of patients who received surgical treatment (ORIF) for unstable and closed ankle fractures at two Norwegian hospitals, Østfold Hospital and Akershus University Hospital. These hospitals have a combined geographical catchment area of about 730,000 inhabitants, and all patients 18 years of age living in the catchment area who were treated for unstable and closed ankle fractures by ORIF between January 1, 2009 and December 31, 2011 were eligible for inclusion in the study. Patients were selected from the information systems of the hospitals using discharge diagnoses (10th revision of the International Classification of Diseases: codes S82.3–S82.9, S93.2 and S93.4)[12] combined with surgical procedure codes (Nordic Medico-Statistical Committee Classification of Surgical Procedures: codes NHJ00–NHJ98 and NHE 99) [13]. In total, 1,149 patients were eligible for chart review. We excluded 128 patients living outside the hospitals’ catchment area or who were misclassified and 62 patients, who were unable to respond to questionnaires because they had cognitive problems, could not use the other leg for comparison, had moved out of the area or had died. Details of the exclusions are shown in Fig. 1. After exclusions, 959 patients were eligible for inclusion in a postal survey. We mailed a questionnaire to the participants in January 2015, and 4 weeks later we sent a reminder to the non-respondents. The questionnaire included the Olerud and Molander Ankle Score (OMAS), the Lower Extremity Functional Scale (LEFS) and the Self-reported Foot & Ankle Questionnaire (SEFAS) and items about demographics. In total, 567 patients (59.1% of those eligible) completed the questionnaire, 345 patients did not respond and 47 questionnaires were returned unopened due to incorrect addresses (Fig. 1).
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The study was approved by the Norwegian Social Science Data Services (approval no. 28813/5) and the Regional Committees for Medical and Health Research Ethics, Health Region South East (approval no. 2012/384).
2.2. Variables and classifications 2.2.1. Medical record review and variables All electronic medical records and radiographs were reviewed by one of the authors (M.G.N. or U.S.) to verify the recorded diagnosis and procedures and to collect information on demographics (age at trauma and sex), physical status before surgery [American Society of Anesthesiologists (ASA) class I–III: I, completely healthy fit; II, mild systemic disease; and III, severe systemic disease] [14], diabetes (yes or no), current smoking status (yes, no or unknown), fracture classification (see below), treating hospital and whether surgery was performed within 8 hours of trauma. Finally, we recorded the number of in-hospital days, preoperative antibiotics given (yes or no), insertion of one or more syndesmosis screws (yes or no), and the duration of surgery (in minutes). 2.2.2. Fracture treatment and classification The patients in both hospitals were treated according to the recommendations of the Swiss Arbeitsgemeinschaft für Osteosynthesefragen (AO) and the American Orthopaedic Trauma Association (OTA). The radiographs of the patients were classified for descriptive purposes using the Weber classification and into uni-, bi- and trimalleolar fractures [15]. 2.2.3. Surgical site infections We classified SSIs as superficial or deep infectious complications occurring within 6 months after the day of ankle surgery. More specifically, superficial infections were defined as minor wound complications that could be treated conservatively without surgical intervention while deep infections were defined as major wound complications and needing surgical treatment. 7
2.2.4. Assessment of functional outcomes The subjects completed three different questionnaires to assess functional outcomes, as described below.
Olerud and Molander Ankle Score The OMAS was designed to assess symptoms and function after ankle fractures. It consists of items that are scored in the following domains with ordinal scales: pain (0–25), stiffness (0– 10), swelling (0–10), stair climbing (0–10), running (0–5), jumping (0–5), squatting (0–5), supports (0–10) and work/activity level (0–20). The item scores are summed to produce a total score ranging from 0 (totally impaired) to 100 (completely unimpaired). Each item is scored so as to represent the degree of disability. The total score can be categorized as poor (0–30), fair (31–60), good (61–90) or excellent (91–100) [16]. The OMAS has documented reliability, validity and responsiveness in studies of ankle fractures [17].
Lower Extremity Functional Scale The LEFS comprises 20 items related to the ability to perform everyday activities that are scored on the following scale: extreme difficulty or unable to perform activity (0), severe difficulty (1), moderate difficulty (2), minor difficulty (3) and no difficulty (4). The items are summed to produce a total score ranging from 0 (very poor function) to 80 (very good function) [18]. The reliability, construct validity and responsiveness of the LEFS have been documented in people with ankle sprains and a general population with lower-extremity musculoskeletal dysfunction [19,20]. The smallest detectable change is 9 scale points, which is also the smallest clinically important difference [18].
Self-reported Foot & Ankle Questionnaire 8
The SEFAS is a slightly modified version of the Oxford-12 questionnaire for total hip replacement [21]. Each of the 12 questions was scored on an ordinal scale from 1 to 5, with the scores summed to produce a total score ranging from 12 (normal function) to 60 (most severe disability)[22]. The SEFAS was developed in patients undergoing total ankle replacements and has been validated in patients with disorders of the toe, ankle or hindfoot [23].
2.3. Statistical analysis The characteristics of the patients, their fractures and their surgery are presented as mean (range), median (interquartile range) or number (%) values, as appropriate. Descriptive variables for respondents and non-respondents and for subjects with and without SSIs were compared using the t-test (for normally distributed data) or Mann-Whitney U test (for nonnormally distributed data) for continuous variables, or Fisher’s exact test for categorical variables. The association of infection status with self-reported outcomes (OMAS and scores on the LEFS and SEFAS) were analysed using multivariable linear regression analysis. We assessed the effect of infection using two dummy variables for superficial and deep infection, respectively. In multivariable models, we adjusted for the following covariates: age, sex, current smoking status (yes vs. no, subjects with unknown smoking status were excluded), diabetes (yes vs. no), ASA class, fracture classification (Weber), fracture classification (uni-, bi- or trimalleolar fracture) and duration of surgery. We did not impute missing values before performing the modelling. In the regression models, the residuals showed some deviation from normal distributions. Log-transformation of the dependent variable did not materially improve this situation, and such a transformation would have also made the results more difficult to 9
interpret. We therefore used the untransformed values for the dependent variable, but used bootstrapped 95% confidence intervals, with 1000 replications, in all models. The threshold for statistical significance was set at p<0.05 in two-sided tests. All statistical analyses were conducted using the Stata software (version 14.1, Stata Corporation, College Station, TX, USA).
3. Results 3.1. Sample and respondents In total, 567 of 959 patients (59.1%) responded to the questionnaire. The median time between surgery and completion of the questionnaire was 4.3 years (interquartile range 3.9 to 5.1 years, range 2.7 to 6.2 years).Respondents were older than non-respondents with a mean age of 53.2 (SD15.1) years and 46.2 (17.5) years, respectively (p<0.001), were more likely to be current non-smokers (75% vs. 61%, p<0.001), and to have had surgery within 8 hours (33% vs. 27%, p=0.039). There were no differences between respondents and nonrespondents in sex, diabetes and fracture characteristics according to the uni-, bi-, trimalleolar and Weber classifications. The infection rate was 5.1% (29/567) for respondents and 5.1% (20/392) for non-respondents (p=0.56). Patients with an SSI were older, than those without an SSI. The fracture classifications, ASA class and length of stay did not differ between those with and without SSIs (Table 1).
