Postoperative Management of K-Wires in Percutaneous Foot Surgery

Citation: Ignacio AU (2021) Postoperative Management of K-Wires in Percutaneous Foot Surgery. Int J Foot Ankle 5:054. doi.org/10.23937/2643-3885/1710054 Accepted: May 08, 2021; Published: May 10, 2021 Copyright: © 2021 Ignacio AU. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Introduction
Introduced by Martin Kirschner, in 1909, Kirschner wires (K-wires) are extensively used in orthopedics in bone fixation procedures. They are reliable, easily acquired, and inexpensive [1,2].
The following variables were evaluated: Age, gender, AOFAS score, duration of K-wire stay, antibiotic prophylaxis, diagnosis (hallux valgus, hammer toe, overlapping fifth toe, tailor's bunion), previous conditions (hypertension, hypothyroidism, diabetes, hypercholesterolemia, breast cancer), pin extrusion, type of surgery (PIP arthrodesis, percutaneous osteotomy of the proximal phalanx of the fifth toe, Bosch plus Akin osteotomy, DMMO), post-operative management of the pin, K-wire location and complications.

Statistical analysis
For quantitative variables, a normality test was performed. If variables followed a normal distribution, mean and standard deviation were used as summary measures. In the event of not following a normal distribution, median and interquartile range were used instead.

Results
Based on the above considerations, the aim of this study was to determine the ideal postoperative management of K-wires to prevent complications associated with exposed temporary implants. Our hypothesis is that by cutting the pin at skin level and burying it in the subcutaneous tissue, postoperative comfort is improved without the risk of unwanted extrusion or infection.

Materials and Method
Between January 2017 and December 2018, 39 adult patients underwent transient K-fixation for the treatment of hallux valgus, hammer toe, overlapping fifth toe and/or tailor's bunion, totaling 70 procedures. All patients were treated by a single foot and ankle orthopedic surgeon. For overlapping fifth toe correction, Distal Metatarsal Minimal Invasive Osteotomy (DMMO) was performed and osteotomies were fixed with 1.5 mm K-wires, as in interphalangeal arthrodesis and tailor's bunion correction.
All pins were cut at skin level and buried in the subcutaneous tissue of the finger until completely hidden beneath the skin ( Figure 1).
Antibiotic therapy consisted of a single preoperative dose of IV cephalothin (1g) given 30 minutes prior to incision, followed by oral cephalexin (1g) every 12 hours for an additional 4 days.
After the first postoperative visit (24 hours following surgery), patients were allowed to shower and wet the surgical site, and were advised to clean the wound with regular soap and apply alcohol afterwards. A gauze dressing was applied on the wound for ambulation during the first 10 days. Immediate weight bearing was allowed on a postoperative shoe/sandal, limited by patient tolerance.
All patients underwent radiographic evaluation 24 hours after surgery, on the 21 st day upon K-wire removal, and 6, 12 and 18 months following surgery.
Seventy procedures in which K-wires were inserted percutaneously and buried beneath the skin were included in the study, its use being more frequent in hallux valgus correction (Graph 2). All 70 procedures were performed on an outpatient basis.
Patients were allowed to shower and wet the wound 24 hours after surgery, with a median antibiotic prophylaxis of 4 days.
All patients were clinically evaluated every 7 days until the 30-day postoperative period was completed. At this time point, the K-wire was removed in the operating room, under local anesthesia and without suturing the pin site. Subsequently, patients were evaluated in follow-up visits every 2 months until the first postoperative year was completed, as well as in a final visit 18 months after surgery.
Two of the patients in whom the Bosch technique was used for the treatment of hallux valgus deformity experienced pin extrusion (2.85%) with superficial infection (none had previous conditions). These patients were treated with oral antibiotics for 10 days and K-wire removal at 24 and 30 days, respectively.
The latter also experienced delayed union, with callus formation 4 months after surgery. There were no complications in the remaining 68 (97.14%) procedures.
In only one procedure (1.40%), in which the Bosch percutaneous technique for the treatment of hallux valgus deformity was used, a patient complained of discomfort caused by the K-wire in the postoperative period but stated that he would undergo a similar surgical technique in the future.
The AOFAS score at 18 months was 98.17.

Discussion
K-wires are extensively used for fracture, dislocation, osteotomy and arthrodesis fixation in foot surgery since they are easily available, reliable and inexpensive [1,8].
Complications when using this type of fixation include infection, pin loosening, pin migration, fatigue failure and loss of reduction [1,3]. Another drawback when using K-wires is that the protruding end causes soft tissue irritation, pain and discomfort.
Choosing the right pin diameter is vital to ensure sufficient bone stability and prevent potential implant breakage. Pichler, et al. reported K-wire breakage in only 14 cases [9]. Botte, et al. [3] reported an 18% complication rate, including pin loosening, pin tract infection and pin bending. Neurological complications (16.5%) have also been reported by Gosens, et al. [10]. In our study, no implant breakage, bending or neurological damage were observed.  There is no consensus on the cleaning method and frequency of the K-wire tip, or on how patients should shower. Some authors recommend not wetting the surgical site, others advise cleansing on a weekly basis while others suggest daily cleansing [12]. In our series, we allowed patients to shower 24 hours after surgery since there is no exposed end of the K-wire and the wound is cleaned with alcohol on a daily basis.
Botte, et al. [3] observed infections in 7% of patients, implant loosening in 4%, and osteomyelitis in 2%. In their series, Green, et al. [16] reported pin tract infections which required implant removal and fully resolved within 3 months of follow-up. In our study, 2 patients developed superficial infections (2.85%), which were Concern over the use of K-wires lies with their exposed end and the risk of infection; however, not all cases are susceptible to contamination of the pin entry point [11][12][13][14][15]. Risk factors include advanced age, diabetes, rheumatoid arthritis, collagen diseases, and chronic use of corticosteroids. Another factor which increases the risk of infection is duration of K-wire stay; the longer the implant is used, the higher the infection rate [12]. Gordon, et al. [12] suggested that periarticular fixation is associated with a higher infection rate than diaphyseal fixation (4.5% vs. 1.6%), possibly due to increased soft tissue movement over the joints. Thicker soft tissue areas on the bone and skin tension around the pin site have also been associated with higher infection rates [15].  treated with oral antibiotics. Although they resolved without the need of immediate implant removal, one of them experienced delayed union of the Bosch osteotomy, which resolved completely with bone healing within 4 months after surgery and no loss of alignment.
The AOFAS score obtained with our surgical technique was similar to that published in other publications [17,18].

Conclusion
The use of K-wiring as a fixation method is effective and inexpensive; however, there is no consensus on how to manipulate the implant free ends. The method described in our study is easily performed and does not require special equipment or supplies. Postoperative management of K-wires by burying the protruding end beneath the skin has good aesthetic and functional outcomes, causes less discomfort to the patient and does not increase the infection rate.

Highlights
• The use of K-wiring as a fixation method is effective and inexpensive.
• Our study reports new way to managefoot post-operative k-wires.
• Postoperative management of K-wires by burying the protruding end beneath the skin has good aesthetic and functional outcomes, causes less discomfort to the patient and does not increase the infection rate.