The utilisation of transcutaneous metal devices is common practice in orthopaedic practice, and with increasing involvement of plastic surgeons in hand trauma and combined management of lower limb injuries, many of these patients are managed for variable periods by plastic surgeons. Transcutaneous devices of various types are used on a short- or longer-term basis to stabilise fractures or to correct deformity. Kirschner wires, known as K-wires, are most commonly used on a short-term basis as a simple and cost-effective way to provide stability to small bone fractures [1]. The Hoffman external fixator or the Ilizarov circular frame, used for long bone fractures, may be applied for periods extending to several months with an increasing incidence with time. Essentially, a pin tract is a chronic wound containing a foreign body providing an ideal focus for bacterial colonisation. Although pin-tract infection is often not considered to be a serious complication in the short term, it has the potential to decrease the stability of the bone–pin interface, which can cause pin loosening, osteomyelitis and poor functional outcome [2, 3]. The problem has heretofore been widely reported in orthopaedic literature, but as pin-site infection impacts the care of plastic surgery patients also, it is important for plastic surgeons to understand the scale of the problem and strategies for prevention.

The aims of this study were:

  1. 1.

    To record the incidence of pin-site infection in a Plastic Surgery department in comparison with published reports;

  2. 2.

    To review literature on comparative trials of pin site management to determine from the literature what method of wound care best prevents pin-site infection;

  3. 3.

    To establish current nursing practices in pin-site care and patient-initiated practices;

  4. 4.

    To determine the need for more innovative technology in prevention.

Methods

A prospective, cohort study was conducted on patients presenting to the Plastic Surgery ward or clinic with any type of transcutaneous metal device. Patients presenting between November 1, 2010 and February 1, 2011 were included. Episodes of subjective or objective complications were recorded. Objective data comprised of demographic information, the reason for the transcutaneous metal insertion, details of the type of fixator used, any reported complication, the results of microbiology swabs sent to the laboratory, antibiotic use and relevant radiological findings. Infection was defined by clinical symptoms such as redness, pain, prolonged discharge and functional loss. Subjective data were obtained by interviewing the patient, asking about skin problems, discharge, functional loss associated with the metal device and any discomfort (Figs. 1, 2, 3, 4, 5).

Fig. 1
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K-wiring of the little finger

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Fig. 2
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Hoffman external fixator

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Fig. 3
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Insertion of external fixator pins

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Fig. 4
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Pennig orthofix

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Fig. 5
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Infected threaded pin

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Results

Thirty-five consecutive patients with transcutaneous metal devices were seen in our specialised outpatient clinic from November 1, 2010 to February 1, 2011. Of these, 25 individuals were suitable for inclusion in the study. Seven patients were excluded as their K-wires were buried, and three were not compliant with follow-up. Of the 25 cases, 9 patients had an external fixator (51 pin sites) and 16 had K-wires (27 pin sites) in situ. In Table 1, you find the patients’ characteristics and recorded complications. The duration of treatment varied between 14 and 78 days for K-wires and between 21 and 78 days for external fixators. The duration of follow-up varied between 7 and 89 days.

Table 1 Characteristics and recorded complications of patients with transcutaneous metal devices seen between November 1, 2010 and February 1, 2011
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Of the 25 patients with transcutaneous metal devices, nine developed complications (36%). In three cases, slight migration of K-wires occurred (12%). Six patients suffered from pin-tract infection (24%, with a 95% confidence interval (CI) of 12% to 43%). In three patients, the swab taken from the pin site was positive for Staphylococcus aureus. The external fixator had to be prematurely removed from one patient due to an infection. This patient developed recurrent infections at the site of his previous pin tracts even after pin removal. Of the patients surveyed, 80% had not been provided with instructions on wound management. Only one of the patients had the benefit of a district nurse assessment with pin-site care. The patients did not receive instructions on either washing the pin sites or on cleaning them.