3.2. Functional outcome scores In bivariate comparisons of functional outcome scores, patients without an infection had a higher OMAS and LEFS score and a lower score on the SEFAS than those with superficial or
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deep infection, which indicates that the functional outcomes were better for those without an SSI on all scales (Table 2). In multivariable analysis after adjusting for several variables, patients with a deep SSI had a lower OMAS score (p=0.017) and LEFS score (p=0.009) than those without deep SSI (Table 3), indicating a worse functional outcome. The patients with a deep SSI scored higher on the SEFAS (indicating a worse outcome) than those without, but this difference was not statistically significant (p=0.096). Those with superficial SSI had a slightly worse, although statistically non-significant, functional outcome than those without infection on the OMAS and SEFAS scales (Table 3). Current smoking, ASA class II and III and longer duration of surgery were associated with worse functional outcomes on the OMAS, LEFS and SEFAS. (Table 3)
4. Discussion The main finding in the present study was that the functional outcomes 3 to 6 years after surgery for closed ankle fractures were worse in those with a deep SSI than in those without an SSI. This finding was consistent and remained statistically significant after adjusting for several background variables and possible confounders. Relative to the previous studies, the present study surveyed patients in a historical cohort, had a larger number of respondents to the questionnaires, had a longer duration between surgery and follow-up, and applied multivariable analysis. We also used three distinct and validated questionnaires: the OMAS, SEFAS and LEFS. Our findings regarding the overall infection rate were consistent with those of previous studies, [4-9] though some previous studies also included patients with open fractures or polytrauma [6,9]. This finding supports previous studies that used different study designs, outcome measures and analytic approaches [4,10,11]. Høiness et al. reported lower subjective 11
functional scores on the OMAS for patients with soft-tissue injuries compared to patients without, though details for the scores were not reported [4]. In a case-series bivariate analysis, Schepers et al. found that the functional outcomes of Weber type-B ankle fractures on the OMAS and AOFAS (American Orthopaedic Foot & Ankle Society) scale were worse in patients with infectious complications than in those without infections [10]. In contrast, Korim et al. used a case–control design and showed that the OMAS at least 6 months after surgery was lower following ORIF in patients with ankle fractures and postoperative infections than in age- and gender-matched patients without infectious complications [11]. However, that study included some patients with open fractures, in contrast to the present study. The association between superficial SSI and functional outcome was smaller than for deep SSI. A superficial infection would be expected to be milder and of shorter duration than a deep infection, and in need of no surgical treatment. Hence, it seems reasonable that superficial infections have a smaller impact on functional outcome than deep infections. However, the number of infections in the present study was small, and the lack of statistical significance for the impact of superficial infection may possibly be related to the limited statistical power of the study. Current smoking, longer duration of surgery and ASA class II and III were associated with worse long-term functional outcomes after ORIF as assessed with the OMAS, SEFAS and LEFS in this study. The association of current smoking with worse functional outcomes in the present study supports the findings in a previous study that used a modified version of the ACFAS (American College of Foot and Ankle Surgeons) scoring scale [24]. A longer duration of surgery was associated with worse long-term functional outcomes in this cohort. We are not aware of any studies that have investigated the association between the duration of surgery for ankle fractures and long-term functional
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outcomes. Patients with more complicated fractures, greater comorbidity or who are operated on by less experienced surgeons may experience a longer duration of surgery and therefore may be at risk of worse functional outcomes. The present study controlled for some of these variables, but other influencing variables may also exist, and hence residual confounding may have been present. Finally, some important variables might not have been available for this retrospective study, such as functional status before surgery or more detailed information on comorbidity. Patients with greater comorbidity (i.e., in ASA class II or III) showed worse functional outcomes both on OMAS, LEFS and SEFAS. This pattern of association between ASA class and functional outcomes is in line with that reported 1 year after surgical treatment for ankle fractures using two other questionnaires [25]. The present study was large and was conducted in hospitals covering a geographical area that comprises about 14% of the Norwegian population. The rate of emigration from this area is low, and so few of the patients would have been followed up later in hospitals outside the area. We consider that the response rate to the questionnaires was acceptable and at the level that can be expected for this type of study. Moreover, there were few differences between respondents and non-respondents. Therefore, the results should be representative of the Norwegian setting, where ankle fractures are typically treated according to recommendations of the AO/OTA, as in many other Western countries. The three questionnaires used in the study are widely used, and the present findings were generally consistent across all three instruments. This study was subject to several limitations. The population was identified retrospectively, and variables were collected by a review of electronic medical records, which limits the number, quality and completeness of variables that can be collected. Therefore, some potentially relevant variables might not have been included. SSI was defined using
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established clinical criteria rather than being confirmed with bacterial cultures. The chart and radiograph reviews were performed by only one researcher, and the interrater reliability and validity for the data extracted from the medical records were not assessed. Covariates also could not be updated throughout the study, in contrast to what might be possible in a prospective study. Time-dependent covariates could therefore not be included in the analysis. Patients with an SSI had worse self-reported functional outcomes at 3–6 years after ORIF in closed ankle fracture than those without an SSI, and hence general measures to reduce the prevalence of SSIs may lead to an improved outcome in this population [26]. Some of the risk factors associated with poor functional outcomes, such as smoking and obesity, are modifiable and therefore may be influenced by public health interventions in the society or individual counselling. Applying such interventions immediately before surgery may have positive impacts on wound healing and infection rate, and may also lead to a better general condition and better functioning that may be reflected in better scores for the self-reported functional outcomes. As this study was a cross-sectional follow-up study, one should be careful with statements about causal associations between infection and functional outcome after about 4 years. Infection and concomitant inflammation may inhibit the healing process or callus formation, and thus lead to suboptimal fracture healing and long-term pain or swelling. Also it is possible that those with infection had prolonged immobilization of the leg, which may have contributed to prolonged stiffness and worse long-term functional outcome. Finally, there may still be confounding from unavailable variables. We speculate that better surgical skills or the use of enhanced surgical techniques may contribute to shortening the duration of surgery and improve long-term outcomes. However, this needs to be assessed in future prospective studies.
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In conclusion, this survey of patients in a historical cohort study found that patients with a deep SSI that occurred within 6 months following ORIF in closed ankle fractures reported worse functional outcomes on the OMAS, LEFS and SEFAS at a median of 4.3 years after surgery. This finding remained statistically significant after adjusting for several background variables and potential confounders. The study also found that current smoking, longer duration of surgery and ASA class II and II were associated with worse long-term functional outcomes.
