RESEARCH ARTICLE


High Rates of Postoperative Wound Infection Following Elective Implant Removal



M Backes*, 1, 2, N.W.L Schep 1, J.S.K Luitse 1, J.C Goslings 1, T Schepers1
1 Trauma Unit, Department of Surgery, Academic Medical Center, University of Amsterdam, The Netherlands
2 Department of Surgery, St Lucas Andreas Hospital, Amsterdam, The Netherlands


Article Metrics

CrossRef Citations:
0
Total Statistics:

Full-Text HTML Views: 1186
Abstract HTML Views: 892
PDF Downloads: 246
Total Views/Downloads: 2324
Unique Statistics:

Full-Text HTML Views: 643
Abstract HTML Views: 514
PDF Downloads: 157
Total Views/Downloads: 1314



© Backes et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Trauma Unit, Department of Surgery, Academic Medical Center, University of Amsterdam, The Netherlands; Tel: 0031250661895; Fax: 0031205666569; E-mail: m.backes@amc.uva.nl


Abstract

Introduction :

Metal implants placed during fracture surgery are often removed for various reasons (i.e. pain, prominent material, patients request). The removal of implants is considered a ‘clean’ procedure and as low risk surgery. The incidence of wound infections following implant removal has received little attention in the literature. The aim of the current study was to assess the incidence and risk factors of postoperative wound infections (POWIs) following implant removal.

Material and Methods :

All consecutive adult patients in a Level 1 and Level 2 Trauma Center who had their implants removed during a 6.5 years period were included. Exclusion criteria were removal of implants because of an ongoing infection or fistula and removal followed by placement of new implants. Primary outcome measure was a POWI as defined by the US Centers for Disease Control and Prevention. Patient characteristics and peri-operative characteristics were collected from the medical charts.

Results :

A total of 452 patients were included (512 procedures). The overall POWI rate was 11.6% (10% superficial, 1.6% deep). A total of 403 procedures (78.7%) comprised of implant removal below the knee joint with a 12.2% POWI rate. A POWI following initial fracture treatment was associated with a higher rate of POWI following implant removal (p=0.012). A POWI occurred more often in younger patients (median age 36 versus 43 years; p=0.004).

Conclusion :

The overall incidence of postoperative wound infection was 11.6% with 10% superficial and 1.6% of deep infections in patients with elective implant removal. A risk factor for POWI following implant removal was a previous wound infection.

Keywords: Fracture surgery, implant removal, postoperative wound infection, POWI, risk factor.



INTRODUCTION

Implants are used to stabilize fractures and are often removed at a later stage for various reasons. Indications for implant removal mainly consist of pain, functional impairment, prominent material or at patients request [1]. Removal can result in pain relief, improvement in function and a high rate of patient satisfaction [2, 3]. Implant removal is a frequently performed procedure and it accounts for up to 29% of all elective surgery and 6.3% of orthopedic surgical interventions [4].

Antibiotic prophylaxis is administered prior to placement of implants in order to lower the rate of postoperative wound infection (POWI) [5]. However, it is not a common practice to administer antibiotic prophylaxis before implant removal. This is because, according to the Centers for Disease Control and Prevention classification of surgical wounds, implant removal is considered as a ‘clean’ procedure [6]. The effect of pre-operative antibiotics are disputed in clean wounds, as there is lack of evidence that they decrease the rate of POWI of 2% [6].

Remarkably, in contrast to literature on infectious complications following elective fracture surgery such as open reduction and internal fixation, there is a paucity in the literature on rates of POWI following implant removal (Table 1) [2, 7-13].

The aim of the current study was to assess the incidence of postoperative wound infection following elective implant removal in a Level 1 and Level 2 Trauma Center and to evaluate possible risk factors.

MATERIAL AND METHODS

We conducted a retrospective cohort study of all consecutive adult orthopedic trauma patients in two hospitals (Level 1 and Level 2 Trauma Center) who had their implants removed following fracture healing. The electronic hospital databases were searched from 2007 to 2012 for all procedures with implant removal using the appropriate surgical procedure coding reference. The start of the inclusion period coincided with the introduction of electronic medical charts.

We excluded patients with implant removal because of an ongoing infectious complication (persistent infection or chronic plate fistula) and patients with removal as part of a new procedure (e.g. non-union) from the analysis.