In our study, we found that pin-site care was not consistent. Mostly, the pins were cleaned daily with normal saline and a new dressing was applied. The pin sites were not washed. In some cases, betadine or chloramphenicol 1% ointment was applied to the pin sites.

In our study, there was no standard protocol on the prescription of antibiotics in patients with transcutaneous metal. Fifty percent received a preoperative antibiotic dose. Others received a single dose or multiple postoperative doses of co-amoxiclav or flucloxacillin.

Discussion

Our data show six infections from 25 patients, which is 24%, with a 95% CI of 12% to 43%. Thus, the true infection rate in the whole patient population is between 12% and 43%.

Our key limitation is the small number of patients. We calculated that if we would have entered more patients, or if we would repeat the study, we could expect an infection rate in the same range (for 95 out of 100 projects). Assuming the same infection rate of 24%, with 12 infections from 50 patients, the 95% CI is 14% to 37%, and with 24 infections from 100 patients, the 95% CI is 17% to 33%. As these numbers would not have made a great difference, we decided to keep our number of patients to 25.

The reported rate of pin-tract infection in the literature is high, ranging from 4.5% to 71%. Although diagnostic criteria vary (Santy [20]), and this may be a factor in the wide range of these quoted figures, certain factors however seem to be important. In Table 2, you find the reported infection rates in the literature, with the prevention and management measures listed. Table 3 explains the several classification systems which are used to diagnose a pin-tract infection.

Table 2 Reported infection rates in the literature; diagnosis, prevention and management of pin-tract infection
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Table 3 Different classification systems of pin-tract infection
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K-wires and external fixators in the hand and wrist

In a retrospective study by Stahl and Schwartz [1], which considers the use of K-wires in wrists, the authors reported an infection rate of 5.5%; 13 out of 236 patients developed infection around the pin. Margic [4] observed 100 patients in a prospective study of small external fixators used on metacarpal and phalangeal fractures, and found an infection rate of 7%. Studies on external fixator use for fractures of the distal radius report a higher recurrent infection rate of between 10.1% and 43% [5, 9, 10]. Egol et al. [6] performed a randomized controlled trial on such fixators and recorded an infection rate of 10.1%.

The role of skin movement

Hove et al. [7], who investigated the differences between static and dynamic fixation of the wrist, found that 15 of their patients (43%) in the dynamic fixator group and 4 (11%) of the static group had a superficial pin-tract infection (p < 0.01). They attributed this difference to the motion allowed by the dynamic fixator which seemed to increase skin irritation around the wrist.

Fixators applied to the elbow must also contend with motion. Cheung et al. [8] looked at the hinged external fixator .The pin-tract infection rate was found to be 25%.

External fixators in areas prone to infection

The pelvic external fixator is another device associated with a high rate of infection; Mason et al. [9] reported a complication rate of 62% for definitive pelvic fixators (mean duration of treatment is 60 days) and an infection rate of 21% for temporary fixators (mean duration of treatment is 8 days). This resulted in the premature removal of seven devices, the reinsertion of one pin and the drainage of two abscesses.

Lower limb external fixator devices

The lower limb is an area where wound healing is notoriously difficult.

Blasier et al. [10] investigated 132 children with fractures of the femur who were treated with external fixators. They found an infection rate of 40.5%; a rate of superficial infection of 36% and a rate of 4.5% for cases requiring intravenous antibiotics. Sims and Saleh [11] reported a higher pin-tract infection rate of 86% associated with external fixation of the femur. These authors related the high infection rate to the bulk of tissue in the upper leg and its associated movement.