Acknowledgements The project was partially funded by The Sophies Minde Foundation and Østfold Hospital. The sponsors had no involvement in study planning, collection, analysis, or interpretation of the data, or in the preparation, or approval of the manuscript
References [1] Court-Brown CM, Caesar B. Epidemiology of adult fractures: A review. Injury 2006;37:691-7. [2] Jensen SL, Andresen BK, Mencke S, Nielsen PT. Epidemiology of ankle fractures. A prospective population-based study of 212 cases in Aalborg, Denmark. Acta Orthop Scand 1998;69:48-50. [3] Sanders DW, Tieszer C, Corbett B. Operative versus nonoperative treatment of unstable lateral malleolar fractures: a randomized multicenter trial. J Orthop Trauma 2012;26:129-34. [4] Høiness P, Engebretsen L, Strømsøe K. The influence of perioperative soft tissue complications on the clinical outcome in surgically treated ankle fractures. Foot Ankle Int 2001;22:642-8.
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[5] Høiness P, Engebretsen L, Strømsøe K. Soft tissue problems in ankle fractures treated surgically. A prospective study of 154 consecutive closed ankle fractures. Injury 2003;34:92831. [6] Miller AG, Margules A, Raikin SM. Risk factors for wound complications after ankle fracture surgery. J Bone Joint Surg Am 2012;94:2047-52. [7] Ovaska MT, Makinen TJ, Madanat R, Vahlberg T, Hirvensalo E, Lindahl J. Predictors of poor outcomes following deep infection after internal fixation of ankle fractures. Injury 2013;44:1002-6. [8] Singh RA, Trickett R, Hodgson P. Early versus late surgery for closed ankle fractures. J Orthop Surg (Hong Kong) 2015;23:341-4. [9] SooHoo NF, Krenek L, Eagan MJ, Gurbani B, Ko CY, Zingmond DS. Complication rates following open reduction and internal fixation of ankle fractures. J Bone Joint Surg Am 2009;91:1042-9. [10] Schepers T, De Vries MR, Van Lieshout EM, Van der Elst M. The timing of ankle fracture surgery and the effect on infectious complications; a case series and systematic review of the literature. Int Orthop 2013;37:489-94. [11] Korim MT, Payne R, Bhatia M. A case-control study of surgical site infection following operative fixation of fractures of the ankle in a large U.K. trauma unit. Bone Joint J 2014;96b:636-40. [12] WHO-ICD10. ICD-10 International Statistical Classification of Diseases and Related Health Problems 10th Revision, http://apps.who.int/classifications/icd10/browse/2015/en 2015 [accessed 23 June 2016]. [13] Nordic Medico-Statistical Committee (NOMESCO). NOMESCO Classification of Surgical Procedures (NCSP), version 1.16, http://www.nordclass.se/NCSP_1_16.pdf 2011 [accessed 23 June 2016].
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[14] American Society of Anesthesiologists. Physical Status Classification System, http://www.asahq.org/resources/clinical-information/asa-physical-status-classification-system 2014 [accessed 23 June 2016]. [15] Broos P, Bisschop A. A new and easy classification system for ankle fractures. Int Surg 1992;77:309-12. [16] Olerud C, Molander H. A scoring scale for symptom evaluation after ankle fracture. Arch Orthop Trauma Surg 1984;103:190-4. [17] Nilsson GM, Eneroth M, Ekdahl CS. The Swedish version of OMAS is a reliable and valid outcome measure for patients with ankle fractures. BMC Musculoskelet Disord 2013;14:109. [18] Binkley JM, Stratford PW, Lott SA, Riddle DL. The Lower Extremity Functional Scale (LEFS): scale development, measurement properties, and clinical application. North American Orthopaedic Rehabilitation Research Network. Phys Ther 1999;79:371-83. [19] Lin CW, Moseley AM, Refshauge KM, Bundy AC. The lower extremity functional scale has good clinimetric properties in people with ankle fracture. Phys Ther 2009;89:580-8. [20] Alcock GK, Stratford PW. Validation of the Lower Extremity Functional Scale on athletic subjects with ankle sprains. Physiotherapy Canada 2002;54:233-40. [21] Dawson J, Fitzpatrick R, Carr A, Murray D. Questionnaire on the perceptions of patients about total hip replacement. J Bone Joint Surg Br 1996;78:185-90. [22] Hosman AH, Mason RB, Hobbs T, Rothwell AG. A New Zealand national joint registry review of 202 total ankle replacements followed for up to 6 years. Acta Orthop 2007;78:58491. [23] Coster MC, Rosengren BE, Bremander A, Brudin L, Karlsson MK. Comparison of the Self-reported Foot and Ankle Score (SEFAS) and the American Orthopedic Foot and Ankle Society Score (AOFAS). Foot Ankle Int 2014;35:1031-6.
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[24] Still GP, Atwood TC. Operative outcome of 41 ankle fractures: a retrospective analysis. J Foot Ankle Surg 2009;48:330-9. [25] Egol KA, Tejwani NC, Walsh MG, Capla EL, Koval KJ. Predictors of short-term functional outcome following ankle fracture surgery. J Bone Joint Surg Am 2006;88:974-9. [26] APIC Association for Professionals in Infection Control and Epidemiology. Guide to the elimination of orthopedic surgery surgical site infections, http://www.apic.org/Resource_/EliminationGuideForm/34e03612-d1e6-4214-a76be532c6fc3898/File/APIC-Ortho-Guide.pdf 2010 [accessed 23 June 2016].