Patient-characteristics (gender, age, BMI, ASA-classification, type of fracture) and peri-operative characteristics (time interval from index procedure to implant removal, surgical experience (senior or resident), duration of surgery, administration of antibiotic prophylaxis and type of wound closure (subdivided into intra- and transcutaneous) were obtained from the electronic charts.

Patients were seen within four weeks postoperatively in the outpatient clinic where a wound inspection was performed. The primary outcome, POWI, was subdivided in superficial or deep by applying the criteria of the US Centers for Disease Control and Prevention [6]. A POWI was considered superficial if amendable for treatment with oral antibiotics and was considered as deep when treated with intravenous antibiotics or surgical wound debridement. Bacterial cultures were obtained postoperatively in the surgical ward or in the outpatient clinic and were recorded. They were collected on suspicion of a POWI (dry swab). The occurrence of wound dehiscence was documented, which was diagnosed by wound inspection or a negative culture.

Patient and peri-operative characteristics were compared between patients with and without POWI.

Statistical Analysis

Data were analyzed using Statistical Package for the Social Sciences (SPSS) version 17.0 (SPSS, Chicago, Illinois, USA). Normality of continuous data was tested by inspecting the frequency distributions (histograms). Descriptive analysis were performed to compare baseline characteristics between patients with and without POWI. For continuous data mean SD (parametric data) or medians and interquartile ranges (non-parametric data) were calculated. Differences between the two groups of patients with and without POWI were assessed using the Student’s T-test (parametric data) or the Mann-Whitney U-test (non-parametric data). Categorical data were compared using the Chi-square test. A p-value <0.05 was taken as the threshold of statistical significance.

RESULTS

A total of 452 patients with 512 procedures were included. Patient- and perioperative characteristics are presented in Table 2.

Ten percent of patients (N=51) suffered from a superficial POWI and 1.6% (N=8) from a deep POWI. Of these eight patients one patient was treated with intravenous (iv) antibiotics. Seven patients were treated with iv antibiotics and surgical debridement. One of these patients was treated with surgical debridement three times. Forty-one of 51 patients with superficial POWI were treated with oral antibiotics. A wound dehiscence occurred in 37 patients (7.2%).

In 51 patients (10.2%) iv antibiotic prophylaxis was administered prior to implant removal. Five of these patients (9.8%) developed a POWI, which were all superficial infections. Unfortunately, the reason for administration of antibiotic prophylaxis was not routinely documented.

Seventy-three procedures (14.3%) were performed in the upper extremity with four POWIs (5.5%) versus 439 procedures in the lower extremity (85.7%) with 55 POWIs (12.5%) (Fig. 1). Given the current number of patients surgery performed in the lower extremity was not significantly associated with an increased risk of POWI (p=0.151).

Fig. (1).

The number of implant removals per body part (left) and the corresponding number and rate of postoperative wound infections (right).


Table 1.

Current literature on implant removal and the incidence of postoperative wound infection.


Study (Year) N Patients N POWI (%)
Raahave (1976) [7] 269 7 (3.2)
Richards (1992) [8] 88 0 (0)
Sanderson (1992) [9] 188 27 (14.4)
Minkowitz (2007) [10] 60 0 (0)
Pot (2011) [11] 80 16 (20)
Wadia (2012) [12] 27 0 (0)
Williams (2012) [2] 69 2 (2.9)
Vos (2013) [13] 284 23 (8)

N; Number, POWI; postoperative wound infection.

Table 2.

Patient- and perioperative characteristics with statistical association on postoperative wound infections following implant removal.


N Implant Removal of 512 (%) N POWI (%) p-Value (Two-Sided)
PATIENT CHARACTERISTICS
Male (N)
Age in (years)
BMI
ASA-classification**
I
II
III
Diabetes Mellitus
POWI following index procedure
PERI-OPERATIVE CHARACTERISTICS
Weeks to implant removal
Resident performing procedure
Duration of surgery (minutes)
Antibiotic prophylaxis
Transcutaneous wound closure
  287 (56.1)
42 (31-54)*
25 (22-28)* 370 (72.3)
130 (25.4)
11 (2.1)
15 (2.9)
71 (13.9) 49 (25-78)*
299 (60.4)
40 (26-60)*
51 (13.6)
226 (69.1)
  41 (14.3)
36 (25-49)*
26 (22-30)* 43 (11.6)
14 (10.8)
1 (9.1)
1 (6.7)
15 (21.1) 53 (34-85)*
43 (14.4)
46 (30-72)*
5 (9.8)
34 (15)
  0.130
0.004
0.336
1.000   NA
0.014 0.280
0.551
0.070
0.911
0.868

N; Number, POWI; postoperative wound infection, NA; not available.