External fixation devices for tibial shaft fractures have been widely investigated. The Ilizarov circular, external frame is one of the transcutaneous devices often used to treat tibial fractures. The pin-tract infection rate varies from 36% to 54.2% [12, 13]

Pin-site wound care

Lethaby et al. showed in 2008, in a systemic review, that there is insufficient evidence available on any one best way to care for pin sites [14]. Recently, the Russian Protocol of pin-site care has become more popular. This Russian Protocol was developed by the “Ilizarov Scientific Centre” for Restorative Orthopaedics in Russia. The system advises non-touch techniques when using the wires and pins, the utilisation of pulsed drilling, the removal of bone swarf and immediate coverage of the pin-site with dressings soaked in Chlorhexidine 1% ointment. The pins should be cleaned daily for 3 days with 70% alcohol, after which an occlusive dressing should be applied. This ritual is repeated every 7 days while the transcutaneous metal device is in place. Davies et al. [15] showed that infection rates are higher by 37% in cases where the Russian Protocol is not utilised (p < 0.001). The Cochrane review dismissed the findings of Davies et al. as it questioned their methods of randomizing their sample, even though, Timms and Pugh [16] advocate the following of this prescription.

Grant et al. [17] concluded that there is a role for the application of a bactericidal solution, such as 10% povidone–iodone solution, to the skin surrounding the pin sites. The problematic aspect of this treatment is the difficulty in securing an occlusive dressing.

The pin insertion technique

When inserting Ilizarov or K-wires, it has been shown that several important issues should be addressed to keep the infection rate down; adequate cooling during drilling is vital to prevent thermal damage, and (as recommended in the Russian Protocol) drilling should be conducted using the pulsed technique. The ends of transcutaneous wires should be bent to avoid migration [18] (in our study, three wires migrated; one of which had not been bent).

Pre-drilling was thought to be necessary for certain pins in certain bones, and unnecessary for other situations. If the pins have sharp-cutting trocar points, pre-drilling may be unnecessary. In a study by Hutchinson et al. [19], soft tissue inflammation around the pins was almost twice as common in pre-drilled pin sites, which could be attributable to the increased soft tissue trauma associated with two passages of the wire across the tract. It has been suggested that with the use of sharp trocar points, the skin does not need pre-incision, but the skin should be incised if tenting appears at the pin site, as otherwise a fluid reservoir could develop and attract bacteria [20].

Antibiotics

There is evidence that the presence of transcutaneous metal leads to the development of a biofilm between the skin and metal which allows bacterial growth. As transcutaneous metal is a foreign material, prophylactic antibiotics may be considered. Yet, according to W-Dahl and Toksvig-Larsen [21], antibiotics should be used as little as possible, and only those with a specific spectrum should be employed. These authors showed that prolonged antibiotic use has no benefit in eradicating infection. As you see in Table 2, good wound management and optimal insertion techniques do not eradicate this problem. The quickest answer to pin-site infection is often pin removal.

Technological solutions

Various technological solutions have been tried in the hope of preventing pin-tract infection. Coated pins create an extra defence barrier between the pin and bacteria. In a recent systematic review of the influence of hydroxyapatite coating on pin loosening and pin-tract infection by Saithna [22], he concluded that there was less loosening with coated pins, but unfortunately not less infection.

Titanium is frequently used in Dentistry and in Orthopaedics for intraoral or intraosseous prostheses. [23]. This material produces a reduced susceptibility to bacterial adhesion. In a study by Pieske et al. [24], titanium alloy pins were compared with stainless pins in 80 patients. There was no difference in the incidence of pin-tract infection. Masse et al. [25] found, in a randomized study, that silver pins resulted in a lower rate (30%) of positive microbiology cultures than uncoated pins (42%), but this difference was not statistically significant, and there was a raised serum silver in the patients with silver-coated pins. Much money is spent each year on improving technology, yet such attractive possibilities should not distract staff from executing the simple, basic but effective methods of wound and pin-site care.

Implications for practice

  1. 1.

    Our study found an infection rate of 24% associated with transcutaneous metal.

  2. 2.

    Plastic surgery departments need to develop clear protocols for prevention of pin-site infection, and randomized controlled trials are necessary to establish the best practice.

  3. 3.

    Patients need clearer instructions on how best to care for their pin sites.

  4. 4.

    There is a need to consider new technological solutions for this problem. Long-term implantation in dental practice has been established, but it is less successful in skin than oral mucosa.