Figure legend Figure 1. Flow chart of the study
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Tables Table 1. Respondent characteristics at admission and injury data. Data are number (%) values except where stated otherwise (n=567)
No infection Infection (n=29)
p (n=538)
61.0 (26.8 to Age, years, mean (range)
52.8 (18.1 to 85.7)
0.005***
302 (56)
0.19*
86.2) Sex, female
20 (69)
Treating hospital
0.52*
Akershus University Hospital
14 (48)
252 (47)
Østfold Hospital
15 (52)
286 (53)
Physical status, ASA class
0.098**
I Completely healthy fit
8 (28)
189 (35)
II Mild systemic disease
17 (59)
323 (60)
4 (14)
26 (5)
2 (7)
32 (6)
0.69*
10 (35)
126 (23)
0.22**
III Severe systemic disease Diabetes Current smoking Fractures, clinical features
0.76**
Lateral malleolus
10 (35)
231 (43)
Bimalleolar
8 (28)
120 (22)
Trimalleolar
8 (2)
130 (24)
Maisonneuve
2 (7)
44 (8)
Isolated syndesmosis rupture
0 (0)
7 (1)
Medial malleolus
1 (3)
6 (1)
19
Modified fracture classification1 (n=560)
0.69**
Unimalleolar
13 (45)
281 (52)
Bimalleolar
8 (28)
120 (22)
Trimalleolar
8 (28)
130 (24)
Fracture classification2 (n=554)
0.33**
A
2 (7)
13 (3)
B
21 (72)
362 (69)
C
6 (21)
150 (29)
Syndesmosis screw, one or two
16 (55)
271 (50)
0.70*
Preoperative antibiotics (n=566)
17 (59)
310 (58)
1.00*
5 (4 to 9)
5 (3 to 9)
0.22***
85 (60 to 117)
76 (53 to 106)
0.27***
Number of in-hospital days, median (IQR) Duration of surgery in minutes, median (IQR) *Fisher’s exact test, **Pearson chi-square test, ***Mann-Whitney U test, 1 Broos & Bisschop, 2
Weber
IQR=interquartile range, ASA=American Society of Anesthesiologists
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Table 2. Functional outcomes and quality-of-life measurements in 567 patients following open reduction and internal fixation (ORIF) in closed ankle fractures
No surgical-site infection
Superficial infection
Deep infection
n
Median
IQR
n
Median
IQR
n
Median
IQR
p*
OMAS (range 0–100) ¹
437
80
60–100
11
75
50-90
14
48
25-85
0.001
LEFS (range 0–80) ¹
514
74
61–79
13
64
62-76
15
48
38-74
0.004
SEFAS (range 12–60) ²
521
18
13–26
13
19
16-30
15
29
16-38
0.060
*Kruskal-Wallis-Test ¹ higher score denotes better function, ² lower score denotes better function OMAS=Olerud and Molander Ankle Score, LEFS=Lower Extremity Functional Scale, SEFAS=Self-Reported Foot & Ankle Questionnaire IQR=interquartile range
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Table 3 Functional outcomes at surveys performed at median of 4.3 years after ORIF in closed ankle fractures, multivariable linear regression analysis. OMAS (n=430)
LEFS (n=504)
SEFAS (n=511)
(range 0–100)
(range 0–80)
(range 12–60)
β Postoperative infection, superficial
95% CI
p
β
95% CI
p
β
95% CI
-5.7
(-21.9 to 7.3)
0.43
1.1
(-4.2 to 6.4)
0.68
1.2
Postoperative infection, deep
-19.8
(-35.2 to -4.1
0.017
-10.2
(-17.9 to -2.5)
0.009
5.0
Age, years
-0.02
(-0.2 to 0.1)
0.79
-0.2
(-0.3 to -0.1) <0.001
0.004
5.1
(0.2 to 10.0)
0.040
3.4
(0.6 to 6.3)
0.018
-1.4
(-3.2 to 0.4) 0.116
-6.00
(-11.5 to -0.2)
0.028
-4.5
(-7.7 to -1.2)
0.007
2.6
(0.6 to 4.6) 0.010
1.5
(-9.2 to 12.1)
0.79
-3.8
(-10.0 to 2.4)
0.23
2.0
-6.0
(-11.5 to -1.0)
0.018
-2.8
(-5.4 to -0.3)
0.029
2.6
(0.7 to 4.74) 0.006
-13.8
(-24.9 to -5.0)
0.003
-11.9
(-19.0 to -4.8)
0.001
6.0
(1.6 to 10.4) 0.008
9.3
(-6.3 to 24.9)
0.244
9.2
(0.04 to 18.3)
0.049
-5.5
(-11.2 to 0.3) 0.065
Sex, male Current smoking1, yes Diabetes, yes
(-3.7 to 6.2)
p 0.63
(-0.9 to 10.9) 0.096 (-0.1 to 0.1)
(-2.1 to 6)
0.89
0.34
Physical status (ASA2 class) II Mild systemic disease III Severe systemic disease Fracture classification, Weber B
22
C
1.1 (-15.4 to 17.6)
0.90
7.7
(-1.6 to 16.9)
0.106
-3.7
(-9.6 to 2.3)
0.23
Fracture classification, modified Bimalleolar
-3.9
(-10.1 to 2.5)
0.193
-2.7
(-6.1 to 0.7)
0.123
1.0
(-1.1 to 3.1)
0.35
Trimalleolar
-2.6
(-9.3 to 5.1)
0.46
-0.4
(-4.4 to 3.6)
0.85
1.0
(-1.6 to 3.6)
0.45
-1.8
(-2.9 to -0.7)
0.001
-0.8
(-1.4 to -0.3)
0.004
0.5
(0.1 to 0.9) 0.008
Duration of surgery, per 15 minutes 1
Patients with unknown smoking status are excluded
2
American Society of Anesthesiologists
OMAS=Olerud and Molander Ankle Score, LEFS=Lower Extremity Functional Scale, SEFAS=Self-Reported Foot & Ankle Questionnaire CI, confidence interval
23
24
S1268-7731(16)30450-7 http://dx.doi.org/doi:10.1016/j.fas.2016.10.002 FAS 968
To appear in:
Foot and Ankle Surgery
Received date: Revised date: Accepted date:
30-6-2016 5-10-2016 16-10-2016
Please cite this article as: Naumann Markus G, Sigurdsen Ulf, Utv˚ag Stein Erik, Stavem Knut.Functional outcomes following surgical-site infections after operative fixation of closed ankle fractures.Foot and Ankle Surgery http://dx.doi.org/10.1016/j.fas.2016.10.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. 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.
Functional outcomes following surgical-site infections after operative fixation of closed ankle fractures
Markus G Naumann, MD1 Ulf Sigurdsen, MD, PhD2 Stein Erik Utvåg, MD, PhD2,3 Knut Stavem, MD, MPH, PhD3,4,5
1
Department of Orthopaedics, Østfold Hospital, Norway
2
Department of Orthopaedics, Akershus University Hospital, Norway
3
Institute of Clinical Medicine, University of Oslo, Norway
4
Department of Pulmonary Medicine, Medical Division, Akershus University Hospital,
Norway 5
Health Services Research Unit, Akershus University Hospital, Norway
Corresponding author: Markus G Naumann, Department of Orthopaedics, Østfold Hospital, Postboks 300, 1714 Grålum, Norway Email: [email protected] Tel.: +47-47263913 1
Highlights
The study assessed functional outcomes 3 to 6 years after ankle surgery
Computerized charts were reviewed to identify superficial and deep infections (SSI)
Superficial and deep SSIs occurring within 6 months of surgery were analysed
A deep SSI was associated with worse functional outcomes on three different scales
2
Functional outcomes following surgical-site infections after operative fixation of closed ankle fractures
Abstract Background To compare the functional outcomes between patients with and without postoperative surgical-site infection (SSI) after surgical treatment in closed ankle fractures. Methods Retrospective cohort study with prospective follow-up. Of 1,011 treated patients, 959 were eligible for inclusion in a postal survey. Functional outcomes were assessed using three self-reported questionnaires. Results In total 567 patients responded a median of 4.3 years (range 2.7 to 6.2 years) after surgery. In total 29/567 had an SSI. The mean Olerud and Molander Ankle Score was 19.8 points lower for patients with a deep SSI (p=0.02), the Lower Extremity Functional Scale score was 10.2 points lower (p<0.01) and the Self-Reported Foot & Ankle Questionnaire score was 5.0 points higher (p=0.10) than for those without an SSI, after adjusting for age, sex, smoking status, diabetes, physical status, fracture classification and duration of surgery. Conclusions Patients with a deep SSI had worse long-term functional outcomes than those without an SSI.