*Median with interquartile ranges.

** (Chi2) difference in between ASA I and II+III.

Fifteen of 71 patients (21.2%) with a POWI following the index procedure developed a POWI following implant removal versus 44 patients following 381 uncomplicated procedures (11.5%) (p=0.014). Cultures were taken in 10 of these 15 patients, of which half showed the same micro-organism; a Staphylococcus aureus.

A POWI occurred more often in younger patients with a median age of 36 against 43 without a POWI (p=0.004). No association was found with gender, BMI, ASA-classification, smoking, diabetes mellitus, duration to implant removal, surgical experience or type of wound closure (Table 2).

DISCUSSION

Rates of POWI following implant removal from the upper and lower extremity in the current studies were 5.5% and 12.5%, respectively. These rates are consistent with rates in a recent prospective study of 6% and 10% [13]. Other retrospective studies show POWI rates of 9.2% following syndesmotic screw removal and 19% following calcaneal implant removal [14, 15]. However, overall a lower POWI rate than 11.6% is reported in literature (Table 1).

The high rate in the current study might be the result of the relatively high number of lower extremity surgery (85.7%) compared to upper extremity surgery (14.3%). In the foot and ankle region the bones are more prominent due to the limited soft tissue coverage (as compared to other bones with extensive muscle coverage). For example, after plating of the fibula in ankle fractures the plates are removed in about 27-36% of patients and following a calcaneal fracture almost 50% of patients have their implant removed [11, 16-18].

Remarkably, when looking at POWI following elective orthopedic surgery lower rates (0-5.4%) are found compared to implant removal [5, 19-28]. This might be the result of the instant use, full range of motion and weight-bearing of a limb following implant removal compared to fracture surgery, when patients are asked to build up exercise. In addition, it is a secondary procedure through scar tissue.

Importantly, the occurrence of POWI following fracture surgery was associated with the occurrence of POWI following implant removal. This information might be of help to the clinician or patient in decision making on implant removal.

Our results show that relatively younger patients are more susceptible to a POWI. This could be a result of a higher level of activity or earlier motion of younger patients compared to older patients. Earlier motion is associated with an increased risk of wound infection [29].

Finallly, in 10.2% of patients antibiotic prophylaxis was administered preoperatively. This was most likely the result of the surgeon’s preference. This missing information is a drawback inherent to the retrospective character and the main limitation of the current study.

In conclusion, the incidence of POWI following implant removal in a Level 1 and Level 2 Trauma Center is 11.6%. Risk factors for POWI following implant removal are a previous infection after initial fracture management and younger age. The results of the current study will be used in a prospective study on the effects of antibiotic prophylaxis prior to implant removal on a POWI (www.clinicaltrials.gov).

CONFLICT OF INTEREST

The authors confirm that this article content has no conflict of interest.

ACKNOWLEDGEMENTS

Declared none.

COMPLIANCE WITH ETHICAL REQUIREMENTS

The current study was approved by the hospital review board and has therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.