Keywords Surgical site infection Closed ankle fracture ORIF Functional outcome Questionnaire OMAS
3
LEFS SEFAS
4
1. Introduction Ankle fractures are common injuries that constitute approximately 9% of all fractures, with an estimated incidence of 101–108 per 100,000 inhabitants per year [1,2]. About 50% of ankle fractures require surgical stabilization with open reduction and internal fixation (ORIF) [2,3]. Surgical-site infections (SSIs) in closed ankle fractures treated by ORIF are common, reportedly afflicting from 1.4% to 9.8% of patients [4-9]. The influence of postoperative infections on the functional outcomes in patients with closed ankle fractures treated by ORIF has received little attention. In a case series of Weber type-B ankle fractures, the functional outcome scores were lower for patients with infectious complications than for those without infections [10]. A recent case–control study found that the self-reported functional outcome scores were lower for patients with postoperative infections following ORIF in ankle fractures than in age- and gender-matched patients without infectious complications [11]. However, both of these studies included only a small number of patients in the analysis of functional outcomes and did not use multivariable analysis [10,11] which means that the results may have been influenced by other differences between the comparison groups. The objective of the present study was to determine whether patients with an SSI have lower self-reported outcome scores than those without infection following ORIF in closed ankle fractures, adjusting for possible confounding variables. The study involved a crosssectional survey of a large retrospective cohort of patients with fractures of the ankle in two Norwegian hospitals.
5
2. Material and methods 2.1. Subjects and study design This was a retrospective cohort study of patients who received surgical treatment (ORIF) for unstable and closed ankle fractures at two Norwegian hospitals, Østfold Hospital and Akershus University Hospital. These hospitals have a combined geographical catchment area of about 730,000 inhabitants, and all patients 18 years of age living in the catchment area who were treated for unstable and closed ankle fractures by ORIF between January 1, 2009 and December 31, 2011 were eligible for inclusion in the study. Patients were selected from the information systems of the hospitals using discharge diagnoses (10th revision of the International Classification of Diseases: codes S82.3–S82.9, S93.2 and S93.4)[12] combined with surgical procedure codes (Nordic Medico-Statistical Committee Classification of Surgical Procedures: codes NHJ00–NHJ98 and NHE 99) [13]. In total, 1,149 patients were eligible for chart review. We excluded 128 patients living outside the hospitals’ catchment area or who were misclassified and 62 patients, who were unable to respond to questionnaires because they had cognitive problems, could not use the other leg for comparison, had moved out of the area or had died. Details of the exclusions are shown in Fig. 1. After exclusions, 959 patients were eligible for inclusion in a postal survey. We mailed a questionnaire to the participants in January 2015, and 4 weeks later we sent a reminder to the non-respondents. The questionnaire included the Olerud and Molander Ankle Score (OMAS), the Lower Extremity Functional Scale (LEFS) and the Self-reported Foot & Ankle Questionnaire (SEFAS) and items about demographics. In total, 567 patients (59.1% of those eligible) completed the questionnaire, 345 patients did not respond and 47 questionnaires were returned unopened due to incorrect addresses (Fig. 1).
6
The study was approved by the Norwegian Social Science Data Services (approval no. 28813/5) and the Regional Committees for Medical and Health Research Ethics, Health Region South East (approval no. 2012/384).
2.2. Variables and classifications 2.2.1. Medical record review and variables All electronic medical records and radiographs were reviewed by one of the authors (M.G.N. or U.S.) to verify the recorded diagnosis and procedures and to collect information on demographics (age at trauma and sex), physical status before surgery [American Society of Anesthesiologists (ASA) class I–III: I, completely healthy fit; II, mild systemic disease; and III, severe systemic disease] [14], diabetes (yes or no), current smoking status (yes, no or unknown), fracture classification (see below), treating hospital and whether surgery was performed within 8 hours of trauma. Finally, we recorded the number of in-hospital days, preoperative antibiotics given (yes or no), insertion of one or more syndesmosis screws (yes or no), and the duration of surgery (in minutes). 2.2.2. Fracture treatment and classification The patients in both hospitals were treated according to the recommendations of the Swiss Arbeitsgemeinschaft für Osteosynthesefragen (AO) and the American Orthopaedic Trauma Association (OTA). The radiographs of the patients were classified for descriptive purposes using the Weber classification and into uni-, bi- and trimalleolar fractures [15]. 2.2.3. Surgical site infections We classified SSIs as superficial or deep infectious complications occurring within 6 months after the day of ankle surgery. More specifically, superficial infections were defined as minor wound complications that could be treated conservatively without surgical intervention while deep infections were defined as major wound complications and needing surgical treatment. 7
2.2.4. Assessment of functional outcomes The subjects completed three different questionnaires to assess functional outcomes, as described below.
Olerud and Molander Ankle Score The OMAS was designed to assess symptoms and function after ankle fractures. It consists of items that are scored in the following domains with ordinal scales: pain (0–25), stiffness (0– 10), swelling (0–10), stair climbing (0–10), running (0–5), jumping (0–5), squatting (0–5), supports (0–10) and work/activity level (0–20). The item scores are summed to produce a total score ranging from 0 (totally impaired) to 100 (completely unimpaired). Each item is scored so as to represent the degree of disability. The total score can be categorized as poor (0–30), fair (31–60), good (61–90) or excellent (91–100) [16]. The OMAS has documented reliability, validity and responsiveness in studies of ankle fractures [17].
Lower Extremity Functional Scale The LEFS comprises 20 items related to the ability to perform everyday activities that are scored on the following scale: extreme difficulty or unable to perform activity (0), severe difficulty (1), moderate difficulty (2), minor difficulty (3) and no difficulty (4). The items are summed to produce a total score ranging from 0 (very poor function) to 80 (very good function) [18]. The reliability, construct validity and responsiveness of the LEFS have been documented in people with ankle sprains and a general population with lower-extremity musculoskeletal dysfunction [19,20]. The smallest detectable change is 9 scale points, which is also the smallest clinically important difference [18].
Self-reported Foot & Ankle Questionnaire 8
The SEFAS is a slightly modified version of the Oxford-12 questionnaire for total hip replacement [21]. Each of the 12 questions was scored on an ordinal scale from 1 to 5, with the scores summed to produce a total score ranging from 12 (normal function) to 60 (most severe disability)[22]. The SEFAS was developed in patients undergoing total ankle replacements and has been validated in patients with disorders of the toe, ankle or hindfoot [23].
2.3. Statistical analysis The characteristics of the patients, their fractures and their surgery are presented as mean (range), median (interquartile range) or number (%) values, as appropriate. Descriptive variables for respondents and non-respondents and for subjects with and without SSIs were compared using the t-test (for normally distributed data) or Mann-Whitney U test (for nonnormally distributed data) for continuous variables, or Fisher’s exact test for categorical variables. The association of infection status with self-reported outcomes (OMAS and scores on the LEFS and SEFAS) were analysed using multivariable linear regression analysis. We assessed the effect of infection using two dummy variables for superficial and deep infection, respectively. In multivariable models, we adjusted for the following covariates: age, sex, current smoking status (yes vs. no, subjects with unknown smoking status were excluded), diabetes (yes vs. no), ASA class, fracture classification (Weber), fracture classification (uni-, bi- or trimalleolar fracture) and duration of surgery. We did not impute missing values before performing the modelling. In the regression models, the residuals showed some deviation from normal distributions. Log-transformation of the dependent variable did not materially improve this situation, and such a transformation would have also made the results more difficult to 9
interpret. We therefore used the untransformed values for the dependent variable, but used bootstrapped 95% confidence intervals, with 1000 replications, in all models. The threshold for statistical significance was set at p<0.05 in two-sided tests. All statistical analyses were conducted using the Stata software (version 14.1, Stata Corporation, College Station, TX, USA).
3. Results 3.1. Sample and respondents In total, 567 of 959 patients (59.1%) responded to the questionnaire. The median time between surgery and completion of the questionnaire was 4.3 years (interquartile range 3.9 to 5.1 years, range 2.7 to 6.2 years).Respondents were older than non-respondents with a mean age of 53.2 (SD15.1) years and 46.2 (17.5) years, respectively (p<0.001), were more likely to be current non-smokers (75% vs. 61%, p<0.001), and to have had surgery within 8 hours (33% vs. 27%, p=0.039). There were no differences between respondents and nonrespondents in sex, diabetes and fracture characteristics according to the uni-, bi-, trimalleolar and Weber classifications. The infection rate was 5.1% (29/567) for respondents and 5.1% (20/392) for non-respondents (p=0.56). Patients with an SSI were older, than those without an SSI. The fracture classifications, ASA class and length of stay did not differ between those with and without SSIs (Table 1).
3.2. Functional outcome scores In bivariate comparisons of functional outcome scores, patients without an infection had a higher OMAS and LEFS score and a lower score on the SEFAS than those with superficial or
10
deep infection, which indicates that the functional outcomes were better for those without an SSI on all scales (Table 2). In multivariable analysis after adjusting for several variables, patients with a deep SSI had a lower OMAS score (p=0.017) and LEFS score (p=0.009) than those without deep SSI (Table 3), indicating a worse functional outcome. The patients with a deep SSI scored higher on the SEFAS (indicating a worse outcome) than those without, but this difference was not statistically significant (p=0.096). Those with superficial SSI had a slightly worse, although statistically non-significant, functional outcome than those without infection on the OMAS and SEFAS scales (Table 3). Current smoking, ASA class II and III and longer duration of surgery were associated with worse functional outcomes on the OMAS, LEFS and SEFAS. (Table 3)
4. Discussion The main finding in the present study was that the functional outcomes 3 to 6 years after surgery for closed ankle fractures were worse in those with a deep SSI than in those without an SSI. This finding was consistent and remained statistically significant after adjusting for several background variables and possible confounders. Relative to the previous studies, the present study surveyed patients in a historical cohort, had a larger number of respondents to the questionnaires, had a longer duration between surgery and follow-up, and applied multivariable analysis. We also used three distinct and validated questionnaires: the OMAS, SEFAS and LEFS. Our findings regarding the overall infection rate were consistent with those of previous studies, [4-9] though some previous studies also included patients with open fractures or polytrauma [6,9]. This finding supports previous studies that used different study designs, outcome measures and analytic approaches [4,10,11]. Høiness et al. reported lower subjective 11
functional scores on the OMAS for patients with soft-tissue injuries compared to patients without, though details for the scores were not reported [4]. In a case-series bivariate analysis, Schepers et al. found that the functional outcomes of Weber type-B ankle fractures on the OMAS and AOFAS (American Orthopaedic Foot & Ankle Society) scale were worse in patients with infectious complications than in those without infections [10]. In contrast, Korim et al. used a case–control design and showed that the OMAS at least 6 months after surgery was lower following ORIF in patients with ankle fractures and postoperative infections than in age- and gender-matched patients without infectious complications [11]. However, that study included some patients with open fractures, in contrast to the present study. The association between superficial SSI and functional outcome was smaller than for deep SSI. A superficial infection would be expected to be milder and of shorter duration than a deep infection, and in need of no surgical treatment. Hence, it seems reasonable that superficial infections have a smaller impact on functional outcome than deep infections. However, the number of infections in the present study was small, and the lack of statistical significance for the impact of superficial infection may possibly be related to the limited statistical power of the study. Current smoking, longer duration of surgery and ASA class II and III were associated with worse long-term functional outcomes after ORIF as assessed with the OMAS, SEFAS and LEFS in this study. The association of current smoking with worse functional outcomes in the present study supports the findings in a previous study that used a modified version of the ACFAS (American College of Foot and Ankle Surgeons) scoring scale [24]. A longer duration of surgery was associated with worse long-term functional outcomes in this cohort. We are not aware of any studies that have investigated the association between the duration of surgery for ankle fractures and long-term functional
12
outcomes. Patients with more complicated fractures, greater comorbidity or who are operated on by less experienced surgeons may experience a longer duration of surgery and therefore may be at risk of worse functional outcomes. The present study controlled for some of these variables, but other influencing variables may also exist, and hence residual confounding may have been present. Finally, some important variables might not have been available for this retrospective study, such as functional status before surgery or more detailed information on comorbidity. Patients with greater comorbidity (i.e., in ASA class II or III) showed worse functional outcomes both on OMAS, LEFS and SEFAS. This pattern of association between ASA class and functional outcomes is in line with that reported 1 year after surgical treatment for ankle fractures using two other questionnaires [25]. The present study was large and was conducted in hospitals covering a geographical area that comprises about 14% of the Norwegian population. The rate of emigration from this area is low, and so few of the patients would have been followed up later in hospitals outside the area. We consider that the response rate to the questionnaires was acceptable and at the level that can be expected for this type of study. Moreover, there were few differences between respondents and non-respondents. Therefore, the results should be representative of the Norwegian setting, where ankle fractures are typically treated according to recommendations of the AO/OTA, as in many other Western countries. The three questionnaires used in the study are widely used, and the present findings were generally consistent across all three instruments. This study was subject to several limitations. The population was identified retrospectively, and variables were collected by a review of electronic medical records, which limits the number, quality and completeness of variables that can be collected. Therefore, some potentially relevant variables might not have been included. SSI was defined using
13
established clinical criteria rather than being confirmed with bacterial cultures. The chart and radiograph reviews were performed by only one researcher, and the interrater reliability and validity for the data extracted from the medical records were not assessed. Covariates also could not be updated throughout the study, in contrast to what might be possible in a prospective study. Time-dependent covariates could therefore not be included in the analysis. Patients with an SSI had worse self-reported functional outcomes at 3–6 years after ORIF in closed ankle fracture than those without an SSI, and hence general measures to reduce the prevalence of SSIs may lead to an improved outcome in this population [26]. Some of the risk factors associated with poor functional outcomes, such as smoking and obesity, are modifiable and therefore may be influenced by public health interventions in the society or individual counselling. Applying such interventions immediately before surgery may have positive impacts on wound healing and infection rate, and may also lead to a better general condition and better functioning that may be reflected in better scores for the self-reported functional outcomes. As this study was a cross-sectional follow-up study, one should be careful with statements about causal associations between infection and functional outcome after about 4 years. Infection and concomitant inflammation may inhibit the healing process or callus formation, and thus lead to suboptimal fracture healing and long-term pain or swelling. Also it is possible that those with infection had prolonged immobilization of the leg, which may have contributed to prolonged stiffness and worse long-term functional outcome. Finally, there may still be confounding from unavailable variables. We speculate that better surgical skills or the use of enhanced surgical techniques may contribute to shortening the duration of surgery and improve long-term outcomes. However, this needs to be assessed in future prospective studies.