References

[1] Vos DI, Verhofstad MH, Vroemen JP, et al. Clinical outcome of implant removal after fracture healing In: 2013.
[2] Williams AA, Witten DM, Duester R, Chou LB. The benefits of implant removal from the foot and ankle J Bone Joint Surg Am 2012; 94(14): 1316-20.
[3] Minkowitz RB, Bhadsavle S, Walsh M, Egol KA. Removal of painful orthopaedic implants after fracture union J Bone Joint Surg Am 2007; 89(9): 1906-12.
[4] Böstman O, Pihlajamäki H. Routine implant removal after fracture surgery: a potentially reducible consumer of hospital resources in trauma units J Trauma 1996; 41(5): 846-9.
[5] Boxma H, Broekhuizen T, Patka P, Oosting H. Randomised controlled trial of single-dose antibiotic prophylaxis in surgical treatment of closed fractures: the Dutch Trauma Trial Lancet 1996; 347(9009): 1133-7.
[6] Mangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR. Guideline for prevention of surgical site infection, 1999 Infect Control Hosp Epidemiol 1999; 20(4): 250-78.
[7] Raahave D. Postoperative wound infection after implant and removal of osteosynthetic material Acta Orthop Scand 1976; 47(1): 28-35.
[8] Richards RH, Palmer JD, Clarke NM. Observations on removal of metal implants Injury 1992; 23(1): 25-8.
[9] Sanderson PL, Ryan W, Turner PG. Complications of metalwork removal Injury 1992; 23(1): 29-30.
[10] Minkowitz RB, Bhadsavle S, Walsh M, Egol KA. Removal of painful orthopaedic implants after fracture union J Bone Joint Surg Am 2007; 89(9): 1906-12.
[11] Pot J, Van Wensen R, Olsman J. Hardware related pain and hardware removal after open reduction and internal fixation of ankle fractures Foot Ankle Online 2011; 4(5): 1-6.
[12] Wadia F, Sundar M. Metalwork removal in elective foot and ankle practice: does it make any difference to the patient? Foot 2012; 22(2): 74-6.
[13] Vos DI, Verhofstad MH, Hanson B, van der Graaf Y, van der Werken C. Clinical outcome of implant removal after fracture healing. Design of a prospective multicentre clinical cohort study BMC Musculoskelet Disord 2012; 13: 147.
[14] Backes M, Schep NW, Luitse JS, Goslings JC, Schepers T. Indications for implant removal following intra-articular calcaneal fractures and subsequent complications Foot Ankle Int 2013; 34(11): 1521-5.
[15] Schepers T, Van Lieshout EM, de Vries MR, Van der Elst M. Complications of syndesmotic screw removal Foot Ankle Int 2011; 32(11): 1040-4.
[16] Harvey EJ, Grujic L, Early JS, Benirschke SK, Sangeorzan BJ. Morbidity associated with ORIF of intra-articular calcaneus fractures using a lateral approach Foot Ankle Int 2001; 22(11): 868-73.
[17] Schepers T, Den Hartog D, Vogels LM, Van Lieshout EM. Extended lateral approach for intra-articular calcaneal fractures: an inverse relationship between surgeon experience and wound complications J Foot Ankle Surg 2013; 52(2): 167-71.
[18] Schepers T, Van Lieshout EM, De Vries MR, Van der Elst M. Increased rates of wound complications with locking plates in distal fibular fractures Injury 2011; 42(10): 1125-9.
[19] Pavel A, Smith RL, Ballard A, Larson IJ. Prophylactic antibiotics in elective orthopedic surgery: a prospective study of 1,591 cases South Med J 1977; 70(Suppl. 1): 50-5.
[20] Miller WA. Postoperative wound infection in foot and ankle surgery Foot Ankle 1983; 4(2): 102-4.
[21] Reyes C, Barnauskas S, Hetherington V. Retrospective assessment of antibiotic and tourniquet use in an ambulatory surgery center J Foot Ankle Surg 1997; 36(1): 55-62.
[22] Sticha RS, Swiriduk D, Wertheimer SJ. Prospective analysis of postoperative wound infections using an early exposure method of wound care J Foot Ankle Surg 1998; 37(4): 286-91.
[23] Zgonis T, Jolly GP, Garbalosa JC. The efficacy of prophylactic intravenous antibiotics in elective foot and ankle surgery J Foot Ankle Surg 2004; 43(2): 97-103.
[24] Dickemore C, Green R, Jolley W, Green D. Prophylactic antibiotics in clean forefoot surgery: Are they necessary?. USA: The Podiatry Institute 2005.
[25] Cichero MJ. Elective foot and ankle surgery; activity and perioperative complications in Queensland public hospitals, Australia Foot 2009; 19(3): 139-44.
[26] Maher AJ, Metcalfe SA. A report of UK experience in 917 cases of day care foot surgery using a validated outcome tool Foot 2009; 19(2): 101-6.
[27] Butterworth P, Gilheany MF, Tinley P. Postoperative infection rates in foot and ankle surgery: a clinical audit of Australian podiatric surgeons, January to December 2007 Aust Health Rev 2010; 34(2): 180-5.
[28] Wukich DK, Lowery NJ, McMillen RL, Frykberg RG. Postoperative infection rates in foot and ankle surgery: a comparison of patients with and without diabetes mellitus J Bone Joint Surg Am 2010; 92(2): 287-95.
[29] Thomas G, Whalley H, Modi C. Early mobilization of operatively fixed ankle fractures: a systematic review Foot Ankle Int 2009; 30(7): 666-74.