14
In conclusion, this survey of patients in a historical cohort study found that patients with a deep SSI that occurred within 6 months following ORIF in closed ankle fractures reported worse functional outcomes on the OMAS, LEFS and SEFAS at a median of 4.3 years after surgery. This finding remained statistically significant after adjusting for several background variables and potential confounders. The study also found that current smoking, longer duration of surgery and ASA class II and II were associated with worse long-term functional outcomes.
Acknowledgements The project was partially funded by The Sophies Minde Foundation and Østfold Hospital. The sponsors had no involvement in study planning, collection, analysis, or interpretation of the data, or in the preparation, or approval of the manuscript
References [1] Court-Brown CM, Caesar B. Epidemiology of adult fractures: A review. Injury 2006;37:691-7. [2] Jensen SL, Andresen BK, Mencke S, Nielsen PT. Epidemiology of ankle fractures. A prospective population-based study of 212 cases in Aalborg, Denmark. Acta Orthop Scand 1998;69:48-50. [3] Sanders DW, Tieszer C, Corbett B. Operative versus nonoperative treatment of unstable lateral malleolar fractures: a randomized multicenter trial. J Orthop Trauma 2012;26:129-34. [4] Høiness P, Engebretsen L, Strømsøe K. The influence of perioperative soft tissue complications on the clinical outcome in surgically treated ankle fractures. Foot Ankle Int 2001;22:642-8.
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[5] Høiness P, Engebretsen L, Strømsøe K. Soft tissue problems in ankle fractures treated surgically. A prospective study of 154 consecutive closed ankle fractures. Injury 2003;34:92831. [6] Miller AG, Margules A, Raikin SM. Risk factors for wound complications after ankle fracture surgery. J Bone Joint Surg Am 2012;94:2047-52. [7] Ovaska MT, Makinen TJ, Madanat R, Vahlberg T, Hirvensalo E, Lindahl J. Predictors of poor outcomes following deep infection after internal fixation of ankle fractures. Injury 2013;44:1002-6. [8] Singh RA, Trickett R, Hodgson P. Early versus late surgery for closed ankle fractures. J Orthop Surg (Hong Kong) 2015;23:341-4. [9] SooHoo NF, Krenek L, Eagan MJ, Gurbani B, Ko CY, Zingmond DS. Complication rates following open reduction and internal fixation of ankle fractures. J Bone Joint Surg Am 2009;91:1042-9. [10] Schepers T, De Vries MR, Van Lieshout EM, Van der Elst M. The timing of ankle fracture surgery and the effect on infectious complications; a case series and systematic review of the literature. Int Orthop 2013;37:489-94. [11] Korim MT, Payne R, Bhatia M. A case-control study of surgical site infection following operative fixation of fractures of the ankle in a large U.K. trauma unit. Bone Joint J 2014;96b:636-40. [12] WHO-ICD10. ICD-10 International Statistical Classification of Diseases and Related Health Problems 10th Revision, http://apps.who.int/classifications/icd10/browse/2015/en 2015 [accessed 23 June 2016]. [13] Nordic Medico-Statistical Committee (NOMESCO). NOMESCO Classification of Surgical Procedures (NCSP), version 1.16, http://www.nordclass.se/NCSP_1_16.pdf 2011 [accessed 23 June 2016].
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[14] American Society of Anesthesiologists. Physical Status Classification System, http://www.asahq.org/resources/clinical-information/asa-physical-status-classification-system 2014 [accessed 23 June 2016]. [15] Broos P, Bisschop A. A new and easy classification system for ankle fractures. Int Surg 1992;77:309-12. [16] Olerud C, Molander H. A scoring scale for symptom evaluation after ankle fracture. Arch Orthop Trauma Surg 1984;103:190-4. [17] Nilsson GM, Eneroth M, Ekdahl CS. The Swedish version of OMAS is a reliable and valid outcome measure for patients with ankle fractures. BMC Musculoskelet Disord 2013;14:109. [18] Binkley JM, Stratford PW, Lott SA, Riddle DL. The Lower Extremity Functional Scale (LEFS): scale development, measurement properties, and clinical application. North American Orthopaedic Rehabilitation Research Network. Phys Ther 1999;79:371-83. [19] Lin CW, Moseley AM, Refshauge KM, Bundy AC. The lower extremity functional scale has good clinimetric properties in people with ankle fracture. Phys Ther 2009;89:580-8. [20] Alcock GK, Stratford PW. Validation of the Lower Extremity Functional Scale on athletic subjects with ankle sprains. Physiotherapy Canada 2002;54:233-40. [21] Dawson J, Fitzpatrick R, Carr A, Murray D. Questionnaire on the perceptions of patients about total hip replacement. J Bone Joint Surg Br 1996;78:185-90. [22] Hosman AH, Mason RB, Hobbs T, Rothwell AG. A New Zealand national joint registry review of 202 total ankle replacements followed for up to 6 years. Acta Orthop 2007;78:58491. [23] Coster MC, Rosengren BE, Bremander A, Brudin L, Karlsson MK. Comparison of the Self-reported Foot and Ankle Score (SEFAS) and the American Orthopedic Foot and Ankle Society Score (AOFAS). Foot Ankle Int 2014;35:1031-6.
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[24] Still GP, Atwood TC. Operative outcome of 41 ankle fractures: a retrospective analysis. J Foot Ankle Surg 2009;48:330-9. [25] Egol KA, Tejwani NC, Walsh MG, Capla EL, Koval KJ. Predictors of short-term functional outcome following ankle fracture surgery. J Bone Joint Surg Am 2006;88:974-9. [26] APIC Association for Professionals in Infection Control and Epidemiology. Guide to the elimination of orthopedic surgery surgical site infections, http://www.apic.org/Resource_/EliminationGuideForm/34e03612-d1e6-4214-a76be532c6fc3898/File/APIC-Ortho-Guide.pdf 2010 [accessed 23 June 2016].
Figure legend Figure 1. Flow chart of the study
18
Tables Table 1. Respondent characteristics at admission and injury data. Data are number (%) values except where stated otherwise (n=567)
No infection Infection (n=29)
p (n=538)
61.0 (26.8 to Age, years, mean (range)
52.8 (18.1 to 85.7)
0.005***
302 (56)
0.19*
86.2) Sex, female
20 (69)
Treating hospital
0.52*
Akershus University Hospital
14 (48)
252 (47)
Østfold Hospital
15 (52)
286 (53)
Physical status, ASA class
0.098**
I Completely healthy fit
8 (28)
189 (35)
II Mild systemic disease
17 (59)
323 (60)
4 (14)
26 (5)
2 (7)
32 (6)
0.69*
10 (35)
126 (23)
0.22**
III Severe systemic disease Diabetes Current smoking Fractures, clinical features
0.76**
Lateral malleolus
10 (35)
231 (43)
Bimalleolar
8 (28)
120 (22)
Trimalleolar
8 (2)
130 (24)
Maisonneuve
2 (7)
44 (8)
Isolated syndesmosis rupture
0 (0)
7 (1)
Medial malleolus
1 (3)
6 (1)
19
Modified fracture classification1 (n=560)
0.69**
Unimalleolar
13 (45)
281 (52)
Bimalleolar
8 (28)
120 (22)
Trimalleolar
8 (28)
130 (24)
Fracture classification2 (n=554)
0.33**
A
2 (7)
13 (3)
B
21 (72)
362 (69)
C
6 (21)
150 (29)
Syndesmosis screw, one or two
16 (55)
271 (50)
0.70*
Preoperative antibiotics (n=566)
17 (59)
310 (58)
1.00*
5 (4 to 9)
5 (3 to 9)
0.22***
85 (60 to 117)
76 (53 to 106)
0.27***
Number of in-hospital days, median (IQR) Duration of surgery in minutes, median (IQR) *Fisher’s exact test, **Pearson chi-square test, ***Mann-Whitney U test, 1 Broos & Bisschop, 2
Weber
IQR=interquartile range, ASA=American Society of Anesthesiologists
20
Table 2. Functional outcomes and quality-of-life measurements in 567 patients following open reduction and internal fixation (ORIF) in closed ankle fractures
No surgical-site infection
Superficial infection
Deep infection
n
Median
IQR
n
Median
IQR
n
Median
IQR
p*
OMAS (range 0–100) ¹
437
80
60–100
11
75
50-90
14
48
25-85
0.001
LEFS (range 0–80) ¹
514
74
61–79
13
64
62-76
15
48
38-74
0.004
SEFAS (range 12–60) ²
521
18
13–26
13
19
16-30
15
29
16-38
0.060
*Kruskal-Wallis-Test ¹ higher score denotes better function, ² lower score denotes better function OMAS=Olerud and Molander Ankle Score, LEFS=Lower Extremity Functional Scale, SEFAS=Self-Reported Foot & Ankle Questionnaire IQR=interquartile range
21
Table 3 Functional outcomes at surveys performed at median of 4.3 years after ORIF in closed ankle fractures, multivariable linear regression analysis. OMAS (n=430)
LEFS (n=504)
SEFAS (n=511)
(range 0–100)
(range 0–80)
(range 12–60)
β Postoperative infection, superficial
95% CI
p
β
95% CI
p
β
95% CI
-5.7
(-21.9 to 7.3)
0.43
1.1
(-4.2 to 6.4)
0.68
1.2
Postoperative infection, deep
-19.8
(-35.2 to -4.1
0.017
-10.2
(-17.9 to -2.5)
0.009
5.0
Age, years
-0.02
(-0.2 to 0.1)
0.79
-0.2
(-0.3 to -0.1) <0.001
0.004
5.1
(0.2 to 10.0)
0.040
3.4
(0.6 to 6.3)
0.018
-1.4
(-3.2 to 0.4) 0.116
-6.00
(-11.5 to -0.2)
0.028
-4.5
(-7.7 to -1.2)
0.007
2.6
(0.6 to 4.6) 0.010
1.5
(-9.2 to 12.1)
0.79
-3.8
(-10.0 to 2.4)
0.23
2.0
-6.0
(-11.5 to -1.0)
0.018
-2.8
(-5.4 to -0.3)
0.029
2.6
(0.7 to 4.74) 0.006
-13.8
(-24.9 to -5.0)
0.003
-11.9
(-19.0 to -4.8)
0.001
6.0
(1.6 to 10.4) 0.008
9.3
(-6.3 to 24.9)
0.244
9.2
(0.04 to 18.3)
0.049
-5.5
(-11.2 to 0.3) 0.065
Sex, male Current smoking1, yes Diabetes, yes
(-3.7 to 6.2)
p 0.63
(-0.9 to 10.9) 0.096 (-0.1 to 0.1)
(-2.1 to 6)
0.89
0.34
Physical status (ASA2 class) II Mild systemic disease III Severe systemic disease Fracture classification, Weber B
22
C
1.1 (-15.4 to 17.6)
0.90
7.7
(-1.6 to 16.9)
0.106
-3.7
(-9.6 to 2.3)
0.23
Fracture classification, modified Bimalleolar
-3.9
(-10.1 to 2.5)
0.193
-2.7
(-6.1 to 0.7)
0.123
1.0
(-1.1 to 3.1)
0.35
Trimalleolar
-2.6
(-9.3 to 5.1)
0.46
-0.4
(-4.4 to 3.6)
0.85
1.0
(-1.6 to 3.6)
0.45
-1.8
(-2.9 to -0.7)
0.001
-0.8
(-1.4 to -0.3)
0.004
0.5
(0.1 to 0.9) 0.008
Duration of surgery, per 15 minutes 1
Patients with unknown smoking status are excluded
2
American Society of Anesthesiologists
OMAS=Olerud and Molander Ankle Score, LEFS=Lower Extremity Functional Scale, SEFAS=Self-Reported Foot & Ankle Questionnaire CI, confidence interval
23
24